Highly Time Varying Channel Estimation for OFDMA Uplink Transmission in IEEE 802.16e Network

Basis expansion model (BEM) based estimation is studied for highly time varying OFDMA uplink channel. We consider two popular pilot patterns-pilot placed over frequency-time grid as proposed in IEEE 802.16e standard and pilot placed on the time axis. In a high Doppler spread scenario, taking intercarrier interference (ICI) impact from data block into account, least square (LS) estimator is developed for both time and frequency domain pilot aided estimation. From the performance analysis and simulation result, it is shown that, time domain LS (LS-T) estimator performs better than the current frequency domain estimator. The computational complexity for time domain LS is also discussed.