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Transcript of Routing protocols
No best routing protocol than other
We should check for all routing protocols existing to meet the best suitable for our needs
Results with bad Mobility models could lead to bad decisions/conclusions
Routing protocols in VANET
VANET: The Vehicular Ad-Hoc Network
Is a technology that uses moves cars as nodes in a network to create a mobile network
Cars approximately 100 to 300 meters of each other to connect
Create a network with a wide range
Routing and forwarding
finding routes towards the desired destination in such disconnected and rapid topology changing environments is regarded as the most compelling issue
Simulation study of VANETs
use of a mobility model which resembles, as closely as possible, the real behavior of vehicular traffic.
Random Waypoint Model (RWM)
Fluid Traffic Model (FTM)
current vehicle speed based on the total number of vehicles
Intelligent Driver Model with Intersection Management (IDM-IM)
adapts a vehicle speed according to other vehicles driving ahead. It can manage crossroads regulated by both stop signs and traffic lights
In (GOSR) algorithms
non-neighbor nodes as well as the
best-known neighbor( typically the neighbor nearest to the next junction in a greedy fashion), is designated as the next hop.
non-neighbor nodes are given opportunities to do forwarding
Geographical Source Route Selection
A graph is extracted from the e-map
Junctions (source and destination) as vertices
Road segment between junctions are mapped as edges
. Each edge is coupled with a weight, whose value is proportional to the length of the road segment
Getting shortest path from source to destination
The Dijkstra algorithm
2) Geographical Opportunistic Forwarding
When one node receives a packet uses the last hop position and the scope information in the packet in order to checks if it is in the designated scope or not
it becomes the candidate
if ( it is nearer to the next junction than the best- known neighbor)
it becomes the
defer timers to avoid simultaneous transmissions
defer _ time = max_ defer _ time *R − Dcn/R
max_defer_time is a predefined value
R = scope − Dsn
Dsn is the distance between the last hop and the best-known neighbor
Dcn is the distance between the current node and the best-known neighbor.
In this way, we ensure that better forwarding opportunities are given higher priorities.
Avg. Latency vs Speed of Nodes
Packet Delivery Ratio vs Speed of Nodes
Network Throughput vs Speed of Nodes
Avg. Latency vs Distance between Nodes
Packet Delivery Ratio vs Distance
Network Throughput vs Distance between Nodes
- Able to work with simple MAC protocols Ex. CSMA.
- 2 phases:
- Compute Trajectory phase
- Forward phase
- Source-based reactive protocol
- Forwarding decisions shifted from transmitter to the receiver.
- Sift is based on broadcast instead of point-to-point transmissions.
SIFT: Compute Trajectory
- This phase is executed by the source.
- In this phase a trajectory to the destination is calculated
- It is reactive
- This phase is executed by each intermediate node.
- This procedure decides whether to forward or not a packet
- No control packets
- All information for forwarding is int the data packet
- Stable Latency
- Stable number of hops
- Proactive protocol
- Single hop neighbors exchange information
- Very low delay
- Not a good option for limited power-energy network
- Two forwarding methods:
- Greedy forwarding
- Perimeter forwarding
- Greedy choice is based on the locations of the nodes
- Optimal choice for next hop -> neighbor geographically closest to destination
Greedy Forwarding Failure
The Right-Hand Rule
- High delivery packet rate
- Robust protocol
- GPSR suffers in city scenarios:
- No direct communications
- Planarized graphs problem
- Loops for face routing
- Every routing protocol has its features.
- Mobility models could lead to a bad choice.
- We should choice wisely depending on the needs of our network.