2016年3月9日

Computing Research Seminar (2015/16): “CBS: Community-based Bus System as Routing Backbone for Vehicular Ad Hoc Networks”

Speaker:  Dr Liu Hai

Research Assistant Professor

Hong Kong Baptist University

Dr Liu presented his research results in computer networking.Compared to general vehicular systems, bus systems have advantages includingwide coverage, fixed routes and regular service. Inspired by these uniquefeatures of the bus systems, Dr Liu proposed to use the bus systems as routingbackbones of VANETs. Dr Liu presented a Community-based Bus System (CBS) whichconsists of two components: a community-based backbone and a routing schemeover the backbone. The backbone construction is a one-off operation which isdone offline while the routing is done online in individual buses. Dr Liu collectedreal-world traces of 2515 buses and built a community-based backbone byapplying community detection techniques in the Beijing bus system. A two-levelrouting scheme is proposed to operate over the backbone. The proposed routingscheme performs sequentially in the inter-community level and the intra-communitylevel, and is able to support message delivery to both mobile vehicles andspecific locations/areas. Dr Liu developed a probabilistic model to analyze themessage delivery latency of CBS. The average error of the analytically-derivedlatency is shown to be 8.9% of the latency derived from the real traces.Extensive experiments are conducted and the results show that CBS cansignificantly lower the delivery latency and improve the delivery ratio,compared to the existing solutions. CBS is a general solution which isapplicable to any bus-based VANETs.