Theses and Dissertations
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Item Open Access Application of network coding in wireless sensor and relay based ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2015) Singh, Dushyant; Pillutla, Laxminarayana S.Network Coding (NC) is a new area which brings radical change in the way we treat information flow in networks. NC considered being a layer 3 operation has been shown to improve the throughput of wired networks especially for broadcast and multicast traffic. Linear network coding (LNC) in which packets are combined using simple linear operations over finite fields can indeed achieve the multicast capacity. Random LNC (RLNC) is attractively used for distributed scenario where the codes are generated by various nodes in random fashion. The data dissemination latency scales as O(N2) (N is the number of nodes) in naive broadcast scenario. However with RLNC the data dissemination latency scales between O(N) and O(N2) depending on the network connectivity. NC is at the heart of two problems that we have considered in this thesis. Firstly we consider collaborative distributed indoor target tracking using wireless sensor networks (WSNs) where we show how RLNC can be used for effective information dissemination and analyzed its impact on tracking performance for the case of indoor target tracking. Our simulation results demonstrate that for a target root mean square (RMS) value of tracking error the RLNC scheme would require less number of time slots in comparison with the two competing schemes. Secondly we consider the performance of NC in relay assisted contention based ad hoc networks considered like the IEEE 802.11 compliant ones. We specifically show as how MAC layer NC can be used at both relay, source & destination nodes to improve throughput in contention based wireless networks. Our simulation results demonstrate an increment in system throughput by 15-20% for the case with NC.Item Open Access Analysis of address allocation protocols for mobile ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2011) Sati, Mohit; Srivastava, Sanjay; Divakaran, SrikrishnanIn almost all networks, it is necessary to have a unique identifier for each node. This identifier is used to find out route locating a particular node. So an address is must for any node for unicast communication. Addresses can be preconfigured manually or can be assigned dynamically using a server (e.g. DHCP server). Manual configuration of ad hoc network is not possible for large scale networks. And setting up a server is not possible due to lack of infrastructure in Ad Hoc Networks. So it is necessary to have a mechanism by which we can allocate addresses to the nodes dynamically without any prior setup. Lack of infrastructure and mobility of nodes makes address allocation a challenging task in MANET. We present worst case message complexity analysis of a number of proposed address allocation protocols, which can be useful for estimating upper bounds for overhead and latency involved in address allocation as well as partitioning and merging. We also show that the worst case analysis is not a useful indicator of real world performance of the protocols. Buddy approach [5] is one of the many proposed approaches for address allocation. We model DPDA (A Distributed Protocol for Dynamic Address assignment in mobile ado networks)[6], a protocol based on buddy approach, to estimate the overhead involved in address allocation. We conduct simulations in NS-2 and compare with analytical results to validate our model. We perform simplified simulations using Python script which also validates the proposed model. We also do a simulation based comparison of MANETconf (MANET configuration) [8] and DPDA[6] in term of overhead and latency in address allocation, which shows that DPDA causes lower communication overhead and latency than Manetconf.Item Open Access Secure data delivery in mobile ad hoc network using multiple paths(Dhirubhai Ambani Institute of Information and Communication Technology, 2011) Maheshwari, Mayur; Das, Manik LalA mobile ad hoc network (MANET) is a self configurable, self organized, infrastructure less multi hop mobile wireless network.Characteristics of ad hoc network make security a critical issue i.e. any node can join the network without revealing its presence as well as any node can behave in either a passive way (eavesdropping the message) or in an active way (manipulating the message, signal interference or jamming the network). When a node has some confidential information needed to transmit to other node, it needs some secure data delivery protocols such that, information can reach to intended node confidentially without tempered. We have studied two secure data delivery protocols namely SPREAD and Xia et al‟s scheme. These protocols focus on how to deliver a secret message over insecure MANET using multiple paths. These protocols provide confidentiality and robustness but don‟t focus on authentication and integrity. Due to the lack of authentication, any node can impersonate the good node or the intermediate node can manipulate message and no one can detect this misbehaviour. We have proposed a scheme that aims to provide confidentiality, authentication, and robustness for a message when they are delivered across the insecure MANET. We have used the concept of SPREAD, where message transforms into multiple shares and then delivers the shares via multiple independent paths to the destination, so that if a small number of nodes that