rrh

RRH (Remote Radio Head)
기지국의구조는RF신호를송수신하여처리해주는RF Unit과이를디지털단에서통신신호처리를해주기위한BBC(Baseband Card)로구성되어있다. 기존의기지국은일종의셀터(컨테이너) 내부에일련의장비들을설치하는방식을취하고있는데, 이러한방식은비용이비싸고, 동축케이블의비효율성이중대한파워손실로이어졌다. RRH는“분산기지국” 형태를취하며적절한프로세싱과광학인터페이스로RF Unit 부분이안테나인근타워위의방수박스장치에설치되도록하는접근방법을취하며종전의문제점을해소하는솔루션이다. 또한거의모든부분이소프트웨어컨트롤러에의해작동되고, 작성된공중인터페이스조직단위내에다양한기술들을관리할수있도록구성되면서, 높은효율성, 낮은전력소비, 낮은기지국설치비용으로전세계통신업자들이선호하는시스템이다.
RRH(Remote Radio Head)는통신제어부문인베이스밴드와전파를직접전달하는라디오유닛(RU)으로구성되는기지국설비에서RU의일부를원격으로분리해기존중계기역할을할수있도록한장치입니다.
RRH를이용하면하나의베이스밴드에여러원격무선장비를둘수있어중계기의역할을기지국이대체할수있도록합니다. 따라서이동통신사들은기존기지국-중계기설비대신RRH를포함한기지국설비를늘려가며중계기시장이위협받고있다는평가를받고있기도합니다.
Remote radio heads (RRHs) have become one of the most important subsystems of today's new distributed base stations. The remote radio head contains the base station's RF circuitry plus analog-to-digital/digital-to-analog converters and up/down converters. RRHs also have operation and management processing capabilities and a standardized optical interface to connect to the rest of the base station. This will be increasingly true as LTE and WiMAX are deployed. Remote radio heads make MIMO operation easier; they increase a base station's efficiency and facilitate easier physical location for gap coverage problems. RRHs will use the latest RF component technology including GaN RF power devices and envelope tracking technology within the RRH RFPA.
RF(무선주파수)부품, RRH(원격무선장비), 기지국/차량용안테나, 중계기, 방산부품등을제조하는무선통신장비업체
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세계무선통신장비시장부동의1위업체인에릭슨의전략적파트너로서위상을확보하고있으며, 경쟁업체인Powerwave, Andrew는물론NSN, 알카텔-루슨트등과같은메이저무선통신장비업체와국내삼성전자(서울전자통신포함), LG에릭슨, SK텔레콤, KT 등의다양하고우량한거래처를확보하고있는데다, 차세대기지국의핵심장비로급부상하고있는RRH장비를2011년부터제품라인업에추가할예정이기때문이다.
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고용량무선데이타수요급증, 환경과미관을고려한친환경기지국구축필요성, 그린이슈에따른기지국의저전력소비요구등이이슈로부각되며차세대무선통신기지국(BTS)에대한관심이커지고있다. 특히4G의핵심기술인OFDM(직교주파수다중분할), MIMO(다중입출력)의효율적인구현이가능하게해주는RRH(Remote Radio Head; 원격무선장비)기술을적용한초소형기지
국이유력한방안으로급부상하고있다. 이와관련2010년5월원천기술을보유한영국AXIS 인수와함께7월NSN과RRH에대한개발및공급계약을체결한에이스테크놀로지는2011년1분기부터NSN과알카텔루슨트향납품을시작할예정이며2012년국내통신장비업체로의RRH매출도전망된다. 따라서인도의3G 상용서비스와함께북미, EU, 우리나라등주요통신선진국에서의LTE 활성화수혜로2011년부터실적호전이가속화될전망이다.
A Remote Radio Head is an equipment used in wireless telecom systems. This type of equipment will be used in all wireless technologies like GSM, CDMA, UMTS, LTE.
