An energy efficient geographic routing protocol design in vehicular ad-hoc network

Supervisor:
Dr.H.Aghdasi
Rsearcher:
Sina Ajilyan
An energy-efficient geographic routing
protocol design in vehicular ad-hoc
network

An energy-efficient geographic routing protocol
design in vehicular ad-hoc network 2
In last session that we had in class about VANETS we learned that
exsitence of vehicle and combination of them with wireless connections
is the reason for creating such a networks and in this paper we study about
some famous routing algorithm and we will learn what is important in
optimization of routing algorithms.

3
design in vehicular ad-hoc network
The important factors in routing problem :
•Bandwidth
•power
•speed of mobile node
•density of topology
•distances between mobile nodes
The challenge is :
•reduction of wasted bandwidth and power while
•quickly responding to network changes and keeping a stable
information transmission

4
Simple categorize for VANET routing
• Topology based routing
• Geographic position routing
 Topology based :
These routing protocols use link information that exit in the network to perform
packet forwarding. They discover the route and maintain it in a table before the
sender starts transmitting data. They are further divided into reactive, proactive
and hybrid protocols.

5
 Topology based (cont.)
 Ad Hoc on Demand Distance Vector routing (AODV) :
AODV is a source initiated routing protocol and uses HELLO messages to identify
its neighbors. Source node broadcasts a route request to its neighbors which fill
forward to the destination. Then the destination unicast a route reply packet to
the sender.

6
 Pros and cons :
 advantage of this approach is that the routing overhead is greatly reduced
 disadvantage is a possible large delay from the moment the route is needed (a
packet is ready to be sent) until the time the route is actually acquired.
 When a link fails, a routing error is passed back to a transmitting node, and
the process repeats.
each request for a route has a sequence number. Nodes use this sequence
number so that they do not repeat route requests that they have already
passed on. Another such feature is that the route requests have a "time to
live" number that limits how many times they can be retransmitted. Another
such feature is that if a route request fails, another route request may not be
sent until twice as much time has passed as the timeout of the previous route
request.

 Dynamic Source Routing (DSR)
is a routing protocol for wireless mesh networks. It is similar to AODV in that it
forms a route on-demand when a transmitting node requests one. However, it uses
source routing instead of relying on the routing table at each intermediate device.

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 Geographic source routing(GSR)
In this algorithm, each node maintains a Neighbor list, a Topology table, a Next Hop
table and a Distance table. Neighbor list of a node contains the list of its neighbors .
For each destination node, the Topology table contains the link state information as
reported by the destination and the timestamp of the information. For each
destination, the Next Hop table contains the next hop to which the packets for this
destination must be forwarded. The Distance table contains the shortest distance to
each destination node.(dijekstra)
each update message contain information about all nodes

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VANET characteristics
• IVC
• RVC
• Hybrid
 This paper represents an IVC protocol

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 we need the following notations:
 D(s, d) The distance from the source to the destination.
 D( j, d) The distance from the alternate junction to the destination.
 𝐷 𝑛 The direction of the vehicle (node) travel.
 𝐷 𝑝 The direction of the data packet transmission (from source to
destination).
 Q(𝐷 𝑛 , 𝐷 𝑝) The quality factor between direction of the vehicle travel
and the direction of the packet transmission.
 Dc The proximity of the candidate junction to the destination point.
 𝑁𝐴𝑣𝑔 The average number of vehicles per cell.
 𝑁𝑐𝑜𝑛 The constant which represents the ideal connectivity degree we
can have within a cell.
 α, β, γ used as weighting factors for the distance, direction, and traffic
density,respectively (with α + β + γ = 1).
→
→
→
→
→
→
→
→
→

11
 To demonstrate the advantage of grouping vehicles, we formulate the problem
using the following simple example:

12
 Grouping example

13
 Grouping of vehicles
S1
S2
S3
S4
Group 1Group 3
Group 4
Group 2 A
Unit vector
S1=(1,0), S2=(0,1),
S3=(-1,0), S4=(0,-1)
VA=(vx,vy)
VA．SN VA=(10,0)
VA．S1 = 10
VA．S2 = 0
VA．S3 =-10
VA．S4 = 0
Max

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S1
S2
S3
S4
Group 1Group 3
Group 4
Group 2
B
Unit vector
S1=(1,0), S2=(0,1),
S3=(-1,0), S4=(0,-1)
VB=(vx,vy)
VB．SN VB=(0,-15)
VB．S1 = 0
VB．S2 = -15
VB．S3 = 0
VB．S4 = 15 Max
 Grouping of vehicles (Cont.)

