User Scheduling and Grouping in Massive MIMO Broadcast Channels with Heterogeneous Users

다국어 초록 (Multilingual Abstract)

This paper considers a frequency division duplexing massivemulti-input multi-output system with two-stage beamforming.
In two-stage beamforming, user scheduling and grouping are appliedto reduce inter-user and inter-group interferences, respectively.
Conventional scheduling utilizes the channel norm as a userselection metric. However, the metric degrades the multiuser diversitygain due to inter-group interference. To increase multiuserdiversity gain from scheduling, an approximate lower bound onexpected signal-to-interference-plus-noise ratio (SINR) value is derivedin this paper. Its asymptotic sum rate is also derived in a realisticchannel model where each user is randomly located in thecell. Analysis results show that the sum-rate growth increases withthe pathloss exponent, but is upper-bounded due to inter-groupinterference. In addition, user grouping for randomly-distributedusers is proposed. The approximate lower bound in user selectionis used to obtain a new grouping metric by averaging over an instantaneouschannel. In simulations, the proposed metric providedhigher sum rate than did conventional user grouping methods.

참고문헌 (Reference)

1 Q. H. Spencer, "Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels" 52 (52): 461-471, 2004

2 Y. Xu, "User grouping for massive MIMO in FDD systems : New design methods and analysis" 2 (2): 947-959, 2014

3 J. Chen, "Two-tier precoding for FDD multi-cell massive MIMO time-varying interference networks" 32 (32): 1230-1238, 2014

4 M. Dai, "Transmit beamforming for MISO broadcast channels with statistical and delayed CSIT" 63 (63): 1202-1215, 2015

5 F. Rusek, "Scaling up MIMO : Opportunities and challenges with very large arrays" 30 (30): 40-60, 2013

6 D. Gesbert, "Rate scaling laws in multicell networks under distributed power control and user scheduling" 57 (57): 234-244, 2011

7 M. Min, "On the performance analysis of MISO broadcast channels with spatial heterogeneity" 17 (17): 665-668, 2013

8 T. Yoo, "On the optimality of multiantenna broadcast scheduling using zero-forcing beamforming" 24 (24): 528-541, 2006

9 G. Caire, "On the achievable throughput of a multiantenna Gaussian broadcast channel" 49 (49): 1691-1706, 2003

10 T. L. Marzetta, "Noncooperative cellular wireless with unlimited numbers of base station antennas" 9 (9): 3590-3600, 2010

11 T. Yoo, "Multi-antenna downlink channels with limited feedback and user selection" 25 (25): 1478-1491, 2007

12 E. G. Larsson, "Massive MIMO for next generation wireless systems" 52 (52): 186-195, 2014

13 I. Sohn, "MIMO broadcast channels with spatial heterogeneity" 9 (9): 2449-2454, 2010

14 Y. S. Jeon, "Large system analysis of two-stage beamforming with limited feedback in FDDmassive MIMO systems" 67 (67): 605-609, 2018

15 A. Adhikary, "Joint spatial division and multiplexing–the large-scale array regime" 59 (59): 6441-6463, 2013

16 J. Nam, "Joint spatial division and multiplexing–opportunistic beamforming, user grouping and simplified downlink scheduling" 8 (8): 876-890, 2014

17 김현명, "Frequency Domain Channel Estimation for MIMO SC-FDMA Systems with CDM Pilots" 한국통신학회 16 (16): 447-457, 2014

18 H. Q. Ngo, "Energy and spectral efficiency of very large multiuer MIMO systems" 61 (61): 1436-1449, 2013

19 Y. S. Jeon, "Beamforming design and user grouping for FDD massive MIMO systems" 439-443, 2017

20 G. Lee, "Asymptotically optimal simple user scheduling for massive MIMO downlink with two-stage beamforming" 1-5, 2014