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Wireless and Cellular Communications

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					Wireless and Cellular
  Communication
Dagoberto Lopez
TEL660
16 Feb 2006
               Wireless Topics
   Wireless Devices and Applications

   The Foundation of the Cellular System Architecture

   The Mobile Telephone Switching Office

   Wireless Multiplexing

   Cellular and PCS services
   Wireless Devices and Applications
Wireless- Describes methods of telecommunication that use electromagnetic waves
   to carry data and voice over the communication path rather than wire conductors
   for telecommunications.


       Category                 Description
       Fixed Wireless           Devices that are connected to the Internet using special
                                modems (wireless DSL [Digital Subscriber Lines]) in homes
                                and Offices


       Mobile Wireless          Devices (Mobile Phones) that are used from motorized
                                moving vehicles, such as automobile, buses, trains, and
                                boats.


       Portable Wireless        Battery-powered wireless devices, such as cellular phones
                                and PDA's, which travel with the user from office to home
                                to vehicle


       IR Wireless              Devices such as wireless hubs that use infrared radiation
                                (IR) to convey data. Laptops use wireless adapter cards for
                                their network interface to the wireless hub. They are
                                normally used for limited-range communication.
        Levels of Mobile communication
Mobile Voice Communications- Standard voice service is
    offered with connections established to land lines to
    communicate with regular phone users

Mobile Information
    -The retrieving of emails from office
    -Instant messaging or two way messaging
    -Access to yellow pages and
    -Mobile services have established partnership with
    companies like AOL and Yahoo in order to provide
    design for mobile phone users

Mobile E-Commerce
    -Features are more enhanced
    -Able to pinpoint a mobile user’s wireless location
    -Mobile users have the capability to perform one-
    click transactions
   Cellular System Architecture
-Each region consist of the following
 Cells
 Clusters
 Frequency Reuse
 Cell Splitting
 Handovers

-Guidelines apply to both rural and urban regions
   Cellular System Architecture
Cells
 Cells are base stations transmitting over small
  geographic areas.
 Cellular- refers to communication systems that divide a
  geographic region into sections. (Cells)
 Base stations communicate with cellular phones through
  a channel.
 channel provides two frequencies
  -receiving
  -transmitting
Cellular System Architecture
     Cellular System Architecture
   Two cells can use the same frequency for different
    conversations as long as the cells are not adjacent to
    one another.
   Cells are given a set number of frequencies
    Cellular System Architecture
Clusters
 A cluster is a group of cells or base stations.
 Do not re-use channels
 Boundaries for communication.
   Cellular System Architecture
Frequency Reuse
 Frequencies were limited during dev. of mobile
  telephone system
 small number of radio channel frequencies available
 Channels were reused to provide more than one
  conversation at a time
 Each cell is assigned a group of channels different from
  its neighboring cell
 Same group of channel can be reused in different cells
  -footprint (boundary coverage of a cells)
 Frequency reused is still a common practice today
   Cellular System Architecture
Handovers
 Handovers- designed to manage communication when a
  cellular phone user travels from one cell to another
  during a call.
 Adjacent areas do not use same same frequency
  channels.
 Calls need to be transmitted from one channel to another
 Phone reception also becomes weak when user moves
  out of cell coverage
 Handover switches the call to a stronger frequency
  channel in a new cell. (user does not notice this)
   Cellular System Architecture
Cell Splitting
 Phone carrier’s area becomes full of users
  -In return service is compromised
 Cell splitting allows a single area to be split into many
  areas to provide acceptable service levels
                        Frequency
   Cell phones use radio waves to transmit and receive signals.
   Different frequencies are provided to manage transmission of
    several services through the air
   In wireless communication the frequency of a signal is related to the
    wavelength
             w = 300/f   and conversely   f = 300/w
   Each radio wave is produced by a cycle of electric current in a
    transmitting antenna. w/frequency of current being the same as the
    wave frequency.
   Radio frequency is measured as the number of cycles transmitted or
    received in 1 second.
   The FCC controls radio frequency transmission in the U.S.
Frequency
                Frequency Bands
   Cellular phones and base
    stations use frequency Band A
    &B
   PCS however uses more bands
   Cellular systems operate
    between 824 MHz and 894
    MHz
   PCS operates in the 1850 MHz
    – 1990 MHz bands
    Mobile Telephone Switching Office (MTSO)

    A cellular systems main mobile switching center
    Each mobile telephone carrier has one at CO of a Telco.
    Provides centralized management of phone owner and
     service provider.
    Communicates with mobile phones using special codes
     -identify the phone
     -the phone’s owner
     -the service provider
        Mobile Telephone Switching Office

