RELAY METHOD OF SENDING SOFT DECIDED SYMBOL IN COOPERATIVE COMMUNICATION

摘要

Cooperative communication is the two-step transmission method. In first step, each user's data is transmitted from the user to the base station and the other user, and in second step, each user's data is transmitted from the other user to the base station. As a result, transmit diversity gain can be obtained. However, in the conventional system, second step is suspended if the user detects the erroneous bits from the received packet with the cyclic redundancy check (CRC) in first step. Instead, in second step, the user transmits the own data to the base station again. As a result, transmit diversity gain cannot be obtained and each user must inform the CRC result to the base station. In this paper, we propose a novel cooperative method. In the proposed system, even if the CRC detects the erroneous bits from the received packet, in second step, the user transmits soft decided symbol which is obtained from the decoded data. Furthermore, since the user relays the partnership user's data constantly, transmit diversity gain is obtained and side information is not required at the base station. In computer simulation, the proposed system can achieve the better error rate performance than the conventional one.