IEE Proceedings - Communications
Volume 142, Issue 4, August 1995
Volumes & issues:
Volume 142, Issue 4
August 1995
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- Author(s): B. Honary ; G. Markarian ; M. Darnell
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 201 –209
- DOI: 10.1049/ip-com:19952037
- Type: Article
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p.
201
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The authors introduce a new simple encoding technique which allows the design of a wide variety of linear block codes. They present a number of examples in which the most widely used codes (Reed-Muller, Hamming, Golay, optimum etc.) have been designed. They also introduce a novel trellis design procedure for the proposed codes. It is shown that the trellises of the designed codes are similar to the trellises of coset codes and allow low complexity soft maximum likelihood decoding. - Author(s): P.Z. Fan and M. Darnell
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 210 –215
- DOI: 10.1049/ip-com:19952005
- Type: Article
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210
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It is well known that Frank sequences are a class of polyphase sequences with ideal periodic autocorrelation functions. It is shown that some of the Frank sequences also have very favourable aperiodic autocorrelations. For Frank sequences of length L=q2, there exist two sequences whose maximum out-of-phase aperiodic autocorrelation values are asymptotic to q/ pi as q tends to infinity. If L is odd, there exist two sequences whose maximum out-of-phase aperiodic autocorrelation values are bounded by 2 square root ((2)(q/ pi )). - Author(s): B. Farhang-Boroujeny
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 216 –220
- DOI: 10.1049/ip-com:19952054
- Type: Article
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p.
216
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A new data receiver structure is proposed which removes sinusoidal phase jitters (SPJ) present on the received signals prior to their equalisation. It is shown that under the conditions that the SPJ is excessive, the proposed scheme improves receiver performance significantly when compared with the conventional methods which cancel the SPJ after equalisation of the received signal. This improvement is achieved at the cost of doubling the complexity of the receiver. - Author(s): P. Larsson
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 221 –226
- DOI: 10.1049/ip-com:19952058
- Type: Article
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p.
221
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For a single-loop frequency synthesiser, there is a trade-off between time-to-lock and output phase-noise. To lock a PLL quickly, a high natural frequency ( omegan) is required, while a low omegan is necessary to obtain good jitter damping. The author presents a technique to reduce the time to lock of a frequency synthesiser PLL without changing the jitter transfer function. - Author(s): B.J. Tye ; A. Dagiuklas ; M. Ghanbari
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 227 –232
- DOI: 10.1049/ip-com:19952036
- Type: Article
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p.
227
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A method for optimising the usage parameter control (UPC) of video services in an ATM network is proposed. The video encoder uses a sliding window for its maximum network utilisation without exceeding the declared bit rate at the call setup. At video scene cuts, where the peak bit rates are generated, the coder limits its generated bit rate through a leaky bucket mechanism. The impacts of optimum UPC on both coding and network performance are investigated. It is shown that for video sequences with scene cuts there is an optimum value of peak-to-mean ratio where the network performance is optimised. - Author(s): C.I. Ani ; R. Ahmad ; F. Halsall
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 233 –237
- DOI: 10.1049/ip-com:19952032
- Type: Article
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p.
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The statistical mode of operation of asynchronous-transfer-mode (ATM) networks can lead to congestion which, in turn, leads to a degradation in the quality of service (QOS) of calls. Normally, congestion manifests itself by overflow in the input or output controllers of switches. An outstanding research issue relating to ATM networks, therefore, is resource management; i.e. determining the optimum network resources, in terms of link bandwidth and buffer capacity in switches, that are required for a call which guarantees a defined QOS, even under high-network-loading conditions. The two most important QOS parameters associated with a cell are cell-loss rate and cell-delay variation. In practice, the parameters are interrelated and make conflicting demands on the available resources. Video services, for example, are sensitive to both parameters and hence it is necessary to consider the combined parameters when allocating resources for such services. The paper describes a new method for deriving the optimum resources required for video-related services in an ATM-based private network to guarantee specific QOS requirements. - Author(s): E.A. Medova
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 238 –242
- DOI: 10.1049/ip-com:19951933
- Type: Article
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p.
238
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Wavelength-division multiplexing adds one more dimension to routing in telecommunication networks through identification of origin-destination (OD) pairs by wavelength assignment. However, only partial logical direct connectivity is possible owing to the availability of a limited number of wavelengths. One of the existing solutions to this problem is based on fixed wavelength assignment and multihop OD pair connections. The resulting network model involves a multiplicity of traffic flows corresponding to the number of wavelengths used, with simultaneous pairwise OD traffic requirements. This "multicommodity network flow" problem is well known in combinatorial optimisation as a hard problem in terms of its computational complexity. A two-stage heuristic approach is investigated using existing network flow algorithms to achieve near-optimal network capacity allocation through consideration of the number of wavelengths, the topology and the possible traffic pattern in a given network. The resulting computations illustrate that the wavelength assignment problem at the first stage depends highly on the pattern of projected traffic and that more complex routing algorithms than shortest-path produced routings with a lower number of wavelength translations and more uniformly distributed traffic loads. - Author(s): D.A. Hill and E.B. Felstead
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 243 –249
- DOI: 10.1049/ip-com:19952059
- Type: Article
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p.
