An OFDM System Concept for Joint Radar and
OFDM雷达及其关键技术研究进展
OFDM雷达及其关键技术研究进展刘晓斌;刘进;赵锋;艾小锋;张文明【摘要】正交频分复用（ Orthogonal Frequency Division Multiplexing，OFDM）雷达采用了OFDM信号，具有大时宽带宽积，且信号编码方式灵活，通过不同的波形设计准则，能够自适应调整信号子载频的系数，具备了认知雷达系统的基本特点。
通过简要回顾OFDM雷达的发展历程，讨论了OFDM雷达信号特点、信号处理及波形设计方法等关键技术，对目前的研究成果进行了分析与总结，指出了存在的问题。
讨论了OFDM雷达的未来发展方向。
%The Orthogonal Frequency Division Multiplexing ( OFDM ) radar possesses broadband and wideband with the use of OFDM signal.By better utilizing the flexibility of coding and frequency diversities of the signal,the OFDM radar can be candidate cogni⁃tive radar in the future.This paper reviews the development of OFDM radar.Then the key technologies of signal processing and waveform design are discussed.The research advances are analyzed and summarized.At last,the prospects of OFDM radar are pointed out.【期刊名称】《无线电工程》【年(卷),期】2016(000)001【总页数】5页(P25-29)【关键词】OFDM雷达;认知雷达;波形设计;信号处理【作者】刘晓斌;刘进;赵锋;艾小锋;张文明【作者单位】国防科学技术大学电子信息系统复杂电磁环境效应国家重点实验室，湖南长沙410073;国防科学技术大学电子信息系统复杂电磁环境效应国家重点实验室，湖南长沙410073;国防科学技术大学电子信息系统复杂电磁环境效应国家重点实验室，湖南长沙410073;国防科学技术大学电子信息系统复杂电磁环境效应国家重点实验室，湖南长沙410073;国防科学技术大学电子信息系统复杂电磁环境效应国家重点实验室，湖南长沙410073【正文语种】中文【中图分类】TN958Jankiraman[1,2]等人于1998年将多载频连续波信号引入到雷达系统中，设计了由8个调频连续波信号组成的发射信号，并应用于PANDORA(Parallel Array for Numerous Different Operational Research Activities)雷达，获得了高分辨能力。
中英对照 OFDMA技术
OFDMA技术一、定义OFDM(Orthogonal Frequency Division Multiplexing)即正交频分复用技术，实际上OFDM是MCM Multi-CarrierModulation，多载波调制的一种。
其主要思想是：将信道分成若干正交子信道，将高速数据信号转换成并行的低速子数据流，调制到在每个子信道上进行传输。
正交信号可以通过在接收端采用相关技术来分开，这样可以减少子信道之间的相互干扰ICI 。
每个子信道上的信号带宽小于信道的相关带宽，因此每个子信道上的可以看成平坦性衰落，从而可以消除符号间干扰。
而且由于每个子信道的带宽仅仅是原信道带宽的一小部分，信道均衡变得相对容易。
二、原理DM —— OFDM(Orthogonal Frequency Division Multiplexing)即正交频分复用技术，实际上OFDM是MCM Multi-CarrierModulation，多载波调制的一种。
其主要思想是：将信道分成若干正交子信道，将高速数据信号转换成并行的低速子数据流，调制到在每个子信道上进行传输。
正交信号可以通过在接收端采用相关技术来分开，这样可以减少子信道之间的相互干扰ICI 。
正交频分复用OFDM（OrthogonalFrequencyDivisionMultiplex)是一种多载波调制方式，通过减小和消除码间串扰的影响来克服信道的频率选择性衰落。
它的基本原理是将信号分割为N个子信号，然后用N个子信号分别调制N个相互正交的子载波。
由于子载波的频谱相互重叠，因而可以得到较高的频谱效率。
当接收机检测到信号到达时，首先进行同步和信道估计。
当完成时间同步、小数倍频偏估计和纠正后，经过FFT变换，进行整数倍频偏估计和纠正，此时得到的数据是QAM或QPSK的已调数据。
对该数据进行相应的解调，就可得到比特流。
FDM/FDMA（频分复用/多址）技术其实是传统的技术，将较宽的频带分成若干较窄的子带（子载波）进行并行发送是最朴素的实现宽带传输的方法。
ITU-R卫星移动通信标准--整合移动业务的动力
ITU-R卫星移动通信标准--整合移动业务的动力金秀英【摘要】认为国际电信联盟无线电通信部门（ITU-R）关于卫星移动通信的标准化新进展将在全球移动通信设备和系统无缝连接的实现过程中起到重要作用，卫星和地面的集成/混合的天地一体化系统将充分发挥原系统各自的优势，未来多数的卫星移动业务（MSS）都将基于这种天地一体化系统。
指出IMT-Advanced系统的卫星部分和ITU-R标准化无线接口是集成MSS系统的关键技术，将成为激活MSS产业的新的驱动力。
%Wel-developed standards wil play an important role in facilitating seamless interworking of equipment and systems global y. Most future MSS services wil use integrated and/or hybrid satel ite-terrestrial networks that leverage both satel ite and terrestrial networks. Satel ite components of IMT-Advanced systems and ITU-R standardized radio interfaces provide key technology in integrated satel ite and terrestrial networks, and this wil be a new driving force behind MSS industries.【期刊名称】《中兴通讯技术》【年(卷),期】2015(000)002【总页数】4页(P44-47)【关键词】卫星移动通信;天地一体化;标准化;国际电信联盟无线电通信部门【作者】金秀英【作者单位】韩国全北国立大学，韩国全州市561756【正文语种】中文【中图分类】TN929.5国际移动通信系统的卫星无线接口已成功修订并全新开发混合与集成式网络架构将在未来高效卫星移动业务中发挥重要作用天地一体化系统将成为激活卫星移动业务产业新动力国际电信联盟（ITU）是主管信息与通信技术的联合国专门机构。
道路与桥梁工程中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Bridge research in EuropeA brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of post-tensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in post-tensioned concrete bridges using digital impulse radar.IntroductionThe challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original community of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purelyeconomic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the community to a European Union, EU, with certain political goals together with the objective of a common European currency.Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of common thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —e.g. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial partners within a number of the states— a Brite Euram bid would normally be led by an industrialist.In terms of dissemination of knowledge, two quite different strands appear to have emerged. The UK and the USA have concentrated primarily upon disseminating basic research in refereed journal publications: ASCE, ICE and other journals. Whereas the continental Europeans have frequently disseminated basic research at conferences where the circulation of the proceedings is restricted.Additionally, language barriers have proved to be very difficult to break down. In countries where English is a strong second language there has been enthusiastic participation in international conferences based within continental Europe —e.g. Germany, Italy, Belgium, The Netherlands and Switzerland. However, countries where English is not a strong second language have been hesitant participants }—e.g. France.European researchExamples of research relating to bridges in Europe can be divided into three types of structure:Masonry arch bridgesBritain has the largest stock of masonry arch bridges. In certain regions of the UK up to 60% of the road bridges are historic stone masonry arch bridges originally constructed for horse drawn traffic. This is less common in other parts of Europe as many of these bridges were destroyed during World War 2.Concrete bridgesA large stock of concrete bridges was constructed during the 1950s, 1960s and 1970s. At the time, these structures were seen as maintenance free. Europe also has a large number of post-tensioned concrete bridges with steel tendon ducts preventing radar inspection. This is a particular problem in France and the UK.Steel bridgesSteel bridges went out of fashion in the UK due to their need for maintenance as perceived in the 1960s and 1970s. However, they have been used for long span and rail bridges, and they are now returning to fashion for motorway widening schemes in the UK.Research activity in EuropeIt gives an indication certain areas of expertise and work being undertaken in Europe, but is by no means exhaustive.In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio. The example relates to the identification of voids in post-tensioned concrete bridges, using digital impulse radar.Post-tensioned concrete rail bridge analysisOve Arup and Partners carried out an inspection and assessment of the superstructure of a 160 m long post-tensioned, segmental railway bridge in Manchester to determine its load-carrying capacity prior to a transfer of ownership, for use in the Metrolink light rail system..Particular attention was paid to the integrity of its post-tensioned steel elements. Physical inspection, non-destructive radar testing and other exploratory methods were used to investigate for possible weaknesses in the bridge.Since the sudden collapse of Ynys-y-Gwas Bridge in Wales, UK in 1985, there has been concern about the long-term integrity of segmental, post-tensioned concrete bridges which may b e prone to ‘brittle’ failure without warning. The corrosion protection of the post-tensioned steel cables, where they pass through joints between the segments, has been identified as a major factor affecting the long-term durability and consequent strength of this type of bridge. The identification of voids in grouted tendon ducts at vulnerable positions is recognized as an important step in the detection of such corrosion.Description of bridgeGeneral arrangementBesses o’ th’ Barn Bridge is a 160 m long, three span, segmental, post-tensionedconcrete railway bridge built in 1969. The main span of 90 m crosses over both the M62 motorway and A665 Bury to Prestwick Road. Minimum headroom is 5.18 m from the A665 and the M62 is cleared by approx 12.5 m.The superstructure consists of a central hollow trapezoidal concrete box section 6.7 m high and 4 m wide. The majority of the south and central spans are constructed using 1.27 m long pre-cast concrete trapezoidal box units, post-tensioned together. This box section supports the in site concrete transverse cantilever slabs at bottom flange level, which carry the rail tracks and ballast.The center and south span sections are of post-tensioned construction. These post-tensioned sections have five types of pre-stressing:1. Longitudinal tendons in grouted ducts within the top and bottom flanges.2. Longitudinal internal draped tendons located alongside the webs. These are deflected at internal diaphragm positions and are encased in in site concrete.3. Longitudinal macalloy bars in the transverse cantilever slabs in the central span .4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity.5. Transverse macalloy bars through the bottom flange to support the transverse cantilever slabs.Segmental constructionThe pre-cast segmental system of construction used for the south and center span sections was an alternative method proposed by the contractor. Current thinking suggests that such a form of construction can lead to ‘brittle’ failure of the ent ire structure without warning due to corrosion of tendons across a construction joint，The original design concept had been for in site