Deconvolution in the presence of Doppler with application to specular multipath parameter estimation

Modeling and Estimation of Wireless OFDM Channels by Using Time-Frequency Analysis

“…However, if there are significant Doppler frequency shifts in the channel, then the time invariance assumption above is no longer valid. In this paper, we consider time-varying modeling and estimation of OFDM channels [23], [4], [15], [6], based on a time-frequency representation approach.…”

“…In wireless communications, the multipath, fading channel with Doppler frequency shifts is generally modeled as a linear time-varying system with the following impulse response [6], [2], [18]:…”

“…The variance σ 2 i is a measure of the average signal power received at path i, characterized by the relative attenuation of that path, α i . Assuming that the sampling frequency is high enough so that the delays are integer multiples of the sampling interval, a discrete-time channel model can be obtained as [4], [6] h(m, ) =…”

“…The Doppler frequency shift ψ, on the carrier frequency ω c , is caused by an object with radial velocity υ and can be approximated by [6] ψ ∼ = υ…”

“…S( s , k) displays peaks located at the time-frequency positions determined by the delays and the corresponding Doppler frequencies, with α i as their amplitudes [6], [4]. If we extract this information from the received signal, we should then be able to figure out the transmitted data symbol.…”