1. Madhavi W. SubbaraoWCTG - NIST Dynamic Power-Conscious Routing for Mobile Ad-Hoc Networks Madhavi W. Subbarao Wireless Communications Technology Group National Institute of Standards and Technology

2. Madhavi W. SubbaraoWCTG - NIST Outline Introduction to MANETs Project Overview Project Approach Results Conclusion and Future Directions

3. Madhavi W. SubbaraoWCTG - NIST Mobile Ad-Hoc Networks (MANET) Rapid deployment of autonomous mobile users Communication over wireless radio links Decentralized structure Dynamic topology Contend with effects of radio communication Stand-alone or connected to larger network Examples –Fire/Rescue operations –Disaster relief efforts

4. Madhavi W. SubbaraoWCTG - NIST MANET Routing Dynamic routing algorithms: Must adapt to –Entering/departing nodes –Changes in link quality –Changes in terrain –Traffic patterns and interference –Rate of topological change Fast run time compared to rate of topology change Low overhead and storage requirements High throughput and low packet delay time Preserve network requirements (e.g., security) Efficient use of power

5. Madhavi W. SubbaraoWCTG - NIST Motivation In emergency situation or disaster, centralized infrastructure may fail Research in area focusing on establishing routes –Links either “present” or “absent” –All “present” links have same link quality –Generalization - since links have different reliability statistics and power needs! Prompted interest to consider –Power consciousness –Variable link quality –Distributed routing scheme

6. Madhavi W. SubbaraoWCTG - NIST ATP / NIST Project Overview Investigate importance of power in MANETs Make networks more survivable by efficiently using power Incorporate physical and link layer structure Account for location and surrounding of node –Capture shadowing and fading effects –Account for multi-user interference Assign cost function indicating TX power needed to reliably communicate over link Provide level of “network diversity” by routing around undesirable areas

7. Madhavi W. SubbaraoWCTG - NIST Benefits of Power-Consciousness Prolong life of power supply LPD & LPI Less multiuser and adjacent channel interference Higher spatial reuse Efficient use of power –Too low -> disconnected network –Too high -> excess interference

8. Madhavi W. SubbaraoWCTG - NIST Minimum Power Routing (MPR) Goal: Select path that will require least amount of total power expended, while maintaining acceptable SNR. Alter TX power according to link quality. Strategy: Assign link cost as TX power needed to successfully transmit packet on link. Extend concept to other algorithms. Transmission from Node i to Node j: -RX Power -SNR where -Compute TX power needed to reliably transmit on link:

9. Madhavi W. SubbaraoWCTG - NIST MPR implementation Use side-information for estimation - test symbols Link scale factor estimation : Power estimation: Link cost update:,  = 0.3 Propagate link costs through network Initial approach: use distributed Bellman-Ford algorithm to find most “power-efficient route” Comparison between MPR, SD-PC, and MH-PC to see if power-conscious concept benefits MANET routing.

10. Madhavi W. SubbaraoWCTG - NIST Simulation Framework Designed and developed simulation framework in OPNET

11. Madhavi W. SubbaraoWCTG - NIST Simulation experiment: Static network 16 nodes Data rate:10pk/sec Load - 10K pk

12. Madhavi W. SubbaraoWCTG - NIST Simulation experiment: Mobile network 16 nodes Data Rate 10 pk/sec Load - 10K pk

13. Madhavi W. SubbaraoWCTG - NIST Simulation experiment: Mobile network Environment same with added mobility - 4m/s Mean power per hop averages around 90mW.

14. Madhavi W. SubbaraoWCTG - NIST MPR Conclusions MPR optimizes on link quality and power expended NOT on distance or hops Investigation shows benefit by routing on power- conscious route, even though may be longer Greatly improve overall efficiency of network by –Routing around heavy shadowing in network –Altering TX power according to link quality and NOT path loss Power-conscious concepts should be extended to other routing protocols.

15. Madhavi W. SubbaraoWCTG - NIST Future Directions Extend power-conscious routing concepts to various distributed routing protocols Investigate power-conscious concepts in heterogeneous emergency MANETs (fire, rescue, police, etc.) Enhance simulation testbed and compare performance with various MANET protocols Conference Publications IEEE Vehicular Technology Conference Fall 1999 OPNETWORK Conference Fall 1999