1. EAIT, February 2006 A Pragmatic Approach towards the Improvement of Performance of Ad Hoc Routing ProtocolsOptimizations To Multipath Routing Protocols In Mobile Ad hoc Networks Sudipto Das, Rajesh Roy, Pradip K. Das Department of Computer Science & Engineering, Jadavpur University, Kolkata – 32, sudipto.das@rediffmail.com, rajesh.roy@rediffmail.com, pkdas@ieee.org

2. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Presentation Outline Introduction Introduction Description Design Specifications Conclusion & Future Enhancements

3. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Introduction Mobile Ad hoc Networks are characterized by high mobility and frequent link failures. Routing algorithms selecting a single path during route creation require frequent route discoveries - D ecreased throughput and high end-to-end delay. Multipath routing approaches like AOMDV make use of pre-computed routes determined during route discovery. - Alternate paths are not actively maintained. Hence, precisely when needed, the routes are often broken. Information gathered by a node about its neighbor can used to dynamically determine the node to which a particular data packet has to be forwarded. Results in better load balancing, utilization of the additional routes, if feasible, and maintenance of additional routes.

4. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Presentation Outline Introduction Description Description Design Specifications Conclusion & Future Enhancements

5. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Our Solution – A New Layer We use a New Layer between the Network Layer and MAC Sublayer Main function of the New Layer is to gather information about the Neighbors Information gathered by the Layer augments the Routing Entity Shares a portion of the Routing Overhead of the Routing Entity Schematic Representation of the New Layer

6. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Description The New Layer uses Protocol Specific Beacons to gather Network statistics Interface to Routing Entity Lookup Table referred to as Neighbor Information Table (NIT)

7. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Description Description of Fields of the NIT -IP Address & MAC address: Uniquely Identify the neighbors -Beacon Counter: Counts the number of beacons received from the neighbor and is a measure of stability -Time Stamp: Tells when the last beacon was received and is used to determine whether a timeout has occurred -Neighbor State: Specifies the exact state the neighbor is in -Fractional Resource Usage: Gives the usage of neighbor capacity as a fraction of the total capacity (indicator of load) -Battery Power Left: Gives a measure of the battery power left in the neighbor -Signal Strength: The strength of the signal received from the neighbor and is a measure of the stability of the neighbor

8. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Presentation Outline Introduction Description Design Specifications Design Specifications Conclusion & Future Enhancements

9. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Design Specifications Finding Multiple Loop-free Link-Disjoint Paths - Uses a scheme similar to that used in AOMDV - Ensures creation of multiple loop-free paths during the query/reply based route discovery process Creating and Maintaining the NIT - On receipt of a beacon at a node, data is extracted and corresponding fields in NIT updated - The New Layer periodically updates this table to reflect the present status of the neighbors - Modified AOMDV uses this information for routing decisions Routing Decisions - Based on information such as Neighbor stability, load on the neighbor, Battery Power Left and Signal Strength, the best possible next hop is selected

10. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Design Specifications Stable Neighbor Detection A N-consecutive periodic hello messages scheme (deals with Fluctuating Neighbor Problem) Minimum signal strength threshold value for hello messages (deals with Communication Gray Zone Problem) Neighbor Status Unstable Meta Stable Stable Unstable State Meta Stable State Stable State Timeout N 1 consecutive beacons N 2 consecutive beacons K consecutive timeouts

11. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Routing In AOMDV A C D E F G H I J B Alternate routes not maintained, may timeout New Route Discovery ensues

12. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Modified Routing Strategy A C D E F G H I J B F I J F H J H G Next Hop Selected Dynamically from the list of possible next hops Alternate routes maintained

13. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Presentation Outline Introduction Description Design Specifications Conclusion & Future Enhancements Conclusion & Future Enhancements

14. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Conclusion We propose a possible optimization to the AOMDV routing protocol Based on information gathered from the neighboring nodes, best possible next hop is selected Data transmission through these alternate routes helps maintain them and prevent them from timing out

15. Jadavpur University Optimizations To Multipath Routing Protocols In Mobile Ad hoc Networks EAIT, February 2006 Future Enhancements We aim to find out an expression, as a function of the various values obtained from the Neighbor Information Table, to select the optimal next hop based on the Performance evaluation of the optimized algorithm based on some metrics like Packet Delivery Ratio, Average End-to-End Delay and Control Overhead Possibilities of incorporating QoS provisioning

16. EAIT, February 2006 A Pragmatic Approach towards the Improvement of Performance of Ad Hoc Routing ProtocolsOptimizations To Multipath Routing Protocols In Mobile Ad hoc Networks Acknowledgements The authors gratefully acknowledge the facilities provided and support given by all the staff members of the Centre for Mobile Computing and Communication, Jadavpur University formed by UGC under its “University with Potential for Excellence” program.

17. EAIT, February 2006 A Pragmatic Approach towards the Improvement of Performance of Ad Hoc Routing ProtocolsOptimizations To Multipath Routing Protocols In Mobile Ad hoc Networks Questions? Thank You