Transcript Slide 1

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
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Introduction
Review of TCP/IP
Moving Forward
Wireless Networks
Transport
Incentives
Introduction
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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 …
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Along the way, we cover some useful tools
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Markov models
Stability of nonlinear systems
Duality in convex programming
Game theory
Introduction
• Major developments in Internet and networks
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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
ARCHITECTURE
Security
Mobility
Economics
Management
Applications
Network Transport
MIDDLEWARE
Sensor Networks
Link/PHY
Service Model
Packets/VC/C/…
Names, Addresses
Compatibility
Structure
PROTOCOL FUNCTIONS
WIRELESS
GENERAL
VoIP - Streaming
Ad Hoc Applications
Sensor/Actuators
Transport for Ad Hoc
QoS Routing
Network Processing
Combining Networks
Parallel Paths
TDM/Reservation
Multi-Channel
Low energy
Cognitive
Relays, MIMO, Capacity
Overlay
Searching
P2P
Storage
Fast Transport over fast links
Service Differentiation
QoS Routing
Improved BGP
Optical
Packets, Bursts, Lambda
Introduction
• Architecture
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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
n
Interface
n
Interface
C’
C
n-1
Services
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n-1
H
H
Services
Introduction
• Architecture: Mode
Packet
MPLS
BURST
Lambda
BURST
MPLS
Packet
Introduction
• Middleware
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Economics: Differentiation, Revenue Sharing
QoS: Specified or end-to-end choice
Mobility: Indirection Name  Address
Security: Insurance?
Introduction
• Middleware: Differentiation
Premium
- $0.1/min
Basic
- free
Introduction
• Middleware: QoS
• Specified: Premium = less than 150ms
• Choice: premium better than basic…
Introduction
• Middleware: Mobility
• Indirection (similar to cell phone)
Bill
(3): Bill = ? To H(Bill)
D = H(Bill)
(1) A (e.g., DHCP)
Bill: A
(4): Bill = A
(2): Bill = A to H(Bill)
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
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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
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Random network or given network?
O(.)-results or precise results?
Optimal or given set of protocols?
Delay-constrained or not?
Introduction
• Wireless: Scheduling
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Graph coloring
Key issue: correct model of constraints
Difficulty: Interference;Uncertainties
Question: Complexity (time, communication)
1, 4
2, 5
3, 5
1, 3
2, 4
Introduction
• Wireless: Power Control
• Strategic: In CDMA, increasing a improves rate for
node but increases interference for others
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c
b
Introduction
• Wireless: Routing
• Principle of optimality fails….
• Short or long hops?
Introduction
• Wireless: Transport
• Constraints?
Assume CDMA or TDMA?
Introduction
• Wireless: Network Processing
• Complexity
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Max(1, 4, 7)
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Max(3, 6, 9)
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Introduction
• Wireless: Network Coding
• Worthwhile?
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Introduction
• Wired
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Overlay pros and cons
P2P incentives
Transport: Control problem, strategic aspects
Service differentiation: benefits
Routing: BGP, QoS, Strategic aspects