摘要:

AbstractThe present study is devoted to multihop Metropolitan Area Network architectures characterized by some buffer capacity at the nodes and routing algorithm slightly more complex than those already present in the literature. A new adaptive routing algorithm and a new buffer management scheme are presented, and their performance are compared to that of the best algorithms known in the literature. Both the new proposals exhibit significant improvements in throughput and delay with respect to the older ones, for various MAN topologies, sizes and buffer dimensions. These results, which in some cases are very close to the theoretical optimum, are achieved with an implementation complexity well within the limits of present day technology.

ISSN:1124-318X    

DOI:10.1002/ett.4460130302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractIn this paper, performance formulae for a queue serving Gaussian traffic are presented. The main technique employed is motivated by a general form of Schilder's theorem, the large deviation result for Gaussian processes. Most probable paths leading to a given buffer occupancy are identified. Special attention is given to the case where the sample pams of die Gaussian process are smooth. The performance approximations are compared with known analytical results or by means of simulation. The approximations appear to be surprisingly accurate.

ISSN:1124-318X    

DOI:10.1002/ett.4460130303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractAnalyzing and estimating the cell loss probability in an ATM multiplexer is one of the most important problems concerning traffic control and resource management in an ATM‐based B‐ISDN. In this paper, an extension of the discrete fluid‐flow technique is proposed to calculate the cell loss probability of an ATM multiplexer fed by a 2‐state MMDP source. This technique is also used to analyze and estimate the cell loss performance of an ATM multiplexer loaded with homogeneous On‐Off sources. Numerical calculation and simulation results indicate that the method is both accurate and computationally

ISSN:1124-318X    

DOI:10.1002/ett.4460130304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractPhase noise could be the major source of performance degradation in low cost low bit‐rate digital systems operating in the millimeter wavelength band. A general model considers the phase noise as the sum of several components, namely a white phase noise, a white frequency noise and a flicker frequency noise. All these components are taken into account in the evaluation of error probability in a DPSK receiver and are compared in terms of performance degradatio

ISSN:1124-318X    

DOI:10.1002/ett.4460130305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractThis paper presents a nonlinear sub‐optimum receiver structure for DS‐CDMA. We also draw attention to the nonlinear separation problem in a DS‐CDMA system and suggest me use of ideas known in the field of partem recognition. We visualise the separation problem and the decision boundaries of different receiver structures, which in return give reasons for each receiver's performance. The proposed receiver structure is based upon the radial basis function (RBF) network. Techniques from pattern recognition are exploited to reduce the RBF complexity for mulupath scenarios, for example the use of the Mahalanobis distance measure. The presented RBF receiver has significantly less complexity (in terms of centres or neurons) than the optimum RBF receiver through the use of super centres, and outperforms Verdu's det

ISSN:1124-318X    

DOI:10.1002/ett.4460130306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractThis paper consists of three parts. In the first one, we present a statistical analysis of experimental MPEG video sources and we discuss some modeling issues relevant to the performance evaluation of a queuing system loaded with such bit streams. In the second one, we propose a modeling approach (basic model) that considers the particular structure of MPEG streams and gives accurate results in a well‐defined set of the queuing system parameters. In the third part, we introduce an extension of the basic model to take into account Long Range Dependences (LRD). This extension enlarges the range of applicability of the basic model. Our results show that the impact on the performance of the particular structure of MPEG sequences and the relevant bit rate distribution is always significant, while the impact of long term correlations is important only for large buffer sizes and high loads. These cases do not correspond often to realistic scenarios. The proposed model is validated with simulation results produced by using many experimental video sequences (both MPEG1 and MPEG2

ISSN:1124-318X    

DOI:10.1002/ett.4460130307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractIn this paper, successive interference cancellation (SIC) scheme is proposed for a multicarrier DS/CDMA system and its performance is analyzed in a Rayleigh fading channel. The SIC scheme is employed to mitigate performance degradation due to multiple access interference (MAI) coupled with near‐far problem. Bit error probability of the proposed system is derived for maximal‐ratio and equal‐gain combining schemes of subcarrier signals, respectively. From numerical results, it is Shown that the proposed system achieves significant performance improvement over a conventional multicarrier DS/CDMA system. The proposed system can find application in multicarrier DS/CDMA systems for high‐rate data s

ISSN:1124-318X    

DOI:10.1002/ett.4460130308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractData in Synchronous Digital Hierarchy (SDH) networks may be routed, managed, and regulated bydigital cross‐connect systems(DCSs). The adequacy and performance of current and proposed DCSs are determined through simulations, which require realistic connection requests ortraffic.This work entailed the creation and analysis of a traffic generation algorithm for SDH DCSs. The algorithm accepts any valid configuration of desired traffic characteristics, and it produces connection and disconnection requests according to the provided configuration. The algorithm incorporates a probabilistic approach that allows the statistics of the configuration to determine the distributions of the types of connections and disconnections that are attempted. Special considerations are made to maintain the requested output load, to apportion the payloads, and to create opportunities for bidirectional connections. This paper includes an analysis of factors that may affect traffic generatio

ISSN:1124-318X    

DOI:10.1002/ett.4460130309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractThis paper presents a new kind of optical code‐division multiple‐access (CDMA) codes, calledunequal‐length optical orthogonal codes(UL‐OOC's), for multirate data communications. The autocorrelation and cross‐correlation functions of UL‐OOC's are dependent only on each individual codeword, in spite of either an aperiodic or a periodic pulse‐sequence pattern at the input of optical CDMA decoders. This property can be thus used to support multirate data communications in a lightwave network, without any violation of the minimum correlation constraint (i.e., “1”) for incoherent optical processing. Theory and simple design of UL‐OOC's are presented. Applications of the proposed codes to multirate optical CDMA is also

ISSN:1124-318X    

DOI:10.1002/ett.4460130310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY

摘要:

AbstractThe distribution of the dwell time, which represents a higher level of abstraction than the use of mobility models, is often required for the performance evaluation of mobile communication systems. This contribution investigates the problem of the dwell time modeling. Using the often employed model for a constant movement, it is shown that a suitable choice of the velocity distribution is very important. Thus, a condition for the probability density function (PDF) of the velocity is derived, which prevents an unbounded mean dwell time. Since an infinite mean dwell time causes some problems for me estimation of the mobility‐related signaling traffic, it is important that the mean dwell time is finite. Furthermore, some basic models for the PDF of the travel length of a subscriber within a radio cell are introduced and the relation wim realistic mobility patterns are show

ISSN:1124-318X    

DOI:10.1002/ett.4460130311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:2002

数据来源: WILEY