Arun Prakash

Spectrum handoff in cognitive radio networks

The rapid progression in wireless networking has raised the demand of extra spectrum bands. The current fixed spectrum allocation policy used by the government agencies is unable to accommodate the growing demand of the wireless networks. The research in cognitive radio networks is envisaged to solve the problem of spectrum scarcity and inefficiency in spectrum usage. Hence, cognitive radio networks are providing high attention to wireless community which allows the dynamic use of the underutilized spectrum. The dynamic use of the available unutilized spectrum can be done by spectrum handoff. An extensive work has been carried out in the field of spectrum handoff for cognitive radio networks to fulfill the growing demand of extra spectrum. At present, there is no standardization, detailed classification and comprehensive survey exist for spectrum handoff schemes. This paper presents a detailed classification and comprehensive survey of existing spectrum handoff schemes for cognitive radio networks. The spectrum handoff schemes are classified into various categories which provide an overview of the active research initiatives in the area of spectrum handoff. On the synthesis of available spectrum handoff schemes, various research issues and challenges are also presented which require the attention of the researchers.

Machine-to-Machine (M2M) communications

Machine-to-Machine (M2M) communication is a promising technology for next generation communication systems. This communication paradigm facilitates ubiquitous communications with full mechanical automation, where a large number of intelligent devices connected by wired/wireless links, interact with each other without direct human intervention. As a result, M2M communication finds applications in wide areas such as smart grids, e-healthcare, home area networks, intelligent transportation systems, environmental monitoring, smart cities, and industrial automation. However, distinctive features in M2M communications form different challenges from those in human-to-human communications. These challenges need to be addressed, or otherwise it is not easy for this paradigm to gain trust of people. To understand M2M communications deeply, this paper presents a comprehensive review of M2M communication technology in terms of its system model architecture proposed by different standards developing organizations. This mainly includes 3GPP, ETSI, and oneM2M. Further, we have investigated distinctive features of various M2M applications and their supporting attributes, the M2M data traffic and their characterization, various M2M standardization bodies and their unique tasks, and potential M2M communication challenges and their proposed state-of-the-art solutions, followed by future research directions.

Medium access control protocols for safety applications in Vehicular Ad-Hoc Network

Vehicular Ad-Hoc Network (VANET) is seen as an emerging solution to improve road safety, highway assistance and traveler comfort accounting to vivid applications including safety, non-safety and infotainment applications. Over the past few years, research paradigm has shifted towards areas such as multi-hop broadcasting, information security, clustering, etc. covering intra-vehicular and vehicle-to-infrastructure communication modes. Whereas these scenarios provide diversified information dissemination techniques through various applications of Intelligent Transportation Systems (ITS), data dissemination in VANET environment is still a challenging task, mainly due to rapid changes in network topology and frequent disruptions in connectivity. A distinguished area that still lacks significant research contributions is towards designing reliable and efficient Medium Access Control (MAC) protocols for vehicular communication in order to enhance travel safety. The main motivation behind such a survey is to integrate a wide range of research contributions that have been recently proposed to envisage the inherent characteristics of vehicular communication. Such a study serves as a reference for an in-depth research towards enhancements in the PHY/MAC layers. In this paper, we present state-of-the-art survey of the MAC protocols available for vehicular safety. We classify these protocols based on different applications and the techniques they adopt. We also review the performance metrics used for evaluating these protocols. In later sections, we qualitatively analyze the protocols based on different parameters along with related issues and the challenges they generate. We highlight the mechanisms involved, conceptual features, optimization techniques, strength and drawbacks of the available protocols as well as their applicability in future deployment. Finally, we discuss the open issues and future research directions.

Vehicle assisted cross-layer handover scheme in NEMO-based VANETs (VANEMO)

The combination of VANET and NEMO is termed as VANEMO. In this paper, we propose the use of ad hoc communications between vehicles in VANEMO to assist seamless NEMO handover in vehicular scenario. Using cross-layer information, a vehicle which is undergoing handover process, can take assistance from other vehicles in the ad hoc region to reduce handover latency as well as to minimise packet loss during handover. Using other vehicles assistance, a handover vehicle can get the router advertisement of the next access point before actual handover takes place. Thus, it can configure its new care-of-address on the fly, resulting in considerable reduction in handover latency. At the same time, another vehicle in the ad hoc region may assist in receiving packets destined for handover vehicle, resulting in minimisation of packet loss during handover period. The main contribution of this paper is to optimise handover latency and minimise packet loss based on the uses of mixed ad hoc and infrastructure communications, thus enabling vehicle to infrastructure communications to be improved. The proposed solution is characterised and evaluated through extensive simulation, showing that it provides an efficient handover in vehicular communications.

Multiple Mobile Routers Based Seamless Handover Scheme for Next Generation Heterogeneous Networks

Next generation heterogeneous networks require an effective handover scheme, optimized specially to support network mobility. The paper proposes an architecture to support seamless mobility of mobile networks across heterogeneous networks. We consider the vehicular scenario where a vehicle is provided with mobility through different Internet service providers (ISPs) and propose to use multiple mobile routers based handover scheme in vehicles. We carry out comparative performance evaluation of the handover performance of the proposed scheme in regard to UDP and TCP throughput, and signaling overhead. Moreover, we analyze the impact of vehicle speed and overlapping distance of access routers on packet loss. The simulation results show that the proposed scheme provides a mobile network with seamless mobility across heterogeneous networks and significantly reduces packet loss during handover.

