1. Support for Multimedia Traffic in Mobile, Distributed, Multiple-Hop Wireless Networks Steven Boyd S.U.R.E. Program 2003

2. Presentation Overview  Project Background  Current Routing Protocols  Improving the Protocols  Network Model  Conclusions  Future Work

3. Project Background  Ad hoc Networks Small group of wireless mobile nodes (<100) No Centralized Infrastructure Military Applications - Handheld Multimedia Terminals (HMTs)  RAVEN (Reliable All-Informed Voice Network) Networking Protocols for HMTs  Adaptive Transmission Protocol (ATP)  Other Routing Protocols HMT Capabilities  Direct-Sequence Spread-Spectrum Radio  Four Frequency Channels  Can Adapt Power, Code Rate, and Spreading Factor

4. What Makes a Network Efficient?  High Completion Rates Packets Delivered Successfully vs. Packets Sent  Low End to End (ETE) Delay  Quality of Service Requirements Voice vs. Data

5. Improving the Current Protocols  Goal: Increase Network Efficiency for Voice Traffic  Voice packets travel along dedicated multi-hop paths called “Virtual Circuits” Problem: Virtual circuits need to be repaired.  Solution: Predict when a transmission link will fail and re-route the virtual circuit to avoid losing the packet. Use Link Resistance values

6.  LR v =  v E(A,B) +  v L(A,B) +  v R(A,B) + C Calculating Link Resistance Energy Metric Determined by the Power Rate and Information Rate for the Link Failed Tx Metric Determined by the number of failed forwarding attempts on the link. Remote Resistance Determined by the amount of traffic at the receiving terminal.  Adaptive Transmission Protocol Adjust Power and Information Rate

7. Current vs. Proposed  Re-routing based only on total value of link resistance  Does not account for time validity of data stored in neighbor tables  Re-routing based on individual components of link resistance  Takes into consideration the time validity of data.

8. Network Model  Established a Network of 25 Nodes  12 Nodes generate voice packets  All Nodes generate data packets  OPNET Simulation Software Allows Modeling of Defined Networks Allows Simulations to Determine Network Efficiency for Network Models

9. Network Mobility Model 9 Stationary Nodes 16 Mobile Nodes Source Node Destination Node

10. Performance of Current Protocol

11. Performance vs. Increased Mobility

12. Conclusions  Information rate is a good predictor of link failure.  Using time-validity of gathered data improves completion rates.  Using a combination of information rate and time-validity provides the best overall network routing protocol.

13. Future Work…  Define a new routing metric which introduces time-validity as a component of link resistance.  Establish a more detailed interface between the virtual circuit manager and the ATP protocol to use all possible information when determining routes.

14. Questions… ?