Timing synchronization schemes for ofdm based wireless systems

Abstract

Wireless communication has recorded a remarkable and exponential growth in the demand newlineof multimedia services. The environment of future wireless applications demands high newlinedata rate communication with high spectral efficiency. OFDM is capable of providing high newlinedata rate multimedia services in wireless environment, such as WLAN, WiMAX, LTE (4G newlinestandard), and MB-OFDM etc. However, OFDM is very sensitive to synchronization newlineerror. The goal of this thesis is to investigate new methods for timing synchronization in newlineOFDM-based systems. newlineWe have studied different classical data aided timing synchronization schemes due to newlineSchmidl and Cox, Minn and Park, where OFDM symbol with several identical are generated newlineusing IFFT operation with PN sequence as input. It is observed that the timing metric for newlinethe scheme due to Park has sharp peak at correct time and several small peaks compared to newlinethe Cox s scheme and Minn s scheme. The presence of smaller peaks at instances other newlinethan correct time results in poor timing synchronization. We have presented a modified newlinetiming metric, where the denominator is the sum of square of difference of absolute value newlineof the sample in the correlation window. The low value of the denominator at correct time newlineresults in the significantly high value of the timing metric and very low value of the timing newlinemetric at any other time. High value of timing metric at correct time and very low value of newlinetiming metric at other time for the proposed scheme shows high peak to side lobe ratio newlinecompared to park s scheme. Probability of detection of our scheme is observed to be better newlinethan other classical schemes. This scheme can also be applied to MIMO OFDM system. newlineSeveral classical timing synchronization schemes have been proposed for the timing newlinesynchronization in OFDM systems based on the correlation between identical parts of newlineOFDM symbol. It is observed that the PAPR of the time domain OFDM symbol designed newlinefor timing synchronization is high. These schemes show poor performance due to the newlinepresence of plateau and significa