| It is modulation technology that plays an important role in digital communication system. There are four conventional modulation methods such as ASK, PSK, FSK and QAM in wireless digital communication system. OFDM of multi-carrier modulation, which can match the criterion which is required by 4G lately developed, is widely adopted. OFDM has its own advantages over other modulation methods which are confined to multi-path delay, hence it can fulfill high-speed data transmission rate. As OFDM has a strict limit to orthogonal between each sub-carrier, transmission reliability of OFDM system is susceptible to Doppler frequency-shift from wireless channel and frequency deviation between carrier frequency of transmitter and local oscillator of receiver. So simulation and analysis of a novel non-orthogonal modulation method (NMT) are studied in this thesis. Three kinds of modulation methods MLSK, NMAM and NFDM are involved in NMT. The previous researches demonstrate that NMAM has considerable effect on increasing transmission rate and enlarging transmission distance.The objective of the thesis is to investigate the applications of MLSK and NMAM in wireless communication and the system performance by MATLAB simulation using Rayleigh model. The system performance of the MLSK is analyzed under different demodulation methods for AWGN and Rayleigh channel and compared with that of PSK. Furthermore, the improvement of system performance on NMAM after introduction of wave pre-processing and channel estimation with training sequences is also researched and compared with that of 16QAM. As far as bandwidth and efficiency are concerned, experimental results show that MLSK is superior to PSK. The system performance of NMAM is further improved after introduction of wave pre-processing and channel estimation. Hence the transmission performance of NMAM is more reliable than that of 16QAM under the same conditions. Finally, analysis and comparison are researched considering NFDM and OFDM. |
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