Method and device for the configuration of a transmission link

Abstract

A method and apparatus for data transmission between a transmitter-side data transmission unit and a receiver-side data transmission unit is provided. The method includes transmitting a first portion of a data packet from a real-time application to the receiver-side data transmission unit, receiving a communication channel availability indicator from the receiver-side data transmission unit, and, if the availability indicator shows that the communication channel is available, adjusting the configuration of the remaining data of the data packet to be transmitted within the maximum permissible data transmission time which is still available for the data packet and transmitting the remaining data to the receiver-side data transmission unit. A transmitter-side data transmission unit and a receiver-side data transmission unit configured to execute the data transmission method are also provided.

Claims

1. A method for data transmission at a transmitter-side data transmission unit, comprising the acts of: receiving at the transmitter-side data transmission unit a data transmission request for a data packet initiated by a real-time application operatively connected to the transmitter-side data transmission unit prior to initiating data transfer to a receiver-side data transmission unit; transmitting from the transmitter-side data transmission unit a first portion of the data packet to the receiver-side data transmission unit via a communication channel; receiving at the transmitter-side data transmission unit an availability indicator for the communication channel in the form of an availability code transmitted from the receiver-side data transmission unit, the availability indicator being determined by the receiver-side data transmission unit based on parameters of the communication channel measured during the data packet first portion receiving act, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time; and if the availability indicator indicates the communication channel is available, configuring using the transmitter-side data transmission unit a portion of the data packet not yet transmitted for transmission within an available remainder of a maximum permissible data transmission time determined by the real-time application for the data packet, and transmitting from the transmitter-side data transmission unit the portion of the data packet not yet transmitted to the receiver-side data transmission unit via the communication channel.

2. The method as claimed in claim 1, further comprising the acts of: if the availability indicator indicates that the communication channel is not available, terminating the transmission of the data packet from the transmitter-side data transmission unit; and repeating the transmitting act after a predetermined pause if sufficient time for the transmission of the data packet from the transmitter-side data transmission unit is available within the available remainder of the maximum permissible data transmission time for the data packet.

3. The method as claimed in claim 1, wherein the act of configuring the portion of the data packet not yet transmitted for transmission includes adjusting at least one of a number and a length of data blocks of the data packet not yet transmitted based on an expected number of individual data block transmission repetitions.

4. The method as claimed in claim 2, wherein the act of configuring the portion of the data packet not yet transmitted for transmission includes adjusting at least one of a number and a length of data blocks of the data packet not yet transmitted based on an expected number of individual data block transmission repetitions.

5. The method as claimed in claim 1, further comprising the acts of: if the availability indicator indicates that the communication channel is not available, terminating the transmission of the data packet from the transmitter-side data transmission unit; and after terminating the transmission of the data packet, releasing the communication channel for use by other data transmission units.

6. A method for data transmission at a receiver-side data transmission unit, comprising the acts of: receiving at the receiver-side data transmission unit a first portion of a data packet from a transmitter-side data transmission unit via a communication channel; determining at the receiver-side data transmission unit an availability of the communication channel on the basis of parameters of the communication channel measured during the data packet first portion receiving act, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time; transmitting from the receiver-side data transmission unit an availability indicator based on the determined communication channel availability to the transmitter-side data transmission unit; and if the availability indicator indicates the communication channel is available, receiving the portion of the data packet not yet transmitted from the transmitter-side data transmission unit at the receiver-side data transmission unit via the communication channel.

7. A method for data transmission at a receiver-side data transmission unit, comprising the acts of: receiving at the receiver-side data transmission unit a first portion of a data packet from a transmitter-side data transmission unit via a communication channel; determining at the receiver-side data transmission unit an availability of the communication channel on the basis of parameters of the communication channel measured during the data packet first portion receiving act, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time; transmitting from the receiver-side data transmission unit an availability indicator based on the determined communication channel availability to the transmitter-side data transmission unit; and if the availability indicator indicates the communication channel is available, receiving the portion of the data packet not yet transmitted from the transmitter-side data transmission unit at the receiver-side data transmission unit via the communication channel, wherein in the act of receiving the portion of the data packet not yet transmitted, applying an adapted data block size determined by the receiver-side data transmission unit by calculating a value for an accumulated mutual information content after each transmission repetition of a data block of the data packet, comparing the calculated accumulated mutual information content value with an accumulated mutual information content value based on the parameters for the communication channel, and transmitting the adapted data block size from the receiver-side data transmission unit to the transmitter-side data transmission unit; adjusting a data block size of data blocks of the portion of the data packet not yet transmitted from the transmitter-side data transmission unit such that a difference between the calculated accumulated mutual information content value and the estimated accumulated mutual information content value is reduced.