As this Radio equipment is remote to the BTS/NodeB/eNodeB, It is called Remote Radio Head. These equipments will be used to extend the coverage of a BTS/NodeB/eNodeB like rural areas or tunnels.
They are generally connected to the BTS/NodeB/eNodeB via a fiber optic cable using Common Public Radio Interface protocols.
Designing remote radio heads (RRHs) on high-performance FPGAs
Xiaofei Dong, Altera Corporation
2/7/2011 4:28 PM EST
Introduction
Current and future generations of wireless cellular systems feature heavy use of Remote Radio Heads (RRHs) in the base stations. Instead of hosting a bulky base station controller close to the top of antenna towers, new wireless networks connect the base station controller and remote radio heads through lossless optical fibers. The interface protocol that enables such a distributed architecture is called Common Publish Radio Interface (CPRI). With this new architecture, RRHs offload intermediate frequency (IF) and radio frequency (RF) processing from the base station. Furthermore, the base station and RF antennas can be physically separated by a considerable distance, providing much needed system deployment flexibility.
Typical advanced processing algorithms on RRHs include digital up-conversion and digital down-conversion (DUC and DDC), crest factor reduction (CFR), and digital pre-distortion (DPD). DUC interpolates base band data to a much higher sample rate via a cascade of interpolation filters. It further mixes the complex data channels with IF carrier signals so that RF modulation can be simplified.
CFR reduces the peak-to-average power ratio of the data so it does not enter the non-linear region of the RF power amplifier. DPD estimates the distortion caused by the non-linear effect of the power amplifier and pre-compensates the data. CFR and DPD protect the data, mitigate the effect of power amplifier non-linear distortions, and widen the operation range. However, CFR and DPD are computationally intensive and need to support very high throughput streaming data. Field programmable gate arrays (FPGAs) are an ideal platform for computationally-intensive RRH designs. Abundant hardened multipliers on an FPGA provide speed, area, and power reduction for highly
arithmetic RRH implementations.
More importantly, many wireless standards demand reconfigurability in both the base station and the RRH. For example, the 3GPP Long Term Evolution (LTE) and WiMax systems both feature scalable bandwidth. The RRH should be able to adjust – at run time – the bandwidth selection, the number of channels, the incoming data rate, among many other things. On the other hand, as FPGAs evolve with higher density, larger numbers of hardened multipliers, and more complex embedded processors, it has become possible to support multiple wireless standards in a single device. For instance, a US wireless vendor may support both WCDMA (UMTS) systems and 3GPP LTE systems from a single RRH card. A wireless operator in China may service the same location with both LTE and TD-SCDMA networks. With a multi-mode single device RRH solution, network providers can significantly reduce cost, power, and maintenance efforts in RRH applications.
With the requirement to design a multi-mode RRH on a single device, let’s examine a few system planning issues that should be considered in RRH designs. Factors, such as protocol support, number of antennas and carriers, as well as FPGA clock rate, affect how compact and efficient an RRH design will be. In this article we will focus on CPRI and DUC configuration.
RRH system model
Typically, a base station connects to a RRH via optical cables. On the downlink direction, base band data is transported to the RRH via CPRI links. The data is then up-converted to IF sample rates, preprocessed by CFR or DPD to mitigate non-linear effects of broadband power amplifiers, and eventually sent for radio transmission. A typical system is shown in Figure 1.
Figure 1. Block diagram of a typical RRH System
CPRI configuration
The CPRI specification is an initiative to define a publicly available specification that standardizes the protocol interface between the radio equipment control (REC) and the radio equipment (RE) in wireless base stations. This allows interoperability of equipment from different vendors, while preserving the software investment made by wireless service providers. Figure 2 illustrates a CPRI
interface.
Figure 2. CPRI Interface
When designing a RRH with a CPRI link, there are a few system level decisions that must be made regardless of the actual hardware implementation of the CPRI interface:
Determine the wireless standard being supported and thus what CPRI mapping method required What the number of antenna-carrier interface will be required per CPRI link
The CPRI line rate
The CPRI output data format
Each of these decisions will be discussed in the following sections.
