Intelligent multimode TDMA systems for PCS
Intelligent multimode TDMA systems for PCS
The radio interfaces required for third generation personal communications networks (PCNs), and the attributes of an intelligent multimode portable to operate within the PCN are investigated. After discussing key factors that determine spectral efficiency defined as Erlang/MHz/km2 in PCNs, we conclude that cell size is the most influential factor. In a network primarily carrying speech traffic, the speech encoding rate is the next most significant factor in determining spectral efficiency. Other factors of importance are co-channel interference tolerance, modulation speed, and channel coding power. After the identification of these key parameters, radio link subsystems are examined, particularly modulation schemes and source and channel codecs. Multiple access issues are then addressed with an emphasis on time division multiple access (TDMA). We consider various dynamic and adaptive TDMA schemes. Packet reservation multiple access (PRMA) using voice activity detection doubles the spectral efficiency compared to TDMA schemes that do not make use of silences in speech. Multilevel modulation, where the number of levels adapts to the mean path loss, results in substantial gains in spectral efficiency, and when combined with PRMA the number of calls for a given bandwidth triples compared to conventional TDMA. Next the benefits of deploying microcells on spectral efficiency are examined. As an example, the GSM and DCS1800 networks are compared and it is shown that the spectral efficiencies increased from 2.55 to 7.9 E/MHz/km2 for GSM and from 3.15 to 15.2 E/MHz/km2 for DCS1800 when microcells are added to a macrocellular network.
A theoretical discussion of the benefits of dynamic channel allocation (DCA) and adaptive modulation in a cellular system follows. DCA yields a doubling in capacity over fixed channel allocation (FCA), and adaptive modulation provides an increase of capacity over a non-adaptive binary scheme for the same interference tolerance of up to 97%. An analysis reveals that the gains of DCA and adaptive modulation are not additive when they are used to reduce cluster size.
University of Southampton
Williams, John Edward Brunton
1996
Williams, John Edward Brunton
Williams, John Edward Brunton
(1996)
Intelligent multimode TDMA systems for PCS.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The radio interfaces required for third generation personal communications networks (PCNs), and the attributes of an intelligent multimode portable to operate within the PCN are investigated. After discussing key factors that determine spectral efficiency defined as Erlang/MHz/km2 in PCNs, we conclude that cell size is the most influential factor. In a network primarily carrying speech traffic, the speech encoding rate is the next most significant factor in determining spectral efficiency. Other factors of importance are co-channel interference tolerance, modulation speed, and channel coding power. After the identification of these key parameters, radio link subsystems are examined, particularly modulation schemes and source and channel codecs. Multiple access issues are then addressed with an emphasis on time division multiple access (TDMA). We consider various dynamic and adaptive TDMA schemes. Packet reservation multiple access (PRMA) using voice activity detection doubles the spectral efficiency compared to TDMA schemes that do not make use of silences in speech. Multilevel modulation, where the number of levels adapts to the mean path loss, results in substantial gains in spectral efficiency, and when combined with PRMA the number of calls for a given bandwidth triples compared to conventional TDMA. Next the benefits of deploying microcells on spectral efficiency are examined. As an example, the GSM and DCS1800 networks are compared and it is shown that the spectral efficiencies increased from 2.55 to 7.9 E/MHz/km2 for GSM and from 3.15 to 15.2 E/MHz/km2 for DCS1800 when microcells are added to a macrocellular network.
A theoretical discussion of the benefits of dynamic channel allocation (DCA) and adaptive modulation in a cellular system follows. DCA yields a doubling in capacity over fixed channel allocation (FCA), and adaptive modulation provides an increase of capacity over a non-adaptive binary scheme for the same interference tolerance of up to 97%. An analysis reveals that the gains of DCA and adaptive modulation are not additive when they are used to reduce cluster size.
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Published date: 1996
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Local EPrints ID: 459930
URI: http://eprints.soton.ac.uk/id/eprint/459930
PURE UUID: 5b932ce5-d16f-4a7c-a11c-8b63aacb36a7
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Date deposited: 04 Jul 2022 17:28
Last modified: 04 Jul 2022 17:28
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Author:
John Edward Brunton Williams
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