1. Overview on Communications Systems
Wireless Information Networking Group (WING)
Overview on Communications Systems
EEL 6507: Queueing Theory and Data Communications

2. Overview on Communications Systems
Wireless Information Networking Group (WING)
Overview on Communications Systems
Why do we need this course
This course is to present the methods for the design of the computer communication networks to support so many interesting applications. The tools developed in this course can be used for the network design, service provisioning, and resource dimensioning.

3. Motivating Examples Example 1 Solution
Wireless Information Networking Group (WING)
Motivating Examples
Example 1
You just join a company, which is in the process of upgrading their systems. You are asked to evaluate the computer networks system, create a budget plan for the company. What should you do?
Solution
Evaluate the traffic demand and potential future traffic, decide how much network capacity is necessary, then carry out a cost analysis, etc.

4. Motivating Examples (cont.)
Wireless Information Networking Group (WING)
Motivating Examples (cont.)
Example 2
A major WAN service provider (ATT/Verizon) intends to install an optical fiber link between Gainesville and Orlando, you are responsible for the link design? What should you do?
Solution
Predict/analyze the traffic the link has to handle and the service characteristics, possibly the QoS requirements, then decide how many wavelengths you need in the waveguide.

5. Motivating Examples (cont.)
Wireless Information Networking Group (WING)
Motivating Examples (cont.)
Example 3
A wireless services provider just won an FCC auction bid for a chunk of frequency to be used, you are hired with big bucks to figure out how to build their wireless networks in Gainesville area. In one week, you have to propose the building plan, what should you do?
Solution
Figure out what you need: man power, resources, field study etc. You have to hire a traffic engineer to perform the traffic analysis!

6. Motivating Examples (cont.)
Wireless Information Networking Group (WING)
Motivating Examples (cont.)
Example 4
You study computer sciences and want to do a business on web hosting. How much money do you want to spend for your server?
Solution
Predict/analyze the traffic to your web hosting server and determine how much storage, traffic capacity, etc

7. Motivating Examples (cont.)
Wireless Information Networking Group (WING)
Motivating Examples (cont.)
Example 5
Tmobile intends to add a new base station near Oaks Mall, you are a communications engineer and asked to come up with a plan for the needed facilities
Solution
Determine the coverage size and potential traffic accommodation (in and out traffic, etc)
According to the quality requirement, determine how much bandwidth is needed

8. Purpose of the Course Provides analytical tools for Traffic analysis
Wireless Information Networking Group (WING)
Purpose of the Course
Provides analytical tools for
Traffic analysis
Resource dimensioning
Quality of service provisioning

9. Historical Overview Communications systems
Wireless Information Networking Group (WING)
Historical Overview
Communications systems
Primitive forms of communications (e.g., smoke signals)
Marconi’s experiments on radio communications (wireless telegraphy) in 1897
Armstrong’s FM technology revolution in 1938
Shannon’s paper and information theory in 1948
von Neuman’s paper and invention of computers in 1948
Central computers to remote terminals and other peripheral devices (1950s)
Network with one central processors but with shared links

10. Historical Overview (cont.)
Wireless Information Networking Group (WING)
Historical Overview (cont.)
Communications systems (cont.)
1970s: Aloha systems for packet radios
“Russians are coming” 
DARPA projects: robust comm net design
ARPANET and TYMNET

11. Historical Overview (cont.)
Wireless Information Networking Group (WING)
Historical Overview (cont.)
Communications systems (cont.)
Internet (1980s) /wireless AMPS
World Wide Web /second generation wireless (GSM)
Internet telephony /third generation wireless (3G, Wi-Fi)
Digital age: paradigm shifts
Wireless Internet / Ubinet: Ubiquitous Networking
Any one, anywhere, anytime, any form, with flexible data rate---future generation telecommunication networks!
Cyberspace!

12. Applications Remote access and computing, file transfer
Wireless Information Networking Group (WING)
Applications
Remote access and computing, file transfer
Remote update and transactions
Electronic mail
Telephony: voice services
Video conferencing
Internet surfing
E-commerce
Telemedicine
Internet Faxing, Internet Telephony, …

13. Applications (cont.) Internet gaming (Internet entertainment)
Wireless Information Networking Group (WING)
Applications (cont.)
Internet gaming (Internet entertainment)
Digital content dissemination (youtub, …)
Distance learning
Digital library (e-books…)
Web publishing (blogs,…)
Fight crimes including cyber crimes (phishing, …) …
“We cannot live without Internet!”
“We could not live without iPhone!” …

14. Communications Technology
Wireless Information Networking Group (WING)
Communications Technology
Wired: cable or optical fiber or powerline or phoneline—high speed
Wireless: radio, microwave, infrared, satellite—convenience

15. A Communications Model
Wireless Information Networking Group (WING)
A Communications Model

16. Data Communications Model
Wireless Information Networking Group (WING)
Data Communications Model

17. Wireless Information Networking Group (WING)
Communications
The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point
(Claude Shannon, The Mathematical Theory of Communication)
“garbage” at one point is moved around in the network without any change, i.e., the same “garbage” 

18. Information Transfer Units
Wireless Information Networking Group (WING)
Information Transfer Units
Messages: independent data unit which has its meaning itself.
Packets: Parts of a message, used for easier information transfer, the concept which revolutionized the data communications.

19. Switching Circuit switching (message switching)
Wireless Information Networking Group (WING)
Switching
Circuit switching (message switching)
Packet switching (store-and-forward)– second revolution
Virtual circuit switching: resource sharing idea—third revolution (ATM)

20. Layering Network Design
Wireless Information Networking Group (WING)
Layering Network Design
Reference Model

21. Layering Network Design
Wireless Information Networking Group (WING)
Layering Network Design
TCP/IP Model
Application layer
Host-to-host, or transport layer
Internet layer
Network access layer
Physical layer

22. OSI v TCP/IP Wireless Information Networking Group (WING)
There are a number of reasons why the TCP/IP architecture has come to dominate. Perhaps the most important is that the key TCP/IP protocols were mature and well tested at a time when similar OSI protocols were in the development stage. When businesses began to recognize the need for interoperability across networks, only TCP/IP was available and ready to go. Another reason is that the OSI model is unnecessarily complex, with seven layers to accomplish what TCP/IP does with fewer layers. Stallings DCC8e Figure 2.7 illustrates the layers of the TCP/IP and OSI architectures, showing roughly the correspondence in functionality between the two.

23. Network Performance Network throughput—network capacity
Wireless Information Networking Group (WING)
Network Performance
Network throughput—network capacity
Network delay— point-to-point, end-to-end
Network dimensioning— resource (storage and transmission)
QoS—voice, data, multimedia —more important than ever
Connection blocking and dropping

24. Connections Sessions Modeling such processes are very important:
Wireless Information Networking Group (WING)
Connections
Sessions
A process for fulfilling the communications between two end points or one point with many points.
Modeling such processes are very important:
Message arrivals: the rate and the variability
Session holding time
Message length: mean and its distribution