A Throughput Evaluation of an Over-Distributed Antenna System with Limited Pilot Resources

Yuki NAKANISHI  Toshihiko NISHIMURA  Takeo OHGANE  Yasutaka OGAWA  Yusuke OHWATARI  Yoshihisa KISHIYAMA  

IEICE TRANSACTIONS on Communications   Vol.E98-B   No.8   pp.1465-1473
Publication Date: 2015/08/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E98.B.1465
Type of Manuscript: Special Section PAPER (Special Section on 5G Radio Access Networks―Part I: Radio Access Technologies and System Design)
distributed antenna system,  multiuser MIMO system,  throughput,  pilot resource,  

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A distributed antenna system, where the antennas of a base station are spatially distributed throughout the cell, can achieve better throughput at the cell edge than a centralized antenna system. On the other hand, the peak throughput degrades in general because each remote antenna unit has only a few antennas. To achieve both high peak and cell-edge throughputs, we need to increase the total number of antennas. However, this is not easy due to the pilot resource limitation when we use frequency division duplexing. In this paper, we propose using more antennas than pilot resources. The number mismatch between antennas and signals is solved by using a connection matrix. Here, we test two types of connection matrix: signal-distributing and signal-switching. Simulation results show that the sum throughput is improved by increasing the number of antenna elements per remote antenna unit under a constraint on the same number of pilot resources.