A Cross Layer Seamless Handover Scheme in IEEE 802.11p Based Vehicular Networks

In this paper, we propose a seamless handover scheme for Network Mobility (NEMO) in vehicular scenario assisted by IEEE 802.11p based ad hoc communications among vehicles. The proposed scheme reduces handover latency and minimizes packet loss during handover by utilizing cross layer information available from other vehicles in the ad hoc manner. The role of neighboring vehicles assistance to the handover vehicle is twofold. First is to get the router advertisement of the next access point in advance to actual handover, resulting in considerable reduction in handover latency. Second is to receive packets destined for handover vehicle, thus minimizing packet loss during handover period. The extensive simulation study reveals that the proposed handover scheme provides seamless network mobility handover in vehicular communication scenario.

Extended Mobile IPv6 route optimization in nested mobile networks

Route optimization support in mobile networks is one of the most important concerns in Next Generation Networks (NGNs). NGNs require an efficient route optimization scheme, optimized specially to support nesting of mobile networks. We propose an Extended Mobile IPv6 route optimization (EMIP) scheme to enhance the performance of nested mobile networks. EMIP scheme is based on MIPv6 route optimization and the root Mobile Router (MR) performs all the route optimization tasks on behalf of all active Mobile Network Nodes (MNNs). Thus, the network movement remains transparent to sub MRs and MNNs. It modifies only MRs and MNNs leaving other entities untouched and is more efficient than the Network Mobility Basic Support protocol (NEMO BS). We carried out extensive simulation study to show that EMIP performs better than NEMO BS and Reverse Routing Header (RRH, a well established route optimization protocol) with respect to TCP throughput and round trip time. EMIP effectively reduces unnecessary large travelling route and overhead, thereby enhances performance. It also achieves route optimization between the mobile network nodes inside nested mobile network.

Vehicular ad hoc networks toward Intelligent Transport Systems

As a prospective intelligent transport systems (ITS) technology, vehicular ad hoc networks (VANETs) have recently been attracting an increasing attention from both research and industry communities. These networks have no fixed infrastructure and instead rely on vehicles themselves to provide network functionality. In this paper we review the related literature on VANETs characteristics and provide more insight on multi-hop inter-vehicle communication. We explore VANETs with respect to key enabling technologies ranging from physical radio frequency, MAC/PHY layer, routing strategies, security and privacy to mobility modeling and simulation study. Then we outline current state of research and open issues.

Clustering based cognitive MAC protocol for channel allocation to prioritize safety message dissemination in vehicular ad-hoc network

Abstract With the rising demand for vehicular networking through wireless communication for safety as well as non-safety applications, the urge to provide efficient bandwidth utilization along with reliable data delivery is rising significantly. Apparently, various communication services and applications are falling short of radio frequencies to be assigned to them. In addition to that, the IEEE 802.11p standard to enable wireless access in vehicular communication on DSRC frequencies is known to yield insufficient spectrum for reliable exchange of information over congested channels. To address these issues, this paper presents a clustering based cognitive MAC (CCMAC) protocol which allows dynamic allocation of channels in the band adjacent to the DSRC band, known as 5.8 GHz U-NII-3/ISM band. The novelty of CCMAC lies in exploiting the free unlicensed band thereby, eliminating the concept of primary and secondary user. For this purpose, we introduce mobility aware clustering based channel allocation protocol that proactively monitors the channel sensing outcomes. Using these results, vehicles access information about spectrum availability prior to transmission. The protocol ensures immediate channel access to safety messages within DSRC band at the cost of non-safety messages which are switched to U-NII-3/ISM band when falling short of channel access in the DSRC band. This not only results in alleviating access delay but also renders efficient channel utilization. The results demonstrate the effectiveness of the CCMAC protocol in allocating real-time and scalable spectral resources, fast and efficient reception of safety messages compared to existing schemes, and in alleviating the operation of safety application based services in VANET.

A seamless handover scheme for vehicles across heterogeneous networks

Next generation heterogeneous networks require an effective handover scheme, optimised specially to support network mobility. The paper proposes an architecture to support seamless mobility of mobile networks across heterogeneous networks. We consider the vehicular scenario where a vehicle is provided with mobility through different internet service providers (ISPs) and propose to use multiple mobile routers-based handover scheme in vehicles. The multiple mobile routers architecture is extended to include multiple home agents (HAs) where each HA belongs to different administrative domains. We carry out comparative performance evaluation of the handover performance of the proposed scheme in regard to UDP and TCP throughput, service disruption time, and signalling overhead. Moreover, we analyse the impact of vehicle speed and overlapping distance of access routers on packet loss during handover period. The simulation results show that the proposed scheme provides a mobile network with seamless mobility across heterogeneous networks. The overlapped reception of packets from different access routers significantly minimises packet losses during handover even without reducing handover latency.