Hierarchically modulated coded cooperation for relay system

Coded cooperation (CC) is an excellent scheme for cooperative communication. However, the throughput of CC is not high enough. In this paper, we propose a novel cooperative scheme called hierarchically modulated coded cooperation (HMCC). This scheme takes the frame group as the input instead of a single frame in CC and adopts hierarchical modulation in source node according to the asymmetry between the links of source-relay and source-destination, expecting that some frames can be received by destination node directly and others are forwarded by relay node. In HMCC, a higher order modulation can be used by source node. Theoretical analysis and simulation show that HMCC achieves a better performance on throughput compared to other schemes. On the other hand, HMCC distributes burst errors to the frame group owing to the hierarchical modulation, which suggests that HMCC is able to struggle against the burst errors.