HK1022589A - Method for making emergency calls in cordless telecommunications systems, in particular dect/gap systems - Google Patents

Description

Method for making emergency calls in a wireless communication system, in particular a DECT/GAP system

no marking

In an information system having an information transmission path between an information source and an information sink, a transmission and reception device is provided for processing and transmitting information, wherein

1) The information processing and information transmission can be effected in one preferred direction (simplex) or in both transmission directions (duplex),

2) the information processing is either analog or digital,

3) the information transmission is based on various information transmission methods FDMA (frequency division multiple access), TDMA (time division multiple access) and/or CDMA (code division multiple access) via the remote transmission path, for example according to the following standards: DECT, GSM, WACS or PACS, IS-54, PHS, PDC etc. (see IEEE journal of communication, 1 month 1995, pages 50 to 57; D.D falcon et al: "time division multiple access method for wireless personal communication") and/or wireless connection implementation.

"information" is a generic concept that represents both the content of a signal (information) and the physical form of expression (signal). Information having the same signal content-the same information-can also have different signal forms. Whereby for example an information relating to the object can be

(1) In the form of an image, the image is,

(2) as a result of the language being spoken,

(3) as a matter of language in which the writing is made,

(4) transmitted as encrypted language or image.

The transmission according to (1) … (3) is typically carried out by means of continuous (analog) signals, while the transmission according to (4) is typically carried out by means of discontinuous signals (e.g. pulses, digital signals).

Starting from this general definition of information, the invention relates to a method for making emergency calls in a wireless communication system, in particular a DECT/GAP system, according to the preamble of claim 1.

Wireless communication systems of the above defined type are for example the DECT system [ digital enhanced (formerly: european) wireless communication; see (1): information technology electronics 42(1992) japan/february, first generation, berlin, germany; pilger "structure of DECT standard", pages 23 to 29, in conjunction with ETSI publication ETS300175-1 … 9, october, 1992; (2): journal of communications 16(1993), first phase, j.h.koch: "digital comfort for wireless communication-DECT opens up a new field of application", pages 26 and 27; (3) tec 2/93-Ascom's journal of technology "route of global mobile communications", pages 35 to 42; (4): review of philips general information, volume 49, third, september, 1991, r.j.mulder: "DECT, global wireless access system"; (5) WO93/21719 (FIGS. 1 to 3 and the description to which it belongs) or GAP systems (generic Access protocol; ETSI publication PRETS300444, April 1995, draft Final, ETSI, France), which are constructed, for example, as described in FIG. 1.

The GAP standard is a sub-standard of the DECT standard and has the function of guaranteeing the interworking of the DECT air interface, in particular of public communication applications.

If a DECT/GAP system is discussed below, this means a private and/or public system.

According to the DECT/GAP standard, a maximum of 12 connections parallel to the DECT/GAP mobile part MT1 … MT12 can be formed on the DEC/GAP base station BS according to the description of fig. 1 by means of the TDMA/FDMA/TDD- (time division multiple access/frequency division multiple access/time division multiplexing) method over the DECT/GAP air interface for the frequency range between 1.88 and 1.90 GHz. The number 12 is derived from the number "K" which is used for the multiplexing of the DECT/GAP system for the time slots and the communication channel (K = 12). The connection can be internal and/or external. When internally connected, two mobile parts, e.g. mobile part MT2 and mobile part MT3, registered at the base station BS can communicate with each other. When the external connection is established, the base station BS with the communication network TKN is connected to the communication network connected to wires, for example in the form of a wire connection, via the communication connection device TAE or the peripheral device NStA, or is connected to a higher-level communication network in the form of a radio as a repeater according to WO 95/05040. When externally connected, a mobile part, for example the mobile part MT1, can be used to communicate with a user in the communication network TKN via the base station BS, the communication connection means TAE and the private exchange NStA. If the base station BS has only one interface to the communication connection TAE and the private exchange NStA, as is the case, for example, in Gigaset951 (siemens radio telephone, see communication report 16, (1993) first date, pages 26 and 27), only an external connection can be established. If the base station BS has two interfaces to the communication network TKN, as is the case, for example, in Gigaset951 (siemens radiotelephone, see communication report 16, (1993) first, pages 26 and 27), then, in addition to the external connection with the mobile part MT1, an additional external connection of the communication terminal device TKE wired to the base station BS can be realized. In principle, it is also conceivable here for the second mobile part, for example the mobile part MT12, to use a second interface for external connection instead of the communication terminal TKE. The mobile part MT1 … MT12 is powered by dry batteries or batteries, and the base station BS, which is a wireless small exchange, is connected to the voltage network SPN via a network connection NAG.

