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“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
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“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
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“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
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“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
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“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
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“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
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“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)
Encapsulation and Multiplexing
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“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
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“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
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“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)
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“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
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“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
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“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
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“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
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“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
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“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
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“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)
Perfect Simulation
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“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
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“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
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“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
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“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
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“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
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“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
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“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
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“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
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“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
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“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
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“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)
CSMA/CA
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“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
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“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
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“Cognitive Radio Communications and Networks: Principles and Practice”By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)
Maximizing Network Lifetime
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“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
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“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
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“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