摘要:

AbstractThe changing environment of telecommunications service operators leads to an increasing customer orientation and an ever increasing complexity. The technical consequence of the increased customer orientation is visible in the higher interest in flexibility engineering. The increasing complexity is becoming the major problem in telecommunication systems of this decade. To deal with this complexity two fundamental capabilities are used: abstraction and structuring. In general, models can be identified on any level of abstraction, e.g. high‐level system behaviour models, high‐level system architectural models and low‐level architectural models. When system complexity increases, more levels of abstraction will be necessary to deal with this complexity. Various methods exist to define models at different levels of abstraction. In this paper three modelling methods are discussed. It is demonstrated that abstraction is used in a similar way in these modelling methods. One particular method for abstraction is the use of the object‐oriented paradigm, a powerful approach for modelling as well as for implementation. Additional structuring methods based on considerations with respect to the functionality, however, remain indispensable in order to keep complexity under control. Those methods, stratification and segregation, are specifically relevant in high level architectural

ISSN:1074-5351    

DOI:10.1002/dac.4500070103

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

年代:1994

数据来源: WILEY

摘要:

AbstractCSMA protocols have been extensively studied under the assumption of an equilibrium condition. The results obtained in this manner provided useful insight for the development of packet radio and local area networks for the transmission of bursty data. The integration of isochronous and bursty traffic in the same network may, however, make the equilibrium assumption unrealistic, for example when fixed‐length frames are defined, only a portion of which is devoted to the transmission of bursty data according to a CSMA protocol. In such cases, it is necessary to study the protocol behaviours in fixed‐length time segments. This paper presents a technique for the analysis of slotted CSMA protocols in such an environment. Definitions for the transient throughput and transient average packet delay are introduced, and closed form expressions are derived for non‐persistent and 1‐persistent CSMA and CSMA/CD protocols with arbitrary distribution of the packet length. Numerical results help in the visualization of some interesting phenomena, peculiar to the CSMA operations in finite‐length

ISSN:1074-5351    

DOI:10.1002/dac.4500070104

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

年代:1994

数据来源: WILEY

摘要:

AbstractCurrent trends in personal and data communication networks favour code division multiple access (CDMA) as a solution to spectral congestion. This is because of enhanced capacity, security, network flexibility, simplified protocol, and relative immunity to propagation induced errors such as multipath and interference, as compared with traditional frequency division multiple access (FDMA). Various CDMA schemes have been proposed and described in relation to VSAT systems, local area microcells,2and cellular telephones. Additionally, numerous product applications have emerged in the areas of modems, voice links and wireless local exchanges. These systems require inter‐ and intra‐cell control. By contrast, the scheme presented in this paper places no reliance on intercell protocol. It enables new cells to be added to the network without any impact on the hardware. Network reconfiguration requires software changes only. Therefore, the scheme is appropriate to systems which demand flexibility with minimum overhe

ISSN:1074-5351    

DOI:10.1002/dac.4500070105

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

年代:1994

数据来源: WILEY

摘要:

AbstractA simple algorithm for resolving output contentions in an input‐buffered Batcher‐banyan network is described. The basic idea in this algorithm is to let the binary nodes of the Batcher network participate in the arbitration process. The proposed algorithm is completely distributed and parallel; thus it scales well to large size switches. Furthermore, our algorithm is fair and requires an overhead that is significantly less than that due to the well‐known three‐phase algorithm. Two variations of the algorithm are de

ISSN:1074-5351    

DOI:10.1002/dac.4500070106

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe staggered multicast protocol for multihop spread spectrum packet radio networks is suitable for unicasting and broadcasting as well as multicasting. The common‐header/transmitter‐based spreading code is used for data packet transmission and the receiver‐based code is used for acknowledgement packet transmission. By staggering packet transmission the protocol can significantly reduce broadcasting delay. A special addressing method and packet format are also designed to achieve collision‐free acknowledgement and multicast capability. Simulation results show that the protocol provides better throughput‐delay performance than the common‐header/transmitter‐based slotted A

ISSN:1074-5351    

DOI:10.1002/dac.4500070107

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

年代:1994

数据来源: WILEY

摘要:

AbstractA novel multiplexing scheme for integrated networks characterized by the coexistence of circuitswitched and packet‐switched traffic is described in this paper. The new scheme is realized by a reinforcement of the basic movable boundary hybrid‐switching technique, by incorporating an adaptive interpolation within the circuit‐switched subsystem. The adaptation mechanism is controlled by the level of congestion in the packet queue. A precise queueing model for the multiplexer is developed and an analytical evaluation of the key performance parameters of interest, namely the loss probability and expected delay of the packet‐switched subsystem, and the freeze‐out fraction of the circuit‐switched subsystem, is conducted. The results of several numerical studies are presented to describe the performance of the multiplexer under different conditions. Of particular significance resulting from these studies is the trade‐off between the freeze‐out fraction of the circuit‐switched subsystem and the loss probability of the packet‐switched subsystem; this trade‐off may be exploited in a systematic design of the interrated multiplexer tailored to

ISSN:1074-5351    

DOI:10.1002/dac.4500070108

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

年代:1994

数据来源: WILEY

摘要:

AbstractWe discuss the interference of two sequences ofnpulses reaching a point x of space at two separate times.

ISSN:1074-5351    

DOI:10.1002/dac.4500070109

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

年代:1994

数据来源: WILEY

ISSN:1074-5351    

DOI:10.1002/dac.4500070102

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

年代:1994

数据来源: WILEY