Amir Qayyum

Optimized link state routing protocol for ad hoc networks

In this paper we propose and discuss an optimized link state routing protocol, named OLSR, for mobile wireless networks. The protocol is based on the link state algorithm and it is proactive (or table-driven) in nature. It employs periodic exchange of messages to maintain topology information of the network at each node. OLSR is an optimization over a pure link state protocol as it compacts the size of information sent in the messages, and furthermore, reduces the number of retransmissions to flood these messages in an entire network. For this purpose, the protocol uses the multipoint relaying technique to efficiently and economically flood its control messages. It provides optimal routes in terms of number of hops, which are immediately available when needed. The proposed protocol is best suitable for large and dense ad hoc networks.

Multipoint relaying for flooding broadcast messages in mobile wireless networks

We discuss the mechanism of multipoint relays (MPRs) to efficiently flood broadcast messages in mobile wireless networks. Multipoint relaying is a technique to reduce the number of redundant re-transmissions while diffusing a broadcast message in the network. We discuss the principle and the functioning of MPRs, and propose a heuristic to select these MPRs in a mobile wireless environment. We also analyze the complexity of this heuristic and prove that the computation of a multipoint relay set with minimal size is NP-complete. Finally, we present some simulation results to show the efficiency of multipoint relays.

Performance evaluation of AODV and OLSR in highly fading vehicular ad hoc network environments

Vehicular Ad hoc Network (VANET) is a challenging network environment in which communication between vehicles in highly fading environments, like an urban scenario, is unpredictable and difficult. In order to analyze the performance of protocols and applications, network simulators like NS-2 use deterministic Two Ray Ground radio propagation model. This model, however, poorly reflects the channel characteristics of real world conditions. In this paper, probabilistic Nakagami radio propagation model is used to represent channel fading characteristics of urban scenarios. The performance analysis of two routing protocols, AODV and OLSR using Nakagami propagation model under high obstacle urban environment is presented. It is observed that both routing protocols fail to provide acceptable packet delivery ratio. Overall, OLSR, with short interval of control messages, performed better than AODV in urban environments.

VANET architectures and protocol stacks: a survey

Intelligent transportation systems (ITS) provide a set of standards for vehicular communications. The main focus of research activities, within ITS, has been on development of safety, traffic efficiency and infotainment related applications. Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications are the main research goals of ITS. This paper reviews some popular architectures of VANETs (Vehicular Ad hoc NETworks) i.e., WAVE by IEEE, CALIM by ISO, C2CNet by C2C consortium / GeoNet. It also includes some recent research regarding these standards, specially focusing on Network and MAC layer issues. This paper also discusses safety related application protocols, i.e. WSMP by WAVE, CALM FAST by ISO and C2CNet by C2C consortium. Various recommendations regarding the above protocol stacks are presented. The recommendations are based on different parameters like flexibility, implementation etc.

A Survey on Security in Vehicular Ad Hoc Networks

Vehicular Ad-hoc Networks (VANETs) are the most prominent enabling network technology for Intelligent Transportation Systems. VANETs provide many new exciting applications and opportunities albeit transportation safety and facilitation applications are their core drivers. Security of vehicular networks remains the most significant concern in VANETs deployment – because it is mandatory to assure public and transportation safety. In this paper, we review the various dimensions of VANETs security including security threats, challenges in providing security in vehicular networks environment, requirements and attributes of security solutions. We also provide taxonomy and critically review of the notable security solutions – available for VANETs in literature.

On End-to-End Mobility Management in 4G Heterogeneous Wireless Networks

With the advent of modern technology, mobile devices with multi homed capabilities are proliferating. Existence of different network interfaces in multi homed devices enables them to seamlessly roam across heterogeneous networks. These vertical handovers however, causes to affect the TCP connections. Many solutions exist that handle this problem caused by mobility of the nodes. However, current mobility management solutions either require support of additional entities in the network or require changes in current implementation of TCP. This paper argues that mobility management service can effectively be provided without requiring the support of additional entities in the network and without changing the current implementation of TCP. On the basis of this principle, we present an end-to-end mobility management framework (EMF) that overcomes the limitations of current mobility management solutions and provides a richer set of mobility services such as location updates, soft handover, willful handover, etc.

