Showing papers by "Vojislav B. Misic published in 2010"

Bridge performance in a multitier wireless network for healthcare monitoring

Abstract: Advances in computer and communication technology have enabled online healthcare monitoring using miniature sensing devices attached to a patient's body. Data collected in this manner is then delivered in real time, through one or more wireless hops, to the hospital network. In this article we discuss some design alternatives for the wireless portion of an integrated healthcare monitoring system, in particular issues related to its topology, the choice of wireless communication technology for tiers with well defined function, and the bridging between tiers. We also present some performance results for a two-tier topology with isolation of high-data-rate traffic from low-data-rate traffic, in which the patient's body area network is implemented using 802.15.4 low-data-rate WPAN technology, while connection in the next higher tier (i.e., from the body area network to a hospital ward network or home network) uses the ubiquitous 802.11 WLAN technology.

Tradeoff Issues for CCH/SCH Duty Cycle for IEEE 802.11p Single Channel Devices

Abstract: In this paper we investigate the ratio of dwelling time in control channel (CCH) and service channel (SCH) for single channel devices deploying WAVE (Wireless Access in Vehicular Environments) protocols. Based on analytical model for both channels and four traffic types we present tradeoffs in channel performance when CCH/SCH duty cycle is changing. Our results show that, when video traffic is absent, duty cycles smaller than 0.5 can offer satisfactory performance on CCH while running larger amount of revenue generating traffic on SCH.

Performance Analysis of Cloud Computing Centers

Abstract: Cloud computing is a computing paradigm in which different computing resources, including infrastructure, hardware platforms, and software applications, are made accessible to remote users as services. Successful provision of infrastructure-as-a-service (IaaS) and, consequently, widespread adoption of cloud computing necessitates accurate performance evaluation that allows service providers to dimension their resources in order to fulfil the service level agreements with their customers. In this paper, we describe an analytical model for performance evaluation of cloud server farms, and demonstrate the manner in which important performance indicators such as request waiting time and server utilization may be assessed with sufficient accuracy.

Cognitive MAC Protocol with Transmission Tax: Dynamically Adjusting Sensing and Data Performance

Abstract: Efficient operation of a cognitive personal area network (CPAN) may be achieved if each data transmission is taxed by requiring the transmitting node to participate in cooperative sensing for a prescribed time period We investigate the data transmission performance of this approach as well as its sensing accuracy Through adaptive management of both the sensing process and data transmission, we show that the two facets of performance may be adjusted almost independently

Best papers from the WWASN2009 workshop

Abstract: The use of wireless ad hoc and sensor networks is steadily increasing from general networking applications to more specialised areas such as environmental monitoring, health care, logistics, military and surveillance. Theory, design and deployment of those networks are subject to many constraints and challenges, most of which differ from those encountered in traditional wired networks. These challenges are addressed through efforts of many research groups from both academia and industry all around the world, and many conferences and symposia are devoted to the presentation and dissemination of their research results. One of such conferences is the highly successful series of workshops on Wireless Ad hoc and Sensor Networks (WWASN) held in conjunction with previous ICDCS conferences in Providence, RI; Tokyo, Japan; Columbus, OH; Lisbon, Portugal; Toronto, ON; Beijing, China; and, most recently, Montreal, Canada. The Sixth International Workshop on Ad hoc and Sensor Wireless Networks (WWASN2009), held in Montreal on June 2009, has attracted no less than 37 paper submissions, out of which a total of 18 were selected for presentation at the workshop. While the acceptance rate has remained more or less at the same level over the years, the quality of submitted papers has steadily increased. We have also noticed that, while the well-established areas of topology, routing and performance still attract a lot of attention, an increasing number of papers dealt with emerging areas of energy efficiency, security, underwater/medical sensor networks, opportunistic spectrum access and data caching and storage in ad hoc and sensor networks. The scope and number of submissions indicate that the field of wireless ad hoc and sensor networks is alive and healthy and that research-oriented workshops such as this one are the primary outlet needed to disseminate the latest advances in the state of the art in modelling, design and deployment of such networks. Extended versions of five of the best papers from the workshop are presented in this special issue. The first paper, by Akkaya, Guneydas and Bicak, deals with sensor–actor network in which sensors and actors collaborate to facilitate autonomous actor positioning and thus reduce the need for human intervention or eliminate it altogether. The paper presents a location-matching algorithm that assigns actors to appropriate clusterheads with the goal of minimising both message overhead (born by the sensors) and travel distance of individual actors. Simulation results show that the proposed approach can give satisfactory results with very little overhead, while not requiring centralised control and knowledge of all actor and clusterhead positions. The paper by Li focuses on multihop wireless networks with multiple channels and attempts to solve the transmission time minimisation problem. While the problem itself is NP-hard, a number of heuristic algorithms that approach the lower bound of the minimum transmission time are described and analysed. The performance of proposed algorithms for

