WO1998042090A1

WO1998042090A1 - Method for transmitting information to a mobile receiver such as a pager, using radio transmitters

Info

Publication number: WO1998042090A1
Application number: PCT/DE1998/000735
Authority: WO
Inventors: Manfred Tasto
Original assignee: Siemens Aktiengesellschaft
Priority date: 1997-03-14
Filing date: 1998-03-12
Publication date: 1998-09-24
Also published as: EP0966806A1; EP0966806B1; JP2001515672A; DE59812332D1

Abstract

The invention relates to a method, a radio transmitter (TRA) and a mobile receiver for transmitting information, for example to a pager (PAG) or to a mobile part of a mobile radiotelephone or satellite telecommunications system, whereby specific information (INF) for the receiver is sent in addition to a radio signal (AUD) by a radio transmitter (TRA). The transmitter is digitally modulated and the data rate is continuously adjusted by means of data compression and a fluctuating bit rate to suit the radio signal to be transmitted. At intervals when less than the maximum possible bit rate is sent, the free channel capacity is filled with the specific information. The transmitter contains a coder (COD) for compressing and digitally coding an analog input signal (AES) and a modulator (MOD), to which the coded signal the modulator is fed, as well as a high frequency stage (HFS) operating in the short, medium or long wave range. The radio signal is sent with a fluctuating bit rate.

Description

Description ^~~

Method for transmitting information to a mobile receiver, such as a pager, using radio transmitters.

The invention relates to a method for transmitting information to a mobile receiver, e.g. to a pager or to a mobile part of a mobile radio or satellite telecommunications system.

The invention also relates to a radio transmitter for broadcasting a radio signal, with an encoder for compressing and digitally coding an analog input signal, with a modulator to which the coded signal is fed, and with a high-frequency stage operating in the short-medium or long-wave range , wherein the broadcast signal comes to a shutdown with fluctuating bit rate.

Finally, the invention also relates to a mobile receiver which is set up to receive digitally coded information received as well as to store and / or display the decoded information.

Usual pagers and mobile phones work in a frequency range from 100 MHz to a few GHz and cannot be used everywhere due to physical conditions alone, since the radio waves are shielded by obstacles such as walls, soil, metal walls etc.

This is usually the case in subways, cellars, underground garages, inside large buildings, etc. Even occasionally used "microstations" in inaccessible areas do not change the basic problem. That being said, this increases network setup and maintenance costs. A handset may also be unavailable for other reasons, for example if it is in a region without a network operator's network infrastructure, because it must be switched off for security reasons, such as in airplanes or intensive care units, or because of other physical effects, such as the Doppler effect not allow a connection in otherwise moving vehicles, fading, etc.

The situation described is alleviated by the already common call memory ("mailbox") in the network, since the user of the handset can query this call memory as soon as a connection to a base station of the network is possible again. However, the user cannot find out beforehand that, for example, he should urgently call back another subscriber.

The above applies even more to satellite telephones, since they are set up to maintain connections with other telephone subscribers via a communications satellite, whereby a visual connection in the sense of a "line-of-sight" connection between the handset, i.e. the satellite phone, and the satellite must exist. Because of the high frequencies used, which are between 1.5 and 2 GHz or higher, and the extremely low reception power, walls, trees, foliage, etc. are already insurmountable obstacles, so that the user can only make calls outdoors or at the window if this and thus its antenna is in the right direction.

If the user of the handset wants to establish a connection, he can bring the satellite telephone or its antenna into the correct "line-of-sight" position. However, the user of the handset cannot ensure that the antenna of his satellite telephone is in a "line-of-sight" position during a journey in vehicles of any kind is therefore not available to other subscribers and cannot receive your call.

It is an object of the invention to find a solution to the problems mentioned above.

To achieve this object, the invention is based on a method of the type mentioned in the introduction, in which, according to the invention, specific information to be transmitted to the receiver is emitted by at least one radio transmitter in addition to a radio signal, the transmitter being modulated using a digital method, in which the data rate is continuously adapted to the broadcast signal to be transmitted by data compression and a fluctuating bit rate, and in time periods in which the maximum possible bit rate is not transmitted, the free channel capacity given by the difference between the maximum bit rate and the bit rate claimed by the broadcast signal with the specific Information is replenished.

