Performance Analysis Of Faster-than-Nyquist (FTN) Signaling And Overlapped Time Domain Multiplexing (OVTDM) Under High Mobility Scenarios

Faster than Nyquist (FTN) signaling and Overlapped Time Division Multiplexing (OVTDM) are promising technologies which may break the traditional Nyquist transmission technology, hence providing efficient spectrum utilization while increasing the information transmission rate. FTN focuses on increasing the symbol rate, thus making transmission interval less than Nyquist criterion by shortening the symbol interval, and improving the spectrum efficiency while maintaining the minimum Euclidean distance to guarantee error probability at an acceptable level. OVTDM uses shifted overlapping transmission, and introduces intentionally controlled inter-symbol interference, in order to improve the signal output level distribution. OVTDM emphasizes the idea of waveform division to distinguish different signals, to achieve higher coding gain and spectral efficiency. Besides, OVTDM employs waveform division rather than level division, thus can be considered as a kind of waveform coding.However, the existing research shows that, although the decoding performance of different systems using FTN or OVTDM has been analyzed extensively, but mainly under the AWGN channels or low mobility scenarios. As far as the author is aware, no work is done for high mobility scenarios for FTN or OVTDM systems. Therefore, it is very important to design appropriate receiver in order to more accurately estimate the fast time-varying channel state caused by the high mobility, to more effectively eliminate the inter-symbol interference (ISI) and inter-carrier interference (ICI).Considering the influence of the fast time-varying channel interference, this thesis proposes an improved receiver structure, by adding iteration based fast time-varying interference estimation and pre-elimination module to the existing FTN or OVTDM receivers, in order to pre-estimate and eliminate the interference due to fast time-varying channel characteristics and non-orthogonal transmission.Our simulation results shows that, the acceleration factor has significantly impact on the performance of FTN system. The thesis analyses the trade-offs between the data transmission rate and error performance. In particular, the thesis has investigated the error performance of FTN and OVTDM systems, especially to improve the receiver performance under high mobility scenarios by eliminate the colored noise by using the noise whitening mechanism.