Wireless _ Mobile Communication - More from yimg.com

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					Wireless & Mobile
          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
Electronics boom :
Evolution of Mobile
 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
 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.
 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
Frequency Allocation in the US for AMPS

           January, 2006
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
   Developed in 1980s
   Identical to AMPS except the bandwidth was reduced
    to 25kHz
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
Major Mobile Radio Standards in North America

            January, 2006
Major Mobile Radio Standards in Europe

            January, 2006
Major Mobile Radio Standards in Japan

          January, 2006
Wireless Communications System Definitions:

            January, 2006
Wireless Communication System
Types of Mobile Radio Systems:
   Radio/TV broadcast
   push to talk and release to listen
3) Full Duplex:
   Cell Phone
   Full duplex requirement:
     FDD
     TDD
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
 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
  Do you know why?
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
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
•Simulcast transmitters can be located in the same service area or in
different cities and countries
A cordless Telephone system

  •1st generation Cordless Telephone systems
  •2nd Generation
A Cellular System

        January, 2006
  •   CAI: Common Air Interface
      •   For communication between the base station and the mobile
      •   It has 4 different channels
           1. FVC: Forward Voice Channel (from base station to mobile)
           2. RVC: Reverse Voice Channel
           3. FCC: Forward Control Channel
           4. RCC: Reverse Control Channel
           ** Control channels are often called setup channels because
              they are involved in setting up a call and moving to unused
           **Control channels contain handoff instructions
           ** Control channels make up about 5% of the total channels
                    January, 2006
Definitions/Acronyms (contd.)
    • MSC: Mobile Switching Center also called
    • MTSO: Mobile Telephone Switching office
    • PSTN: Public Switched Telephone Network

              January, 2006
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
2.MIN(Mobile Identification
 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
 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
  MIN: mobile identification number

                                           Free channels
                                     MIN        RCC
        PSTN           MSC


                     January, 2006
Timing Diagram Illustration for
Call from Land line to Mobile

                            January, 2006
How a Cellular Telephone Call is Made
From Mobile to Land line

MIN: mobile identification number

                                                     Free channels
      PSTN           MSC
                                   MIN/telephone   MIN/telephone #

                   January, 2006
Timing Diagram Illustration for
Cal from Mobile to Land line

                            January, 2006
  Frequency Reuse
 The problems with cellular concept was:
   Spectral congestion
   User capacity
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
      f1           f2           f3      f1         f2          f3

            P             I

   Cell 1        Cell 2       Cell 3   Cell 1     Cell 2      Cell 3

                Cluster 1                       Cluster 2
Cluster Size

        3 Cell Cluster               4 Cell Cluster

                                                         3       4
                         1       3       4       2
    3                                1
           1                 2
                                             3           4
                   3                                 1
                         1               2

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