8. A transmitter-side data transmission unit configured to transmit a data packet from a real-time application via a communication channel to a receiver-side data transmission unit, comprising: at least one transmitter-side data output/reception unit; and at least one availability determination unit configured to determine an availability of the communication channel between the at least one transmitter-side data output/reception unit and at least one receiver-side data transmission unit based on parameters of the communication channel measured during transmission of a first portion of the data packet, wherein the at least one transmitter-side data output/reception unit is configured to receive a data transmission request for the data packet from the real-time application operatively connected to the transmitter-side data transmission unit; transmit the first portion of the data packet from the transmitter-side data transmission unit to the receiver-side data transmission unit via the communication channel; receive at the transmitter-side data transmission unit an availability indicator for the communication channel from the receiver-side data transmission unit; and if the at least one availability determination unit determines the communication channel is available, configure a portion of the data packet not yet transmitted for transmission within an available remainder of a maximum permissible data transmission time determined by the real-time application for the data packet, and transmit the portion of the data packet not yet transmitted from the at least one data output/reception unit to the receiver-side data transmission unit via the communication channel.

9. The transmitter-side data transmission unit as claimed in claim 8, wherein if the at least one availability determination unit determines that the communication channel is not available, the at least one transmitter-side data output/reception unit is configured to terminate the transmission of the data packet from the transmitter-side data transmission unit and repeat the transmitting act after a predetermined pause if sufficient time for the transmission of the data packet from the transmitter-side data transmission unit is available within the available remainder of the maximum permissible data transmission time for the data packet.

10. The transmitter-side data transmission unit as claimed in claim 8, wherein the at least one transmitter-side data output/reception unit adjusts the portion of the data packet not yet transmitted for transmission by adjusting a number and length of data blocks of the data packet not yet transmitted based on an expected number of individual data block transmission repetitions.

11. The transmitter-side data transmission unit as claimed in claim 9, wherein the at least one transmitter-side data output/reception unit configures the portion of the data packet not yet transmitted for transmission by adjusting a number and length of data blocks of the data packet not yet transmitted based on an expected number of individual data block transmission repetitions.

12. The transmitter-side data transmission unit as claimed in claim 8, wherein if the at least one availability determination unit determines that the communication channel is not available, the at least one transmitter-side data output/reception unit is configured to terminate the transmission of the data packet from the transmitter-side data transmission unit and after terminating the transmission of the data packet, release the communication channel for use by other data transmission units.

13. A receiver-side data transmission unit configured to receive a data packet from a real-time application transmitted by a transmitter-side data transmission unit via a communication channel, comprising: at least one receiver-side data output/reception unit; and at least one availability determination unit configured to determine an availability of the communication channel between the at least one receiver-side data output/reception unit and at least one transmitter-side data transmission unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, wherein the at least one receiver-side data output/reception unit is configured to receive a first portion of the data packet from the at least one transmitter-side data transmission unit via the communication channel; transmit an availability indicator based on the determined communication channel availability to the transmitter-side data transmission unit, the availability indicator being determined by the at least one availability determination unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time, and if the availability indicator indicates the communication channel is available, receiving the portion of the data packet not yet transmitted from the transmitter-side data transmission unit via the communication channel.

