Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
2000-05-08
2002-04-23
Chin, Wellington (Department: 2664)
Multiplex communications
Communication over free space
Repeater
C370S249000, C370S334000, C370S342000, C375S149000, C375S213000
Reexamination Certificate
active
06377559
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a method, a receiver and a mobile station for transmitting data in a radio communication system, in particular in TD/CDMA mobile radio systems.
International Publication No. WO 97/05707 describes a method for transmitting data between radio stations in a radio communication system, in which first signaling information items are superimposed with second or further information items at a transmitting end to form an aggregate signal, the aggregate signal is transmitted in a frequency channel, whereby it is possible to distinguish the first signaling information items and the second information items with the aid of individual fine structures, and a received signal is evaluated at a receiving end. International Publication No. WO 97/05707 also describes a receiver for a radio station, including a radio-frequency device for demodulating received signals, wherein first signaling information items and second or further information items, which can be distinguished with the aid of individual fine structures, are superimposed in the received signals to form an aggregate signal, and a coupling device for connecting the radio-frequency device to a signal-processing device.
In radio communication systems, messages (for example voice, image information or other data) are transmitted with the aid of electromagnetic waves through an air interface between transmitting and receiving radio stations (base station or mobile station, respectively). The emission of electro-magnetic waves is performed in that case by using carrier frequencies which are situated in a frequency band provided for the respective system. In the case of the GSM (Global System for Mobile Communication), the carrier frequencies are situated in the region of 900, 1800 or 1900 MHz. Frequencies in the frequency band of approximately 2000 MHz are provided for future mobile radio networks, for example the UMTS (Universal Mobile Telecommunication System) or other systems of the third generation.
The currently existing mobile radio system GSM (Global System for Mobile Communications) is a mobile communication system having a TDMA (Time Division Multiple Access) component for subscriber separation. User information items of the subscriber connections are transmitted in time slots in accordance with a frame structure. The transmission is performed in blocks. Organization channels (BCCH broadcast control channel) which are also known from the GSM mobile radio system are likewise matched to the time frame of the frame structure, for transmitting signaling and organization information items to all mobile stations in the respective radio cell. Those organization information items include details of the location area, the radio cell, the channel structure and of options which are supported inside the cell. Further signaling information items are transmitted in the down direction.
With the aid of the organization channel, which is emitted at maximum power, a mobile station undertakes performance measurements which permit statements to be made on the radio cell suitable for a connection set-up or handover. That organization channel is transmitted in a dedicated time slot in the frequency range of the user information.
German Patent DE 197 13 667 C1 discloses a radio communication system with TDMA/CDMA subscriber separation (Code Division Multiple Access), in which the organization information items are emitted as first signaling information items, likewise together with further information items, for example with user information items, in one frequency range. On one hand, the disadvantage of that solution resides in the additional interference which the organization channel entails for the user data channels. On the other hand, the user information items or further signaling information items also disturb the transmission of the first signaling information items. The range of the organization channel is also reduced.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method, a receiver and a mobile station for transmitting data in a radio communication system, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and which improve detection of further information items.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for transmitting data between radio stations in a radio communication system, which comprises superimposing first signaling information items with second information items at a transmitting end to form an aggregate signal; transmitting the aggregate signal in a frequency channel, for distinguishing the first signaling information items and the second information items with the aid of individual fine structures; evaluating a received signal at a receiving end; initially reducing an influence of the first signaling information items on the second information items by a compensation calculation carried out with reference to the received signal; and subsequently detecting the second information items in the received signal already subjected to the compensation calculation.
With the objects of the invention in view, there is also provided a receiver for a radio station, comprising a radio-frequency device for demodulating received signals, the received signals having first signaling information items and second information items, to be distinguished with the aid of individual fine structures, superimposed therein to form an aggregate signal; a coupling device; a signal-processing device connected to the radio-frequency device by the coupling device, the signal-processing device including a device for reducing an influence of the first signaling information items on the second information items by a compensation calculation, and a detection device for the second information items; and the influence reducing device carrying out the compensation calculation before the detection device begins to detect the second information items.
With the objects of the invention in view, there is additionally provided a mobile station, comprising the receiver.
The interference affecting the further information items to be detected is reduced by the measure of compensating for the influence of the first signaling information items before detecting the further information items. The first signaling information items can be emitted without losses in quality at a higher transmission power, for example at the transmission power of the further information items, resulting in an increase in range.
It is thereby also possible for more remote radio stations, for example mobile stations in neighboring radio cells, to use the first signaling information items for performance measurement and cell selection. According to the invention, the transmission of the further information items need not be performed coherently with the first signaling information items. The transmission is admittedly performed in a common frequency band, that is to say with superimposition in terms of power, but there is no correlation between the signal components in the transmitted signal.
In accordance with another mode of the invention, the method operates particularly advantageously if the first signaling information items are emitted at the transmitting end with a lower level of directional selectivity than the further information items. In the case of a different directional selectivity, a channel estimation is carried out at the receiving end with the aid of training sequences embedded in the further information items.
The lower level of directional selectivity can be compensated by a higher process gain. The higher process gain can be implemented, for example, by the selection of a higher spread factor for the first signaling information items.
The greater spread factor for the first signaling information items is achieved according to an advantageous development by virtue of the fact that their symbols have a longer symbol duration than the symbols
Chin Wellington
Greenberg Laurence A.
Lerner Herbert L.
Phan M
Siemens Aktiengesellschaft
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