This document discusses communications systems and networking by Sayed Ahmed. It provides an overview of communication systems, including computer-to-computer and computer-to-device communication. It also discusses communication media like telephone lines, fiber optic cables, and microwave transmission. The document then covers key concepts in data communications including transmission methods, bandwidth, data transmission speed, and wired and wireless communication mediums.

1. COMMUNICATIONS SYSTEMS AND NETWORKING: PART 1
Sayed Ahmed
BSc. Engineering in Computer Science and Eng. (BUET, Bangladesh)
MSc. In Computer Science, University of Manitoba, Canada
Owner
Justetc (Just et cetera) Technologies, Canada
http://www.justetc.net
http://sayed.justetc.net
sayed@justetc.net

2. ADDRESSES
 Trudelle Street, Toronto, Canada
 sayed@justetc.com
 Shimultuly, Gazipur, Bangladesh
 Justetc Computers
 Habib Complex, 2nd Floor
 rafik@justetc.com (01942747702)

3. FREE TRAINING BY JUSTETC
 Training and Education in Bangla:
 http://Bangla.SaLearningSchool.com
 Training and Education in English:
 http://www.SaLearningSchool.com
 http://English.SaLearningSchool.com
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 Ask questions and get answers
 http://Ask.JustEtc.net
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 Offline IT Training:
 http://University.JustEtc.net

4. COMMUNICATION SYSTEM
 Communication System
 Computer to Computer
 Computer to other devices
 Communication Media
 Telephone Line
 Fiber Optic Cable
 Microwave
 An Example

5. COMMUNICATION SYSTEM
 An example
 Computer to computer through Modem
 using Telephone system
 Information from the source computer is
converted to analog signals and passed over
telephone line
 Modem does the conversion work
 On the receiving end, modem again converts
analog signal to digital signal and supplies to the
destination computer

6. CONCEPTS BEHIND DATA COMMUNICATIONS
 Elements of Data Communication System
 Source - computer
 Transmitter - modem
 Communication channel/medium – telephone
line
 Receiver - modem
 Destination - computer

7. BANDWIDTH: DATA TRANSMISSION SPEED
 Narrow Band
 45 to 300 bps
 Low speed
 Example: telegraph
 Voice Band
 Speed upto 9600 bps
 Used in telephone line, computer to printer
communications
 Broad Band
 Minimum speed 1 Mbps
 Coaxial and optical fiber
 Satellite communications and microwave
communications

8. METHODS OF DATA TRANSMISSION
 Methods
 Asynchronous
 Synchronous
 Isochronous
 Asynchronous Transmission
 Data can be transmitted intermittently rather than a steady stream,
no external clock signal
 data is not transmitted at regular intervals, thus making possible
variable bit rate, and that the transmitter and receiver clock
generators do not have to be exactly synchronized all the time.
 Exception: R2-232
 Keyboard to computer
 asynchronous transmission is used commonly
for communications over telephone lines.


9. SYNCHRONOUS TRANSMISSION
 Synchronous Transmission
 Data is sent as Blocks
 Data transfer method in which
 a continuous stream of data signals is accompanied by
timing signals (generated by an electronic clock)
 to ensure that the transmitter and the receiver are in step
(synchronized) with one another
 Most network protocols (such as Ethernet, SONET,
Token Ring) use synchronous transmission

10. ISOCHRONOUS TRANSMISSION
 Isochronous Transmission
 Improved synchronous transmission
 Data transmission delay is kept to be the
minimum between two blocks
 Used in real time data transfers

11. DATA TRANSMISSION MODE- DATA FLOW
 Simplex
 Half-Duplex
 Full-duplex

12. DATA TRANSMISSION MODE- DATA FLOW
 Simplex
 One way transmission
 Radio, TV
 Half-Duplex
 Both way transmission possible
 But at one moment, only in one direction
 Waki-taki
 Full Duplex
 Data can be transmitted in both ways at the same
time
 Telephone, mobile

