Performance of quasisynchronous scale time code division multiple access for AWGN channel

Abstract

We analyze bit error rate performance of a recently proposed multiple access system called scale time code division multiple access (STCDMA) for quasisynchronous communication over an AWGN channel. STCDMA depends on code, time and scale orthogonality introduced by spreading sequences and wavelets. Wavelets are employed as an orthogonal set of symbols for signaling, and their orthogonality over scale and time is exploited. The channel is partitioned into different scales, and each scale into different time slots. Each user is assigned a specific scale, time slot, and spreading code. Information symbols of each user are encoded by the Haar wavelet in its scale and time slot, and then they are spread by its spreading code. Complex-valued Hadamard sequences are used as spreading sequences and conventional detector (i.e. matched filter) is used at the receiver. Results show that the performance of STCDMA gets much better than that of CDMA over the quasisynchronous AWGN channel as the number of scales increases. (c) 2007 Elsevier Ltd. All rights reserved.