CPRI support for multiple wireless standards
CPRI Specification v4.2 is based on the Universal Mobile Telecommunication System (UMTS), the WiMAX IEEE Std 802.16-2009, and the Evolved UMTS Terrestrial Radio Access (E-UTRA), with the possibility of supporting other wireless standards in future revisions of the CPRI specifications.
The three mapping method described in CPRI v4.2 targets only the three standards listed above. However, many CPRI IP vendors provide some flexibility in supporting customer defined mapping modules, which means it may be possible to support additional wireless standards.
CPRI frame structure
A basic CPRI frame has duration Tc=1/fc=1/3.84MHz = 260.41667ns. The basic frame structure is shown in Figure 3, where T is the word length given by (Line Rate in Mbps)/76.8, so it varies with the line rate. For a 3.072Gbps line rate, for example, T is 40. One hyperframe is made up from 256 basic frames, and a 10ms CPRI frame consists of 150 hyperframes.
A basic frame consists of 16 words, where the first word of each basic frame is a control word. The other 15 words are used to carry user plane data (SAPIQ) as shown in Figure 2. The user plane information is presented in the form of in-phase and quadrature base band data, or IQ data. The frame structure illustrated in Figure 3 dictates the amount of user plane data a particular line rate can
support. The next subsection is how to select line rate based on a user application.
Figure 3. Basic frame structure for different
CPRI line rates. T is the word length and
varies depending on the line rate [1].
Choosing the CPRI line rate
The basic frame structure in Figure 3 illustrates the amount of user plane data a particular line rate can carry. The following equation calculates how many data bits are available in a CPRI basic frame to carry IQ data:
The factor 15/16 accounts for the fact that out of the 16 words in a basic frame, 15 are data words. The factor 8/10 accounts for the 8B10B encoding that the CPRI specification requires in the Tx direction. Based on 8B10B, only 80% of the CPRI line capacity is used to transmit non-encoded data, with the other 20% being used on encoding redundancy.
Based on Equation (1), the number of IQ data bits per basic frame as a function of CPRI line rates is listed in Table 1.
Table 1. Number of IQ bits per basic frame
as a function of CPRI line rates.
The minimum CPRI line rate should be able to support a wireless system’s total bandwidth. That is, the amount of IQ data that comes across the CPRI link between the base station and the RRH during a 260.67ns period, must not exceed the number of IQ bits listed in Table 1for a given line rate.
The following example considers a single sector, mixed bandwidth LTE FDD system with two transmitting and two receiving antennas. Across a 20MHz allocated bandwidth per antenna, a 10MHz LTE carrier runs concurrently with two 5MHz LTE carriers.
In this example, a total of (1 + 2) x 2 = 6 antenna-carrier pairs, where the factor 2 is to account for 2 antennas on either the transmitting or the receiving side. Assume both I and Q data are 16-bit wide. The number of bits the 6 antenna-carrier pairs carry during a 260.67ns basic frame can be calculated as [Sample Rate (in MHz)/3.84] x 16 x 2 x [Number of AxCs]. In this example, total number of IQ bits from the application is:
30.72/3.84x32x2 + 7.68/3.84x32x4 = 768.
Compare 768 with the total number of IQ bits that a line rate supports shown in Table 1, where 4.9Gbps is the minimal line rate required for this application. Alternatively, multiple parallel CPRI links can be used to support high throughput high bandwidth applications. In most cases, however, having multiple parallel CPRI links complicates data path synchronization tasks in the actual implementation. It also requires multiple optical cables between REC and RE, which adds to the system setup and maintenance cost.
