Blind channel estimation for precoded variable bit-rate multiuser systems

The precoder has been shown to be able to provide source diversity and more freedom in design. In this paper we employ precoding techniques for block transmission based on a multirate filterbank structure. To meet multiuser communication requirements for various high data-rates, different filterbanks are used as precoders with corresponding coefficients and up/down sampling rates. However due to high speed communication in the presence of unknown multipath, different interferences exist in the received data such as multiuser interference, intersymbol interference and interblock interference. To estimate the multipath channel for a desired user we generalize the subspace method by employing all signatures associated with this channel in the current system. In this way a better performance for the channel estimate can be achieved. The delay for that user can also be jointly estimated together with channel estimation.