Communications systems and networking – part 2

1. COMMUNICATIONS SYSTEMS AND NETWORKING – PART 2
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

2. ADDRESSES
 Trudelle Street, Toronto, Ontario, Canada
 Shimultuly, Gazipur, Bangladesh
 Justetc Computers
 Habib Complex, 2nd Floor
 Contact us
 Sayed: sayed@justetc.net (647-624-8509)
 Rafik: 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. OUR SERVICES
 I provide consulting under Justetc (Just et cetera) Technologies, Canada
 I provide consulting on
 Software Development
 Web Development
 Software Engineering
 Software and Information Architecture
 Mobile Development
 Business Analysis
 I have several years of professional experience in different areas of IT,
Computer Science, and Software & Computer Engineering
 My education and experience exposed me to many abstraction levels of
computing; from the lowest level to the highest level (electronics, digital
system design, computer networks, data communications, databases,
software engineering, software development to web development)

5. MOBILE COMMUNICATION
 In general, In mobile telephone system
 Data and information are communicated
 Between two or more mobile devices (i.e. mobile
handsets)
 Between one mobile device and one standalone
device (telephone)
 Mobile phones also communicate with base stations
 Base stations also communicate with each other as
required

6. CONCEPT OF CELLULAR NETWORK
 The provider of mobile communication
service
 Divides the coverage area into smaller areas
known as cells
 In each cell, there is a base station with usually
one antenna
 Base stations are controlled from a mobile
switching center
 Connecting calls
 Call information recording
 Computerized billing system

7. CONCEPT OF CELLULAR NETWORK
 Cellular networks use radio frequency for
communications
 Cells can be hexagonal, square, circular, or
of irregular shapes
 For each cell a range of radio frequency is
allocated
 The same frequency range can be allocated
for another cell but not for the neighbour cell

8. CELL SIGNAL ENCODING
 FDMA
 Requires that neighboring cells use different frequency
range
 CDMA
 PDMA and TDMA cannot be used to divide cells
 TDMA can be used with FDMA and CDMA to create
many channels in the same cell
 http://electronicdesign.com/communications/fundame
ntals-communications-access-technologies-fdma-
tdma-cdma-ofdma-and-sdma
 http://www.shamasis.net/2002/09/the-demise-of-
fdma-cellular-transceiving-technology/

9. MOBILE UNIT
 Main Components
 One control unit
 One transceiver
 One antenna system
 Other components
 A battery
 Key-pad or touchpad
 SIM (GSM), R-UIM (CDMA)
 IMEI – unique device identification number for GSM,
WCDMA, iDEN, and some satellite phone device
 ,

10. PHONE TECHNOLOGIES
 Technologies
 GSM (Global System for Mobile Communications)
 CDMA (Code division multiple access)
 GSM
 Third generation of GSM is known as UMTS (Universal Mobile
Telecommunication System)
 In Bangladesh Grameenphone, Banglalink, Teletalk, and Airtel use GSM
 GSM uses FDMA with TDMA
 In FDMA,
 the number of Channels is: 124
 Each channel is: 200 KHz
 Uplink and Downlink: 935 to 960 MHz
 Duplex separation: 45 MHz
 When TDMA is used in 200 KHz channel, one frame can contain 8 time slots
 Frame time: 4.615 milli second
 GSM improves TDMA for Mobile Radio Station

11. USE OF GSM
 Four frequency range:
 GSM 400, GSM 900, GSM 1800, GSM 1900
 Advantages
 Roaming
 Frequency hopping
 High quality continuous connectivity
 GPRS and EDGE facility
 SIMs are easy to use
 High quality digital voice
 SMS service, MMS Service

12. ADVANTAGES OF GSM
 Most popular
 Used in around 218 countries
 Can support/integrate third generation of
mobile technologies
 Provides secure communications

13. DISADVANTAGES OF GSM
 Some interference (Audio Amplifier)
 Comparatively high electricity consumption
 Maximum cell size: 120 KMs (Previously 35
KMs)

14. CDMA
 Invented by Qualcom
 Spread in 1995
 Data can be sent with the same frequency but
with different code/encoding for each message
 2nd generation technology
 Became 3rd generation technology on 1999
 Wideband CDMa: 5 MHz
 Each receiver has a unique code. Messages
with any other code are regarded as noise

