用于大规模稀疏接入的增强型ODMA：在块衰落信道上的混合数据冻结比特传输和定点分析
Enhanced ODMA for Massive Sparse Access: Hybrid Data-Frozen Bit Transmission and Fixed-Point Analysis over Block Fading Channels
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中文总结 AI 辅助
研究针对大规模稀疏接入提出增强型ODMA传输方案，通过插入少量冻结符号实现联合多用户信道估计与迭代解码，性能等同于用户信道已知情况。还提出定点分析方法，可准确估计多用户块衰落信道迭代收敛性能，为多用户码设计提供有效工具。
中文摘要 AI 辅助
本文提出一种新颖的开关键控多址接入（ODMA）传输方案，通过在码字中插入少量冻结符号实现高效联合多用户信道估计和迭代解码。这些符号类似于导频，稀疏分布在码字中。与传统基于导频的方法不同，该方法只需极少冻结符号（如300用户系统中每个用户5至20个符号），兼具估计参考和解码辅助双重作用。通过采用低复杂度单用户信道估计与解码，结合简单迭代干扰消除，该方案即便考虑冻结符号的额外能量和带宽成本，性能也等同于用户信道完全已知的情况。此外，针对大规模ODMA稀疏多址接入系统，本文提出一种定点分析方法，仅利用单用户加性高斯白噪声（AWGN）信道下的解码函数，就能准确估计多用户块衰落信道上的迭代收敛性能。此方法适用于任意码长、码率和解码算法的性能分析，无需大量蒙特卡罗模拟时间，为多用户码设计提供了有效工具。
英文摘要
This paper proposes a novel on-off division multiple access (ODMA) transmission scheme that enables efficient joint multi-user channel estimation and iterative decoding by inserting a small number of frozen symbols into the codewords. Functionally analogous to pilots, these symbols are sparsely distributed within the codeword. Unlike conventional pilot-based methods, our approach requires only a minimal number of frozen symbols (e.g., $5\sim20$ symbols per user in a 300-user system), which serve dual purposes as both estimation references and decoding aids. By employing low-complexity single-user channel estimation and decoding, combined with simple iterative interference cancellation, the scheme achieves performance equivalent to that with perfectly known user channels, even when accounting for the additional energy and bandwidth costs of the frozen symbols. Furthermore, for the large-scale ODMA sparse multiple access system, this paper proposes a fixed-point analysis method, which can accurately estimate the iterative convergence performance over multi-user block fading channels by only leveraging the decoding functions under the single-user AWGN channel. This method is applicable to performance analysis for arbitrary code lengths, code rates, and decoding algorithms. It eliminates the need for extensive Monte Carlo simulation time, and provides an efficient tool for the design of multi-user codes.
