Optimal Rate Selection Scheme in a Two-Hop Relay Network Adopting Chase Combining HARQ in Rayleigh Block-Fading Channels
In Rayleigh block fading channels which represent fast-varying channels, long-term rate adaptation is required instead of instantaneous rate adaptation because the channel information fed back may be outdated. The authors maximize the Long-term Average Transmission Rate (LATR) in a two-hop relay network which adopts Chase Combining (CC) type Hybrid Automatic-Repeat-reQuest (HARQ). The round transmission rate, i.e. the transmission rate of each HARQ round in each hop, is optimally selected based on the channel statistics of two hops. Two constraints are considered: the outage probability and the maximum number of HARQ rounds, L.