Showing papers by "Vojislav B. Misic published in 2012"

Performance Analysis of Cloud Computing Centers Using M/G/m/m+r Queuing Systems

Abstract: Successful development of cloud computing paradigm necessitates accurate performance evaluation of cloud data centers. As exact modeling of cloud centers is not feasible due to the nature of cloud centers and diversity of user requests, we describe a novel approximate analytical model for performance evaluation of cloud server farms and solve it to obtain accurate estimation of the complete probability distribution of the request response time and other important performance indicators. The model allows cloud operators to determine the relationship between the number of servers and input buffer size, on one side, and the performance indicators such as mean number of tasks in the system, blocking probability, and probability that a task will obtain immediate service, on the other.

DDoS attack on WAVE-enabled VANET through synchronization

Abstract: A VANET that uses IEEE 802.11p EDCA mechanism is susceptible to a synchronization-based DDoS attack due to periodicity of transmissions and small contention window sizes. To make things worse, neither the sender nor receivers of periodic broadcasts will be aware of the attack since broadcast communications in VANET do not have acknowledgements. In this paper, we analyze the prospect of a synchronization-based DDoS attacks on vehicular communications and propose mitigation techniques to avoid such an attack.

Availability analysis of cloud computing centers

Abstract: Accurate availability and performance analysis are important requirements to guarantee quality of services (QoS) for cloud users. In this paper, we integrate an availability model in overall analytical sub-models of cloud system. Each sub-model captures a specific aspect of cloud centers. The key performance metrics such as task blocking probability and total delay incurred on user tasks are obtained. Our results can be used by an admission control to prevent the cloud center from entering unstable regime of operation. The results also reveal practical insights into capacity planning for cloud computing centers.

Analysis of Impact of TXOP Allocation on IEEE 802.11e EDCA under Variable Network Load

Abstract: In this paper, we investigate the impact of transmission opportunity (TXOP), arbitration interframe space (AIFS), and contention window on the performance of an IEEE 802.11e cluster with four traffic classes under Poisson frame arrivals. We derive an analytical model of the cluster using queuing model of individual nodes, discrete time Markov chain, and probabilistic modeling of the backoff process. The analytical model demonstrates the complex interaction between TXOP, on one side, and AIFS and contention window, on the other. We derive saturation and stability points for all traffic classes and discuss their dependency on TXOP allocations. Our results indicate that use of nonzero TXOP parameter under Poisson frame arrivals improves performance slightly by separating points of saturation and instability. More substantial performance improvements should be expected by deploying TXOP differentiation under bursty traffic. Since all traffic classes need to operate in stable, nonsaturated regime, this work has important implications for the design of congestion control and admission control schemes in IEEE 802.11e clusters.

Capillary machine-to-machine communications: the road ahead

Abstract: Machine-to-Machine (M2M) communications are expected to include billions of smart devices in the next three to five years. However, existing communication standards are incapable of providing satisfactory performance for M2M traffic. In this paper, we outline some advances that will enable existing wireless personal area networks, in conjunction with existing cellular communication standards, to be adapted to the needs of M2M traffic.

Extending LTE to support machine-type communications

Abstract: We discuss the changes needed in several of the key areas of 3GPP Long Term Evolution (LTE) network technology that would enable LTE networks to accommodate Machine-Type Communication traffic and applications, in particular those related to smart metering.

MAC performance modeling of IEEE 802.15.6-based WBANs over Rician-faded channels

Abstract: Since the signal transmission in WBANs takes place around or in the human body, the channel fading significantly affects the error performance of the networks. In this paper, we investigate MAC performance of an IEEE 802.15.6-based WBAN operating over a Rician-faded channel. We deploy Bit Error Rate (BER) as a function of channel quality, diversity order, and Signal to Noise Ratio (SNR) values for all User Priorities (UPs) in analytical and simulation models to evaluate the MAC performance. We study how varying Signal to Noise Ratio (SNR) of all UPs affects the MAC performance. Our results indicate that data frame sizes and channel quality between a node and the hub are the most effective parameters on PHY/MAC performance of a WBAN.

An identity-based authentication scheme for safety messages in WAVE-enabled VANETs

Abstract: In a vehicular ad hoc network VANET, a road-side infrastructure or road-side unit RSU is anticipated to be installed at some road-side location. This exposes the VANET to several different adversaries. In this paper, we present an authentication scheme for infrastructure-generated safety messages using an identity ID-based proxy signature and verification mechanism. An ID-based technique offers a certificate-less public key verification, while a proxy signature provides flexibility in message authentication and trust management. We incorporate an ID-based proxy signature framework with the standard elliptic curve digital signature algorithm for safety application messages from RSU. We also provide forwarding of safety message components ensuring the accountable authentication of RSU's application messages. Security analysis and network simulation prove that our scheme is resilient to all major security threats, compatible to standards and efficient in terms of computation complexity. We also conduct simulation experiments to determine the most suitable access classes for on-board unit and RSU.

