On the performance of orthogonal polyphase sequences in asynchronous CDMA systems

Author

Alsusa, E. ; ElKalagy, A.

Author_Institution

MACS Group, Univ. of Manchester, Manchester, UK

fYear

2009

fDate

24-26 Sept. 2009

Firstpage

196

Lastpage

200

Abstract

In this paper we study the performance of orthogonal poly-phase (OPP) sequences on the uplink of asynchronous code division multiple access (CDMA) systems. We explore the application of dynamic code allocation (DCA) of OPP sequences with the objective to minimize multiple access interference (MAI), arising due to the asynchronous transmission, and enhance the system´s overall performance. Two DCA criteria are analyzed and compared. Finally, for the sake of completeness, the performance of OPP codes with and without DCA is compared to that of Walsh-Hadamard (WH) orthogonal codes and complex pseudorandom (PN) sequences for the cases of conventional rake-receiver detection as well as pre-raked transmission. It will be shown that OPP codes can provide superior performance, especially with pre-rake transmission, to both WH and PN sequences even under sever asynchronous and multipath fading conditions..

Keywords

channel allocation; code division multiple access; fading channels; interference suppression; mobile radio; multipath channels; orthogonal codes; radiofrequency interference; spread spectrum communication; DCA criteria; DS-CDMA mobile communication system; MAI; OPP sequence code; PN sequence; WH orthogonal code; Walsh-Hadamard orthogonal code; asynchronous transmission; conventional rake-receiver detection; direct sequence code division multiple access system; dynamic code allocation; multipath fading channel condition; multiple access interference minimization; orthogonal polyphase sequence; preraked transmission; pseudorandom sequence; Degradation; Detectors; Direct-sequence code-division multiple access; Downlink; Fading; Maximum likelihood detection; Multiaccess communication; Multiple access interference; Signal to noise ratio; System performance;

fLanguage

English

Publisher

ieee

Conference_Titel

Software, Telecommunications & Computer Networks, 2009. SoftCOM 2009. 17th International Conference on

Conference_Location

Hvar

Print_ISBN

978-1-4244-4973-6

Electronic_ISBN

978-953-290-015-6

Type

conf

Filename

5306829