Issues in routing protocol
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The document discusses key issues in designing ad hoc wireless routing protocols including mobility, bandwidth constraints from a shared radio channel, and resource constraints of battery life and processing power. It outlines problems like the hidden and exposed terminal problems that can occur on a shared wireless channel. It also provides ideal characteristics for routing protocols, noting they should be fully distributed, adaptive to topology changes, use minimal flooding, and converge quickly when paths break while minimizing overhead through efficient use of bandwidth and resources.
Issues in routing protocol
- 1. Issues in Designing Adhoc Wireless routing Protocols T S Pradeep kumar h"p://www.nsnam.com
- 2. Issues in routing Mobility Bandwidth constraint Error prone shared broadcast radio channel hidden and exposed terminal problems Resource Constraints
- 3. Mobility highly dynamic frequent path breaks frequent topology changes
- 4. Bandwidth constraints Radio band is limited, hence the data rates are smaller when compared with the wired network so bandwidth has to be used carefully to avoid overheads topology changes incur more control overhead in turn consumes more bandwidth
- 5. shared broadcast radio channel wireless links have time varying characteristics the routing protocols interacts with the MAC layer for finding the routes or alternate routes so collision of data and control packets
- 6. Hidden terminal problem Assuming B is the intermediate node between A and C. A and C are sending data to B. A is hidden to C and C is hidden to A. But both are visible to B. Since A and C are hidden terminals, the packets sent by both the nodes at the same time causes collision at node B. This can be avoided by using RTS-CTS messages and also using RTS- CTS- Data- ACK.
- 7. Exposed Terminal Problem Node arrangement is A<-->B<-->C<-->D B is sending to A and at the same time C wants to send to D, but it cannot, because of inability of use of radio spectrum. when B-> A and C->D to happen simultaneously, then the transmitting frequency of C to be different from the receiving frequency.
- 8. Resource Constraints Battery life processing power size and weight constraints
- 9. Ideal characteristics of routing protocol Fully distributed (it is more fault tolerant than centralized) adaptive to frequent topology changes route computation and maintenance must involve minimum number of nodes localized, loop free and free from stale routes number of broadcasts to be limited to avoid packet collisions must converge to optimal route in case of path break or path failure
- 10. Ideal characteristics of routing protocol Scarce use of battery, bandwidth, computing power, memory, etc. store information locally within the nodes (to store only the stable local route, rather than the remote unstable route) Should support some Quality of service and also to support time sensitive traffic