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Wireless & Mobile Communication. Freeha Azmat. Mobile Radio Communication. In last 10 years, this industry is fueled by: Digital RF circuit Fabrication New Large Scale Circuit Integration Miniaturization Technologies which make portable radio equipment cheaper, smaller and more reliable.

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Presentation Transcript
mobile radio communication
Mobile Radio Communication
  • In last 10 years, this industry is fueled by:
    • Digital RF circuit Fabrication
    • New Large Scale Circuit Integration
    • Miniaturization Technologies which make portable radio equipment cheaper, smaller and more reliable
evolution of mobile communication
Evolution of Mobile Communication
  • 1946:
    • Mobile telephone services in 25 major American cities
    • 120KHz of RF bandwidth in half duplex mode
  • 1950 &1960:
    • IMTS(Improved Mobile Telephone service) came which offered full duplex communication
    • IMTS became saturated due to availability of less channels
slide5

1950 and 1960:

AT &T labs and other telecom companies developed the theory and techniques for cellular radiotelephony :

“The concept of breaking a coverage zone into small cells, each of which reuse portions of spectrum to increase spectrum usage at the expense of greater system infrastructure”

  • AT &T proposed the concept of cellular mobile system to FCC in 1968,although the technology wasn’t present to implement the concept.
slide6

In 1983 FCC allocated 666 duplex channels (40MHz spectrum in 800MHz band)

Additional 10MHz(166 channels) were allocated in 1989 which made the total spectrum of 50MHz

evolution
Evolution

AMPS (Advance Mobile Phone Service)

  • In 1970s,AT&T labs developed the first US cellular telephone system called the AMPS (Advance Mobile Phone Service)
  • By mid 1960s,the FM bandwidth of voice transmission was cut to 30KHz

ETACS(European Total Access Communication System)

  • Developed in 1980s
  • Identical to AMPS except the bandwidth was reduced to 25kHz
evolution cont
Evolution (Cont)

USDC (US Digital Cellular System) :

  • In 1991,the first digital cellular system hardware was installed in major US cities.
  • Support 3 users in the same 30kHZ bandwidth

CDMA (Code Division Multiple Access):

  • Cellular system based on CDMA
  • Can support variable users in 1.25MHz wide channel
  • Improvement in capacity due to FM techniques
types of mobile radio systems
Types of Mobile Radio Systems:

1)Simplex

  • Radio/TV broadcast

2)Half-Duplex

  • push to talk and release to listen

3) Full Duplex:

  • Cell Phone
  • Full duplex requirement:
    • FDD
    • TDD
frequency division duplexing fdd
Frequency Division Duplexing(FDD)
  • Simultaneous Radio transmission channels for the subscriber and base station.
  • To facilitate FDD, it is necessary to separate the transmit and receive frequencies by about 5% of the nominal frequency.
time division duplexing
Time Division Duplexing
  • Share a single radio channel in time
  • Portion of the time consumed from base station to mobile and vice versa
  • Preferred for indoor or small area wireless applications

Do you know why?

comparison of fdd and tdd
Comparison of FDD and TDD:
  • FDD is efficient in case of symmetric traffic
  • It makes radio planning easier because base stations do not hear each other.
    • With TDD systems, guard bands between neighboring base stations is necessary
  • TDD has a strong advantage where asymmetry of the uplink and downlink data speed is variable.
    • As the amount of uplink data increases, more bandwidth can dynamically allocated to that and vice versa
paging systems
Paging Systems
  • Those communication systems that send brief messages to subscriber. The message may either be
    • A numeric message
    • An alphanumeric message
    • A voice message
  • The issued message is called Page. In modern Paging system, news headlines, stock quotations and faxes may be sent
  • Paging systems vary on the basis of complexity and coverage area
a wide area paging system
A wide area Paging System
  • Simulcast transmitters can be located in the same service area or in different cities and countries
a cordless telephone system
A cordless Telephone system
  • 1st generation Cordless Telephone systems
  • 2nd Generation
a cellular system
A Cellular System

January, 2006

definitions acronyms
Definitions/Acronyms
  • CAI: Common Air Interface
    • For communication between the base station and the mobile
    • It has 4 different channels
      • FVC: Forward Voice Channel (from base station to mobile)
      • RVC: Reverse Voice Channel
      • FCC: Forward Control Channel
      • RCC: Reverse Control Channel
      • ** Control channels are often called setup channels because they are involved in setting up a call and moving to unused channel
      • **Control channels contain handoff instructions
      • ** Control channels make up about 5% of the total channels

January, 2006

definitions acronyms contd
Definitions/Acronyms (contd.)
  • MSC: Mobile Switching Center also called
  • MTSO: Mobile Telephone Switching office
  • PSTN: Public Switched Telephone Network

January, 2006

call setup procedure
Call setup Procedure:
  • 1.ESN(Electronic Serial Number):

Is unique 32bit identification number embedded in a wireless phone by the manufacturer. Each time a call is placed, the ESN is automatically transmitted to the base station.ESN cannot easily be altered in the field.ESN can be checked electronically to prevent the fraud.

2 min mobile identification number
2.MIN(Mobile Identification number)
  • Is 24 bit number corresponding to the actual 7 digit telephone number assigned by the cellular carrier exclusively to a phone, used for billing and for receiving calls.
  • The MIN is paired with ESN. Theoretically both numbers are verified, and in combination, every time a call is placed in order to verify the legitimacy of the call and device
3 system identification number sid
3.System Identification Number(SID)
  • Is unique 5-digit number that has been assigned to identify the particular cellular carrier i.e. the service provider, from whom you are obtaining service. This number identifies your home system
how a cellular telephone call is made from land line to mobile

FCC

Free channels

MIN

RCC

How a Cellular Telephone Call is MadeFrom Land line to Mobile

MIN: mobile identification number

PSTN

MSC

MIN

January, 2006

how a cellular telephone call is made from mobile to land line

Free channels

RCC

MIN/telephone

MIN/telephone #

How a Cellular Telephone Call is Made From Mobile to Land line

MIN: mobile identification number

PSTN

MSC

January, 2006

frequency reuse
Frequency Reuse
  • The problems with cellular concept was:
    • Spectral congestion
    • User capacity
linear cells as an example of frequency reuse

f1

f2

f3

f1

f2

f3

P

I

Cell 1

Cell 2

Cell 3

Cell 1

Cell 2

Cell 3

Cluster 1

Cluster 2

Linear Cells as an Example of Frequency Reuse

Total Band width (BW) is divided into three adjacent bands f1,f2 and f3

Such that BW = f1+f2+f3

cluster size

3

4

3

1

1

2

2

3

3

1

4

3

4

2

3

1

1

2

2

1

2

Cluster Size

3 Cell Cluster

4 Cell Cluster