Chhagan Lal

A Node-Disjoint Multipath Routing Method Based on AODV Protocol for MANETs

Frequent link failures are caused in mobile ad-hoc networks due to nodes mobility and use of unreliable wireless channels for data transmission. Due to this, multipath routing protocols become an important research issue. In this paper, we propose and implement a node-disjoint multipath routing method based on AODV protocol. The main goal of the proposed method is to determine all available node-disjoint routes from source to destination with minimum routing control overhead. With the proposed approach, as soon as the first route for destination is determined, the source starts data transmission. All the other backup routes, if available, are determined concurrently with the data transmission through the first route. This minimizes the initial delay caused because data transmission is started as soon as first route is discovered. We also propose three different route maintenance methods. All the proposed route maintenance methods are used with the proposed route discovery process for performance evaluation. The results obtained through various simulations show the effectiveness of our proposed methods in terms of route availability, control overhead, average end-to-end delay and packet delivery ratio.

Performance analysis of MANET routing protocols for multimedia traffic

Providing requisite Quality of service (QoS) guarantees in wireless multi-hop networks is much more challenging than in wired networks. This is mainly due to its dynamic topology, distributed nature, interference, multi-hop communication and contention for channel access. In particular, it is important for routing protocols to provide QoS guarantees by incorporating metrics like achievable throughput, delay, jitter, packet loss ratio, etc. In this paper, we present comparative analysis of mobile ad-hoc routing protocols over real time video streaming. Our analysis exploits the built-in support for real time multimedia streaming in MANETs. We use H.264/SVC encoded video sequences to evaluate the performance of various routing protocols over a large number of scenarios in terms of throughput and end-to-end delay. Effects of changes in mobility, network scalability and network load are evaluated and presented. Our results show that it is possible to stream some multimedia applications with acceptable quality over MANETs within limited mobility, QoS and network size.

JellyFish attack

Mobile ad hoc networks (MANETs) are vulnerable to various types of attacks due to inherently in-secure wireless communication medium and multihop routing communication process. In this paper, we analyze the behavior and impact of JellyFish attack over TCP-based MANETs. We have implemented and evaluated all three variants of JellyFish attack namely JF-reorder, JF-delay and JF-drop through simulation processes. These attacks exploit the behavior of closed loop protocols such as TCP and disturb the communication process without disobeying any protocol rules, thus the detection process becomes difficult. Consequently, traffic is disrupted leading to degradation in network throughput. Through extensive simulation results that are obtained using an industry standard scalable network simulator called EXata-Cyber, impact of these attacks in terms of network throughput, overhead incurred and end-to-end delay is analyzed and used for devising detection and countermeasure. We have proposed a light-weight direct trust-based detection (DTD) algorithm which detect and remove a JellyFish node from an active communication route. In our proposed DTD algorithm, each node uses locally calculated trust values which are collected over a time period to identify whether its neighbor node is a JF-attacker or not.

Bandwidth-aware routing and admission control for efficient video streaming over MANETs

In this paper, we develop and evaluate an adaptive self-configurable routing framework that can deal with dynamic nature of mobile ad hoc networks and provides quality-of-service (QoS) guarantees for efficient video streaming. Proposed framework mainly consists of two major components. Firstly, it is a reactive bandwidth-aware node-disjoint multipath routing protocol which determines routes based on the specified bandwidth requirements of the requesting application. The second component of the framework is a session admission control (SAC) process that permits or denies a session to enter into the network based on the current availability of network bandwidth. We also propose methods to handle QoS violations caused by network mobility and congestion by keeping backup routes, performing local route recovery, avoiding routing through short-lived low quality links and periodic monitoring of the active transmission routes. To verify our proposed algorithms, the network with H.264/SVC encoded video traces which are generated from real-time video traffic is used for modeling the behaviour of the source nodes. It has been observed that reactively discovered and maintained routes on the basis of the most recent information about network topology and available resources can significantly improve the admission decision accuracy of SAC process, in turn improving the quality of received video traffic significantly.

Impact analysis of JellyFish attack on TCP-based mobile ad-hoc networks

Tremendous increase has been seen in the number of application areas of mobile ad-hoc networks (MANETs) in recent years owing to the advancements in hardware of hand- held devices and wireless network deployment technologies. As a result, providing security in these kinds of networks has become central concern for researchers. In this paper, we analyze the behavior and impacts of JellyFish attack over TCP-based MANETs. We implement and evaluate three variants of JellyFish attack namely JF-reorder, JF-delay and JF-drop. JellyFish attack exploits the behavior of closed loop protocols such as TCP and performs the attacks without disobeying any rules of the protocol. Consequently, it causes ruinous effects and becomes difficult to detect due to its protocol compliance nature. This paper provides the complete simulation study of JellyFish attacks on three TCP variants known as TCP-Tahoe, TCP-SACK and TCP-NewReno. The simulations have been taken in the light of throughput, number of JF nodes and number of retransmissions. The paper contributes to the field of denial of service (DoS) attacks in MANETs by giving a comparative analysis of three TCP variants and discovers which TCP variant performs best under different variants of JellyFish attack. In addition to this, our simulation results also shed some light on the seriousness of the attacks caused by JF nodes and their effects on data communication.