concrete construction.Inspection and assessmentInspectionInspection work was undertaken in a number of phases and was linked with the testing required for the structure. The initial inspections recorded a number of visible problems including:Defective waterproofing on the exposed surface of the top flange.Water trapped in the internal space of the hollow box with depths up to 300 mm.Various drainage problems at joints and abutments.Longitudinal cracking of the exposed soffit of the central span.Longitudinal cracking on sides of the top flange of the pre-stressed sections.Widespread sapling on some in site concrete surfaces with exposed rusting reinforcement.AssessmentThe subject of an earlier paper, the objectives of the assessment were:Estimate the present load-carrying capacity.Identify any structural deficiencies in the original design.Determine reasons for existing problems identified by the inspection.Conclusion to the inspection and assessmentFollowing the inspection and the analytical assessment one major element of doubt still existed. This concerned the condition of the embedded pre-stressing wires, strands, cables or bars. For the purpose of structural analysis these elements、had been assumed to be sound. However, due to the very high forces involved,、a risk to the structure, caused by corrosion to these primary elements, was identified.The initial recommendations which completed the first phase of the assessment were:1. Carry out detailed material testing to determine the condition of hidden structural elements, in particularthe grouted post-tensioned steel cables.2. Conduct concrete durability tests.3. Undertake repairs to defective waterproofing and surface defects in concrete.Testing proceduresNon-destructi v e radar testingDuring the first phase investigation at a joint between pre-cast deck segments the observation of a void in a post-tensioned cable duct gave rise to serious concern about corrosion and the integrity of the pre-stress. However, the extent of this problem was extremely difficult to determine. The bridge contains 93 joints with an average of 24 cables passing through each joint, i.e. there were approx. 2200 positions where investigations could be carried out. A typical section through such a joint is that the 24 draped tendons within the spine did not give rise to concern because these were protected by in site concrete poured without joints after the cables had been stressed.As it was clearly impractical to consider physically exposing all tendon/joint intersections, radar was used to investigate a large numbers of tendons and hence locate duct voids within a modest timescale. It was fortunate that the corrugated steel ducts around the tendons were discontinuous through the joints which allowed theradar to detect the tendons and voids. The problem, however, was still highly complex due to the high density of other steel elements which could interfere with the radar signals and the fact that the area of interest was at most 102 mm wide and embedded between 150 mm and 800 mm deep in thick concrete slabs.Trial radar investigations.Three companies were invited to visit the bridge and conduct a trial investigation. One company decided not to proceed. The remaining two were given 2 weeks to mobilize, test and report. Their results were then compared with physical explorations.To make the comparisons, observation holes were drilled vertically downwards into the ducts at a selection of 10 locations which included several where voids were predicted and several where the ducts were predicted to be fully grouted. A 25-mm diameter hole was required in order to facilitate use of the chosen horoscope. The results from the University of Edinburgh yielded an accuracy of around 60%.Main radar sur v ey, horoscope verification of v oids.Having completed a radar survey of the total structure, a baroscopic was then used to investigate all predicted voids and in more than 60% of cases this gave a clear confirmation of the radar findings. In several other cases some evidence of honeycombing in the in site stitch concrete above the duct was found.When viewing voids through the baroscopic, however, it proved impossible to determine their actual size or how far they extended along the tendon ducts although they only appeared to occupy less than the top 25% of the duct diameter. Most of these voids, in fact, were smaller than the diameter of the flexible baroscopic being used (approximately 9 mm) and were seen between the horizontal top surface of the grout and the curved upper limit of the duct. In a very few cases the tops of the pre-stressing strands were visible above the grout but no sign of any trapped water was seen. It was not possible, using the baroscopic, to see whether those cables were corroded.Digital radar testingThe test method involved exciting the joints using radio frequency radar antenna: 1 GHz, 900 MHz and 500 MHz. The highest frequency gives the highest resolution but has shallow depth penetration in the concrete. The lowest frequency gives the greatest depth penetration but yields lower resolution.The data collected on the radar sweeps were recorded on a GSSI SIR System 10.This system involves radar pulsing and recording. The data from the antenna is transformed from an analogue signal to a digital signal using a 16-bit analogue digital converter giving a very high resolution for subsequent data processing. The data is displayed on site on a high-resolution color monitor. Following visual inspection it is then stored digitally on a 2.3-gigabyte tape for subsequent analysis and signal processing. The tape first of all records a ‘header’ noting the digital radar settings together with the trace number prior to recording the actual data. When the data is played back, one is able to clearly identify all the relevant settings —making for accurate and reliable data reproduction.At particular locations along the traces, the trace was marked using a marker switch on the recording unit or the antenna.All the digital records were subsequently downloaded at the University’s NDT laboratory on to a micro-computer.（The raw data prior to processing consumed 35 megabytes of digital data.）Post-processing was undertaken using sophisticated signal processing software. Techniques available for the analysis include changing the color transform and changing the scales from linear to a skewed distribution in order to highlight、突出certain features. Also, the color transforms could be changed to highlight phase changes. In addition to these color transform facilities, sophisticated horizontal and vertical filtering procedures are available. Using a large screen monitor it is possible to display in split screens the raw data and the transformed processed data. Thus one is able to get an accurate indication of the processing which has taken place. The computer screen displays the time domain calibrations of the reflected signals on the vertical axis.A further facility of the software was the ability to display the individual radar pulses as time domain wiggle plots. This was a particularly valuable feature when looking at individual records in the vicinity of the tendons.Interpretation of findingsA full analysis of findings is given elsewhere, Essentially the digitized radar plots were transformed to color line scans and where double phase shifts were identified in the joints, then voiding was diagnosed.Conclusions1. An outline of the bridge research platform in Europe is given.2. The use of impulse radar has contributed considerably to the level of confidence in the assessment of the Besses o’ th’ Barn Rail Bridge.3. The radar investigations revealed extensive voiding within the post-tensioned cable ducts. However, no sign of corrosion on the stressing wires had been found except for the very first investigation.欧洲桥梁研究欧洲联盟共同的研究平台诞生于欧洲联盟。
OFDM系统频偏估计与补偿
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可以看到 sk 等效为对 di 进行 IDFT。同样在接收端，可对 sk 进行 DFT 以恢复出原始数 据符号 di，即:
di
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传统的并行传输系统中，整个信号带宽被分成多个并行的非正交的子载波。每个子载波 单独调制，整个系统构成了频分复用。两个相邻的子载波之间频谱没有交叠，这样有利于消 除子载波间的干扰。然而，这种频分复用方式降低了频谱的利用率。为了提高频偏利用率， 在20世纪60年代中期提出了并行传输和带有频谱交朴的FDM的思想，即正交频分复用 (OFDM )。正交的多载波机制比传统的频分复用系统的频谱利用率提高一倍。为了减小子载 波间的干扰，必须保证子载波间的正交性。
OFDM[1]系统的历史：OFDM 是一种特殊的多载波传输技术，它将一个较宽的传输带 宽分割成互相正交的多个子载波用于并行传输数据。当然，OFDM 也可视为一种调制技术 或复用技术。OFDM 技术的一个最大优势就是对抗多径衰落。由于整个传输带宽被分成多 个窄带的子载波，因而每个子载波内，信号可视为平坦衰落的。在单载波调制系统中，信道 的衰落将会影响到整个信号带宽：然而在多载波调制系统中，只有一小部分子载波被衰落。 这些由衰落子载波引起的错误可以通过使用纠错码进行纠正。
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术语翻译59313080
