IEE Proceedings - Communications
Volume 148, Issue 2, April 2001
Volumes & issues:
Volume 148, Issue 2
April 2001
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- Author(s): A. Al-Hammadi and J. Schormans
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 57 –62
- DOI: 10.1049/ip-com:20010067
- Type: Article
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p.
57
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The authors show that in a prioritised switch it is necessary to monitor the buffers to be controlled as well as higher priority buffers. Furthermore, it is shown that the fuzzy scheme in a time-prioritised ATM switch gives lower cell loss and delay, and higher utilisation when compared with the conventional explicit binary scheme. - Author(s): M. Saleh and M. Atiquzzaman
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 63 –69
- DOI: 10.1049/ip-com:20010159
- Type: Article
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p.
63
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The authors have developed an exact model to evaluate the performance of multistage interconnection networks using internal shared buffering. The model assumes a general output distribution which allows the study of the performance of such networks under any desired output distribution. Among many possible output distributions, uniform, hot-spot and favourite distributions are studied. The model is validated by the comparison of some numerical results with event simulation results which are shown to be very close to the model. - Author(s): S.-J. Yoo and S.-D. Kim
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 70 –76
- DOI: 10.1049/ip-com:20010069
- Type: Article
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70
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An efficient policing mechanism for Markov model-based traffic descriptors of VBR MPEG video traffic is proposed. A VBR video sequence is described by a set of traffic descriptors using a scene-based Markov model for effective resource allocation and accurate QoS prediction. To monitor the input traffic from the source, the authors have defined a set of a limited number of representative monitoring parameters and also defined an exponential bounding function in order to accommodate dynamic behaviour. The simulation results show that the proposed policing mechanism for Markovian traffic descriptors monitors sophisticated traffic, such as MPEG video, effectively and also protects network resources from both malicious and abnormally behaved traffic. - Author(s): S.W. Lei and V.K.N. Lau
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 77 –80
- DOI: 10.1049/ip-com:20010071
- Type: Article
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77
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The authors propose a novel interleaving technique, namely adaptive interleaving, which can break the bursty channel errors more effectively than traditional block interleaving. This new scheme resequences the transmitted symbols adaptively, according to the instantaneous subcarrier channel state information. In this way, the bursty errors introduced by the channel can be broken more effectively, thus a better BER performance can be achieved. This technique is well suited to OFDM systems, because the CSI values of the whole frame could be estimated at the same instant when transmitted symbols are framed in the frequency dimension. Computer simulation shows that significant SNR gains can be achieved, compared with traditional block interleaving. - Author(s): J.H. Lee
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 81 –85
- DOI: 10.1049/ip-com:20010212
- Type: Article
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p.
81
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The author proposes a persistent reservation protocol in a wavelength division multiplexing (WDM)-based local network using a passive star topology. With this protocol, once a node reserves a data channel, the node persistently uses the channel until its message is completely transmitted. Therefore, the protocol needs only one tuning time for a node to begin to transmit its message, which reduces deterioration of throughput due to tuning overhead. The proposed protocol can efficiently support variable-length messages. The network can accommodate a variable number of nodes and can operate independently of any change of the number of nodes. Hence, any ‘new’ node can join the network at anytime without network re-initialisation. Moreover, with the protocol, data channel and destination conflicts can be avoided. Throughput–delay characteristics are analysed with a finite population model, and are verified by simulation results. - Author(s): Y.-K. Kwok and V.K.N. Lau
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 86 –94
- DOI: 10.1049/ip-com:20010160
- Type: Article
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p.