CPRI output data format
Although different users may implement CPRI and subsequent DUC designs differently, it is common that a framer or data re-formatter is needed between CPRI and DUC modules. A DUC is designed to maximize hardware reuse due to its computation complexity. To share the multiplier resources efficiently in the FIR filter chain, the input multi-channel data to the DUC usually needs to be arranged in a certain pattern. The data pattern should allow AxCs to access the FPGA logic and multiplier resources in a time division multiplexing (TDM) fashion. The framer or format converter design depends on the CPRI output data format and required DUC input data format. It is commonly implemented using the FPGA on chip memory.
DUC configuration
A typical DUC and DDC system for a single standard RRH is shown in Figure 4. Base band data is first filtered by a FIR channel filter, then upsampled. A final cascaded integrator and comb (CIC) filter provides a variable rate change. A CIC filter uses only addition and subtraction to realize low pass filtering, without resorting to multiplications. In multiplier hungry DUC designs, it is a highly hardware-friendly solution. The only drawback is that a FIR compensation filter is needed to alleviate the pass band droop problem in CIC filters [2]. A numerically controlled oscillator (NCO) generates digital sinusoidal waveforms and a complex mixer is needed to provide IF stage mixing.
Figure 4. Illustrative block diagram of a single mode
DUC and DDC on an FPGA.
When planning a DUC module, the biggest challenge is the filter design optimization. Needless to say, finding the optimal filter coefficients and filter order that meet the wireless transmission spectrum mask of various standards is a challenge. However, how the multiple filter cascades are partitioned also has a great impact on resource and power utilization. Similarly the IF carrier mixing may also be broken down into stages. When and where the data and carrier mixing should happen affects the resource utilization as well. In a RRH supporting multiple wireless standards, it is particularly important to reuse as much resource as possible; otherwise DUC itself can take up significant amount of logic and multiplier resources on the FPGA.
Choosing the FPGA clock rate and IF sample rate
Wireless applications are multi-channel applications because both inphase and quadrature signals are needed, across the entire data path. Multiple antenna (MIMO) configuration in all leading wireless standards such as LTE, WiMAX, TD-SCDMA require that even more data channels are supported simultaneously. As a result the FPGA logic must operate at the fastest rate attainable in order to process as many data channels as possible, using the same set of resources. To lower cost, hardware sharing has to be maximized and that also means selecting a higher FPGA clock rate.
In DUC applications, FPGA logic often runs at a clock frequency that is an integer multiple of the data path sample rate. Doing so enables most efficient resource sharing via time division multiplexing (TDM). Furthermore, data is aligned with clocks, therefore control logic and clocking schemes are simpler.
More recently the LTE standard has become the prominent candidate for next generation mobile broadband systems. As a result modern multi-mode RRH systems most likely will support at least the LTE specification. LTE is evolved from UMTS or Wideband CDMA. Wideband CDMA has chip rate of 3.84MHz, and LTE sample rates for all bandwidth selections are integral multiples of 3.84MHz. Table 2 shows the sample rate or clock rate of LTE RRH as an integral multiple of 3.84MHz. It is quite common that FPGA clock rate and IF sample rate are chosen from Table 2.
Table 2. List of sample rates as integral multiple of 3.84MHz.
Because LTE is evolved from WCDMA (UMTS), WCDMA will be supported effortlessly in most RRH systems targeting LTE. Other major wireless standards such as WiMAX, Multi-carrier GSM, TD-SCDMA, and CDMA2000 can also be supported in same DUC data path using sample rate converters. That is, the front end filtering in WiMAX, MC-GSM, TD-SCDMA and CDMA2000 systems need to convert the input sample rate to a value in Table 2. Doing so allows subsequent interpolation and IF carrier mixing to be shared with LTE data.
