Research And Design On Multiple-mode OFDM With Index Modulation

With the rapid development of the information industry,the amount of data for communications is growing and people are demanding communication of higher performance and faster speed.Index modulation(IM)technique attracts great attention from scholars due to its high spectral efficiency and high energy efficiency.In addition,a new technique for implementing index modulation using orthogonal frequency division multiplexing(OFDM)subcarriers has been proposed in recent years.This technique is called OFDM with index modulation(OFDM-IM).Instead of activating all subcarriers,OFDM-IM technology selectively activates a portion of subcarriers to transmit modulation symbols.Multiple-mode OFDM with index modulation(MM-OFDM-IM)is a new OFDM-IM system.On this system,all subcarriers are active,and each subcarrier transmits modulation symbols of different modes.In this paper,we first introduce OFDM-IM system in detail.Then,a low-complexity Maximum Likelihood(ML)algorithm is presented and the grouping interleaved technique is applied to the system.Compared to classical OFDM system,OFDM-IM system can bring performance improvement.In order to further improve spectrum efficiency of MM-OFDM-IM system,a multiplemode OFDM with hybrid in-phase quadrature index modulation(MM-OFDM-HIQ-IM)system is proposed.The receiver algorithms,theoretical analysis of MM-OFDM-IM and MM-OFDMHIQ-IM systems are also studied in detail.Finally,in order to provide a more flexible spectrum efficiency than MM-OFDM-IM,we propose a generalized multiple-mode OFDM with index modulation(GMM-OFDM-IM)system.Then,the design guidelines of signal constellation mode and low-complexity detector of GMM-OFDM-IM system are studied in detail.Compared to MM-OFDM-IM system,GMMOFDM-IM system allows subcarriers to use signal constellations of different order to modulate transmitted symbols.We use Monte Carlo simulations to evaluate the performance of MM-OFDM-HIQ-IM and GMM-OFDM-IM systems.The simulation results show that the performance gain of MMOFDM-HIQ-IM system can be obtained at medium-to-high signal-to-noise ratio(SNR).Moreover,the error performance of GMM-OFDM-IM system is better than that of OFDM-IM system,and the detection performance of the low-complexity receiver is close to the ML detection algorithm.