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Orthogonal frequency division multiplexing (OFDM) is a high efficient multi-carrier modulation technique for broadband communication applications with high peak to average power ratio (PAPR). In order to reduce the adverse effects of high PAPR on communication, a novel time shifted non-orthogonal frequency division multiplexing (TS-NFDM) technology is created by introducing the time-shift factor into multi-carrier modulation in this paper, which brings distinct advantages on bandwidth efficiency and PAPR. According to the analysis of constellation diagram and experiment results, the bandwidth efficiency of TS-NFDM is 4.29 times as higher as OFDM approximately. PAPR of TS-NFDM also could be reduced better than OFDM.

The linear frequency modulated (LFM) signal has been widely implemented in broadband wireless communications in high-speed vehicles, such as internet of vehicles(IoV), because of its excellent characteristic of long time interval and wide frequency band. In this paper, a novel method, which employs the fractional Fourier transform and the Tuneable-Sigmoid transform, is proposed to estimate parameters of multicomponent LFM signals in Internet of Vehicles(IoV) under the impulsive noise environment. For the optimization in the fractional Fourier domain, an algorithm based on peak searching is proposed. And for multicomponent signals, we further propose a signal separation technique in the fractional Fourier domain which can effectively suppress the interferences on the detection of the weak components brought by the stronger components, and estimate parameters of LFM signals. Moreover, boundedness and the complexity analysis of Tuneable-Sigmoid-FFRT to the noise are presented to evaluate the performance of the proposed method. In additional, the Cramér–Rao bound for parameter estimation is derived and computed in closed form, which shows that better performance has been achieved. Both theoretical analysis and simulations demonstrate the superior performances of the proposed approach over other existing methods.