“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

1

Chapter 9

Fundamentals of Communication Networks

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Communication Network Architecture

Communication devices Network nodes Communication links

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Protocol Architecture

Break communication task down into subtasks Divide-and-conquer approach Hierarchical layers

Protocols Define subtask operation within a layer TCP/IP protocols

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Switching Technologies

Circuit switching Circuit establishment Data transfer Circuit termination

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Switching Technologies

Packet switching Store-and-forward Network resources allocated on-demand

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Switching Technologies

Virtual circuit switching Combining features of circuit switching

and packet switching Virtual circuit pre-established Link bandwidth shared efficiently

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Encapsulation and Multiplexing

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Naming and Addressing

Domain name Domain Name System (DNS)

Port number Well-known port numbers Ephemeral port numbers

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Naming and Addressing

IP address Subnetting Socket: combination of an IP address and

a port number

Medium Access Control (MAC) address

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Multiple Access

Media shared in a broadcast network Rules for hosts to access the media Media Access Control (MAC)

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Routing and Forwarding

Network layer function Maintaining network topology

information Routing table

Forwarding packets Packets forwarded hop-by-hop

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Congestion Control and Flow Control

Congestion control Router congestion

Flow control Fast transmitter and slow receiver

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Error Control

Checksum in TCP/IP Cyclic redundancy check (CRC) in

Ethernet Sequence numbers to detect lost

packets

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

New Challenges in Wireless Networks Wireless transmissions

Different concept of communication link Coupled channels Capacity limited by SINR

Mobility Handoff in infrastructure-based wireless

networks Rerouting in infrastructureless wireless

networks Energy efficiency

Significant impact in every layer

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Mobility Modeling

The Random Waypoint Model

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Mobility Modeling

Speed distribution

Average speed Location distribution

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Perfect Simulation

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Power Control and Multiuser Diversity

Uplink of a infrastructure-based wireless network

Received signal at the base station is

Frequency flat Reyleigh fading

Objective

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Power Control and Multiuser Diversity

No power control

Perfect power control

Optimal power control

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Power Control and Multiuser Diversity

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Multiple Access Schemes

Classification of multi-access schemes

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Polling

Queueing system with one server and m stations

Finite buffer and infinite buffer

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Polling Service policies

Limited service Exhaustive service Gated service

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

ALOHA and Slotted ALOHA

ALOHA A station transmits a packet whenever it

wants to Maximum throughput 0.184

Slotted ALOHA Time is divided into slots Maximum throughput 0.368

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

CSMA

User senses the medium before start transmission

Hold packets until the medium is free Strategies

1-persistent CSMA Non-persistent CSMA

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

CSMA

An example of collision in CSMA

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

CSMA

A typical cycle of CSMA operation

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

CSMA/CA

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Hidden Terminal and Exposed Terminal Problems

Hidden terminal problem

Exposed terminal problem

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Routing, Energy Efficiency and Network Lifetime

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Maximizing Network Lifetime

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Congestion Control in Wireless Networks

TCP is not suitable for wireless networks Basic assumption: all loss are due to buffer

overflow Suffers from frequent route failures and MAC

layer contention

TCP enhancements Link layer mechanisms Split TCP Explicit notification schemes

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Cross-layer Design and Optimization

“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

Cross-layer Principles

Interactions and the law of unintended consequences

Dependency graph Timescale separation and stability The chaos of unbridled cross-layer

design