are used to relay the message shares are compromised, the whole message is not compromised. We are using basic idea of TESLA to provide authentication. Finally, when we analyzed our proposed protocol and compared it with SPREAD. Our analysis showed that the proposed scheme provides all basic security objectives as well as it protects against data tempering, impersonation, replay and known session key attacks.Item Open Access Packet forwarding strategies for cooperation enforcement in mobile wireless ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2011) Patel, Nidhi; Muthu, RahulIn self-organized ad hoc networks, all networking functions rely on the contri- bution of the relay nodes. Nodes have to forward packets for each other in order to enable multi-hop communication. In recent years, researchers have identi ed the problem of stimulating cooperation in ad hoc networks and proposed several solutions to give nodes incentive to contribute to common network services. These solutions are based on incentive mechanisms like reputation based system or virtual currency based system. This paper aims at determining conditions under which, such cooperation without incentives can exist, while taking the network topology into account. We have focused on the most basic networking mechanism, namely, packet forwarding and proposed a game theoretic approach for achieving cooperation. We have de ned a game model where nodes act as players, their actions (forward or drop a packet) de ne strategies and they are given payo s based on the payo functions designed in terms of network parameters. We have considered di erent parameters for simulation like tramsmission range, di erent strategies, initial condition of nodes, energy cost for sending or forwarding packets, tra c rate, noise e ect, mobility, etc. Our simu- lation result shows how cooperation is achieved in network with nodes getting better payo s. Later we have extended our work to cover network with mobile nodes.Item Open Access Testbed based experimental analysis of transport protocols over wireless ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Shah, Harshil Anilkumar; Srivastava, SanjayAd hoc networks are networks with no infrastructure and self-organized in nature. ad hoc networks allow nodes to form network when they come into range of each other provided nodes are configured in ad hoc mode. But these types of network are challenges like high bit error rates, route failures due to mobility, high noise, signal fading and low speed etc. to deal with. Due to this, protocols which are widely used in traditional wired networks may not perform well in MANETs. lower layers like MAC and network layer are either completely changed like 802.11 instead of 802.3 at MAC layer and introducing reactive routing protocols instead of only proactive routing at network layer or significant improvement schemes have been proposed for wireless networks in the existing legacy wired network protocols. But transport layer in MANET is mostly similar to wired networks except some improvements like TCP-ELFN and TCP-Feedback and new transport protocols like Ad hoc-TCP (ATCP), Transport Protocol for Ad hoc networks (TPA) and Ad-hoc Transport Pro- tool (ATP).performance degradation of TCP over wireless links is mainly due to wireless characteristics, TCP features like self-clocking, loss based congestion control, coupling of congestion and reliability, slow start. Several studies have been carried out to evaluate performance of TCP over MANETs but most of them are simulation based studies. But as simulation scenarios can not model exactly the unpredictable nature of wireless environment, we have decided to analyze performance of trans- port protocols over experimental test bed which can be more accurate evaluation of protocols in real-life situation. Performance of 2 transport protocols is analyzed.Item Open Access Cache performance evaluation in DSR protocol through cross-layering for mobile ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Sharma, Kapil; Sunitha, V.Wireless mobile ad-hoc networks are being actively studied by many researchers these days. These networks are suitable to be used in various situations because of (i) their infrastructure-less property and (ii) the mobility of the nodes of the network. However, it is these features which give rice to problems in study of such networks. Further, routing is one of the basic issues in any network design. Inclusion of moving capability to the nodes, make the routing problem more complicated. One is always interested in increasing the throughput and reducing overhead while at the same time solving the issues related to routing. DSR is a protocol that is extensively used for routing in such networks. Cache management and route caching play a significant role in using DSR successively to attain the best behavior for these networks. This thesis looks at and suggests some methods for route caching in DSR.Item Open Access Cooperation enforcement mechanisms in wireless adhoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Chaturvedi, Manish Shivshankar; Srivastava, SanjayWireless adhoc networks are autonomous, infrastrutureless networks where there are no dedicated routers or base stations and nodes are expected to cooperate in Wireless performing routing duties to keep network connected. Cooperation can be assumed if all nodes belong to single authority (e.g. military service or disaster management). But in applications where nodes do not belong to single authority and have limited