Coding schemes for an erasure relay

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Shannon capacity[香浓定律]

1 1 I log 2 log 2 log 2 M P(x) 1/ M
(bit)
Channel Capacity and Entropy
For the discrete information source of unequal probability: If the information source consists of M symbols, and the symbol values x1 , x2, ..., xM appear with probabilities P(x1 ), P(x 2 ),..., P(x M ) ,then each symbol contains the amount of information :
Communication System
In the receiver the corresponding inverse operations are implemented:
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Modulation
Channel Decoding Source Decoding
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To the end , the channel encoder introduces redundancy into the information sequence u. This redundancy can be exploited by the channel decoder for error detection or error correction by estimating the transmitted symbol sequence û .
Communication System
The basic structure of a Digital Communication System is show which represents the architecture of the communication systems in use today.

基于网络编码的协作中继技术

２１０２年３月
计算机工程与设计
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第３３卷
第３期
Ｖｏ．３Ｎｏ３１３．
基于网络编码的协作中继技术
戴丽妮。，周婷，徐景。（．中国科学院上海微系统与信息技术研究所，上海２０５；２海无线通信研究中心，１０００．上上海２０３；３０３５．中国科学院无线传感网与通信重点实验室，上海２０５）０００
以提高网络的传输可靠性，而网络编码可以提高网络的吞吐量，将网络编码与协作中继相结合的传输模式可以进一
步提高网络的数据传输速率＿。８伽在现有的协作中继中使用网络编码的传输方法中，如果出现中继译码错误会造成误码扩散，从而影响系统性能。为了克服这一缺点，本文提出了一种基于软信息的网络编
ａｄｆｒｒ，Ｄ）传输协议。ｎｗａｄＦｏ
传输的所有节点对数据的变换操作可以保证最终所有接收
节点正确恢复出信源所发送的所有信息。
在传统的网络中，作为中继的节点只能对接收到的各
个信号进行分别处理和各自转发，这对于网络资源有时候是一种浪费。网络编码技术打破了这种限制，它允许中继节点对接收到的信息进行编码，并将接收到的多个数据包
发来的数据符号分别进行解调，得到两路ＬＲ软信息。将Ｌ

2024年同等学力申硕计算机学科综合考前押卷模拟题

同等学力申硕-计算机科学与技术学科综合-模拟题1 【单选】OSI参考模型的第5层（自下而上）完成的主要功能是（）。

A 差错控制B 路由选择C 会话管理D 数据表示转换【答案】C【解析】OSI参考模型分层（自上而下）：应用层、表示层、会话层、传输层、网络层、数据链路层、物理层，所以OSI参考模型自下而上的第五层即自上而下的第三层为会话层，它负责通信主机间的会话的建立，管理和拆除，答案选C。

2 【单选】对于滑动窗口协议，如果分组序号采用3比特编号，发送窗口大小为5，则接收窗口最大是（）。

A 2B 3C 4D 5【答案】B【解析】对于滑动窗口协议，如果分组序号采用n比特编号，则：发送窗口大小＋接收窗口大小≤2 n ，由题意可知，分组序号采用3比特编号，发送窗口大小为5，所以接收窗口大小≤23—5，即最大为3，答案选B。

3 【单选】在10000Hz的最大频带宽上达到100000bps，允许最小信噪比是（）。

A 511B 512C 1023D 1024【答案】C【解析】在有噪声信道的情况下，由香农定理得C＝H x log2（1＋S／N），即100000＝10000 x log2（1＋S／N），所以S／N＝210-1＝1023，所以允许的最小信噪比是1023，答案选C。

4 【单选】RIP协议和OSPF协议分别使用（）协议进行传输。

A UDP和IPB TCP和UDPC TCP和IPD 都是用IP【答案】A【解析】RIP通过广播UDP报文来交换路由信息，每30秒发送一次路由信息更新：OSPF 不使用UDP而是直接用IP数据报来传送。

5 【单选】某校园网的地址是202．100．192．0／18，要把该网络分成30个子网，则子网掩码应该是（），每个子网可分配的主机地址数是（）。

A 255.255.200.0,32B 255.255.224.0,64C 255.255.254.0,510D 255.255.255.0,512【答案】C【解析】把网络202.100.192.0／18划分成30个子网，需要5位来标识子网号，再加上原来的18位，则子网掩码为255.255.254.0，还留有32—5—18＝9位来表示主机地址。