13. DATA TRANSMISSION MODE
 Unicast
 Simplex, half-duplex, full-duplex
 Broadcast
 Multicast

14. DATA COMMUNICATION MEDIUM
 Wired
 Co-axial
 Twisted-pair
 Fiber optic

15. WIRELESS MEDIUMS
 Radio
 10 khz to 1 ghz
 Speed: 24 kbps
 Controlled/Open
 Microwave
 Terrestrial
 Satellite

16. MICROWAVE
 Frequency range:
 300 MHz to 300 GHz
 Data Transfer Speed: 1 Gbps
 RF Engineering: lower boundary at 1 GHz (30 cm),
and the upper around 100 GHz (3 mm).
 Can transmit data, voice, picture
 Usually uses Transmitter and Receiver
 Terrestrial
 Uses line of sight
 Should not be any block between transmitter and
receiver

17. TERRESTRIAL MICROWAVE

18. SATELLITE MICROWAVE

19. SATELLITE MICROWAVE
 Low orbit satellite
 Slow
 Could not cover the whole world
 Geosynchronous satellite
 Rotates at the same speed of the earth
 Components of satellite
 Receiver
 Receiver antenna
 Transmitter
 Transmitter antenna

20. WI-FI
 Uses radio wave
 Can help to connect to internet
 Can be used to create wireless LANs among computers
 a popular technology that
 allows an electronic device
 to exchange data
 or connect
 to the internet wirelessly using radio waves.
 The Wi-Fi Alliance defines Wi-Fi as any "wireless local area
network (WLAN) products that are based on the IEEE 802.11
standards
 However, since most modern WLANs are based on these
standards, the term "Wi-Fi" is used in general English as a
synonym for "WLAN"

21. WI-FI
 Advantages
 You can create WLAN where using cable is
difficult
 Most laptops have WI-FI, so you can easily
connect to WI-FI hot spots
 Disadvantages
 Data transfer slow
 Coverage limited
 Data security is an issue
 Network Security is also an issue

22. WIMAX
 A standards-based technology enabling the
delivery of last mile wireless
broadband access as an alternative
to cable and DSL

23. WIMAX
 Speed
 June 2005: 30 to 40 megabit-per-second data rates
 2011: 1 Gbps
 4G mobile technology
 75 Mbps for mobile communications
 Video + data
 WiMAX is sometimes referred to as "Wi-Fi on
steroids"and can be used for a number of
applications including broadband connections,
cellular backhaul, hotspots, etc. It is similar to Wi-Fi,
but it can enable usage at much greater distances

24. WIMAX USES
 The bandwidth and range of WiMAX make it
suitable for the following potential applications:
 Providing portable mobile broadband connectivity
across cities and countries through a variety of
devices.
 Providing a wireless alternative to cable and digital
subscriber line (DSL) for "last mile" broadband
access.
 Providing data, telecommunications (VoIP)
and IPTV services (triple play).
 Providing a source of Internet connectivity as part of
a business continuity plan
 Smart grids and metering

25. ADVANTAGES OF WIMAX
 Competes with Microwave
 Can provide internet access to remote areas
 A very good alternative to DSL and Cable
Modem
 Can be used in Smart Grids and Metering

26. DISADVANTAGES
 After 50 kms, speed becomes <= 70 mbps.
With increased distance more base stations
are required
 Bad weather can affect the signal

27. REFERENCES
 Wikipedia

28. Thanks
Any Concerns?
http://ask.justetc.net

29. COMMUNICATIONS SYSTEMS AND NETWORKING
Sayed Ahmed
BSc. Engineering in Computer Science and Eng. (BUET)
MSc. in Computer Science, University of Manitoba, Canada
Owner
Justetc (Just et cetera) Technologies, Canada
http://www.justetc.net
http://sayed.justetc.net
sayed@justetc.net