GSM TDMA Frame Rate Internal Active Noise Cancellation

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Full text:
Author(s): Ingvar Claesson, Andreas Nilsson
Title: GSM TDMA Frame Rate Internal Active Noise Cancellation
Journal: International Journal of Acoustics and Vibration
Year: 2003
Volume: 8
Issue: 3
Pagination: 159-166
ISSN: 1027-5851
Publisher: Int. Inst. Acoustics and Vibration, USA
Organization: Blekinge Institute of Technology
Department: Department of Telecommunications and Signal Processing (Institutionen för telekommunikation och signalbehandling)
Department of Telecommunications and Signal Processing S-372 25 Ronneby
+46 455 38 50 00
Authors e-mail: icl@bth.se, andreas.s.nilsson@ericsson.com
Language: English
Abstract: A common problem in the world's most widely-used cellular telephone system, the GSM system, is the interfering signal generated by the switching nature of TDMA cellular telephony in handheld and other terminals. Signals are sent as chunks of data, speech frames, equivalent to 160 samples of data corresponding to 20 ms at sampling rate of 8 kHz. This paper describes a study of two different software solutions designed to suppress such
interference internally in the mobile handset. The methods are 1) notch filtering, which is multiplicative in frequency, and 2) subtractive noise cancellation, which is an alternative method employing correlators. The latter solution is a straigtforward, although somewhat unorthodox, application of "in-wire" active noise control. Since subtraction is performed directly in the time domain, and we have access to the state of the mobile, it is also possible to consider a recurring pause in the interference caused by the idle frame in the transmission, when the mobile listens to other base stations communicating. More complex control algorithms, based on the state of the communication between the handset and the base station, can be utilised.
Subject: Signal Processing\Speech Enhancement
Signal Processing\Active Noise and Vibration Control
Keywords: Active Noise Cancellation, Cellular Phone, GSM, Bumblebee
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