Towards an efficient rendezvous protocol for a cognitive PAN

Abstract: In this paper we describe a rendezvous protocol that enables nodes to quickly and reliably discover an existing channel-hopping cognitive PAN. The proposed protocol does not rely on the presence of a dedicated controller, the availability of a common control channel, or clock synchronization between the cognitive PAN and the new node. Furthermore, the CPAN need not suspend its operation for the discovery procedure to succeed. The performance of the proposed protocol is evaluated under fixed and adaptive superframe duration.

Capacity limits in a variable duty cycle IEEE 802.11p-based VANET

Abstract: In this paper, we investigate the capacity limits in a variable duty cycle VANET that uses the IEEE 802.11p standard. We show that the default value of duty cycle that allocates time equally between control and service channels leads to unbalanced performance and that the performance of typical traffic on those channels can be greatly improved by judicious choice of the value for duty cycle. We find the values of spatial density of vehicular traffic that lead to spatial saturation of network traffic. In addition, to model the distribution of the vehicles on the road segment, we used Poisson distribution, as well as Erlang-k distribution. Copyright © 2012 John Wiley & Sons, Ltd.

A two-tier integrated RFID/sensor network with a WiFi WLAN

Abstract: We investigate the coexistence of Wi-Fi (WLAN) and RFID/sensor networks that use IEEE 802.15.4 standard in the Industrial, Scientific and Medical (ISM) frequency band. To minimize the interference between the networks, a time scheduling scheme is combined with a sleeping scheme for RFID tags/sensors to further reduce the collision rate and energy consumption. We evaluate the performance of our solution under two different scenarios using discrete event simulation.

CSCD: A simple channel scan protocol to discover and join a cognitive PAN

Abstract: The paper describes a simple channel scan protocol through which a station can quickly discover and join an existing piconet following a specified channel-hopping MAC protocol piconet in its vicinity. The proposed MAC protocol is simple and does not need a dedicated control channel. Moreover, the cognitive piconet can operate normally throughout the search, unlike Bluetooth where piconet operation is temporarily suspended during the inquiry/inquiry scan procedure. The performance of the proposed protocol is evaluated through discrete event simulation.

Capacity limits in a variable duty cycle IEEE 802.11p-based VANET

Abstract: In this paper, we investigate the capacity limits in an variable duty cycle VANET that uses the IEEE 802.11p standard. We show that the default value of duty cycle that allocates time equally between control and service channels (CCH and SCH, respectively) leads to unbalanced performance, and that the performance of typical traffic on those channels can be greatly improved by judicious choice of the value for duty cycle. We also find the values of spatial density of vehicular traffic that lead to spatial saturation of network traffic.

Analyzing the Cost and Benefit of Pair Programming Revisited

Abstract: Pair programming has received a lot of attention from both industry and academia, but most paper focus on its technical aspects, while its business value has received much less attention. In this paper, we focus on the business aspects of pair programming, by using a number of software development related met rics, such as pair speed advantage, module breakdown structure of the software and project value discount rate, and augmenting them by taking into account the cost of change after the initial product release and inherent non-linearity of the discount rate curves. The proposed model allows for a more realistic estimation of the final project value, and the results of System Dynamics simulations demonstrate some useful insights for software development management.

Providing qos in the integration of RFID and wi-fi WLAN

Abstract: Radio Frequency Identification (RFID) systems are widely used in various application domains. However, when RFID networks are integrated with WiFi WLANs to extend their short transmission range, interference results due to the use of the same ISM frequency band, and some co-existence mechanism must be found. In this paper, we propose a time-sharing mechanism that allows RFID networks using IEEE 802.15.4 networks to connect to a WLAN that uses IEEE 802.11e EDCA for ensuring priority access for RFID data. To reduce collisions among RFID tags, we use an energy management mechanism based on randomized sleep. Simulation results show that the proposed solution achieves Quality of Service (QoS) by maintaining higher throughput and lower collision probability.

On intrusion detection in a neighbourhood area network in the smart grid

Abstract: Smart grid, which is an upgrade of power electric system, mainly relies on powerful communication networks to provide a secure, reliable and efficient information delivery. Updating a system as complex as the electrical power grid with a large number of components has the potential of introducing new security vulnerabilities into the system. Hence, security mechanisms should be deployed to protect the smart grid as a first wall of defence against malicious attacks. As a second wall of defence, there should be intrusion detection systems in place to protect the smart grid against any security breaches. In this work, we describe an anomaly-based intrusion detection system (IDS) for neighbourhood area network whose security is of critical importance in smart grid.