Feedback based cooperative transmission for multiuser multichannel systems

In this paper, we propose a feedback based cooperative transmission (FBCT) scheme for multiuser multichannel communication systems. We focus on uplink channels and consider a user, say user 1, who has a weak uplink channel. Another user (who is possibly located somewhere between the base station and user 1), say user 2, can be a relay for cooperative transmission. Using the feedback information of a positive acknowledgment (ACK) or negative acknowledgment (NACK) signaling from the base station, the signal from user 1 can be re-relayed by the relay (i.e., user 2) or re-transmitted by the source (i.e., user 1) in the proposed FBCT scheme. The resulting FBCT scheme can be seen as a hybrid of cooperative transmission and automatic repeat request (ARQ) protocol. We show that a mixed strategy of re-relay and re-transmission of the proposed FBCT scheme can perform better than a pure strategy of re-relay or re-transmission.