IEE Proceedings - Communications
Volume 150, Issue 4, August 2003
Volumes & issues:
Volume 150, Issue 4
August 2003
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- Author(s): D.J. Parish ; K. Bharadia ; A. Larkum ; I.W. Phillips ; M.A. Oliver
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 221 –227
- DOI: 10.1049/ip-com:20030411
- Type: Article
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Communication networks, including the Internet, support a wide range of packet-based applications. It is often necessary to know what applications are in use. Traditionally, applications were readily identified by inspection of data held in the packet header such as the destination port number. However, newer and real-time applications cannot always be detected by such a simple investigation and hence other techniques such as packet classification or deep packet analysis have been developed. Deep packet analysis however has significant problems such as its inability to operate on encrypted data packets, and its need to capture specific packets from the traffic stream. The paper considers an alternative approach to the detection of real-time applications. A search was made for a statistical fingerprint derivable from the observable traffic streams generated by such applications. This has been found to be the packet size distribution of the application, and the paper considers this statistic for a range of such applications and network conditions. A detector, based on the described approach, is presented and evaluated using real network traffic. - Author(s): A. Holt
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 228 –232
- DOI: 10.1049/ip-com:20030530
- Type: Article
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Popular World Wide Web sites can often cause congestion hot spots in the network, resulting in degradation of performance. Typically, such sites are mirrored in order to alleviate bottlenecks. This presents users of these sites with a choice of where to access their documents. Using a theoretical Web access delay model, a performance analysis is carried out which shows the effects of mirror location and communication facility speed. The analysis shows the conflict of interest between the network operator trying to optimise aggregate data rates and that of the users trying to maximise their own individual data rates. The results reflect upon the load balancing policies for optimal network performance. - Author(s): J. Liu and N. Ansari
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 233 –238
- DOI: 10.1049/ip-com:20030480
- Type: Article
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The aggressive reservation strategy in optical burst switching systems is investigated. A success probability - driven algorithm and a bandwidth-utilisation-driven algorithm are proposed to facilitate the authors' recently proposed forward resource reservation transmission scheme. The principles and the theoretical analysis of these two algorithms are presented and, their performance is compared with respect to the reservation success probability and the bandwidth usage efficiency. Simulation results have validated the algorithms and the analysis. - Author(s): F. Moraes ; N. Calazans ; C. Marcon ; D. Mesquita ; J. Palma ; V. Blauth
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 239 –243
- DOI: 10.1049/ip-com:20030589
- Type: Article
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The paper describes the design and prototyping of a telecommunication intellectual property soft core developed in the scope of an industry–academia co-operation. The soft core allows the manipulation of E1 2048 kHz 32-channel carrier information. It inserts/removes data into/from an E1 frame and multiframe structures. The soft core was fully described in VHDL, functionally validated by simulation, prototyped in FPGA platforms and certified using E1 testers. The main use of the developed soft core in the implementation of data communication equipment is to allow multiple users to share a common E1 carrier with a flexible scheme for bandwidth allocation. The main contribution of the paper is a reusable hardware module that increases performance and reduces latency of the data treatment when compared to existing commercial solutions. - Author(s): A.J. Al-Sammak ; R.L. Kirlin ; P.F. Driessen
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 244 –248
- DOI: 10.1049/ip-com:20030379
- Type: Article
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The design of a new multiuser line-coding scheme based on ideas from collaborative coding multiple access (CCMA) is presented. The new scheme yields good throughput in terms of user information bits per time slot (baud). Separate user data streams (or a single data stream demultiplexed into multiple separate streams) are combined in a binary adder channel. Trade-offs among the number of users, number of time slots per user symbol, and number of user information bits per user symbol are developed, and possible codes are tabulated. A maximum rate of 4.4 bits/baud can be achieved by using five time slots, with two symbols/user and 22 users. - Author(s): M. Albanese ; I. Rinaldi ; A. Spalvieri
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 249 –252
- DOI: 10.1049/ip-com:20030412
- Type: Article
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The authors present an analysis and the FPGA implementation of an ordered statistics decoder for the singly extended Reed–Solomon code seRS(16,14). The goal of the design is to maintain good performance while reducing computational complexity and area with respect to the maximum-likelihood decoder of the same code or a Viterbi decoder of a high-rate punctured convolutional code of comparable performance. The authors also analyse a multilevel coded modulation system based on the partition chain E8/RE8/2E8, that makes use of a rate-1/2 16-ary convolutional code at the first level and of the seRS(16,14) code at the second level. This scheme is well suited to STM1 data transmission (155.52 Mbit/s) with 28 MHz channel spacing and 256 QAM modulation. - Author(s): S.A. Charles ; E.A. Ball ; T.H. Whittaker ; J.K. Pollard