Fig. 2 shows the s.althammer, d.brueckmann: schematic circuit diagram of the base station BS and the mobile part MT of a "highly optimized IC for DECT radio telephones". The base station BS and the mobile part MT have a radio part FKT with an antenna ANT for transmitting and receiving radio signals, a signal processing means SVE and a central controller ZST, which are connected to one another in the described manner. The components contained in the radio part FKT are basically known, such as the transmitter SE, the receiver EM and the synthesizer SYN. A coder/decoder CODEC is contained in the signal processing means SVE. The central controller ZST contains a microprocessor μ P for the base stations BS and the mobile part MT, which has a data transmission according to the OSI/ISO layer model [ see (1): lecture documents german telecommunications, yearbook 48, pages 2/1995,102 to 111; (2) ETSI publication ETS300175-1 … 9, october 1992, a program module PGM, a signal control section SST and a digital signal processor DSP, which are connected to one another in the described manner. The layers defined in the layer mode represent the first four layers only for the base station BS and the mobile part MT directly. The signal control part SST is formed in the base station BS as a time switch controller TSC and in the mobile part MT as a burst mode controller BMC. The main difference between the two signalling controllers TSC, BMC is that the base station specific signalling control part TSC contains an additional switching function with respect to the mobile part specific signalling control part BMC.

The functional manner of the principle of the circuit arrangement described above is described, for example, in the above-mentioned publication unit 31(1993), No. 6, pages 215 to 218.

The circuit configuration depicted in fig. 2 is supplemented in the base station BS and the mobile part MT by further functional means in accordance with the functions of the DECT/GAP system of fig. 1.

The base station BS is connected to the communication network TKN via the signal processing means SVE and the communication connection means and the private branch exchange NStA. The base station BS also has a user interface (functional means indicated by dashed lines in fig. 2), which is, for example, an input device EE embodied as a keyboard, a display device AE embodied as a display, a speech/listening device SHE embodied as a receiver with a microphone MIF and an earphone HK, and a call bell TRK.

The mobile part MT contains a user interface which can be selected from the base station BS and has the above-mentioned control elements cooperating with this user interface.

Fig. 3 shows a cellular DECT/GAP multi-system CMI (wireless multi-cellular integration) from the DECT system of fig. 1, in which a plurality of the above-mentioned DECT/GAP systems TKS respectively appear in arbitrary locations with a base station BS and one or more mobile parts MT, for example-arranged in "hot spots" -concentrated in a control building with a large open office. However, instead of this "closed" geographical location, such as a control building, an "open" geographical location with strategic communication significance, such as a square in a large city with high traffic flow, a large concentration of economic units and a large number of crowd moves can also install the cellular DECT/GAP multi-system CMI. A number of base stations BS are here arranged in an open office as antenna diversity base stations in contrast to the base stations described in WO95/10764 in fig. 1 and 2. The concentration of DECT/GAP systems TKS is here indicated (uninterrupted wireless notification of the geographical location), each DECT/GAP system TKS operating in the same range as an overlapping cellular DECT/GAP wireless area FB.

Depending on the degree of overlap, the same region may here mean:

a) the first base station BS1 of the first communication system TKS1 is provided in one first wireless area FB1 and the second base station BS2 of the second communication system TKS2 is provided in one second wireless area FB2, and can constitute to at least one mobile part MT_1,2The communication connection of (a) to (b),

b) the base station BS3 of the third communication system TKS3 and the fourth base station BS4 of the fourth communication system TKS4 are arranged in a common third wireless area FB3 and can constitute to at least one mobile part MT_3,4To the communication connection of (1).

