A new SIC-HARQ receiver for the WCDMA enhanced uplink system

In this paper, we propose a new interference canceller (SIC-HARQ) for the WCDMA enhanced uplink system which is the combination of the hybrid ARQ technique (HARQ) with an improved successive interference canceller (SIC). The proposed SIC detector is an iterative receiver which consists of a multiple stages. It is capable of eliminating multiple user interferences (MUI) by generating and subtracting the user's contribution from the received signal. At the last stage, when there are users which have transmission errors, the erroneous packets are saved at the receiver buffer and negative acknowledgements (NACK) are sent to the transmitters which in response retransmit the packets. The retransmitted packets are maximum ratio combined (MRC) with the previously saved ones. In this manner, the obtained packet after combining is more reliable than the individually transmitted packet. This increases the probability of correct decoding and increases the performance of the improved SIC detector. We have shown that the proposed SIC-HARQ receiver improves the block error rate (BLER) results of the data physical channels. This enhancement achieves, for the modulation and coding scheme 1 (MCS1), almost 5dB at the BLER equal to 10^-2.