The invention offers the advantage that existing devices, namely the radio transmitters for short, medium and long waves, can be used for the transmission of information, in particular a short message in the sense of known pager messages. The accessibility of the mobile receiver is considerably improved, whereby the frequency range of the broadcasting band used can be aware of the Erforder ^¬ Nissen selected accordingly.

So with long waves, because of their great depth of penetration in

Soil, concrete, water, etc., even in unfavorable situations, such as in subways, underground garages and long tunnels, the transmission of information is possible, so that, for example, a GSM cell phone that has an additional receiver can access the short information practically anywhere . Long waves also have an extremely high range that is practically independent of the time of day. In the medium wave range, in turn, a great number of transmitters are still working or transmitters are reactivated, so that there is good area coverage.

Although short waves are subject to even more fluctuations in field strength depending on the time of day than medium waves, there is also a well-developed transmitter network here and in some cases the long ranges possible with low transmission energy can be very important.

The invention therefore does not require the installation of new transmitters, which would in any case be difficult given the scarce frequencies in the KW, MW and LW range. Rather, only existing transmitters need to be modernized without new locations or antennas being required.

In advantageous variants for achieving the free channel capacity, the broadcast signals are scaled dynamically or a Huffman variable length code is used to encrypt the broadcast signals.

In a recommended variant that does not impair radio operation at all, it is provided that the transmission of radio signals always takes place with a higher priority than the transmission of specific information.

Furthermore, it is advantageous if the specific information is classified into signals with different priorities with regard to the transmission or if the priority is chosen the higher the lower the permissible delay with respect to real-time transmission is given, since this means, for example, signaling for mobile - Or satellite telephones can be transmitted with less delay than pager signals, in which delays in the minute range are easily accepted. In a further variant, it is provided that the bit rate of the coded radio signals is temporarily reduced as of a bit congestion of the specific information to be sent that exceeds a predetermined dimension due to insufficient channel capacity. In this way, if, for example, more complex broadcast signals have led to such a bit jam, the transmission of the specific information can be forced, the bit rate reduction required for the broadcast signal usually being barely perceived.

It is expedient if the specific information is encoded in digital information blocks of variable length, since this results in a better possibility of using free channel capacity. It is advantageous if the classification is written in signals of different priority in the header of the information blocks.

For the reasons already mentioned, it is advantageous if the radio transmitter or transmitters are operated in the range from 150 kHz to 30 MHz, the simultaneous broadcasting on different frequencies, e.g. can bring special advantages in the LW and MW area.

The object is also achieved with a radio transmitter of the type cited at the beginning, in which, according to the invention, the encoder is additionally supplied with specific information and the encoder is set up in periods in which the maximum possible bit rate is not transmitted, which is transmitted by the Fill the difference between the maximum bit rate and the free channel capacity given by the broadcast signal with the specific information. The advantages that can be achieved with this have already been mentioned in connection with the method according to the invention.

An expedient variant provides that the encoder is set up to forward broadcast signals with higher priority for transmission than specific information. Furthermore, it is recommended if signals of the specific information of different priority are fed to the encoder.

It can also be advantageously provided that the encoder is set up to read the priority of the signals from headers of signal blocks.

A favorable variant is characterized in that the encoder is set up to temporarily lower the bit rate of the encoded broadcast signal from a predeterminable bit jam of the specific information to be sent.

To achieve the object, a mobile receiver of the type specified above can be used, which is used in a method with the features mentioned and for receiving a transmitter with the features mentioned above for this purpose.

The mobile receiver can be contained in a pager or it can be contained as an additional receiver in a mobile radio device or in a satellite telephone.

To improve accessibility, it can be provided that it is set up for the continuous reception of radio stations in substantially different bands, such as shortwave and longwave.

Finally, an embodiment can also be recommended in which it is used for receiving and evaluating both the

Broadcast signals and specific information is set up so that a radio with pager function is available.