14. A receiver-side data transmission unit configured to receive a data packet from a real-time application transmitted by a transmitter-side data transmission unit via a communication channel, comprising: at least one receiver-side data output/reception unit; and at least one availability determination unit configured to determine an availability of the communication channel between the at least one receiver-side data output/reception unit and at least one transmitter-side data transmission unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, wherein the at least one receiver-side data output/reception unit is configured to receive a first portion of the data packet from the at least one transmitter-side data transmission unit via the communication channel; transmit an availability indicator based on the determined communication channel availability to the transmitter-side data transmission unit, the availability indicator being determined by the at least one availability determination unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time, if the availability indicator indicates the communication channel is available, receive the portion of the data packet not yet transmitted from the transmitter-side data transmission unit via the communication channel, and in the receiving of the portion of the data packet not yet transmitted from the transmitter-side data transmission unit, the at least one receiver-side data output/reception unit is further configured to cooperate with the transmitter-side data transmission unit to apply an adapted data block size determined by calculating a value for an accumulated mutual information content after each transmission repetition of a data block of the data packet, comparing the calculated accumulated mutual information content value with an accumulated mutual information content value based on the parameters for the communication channel, transmitting the adapted data block size from the receiver-side data transmission unit to the transmitter-side data transmission unit, and adjusting a data block size of data blocks of the portion of the data packet not yet transmitted from the transmitter-side data transmission unit such that a difference between the calculated accumulated mutual information content value and the estimated accumulated mutual information content value is reduced.

15. A data communication system comprising: a transmitter-side data transmission unit configured to transmit a data packet from a real-time application via a communication channel to a receiver-side data transmission unit; and the receiver-side data transmission unit configured to receive the data packet from the transmitter-side data transmission unit via the communication channel; wherein the transmitter-side data transmission unit includes at least one transmitter-side data output/reception unit; and at least one transmitter-side availability determination unit; and the receiver-side data transmission unit includes at least one receiver-side data output/reception unit; and at least one receiver-side availability determination unit; the at least one transmitter-side data output/reception unit is configured to receive a data transmission request for the data packet from the real-time application operatively connected to the transmitter-side data transmission unit; transmit a first portion of the data packet from the transmitter-side data transmission unit to the receiver-side data transmission unit via the communication channel; receive at the transmitter-side data transmission unit an availability indicator for the communication channel from the receiver-side data transmission unit; and if the at least one transmitter-side availability determination unit determines the communication channel is available, configure a portion of the data packet not yet transmitted for transmission within an available remainder of a maximum permissible data transmission time determined by the real-time application for the data packet, and transmit the portion of the data packet not yet transmitted from the at least one data output/reception unit to the receiver-side data transmission unit via the communication channel, and the at least one receiver-side data output/reception unit is configured to receive the first portion of the data packet from the at least one transmitter-side data transmission unit via the communication channel; transmit the availability indicator based on the determined communication channel availability to the transmitter-side data transmission unit, the availability indicator being determined by the at least one receiver-side availability determination unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, and estimated parameters of the communication channel for the portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within the available remainder of the maximum permissible data transmission time, and if the availability indicator indicates the communication channel is available, receiving the portion of the data packet not yet transmitted from the transmitter-side data transmission unit via the communication channel.

16. A vehicle, comprising: a transmitter-side data transmission unit configured to transmit a data packet from a real-time application via a communication channel to a receiver-side data transmission unit, the transmitter-side data transmission unit including: at least one transmitter-side data output/reception unit; and at least one availability determination unit configured to determine an availability of the communication channel between the at least one transmitter-side data output/reception unit and at least one receiver-side data transmission unit based on parameters of the communication channel measured during transmission of a first portion of the data packet, wherein the at least one transmitter-side data output/reception unit is configured to receive a data transmission request for the data packet from the real-time application operatively connected to the transmitter-side data transmission unit; transmit the first portion of the data packet from the transmitter-side data transmission unit to the receiver-side data transmission unit via the communication channel; receive at the transmitter-side data transmission unit an availability indicator for the communication channel in the form of an availability code from the receiver-side data transmission unit; and if the at least one availability determination unit determines the communication channel is available, configure a portion of the data packet not yet transmitted for transmission within an available remainder of a maximum permissible data transmission time determined by the real-time application for the data packet, and transmit the portion of the data packet not yet transmitted from the at least one data output/reception unit to the receiver-side data transmission unit via the communication channel; and a vehicle processor configured to execute the real-time application.