86
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Multiple access control (MAC) protocols for a wireless ATM network are required to handle the diverse traffic characteristics in CBR, VBR and ABR data. Considerable research effort expended in tackling the problem has resulted in a myriad of MAC protocols. While each protocol is individually shown to be effective by the respective designers, it is unclear how these different protocols compare with each other on a unified basis. Seven recently proposed TDMA-based MAC protocols for integrated wireless data and voice services are quantitatively compared. Using a time-varying channel model, the protocols are evaluated by simulations. It is found that exploiting the synergy between the MAC and physical layers can lead to a higher performance. - Author(s): G. Fairhurst ; N.K.G. Samaraweera ; M. Sooriyabandara ; H. Harun ; K. Hodson ; R. Donadio
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 95 –99
- DOI: 10.1049/ip-com:20010130
- Type: Article
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The next generation of broadband satellites will offer high-capacity digital services to provide high-speed Internet access at low cost, using the terrestrial dial-up infrastructure to provide a return path. The resulting service exhibits significant bandwidth asymmetry and when TCP is used a phenomenon termed ‘ACK congestion’ is observed. TCP behaviour in an asymmetric network using simulations and both live and emulated test bed experiments is studied. A set of existing techniques to restore performance are analysed and a new technique called ‘ACK compaction’ is presented and analysed. Although the study focuses on one technology most discussions will be common to any bandwidth-asymmetric network. - Author(s): W. Ren ; J. Ward ; S. Hodgart ; M. Sweeting
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 100 –104
- DOI: 10.1049/ip-com:20010273
- Type: Article
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p.
100
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The capture effect can improve throughput of random multiple access protocols. An exact model for evaluating the capture effect is proposed for noncoherent FSK demodulation (NCFSK) under a slow fading assumption. This model takes into account the bit decision process of the NCFSK demodulator in the presence of both co-channel interference and noise. An approximate and simplified model is also presented for comparison. Additionally, a Gaussian assumption-based model is derived, which turns out to be too pessimistic for slow fading channels. The capture effect is investigated by means of the proposed exact model in a low Earth orbit satellite channel. The result shows that a relatively large link margin can result in a large capture probability, and consequently benefit slotted ALOHA protocols with a substantial throughput improvement. - Author(s): D.D.N. Bevan ; V.T. Ermolayev ; A.G. Flaksman
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 105 –111
- DOI: 10.1049/ip-com:20010175
- Type: Article
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p.
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A novel technique to calculate the BER of a q-branch coherent receiver for an antipodal binary-modulated transmitted signal is described. When the amplitude fading on each branch is Rician and independent, the BER is calculated through simplification of a (q + 1)-dimensional integral down to a one-dimensional integral, which is readily amenable to numerical evaluation. For systems where the Rician fading on the branches is dependent, it is shown that the problem can be transformed to an independent-fading problem using the technique of ‘spatial whitening’. The authors apply the results to construct diversity contours for the analysis of dependent Rician-faded channel data. - Author(s): J. Zhang and V. Aalo
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 112 –118
- DOI: 10.1049/ip-com:20010267
- Type: Article
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p.
112
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The performance of a multicell DS-CDMA cellular system with base station diversity is studied taking into consideration the effects of imperfect power control, multipath fading, shadowing and the dependence of propagation losses to a different base station from a mobile user. It is assumed that a mobile user is connected to the base station that provides the least attenuation among a set of closest uniformly correlated base stations. Analytical expressions are derived for the average probability of error of binary phase shift keying modulated signals for both the reverse link and the forward link. The channel is assumed to undergo correlated lognormal shadowed Rayleigh fading. Analytical results show that base station diversity significantly improves system performance. - Author(s): A.C. McCormick ; P.M. Grant ; J.S. Thompson
- Source: IEE Proceedings - Communications, Volume 148, Issue 2, p. 119 –124
- DOI: 10.1049/ip-com:20010272
- Type: Article
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p.
119
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A novel interference cancellation detector, which combines an initial phase of cancelling one or more users per iteration depending on the tentative decision metrics, followed by maximum likelihood detection for the last few users, is proposed for multi-carrier CDMA uplink communication. Simulation results compare the system with a number of other multi-user detection receivers for an uplink multipath multi-user problem. The number of iterations and computation complexity are compared with a successive interference cancellation approach. The influence of the near–far effect and of poor channel estimation is also investigated.
Fuzzy congestion controller in a prioritised ATM switch
Exact model for analysis of shared buffer ATM switches with arbitrary traffic distribution
Policing method for Markovian traffic descriptors of VBR MPEG sources over ATM networks
Adaptive interleaving for OFDM in TDD systems
Persistent reservation protocol for variable-length messages in WDM-based local networks
Performance evaluation of multiple access control schemes for wireless multimedia services
Performance issues in asymmetric TCP service provision using broadband satellite
Exact evaluation of capture effect under NCFSK demodulation
Coherent multichannel reception of binary modulated signals with dependent Rician fading
Performance analysis of a multicell DS-CDMA system with base station diversity
Hybrid uplink multi-carrier CDMA interference-cancellation receiver
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