Relay Method of Sending Soft Decision Symbol Based on the Result of Error Detecting Code in Cooperative Communication


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.11   pp.2404-2412
Publication Date: 2007/11/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Wideband Systems)
Category: OFDM/Relay
cooperative communication,  transmit diversity,  soft decision symbol,  CRC,  

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Transmit diversity gain can be obtained in cooperative communication by cooperating the multiple users with single antenna. In cooperative communication, in the first step, each mobile station (MS) transmits its own data to both the base station (BS) and the other MS. In the second step, each MS's data is transmitted from the other MS to BS. As a result, transmit diversity gain can be obtained without implementing multiple transmit antennas at MS. In the conventional relay method, if error is detected within the received packet by using cyclic redundancy check (CRC) code, MS transmits its own data to BS instead of relaying the other MS's data in the second step. As a result, transmit diversity gain cannot be obtained. In this paper, we propose a novel cooperative method. In the proposed method, if the CRC decoder detects error within the received packet, MS transmits soft decision symbol which is obtained from the decoded data in second step. As a result, the transmit diversity gain always can be obtained. From the computer simulation, we show that the proposed method can achieve the better error rate performance than the conventional one.