基于统计信道状态信息的有限反馈空分多址方法

Journal of Southeast University( English Edition) VoL 28, No 1, pp 1-7Mar.2012ISSN1003-7985Limited feedback Sdma schemes based on statistical CSISun Qiang"- Zhang YJin Shi Gao xiqi(National Mobile Communications Research Laboratory, Southeast University, Nanjing 210096, China)School of Electronic and Information Engineering, Nantong University, Nantong 226019, ChinaAbstract: This paper investigates the multi-beam selection and the feedback overhead of the users are higher when aalgorithms for transmit correlation channels by using statistical larger codebook is used to reduce the interference, sincechannel state information( SCSI) and instantaneous channel the beamforming vector is generally determined by an erstate information. Unlike the conventional codebook-basehaustive search in the sets of codebooks at the user sidetransmission scheme, the proposed multi-beam selection with and it is sent back to the base station(BS) at each time-the single channel quality indicator( cQn) feedback(MBSslot. 2) The schedulers become inefficient, especiallySCF)algorithm determines the preferred beam vector by when the user pool is small, because it is unlikely to findexploiting the SCSI and only feeds back CQI at each timeslot. a few simultaneous users with semi-orthogonal channelsThe performance of the MBS-SCF algorithm is nearly then a small user poolsame as that of the conventional scheme. In order to further In this paper, we consider a limited feedback SDMAimprove the average sum rate, a novel multi-beam selectionwith the dual CQls feedback MBS-DCF)algorithm isscheme in a suburban scenario, where the channel fadingof different antennas(e. g. uniform linear array ) at thproposed, which determines dual preferred statistical eigen- BS is highly correlated due to little scattering and smalland simulation results demonstrate that the angular spread. The statistical channel state informationMBS-DCF algorithm can increase the multiuser diversity and (SCSI)represents the statistical properties of the channel.multiplexing gain and exhibits a higher average sum rate.generally including the distribution of channel fading, theKey words: spatial division multiple access; statistical channel average channel gain and the spatial correlation, etc. Itsstate information; multiuser multiple-input multiple-outputcoherence period is generally much longer than that of thedoi:10.3969/jiss.1003-7985.2012.01.001instantaneous channel realizations 4. Therefore it can beasily obtained by the receiver and feed back to the trans-Multiuser multiple-input multiple-output MU-MF. mitter, An altermative is to exploit the uplink/downlinkMO)downlink systems exploit multiplexing gains reciprocity of channel statistics. Compared with the in-and the multiuser diversity gains to significantly increase stantaneous CSI per timeslot, the overhead of the SCSIthe throughput of the systems". In practice,limitedcan befeedback spatial division multiple access SDMABased on these observations, we propose simple andefficient SDMA schemes with limited feedback by explA per-user unitary and rate control( PU2RC) scheme, correlation matrices)are acquired by either of the annelcomputational complexity and little amount of overhead. ting the SCSI. First, assuming that the SCSIs(channelwhich is a practical implementation of the limited feed. methods, the BS and each user can determine theback SDMA scheme with predefined sets of orthogonal co- ferred statistical cigen-direction beamforming vector)ebooks, has been proposed as a practical MU-MIMO so- during the period of updating the SCSI (or each user canlution in next-generation wireless communication stand. determine the preferred statistical eigen-direction and sendards.However, the major drawbacks of the pu2Rc back the index of the preferred statistical eigen-directiorscheme are as follows: 1)The computational complexity to the BS). During the scheduling period, each user onlyfeeds back the channel quality indicator( CQi)on its pre-Received 2011-11-21ferred statistical eigen-direction without the corespondingBiographies: Sun Qiang(1980-), male, lecturer, graduate; Gao Xiqi vector index at each timeslot. Secondly, in order to over-carresponding author), male, doctor, professor, xqgaoe seu. edu.cn.Foundation items: The National Natural Science Foundation of chinaome the obstacle due to a small user pool, cachlo, 608925004, 60002009, 6101 103). the National Science and Technology user can select dual preferred statistical eigen-direcMajor Project of China( No 2009ZX03003-005-02 2009ZX03003-011-04. according to the sCsI. At each timeslot, each user2011ZX0B0B-008-03), the Natural Science Foundation of Jiangsu Province back dual CQIs on its dual preferred statistical eigen-di-of China(No BK201 1019), the Natural Science Foundation of the Jiangsu rections, which will increase the multiplexing gains andHigher Education Institutions of China(No. 10KJBS10021)e multiuser diversity gainsCitation: Sun Qiang, Zhang Yuan, Jin Shi, et al. Limited feedback SDMA schemes based on statistical CSI[ J]. Joumal of Southeast University 1 System Model( English Edition),2012,28(1):1-7.Idoi:10.3969/j.isn.10037985.2012.01.0011We consider the downlink MIMO system with K users.Sun Qiang, Zhang Yuan, Jin Shi, and Gao xiqiThe Bs is exposed to little scattering and is equipped with of user i, the BS and user i determine user clustering anda uniform linear array (ULA)of M antennas, whereas the user's preferred statistical eigen-directions. The detailseach user is equipped with a single antenna, Since in a of clustering the user and determining the statistical eigentypical cellular system, the number of users is much grea- directions are described as followster than the number of transmit antennas(K>M).Ineach timeslot, the BS selects user sets Q(B=IQI