Performance of a Cognitive MAC Protocol with Transmission Tax

Abstract: Efficient operation of a cognitive personal area network (CPAN) may be achieved if each data transmission is taxed by requiring the transmitting node to participate in cooperative sensing for a prescribed time period. We investigate the data transmission performance of this approach, as well as its sensing accuracy, and discuss two modifications that involve centralized and distributed selection of the channels to be sensed.

Mobile Software Agents for Wireless Network Mapping and Dynamic Routing

Abstract: Mapping and dynamic routing in a wireless network are essential and basic operations that are the prerequisites for all higher order interactions between nodes on that network. The Intent of network mapping by multi mobile software agents is to obtain the topology of network in a distributed manner. In this paper we examine how software agents can wander in an unknown Ad hoc network with cooperation to report the topology of the network. We present results from a simulation of such a system and discuss the relationship between the overall efficiency of the system and diversity of the agent types, agent population, agent memory, inter-agent communication styles. In dynamic network routing, mobile agents are responsible for updating the routing table of nodes for a multi-hop communication purpose. The dynamic nature of the topology of the Ad hoc networks is due to mobility of some nodes in the network: wireless links are broken and reformed frequently. In this paper we present a dynamic, wireless, peer to peer network with routing tasks performed in a decentralized and distributed fashion by mobile software agents that cooperate to accumulate and distribute network connectivity information. We also examine different types of agents, stigmergic versus non stigmergic having identical overheads to study the outcome connectivity in a dynamic wireless network.

Controlling Sensing Error for Cognitive PANs with 1-Limited Packet Scheduling

Abstract: Packet transmission in cognitive personal area networks (CPANs) may be linked to spectrum sensing, in the sense that each node is allowed to transmit a single packet in one transmission cycle, but must then `pay' for it by spectrum sensing; this ensures fairness with respect to transmission as well as the sensing burden. The amount of `payment' effort is dimensioned so as to keep the total sensing error below a pre-defined limit. We model the integrated system and evaluate its performance with respect to packet transmissions and spectrum sensing.

Stability Boundaries between Non-Saturation and Saturation Regimes for IEEE 802.11e EDCA

Abstract: In this paper we investigate the transition between non-saturation and saturation regimes for the EDCA function within the IEEE 802.11e standard. We develop queueing and Markov chain models for node operation, and demonstrate interaction among traffic classes in transition from non-saturation to saturation regime. We derive probability generating functions (PGFs) for the probability distributions of packet service time and buffer occupancy. We also derive Laplace-Stieltjes transform (LST) for the probability distribution of frame response time and show stability limits for each traffic class.

Performance of G-limited scheduling in a cognitive MAC with transmission tax

Abstract: Efficient operation of a cognitive personal area network (CPAN) may be achieved if each data transmission is taxed by requiring the transmitting node to participate in cooperative sensing for a prescribed time period. Extended sensing, however, tends to impair the data transmission performance. In this paper we investigate the performance of G-limited scheduling which ensures satisfactory packet delay for each node, whilst making sure that sufficient sensing is done so as to maintain smooth operation of the CPAN.

Performance of Bridging Algorithms in IEEE 802.15.3 Multi-Piconet Networks

Abstract: In this chapter, we introduce the bridging problem from the viewpoint of the recent IEEE 802.15.3 high data rate WPAN, and present alternative solutions that are possible in 802.15.3 networks. Then, we investigate the performance of a network with two piconets interconnected in a parent-child manner and linked through a bridge device which operates in a master-slave fashion. We have designed an adaptive bandwidth allocation algorithm for bridge down link CTA allocation, and examined the impact of the value of the smoothing constant and threshold hysteresis on the throughput, blocking probability, and average queue size for the downlink queue at the bridge.

Performance of sensing-after-transmission policy in cognitive personal area networks

Abstract: Performance of cognitive personal area networks is critically dependent on the accuracy of channel sensing. To ensure smooth operation of a cognitive PAN, all nodes that have data to transmit must take part in the sensing process. However, sensing affects transmission and vice versa, and a balance between sensing and data transmission must be found. One mechanism suitable for achieving this balance is to mandate a predefined sensing duty after each packet transmission. The paper describes this policy and investigates its performance under a wide range of network and traffic parameters.