术语翻译GPM General Purpose Medium 通用介质hp horsepower 马力HTA High Threat Area 高威胁区HVLT High V oltage Long-Term 长期高压HVST High V oltage Short-Term 短时低压Hz hertz 赫兹IL Isolating 隔离/绝缘ILS Instrument Landing System 仪表着陆系统IMA Individual Mobilization Augmentee个人动员增长IR Infrared 红外线/红外的ISO International Standardization Organization 国际标化组织ISSA Interservice Support Agreement 军种支持协议JCS Joint Chiefs of Staff参谋长联席会议JSP Joint Support Plan 联合支援计划kg/L kilogram per liter 千克/升kV kilovolt 千伏kV A kilovoltampere 千伏安kVp kilovolt peak 千伏峰值kWh kilowatt hour 千瓦时lat Latitude 维度LB Limited Base 有限的基地LCN Load Classification Number 荷载等级号码lin ft linear foot 纵尺，延长英尺LN Local National 当地国民/当地人LOC Lines of Communications 通信线路LORAN Long-Range Aid to Navigation 远距导航LTA Low Threat Area 低威胁区LVLT Low V oltage Long-term 长期低压LVST Low V oltage Short-term 短时低压MDF Main Defense Force 主要的防御部队MEP Mission Essential Power 任务必须的动力MHE Materials Handling Equipment 物料处理设备Mi mile 英里MKT Mobile Kitchen Trailer 移动式厨房拖车mm millimeter 毫米mph miles per hour 英里/小时MRA Minimum Reserve Authorization最低储备金授权MSL Mean Sea Level 平均海平面MTF Medical Treatment Facility 医疗设施NBC Nuclear, Biological, and Chemical 核、生、化NCO Noncommissioned Officer 士官NCOIC Noncommissioned Officer in Charge 主管士官/值班军士NSN National Stock Number 国家库存物资编号NTA Non-Threat Area 无威胁区OIC Officer in Charge 主管官员ONC Operational Navigation Charts 作战领航图OR Operationally Ready作好战斗准备OSHA Occupational Safety and Health Administration职业安全与健康管理（局）OSI Office of Special Investigations 特别调查办公室PDC Primary Distribution Center 基层配送中心/高压配电中心PMEL Precision Measurement Equipment Laboratory精密测量设备实验室ppm parts per million 百万分之RAL Remote Area Lighting 远程大面积照明/远程区域照明RAPCON Radar Approach Control 雷达进场控制/管制RCR Runway Condition Reading跑道状况读数ROK Republic of Korea 韩国RRR Rapid Runway Repair 跑到快速维修RSC Runway Surface Condition 道面状况RSP Render-safe Procedures执行安全程序SAR Search and Rescue 搜救SBSS Standard Base Supply System （美国空军）标准基地供应系统SCNS Standard Camouflage Net System标准伪装网系统SDC Secondary Distribution Center二次配电中心，辅助配电中心，低压配电中心SME Squadron Medical Element 中队医疗分队SNCOIC Senior NCOIC 高级军士SOA Separate Operating Agency 分开的作战机构SOF Special Operations Forces特种作战部队SP Security Police 安全警察SRC Survival Recovery Center救援中心STAMP Standard Air Munitions Package标准航空弹药包STANAG Standard NA TO Agreement标准北约协议SWA Southwest Asia 西南亚TACAN Tactical Air Navigation战术空中导航TDS Total Dissolved Solids总溶解固体TLV Threshold Limit V alue 临界阈值TM Technical Manual 技术手册TO Technical Order 技术规程TOL Takeoff and Landing 起飞与着陆UMD Unit Manning Document分队人员职位配制表/分队人员配置表UTC Unit Type Code设备类型代号UXO Unexploded Ordnance未爆弹药V V olt 伏特V A voltampere 伏安V AC volts alternating current 交流电压V AL V ehicle Authorization List车辆核定表V ASI V isual Approach Slope Indicator目视进近坡度指示灯VDC volts direct current 直流电压W Watt瓦特WDR War Damage Repair 战损修复WOC Wing Operations Center 联队作战中心WRM War Reserve Materiel战争储备物资WRSK War Readiness Spares Kit战备备用套件Air Base Defense--Those measures taken to nullify or reduce the effectiveness of enemy attacks on, or sabotage of, air bases to ensure that the senior commander retains the capability to assure aircraft sortie generation.Air Force Civil Engineer Support Agency (AFCESA)--A field operating agency (FOA) located at Tyndall Air Force Base, Florida. The Directorate of Contingency Support (HQ AFCESA/CEX) acts as the Air Force program manager for Base Civil Engineer (BCE) Contingency Response Planning.空军土木工程师支援局（AFCESA）- 一个位于佛罗里达州廷德尔空军基地野战工作的机构（FOA）。
美国舰载四面阵相控阵雷达ANSPY-1研制概况
美国舰载四面阵相控阵雷达AN SPY-1研制概况This paper first briefly introduces the ship-borne AEGIS (AEGIS) area air defense weapon system, and then to the core of the system - the shipboard all array phased-array radarAN/development situation of SPY - 1 were described in detail. The content includes the radar, the main technical performance parameters, the technical characteristics and the improvement and updating plan.AEGIS combat effectivenessThe shipboard all array phased-array radar AN/SPY - 1 is the U.S. navy shipboard AEGIS (AEGIS) a unit area defense weapon system, therefore, in the AN/radar SPY - 1 before, first it is necessary to make a brief introduction of the AEGIS system.The U.S. navy was hit hard by the Japanese attack on Pearl Harbor in 1941. Since then, the U.S. navy invested a lot of manpower and material resources and financial resources, discusses the hands of missile weapon system integration concept and design, which is developed after the second world war to the AEGIS defense weapon system (AEGIS) area. The AEGIS defense system was formally established by the defense department in 1969. The purpose of the project is mainly used to deal with in the 80 s and 90 s is check the increasing threat of air, since 2000 the main threat is appeared since the 50 s high altitude or low level with high speed and high load of new aircraft andhigh-speed air/surface and surface/surface tactical missile. These missiles employ a deceptive trajectory and increase the high power and multi-functional electronic countermeasures.AEGIS system in October 1970 to complete the system design, in 1971 into the design and production stages, in February 1972 to complete the key design scheme evaluation and set about making and test, the end of 1972 completed components evaluation test, 1973 army proving ground for system level testing/RCA company, installed in 1974 in the NORTON sound test ship for 32 months of sea trial.In 1974, the AN/APY - 1 installed in NORTON sound test ship, succeeded in automatic detection and tracking in 20 planes flying over the Pacific, with EA - 6 b jammer for the AN/APY - 1 full power interference also of no help. The U.S. air force's switch to the equivalent of 32 ea-6b full power jammers (the configuration of TREE SHARK) can still not completely interfere with AN/spy-1. In both cases, the AN/spy-1 radar beam can "burn through" jammers and simulate the launch of a defensive missile.In 1975, AEGIS conducted a six-day "combat" exercise in the sea, focusing on the success of the three sm-1 missiles that had actually fired on unmanned aircraft and missile threats.In March 1976, the U.S. navy organized a multinational fleet off the coast of south California, with 41 ships, hundreds of planes and 18,000 people in five countries. The exercise was "hostile" and lasted for 10 days. The NORTON bay test ship successfully detects and intercepts "enemy aircraft" and "enemy ships" of single or multiple attacks during theall-weather and electronic countermeasures environment. On December 10, 1976, a sm-2 medium-range missile was intercepted, tracked and controlled by AN/spy-1 in a short time after launch,until it successfully hit the unmanned target.To sum up, the AEGIS weapon system is a fast response can be the standard missiles fired into the air and ground targets high-performance air defense combat system, and the first U.S. navy to dense air attack weapon system can make automatic reaction. It provides the wide domain surface/air andface/surface defense of the 1980s and 1990s. The ability to attack the surface of the sea can be provided by using a long-range surface/surface cruise missile and an extended surface/air missile.At the beginning of the AEGIS project, the military proposed five key technical requirements, namely quick response, strong firepower, strong survivability, high availability and high coverage. These five requirements are the "cornerstone" of design AEGIS.1) quickThe AEGIS must destroy the target within two minutes when high-speed, low or high Angle attacks are on target (within 20km).(2) the firepower fierceRequires a strong attack that is strong enough to handle multiple targets at the same time as high killing rates.The ability to survive is strongIt is required to work effectively in strong ECM, metal foil interference and bad weather conditions.(4) high availabilityTo specific environment on the sea (underwater shock, nuclear shock, 20 ° F and relative wind speed of 70 miles per hour, can work continuously at a specific time, can't shut down for a long time to repair.The range is largeTo provide effective area defense fleet, covering 360 ° of space.The composition and technical characteristics of AN/spy-1The AN/SPY - 1 is the heart of the AEGIS system, is the AEGIS combat system is mainly to empty to sea radar, is a target for air and sea for automatic search, detection, tracking and the SM - 2 missile midcourse guidance of multi-function radars.AN/SPY - 1 is a work in E/F spectrum matrix, can provide bearing 360 °, 90 ° Angle of coverage, more than 250 nm r ange.AN/spy-1 is currently available in four types: AN/spy-1a, AN/spy-1b, AN/spy-1c and AN/spy-1d. AN/spy-1a is used to equip the ddg-47 destroyers and the cg-58 cruisers.AN/spy-1b is used to equip the cg-59 cruiser.AN/spy-1c is a project that USES aircraft as a carrier, and is cancelled because it is difficult to implement.AN/spy-1d is used to equip the ddg-51 destroyers.The AN/spy-1 series radar structure and features are basically the same, so this article focuses on the AN/spy-1a. Other parts of the improvement section are introduced only briefly.AN/spy-1a consists of five functional units: antenna unit, radar transmitter unit, signal processing unit, control unit and auxiliary unit. The combination of these five units supports the five key capabilities of AEGIS. This "five" key performance is also the five notable features of the AN/spy-1 series radar.The antenna unit forms and controls the high power emission beam and radiates it into space. It can also receive and amplify the received signals and convert them to medium frequency.The firing unit