Arrangement for using a mobile terminal in a radio switching system with different transmission standards

The invention relates to an arrangement for operating a mobile terminal, for example, optionally via a cordless system in the fixed network to the DECT (Digital European Cordless Telecommunications) standard, or via a cellular mobile radio system according to the GSM (Global System for Mobile Communication) standard. Increasingly there is a need to be able to make calls from any location, both in a confined premises, which is powered by a cordless system, as well as in the car for many participants. Usually, a participant at the premises used to a cordless telephone, which operates according to the DECT standard, and in the car, a car phone, which operates according to the GSM standard. In order to avoid the use of two different telephone sets, it is known, a two systems handset, engl. to use dual-mode phone, send the both DECT and GSM signals and receive. See DE 43 44 702 A1. The radio contact with the DECT system is preferably because the voice quality is better than to technical reasons in GSM systems in DECT systems. While an implementation of the two systems handheld device is possible, however, a considerable effort is required to adjust the specifications of the different standards, such as speech coding, encryption, authentication and handover procedure of the mobile terminal to each other. To meet this requirement, it is known to associate each DECT control station a so-called. Interworking Unit. See radio show, Issue 3, 1996, page 24, Franzis Verlag GmbH, Feldkirchen.

With the invention, the object will be solved to provide a cost-effective arrangement in which a mobile terminal in cordless systems or in cellular mobile radio systems can be used, without having to make interventions in the network infrastructure.

This object is achieved with the arrangement described in the first claim.

The essence of the invention is that has an interface between the mobile terminal and a fixed module, access to the cordless system or the cellular mobile radio system, all the necessary data is transferred, which are necessary for a man-machine communication. In the case of a phone that is the language, the content of the display and the information on each confirmed key.

The operation of the invention is explained below using an exemplary embodiment. The accompanying drawing shows a figure with an interface arrangement between a GSM device and a DECT device.

In a first application case, the access of a cordless telephone according to the DECT standard is the DECT telephone, described briefly to the GSM network.

Given a fixed in-vehicle installed adapter for a GSM phone, for example, equipped with an infrared interface circuit. Likewise, the DECT phone is equipped with an infrared interface circuit, so that DECT phone can be both accessed as intended on the DECT network and via the infrared interface on the GSM network with. The GSM phone can then be omitted in this case.

In a second application, the GSM phone and a DECT base station, each with an infrared interface circuit is equipped. In this case, it is possible to access to a GSM phone to the DECT network.

According figure, the interface arrangement of an interface circuit 1 in a GSM adapter and an interface circuit 2 in a DECT telephone. There are shown in the figure, only the components that are essential for explaining the invention. With the interface circuits 1, 2 a-duplex connection via an infrared link 3 is established. Each interface circuit 1, 2 essentially consists of an infrared transceiver 1.1, 2.1, a digital signal processor 1.2, 2.2 and a codec 1.3, 2.3.

When a connection request of a subscriber with a DECT unit via the GSM network, the transmitter of the infrared transceiver 2.1 must first be activated. This is done either by pressing a button located in the DECT device or automatically by sequential polling the interface arrangement, so-called. Polling whether information for transmission is present. The triggered by the keyboard of the DECT telephone dialing information and commands are supplied from the digital signal processor 2.2 as processed data via a bidirectional data line 2.4, the infrared transceiver 2.1 and the infrared path 3 to the transceiver 1.1 of the GSM device from which a bidirectional data line 1.4 leads to the digital signal processor 1.2 of the GSM unit, with the dialing information and instructions on the DECT device to be further processed, as the dialing information and instructions would come from a GSM phone. Once connected, the language or, for example, in facsimile transmission will be the data from the DECT device via the Codec 2.3 in PCM or ADPCM format and a bidirectional line 2.5 to the transceiver 2.1 and from there via the infrared path 3 to the transceiver 1.1 bidirectional via a line 1.5 transferred to the codec 1.3 of the GSM unit.

The simple and thus inexpensive interface arrangement, it is possible for the participants, with only one mobile terminal alternatively to use the GSM network or the DECT network depending on the location and to use the advantages of the different tariff structures. The availability of the subscriber is ensured by utilizing known network performance characteristics such Rufweiterschalten no reply of the participant so that the participant is always on the same number. The infrared interface is found to be particularly favorable, since no interference with the appropriate radio part occur and component costs for infrared interfaces are low. but it is also possible to already existing interfaces to utilize, for example, for the data transmission via GSM equipment, for the purpose described. In this case a cable connection between the GSM-unit and DECT device would be required. The interface arrangement according to the invention is far less expensive than the cost of dual-mode devices known. The simple circuit structure, it is possible to equip designed equipment with the interface arrangement or to expand already in use devices with the interface arrangement.