In this paper, we develop efficient analytic techniques for characterization of other-cell interference in the uplink of CDMA cellular networks. An iterative method for solving fixed-point equations is employed to determine the mean and variance for lognormal approximation of the other-cell interference. All the parameters involved in calculation are obtained analytically, which ensures the proposed model to be pure analytical. Subsequently, the outage probability is defined and evaluated based on the approximation of tail probability.

Wireless local area networks have developed into a promising solution to support advanced data services in untethered environments. Selection of an efficient packet-scheduling scheme is important for managing the bandwidth while satisfying QoS requirements of active sessions having diverse traffic characteristics. The key difficulty is the distributed nature of the queues in the uplink, resulting in the scheduler having to trade off polling greedy stations against wasting resources by polling potentially idle stations. In order to address this, we propose a novel scheduling scheme, "embedded round robin", which dynamically classifies stations as "busy" and "clear". We then extend the previously proposed dual queue scheduling discipline to the case of wireless networks.

Future cellular networks will witness a full-scale introduction of small sized cells and wide implementation of smart antenna systems. In such systems, the combination of high traffic density and mobility effects on system performance are quite significant. In this paper we present a study of the performance of a CDMA cellular system using smart antennas, where mobility of users inside the cell and between cells is considered. A considerable number of calls are dropped due to the movement of mobiles in different regions of a cell; therefore the capacity is significantly reduced. The beamwidth and cell size also affect the performance and considerably influence the impact of mobility on the capacity of the system. We show how decreasing the beamwidth increases the capacity but at the same time worsens the effects of mobility on the performance.

Wireless local area networks are a promising solution to support advanced data services in mobile environments. The IEEE 802.11 wireless LAN standard is emerging as a mature technology to support delay sensitive network services. In order to support these services the standard has proposed the use of a polling scheme; however, existing polling schemes require high communication overheads or suffer from unfairness. In this paper, we propose a distributed fair queueing algorithm "distributed deficit round robin", which is compatible with the 802.11 medium access control rules. Software simulation of this scheme shows that it can manage a heterogeneous mix of delay sensitive traffic.

A substantial demand exists in enterprise networks for obtaining an interLAN telephony service integrated with asynchronous data services. We determine the end-to-end performance of a standalone IEEE 802.5 LAN and ATM internetworked 802.5 LANs by using a simulation based approach and compare their performance. Both the standalone IEEE 802.5 LAN and ATM internetworked 802.5 LANs offer a telephony service integrated with an asynchronous data service. The provision of an interLAN telephony service integrated with asynchronous data services entails the implementation of a novel method in the interworking units so as to segregate the voice data from the asynchronous data. The end subnetworks considered in the case of internetworked integrated services heterogenous ATM LANs are IEEE 802.5 and the recently standardised 802.9a (isoEthernet) LANs. A key issue addressed in this case is the internetworking of the packet based IEEE 802.5 LAN to the 802.9a LAN.

This paper examines wavelength translation in all-optical wavelength-routed networks. Previous studies have shown that wavelength translation can improve the blocking performance of these networks. However, all the previous work has assumed that wavelength translators can translate from any input wavelength to any output wavelength. In contrast, all-optical wavelength translators demonstrated in the laboratory to date are, in general, only capable of limited translation. We assess, for the first time, the network performance improvements offered by realistic all-optical wavelength translators with a limited translation range. In particular, we consider all-optical wavelength translators based on four-wave mixing in semiconductor optical amplifiers. Using a simple model for their function, we consider the blocking performance of two-hop and multiple-hop paths, and unidirectional ring and mesh-torus networks. In all the cases we consider, significant improvement in the blocking performance of the network is obtained when limited-range wavelength translators with as little as one quarter of the full range an introduced. We also find that almost all of the network performance improvement observed by an ideal wavelength translator can be gained from a translator with only half of the full translation range.

The introduction of ATM technology in the customer premises is being propelled by the need for a seamless interconnection between end subnetworks. Furthermore, integrated services over the end LANs in the customer premises are envisaged to gain momentum with the advent of efficient data compression techniques and high performance computers. In this paper, we first propose a distributed communications network architecture based on an ATM switch fabric for internetworking IEEE 802.3 and 802.5 LANs carrying integrated voice and data services. In the second section of this paper, performance analysis of the integrated services LANs, which form the end subnetworks in the architecture, is carried out. The principal objectives of this performance analysis are to determine the magnitude of the mean frame transfer delay contributed by the LANs as well as to confirm that a satisfactory number of Integrated Voice and Data Stations (IVDSs) could be supported on the LAN subnetworks. The performance evaluation of the IEEE 802.3 and 802.5 LANs for the transfer of asynchronous data is validated by extensive stochastic simulations. Simulation results obtained for the transfer of isochronous data on the IEEE 802.5 LAN are also presented.

The paper analyses the teletraffic behaviour of the mobile to cell site link in code division multiple access (CDMA) cellular mobile systems. The analysis models such systems as a network of queues to derive a general solution for traffic handling capability.>

The drop-out probability and the unnecessary handover performance of several handover schemes have been investigated using a simulation model which incorporates detailed representation of mobility, traffic and propagation environments. Specifically the overall performance of variable hysteresis level handover schemes are investigated. The performance under various mobility conditions are presented for both Manhattan city environment and hexagonal cell layout. Also the performance dependency on more critical input parameters such as mobile speed and correlation of sample measurements, is presented. It is shown that an environment dependent, variable hysteresis function can be devised by closely studying the system handover behaviour to give the optimum overall performance.>

The traffic analysis of small-cell mobile networks with dynamic channel assignment is investigated to determine their blocking performance, using a hybrid method of analysis and simulation. The authors particularly focus on the performance problems presented by networks with heterogeneous cell traffic loads, the impact of traffic volatility among the cells, and the impact of multichannel traffic on the channel blocking probabilities. Significant improvement in network performance with dynamic channel assignment is established by numerical results.>

A cyclic service system with the limited service discipline, where up to a fixed number k of messages can be served at each visit to each queueing station is presented. This limit may be utilized in exhaustive or gated mode. A pseudoconservation law is derived for the exhaustive form of limited service, and a derivation is provided for the gated form of limited service.>

Recently, a conservation law for the waiting times at a token ring has been derived. This conservation law is used here to develop simple approximations to the waiting times at individual queues on a token ring. Although exact algorithms are available, they may require significant computation time. In contrast, the approximation developed here is easily calculated on a pocket calculator, and is more accurate than earlier approximations.