Multiple-mode orthogonal frequency division multiplexing with index modulation (MM-OFDM-IM) is a promising multiple-carrier modulation technique, which activates all OFDM subcarriers to transmit multiple distinguishable modes (or signal constellations, alternatively) and carries additional information with the full permutation of the modes, enjoying superior error performance and high spectral efficiency. In this paper, we propose a novel detector tailored to MM-OFDM-IM based on the expectation maximization (EM) algorithm to further improve the detection performance. The idea is to first select the signal constellation points candidates for any given mode permutation by applying the EM algorithm and then determine the most-likely mode permutation as well as the associated signal constellation points by minimizing the Euclidean distance. The effectiveness of the EM detector has been verified in terms of bit error rate (BER) performance by Monte Carlo simulations.

带有索引调制的多模式正交频分复用（MM-OFDM-IM）是一种很有前途的多载波调制技术，该技术可以激活所有OFDM子载波以传输多个可区分的模式（或者信号星座图），并携带完整的附加信息。模式的排列，具有出色的误差性能和高频谱效率。在本文中，我们基于期望最大化（EM）算法提出了一种针对MM-OFDM-IM的新型检测器，以进一步提高检测性能。这个想法是首先通过应用EM算法为任何给定的模式排列选择信号星座点候选，然后通过最小化欧几里得距离来确定最可能的模式排列以及相关的信号星座点。