16DAPSK软解调的优化及硬件实现

In this paper, two improved schemes for 16DAPSK differential amplitude soft demodulation called multiplicative soft demodulation and additive soft demodulation are proposed based on the LDPC+16DAPSK coded modulation simulation system. The results show that in AWGN channel using IEEE 802.16e LDPC with 1/2 code rate and 1536 code length, nearly 3dB perfomance gain can be achieved using the two improved differential amplitude soft demodulation methods compared with the usual soft demodulation. In terms of hardware implementation, the additive soft demodulation has a lower complexity but a slightly worse in performance than the multiplicative soft demodulation. Otherwise, this paper analysis and compare several common methods in amplitude normalization and differential phase soft demodulation in 16DAPSK demodulation, and selects "rectangle ring" normalization and simiplified equations as soft demodulation schemes.