The maximum information rates for bandlimited channels with direct detection are achieved with joint detection and decoding (JDD), but JDD is often too complex to implement. Two receiver structures are studied to reduce complexity: separate detection and decoding (SDD) and successive interference cancellation (SIC). For bipolar modulation, frequency-domain raised-cosine pulse shaping, and fiber-optic channels with chromatic dispersion, SIC achieves rates close to those of JDD, thereby attaining significant energy gains over SDD and intensity modulation. Gibbs sampling further reduces the detector complexity and achieves rates close to those of the forward-backward algorithm at low to intermediate signal-to-noise ratio (SNR) but stalls at high SNR. Simulations with polar codes, higher-order modulation, and multi-level coding confirm the predicted gains.

翻译：采用联合检测与译码(JDD)可实现带限信道直接检测的最大信息速率，但JDD复杂度通常过高而难以实施。为降低复杂度，本文研究了两种接收机结构：分离检测与译码(SDD)以及串行干扰消除(SIC)。对于双极性调制、频域升余弦脉冲整形以及具有色散特性的光纤信道，SIC的速率接近JDD，从而相比SDD和强度调制获得显著的能量增益。吉布斯采样进一步降低了检测器复杂度，在中低信噪比(SNR)下可达到接近前向-后向算法的速率，但在高SNR时出现停滞。采用极化码、高阶调制和多级编码的仿真验证了所预测的增益。