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UBC Theses and Dissertations

Load-balancing and secure routing for wireless mobile ad hoc Song, Joo-Han


A mobile ad hoc network is a collection of mobile nodes dynamically forming a multihop wireless network. Due to the limited transmission range of wireless interface, a routing protocol is needed to enable communication between mobile nodes. The first part of our work focuses on the load-balancing routing protocol in mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Although on-demand routing schemes are appealing with low routing overhead in bandwidth restricted networks, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the Ad hoc On-demand Distance Vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Results show that LB-AODV outperforms other routing schemes as traffic increases. We compare the performance of our proposed LB-AODV protocol with both the original AODV and gossip-based routing protocols in different mobility and traffic scenarios. Simulation results show that LBAODV delivers more data packets to the gateway and decreases the end-to-end delay of packets delivered by reducing the transmissions of routing control messages by 50 % or more. In scenarios with traffic congestion, LB-AODV outperforms AODV and GOSSIP 1 routing protocols. Another important issue in ad hoc routing protocol is security. In hostile environments, it is crucial to provide a secure communication infrastructure between mobile nodes. We investigate the severe threats of routing table tampering attack, where attackers can modify the information stored in a mobile host's routing table. To guard against this attack, we propose the use of either the Tamper Resistant Module (TRM) or the Secure Table Entry Protection (STEP) mechanisms. STEP can provide the authentication for both the destination sequence number and hop-count fields in the routing table entry. We analyze security threats against AODV routing protocol and propose Secure AODV (SeAODV), a secure routing extension to the original AODV. We also propose a Secure Data Forwarding (SDF) scheme based on SeAODV for secure transmissions of data packets over the wireless links. Simulation results showed that STEP continues to maintain a high packet delivery fraction and a small end-to-end delay at the expense of slightly higher route acquisition latency and control overhead in route discovery. In the presence of either data packet dropping or routing table tampering attacks, SeAODV continues to maintain a high packet delivery fraction and a small end-to-end delay. We further investigate the security problems of position-based routing protocol in mobile ad hoc networks. Although position-based routing protocols can offer significant performance improvement over topology-based routing protocols by using location information in large and dense mobile ad hoc networks, attackers can disrupt the location service by violating protocol specifications. We propose the Secure Grid Location Service (SGLS), which is an enhancement to the original Grid Location Service (GLS) protocol by using a broadcast authentication protocol and a Local Reputation System (LRS) for monitoring. Simulation results showed that in the presence of message dropping attacks, the proposed LRS mechanism maintains a high message delivery ratio at the expense of a higher average end-to-end delay and routing overhead.

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