AU727966B2

AU727966B2 - Terminal for digital mobile radio, and a method for evaluating data received in such a terminal

Info

Publication number: AU727966B2
Application number: AU82062/98A
Authority: AU
Inventors: Jan Meyer; Bernhard Raaf
Original assignee: Siemens AG
Current assignee: Thales DIS AIS Deutschland GmbH
Priority date: 1997-04-24
Filing date: 1998-04-20
Publication date: 2001-01-04
Anticipated expiration: 2018-04-20
Also published as: EP0978166B1; ID22829A; CN1261477A; WO1998048521A3; AU8206298A; WO1998048521A2; DE59801970D1; EP0978166A2

Description

GR 97 P 1506 P 1 PCT/DE 98/01101 Description Terminal for digital mobile radio, and a method for evaluating data received in such a terminal The present invention relates to a terminal for digital mobile radio and to a method for evaluating received data in a terminal for digital mobile radio, which offers the capability to reduce the power consumption when receiving information which is not important.

As a rule, time-division multiplex methods are used for transmitting data in digital mobile radio. In this case, the bandwidth which is available on a carrier signal transmitted between base stations and mobile stations is subdivided in time between the various subscribers. Time-division multiplex and frequency-division multiplex methods are frequently combined in such a manner that there are a number of carrier frequencies, which are then each accessed separately using the time-division multiplex method.

Thus, for example, in the GSM system (Global System for Mobile Communications), carrier frequencies with a spacing of 200 kHz from one another are in each case used, which, for their part, are in turn subdivided into each case eight time slots or data packets. In this case, data is frequently transmitted to the mobile stations from the base stations which is important for only a single one of the mobile stations, or for none of them. However, conversely, this can also relate to data packets which are sent from a mobile station to a base station. Data packets which are not important may in this case be data packets which contain so-called dummy data or filling data, but they may also be data packets which contain information which does not relate, or no longer relates, to the received terminal since, for example, the terminal has already received AMENDED SHEET

I

GR 97 P 1506 P la PCT/DE 98/01101 it once. In the prior art, all the transmitted data is received by the receiving terminal and is processed irrespective of whether the data is or is not required by the terminal. This results in increased power consumption in the terminal which is disadvantageous, particularly for mobile stations powered by batteries or rechargeable batteries.

WO96/37051 discloses a method and an apparatus for saving power in portable battery-powered radio appliances. In this case, a received message is compared with a previous received message. If the two messages match, the radio appliance is switched to a power saving mode, in which the message received later is not processed any further. WO94/08432 discloses a method for transmitting information between a base station and a mobile station in a digital control channel of a telecommunications system. In this case, the base station transmits change characters which indicate whether successive messages differ. The mobile station processes received messages only if a previous change character indicates a change in comparison to the previous messages. WO94/27377 discloses a mobile station for mobile radio, having a receiving device for receiving digital data packets and for providing softdecision values for received data packets, and having a decision device which, before complete reception of an information unit comprising one or more data packets, uses a part of the information unit which has already been received to decide whether the information unit is or is not important and, if the decision is that the information unit is not important, causes the receiving unit to ignore the rest of the information unit. In this case, the soft-decision values are used to determine whether a received data packet is or is not free of errors. If the data packet is free of errors, a power saving signal is produced.

AMENDED SHEET GR 97 P 1506 P Ib PCT/DE 98/01101 The received data packet is furthermore compared with expected or predetermined data in order to determine whether the data packet contains information which is or is not important for the mobile station. If the information is not important, the mobile station is switched AMENDED SHEET GR 97 P 1506 2 The object of the present invention is thus to provide a terminal for digital mobile radio as claimed in the preamble of the attached claim 1, and to provide a method for evaluating received data in a terminal for digital mobile radio, in the case of which terminal and method a reduction in the power consumption is ensured when receiving information which is not important.

This object is achieved by a terminal for digital mobile radio having the features of the attached claim 1, and by a method for evaluating data received in a terminal for digital mobile radio, having the features of the attached claim 12.