Mobile telephone codes
  Electronic Serial Number (ESN)- a unique 32-bit number created when
   phone is manufactured.
 Mobile Identification Number (MIN)- a 10-digit number derived from phone
   number.
 System Identification Code (SID)- a unique 5-digit number assigned by the
   FCC.
-ESN is permanent
-MIN and SID are programmable.
        Mobile Telephone Switching Office

Communication process between mobile phones and the MTSO




-The phone listens for an SID over the control channel
-control channel is a special frequency that is used by base station and
   phone (talking)
-special frequency also used for call setup and channel changing
-No control channel found “No Service”
      Mobile Telephone Switching Office

-If signal is found by MTSO then it reads the SID
-It compares the SID to the one programmed on the phone




-If they match then the phone knows in what cell it is
    communicating in
-mobile phone along with SID transmit a registration
    request
        Mobile Telephone Switching Office

-Then MTSO gets the call and tries to find you, it will also look in its
     database to see which cell you are in.
-It then selects a frequency pair that your phone will use in that cell to
     receive the call.
-Then the MTSO communicates with the mobile phone over the control
     channel and tells it the frequencies to use for your phone and the
     tower switch.
-Once you are on the call then base stations communicate with one
     another through the MTSO.
               Frame Transmission
-allows for higher level of connectivity
    along with multiplexing
-carry the conversion or data along
    with error detection and correction
    bits
-slots- hold individual call information
    within a frame
-two time slots make up one voice
    circuit
-other slots are used for data
-multiplexing uses time slots to allow
    various calls to occupy one
    channel
               Wireless Multiplexing
Frequency Division Multiple Access
   (FDMA) - Each cell is on a separate
   frequency
  Primarily used for analog transmission
  Voice channels are split into identical
   sections of bandwidth
  Used with Advance Mobile Phone
   Service (AMPS)-standard system for
   analog signal cellular telephone
   service.
             Wireless Multiplexing
Time Division Multiple Access
   (TDMA)- Assigns each call a
   certain “slice of time” on a
   designated frequency.
 Used with digital cellular
   telephone communication.
 Divides each channel into 3 time
   slots
 Used with GSM technology
   (Global system for mobile
   communication)
 Use SIM cards (subscriber
   identification module)
 Digitizes and compresses data to
   send it down a channel with other
   data
             Wireless Multiplexing
Code Division Multiple Access
  (CDMA) – A unique code is
  assigned to each cell and spreads
  it over the available frequencies.
 Spread –spectrum technology to
  provide wider channels for comm.
 Allows several signals to occupy a
  single transmission channel
 Combines analog-to digital
  conversation and spread spectrum
  technologies
 No frequency re-use
 Good for handovers
    Cellular and PCS services/devices
  Personal Communication Services (PCS)- services that
   offer personal service and extended mobility. (wireless
   internet services)
Basic Phone Functions
-Store contact information
-Send and receive E-mail
-Send and receive text messages or pictures
-Integrate with other devices (PDA’s, MP3 players, GPS
   receivers etc..)
                Wireless Devices
Smart Phones
-They have more features installed then your average phone.
-Built in keyboards
-Internet ready
-personal digital assistant (PDA) or a Trio
Wireless Devices
                       Blackberry
Blackberry
-Service is always on
-End-to-End-Solution [complete email, messaging, organizer and
   calling solution]
-Built in keyboard, thumb-operated trackwheel and integrated speaker
   and microphone
-Blackberry servers
-Blackberry Redirector is an option if server not available
        Wireless Network Cards
-Card allows access to web and email from almost any sight.
-Available in major airports
-The card acts as a cell phone in order to access the Web.
-High Speed where available (EV-DO technology)
-average download speeds of 400-700 kbps capable of reaching up to
   2.0Mbps. (VerizonWireless network)
-Broadband and National access
                Wireless Service
Precision Locator
 Locate , monitor and manage workers through their mobile device in
   real time.
 Phone acts as a GPS tracking device along with software
 Productivity- Allows to increase job load
 Efficiency- Adjust on the fly as calls are requested
 Flexibility- Ideal for many types of businesses
 Simplicity- One time setup (provider takes care of rest)
 Will help increase productivity and revenue
                    References:
•   http://www.verizonwireless.com
•   http://www.sprint.com
•   Trivedi, Carol, “Wide Area Networks”; EMCParadigm 2004

				
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