FIG. 4 shows the TDMA structure of the TKS of the DECT/GAP system, which proceeds from FIGS. 1 to 3 and is taught in the publication "information technology electronics 42(1992) month 1/2, first generation, Berlin, Germany; pilger: "structure of DECT standard", pages 23 to 29, in combination with ETS300175-1, 10 months 1 … 9,1992. The DECT/GAP system is a hybrid system involving multiple access methods where wireless communication can be transmitted according to FDMA principles according to the time-sequential TDMA principle described in fig. 4 with 10 multiples of the frequency band between 1.88 and 1.90GHz from the base station BS to the mobile part MT and from the mobile part MT to the base station BS (time division multiplexing). The sequence is determined here by a multi-frame MZR, which is generated every 160ms and has 16 frames, each with a period of 10 ms. Information about the C-, M-, N-, P-, Q-channels defined in the DECT standard is transmitted to the base station BS and the mobile part MT at these frames ZR, respectively. If the information for a plurality of these channels is transmitted at a time frame ZR, the transmission takes place with a priority M > C > N and P > N. Each of the 16 frames ZR of the multi-frame MZR is in turn divided into 24 time slots ZS with a period 417 μ s, respectively, of which 12 time slots ZS (time slot 0 … 11) are used for the transmission direction "base station BS → mobile part MT" and the other 12 time slots ZS (time slot 12 … 23) are used for the transmission direction "mobile part MT → base station BS". In each of these time slots ZS, information having a bit length of 480 bits is transmitted according to the DECT standard. Of these 480 bits, 32 bits are transmitted as synchronization information in the SYNC field, and 388 bits are transmitted as useful information in the D field. The remaining 60 bits are transmitted as additional information in the Z field and as protection information in the "protection time" field. 388 bits of the D field transmitted as useful information are sequentially divided into an a field 64 bits long, a B field 320 bits long, and a word of "X-CRC" 4 bits long. The 64-bit long A field contains an 8-bit long data header, the 40-bit long data record contains the time for the C-, Q-, M-, N-, P-channels and a 16-bit long "A-CRC" word.

In addition, for the DECT/GAP systems described above, radio communication systems which are built up in the future on the known multiple access methods FDMA, TDMA, CDMA (frequency division multiple access, time division multiple access, code division multiple access) and hybrid multiple access methods which are formed therewith can also be used for transmitting emergency calls.

The steps described below are provided by way of example in the DECT/GAP standard for establishing a communication connection between a base station BS and a mobile part MT in a DECT/GAP system according to fig. 1 to 4.

The base station BS (radio fixed part RFP) transmits, according to fig. 1 to 4, via the DECT air interface at regular time intervals, a dummy bearer on the simplex transmission route, which is the broadcast information received via the mobile part MT (radio mobile part RPP) according to fig. 1 to 4 and which is used for synchronization and connection set-up with the base station. The broadcast information need not be transmitted in a pseudo transmission route (pseudo bearer).

It is also possible for the base station to contain no dummy transmission routes, since the base station already contains at least one communication connection to another mobile part, a so-called Traffic-Bearer (Traffic-Bearer), and transmits the necessary broadcast information on the transmission route. In this case, it is desirable that the mobile part having a communication connection to the base station is able to receive broadcast information-for example, in the case where the broadcast information is transmitted on a pseudo transmission route.

This broadcast information-chapter 9.1.1.1-contains access rights information, system information, and paging information according to ETSI publication ETS300175-3,1992, month 10.

In addition the system information contains additional information to inform the mobile part whether the base station is the one it can transmit an emergency call (the subject matter is discussed publicly in ETSI-reo 3RGremium and ETSI-reo 3N gredium in the first half of 1996).

If the mobile part receives this additional information and if the respective mobile part has the right to access the base station transmitting the additional information (for example if the mobile part applies and registers according to WO 94/10785-claim iVm of the introductory part of fig. 4), then a pre-formed emergency call number is automatically selected and an emergency call connection to the emergency call service point is established on the mobile part according to a special user interface procedure (for example selecting the emergency call number 112, pressing the emergency call key, selecting menu information "EMERGENCY CALL", etc.) on the basis of the general (usual) communication connection according to the GAP standard (see ETSI publication prETS s300444,1995, month 4) (see ETSI publication prETS 444, month 4 1995, 3008.10 ("CC-INFO" MULTI key "), based on the direct call connection.

The above-described procedure for transmitting emergency calls in DECT/GAP systems can be sufficient for private systems, in which it can be assumed that the mobile part has access rights to the base station, but the procedure determined is not sufficient for public systems, in which the access rights may be provided only in individual cases.

In addition, in the above-described procedure for transmitting emergency calls in DECT/GAP systems, it cannot always be guaranteed that a mobile part having access rights can transmit an emergency call to a base station in any case. Hereby, for example, the situation may occur in case no respective base station has a free channel, e.g. because of restricted channel resources, or because of other (unusual) reasons (see ETSI publication prETS300444,1995, month 4, chapter 8.2.2.3 and chapter 8.8) having to reject the request or desire to transmit an emergency call. The mobile part is able to search for other base stations so that emergency calls can still be transmitted, but there is no guarantee that the search must be successful.

