Abstract
A bidirectional multi-symbol phase estimation (BD-MSPE) scheme for differentially encoded optical signals, which can realize high-speed processing with superior BER characteristics, is proposed. Conventional MSPE needs decision feedback to correct phases of past symbols, so it is not suitable for parallelization. BD-MSPE, in contrast, uses tentative decision to avoid feedback. Due to the tentative decision, both past and future symbols can be utilized for phase estimation. Moreover, BD-MSPE can be organized in multistage when the decision result of the first stage of MSPE is used as the second tentative decision result for the next stage. Simulation results show the bit-error-rate (BER) curve of the proposed scheme asymptotically approaches that obtained by coherent detection.
