Adaptive modulation for coded cooperative systems

Throughput plays a key role in data communications over a wireless link. In this paper, we use adaptive modulation for a cooperative relaying system with the goal of maximizing the data throughput. We compare the throughput performance of three different schemes with adaptive modulation: direct transmission, multihop and coded cooperation. We find that cooperation with adaptive modulation provides large throughput improvement over multihop and direct transmissions. We also observe that to maximize the data throughput in direct transmission and multihop, the modulation mode for each hop only depends on the channel quality from the transmitter to the receiver. However, in coded cooperation a system wide optimization is necessary.