sends a high power radio frequency pulse to the phased array antenna. Launch unit contains two sets of each type 32 SFD - 261 crossed-field amplifier as terminal amplifier (SFD - 261 design specification for the 5000 - hour life, but by the mid - 70 - s has specified life of 2 ~ 4 times, each group of amplifier, are available on warship drive electric control at the end of the array.The signal processor produces the radar transmitter waveform and handles the selected echo based on the receiver specified by the radar unit. It can also produce and assign AN/spy-1aradar video signal for AN AN/UYA 4 display unit.The control unit contains AN/spy-1a radar calculating unit and display equipment.The equipment is based on AN AN/spy-1a radar computer program to schedule and control radar system functions.The auxiliary device unit provides specific working conditions for the AN/SPY / 1A radarWork best. The unit includes air cooling and water cooling, air dehydration, water purification and several power supplies.The AN/spy-1a radar and adoption rate is ensured by the recombination of redundant technology and rapid computer control in the machine. The radar must work continuously, with a small amount of maintenance personnel.The operation of AN/spy-1a is as follows:First, the use of the AN/uyk-7 computing unit (control unit) is used to generate the appropriate search rf waveform or follow the rf waveform from the signal processor. The signal is amplified and selected in the transmitter channel. The beam direction via the antenna position program instructions into array phase shifter, resulting in a transmitter output, the output through the antenna array surface formed in the specific space Angle beam. By array and channel (distance) and two difference channels (elevation and azimuth) receiving the signal is amplified in the rf preamplifier, first in the radarreceiver frequency conversion and was further enlarged. The signals are then sent to the signal processor. The signal processor can be used to complete the signal from the docking station for constant virtual alarm rate and pulse pressure processing and Angle and distance estimation. These data are used by the AN/spy-1a unit to start the radar tracking. MTI processing can also be used to track and search the two ways of working, if additional clutter is needed.AN/spy-1b adopts a new phase shifter and beam forming technique to reduce the antenna side lobe, thereby reducing the threat of active electronic interference. The AN/SPY - 1 b decay processor will also adopt distribution system in order to realize the fast signal processing, make the signal analysis of central processing unit (CPU) and the fusion center fusion task easy to do.The AN/spy-1d radar update is currently being conducted by lockheed Martin for pre-assembly. Update the purpose is to improve the radar in heavy clutter environment (such as city, industrial zone in the coastal area, migrating birds and sandstorm) rapid acquisition capability of low altitude target.Update items include changes to the transmitter, signal processor, and computer programs. The critical parts of the transmitter are replaced by new devices to reduce internal noise and improve signal stability. The signal processor is changed to the advanced data distribution structure, and the capability of the microprocessor is strengthened, which greatly speeds up the signal processing speed. Computer programwith new processing method, strengthen the management of signal processing and transmitter, improves the eliminate clutter and for fraudulent electromagnetic interference suppression ability, thus ensure the phase synchronization and the current threat is developing target.3 conclusionThe navy equipment AEGIS system is a successful shipboard area defense weapon system, the AN/SPY - 1 radar is its core, is by far the world's first round array of shipborne phased array radar. The AEGIS system, which began in 1969, took 30 years and cost $50 billion. Each AEGIS ship costs $7.5 billion to $900 million.To deal with after 2000 long-range strategic ballistic threats from outer space, the us navy has been set for further development and improvement, including researching new interceptors and radar for the AN/SPY - 1 for further improvement. The improvement plan calls for expanding the zone, and when the target is in the atmosphere, the AEGIS system should be able to identify and re-enter the warhead and the shrapnel, which is the key to the AEGIS system's improvement. This improved AEGIS combat system must be integrated with the U.S. global combat management system and the C&C system deployed at the beginning of the next century. The new AEGIS system will provide the joint forces command with the requisite reliable ballistic missile defense throughout the zone, which is expected to be deployed by the armed forces in the year 2000.U.S. navy shipboard AEGIS system developed for China's navyshipboard equipment has a great reference to regional weapon system, we deal with AEGIS system more in-depth study, in order to "foreign serve China".。
基于动态超表面天线的雷达通信一体化设计
doi:10.3969/j.issn.1003-3114.2023.05.021引用格式:高克,张海洋,王保云.基于动态超表面天线的雷达通信一体化设计[J].无线电通信技术,2023,49(5):946-952.[GAO Ke,ZHANG Haiyang,WANG Baoyun.Beamforming Design for Dual-functional Radar-communication Systems with Dynamic Metasurface Antennas[J].Radio Communications Technology,2023,49(5):946-952.]基于动态超表面天线的雷达通信一体化设计高㊀克,张海洋,王保云(南京邮电大学通信与信息工程学院,江苏南京210003)摘㊀要:雷达通信一体化(Dual-Functional Radar-Communication,DFRC)利用相同的硬件平台㊁频谱资源同时实现雷达感知和无线通信双功能,是当前无线通信领域研究的热点技术㊂针对动态超表面天线(Dynamic Metasurface Antenna,DMA)辅助的雷达通信一体化系统,研究了最优波束成形设计问题㊂最优波束成形设计是一个非凸优化问题,很难直接求解㊂设计全数字天线架构下的最优波束,将动态超表面天线雷达波束设计转换为拟合最优编码矩阵问题㊂转换后的波束设计问题仍为非凸,为此将其分解为两个子问题交替最小化,其中两个子问题分别采用黎曼共轭梯度和半正定松弛算法求解㊂数值仿真表明,满足通信质量约束的情况下,动态超表面天线架构的DFRC 雷达波束性能接近于无频谱共享时的纯雷达波束性能㊂关键词:雷达通信一体化;动态超表面天线;交替最小化;黎曼共轭梯度;半正定松弛中图分类号:TN929.5㊀㊀㊀文献标志码:A㊀㊀㊀开放科学(资源服务)标识码(OSID):文章编号:1003-3114(2023)05-0946-07Beamforming Design for Dual-functional Radar-communicationSystems with Dynamic Metasurface AntennasGAO Ke,ZHANG Haiyang,WANG Baoyun(Communication and Information Engineering,Nanjing University of Posts and Telecommunications,Nanjing 210003,China)Abstract :Dual-Functional Radar-Communication (DFRC)uses same hardware platform and spectrum re-sources to realize dualfunctions of radar detection and wireless communication simultaneously,which is a hot topic in the field of wireless communications.Forthe Dynamic Metasurface Antennas (DMA)-assisted DFRC system,an optimal beamforming design problem is studied.The optimalbeamforming design is a non-convex optimization problem that is difficult to solve directly.In this paper,an optimal beam with a digitalantenna architecture is designed first,and then the dynamic metamaterial antenna radar beam design is converted into a fitting optimalcoding matrix problem.Though the resulting design problem is still non-convex.it can be decom-posed into two sub-problems and then been solved alternately.In particular,the two sub-problems are solved by riemannian conjugate gradient and semidefinite relaxation algo-rithms,respectively.Finally,numerical results show that the performance of our proposed beamforming design for DMA-assisted DFRC system is close to that of the radar only beamforming without communication requirement.Keywords :DFRC;DMA;alternate minimization;riemannian conjugate gradient;semidefinite relaxation收稿日期:2023-05-050 引言随着5G 时代的到来,无线设备数量和种类均呈现出了爆发性增长,全球通信产业对无线频谱的需求日益迫切㊂有很多场景需要感知与通信联合设计,例如:自动驾驶㊁智慧城市和智能家居等[1]㊂与此同时,随着无线通信速率需求的不断提高,载波频率被推向了传统上分配给雷达系统的毫米波频率频段[2]㊂未来后5G 及6G 时代,为提高频谱效率以及降低雷达与通信系统之间的电磁干扰问题,雷达通信一体化(Dual-Functional Radar-Communication,DFRC)系统成为了一个有前途的热门研究领域㊂在雷达通信一体化系统中,雷达与通信系统之间共享相同的硬件平台和频谱资源,同时实现通信和雷达感知的双功能㊂在雷达通信一体化系统中,由于雷达和通信具有不同的需求且共享相同的资源,因此需要精心设计传输波束以平衡二者的性能㊂为了在保证通信用户服务质量的同时提高雷达的性能,文献[3]研究了发射波束成形优化设计㊂针对全数字天线架构,文献[4]考虑波束之间的相互干扰因素,设计了性能更优的雷达波束㊂考虑到全数字天线功耗大㊁成本高的问题,目前对雷达通信一体化系统研究比较广泛的是基于相移器的混合波束天线架构[5-10],其中文献[5-6]研究了设计模拟和数字预编码矩阵,使其与最优通信预编码矩阵和最优雷达波束预编码矩阵之间误差的加权总和最小;文献[7-8]研究主要集中在雷达波束与理想波束差距小于一定阈值作为约束条件,最大化用户通信质量;文献[9-10]研究了在保证用户通信质量前提下,最优化雷达波束性能,其雷达的波束性能直接由雷达接收机的信干扰加噪声比(Signal to Interference plus Noise Ratio, SINR)决定㊂智能超表面是当前无线通信领域的另外一个研究热点,其可用于增强无线通信盲区覆盖㊁物理层辅助安全通信㊁大规模D2D(Device-to-Device)通信㊁物联网中无线携能通信以及室内覆盖等领域[11]㊂然而,智能超表面除了用来做被动的反射外,还可以用来实现低功耗的主动收发天线㊂动态超表面天线(Dynamic Metasurface Antennas,DMA)是一种典型的基于超表面天线的收发天线㊂在基于DMA的收发器中,每个超表面天线单元是由低功耗的超表面组成,且每个天线单元的幅频特性可以动态实时调控[12]㊂DMA天线架构可以被视为混合模拟数字天线架构,即它不需要额外的专用模拟相移器网络,仅利用自身的信号处理功能便可实现模拟预编码[13]㊂此外,DMA可以包含大量可调谐的超表面天线元件,并且其天线单元之间的距离可以是亚波长,DMA需要的物理面积可以更小,有助于设备的小型化[14]㊂1㊀系统模型和问题描述1.1㊀系统模型雷达通信一体化系统场景示意图如图1所示,一个雷达通信一体化基站拥有N T根天线,为K个单天线用户提供通信服务并探测区域内目标㊂基站使用的动态超表面天线架构,其由数字预编码矩阵㊁L T条射频链路和模拟预编码矩阵组成㊂图1㊀雷达通信一体化系统场景示意图Fig.1㊀Schematic diagram of DFRC基带信号表示为sɪKˑ1,s i~(0,1),iɪ{1, 2, ,K}为第i个用户接收到的信息符号㊂发射信号可以表示为:y=UF DMA F BB s,(1)式中:F DMAɪN TˑL T为DMA天线模拟预编码矩阵, F BBɪN DMAˑK为数字预编码矩阵,DMA微带内的信号传播公式为:u i,j=e-ρi,j(αi+jβi),∀i,j,其中αi为波导衰减系数,βi为波数,ρi,j表示第i微带中第l个单元的位置,其中U((i-1)L+l,(i-1)L+l)=u i,l,L为每条微带上单元的个数[13]㊂功率约束条件为 UF DMA F BB 2FɤP max,P max为基带最大分配功率㊂F DMA矩阵满足以下形式[15]:F DMA=t10 00t2 0︙︙︙00 t L Téëêêêêêùûúúúúú,(2)式中:t iɪN TN DMAˑ1,非零相q i,l=j+e jφi,l2,{φi,lɪ[0,2π]}ɪF DMA,∀i,l㊂雷达在θ角方向的传输功率波束图可以表示为:P(θ;R)=a H(θ)Ra(θ),(3)式中:RɪN TˑN T为传输波束的协方差矩阵,R= UF DMA F BB ss H F H BB F H DMA U-H=UF DMA F BB F H BB F H DMA U H㊂对于N个天线单元的均匀线性天线阵列,其导向矢量为:a(θ)=1N[1,e j2πλdsin(θ), ,e j2πλd(N-1)sin(θ)]T,(4)式中:λ为信号波长,d=λ/2为天线单元间距㊂雷达在θ1和θ2两角之间的波束互相关可以表示为:P c(θ1,θ2;R)=a H(θ1)Ra T(θ2)㊂(5)由式(3)和式(5)可以看出,雷达的传输功率波束图和波束互相关都是由传输波束的协方差矩阵R决定㊂通过波束方向误差和波束互相关两部分的加权和组成一个损失函数,用损失函数评估雷达性能㊂第一部分可以用接收到的波束与理想波束之间的均方差来评估:L r,1(R,α)=1LðL l=1|αd(θl)-P(θl;R)|2,(6)式中:α为比例因子,d(θl)为θl方向理想接收波束㊂第二部分用波束互相关均方差来评估:L r,2(R)=2P2-PðP-1p=1㊀ðP q=p+1|P c(θ-p,θ-q);R|2㊂(7)㊀㊀将以上两部分加权和后,雷达波束图的损失函数表示为:L r(R,α)=L r,1(R,α)+ωL r,2(R)㊂(8)在本文雷达通信一体化系统中,假设通信用户是单天线的,则第k个用户接收信号为:y k=h H k UF DMA F BB,k s k+ðK iʂk h H k UF DMA F BB,i s i+n k,(9)式中:h kɪN Tˑ1为基站与第k个用户之间的下行通道,n k~(0,σ2k)为第k个用户加性高斯白噪声(Additive White Gaussian Noise,AWGN)㊂第k个用户接收信号的SINR可以表示为:γk=|h H k UF DMA F BB,k|2σ2k+ðK iʂk|h H k UF DMA F BB,i|2㊂(10)1.2㊀问题描述雷达通信一体化系统需要权衡通信和雷达之间的性能㊂基于动态超表面天线的雷达通信一体化系统,在保证每个通信用户的SINR高于给定阈值前提下的式(10),使雷达传输波束的性能达到最优的式(8)㊂另外,加上预编码矩阵有功率限制和模拟预编码矩阵相位限制的式(2),雷达通信一体化系统传输波束成形设计问题可以表示为:㊀min FBB,F DMA L r(R,α)㊀㊀㊀㊀㊀㊀㊀㊀㊀㊀s.t.