Reduced Length Chirp Pilots for Estimation of Linear Time-Varying Communication Channels

Abstract: In wireless communication multipath fading causes significant performance degradation and necessitates channel estimation. Transmission of two consecutive chirps with different rates as a pilot sequence is a method that has been used in the estimation of linear time-varying (LTV) channel parameters. In this paper, we propose an improvement on the chirp based channel estimation method for LTV model. We show that combination of a chirp with its complex conjugate, in particular a frequency modulated sinusoid, provides us an efficient pilot sequence. Besides reducing the length of the pilot sequence by half, the length and the rate of our proposed pilot sequence can be adjusted to comply with a-priori information on the channel. We implement the proposed method for an orthogonal frequency division multiplexing (OFDM) communication system and compare with conventional two chirps method.