Coded Orthogonal frequency division multiplexing with index modulation (OFDM-IM) has been proposed, where channel coding and soft decision are employed to exploit the multipath diversity for the information conveyed by the constellation symbols. However, the performance of coded OFDM-IM is dependent on the detection performance of subcarrier activation pattern (SAP) and the diversity order of the SAPs requires further investigation. In this paper, a lower-bound of LLR detector is derived to show that the maximum achievable diversity order is the minimum Hamming distance between the SAPs for the LLR detector. Based on the analyses, iterative detection is proposed to improve the performance of coded OFDM-IM, where information-assisted LLR detector is proposed to improve the detection performance of SAP by using the soft information of the constellation symbols. Simulation results are provided to corroborate the diversity analyses and show the advantage of the coded OFDM-IM with iterative detection.

已经提出了具有索引调制的编码正交频分复用（OFDM-IM），其中采用信道编码和软判决来利用星座符号所传达的信息的多径分集。然而，编码的OFDM-IM的性能取决于子载波激活模式（SAP）的检测性能，并且SAP的分集顺序需要进一步研究。本文推导了LLR检测器的下界，以表明最大可实现的分集阶数是LLR检测器的SAP之间的最小汉明距离。在此基础上，提出了迭代检测以提高编码后的OFDM-IM的性能，提出了一种信息辅助LLR检测器，通过利用星座符号的软信息来提高SAP的检测性能。提供了仿真结果以证实分集分析，并显示了带有迭代检测的编码OFDM-IM的优势。