A new adaptive strategy for turbo decoder with prior statistical knowledge of extrinsic information over AWGN and fading channels

Abstract

A new adaptive strategy for a turbo decoder with prior statistical knowledge of extrinsic information is proposed. A test pseudorandom bits block, with distribution patterns of 1s and 0s known by both the transmitter and receiver, is sent to the receiver when the channel status changes and is detected by the receiver. The turbo decoder computes the conditional probability mass functions of the extrinsic information for both arms at each iterative decoding by using the test block. These updated probability mass functions are kept in the turbo decoder to replace the conventional Gaussian assumptions for iterative decoding of an information bits block over AWGN and various fading channels. The simulation results show that the novel iterative turbo decoding has considerable performance gains over conventional ones under the same channel conditions.