Multi-carrier modulation scheme based on prolate spheroidal wave functions with generalized index modulation

Abstract

Multi-carrier modulation (MCM) based on prolate spheroidal wave functions (PSWFs) with generalized index modulation (GIM) was proposed in this paper. The proposed method relaxes the restriction on the number of the activated PSWFs signals, effectively increases the number of modulation symbol combinations and improves the spectral efficiency (SE) of the system. It solves the problem that the SE of the MCM-PSWFs with signal grouping optimization (MCM-PSWFs-SGO) is limited by the fixed number of the activated signals. At transmitter, a novel power control scheme of modulation signal based on fixed power gain is proposed. By introducing fixed power gain, the complexity of GIM transmitter is effectively reduced, and the minimum Euclidean distance between modulation symbols is increased. At receiver, based on the fact that the activation states of different PSWFs signals are independent of each other, a novel signal index detection method based on local optimization is proposed, which converts the signal index detection to the activation state detection of single branch signals. Under the same bit error rate (BER) performance, the complexity of signal index detection is reduced from $O(mMgn)$ of classical GIM to $O(gn)$. Theoretical and simulation results show that the proposed method can achieve improvement of SE. For example, when BER is $10^{-5}$, compared with MCM-PSWFs-SGO, the SE of the proposed method increases by 14.5%, and the required signal to noise ratio decreases by 2.73 dB. Compared with classical GIM, the SE increases by 2.9% and the required signal to noise ratio decreases by 1.92 dB.