Performance simulation of a transform domain communication system for multiple access applications

Abstract

A previously proposed interference-avoiding Transform Domain Communication System (TDCS) is shown capable of operating successfully in a Multiple Access Environment (MAE)(1). The TDCS uses phase coding (mapping) generated from a Linear Feedback Shift Register (LFSR) configured to output a maximal- length binary pseudorandom sequence (m-sequence). Quasi-orthogonal Basis Functions (BFs) are used in a Code Division Multiple Access (CDMA) scheme to provide private communication channels to independent user pairs in the MAE. An existing single channel TDCS model is augmented to simulate MAE interference effects on bit error performance (PB). The proposed TDCS system is simulated using MATLAB® for system capacities up to eight channels and E b/N0 values ranging from 0 to 9 dB. Simulated MAE TDCS bit error performance closely approximates estimated results; the error for eight channels has a mean value less than 1.7 x 10 -3 and a standard deviation less than 1.3 x 10 -3 . The