㊀ UF DMA F BB 2FɤP max,F DMA(i,l)=j+e jφi,l2,φi,lɪ[0,2π],|h H k UF DMA F BB,k|2σ2k+ðK iʂk|h H k UF DMA F BB,i|2ȡΓ,(11)式中:Γ为给定用户的SINR阈值㊂式(11)涉及到数字预编码矩阵和模拟预编码矩阵的联合设计,并且问题本身也是非凸的,很难求解㊂当天线架构为全数字天线架构时,该问题对应的问题容易求解,并且在用户SINR满足一定阈值时,其最优预编码矩阵获得的波束与理想波束十分相似㊂因此可以先求出全数字天线最优预编码矩阵,然后将动态超表面天线的模拟预编码矩阵和数字预编码矩阵拟合全数字天线的最优预编码矩阵,由此得到动态超表面天线的模拟与数字最优预编码矩阵㊂2㊀雷达通信一体化波束成形设计2.1㊀基于全数字天线架构先设计基于全数字天线架构的雷达通信一体化系统预编码矩阵W,使其在满足功率约束和用户SINR高于一定阈值前提下,雷达波束性能达到最优㊂其问题表示为:㊀㊀㊀min R L r(R,α)s.t.㊀R=WW HɪS+MW 2FɤP max|h H k w k|2σ2k+ðK iʂk|h H k w i|2ȡΓ,(12)式中:w i为W的第i列,W=(w1,w2 ,w K)㊂将第三个约束化简后的问题为:min R,RkL r(R,α)s.t.㊀R=WW HɪS+MW 2FɤP maxRkɪS+M,rank(R k)=1,k=1,2, ,K(1-Γ-1)h H k R k h kȡh H k Rh k+σ2k,(13)式中:R k=w k w H k,R=ðK k=1R k㊂由于其中的约束条件rank(R k)=1,k=1,2, , K是非凸的,可以先将其松弛掉,松弛后的问题是凸问题:min R,RkL r(R,α)s.t.㊀R=WW HɪS+MW 2FɤP maxRkɪS+M,k=1,2, ,K(1-Γ-1)h H k R k h kȡh H k Rh k+σ2kW=(w1,w2, ,w K),R k=w k w H k㊂(14)可以用Matlab中CVX工具箱求得最优解:R^, R^k,k=1,2, ,K㊂如果式(14)全局最优解满足R^kɪS+M,k=1,2, ,K 秩为1,那么求解式(13)中使用的松弛就是紧的,即松弛后问题的解也是原非凸问题的解㊂定理1㊀式(13)存在最优解R ~,R ~k ,k =1,2, ,K ,满足rank(R ~k )=1,k =1,2, ,K ㊂证明㊀R ^,R ^i ,i =1,2, ,K 为式(14)的全局最优解,将R ^,R ^i,i =1,2, ,K 做以下变换:R ~=R ^,w ~i =(h H i R ^i h i )-1/2R ^i h i ,R ~i =w ~i w ~H i ,R ~,R ~i ,i =1,2, ,K 为半正定矩阵且秩为一㊂因为R ~=R^,并且式(13)和式(14)的最终问题是相同的,所以R ~是式(13)全局最优解㊂现在只要证明R ~,R ~i ,i =1,2, ,K 为式(13)的可行解,则R ~,R ~i ,i =1,2, ,K 为式(13)的全局最优解㊂由于h H kR ~k h k =h H kw ~k w ~H k h k =h H k R ^k h k ,将其带入到(1-Γ-1)h H k R ~k h k=(1-Γ-1)h H k R ^k h k ȡh H k R ^k h k +σ2k =h H k R ~k h k +σ2k 满足式(13)的限制条件㊂所以R ~,R ~i ,i =1,2, ,K 为原问题的全局最优解㊂由定理1可知将式(14)最优解做以下变换:R ~=R ^,w ~k =(h H k R ^k h k )-1/2R ^k h k ,R ~k=w ~k w ~H k ,R ~k ɪS +M ,k=1,2, ,K 且秩为1,并且R ~仍为原问题的解㊂由此可以求解得到全数字天线最优预编码矩阵的列向量w k ,全数字天线架构的最优预编码矩阵W 也就可以求出㊂2.2㊀基于动态超表面天线架构在上节求解得到了全数字天线最优预编码矩阵,本节设计动态超表面天线架构预编码矩阵,使雷达通信一体化系统在满足功率约束㊁模拟预编码矩阵相位约束和通信用户信干扰加噪声比高于一定阈值前提下,最优拟合全数字天线预编码矩阵,其问题表示为:min F BB ,F DMAUF DMA F BB -W ~2Fs.t.㊀ UF DMA F BB 2F ɤP maxq i ,l =j +ej φi ,l2,φi ,l ɪ[0,2π]}{ɪF DMA ,∀i ,l|h H kUF DMA F BB,k|2σ2k+ðKi ʂk|h H kUF DMA F BB,i|2ȡΓ㊂(15)由于此问题不是凸问题,故将问题分解成设计两个子问题相互迭代来求解,两个子问题分别设计数字和模拟预编码矩阵㊂然而,数字和模拟预编码矩阵的设计问题都是非凸问题㊂为此,本文分别采用半正定松弛(Semidefinite Relaxation,SDR )技术[16-17]和黎曼共轭梯度(Riemannian Conjugate Gra-dient,RCG)算法[18]分别设计最优数字和模拟预编码矩阵㊂2.2.1设计模拟预编码矩阵当固定数字预编码矩阵F BB 设计最优模拟预编码矩阵时,限制条件只有模拟预编码矩阵的相位限制㊂其问题为:min FDMAUF DMA F BB -W ~2Fs.t.㊀q i ,l =j +ej φi ,l2,φi ,l ɪ[0,2π]}{ɪF DMA ,∀i ,l ㊂(16)由于问题是矩阵形式,不方便求解,所以将矩阵向量化:min FDMAUF DMA F BB -W ~2F =min F DMA(F T BB U )vec(F DMA )-w 2F ,式中:w =vec(W ~)㊂因为vec(F DMA )中的元素除了相位限制元素,其他为零元素㊂由于零元素的具体位置是已知的,所以可以先将零元素剔除掉㊂令q 为vec(F DMA )去除零元素后的向量,A 为(F T BB U )去除掉与vec(F DMA )零元素相对应的列向量㊂此时的问题转换为:㊀min F DMA(F T BB U )vec(F DMA )-w 2F =min q(Aq -w )H (Aq -w )=min qq H A H Aq -2q H A H w +w H w ㊂(17)由于模拟预编码矩阵的非零元素q i ,l 可以描述为圆心点为0,12e j π2(),半径为12的复平面圆上:q i ,l -12e j π2=12,定义向量b 为:b k =2q k -e j π2,所以q =12b +e j π21(),|b k |=1㊂最终可以将问题转换为关于向量b 的问题:min bq H A H Aq -2q H A H w +w H w =min b 14b +e j π21()H A H A b +e j π21()-b +e j π21()H A H w +w H w s.t.㊀|b k |=1ɪb ,(18)这时搜索空间为N T 个复数圆上,是一个N T的黎曼子流形,可以通过RCG 求得最优解b opt ㊂其中该问题的黎曼梯度为Δf (bt +1k)=AH㊃12A b t +1k +e j π21()-w ()㊂由于F DMA 非零位置是已知的,所以将最优解bopt扩展成矩阵形式,可以得到最优模拟预编码矩阵F opt DMA ㊂2.2.2设计模拟预编码矩阵当固定模拟预编码矩阵F DMA 时,限制条件为预编码矩阵功率约束和通信SINR 阈值约束,其问题为:㊀㊀㊀㊀min F BBUF DMA F BB -W ~ 2F㊀㊀㊀㊀s.t.㊀ UF DMA F BB 2FɤP maxh H k UF DMA F BB,k2σ2k+ðKi ʂk|h H kUF DMA F BB,i |2ȡΓ㊂(19)由于式(19)中第二个限制条件F BB 是按列展开的,所以将问题中的矩阵F BB 和W ~也按列展开:ðKk =1UF DMA F BB,k-W ~k 2F =ðK k =1F H BB,k F H DMA U H UF DMA F BB,k -2F H BB,k F H DMA U H W ~k +W ~Hk W ~k ㊂(20)展开后的问题并不容易求解,引入辅助变量t 2=1,可以化解成二次约束二次规划问题(Quadrati-cally Constrained Quadratic Programs,QCQP):v -k =F BB,kt(),Q k =F H DMA U H UF DMA ,-F H DMA U HW ~k ㊀㊀-W ~H k UF DMA ,W ~H k W ~k(),F H BB,k F H DMA U H U F DMA F BB,k -2F H BB,k F H DMA U H W ~k +W ~H k W ~k=v -H k Q v -k ㊂但此时,由于式(20)中第二个限制条件是非凸的,所以该问题也是非凸的㊂引用SDR 技术将问题进行化简,令V k =v -k v -H k ,rank(V k )=1,可以将问题简化为SDR 的标准形式:min V k ðKk =1tr(Q k V k )s.t.㊀ðKk =1trF H DMA U HUF DMA ,00,()V k ()ɤP max ,∀k ,trH k ,00,0()V k ()Γ-ðKi ʂktrH k ,00,()V i ()ȡσ2k ,tr0K ∗K ,00,1()V k ()=1,V k ȡ0,rank(V k )=1,H k =F H DMA U H h k h Hk UF DMA ㊂(21)由于约束项rank(V k )=1是非凸的,先将其松弛掉,之后的问题是凸问题,可以用Matlab 中CVX 工具箱求最优解V opt k ㊂如果该问题可解或有界,则ðKk =1[rank(V opt k )]ɤK +1,又因为每个用户的SINR 阈值限制,最优解满足:rank (V opt k )ȡ1,所以其最优解满足rank(V opt k )=1㊂由此证得rank(V k )=1的松弛是紧的,V opt k是原问题的最优解㊂F opt BB,k 是V optk的最大特征向量乘以最大特征值的平方根,因此,可以得到最优数字预编码矩阵F opt BB ㊂3 仿真分析本节采用数值仿真验证DMA 雷达通信一体化设计算法的性能,并且与全数字天线架构㊁基于相移器的混合波束天线架构和理想雷达波束进行对比㊂考虑雷达通信一体化基站的天线为均匀线性天线阵列,总发射功率为1W 和天线数量为24,其为用户提供通信服务并探测区域内目标㊂在探测区域内设置了方向为-40㊁0ʎ和40ʎ的3个理想目标,其波束表达式为:d (θ)=1,θ0-Δ2ɤθɤθ0+Δ20,㊀㊀otherwise{,(22)式中:Δ为理想波束的宽度,设置为2ʎ㊂当系统设计的DMA 射频链路为12个,信噪比设置为20dB 时,不同天线架构随角度变化的波速比较如图2所示㊂不同天线架构在满足用户需求前提下,使雷达波束达到最优的仿真,图中K =0㊁FD㊁DMA 和BP 线分别为理想目标波束㊁全数字天线架构波束㊁DMA 天线架构波束和基于相移器架构波束㊂可以看出,全数字天线的雷达波束图基本与理想的波束重合,DMA 天线架构和基于相移器架构也很好地还原了最优波束图,并且从中很容易查找出在-40ʎ㊁0ʎ和40ʎ方向有目标,因为这3个方向的波束峰值明显高于其他方向㊂图3是在4个通信用户SINR 的阈值从6dB 调整到14dB,不同天线架构随角度变化的波束比较㊂图2与图3对比可知,在通信用户阈值提高的情况下,DMA 架构和基于相移器的混合架构的目标雷达波束图峰值有明显的变差㊂图4是在6个通信用户信SINR 的阈值为6dB 情况下,不同天线架构随角度变化的波束比较㊂图2与图4对比可知,服务通信用户增加,目标雷达波束图峰值会变差㊂图5是在4个通信用户信SINR 的阈值为6dB,功率约束调整为2W 情况下,不同天线架构随角度变化的波束比较㊂图2与图5对比可知,增加发射功率,图5中目标雷达波束图峰值接近图2中目标峰值的2倍㊂图2㊀不同天线架构随角度变化的波束比较Fig.2㊀Comparison of beams varying by angle fordifferent antennaarchitectures图3㊀调整用户SINR 后的波束比较Fig.3㊀Beam comparison after adjusting theuser sSINR图4㊀调整用户个数后的波束比较Fig.4㊀Beam comparison after adjusting the number ofusers图5㊀调整功率约束后的波束比较Fig.5㊀Beam comparison after adjusting power constraints图6展示了基于DMA 的雷达一体化系统在不同发射功率情况下,用户SINR 阈值约束和雷达波束性能之间的权衡㊂可以看出,在发射功率一定时,随着用户SINR 阈值的增加,DMA 天线预编码矩阵与全数字天线预编码矩阵之间的均方差也在增加,并且发射功率为2W 时的均方差明显大于功率为1W 的设计㊂这是因为当通信质量要求增加时,为满足用户质量需要消耗更多的功率,而生成雷达波束的功率会变少,雷达波束性能也会变差㊂因此,降低通信质量要求,可以提高雷达波束性能㊂图6㊀用户SINR 阈值与雷达波束均方差之间关系Fig.6㊀Relationship between the user s SINR threshold andthe mean square deviation of the radarbeam4 结束语本文研究了基于动态超表面天线的雷达通信一体化系统,设计了相应的最优波束成形策略㊂采用了数字预编码矩阵与模拟预编码矩阵设计联合交替优化设计,分别应用半正定松弛和黎曼共轭梯度算法求解㊂数值仿真结果表明,所提算法设计的动态超表面天线架构的雷达通信一体化系统,在满足通信用户性能的前提下,其雷达性能接近理想雷达波束㊂动态超表面天线架构与基于相移器的混合波束天线架构整体性能相似,其雷达通信一体化系统中雷达与通信性能之间存在负相关,雷达性能随着通信性能的提高而降低㊂参考文献[1]㊀刘凡,袁伟杰,原进宏,等.雷达通信频谱共享及一体化:综述与展望[J].雷达学报,2020,10(3):467-484. [2]㊀ZHENG L,LOPS M,ELDAR Y C,et al.Radar and Com-munication Coexistence:An Overview:A Review of RecentMethods[J].IEEE Signal Processing Magazine,2019,36(5):85-99.[3]㊀CHU J,LIU R,LIU Y,et al.AN-aided Secure Beamform-ing Design for Dual-functional Radar-communication Sys-tems[C]ʊ2021IEEE/CIC International Conference onCommunications in China(ICCC Workshops).Xiamen:IEEE,2021:54-59.[4]㊀LIU X,HUANG T,SHLEZINGER N,et al.Joint TransmitBeamforming for Multiuser MIMO Communications andMIMO Radar[J].IEEE Transactions on Signal Process-ing,2020,68:3929-3944.[5]㊀KAUSHIK A,MASOUROS C,LIU F.Hardware EfficientJoint Radar-communications with Hybrid Precoding andRF Chain Optimization[C]ʊICC2021-IEEE InternationalConference on Communications.Montreal:IEEE,2021:1-6.[6]㊀LIU F,MASOUROS C.Hybrid Beamforming with Sub-arrayed MIMO Radar:Enabling Joint Sensing and Commu-nication at mmWave Band[C]ʊICASSP2019-2019IEEE International Conference on Acoustics,Speech andSignal Processing(ICASSP).Brighton:IEEE,2019:7770-7774.[7]㊀CHENG Z,LIAO B,HE Z.Hybrid Transceiver Design forDual-functional Radar-communication System[C]ʊ2020IEEE11th Sensor Array and Multichannel Signal Process-ing Workshop(SAM).Hangzhou:IEEE,2020:1-5. [8]㊀CHENG Z,HE Z,LIAO B.Hybrid Beamforming for Multi-carrier Dual-function Radar-communication System[J].IEEE Transactions on Cognitive Communications and Net-working,2021,7(3):1002-1015.[9]㊀CHEN C Y,VAIDYANATHAN P.MIMO Radar Wave-form Optimization with Prior Information of the ExtendedTarget and Clutter[J].IEEE Transactions on Signal Pro-cessing,2009,57(9):3533-3544.[10]DAI Y,HAN K,WEI G,et al.Hybrid Beamforming forDFRC System Based on SINR Performance Metric[C]ʊ2021IEEE/CIC International Conference on Communicationsin China(ICCC Workshops).Xiamen,IEEE,2021:82-87.[11]LAN G,IMANI M F,DEL HOUGNE P,et al.WirelessSensing Using Dynamic Metasurface Antennas:Challengesand Opportunities[J].IEEE Communications Magazine,2020,58(6):66-71.[12]SMITH D R,YURDUSEVEN O,MANCERA L P,et al.Analysis of a Waveguide-fed Metasurface Antenna[J].Physical Review Applied,2017,8(5):054048. [13]ZHANG H,SHLEZINGER N,GUIDI F,et al.Beam Focu-sing for Near-field Multiuser MIMO Communications[J].IEEE Transactions on Wireless Communications,2022,21(9):7476-7490.[14]SHLEZINGER N,ALEXANDROPOULOS G C,IMANI M F,et al.Dynamic Metasurface Antennas for6G ExtremeMassive MIMO Communications[J].IEEE WirelessCommunications,2021,28(2):106-113. [15]SHLEZINGER N,DICKER O,ELDAR Y C,et al.Dynam-ic Metasurface Antennas for Uplink Massive MIMO Sys-tems[J].IEEE Transactions on Communications,2019,67(10):6829-6843.[16]LUO Z Q,MA W K,SO A M C,et al.Semidefinite Relax-ation of Quadratic Optimization Problems[J].IEEE Sig-nal Processing Magazine,2010,27(3):20-34. [17]ZHANG S.Quadratic Maximization and Semidefinite Re-lax-ation[J].Mathematical Programming,2000,87:453-465.[18]YU X,SHEN J C,ZHANG J,et al.Alternating Minimiza-tion Algorithms for Hybrid Precoding in Millimeter WaveMIMO Systems[J].IEEE Journal of Selected Topics inSignal Processing,2016,10(3):485-500.作者简介:㊀㊀高㊀克㊀男,(1994 ),硕士研究生㊂主要研究方向:雷达通信信号处理㊂张海洋㊀男,(1987 ),博士研究生㊂主要研究方向:无线通信信号处理㊁面向6G近场无线通信㊂王保云㊀男,(1967 ),博士,教授㊂主要研究方向:香农信息论㊁无线通信中的博弈与协作㊁无线通信中的信号处理技术㊁视频信息的分析与理解㊂。