The terminal according to the invention for digital mobile radio comprises a receiving device for receiving digital data packets, and is characterized by a decision device which, before complete reception of an information unit which comprises one or more data packets, uses a part of the information unit which has already been received to decide whether the information unit is or is not important and, if the decision is that the information unit is not important, causes the receiving unit to ignore the rest of the information unit. The method according to the invention for evaluating received data as claimed in claim 12 is implemented in the terminal according to the invention and comprises the following steps: receiving digital data packets, using an already received part of an information unit to decide, before complete reception of the information unit, whether the information unit is or is not important, and ignoring the rest of the information unit if the information unit is not important.

GR 97 P 1506 3 According to the present invention, the terminal does not wait until an information unit has been received completely, but an evaluation is carried out at an early stage on the basis of an already received part of an information unit to determine whether the transmitted information unit is or is not important for the relevant terminal. If the information unit is not important for the relevant terminal, then reception of the rest of the information unit is terminated. The rest of an information unit which has been identified as not being important thus may not be received or subsequently processed, and this results in a considerable reduction of the power consumption in the terminal. The terminal according to the invention may be a base station or a mobile station. Particularly in the case of a mobile station powered by batteries or rechargeable batteries, the reduced power consumption permitted by the present invention is of major importance.

Furthermore, the present invention is independent of the system in which the data is transmitted. For example, the present invention is just as applicable to the GSM system as to the DECT system (Digital European Cordless Telephone), with the timedivision multiplex method being used to transmit digital data in both systems. In the time-division multiplex method, the data is transmitted in so-called time slots, which each contain one data packet. In the GSM system, each time frame contains eight time slots or data packets, while in the DECT system, twelve time slots or data packets are in each case provided for transmission and reception per frame.

The present invention allows information units comprising one or more data packets to be ignored after receiving only a part of the information unit, if the information unit is identified as not being important.

In this case, a decision is accordingly made after Sreceiving just one data packet or a part of a data 4Dacket GR 97 P 1506 4 as to whether the associated information unit is or is not important.

For example, a signaling channel, or, in other words, an information unit containing signaling data, is provided in the GSM system, which is transmitted to the mobile stations from a base station every 0.5 to 2 s. The signaling information unit is in this case distributed over four time slots, with in each case one time slot being transmitted in one of four time frames which follow one another, that is to say the information unit is transmitted in blocks separated in time. Even after the first of four data packets is received, the present invention makes it possible to avoid receiving and thus processing the remaining three data packets, if the information unit is identified as not being important on the basis of the first received data packet.

In this case, for the purposes of the invention, not important means all information units which contain data which are irrelevant for the receiving terminal or are not required, or are no longer required, by it. Such data may be, for example, information units containing dummy data or filling data which are transmitted, for example, by a mobile station, whenever no call need be switched and, thus, no data need be transmitted in the signaling channel.

Furthermore, information units which are not important may relate to data which has already been received by the receiving terminal, but is not required once again.

A further possibility for the information units which are not important is data which does not relate to the receiving terminal, but only to other terminals.

Advantageous refinements of the present invention are specified in the dependent claims 2 to 11 and 13 to 22.

GR 97 P 1506 5 The decision as to whether the information unit is or is not important is in this case advantageously made using a probability value which is calculated from the soft-decision values of the already received part of the information unit. Soft-decision values of a digital signal are provided by an equalizer in the receiving unit of terminals and contain information about the statistical confidence of the transmitted digital value. In other words, the soft-decision value of a received digital signal indicates a probability value as to whether the digital signal has been transmitted correctly. Thus, according to the invention, a probability value is calculated by means of the soft-decision values of the already received part of the information unit, these values being a measure of the correctness of the received data. This probability value is used as a basis for the decision as to whether the information unit is or is not identified as not being important. If, as a result of this, there is a sufficiently high probability that the information unit is not important, the decision is made that the rest of the information unit should be ignored. The quality information relating to the already received part is thus used, so to speak, to calculate a probability that the information unit is not important.

