• Title, Summary, Keyword: Multiuser MIMO

Search Result 118, Processing Time 0.072 seconds

Precoding Method for Increasing System Capacity in Multiuser MIMO Downlink Channels (다중사용자 MIMO 하향링크 채널 환경에서 시스템 용량 향상을 위한 프리코딩 기법)

  • Kim, Kwang-Yoon;Lee, Jong-Sik;Koo, Sung-Wan;Yang, Jea-Su;Kim, Jin-Young
    • 한국정보통신설비학회:학술대회논문집
    • /
    • /
    • pp.12-16
    • /
    • 2008
  • In this paper, we study precoding techniques for co-channel interference suppression in multiuser MIMO systems. DPC is optimal techniques to achieve the system capacity of multiuser MIMO downlink channels. DPC is not proper in practical wireless systems because complexity is very high. So block diagonal precoding for multiuser MIMO downlink channel is studied. The block diagonal precoding is used to suppress co-channel interference between multiuser. Block diagonal precoding method, whose complexity is reduced by modified null space operation, change multiuser MIMO channel to multiple single-user MIMO channel. We also use V-BLAST decoder in receiver. V-BLAST decoder can achieve increased system capacity in proportion to the number of users. We show improved system performance by using computer simulation.

  • PDF

Simulation Models for Investigation of Multiuser Scheduling in MIMO Broadcast Channels

  • Lee, Seung-Hwan;Thompson, John S.
    • ETRI Journal
    • /
    • v.30 no.6
    • /
    • pp.765-773
    • /
    • 2008
  • Spatial correlation is a result of insufficient antenna spacing among multiple antenna elements, while temporal correlation is caused by Doppler spread. This paper compares the effect of spatial and temporal correlation in order to investigate the performance of multiuser scheduling algorithms in multiple-input multiple-output (MIMO) broadcast channels. This comparison includes the effect on the ergodic capacity, on fairness among users, and on the sum-rate capacity of a multiuser scheduling algorithm utilizing statistical channel state information in spatio-temporally correlated MIMO broadcast channels. Numerical results demonstrate that temporal correlation is more meaningful than spatial correlation in view of the multiuser scheduling algorithm in MIMO broadcast channels. Indeed, the multiuser scheduling algorithm can reduce the effect of the Doppler spread if it exploits the information of temporal correlation appropriately. However, the effect of spatial correlation can be minimized if the antenna spacing is sufficient in rich scattering MIMO channels regardless of the multiuser scheduling algorithm used.

  • PDF

Spatial Multiuser Access for Reverse Link of Multiuser MIMO Systems

  • Shin, Oh-Soon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.10A
    • /
    • pp.980-986
    • /
    • 2008
  • Spatial multiuser access is investigated for the reverse link of multiuser multiple-input multiple-output (MIMO) systems. In particular, we consider two alternative a aches to spatial multiuser access that adopt the same detection algorithm at the base station: one is a closed-loop approach based on singular value decomposition (SVD) of the channel matrix, whereas the other is an open-loop approach based in space-time block coding (STBC). We develop multiuser detection algorithms for these two spatial multiuser access schemes based on the minimum mean square error (MMSE) criterion. Then, we compare the bit error rate (BER) performance of the two schemes and a single-user MIMO scheme. Interestingly, it is found that the STBC approach can provide much better BER performance than the SVD approach as well as than a single-user MIMO scheme.

Regularized Channel Inversion for Multiple-Antenna Users in Multiuser MIMO Downlink (다중 안테나 다중 사용자 하향 링크 환경에서 Regularized Channel Inversion 기법)

  • Lee, Heun-Chul;Lee, Kwang-Won;Lee, In-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.35 no.3A
    • /
    • pp.260-268
    • /
    • 2010
  • Channel inversion is one of the simplest techniques for multiuser downlink systems with single-antenna users. In this paper, we extend the regularized channel inversion technique developed for the single-antenna user case to multiuser multiple-input multiple-output (MIMO) channels with multiple-antenna users. We first employ the multiuser preprocessing to project the multiuser signals near the null space of the unintended users based on the MMSE criterion, and then the single-user preprocessing is applied to the decomposed MIMO interference channels. In order to reduce the complexity, we focus on non-iterative solutions for the multiuser transmit beamforming and use a linear receiver based on an MMSE criterion. Simulation results show that the proposed scheme outperforms existing joint iterative algorithms in most multiuser configurations.

Adaptive Opimization of MIMO Codebook to Channel Conditions for Split Linear Array (분할된 선형배열안테나를 위한 채널 환경에 적응하는 MIMO 코드북 최적화)

  • Mun, Cheol;Jung, Chang-Kyoo;Kwak, Yun-Sik
    • The Journal of Advanced Navigation Technology
    • /
    • v.13 no.5
    • /
    • pp.736-741
    • /
    • 2009
  • In this paper, adaptive optimizations of precoder codebook to channel conditions is proposed for a multiuser multiple-input multiple-output (MIMO) system with split linear array and limited feedback. We propose adaptive method for constructing a precoder codebook by coloring the random vector quantization codebook at each link by using limited long-term feedback information on transmit correlation matrix of each link. It is shown that the proposed multiuser MIMO codebook design scheme outperforms existing multiuser MIMO codebook design schemes for various channel conditions in terms of the average sum throughput of multiuser MIMO systems using zero-forcing maximum eigenmode transmission and limited feedback.