LTE R12 协议 36212

3GPP TS 36.212 V12.0.0 (2013-12)Technical Specification3rd Generation Partnership Project;Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA);Multiplexing and channel coding(Release 12)The present document has been developed within the 3rd Generation Partnership Project (3GPP TM) and may be further elaborated for the purposes of 3GPP. The present document has not been subject to any approval process by the 3GPP Organizational Partners and shall not be implemented.This Specification is provided for future development work within 3GPP only. The Organizational Partners accept no liability for any use of this Specification. Specifications and reports for implementation of the 3GPP TM system should be obtained via the 3GPP Organizational Partners‟ Publications Offices.KeywordsUMTS, radio, Layer 13GPPPostal address3GPP support office address650 Route des Lucioles – Sophia AntipolisValbonne – FranceTel. : +33 4 92 94 42 00 Fax : +33 4 93 65 47 16InternetCopyright NotificationNo part may be reproduced except as authorized by written permission.The copyright and the foregoing restriction extend to reproduction in all media.© 2013, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC).All rights reserved.UMTS™ is a Trade Mark of ETSI registered for the benefit of its members3GPP™ is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners LTE™ is a Trade Mark of ETSI registered for the benefit of its Members and o f the 3GPP Organizational Partners GSM® and the GSM logo are registered and owned by the GSM AssociationContentsForeword (5)1Scope (6)2References (6)3Definitions, symbols and abbreviations (6)3.1 Definitions (6)3.2Symbols (6)3.3 Abbreviations (7)4Mapping to physical channels (7)4.1Uplink (7)4.2Downlink (8)5Channel coding, multiplexing and interleaving (8)5.1Generic procedures (8)5.1.1CRC calculation (8)5.1.2Code block segmentation and code block CRC attachment (9)5.1.3Channel coding (11)5.1.3.1Tail biting convolutional coding (11)5.1.3.2Turbo coding (12)5.1.3.2.1Turbo encoder (12)5.1.3.2.2Trellis termination for turbo encoder (13)5.1.3.2.3Turbo code internal interleaver (13)5.1.4Rate matching (15)5.1.4.1Rate matching for turbo coded transport channels (15)5.1.4.1.1Sub-block interleaver (15)5.1.4.1.2Bit collection, selection and transmission (16)5.1.4.2Rate matching for convolutionally coded transport channels and control information (18)5.1.4.2.1Sub-block interleaver (19)5.1.4.2.2Bit collection, selection and transmission (20)5.1.5Code block concatenation (20)5.2Uplink transport channels and control information (21)5.2.1Random access channel (21)5.2.2Uplink shared channel (21)5.2.2.1Transport block CRC attachment (22)5.2.2.2Code block segmentation and code block CRC attachment (22)5.2.2.3Channel coding of UL-SCH (23)5.2.2.4Rate matching (23)5.2.2.5Code block concatenation (23)5.2.2.6 Channel coding of control information (23)5.2.2.6.1Channel quality information formats for wideband CQI reports (33)5.2.2.6.2Channel quality information formats for higher layer configured subband CQI reports (34)5.2.2.6.3Channel quality information formats for UE selected subband CQI reports (37)5.2.2.6.4Channel coding for CQI/PMI information in PUSCH (39)5.2.2.6.5Channel coding for more than 11 bits of HARQ-ACK information (40)5.2.2.7 Data and control multiplexing (41)5.2.2.8 Channel interleaver (42)5.2.3Uplink control information on PUCCH (44)5.2.3.1Channel coding for UCI HARQ-ACK (44)5.2.3.2Channel coding for UCI scheduling request (49)5.2.3.3Channel coding for UCI channel quality information (49)5.2.3.3.1Channel quality information formats for wideband reports (49)5.2.3.3.2Channel quality information formats for UE-selected sub-band reports (52)5.2.3.4Channel coding for UCI channel quality information and HARQ-ACK (56)5.2.4Uplink control information on PUSCH without UL-SCH data (56)5.2.4.1 Channel coding of control information (57)5.2.4.2 Control information mapping (57)5.2.4.3 Channel interleaver (58)5.3Downlink transport channels and control information (58)5.3.1Broadcast channel (58)5.3.1.1Transport block CRC attachment (58)5.3.1.2Channel coding (59)5.3.1.3 Rate matching (59)5.3.2Downlink shared channel, Paging channel and Multicast channel (59)5.3.2.1Transport block CRC attachment (60)5.3.2.2Code block segmentation and code block CRC attachment (60)5.3.2.3Channel coding (61)5.3.2.4Rate matching (61)5.3.2.5Code block concatenation (61)5.3.3Downlink control information (61)5.3.3.1DCI formats (62)5.3.3.1.1Format 0 (62)5.3.3.1.2Format 1 (63)5.3.3.1.3Format 1A (64)5.3.3.1.3A Format 1B (66)5.3.3.1.4Format 1C (68)5.3.3.1.4A Format 1D (68)5.3.3.1.5Format 2 (70)5.3.3.1.5A Format 2A (73)5.3.3.1.5B Format 2B (75)5.3.3.1.5C Format 2C (76)5.3.3.1.5D Format 2D (78)5.3.3.1.6Format 3 (79)5.3.3.1.7Format 3A (79)5.3.3.1.8Format 4 (80)5.3.3.2CRC attachment (81)5.3.3.3Channel coding (82)5.3.3.4Rate matching (82)5.3.4Control format indicator (82)5.3.4.1Channel coding (83)5.3.5HARQ indicator (HI) (83)5.3.5.1Channel coding (83)Annex A (informative): Change history (85)ForewordThis Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP).The contents of the present document are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follows:Version x.y.zwhere:x the first digit:1 presented to TSG for information;2 presented to TSG for approval;3 or greater indicates TSG approved document under change control.Y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc.z the third digit is incremented when editorial only changes have been incorporated in the document.1 ScopeThe present document specifies the coding, multiplexing and mapping to physical channels for E-UTRA.2 ReferencesThe following documents contain provisions which, through reference in this text, constitute provisions of the present document.∙References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.∙For a specific reference, subsequent revisions do not apply.∙For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (includinga GSM document), a non-specific reference implicitly refers to the latest version of that document in the sameRelease as the present document.[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".[2] 3GPP TS 36.211: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels andmodulation".[3] 3GPP TS 36.213: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layerprocedures".[4] 3GPP TS 36.306: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE)radio access capabilities".[5] 3GPP TS36.321, “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium AccessControl (MAC) protocol specification”[6] 3GPP TS36.331, “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio ResourceControl (RRC) proto col specification”3 Definitions, symbols and abbreviations3.1 DefinitionsFor the purposes of the present document, the terms and definitions given in [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in [1].Definition format<defined term>: <definition>.3.2 SymbolsFor the purposes of the present document, the following symbols apply:DLN Downlink bandwidth configuration, expressed in number of resource blocks [2] RBULN Uplink bandwidth configuration, expressed in number of resource blocks [2] RBRBN Resource block size in the frequency domain, expressed as a number of subcarriers scPUSCHN Number of SC-FDMA symbols carrying PUSCH in a subframesym b-PUSCHinitialN Number of SC-FDMA symbols carrying PUSCH in the initial PUSCH transmission subframe symbULN Number of SC-FDMA symbols in an uplink slotsymbN Number of SC-FDMA symbols used for SRS transmission in a subframe (0 or 1).SRS3.3 AbbreviationsFor the purposes of the present document, the following abbreviations apply:BCH Broadcast channelCFI Control Format IndicatorCP Cyclic PrefixCSI Channel State InformationDCI Downlink Control InformationDL-SCH Downlink Shared channelEPDCCH Enhanced Physical Downlink Control channelFDD Frequency Division DuplexingHI HARQ indicatorMCH Multicast channelPBCH Physical Broadcast channelPCFICH Physical Control Format Indicator channelPCH Paging channelPDCCH Physical Downlink Control channelPDSCH Physical Downlink Shared channelPHICH Physical HARQ indicator channelPMCH Physical Multicast channelPMI Precoding Matrix IndicatorPRACH Physical Random Access channelPUCCH Physical Uplink Control channelPUSCH Physical Uplink Shared channelRACH Random Access channelRI Rank IndicationSR Scheduling RequestSRS Sounding Reference SignalTDD Time Division DuplexingTPMI Transmitted Precoding Matrix IndicatorUCI U plink Control InformationUL-SCH Uplink Shared channel4 Mapping to physical channels4.1 UplinkTable 4.1-1 specifies the mapping of the uplink transport channels to their corresponding physical channels. Table 4.1-2 specifies the mapping of the uplink control channel information to its corresponding physical channel.Table 4.1-1Table 4.1-24.2 DownlinkTable 4.2-1 specifies the mapping of the downlink transport channels to their corresponding physical channels. Table4.2-2 specifies the mapping of the downlink control channel information to its corresponding physical channel.Table 4.2-1Table 4.2-25 Channel coding, multiplexing and interleavingData and control streams from/to MAC layer are encoded /decoded to offer transport and control services over the radio transmission link. Channel coding scheme is a combination of error detection, error correcting, rate matching, interleaving and transport channel or control information mapping onto/splitting from physical channels.5.1Generic procedures This section contains coding procedures which are used for more than one transport channel or control information type.5.1.1 CRC calculation Denote the input bits to the CRC computation by 13210,...,,,,-A a a a a a , and the parity bits by 13210,...,,,,-L p p p p p . A is the size of the input sequence and L is the number of parity bits. The parity bits are generated by one of the following cyclic generator polynomials:- g CRC24A (D ) = [D 24 + D 23 + D 18 + D 17 + D 14 + D 11 + D 10 + D 7 + D 6 + D 5 + D 4 + D 3 + D + 1] and;- g CRC24B (D ) = [D 24 + D 23 + D 6 + D 5 + D + 1] for a CRC length L = 24 and;- g CRC16(D ) = [D 16 + D 12 + D 5 + 1] for a CRC length L = 16.- g CRC8(D ) = [D 8 + D 7 + D 4 + D 3 + D + 1] for a CRC length of L = 8.The encoding is performed in a systematic form, which means that in GF(2), the polynomial:23122221230241221230......p D p D p D p D a D a D a A A A ++++++++-++yields a remainder equal to 0 when divided by the corresponding length-24 CRC generator polynomial, g CRC24A (D ) or g CRC24B (D ), the polynomial:15114141150161141150......p D p D p D p D a D a D a A A A ++++++++-++yields a remainder equal to 0 when divided by g CRC16(D ), and the polynomial:7166170816170......p D p D p D p D a D a D a A A A ++++++++-++yields a remainder equal to 0 when divided by g CRC8(D ).The bits after CRC attachment are denoted by 13210,...,,,,-B b b b b b , where B = A + L . The relation between a k and b k is:k k a b = for k = 0, 1, 2, …, A -1A k k p b -=for k = A , A +1, A +2,..., A +L -1.5.1.2 Code block segmentation and code block CRC attachmentThe input bit sequence to the code block segmentation is denoted by 13210,...,,,,-B b b b b b , where B > 0. If B is larger than the maximum code block size Z , segmentation of the input bit sequence is performed and an additional CRC sequence of L = 24 bits is attached to each code block. The maximum code block size is:- Z = 6144.If the number of filler bits F calculated below is not 0, filler bits are added to the beginning of the first block.Note that if B < 40, filler bits are added to the beginning of the code block.The filler bits shall be set to <NULL > at the input to the encoder.Total number of code blocks C is determined by:if Z B ≤L = 0Number of code blocks: 1=C B B ='elseL = 24Number of code blocks: ()⎡⎤L Z B C -=/. L C B B ⋅+='end ifThe bits output from code block segmentation, for C ≠ 0, are denoted by ()13210,...,,,,-r K r r r r r c c c c c , where r is the code block number, and K r is the number of bits for the code block number r .Number of bits in each code block (applicable for C ≠ 0 only):First segmentation size: +K = minimum K in table 5.1.3-3 such that B K C '≥⋅if 1=Cthe number of code blocks with length +K is +C =1, 0=-K , 0=-Celse if 1>CSecond segmentation size: -K = maximum K in table 5.1.3-3 such that +<K K -+-=∆K K KNumber of segments of size -K : ⎥⎦⎥⎢⎣⎢∆'-⋅=+-K B K C C . Number of segments of size +K : -+-=C C C .end ifNumber of filler bits: B K C K C F '-⋅+⋅=--++for k = 0 to F -1-- Insertion of filler bits >=<NULL c k 0end fork = Fs = 0for r = 0 to C -1if -<C r-=K K relse+=K K rend ifwhile L K k r -<s rk b c =1+=k k1+=s s end whileif C >1The sequence ()13210,...,,,,--L K r r r r r r c c c c c is used to calculate