2007 15th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems

A wireless sensor network (WSN) comprises many sensor nodes each one containing a processing unit, one or more sensors, a power unit, and a radio for data communication. Nodes are power constrained, because they run on batteries, that in many cases cannot be easily replaced. This paper presents a novel dynamic power management technique, named Dynamic Power Management with Scheduled Switching Mode... View full abstract»

We present a turnover based adaptive HELLO protocol (TAP), which enables nodes in mobile networks to dynamically adjust their HELLO messages frequency depending on the current speed of nodes. To the best of our knowledge, all existing solutions are based on specific assumptions (e.g., slotted networks) and/or require specific hardware (e.g., GPS) for speed evaluation. One of the key aspects of our... View full abstract»

We present Timestepped stochastic simulation (TSS) for 802.11 WLANs. TSS overcomes scalability problems of packet-level simulation by generating a sample path of the system state S(t) at time t = delta, 2delta, . . . , rather than at each packet transmission. In each timestep [t, t + delta], the distribution Pr( S(t + delta) | S(t) ) is obtained analytically, and S(t + delta) is sampled from it. O... View full abstract»

The transmission energy required for a wireless communication increases superlinearly with the communication distance. In a mobile wireless network, nodal movement can be exploited to greatly reduce the energy required by postponing communication until the sender moves close to a target receiver, subject to application deadline constraints. In this paper, we characterize the fundamental performanc... View full abstract»

We present an optimized scalable simulation model for TCP, developed in OPNET, and investigate its performance in the case of OLSR mobile ad-hoc networks (MANETs). The key idea for the model's construction is to represent each node by a subqueue, in the simulation model. Thus, the exchange of packets in the network is literally a set of enqueue/dequeue operations among the subqueues. The physical,... View full abstract»

Quality of service (QoS) in wireless 802.11 networks cannot be achieved without the support for service differentiation at the medium access layer. IEEE802.11 suffers from QoS limitations that have often been summarized in the literature. We present simulation results to show the effectiveness of several proposed techniques of improving the QoS in the IEEE802.11 protocol. Specifically, we closely ... View full abstract»

Simulation methods have become an integral part of almost all aspects of networking research and particularly in the area of wireless networks. Any new protocol or methodology that is proposed for wireless networks almost always will be demonstrated using simulations. However, there is little evidence that existing models of physical layer signal propagation and signal strength calculations produc... View full abstract»

We present interference analysis for wireless ad hoc networks and show that, depending on the path loss parameter (alpha), the average signal to noise and interference ratio (SNIR) either remains constant, or decays, when the number of interferers scales to infinity in the network, for nodes communicating with their close neighbors. Thus, communication is feasible in dense networks as long as alph... View full abstract»

We propose a hierarchical connected dominating set (CDS) based algorithm for clustering in mobile ad hoc networks (MANETs). Our algorithm is an extension of our previous connected dominating set based clustering (CDSC) algorithm [1]. We extended the levels of the CDS to two levels and improved functionality at each level by providing additional rules to make sure that every node belongs to a singl... View full abstract»

This paper aims to design a self-configuring cellular radio access network. It is a WiMAX based meshed network where base stations form a Cellular IP, all radio network. We then take advantage of mesh networks fast-deployment and self-organising properties, and of cellular networks high mobility support. In the proposed model, WiMAX nodes, or SSs, form the wireless mesh network and in the other ha... View full abstract»

Due to the proliferation of the multimedia applications over unreliable medium like wireless networks, robust image and video communication have become more important. In this paper, we consider the transmission distortions on the multimedia data due to both channel impairments and instant node failures for Wireless Multimedia Sensor Networks (WMSN). Two techniques are investigated to compensate t... View full abstract»

Many wireless sensor networks (WSNs) are used to collect and aggregate data from potentially hostile environments. Catering to this, early application scenarios did not put tight constraints on performance properties like delay, but rather focused on ruggedness and energy conservation. Yet, there is a growing number of sceanarios like e.g. production monitoring, intrusion detection, or health care... View full abstract»

Contention free bursting (CFB) is an innovative quality-of-service (QoS) scheme specified in the IEEE 802.11e standard. To reduce the contention overheads, this scheme enables the stations that gain the channel to transmit multiple frames back-to-back in a burst. Most existing analytical models of the CFB scheme have been developed under the assumption of identical stations with saturated traffic ... View full abstract»

Previously, we have developed a framework to perform systematic analysis of CSMA/CA based wireless MAC protocols. The framework first identifies protocol states that meet our study objective of minimizing a given performance metric. It then applies search techniques and heuristics to construct sequences of protocol events in a given topology that satisfy our objective. In this paper, we demonstrat... View full abstract»

Wireless Mesh Networks are a scalable and cost-effective solution for next-generation wireless networking. In the present work, we consider the Round Weighting Problem (RWP) which solves a joint routing and scheduling problem to satisfy a given demand subjected to the multi-access interferences. We propose a multiobjective approach that deals with two objectives. The first one is to balance the lo... View full abstract»

The IEEE 802.15.4 protocol has the ability to support time-sensitive wireless sensor network (WSN) applications due to the guaranteed time slot (GTS) medium access control mechanism. Recently, several analytical and simulation models of the IEEE 802.15.4 protocol have been proposed. Nevertheless, currently available simulation models for this protocol are both inaccurate and incomplete, and in par... View full abstract»

The distribution of the sensor locations may be nonuniform under some terrain imposed physical constraints or different sensing quality requirements in different parts of a wireless sensor network. Given such a nonuniformly deployed sensor network, some bottleneck areas will form soon after the network becomes operational. Those areas will severely decrease the lifetime of the network. We propose ... View full abstract»

A novel extension to binary-tree table organization suitable for external storage providing successful searches for nearly full tables requiring less than two accesses is presented. The generalizes the "efficient ordering of hash tables" effort presented in 1979. Both the experimental and analytical results demonstrate the reductions possible. This method places no restrictions on the the table co... View full abstract»

Object replacement strategies are considered as key performance factors of a web proxy caching application. Several algorithms have been proposed, analyzed and simulated during the last decade, in order to decide upon the champion one. In this paper, we recommend the methodology of Data Envelopment Analysis as a powerful tool, with a complementary activity to that of trace driven simulation, which... View full abstract»