Initial synchronization assisted from inherent diversity on LTE sector search process

Estimations of time error and frequency offset upon initial synchronization are investigated in this paper as components of the sector search process in third-generation partnership project (3GPP) long-term evolution (LTE) communications. The proposed system considers intercell interference, inter-carrier interference and multipath fading by exploiting various diversity. A coarse timing alignment is achieved by the acquisition of a primary synchronization sequence. The coarse timing alignment extracts autocorrelation at a long lag of one half of a frame length from the decimated signal at a lower sampling rate by exploiting a differential correlator.

Estimations of residual time error and fractional frequency offset are achieved by evaluating the short-lag autocorrelation at an OFDM symbol duration. The estimations utilize 70 cyclic prefixes that are pre-stored in the buffer employed in the aforementioned differential correlator. The estimations can effectively overcome the time variation of the channel that occurs as a result of a Doppler spread. Comprehensive computer simulations are conducted to verify that the proposed technique can effectively overcome inter-cell interference, time-selectivity, and multipath fading, thereby achieving low estimation errors.

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