Digital cellular mobile radio links and networks
Digital cellular mobile radio links and networks
Aspects of radio and fixed networks for high capacity digital mobile radio systems employing microcells are investigated. For the radio network, the system performance is studied in terms of bit error rates (BERs), channel signal-to-noise ratios, and carrier-to-interference ratios. Theoretical expressions are derived of BER performance of continuous phase modulation (CPM) schemes using coherent minimum shift keying (MSK) detection in the presence of multiple cochannel interferers, for radio transmissions over additive white Gaussian noise (AWGN) and Rayleigh fading channels. Theoretical and Monte Carlo simulations of Gaussian minimum shift keying (GMSK) modulation showed that in an AWGN channel, the BER increases with the number of cochannel interferers. However, for Rayleigh fading channels the BER performance was substantially independent of the number of cochannel interferers. Using our theoretical expressions, the BER performance of a slow frequency hopping multiple access system employing concatenated Reed-Solomon (RS) coding and slow frequency hopping was evaluated for different mobile radio channels. The Monte Carlo methodology was also used to simulate the one-bit differential GMSK (DGMSK) detector. The BER performance for transmission over AWGN and Rayleigh fading channels in the presence of an interferer was examined. The performance for the two-ray Rayleigh fading channel was also simulated. A feasibility study of quaternary GMSK using one-bit DGMSK detection, revealed that schemes with low values of normalised bandwidth gave erroneous decisions, even in the ideal noiseless condition, due to excessive intersymbol interference. We were able to significantly improve the BER performance of the differential detector using decision feedback equalizers to partially remove the intersymbol interference. An experimental time division multiple access (TDMA) radio testbed incorporating an RS (12,8)4 channel codec, a one-raised cosine frequency shift keying modulator, and a discriminator was constructed. The long-term and short-term characteristics of the received signal strength in building microcells were investigated using this testbed. From the line-of-sight (LOS) experiments along a corridor, the propagation exponent α was 1.3 and the signal exhibited a Rician pdf where the ratio of the power of the direct to the scattered rays was 3.4 dB. When the transmitter and receiver were separated by a floor, α became 3.4. The signal strength in non-LOS situations had Rayleigh statistics. A local area network (LAN) with a double-loop topology using random slot seizures linked the base-stations (BSs) to their group-station. Mean value analysis showed that while the single loop LAN had a wide range of queueing delays at its BSs, the double loop LAN achieved approximately the same delay at all the BSs. A TDMA blocking formula was derived for loss call cleared systems and was compared with the Erlang-B formula. Our investigations have ranged from CPM modulation, slow frequency hopping systems, propagation measurements in buildings, through to an optical LAN for linking microcellular mobile BSs to the wide area network. We trust that our results provide a significant contribution to the understanding and the design of microcellular mobile radio networks.
University of Southampton
1989
Ko, Yiu Fai
(1989)
Digital cellular mobile radio links and networks.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Aspects of radio and fixed networks for high capacity digital mobile radio systems employing microcells are investigated. For the radio network, the system performance is studied in terms of bit error rates (BERs), channel signal-to-noise ratios, and carrier-to-interference ratios. Theoretical expressions are derived of BER performance of continuous phase modulation (CPM) schemes using coherent minimum shift keying (MSK) detection in the presence of multiple cochannel interferers, for radio transmissions over additive white Gaussian noise (AWGN) and Rayleigh fading channels. Theoretical and Monte Carlo simulations of Gaussian minimum shift keying (GMSK) modulation showed that in an AWGN channel, the BER increases with the number of cochannel interferers. However, for Rayleigh fading channels the BER performance was substantially independent of the number of cochannel interferers. Using our theoretical expressions, the BER performance of a slow frequency hopping multiple access system employing concatenated Reed-Solomon (RS) coding and slow frequency hopping was evaluated for different mobile radio channels. The Monte Carlo methodology was also used to simulate the one-bit differential GMSK (DGMSK) detector. The BER performance for transmission over AWGN and Rayleigh fading channels in the presence of an interferer was examined. The performance for the two-ray Rayleigh fading channel was also simulated. A feasibility study of quaternary GMSK using one-bit DGMSK detection, revealed that schemes with low values of normalised bandwidth gave erroneous decisions, even in the ideal noiseless condition, due to excessive intersymbol interference. We were able to significantly improve the BER performance of the differential detector using decision feedback equalizers to partially remove the intersymbol interference. An experimental time division multiple access (TDMA) radio testbed incorporating an RS (12,8)4 channel codec, a one-raised cosine frequency shift keying modulator, and a discriminator was constructed. The long-term and short-term characteristics of the received signal strength in building microcells were investigated using this testbed. From the line-of-sight (LOS) experiments along a corridor, the propagation exponent α was 1.3 and the signal exhibited a Rician pdf where the ratio of the power of the direct to the scattered rays was 3.4 dB. When the transmitter and receiver were separated by a floor, α became 3.4. The signal strength in non-LOS situations had Rayleigh statistics. A local area network (LAN) with a double-loop topology using random slot seizures linked the base-stations (BSs) to their group-station. Mean value analysis showed that while the single loop LAN had a wide range of queueing delays at its BSs, the double loop LAN achieved approximately the same delay at all the BSs. A TDMA blocking formula was derived for loss call cleared systems and was compared with the Erlang-B formula. Our investigations have ranged from CPM modulation, slow frequency hopping systems, propagation measurements in buildings, through to an optical LAN for linking microcellular mobile BSs to the wide area network. We trust that our results provide a significant contribution to the understanding and the design of microcellular mobile radio networks.
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Published date: 1989
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Local EPrints ID: 461606
URI: http://eprints.soton.ac.uk/id/eprint/461606
PURE UUID: caa38c7b-12a8-4327-8f90-155e47d9f1c1
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Date deposited: 04 Jul 2022 18:50
Last modified: 04 Jul 2022 18:50
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Author:
Yiu Fai Ko
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