采用BICM-ID的PP-OFDM系统及后缀幅度优化

PP-OFDM with BICM-ID and Postfix Amplitude Optimization

该文设计了一种用于正交频分复用(OFDM)系统的新型保护间隔信号-导频后缀(Pilot Postfix,PP),并构建了采用比特交织编码调制-迭代解码(BICM-ID)技术的PP-OFDM系统。PP由OFDM符号中的频域导频符号进行逆傅氏变换(IFFT)生成,在接收端可与OFDM符号中的导频相干合并,从而提高信道估计性能。该文给出了相应的信道估计、均衡和BICM-ID算法,并通过研究信道估值误差带来的接收信号有效信噪比变化,给出了PP幅度优化设计方法。仿真表明:选取适当的PP大小后,PP-OFDM比循环前缀/补零后缀-OFDM(CP/ZP-OFDM)的信道估计性能更好,误包率更低。

A new postfixing scheme for OFDM is proposed, where PP （Pilot Postfix） is inserted in the guard interval after OFDM symbol, and PP-OFDM system is constructed with BICM-ID（Bit-Interleaved Coded Modulation with Iterative Decoding）. PP is generated by IFFT to frequency domain pilot symbols in OFDM symbol, and can be combined with those pilots in OFDM symbol at receiver. Channel estimation, equalization and BICM-ID algorithm for PP-OFDM are also proposed. Effective SNR degradation caused by imperfect channel estimation is studied, and a method is proposed to optimize the amplitude of PP. With the optimal PP amplitude, simulations show that PP-OFDM has better channel estimation performance and lower PER （Packet Error Rate） than CP/ZP-OFDM （Cyclic Prefix/Zero Postfix -OFDM）.