Multi-carrier CDMA systems using bridge functions

Abstract

Multi-Carrier CDMA systems appear to be a good candidate for high speed wireless data transmission. These systems avoid time domain equalization and have the capability of achieving high diversity gains over frequency selective fading channels. Orthogonal Walsh-Hadamard spreading waveforms have been commonly considered for these systems. However, reliable system performance over f r e quency selective fading channels requires complicated detector structures with a complexity that increases with the length of the spreading code.In this paper a multi-carrier CDMA system using the Bridge functions as spreading waveforms is considered and its performance over frequency selective fading channels is evaluated. The Bridge functions are three valued orthogonal functions which take the values +1, 0, and -1. Such a structure adds flexibility to the multi-carrier CDMA where the number of zeros in the spreading code can be used to decide on the frequency separation between the modulated subcarriers and thus avoiding the need for frequency interleaving. Another benefit is the possibility to use more powerful detectors at the receiver. Infact, this combined system can be seen as a generalization to multi-carrier CDMA where the Bridge functions play the role of bridging between the regular OFDM with no spreading and multi-carrier CDMA with WalshHadamard functions.

A new direct-sequence UWB transceiver based on Bridge function sequence

“…Bridge function sequence with built-in ZCZs is a kind of well established ternary mutually orthogonal sequences, which is being employed in the fields such as multi-carrier CDMA, Haar wavelet, passive beamformer etc [7][8][9][10] …”

Performance Analysis of Frequency Diversity for Multi-Carrier CDMA System Based on Bridge Function

“…Slimane and Abdullatif firstly introduced bridge function into MC-CDMA system [3]. Reference [ ] analyzes the influence of channel parameters, multiple access interference (MAI) and combining algorithm on frequency diversity gain, and compares the performance of continuous spreading with that of discrete spreading random spreading.…”

The novel generating algorithm and properties of hybrid-P-ary generalized bridge functions

“…Zhang et al [7] introduces the bridge function theory in detail, and discusses its main properties and application. Slimane [8] designs a multi-carrier CDMA communication system using bridge functions as spread spectrum code, and discusses the system's properties under frequency selective fading channel. The combined system can be seen as a generalization of multi-carrier CDMA where the bridge functions play the role of bridging between the regular OFDM with no spreading and multi-carrier CDMA with Walsh functions.…”