May, Zin Oo (2012) A proxy-assisted routing for efficient data transmission in mobile ad hoc networks / May Zin Oo. PhD thesis, University of Malaya.
Abstract
A new protocol, named Proxy-Assisted Routing for efficient data Transmission (PART), that uses a cross layer approach is proposed to route packets to a destination efficiently in Mobile Ad Hoc Networks (MANETs). PART limits the number of control packets with the aid of proxy nodes, adapts to route failures and avoids congestion quickly by broadcasting routing information within a predefined zone. It utilizes the address information of the Medium Access Control (MAC) layer to transmit unicast control messages and limit the broadcast zone. Only mobile nodes that are in this zone are allowed to broadcast routing information to reduce the control overhead and packet collision. A middle node is selected to perform proxy duty for a TCP connection. The responsibility of a proxy node is to reply to a new route request from a source node and to request a new route to the destination when there is a link break. In order to reduce the extra routing overhead of assigning a proxy node, a unicast route reply packet is modified by adding a proxy address and a proxy hop count field in the packet header. A destination node determines whether a proxy node is needed based on the hop count. If the hop count to the source node is longer than a pre-defined value, it initiates a procedure to appoint a proxy node. Otherwise, a proxy node is not appointed. Whenever a route failure occurs between a source and proxy node, the source node takes the responsibility of searching for a new route to the proxy node. The proxy node also does the same thing, as long as the proxy node is available. In order to ensure the reliability of TCP, a proxy node acknowledgement (PACK) is introduced to check the correctness of data packets and informing the source node of missing packets by sending an acknowledgement to the source node in advance. By doing so, the source node does not have to wait for an end-to-end acknowledgement from a destination, resulting in increased throughput and decreased delay. For the purpose of performance analysis, an analytical framework is proposed to compare the robustness and efficiency of PART to other routing protocols. The comparisons were done across the mobility models that are intended for MANETs. The simulation results show that PART improves the overall network performance in terms of throughput, control overhead, delay, packet losses and packet collisions at the MAC layer. Among the contributions of this research are to limit the broadcast region by using a proxy node, to repair broken routes between source-proxy and proxy-destination nodes, and the use of local acknowledgement from a proxy to a source to ensure the reliability and correctness of TCP packets.
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