Title :
Complex Hadamard Transform-Based Quaternary Quasi-Orthogonal Sequences and Allocation for DS-CDMA Systems
Author :
Xie, Shoulie ; Gu, Zhenghui ; Rahardja, Susanto
Author_Institution :
Inst. of Infocomm Res.
Abstract :
The capacity of downlink direct-sequence code-division multiple access (DS-CDMA) system is often limited by the available number of Walsh-Hadamard (WH) codes. Using quasi-orthogonal sequences (QOSs) is a practical solution to enhance the capacity. In this paper, a new construction for a set of quaternary quasi-orthogonal sequences (QQOSs) is proposed based on a complex Hadamard transform (CHT) matrix. This approach is simple and easy to generate QQOSs with any length in {2m, m=1, 2,...,}. Meanwhile, allocation schemes of proposed QQOSs are investigated for downlink DS-CDMA systems over frequency selective fading channel. Simulation shows that different sequence allocation schemes result in different bit error rate performance
Keywords :
Hadamard codes; Hadamard matrices; Hadamard transforms; Walsh functions; code division multiple access; error statistics; fading channels; spread spectrum communication; Hadamard transform-matrix; Walsh-Hadamard codes; bit error rate; direct-sequence code-division multiple access; downlink DS-CDMA systems; frequency selective fading channel; quasiorthogonal sequences; quaternary QOS; Binary sequences; Bit error rate; Downlink; Error correction; Error correction codes; Fading; Gold; Multiaccess communication; Quadrature phase shift keying; Radio spectrum management;
Conference_Titel :
Communication systems, 2006. ICCS 2006. 10th IEEE Singapore International Conference on
Conference_Location :
Singapore
Print_ISBN :
1-4244-0411-8
Electronic_ISBN :
1-4244-0411-8
DOI :
10.1109/ICCS.2006.301491