Transcript スライド 1 - 江崎研究室

Ad hoc Network
江崎研究室 修士１年
中島 亮
What is Ad hoc Network?
 Meaning of Ad hoc Network
 Ad hoc＝その場限りの
 Node to node
→ノード間で一時的に形成されるネットワーク
A
B
C
Communicate with A…
I can!!
Use of Ad hoc Network
 Sensor network
 IC chip
 Weather sensor
 Sensor for scout
 Mobile network
 Cellular phone
 Note PC
 PDA
→movable and weak computation and
battery power
Packet transferring
 Multi-hop between nodes
 Efficient packet routing
→need to find efficient route
Efficient route
Multi-hop transferring
 Getting routing information
 Pro-active
 Making routing table beforehand
 Smaller lookup delay but more
communication
Ex. OLSR, TBRPF
 Re-active
 Look up route when needed
 Bigger delay but fewer communication
Ex. DSR, AODV
OLSR
 Optimized Link State Routing
 Hello message
 One hop to all neighbor nodes
 Never forward (IP TTL=1)
 Message: own and neighbor’s address
HELLO MESSAGE
Feature of OLSR
 MPR( Multi-Point Relay )
 Smallest set of 1 hop nodes that can join all 2 hop
neighbor nodes
 Efficient flooding
Pink object in right picture is MPR
Getting topology
 TC( topology control ) message
 All nodes selected as MPR MUST send
 Contain links between MPR and the node
which select the node as MPR
 Broadcast to all nodes
 Each nodes calculate topology and route
from this TC message and HELLO message
DSR
 Dynamic Source Routing
 Route discovery
 Efficient flooding by sequence number
 Relay node cache route information too
Request
Reply
Feature of DSR
 Route is written in Packet
 No loop can occur
 Confirm connection: use wireless ack
S-A-B-D
Source Node
S
F
C
G
A
S-A-B-D
E
H
B
S-A-B-D
D
Destination Node
I
AODV
 Ad hoc On-demand Distance Vector
 Re-active but partly pro-active
 Search route when needed
 Same as DSR
 Each node cache route from forwarding
packet
 Can use the same Hello Message as OLSR
use
 To confirm links to neighbors are alive
Feature of AODV
 Distance Vector (DV)
 Routing table
 Destination node’s address
 Hop number to Destination node
 Next node to Destination node
Distance
Vector
 Smaller packet
 Route is not in the packet
 Smaller routing table
 Each node know only next hop node
Conclusion
 Outline of ad hoc network
 Behavior of OLSR, DSR, AODV
 Advantages and Disadvantages
 OLSR:smaller delay,bigger communication
 Have way to lessen communication
 DSR:bigger delay,smaller communication
 Have way to lessen delay
→Choose protocol as the situation demands