the CRC parity bits ()1210,...,,,-L r r r r p p p paccording to section 5.1.1 with the generator polynomial g CRC24B (D ). For CRC calculation it isassumed that filler bits, if present, have the value 0.while r K k <)(r K L k r rk p c -+=1+=k kend whileend if 0=kend for5.1.3 Channel codingThe bit sequence input for a given code block to channel coding is denoted by 13210,...,,,,-K c c c c c , where K is thenumber of bits to encode. After encoding the bits are denoted by )(1)(3)(2)(1)(0,...,,,,i D i i i i d d d d d -, where D is the number of encoded bits per output stream and i indexes the encoder output stream. The relation between k c and )(i k d and betweenK and D is dependent on the channel coding scheme.The following channel coding schemes can be applied to TrCHs: - tail biting convolutional coding; - turbo coding.Usage of coding scheme and coding rate for the different types of TrCH is shown in table 5.1.3-1. Usage of coding scheme and coding rate for the different control information types is shown in table 5.1.3-2. The values of D in connection with each coding scheme: - tail biting convolutional coding with rate 1/3: D = K ; - turbo coding with rate 1/3: D = K + 4.The range for the output stream index i is 0, 1 and 2 for both coding schemes.Table 5.1.3-1: Usage of channel coding scheme and coding rate for TrCHs.Table 5.1.3-2: Usage of channel coding scheme and coding rate for control information.5.1.3.1 Tail biting convolutional codingA tail biting convolutional code with constraint length 7 and coding rate 1/3 is defined. The configuration of the convolutional encoder is presented in figure 5.1.3-1.The initial value of the shift register of the encoder shall be set to the values corresponding to the last 6 information bits in the input stream so that the initial and final states of the shift register are the same. Therefore, denoting the shift register of the encoder by 5210,...,,,s s s s , then the initial value of the shift register shall be set to()i K i c s --=10 = 133 (octal)1 = 171 (octal)2 = 165 (octal)Figure 5.1.3-1: Rate 1/3 tail biting convolutional encoder.The encoder output streams )0(k d , )1(k d and )2(k d correspond to the first, second and third parity streams, respectively asshown in Figure 5.1.3-1.5.1.3.2Turbo coding5.1.3.2.1Turbo encoderThe scheme of turbo encoder is a Parallel Concatenated Convolutional Code (PCCC) with two 8-state constituent encoders and one turbo code internal interleaver. The coding rate of turbo encoder is 1/3. The structure of turbo encoder is illustrated in figure 5.1.3-2.The transfer function of the 8-state constituent code for the PCCC is: G (D ) = ⎥⎦⎤⎢⎣⎡)()(,101D g D g ,whereg 0(D ) = 1 + D 2 + D 3,g 1(D ) = 1 + D + D 3.The initial value of the shift registers of the 8-state constituent encoders shall be all zeros when starting to encode the input bits.The output from the turbo encoder isk k x d =)0( k k z d =)1( k k z d '=)2(for 1,...,2,1,0-=K k .If the code block to be encoded is the 0-th code block and the number of filler bits is greater than zero, i.e., F > 0, thenthe encoder shall set c k , = 0, k = 0,…,(F -1) at its input and shall set >=<NULL d k )0(, k = 0,…,(F -1) and >=<NULL d k )1(, k = 0,…,(F -1) at its output.The bits input to the turbo encoder are denoted by 13210,...,,,,-K c c c c c , and the bits output from the first and second 8-state constituent encoders are denoted by 13210,...,,,,-K z z z z z and 13210,...,,,,-'''''K z z z z z , respectively. The bits outputfrom the turbo code internal interleaver are denoted by 110,...,,-'''K c c c , and these bits are to be the input to the second 8-state constituent encoder.Figure 5.1.3-2: Structure of rate 1/3 turbo encoder (dotted lines apply for trellis termination only).5.1.3.2.2 Trellis termination for turbo encoderTrellis termination is performed by taking the tail bits from the shift register feedback after all information bits areencoded. Tail bits are padded after the encoding of information bits.The first three tail bits shall be used to terminate the first constituent encoder (upper switch of figure 5.1.3-2 in lower position) while the second constituent encoder is disabled. The last three tail bits shall be used to terminate the second constituent encoder (lower switch of figure 5.1.3-2 in lower position) while the first constituent encoder is disabled. The transmitted bits for trellis termination shall then be:K K x d =)0(, 1)0(1++=K K z d , K K x d '=+)0(2, 1)0(3++'=K K z d K K z d =)1(, 2)1(1++=K K x d , K K z d '=+)1(2, 2)1(3++'=K K x d1)2(+=K K x d , 2)2(1++=K K z d , 1)2(2++'=K K x d , 2)2(3++'=K K z d5.1.3.2.3 Turbo code internal interleaverThe bits input to the turbo code internal interleaver are denoted by 110,...,,-K c c c , where K is the number of input bits.The bits output from the turbo code internal interleaver are denoted by 110,...,,-'''K c c c . The relationship between the input and output bits is as follows:()i i c c ∏=', i =0, 1,…, (K -1)where the relationship between the output index i and the input index )(i ∏ satisfies the following quadratic form:()K i f i f i mod )(221⋅+⋅=∏The parameters 1f and 2f depend on the block size K and are summarized in Table 5.1.3-3.Table 5.1.3-3: Turbo code internal interleaver parameters.5.1.4Rate matching5.1.4.1Rate matching for turbo coded transport channelsThe rate matching for turbo coded transport channels is defined per coded block and consists of interleaving the threeinformation bit streams )0(k d , )1(k d and )2(k d , followed by the collection of bits and the generation of a circular buffer asdepicted in Figure 5.1.4-1. The output bits for each code block are transmitted as described in section 5.1.4.1.2.Figure 5.1.4-1. Rate matching for turbo coded transport channels.The bit stream )0(k d is interleaved according to the sub-block interleaver defined in section 5.1.4.1.1 with an output sequence defined as )0(1)0(2)0(1)0(0,...,,,-∏K v v v v and where ∏K is defined in section 5.1.4.1.1.The bit stream )1(k d is interleaved according to the sub-block interleaver defined in section 5.1.4.1.1 with an output sequence defined as )1(1)1(2)1(1)1(0,...,,,-∏K v v v v .The bit stream )2(k d is interleaved according to the sub-block interleaver defined in section 5.1.4.1.1 with an output sequence defined as )2(1)2(2)2(1)2(0,...,,,-∏K v v v v .The sequence of bits k e for transmission is generated according to section 5.1.4.1.2.5.1.4.1.1 Sub-block interleaverThe bits input to the block interleaver are denoted by )(1)(2)(1)(0,...,,,i D i i i d d d d -, where D is the number of bits. The output bit sequence from the block interleaver is derived as follows:(1) Assign 32=TCsubblockC to be the number of columns of the matrix. The columns of the matrix are numbered 0, 1, 2,…,1-TCsubblockC from left to right. (2) Determine the number of rows of the matrix TCsubblock R , by finding minimum integer TCsubblock R such that:()TCsubblock TC subblock C R D ⨯≤The rows of rectangular matrix are numbered 0, 1, 2,…,1-TCsubblockR from top to bottom.(3) If ()D C R TC subblock TC subblock >⨯, then ()D C R N TCsubblock TC subblock D -⨯= dummy bits are padded such that y k = <NULL > for k = 0, 1,…, N D - 1. Then, )(i k k N d y D =+, k = 0, 1,…, D -1, and the bit sequence y k is written intothe ()TC subblockTC subblock C R ⨯ matrix row by row starting with bit y 0 in column 0 of row 0: ⎥⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎢⎣⎡-⨯+⨯-+⨯-⨯--++-)1(2)1(1)1()1(12211210TCsubblock TC subblock TCsubblock TCsubblock TCsubblock TCsubblock TCsubblockTC subblock TCsubblock TCsubblock TCsubblock TCsubblock TCsubblock C R C R C R C R C C C C C y y y y y y y y y y y yFor )0(k d and )1(k d :(4) Perform the inter-column permutation for the matrix based on the pattern (){}1,...,1,0-∈TCsubblock C j j P that is shown intable 5.1.4-1, where P(j ) is the original column position of the j -th permuted column. After permutation of thecolumns, the inter-column permuted ()TCsubblockTC subblock C R ⨯ matrix is equal to ⎥⎥⎥⎥⎥⎦⎤⎢⎢⎢⎢⎢⎣⎡⨯-+-⨯-+⨯-+⨯-++-+++-TCsubblockTC subblock TCsubblock TCsubblockTCsubblock TCsubblockTCsubblock TCsubblock TC subblock TCsubblockTCsubblock TCsubblockTCsubblockTCsubblock TC subblock C R C P C R P C R P C R P C C P C P C P C P C P P P P y y y y y y y y y y y y )1()1()1()2()1()1()1()0()1()2()1()0()1()2()1()0((5) The output of the block interleaver is the bit sequence read out column by column from the inter-columnpermuted ()TCsubblockTC subblock C R ⨯matrix. The bits after sub-block interleaving are denoted by )(1)(2)(1)(0,...,,,i K i i i v v v v -∏,where )(0i v corresponds to )0(P y ,)(1i v to TC subblockC P y +)0(… and ()TCsubblock TC subblock C R K ⨯=∏.For )2(k d :(4) The output of the sub-block interleaver is denoted by )2(1)2(2)2(1)2(0,...,,,-∏K v v v v , where )()2(k ky v π= and where ()∏⎪⎪⎭⎫ ⎝⎛+⨯+⎪⎪⎭⎫ ⎝⎛⎥⎥⎦⎥⎢⎢⎣⎢=K R k C R k P k TC subblock TC subblock TC subblock mod 1mod )(π The permutation function P is defined in Table 5.1.4-1.Table 5.1.4-1 Inter-column permutation pattern for sub-block interleaver.5.1.4.1.2 Bit collection, selection and transmissionThe circular buffer of length ∏=K K w 3 for the r -th coded block is generated as follows: )0(k k v w =for k = 0,…, 1-∏K)1(2k k K v w =+∏ for k = 0,…, 1-∏K)2(12k k K v w =++∏ for k = 0,…, 1-∏KDenote the soft buffer size for the transport block by N IR bits and the soft buffer size for the r -th code block by N cb bits. The size N cb is obtained as follows, where C is the number of code blocks computed in section 5.1.2: -⎪⎪⎭⎫⎝⎛⎥⎦⎥⎢⎣⎢=w IR cb K C N N ,min for DL-SCH and PCH transport channels- w cb K N = for UL-SCH and MCH transport channelswhere N IR is equal to:()⎥⎥⎦⎥⎢⎢⎣⎢⋅⋅=limit DL_HARQ MIMO ,min M M K K N N C soft IRwhere:If the UE signals ue-Category-v1020, and is configured with transmission mode 9 or transmission mode 10 for the DLcell, N soft is the total number of soft channel bits [4] according to the UE category indicated by ue-Category-v1020 [6]. Otherwise, N soft is the total number of soft channel bits [4] according to the UE category indicated by ue-Category (without suffix) [6]. If N soft = 35982720, K C = 5,elseif N soft = 3654144 and the UE is capable of supporting no more than a maximum of two spatial layers for the DL cell, K C = 2 else K C = 1 End if.K MIMO is equal to 2 if the UE is configured to receive PDSCH transmissions based on transmission modes 3, 4, 8, 9 or 10 as defined in section 7.1 of [3], and is equal to 1 otherwise.If the UE is configured with more than one serving cell and if at least two serving cells have different UL/DLconfigurations, M DL_HARQ is the maximum number of DL HARQ processes as defined in Table 7-1 in [3] for the DL-reference UL/DL configuration of the serving cell. Otherwise, M DL_HARQ is the maximum number of DL HARQ processes as defined in section 7 of [3]. M limit is a constant equal to 8.Denoting by E the rate matching output sequence length for the r -th coded block, and rv idx the redundancy version number for this transmission (rv idx = 0, 1, 2 or 3), the rate matching output bit sequence is k e , k = 0,1,..., 1-E . Define by G the total number of bits available for the transmission of one transport block.Set )m L Q N G G ⋅=' where Q m is equal to 2 for QPSK, 4 for 16QAM and 6 for 64QAM, and where - For transmit diversity: - N L is equal to 2, - Otherwise:- N L is equal to the number of layers a transport block is mapped onto Set C G mod '=γ, where C is the number of code blocks computed in section 5.1.2.if 1--≤γC rset ⎣⎦C G Q N E m L /'⋅⋅= elseset ⎡⎤C G Q N E m L /'⋅⋅=end if Set ⎪⎪⎭⎫ ⎝⎛+⋅⎥⎥⎤⎢⎢⎡⋅⋅=2820idx TC subblock cb TCsubblockrv R N R k , where TC subblock R is the number of rows defined in section 5.1.4.1.1. Set k = 0 and j = 0 while { k < E } if >≠<+NULL w cb N j k m od )(0 cb N j k k w e m od )(0+=k = k +1end if j = j +1end while5.1.4.2Rate matching for convolutionally coded transport channels and control informationThe rate matching for convolutionally coded transport channels and control information consists of interleaving thethree bit streams, )0(k d , )1(k d and )2(k d , followed by the collection of bits and the generation of a circular buffer asdepicted in Figure 5.1.4-2. The output bits are transmitted as described in section 5.1.4.2.2.Figure 5.1.4-2. Rate matching for convolutionally coded transport channels and control information.The bit stream )0(k d is interleaved according to the sub-block interleaver defined in section 5.1.4.2.1 with an output sequence defined as )0(1)0(2)0(1)0(0,...,,,-∏K v v v v and where ∏K is defined in section 5.1.4.2.1.The bit stream )1(k d is interleaved according to the sub-block interleaver defined in section 5.1.4.2.1 with an output sequence defined as )1(1)1(2)1(1)1(0,...,,,-∏K v v v v .。

