Title: Suppressing opposite-direction interference in TDD/CDMA systems with asymmetric traffic by antenna beamforming
Authors: Chen, CJ
Wang, LC
交大名義發表
National Chiao Tung University
Keywords: adaptive arrays;beamforming;code-division multiple-access (CDMA);land mobile cellular systems;time-division switching
Issue Date: 1-Jul-2004
Abstract: One of the key advantages for the time-division duplex (TDD) system is the capability to deliver asymmetric traffic services by allocating different numbers of uplink and downlink time slots. However, in a TDD/code-division multiple-access (CDMA) system, asymmetric traffic may result in severe opposite-direction interference because downlink transmitted signals from neighboring base stations may interfere with the uplink received signals of the home cell. In this paper, we investigate the effect of four-antenna beamforming schemes from the perspective of suppressing the opposite-direction interference. We compare the uplink bit energy-to-interference density ratio of a traditional beam-steering technique (Scheme 1) with that of the minimum-variance distortionless-response (MVDR) beamformer (Scheme 11). Furthermore, Scheme III applies the conventional beam-steering technique for both downlink transmissions and the uplink reception. In Scheme IV, we implement beam-steering for downlink transmissions, while adopting the MVDR beamformer to process the uplink signals received at base stations. Our numerical results indicate that Scheme IV outperforms all the other three schemes, which can effectively suppress the strong opposite-direction interference in TDD/CDMA systems. While keeping low implementation costs in mind, employing the simpler Scheme HI in a sectorized cellular system can also allow every cell to provide different rates of asymmetric traffic services.
URI: http://dx.doi.org/10.1109/TVT.2004.830941
http://hdl.handle.net/11536/26585
ISSN: 0018-9545
DOI: 10.1109/TVT.2004.830941
Journal: IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
Volume: 53
Issue: 4
Begin Page: 956
End Page: 967
Appears in Collections:Articles


Files in This Item:

  1. 000222884400002.pdf

If it is a zip file, please download the file and unzip it, then open index.html in a browser to view the full text content.