Correlation method for channel estimation for OFDM

Abstract

The present invention concerns a method for estimating the time-dispersion of a channel comprising D subschannels, wherein one computes from a received signal a set of estimated Channel Transfer Factors (CTF's) H[nu], where nu (0<= NU<D) is the subchannel number, said method comprising a step of calculating, for a predetermined strictly positive integer d, a correlation factor Cd representing thecorrelations, both in amplitude and in phase, between pairs H[nu] and H[nu + d] of said computed CTF estimates. By an appropriate choice of d, the time-dispersion resolution can be adapted to most prevalent channels. The correlation is optionally corrected according to the mean channel estimation signal-to-noise ratio. This method can be useful for many applications where knowing the time-dispersion characteristics of a channel is required, and is, for example, particularly suitable for designing a channel estimation filter, and for link adaptation. Application to devices and apparatus implements these methods.

Description

technical field The present invention relates to methods and devices for channel estimation in communication systems utilizing Orthogonal Frequency Division Multiplexing (OFDM). Background technique The invention is particularly applicable to the field of wireless digital communication systems. Among these systems, one usually deals with multipath channels: reflections due to obstacles. The transmitted signal travels many paths to reach the receiver. The received signal is thus produced by the superposition of multiple replicas of the transmitted signal, each replica of the transmitted signal being associated (in the equivalent complex baseband representation) with a specific time delay and attenuation. The received signal is thus equal to the convolution of the transmitted signal with the so-called Channel Impulse Response (CIR) h(t), where t represents time. The CIR is non-zero only in the interval 0<t<τ, where τ is the so-called excess delay of the channel, ie t...

AI Technical Summary

Problems solved by technology

The second has a bandwidth properly determined after the receiver computes the CIR by Fourier transforming the CTF: but this transform from the frequency domain to the time domain is computationally quite expensive

But this function is defined more or less heuristically and does not take into account the phase of said frequency domain samples, so this method is not reliable to perform

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