Block orthogonal sparse superposition (BOSS) code is a class of joint coded modulation methods, which can closely achieve the finite-blocklength capacity with a low-complexity decoder at a few coding rates under Gaussian channels. However, for fading channels, the code performance degrades considerably because coded symbols experience different channel fading effects. In this paper, we put forth novel joint demodulation and decoding methods for BOSS codes under fading channels. For a fast fading channel, we present a minimum mean square error approximate maximum a posteriori (MMSE-A-MAP) algorithm for the joint demodulation and decoding when channel state information is available at the receiver (CSIR). We also propose a joint demodulation and decoding method without using CSIR for a block fading channel scenario. We refer to this as the non-coherent sphere decoding (NSD) algorithm. Simulation results demonstrate that BOSS codes with MMSE-A-MAP decoding outperform CRC-aided polar codes, while NSD decoding achieves comparable performance to quasi-maximum likelihood decoding with significantly reduced complexity. Both decoding algorithms are suitable for parallelization, satisfying low-latency constraints. Additionally, real-time simulations on a software-defined radio testbed validate the feasibility of using BOSS codes for low-power transmission.

翻译：块正交稀疏叠加（BOSS）码是一类联合编码调制方法，可在高斯信道下以较低编码速率通过低复杂度译码器逼近有限分组长度容量。然而在衰落信道中，由于编码符号经历不同的信道衰落效应，该码的性能显著下降。本文针对衰落信道下的BOSS码提出了新型联合解调解码方法。针对快衰落信道场景，当接收端已知信道状态信息时，我们提出了一种最小均方误差近似最大后验（MMSE-A-MAP）联合解调解码算法。针对块衰落信道场景，我们进一步提出了一种无需信道状态信息的联合解调解码方法，称为非相干球形译码（NSD）算法。仿真结果表明：采用MMSE-A-MAP译码的BOSS码性能优于CRC辅助的极化码，而NSD译码在显著降低复杂度的同时实现了与准最大似然译码相当的性能。两种译码算法均支持并行化处理，满足低延迟约束。此外，基于软件无线电平台的实时仿真验证了BOSS码在低功耗传输中的可行性。