15
1. The requesting vehicle broadcasts an RREQ to all vehicles within its range.
2. The receiving vehicle first checks whether the current RREQ is not a duplicate
packet. If it is, it drops it. Otherwise, it checks if the RREQ is from the same group
by checking the group ID of the RREQ. If this is the case, it then checks whether it
can provide the requested information or whether it has knowledge of a path that
can provide this requested information. If it does, it produces an RREP; if not, it
will add its own address to the request packet and rebroadcast the packet.
A
S
C
G
D
E
B

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3. The RREP is reached at the source (requesting) vehicle; the most suitable routing
path is chosen to obtain the information.
4. A new route discovery is always initiated prior to the link being expired. This
happens at time “t” before the estimated link expiry time (LET). In addition to the
group ID, the lifetime of the packet ensures that rebroadcasting of packets ceases
after either a certain number of rebroadcasts by different vehicles (hop count) or
when the lifetime of a packet is reached (packet expiration).
A
S
C
G
D
E
B
CNA Required
Data
Mobility
Information
Bottleneck
LET
RREP packet format

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 Calculation of LET( Link expiration time )
r : Transmission or line-of-sight range
V: Velocity
Ө: Velocity angle
Өi
Өj
vj
vi
(xj, yj )
(xi, yi )
r i
j

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Өi =30Өj = 0
vj =20 m/s
(0,0 ) (5,0 )
5
LET = 1.2
vi =10 m/s
Өi = 0Өj = 0
vj =20 m/s
(0,0 ) (5,0 )
5
vi =10 m/s
LET = 5.5
j
j
i
i
 Calculation of LET( Cont. )

19
CNA Required
Data
Required
Time
Lifetime Group
ID
 RREQ packet format
Cached node address is where the address of the
forwarding vehicle stored.
The Required Data field defines the requested
data.
The Required Time field defines the time
needed
for the data transmission.
Lifetime field will determine the expiration
parameters for the request packet.
The Group ID field identifies the group to
which
the requesting vehicle belongs.

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CNA Required
Data
Required
Time
Lifetime Group
ID
data.
The Required Time field defines the time needed
The Group ID field identifies the group to which

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CNA Required
Data
Required
Time
Lifetime Group
ID
data.

22
CNA Required
Data
Required
Time
Lifetime Group
ID
data.

23
CNA Required
Data
Required
Time
Lifetime Group
ID
data.

24
CNA Required
Data
Mobility
Information
Bottleneck
LET
 RREP packet format
Each node inputs its mobility information into
this field before forwarding the RREP packet.
The Bottleneck LET field represents the
shortest lived link on the path.

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CNA Required
Data
Mobility
Information
Bottleneck
LET
 RREP packet format
Each node inputs its mobility information into
this field before forwarding the RREP packet.
The Bottleneck LET field represents the
shortest lived link on the path.

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 Calculation of weights of scores (Ws)
 weight of path selection as the vehicle distance from the delivery node to
destination :
𝐷𝑖𝑠(𝑤𝑠) = max log
𝐷(𝑠,𝑑)
𝐷(𝑗,𝑑)
, 0.1
 Definition of the weight of real time traffic density “Den(ws)” is as shown in
𝐷𝑖𝑟(𝑤𝑠) = 𝑄 𝐷 𝑛 , 𝐷 𝑝
 the direction of the packet transmission, denoted by Dir(ws), can be expressed
by :
𝐷𝑒𝑛(𝑤𝑠) = 1 − 𝐷𝑐 + min
𝑁 𝑎𝑣𝑔
𝑁𝑐𝑜𝑛
, 1
1
2
3

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 total weights of scores T (ws) obtained as :
𝑇(𝑤𝑠)
= 𝛼 × max log
𝐷(𝑠,𝑑)
𝐷(𝑗,𝑑)
, 0.1 + 𝛽 × 𝑄 𝐷 𝑛 , 𝐷 𝑝 + 𝛾 × 1 − 𝐷𝑐
+ min
𝑁 𝑎𝑣𝑔
𝑁𝑐𝑜𝑛
, 1
→

An energy efficient geographic routing protocol design in vehicular ad-hoc network

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An energy efficient geographic routing protocol design in vehicular ad-hoc network