Communication Networks

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 • Wireless: Wi-Fi, Wi-Max, MANETs, Sensors • QoS, Transport, Routing, Cross-Layer… • 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 insuranceInsurance 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

Communication Networks