卫星通信在数据链系统中的应用
通信网络技术ＤＯＩ：１０．１９３９９／ｊ．ｃｎｋｉ．ｔｐｔ．２０２３．０１．０５０卫星通信在数据链系统中的应用韩路（中国电子科技集团公司第二十研究所，陕西西安710068）摘要：在科技时代中，得益于通信技术、互联网技术等先进技术的出现，电子信息技术得到了飞速发展。
数据链系统在众多领域内获得了广泛应用，能够为数据信息的传输提供安全、可靠的保障，已经成为了现代通信系统中的一个重要组成部分。
而在电子信息技术的驱动下，数据链也正在朝着高速率、大容量的方向发展，在这种大背景下，采用具有覆盖面广、通信质量高的卫星通信技术来弥补数据链通信距离限制已经成为了数据链系统创新发展的一大趋势。
首先针对卫星数据链的发展现状进行了阐述，并在此基础上对卫星通信在数据链系统中的具体应用进行了分析，期望能够对数据链系统的发展提供一些理论借鉴。
关键词：卫星通信；数据链系统；互联网技术；电子信息技术Application of Satellite Communication in Data Link SystemHAN Lu(The 20th Research Institute of China Electronics Technology Group Corporation, Xi’an 710068, China) Abstract: In the age of science and technology, thanks to the emergence of advanced technologies such as communication technology and Internet technology, electronic information technology has developed rapidly. Data link system has been widely used in many fields, can provide safe and reliable guarantee for the transmission of data information, has become an important part of the modern communication system. Driven by electronic information technology, data link is also developing towards the direction of high speed and large capacity. Under this background, it has become a trend of innovation and development of data link system to use satellite communication technology with wide coverage and high communication quality to make up for the limitation of data link communication distance.Firstly, the development status of satellite data link is described, and on this basis, the specific application of satellite communication in data link system is analyzed, hoping to provide some theoretical reference for the development of data link system.Keywords: satellite communication; data link system; Internet technology; electronic information technology0 引 言近年来，世界各国针对数据链的研究开始逐渐增加，而对数据链系统展开研究的主要目的是能够让其适应现代科技环境中对信息传输的高精准度和全方位特征要求，旨在提升对信息数据的掌控水准，并同时满足对数据信息通信的高质量要求。
通信雷达一体化波形设计及信号处理
通信雷达一体化波形设计及信号处理摘要：近年来我国社会会发展迅速，科技不断进步。
随着现代信息技术的快速发展，人工智能、大数据等技术与传统的电子信息领域深度融合，催生出沉浸式体验、全息传送、拓展现实、数字孪生等一系列新兴业务，这些新兴业务的实现往往依赖于多种传统的信息技术手段。
业务量的增加本质上是对带宽资源需求的扩张，而在频谱拥塞问题日益严重的今天，更好地推进信息技术需要发展一体化技术。
得益于先进的数字信号处理技术，雷达感知和无线通信系统可以采用相似的架构实现，这使感知通信一体化成为可能。
该技术通过共享收发系统，实现更有效、更紧凑的硬件设计，能够显著提升资源利用效率，因此受到了许多研究机构的关注。
关键词：通信雷达；一体化；波形设计；信号处理引言作为使用无线频谱的两种典型方式，通信和雷达在各自领域内取得了深入发展。
近年来，为提高平台智能化水平，在同一平台中同时配置通信和雷达两种功能的需求日益强烈。
传统意义上，配置通信和雷达功能，需要两套独立硬件，但这极大地增加了硬件成本，也给系统集成带来了较大困难。
近年来，通信雷达一体化设计理念被提出，其基本思想是：前端共用射频通道及天线，后端采用统一数字处理硬件。
由于该方法能够将通信和雷达功能在同一硬件平台中实现，因此能够极大地降低硬件成本、减小系统集成复杂度，从而近年来得到了广泛关注。
1雷达通信一体化基本概念及其优势雷达通信一体化是指在同一软件或者硬件平台上实现雷达探测和无线通信两种功能。
2021年，WeijieYuan等人提出，在车联网场景中，路边小基站通过接收到的回波信号估计车辆的位置和速度等各种运动相关参数，借助这些信息，在基站发射端预测雷达信道参数，在下一次发送一体化信号之前做预处理来补偿雷达信道的路径损耗和多普勒频移，车辆接收到基站发射的信号后可以绕过复杂的信道估计进行下行传输。
2015年，DCiuonzo等人为了实现在雷达感知过程中的隐蔽通信，采用了一种经济有效的方法，将通信信号嵌入雷达回波，以掩盖通信数据传输。
非确知先验信息条件下MIMO雷达波形设计
收稿日期：2019-10-21修回日期：2019-12-07基金项目：国家自然科学基金项目（61301258，61401526）；国家博士后面上项目一等（2016M590218）；国家自然科学基金应急管理基金资助项目（11847113）作者简介：姚遥（1984-），男，河南周口人，硕士，讲师。
研究方向：MIMO 雷达信号处理。
*摘要：考虑了目标先验知识未确知条件下，提升基于多输入多输出正交频分复用（MIMO-OFDM ）雷达的空时自适应处理（STAP ）最差条件下检测概率的稳健波形设计问题。
在发射波形恒模特性及目标参数不确定凸集约束下，基于最大化输出信干噪比（SINR ）准则，构建了提高最差条件下MIMO-OFDM-STAP 检测性能的极大极小波形优化问题。
为求解所得NP-hard 问题，先将发射波形恒模特性松弛为低峰均比约束，而后利用对角加载（DL ）将其重构为可有效求解的半定规划（SDP ）问题。
与传统非相关信号和主流非稳健算法相比，数值仿真验证了该算法可显著提升MIMO 雷达目标检测的稳健性。
关键词：多输入多输出雷达，正交频分复用，空时自适应处理，稳健波形优化，半定规划中图分类号：TN951文献标识码：ADOI ：10.3969/j.issn.1002-0640.2020.12.011引用格式：姚遥，周吉生，李琼，等.非确知先验信息条件下MIMO 雷达波形设计［J ］.火力与指挥控制，2020，45（12）：57-63.非确知先验信息条件下MIMO 雷达波形设计*姚遥1，周吉生2，李琼3，王洪雁4（1.周口师范学院物理与电信工程学院，河南周口466000；2.周口科技职业学院汽车工程系，河南周口466000；3.周口市农业科学院，河南周口466000；4.大连大学信息工程学院，辽宁大连116622）MIMO Radar Waveform Design withImperfect Prior InformationYAO Yao 1，ZHOU Ji-sheng 2，LI Qiong 3，WANG Hong-yan 4（1.School of Physics and Telecommunication Engineering ，Zhoukou Normal University ，Zhoukou 466000，China ；2.Department of Automotive Engineering ，Zhoukou Vocational College of Science and Technology ，Zhoukou 466000，China ；3.Zhoukou Academy of Agricultural Science ，Zhoukou 466000，China ；4.School of Information Engineering ，Dalian University ，Dalian 116622，China ）Abstract ：The robust waveform design issue is considered here to improve the worst -casedetection performance of multi-input multi-output orthogonal frequency division multiplexing （MIMO-OFDM ）radar based STAP in the case of imperfect target prior knowledge.With the transmitting waveform constant characteristic and the convex set of target parameter uncertainty ，under the criterionof maximizing the output signal -to -interference -and -noise -ratio （SINR ），the max -min waveform optimization problem can be constructed to better the worst -case detection performance of MIMO -OFDM-STAP.In order to solve the resultant NP-hard problem ，the constant envelope characteristic ofthe transmitting waveform can be firstly relaxed as the low peak-average-ratio （PAR ）constraint ，in what follows ，this issue can be reformulated as a semidefinite programming （SDP ）one by exploiting diagonal loading （DL ）to acquire an effective solution.In comparison with the traditional uncorrelated signals and state-of-the-art non-robust algorithm ，numerical results verify that the robustness of the target detection of MIMO radar can be improved considerably via the proposed algorithm.文章编号：1002-0640（2020）12-0057-07Vol.45，No.12Dec ，2020火力与指挥控制Fire Control &Command Control 第45卷第12期2020年12月57··（总第45-）火力与指挥控制2020年第12期0引言相较于传统相控阵仅可发射相干信号，多输入多输出（Multiple-Input Multiple-Output，MIMO）雷达可同时发射互不相关波形，并在接收端对所有回波联合处理以获得目标检测及参数估计结果［1-2］，MIMO雷达可提升干扰相消能力，增强参数辨识性和发射方向图设计的灵活性［3］。
通用汽车生产系统SGMGMSCONCEPT
Five GM-GMS Principles
五项原则
不断改进
人员参与
标准化
缩短制造 周期
制造质量
9
GMS（Global Manufacturing System） 全球制造体系
Thinking Way 精益概念
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GMS（Global Manufacturing System） 全球制造体系
Purpose of GMS is to make lean-thinking People & lean Processes to deliver lean Results for the Customer
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GMS（Global Manufacturing System） 全球制造体系
System Position 系统所在的位置
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GMS（Global Manufacturing System） 全球制造体系
How WE are MEASURED
如何衡量我们的业绩
Safety安全 People人员发展
想学丰田生产体系 TPS • Toyota wanted to learn about manufacturing in the U.S. 丰
田想学如何在美国造车 • Each GM unit was free to study TPS and implement as they
saw fit 每个GM的工厂都可以学习TPS,并按需实施
Tools工具 Tools工具
Methods标准
Tools工具 Tools工具
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GMS（Global Manufacturing System） 全球制造体系
Structure Explanation 结构说明
一种分布式雷达红外复合制导信息融合方案
火控雷达技术Fire Control Radar Technology第50卷第1期（总第195期）2021年3月Vol. 50 No. 1( Soics 195)Mao 2021一种分布式雷达/红外复合制导信息融合方案李时光李云职晓磨国瑞（西安电子工程研究所西安710100）摘 要：多模复合制导技术可以使不同传感器的检测、跟踪及抗干扰等性能得以互补，从而提升导 引头的整体性能。
以毫米波雷达/红外成像复合制导系统为研究背景，设计了 一种分布式信息融合方案，在此基础上制定了信息融合系统的融合策略％最后通过几组外场试验,对该信息融合方案进 行了测试验证，结果表明，该方案可有效提高导引头的跟踪性能及抗干扰能力％关键词:复合制导；分布式；信息融合;抗干扰中图分类号:TN957.51 &TN958 文献标志码:A 文章编号：1008 -8652 (2021)01 -081 -05引用格式:李时光，李云，职晓，磨国瑞• 一种分布式雷达/红外复合制导信息融合方案[J ].火控雷达技术,2021,50( 1)：81 -85 +93.DOI ：10.19472/j. eki. 1008 -8652.2021.01.015A Distributed Information Fusion Concept for Radar and IR Combined Guidance SystemLI Shiguang $ LI Yun , ZHI Xiao , MO Guooi(Xidn Electronic EngineeOng Research Institute , Xidn 710100 )Abstract : Multimode combined guidance technology makes it possible for functions of dideont sensors , such as de tection ,tracking , and anti-jamming , complement each other so that tuv overall peObonanco of seekers is improved.Thd paper proposes a ddtributed infoonation fusion concept for millimeter-Dave radar and infrared imaainy com bined guidance systems. In addition , the information fusion sWateaivs are descrided. At last , fled test results prove that the proposed infoonation fusion concept can improve the locking and anti-jamming peObonanco of seekers.Keywords ： combined guidance; distriduted; infoonation fusion ； anti-jammingo 引言现代战争的战场环境日益复杂，电子对抗的手 段也越来越多样化，这就对精确制导武器的探测精度、抗干扰能力及稳定性提出了越来越高的要求。
