DocumentCode :
2410786
Title :
Channel-adaptive modulation
Author :
Williams, J. ; Hanzo, L. ; Steele, R.
Author_Institution :
Southampton Univ., UK
fYear :
1995
fDate :
26-27 Sep 1995
Firstpage :
144
Lastpage :
147
Abstract :
Packet reservation multiple access (PRMA) assisted adaptive modulation using 1, 2 and 4 bit/symbol transmissions is proposed as an alternative to dynamic channel allocation (DCA) in order to maximise the number of users supported in a traffic cell. The cell is divided in three concentric rings and in the central high signal-to-noise ratio (SNR) region 16-level star quadrature amplitude modulation (16-StQAM) is used, in the first ring differential quaternary phase shift keying (DQPSK) is invoked, while in the outer ring differential phase shift keying (DPSK) is utilised. A channel SNR of about 7, 10 and 20 dB, respectively, was required in order to maintain a bit error ratio (BER) of about 1%, which can then be rendered error-free by the binary BCH error correction codes used. A 4.7 kbps algebraic code excited linear predictive (ACELP) speech codec is favoured, which is protected by a quad-class source-sensitivity matched BCH coding scheme, yielding a total bit rate of 8.4 kbps. A GSM-like voice activity detector (VAD) controls the PRMA-assisted adaptive system, which ensures a capacity improvement of a factor of 1.78 over PRMA-aided binary schemes
Keywords :
BCH codes; algebraic codes; cellular radio; differential phase shift keying; frequency allocation; linear predictive coding; packet reservation multiple access; quadrature amplitude modulation; speech codecs; telecommunication channels; 10 dB; 16-StQAM; 16-level star quadrature amplitude modulation; 20 dB; 7 dB; 8.4 kbit/s; BER; DPSK; DQPSK; GSM-like voice activity detector; PRMA-assisted adaptive system; SNR; algebraic code excited linear prediction; binary BCH error correction codes; bit error ratio; channel SNR; channel adaptive modulation; differential phase shift keying; differential quaternary phase shift keying; packet reservation multiple access; signal-to-noise ratio; source-sensitivity matched BCH coding; speech codec; total bit rate; traffic cell;
fLanguage :
English
Publisher :
iet
Conference_Titel :
Radio Receivers and Associated Systems, 1995., Sixth International Conference on
Conference_Location :
Bath
Print_ISBN :
0-85296-643-1
Type :
conf
DOI :
10.1049/cp:19951135
Filename :
533449
Link To Document :
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