Routing in WSN Exercise

Transkript

1 Routing in WSN Exercise Thomas Basmer telefon: fax: basmer [ at ] ihp-microelectronics.com web:

2 Outline Routing in general Distance Vector Routing Link State Routing Distance Vector vs. Link State Routing Proactive Protocols Reactive Protocols Proactive vs. Reactive Protocols Addressing Kapitel 1 Seite 2

3 Routing in General What is Routing? Finding a way from source to destination Multi-hop communication source destination Kapitel 1 Seite 3

4 Routing in General Air is a Broadcast medium. Why routing is necessary? Sending range is limited (can t reach destination directly) Energy consumption depends on distance in a exponential manner (TXenergy ~ distance³) Collisions overhearing Kapitel 1 Seite 4

5 Routing in General Challenges Nodes fail (hardware / software) Nodes move around / breathing cell Large networks Limited energy goals Energy efficient routing Long network lifetime Kapitel 1 Seite 5

6 Routing in General Routing needs: Additional information about neighborhood Neighbors Network topology Weights of links (BER, energy, ) Information must be efficient exchanged Routing tables Size of the tables Update period of the tables Kapitel 1 Seite 6

7 Distance Vector Routing Each node has a routing table containing all neighbors The distances (hops, delay, energy consumption, BER) to all neighbors The next hop to destination No information over network topology Routing table is periodically exchanged between neighbors and updated Kapitel 1 Seite 7

8 Distance Vector Routing A B C D destinantion A C D Next hop - - C Distance (hops) Kapitel 1 Seite 8

9 Distance Vector Routing A B C D Routing tables of the other nodes? What happens when link between C and D disappears? Count to infinity problem! Kapitel 1 Seite 9

10 Distance Vector Routing A B C D Solutions to prevent C2I? Time stamp for routes (sequence numbers) Exchange whole path to destination Show changes in the routing tables! Kapitel 1 Seite 10

11 Link State Routing A B C D Store network topology graph ID, link cost Calculate shortest path Exchange information with ALL NODES Update tables when receiving Link state of the nodes? Kapitel 1 Seite 11

12 Distance Vector vs. Link State Routing Effort to setup Distance Vector Routing Link State Routing Effort to maintain Distance Vector Routing Link State Routing All information has a size of 1 byte ID, distance, next Kapitel 1 Seite 12

13 Distance Vector vs. Link State Routing Distance Vector + small data to exchange - Count to infinity Link State + good if topology is often changing - Large overhead Kapitel 1 Seite 13

14 Proactive Protocols Routing information is exchangend continously This strategy is good for? Networks with short reaction times or high data throughput Kapitel 1 Seite 14

15 Proactive Protocols Examples Destination Sequenced Distance-Vector (DSDV) DV + sequence number Fisheye State Routing Link State Protocol Exchanged information is reduced with rising distance between nodes Higher distance larger update period Kapitel 1 Seite 15

16 Reactive Protocols Routing information is exchanged just before transmission Flood network with routing packets to get route Send data on best path This strategy is good for? Networks with little data transfer And an often changing topology Kapitel 1 Seite 16

17 Reactive Protocols Examples Ad Hoc On-Demand Distance Vector Routing (AODV) Dynamic Source Routing (DSR) request ist not forwarded when intermediate node knows the route Zone Routing Protocol (ZRP) Hybrid Proactive in close neighborhood Reactive for large distances Kapitel 1 Seite 17

18 Proactive vs. Reactive Protocols Proactive + no latency before TX - Exchange of routing information even if no data tx Reactive + routing information is exchangend if necessary - Higher latency Kapitel 1 Seite 18

19 Addressing Id centric Each node has an address Address length limits network size Data centric Requested data is important not the source Reduces traffic because no redundand data Data aggregation Publish subscribe (Direct Diffusion, Rumor Routing) Kapitel 1 Seite 19

20 Addressing Geographic Nodes know their location Greedy Routing Send to known nodes in direct line to destination Location-Aided Routing (LAR) Route request only forwarded by nodes closer to destination then sender Kapitel 1 Seite 20

21 Goodby! Thank you for your attention! Kapitel 1 Seite 21