Among the possible FPGA clock rates, 245.76MHz is the most prevailing choice in modern high end FPGAs. It is fast enough to provide efficient and adequate resource sharing and low enough to be easily achievable. Since it is 64 times the base sample rate 3.84MHz, it is also possible to replace the traditional FIR and CIC filter combination with highly efficient half band filter cascades [3]. An interpolation half band filter raises the data sample rate by a factor of 2, where only half of the filter coefficients are non-trivial. In addition, half-band filter cascades typically require fewer taps (i.e. smaller filter order) than non-half band interpolation FIRs. As a result, the overall required multiplier count in the DUC may be fewer, although the actual design optimization needs to be evaluated on a case-by-case basis.
As technology progresses, future generations of FPGAs will feature more abundant hard multipliers and much faster logic speed. It is therefore possible and even desirable to move FPGA clock rates and IF sample rates even higher, such as 491.52MHz.
Design space exploration
A properly designed DUC module needs to meet the transmission spectrum mask requirement of the
wireless standards it supports. In addition, error vector magnitude (EVM) requirements also impact the filter coefficients selection. Regardless of the design criteria, multiple design iterations are commonly required.
The major areas of exploration include multiple stage filter partition and IF carrier mixing. Often along the data up-conversion filter chain, a very long filter with tight transition bandwidth requirements can be broken down into two or more filter cascades. Each new filter in the chain has relaxed cutoff frequency or transition bandwidth requirement. The total filter length may still be smaller than the original filter. In other cases, a half-band filter cascade can replace a traditional FIR filter chain to significantly reduce resources. This explains how and when the half band filter option can be selected in the previous section.
Intermediate frequency (IF) mixing using NCOs and complex mixers can also be broken down into stages. The first stage complex data mixing modulates IQ data onto low IF frequencies and sums them together. As a result, subsequent up-conversion filters handle fewer channels. The second stage mixing further modulates IF data to the final IF carrier frequency. The resource saving from filters between the first and second stage mixing can exceed the cost in implementing two stages of mixing. However the tradeoff needs to be evaluated based on actual system configuration.
Conclusion
In this article we discussed a few system level planning issues when designing a remote radio head system on an FPGA. CPRI is the interface protocol that enables the distributed architecture in base station. The number of MIMO antennas, the wireless standard being supported and the bandwidth selection all play a role in determining the minimum CPRI line rate requirement. The digital up and digital down converters interface the CPRI module on the RRH, and a format converter is often needed as glue logic. The DUC and DDC are designed to maximize resource reuse. Proper selection of FPGA clock rate, filter design partition and IF mixing design all play important roles in resource optimization.
References
[1] Common Public Radio Interface (CPRI) Interface Specification, v4.2, Sept. 29, 2010.
[2] Eugene B. Hogenauer, “An economical class of digital filters for decimation and interpolation,” IEEE Transactions on Acoustics, Speech and Signal Processing, pp. 155-162, April 1981.
[3] Fredric J. Harris, Multirate Signal Processing, Prentice Hall, 2004
LTE Digital Remote Radio Head
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Powerwave award-winning remote radio head family supports LTE with products optimized for use in the 700 MHz and 2.1 GHz bands – the two most dominant frequency bands in the US being targeted near term by major carriers – for 3GPP Long Term Evolution (LTE) network deployments.
Featuring a small, lightweight form factor weighing less than 13k g, Powerwave’s LTE digital remote radio heads can be physically mated to a base-band subassemblies to form tower-mounted macro base stations that support up to three LTE carriers, and can be tower- or rooftop- mounted. The digital remote radio head is highly configurable via firmware, providing ease of customization and time-to-market advantage, and is also power efficient, to provide operational cost savings over the life of the network.
Powerwave has deployed more than 80,000 digital radio heads around the globe –facilitating the rapid deployment of major 4G projects and supporting all manner of air interfaces and technologies. Powerwave’s technology and service is unsurpassed in the industry, and the company possesses all the expertise and owns several patented technologies employed in the design of the 4G Digital Remote Radio Head products.