The invention together with further advantages is explained in more detail below on the basis of exemplary embodiments, some of which are illustrated in the drawing. In this show 1 shows the application of the invention using a scenario of a network with radio transmitters, satellite telephones, mobile radio cells and pagers in a schematic representation, FIG. 2 shows a basic block diagram of a radio transmitter according to the invention,

3 shows in a diagram the fluctuating bit rates and their use for the invention,

4 shows a block diagram of a receiver which is additionally arranged in a mobile telephone, and

5 shows the basic structure of a message block for the specific message.

Fig. 1 shows two base stations' FIP1, FIP2 of a mobile radio network, e.g. a GSM network, the cells of which are shown symbolically as dash-dotted circles. There is a mobile part POP in one cell. A base station controller BSC is assigned to the base stations FIP1, FIP2 and others and this is assigned a mobile radio switching unit MSC which does not have access to the so-called Visitor Location Register VLR or the Home Location Register HLR and others units shown, such as an authentication register. The base station controller BSC has a suitable interface with a fixed network, e.g. an ISDN network.

1 also shows two radio transmitters TRA, TRA 'with antennas SAN, SAN'. The broadcasting transmitters are supplied with a broadcasting signal AUD, namely an audio signal, for example from a broadcasting studio RFS, which is indicated for the transmitter TRA with a direct line, whereas the transmitter TRA 'is connected to the studio RFS via a network NET . The transmitter TRA, TRA 'are in principle available to the network NET in ^"connection, which is symbolically indicated here with an open block. It can involve the mobile network, a fixed network or to a higher-level network to act. Possible wä- re however, a direct connection of a transmitter TRA, TRA 'to a base station FIP1, FIP2.

1 also shows a news satellite SAT, a satellite telephone SPP and a ground station BST, which is assigned to the news satellite SAT and is connected to at least the news network NET. The radio transmitter TRA receives information from a satellite receiver SRE, which the satellite receiver receives from the satellite SAT. Alternatively, there is a direct connection between the BST ground station and the TRA transmitter.

In anticipation of FIG. 4, a mobile part POP can be seen, which has an HF part HFT, which is connected to an antenna ANT. The handset SPP also contains a digital signal processor DSP and an audio unit AUD, which has a loudspeaker LSP and a microphone MIC connection. An essential component of the handset is a receiver RWE, which is equipped, for example, with two ferrite antennas FA1 and FA2, which are at right angles to one another in order to avoid directional dependence.

The receiver is RWE forms one channel out ^¬ in the simplest case and can receive a frequency in the LW, MW or HF range, it means operates in a frequency range of, for example, 148.9 kHz to 30 MHz. At higher frequencies, rod antennas may have to be used instead of the ferrite antennas.

The receiver RWE can also be tuned, especially in the

Be the sense of a scanner and have a frequency memory FRM. The receiver RWE can then be set up to determine those radio transmitters which have the greatest field strength and / or lowest bit error rate and store them in the frequency memory FRM. On the other hand, frequency values can also be stored in the frequency memory FRM, which have been specified by the network NET and have been transmitted to the handset POP via the usual mobile radio link.

FIG. 4 is also intended to represent the SPP satellite telephone and therefore a parabolic antenna PAN is shown in broken lines, which in the case of a SPP satellite telephone replaces the otherwise rod-shaped antenna ANT.

According to FIG. 2, the radio transmitter TRA or TRA 'consists of an encoder COD and a modulator MOD, the latter controlling a high-frequency output stage HFS, which feeds the antenna SAN. The encoder COD receives the audio signal AUD, for example from the studio RFS, here also called "broadcast signal", as well as a channel coding CCO and the specific information INF, which comes from a priority selection PRI, which in this example has three different ^messages are NR1, NR2 and NR3 supplied, for example, a message NR1 for a mobile phone POP, a message NR2 for a satellite phone SPP and a message NR3 for egg ^¬ NEN pager PAG, which is also shown in Fig. 1 and also includes a receiver, which can receive the signals of the radio stations used.

The radio transmitter RFS works digitally and the data rate is continuously adapted to the broadcast signal to be transmitted by data compression and a fluctuating bit rate. For example, the signals AUD can be scaled dynamically; a Huffman variable length code can be used for their coding. Further details on digital broadcasting on long, medium and short waves can be found in the "System Description DMW", Technical Report of Deutsche Telekom, Internationale Funkausstellung 1997, Berlin. Digital modulation methods for are also described radio in the articles "Digital unter 30 MHz", Hans Weber, ELRAD 1997, number 10, pages 60 to 63 and "Digitale Kurzwelle", Hans Weber, Funkschau 3/98.