Furthermore, the terminal according to the invention is preferably operated in the GSM system, and/or the method according to the invention relates to a terminal operated in the GSM system. The information unit is in this case transmitted in a transmission channel for signaling data, in which case information data which are not important are filling data or signaling data which are not required, or are no longer required, in the terminal.

In a first preferred refinement of the present invention, the decision as to whether the information unit is or is not important is made by evaluating the information content of the already received part of the GR 97 P 1506 -6information unit and by comparing this information content with information stored in a memory device in the terminal. Specific parts, for example, bits of the information unit, may in each case be considered in this case, whose information content is defined and, for example, specified the length of the information unit or the format of the information unit.

The first refinement of the present invention is particularly suitable in those cases in which the transmitted data is coded using a coding method in which the wanted bits, for example the signaling bits, influence only a certain, relatively tightly localized, portion, of all the coded bits transmitted. One example of this is the convolutional code used in the GSM system in which one wanted bit influences approximately eight coded bits.

In a second advantageous refinement of the present invention, the already received part of the information unit is compared with information stored in a memory device in the terminal, in order to decide whether the information unit is or is not important. In contrast to the first preferred refinement, no evaluation of the information content of the already received part is carried out in this case. In the memory unit according to the second refinement, the corresponding part of an expected information unit which is not important can, in this case, be stored, for example. Such an information unit which is not important may comprise, for example, filling data. The filling data transmitted by a specific base station in a frame is normally always the same so that a decision can be made by comparing the already received part of the information unit with the corresponding stored part of the expected information unit which is not important.

GR 97 P 1506 7 This second refinement is particularly suitable in those cases in which the transmitted data is coded using a coding method in which the wanted bits influence a very wide range of the coded bits transmitted. One example of this is the fire code used in the GSM system, in which one wanted bit influences up to 80 coded bits. The second refinement is, however, predicated on the expected information unit which is not important being known completely from the start, that is to say being completely specified.

Thus, in a third advantageous refinement of the present invention, a part of a previously received information unit is stored in a temporary memory device in the terminal and is compared with the received part of a current information unit in order to decide whether the current information unit is or is not important. Thus, if an expected information unit or parts thereof which is or are not important is or are not known or specified accurately, a previously received information unit, or a part of it, is stored temporarily. The previously received information unit may in this case have been assessed or identified as not being important after complete reception and complete decoding in the terminal, for example, or it may have become unimportant subsequently. This may relate to repetitions of already received information units which the terminal no longer requires, for example, signaling data which has already been received and evaluated. For example, in GSM systems, base stations transmit requests to set up a connection (paging requests) more than just once, in order to ensure a higher probability of accessibility. If a mobile station has already received and evaluated such a request, then the corresponding information can be stored in the temporary memory, in order to avoid the same data being received once again.

GR 97 P 1506 8 In a fourth preferred refinement of the present invention, the already received part of the information unit contains information as to whether the information unit is or is not important, and the terminal evaluates this information in order to make the appropriate decision. For example, the already received part of the information unit may contain information as to whether the information unit contains filling data or wanted data, for example signaling data. In the GSM system, the so-called stealing flags of some signaling channel other than the FACCH channel are preferably used for this purpose, which in each case make up two bits per data packet. This may be, for example, the CCCH channel (Common Control Channel). Thus, in this refinement, it is possible to decide immediately after detection of the stealing flags whether the information unit is or is not important, and the receiver can be switched off even while the rest of the data packet is being transmitted.

The present invention will be explained in more detail in the following text using preferred exemplary embodiments and with reference to the attached drawing, in which the single Figure 1 shows the design of a terminal according to the invention for digital mobile radio.

As is shown in Figure 1, a terminal according to the invention for digital mobile radio comprises a receiving unit 1 and a decision unit 2, to which a deinterleaver 3 and a channel decoder 4 are connected.

The illustrated elements are arranged in the receiving unit of the terminal in which case, of course, the terminal contains other elements for processing the received data as well as a transmission unit etc., although these are of no further importance to the present invention.