Multi-Mode Radio Heads for LTE & LTE Advanced
Technology-agnostic platform
The Radiocomp RRH platform is a technology-agnostic remote radio head subsystem that can be adapted to comply with various bearer technologies. The fourth generation 3GPP LTE radio access standard specifies throughput performance in excess of 300 Mbps for every 20 MHz of spectrum (downlink) and very low latency, and the first commercial launches are expected in 2010.
SDR architecture
Radiocomp RRH technology - including the most advanced implementation of SDR design concepts on the market today - allows a highly cost efficient and high-performance implementation of the 3GPP LTE radio interface.
Full OBSAI & CPRI interfacing capabilities
Fully functional OBSAI and CPRI components for fast-track design & development of 3GPP LTE distributed base station subsystems are available today from MTI Radiocomp. The MTI Radiocomp solution for LTE radioheads will include version for both FD and TD variants of 3GPP LTE. For more information and prices contact our sales department at sales@.
News
Belgacom tests RFS Hybriflix cable system
Monday 19 September 2011 | 10:43 CET
Wireless and broadcast infrastructure specialist Radio Frequency Systems (RFS) said it has successfully trialed ist Hybriflex feeder cabling system into a Belgacom live network. Hybriflex
combines optical fibre and DC power for Remote Radio Heads (RRHs) in a single corrugated cable. During the trial held in April, May and June, Hybriflex was installed at a Belgacom cell site in Verviers, on the roof of a residential building, and in Spa where the site was located between the two steeples of a church. At both sites, three RRHs were being deployed for each of the sectors to improve GSM, DCS and UMTS capacity within the city areas. Belgacom said the systen satisfied its requirements.
Published on: 8th February 2008
Denmark based, Radiocomp says that it aims to deliver the world's first commercially available remote radio head (RRH) for 3GPP LTE to its OEM customers during the second half of this year. The new LTE RRH will follow the successful first deliveries of RRH units for 3.5 GHz mobile WiMAX first half this year.
"The Radiocomp LTE RRH development project has already been launched. We base our RRH LTE on our existing and highly flexible digital platform also used for WiMAX, with the mechanics and RF scaled up & redesigned to accommodate the greater power output required by LTE," says Thomas Noergaard, CEO of Radiocomp.
Radiocomp believes that the mobile broadband future will be shaped by a global technology shift towards both WiMAX and 3gpp LTE. "The mass-market uptake of mobile broadband will be enabled by WiMAX and LTE, with LTE being the technology of choice for existing UMTS mobile operators. WiMAX may well be the most cost-efficient choice for new operators," says Mr Noergaard.
At the same time the mobile industry will need new ways of deploying wireless broadband systems for operators to be able to run a profitable business. "High-performance radio heads will be a critical part of the architecture of new LTE networks, and Radiocomp will be ready to deliver an industry-leading RRH product," says Noergaard.
Radiocomp predicts that the use of remote radioheads may save mobile operators as much as 40% in power consumption alone. Operators will also save on CAPEX and receive the benefit of vastly increased flexibility
AceAxis to Launch All New Atlas RRH Range at MWC
AceAxis Ltd, the world leading innovator in Remote Radio Head technology, will be launching a new generation of high quality, LTE RRH on 14th February at the MWC show in Barcelona.
The latest range of AceAxis products will be named Atlas RRH and will feature the world’s most cost efficient LTE 2x2 MIMO RRH. Also being launched will be the highly flexible multimode, multicarrier, multiband 4x4 MIMO RRH and the top of the range 8x8, the world’s first LTE multi-antenna beamforming enabled RRH.
Announcing the launch of the new Atlas RRH range, CEO Simon Mellor said “The AceAxis Atlas RRH range will redefine the Remote Radio Head market in terms of value, quality, reliability, efficiency and continuity of supply. Any OEM that is currently producing Remote Radio Heads in-house or outsourcing to another supplier should take the time to visit our stand at MWC to talk about a superior
product at a better price”
AceAxis will be exhibiting from stand 2F28 at MWC from 14th to 17th February
Full details of the AceAxis Atlas RRH range will be made available on 14th February.
