Integrated iterative equalization for ARQ systems

In this paper, a new approach is presented to enhance receiver performance for ARQ communication systems that use systematic codes in rapidly-changing environments. This new approach involves a simple modification to the traditional turbo-equalizer by integrating multiple ARQ transmissions for joint equalization of systematic codewords. This modification provides a computationally efficient joint receiver that improves frame error rates and throughput when compared with a few other simple approaches. To analyze the receiver, simulation results are presented for two types of systematic codes: recursive systematic codes (RSC) and low-density parity check codes (LDPC). Results are also presented for a hybrid ARQ system where subsequent transmissions contain only portions of the original transmission.