An Architecture for Exploiting Multihoming in Mobile Devices for Vertical Handovers & Bandwidth Aggregation

In recent years, mobile devices with multihoming capabilities i.e. equipped with multiple network interfaces have gained large scale popularity. This multihoming capability enables the mobile devices to connect with multiple diverse access networks simultaneously. However, networking protocol stack implemented in current devices is not capable of exploiting the availability of multiple network interfaces. Multihoming can be used to provide two important services: vertical handovers and bandwidth aggregation. Vertical handover enables a multihomed device to switch its connectivity from one access network to another access network without disrupting the communication session. Bandwidth aggregation enables multihomed device to achieve higher throughput by establishing simultaneous connections over multiple available network interfaces. A number of solutions have been proposed to exploit multihoming for vertical handovers and bandwidth aggregation. However, most of these solutions either require the support of additional network entities such as host agent, foreign agent, mobility gateway, proxy, etc. or they require changes in current widely deployed protocol stack in operating system kernels. Dependence on either network operator, administrator or operating system vendors hinders the large scale deployment of these solutions. This paper presents an end-to-end architecture that offers the vertical handover and bandwidth aggregation services to TCP applications. This architecture neither requires any additional network entity nor it requires the changes in current networking protocol stack in operating system kernels. The paper presents the design, implementation and performance analysis of the proposed architecture.

Protocol Independent Adaptive Route Update for VANET

High relative node velocity and high active node density have presented challenges to existing routing approaches within highly scaled ad hoc wireless networks, such as Vehicular Ad hoc Networks (VANET). Efficient routing requires finding optimum route with minimum delay, updating it on availability of a better one, and repairing it on link breakages. Current routing protocols are generally focused on finding and maintaining an efficient route, with very less emphasis on route update. Adaptive route update usually becomes impractical for dense networks due to large routing overheads. This paper presents an adaptive route update approach which can provide solution for any baseline routing protocol. The proposed adaptation eliminates the classification of reactive and proactive by categorizing them as logical conditions to find and update the route.

Evaluation OF IEEE 802.11n for Multimedia Application in VANET

Abstract WAVE by IEEE, CALM by ISO and Car-to-Car are the popular VANET architectures. These architectures mainly focus on safety applications. IEEE 802.11p is the IEEE recommended MAC and PHY layer standard for VANET. Different VANET pro- tocol stacks recommend this standard not only for the safety applications but also other applications. In this paper, we focus on Multimedia-based ad-hoc networking and WLAN aspects for VANETs. The use of Multimedia applications is increasing day by day. Applications like Voice over IP (VoIP), video conferencing, online gaming and file transfer etc. demand time bounded and high throughput services. To fulfill these demands in a vehicular environment, there is a need to evaluate the current IEEE VANET standard for MAC (IEEE 802.11p) to know its limitations for these applications and move towards exploration of a new standard. IEEE 802.11n claims high throughput up to 300Mbps and proved to be more suitable standard for multimedia applications. In this paper, we have evaluated IEEE 802.11p and IEEE 802.11n specifically for multimedia applications in VANET. Simulation results show, IEEE 802.11n comparatively performs better for multimedia applications in urban environment in low BER (bit error rate) as well as high BER as compared to IEEE 802.11p.

Review: Performance comparison of end-to-end mobility management protocols for TCP

Mobility management for TCP connections has been discussed in literature since last several years. Many mobility management solutions have been proposed including end-to-end solutions and infrastructure dependent solutions. These solutions operate at different layers of TCP/IP protocol stack. End-to-end mobility management solutions have the advantage of not requiring the deployment of additional entities in network infrastructure to handle mobility management as compared to the infrastructure dependant solutions. Performance analysis of these end-to-end mobility management protocols seems missing in literature. In this paper, we analyze the performance of different end-to-end mobility management protocols using mathematical modeling. Evaluation has been carried out for evaluating the handover delay, throughput degradation time and protocol overhead. Some security and implementation issues pertaining to these protocols have also been discussed. Results show that protocols that allow simultaneous communication through multiple network interfaces provide throughput stability during vertical handovers, thus facilitating smooth handovers.