Theory of MIMO biorthogonal partners and their application in channel equalization

Channel equalization is an important step in most applications of digital communications. In this paper we consider the equalization of multiple input multiple output (MIMO) channels. To that end we derive the theory of MIMO biorthogonal partners, a concept that has already been introduced (only in the scalar case) by the authors. We develop conditions for the existence of an FIR MIMO biorthogonal partners and describe their application in the MIMO channel equalization. We also show that it is possible to exploit the non-uniqueness of FIR MIMO biorthogonal partners in order to design flexible fractionally spaced MIMO equalizers that will be more robust to the channel noise.