CA2215788A1

CA2215788A1 - Fixed station of mobile radio system

Info

Publication number: CA2215788A1
Application number: CA002215788A
Authority: CA
Inventors: Klaus-Dieter Pillekamp
Original assignee: Individual
Current assignee: Siemens AG
Priority date: 1995-03-20
Filing date: 1996-03-04
Publication date: 1996-09-26
Also published as: WO1996029836A1; EP0815699A1; AU4874796A; JPH10505213A

Abstract

The directional radiation characteristic of the aerial system (1) of the fixed station of a mobile radio-telephone system operating with a digital time-multiplex (TDMA) process is matched to the current location of the mobile station which is transmitting or being received at that time. The invention can advantageously be used in radio-telephones on the DECT standard.

Description

. CA 0221~788 1997-09-18 Description Fixed station of a mobile radio system The invention relates to a fixed station accord-ing to the precharacterizing clause of patent claim 1.
The range of a mobile radio system, for example a cordless telephone, which comprises a fixed station and one or more mobile stations, is essentially governed by its transmitted power and its receiver sensitivity. In this case, the transmitted power is emitted uniformly in all directions, that is to say at least approximately omnidirectionally in order, on the one hand, to be useable universally in any environment and, on the other hand, to achieve the same range in every direction. If however, a single point in time is considered, then, from the point of view of the fixed station, that is to say in the example the base station of a cordless telephone, only a fraction of the transmitted energy is emitted in the direction of the mobile station which is in use at this instant, that is to say, in the example, the mobile section of the cordless telephone. By far the majority of the transmitted energy is, in contrast, not used and may even interfere with other devices. The range o~ the radiation is limited by the transmitted power, the path attenuation and the received power. The path attenuation is a constant factor in this case, and cannot be reduced.
The transmitted power cannot be increased indefinitely.
In principle, the received power, and thus the range, can be increased by directional transmission, that is to say by the use of a focused directional antenna which emits the available energy concentrated in a specific direc-tion. The use of directional antennas in radio systems for this purpose is generally known.
The object of the invention is, by refining the fixed station, to provide an advantageous capability for improving the CA 0221~788 1997-09-18 transmission behavior between the fixed station and the mobile stations of a mobile radio system, in particular of a cordless telephone.
This object is achieved in the case of a fixed station according to the precharacterizing clause of patent claim 1 by the features specified in the charac-terizing part of this patent claim.
Expedient developments and refinements of the fixed station specified in patent claim 1 are specified in claims 2 to 6.
The following text uses a block diagram, which is shown in a figure, to describe a fixed station according to the invention.
This fixed station of a mobile radio system may be, for example, the base station of a cordless telephone operating to the DECT Standard.
The illustrated fixed station has an antenna device 1 which is connected via an antenna diplexer 2 either to a transmitter 3 or a receiver 4. The antenna device 1 is formed as an antenna array which has a plurality of individual radiating elements and whose radiation characteristic can be shaped to produce a directional beam characteristic. Individual radiating elements in this antenna array can be connected and disconnected and/or specific phase relationships can be selected between these individual radiating elements to allow a suitable directional beam characteristic to be produced, which can then be aimed in different direc-tions.
The fixed station illustrated in the figure includes a control mechanism 5 for adjusting the radia-tion characteristic of the antenna device 1. The radia-tion characteristic, which has the form of a focused directional beam, of this -r CA 0221~788 1997-09-18 antenna device 1 is always matched to the instantaneous location o~ that mobile station which is being trans-mitted to at the relevant time by connection of the transmitter 3, or is being received from at the relevant time by connection of the receiver 4. The drive data for adjusting the respective radiation characteristic of the antenna device 1 is derived, using an algorithm, from the received field strength measured in the control mechanism in a measuring device 6 and/or directly from the received digital data, using a device 7 in which bit/burs~ faults are identified. The actual computational evaluation in order to define the drive data is carried out in a central section 8 o~ the control mechanism 5, which executes the algorithm. A memory device 9 in the control mechanism 5 is used to buffer-store the asso-ciated radiation characteristics ~or 1 to n mobile stations, in the form of drive data for the antenna device 1.
The memory device 9 in the control mechanism 1 can advantageously be used to store two radiation charac-teristics, whose difference corresponds only to a minor change in the characteristic. This makes it possible to avoid interruptions in reception from fading holes in the case of a non-moving mobile station.

Claims

Patent Claims - 4 -

1. A fixed station of a mobile radio system which operates on the radio path using a digital time division multiple access (TDMA) method, in particular a cordless telephone to the DECT Standard comprising a base station and one or more mobile sections, having an antenna device whose radiation characteristic is variable, characterized in that a control mechanism is provided for adjusting the radiation characteristic, so that the latter is always matched, in the form of a switchable directional antenna characteristic, to the instantaneous location of that mobile station which is being transmitted to at the relevant time or is being received from at the relevant time.

2. The fixed station as claimed in claim 1, characterized in that, in the control mechanism (5), the drive data for setting the respective radiation characteristic of the antenna device (1) on the basis of an algorithm is derived from the received field strength and/or directly from the received digital data.

3. The fixed station as claimed in claims 1 and 2, characterized in that the control mechanism (5) has a memory apparatus (9) in which the associated radiation characteristics of the antenna device (1) are buffer-stored, in the form of drive data for the antenna device, for 1 to n mobile stations which are potentially available in a mobile radio system.

4. The fixed station as claimed in claim 3, characterized in that each mobile station has two antenna device (1) radiation characteristics stored for it, the difference between which corresponds to only a minor change in the characteristic, such that reception interruptions caused by fading holes in the case of a non-moving mobile station are prevented by causing a change between these two antenna characteristics.

5. The fixed station as claimed in one of the preceding claims, characterized in that the antenna device (1) is designed as an antenna array having a plurality of individual radiating elements which can be switched on or off and/or can be fed with different phases in order to achieve different antenna device radiation characteristics.

6. The fixed station as claimed in one of the preceding claims, characterized in that the changeover between the different antenna device (1) radiation characteristics takes place from burst to burst.