A simplification in integral frequency offset estimation based on joint detection algorithm for WiMAX 802.16e

Initial downlink synchronization for orthogonal frequency division multiple access ( OFDMA ) network access involves timing and frequency synchronization. The frequency offset is produced by oscillator drifts and time-varying Doppler shifts. In mobile WiMAX 802.16e carrier frequency offset (CFO) can be divided into: integral carrier frequency offset (ICFO) and fractional carrier frequency offset (FCFO). There are mainly three methods for CFO estimation: data-aided method, blind and semi-blind. This paper is based on the semi-blind method presented in "Joint detection of integral carrier frequency offset and preamble index in OFDMA WiMAX downlink synchronization", IEEE, 2007 , see [2]. We simplify the algorithm presented in that paper by (a) using an adder-subtractor instead of using squares to estimate power and (b) by using a XNOR instead of complex multiplier; thereby reducing hardware gates by a factor of 676. Simulation results show only a slight degradation in performance with a considerable reduction in complexity.