An H-ARQ Transmission Scheme Based on Rateless Code

In the traditional cross-layer redundancy optimization allocation, the system can´t fully adapt the time-varying channel, so an H-ARQ transmission mechanism based on rate less code is proposed in this paper. The source uses LT-code as error-erasure code to encode the original packets in the packet-level, every bit of one coded packets is encoded by using LT-code as error-correction code in physical layer. The Receiver can set an upper limit value of the received bits to control decoding overhead, it sends a feedback to the source when the receiver decodes all the bits of a coded packet successfully, and otherwise it will discard the coded packet and send a feedback. Simulation results show that our mechanism improves the transmission efficiency greatly comparing to the mechanism with constant rate for coding transmission.