It is also problematic that if an emergency call is successfully transmitted from the mobile part to the emergency call service point via the base station in the first location, it is not clear when, in particular, who can again end or clear the existing emergency call connection.

The transmission of emergency calls in wireless communication systems is known in mobile wireless communication systems according to the GSM standard (see publication m.mouly, M-b.pautet: "GSM system for mobile communication", 1992, international united states number 2-9507190-0-7, pages 49, 453, 437 and 532535).

The above-described problems associated with emergency call transmissions are not present in these mobile radio communication systems.

The object on which the invention is based is to enable an efficient and reliable emergency call in a wireless communication system, in particular a DECT/GAP system.

This object is achieved by the features given in the characterizing part of claim 1, starting from the method defined in the preamble of claim 1.

The idea underlying the invention is primarily that emergency calls in a radio communication system are made by means of a specific emergency call transmission procedure, taking into account the fact that the system contains mobile parts with or without access rights to the base station, and by means of which procedure an emergency call connection is made in all cases.

Advantageous developments of the invention are given in the dependent claims.

An embodiment of the invention is explained with the aid of fig. 5.

Fig. 5 shows, with the aid of a start state diagram, an emergency call transmission procedure which ensures efficient and reliable transmission of emergency calls in the DECT/GAP system according to fig. 1 to 4.

Before the mobile part MT (portable part) initiates the above-described procedure with the base station BS (fixed part), it should have-as already mentioned at the outset-an access right to this base station BS or, if this is lacking, as a precaution should have a synchronous, at least temporary, communication with the base station BS which is restricted for the delivery of emergency calls. This advanced synchronization greatly shortens the setup time for emergency calls in case of emergency. The synchronization with the base station enables the base station to transmit the additional information indicated by the start within the range of the transmitted broadcast information. During the search for a base station, the mobile part does not have any access rights, it is advantageous if the mobile part first searches for a public base station, because this additional information can be transmitted with more reliability with respect to the private base station, and searches for the private base station only if this search is not successful. The criterion for the distinction between public base stations and private base stations is here simply the identification ARC (access rights level) used by the public base station, which is transmitted more frequently than the additional information.

If the mobile part MT has found a base station BS according to the above criteria, the transmission of the emergency call is initiated on the mobile part MT when required by means of the already noted manual user interface procedure. The mobile part MT then transmits a first MAC information "BEARER _ REQUEST" (see ETSI publication ETS300175-3,1992, 10 months, chapter 7.3.3.2) with the parameter "PMID" (portable MAC identification) to the base station BS within the scope of the connection establishment procedure (BEARER establishment procedure; see ETSI publication ETS300175-3,1992, 10 months, chapter 10.5.1.1), for which the parameter "PMID" parameter "TPUI" (temporary portable subscriber identity; see ETSI publication ETS300175-6,1992, 10 months, chapter 6.3.1) is designed as a temporary identity specific to the emergency call. By this special information the base station BS can distinguish between emergency call requests and general call requests of the mobile part. In reply to the received first message, the base station BS transmits a second MAC message "BEARER-CONFIRM" (see ETSI publication ETS300175-3,1992, month 10, chapter 7.3.3.3) to the mobile part MT.

When the base station BS (MAC protocol layer) recognizes an emergency call request, the higher protocol layer and the protocol layer control (lower layer authority LLME) the task of being granted to set up a free communication channel. The establishment can take the form here of either-if all channels in the base station BS are being established using a free channel by clearing an existing communication connection, or reserving a free channel from the peripheral. If a communication channel is involved in the above case, this means a voice and data channel on the network side and a radio channel or time slot.

After establishing the free communication channel and informing the mobile part MT of this, the mobile part MT transmits a first NWK message "CC-SETUP" (see ETSI publication ETS300175-5,1992, month 10, chapter 6.3.2.1) with

1) The information component "BASIC session" (see ETSI publication ETS300175-5,1992, month 10, chapter 7.6.4), wherein the field "CALL CLASS" has the contents of an emergency call,

2) the information component "PORTABLE IDENTITY" (see ETSI publication ETS300175-5,1992, month 10, chapter 7.7.30) and the field "IPUI-N",

3) the information component "FIXED identity" (see ETSI publication ETS300175-5,1992, month 10, chapter 7.7.18) and the field "LENGTH OF CONTENTS O".

The base station BS should receive this NWK information from the mobile part MT without checking "FIXED-IDENTITY" and "PORTABLE-IDENTITY" and continue processing with NWK protocol layer procedures according to the GAP standard (see ETSI publication prets300444, month 4 1995, chapter 8.2) without checking that the NWK protocol layer IDENTITY.

