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

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

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

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 RequestReply

Feature of DSR  Route is written in Packet No loop can occur Confirm connection: use wireless ack Source Node Destination Node

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 Smaller packet  Route is not in the packet Smaller routing table  Each node know only next hop node Distance Vector

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