Proceedings ArticleDOI
Quality of service and bandwidth efficiency of cellular mobile radio with variable-bit-rate speech transmission
David J. Goodman,C.-E.W. Sundberg +1 more
- Vol. 33, pp 316-321
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TLDR
The performance of an adjustable source/channel codec in a cellular mobile-radio environment is investigated and it is found that this approach offers an improved grade of service.Abstract:
We have investigated the performance of an adjustable source/channel codec in a cellular mobile-radio environment. The speech transmission rate and the amount of forward error correction change in response to changing channel conditions. The channel rate is constant at 32 kb/s and when the channel is good all of these bits are used for speech transmission. In intermediate and poor channels the speech rate is 24 or 16 kb/s and the remaining channel symbols are used for forward error correction. Relative to conventional transmission this approach offers an improved grade of service. For example, the outage rate (the proportion of "poor or worse" communications) goes from 9% with fixed-rate to 3% with variable-rate transmission. Alternatively, this improved grade of service can be exchanged for higher bandwidth efficiency. The fixed-rate system (with 9% outage) has 23 users per cell. With 52 users per cell the outage of the variable-rate system is only 6%.read more
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References
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Journal ArticleDOI
Outage Probability in Mobile Telephony Due to Multiple Log-Normal Interferers
Yu-Shuan Yeh,S. Schwartz +1 more
TL;DR: The average outage probability is computed for centrally located base stations when multiple log-normal interferers are present and it is found that the outage probabilities for the two cases do not differ in a significant way.
Journal ArticleDOI
Embedded DPCM for Variable Bit Rate Transmission
TL;DR: In this paper, an adaptive DPCM (ADPCM) encoder and decoder is proposed for variable rate transmission with variable bit rates up to any desired maximum. But the decoded analog signal is substantially noisier than the output of an ADPCM encoder with D = E - C bits/sample.
Proceedings Article
Embedded DPCM for variable bit rate transmission
TL;DR: Within the bit stream of an embedded digital code is a stream that can be decoded to produce a reasonable replica of the analog source signal, and with minor modifications to the encoder and decoder, DPCM becomes an embedded code.
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Models for the subjective effects of loss, noise, and talker echo on telephone connections
TL;DR: These subjective test results are used to formulate graphical and analytical models of subjective opinion that can be used in network planning studies to evaluate transmission performance of the network and to study the effects of network changes on performance.
Journal ArticleDOI
A 60 Channel PCM-ADPCM Converter
TL;DR: The ADPCM technique described in this paper features a simple adaptive quantization scheme and a tenth-order linear prediction adaptive filter realized as a cascade of five second-order sections, resulting in superior performance characteristics and the nonaccumulation of degradations in tandem connections.