Seminar: Opportunistic Routing and Network Coding in Multi-hop Wireless Mesh Networks

Chen Zhang
Ph.D. Oral Comprehensive
Supervisory Committee: Dr. Yuanzhu Chen, Dr. Cheng Li and Dr. Octavia Dobre

Opportunistic Routing and Network Coding in Multi-hop Wireless Mesh Networks

Department of Computer Science
Monday, December 19, 2016, 2:00p.m., Room EN 2022



The rapid advancements in communication and networking technologies are making the ubiquitous presence of wireless networks nowadays. Multi-hop wireless networks are extremely exciting and rapidly developing area and have been receiving an increasing amount of attention by the researchers. Due to the limited transmission range of the nodes, end-to-end nodes need other intermediate nodes to forward packets. Routing in such networks is a critical issue and has many challenges.

Opportunistic routing has been proposed to increase the network performance by utilizing the broadcast nature of wireless media. Unlike traditional routing protocols, the forwarder in opportunistic routing broadcasts the date packets before the selection of next hop. Therefore, opportunistic routing allows multiple downstream nodes as potential candidates to forward data packets instead of using a dedicated next hop.

Network coding is another innovative technique for improving network throughput and robustness by utilizing the broadcast nature. Instead of simply forwarding received packets, intermediate nodes can combine all received packets into one or several coded packets. Our research will study the properties, disordered transmissions, coding delay, spatial reuse, routing metric and candidate selection about opportunistic routing and network coding.

Firstly, we will propose a mechanism to support TCP with network coding and opportunistic routing, which are rarely incorporated with TCP because the frequent occurrences of out-of order arrivals in opportunistic data forwarding and long decoding delay in network coding overthrow TCP’s congestion control. Our solution completes the control feedback loop of TCP by creating a bridge between the sender and the receiver. The simulation result shows that our protocol significantly outperforms TCP/IP in terms of the network throughput in different topologies of wireless networks.

Secondly, we will propose a regional forwarding schedule for coordination of opportunistic data forwarding. In our coordination algorithm, the forwarding schedule is limited to the range of the transmitting node rather than among the entire set of forwarders. With such a algorithm, our proposal can increase the throughput by deeper pipeline transmissions.

Thirdly, we focus on the performance analysis of opportunistic routing by the Discrete Time Markov Chain (DTMC). We evaluate opportunistic routing in multi-hop wireless networks in terms of the expected transmission count and the expected transmission delay. Then, we will propose a routing metric for the opportunistic routing protocol.


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