(整理)英语翻译MicrosoftWord文档

限制性核酸内切酶微生物能够在获得的其他来源的ＤＮＡ中识别自己的ＤＮＡ。

这种体系已经发展到识别自我和非自我，依靠细胞内部的两种酶：修饰性甲基化酶和限制性核酸内切酶。

这种甲基化酶在新生的双链ＤＮＡ链上以特定的方式对各种核苷酸残基增加甲基集团。

这种识别序列在长度上通常有４到７个碱基对并且是回文序列，这就是说，这种序列在ＤＮＡ一条链上与它互补链是相同的。

大多数生物体具有许多不同的修饰性甲基化酶。

限制性核酸内切酶作为修饰性酶识别相同的序列，但是代替甲基化，在序列上切割ＤＮＡ。

然而，核酸内切酶不会切割自身序列但是会降解外援ＤＮＡ。

这种识别和切开双链ＤＮＡ特殊序列的特性已经成为从许多类型的微生物中切除ＤＮＡ片段的基础。

不同种类的限制性内切酶被发现，被称为１，２，３，和４类型。

只有２类型对新的DNA 技术是重要的。

2类型限制性内切酶有特殊的重要性因为他们的特殊序列并且可以在精确的位置使双链DNA断裂。

用这种方式切开长的外源DNA分子成为短的片段也可以在质粒载体做一个单一缺口，在这位置上DNA片段可以被插入。

在一些酶的作用下，切口产生单一链末端并且对于一个给定的限制性核苷酸得到的所有片段的目的序列是相同的。

用这种方法，任一片段通过一种特殊的退火增殖可以与其他通过相同核酸内切酶切割的片段进行配对，因此创造出一个杂交分子。

自从来自大量细菌的限制性核酸内切酶发现以后，命名细菌的一套专业术语就被采用了。

宿主微生物的属名和种名由类型的首字母确定，并且种名的前两个字母用斜体字形成三个字母的缩写。

例如，E。

coli，Eco.菌株和类型用无下滑线记号鉴定并且核酸内切酶的号码用罗马数字—EcoRⅡ.不同的核算内切酶可以用于产生不同尺寸的DNA片段使不同的3‘或5’单链延长。

这种DNA片段可以用电泳纯化。

通过EcoR1水解PBR322的单一目的位点或者通过限制性核酸内切酶因为有一个单一的目标位点，改变环状制粒成为线状DNA分子。

这个位点可以通过有两个折叠对称轴的2型限制性核酸内切酶识别：它们可以是4，5，或6核苷酸序列。

Erasurecode在分布式存储系统中的研究

Erasure Codes编码与解码过程
编码过程
将原始数据分割成多个块，并使用额外的块进行编码。编码过程中，可以使用不同的算法和参数来选择最佳的编码方式，以满足系统的可靠性和性能要求。
VS
解码过程
当部分数据丢失时，可以使用剩余的块和额外的块进行解码，以恢复原始数据。解码过程中，需要使用相应的算法和参数来处理丢失的数据，并生成新的额外块来恢复数据。
REPORT
CATALOG
DATE
ANALYSIS
SUMMAR Y
06
结论与展望
研究成果总结
• Erasurecode技术提高了数据冗余度，增强了数据可靠性。通过将数据分成多个块并存储在不同的节点上，即使部分节点发生故障，也能从其他节点恢复数据，从而确保数据的可靠性和可用性。
• Erasurecode技术降低了存储成本。由于数据被分散存储在多个节点上，因此可以减少每个节点的存储需求，从而降低整个分布式存储系统的成本。
• Erasurecode技术提高了数据访问性能。通过将数据分散存储在多个节点上，可以并行访问数据，从而提高数据访问速度和效率。
• Erasurecode技术具有灵活性和可扩展性。它可以适应不同的应用场景和需求，通过调整参数和配置来优化性能和成本。同时，随着节点数量的增加，分布式存储系统的容量和可靠性也可以得到进一步提升。
数量后，提高幅度逐渐减小。
存储效率
02
采用erasure code技术可以有效降低存储空间需求，提高存储
效率。
传输效率
03
在节点间传输数据时，采用erasure code技术可以有效降低传
输量，提高传输效率。
实验结果与分析

存储HCIP试题库+参考答案

存储HCIP试题库+参考答案一、单选题（共38题，每题1分，共38分）1.下列选项中关于配额与统计描述错误的是：A、可供统计的桶资源包括桶的空间大小、拥有的桶数量以及桶中的对象数量。

B、当帐户的桶容量总数达到所配置的帐户配额后，该帐户无法再进行写入操作。

C、可供统计的帐户资源包括帐户配额、拥有的桶数量、对象数量及容量总大小。

D、当桶容量达到所配置的桶配额后，无法再对该桶进行写入操作。

正确答案：D2.华为分布式存储对象服务使用哪种协议获取租户、桶的资源统计情况（）A、SNMPB、SSLC、RESTD、SMI-S正确答案：A3.以下哪个不是 NAS 系统的体系结构中必须包含的组件？A、可访问的磁盘阵列B、文件系统C、访问文件系统的接口D、访问文件系统的业务接口正确答案：D4.以下关于 Oceanstor 9000 的物理分域描述错误的是哪一项?A、物理分域是一种隔离故障的有效手段B、某些节点故障,会造成与这些节点在一个物理分域内的其他节点上的数据的可靠性级别降低C、Oceanstor 9000 通过节点池与分级的方法来实现物理分域D、管理员最少要将 2 个存储节点加入一个分域中正确答案：D5.帐户是使用对象存储服务（兼容 Amazon S3 接口）的凭证，其管理功能不包括：A、签约业务管理B、帐户基本管理C、证书管理D、跨域访问策略管理正确答案：D6.大数据时代对传统技术升级已经满足不了了大数据处理的需求,以下哪一项不是大数据时代技术发展的方向?A、计算向集群化发展B、由非关系型数据库想关系型数据库发展C、网络向更高苏,协议开销更低,更有效的方向发展D、向虚拟化方向发展正确答案：B7.站点 A 需要的存储容量为 2543GB.，站点 B 需要的存储容量为3000GB.，站点 B 的备份数据远程复制到站点 A保存。

考虑复制压缩的情况，压缩比为 3，计算站点 A 需要的后端存储容量是多大？A、3543GB.B、4644GB.C、3865GB.D、4549GB.正确答案：A8.华为 Oceanstor 9000 InfoTier 文件池策略将决定文件创建的存储位置,以及文件重条带化时的目标分级,以下关于文件池策略说法不正确的是哪一项?A、default 策略可以被修改B、default 策略优先级最低C、最多可支持配置 128 条文件池策略D、策略参数组合间为“或”的关系正确答案：D9.以下那个特性不能提升华为混合闪存存储产品的性能？A、SmartPartitionB、SmartCacheC、SmartVirtualizationD、SmartTier正确答案：C10.以下关于 CIFS 的工作原理说法正确的是哪一项？A、在建立共享连接之前，先建立回话，然后进行协议协商B、建立共享连接之后才能进行文件操作C、在协议协商阶段进行安全认证D、文件操作完成后，不需要客户端请求，服务器将自动断开共享连接正确答案：B11.NAS 系统专注对于以下哪种类型的数据存储和管理?A、大块数据B、文件数据C、小块数据D、连接数据块正确答案：B12.InfiniBand 协议特点不包括以下哪一项？A、速度高B、远程直接内存存取功能C、基于标准协议开发D、传输卸载，可将数据包路由从芯片级转到 os正确答案：D13.pcie 协议的特点不包括哪一项？A、高可靠B、基于帧结构的传输C、并行总线结构D、点对点连接正确答案：C14.以下描述正确的是?1 备份的目标是为了防止人为误操作或系统问题，保存的是历史数据，恢复时间相对长 2 备份方案通常使用快照、镜像或复制技术来实现。

