Telecommunications – Radiotelephone system – Including public cordless extension system
Reexamination Certificate
1999-11-01
2001-11-06
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Including public cordless extension system
C455S435100, C455S411000, C455S450000
Reexamination Certificate
active
06314299
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the telecommunications field. More specifically, the invention relates to a method and a home base station for setting up connections for a mobile station in a mobile radio network, whereby the setting up of the connection can be initiated by the home base station or by the mobile station.
Radio communications systems are formed, for example, by mobile radio systems, wireless telephony systems or by radio stations for wireless subscriber connection (RITL radio in the local loop). Mobile radio networks allow communications connections to be set up to mobile subscribers, wireless telephony systems connect specific mobile terminals in the home area, while radio stations for wireless subscriber connection set up communications connections to stationary subscribers. A radio station on the network side is called a base station.
Communications connections are set up and maintained by signaling and wanted information being transmitted via a radio interface. If a plurality of subscribers using the same carrier frequency in the radio interface are separated by different time slots, this is a time-division multiplex system. The time-division multiplex method is referred to as the TDMA (time division multiple access) method. If subscriber signals for different connections are transmitted simultaneously but in different frequency bands, then this is a frequency-division multiplex system (FDMA=frequency division multiple access).
One known mobile radio system is, for example, the GSM (Global System for Mobile Communications) mobile radio network. In addition to time-division multiplex and frequency-division multiplex, other methods may also be used to separate the subscribers at the radio interface. Alternatively or additionally to the the methods for subscriber separation, specific codes may also be used for each communications connection.
A base station is a remote unit, which is normally connected on the network side by wires to other network components, and which is connected via the radio interface to the terminal or some other radio station.
International PCT publication WO 95/02927 discloses a method in which SIM cards (SIM=subscriber identification module) are used to store not only the subscriber number, telephone number and authentication code, but also settings of transmitting/receiving devices in a mobile station and in a home base station. The home base station is thereby connected to a wire-based communications network.
A wireless communications connection can be set up between the mobile station and the home base station by setting the frequency band and transmission power, without any major interference of the surrounding mobile radio network. The tuning to a specific frequency band and the synchronization are, however, related only to the stored settings. The flexibility and accuracy of the communications connection between a mobile station and a home base station is thus limited.
British patent application GB 2 285 556 A and international PCT publication WO 97/11567 disclose radio communications systems with base stations that can be connected to the fixed network for setting up connections to mobile stations. Dedicated synchronization methods are used for that purpose between the base stations and the mobile stations.
A further possibility for parallel use of home base stations and base stations in a mobile radio network is so-called dual-mode terminals, which are designed to set up connections to home base stations via a wireless connection in accordance with the DECT standard (DECT=digital enhanced cordless telephony) and, in addition, for setting up connections to base stations in the mobile radio network in accordance with the GSM Standard. Mutual interference between the various radio interfaces is low, since different frequency bands are used. However, the preparation of radio transmission and signal processing in accordance with both standards involves increased complexity in the mobile stations, leading to less economic solutions.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method of setting up connections and a home base station, which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which, with little financial cost, allows connections to be set up flexibly and reliably between a mobile station and a home base station.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of establishing a connection for a mobile station in a mobile radio network, wherein a plurality of base stations are provided in the mobile radio network, and at least one home base station for supplying small cells, and wherein the mobile stations transmit to the home base station in an uplink direction, and the home base station transmits to the mobile station in a downlink direction. The method comprises the following steps:
synchronizing a mobile station and a home base station based on an evaluation of an organization channel in the mobile radio network;
transmitting with the mobile station a message in the uplink direction to the home base station in a frequency band of the home base station, the message containing a mobile-station-specific first identifier;
receiving and evaluating the message by the home base station; and
if the first identifier matches a second identifier registered for the home base station, setting up the connection between the home base station and the mobile station.
The setting up of a connection can be initiated by the mobile station in a mobile radio network or by the home base station. Mobile-station-specific identifiers are introduced for this purpose, which define the assignment of a mobile station to a specific home base station. Transmission from the mobile station to the home base station, as conventional, is referred to as the uplink direction and the transmission from the home base station to the mobile station is referred to as the downlink direction. The home base station is intended for supplying small cells in addition to radio cells supplied by base stations in the mobile radio network.
According to the invention, when a connection is set up initiated by the mobile station, the mobile station is synchronized on the basis of an evaluation of an organization channel in the mobile radio network. The mobile station transmits in a frequency band of the home base station and to this home base station a message, which contains a mobile-station-specific first identifier and is received and evaluated by the home base station. If the first identifier matches a second identifier registered for the home base station, the connection is set up.
The synchronization of the mobile station and the identifier request result in the setting up of a connection being initiated with little complexity and adequate accuracy. The evaluation of requests to set up connections can be carried out by the home base station using methods known from the mobile radio network.
The use of the organization channel in the mobile radio network means that no dedicated channel is required in the home base station for this purpose. Furthermore, the production costs of the home base station are reduced, since the requirements for an internal time and frequency norm are less stringent.
In accordance with an added feature of the invention, the method further comprises providing with the mobile station a changeover between a first operating mode relevant to the home base station and a second operating mode relevant to the base stations in the mobile radio network. Since the charge structure of the mobile radio network and the further network—for example a fixed network—to which the home base station is connected may differ, it is thus possible for the subscriber to decide to use a specific network. The changeover can be carried out manually via keypad functions on the mobile station, or in accordance with a stored priority list if the version with th
Helms Jochen
Schreib Franz
Gesesse Tilahun
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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