Cloud-Assisted Gateway Discovery
for Vehicular Ad Hoc Networks
Yen-Wen Lin, Jie-Min Shen, and Hao-Jun Weng
Department of Computer and Information Science,
National Taichung University of Education,
Taichung, Taiwan, R.O.C.
Speaker: Lin-You Wu
Outline
I. Introduction
II. System Overview
III. Simulations
IV. Conclusions
I. Introduction
• Cloud services are charming for vehicular ad
hoc network (VANET) users.
• Advances of wireless networks make access to
the Internet from VANETs possible.
• However, the features of VANETs hinder the
delivery of cloud services to VANETs.
• It is important to find proper Internet
gateways to connect the VANET users to the
cloud.
• Thus, Internet access in VANET is quite
necessary to effectively acquire cloud services.
• Internet gateway here is defined as the portal
to the Internet.
• The efficiency of gateway discovery in VANETs
remarkably affects the experience of
employing cloud services.
• A cloud-assisted gateway discovery scheme is
proposed in this paper to get connection to
Internet and advance routing performance.
• In our design, a few cloud servers are
designated for maintaining vehicles’ routing
information.
• The gateway with longest link lifetime is
selected and reserved by the cloud servers for
the requesting vehicle in advance.
II. System Overview
A. System Model
• The system model is
depicted in Fig. 1. The
elements involved in
the system include:
Cloud Server:
Cloud Server is the service provider in the
cloud. In this paper, to support DaaS (Discovery
as a Service; described later) services to the
vehicle users, two special servers, namely, the
DaaS Registrar and the DaaS Dispatcher, are
facilitated in the system.
• DaaS Registrar maintains related information of the
gateways.
• DaaS Dispatcher is responsible of discovering and
dispatching the gateways for the client vehicles.
Gateway:
• Gateway is the entity which is able to connect
to the Internet directly.
• According to the mobility of the gateways, two
types of gateways are considered in this paper,
namely the Stationary Gateway and the
Mobile Gateway.
• The Stationary Gateway (SG) is part of the
roadside infrastructure such as access points
(APs) of WiFi or WiMAX, or base stations (BSs)
of cellular networks.
• The Mobile Gateway (MG) is the vehicles on
the road which can directly connect to the
Internet.
Client Vehicle:
• Client Vehicle (CV) is the vehicle which wants
to connect to the Internet.
Relay Vehicle:
• In case that a CV locates outside the coverage
of any gateway, one or more Relay Vehicles
(RVs) forward packets from/to a CV to/from a
gateway.
B. Gateway Registration
• The gateway willing to support gateway
service registers its state information with the
DaaS Registrar in advance.
• The state information of the gateway includes
current location, speed, direction, and QoS
level.
• The DaaS Registrar then assigns a GID
(Gateway ID) to the gateway.
C. Gateway Discovery
• A CV offloads the overheads of gateway
discovery to the cloud servers by sending a
REQ-DaaS message to currently serving
gateway.
• The DaaS Dispatcher takes over the gateway
discovery and dispatching for the requesting
CV.
D. Gateway Selection
• If more than one gateways are available, the
DaaS Dispatcher selects a best gateway for
serving the portal to the cloud.
III. Simulations
• The simulations are
collected in Table I.
A. Packet Delivery Rate
• The packet delivery rate
of both the AODV and
the proposed scheme
decreases as the
velocity of vehicle
increases.
B. End to End Delay
• In the AODV, the
gateway with least hop
count is selected for
handoff while in the
proposed scheme, the
gateway with longest
link lifetime is chosen as
the next-hop gateway.
C. Signaling Load
• In the AODV, the
gateway with least hop
count is chosen for
handoff.
• Oppositely, in the
proposed scheme, the
gateway with longest
link lifetime is selected
as the next-hop.
IV. Conclusions
• A cloud-assisted gateway discovery scheme is
proposed in this paper.
• Related cloud servers maintain the state
information of the gateways in the system.
• The gateway with longest link lifetime is
dispatched by the cloud servers for the
requesting vehicle ahead.
• Thus, the cloud servers are responsible of
discovering proper gateways for the
requesting vehicles.
END