As illustrated in FIG. 3, the radio channel has a maximum bit rate MAX, which is determined by the bandwidth of the radio transmitters in the LW, MW and KW range - mostly 9 kHz - and is already defined in the modulator and which in the system mentioned above for the audio data is 24 kbit / sec. This maximum bit rate is only required for very complex or higher-frequency audio signals. In Fig. 3, the audio data stream required for a selected period is shown hatched. The remaining "free space" is now "filled" with specific information, here messages NR1, NR2 and NR3. The modulator MOD is set up to insert the additional data blocks of suitable length into the data stream at the appropriate times, for which means suitable for the person skilled in the art, such as elastic or controllable buffer memories, are available.

It can also be provided that if there is too much congestion of specific information, which could occur, for example, in the case of a long complex audio signal with few pauses, the bit rate for the radio signal (e.g. audio signal) can be temporarily reduced, which e.g. is possible with scalable audio coding. This may temporarily reduce the quality of the audio signal, but it will clear the jam in the data to be transmitted for pagers, etc. Regarding the scalable coding, the MPEG-4 audio standard (MPEG = Moving Picture Experts Group) is mentioned in

"Audio transmission on the Internet and intranet", Technical Report, Internationale Funkausstellung Berlin 1997., which is used, for example, on the Internet.

The priority selection PRI described in connection with FIG. 2 can of course also be part of the modulator MOD, as it is irrelevant which "blocks" in the Transmitters (or receivers) are available, since the signal processing takes place primarily in software in processors. The priority of the individual signals or information blocks can be given by a short classification, expediently contained in a header of the blocks, whereby the broadcast signal AUD is naturally always given absolute priority. However, exceptions could be signals of specific information, which are used, for example, to warn of disasters.

5 schematically shows a block BLO which contains the information INF or a part of this information INF. The block may have a predetermined bit length and, apart from a header HEA, may initially contain block length information BIN, furthermore an identification IDE of the subscriber to be called and finally a message field NAF. In the message field, an identification IDS regarding the calling subscriber, e.g. its number, as well as a short message to the called party, e.g. "Call from 7pm".

The order of information within the BLO block mentioned here offers advantages, but is by no means mandatory. Likewise, further specific information can also be contained in the block or in a plurality of blocks, such as test fields or the like.

In normal operation, the radio receiver RWE of the POP or SPP handset is constantly switched on, ie ready to receive. In the event of a call, a connection is established between a base station FIP1, FIP2 and the information INF broadcast by the transmitter TRA can be ignored or rejected by the mobile unit POP, SPD, provided the reception conditions are appropriate. If, however, there is no radio connection to a satellite or a base station, then for example a call request is received via radio, with for example the telephone number of the caller, ie the identification IDS in the block BLO. The handset POP, SPD can then indicate the call request to the user by means of a ringing call or via an optical display, so that the user can then bring the handset to a location with appropriate reception quality, for example outdoors or to a window and accept the call. If too much time passes for this process and, for example, the caller has already hung up, the user of the handset can call back using the stored telephone number. The same applies, of course, to pagers PAG, which are purely passive message recipients.

The invention thus uses existing long-wave or medium-wave transmitters, possibly also short-wave transmitters, to transmit short messages, “specific information”, to mobile

Transfer recipient. These mobile receivers can only be set up to receive these messages, as is the case with a pager, for example. However, separate receivers RWE can also be provided as an add-on in mobile or satellite telephones so that certain messages can be received, stored and also displayed for the corresponding mobile or satellite telephone. Although this is also possible with the known SMS (Short Mail Service), for example in the GSM system, it always presupposes that the radio telephone is not in a "radio shadow". The invention thus enables a ^¬ we sentlich improved accessibility of the pager or cellular / satellite phone, which can be further improved if frequency not only a frequency to transmit the specific information but different frequencies, for example, long waves and short waves are used. In contrast to the known methods in which additional texts and signaling are transmitted in the case of FM radio broadcasts, for example RDS or DAB (Digital Audio Broadcast), no additional frequencies or increased bandwidth are required.

