GF82.70-P-0007-06CW General Information on Mobile Phone System

GF82.70-P-0007-06CW General Information On Mobile Phone System
- with CODE (523) MB Audio 20 radio
- with CODE (510) Audio 20 with CD changer

Component Identification:

Function requirements
^ Status "circuit 30 ON" or "circuit 15R ON"
^ Enabled Subscriber Identification Module (SIM) card inserted in mobile phone
^ Mobile phone and "master control unit" switched on
^ Correct Personal Identification Number (PIN) entered, if set on the mobile phone
^ Mobile phone system operating error-free
^ One mobile telephone network is available in sufficient strength and quality
^ Compatible mobile phone inserted into the mobile phone cradle (A34/15) (comfort telephony) or Bluetooth mobile phone in the vehicle and registered with the "master control unit" (basic telephony)

General
The mobile telephone network on vehicles with code (389) Mobile phone preinstallation with universal interface, USA/Canada (model 204.0) is a digital, cellular wireless network according to the Code Division Multiple Access (CDMA) standard. In vehicles with code (386) Mobile phone, the mobile telephone network is a digital, cellular wireless network based on the Global System Mobile (GSM) standard.
The CDMA or GSM standards represent the normalization of the mobile phone system. The purpose is to offer compatible cellular phone services.
This system transfers dialing information, voice as well as data, digitally. Moreover, additional services are offered, such as:
^ fee display
^ conference calls, calls waiting
^ identification of calling partner
^ call relaying
^ Fax, with code (386) Mobile phone

Radio transmission in the mobile telephone network takes place between the mobile phone and the Base Transceiver Station (BTS). The transmission frequencies vary depending on the frequency band, as shown in the following example:
^ Uplink (1850 up to 1910 MHz), with code (389) Mobile phone preinstallation with universal interface, USA/Canada (model 204.0)
^ Downlink (1930 up to 1990 MHz), with code (389) Mobile phone preinstallation with universal interface, USA/Canada (model 204.0)
^ 900 up to 1900 MHz, with code (386) Mobile phone

As of the Base Transceiver Station (BTS), all signals are forwarded by wire to the Base Station Controller (BSC). In a cellular mobile telephone network, the Base Transceiver Stations (BTS) are arranged in such a way that the honeycomb-shaped radio cells form a mobile telephone network to supply the mobile phone subscribers nationwide.

On the one hand, radio cells in densely populated areas must serve a large number of subscribers, on the other hand in rural areas they must be capable of covering large radio areas. Depending on the requirements, these radio telephone cells have radii of 100 m to 40 km. A feature of cellular mobile radio networks is the automatic handover from one radio cell to the next, without the cellular phone subscriber noticing anything. If, during communication, the range of a Base Transceiver Station (BTS) is left and the subscriber moves into the transmission range of the next Base Transceiver Station (BTS), the communication can be continued without any interruption, although the transmitter of the next Base Transceiver Station (BTS) is transmitting on another frequency.
This handover procedure is accomplished within 5 to 10 ms. Transmission problems can occur if the mobile phone subscriber is located in valleys and low spots (radio shadows) or in areas with a small number of base transceiver stations. However, these transmission problems can usually be eliminated by moving to a different location.

In vehicles with code (386) Mobile phone, it is possible to make phone calls when abroad using the mobile phone and the SIM card. This requires the particular country to have the GSM standard, a corresponding contract (roaming contract) between the country and the network provider and the mobile phone to be dual band or tri-band, depending on the different frequencies.
A radio cell is formed by the transmitting and receiving range of a Base Transceiver Station (BTS). The Base Transceiver Station (BTS) sets up the connection to the mobile phones, monitors the radio transmission and transmits the data by wire to the Base Station Controller (BSC).
With the GSM standard, with code (386) Mobile phone, 124 or 372 channels are available for each Base Transceiver Station (BTS). The Base Station Controller (BSC) is the controller unit for the Base Transceiver Station (BTS).

The Base Station Controller (BSC) is connected between the Base Transceiver Station (BTS) and the Mobile Service Switching Center (MSC). Here, the desired data for voice and data communication is transferred as well as control and checking information. In addition to this, the Base Station Controller (BSC) is the central control point for automatic handover from one radio cell to another.
The Mobile Service Switching Centers (MSC) are networked and form the switching system in mobile telephone networks with the CDMA standard, with code (389) Mobile phone preinstallation with universal interface, USA/Canada (model 204.0), or with the GSM standard, with code (386) Mobile phone. Here, the various databases and lists of visitors and visitor data are stored.

Databases and directories in the Mobile Service Switching Centers (MSC)
Home Location Register (HLR)
This is where subscriber master data are stored, such as name, address, telephone number, service features, caller and call destination numbers, information about time, duration of and charges for the phone call, and information about the radio cells in which a connection has been established and ended again.

Equipment Identification Register (EIR)
A device-specific, electronic identification number for mobile phones is registered here, the so-called International Mobile Equipment Identity (IMEI) number. This IMEI number is sent by the mobile phone during registration. If the mobile phone is blocked or stolen, access to the mobile phone network can be refused.

Visitor Location Register (VLR)
This is where the necessary data of a visiting mobile radio subscriber are temporarily stored.

Authentication Center (AC)
This is where the access authorization of the cellular phone subscribers is checked, and the relevant connection is switched.

The overall public mobile telephone network is designated as a Public Switched Telephone Network (PSTN).