QoS-aware routing for transmission of H.264/SVC encoded video traffic over MANETs

Efficient and reliable video streaming over mobile ad-hoc networks (MANETs) is a challenging task due to the varying characteristics of wireless networks and video traffic. Therefore, these kinds of applications require quality-of-service (QoS) support. Although, many QoS provisioning solutions are reported in the past but none of them are tested on video traffic and also affects of mobility and variations in link quality are not addressed properly. In this paper, we proposed an efficient QoS-aware routing protocol (QARP) which uses the cross-layer communication (CLC) and session admission control (SAC) methods to provide QoS guarantees in terms of network bandwidth. In QARP, we perform QoS-aware route discovery by considering the effects of both inter-contention and intra-contention during the route discovery phase. Only data sessions for which a route with required bandwidth is discovered are admitted into the network by our SAC process. Existing periodic message structures are extended for exchange the QoS states of nodes to minimize the affect of mobility in our QoS-aware routing method. Furthermore, two methods are proposed to handle the QoS violations caused by dynamic characteristics of video traffic and network mobility during data communication. To stress the network with real time multimedia traffic, we use trace files generated from real time video files that are encoded using H.264/SVC encoder.

Video streaming over MANETs: Testing and analysis using real-time emulation

In this paper, we design and deploy a Mobile Ad hoc Network (MANET) testbed that is integrated with EXata-Cyber network emulator to evaluate the performance of real-time video streaming applications. EXata-Cyber can unvaryingly connect emulated networks (virtual networks created by EXata-Cyber) to real machines. Thus, in our testbed, real machines can exchange real-life applications traffic over emulated wireless networks consisting of virtual machines. With the emulation capabilities of EXata-Cyber, our developed testbed gives an efficient, high fidelity and accommodating testing terrain for analyzing the performances and behaviors of real-life applications, machines and MANET routing protocols. We evaluate the performance of both proactive and reactive routing protocols while transmitting real-time video traffic in terms of change in network load, network mobility and video streaming bit rate. Furthermore, to provide accurate measures for perceived video quality at users end in the form of Quality-of-Experience (QoE), we evaluate and analyze metrics such as Mean Opinion Score (MOS), Signal-to-Interference and Noise Ratio (SINR) and Packet Delivery Ratio (PDR) at various layers of TCP/IP protocol stack.

An adaptive cross-layer routing protocol for delay-sensitive applications over MANETs

In this paper, we present an adaptive delay-aware multipath routing (ADAMR) framework for reliable transmission of delay-sensitive applications over mobile ad-hoc networks (MANETs). The proposed method uses cross-layer design to abstract the Quality-of-Service (QoS) constraints of requesting applications in terms of end-to-end delay. To ensure that each admitted data session packet gets the required delay, we use an adaptive flow admission control technique. The proposed admission control procedure admits only those data sessions for which our multipath routing protocol is able to find a delay-aware route. Proposed multipath routing protocol not only discovers routes that satisfy the given delay constraints, but also makes sure that the discovered routes are node-disjoint. When a link break is detected on an active route, we use backup route to bypass another overhead generating route discovery process. Extensive simulations prove the effectiveness of the proposed approach under various network scenarios. We use H.264/SVC encoded video traces to model the video source nodes in the network. The proposed method provides required QoS guarantees and perform congestion control based on the current network load levels. It is also observed from simulation results that ADAMR performs accurate admission control and discovers stable multiple node-disjoint routes with minimal routing overhead.

A Rate Adaptation Scheme to Support QoS for H.264/SVC Encoded Video Streams over MANETs

In recent years, the developments in wireless handheld devices and networking offers the technical platform for multimedia streaming over mobile ad-hoc networks (MANETs). However, providing QoS for multimedia streaming is quite difficult in MANETs due to its physical and organizational characteristics. Due to the high data rate and frame size of multimedia traffic there are times when offered load exceeds the available network capacity. This causes packet drops due to congestion and router input queue overflow. In this paper, we propose a cross layer rate adaptation scheme that provides required rate adaptation between applications transmission rate and network bandwidth. The proposed scheme uses the classical dual leaky bucket (DLB) algorithm to regulate the traffic flow with guaranteed QoS in terms of end-to-end delay. Furthermore, our scheme avoid the congestion in network by controlling the traffic flow of video sequences, this increases the overall network throughput. Our scheme uses the encoding information with QoS requirements of data session (i.e. video stream) provided by application layer to regulate the flow according to the available network resources. We validate our scheme in scenarios where different network size and node mobility degrees are tested in order to show the benefits offered by our scheme. We have used the latest coding standard H.264/SVC video traces to simulate video sources. The quality of received video is measured in terms of network metrics such as end-to-end delay, jitter and packet loss ratio.

Analysis of a Traffic Classification Scheme for QoS Provisioning over MANETs

Differentiated services (DiffServ) is a networking framework. It classifies traffic using differentiated service code point (DSCP) field in packet header at network layer. Each traffic class is mapped with some priority queue that differs from other priority queues in terms of provided throughput and delay. In this paper, we modify the existing DiffServ model in Qualnet simulator so that it suits the dynamic nature of MANETs. We analyze the enhanced DiffServ architecture by configuring each node in such a way that it works as ingress as well as core node. The effectiveness of the traffic classification scheme in terms of network scalability and data rate is analyzed and compared against the best effort traffic method over MANETs for video, audio and plain data. Simulation results obtained for Diffserv enabled networks are compared with Diffserv disabled ones, evaluation metrics being delay and packet delivery ratio. Simulation result shows a reasonable improvement in all QoS metrics, if DiffSersv is enabled in network.