(1987). Applied Probability and Queues. Journal of the Operational Research Society: Vol. 38, No. 11, pp. 1095-1096.

https://link.springer.com/content/pdf/10.1057%2Fjors.1987.184.pdf

Applied Probability and Queues

/pdf/reversibility-and-stochastic-networks-17kl9p5ino.pdf

Reversibility and Stochastic Networks

We study a sensor node with an energy harvesting source. The generated energy can be stored in a buffer. The sensor node periodically senses a random field and generates a packet. These packets are stored in a queue and transmitted using the energy available at that time. We obtain energy management policies that are throughput optimal, i.e., the data queue stays stable for the largest possible data rate. Next we obtain energy management policies which minimize the mean delay in the queue. We also compare performance of several easily implementable sub-optimal energy management policies. A greedy policy is identified which, in low SNR regime, is throughput optimal and also minimizes mean delay.

Optimal energy management policies for energy harvesting sensor nodes

By broadcasting messages about traffic status to vehicles wirelessly, a vehicular ad hoc network (VANET) can improve traffic safety and efficiency. To guarantee secure communication in VANETs, security and privacy issues must be addressed before their deployment. The conditional privacy-preserving authentication (CPPA) scheme is suitable for solving security and privacy-preserving problems in VANETs, because it supports both mutual authentication and privacy protection simultaneously. Many identity-based CPPA schemes for VANETs using bilinear pairings have been proposed over the last few years to enhance security or to improve performance. However, it is well known that the bilinear pairing operation is one of the most complex operations in modern cryptography. To achieve better performance and reduce computational complexity of information processing in VANET, the design of a CPPA scheme for the VANET environment that does not use bilinear paring becomes a challenge. To address this challenge, we propose a CPPA scheme for VANETs that does not use bilinear paring and we demonstrate that it could supports both the mutual authentication and the privacy protection simultaneously. Our proposed CPPA scheme retains most of the benefits obtained with the previously proposed CPPA schemes. Moreover, the proposed CPPA scheme yields a better performance in terms of computation cost and communication cost making it be suitable for use by the VANET safety-related applications.

An Efficient Identity-Based Conditional Privacy-Preserving Authentication Scheme for Vehicular Ad Hoc Networks

VANet security challenges and solutions: A survey

Misbehavior detection schemes (MDSs) form an integral part of misbehaving node eviction in vehicular ad hoc networks (VANETs). A misbehaving node can send messages corresponding to an event that either has not occurred (possibly out of malicious intent), or incorrect information corresponding to an actual event (for example, faulty sensor reading), or both, causing applications to malfunction. While identifying the presence of misbehavior, it is also imperative to extract the root-cause of the observed misbehavior in order to properly assess the misbehavior's impact, which in turn determines the action to be taken. This paper uses the Post Crash Notification (PCN) application to illustrate the basic considerations and the key factors affecting the reliability performance of such schemes. The basic cause-tree approach is illustrated and used effectively to jointly achieve misbehavior detection as well as identification of its root-cause. The considerations regarding parameter tuning and impact of mobility on the performance of the MDS are studied. The performance of the proposed MDS is found to be not very sensitive to slight errors in parameter estimation.

Detecting misbehaviors in VANET with integrated root-cause analysis

A wireless Ad-hoc network is expected to be made up of energy aware entities (nodes) interested in their own perceived performance. An important problem in such a scenario is to provide incentives for collaboration among the participating entities. Forwarding packets of other nodes is an example of activity that requires such a collaboration. However, it may not be in interest of a node to always forward the requesting packets. At the same time, not forwarding any packet may adversly affect the network functioning. Assuming that the nodes are rational, i.e., their actions are strictly determined by their self-interest, we view the problem in framework of non-cooperative game theory and provide a simple punishing mechanism considering end-to-end performance objectives of the nodes. We also provide a distributed implementation of the proposed mechanism. This implementation has a small computational and storage complexity hence is suitable for the scenario under consideration.

/pdf/non-cooperative-forwarding-in-ad-hoc-networks-3s4dwrz66v.pdf

Non-cooperative forwarding in ad-hoc networks

https://www-sop.inria.fr/members/Eitan.Altman/PAPERS/comnet-miorandi-802p11.pdf

A queueing model for HTTP traffic over IEEE 802.11 WLANs

In any vehicular adhoc network, there is always a possibility of incorrect messages being transmitted either due to faulty sensors and/or intentional malicious activities. Detecting and evicting sources of such misbehavior is an important problem. We observe that the performance of misbehavior detection schemes will depend on the application under consideration and the mobility dynamics of the detecting vehicle. Further, the underlying tradeoff in any such detection algorithm is the balance between False Positives and False Negatives; one would like to detect as many misbehaviors as possible, while at the same time ensuring that the genuine vehicles are not wrongly accused.

In this work we propose and analyze (via simulations) the performance of a Misbehavior Detection Scheme (MDS) for Post Crash Notification (PCN) application. We observe that the performance of this proposed scheme is not very sensitive to the exact dynamics of the vehicle on small scales, so that slight error in estimating the dynamics of the detecting vehicle does not degrade the performance of the MDS.

Distributed Misbehavior Detection in VANETs

This paper is about analytical models for calculating the average bandwidth shares obtained by TCP controlled finite file transfers that arrive randomly and share a single (bottleneck) link. Owing to the complex nature of the TCP congestion control algorithm, a single model does not work well for all combinations of network parameters (i.e., mean file size, link capacity, and propagation delay). We propose two models, develop their analyses, and identify the regions of their applicability. One model is obtained from a detailed analysis of TCP's AIMD adaptive window mechanism; the analysis accounts for session arrivals and departures, and finite link buffers. It is essentially a processor sharing (PS) model with time varying service rate; hence we call it TCP-PS. The other model is a simple modification of the PS model that accounts for large propagation delays; we call this model rate limited-PS (RL-PS). The TCP-PS model analysis accommodates a general file size distribution by approximating it with a mixture of exponentials. The RL-PS model can be used for general file size distributions. We show that the TCP-PS model converges to the standard PS model as the propagation delay approaches zero. We also observe that the PS model provides very poor estimates of throughput unless the propagation delay is very small. We observe that the key parameters affecting the throughput are the bandwidth delay product (BDP), file size distribution, the link buffer and the traffic intensity. Several numerical comparisons between analytical and simulation results are provided. We observe that the TCP-PS model is accurate when the BDP is small compared to the mean file size, and the RL-PS model works well when the BDP is large compared to the mean file size.

/pdf/stochastic-models-for-throughput-analysis-of-randomly-4fzhg8uzk8.pdf

Arzad A. Kherani

Papers

Detecting misbehaviors in VANET with integrated root-cause analysis

Non-cooperative forwarding in ad-hoc networks

A queueing model for HTTP traffic over IEEE 802.11 WLANs

Distributed Misbehavior Detection in VANETs

Stochastic models for throughput analysis of randomly arriving elastic flows in the Internet