1. A reduced state sequence estimation decoder for a multidimensional code, wherein a multidimensional code symbol comprises a number of symbol components of lower dimensionality, comprising: at least one branch metric unit that calculates branch metrics for a received signal based on intersymbol interference and intrasymbol interference estimates, said at least one branch metric unit compensating for intrasymbol interference caused by symbol components within a current multidimensional code symbol; and a decision feedback unit that processes survivor symbols to calculate the intersymbol interference estimates for different code states of said multidimensional code and channels used to transmit said multidimensional code.