Cooperative chip-level HARQ-Chase combining for the 3GPP enhanced uplink system

In this paper, we evaluate by computer simulation the performance of the WCDMA enhanced uplink system with cooperative chip-level hybrid ARQ (HARQ) Chase combining technique over a multi-path Raleigh channels. The fixed relaying protocol used is the amplify-and-forward (AF). At each HARQ retransmission, one relay amplifies and forwards it received signal to the destination. At the node B, relay transmissions are seen as additional receive antennas which are jointly combined at chip-level using a space-time linear minimum square error (LMMSE). The simulation results demonstrate that the performance of the cooperative chip-level Chase combining is better than the non-cooperative chip-level Chase combining when the equivalent signal to noise ratio (SNR) of the inter-users channel and the cooperative channel is superior to the SNR of the direct channel.