Short range wireless channel prediction using local information
Wireless channels change due to the mobility of users, which coupled with system delays, causes outdated channel state information (CSI) to be used for transmitter optimization techniques such as adaptive modulation. Channel prediction allows the system to adapt modulation methods to an estimated future CSI. The primary contribution of this paper is a low complexity channel prediction method using polynomial approximation. The method is local in the sense that only a few previous channel samples are required to estimate the next CSI. The computational complexity of the proposed method is demonstrated to be negligible compared to previous methods. Simulation results show that the proposed method accurately tracks slowly to moderately fading channels. The proposed method's usefulness is demonstrated by applying it to a multiuser OFDM system. As an example, a multiuser OFDM with a system delay of 5 ms and a Doppler spread of 40 Hz loses about 17% of its capacity due to imperfect CSI. Using the proposed algorithm to predict the CSI, the capacity loss is less than 1%.