Showing papers by "Vojislav B. Misic published in 2011"

Performance Characterization for IEEE 802.11p Network With Single Channel Devices

Abstract: In this paper, we investigate the performance of networks built from single-channel devices that use wireless access in vehicular environment protocols. We consider several traffic combinations, each of which presents a mix of traffic classes, over control and service channels. Our results show that time switching between the channels causes synchronization of backoff processes, which increases the frame collision probability, in particular for small sizes of contention windows. We also evaluate the impact of the interruption of the backoff process by inactive channel time, which gives rise to a probability distribution with repeated tails and a coefficient of variation larger than 1. Our model can also be used to evaluate different sets of enhanced distributed channel access parameters and to select the channel duty cycle according to the policy of the network operator.

ID-based Safety Message Authentication for Security and Trust in Vehicular Networks

Abstract: We present a safety message authentication scheme for vehicular ad hoc networks using an ID-based signature and verification mechanism. An ID-based technique offers a certificate-less public key verification, while a proxy signature provides flexibilities in message authentication and trust management. In this scheme, we incorporate an ID-based proxy signature framework with the standard ECDSA for VANET's road-side unit (RSU) originated safety application messages. Also, forwarding of signed messages are specially handled to ensure the trust and authentication of RSU's application messages. We claim that this scheme is resilient against all major security threats and also efficient in terms of computation complexity.

Performance Analysis of Cloud Centers under Burst Arrivals and Total Rejection Policy

Abstract: Quality of service, QoS, has a great impact on wider adoption of cloud computing. Maintaining the QoS at an acceptable level for cloud users requires an accurate and well adapted performance analysis approach. In this paper, we describe a new approximate analytical model for performance evaluation of cloud server farms under burst arrivals and solve it to obtain important performance indicators such as mean request response time, blocking probability, probability of immediate service and probability distribution of number of tasks in the system. This model allows cloud operators to tune the parameters such as the number of servers and/or burst size, on one side, and the values of blocking probability and probability that a task request will obtain immediate service, on the other.

Characterization of idle periods in IEEE 802.11e networks

Abstract: In this paper we investigate probability distribution of idle time in IEEE 802.11e networks with an access point. The probability distribution is shown to be sub-geometric and it can be approximated with a sub-exponential Gamma distribution. Secondary network operating within the transmission range of such a WLAN can use these probability distributions to estimate the probability of collisions with the transmissions from WLAN nodes, and make decision about the timing of their own forthcoming transmissions.

Reaching spatial or networking saturation in VANET

Abstract: In this article, we investigate the network transition between non-saturation and saturation regimes for a Vehicular Ad hoc Network (VANET) which is composed of mobile nodes. We combine vehicular traffic theory, queuing model, and Markov chain to evaluate the performance of the network under spatial or networking saturation for multiple data classes over control channel and service channel. Our results indicate that the vehicle density growth can result in saturation of wireless medium around the roadside unit (RSU), further resulting in buffer overflows at on board units (OBUs). We also investigate the network saturation points for different transmission ranges of a RSU. Our results show that RSU's transmission coverage has to be chosen with respect to data patterns of OBUs, minimal distance between vehicles, and number of lanes in order to avoid network saturation condition.

Dynamic parameter adjustment in 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 centralised and distributed selection of the channels to be sensed. We also propose an adaptive algorithm to determine the tax coefficient and show that it offers superior data transmission performance whilst not affecting the sensing accuracy.

Video communications over IEEE 802.11p using single channel devices

Abstract: IEEE 802.11p is a new communication standard for wireless access in vehicular environment (WAVE), intended to support road safety messages, electronic toll collection, infotainment services, and other as well as a number of other intelligent transportation systems (ITS) applications. In this paper, we focus on the impact of the dwelling time on the control channel (CCH) vs. that on the SCH (i.e., the duty cycle) on the performance of video communication on the service channel (SCH), using a novel analytical model. We show that a range of duty cycles allows for satisfactory performance of video traffic on SCH as well as timely delivery of safety messages on CCH.

