Experimental evaluation of pilot arrangement for channel estimation in OFDM systems

Pilot pattern and pilot density are often used for channel estimation in optical/electronic orthogonal frequency division multiplexing (OFDM) systems. To enhance the performance of the channel estimation of OFDM systems, the transmission of the OFDM signals is experimentally investigated via different pilot tone arrangements for effective channel estimation. Three types of pilot patterns (comb-type, block-type and incline-type) are used to evaluate the output OFDM signal in terms of error vector magnitude (EVM), based on the most commonly adopted low complexity Least Square (LS) channel estimation algorithm. It has been shown that, the pilot insertion will definitely improve the quality of the transmitted OFDM signals up to 6 dB in EVM. The best channel estimation is obtained by the block-type pilot pattern, which gives nearly 1dB gain in EVM compared with the other two patterns, implying the measured channel of the electronic cable is relatively quasi-static.