1. PANEL DISCUSSION ON CROSS-LAYER DESIGN 5-14-03 ICC ’03 Anchorage, AK A. Ephremides

2. 2 CROSS–LAYER DESIGN NOT an approach! Recognition of inter-layer coupling that can be exploited All networks – but especially wireless

3. 3 MOST FUNDAMENTAL REASON “Upper” Layers Require a “Graph” In wireless networks there is no a-priori graph Links (Edges) depend on –Physical layer issues (power, signal, rate, detector, mod, coding,…) –Hardware (antenna, processing chip) –MAC (interference)

4. 4 OTHER REASONS 1. Energy (processing vs. transmission) −Compression 2.Parallel Routing vs. Multiple Descriptions −Compression/routing 3.Sensor Networks for Detection −Correlated transmissions −What to transmit - to - whom 4.MAC/Routing −MAC: allocate resources to demand −Routing: place demand where there are resources

5. 5 SOME ANSWERS TO THE POSED QUESTIONS New Architecture? –Possible, but mind that optimum performance design is the antithesis of architecture (that leads to standardization) Different Networks/Different Designs? –Resounding YES! –Even different applications require different designs (e.g., sensor nets) Research in the Area? –Fantastic opportunities –New and solvable problems –Some real challenging ones Advice? –Resist temptation for Fast results and Swollen claims –Be curiosity driven