MIMO channel orthogonalisations applying universal eigenbasis

Abstract

Some mathematical fundamentals of the multiple input multiple output (MIMO) channel orthogonalisations using prolate spheroidal wave functions (PSWFs) as a universal basis are presented. In contrast to the Karhunen–Loeve expansion or singular value decomposition, the PSWF basis is ‘invariant’ to the properties of the MIMO channel covariance matrix and provides an almost minimum set of eigenfunctions that allow the channel to be represented with a predefined accuracy.