Medium Access in Ad Hoc and Sensor Networks

Abstract: Introduction 1 MAC Design Goals in Ad Hoc Networks 2 Classifi cation of MAC Protocols For Ad Hoc Networks 4 Mechanism for Accessing the Medium 4 Alternative Classifi cations on the Basis of Medium Access Mechanism 4 Mechanism Used for Bandwidth Reservation and Its Scope 5 Presence and Scope of Synchronization 5 Presence and Permanence of a Controller 5 Interference Reduction Mechanism 5 Interdependence of Classifi cation Criteria 5 Contention-Based MAC Protocols 6 Basic Carrier Sense Multiple Access 6 IEEE 802.11 MAC 6 Multiple Access Collision Avoidance 7 Multiple Access Collision Avoidance Protocol for WLANs 8 Floor Acquisition Multiple Access 9 MACA by Invitation 9 MACA with Reduced Handshake 10 MAC Protocols that Use Bandwidth Reservation 11 Distributed Packet Reservation Multiple Access 11 Hop Reservation Multiple Access Protocol 11 Collision Avoidance Time Allocation Protocol 12 MACA with Piggybacked Reservation 12 Distributed Priority Scheduling 13 Multichannel MAC Protocols 13 Multichannel CSMA with Soft Channel Reservation 13 Slotted Seeded Channel Hopping 14 Asynchronous Multichannel Coordination Protocol 14 MAC Protocols with Power Management 15 Power-Aware Multiaccess Protocol with Signaling 15 Dynamic Power-Saving Mechanism 15 Power Control Mechanism 16 MAC Protocols that Use Directional Antennae 16 MAC Protocols that Use Out-of-Band Signaling 17 Busy Tone Multiple Access 17 Receiver-Initiated BTMA 17 Dual BTMA 17 MAC Protocols that Use Polling 17 Bluetooth 17 Sensor Networks 18 Energy Effi ciency 18 Protocol Effi ciency 18 Use of Redundant Sensors 19 Node Specialization 19 Traffi c Characteristics 19 Quality-of-Service Requirements 19 Differences from Ad Hoc Networks 19 MAC Protocols for Wireless Sensor Networks 20 Adaptive Rate Control with CSMA 20 S-MAC 20 Time-Out MAC 21 Traffi c-Adaptive Medium Access 22 Other MAC Protocols for Sensor Networks 22 Conclusion 24 Glossary 24 Cross References 25 References 25 Medium Access in Ad Hoc and Sensor Networks

Performance of simple cognitive personal area networks with finite buffers

Abstract: We investigate the performance of simple cognitive personal area network (CPAN) with cooperative sensing. Nodes are equipped with small buffers of capacity K each, and each node is allowed to transmit a batch of up to μ packets in one transmission cycle. Upon transmission, each node must support the operation of the CPAN by performing sensing duty in the amount obtained by multiplying the number of packets sent in a batch by a variable penalty coefficient We model this system and show the relationship between packet blocking and carried load with respect to scheduling parameter μ, penalty coefficient, traffic load and piconet size.

Cognitive wireless personal area network for monitoring and control

Abstract: In this paper, we propose and evaluate a cognitive personal area network (CPAN) suitable for wireless monitoring and control outside the Industrial, Scientific and Medical (ISM) band. Network is based on frequency hopping but the channels are selected on the basis of spectrum sensing performed by the nodes. Nodes balance their data collecting activity and spectrum sensing such that the duration of spectrum sensing done by a node is proportional to the number of packets previously transmitted by that node. We show that the operation of a node in this setup can be modeled as a gated exhaustive round-robin system with vacations, and analyze the performance of the system. The impact of the value of the penalty factor, which determines the duration of sensing activity with respect to transmission, on packet access delay and stability limits of the system is discussed in detail. Copyright © 2009 John Wiley & Sons, Ltd.

Cognitive MAC Protocol with Transmission Tax: Probabilistic Analysis and Performance Improvements

Abstract: We investigate the performance of a cognitive personal area network (CPAN) in which spectrum sensing is linked to packet transmissions. Efficient CPAN operation may be achieved if each data transmission is taxed by requiring the transmitting node to participate in cooperative sensing for a prescribed time period. In this approach, each node is allowed to transmit a single packet in one transmission cycle, but must then ‘pay’ for it by spectrum sensing, which not only ensures fairness with respect to transmission but also distributes the sensing burden to all nodes. We describe a probabilistic model of the integrated system and evaluate its performance with respect to packet transmissions and spectrum sensing. We discuss two modifications that involve centralized and distributed selection of the channels to be sensed. We also propose an adaptive algorithm to determine the tax coefficient and show that it offers superior data transmission performance while not affecting the sensing accuracy.

Performance of simple cognitive personal area networks with finite buffers and adaptive superframe duration

Abstract: We investigate the performance of simple cognitive personal area networks (CPANs) with cooperative sensing. Nodes are equipped with small buffers of capacity K each, and each node is allowed to transmit a batch of up to μ packets in one transmission cycle. Upon transmission, each node must support the operation of the CPAN by performing sensing duty in the amount obtained by multiplying the number of packets sent in a batch by a variable penalty coefficient. We model this system and show the relationship between values of design parameters and piconet performance. We also show that performance and bandwidth utilization can be improved by a simple technique of dynamically adjusting the duration of the superframe to cater to instantaneous traffic volume. Copyright © 2011 John Wiley & Sons, Ltd.