After the emergency call has been identified according to the GAP standard, the base station BS establishes an emergency call connection to the emergency call service point and transmits a second NWK information "CC-CONNECT" (see ETSI publication ETS300175-5,1992, month 10, chapter 6.3.2.6) to the mobile part MT. The emergency call connection is thereby established automatically by the public base station and preferably by the private base station, preferably by automatic selection of the emergency call number.

The actual emergency call information can now be input directly or indirectly to the mobile part MT. This emergency call information is sent to the emergency call service point through the base station BS.

Another advantage is that when an emergency call connection is established and emergency call information is transmitted, the existing emergency call connection is cleared again by the base station. This makes it possible to prevent the emergency call connection from being cleared on the mobile part by an unintentional user interface procedure in case of an emergency, for example an emergency.

Claims (11)

1. A method for making emergency calls in a wireless communication system, in particular a DECT/GAP system, in which emergency calls are initiated to an emergency call service point by a radio Base Station (BS) which is connected to the wireless mobile part (MT) by communication, by means of a manual user interface procedure on the wireless mobile part (MT),

the method is characterized by comprising the following steps:

a) the radio mobile part (MT) transmits a first message (BEARER-REQUEST) with a temporary first identifier (TPUI) specific to the emergency call to the radio Base Station (BS), whereupon the radio mobile part searches on the radio Base Station (BS) for connecting the emergency call to the emergency call service point,

b) the radio Base Station (BS) distinguishes between a general communication request and an emergency call by means of the received first identifier,

c) the radio Base Station (BS) replies to the first information with a second information (BEARER-CONFIRM) and provides a free communication channel for establishing an emergency call connection,

d) the radio mobile part (MT) transmits to the radio Base Station (BS) a third information (CC-SETUP) having a first information component (BASIC SERVICE) containing a call identification (CALL CLASS) for the emergency call, a second information component (PORTABLE-IDENTITY) containing a second IDENTITY specific to the mobile part and a third information component (FIXED-IDENTITY) containing a null content identification (LENGTH context O), which third information enables the radio Base Station (BS) to establish an emergency call connection to the emergency call SERVICE point,

e) the radio Base Station (BS) establishes an emergency call connection to the emergency call service point, and notifies the radio mobile part (MT) of the establishment of the emergency call connection in reply to a fourth message (CC _ CONNECT) as a third message.

2. A method as claimed in claim 1, characterized in that if the first radio Base Station (BS) is a private radio base station, the emergency call connection to the emergency call service point is established by automatic dialling of an emergency call number.

3. A method as claimed in claim 1, characterized in that the emergency call connection to the emergency call service point is established automatically if the first radio Base Station (BS) is a public radio base station.

4. A method as claimed in one of claims 1 to 3, characterized in that a free communication channel for the emergency call connection is established by reserving a communication channel from a plurality of communication channels available in the radio Base Station (BS).

5. A method as claimed in one of claims 1 to 3, characterized in that if all communication channels are occupied, one of the plurality of communication channels available from the radio Base Station (BS) is free to establish a free communication channel for the emergency call connection.

6. A method as claimed in any one of claims 1 to 5, characterized in that the communication channel comprises a radio channel between the radio Base Station (BS) and the radio mobile part (MT), and comprises a speech/data channel between the radio Base Station (BS) and the emergency call service point.

7. Method according to one of the claims 1 to 6, characterized in that the established emergency call connection is cleared inside the wireless communication system by means of a radio Base Station (BS).

8. The method according to one of claims 1 to 7,

a) transmitting additional information from the radio Base Station (BS), which is received through the radio mobile part (MT) and indicates that the emergency call can be transmitted through the radio Base Station (BS) to the emergency call service point,

b) the first wireless mobile part (MT) receives additional information from the first wireless Base Station (BS) and does not have any access rights to this first wireless mobile part (MT), as a precaution against emergency calls, the first wireless mobile part (MT) at least temporarily synchronises with the first wireless Base Station (BS) to establish a communication restricted to making emergency calls.

9. A method as claimed in one of claims 1 to 8, characterized in that the radio communication system is a DECT/GAP system.

10. A method according to one of claims 1 to 8, characterized in that the wireless communication system is a PHS system, a WACS system or a PACS system.

11. A method according to one of claims 1 to 8, characterized in that the radio communication system is a CDMA system, a TDMA system, an FDMA system or a hybrid system in relation to said transmission standard.