Downlink channel estimation and tracking in mobile WiMAX systems

Mobile WiMAX is a new promising technology based on IEEE 802.16-2005 that supports high-speed, broadband fixed and mobile services through using orthogonal frequency division multiple access (OFDMA). In mobile communications, channel estimation is important for system performance, but at the same time it is very crucial when the fading channel is fast time-varying. In this paper, a cluster-based downlink channel estimation and tracking in mobile WiMAX is evaluated based on least square (LS) methods. Interpolation between channel estimates at pilots is carried out both over frequency and time to compensate between high data transfer rate as well as efficient channel estimation. Simulation results in terms of mean square error (MSE) and bit error rate (BER) show that channel estimation over two OFDM symbols exhibits better performance compared to that of single OFDM symbol even at high Doppler frequencies.