Research On Synchronization Technologies Of Hybrid Carrier Communication System

In recent years, a kind of weighted fractional Fourier transform(WFRFT) is introduced to communication system as a mathematical tool to analysis data in the time-frequency domain, due to the particularity of the transformation, a kind of hybrid carrier( HC) communication system came into reality.Weighted-type Fractional Fourier Transform(WFRFT) is a new mathematical tool for time-frequency domain analysis. In recent years it has been applied in communication system and formed a hybrid carrier(HC) communication system, single carrier(SC) and multi carrier(MC) communication are included in the system thus signal transfer in time-frequency domain can be realized. Because the HC communication system includes both single carrier and multi carrier communication, the communication performance of it can be different from them. The traditional multi carrier communication system is the OFDM(Orthogonal Frequency Division Multiplexing) system and the single carrier communication system is the SC-FDE(Single Carrier Frequency Domain Equalization) system. OFDM symbol consists of multiple orthogonal subcarrier signals and it’s crucial to ensure the orthogonality for the OFDM system, thus one of the main problems of the OFDM system is very sensitive to the frequency offset. SC-FDE system is very sensitive to the timing error, which is because the symbol decision is carried out in the time domain, and its receiving end has a higher accuracy requirements. Because the HC communication system includes both multi carrier and single carrier communication, it is bound to face the problem of two kinds of carrier systems. In this paper, we majorly study the synchronization technology of HC communication system.Firstly, the mathematic theory of WFRFT is analyzed and summarized, after which the system model based on HC is given. Then the time domain signal in this system is analyzed and the time domain signal waveform, the signal constellation and signal power spectrum are giver.Secondly, this paper analyzes the influence of timing error on the HC system, and gives the effect of timing synchronization error in the way of mathematical deduction. Then the paper analyses the traditional timing synchronization algorithms, and designs an improved algorithm according to the advantages and disadvantages of the traditional algorithms. It can be seen from the simulation that the algorithm can obtain accurate timing synchronization with a small amount of calculation.Thirdly, this paper analyzes the impact of frequency offset on the HC system, and gives the effect of frequency offset in the way of mathematical deduction. Then the paper analyses the traditional frequency offset estimation algorithms, and designs an improved algorithm according to the advantages and disadvantages of the traditional algorithms. It can be seen from the simulation that the algorithm can obtain accurate frequency offset estimation with timing error. Compared with the traditional algorithm, a better communication performance can be achieved.