Exploiting asynchrony in DS-CDMA systems through interference avoidance

Author

Hombs, Brandon ; Lehnert, James S.

Author_Institution

BAE Syst. E&IS, Nashua, NH, USA

Volume

3

fYear

2005

fDate

28 Nov.-2 Dec. 2005

Abstract

User capacity in synchronous CDMA systems has been well characterized and is fixed by the processing gain and target SIR required by each user. Asynchronous systems have not been as well studied. This paper examines the user capacity of asynchronous CDMA systems. It is shown that the user capacity can be increased over synchronous systems by allowing the users to be chip asynchronous and adapting their spreading codes to decrease interference. The degree to which the system experiences a gain by asynchrony is characterized by the effective dimension of the chip waveform. Simulation results are provided to verify that the user capacity is improved by allowing asynchrony when interference avoidance algorithms are employed.

Keywords

code division multiple access; codes; interference suppression; radiofrequency interference; spread spectrum communication; DS-CDMA systems; chip waveform; interference avoidance algorithms; spreading codes; synchronous CDMA systems; user capacity; Code division multiplexing; Feedback; Interference suppression; Iterative algorithms; Multiaccess communication; Multiple access interference; Power system modeling; Signal processing; Timing; Transmitters;

fLanguage

English

Publisher

ieee

Conference_Titel

Global Telecommunications Conference, 2005. GLOBECOM '05. IEEE

Print_ISBN

0-7803-9414-3

Type

conf

DOI

10.1109/GLOCOM.2005.1577914

Filename

1577914