Minimum redundancy filterbank precoder for blind channel identification irrespective of channel nulls

In this paper we propose a blind deterministic method for channel estimation based on the introduction of minimal redundancy on the transmitted data sequence through linear precoders that map consecutive blocks of information symbols onto higher size blocks. This transmission scheme incorporates, for example, OFDM and CDMA systems. We prove that even allowing the transmitted data block to be longer than the information block by only one sample is sufficient to guarantee the channel identification uniquely with a deterministic algorithm, without any restriction on the channel zero location and under sufficient conditions on the precoder only, which can be easily checked a priori. Our proposed blind estimation method is able to work with any amount of extra redundancy and this renders the method particularly useful for all applications where the channels have long impulse responses, such as in wired as well as in wireless macrocellular communication systems.