The transmission device, from which the terminal receives data, accordingly comprises, inter alia, a channel coder, an GR 97 P 1506 9 interleaver and a transmission device. The transmission unit may be, for example, a base station, while the terminal according to the invention may be, for example, a mobile station. However, the terminal may also be a base station, while the transmission unit is a mobile station. In the channel coder, the data to be transmitted is coded, for example, by means of a block code or a convolution code, while the coded data received in the terminal are decoded appropriately in the channel decoder 4 there. The data to be transmitted is reorganized and spread in time in the transmitter interleaver in order, if necessary, to distribute errors contained in the data randomly, since most block codes or convolution codes can suppress only statistically independent individual errors. The corresponding reproduction of the order of the received data is carried out in the de-interleaver 3 in the receiving terminal.

The transmission unit transmits the data using the time-division multiplex method, that is to say the data is in each case transmitted in time frames which are subdivided into a specific number of time slots.

Each time slot contains a corresponding data packet. As a rule, the data is transmitted at a number of carrier frequencies which are accessed separately using the time-division multiplex method, so that the transmission takes place by a combination of timedivision multiplex and frequency-division multiplex methods. The receiving device 1 shown in Figure 1 thus receives information units which comprise one or more data packets P1 P2 Pz. Each data packet P1, P2 Pz is in this case transmitted in an associated time slot. The decision device 2 uses an already received part of the information unit to decide, before an information unit comprising one or more data packets Pl, P2 Pz has been received completely, whether the information unit is or is not important. If the decision is that the information unit is not important, the GR 97 P 1506 10 decision device 2 transmits a signal to the receiving unit 1 to ignore the rest of the information unit. The receiving unit 1 then terminates reception of the information unit. Depending on the structure and/or the information content of the data in the information unit and on its error rate, the receiving unit 1 can make the decision as to whether the information unit is or is not important after receiving a number of data packets Pl, P2 Pm, after receiving a single data packet Pl, or even after receiving a part of the first data packet Pl. If the decision device 2 decides that the information unit is not important, then it transmits a signal to the receiving unit 1 to ignore the rest of the information unit, that is to say, for example, the rest of the first data packet P1 or the rest of the data packets Pn Pz which have not yet been received. The signal to ignore the rest of the information unit can, for example, activate a switch or a gate which switches off or deactivates the receiving unit, or changes it to a standby state.

An information unit comprising a plurality of data packets is transmitted, for example, like the signaling data in the GSM system, in a plurality of time frames following one another. In this case, one data packet is transmitted in each time frame to the terminal. The terminal according to the invention may decide even after receiving the first data packet whether the information unit is or is not important. In particular, this is possible if the transmitted data has been subjected to redundant coding, which results in the number of data bits in the information unit being doubled. Since, in this case, the first data packet contains twice the number of data bits, a relatively reliable statement can thus be made even after receiving the first data packet as to whether the entire information unit is or is not important. If transmission errors occur on the transmission channel between the transmitter and the receiving terminal, X then additional data must be received GR 97 P 1506 11 in order to allow a reliable decision to be made. If, for example, signaling data to be transmitted contains four data packets, then, beyond a certain error rate, it is no longer possible to decide on the basis of a single data packet whether the signaling data is or is not important, and it is also necessary to receive the second data packet to allow a reliable statement to be made.

The receiving device 1 contains an equalizer which provides the soft-decision values of the received digital data. The soft-decision values provide quality information about the received digital data, that is to say they allow an assessment to be made on the probability that the transmitted data has been transmitted correctly, or contains errors. The decision device 2 uses these soft-decision values of the already received parts of an information unit to calculate a probability value as to whether the information unit is or is not important. The decision device 2 in this case decides that the information unit is not important if the probability of this is sufficiently high, that is to say if the calculated probability value is above a predetermined probability threshold. This makes it possible to avoid an important information unit not being identified as a result of individual bits being transmitted incorrectly, and to avoid an information unit which is not important not being identified for the same reason.