Claims

claims

1. Method for transmitting information to a mobile receiver (RWE), e.g. to a pager or to a mobile part of a mobile radio or satellite telecommunications system, characterized in that a specific piece of information (INF) to be transmitted to the receiver (RWE) is transmitted by at least one radio transmitter (TRA) in addition to a radio signal ( AUD) is emitted, the transmitter is modulated according to a digital process in which the data rate is continuously adapted to the broadcast signal to be transmitted by data compression and a fluctuating bit rate and in periods in which the maximum possible bit rate is not transmitted, which is caused by the difference between the maximum bit rate and the free channel capacity given by the broadcast signal is filled with the specific information.

2. The method according to claim 1, characterized in that the broadcast signals (AUD) are dynamically scaled.

3. The method according to claim 1, characterized in that a Huffman variable length code ver ^¬ is used to encrypt the radio signals (AUD).

4. The method according to any one of claims 1 to 3, characterized in that the transmission of broadcast ^¬ radio signals (AUD) always takes place with higher priority than the transmission of specific information (INF).

5. The method according to any one of claims 1 to 4, characterized in that the specific information (INF) is classified into signals (NR1, NR2, NR3) with different priorities with regard to the transmission.

6. The method according to claim 5, characterized in that the priority is chosen the higher, the lower the permissible delay is specified with respect to a real-time transmission.

7. The method according to any one of claims 1 to 6, characterized in that the bit rate of the encoded radio signals (AUD) is temporarily reduced from a bit jam of the specific information (INF) to be sent that exceeds a predetermined dimension due to insufficient channel capacity.

8. The method according to any one of claims 1 to 7, characterized in that the specific information (INF) is encoded in digital information blocks (BLO) of variable length.

9. The method according to claim 8, characterized in that the classification in signals of different priority in the header (HEA) of the information blocks (BLO) is written.

10. The method according to any one of claims 1 to 7, characterized in that the radio transmitter or transmitters is operated in the range from 150 kHz to 30 MHz.

11. Broadcast transmitter for broadcasting a broadcast signal (AUD), with a coder (COD) for compressing and digitally coding an analog input signal (AES), with a modulator (MOD), to which the coded signal is fed, and with a short, Medium or long wave range working high frequency stage (HFS), wherein the broadcast signal with fluctuating bit rate is emitted, characterized. that the encoder (COD) is additionally supplied with specific information (INF) and the encoder is set up in periods in which the maximum possible bit rate is not transmitted, which is determined by the difference between the maximum bit rate and that by the broadcast signal (AUD) given the bit rate claimed to fill up free channel capacity with the specific information.

12. Broadcast transmitter according to claim 11, characterized in that the encoder (COD) is set up to transmit broadcast signals (AUD) with higher priority for transmission than specific information (INF).

13. Radio transmitter according to claim 11 or 12, characterized in that the encoder (COD) signals (NR1, NR2, NR3) of the specific information (INF) of different priority are supplied.

14. Radio transmitter according to claim 12 or 13, characterized in that the encoder (COD) is set up to read the priority of the signals (AUD, NR1, NR2, NR3) from headers of signal blocks.

15. Radio transmitter according to one of claims 11 to 14, characterized in that the encoder (COD) is set up to temporarily reduce the bit rate of the coded radio signal (AUD) from a predeterminable bit jam of the specific information to be sent (INF).

16. Mobile receiver (RWE), for receiving the encoded in Informa ^¬ tion blocks (BLO) of incoming digital information (INF) and for storing and / or displaying the decoded information is arranged for use in a procedural ren according to any one of claims 1 to 10 and for receiving a transmitter according to one of claims 11 to 15.

17. Mobile receiver according to claim 16, characterized in that it is contained in a pager (PAG).

18. Mobile receiver according to claim 16, characterized in that it is included as an additional receiver (RWE) in a mobile radio device or in a satellite telephone.

19. Mobile receiver (PAG, RWE) according to one of claims 11 to 18, characterized in that it is set up for the continuous reception of radio transmitters in substantially different bands, such as short wave and long wave.

20. Mobile receiver according to one of claims 1 to 19, characterized in that it is set up for receiving and evaluating both the radio signals (AUD) and the specific information.