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 253 –258
- DOI: 10.1049/ip-com:20030356
- Type: Article
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A channel sounder based on correlation of a maximum-length sequence is described. The sounder is designed for the evaluation of the absolute path loss and multipath delay spread of a fixed wireless local loop channel at 5.5 GHz. The sounder achieves good performance with relatively simple hardware. There are two key issues which must be addressed: compensation for drift and offset between the local oscillators and compensation for the distortion caused by the non-ideal nature of the measurement chain. Two-stage down-conversion is used with the second stage and subsequent processing being performed in software. A novel method of allowing for local oscillator drift without the use of a hardware carrier tracking mechanism is presented. The intermediate frequency is estimated by software before second-stage demodulation. Distortion due to the measurement chain is compensated by means of a matched filter. Measurement of absolute path loss and time variance of the channel are also considered. Example results are presented. - Author(s): F. Shu ; J. Lee ; L.-N. Wu ; G.-L. Zhao
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 259 –264
- DOI: 10.1049/ip-com:20030215
- Type: Article
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Digital AM broadcasting (DAMB) channels are investigated in detail. First, the normalised ICI power of time-variant DAMB channels is calculated to determine the range of total subcarriers of an OFDM-based DAMB system. The number of subcarriers provides a base for the subsequent channel estimation. Then, two time–frequency channel estimators with real coefficients are constructed and analysed for a DAMB system based on OFDM. Finally, their BER performance is simulated in DAMB channels. In conclusion, the 1-D estimator provides a better trade-off between BER performance and computational complexity than a 2-D estimator. The low complexity of a 1-D estimator makes it suitable for use in wireless communication systems such as WLAN, DVB and so on. - Author(s): N.Y. Ermolova
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 265 –268
- DOI: 10.1049/ip-com:20030598
- Type: Article
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The extension of Bussgang's theorem for multicarrier signals states that the effect of a memoryless band-pass nonlinearity consists in an attenuation of the input signal and its corruption by additive nonlinear noise. In spite of the fact that before the fast Fourier transform (FFT) block at the receiver nonlinear noise is non-Gaussian, the Kalman filter is applied (which is known to provide the minimum mean-square estimate when the informative Gaussian signal is corrupted by additive Gaussian noise). In doing so the structure of the useful signal is taken into account as well as the relationship between the powers of the useful signal and nonlinear noise. It turns out that the procedure of Kalman filtering, as applied to the above problem, consists in the simple multiplication of the received samples by the ‘Kalman gain’. This gain can be calculated in advance because it depends only on the input signal power and the transfer characteristic of the nonlinearity. If the communication system is operated in an additive white Gaussian noise (AWGN) channel, the noise characteristics should also be taken into account when the above gain is calculated. The theoretical analysis and simulation results show that this simple procedure decreases the noise variance before the decision device and thus improves the performance of the system. - Author(s): J.P. Fonseka ; Y. Yin ; I. Korn
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 269 –274
- DOI: 10.1049/ip-com:20030380
- Type: Article
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p.
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The combined effect of imperfect magnitude and phase of fading estimates in maximal ratio combining (MRC) is analysed. Theoretical error rate bounds are derived under small estimate errors. These bounds are tested over Rayleigh and Nakagami-m fading channels with binary phase shift keying (BPSK) modulation, and verified using computer simulation. Numerical results quantify the sensitivity of MRC to errors in fading estimates. It is numerically demonstrated that for BPSK, MRC is more sensitive to errors in phase estimates than to errors in magnitude estimates. - Author(s): M. Riediger and E. Shwedyk
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 275 –279
- DOI: 10.1049/ip-com:20030410
- Type: Article
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The authors compare different finite-state Markov channel (FSMC) models used to approximate the Rayleigh fading channel. The criterion used to compare the different Markov models is the error performance of corresponding FSMC receivers performing joint maximum a posteriori (MAP) sequence detection and channel estimation, where the sufficient statistics are obtained from the Jakes–Clarke fading channel. To put the results in perspective, the results of these Markov receivers are compared with those of a Kalman filtering receiver based on an ARMA model of the Jakes–Clarke fading channel. There is a moderate improvement in Markov receiver performance when based on a second-order model compared to a first-order model, and the number of Markov states is normalised by model order. This does not justify a second-order model, however, as the complexity of implementing a Markov receiver increases exponentially with model order. Furthermore, the error performance floor of a first-order Markov receiver increases linearly with the number of Markov states. Based on the performance of Markov receivers, it is concluded that a first-order Markov model is sufficient for representing the memory of the fading channel. - Author(s): J. Thomas
