【作者】 唐岚；

【导师】 王树勋；

【作者基本信息】 吉林大学 ， 信号与信息处理， 2005， 硕士

【摘要】 本论文主要研究多入多出(MIMO)系统的空时编码、空分复用技术及多用户MIMO 系统的资源分配问题。在分析MIMO 系统的研究现状、工作原理,MIMO 信道容量及MIMO 空时处理基本技术的基础上,对MIMO-CDMA 系统中的分组空时处理技术,自适应MIMO 空时比特交织技术,及MIMO 自适应多用户分集技术进行了较为深入的研究。在采用分组空时码的MIMO-CDMA 系统中,发射天线被分成若干相互独立的天线组,每组天线进行独立的空时编码,同时对分组块码进行最优功率分配;在接收端用干扰分组抑制的方法对各子块进行线性阵列处理及最大似然解码。该系统能在不增加设备复杂度的基础上,有效提高系统的误码性能和传输速率。为增强MIMO 系统在多径信道中的抗衰落能力,本论文提出采用空时分层交织器的自适应空时比特交织技术,在系统吞吐量一定的情况下最小化系统的误码率,该系统在瑞利衰落信道中能获得比无交织系统更好的性能。在多用户MIMO 系统中,多用户分集技术将资源分配给信道矩阵与随机波束成形矩阵最匹配的用户以获得最大的系统吞吐量。为进一步提高系统性能,本文将自适应编码调制技术运用到MIMO 多用户分集系统中。在频率选择性衰落信道中,采用正交频分复用(OFDM)技术将信道分为不同的空频子信道,通过增加系统的频率分集增益进一步提高系统性能。更多还原

【Abstract】 With the development of economy, advancement of science and technologyand increasing demand for information transmission, higher transmission rate andbetter service quality are required in communication network. In order to realizethe full potential of ‘any where, any time personal communication’, space-timesignal processing is now regarded as a core element of future system deployment.In multiuser system, smart antenna system yields a capacity enhancement or rangeextension over conventional fixed beam antenna installations by focusing theirbeam patterns towards the desired user. Despite these benefits offered by singlearray, 3rd and 4rd generation wireless networks could still fall short of marketexpectations in terms of available capacity for ‘e-commerce’and ‘multi-media’based services. As a result, the smart antenna concept is extended by employingmulti-element arrays at both ends of the communication, which is called MIMOsystem. Important improvement in throughput without additional bandwidth andpower can be achieved when multiple antennas are applied at both the transmitterand receiver side, especially in a rich scattering environment. So, MIMOarchitecture has been applied in wireless cell network, wireless LAN and ADSL.MIMO techniques can basically be split into two groups: space time coding(STC) and space division multiplexing (SDM). STC increases the performance ofthe communication system by coding over the different transmitter branches,whereas SDM achieves a higher throughput by transmitting independent datastreams on the different transmitter branches simultaneously and at the samecarrier frequency. Currently, adaptive MIMO resource allocation techniques havebeen in an active research. In wireless channel, adaptive MIMO space timeprocessing technique which combines space-time processing and adaptive bits,power allocation can suppress multipath fading and improve system throughput.Now, wide researches about space-time techniques in single user MIMOsystem have been conducted. However, adaptive MIMO space-time processingtechnique and adaptive resource allocation technique in multiuser MIMO systemare in a primary stage. This paper consists of seven chapters. The first three chapters mainlyintroduce the existent research fruits, the fourth, fifth and sixth chapters areauthor’s main contribution and the last chapter is conclusion. The first chapter is introduction, which presents the research background,principle, realization and application of MIMO system. In the second chapter, we show an overview on the capacity of MIMO systemin fixed channel and fading channel. In fading channel, channel capacity has aclose relation with channel statistical characteristic and channel informationacquired by transmitter and receiver. In flat fading channel, channel capacitieswith channel state information at the receiver (CSIR) and at the transmitter (CSIT)and with CSIR and channel distribution at the transmitter (CDIT) are discussedrespectively. In frequency-selective fading channel, first, we converts thefrequency-selective channel into frequency flat spatial subchannels with differentcarrier, then introduce the capacity with CSIT, CDIT and CSIR. In the third chapter, receiver algorithms in MIMO flat andfrequency-selective fading channel are introduced, which include the zero forcing(ZF), MMSE, ML and successive interference cancellation algorithm. We present the group space-time processing and power allocation techniquesin MIMO-CDMA system in multipath fading channel in chapter four. This schemeimproves performance of system without increasing the complexity. In chapter five, we research adaptive resource allocation technique in MIMOspatial multiplexing system, which include BLAST, antenna selectin algorithmand adaptive bit interleaved coded modulation technique in fast fading channel. In chapter six, we research adaptive multiuser diversity technique in flatfading channel and frequency-selective fading channel. In flat fading channel,channel is decoupled into parallel sub-channels with random beamforming in thetransmitter and linear processing in the receiver. With each user’s effectivesub-channel SNRs, the transmitter then schedules the transmission to oneparticular selected with proportional fair scheduling algorithm. Finally, adaptivemodulation is applied to each sub-channel of the selected user based on the BERconstraint. In frequency-selective fading channel, sub-carrier random beamformerand QR linear receiver decouple the space-frequency channels into sub-channels.QR receiver can suppress the interference between sub-channels, which make thesystem performance approach that of eigen-beamforming system even the usernumber is small. Simulation results show that multiuser diversity with antennaallocation can achieve better performance than that of eigen-beamforming system.Finally, adaptive subchannel coded modulation is adopted to improve systemperformance further. The sixth chapter is conclusion, which generalizes the main work of thispaper and challenge faced in commercialization. The originality of this paper is as fellows: 1. Apply group space-time coding to CDMA system, which improve system performance without increasing complexity. 2. Propose adaptive bit interleaving coded modulation and correspongding decoding algorithm in fast fading channel, which improve the reliability of communication over multipath fading channel. 3. Propose variable rate multiuser diversity algorithm in flat fading and frequency-selective fading channel and realize resourse allocation in multiuser MIMO system. In flat fading channel, adaptive multiuser diversity can maximum system throughput; in frequency selective fading channel, adaptive multiuser diversity with OFDM can optimize system throughput and BER performance. This paper has some illumination means to the two questions as follows: 1. Best offset algorithm between maximizing diversity gain and maximizing system capacity.更多还原