Erasure-Coding

Erasure-Coding Based Routing for Opportunistic NetworksY ong Wang,Sushant Jain†,Margaret Martonosi,Kevin Fall‡Princeton University,†University of Washington,‡Intel Research BerkeleyABSTRACTRouting in Delay Tolerant Networks(DTN)with unpredictable node mobility is a challenging problem because disconnections are preva-lent and lack of knowledge about network dynamics hinders good decision making.Current approaches are primarily based on redun-dant transmissions.They have either high overhead due to exces-sive transmissions or long delays due to the possibility of making wrong choices when forwarding a few redundant copies.In this pa-per,we propose a novel forwarding algorithm based on the idea of erasure codes.Erasure coding allows use of a large number of re-lays while maintaining a constant overhead,which results in fewer cases of long delays.We use simulation to compare the routing performance of using erasure codes in DTN with four other categories of forwarding al-gorithms proposed in the literature.Our simulations are based on a real-world mobility trace collected in a large outdoor wild-life environment.The results show that the erasure-coding based algo-rithm provides the best worst-case delay performance with aﬁxed amount of overhead.We also present a simple analytical model to capture the delay characteristics of erasure-coding based forward-ing,which provides insights on the potential of our approach. Categories and Subject DescriptorsC.2.2[Network Protocols]:Routing protocolsGeneral TermsAlgorithms,Performance,TheoryKeywordsRouting,Delay Tolerant Network,Erasure Coding1.INTRODUCTIONOpportunistic networks are an important class of DTNs in which contacts(time-window when data can be exchanged)appear op-portunistically without any prior information.Examples of such networks are sparse mobile ad hoc networks,such as ZebraNet[8], Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for proﬁt or commercial advantage and that copies bear this notice and the full citation on theﬁrst page.To copy otherwise,to republish,to post on servers or to redistribute to lists,requires prior speciﬁc permission and/or a fee.SIGCOMM’05Workshops,August22–26,2005,Philadelphia,PA,USA. Copyright2005ACM1-59593-026-4/05/0008...$5.00.where no contemporaneous end-to-end path may exist due to radio range limitations.Routing becomes challenging in such networks because contact dynamics are not known in advance and no sin-gle path can be relied upon.Most current approaches are based on some kind of data replication over multiple paths[14,8].In this paper,we propose an alternate method of improving delay perfor-mance.The basic idea is to erasure code a message and distribute the generated code-blocks over a large number of pared to sending a full copy of the message over a relay,only a fraction of code-blocks are sent over each relay.This fraction allows us to control the routing overhead in terms of bytes transmitted.For sce-narios like ZebraNet,where nodes are energy constrained,limiting such overhead is an important design goal.The basic idea of using erasure coding is simple and has been explored in many applications[11].However,it is not clear if and when it will perform better than simpler alternatives based on pure replications in DTNs.In this paper,we study the performance of an erasure coding approach and other existing alternatives on a diverse mobility scenarios with different node densities and moving pat-terns.We use both synthetic and real-world DTN mobility traces as input to our simulations.We discover that the erasure coding approach can provide good delay guarantees by using aﬁxed over-head.Fundamentally,the beneﬁts of erasure coding arise in elimi-nating cases when long delays arise due to bad choice of forward-ing relays.Erasure coding allows the transmission to be spread over multiple relays while using aﬁxed amount of overhead.This results in a protocol much more robust to failures of a few relays or some bad choices.Weﬁnd that the erasure-coding based algorithm is the least sensitive to different parameters in terms of message latency and message delivery rate.Also,we derive an expression for the delay distribution under a simple network model to argue when and why the erasure coding approach outperforms other sim-pler alternatives.In one extreme case,we show that the average delay of a simple replication strategy will be inﬁnite,whereas,by using erasure coding the average delay can be reduced to a small constant.Erasure coding can also help combat packet loss due to bad chan-nel quality or packet drops due to congestion.A full investigation of the beneﬁts of this aspect is outside the scope of this paper.Here, our focus is on a less-conventional use of erasure coding:to achieve better delay performance using aﬁxed amount of replication.2.BACKGROUNDIn an opportunistic network,reliable data delivery is often achieved using replication to send identical copies of a message over multi-ple paths to mitigate the effects of disconnections.Typical algo-rithms differ based on their decisions as to who forwards the data, at what time is the data forwarded,and to whom is the data sent.Inthe following discussions,we deﬁne a contact as an opportunity to communicate between two nodes and a relay denotes a forwarding node.•Flooding(flood):each node forwards any non duplicated messages(including messages received on behalf of other nodes)to any other node that it encounters.flood delivers messages with the minimum delay if there are no resource constraints,such as link bandwidth or node storage.•Direct contact(direct):the source holds the data until it comes in contact with the destination.direct uses minimal resources since each message is transmitted at most once.However,it may incur long delays.•Simple replication(srep(r)):this is a simple replication strategy in which identical copies of the message are sent over theﬁrst r contacts.Here,r is the replication factor.Only the source of the message sends multiple copies.The relay nodes are allowed to send only to the destination;they cannot forward it to another relay.This leads to small over-head as the messageﬂooding is controlled to take place only near the source.This class of forwarding algorithms is also known as the two-hop relay algorithm[3,2].There is a natu-ral trade-off between overhead(r)and data delivery latency.A higher r leads to more storage/transmissions but has lowerdelays.•History-based(history(r)):here history is used as an in-dicator of the probability of delivery.Each node keeps track of the probability that a given node will deliver its messages.r highest ranked relays(based on delivery probability)are selected as forwarding nodes.ZebraNet uses the frequency at which a node encounters destination as an indicator of the delivery probability.We use the same implementation as[8] in our simulations.A summary of these forwarding algorithms is listed in Table1.Algorithm Who When To whomflood all nodes new contact all newdirect source only destination destination onlysrep(r)source only new contact rﬁrst contacts history(r)all nodes new contact r highest ranked Table1:Summary of various forwarding algorithms.3.THE ERASURE-CODING BASED FOR-W ARDING ALGORITHMAs discussed in the previous section,most current approaches for routing in opportunistic networks are based on sending multi-ple identical copies over different paths.There is a fundamental trade-off between overhead and delay.On one extreme,ﬂooding achieves the best possible delay but results in very high overhead. The other extreme is protocols like direct which have low over-head because they send only few copies or none at ck of knowledge about the topology dynamics prevents distinguishing good paths from bad ones.Therefore,these protocols may result in long delays if bad paths are selected.In this section,we describe a forwarding algorithm based on the idea of erasure coding.Our al-gorithm achieves better worst-case delay performance than existing approaches with aﬁxed overhead.3.1Erasure coding backgroundErasure codes operate by converting a message into a larger set of code blocks such that any sufﬁciently large subset of the gener-ated code blocks can be used to reconstruct the original message. More precisely,an erasure encoding takes as input a message of size M and a replication factor r.The algorithm produces M∗r/b equal sized code blocks of size b,such that any(1+ )·M/b erasure coded blocks can be used to reconstruct the message.Here, is a small constant and varies depending on the exact algorithm used, such as Reed-Solomon codes or Tornado codes.The selection of algorithms involve trade-offs between coding/decoding efﬁciency and the minimum number of code blocks to reconstruct a message. For example,Tornado codes have efﬁcient encoding and decod-ing steps based on simple operations such as XOR,at the cost of slightly higher .A thorough discussion of the various trade-offs is presented in[11].The choice of exact erasure coding algorithm is not important in our forwarding algorithm.The key aspect is that when using erasure coding with a replication factor of r,only1/r of the code blocks are required to decode the message.Therefore, we ignore constant for simplicity.Constant b is the block-size and is implementation dependent.3.2Erasure coding based forwarding(ec)Our erasure-coding based forwarding algorithm can be under-stood as an enhancement to the simple replication algorithm(srep) described in Section2.In srep with a replication factor r,the source sends r identi-cal copies over r contacts and relays are only allowed to send di-rectly to the destination.In the erasure-coding based algorithm,we ﬁrst encode the message at the source and generate a large number of code blocks.The generated code blocks are then equally split among theﬁrst kr relays,for some constant k.In comparison with srep,this approach uses a factor of k more relays and each relay carries a factor of1/k less data.However,the number of bytes generated are rM,the same as the number of bytes generated by srep(r).Now by deﬁnition of erasure coding(with rate r,message size M),the message can be decoded at the destination if1/r of the generated code blocks are received.Since code blocks are divided equally among kr relays,the message can be decoded as soon as any k relays deliver their data if we assume that no code blocks are lost during transmissions to and from a relay.When k=1,the erasure coding approach has the same effect as the simple replication approach,which is,to use theﬁrst r relays and to each carry a copy of the original message.3.3Beneﬁts of erasure coding in forwarding In simple replication,r relays are used to improve the delay per-formance.The erasure-coding based approach,instead,utilizes kr relays for the same amount of overhead.Therefore,one can ex-pect that the chances of at least some relays having low delays are higher,compared to using only r relays.At the same time,erasure coding requires at least k relays to succeed(instead of1in srep) before the data can be reconstructed.Therefore,if the number of such low-delay relays are larger than k,the erasure-coding based approach will successfully deliver the message with a lower delay than simple replication.Thus,the fundamental question is whether to use r relays and wait for one to succeed or use r∗k relays and wait for k relays to succeed.We answer this question using a sim-ple analytical model in Section5.The main observation is that if k is large,the delay distribution converges to a constant.Therefore, with the erasure-coding based approach,one can be almost assured of a constant delay.4.EV ALUATIONIn this section,we use simulation to compare forwarding al-gorithms discussed in Section2and the erasure-coding based ap-proach presented in Section3.4.1MethodologyWe use dtnsim,the discrete event simulator for DTN environ-ments from[6].We implemented the following routing algorithms in dtnsim:ﬂooding(flood),direct contact routing(direct), history-based routing(history),simple replication routing(srep)and erasure-coding based routing(ec).For srep and ec,we rep-resent different replication factors and number of relays used tosplit,using srep-rep r and ec-rep r-p n.Here,r is the replication factor and n are the number of relays among which code blocks aredivided.We simulate using a real-world mobility trace collected as partof a wildlife tracking experiment in Kenya.The mobile networkwas deployed by the ZebraNet group in January,2004[15].Track-ing collars are placed on the necks of selected zebras.Each collaruses GPS to record its position data every8minutes,and period-ically sends back position log data to a mobile base station(e.g.,a vehicle).Due to extreme weather and waterprooﬁng issues,aswell as antenna problems,only one tracking collar returned a com-plete set of uninterrupted movement data for the whole32-hour duration.Due to such limitations1,we create a semi-synthetic mo-bility model as follows:we synthesize node speed and turn angledistributions from the observed data and create other node move-ments following the same distribution.We scale the grid size to 6km×6km with a radio range of1km.Initially,the nodes are ran-domly distributed in the grid.The base station moves along a rect-angular path near the grid boundary.All messages are of size1M.Each node generates12messages every day.The total duration ofsimulation is16days.Another mobility model based on heavy-tailed inter-contact times is discussed in Section4.4.We compare the routing performance of different forwarding al-gorithms using the following three metrics:•Data success rate:the ratio of the number of messages that are delivered to the destination within a time T(deadline).If T is unspeciﬁed,it is considered to be the whole durationof the simulation,i.e16days.•Data latency:the duration between message generation and message reception(at its destination).In a DTN,latency may not be the most critical issue.However,it is always desirable to have fast data delivery whenever possible.The latency distribution metric measures how efﬁciently a protocol uses the available contact opportunities.•Routing overhead:the ratio of the number of bytes trans-mitted to the number of bytes generated during the simula-tion time.This metric measures the extra data transmitted for each message generated,while a metric based solely on the number of message transmissions will overlook the fact that ec has smaller message sizes.The radio transmission energy is proportional to the total number of byes transmit-ted.Therefore,this metric reﬂects the energy efﬁciency of the forwarding algorithm.1At the moment,we are working on collecting more node traces during our secondﬁeld trip in June,2005.We will work on adjust-ing the model once we have those node traces available.0.20.40.60.810 5 10 15 20 25 30 35 40 45 50CDFDelay (hours)Link 1Link 2Link 3Link 4(a)Inter-Contact time distribution0.20.40.60.810 2 4 6 8 10CDFDelay (hours)Link 1Link 2Link 3Link 4(b)Contact duration distributionFigure1:Cumulative distribution plots for inter-contact times and contact durations for the ZebraNet trace.Theﬁgure plots these two metrics for four randomly selected links.Other links show similar characteristics.The contact duration distribution uses a different x-axis range to separate different curves.Ob-serve that inter-contact time patterns show signiﬁcant variation and can be very long in some cases.4.2Zebra trace analysisTo begin our analysis,weﬁrst characterize the contact opportu-nities in the ZebraNet trace,with a focus on inter-contact time and contact durations.These two metrics are important in understand-ing the behavior of different forwarding algorithms on the ZebraNet trace.Simply put,inter-contact time is the time interval for which a link is down(no communications are possible during this time) and contact duration is the interval for which a link is up.Figure1plots the distribution of these two metrics for four ran-domly selected pairs of nodes(links)in the ZebraNet trace.Since almost all the links in the trace show similar characteristics,we just use these four random links as examples.As shown in Figure1(a),the inter-contact time distribution has few cases when a link is broken for a very long time.This ob-servation is important because such inter-contact time patterns can lead to extremely long delays when using a naive forwarding al-gorithm.As expected in such a sparse network,link up-times are relatively short(as compared to the link down times)and therefore, it is important to efﬁciently utilize the available communication op-portunity.4.3Impact of node density4.3.1Data latency distributionFigure2(a)and2(b)show the data latency distribution for the0 0.20.40.60.8 1 02040 8010060C C D FDelay (hours)(a)34nodes0 0.20.4 0.60.8 12040 8010060C C D FDelay (hours)(b)66nodesFigure 2:Latency distribution for different forwarding algo-rithms.Trafﬁc injection rate is 12messages per day.The distribution is shown in Complementary CDF (CCDF)curve.A numeric presentation of this ﬁgure is in Table 2which lists the exact 50th ,90th and 99th percentiles delay.The erasure-coding based approach has signiﬁcantly smaller tail than other approaches (except ﬂood).flood has the lowest latencies but has high overhead as discussed later.ZebraNet trace with 34nodes and 66nodes respectively.Discount-ing source and destination,the total number of relays are 32and 64respectively.The distribution is shown in Complementary CDF (CCDF)curve.Table 2shows various data latency percentiles for both 34-node and 66-node experiments to facilitate the comparison of worse-case delay performance among all the algorithms considered.Generally,ec has a higher 50th percentile compared to other al-gorithms as shown in both Figure 2(a)and Figure 2(b)but a lower 99th percentile.This is because it takes longer to ﬁnd enough relays to distribute data replicas.However,once ec distributes enough code blocks by forwarding along multiple relays (the num-ber of relays is larger than that used by srep ),it takes a much shorter time to transfer the messages to the destination since any n/r relays are required to be successful.Since n is much larger than r ,ec can fully utilize the diversity of multiple relays and is very robust to bad performance of individual relays.That is,in the presence of unpredicted failures or mobility of some of the re-lays,ec still has a good chance of sending the messages to the destination by routing code blocks through other functional relays.Algorithm 34nodes 66nodes 50%90%99%50%90%99%ec-rep2-p80.440.84 1.32———ec-rep2-p160.530.85 1.210.510.83 1.17ec-rep2-p32———0.590.82 1.04srep-rep20.240.88 1.700.250.89 1.91direct 0.49 1.63 3.270.51 1.79 3.54history 0.180.879.500.140.7210.83ﬂood0.0130.0440.120.000120.00910.032Table 2:Latency (in days)for different algorithms for two dif-ferent node densities.This is the same data as shown in Figure 2.We see that ec has signiﬁcantly lower 99th percentile la-tency.This indicates that ec is effective in getting rid of very high latency cases.Therefore,erasure-coding based routing is a promising candidate for opportunistic networks where (1)relay failures are prevalent and delays are unpredictable,and (2)minimizing the worst-case delay is important.This observation is further supported by the data shown in Fig-ure 2(b)where node density is higher.Given more contacts and re-lays,the CCDF curves of all forwarding algorithms become steeper.This is because there are more contacts overall.ec ,as we have ex-plained,still has the lowest 99th percentile and the sharpest data latency curve.Therefore,given enough relay opportunities,ec has the best performance in delivering most of the messages the fastest among all the algorithms considered.Simple replication,direct contact,and history-based algorithms,on the other hand,have very long tails (messages with much longer delays).This is because they use a small number of relays.There-fore,they cannot guarantee when these relays will see the desti-nation.Very likely,some packets may encounter very long delays by selecting some relays that fail to deliver the message promptly.In the long run however,with suf ﬁcient buffer space,all messages will eventually be delivered.The lower the replication factor r ,the longer the tail will be.This is illustrated by comparing the CCDF of srep-rep2and direct .Since srep-rep2replicates its data to two other relays,the chance of losing contact opportunities is lower than that for direct .Hence,srep-rep2has a shorter tail than direct .The history approach,though having the lowest 50th percentile delay,also has the longest tail among all the algorithms considered.The performance of history is dependent on the accuracy of its selection of highest ranked relays based on past statistics.If the decision is relatively accurate,it tends to ﬁnd relays that will for-ward the data to the destinations very quickly.On the contrary,if the relays selected based on this heuristic do not re ﬂect future for-warding probabilities,very long delays may be incurred.However,using certain timeout and retransmission schemes,these long-delay messages might be masked out which makes the history approach more attractive over the others in networks with predictable node movement.This is an interesting research direction to explore.Finally,observe that the flood protocol in Figure 2(a)and Fig-ure 2(b),has latency distribution curves which are almost vertical.This shows that flood has very low delays for all messages.4.3.2Routing overheadTable 3lists the routing overhead corresponding to each forward-ing algorithm.Routing overhead is measured using the ratio of bytes transmitted to the bytes generated.Since both ec and srep transmit a ﬁxed amount of data with respect to the data generated,AlgorithmOverhead(34nodes)(66nodes)ec-rep2-p8 3.96—ec-rep2-p16 3.96 3.98ec-rep2-p32— 3.98srep-rep2 3.98 3.99direct 1.0 1.0history30.2859.61ﬂood68.0132.0Table3:Routing overhead of different forwarding algorithms for two node densities.Forwarding algorithms(such as ec and srep)which employ replication only at the source has signiﬁ-cantly lower overhead.flood has almost an order of magni-tude higher overhead and does not scale well as the number of nodes increase.The high overhead of history results from our implementation in dtnsim2where a copy of message is transmitted even when some copy of the original message has been delivered.Some timeout scheme can solve this problem by reducing unnecessary message transmissions.their overhead is constant.For an algorithm with a replication factor of2,the overhead should be4,with2from the source to the relay and from the relay to the destination and the other2for the other relay.On the other hand,in both history and flood where relays also forward to other relays(and there are no restric-tions on replication factor),multiple identical copies of the original message are transmitted even after theﬁrst delivery of the origi-nal message.As Table3shows,normally history has a higher overhead than srep and ec.This situation becomes worse when more contacts are available and very likely,more duplicate mes-sages will be transmitted.For flood,almost all the nodes could receive a copy potentially and the overhead is proportional to2n, where n is the number of nodes.The factor of two comes because every relay sends to the destination(even if the destination has al-ready received the message)in our implementation.Some simple timeout scheme,such as one that imposes a maximum number of hops a message can traverse,can alleviate this problem.However, data delivery rate will decrease if the number of hops a message can traverse is too small.The exploration of such a trade-off is part of our future work.In summary,in terms of routing overhead,ec and srep scale well with node density and network size,while flood does not.4.3.3Data success rateAlgorithm0.25day1day2days4days8days ec-rep2-p822.6%95.9%100%100%100% ec-rep2-p169.2%94.6%100%100%100%srep-rep251.8%92.5%99.6%99.9%99.9%direct32.0%74.6%94.2%99.5%99.9%history58.4%87.9%92.7%94.6%95.3%ﬂood100%100%100%100%100% Table4:Data success rate of different algorithms for different deadlines.Even with extremely large deadline of8days sim-ple replication can not transfer all its data.Also note that,ec has low data success rate when deadlines are extremely small and hence,caution must be used before deciding to use erasure coding.Table4shows the data success rate for different algorithms with(1)(4)(5)(3)(2)(1) ec−rep2−p8(3) srep−rep2(4) direct(5) history(2) ec−rep2−p160.20.40.60.810.01 0.1 1 100 100010CCDFDelay (hours)Figure3:Latency distribution of different forwarding algo-rithms for the Pareto trace.We use a log-scaled x-axis for clar-ity.Similar to the ZebraNet trace we observe that tails are sig-niﬁcantly smaller when ec is used,i.e.,the worst case delays for other approaches are signiﬁcantly higher.Since x-axis is log scale,the ratio of the worst case delay values is higher than in the ZebraNet trace.deadlines smaller than the total simulation time.All deadlines are speciﬁed in units of days.The data success rate for ec is low if the deadlines are less than6hours long.However,for relatively long deadlines(between1and2days),ec has the highest data success rate.This result can be observed directly by looking at the data latency distribution curve.Because ec has a lower99th percentile of latency distribution,it will deliver more messages before that time and hence a higher data success rate.Therefore,if achieving low latencies for all messages or high success rate within certain reasonable deadlines are the application requirement,ec should be used.On the other hand,history has the highest data success rate when the deadline is less than6hours.This is because history canﬁnd good relays without the need to distribute copies of data to many relays.The performance improvement of history upon direct and srep comes directly from the efﬁciency of its selec-tion of good relays.However,since history has long tails in its data latency distribution curve,its data success rate is relatively low compared to other approaches.4.4Impact of mobility modelIn this section,we evaluate the performance of ec and other ap-proaches on a different mobility model.Our results here demon-strate that the idea of using erasure-coding based routing can be applied to different scenarios other than the ZebraNet trace.We ﬁnd that the beneﬁts of erasure coding are greater when the inter-contact times are heavy-tailed.We use such a heavy-tailed distri-bution for simulations in this section.The mobility model is based on the approximate power law distribution for inter-contact times observed for another set of real-world traces described in[2]. Figure3plots the CCDF of the data latency distribution for the Pareto trace.The other simulation parameters are exactly the same as in Section4.1.Observe that all curves are much sharper than the ZebraNet traces.Again,ec has the sharpest CCDF curve and the lowest99th percentile delay,while all the other algorithms have higher worst case delays.5.DELAY DISTRIBUTION ANALYSISThis section discusses the theoretical behavior of the delay dis-。

