An asynchronous spread spectrum multi-carrier multiple access system

Author

Kaiser, Stefan ; Krzymien, Witold A.

Author_Institution

Inst. for Commun. Technol., German Aerosp. Res. Establ., Oberpfaffenhofen, Germany

fYear

1999

fDate

1999

Firstpage

314

Abstract

We investigate the effects of the asynchronism of user signals in the uplink of a spread spectrum multi-carrier multiple access (SS-MC-MA) system. The proposed uplink SS-MC-MA scheme uses for synchronization only the frame structure received on the synchronous downlink and requires no additional synchronization measures. A guard interval that is smaller than the sum of the maximum time offset between the users and the maximum excess delay of the frequency selective multipath channel is used. It minimizes the loss in bandwidth efficiency by allowing residual interference. The residual interference is minimized by proper positioning of the detection interval in the receiver. It is shown that with this approach the guard interval can be reduced by about 50%

Keywords

adjacent channel interference; cellular radio; delays; interference suppression; intersymbol interference; multi-access systems; multipath channels; multiuser channels; radio links; spread spectrum communication; synchronisation; OFDM; SS-MC-MA system; asynchronous spread spectrum system; bandwidth efficiency; cellular radio; detection interval; frame structure; frequency selective multipath channel; guard interval; interchannel interference; intersymbol interference; maximum excess delay; maximum time offset; multi-carrier multiple access system; receiver; residual interference; synchronization; synchronous downlink; uplink; user signals; Bandwidth; Communications technology; Digital video broadcasting; Downlink; Frequency synchronization; Interchannel interference; Multiaccess communication; Multiple access interference; OFDM modulation; Spread spectrum communication;

fLanguage

English

Publisher

ieee

Conference_Titel

Global Telecommunications Conference, 1999. GLOBECOM '99

Conference_Location

Rio de Janeireo

Print_ISBN

0-7803-5796-5

Type

conf

DOI

10.1109/GLOCOM.1999.831656

Filename

831656