GF82.70-P-0003Q Telephone (D Network) Function

GF82.70-P-0003Q Telephone (D Network) Function
- with CODE (853) MB standard telephone
- with CODE (854) MB portable cellular telephone

Component Identification:

Fixed installation and portable CTEL function
Depending upon the equipment a call can be set up using the:
^ Telephone handset (A34) (code 853)
^ Portable CTEL (A34/6) (code 854)
^ Radio (A2)
^ COMAND operating, display and control unit (A40/3)
^ Multifunction steering wheel
^ Voice control system (VCS) (code 813)

This is contingent on the system being operational following a successful PIN entry and log-in. If the telephone is not required, then it switches to standby mode.

The switching On/Off characteristic of the telephone is controlled by the operating unit and the system-dependent software in the control unit for the digital data bus (D2B). The telephone interface (A34/4) or the telephone transmitter/receiver, D2B (A35/13) is, as is the operating unit, integrated into the vehicle's optical data bus (D2B) and represents the physical connection to the data bus and the telephone antenna (A2/22). The telephone antenna (A2/22) is supplied with voltage by the telephone interface (A34/4) or the telephone transmitter/receiver, D2B (A35/13) and it transmits and/ or receives the radio signals.

D-network, general
The D-net (digital network) is set up in accordance with the GSM standard (Global System for Mobile Communication). This allows telephone calls to be placed to countries whose networks are also laid out according to the GSM standards and whose users have a GSM standard telephone. Contracts must still exist between these countries, which govern telephone traffic and guarantee accessibility. The countries that have been accepted into these contracts can be viewed in lists available at the individual telephone providers. The D-net itself has a honeycomb-type structure for the greatest possible area coverage for mobile subscribers, whereby some areas may not be covered. The individual cells have a radius of 100 m to 35 km. However, this can be even smaller depending on the maximum telephone traffic (e.g. in large cities) or depending on the surface characteristics (mountains, buildings).

Transmission problems can occur when the user is located in low spots (radio shadows) or in areas with few transceiver stations. Reception or transmission difficulties can however usually be rectified by changing the location. There are up to 16 carrier frequencies per cell, which themselves allow up to 7 calls per carrier frequency. Transmission of the voice and data signals is accomplished digitally in the range of 900 to 1800 MHz. The system ensures maximum security against monitoring by third parties and provides additional services such as:
^ Fee display
^ conference calls, waiting function
^ identification of calling party
^ call relaying
^ traffic information service
^ WAP and the Internet

Moreover, because of its ISDN compatibility, the D-net offers access possibilities to text and data stations (corresponding adapters required).

The D-network requires the following operating units:
^ Transmitting and receiving terminal (BTS=Base Transceiver Station, per cell)
^ Concentrator (BSC=Base Station Controller, interconnected cells)
^ MSC=Mobile Service Switching Center, interconnected cells)

Each transceiver station (BTS) is connected to the associated mobile service switching center (MSC) via a concentrator (BSC). The connection between the base transceiver station (BTS) and concentrator (BSC) is accomplished via radio signal (pulsed signal) and the connection from the concentrator (BSC) to the mobile service switching center (MSC) via lines (permanently-wired 4-conductor lines).
The following units are included in the mobile switching center (MSC):
^ HLR Home Location Register
^ VLR Visitor Location Register
^ AC Authentication Center
^ EIR Equipment Identification Register

Moreover, the mobile switching center (MSC) forms the interface to the switching center of the public telephone network (PSTN) Each subscriber in the D-net is listed in his/her mobile service switching center (MSC) or the home location register (HLR) stored for him/ her. The network access authorization of the mobile subscriber is also checked in the authentication center (AC) located there. Moreover, defective or stolen units are identified in the equipment identification register (EIR). All subscribers from other home location registers (HLR) or other networks are identified in the visitor location register (VLR)
It is possible to select between two versions:
^ MB standard code (853)
^ MB portable CTEL code (854)