Alcatel N.v.

Klaus Geywitz

Artur Veloso

Joachim Endler

Hans-Joachim Adolphi

Gerd Siegmund

The essential functions and characteristics of a telecommunications system with cordless terminals are established by the known DECT standard. On the one hand, the invention has the task of reducing the cost of ADPCM/PCM transcoders in DECT or DECT-like systems, and on the other to improve the handover characteristics, by making an interruption-free channel changeover, even during a change of cell bundles. To that effect, all DECT interface circuits (9, 10) are jointly controlled by a central processing unit (MOB CPU) assigned only to these DECT interface circuits (9, 10). The otherwise usual ADPCM/PCM transcoders have been omitted in the DECT interface circuits (9, 10), and are now assigned to the central processing unit (MOB CPU), while their number can be reduced in comparison to known solutions. The central processing unit (MOB CPU) also takes over the switching functions for the channels offered by the DECT interface circuits (9, 10). Since the channels from different DECT interface circuits (9, 10) are in frame-synchronous form, the central processing unit (MOB CPU) can carry out an interruption-free channel change during the cell bundle change of a cordless terminal.

Method and circuit arrangement for the access of cordless terminals to a

To also offer the possibility of mobile communication to branch exchange. The task of the invention is to present an interface arrangement between a private branch exchange and one or more base stations, at low cost for large numbers of existing base stations. To that effect, a microprocessor-controlled interface that maintains the DECT-Standard is offered, which shifts the majority of the functions from the one or more base stations to the branch exchange. A particularly cost-effective solution is obtained by making multiple use of component groups and dynamic channel assignment.

Interface arrangement for connecting base stations to a private branch

The problem of pulse frame synchronization occurs for example in a telecommunications system with cordless terminals operating according to the DECT standard. To establish a radio connection between base station and a cordless terminal, the base station scans its radio cell in sequence with the available ten high-frequency carriers in the DECT frame rhythm. In a multiple cell environment, the synchronization of all base stations belonging to a cordless telecommunications installation is necessary, to enable all base stations to scan the same frequency at the same time. This is achieved by blanking the DECT multi-frame synchronization pulses. The pulse gap is evaluated by error detection circuits which are present anyway, and used for the PSCN Primary receiver Scan Number-synchronization.

Frame Synchronization method

To prevent competitive situations when accessing a bus, it is known to use control circuits and to coordinate the access of the information sources to the bus by means of organization lines between the information sources and the information sinks. According to the invention, the access entitlement is switched from one information source to another by the desire to access, which is triggered by the information offer via a control line (TSDIS) connected to the information source (MAC-ASIC 1, MAC-ASIC 2, MAC-ASIC 3, MAC-ASIC n). The method can be used in a telecommunications installation operating according to the DECT standard or the CT 2 or CT 3 standard, if, when the subscriber changes location, the original radio connection is changed from a first base station (BS 1) to a second base station (BS 2), which has a better transmission path available.

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Gerlingen, Germany

Klaus Geywitz