243
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The laboratory performance of four spread-spectrum (SS) detectors (full-band and partial-band radiometers, chip-rate detector (CRD) and squaring carrier detector) was measured for direct sequence (DS) and frequency hop (FH) SS signals, FH/DS hybrids, and time hop (TH) DS signals. Probability of detection as a function of input SNR for a constant false-alarm rate was measured for numerous combinations of SS waveform and detector. Theories were compiled from the literature and extended as necessary to provide a unified theoretical description. The results usually agreed with theory to within 1 dB. A constant-false-alarm-rate method was used to reduce the drift problem of radiometers. The fact that chip-rate and squaring-carrier detectors have a much reduced drift problem was confirmed. It is concluded that the four SS detectors used are relatively simple and inexpensive devices with laboratory detection performance close to theoretical. - Author(s): F. Solms ; P.G.W. van Rooyen ; J.S. Kunicki
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 250 –254
- DOI: 10.1049/ip-com:19951928
- Type: Article
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p.
250
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The authors show that the Gauss-quadrature rule (GQR) method, which is widely used in performance evaluation of digital communication systems, fails under certain frequently encountered conditions. The maximum entropy method (MEM), on the other hand, continues to give reliable results for most of these problems. In cases where the MEM becomes numerically unstable before it achieves sufficient accuracy the authors incorporate a prior estimate of the error probability distribution function (PDF) in the minimum relative entropy (MREM) algorithm in order to improve on the accuracy of their results. They compare the MEM and MREM results to those obtained with the GQR method for AWGN channels with single Rayleigh-path-faded BPSK signals to the P-branch diversity systems. In both cases the GQR method fails for large values of the SNR,. - Author(s): X.H. Chen and J. Oksman
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 255 –262
- DOI: 10.1049/ip-com:19952034
- Type: Article
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p.
255
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The code protocol (the R3 protocol) for DS/SSMA wireless data networks is examined further and an analytical method is given of studying its delay and throughput bounds. In this protocol the communication-initiation process terminals uses handshaking packets (REQ and ACK packets), followed by the data packet. Different chip rates are utilised in transmissions of different packets to avoid destructive collisions between them. All packets are encoded by receiver-based codes. It is shown that the throughput lower bound of this protocol is about 0.24 when the normalised offered channel-traffic load is equal to one, and that the protocol offers stability to the network even at a very high offered channel-traffic load. - Author(s): F. Adachi
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 263 –270
- DOI: 10.1049/ip-com:19952061
- Type: Article
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p.
263
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The reduced-state Viterbi algorithm (VA), with feedback incorporated into the structure of path metric computations is presented for the differential detection of M-ary DPSK signals. The number of states in the trellis of the VA is reduced to M, and the phase reference used for differential detection is estimated recursively for each state in the trellis, along the surviving path ending in each state. The proposed differential detection is called reduced-state Viterbi differential detection (RSV DD). The most simple form of RSV DD, decision feedback DD (DF DD), is also derived. It allows only a single path to survive, so that a symbol-by-symbol decision is made. The BER performances possible with the proposed RSV DD and DF DD schemes are evaluated by means of computer simulations for 4DPSK transmission over AWGN and Rayleigh fading channels. - Author(s): S.V. Maric
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 271 –273
- DOI: 10.1049/ip-com:19952060
- Type: Article
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p.
271
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The author discusses the problem of constructing frequency hopping patterns for use in TDMA-FDMA cellular systems that employ frequency diversity to minimise bursty errors occurring due to the fading channel. Conditions under which two frequency and time channels fade independently in mobile fading channels are reviewed. The construction of a family of effective frequency hop sequences for achieving maximum diversity is given. The construction is based on the theory of linear congruences, and the number of sequences for every integer is established. It is shown that when sequences are constructed using prime numbers they are also orthogonal. Examples of constructed sequences applicable to the GSM cellular system are given. - Author(s): D.W. Bennett ; R.J. Wilkinson ; P.B. Kenington
- Source: IEE Proceedings - Communications, Volume 142, Issue 4, p. 274 –280
- DOI: 10.1049/ip-com:19952055
- Type: Article
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p.
274
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The demand for increased capacity in cellular and other radio networks has led to the development of more flexible base stations. As a result, the high-level combining of multiple amplifiers, with the stringent frequency planning constraints which this imposes, has been supplanted by a single multichannel linear amplifier in an increasing number of systems. The specification of such systems is a complicated issue, owing to the complex nature of the combined signal which they are required to amplify. The authors present a statistical analysis of the peak envelope power of a multicarrier signal, incorporating a variety of modulation schemes, and show that for a large number of channels, significant savings in the amplifier power rating may be made, resulting in decreased hardware and operating costs for multichannel base stations.
Low-complexity trellis decoding of linear block codes
Aperiodic autocorrelation of Frank sequences
Pre-equaliser cancellation of sinusoidal phase jitter
Reduced pull-in time of phase-locked loops using a simple nonlinear phase detector
Proposed UPC meeting both packet video and network goals
Methodology for derivation of network resources to support video-related services in ATM-based private wide-area networks
Network flow algorithms for routing in networks with wavelength division multiplexing
Laboratory performance of spread spectrum detectors
Maximum entropy and minimum relative entropy in performance evaluation of digital communication systems
Performance-bound analysis of the new DS/SSMA protocol for wireless data networks
Reduced-state Viterbi differential detection using a recursively estimated phase reference for M-ary DPSK
Construction of optimal frequency hopping sequences for minimising bit errors in selective fading channels characteristic to digital cellular systems
Determining the power rating of a multichannel linear amplifier
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