  • PDF

Closed-form Expressions for Capacity Bounds of MRT/MRC MIMO with Multiuser Diversity (다중사용자 다이버시티가 적용된 MRT/MRC MIMO의 Capacity Bound의 Closed-form 표현)

  • Lee, Myougn-Won;Mun, Cheol;Yook, Jong-Gwan
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.31 no.12A
    • /
    • pp.1223-1228
    • /
    • 2006
  • Closed-form expressions for capacity bounds of multiuser diversity combined with maximum ratio transmission (MRT) and maximum ratio combining (MRC) at each link are presented under the assumption of independent and quasi-static flat multiple-input multiple-output (MIMO) Rayleigh fading channels. The analysis results precisely agree with the numerical verification results and clearly show the impact of MRT/MRC on multiuser diversity.

Multiuser Heterogeneous-SNR MIMO Systems

  • Jo, Han-Shin
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.8 no.8
    • /
    • pp.2607-2625
    • /
    • 2014
  • Previous studies on multiuser multiple-input multiple-output (MIMO) mostly assume a homogeneous signal-to-noise ratio (SNR), where each user has the same average SNR. However, real networks are more likely to feature heterogeneous SNRs (a random-valued average SNR). Motivated by this fact, we analyze a multiuser MIMO downlink with a zero-forcing (ZF) receiver in a heterogeneous SNR environment. A transmitter with Mantennas constructs M orthonormal beams and performs the SNR-based proportional fairness (S-PF) scheduling where data are transmitted to users each with the highest ratio of the SNR to the average SNR per beam. We develop a new analytical expression for the sum throughput of the multiuser MIMO system. Furthermore, simply modifying the expression provides the sum throughput for important special cases such as homogeneous SNR, max-rate scheduling, or high SNR. From the analysis, we obtain new insights (lemmas): i) S-PF scheduling maximizes the sum throughput in the homogeneous SNR and ii) under high SNR and a large number of users, S-PF scheduling yields the same multiuser diversity for both heterogeneous SNRs and homogeneous SNRs. Numerical simulation shows the interesting result that the sum throughput is not always proportional to M for a small number of users.

Joint Lattice-Reduction-Aided Precoder Design for Multiuser MIMO Relay System

  • Jiang, Hua;Cheng, Hao;Shen, Lizhen;Liu, Guoqing
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.10 no.7
    • /
    • pp.3010-3025
    • /
    • 2016
  • Lattice reduction (LR) has been used widely in conventional multiple-input multiple-output (MIMO) systems to enhance the performance. However, LR is hard to be applied to the relay systems which are important but more complicated in the wireless communication theory. This paper introduces a new viewpoint for utilizing LR in multiuser MIMO relay systems. The vector precoding (VP) is designed along with zero force (ZF) criterion and minimum mean square error (MMSE) criterion and enhanced by LR algorithm. This implementable precoder design combines nonlinear processing at the base station (BS) and linear processing at the relay. This precoder is capable of avoiding multiuser interference (MUI) at the mobile stations (MSs) and achieving excellent performance. Moreover, it is shown that the amount of feedback information is much less than that of the singular value decomposition (SVD) design. Simulation results show that the proposed scheme using the complex version of the Lenstra--Lenstra--Lovász (LLL) algorithm significantly improves system performance.

Triangulation Algorithm for Multi-user Spatial Multiplexing in MIMO Downlink Channels (MIMO 다운링크 채널에서 다중사용자 공간다중화를 위한 알고리즘)

  • Lee, Heun-Chul;Paulraj, Aroyaswami;Lee, In-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.35 no.1C
    • /
    • pp.45-54
    • /
    • 2010
  • This paper studies the design of a multiuser multiple-input multiple-output (MIMO) system, where a base station (BS) transmits independent messages to multiple users. The remarkable "dirty paper coding (DPC)" result was first presented by Costa that the capacity does not change if the Gaussian interference is known at the transmitter noncausally. While several implementable DPC schemes have been proposed recently for single-user dirty-paper channels, DPC is still difficult to implement directly in practical multiuser MIMO channels. In this paper, we propose a network channel matrix triangulation (NMT) algorithm for utilizing interference known at the transmitter. The NMT algorithm decomposes a multiuser MIMO channel into a set of parallel, single-input single-output dirty-paper subchannels and then successively employs the DPC to each subchannel. This approach allows us to extend practical single-user DPC techniques to multiuser MIMO downlink cases. We present the sum rate analysis for the proposed scheme. Simulation results show that the proposed schemes approach the sum rate capacity of the multiuser MIMO downlink at moderate signal-to-noise ratio (SNR) values.

Fairness-aware Scheduling Scheme for MIMO OFDM Multiuser Diversity System. (MIMO OFDM 다중사용자 시스템 사용자간 공평성을 고려한 스케쥴링 기법)

  • An Sehyun;Yoo Myungsik;Lee Woncheol;Shin Yoan
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.30 no.6A
    • /
    • pp.474-480
    • /
    • 2005
  • In this paper, we present a new scheduling scheme for MIMO OFDM Multiuser Diversity System. This scheduling scheme maximizes the system throughput, and at the same time fairly shares the resources based on the feedback information from the receivers and the queue information. To show the effectiveness of the proposed algorithm, we evaluate the performance of the proposed algorithm as compared to K&H and RR algorithms.