Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-04-24
2002-04-30
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
48, C370S330000, C370S335000, C370S336000, C370S441000, C370S442000
Reexamination Certificate
active
06381461
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 radio communications system for transmitting data in a GSM mobile radio network, in particular between base stations and mobile stations, over a TD/CDMA radio interface.
The mobile radio network has at least one base station controller (BSC) and a first base station (BS) assigned to a radio cell. At least one first frequency channel is made available between the first base station (BS) and the mobile stations (MS) in order to transmit data and to transmit signaling information with a TDMA transmission method according to the GSM standard. The first base station (BS) additionally makes available a second broadband frequency channel with a TD/CDMA transmission method, according to a standard of the third generation of mobile radios, and a connection (V
1
) is set up in the first or second frequency channel. A first base station (BS) of the system contains at least one transmitter/receiver device for a second broadband frequency channel with a TD/CDMA transmission method, and the base station controller is embodied in such a way that a connection setup for a connection is controlled in the first or second frequency channel. Such a method and radio communications system are described by Jurgen Mayer et al., in “Protocol and Signaling Aspects of Joint Detection CDMA,” Proceedings of 8
th
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications-PIMRC '97, Vol. 3, Sep. 1, 1997, pages 867-71, Helsinki, Finland.
U.S. Pat. No. 5,600,707 (European published patent application EP 0 700 225) describes a radio system which has a base station with a TDMA transmission unit and a wireless ISDN transmission unit. A TDMA channel with a low data rate is used to set up a wireless ISDN connection provided with a high data rate.
U.S. Pat. No. 5,793,757 (International PCT publication Wo 97/30526) describes a mobile radio system with so-called dual mode base stations which support both timeslots with FDMA/TDMA channels and timeslots with CDMA channels.
In mobile radio networks, messages (for example voice, image information or other data), are transmitted using electromagnetic waves over a radio interface between a transmitting radio station and a receiving radio station (base station or mobile station). The electromagnetic waves are irradiated here with carrier frequencies which lie in the frequency band provided for the respective system. In the case of the GSM (Global System for Mobile Communication), the carrier frequencies lie in the region of 900, 1800 or 1900 MHz. For future mobile radio networks using TDMA or TD/CDMA methods for transmitting over the radio interface, for example the UMTS (Universal Mobile Telecommunications System) or other 3
rd
generation systems, frequencies in the frequency band of approximately 2000 MHz are provided.
German published patent application DE 195 49 148 discloses a radio communications system which utilizes CDMA subscriber separation (CDMA Code Division Multiple Access), the radio interface additionally having time-division multiplex subscriber separation (TDMA Time Division Multiple Access). Consequently, a TD/CDMA transmission method is used for the radio interface. At the receive end, a JD (Joint Detection) method is used to perform improved detection of the transmitted data based on the knowledge of spread codes of a plurality of subscribers. Here, it is known that at least two data channels can be assigned to a connection over the radio interface, it being possible to distinguish each data channel by means of an individual spread code. The radio communications system which is used in this context is a candidate for a system of the 3
rd
generation of mobile radios.
The article by P. Vary, “Implementation Aspects of the Pan-European digital mobile radio system” IEEE
1989
, pp. 4-17 to 4-22, discloses the structure of a GSM radio station with RF component, filters, channel estimators, modulators/demodulators, channel encoders/channel decoders. The GSM standard uses a combination of FDMA (Frequency Division Multiple Access) and TDMA for the radio interface and has met with acceptance throughout the world. This standard is used to provide services to over 20 million subscribers in Europe alone. There has already been extensive investment in the infrastructure and in mobile stations.
The transition from the 2
nd
generation of mobile radios (GSM) to the 3
rd
generation of mobile radios will again require considerable investment on the part of the network operators if network elements such as mobile switching center, mobile station controller or base stations have to be replaced or installed additionally. Significant development costs will also be incurred by the manufacturers of the infrastructure and mobile stations.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide methods and radio communications systems for transmitting data in a mobile radio network, which overcome the disadvantages of the heretofore-known devices and methods of this general type and which make it possible to migrate from an existing GSM mobile radio network favorably in terms of cost and effort.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of transmitting data in a mobile radio network having a first base station assigned to a radio cell, which comprises the following steps:
making available, with a first base station assigned to a radio cell, a first frequency channel for data transmission and an organization channel for transmitting signaling information with a transmission method according to a first mobile radio standard;
additionally making available, with the first base station, a second frequency channel with a transmission method according to a second mobile radio standard; and
signaling via the organization channel of the first mobile radio standard the standards supported in the radio cell.
In accordance with an additional feature of the invention, a connection is set up in the first or in the second frequency channel; and the connection is handed over to the respectively other frequency channel without selecting a second base station.
In accordance with another feature of the invention, the first mobile radio standard is a GSM standard and the second mobile radio standard is a third generation mobile radio standard.
The system is preferably implemented in the popular GSM mobile radio network having at least one base station controller and one first base station. At least one first frequency channel is made available between the first base station and mobile stations in order to transmit data and to transmit signaling information. In a specific embodiment, the first base station additionally makes available a second broadband frequency channel with a TD/CDMA transmission method. After a connection has been set up in the first or second frequency channel, a handover of the connection to the respective other frequency channel is carried out by the base station controller without a second base station being selected.
This means that, a new transmission method is provided on the basis of an already existing base station system by retrofitting a base station which is already installed in the GSM network, this fact applying equally to the carrier frequencies in the 900, 1800 and 1900 MHz ranges. Thus, no additional expenditure or effort is needed to provide a new base station system. By incrementally retrofitting the base stations, the coverage is improved in a way which permits the additional radio capacity to be provided where there is an adequate level of demand for it. This thus reduces the investment risks for network operators.
Without neglecting the provision of services to GSM mobile stations, it is possible to ensure, on a selective basis, that coverage is provided to mobile stations which use the radio interface according to a TD/CDMA transmission method. For mixed mode mobile stations whic
Besson Marcus
Kammerlander Karl
Neyen Hans Von Der
Greenberg Laurence A.
Lerner Herbert L.
Perez-Gutierrez Rafael
Siemens Aktiengesellschaft
Stemer Werner H.
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