ETSI Preps Spec for Remote Radio Heads
May 11, 2010 | Michelle Donegan | Post a comment
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Some of the world's largest mobile operators and vendors are working on a European Telecommunications Standards Institute (ETSI)specification for a base-station equipment interface that will ultimately help operators reduce cell site costs and energy consumption.
The requirements for the specification were created by the operator group, Next Generation Mobile Networks (NGMN) Ltd. , which then selected ETSI to write the spec.
The new ETSI group, under the name Open Radio Equipment Interface (ORI), will write a standard for an open interface that goes between a base station's baseband unit and remote radio head, which are the basic elements in a distributed base-station architecture.
Operators already deploy remote radio heads today because such a distributed setup is more energy efficient than traditional base stations. But the interface between the baseband unit and the remote radio head, which typically uses a fiber optic physical connection, has not been standardized, and the equipment has not been interoperable.
Operators want the opposite -- standardized, interoperable equipment, according to Ultan Mulligan, director of strategy and new initiatives at ETSI.
"This is a way of making sure the openness on interfaces is more industrialized," says Franck Emmerich, senior program manager at the NGMN group.
The spec is important because it will increase the flexibility and decrease the cost when operators need to deploy basebands or remote radio heads.
Part of the specification will rely on work already done by the Common Public Radio Interface (CPRI) group, which is a cooperation among six companies: Alcatel-Lucent(NYSE: ALU), Ericsson AB (Nasdaq: ERIC), Huawei Technologies Co. Ltd. , NEC Corp. (Tokyo: 6701), Nokia Siemens Networks , and Nortel Networks Ltd.
Another group of vendors, the Open Base Station Architecture Initiative (OBSAI), also defines interfaces between among base station elements. But its contribution to ETSI's ORI group is not clear.
It is understood that all three groups -- CPRI, OBSAI, and now ORI -- will coexist, but not compete with each other.
The first ORI specification is expected to be published in September and will cover both the UMTS and Long Term Evolution (LTE)standards. A second version with added features, including GSM support, is planned for release in the first quarter of 2011.
The participants in ETSI's ORI group are:
Alcatel-Lucent
AT&T Global Network Services
Deutsche Telekom AG (NYSE: DT)
Docomo Communications Laboratories Europe GmbH (Docomo Euro-Labs)
Ericsson
Freescale Semiconductor Inc.
Fujitsu Laboratories Ltd.
Huawei
Kathrein-Werke KG
Motorola Inc. (NYSE: MOT)
NGMN
Nokia Siemens
NTT Docomo Inc. (NYSE: DCM)
Radiocomp
ReVerb Networks
Rohde & Schwarz GmbH & Co. KG
Telecom Italia SpA (NYSE: TI)
Ubidyne GmbH
Vodafone Group plc (NYSE: VOD)
ZTE Corp. (Shenzhen: 000063; Hong Kong: 0763)
— Michelle Donegan, European Editor, Light Reading Mobile
기지국장비를RF 부분과베이스밴드부분으로분리하여RF 부분만기지국에설치하는차세대기지국장비. 통신제어부문인베이스밴드는센터에두고, RF 부분만분리하여원격으로조정한다. RF 부분을분리하여소형화함으로써별도의기지국설치가필요없이건물옥상이나전신주등에설치가가능해투자비및운영비를절감할수있다[출처] RRH 관련기술동향|작성자jackye RRH(Remote Radio Head)는통신제어부문인베이스밴드와전파를직접전달하는라디오유닛(RU)으로구성되는기지국설비에서RU의일부를원격으로분리해기존중계기역할을할수있도록한장치입니다. RRH를이용하면하나의베이스밴드에여러원격무선장비를둘수있어중계기의역할을기지국이대체할수있도록합니다. 따라서이동통신사들은기존기지국-중계기설비대신RRH를포함한기지국설비를늘려가며중계기시장이위협받고있다는평가를받고있기도합니다。