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 280 –286
- DOI: 10.1049/ip-com:20030360
- Type: Article
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Multipoint-to-point code division multiaccess (CDMA) networks have been the primary focus in multiuser interference (MUI) suppression research, where the recent development of the turbo minimum mean square error (MMSE) detector promises near interference-free performance at an acceptable complexity. The complementary case, namely point-to-multipoint, i.e. broadcast transmission is increasingly becoming more important since traffic on the forward link is likely to increase substantially, particularly for data, in the near future. In (synchronous) broadcast with orthogonal spreading, e.g. the forward link in a single-cell configuration such as a wireless local area network (WLAN), MUI arises only due to the frequency selectivity of the propagation medium. MMSE and turbo MMSE equalisation based receivers are developed. They are observed to significantly mitigate MUI in a WLAN's forward link, especially with the turbo configuration comprising a linear MMSE front-end equaliser in early iterations and a decision feedback MMSE front-end equaliser in later iterations. The relevance of such approaches to the multicell CDMA forward link is also discussed in relation to recent trends that tie pricing to the quality of service provided to the user. - Author(s): K. Yang ; A.S. Madhukumar ; F. Chin
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 287 –292
- DOI: 10.1049/ip-com:20030479
- Type: Article
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A two-dimensional multistage interference cancellation scheme for the uplink transmission of a high-speed single carrier cyclic prefix-assisted CDMA system is proposed. In this two-dimensional scheme, equalisation and interference regeneration is performed in the frequency domain while data decision and interference subtraction is done in the time domain. Two variations of this scheme are proposed. They are a serial multistage interference cancellation scheme and a hybrid scheme combining the serial and parallel multistage interference cancellation methods. The second scheme has considerable reduction in the processing delay over the first one at the cost of higher hardware complexity. The performance of both schemes is evaluated by extensive computer simulations. - Author(s): S.A. Ghorashi ; H.K. Cheung ; F. Said ; A.H. Aghvami
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 293 –297
- DOI: 10.1049/ip-com:20030357
- Type: Article
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In a mixed cell architecture, in which cells of different sizes co-exist, the interaction between layers has a major impact on radio resource management. Such interaction can be in terms of directing the traffic overflow from the lower layer to the overlaying layer (overflow-sensitive handover) and/or of classifying the users based on their speed (speed-sensitive handover). In this study, the implementation of a hybrid speed/overflow-sensitive layer assignment strategy in a CDMA-based hierarchical cell structure (HCS) network is studied and its impact on the signalling load and capacity of the system is compared with three other assignment strategies. A new approach to controlling the signalling load in such a network is also proposed. The results indicate that by using the proposed strategy, the signalling load can be controlled even in an area in which the mobile stations have a time-varying speed distribution. - Author(s): B. Fan ; R. Tafazolli ; B.G. Evans
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, p. 298 –303
- DOI: 10.1049/ip-com:20030354
- Type: Article
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A novel radio connection management scheme for QoS-provisioning transport of ATM traffic over a broadband satellite link is presented. The new scheme effectively manages the air interface connections via separation of connection types, establishing QoS-based connections and deploying an efficient communication mapping and lateral scheme. The scheme optimises in respect of cell loss rate for individual services and minimises bandwidth. Evaluation of the scheme is presented for a GEO multimedia satellite system. - Author(s): Y. Wu
- Source: IEE Proceedings - Communications, Volume 150, Issue 4, page: 304 –304
- DOI: 10.1049/ip-com:20030764
- Type: Article
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Using packet size distributions to identify real-time networked applications
Theoretical performance analysis of mirroring World Wide Web sites
Aggressive resource reservation for OBS systems
Design and prototyping of an E1 Drop_Insert soft core
Design of a new time orthogonal multiuser line code
Analysis, implementation and application of an ordered statistics decoder for the seRS(16,14) code
Channel sounder for 5.5 GHz wireless channels
Time – frequency channel estimation for digital amplitude modulation broadcasting systems based on OFDM
Kalman filter application for mitigation of nonlinear effects in multicarrier communication systems
Sensitivity to fading estimates in maximal ratio combining
Communication receivers based on Markov models of the fading channel
Multiuser interference suppression in wideband broadcast CDMA networks
Novel two-dimensional multistage interference cancellation scheme for uplink transmission of single carrier cyclic prefix-assisted CDMA system
Performance of a CDMA-based HCS network with hybrid speed/overflow-sensitive handover strategy
Connection management for broadband mobile satellite systems
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