The present invention will be explained in the following text with reference to preferred exemplary embodiments, in this case referring to a terminal which is operated in the GSM system, and with the information unit being transmitted in a transmission channel for signaling data. In this specific configuration, information units which are not important may be, for example, filling data which are transmitted from a base station to the mobile stations when GR 97 P 1506 12 there is no signaling data to be transmitted on the signaling channel. This is the case, for example, when no call is intended to be transmitted.

Information units which are not important may, however, also contain signaling data which does not relate to the terminal. A base station uses the GSM system to transmit signaling data distributed over four data packets or time slots when a call needs to be transmitted to a mobile station. However, this signaling data is received by all the accessible mobile stations. This signaling data signals to the relevant mobile station that a call is intended to be transmitted. In this case, the transmission of the signaling data lasts for about 15 ms, with each mobile station listening in or being activated every 0.5 to 2 s, in order to check whether it is being called.

However, normally, the signaling data is intended for only a single mobile station, and the other mobile stations are not affected by this. An information unit which is not important thus contains, for example, signaling data which is intended for a different mobile station.

Another possibility for information units which are not important is data which the receiving terminal or mobile station has already received, but which it no longer requires. In the GSM system, these are, for example, call requests (paging requests) which are transmitted several times in succession in order to improve the probability of accessibility. The last case furthermore also relates to the BCCH data (Broadcast Control Channel), in which the configuration of the system is reported to the mobile station. Such data is transmitted in up to eight wanted data packets, and normally changes extremely rarely. However, the mobile station has to receive such data once again every seconds, for the situation where the base station is reconfigured. Data such as this is thus also unimportant data for the GR 97 P 1506 13 purposes of the present invention, once the terminal has received said data and provided it has not changed when transmitted again.

In a first preferred exemplary embodiment, the decision device 2 comprises a memory device having previously stored information, and an evaluation device which evaluates the information content of the already received part of the information unit and compares this information content with the information stored in the memory device, in order to decide whether the information unit is or is not important. The already received data and the stored prior knowledge of the constant bits or relationships between individual bits thus allows those bits, or relationships between bits, to be evaluated, from which it is possible to identify that the information unit is not important for the terminal.

In this case, it is particularly worthwhile to consider in each case one specific fixed part of the data packet in which a specific type of data is always arranged, depending on a specific definition. If, for example in the GSM system, the first byte of a signaling data information unit contains information about the length of the information unit, then the evaluation unit evaluates this length information and compares it with permitted maximum and/or minimum length values which are stored in the memory device. If the evaluated length of the information unit is too short to allow sensible information to be obtained, or if it is longer than the maximum permitted length, then the rest of the information unit can be ignored.

However, the second byte of the data packet, which contains the message format in the GSM system, may also be considered. The evaluation unit then evaluates the message format of the received data and compares GR 97 P 1506 14 it with message format information stored in the memory device, in order to find out whether the message format is of interest to the terminal. If the evaluated data shows that the information unit contains a message which does not relate to the terminal, then the rest of the information unit is ignored. Furthermore, header information defining the expected context in the transmitted data packet can also be investigated, for example layer 2 header, protocol descriptor, etc. The following text quotes one example of an implementation in the GSM system for reception of a filling message in the call request channel (paging message), with the first two bytes representing the part of the filling message which has already been received. The known data is in this case underlined.

01 reserved bits owing to the compatibility with respect to Phase 1 000101-- layer 2 length, where 5 length 22 0110 protocol discriminator 0000---- skip indicator The bits described above are read from right to left, with the two bits in the first line with the value and having been defined as the coding format for Phase 1 of the GSM system, but no longer being required in Phase 2 of the GSM system. In order nevertheless to ensure compatibility between systems operated in Phase 1 and systems operated in Phase 2, these two bits will still continue to be transmitted in the indicated manner even in Phase 2 of the GSM system as well. The second line shows the six bits adjacent to the two in the first line, containing the length information for the layer 2 length. When analyzing the length information in the illustrated example, the underlined sixth bit with the value is used to decide whether the message is or is not important. The two reserved bits shown in the first line, together with the six length bits shown in the second line thus produce GR 97 P 1506 15 the first byte of the already received part of the filling message. The next four bits shown in the third line are the protocol discriminator and are used to activate the corresponding layer in the mobile station.