resources (energy of battery driven devices), like pervasive computing or ubiquitous computing environment, one can not deny possibility of node selfishness. Also as there is no central authority to control node behavior, one can not deny possibility of node maliciousness. Many cooperation enforcement schemes are proposed in literature, and every scheme is shown to perform better under its own set of assumptions. These assumptions are different for different schemes. So, we aim at defining common set of assumptions and comparing selected schemes on this common ground with respect to packet delivery ratio, energy consumption, routing and other control overhead. We find that with the traffic scenario where nodes do not need services of one another at the same time, the cooperation schemes are not effective in dealing with node selfish ness. We also find that, while dealing with malicious nodes, all cooperation schemes perform better than Dynamic Source Routing(DSR) protocol in improving packet de- livery ratio(PDR), but this improvement comes at the cost of significant increase in routing control packets overhead and energy consumption of cooperation enforcement schemes is higher than that of DSR. Also they fail in punishing misbehaving nodes and the PDR of malicious nodes is comparable to that of good nodes.Item Open Access Analysis of address allocation protocols for mobile ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Sheth, Kavan J.; Srivastava, SanjayIn almost all networks, it is necessary to have a unique identifier for each node. This identifier is used to find out route locating a particular node. So an address is must for any node for unicast communication. Addresses can be preconfigured manually or can be assigned dynamically using a server (e.g. DHCP server). Manual configuration of ad hoc network is not possible for large scale networks. And setting up a server is not possible due to lack of infrastructure in Ad Hoc Networks. So it is necessary to have a mechanism by which we can allocate addresses to the nodes dynamically without any prior setup. Lack of infrastructure and mobility of nodes makes address allocation a challenging task in MANET. We present worst case message complexity analysis of a number of proposed address allocation protocols, which can be useful for estimating upper bounds for overhead and latency involved in address allocation as well as partitioning and merging. We also show that the worst case analysis is not a useful indicator of real world performance of the protocols. Buddy approach [5] is one of the many proposed approaches for address allocation. We model DPDA (A Distributed Protocol for Dynamic Address assignment in mobile ado networks)[6], a protocol based on buddy approach, to estimate the overhead involved in address allocation. We conduct simulations in NS-2 and compare with analytical results to validate our model. We perform simplified simulations using Python script which also validates the proposed model. We also do a simulation based comparison of MANETconf (MANET configuration) [8] and DPDA[6] in term of overhead and latency in address allocation, which shows that DPDA causes lower communication overhead and latency than Manetconf.Item Open Access Identifying small world network properties in ad-hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Garg, Neha; Sunitha, V.Small World Network is a densely connected network with low degree of separation. These types of networks have high clustering property like regular network as well as have low average path length like random network. Thus, Small World Networks are both Locally and Globally ecient as compared to other networks. The above prop- erties can be described using parameters like characteristic path length (L), clustering coefficient (C), local efficiency (Eloc) and global efficiency (Eglob). Through experiments, done in the past, it has been found that many real world networks exihibit the properties of small world network. This has given rise To finding models for real world networks so that the models reflect small world ness of the real world network. This thesis uses the model of converting a square grid into a small world model by introducing some special nodes. The equations to compute the small world parameters for this model with one and or two special nodes derived in this thesis.Item Open Access Comparative study between exponential back off and dynamic waiting strategies for medium access in wireless ad hoc networks(Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Shah, Rahul; Srivastava, SanjayIEEE 802.11 DCF (IEEE 802.11 Distributed Coordination Function) is widely used MAC protocol for wireless channel access. Although it is developed for single hop networks where all nodes are in the same radio range, it can be directly used for wireless multiphop hoc networks. But performance of IEEE 802.11 DCF in wireless ad hoc networks suers as it has been developed considering single hop networks only. Many amendments has been proposed to enhance its performance in multihop ad hoc networks. One such scheme is DWMAC (Dynamic Waiting Medium Access Control). In this work, performance of IEEE 802.11 DCF and DWMAC are compared for different network scenarios and traffic patterns. It has been observed that the performance of DWMAC can be further improved if we alter the restricted mode operation of the nodes. We have proposed a new modified protocol DWMAC-Modied and have shown by simulations that DWMAC-Modied offers singnificant improvements.