一种超分辨OFDM雷达通信一体化设计方法（论文）
第38卷第2期电子与信息学报 Vol.38No.2 2016年2月 Journal of Electronics & Information Technology Feb. 2016一种超分辨OFDM雷达通信一体化设计方法刘永军* 廖桂生 杨志伟 许京伟(西安电子科技大学雷达信号处理国家重点实验室西安710071)摘要：传统OFDM雷达通常不考虑传递通信信息，该文设计出一种新的基于OFDM的雷达发射方式以实现雷达和通信的一体化，并提出一种基于通信信息补偿的目标距离速度联合高分辨估计方法。
所设计的雷达发射方式，采用脉冲发射，每个脉冲由多个OFDM符号构成，在脉冲内实现通信功能；在雷达相干处理时间内，对回波进行通信信息补偿和解相干处理后，采用子空间投影方法实现对目标距离和速度的联合超分辨估计。
理论分析和仿真实验表明，所提方法能够在保证通信功能的条件下，可有效实现雷达目标距离和速度的联合超分辨估计。
关键词：雷达通信一体化；正交频分复用；距离速度联合估计；超分辨中图分类号：TN957.51 文献标识码：A 文章编号：1009-5896(2016)02-0425-09 DOI:10.11999/JEIT150320A Super-resolution Design Method for Integration ofOFDM Radar and CommunicationLIU Yongjun LIAO Guisheng YANG Zhiwei XU Jingwei(National Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China)Abstract: The traditional OFDM radar is usually without regard to transmit communication information. A new radar transmitting pattern based on OFDM is designed to realize the integration of radar and communication. Anda new method based on compensated communication information is proposed to achieve joint high-resolutionestimation of targets’ ranges and velocities. In the designed radar transmitting pattern, the radar transmits pulse consisting of multi-OFDM symbols and the communication function is realized within the pulse. During coherent processing interval, the subspace projection method is used to obtain the joint super-resolution estimation of ranges and velocities of targets after the echo data is compensated using communication information and induced non-coherent. Theoretical analysis and simulation results show that the proposed method can obtain the joint super-resolution estimation of targets’ distances and velocities under the condition of guaranteeing the communication function.Key words:Integration of radar and communication; OFDM; Joint estimation of range and velocity; Super- resolution1引言随着科技的不断发展，为了满足新战场环境下的军事需求，同一作战平台上安装的电子装备逐渐增多，造成系统体积、能耗和重量增大，操作复杂，冗余加大，设备间的电磁干扰加重，系统性能下降等诸多问题。
具有可解释性的OFDM雷达信号识别方法
第18卷 第2期太赫兹科学与电子信息学报Vo1.18，No.2 2020年4月 Journal of Terahertz Science and Electronic Information Technology Apr.，2020 文章编号：2095-4980(2020)02-0228-07具有可解释性的OFDM雷达信号识别方法葛鹏1，张文强1，金炜东1，郭建1，何贤坤 2(1.西南交通大学 电气工程学院，四川 成都 610031；2.中国电子科技集团 第二十九研究所，四川 成都 610036)摘 要：针对目前正交频分复用(OFDM)雷达信号识别方法存在的问题，提出了一种具有可解释性的OFDM雷达信号识别方法。
该方法是通过基于树结构的流程优化(TPOT)和与模型无关的局部可理解的解释性(LIME)相结合对OFDM雷达信号进行识别。
针对OFDM雷达信号特性提取了复杂度特征和基于时频图矩阵的奇异值熵，组成特征向量；通过TPOT，得到表现最佳的机器学习流程；通过“解释器”解释预测结果，对识别结果做出是否识别正确的风险评估，同时可根据OFDM雷达信号的解释性，得到哪些信号不易区分。
实验表明，该方法对信噪比为0 dB时的OFDM雷达信号的识别率达91%，通过LIME给出的解释性可以判断数据集中不易区分的雷达信号类型。
关键词：OFDM雷达信号；机器学习；奇异值熵；流程优化；局部可理解的解释性中图分类号：TN911文献标志码：A doi：10.11805/TKYDA2018191An interpretable method for recognition of OFDM radar signalsGE Peng1，ZHANG Wenqiang1，JIN Weidong1，GUO Jian1，HE Xiankun2(1.College of Electrical Engineering，Southwest Jiaotong University，Chengdu Sichuan 610031, China；2.The 29th Research Institute of ChinaElectronics Technology Group Corporation，Chengdu Sichuan 610036，China)Abstract：In view of the existing problems in the current Orthogonal Frequency Division Multiplexing (OFDM) radar signal recognition method, this paper proposes an interpretable method for identification ofOFDM radar signals. The method which is based on Tree-based Pipeline Optimization Tool(TPOT) andLocal Interpretable Model-agnostic Explanations(LIME) is to identify OFDM radar signals. Firstly,according to the characteristics of OFDM radar signals, the complexity features and singular value entropyof time-frequency image matrix are extracted to form the feature vectors. Then through the TPOT，the bestperforming machine learning process is obtained. Finally，the interpretation result is interpreted by theinterpreter, and the result of the recognition is given as a risk assessment; meanwhile，according to theinterpretability of OFDM radar signals, those signals difficult to distinguish are determined. Theexperimental results show that the recognition rate of the OFDM radar signal with R SN=0 dB is 91%. Theinterpretability given by LIME can be utilized to determine the type of radar signal that is difficult todistinguish in the data set.Keywords：Orthogonal Frequency Division Multiplexing radar signal；machine learning；singular value entropy；Tree-based Pipeline Optimization Tool；Local Interpretable Model-agnostic Explanations正确识别雷达信号调制方式不仅是雷达信号参数估计的前提，而且对雷达辐射功能推测，进而判断雷达的威胁等级有着重要意义[1]。
基于期望最大化算法的捷变频联合正交频分复用雷达高速多目标参数估计
基于期望最大化算法的捷变频联合正交频分复用雷达高速多目标参数估计全英汇 高 霞* 沙明辉 陈侠达 李亚超 邢孟道 岳超良(西安电子科技大学雷达信号处理国家重点实验室 西安 710071)摘 要：参数估计对雷达的目标检测和识别有着重要的意义。
该文提出了一种基于期望最大化(EM)算法的捷变频联合正交频分复用(FA-OFDM)雷达高速多目标参数估计方法。
首先，将窄带正交频分复用(OFDM)信号与传统捷变频雷达相结合，在每个脉冲宽度内同时发射多个载频随机跳变的子载波。
然后，对单个脉冲内所有子载波的回波进行脉冲压缩和稀疏重构处理，得到1维高分辨距离。
进一步地，将多个目标在不同脉冲时刻的高分辨距离信息构成观测数据，建立混合高斯模型。
采用EM 算法对模型参数和多个目标的距离、速度进行估计，并同时拟合多条时间-距离直线。
直线斜率对应目标速度，直线纵轴截距对应目标初始距离。
最终，分别分析了信噪比(SNR)对检测概率以及目标速度对相对估计误差的影响。
仿真实验验证了所提算法的有效性。
关键词：捷变频联合正交频分复用雷达；参数估计；高速多目标；EM 算法中图分类号：TN957.51文献标识码：A文章编号：1009-5896(2020)07-1611-08DOI : 10.11999/JEIT190474High Speed Multi-target Parameter Estimation for FA-OFDM RadarBased on Expectation Maximization AlgorithmQUAN Yinghui GAO Xia SHA Minghui CHEN XiadaLI Yachao XING Mengdao YUE Chaoliang(National Key Laboratory of Radar Signal Processing , Xidian University , Xi ’an 710071, China )Abstract : Parameter estimation is very important for radar to detect and recognize targets. In this paper, a high speed multi-target parameter estimation method for Frequency Agility-Orthogonal Frequency Division Multiplexing(FA-OFDM) radar based on Expectation Maximization(EM) algorithm is proposed. Firstly, a promising idea is to combine narrowband Orthogonal Frequency Division Multiplexing (OFDM) signals and frequency agility, multiple subcarriers that frequency hopping randomly are simultaneously transmitted within each pulse width. Then, all echoes of a single pulse are compressed and sparsely reconstructed to achieve 1-demension high range resolution. Subsequently, the high resolution range of multiple targets at each pulse time are obtained to constitute the observation data, and Gauss mixture model is established. EM algorithm is applied to estimate the parameters of the model and the range and velocity of multiple targets. Also, multiple time-range lines are fitted at the same time, and the slope of the line corresponds to the velocity of the target,as well as, the vertical intercept of the line corresponds to the initial range of the target, separately. Finally, the influence of the Signal-to-Noise Ratio (SNR) on detection probability and the target velocity on relative error of estimation are analyzed, respectively. Simulations are provided to verify the effectiveness of the proposal.Key words : Frequency Agility-Orthogonal Frequency Division Multiplexing (FA-OFDM) radar; Parameter estimation; High speed multi-target; Expectation Maximization (EM) algorithm1 引言正交频分复用(Orthogonal Frequency DivisionMultiplexing, OFDM)技术易于实现频谱资源控制和无线环境下的高速传输，因而被首先应用于通信领域。
恒包络OFDM雷达通信一体化信号设计
Z H A N G Q iu yu e，Z H A N G L in ran g ，G U Y ab in ，Z H O U Y u (N ational L aboratory of R adar Signal P rocessing， Xidian U n iv ersity，X i?an 710071，China)
7 倍 ，利 于 实 现 雷 达 高 分 辨 率 、高 检 测 概 率 探 测 ，且 随 着 序 列 长 度 增 加 ，距 离 分 辨 率 提 高 ；通过控制
通 信 加 权 系 数 的 大 小 ，可 在 雷 达 和 通 信 性 能 之 间 取 得 最 佳 折 中 。 关 键 词 ：雷 达 通 信 一 体 化 ；O F D M 信 号 ；模 糊 函 数 ；误码率 中 图 分 类 号 ： T N 957 文 献 标 志 码 ：A 文 章 编 号 ： 0253-987X (2 0 1 9 )06-0077-08
第 53卷 第 6 期 2019年 6 月
JOURNA西L O安F X交P AN通 JIA大OT学ONG学 UN报IVERSITY
Vol.53 N o .6 Jun. 2019
D O I ： 10. 7 65 2/x j t u x b 201906011
恒 包 络 OFDM 雷达通信一体化信号设计
m odulations are perform ed to divide a phase into tw o
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速腾雷达工作原理
速腾雷达工作原理Volkswagen's Sagitar radar system, commonly known as the "Sagitar Radar", is a crucial component in the advanced driver assistance systems (ADAS) of modern vehicles. It uses radio waves to detect objects in the vehicle's vicinity, providing crucial information to the driver to enhance safety on the road.雷达系统通过发射无线电波并接收反射回来的信号来探测周围的物体，从而帮助驾驶员做出正确的决策。
One of the key principles behind the Sagitar radar system is the concept of radar waves bouncing off objects and returning to the radar sensor. This phenomenon, known as radar reflection, allows the system to detect the distance, size, and speed of objects in the vehicle's vicinity.雷达波将会与遇到的物体发生反射，之后返回雷达传感器，通过这一现象，系统可以检测到车辆周围物体的距离、大小和速度。
The Sagitar radar system operates by emitting electromagnetic waves in a specific frequency range, typically in the microwave spectrum. These waves travel through the air until they encounter an object, at which point they are reflected back towards the radar sensor. This enables the system to calculate the time taken for thewaves to return and determine the distance to the object.速腾雷达系统是通过在特定频率范围内发射电磁波来工作的，通常处于微波频谱范围内。
基于多载波调制的太赫兹通信感知一体化系统性能联合优化
ｄｏｉ：１０．３９６９／ｊ．ｉｓｓｎ．１００３－３１１４．２０２４．０１．００８引用格式：李涟漪，余显斌，张鹿．基于多载波调制的太赫兹通信感知一体化系统性能联合优化［Ｊ］．无线电通信技术，２０２４，５０（１）：７４－８０．［ＬＩＬｉａｎｙｉ，ＹＵＸｉａｎｂｉｎ，ＺＨＡＮＧＬｕ．ＰｅｒｆｏｒｍａｎｃｅＪｏｉｎｔＯｐｔｉｍｉｚａｔｉｏｎｆｏｒＩｎｔｅｇｒａｔｅｄＳｅｎｓｉｎｇａｎｄＣｏｍｍｕｎｉｃａｔｉｏｎＳｙｓｔｅｍＢａｓｅｄｏｎＭｕｌｔｉｃａｒｒｉｅｒＭｏｄｕｌａｔｉｏｎ［Ｊ］．ＲａｄｉｏＣｏｍｍｕｎｉｃａｔｉｏｎｓＴｅｃｈｎｏｌｏｇｙ，２０２４，５０（１）：７４－８０．］基于多载波调制的太赫兹通信感知一体化系统性能联合优化李涟漪，余显斌，张 鹿（浙江大学信息与电子工程学院，浙江杭州３１００２７）摘 要：单一的雷达指标和通信指标难以评价通信感知一体化（ＩｎｔｅｇｒａｔｅｄＳｅｎｓｉｎｇａｎｄＣｏｍｍｕｎｉｃａｔｉｏｎ，ＩＳＡＣ）系统的整体性能，不同的ＩＳＡＣ应用场景对通信和雷达的性能需求不同。