The last four bits in the second byte, shown in the fourth line, are not yet specified in Phase 2 of the GSM system, and are each reserved for upgrades in Phase 3 and Phase 4. If values other than the "0000" values illustrated here occur, the incoming information unit is ignored.

Since there are a very large number of known bits in the area around the layer 2 length, the layer 2 length can be determined with some remaining uncertainty by means of the coding used in the GSM system: the length is either 5, in which case the information unit can be only a filling message which is ignored by the terminal or the mobile station, or the length is 23, which is an illegal length and the mobile station likewise ignores the information unit. If one or more of the bits which are identified here as being known has or have a value other than that shown here, the information unit is likewise identified by the mobile station as being invalid, and is ignored.

The terminal and the method in the first exemplary embodiment are particularly suitable for data which has been coded using a coding method in which the wanted bits influence only a certain, relatively tightly localized portion of the transmitted coded bits. One example of this is the convolutional codes which are used in the GSM system and have an influence length of about 8, that is to say a wanted data bit influences about 8 coded bits. If the information unit is transmitted in four data packets, then of the eight influenced coded bits, two bits are thus transmitted in the first data packet. The relationship between these two bits then allows a conclusion to be drawn relating to the entire information unit.

GR 97 P 1506 16 In a second preferred exemplary embodiment, the decision device 2 comprises a memory device having previously stored information, and compares the already received part of the information unit with the information stored in the memory device, in order to decide whether the information unit is or is not important. In contrast with the first exemplary embodiment, the information content of the received data is not evaluated in this case.

For example, the memory unit can be used to store a data packet or an information unit having dummy messages, which are always transmitted in a signaling channel by a base station when there is no signaling data to be transmitted. If the previously received part of the information unit matches the corresponding stored part of an expected information unit with dummy data, then it is assumed that the incoming information unit actually contains dummy data. The receiving unit 1 then ignores the rest of the information unit, and terminates reception.

Depending on the coding method, the assumption that an information unit having dummy data has actually arrived is theoretically not necessarily correct.

However, if the probability that an information unit with dummy data is present is sufficiently high, then the procedure is sufficiently reliable. The method according to the second exemplary embodiment corresponds roughly to the comparison of checksums, even if the data being compared is not explicitly checksums. As a rule, the base stations in the GSM system always transmit identical dummy-data data packets, so that the second exemplary embodiment can advantageously be appliedto this field.

GR 97 P 1506 17 The terminal and the method according to the second exemplary embodiment are particularly suitable for data which is coded using coding methods in which the wanted bits influence the transmitted coding bits over a very wide range. One example of this is the fire codes used in the GSM system, in which a checksum is used having an additional capability for error correction, and in which a wanted data bit influences up to 80 coded bits. However, other checksums may also be used in the second exemplary embodiment.

Nonetheless, a precondition in the second exemplary embodiment is that the information previously stored in the memory device is completely known, that is to say completely specified.

In a third exemplary embodiment of the present invention, the decision device 2 comprises a temporary memory unit, in which a part of a previously received information unit is stored and compares the already received part of a current information unit with the part of the previously received information unit stored in the memory device, in order to decide whether the current information unit is or is not important. This is advantageous in particular when parts of the information unit, or the entire information unit, to be stored in the memory device is not defined from the start. Since, for example in the GSM system, the contents of filling data packets are not defined, parts of the filling data packets, or the entire filling data packets which have already been received are stored in the temporary memory device such that changes in the filling data or dummy data can also be considered, for example when changing a base station. As an alternative or in addition, other data packets may also be stored in the temporary memory device, which have previously been received and were not yet unimportant but have become unimportant since, for example, they are no longer required in the terminal, in order to avoid repetitions of the GR 97 P 1506 18 reception of data which has already been received but is no longer relevant.

