Communications systems and networking
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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.
Communications systems and networking
- 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 -------------------------------------------------------------------------- ------------------------ Ask questions and get answers http://Ask.JustEtc.net -------------------------------------------------------------------------- ------------------------- 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
- 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
- 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