提出了ＩＳＡＣ联合优化方案，能够将通信指标和雷达指标联合，并使一体化波形根据不同场景做适应性改变，提高了ＩＳＡＣ系统整体性能。
推导了雷达条件互信息（ＭｕｔｕａｌＩｎｆｏｒｍａｔｉｏｎ，ＭＩ）和通信数据信息速率（ＤａｔａＩｎｆｏｒｍａｔｉｏｎＲａｔｅ，ＤＩＲ），在总功率的约束下，设计并实现了雷达ＭＩ和通信ＤＩＲ的联合优化方案，通过求解凸函数优化问题得到了优化的发射功率，从而优化一体化波形。
通过仿真和实验验证了联合优化方案的有效性，对比了基于正交频分复用（ＯｒｔｈｏｇｏｎａｌＦｒｅｑｕｅｎｃｙＤｉｖｉｓｉｏｎＭｕｌｔｉｐｌｅｘｉｎｇ，ＯＦＤＭ）信号和正交啁啾分复用（ＯｒｔｈｏｇｏｎａｌＣｈｉｒｐＤｉｖｉｓｉｏｎＭｕｌｔｉｐｌｅｘｉｎｇ，ＯＣＤＭ）信号调制的光子太赫兹一体化系统的优化效果，得出ＯＦＤＭ一体化系统具有更好的优化效果，性能提升较大。
雷达英文-
雷达英文RadarIntroductionRadar is an acronym for “radio detection and ranging.” A radar system is an electromagnetic sensor that is used to detect, locate, and track the position and velocity of objects. Radar systems work by sending out electromagnetic waves, which are then reflected off objects in their path. By examining the echoes of these waves, radar systems can determine the range, bearing, and velocity of objects. Radar systems are used in a variety of applications, including military and civilian aviation, weather forecasting, maritime navigation, and traffic control.HistoryThe development of radar can be traced back to the early 20th century. In 1904, German physicist Christian Hülsmeyer demonstrated the first rudimentary radar system, which he called a “telemobiloscope.” This early experiment was based on the concept of sending out radio waves and detecting their echoes. However, the technology of the time was not advanced enough to create a practical radar system.During World War II, radar played a critical role in both military and civilian applications. The first operational radar system was developed by the British in the late 1930s, and it was used extensively during the Battle of Britain. Radar also played a key role in the development of the atomic bomb,as it was used to track the flight paths of the Enola Gay and Bockscar, the two planes that dropped the atomic bombs on Hiroshima and Nagasaki.After World War II, radar technology continued to evolve. In the 1950s, the development of pulse radar allowed for higher accuracy and better range resolution. In the 1970s, the introduction of digital signal processing made it possible to extract more information from radar signals.Types of RadarThere are several different types of radar systems that are used for different applications. Some of the most common types include:1. Primary Radar: This type of radar system sends out radio waves and detects their echoes to determine the range, bearing, and velocity of objects. Primary radar is used in air traffic control, maritime navigation, and weather forecasting.2. Secondary Radar: This type of radar system is used in aviation to interrogate an aircraft’s transponder, which responds with information such as the aircraft’s altitude and identification.3. Synthetic Aperture Radar (SAR): SAR is an imaging radar system that uses radar waves to create detailed images of the ground. SAR is used in a variety of applications, including mapping, agriculture, and disaster response.4. Pulse Doppler Radar: This type of radar system is used to detect moving objects, such as aircraft or weather patterns. Pulse Doppler radaruses the Doppler effect to determine the velocity of objects based on the frequency shift of the radar waves.5. Phased Array Radar: Phased array radar systems use multiple antenna elements that can be electronically steered to create a beam of radar waves that can be directed in any direction. This makes these systems more flexible and adaptable than traditional radar systems.ApplicationsRadar systems are used in a wide range of applications. Some of the most common include:1. Aviation: Radar is used extensively in aviation for air traffic control, navigation, and weather forecasting.2. Maritime: Radar is used to navigate ships and boats, as well as to monitor weather and sea conditions.3. Military: Radar is used for a wide range of military applications, including surveillance, target acquisition, and missile guidance.4. Weather Forecasting: Radar is used to track weather patterns, including precipitation, clouds, and severe weather events.5. Automotive: Radar is used in some newer vehicles for adaptive cruise control, collision avoidance, and parking assist functions.ConclusionRadar technology has come a long way since its early beginnings in the early 20th century. Today, radar systems are critical for a wide range of applications, from aviation and maritime navigation to military surveillance and weather forecasting. As technology continues to evolve, it is likely that radar systems will become even more sophisticated and versatile, providing new and innovative solutions to the challenges of the modern world.。
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I. INTRODUCTION
Even though the idea of combining radar and communications in one single system platform has been existing for a long time [1], there has never been introduced any relevant implementation of such concept. A joint radar and communications system would constitute a unique costefficient platform for future intelligent transportation systems, for which both environment sensing and the allocation of adhoc communication links are essential tasks. The most important reason for not introducing such systems might be because traditional radar platforms and signals have been too different from their communications counterparts. Nowadays, when the baseband processing can be easily performed in the digital domain, these restrictions do not apply any longer. Also as a result of this progress, in recent years orthogonal frequency division multiplexing (OFDM) in combination with phase shift keying (PSK) has become a popular modulation technique in new communications standards. OFDM offers several advantages like robustness against multi-path fading, easy synchronization and equalization, and a high flexibility in system design, which allows for easily adapting the system parameters to the given channel characteristics. Furthermore, it has been shown that OFDM-like signals are also suitable for radar applications [2]. Also, it has already been proposed in literature to implement radar networks with integrated communications functions based on OFDM signals [3].
An OFDM System Concept for Joint Radar and Communications Operations
Christian Sturm, Thomas Zwick, and Werner Wiesbeck
Institut für Hochfrequenztechnik und Elektronik, University of Karlsruhe (TH) Kaiserstraße 12, 76131 Karlsruhe, Germany christian.sturm@a.de
N −1
x(t) = ∑ I (n)exp( j2πfnt), 0 ≤ t ≤ T
(5)
n=0
In the frequency domain this corresponds to
∑N −1
X ( f ) = I(n)
T sin(π ( f − f n )T )
n=0
(π ( f − f n )T )
In this paper the feasibility of the design of an OFDM system that even simultaneously allows for performing radar and communications operations is investigated. First, the OFDM signal structure is regarded and an already existing approach for OFDM radar processing is compared to a novel one that is proposed later in this paper. Requirements for the
Abstract—In this paper the possibility of designing an OFDM system for simultaneous radar and communications operations is discussed. A novel approach to OFDM radar processing is introduced that overcomes the typical drawbacks of correlation based processing. A suitable OFDM system parameterization for operation at 24 GHz is derived that fulfills the requirements for both applications. The operability of the proposed system concept is verified with MatLab simulations.
II. OFDM RADAR
Strictly speaking OFDM is not a modulation technique but a multiplexing technique, which allows for multiplexing the transmission of symbols over orthogonal subcarriers. These subcarriers are defined by basis functions
ψ n (t) = exp( j2πfnt)
1 rect⎜⎛ t ⎟⎞, T ⎝T ⎠
n = 0,…, N −1 (1)
with fn representing the individual subcarrier frequencies, T denoting the OFDM symbol duration, and N being the number of subcarriers. These basis functions are orthogonal when
Δf = 1
(2)
T
hence, this spacing has to be chosen in order to avoid intercarrier interference. With this choice we obtain for the individual subcarrier frequencies
fn = fmin + nΔf , n = 0,…, N −1
(3)
with fmin being an arbitrary frequency. An arbitrary information series {I(n)} consisting of complex modulation symbols obtained through discrete phase modulation (e.g. PSK) is converted to an OFDM signal by projecting the modulation symbols onto the orthogonal basis functions. The resulting time domain signal can be expressed as
∞ N −1
x(t) = ∑ ∑ I (μN + n)ψ n (t − μT )
(4)
μ =−∞ n=0
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where µ represents the time index of the subsequent OFDM symbols. From this result one single OFDM-symbol can be extracted by regarding only µ=0, which results in
system parameterization from both radar and communications perspective are analyzed. A parameterization for operation in the 24 GHz ISM band that allows for simultaneous operation of both functions is derived. Finally, simulation results for the novel processing approach from a MatLab model are presented.