In a fourth exemplary embodiment of the terminal according to the invention and of the method according to the invention, the already received part of the information unit contains information about whether the information unit is or is not important. In this case, the decision device 2 comprises an evaluation unit, which evaluates this information. This exemplary embodiment is based on the idea of using the first portion of the coded bits of an information unit to make the nature of the information unit identifiable as such even in the first data packet. To do this, for example, dummy data packets and wanted data packets must be defined to be sufficiently different from one another or, possibly, additional data which is not required per se for signaling must be inserted, which is sufficiently different for the dummy data and wanted data packets that the difference can be identified just from the first part of the information unit.

Alternatively, further data may also be attached to the corresponding specified data, to allow a distinction to be drawn at this stage.

In the specific case of the GSM system, it would be possible to carry out the following upgrade.

At the moment, the so-called stealing flags, which each make up two bits per data packet, are not used, inter alia, in the channel CCCH (Common Control Channel). The stealing flags are used exclusively in the FACCH (Fast Associated Control Channel), in order to distinguish between wanted data and signaling data, for example during a handover. Using the CCCH, it is possible to define that the base station is using these stealing flags to signal whether wanted information or dummy or filling data are present. If, after receiving the first data packet, a terminal detects one or both stealing flags, then the data packet does not need to be evaluated any further. This also saves the determination of the other bits in this GR 97 P 1506 19 data packet. In the case of the BCCH data (Broadcast Control Channel), these bits are set when the information has changed within the last 30 seconds, that is to say when it must be read again by all the accessible terminals and mobile stations.

If the terminal has suitably fast data processing, then the receiver can still be switched off during the transmission of the rest of the data packet, even during reception of the first data packet, immediately after the detection of one or both stealing flags in this data packet. This also relates to the first, the second and the third exemplary embodiment, in which the receiver can still be switched off during the transmission of the rest of the first data packet, even immediately after the detection of an already received part of a first data packet of the information unit, by means of appropriately fast data processing.

However, in all the exemplary embodiments, the evaluation of the rest of the first data packet can at least be ended as soon as the decision device has made a decision on the already received part of the information unit and has assessed its importance. This saves a large amount of complexity in the digital signal processing of the equalizer algorithm in the receiving device, and reduces the power consumption.

Claims

1. A terminal for digital mobile radio, having a receiving device for receiving digital data packets and for providing soft-decision values of received data packets, and a decision device which, before complete reception of an information unit which comprises one or more data packets, uses a part of the information unit which has already been received to decide whether the information unit is or is not important and, if the decision is that the information unit is not important, causes the receiving unit to ignore the rest of the information unit, wherein the decision device calculates a probability value from soft- decision values, which are received in the receiving device, of the already received part of the information unit which is a measure of whether the information unit is not important, and decides that the information unit is not important if the calculated probability value is above a predetermined probability threshold. 0 O 0 0 15 2. The terminal for digital mobile radio as claimed in claim 1, wherein the terminal is operated in the GSM system, and the information unit is transmitted in a transmission channel for signaling data, in which case information units which are not important are filling data or signaling data which is not required, or is no longer required, in the terminal. 0 .oo~o oo~o 0000 •4 3. The terminal for digital mobile radio as claimed in claim 1 or 2, wherein the decision device comprises a memory device having previously stored information, and an S* evaluation device which evaluates the information content of the already received part of the information unit, and compares this information content with the information stored in the memory device, in order to decide whether the information unit is or is not important.

4. The terminal for digital mobile radio as claimed in claim 3, wherein the already received part of the information unit contains information about the length of the information unit, in which case the evaluation unit compares this information about the length with permitted maximum and/or minimum length values which are stored in the memory device. The terminal for digital mobile radio as claimed in claim 3, wherein the already Sreceived part of the information unit contains information about the format of the [R:\LIBOO]04914.doc:iad -21 information unit, in which case the evaluation unit compares this information about the format with expected format values which are stored in the memory device.

6. The terminal for digital mobile radio as claimed in claim 1 or 2, wherein the decision device comprises a memory device having previously stored information, and compares the already received part of the information unit with the information stored in the memory device, in order to decide whether the information unit is or is not important.

