High mobility data symbol based channel estimation for Downlink OFDMA IEEE 802.16e standard

High mobility communication systems need suitable channel estimation to cope high frequency selectivity and time variation channel. In recent study on downlink OFDMA mobile WiMAX, channel estimation was done by exploiting pilot from preamble instead of pilot from data symbol due to ununiformly pilot spacing in this standard. In this paper we propose to obtain channel transfer function by exploiting pilot at data symbol. We try two interpolation scheme for this data symbol based channel estimation. First is two dimensional MMSE/linear interpolation scheme. Linear interpolation was carried out at time domain and MMSE interpolation was performed at frequency domain. The other is linear interpolation for both dimension/domain. Based on our simulation, it is proven that the data symbol based channel estimation method have better performance compare with preamble based channel estimation method. It is also shown that the MMSE interpolation at frequency domain achieve better performance at highly dispersive channel (ITU-B vehicular).