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A Connectivity Invariant Dynamic
Multichannel Assignment Method for VANET
Tong Zhao, Shanbo Lu, Wei Yan, and Xiaoming Li
School of Electronics Engineering and Computer Science
Peking University, Beijing, P.R. China, 100871
Abstract.
Multi-Interface Multi-Channel (MIMC) can be used to re-
duce the channel interference and improve the network capacity for
multi-hop wireless ad-hoc networks, but using multichannel will impact
the network connectivity, which is an important QoS factor in VANET.
The basic multichannel assignment scheme in our paper can keep the
connectivity as good as single channel network. Furthermore, the nodes
can periodically monitor the channel usage and dynamically switch the
channels to the less busy ones. In order to work in the highly mobile sce-
narios in VANET, the method works in a fully distributed way with low
overhead. Simulations show that our method can notably improve the
throughput of VANETs. And the performance keeps steady with various
network configurations.
Keywords:
Multichannel, Connectivity, Channel Usage, VANET.
1 Introduction
Vehicular Ad-hoc Network (VANET), as a subset of MANET, is confronted with
the same problems of inter-link interference and low capacity [5]. Multichannel
technology can alleviate the interference [8]. However, channel diversity and
network connectivity are two conflicting factors. Fig. 1 is an example.All the
4 nodes are within direct communication distance. The topology with a single
channel is originally a 4-node fully connected graph (Fig. 1(a)). When link (1,4)
and (2,3) are working on different channels, the network is partitioned to two
parts (Fig. 1(b)). If the nodes can work on two channels concurrently with two
interfaces, a topology in Fig. 1(c) can be formed. If the nodes equip as many
interfaces as channels, they can freely select the channel to avoid interference
while assure connectivity. However, there are 12 orthogonal channels in 802.11a,
3 in 802.11b/g [2] and 7 channels for DSRC [6]. Equipping 3 interfaces on each
node seems possible, but mounting 7 or 12 interfaces is a bit too many.
Most existing works have much fewer interfaces than channels, and sacrifice
some connectivity for the channel diversity [9,3,7,23,19,4,21,16]. In this condi-
tion, an optimal channel assignment method needs to take the routing strategy
This work is supported in part by 973 Program of the Chinese Ministry of Science
and Technology (No. 2009CB320504) and National Natural Science Foundation of
China (No. 61073155 and No. 61201245).
