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Modern E-commerce services are offered in a complex but flexible setup involving multiple websites (e.g., business web portals or price comparison websites) with facilities for determining the quality of products. Though this modern style of service provisioning attracts more customers it also significantly increases load on the web servers that are implementing the E-commerce services. The concern is that overloaded servers will become unresponsive and will drop requests which are beyond their capacity. This paper proposes a formal approach in order to investigate the effects of traffic load and the number of dropped requests on the performance of modern E-commerce services. The proposed approach is based on a class-based priority scheme that classifies E-commerce requests into different classes by taking into account the type of request and the client΄s behaviour. The proposed model is formally specified, implemented and tested through several experiments. The experimental results show that the proposed approach improves the response time and throughout of high priority requests, and also analyses the consequential effect on dropped (low priority) requests. [ABSTRACT FROM AUTHOR]

This paper analyses a multiple class single server M/M/1/K queue with finite capacity under weighted fair queuing (WFQ) discipline. The Poisson process has been used to model the multiple classes of arrival streams. The service times have exponential distribution. We assume each class is assigned a virtual queue and incoming jobs enter the virtual queue related to their class and served in FIFO order.We model our system as a two dimensional Markov chain and use the matrix-geometric method to solve its stationary probabilities. This paper presents a matrix geometric solution to the M/M/1/K queue with finite buffer under (WFQ) service. In addition, the paper shows the state transition diagram of the Markov chain and presents the state balance equations, from which the stationary queue length distribution and other measures of interest can be obtained. Numerical experiments corroborating the theoretical results are also offered. [ABSTRACT FROM AUTHOR]

Prolonging the life time of Wireless Sensor Networks (WSNs) has been the focus of current research. One of the issues that needs to be addressed along with prolonging the network life time is to ensure uniform energy consumption across the network in WSNs especially in case of random network deployment. Cluster based routing algorithms are believed to be the best choice for WSNs because they work on the principle of divide and conquer and also improve the network life time considerably compared to flat based routing schemes. In this paper we propose a new routing strategy based on two layers clustering which exploits the redundancy property of the network in order to minimise duplicate data transmission and also make the intercluster and intracluster communication multihop. The proposed algorithm makes use of the nodes in a network whose area coverage is covered by the neighbouring nodes. These nodes are marked as temporary cluster heads and later use these temporary cluster heads randomly for multihop intercluster communication. Performance studies indicate that the proposed algorithm solves effectively the problem of load balancing across the network and is more energy efficient compared to the enhanced version of widely used Leach algorithm. [ABSTRACT FROM AUTHOR]

Motivated by the need of performance analysis of Active Queue Management (AQM) schemes under highly bursty and correlated traffic in multi-service networks, this paper develops an analytical model for a finite capacity queueing system with an AQM scheme subject to two heterogeneous classes of traffic which are modeled, respectively, by the bursty Markov-Modulated Poisson Process (MMPP) and non-bursty Poisson Process. The well-known MMPP is adopted for modelling bursty traffic owing to its ability to model the time-varying arrival rate and capture the important correlation between inter-arrival times while still maintaining analytical tractability. We derive the aggregate and marginal performance metrics including the mean queue length, response time, system utilization, throughput and loss probability. The accuracy of the model is validated by comparing analytical results with those obtained from simulation. We further focus on the evaluation of the effects of traffic burstiness and correlation of inter-arrival time on the aggregate performance metrics of AQM with different thresholds. [ABSTRACT FROM AUTHOR]

Links between nodes in mobile ad hoc networks (MANETs) are vulnerable to breakage because of the highly dynamic nature of MANETs, this results in frequent changes and unpredictability in network topologies. So, discovering and maintaining routes between nodes is one of the biggest challenges in MANETs. This makes the routing area perhaps the most active research area within the MANET domain. The ultimate goal of the MANET community is to provide a set of standardized protocols that can be both robust and scalable. This paper proposes a routing protocol based on the angles (directions) of the adjacent mobile nodes. Each pair of nodes that form a hop should ideally be moving in the same or similar direction, so the connection between the source and the destination will consist of a series of nodes that are moving in a similar direction. We measure the performance of the proposed approach by evaluating it against the ad-hoc on demand distance vector (AODV) routing protocol. The simulation results reveal thatthe proposed approach demonstrates better performance than AODV for most scenarios. [ABSTRACT FROM AUTHOR]

The rapidly growing mobile demands have reinforced the network providers to emphasize on the basic customer needs and the resource management. The two main areas such as capacity management and data service provisions have engulfed the research field. This research paper attempts to cover both these issues in terms of Call Admission Control (CAC). Paper presents an adaptive technique built upon our previous static CAC research. The scheme provides differentiated admission to various delay sensitive (DS) and delay tolerant (DT) traffic streams for both Handover Request (HOR) and New call Request (NCR) according to current load intensity. It is based on an effective pre-emption priority in order to reduce the forced handover failure probability. Service nature and customer behaviour have been considered to lay down the different levels of priorities that were assigned at different stages of CAC Scheme in order to achieve optimal quality of service (QoS) for urban area (metropolitan) cell. [ABSTRACT FROM AUTHOR]

This paper begins with a brief literature review of various approaches to congestion avoidance and control of Internet traffic. It focuses mainly on one of Active Queue Management (AQM) schemes known as Random Early Detection (RED) mechanism for congestion control at routers. Towards the end of paper, an approximate analytical performance model has been proposed based on standard RED mechanism as an effective congestion control technique. Methodology adopted is based on Principle of Maximum Entropy (ME) to model RED mechanism. To model the bursty input traffic, Generalized Exponential (GE) distribution has been used. Closed form expressions for the state and blocking probabilities have also been presented. Numerical examples have been presented. By comparing results obtained from ME (Analytical Model) and Simulation in QNAP-2 [22], it validates the credibility of ME solution. [ABSTRACT FROM AUTHOR]