15. ADVANTAGES OF CDMA
 Very low transmission power
 Less radiation
 GSM: 600 milliwatt to 2 watt, CDMA: max 200
milliwatt
 Advanced soft switching is used; so no specific
hardware for switching
 Less noise, high quality of voice
 With the same bandwidth CDMA is 4 or 5 times
more capable than GSM

16. DISADVANTAGES OF GSM
 Roaming is limited
 Need to use special phone set
 Less popular
 With increased number of users, call quality
decreases

17. GENERATIONS OF MOBILE
 First Generations
 1983: AMPS – Advanced Mobile Phone System
 Uses analog signal
 Uses FDMA to separate channels
 Two analog channels were used: forward (base to
mobile), reverse (mobile to base)
 Movement disconnects the call
 Microprocessor and semiconductor are used in units
 Signal frequency comparatively low
 AMPS, NMT (Nordic), TACS (Total Access), CT/1

18. GENERATIONS OF MOBILE
 2nd generation
 Initiated noise removal from voice
 Transmits voice using digital technologies
 D-AMPS – 2nd generation of AMPS
 D-AMPS starts to use TDMA with FDMA
 CDMA was invented at this generation
 D-AMPS, CT2, IS-136, GSM, PDC, IS-95
(CDMA), and CDMAONE all use 2nd generation
mobile phones

19. 2ND GENERATION
 Starts to use Digital radio signals as semiconductor
and microwave technology got improved
 Digital modulation is used
 Faster transfer of data
 Improved data security
 Pre-paid service
 Limited international roaming
 Packet switching network for data communications
 Core switch network for voice call
 SMS and MMS
 Both data and voice can be transmitted

20. 2ND GENERATION
 Can be interfered with other carriers
 Call does not get disconnected if the people
move
 Example: GSM 900, GSM 1800, GSM 400,
D-AMPS, CDMA, PDA

21. 3RD GENERATION
 1992
 Plan
 Voice quality should be like the telephone
system
 Data Speed: running cars: 144 Kbps, Walk: 384
kbps, home: 2 Mbps
 Bandwidth: 2 MHz
 Internet facility
 On 2001, DoCoMo in Japan started 3rd
generation mobile system for the first time

22. 3RD GENERATION
 CDMA with W-CDMA became 3rd generation
 W-CDMA = UMTS
 High speed data transfer and use of multimedia data
 HSPA (High Speed Packet Access) got implemented
in this generation
 Data Transfer: both packet and circuit switching
 Packet switching: fast data and picture transfer
 Mobile phone can use Internet and data transfer
(built-in modem)
 EDGE helps to transfer more data
 High speed data transfer, More than 2 Mbps

23. 3RD GENERATION
 Mobile banking, mobile ecommerce
 GSM, EDGE, UMTS, CDMA 2000
 Radio frequency : W-CDMA, UMTS
 Channel Access: TD-SCDMA and TD-CDMA
 Mobile phones:
 Listen to music, watch TV and Cinemas, download
 Internet browse, internet gaming, game download
 Video conferencing
 All time internet
 Different methods to pay bills: pay per bit, pay per session, flat
rate
 UMTS, IMT - 2000, MC-CDMA, TD-SCDMA, EDGE,
HSPA

24. 4TH GENERATION
 Technology for the future
 Use of IP instead of Circuit Switching or Packet
Switching
 Ultra broadband internet in mobile system
 Running device speed: 100 Mbps, Standalone
device speed: 1 Gbps
 Will be used for
 Mobile web access, IP telephony, gaming services,
hi-definition mobile television, video-conferencing, 3d
television

25. 4TH GENERATION
 LTE (Long Term Evolution)
 4G system that provides 326 Mbps peak bit rate
 Can be WiMax or Flash-OFDM Wireless
Metropolitan area network based
 Broadband wireless speed 233 Mbps for mobile users

26. Thanks
Any Concerns?
http://ask.justetc.net

27. COMMUNICATIONS SYSTEMS AND NETWORKING – PART 2
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