New Pilot Designs and ICI Mitigation for OFDM Downlink Systems based on IEEE 802.16m Standards over High Speed Vehicular Channels

Two new pilot patterns and channel estimation methods robust to inter-channel-interference (ICI) caused by fast fading channels are proposed which are applicable to 802.16m standards. A number of clusters of pilot subcarriers are used for channel estimation. In addition, the number of needed parameters for channel estimation is reduced by some properties of ICI in the time and frequency domains. Simulation results show that the proposed channel estimation has good bit-error- rate (BER) performance compared to conventional method based on 802.16m standards at the velocity of 350 km/h and has the same performance at the velocity of 3 km/h. Moreover, if the target BER is lower than the supportable BER of conventional method with uncoded 16 QAM, then the proposed method can be better option compared to diminish the modulation scheme as 8 PSK considering both BER and throughput.