Communication Networks A Second Course Jean Walrand Department of EECS University of California at Berkeley

Administrative Details 3 Units Course Contents: Review major recent networking research ideas Provide background for these papers Get a sense of where field is heading Grade based on Class participation: Writing lecture notes: Lecture  assigned “scribe” writes notes  other students send comments on notes  revised notes Term project and its presentation: Select topic by week 6; outline by week 9; ready to present by week 12; report by week 15.

Contents Introduction Review of TCP/IP Moving Forward Wireless Networks Transport Incentives

Introduction Explain network models and analysis Focus on three active areas of research 1.Wireless: Wi-Fi, Wi-Max, MANETs, Sensors 2.QoS, Transport, Routing, Cross-Layer… 3.Incentives: Differentiation, Revenue Sharing … Along the way, we cover some useful tools Markov models Stability of nonlinear systems Duality in convex programming Game theory

Introduction Major developments in Internet and networks Economic value (B2B, B2C) New applications (voice, video, TV) New structures (P2P) Machine-to-machine communication Mobility support Security concerns Internet protocols over-stretched Protocols must adapt or be changed

Introduction Key Ideas:

Introduction Major research topics

Introduction Architecture Service Model: Best effort or richer? Compatible or “Greenfield” New layer structure for wireless, “cross-layer?” Switching and transport modes

Introduction Architecture: Service Specification: soft or precise? Choice and select?

Introduction Architecture: Layers

Introduction Architecture: Mode

Introduction Middleware Economics: Differentiation, Revenue Sharing QoS: Specified or end-to-end choice Mobility: Indirection Name  Address Security: Insurance?

Introduction Middleware: Differentiation

Introduction Middleware: QoS Specified: Premium = less than 150ms Choice: premium better than basic…

Introduction Middleware: Mobility Indirection (similar to cell phone)

Introduction Middleware: Security Insurance? To connect, you need an insurance Insurance company checks your “security” Incentive: Premium goes down if secure

Introduction Wireless: Sensor and Ad Hoc Application-driven or generic? Network capacity Scheduling: graph coloring Power control: strategic issues Routing: interference; short or long hops; parallel paths Transport: How to include graph constraints? Network-processing Network coding Wi-Fi VoIP+Data Capacity WiMax vs. Wi-Fi

Introduction Wireless: Application-Driven or Generic? Basic observation: No universally best protocols Using features of application yields better solutions Example 1: If central node can reach all sensors, it can provide synchronization, polling, etc. Example 2: Power constraints may not exist in some systems and be essential in others Keep in mind technology trends

Introduction Wireless: Network Capacity Random network or given network? O(.)-results or precise results? Optimal or given set of protocols? Delay-constrained or not?

Introduction Wireless: Scheduling Graph coloring Key issue: correct model of constraints Difficulty: Interference;Uncertainties Question: Complexity (time, communication)

Introduction Wireless: Power Control Strategic: In CDMA, increasing a improves rate for node but increases interference for others

Introduction Wireless: Routing Principle of optimality fails…. Short or long hops?

Introduction Wireless: Transport Constraints? Assume CDMA or TDMA?

Introduction Wireless: Network Processing Complexity

Introduction Wireless: Network Coding Worthwhile?

Introduction Wired Overlay pros and cons P2P incentives Transport: Control problem, strategic aspects Service differentiation: benefits Routing: BGP, QoS, Strategic aspects