IE 100 PRO 无线专业耳机说明书

with Bluetooth® connectorFEATURES• Dynamic full-range transducer for high-resolution,powerful monitoring sound• Reduces acoustic stress factors through natural anddistortion-free reproduction• 2 in 1 bundle: Bluetooth® module for wireless connec-tion to mobile devices, PCs or tablets, with a built-inmicrophone for calls or standard 3,5 mm jack-plugcable• Excellent shielding through optimized earpiece shapeand flexible silicone and foam attachmentsFor the stage. For massive sound. For the road.Developed for high expectations on live stages, the specially designed driver of the IE 100 PRO creates precise audio cla-rity for musicians in live sessions. Typical for the new type of membrane is a powerful, high-resolution and warm monito-ring sound. With the included Bluetooth® module, the in-ears become comfortable everyday companions for your mobile phone, PC or tablet. With the built-in mic, phone calls or Webcasts are also possible.Musicians and DJs choose the IE 100 PRO wireless set for its exceptional sound and high wearing comfort. Not only for live sessions, but also for producing on the road or as an everyday companion.The in-ears come with 4 earpiece adapters that optimize the fit for every ear size and shape. The setup is stage-safe from the connection to the cable conduit.Sophisticated monitoring sound for mixing on live stages, producing in the studio and everywhere in between.DELIVERY INCLUDES• IE 100 PRO (BLACK, CLEAR or RED)• Bluetooth connector• black cable for IE 100 PRO• USB-A to USB-C cable• soft pouch• cleaning tool• foam and silicone ear adapters• quick guide• safety guide• compliance sheetwith Bluetooth® connectorPRODUCT VARIANTSIE 100 PRO WIRELESS BLACKArt. no. 509171IE 100 PRO WIRELESS CLEAR Art. no. 509172IE 100 PRO WIRELESS RED Art. no. 509173SPECIFICATIONS IE 100 PROFrequency response 20 - 18,000 Hz Impedance20 ΩSound pressure level (SPL)115 dB (1 kHz / 1 V rms )Total harmonic distortion (THD)< 0.1 % (1 kHz, 94 dB)Noise attenuation < 26 dB Magnetized field strength 1.63 mT Operating temperature Storage temperature –5 °C to +50 °C (23 °F to 122 °F)–20 °C to +70 °C (–4 °F to 158 °F)Relative humidity< 95 %Bluetooth ® ConnectorWearing style Bluetooth® neckband cable Microphone principle MEMS Microphone frequency response100 - 8,000 HzMicrophone sensitivity -42 dBV/Pa (ITU-T P.79)Microphone pick-up pattern (speech audio)omni-directional Power supply - built-in rechargeable lithium- polymer battery 3.7 V ⎓, 100 mAhUSB charging 5 V ⎓, 100 mA max.Operating time10 h (music playback via SBC) with rechargeable battery;240 h in standby mode Charging time ofrechargeable batteries approx. 2.5 hOperating temperature Charging temperature Storage temperature +5 °C to +40 °C ± 5 °C (41 °F to 104 °F ± 9 °F)+10 °C to +40 °C ± 5 °C (50 °F to 104 °F ± 9 °F)–20 °C to +70 °C (–4 °F to 158 °F)Relative humidity Operation: Storage:10 - 80 %, non-condensing 10 - 90 %Magnetized field strength1.63 mT (with IE 100 PRO)0.23 mT (without headphone)Weight approx. 13 gBluetooth®VersionBluetooth 5.0 compatible,class 1, BLETransmission frequency 2,402 - 2,480 MHz Modulation GFSK, π/4 DQPSK, 8DPSK Profiles HSP, HFP, AVRCP, A2DP Output power 10 mW (max)CodecSBC, aptX®, aptX LL®, AACThe Bluetooth® word mark and logos are registered trade-marks owned by Bluetooth SIG, Inc. and any use of such marks by Sennheiser electronic GmbH & Co. KG is under license.with Bluetooth® connectorSennheiser electronic GmbH & Co. KG · Am Labor 1 · 30900 Wedemark · Germany · ACCESSORIESIE PRO Bluetooth Connector Art. no. 508943IE PRO Mono cable Art. no. 508944Twisted cable Art. no. 507478Black straight cableArt. no. 508584。

一级编码英语

一级编码英语One Level Coding – EnglishIntroduction:Coding is becoming an increasingly important skill in today's digital world. It allows individuals to give instructions to computers and create various programs and applications. In this article, we will explore the importance of coding as a first-level skill in the context of learning English.Importance of Learning English:English has quickly become the global language of communication. Whether it is for business, travel, or personal growth, proficiency in English opens up numerous opportunities. As technology continues to advance, being proficient in English and coding is a powerful combination.Coding for English Language Learning:1. Enhance Language Skills:Learning to code can greatly enhance language skills, especially in English. Coding involves writing instructions using a specific language, which naturally reinforces grammar, vocabulary, and syntax. It challenges learners to think critically and logically, improving their overall language proficiency.2. Engage in Interactive Learning:Coding provides an interactive and engaging way to learn English. Through coding exercises, learners can practice reading, writing, listening, and speaking skills in a stimulating environment. They can develop their language skills while simultaneously exploring the world of technology.3. Develop Problem-Solving Skills:Coding requires learners to break down complex problems into logical steps. This process helps develop problem-solving and critical thinking skills, which are essential in language learning. Learners can apply these skills to analyze and solve linguistic challenges, such as sentence structure or word usage.4. Foster Creativity and Innovation:Coding encourages learners to think creatively and fuel their imagination. This mindset can be transferred to English language learning. Learners can employ innovative approaches to express themselves using the language. They can design multimedia presentations, develop interactive language games, or create their own digital stories.5. Bridge Cultural Gaps:English is not only a language but also a doorway to understanding different cultures. Coding allows learners to connect with people from diverse backgrounds who share a common interest in technology. Collaborative coding projects, such as developing language learning applications, can bring learners together and bridge cultural gaps.6. Prepare for the Future:In an era of digitalization, coding skills are becoming increasingly sought after in the job market. Combining coding with English language proficiency equips learners with valuable skills for future careers. It opens doors to work in tech-related fields, digital marketing, software development, and more.Conclusion:Learning coding as a first-level skill in the context of English language learning offers a wide range of advantages. It enhances language skills, promotes interactive learning, develops problem-solving abilities, fosters creativity and innovation, bridges cultural gaps, and prepares learners for future job opportunities. As the digital world continues to evolve, the importance of combining coding and English language skills cannot be overstated. Therefore, it is crucial to emphasize the inclusion of coding in English language education and foster a generation of learners who are proficient in both.。

二进制输入RS编码中英文翻译

Binary-Input RS EncoderThe Binary-Input RS Encoder block creates a Reed-Solomon code with message length K and codeword length N. You specify both N and K directly in the dialog box. The symbols for the code are binary sequences of length M, corresponding to elements of the Galois field GF(2M), where the first bit in each sequence is the most significant bit. Restrictions on M and N are given in the section Restrictions on the M and the Codeword Length N below. The difference N-K must be an even integer. The input and output are binary-valued signals that represent messages and codewords, respectively. The input must be a frame-based column vector whose length is an integer multiple of M*K. For more information on representing data for Reed-Solomon codes, see the section Integer Format (Reed-Solomon only)." The default value of M is the smallest integer that is greater than or equal to log2(N+1), that is, ceil(log2(N+1)). If N is less than 2M-1, the block uses a shortened Reed-Solomon code. Each M*K input bits represent K integers between 0 and 2M-1. Similarly, each M*N output bits represent N integers between 0 and 2M-1. These integers in turn represent elements of the Galois field GF(2M). An (N,K) Reed-Solomon code can correct up to floor((N-K)/2) symbol errors (not bit errors) in each codeword.Specifying the Primitive PolynomialYou can specify the primitive polynomial that defines the finite field GF(2M), corresponding to the integers that form messages and codewords. To do so, first select the box next to Specify primitive polynomial. Then, in the Primitive polynomial field, enter a binary row vector that represents a primitive polynomial over GF(2) of degree M, in descending order of powers. For example, to specify the polynomial ,enter the vector [1 0 1 1]. If you do not select the box next to Specify primitive polynomial, the block uses the default primitive polynomial of degree M = ceil(log2(N+1)). You can display the default polynomial by entering primpoly(ceil(log2(N+1))) at the MATLAB prompt.Restrictions on the M and the Codeword Length N The restrictions on the degree M of the primitive polynomial and the codeword length N are as follows:If you do not select the box next to Specify primitive polynomial, N must lie inthe rangemust lie in the range .If you do select the box next to Specify primitive polynomial, N must lie in therange and M must lie in the range .Specifying the Generator PolynomialYou can specify the generator polynomial for the Reed-Solomon code. To do so, first select the box next to Specify generator polynomial. Then, in the Generator polynomial field, enter an integer row vectorwhose entries are between 0 and 2M-1. The vector represents a polynomial, in descending order of powers, whose coefficients are elements of GF(2M) represented in integer format. See the section Integer Format (Reed-Solomon only) for more information about integer format. The generator polynomial must be equal to a polynomial with a factored form, where a is the primitive element of the Galois field over which the input message is defined, and b is a non-negative integer. If you do not select the box next to Specify generator polynomial, the block uses the default generator polynomial, corresponding to b=1, for Reed-Solomon encoding. You can display the default generator polynomial by typing rsgenpoly(N1,K1), where N1=2^M-1 and K1=K+(N1-N), at the MATLAB prompt, if you are using the default primitive polynomial. If the Specify primitive polynomial box is selected, and you specify the primitive polynomial specified as poly, the default generator polynomial is rsgenpoly(N1,K1,poly).Binary-Output RS DecoderThe Binary-Output RS Decoder block recovers a binary message vector from a binary Reed-Solomon codeword vector. For proper decoding, the parameter values in this block should match those in the corresponding Binary-Input RS Encoder block. The Reed-Solomon code has message length K and codeword length N. You specify both N and K directly in the dialog box. The symbols for the code are binary sequences of length M, corresponding to elements of the Galois field GF(2M), where the first bit in each sequence is the most significant bit. Restrictions on M and N are described in the section Restrictions on the M and the Codeword Length N. The difference N-K must be an even integer. The input and output are binary-valued signals that represent messages and codewords, respectively. The input must be a frame-based column vector whose length is an integer multiple of M*K. The output is a frame-based column vector whose length is the same integer multiple of M*N. For more information on representing data for Reed-Solomon codes, see the section Integer Format (Reed-Solomon only)." The default value of M is ceil(log2(N+1)), that is, the smallest integer greater than or equal to log2(N+1). You can change the value of M from the default by specifying the primitive polynomial for GF(2M), as described in the section Specifying the Primitive Polynomial below. If N is less than 2M-1, the block uses a shortened Reed-Solomon code. You can also specify the generator polynomial for the Reed-Solomon code, as described in the section Specifying the Generator Polynomial. Each M*K input bits represent K integers between 0 and 2M-1. Similarly, each M*N output bits represent N integers between 0 and 2M-1. These integers in turn represent elements of the Galois field GF(2M). The second output is a vector of the number of errors detected during decoding of the codeword. A -1 indicates that the block detected more errors than it could correct using the coding scheme. An (N,K) Reed-Solomon code can correct up to floor((N-K)/2) symbol errors (not bit errors) in each codeword. You can disable thesecond output by clearing the box next to Output port for number of corrected errors. This removes the block's second output port.Integer-Input RS EncoderThe Integer-Input RS Encoder block creates a Reed-Solomon code with message length K and codeword length N. You specify both N and K directly in the block dialog. The symbols for the code are integers between 0 and 2M-1, which represent elements of the finite field GF(2M). Restrictions on M and N are described in the section Restrictions on M and the Codeword Length N below. The difference N - K must be an even integer. The input and output are integer-valued signals that represent messages and codewords, respectively. The input must be a frame-based column vector whose length is an integer multiple of K. The output is a frame-based column vector whose length is the same integer multiple of N. For more information on representing data for Reed-Solomon codes, see the section Integer Format(Reed-Solomon only)." The default value of M is the smallest integer that is greater than or equal to log2(N+1), that is, ceil(log2(N+1)). You can change the value of M from the default by specifying the primitive polynomial for GF(2M), as described in the section Specifying the Primitive Polynomial following. If N is less than 2M-1, the block uses a shortened Reed-Solomon code. An (N, K) Reed-Solomon code can correct up to floor((N-K)/2) symbol errors (not bit errors) in each codeword.Specifying the Primitive PolynomialYou can specify the primitive polynomial that defines the finite field GF(2M), corresponding to the integers that form messages and codewords. To do so, first check the box next to Specify primitive polynomial. Then, in the Primitive polynomial field, enter a binary row vector that represents a primitive polynomial over GF(2) of degreeM, in descending order of powers. For example, to specify the polynomial, enter the vector [1 0 1 1].If you do not select the box next to Specify primitive polynomial, the block uses the default primitive polynomial of degree M = ceil(log2(N+1)). You can display the default polynomial by entering primpoly(ceil(log2(N+1))) at the MATLAB prompt.Restrictions on M and the Codeword Length N The restrictions on the degree M of the primitive polynomial and the codeword length N are as follows:If you do not select the box next to Specify primitive polynomial, N must lie inthe rangeIf you do select the box next to Specify primitive polynomial, N must lie in therange and M must lie in the rangeSpecifying the Generator PolynomialYou can specify the generator polynomial for the Reed-Solomon code. To do so, first select the box next to Specify generator polynomial. Then, in the Generator polynomial field, enter an integer row vector whose entries are between 0 and 2M-1. The vector represents a polynomial, in descending order of powers, whose coefficients are elements of GF(2M) represented in integer format. See the section Integer Format (Reed-Solomon only) for more information about integer format. The generator polynomial must be equal to a polynomial with a factored formwhere a is the primitive element of the Galois field over which the input message is defined, and b is an integer. If you do not select the box next to Specify generator polynomial, the block uses the default generator polynomial, corresponding to b=1, for Reed-Solomon encoding. You can display the default generator polynomial by typing rsgenpoly(N1,K1), where N1 = 2^M-1 and K1 = K+(N1-N), at the MATLAB prompt, if you are using the default primitive polynomial. If the Specify primitive polynomial box is selected, and you specify the primitive polynomial specified as poly, the default generator polynomial is rsgenpoly(N1,K1,poly).Integer-Output RS DecoderThe Integer-Output RS Decoder block recovers a message vector from aReed-Solomon codeword vector. For proper decoding, the parameter values in this block should match those in the corresponding Integer-Input RS Encoder block.The Reed-Solomon code has message length K and codeword length N. You specify both N and K directly in the block dialog. The symbols for the code are integers between 0 and 2M-1, which represent elements of the finite field GF(2M). Restrictions on M and N are described in the section Restrictions on M and the Codeword Length N following. The difference N - K must be an even integer.The input and output are integer-valued signals that represent messages and codewords, respectively. The input must be a frame-based column vector whose length is an integer multiple of K. The output is a frame-based column vector whose length is the same integer multiple of N. For more information on representing data for Reed-Solomon codes, see the section Integer Format (Reed-Solomon only)."The default value of M is ceil(log2(N+1)), that is, the smallest integer greater than or equal to log2(N+1). You can change the value of M from the default by specifying the primitive polynomial for GF(2M), as described in the section Specifying the Primitive Polynomial below. If N is less than 2M-1, the block uses a shortened Reed-Solomon code.You can also specify the generator polynomial for the Reed-Solomon code, as described in the section Specifying the Generator Polynomial.An (N, K) Reed-Solomon code can correct up to floor((N-K)/2) symbol errors (not bit errors) in each codeword.The second output is the number of errors detected during decoding of the codeword. A -1 indicates that the block detected more errors than it could correct using the coding scheme. An (N,K) Reed-Solomon code can correct up tofloor((N-K)/2) symbol errors (not bit errors) in each codeword.You can disable the second output by clearing the box next to Output number of corrected errors. This removes the block's second output port.The sample times of the input and output signals are equal.二进制输入RS编码二进制输入的RS编码器的结构创建一个消息长度为k和码字长度n的Reed - Solomon码。

diseases of unstable repeat expansion-research progress-2

• Methylation of the C (CGG) due to mispaired Cs in secondary structures, are templates for methylation. • Methylation of the promoter is accompanied (reason unknown), leading to lack of transcription initiation.
HD (Huntingtin)
11-34
6-39 15-24 13-36
40-121
40-82 32-200 61-84
SCA1
(CAG)n
SCA1 (ataxin Transcription 1)
SCA2
(CAG)n
SCA2 (ataxin RNA metabolism 2)
SCA3
(CAG)n
SCA3 (ataxin Deubquitylating 3)
When frataxin level is low, Fe-S cluster containing proteins such as aconitase are reduced.
Fragile X syndromeloss of function
Fragile X syndrome
X linked disease, 1:4000 in males Clinical manifestations • Cognitive difficulties
•Fragile X
•Friedrich’s ataxia
Inheritance patterns and clinical features of unstable repeat expansion disorders

