Research Of Time And Frequency Synchronization Technology In WiMAX System

With the fast development of broadband wireless communication technology,WiMAX, the pioneer of 4G, will be applied for business-use soon. The synchronizationtechnology in the mobile WiMAX (IEEE 802.16e) system that can dramaticallyinfluence the performance is researched in this thesis. Firstly, the current state anddevelopment of WiMAX as well as the OFDM and OFDMA systems are introduced.Then the IEEE 802.16e standard and the time and frequency synchronizationtechnology in OFDM system are introduced too. The downlink and the uplink ofmobile WiMAX system are different. In the uplink system, a synchronizationalgorithm based on ranging symbol is given for ranging slot. And an algorithm basedon pilot symbol is given for Data slot. Then an improved algorithm for timesynchronization in ranging which makes full use of the correlation between rangingcodes is proposed. Through the MATLAB simulation, we find that it improves thesynchronization performance a lot. In the downlink system, the time and frequencysynchronization technologies are carefully researched in both the situation of singlecell and the situation of multiple cells. In the situation of single cell, the triple-repeatcharacter of the preamble is used to do the synchronization. In the situation of multiplecells, both the Cyclic Prefix (CP) and the Common Sync Symbol can be used to do thesynchronization. The two algorithms are given respectively in this thesis. Their resultsof the MATLAB simulation demonstrate that they are both useful and effective.