Impact on Inter-Cell Interference of Reference Signal for Interference Rejection Combining Receiver in LTE-Advanced Downlink

Yousuke SANO  Yusuke OHWATARI  Nobuhiko MIKI  Yuta SAGAE  Yukihiko OKUMURA  Yasutaka OGAWA  Takeo OHGANE  Toshihiko NISHIMURA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E95-B   No.12   pp.3728-3738
Publication Date: 2012/12/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.3728
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Coding and Coding Theory-Based Signal Processing for Wireless Communications)
Category: 
Keyword: 
LTE-Advanced,  interference rejection combining,  inter-cell interference,  reference signal,  turbo equalizer,  

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Summary: 
This paper investigates the dominant impact on the interference rejection combining (IRC) receiver due to the downlink reference signal (RS) based covariance matrix estimation scheme. When the transmission modes using the cell-specific RS (CRS) in LTE/LTE-Advanced are assumed, the property of the non-precoded CRS is different from that of the data signals. This difference poses two problems to the IRC receiver. First, it results in different levels of accuracy for the RS based covariance matrix estimation. Second, assuming the case where the CRS from the interfering cell collides with the desired data signals of the serving cell, the IRC receiver cannot perfectly suppress this CRS interference. The results of simulations assuming two transmitter and receiver antenna branches show that the impact of the CRS-to-CRS collision among cells is greater than that for the CRS interference on the desired data signals especially in closed-loop multiple-input multiple-output (MIMO) systems, from the viewpoint of the output signal-to-interference-plus-noise power ratio (SINR). However, the IRC receiver improves the user throughput by more than 20% compared to the conventional maximal ratio combining (MRC) receiver under the simulation assumptions made in this paper even when the CRS-to-CRS collision is assumed. Furthermore, the results verify the observations made in regard to the impact of inter-cell interference of the CRS for various average received signal-to-noise power ratio (SNR) and signal-to-interference power ratio (SIR) environments.