Users face location-privacy risks when accessing Location-Based Services (LBSs) in an Opportunistic Mobile Social Networks (OMSNs). In order to protect the original requester's identity and location, we propose two location privacy obfuscation protocols utilizing social ties between users. The first one is called Multi-Hop Location-Privacy Protection (MHLPP) protocol. To increase chances of completing obfuscation operations, users detect and make contacts with one-hop or multi-hop neighbor friends in social networks. Encrypted obfuscation queries avoid users learning important information especially the original requester's identity and location except for trusted users. Simulation results show that our protocol can give a higher query success ratio compared to its existing counterpart. The second protocol is called Appointment Card Protocol (ACP). To facilitate the obfuscation operations of queries, we introduce the concept called Appointment Card (AC). The original requesters can send their queries to the LBS directly using the information in the AC, ensuring that the original requester is not detected by the LBS. Also, a path for reply message is kept when the query is sent, to help reduce time for replying queries. Simulation results show that our protocol preserves location privacy and has a higher query success ratio than its counterparts. We have also developed a new OMSN simulator, called OMSN Routing Simulator (ORS), for simulating OMSN protocols more efficiently and effectively for reliable performance.

This thesis presents the design and evaluation of routing protocols for efficient content delivery and dissemination in delay tolerant networks. With the advancement in technology, the communication devices with wireless interfaces become more and more universal. Delay tolerant networks (DTNs) are characterized by intermittent connectivity and limited network capacity. There exist several different application scenarios: connectivity of developing countries, vehicular DTN road communications, and social contact networks. In this thesis, we explore the characteristics in DTNs, such as mobility pattern, contact history information, and social feature information, to design efficient routing schemes. The research reported in this thesis investigates the technical challenges and their solutions of applying different DTN routing protocols. We design multicast schemes to forward the information to a group of destinations in DTN environment. We extend the delegation forwarding scheme in DTN multicasting. An non-replication multicast tree is also studied in this report. We also apply ticket-based and social-tie-based approaches in content distribution systems. We leverage the users' social feature information to study the hypercube-based routing schemes in social contact networks. We also study the resource management problem in DTNs. We design a joint replication-migration-based scheme to solve the storage congestion. These techniques are evaluated comprehensively in realistic simulation studies, by comparing the performance with state-of-the-art approaches in both synthetic and real traces. / Computer and Information Science