5G移动通信技术考试题库及答案(完整版)

1、关于5G AAU A9611，下面说法正确的是：A.A9611是5G NR低频AAU，支持64T64RB.A9611是5G NR低频AAU，支持128T128RC.A9611是5G NR高频AAU，支持64T64RD.A9611是5G NR高频AAU，支持128T128R答案：A2、NR2.0产品中V2.00.20.*版本PCI规划原则有A.PCI模三不等B.PCI模30不等C.PCI模11不等D.PCI不能冲突混淆E.邻区PCI满足相关性<0.1和泄漏比小于-20dB答案：ABDE3、RAN切分后，CU和DU之前的接口是（）A.F1B.X2C.S1D.F2答案：A4、5G室分建设的特征的数字化指的是（）A.网络结构数字化B.运维数字化C.业务数字化D.建设数字化答案：ABC5、5G与4G室分网络差异性A.频段不同B.TDD与FDD区别C.终端相同D.MIMO相同答案：D6、以下哪些是2.0产品A.AAU9611B.AAU9601C.V9200D.V9600答案：AC7、关于RBM的功能，下面说法正确的是：A.用于BBU与EPC或5GC之间的链路交换B.用于BBU之间的X2连接，也可以用于S1连接、时钟连接C.用BBU与AAU/RRU之间桥接和汇聚D.用于提升BBU计算能力答案：C8、下面Preamble序列格式属于长格式的有：A.格式0B.格式1C.格式2D.格式3答案：ABCD9、中移NR2.6G采用5ms单周期的帧结构，主要是为了：A.增强上行覆盖B.增强上行容量C.增强下行容量D.与TD-LTE同步，避免异系统干扰。

答案：C10、NR系统中下行物理信号有哪些A.解调参考信号（Demodulation reference signals，DM-RS）B.相位跟踪参考信号（Phase-tracking reference signals，PT-RS）C.信道状态信息参考信号（channel-state information reference signal，CSI-RS）D.主同步信号（Primary synchronization signal，PSS）E.辅同步信号(Secondary synchronization signal，SSS）答案：ABCDE11、Option 7方案相对于Option 3的优势在于（）A.改动小，投资少，建网速度快B.支持5G 5GC引入的新业务C.支持语音业务回落到2G和3GD.语音业务对NR覆盖无要求答案：B12、AAU作为具备64通道天线阵列的AAU，可以如何安装A.下倾安装B.上倾安装C.水平安装D.倒装答案：AB13、使用1/4英寸馈线连接GPS天线，使用一个功率放大器+1分4功分器最远支持多少米？A.83mB.120mC.150mD.180mE.230m答案：D14、覆盖测试站点选择需要满足哪些要求？A.优选开阔区无遮挡的郊区；B.能满足纵向横向拉远的需求；C.有共站4G站点方便进行对比业务测试；D.有合适建筑物方便室内覆盖对比；答案：ABCD15、NGM容器的描述正确的是A.基站NG口协议处理容器B.处理UE的信令连接功能C.用于检查基站的AAU输出功率D.docker平台容器答案：A16、SA场景需要规划的邻区，一般包括：A.4G->5G的系统间邻区B.5G->4G的系统间邻区C.5G->5G的系统内邻区D.5G->2G的系统间邻区答案：ABC17、V9200传输一般用何种规格的光模块A.1.25GB.6GC.10GD.25G答案：D18、推荐户外设备端口采用哪种防水方式进行防水？A.1+3+3B.热缩管C.冷缩管D.防水盒答案：ABCD19、3GPP定义的5G核心网架构的接口中，UE与AMF的接口名称为？A.N1B.N2C.N3D.N4答案：A20、NR系统中上行物理信号有哪些A.解调参考信号（Demodulation reference signals，DM-RS）B.相位跟踪参考信号（Phase-tracking reference signals，PT-RS）C.探测参考信号（Sounding reference signals，SRS）D.信道状态信息参考信号（channel-state information reference signal，CSI-RS）答案：ABC21、基站开通过程中VSW单板固定在1槽位，其调试地址为A.192.254.1.16B.192.254.2.16C.192.254.1.32D.192.254.2.80答案：A22、关于V9200的VF板的功能，下面说法正确的是：A.与结构子系统一起实现所有复合子系统的互联B.RS232，RS485监控监控和干接点功能C.检测和控制系统温度D.监控、控制和报告风扇状态答案：CD23、NR核心网中用于会话管理的模块是A.AMFB.SMFC.UDMD.PCF答案：B24、5G试验网阶段测试优化工作所需工具主要包含？A.LMTB.罗德扫频仪C.DSPMonitorD.CRTE.CXT答案：ABCDE25、gnodeB与ng-enb之间的接口是（）A.X2B.XnC.XxD.NG答案：B26、双连接信令流程中常见的SN流程有A.Secondary Node AdditionB.Secondary Node ModificationC.Secondary Node ReleaseD.Secondary Node Change答案：ABCD27、一块vBPC5单板最多支持几个100M频宽小区？A.1B.2C.3D.4答案：C28、5G系统中终端共有哪些状态？A.IdleB.ConnectedC.Inactive答案：ABC29、AAU直流电源线需要做几处接地A.1处B.2处C.3处D.视电源线长度而定答案：D30、5G有哪些关键应用场景A.mMTCB.eMBBC.URLLCD.NB-IOT答案：ABC31、NR中物理层小区ID共有（）个A.504B.168C.1008D.336答案：C32、NSA连接态移动性能管理包括A.LTE系统内移动，SN增加B.LTE系统内移动，SN释放C.NR系统内移动，SN变更D.NR系统内移动，PSCell变更答案：ABCD33、5G中不同用户选择各自方向上（）的波束作为最佳子波束A.用户最少B.干扰最小C.信号强度最好D.用户最多答案：C34、根据不同的供电距离，AAU可以选用的电源线有：A.2*4mm2B.2*6mm2C.2*10mm2D.2*16mm2答案：CD35、5G2.5ms双周期帧结构支持的最大广播波束为（）个A.2B.4C.7D.8答案：C36、64TR产品推荐应用于以下哪些场景：A.密集城区B.一般城区C.郊区D.农村答案：AB37、SA组网模式下，控制面切换时延定义是（）A.从Measurement report后的第一个携带HO标识的RRC Connection ReconfigurationB.从Measurement report后的第一个携带HO标识的RRC Connection ReconfigurationC.从UE发送Measurement report到UE发送MSG2的时延D.从UE发送Measurement report到UE发送MSG1的时延答案：A38、关于V9200单板配置原则，下面说法错误的是：A.VSW为必配单板，配置VSWc1可支持2/3/4/5GB.VBP根据需要配置，VBPc1为2/3/4G基带板，VBPc2为5G基带板C.VGC为比配单板，用于提高BBU计算能力D.支持两块VPD单板主备配置，该配置下同时支持12路外部干接点输入答案：ACD39、关于V9200的VSW板的功能，下面说法正确的是：A.与结构子系统一起实现所有符合子系统的互联B.完成主控、系统时钟、IQ数据交换、信令处理功能C.基带数据处理，完成虚拟化基站的业务D.实现计算功能及存储功能答案：B40、配置小区需要和射频AAU进行关联，那么下列哪些配置可以关联到AAU相关配置A.BPFunctipnB.SectorfunctioC.BPPOOLfunctionD.切片答案：BC41、关于S9100的功能，下面说法正确的是：A.用于BBU与EPC或5GC之间的链路交换B.用于BBU之间的X2连接，也可以用于S1连接、时钟连接C.用BBU与AAU/RRU之间桥接和汇聚D.用于提升BBU计算能力答案：B42、传统室分网络5G演进对DAS系统进行改造时，需要替换的无源器件有（）A.馈线B.合路器C.耦合器D.功分器E.天线答案：BCDE43、关于5G AAU A9815，下面说法正确的是：A.A9815是5G NR低频，支持8T8RB.A9815是5G NR低频，支持4T4RC.A9815是5G NR高频，支持8T8RD.A9815是5G NR高频，支持4T4R答案：D44、DCPD10输出端额定电流为A.25AB.30AC.42AD.50A答案：AC45、关于V9200的VBP板的功能，下面说法正确的是：A.与结构子系统一起实现所有符合子系统的互联B.完成主控、系统时钟、IQ数据交换、信令处理功能C.基带数据处理，完成虚拟化基站的业务D.实现计算功能及存储功能答案：C46、V9200可以支持哪些制式：A.5G NRB.4G LTEC.3G UMTSD.2G GSM答案：ABCD47、docker info命令的使用描述正确的是A.在基带单板上使用用于检查docker容器运行状态B.在主控单板上使用用于检查docker容器运行状态C.在AAU上使用用于检查docker容器运行状态D.查看VBPC5和状态答案：B48、5GSA组网方式下BBU使用单板有A.VSWc2B.vbpc1C.vBPc5D.vFCE.vPD答案：49、关于V9200的VEM板的功能，下面说法正确的是：A.与结构子系统一起实现所有符合子系统的互联B.完成主控、系统时钟、IQ数据交换、信令处理功能C.基带数据处理，完成虚拟化基站的业务D.RS232，RS485监控监控和干接点功能答案：D50、Option2组网的优势有哪些A.对现有2G/3G/4G网络无影响B.不影响现网2G/3G/4G用户C.可快速部署，直接引入5G新网元，不需要对现网改造D.引入5GC，提供5G新功能新业务答案：ABCD51、一个直流供电的BBU，在机柜中一共需要多大空间A.2UB.3UC.4UD.5U答案：D52、传统DAS建设5G网络主要困难有（）A.有源设备馈入改造B.无源设备需要改造C.工程难度大D.天线点位利旧答案：ABCD53、传统DAS建设5G网络主要困难有（）A.有源设备馈入改造B.无源设备需要改造C.工程难度大D.天线点位利旧答案：ABC54、CPE上电可以正常进行业务的标志为？A.上电即可B.NR2.0能ping通192.254.1.16后3到5分钟C.NR2.0能ping通192.254.1.48后3到5分钟D.NR2.0能ping通192.254.1.200后3到5分钟答案：C55、AAU9611A S26支持2.6G频段，对于下列描述正确的是A.支持100M5G频宽B.支持160M5G频宽C.支持1各100M5G频宽和60M4G频宽D.支持4个eCPRI接口E.支持1个eCPRI接口和3个CPRI接口答案：ACE56、CU-DU分离不包含以下哪种场景A.DRAN+DUB.CU+DUC.CU+DU集D.DU+DU答案：A57、5G网络中3.5G对应频段是（）A.n70B.n78C.n80D.n85答案：B58、5G网络中su6G不可配置的带宽为（）A.5MB.15MC.25MD.80M答案：C59、TS 38.211 ON NR是下面哪个协议（）A.Physical channels and modulationB.NR and NG-RAN Overall DescriptionC.Radio Resource Control (RRC) ProtocolD.Base Station (BS) radio transmission and reception 答案：A60、5G网络控制信道编码方式为（）A.LDPC(low-density parity-check)码B.Polar码C.Turbo码D.256QAM答案：B61、关于5G网络SCS描述不正确的是（）A.SCS 30khz对应的每时隙符号数为14B.SCS 30khz对应的每帧时隙数为20C.SCS 30khz对应的每子帧时隙数为2D.SCS 30khz对应的每帧时隙数为40答案：D62、NR的新RRC状态不包括（）A.RRC CONNECTEDB.RRC INACTIVEC.RRC ACTIVED.RRC IDLE答案：C63、不属于5G网络的信道或信号是（）A.PDSCHB.PUSCHC.PDCCHD.PCFICH答案：D64、协议已经定义5G基站可支持 CU和DU分离部署架构，在（）之间分离A.RRC和PDCPB.PDCP和RLCC.RLC和MACD.MAC和PHY答案：B65、Sub3G~Sub6G最大SS/PBCH BLOCK数目为（）个A.4B.8C.32D.64答案：B66、短序列为NR新增的PRACH Preamble格式，R15共9种格式，其中C2格式最大小区覆盖半径为（）A.9.29kmB.5.35kmC.3.86kmD.7.56km答案：A67、NR中定义一个子帧时间长度是多长A.0.5msB.1msC.5msD.10ms答案：B68、对于SCS30kHz,BS侧100MHz带宽可以使用的RB数最多有几个？A.50B.100C.272D.273答案：D69、用户多天线蜂值体验特性提升的用户娜个方向体验？A.下行B.上行C.上下行答案：C70、当采用Option 3X架构时，对应的是哪一种承载类型？A.MCG BearerB.MCG Split BearerC.SCG BearerD.SCG Split Bearer答案：D71、gNB配置一个上下行解耦小区,CU上配置的小区数加上DU上配置的小区数共计几个？A.1B.2C.3D.4答案：D72、上下行解耦场景，RRU用于服务于？A.上行小区B.下行小区C.上行和下行小区答案：A73、NR上行用户初传数据传输通过什么来向gNB请求？A.BSRB.PHRC.SRD.ACK/NACK答案：C74、UE计算发射功率时，估计的路损是哪个方向的？A.UplinkB.Downlink答案：A75、3GPP达成结论NR基本业时间同步精度要求达到參少？A.优于3us（±1.5us）B.优于5us（±2.5us）C.优于1us（±0.5us）D.优于10us（±5us）答案：A76、下行SRS权与PMI权自适应中，用于判断切换阈值的SRS SNR是来自？A.上行B.下行C.上行下行鄱可以答案：A77、关于对时服务，以下描述不正确的是？A.NTP服务器对时端囗号默认123、可配置B.GPS可以作为UTC时间同步源，优选GPSC.NTP对时周期设越短越好，保证基站时间和NTP服务器始终一敗D.支持配多个NTP服务器主备冗余答案：C78、NR 3GPP R15 序列长度为139的PRACH格式一共有几种？A.9B.4C.6D.8答案：A79、下行DMRS大支持多少个天选端口配置？A.4B.6C.8D.12答案：D80、以下个信号在NR中主要用于相位跟踪和补偿？A.CRS-RSB.PT-RSD.SRS答案：B81、用户多天线峰值体验特性未激活时，用户获得什么样的性能?A.用户无法获得数据服务B.用户只能获得单流性能C.用户仍然可以获得多流性能答案：B82、下行干扰随机化调度资源分配起始位置PCI模几A.3B.4C.30D.6答案：A83、eNB下发测量控制测量NR的测量类型是什么?A.B1B.B2C.B3D.B4答案：A84、对于SCS 120KHz, 一个子帧包含几个slot?A.2B.4C.6D.8答案：D85、NR 3GPP R15序列长度为139的PRACH格式一共有几种A.3B.5C.7D.9答案：D86、UE计算发射功率时，估计的路损是?A.上行B.下行C.上行和下行D.以上都不对答案：B87、以下信道或信号中，发射功率跟随PUSCH的是?A.PRACHB.PUSCHC.PUCCHD.SRS答案：D88、以下哪个信号在NR中主要用于相位跟踪和补偿A.PT-RSB.CRSC.DMRSD.PDCCH89、LTE+NR做NSA DC时，LTE可以做CA，LTE下行最多可以支持几个CCA.2CCB.3CCC.4CCD.5CC答案：D90、对MCG Split Bearer/SCG Split Bearer设置分流模式，哪种配置是可以进行动态分流的A.SCGB.MCGC.SCG_AND_MCGD.以上都不对答案：C91、关于对时服务，不正确的是?A.NTP服务器对时端口默认123，可配置B.GPS可以作为UTC时间同步源，优先GPSC.NTP对时周期设置越短越好，保证基站时间和NTP服务器时间始终一致D.支持多个NTP服务器主备冗余答案：C92、下行SRS权与PMI权自适应中，用于判断切换阈值的SRS SNR是来自A.上行B.下行C.上行下行都可以D.以上都不对答案：A93、不管对于上行业务，还是下行业务，用户峰值体验最大流数和收发天线的关系是?A.发射天线数B.接受天线数C.min (发射天线数，接受天线数)D.max (发射天线数，接受天线数)答案：C94、X2 IPPM的用途是A.检测X2接口控制面IP地址配置正常B.检测X2接口的丢包、时延、抖动等信息C.检测X2接口用户面IP地址配置正常D.检测X2接口通断答案：B95、36.873协议UMA模式与cost231-Hata模式的关键差异A.多了w和h因子B.多了基站高度答案：A96、5G是由ITU定义的第五代移动通信标准，它的正式名字是什么A.IMT-2000B.IMT-2005C.IMT-2010D.IMT-2020答案：D97、5G建网初期要达到随时随地多少Mbps的体验速率？A.50MbpsB.100MbpsC.1GbpsD.10Gbps答案：B98、NR中定义的一个子帧时间长度是多长？A.0.5msB.1msC.5msD.10ms答案：B99、对于SCS 30kHz，BS侧100MHz带宽可以使用的RB数最多有几个？A.50B.100C.272D.273答案：D100、当采用Option3X架构时，对应的是哪一种承载类型？A.MCG BearerB.MCG Split BearerC.SCG BearerD.SCG Split Bearer答案：D101、NSA组网，eNodeB与gNodeB之间的接口叫什么？A.UUB.X2C.XnD.S1答案：B102、gNB配置一个上下行解耦小区，CU上配置的小区数加上DU上配置的小区数共计几个？A.1B.2C.3D.4答案：D103、5G PCI有多少个？A.200B.504C.1008D.1024答案：C104、5G支持的新业务类型不包括A.eMBBB.URLLCC.eMTCD.mMTC答案：C105、3GPP规范的5G UMa/UMi/RMa等LOS路损模型都是双截距的路损模型，下面因素和BreakPoint不相关的有：B.街道宽度C.天线高度D.移动台高度答案：B106、对FR1频段（450MHz~6000MHz）支持的信道带宽描述正确的是：A.最小5MHz ，最大100MHzB.最小5MHz ，最大400MHzC.最小50MHz ，最大100MHzD.最小50MHz ，最大400MHz答案：A107、5G广播信道 CBand和2.6G频段，最大支持多少波束扫描？A.5B.6C.7D.8答案：D108、5G链路预算时，华为AAU设备考虑的馈线损耗是多少dB？B.0.5C.1D.2答案：A109、5G链路预算时，华为AAU设备考虑的馈线损耗是多少dB？A.2515-2615MHzB.3300-3400MHzC.3400-3500MHzD.3500-3600MHz答案：C110、在5G中PDSCH最大调制是（）A.128QAMB.512QAMC.64QAMD.256QAM答案：D111、在5G中PDCCH共有多少种DCI格式（）A.8B.24C.4D.16答案：A112、在5G技术中，用于提升接入用户数的技术是（）A.MassiveMIMOB.1mcTTIC.SOMAD.MassiveCA答案：A113、在5G的可用频段中，哪个频段更适合用于覆盖海量的物类连接？A.C波段C.毫米波答案：D114、以下商用案例，哪个属于行业领域类场景？A.物流车辆编队B.灾害或者恐怖事件发生时，保证现场人员以及救援人员的稳定通讯C.沉浸式娱乐（VR/AR游戏、多视角UHDV.D.移动办公（高清视频通讯、云桌面.答案：A115、以下哪种业务属于uRLLC场景应用？（）A.物流跟踪B.车载多媒体C.3D全息D.远程驾驶答案：D116、以下哪种业务属于uRLLC？A.车联网B.抄表业务C.高速上网D.高清视频答案：A117、以下哪种信号是仅仅用于高频的？（）A.PTRSB.SRSC.DMRSD.CSI-RS答案：A118、以下哪种多址接入技术是5G新提出的？A.FDMAB.CDMAC.SCMAD.TDMA答案：C119、以下哪种场景无法使用毫米波？A.自回传，有电即有站B.广覆盖C.容量提升D.家庭宽带接入答案：B120、以下哪种SSB必须在SSraster上（）A.用于NRScell接入的SSBB.用于测量的SSBC.用于NRPcell接入的SSBD.用于PScell接入的SSB答案：C121、以下哪种DCIFormat必须与Format1-0size相等（）。

