Author: Chen, Honglong
Title: Routing strategies and cooperation incentive mechanisms for delay tolerant networks
Degree: Ph.D.
Year: 2012
Subject: Computer networks -- Reliability.
Routing (Computer network management)
Fault-tolerant computing.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Computing
Pages: xviii, 146 p. : ill. ; 30 cm.
Language: English
Abstract: In most of the conventional routing protocols, the messages are designed to be delivered along the always-connected end-to-end path between the source and destination. However, this kind of routing protocols are not applicable in delay tolerant networks (DTNs), in which the nodes are intermittently connected. DTNs, as an emergent communication paradigm, enable the transfer of messages among the intermittently connected nodes. Applications of DTNs include social networks, vehicular networks, pocket switched networks and habitat monitoring sensor networks, etc. In DTNs, the nodes are generally with some characteristics, which should be carefully considered in the research. Firstly, they are always intermittently connected due to their high mobility, sparse deployment and short radio range. Secondly, they are always some resource-limited (e.g., bandwidth, buffer space, energy power, etc.) mobile devices such as smart phones or PDAs. Thirdly, they are always some distributed autonomous entities, which make the routing decision locally and independently. Such kind of characteristics will challenge the research of DTNs from the aspects of routing, cooperation incentive, security and privacy, etc. Firstly, this dissertation proposes to use the contact expectation for the DTN routing. An expected encounter based routing protocol (EER) is proposed, which distributes multiple replicas of a message proportionally between two encounters according to their expected encounter values. In case of single replica of a message, EER makes the routing decision by comparing the minimum expected meeting delay to the destination. A community based routing protocol (CR) is further proposed, which takes advantages of the high contact frequency property of the community. The simulations demonstrate the effectiveness of the proposed EER and CR protocols under different network parameters.
Secondly, this dissertation proposes a cooperative routing protocol using the group feature for the DTNs under resource constraints, which includes a cooperative message transfer scheme and a buffer management strategy. In the cooperative message transfer scheme, the limited bandwidth is considered and the message transfer priorities are designed to maximize the delivery probability. In the buffer management strategy, by considering the constraint of buffer space, the cooperative message caching scheme is proposed and the dropping order of the messages is designed to minimize the reduced delivery probability. Finally, the simulations are conducted to demonstrate the effectiveness of the proposed group aware routing protocol under different network parameters. Thirdly, this dissertation considers the noncooperative DTNs, in which the nodes may be selfish and reluctant to cooperate with each other in the message forwarding. Two credit-based rewarding schemes, called earliest path singular rewarding scheme (EPSR) and earliest path cumulative rewarding scheme (EPCR) respectively, are proposed to ensure the nodes truthfully forward the messages. The proposed rewarding schemes are proved to be incentive compatible. It is also proved that the payment for each delivered message in these schemes is upper bounded. Furthermore, the proposed rewarding schemes can prevent selfish nodes from having malicious behaviors. The real trace based simulations are conducted to illustrate the effectiveness of the proposed rewarding schemes. Finally, this dissertation proposes to protect the end-to-end location privacy in the delay tolerant event collection systems, which are one of the typical DTN applications. Previous research only focuses on the location privacy of the source or sink independently. In this dissertation, the importance of location privacy of both the source and sink are addressed and four schemes called forward random walk (FRW), bidirectional tree (BT), dynamic bidirectional tree (DBT) and zigzag bidirectional tree (ZBT) respectively are proposed to protect them simultaneously. Simulation results illustrate the effectiveness of the proposed end-to-end location privacy protection schemes.
Rights: All rights reserved
Access: open access

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