Research On Broadband MIMO OFDM With Index Modulation In Wireless Transmission Technology

Orthogonal Frequency Division Multiplexing with Index Modulation(OFDM-IM), as a novel multi-carrier scheme, has the advantage of high spectrum efficiency and strong anti multipath effect. Compared with conventional OFDM, the non-continuous structure of OFDM-IM has the potentials to combat inter-carrier interference(ICI) and construct energy efficient transmit signals, so OFDM-IM has become one of the hotspot in the research of wireless communication in recent years.In order to further improve the spectrum efficiency and system capacity, this paper considers the combination of OFDM-IM scheme and Multiple Input Multiple Output(MIMO) technology, and studies the performance of MIMO-OFDM-IM system. In this paper, the optimization and design of MIMO-OFDM-IM receiver are studied, and several detection algorithms are proposed based on the optimal performance or low complexity. In addition, we deal with the main drawbacks of high peak-to-average ratio and out-of-band power of MIMO-OFDM-IM signals and a sub-optimal receivers are proposed.The specific structure of this paper is as follows:In chapter 1, the research status of OFDM-IM and MIMO technology is firstly introduced. Then, the advantages and disadvantages of MIMO-OFDM-IM are summarized compared with the traditional MIMO-OFDM.In chapter 2, we study the reciever of MIMO-OFDM-IM signals from the perspective of optimal performance, and three detection algorithms are proposed, called Distance-Based ordered Detection(DBD), modified DBD detection and Sorting-Based Detection, whose Bit Error Ratio(BER) performances are simulated. Specifically, we firstly summarize the existing detectors, named Maximum Likelihood(ML) and Log-Likelihood Ratio(LLR), and analyse their performances. Then three detctors are presented to cover the shortages of striking complexity of ML and poor BER performance of LLR detector. Compared with the LLR algorithm, DBD detection, based on MMSE equalization, has better BER performance. The modified DBD detector introduces a threshold, which greatly reduce the complexity. The Sorting-Based Detection sorts the active carrier combinations, so that it can achieve near ML detection performance with greatly reduced complexity of the algorithm.In chapter 3, three low-complexity recievers of MIMO-OFDM-IM signals are proposed, respectively called Energy Detection based on MMSE equalization, Local Search algorithm and Reactive Tabu Search algorithm, and their BER performances and complexity are analyzed. Energy Detection has the lowest complexity, but its detection performance is poor. Local Search algorithm firstly obtain the initial solution by Energy Detection, and then iterate traversing the neighborhood space of the initial solution until the termination condition are met. The Reactive Tabu Search algorithm can avoid the dead circulation of the local optimal solution by modifying the neighborhood space of each search, which improves the search efficiency. In addition, the termination conditions are reasonably set, which can achieve a balance between the performance and complexity of the algorithm.In chapter 4, the classic techniques are utilized to reduce peak-to-average ratio(PAPR) and out-of-band power of MIMO-OFDM-IM signals, and sub-optimal receivers are proposed.In chapter 5, we conclude this paper, and point out the possible research directions in the future.