oracleweblogic认证考试

oracleweblogic认证考试Oracle 1z0-523Oracle Application Grid 11g EssentialsQUESTION NO: 1Which interface provides the ability to see changes in real-time as they occur?A. ConcunentMapB. java. util. AbstractMapC. ObservableMapD. InvocableMapAnswer: CExplanation:QUESTION NO: 2Coherence provides the ideal infrastructure for building _____ services, and the ______ applications.A. Data Grid, Client and Server basedB. Ouster, Client and Server basedC. Data Grid, DNS basedD. Cloud cluster, Client and Server basedAnswer: AExplanation:QUESTION NO: 3Node Manager is a WebLogic Server ______ that enables you to start, shut down, and restart Administration Server and Managed Server instances from a remote location.A. InstanceB. UtilityC. DestinationD. OusterAnswer: BWhich two Oracle products come pre-packaged with Oracle's JRockit JDK?A. Oracle WebLogic ServerB. Oracle CoherenceC. Oracle DatabaseD. Oracle Real Time Operations ControlAnswer: A,BExplanation:QUESTION NO: 5Which three of the following are considered Fixed Asset Depreciation Rule Components?A. International Depreciation MethodsB. HeaderC. Annual RulesD. Rule ConventionsE. Predefined Depreciation MethodsAnswer: B,C,DExplanation:QUESTION NO: 6As a best practice, what would you change in the following command line to create successful domain template "My WebLogic Domain"?Pack -domain=C: \oracle\user_projects\domains\mydomain -template=C:\oracle\user_templates\mydomain -template_name="My WebLogic Domain"A. Pack -domain=C:\oracle\user__projects\domains\mydomain.dll - template=C:\oracle\user_templates\mydomain.jar -template_name="My WebLogic Domain"B. Pack-domain=C:\oracle\user_projects\domains\mydomain.jar - template=C:\oracle\userJ:emplates\mydomain -template_name=nMy WebLogic Domain"C. Pack -domain=C:\oracle\user_projects\domains\mydomain - template=C:\oracle\user_templates\mydornain.jar -template_name="My WebLogic Domain"D. Pack -domain=C:\oracle\user_projects\domains\mydomain.jar - template=C:\oracle\user_templates\mydomain.jar -template_name="My WebLogic Domain" Answer: CQUESTION NO: 7In a typical production environment, which server(s) hosts the application?A. Node ServerB. Administration ServerC. Managed ServerD. Configuration ServerAnswer: CExplanation:QUESTION NO: 8In a typical production environment, which server(s) hosts the application?A. Node ServerB. Administration ServerC. Managed ServerD. Configuration ServerAnswer: CExplanation:QUESTION NO: 9Which three data source integrations are provided by Coherence out of the box?A. TopLink Grid and TopLink EssentialsB. Java Persistence API (JPA)C. Open Database Connectivity (ODBC)D. File SystemE. Java Database Connectivity (JDBC)Answer: A,B,EExplanation:QUESTION NO: 10Which two statements are true about the Application Grid?A. Application Grid computing brings key industry-leading technologies like MS IIS and Grade WebLogic Server together.B. Application Grid computing promotes well architected sharing of resources.C. Application Grid computing is based on Oracle's RAC technology.D. Application Grid computing results in more predictable behavior through better Instrumentation and more optimal allocation of resources.Answer: B,DExplanation:QUESTION NO: 11Which statement is true about XpauseTarget in Oracle JRockit JVM?A. This option is supported by all type of Garbage collection modes.B. This option is only supported by Generational Garbage Collection mode.C. This option is only supported by Mark and Sweep Garbage Collection Model.D. This option is only supported by Dynamic Garbage Collection Model.Answer: DExplanation:QUESTION NO: 12Identify the feature of WebLogic JMS: If the message destination (5, not available at the moment the sages are being sent, either because of network problems or system failures, then the messages are saved on a local server instance, and are forwarded to the remote destination once it becomes available.A. Unit of WorkB. Store-and-ForwardC. Unit of OrderD. Distributed DestinationsAnswer: BExplanation:QUESTION NO: 13In Real Operations Insight, metrics are sent from the various WebLogic Suite components into Enterprise Manager for _____ and_____.A. OptimizationB. VisualizationC. AutomationD. CustomizationAnswer: A,CExplanation:QUESTION NO: 14When scaling Coherence from one to two cache servers, itwill not show the same scalability as two to four. Why?A. Coherence uses a more efficient TCMP algorithm going from two to four cache servers.B. When going from one to two cache servers, object backups are copied across servers so work is doubled, but going from two to four is a fixed amount of work.C. Near cache is enabled with a larger quorum thus performance is improved.D. All of the above.Answer: BExplanation:QUESTION NO: 15This is a special WebLogic Server instance included by the WebLogic Server Domains. It represents a central point from which you configure and manage all resources in the domain.A. Managed ServerB. Web ServerC. Administration ServerD. Node ServerExplanation:QUESTION NO: 16You are an Enterprise Architect in a large IT organization. Your organization has deployed applications on a variety of containers such as WLS, WebSphere, and JBoss.Why would you consider consolidating on a single type of container (instead of a mix)?A. Guarantee of higher application performance and reliability if the transactions are flowing between instances of the same container type.B. Easier to build a Shared Services infrastructure that canprovide best practices, tools and expertise around HA/Management... with a single type of container than a mix of multiple types.C. You'll save on hardware costs with a homogeneous environment.D. It's a necessary step in our move toward adopting SOA.Answer: BExplanation:QUESTION NO: 17Which two statements are true when a Coherence cluster member is lost?A. Remaining members recover by repartitioning the data across the remaining cluster members in parallel with normal request processing.B. Some latencies may be experienced due to higher priority of recovery.C. In flight operations may be lost.D. A system administrator must manually assist recovery of the lost data.Answer: A,BExplanation:QUESTION NO: 18Which two statements are true about Oracle JRockit Mission Control (JRMC)?A. JRMC is platform neutral. It supports most JVMs in market.B. JRMC is used for Deep visibility and analysis of single JVMs.Answer: C,DExplanation:QUESTION NO: 19Which Coherence caching pattern matches the sequence ofevents?1. Data is requested from the cache.2. The requested data does not exist in the cache (cache miss).3. The Coherence cache store is used to read data from the back-end persistent data source, and placed in the cache.4. Data requested from the cache is returned to the caller.A. Read ThroughB. Write ThroughC. Refresh AheadD. Write BehindAnswer: AExplanation:QUESTION NO: 20Which two are advantages of using WLS JMS instead of using a third-party JMS Provider (Tibco, Sonic, etc.)?A. JMS subsystem of WLS shares same JVM as core WLS application server, so application avoids the overhead of message serialization/de-serialization (necessary when using a 3rd party JMS provider with WLS)B. WLS JMS is always faster than 3rd party JMS providersC. Unified operations and management tools across Application Server and JMS Provider will help with manageability and diagnosticsD. WLS JMS more compliant with JMS spec than 3rd party vendorsAnswer: A,DExplanation:QUESTION NO: 21You are at the client site working with a WebLogic Administrator who has to type Username and Password eachtime he/she starts an instance of Oracle WebLogic server and is quite annoyed by it. Please suggest a secure and optimal way to reduce the typing of username password during server startup.A. Since Boot Identity file for server doesn't exist, you recommend creating a script file that can automate the task of entering username and passwordB. Since Boot Identity file for server doesn't exist you recommend reinstalling the serverC. Since Boot Identity file for server doesn't exist you recommend creating one as this file is referred for credentialsD. Since Boot Identity file for server doesn't exist, you recommend logging a support ticket with OracleAnswer: CQUESTION NO: 22Identify two correct statements to complete the sentence. In a Coherence implementation, it is a best practice to implement PortableObject on all customer objects because:A. It leverages Java's built-in serialization.B. It provides a more efficient serialization of the object.C. It allows the object to be shared across applications.D. It allows the object to be shared across programming platforms.Answer: A,CExplanation:QUESTION NO: 23Which two stand-alone products are also parts of Oracle Web logic Enterprise Edition offering?A. Oracle WebLogic Real TimeB. Oracle Internet Application ServerC. Oracle Application Development Framework (ADF)D. Oracle Enterprise Pack for EclipseExplanation:QUESTION NO: 24You are doing an environment assessment for a client that has invested in Oracle RAC for fault tolerance, load balancing, and scalability. The client also invested in clustered Oracle WebLogic Server. You notice that this client's environment is not integrated for active-active high availability deployment of applications.What will be your recommendation to achieve that?A. MetaLink to RACB. ClusterLink for RACC. TopLink for RACD. GridLink for RACAnswer: DExplanation:QUESTION NO: 25I guide users through the process of creating or extending a domain for their target environment: Identify me.A. Pack ToolB. Configuration WizardC. Auditing ProviderD. Node ManagerAnswer: BExplanation:QUESTION NO: 26Which two statements are true about the WebLogic Cluster?A. Clustered Servers capacity can be increased by adding new server instance to the cluster on an existing machine.B. Clustered Servers can be on a same or different machinewith same operating system onlyD. Clustered Servers can be on a same or different machine with same or different operating systemAnswer: A,BExplanation:QUESTION NO: 27Which two statements are true about interoperating with Oracle AQ JMS with Oracle WebLogic server?A. If you select a non-XA JDBC driver, you can use WebLogic AQ JMS in both local & global transactions.B. Oracle WebLogic Server requires a JDBC driver to communicate with the Oracle AQ JMS.C. Oracle WebLogic AQ JMS stand-alone client automatically participate in global transactions managed by Oracle WebLogic Server.D. If you select an XA JDBC driver, you can use WebLogic AQ JMS in both local and global transactions.Answer: B,DExplanation:QUESTION NO: 28With regard to the drivers behind Application Grid based computing, consider the following statements and indicate which are TRUE:I.data center complexity leads to a lack of predictability making it difficult if not impossible to guarantee quality of service.II. Data centers must do more with less and find a way to better utilize existing capacity.III. Growth means added complexityA. I and IIB. I and IIIC. II and IIID. I, II and IIIAnswer: DExplanation:QUESTION NO: 29Which product should be used along with Oracle Enterprise ManagerPacksfor Fusion Middleware for end-to-end visibility?A. Oracle Data Masking PackB. Oracle Real Application TestingC. Oracle Byte Code Instrumentation for Java (BCI4J)D. Oracle Real User Experience Insight (ORUEI)Answer: DQUESTION NO: 30Select three true statements regarding Coherence.A. Coherence provides stronger data management than an Application ServerB. Coherence provides better scale-out performance than an Application ServerC. Coherence provides better scale-out performance than a Database ServerD. Coherence provides better throughput thanaJMS messaging serverCoherence provides stronger configuration management than Grid ControlAnswer: A,B,CExplanation:QUESTION NO: 31Oracle Fusion Middleware Control runs as:A. A module in Oracle HTTP ServerB. A PIVSQL module in Oracle DatabaseC. An application in WebLogic Server Administration ServerD. An application in WebLogic Server Managed ServersAnswer: AExplanation:QUESTION NO: 32Identify the two optional WebLogic security providers in an Oracle WebLogic security realm.A. Authentication ProviderB. Adjudication ProviderC. Authorization ProviderD. Auditing ProviderAnswer: B,DExplanation:QUESTION NO: 33As an architect for ABC bank, you have been tasked to improve the performance of their online balance transfer application. Due to various mergers and takeovers, the bank has heterogeneous systems. Some applications are based on Java while others on either .net or C+ + . You would like to propose object serialization with Coherence to enable passing objects between these different language platforms.Which of the following options provides this capability?A. Standard Java serializationB. .Net Binary serializationC. Coherence Portable Object FormatD. Coherence ExternalizableLiteAnswer: CExplanation:QUESTION NO: 34A _____ is a collection of components managed by FusionMiddleware Control. It can contain Oracle WebLogic Server domains, one Administration Server, one or more Managed Servers, clusters, and the Oracle Fusion Middleware components that are installed, configured, and running in the domain.A. farmB. beanC. unitD. nodeAnswer: AExplanation:QUESTION NO: 35Integration between______ with "multi data sources' and _________ is defined as Gridlink for RAC (Real Application Clusters).A. Oracle WebLogic Server; Oracle DatabaseB. Oracle WebLogic Server clusters; Oracle DatabaseC. Oracle WebLogic Server clusters; Oracle Database RACD. Oracle OC4J; Oracle Database RACAnswer: CExplanation:QUESTION NO: 36Which console allows me to choose between stopping a WebLogic managed server immediately versus quiescing it and stopping the server when all requests complete?A. Grid Control ConsoleB. Fusion Middleware ConsoleC. WebLogic Administration ConsoleD. CAMM ConsoleAnswer: CExplanation:QUESTION NO: 37Which Oracle WebLogic Server feature would you recommend to your clients to enable a stand-alone message producer, or a group of producers acting as one with respect to the processing order?A. Connection FactoryB. Messaging BridgeC. Unit-of-OrderD. Store-and-ForwardAnswer: CExplanation:Name three attributes used to configure a multi-data source in Oracle WebLogic.A. Statement Cache TypeB. Logging Last ResourceC. Algorithm TypeD. Failover Request if BusyE. JNDI NameAnswer: A,B,EExplanation:QUESTION NO: 39At run time, each Oracle WebLogic Server instance in a given domain creates an in-memory representation of the configuration described in this document.A. mds-mbeans.xmlB. config.xmlC. policy.xmlD. data.xmlAnswer: BExplanation:QUESTION NO: 40Which two statements are true about Oracle ActiveCache?A. It supports very large data-sets such as the result-sets from large search queries to be held in memory.B. It provides a set of management tools that enables automation of configuration.C. It provides enhanced visibility across the entire application infrastructure.D. It significantly increases the performance of Web-based applications with no code change.Answer: A,DExplanation:Identify architecturally where in an application, Coherence stack will be used.A. Coherence resides locally on the machines of all remote application users.B. Coherence resides between remote users and the Web tier.C. Coherence resides between the Web tier and application tier.D. Coherence resides between the application tier and data tier.Answer: CExplanation:QUESTION NO: 42You want to use the Coherence Java APIs to directly cache POJOs. Consider this snippet of code: NamedCache cache - CacheFactory.getCache("mycache");cache.put(new Integer(l)f "hello");cache.put(T, "hi");cache.put(new Long(ll), "hey");This code inserts three objects into the cache. Why?A. hashCode() and equals() method for each object type is different so a different key is usedB. Each object value string is different so a different value is inserted on each putC. equals () and compare() method is different for each putD. POF needs to be implemented for this to work properlyAnswer: AExplanation:QUESTION NO: 43ABC Company has approximately 150,000 products in their catalog and wants to put these within a Coherence cache to improve performance and access times of their existing JEE application without too much change to existing code. There are a number of servlets that get the same product information multiple times within a page. There are also a number of server-basedhave small changes which need to be updated during the day.What would be the most appropriate caching scheme to use?A. Near cacheB. Distributed cacheC. Local cacheD. Replicated cacheAnswer: CExplanation:QUESTION NO: 44Which of these is an available Oracle WebLogic Message Bridge attribute?A. XA EnabledB. Connection URLC. Local JNDI nameD. Quality of ServiceAnswer: CExplanation:QUESTION NO: 45See the build instructions for managing Coherence via JMX and put the steps in order.1.Update set-env.cmd (or set-env.sh if you are building on UNIX) to reflect your system environment2.Open a command shell and execute set-env.cmd (or source set-env.sh if you are building on UNIX)3. Run ant build4.Deploy the jmx-console.war file found under the build directory to your application server. Be sure to start your application server JVM with the necessary Coherence Management Framework overrides. For example: -Dtangosol.coherence.management=all5.To remove build artifacts from your file system, run 'ant clean'.B. 1,3,2,4,5C. 1,2,3,5,4D. 2,1,3,4,5Answer: AExplanation:QUESTION NO: 46Which two statements are true about the Oracle Enterprise Manager (OEM)?A. OEM can do management and monitoring across multiple WLS DomainsB. OEM is a unified solution for management and monitoring across entire architecture - Web Tier, App Tier & DB TierC. OEM is focused solely on Oracle solutions, cannot manage 3rd party productsD. OEM includes tools to configure the operating systemAnswer: A,BExplanation:QUESTION NO: 47Oracle JRockit JVM uses -Xns option to set nursery size when the generational garbage collection model is used. Which two JVM properties are affected by changing its size?A. Compaction ratio limitB. garbage collection frequencyC. garbage collection timesD. fragmentation heap sizeAnswer: B,CExplanation:QUESTION NO: 48Which two statements are TRUE regarding Coherence Indexes?A. Indexes are maintained by Cache Entry OwnersB. An application should not suggest an index that another application had suggestedAnswer: A,DExplanation:QUESTION NO: 49Which one is a command-line scripting interface based on Jython used for automation of WebLogic Server administration?A. WebLogic Scripting ToolB. WebLogic OPMNC. WebLogic DeployerD. WebLogic ICommandAnswer: AExplanation:QUESTION NO: 50Which two of the following are the imposed restrictions to production redeployment In WebLogic Server?A. Can't change application's deployment targetsB. Can't change application's security modelC. Can't change application's node managerD. Can change application's persistent store settingsAnswer: A,BExplanation:QUESTION NO: 51What are the two types of distributed destinations that Oracle WebLogic Server supports?A. Shared Distributed Destinations (SDD.B. Uniform Distributed Destinations (UDD.C. Weighted Distributed Destinations (WDD.D. Bounced Distributed Destinations (BDD)。

2022年海南大学数据科学与大数据技术专业《计算机网络》科目期末试卷A(有答案)

2022年海南大学数据科学与大数据技术专业《计算机网络》科目期末试卷A（有答案）一、选择题1、（）属于TCP/IP协议簇的应用层应用服务元素。

A.文件传输协议FTPB.用户数据报协议UDPC.控制报文协议ICMPD.地址解析协议ARP2、当一台计算机从FTP服务器下载文件时，在该FTP服务器上对数据进行封装的5个转换步骤是（）。

A.数据、报文、IP分组、数据帧、比特流B.数据、IP分组、报文、数据帧、比特流C.报文、数据、数据帧、IP分组、比特流D.比特流、IP分组、报文、数据帧、数据3、数据段的TCP报头中为什么包含端口号（）。

A.指示转发数据段时应使用正确的路由器接口B.标识接收或转发数据段时应使用的交换机端口C.让接收主机以正确的顺序组装数据报D.让接收主机转发数据到适当的应用程序4、使用两种编码方案对比特流01100111进行编码的结果如图所示，编码1和编码2分别是（）A.NRZ 和曼彻斯特编码B.NRZ 和差分曼彻斯特编码C.NRZ-I和曼彻斯特编码D.NRZ-I和差分曼彻斯特编码5、以太网中如果发生介质访问冲突，按照二进制指数后退算法决定下一次重发的时间，使用二进制后退算法的理由是（）。

A.这种算法简单B.这种算法执行速度快C.这种算法考虑了网络负载对冲突的影响D.这种算法与网络的规模大小无关6、对于无序接收的滑动窗口协议，若序号位数为n，则发送窗口最大尺寸为（）A.2n -1B.2nC.2n-1D.2n-17、某以太网拓扑及交换机当前转发表如图所示，主机00-el-d5-00-23-al向主机00-el-d5-00-23-cl发送1个数据帧，主机00-e1-d5-00-23-cl收到该帧后，向主机00-el-d5-00-23-al发送1个确认帧，交换机对这两个帧的转发端口分别是（），A.{3}和{3}B. {2，3}和{3}C. {2，3}和{3}D. {1，2，3}和{1}8、在无噪声的情况下，若某通信链路的带宽为3kHz，采用4个相位，每个相位具有4种振幅的QAM调制技术，则该通信链路的最大数据传输速率是（）。

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BOUND
The network in Fig. 1 is a particular kind of degraded erasure relay channel – one in which the destination receives only the source symbols that are also received by the relay. The capacity of the general degraded relay channel was derived in [6]. This section develops an achievable cut-set bound ([7]) for the channel under consideration. Similar bounds for more general erasure relay channels are in [1], [2]. Let θ be the fraction of time for which the source is transmitting. Then, across the cut C1 (broadcast cut) in Figure 1, the maximum rate of information transfer is bounded by θ symbols/time slot. This follows from the fact that every symbol received by the destination is also received by the relay, and the capacity of the ideal source-relay channel, when active, is just one symbol/time slot. Similarly, across the cut C2 (multiple-access cut), the maximum rate of information
Abstract— This paper considers a simple network consisting of a source, a destination, and a relay. In this model, the sourcerelay and relay-destination links are lossless, while the sourcedestination link is subject to erasures. Four coding schemes for reliably conveying k symbols from the source to the destination are described. Three of these techniques are adapted directly from well-known point-to-point coding schemes - viz., the use of maximum-distance separable (MDS) codes and Luby Transform (LT) codes. The fourth approach is a new technique using uncoded transmission from the source in conjunction with a relay that transmits a sequence with this property: When the destination subtracts the effects of the unerased symbols from the sequence, what remains is an “LT-like” code for the erased symbols - and this property holds regardless of which symbols were erased on the source-destination link. The four approaches are compared in terms of their complexity and performance.
slots, where ∆ is close to (but necessarily larger than) ǫ. The feasibility of this task is established in Section II. Then, in Section III, we discuss two possible approaches – one based on MDS codes, and the other based on LT codes [4]. The LT-based scheme requires encoding at the source, whereas the MDS-based scheme does not – i.e., the MDS scheme is systematic. However, the complexity of the MDS scheme suffers in comparison to that of the LT-based approach. Motivated by this observation, we propose two systematic schemes based on LT codes. The ﬁrst approach adapts systematic LT codes as developed by Shokrollahi [5]. The second technique encodes the symbols at the relay in such a way that the effect of the unerased symbols can be subtracted off at the destination – and what remains resembles an LT sequence for the erased symbols, regardless of which symbols were erased. These new schemes are analyzed in Sections III-C and III-D, respectively. II. A CUT- SET
Coding Schemes for an Erasure Relay Channel
Srinath Puducheri, J¨ org Kliewer, and Thomas E. Fuja
Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA Email: {spuduche, jkliewer, tfuja}@
This work was supported inቤተ መጻሕፍቲ ባይዱpart by the Center for Applied Mathematics, University of Notre Dame. It was also supported by NSF grant CCF 02-05310, by German Research Foundation grant KL 1080/3-1, and by the University of Notre Dame Faculty Research Program.
r 0 0
s C1
Fig. 1.
d ε C2
A three-node erasure relay network
I. I NTRODUCTION Wireless relay networks modelled as erasure relay channels have been well studied in the literature. For example, in [1] and [2], the capacities of certain relay channels are derived, and practical coding schemes based on maximum-distance separable (MDS) codes are given. In [3] a max-ﬂow min-cut capacity result is obtained for a particular class of interferencefree wireless erasure networks assuming the decoder has perfect knowledge about the erasure pattern. This paper considers a three-node relay network comprised of a source s, a destination d and a relay r. (See Figure 1.) The source-relay and source-destination links together constitute a (physically degraded) broadcast channel, while the relaydestination link is a point-to-point channel. We assume timeslotted packetized transmissions (of ﬁxed duration/size) at both the source and relay. Moreover, the source and relay transmissions are assumed to occur in different time slots – i.e., a time-division multiplexing (TDM) strategy is used to control interference between the source and relay transmissions. Finally, the source-relay and relay-destination links are assumed to be lossless, while the source-destination channel is modelled as an erasure channel in which each symbol (or packet) is independently erased with probability ε. In the presence of physical-layer error-correction, this is a good higher-layer model for the case when the source-relay and relay-destination distances are much smaller than the sourcedestination distance. The goal is to communicate k information symbols from the source to the destination in no more than k · (1 + ∆) time