In fast fading channel, for reducing detection complexity, a nearly banded channel is adopted in many literatures. For the sake of designing a nearly banded channel perfectly, the authors deduce the relationship between the bandwidth of the nearly banded channel matrix and normalised Doppler frequency shift under certain power of negligible intercarrier interference (ICI) coefficients. Then, in order to take account of all the ICI coefficients when the nearly banded channel matrix is divided into Nblocks, a new structure of nearly banded channel matrix is proposed.
On the basis of the new proposed structure, sequential detection with successive cancellation and sequential detection with optimal ordering are applied to detect the orthogonal frequency division multiplexing signals in each block. Simulation results show that although a little more computational complexity is costly, the detection methods using the proposed structure can achieve better performance than the detection methods using the original blocks.