7. The terminal for digital mobile radio as claimed in claim 6, wherein the information previously stored in the memory device contains a part (which corresponds to the already received part of the information unit) of an expected information unit which is o• not important.

8. The terminal for digital mobile radio as claimed in claim 1 or 2, wherein the 15 decision device comprises a temporary memory device in which a part of a previously received information unit is stored, and compares the already received part of a current information unit with the part of the previously received information unit which is stored o in the memory device, in order to decide whether the current information unit is or is not •c important. 2 0 The terminal for digital mobile radio as claimed in claim 1 or 2, wherein the *.*already received part of the information unit contains information as to whether the S• information unit is or is not important, and the decision device comprises an evaluation unit which evaluates this information in order to decide whether the information unit is or is not important. The terminal for digital mobile radio as claimed in claim 9, wherein the terminal is operated in the GSM system, and the information unit is assigned to a signaling channel other than the FACCH channel, in which case the already received part of the information unit comprises the stealing flags of this signaling channel.

11. A method for evaluating data received in a terminal for digital mobile radio, comprising the steps of receiving digital data packets, providing soft-decision values of received data packets, and [R:\LIBOO]04914.doc:iad 22 using an already received part of an information unit which comprises one or more data packets to decide, before complete reception of the information unit, whether the information unit is or is not important, and ignoring the rest of the information unit if the decision is that the information s unit is not important, wherein the soft-decision values of the previously received part of the information unit are used to calculate a probability value, which is a measure of whether the information unit is not important, and the decision that the information unit is not important is made if the calculated probability values is above a predetermined probability threshold. i0

12. The method for evaluating received data as claimed in claim 11, wherein the terminal is operated in the GSM system and the information unit are transmitted in a go transmission channel for signaling data, in which case information units which are not important are filling data or signaling data which is not required, or is no longer required, in the terminal:

13. The method for evaluating received data as claimed in claim 11 or 12, wherein, before the decision, an evaluation of the information content of the already received part O*O* of the information unit is carried out and, for making the decision as to whether the information unit is or is not important, this information content is compared with information previously stored in the terminal. S• 14. The method for evaluating received data as claimed in claim 13, wherein the already received part of the information unit contains information about the length of the information unit in which case, for making the decision, compares this information about the length with permitted maximum and/or minimum length values which have been previously stored in the terminal. The method for evaluating received data as claimed in claim 13, wherein the already received part of the information unit contains information about the format of the information unit, in which case, for making the decision, this information about the format is compared with expected format values which have previously been stored in the terminal. [R:\LIB00104914.doc:iad -23-

16. The method for evaluating received data as claimed in claim 11 or 12, wherein for making the decision as to whether the infonnrmation unit is or is not important, the already received part of the information unit is compared with information which has previously been stored in the terminal.

17. The method for evaluating received data as claimed in claim 16, wherein the information previously stored in the terminal contains apart (which corresponds to the already received part of the information unit) of an expected information unit which is not important.

18. The method for evaluating received data as claimed in claim 11 or 12, wherein for making the decision as to whether a current information unit is or is not important, the already received part of the current information unit is compared with a part (which has been temporarily stored in the terminal) ofa previously received information unit.

19. The method for evaluating received data as claimed in claim 11 or 12, wherein the already received part of the information unit contains information relating to whether :..the information unit is or is not important, and this information is evaluated for making the decision as to whether the information unit is or is not important. The method for evaluating received data as claimed in claim 19, wherein the terminal is operated in the GSM system, and the information unit is assigned to a *99999 signaling channel other than the FACCH channel, in which case the already received part of the information unit comprises the stealing flags of this signaling channel.

21. A terminal for digital mobile radio, substantially as herein described with reference to Fig. 1.

22. A method for evaluating data received in a terminal for digital mobile radio, substantially as herein described with reference to Fig. 1. DATED this Twelfth Day of October 2000 Siemens Aktiengesellschaft R Patent Attorneys for the Applicant SPRUSON FERGUSON [R:\LIB00]04914.doc:iad