Patent Document ID: 20170180063
Application ID: 14976854
Patent Flag: 0

Claim One:
1. In a digital communication system comprising: a transmitter, a receiver and a transmission channel, which could be wired or wireless and may distort a transmitted signal; the transmitted signal having the following characteristics: a bandwidth and spectral shape known to both the transmitter and the receiver; a test sequence embedded within the transmitted signal; the contents of the test sequence being known in advance by both the transmitter and the receiver; the location of the test sequence both in time and frequency being known by both the transmitter and the receiver; wherein the transmission channel is a multipath channel, comprising a plurality of channel paths, including a dominant channel path. a method at the receiver of estimating the multipath channel's frequency response, comprising: downconverting the received signal at the receiver to baseband; locating and extracting the received version of the test sequence from the received signal; executing a signal processing algorithm upon the received version of the test sequence in order to estimate the multipath channel's frequency response; the signal processing algorithm comprising the steps of: modeling the multipath channel as a series of L multipath components, each having an associated delay and gain factor which are to be estimated; calculating an initial rough approximation of the multipath channel's impulse response using the received version of the test sequence; iteratively estimating the delays and gain factors by: a) performing peak detection on absolute values of the approximation of the multipath channel's impulse response to estimate the gain factor and delay of the dominant channel path; b) modulating the gain factor and delay with a modeling function to obtain an estimate of the effect of the dominant channel path upon the approximation of the multipath channel's impulse response, where the modeling function is determined based upon the bandwidth and spectral shape of the transmitted signal; c) subtracting the estimate of the effect of the dominant channel path from the approximation of the multipath channel's impulse response, such that the next largest channel path in terms of gain factor's magnitude becomes the dominant channel path in the remaining approximation of the multipath channel's impulse response; d) repeating L−1 times, said delay and gain factor estimation steps a) to c) to fully obtain all delays and gain factors of the plurality of channel paths. e) iteratively performing steps a) to d) one or more times in order to further refine the estimate of the delay and gain factors until a desired level of accuracy is reached; and f) using the delay and gain factors obtained at the last iteration to obtain the frequency response of the multipath channel by applying a discrete Fourier transformation.