Theses and Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/1

Browse

Subject: search.filters.subject.Mobile ad-hoc networks

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    ItemOpen 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, Srikrishnan
    In 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.
  • Thumbnail Image
    ItemOpen 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, Sanjay
    Ad 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.
  • Thumbnail Image
    ItemOpen 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.
  • Thumbnail Image
    ItemOpen Access
    Analysis of address allocation protocols for mobile ad hoc networks
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2009) Sheth, Kavan J.; Srivastava, Sanjay
    In 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.
  • Thumbnail Image
    ItemOpen 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.
  • Thumbnail Image
    ItemOpen Access
    Queueing-theoretic framework for perfermance analysis of mobile ad hoc networks with finite buffer nodes
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2008) Shah, Sapan; Lenin, R. B.; Srivastava, Sanjay
    Wireless Ad Hoc network is a decentralized wireless network which allows nodes to join and create networks without any infrastructure. These kinds of networks are advantageous because they can be readily deployed anywhere, anytime. Mobile Ad Hoc Network (MANET) is a special type of ad hoc network where nodes are mobile. Due to mobility of the nodes, network topology may change rapidly and unpredictably. MANETs are expected to plat a vital role in a variety of applications and are therefore studied extensively. It is imperative to analyze these networks, to assess the suitability of their use in different scenarios and to identify the techniques to improve their performance. In last few years, many models have been proposed to analyze MANETs. Many of then have an unrealistic assumption of an infinite buffer in each node. Moreover, in MANETs, as nodes are mobile, a packet may revisit the same node which creates feedback loops of a packet. These loops make modeling and analysis of MANETs difficult as the network becomes cyclic. This work analyzes MANET with finite buffer nodes. Open finite queuing network with gated queue, intermittent links and servers is used. The expansion method technique has been used to study the open finite queuing network with stable links and servers. We modify the method for intermittency. Numerical results are derived and compared with simulation results to show effectiveness of the method.
  • Thumbnail Image
    ItemOpen Access
    Mobility aware MANET routing protocol using cross layer design
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2006) Patel, Komalben; Srivastava, Sanjay; Lenin, R. B.
    Mobile Adhoc Network (MANET) is a dynamic network with time varying topology and time varying network resources. Due to the error-prone wireless channel and high mobility, traditional protocols of wired networks cannot be successfully applied to MANETs. The popularity of mobile and hand held devices equipped with wireless interface is creating a new challenge for Quality of Service. The wired network has also not been able to fulfill end-to-end guarantees. Due to the nature of MANETs, achieving the same end-to-end guarantees is very difficult. The mobility rate makes the task dicult. The aim is to fight against the losses caused due to mobility. This work attempts to build stable paths so as to counter the effects of mobility induced route failures. Using the Cross Layer Approach, the signal strength of the link from the MAC Layer is captured and used at the network layer. Upon receiving the signal strength values, the network layer carries out a prediction mechanism to predict the future signal strength. This information is then used to categorize the link as stable or unstable. The work also deals with designing a proactive routing protocol which uses the information of stable and unstable links to build up routes using limited dissemination technique. The protocol is similar to distance vector protocol in which, only the distance vectors whose next hop is a stable is advertised. This ensures that only stable link information reaches the other nodes in the network. The protocol has been tested in Network Simulator-2 and compared with the Destination Sequenced Distance Vector [PB94] and the Adhoc On-Demand Distance Vector [PR97] protocols. Various parameters like percentage of packet delivery, packet latency, effects of moblity, etc. are measured. The results show that the performance of the designed protocol is better than AODV in high traffic scenarios. With less overhead, the proposed protocol always performs better than DSDV. In high mobility scenarios, the protocol is comparable to AODV and performs better than DSDV.