a new symbol time synchronization technique for short-burst TDM transmissions

• Main Authors: jin, yuh-chuan, 金郁川
• Other Authors: thomas t. fang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/09587688742791529558

碩士 === 國立中正大學 === 電機工程學系 === 85 === Two key elements in the design of a demodulator are symbol time synchronization and offset frequency synchronization. PACS( Personal Access Communication Service)is a low-power microcell mobile phone system proposed by Bellcore. This system features short-burst TDM transmission at 1.8 GHz. Bellcore has proposed a method of implementing the PACS demodulator which has been patented. The Bellcore method obtains (1) symbol synchronization, (2) an estimate of the offset frequency,and (3) the quality measure, i.e., an estimate of the channel(path) quality simultaneouslyafter a predetermined set of computation. We develop a new method which obtainsa symbol time synchronization and a frequency offset estimation through separatecalculations, whith symbol time estimation preceeding frequency offset synchronization.However the total of the two calculation does not exceed the one data burst limit. Furthermore, the amount of computation in this new method is comparable to that Bellcore method. This thesis addresses the problem of symbol time synchronization for a PACSmodem. A prefilter-square-DFT combination was able to determine the proper sampingpoint within 30 symbols. This, in conjunction with the 30 symbol periods required for the frequency offset estimation algorithm, is able to complete the time and freuency synchronization within one burst of 64 symbols, as required by the PACS specifications. Analysis, computer simulation results and hardware architectureare presented.