17. The vehicle as claimed in claim 16, wherein the real-time application is a driver-assistance functionality.

18. A vehicle, comprising: a receiver-side data transmission unit configured to receive a data packet from a real-time application transmitted by a transmitter-side data transmission unit via a communication channel, comprising: at least one receiver-side data output/reception unit; and at least one availability determination unit configured to determine an availability of the communication channel between the at least one receiver-side data output/reception unit and at least one transmitter-side data transmission unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, wherein the at least one receiver-side data output/reception unit is configured to receive a first portion of the data packet from the at least one transmitter-side data transmission unit via the communication channel; transmit an availability indicator in the form of an availability code based on the determined communication channel availability to the transmitter-side data transmission unit, the availability indicator being determined by the at least one availability determination unit based on parameters of the communication channel measured during the receiving of the first portion of the data packet, and estimated parameters of the communication channel for a portion of the data packet not yet transmitted from the transmitter-side data transmission unit to the receiver-side data transmission unit within an available remainder of a maximum permissible data transmission time, and if the availability indicator indicates the communication channel is available, receiving the portion of the data packet not yet transmitted from the transmitter-side data transmission unit via the communication channel; and a vehicle processor configured to execute the real-time application.

19. The vehicle as claimed in claim 18, wherein the real-time application is a driver-assistance functionality.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates diagrammatical a data transmission method between two data transmission units via a communication channel in accordance with an embodiment of the present invention.

(2) FIG. 2 shows three sequence examples of the data transmission method of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 shows a first data transmission unit 10 and a second data transmission unit 10, which provide a communication channel 15 for data transmission between a transmitter-side real-time application 20 and a receiver-side real-time application 20.

(4) Real-time applications 20, 20 may for example each be a vehicle safety application, such as for example a brake assist of a driver assistance system. First and second data transmission unit 10, 10 are than respectively located in an associated first and second vehicle. In other words, real-time applications 20, 20 may implement identical or complementary functions.

(5) The real-time application may however also be a client real-time application 20 in a driver information system of a vehicle, which communicates via a data link with a host real-time application 20 on a back-end server. Second data transmission unit 10 is then located in an associated vehicle and first data transmission unit 10 for example in a base station of a radio communication network or mobile communication network, such as for example the latest 3GPP LTE mobile communication network. A service which informs subscribers about the present traffic situation (traffic density, traffic jams etc.) may run for example as host real-time application 20 on the back-end server. In the case of client real-time application 20, it may then for example be a navigation system of the vehicle, which graphically displays the current traffic situation to the driver or takes account of the information concerning the present traffic situation in the navigation. In other words, client real-time application 20 consumes the service that is provided by host real-time application 20. A client-server relationship thus exists between real-time applications 20, 20.

(6) First and second data transmission unit 10, 10 comprises in each case a data output/data reception unit 30, 30 and in each case an availability determination unit 40, 40. Availability determination units 40, 40 each serve to determine the availability of communication channel 15 between data transmission units 10, 10put more precisely, between data output/data reception units 30, 30, which are each connected to associated real-time application 20, 20.

(7) The embodiments for data transmission units 10, 10 represented in FIG. 1 are identically constituted data transmission units. That is to say that both first and second data transmission unit 10, 10 may each function as a transmitting as well as a receiving data unit.

(8) For the sake of simplification and on account of the identical design, the design of data transmission units 10, 10 is described below solely on the basis of the example of first data transmission unit 10. Thus, an availability output unit 41 is further provided as part of availability determination unit 40, which availability output unit is configured for outputting an availability indicator for communication channel 15. The availability indicator may be obtained from real-time application 20 by a data transmission request unit 42.

(9) Data output/data reception unit 30 is configured to transmit data packets reliably within a fixed time window (as maximum permissible data transmission time) via communication channel 15. For this purpose, availability determination unit 40 determines, in the interaction with receiver-side availability determination unit 40 yet to be explained, the availability of communication channel 15. The determined availability indicator may be transmitted with the aid of availability output unit 41 to real-time application 20.

(10) Within the scope of the data transmission method proposed here, a data transmission request from real-time application 20 is received in a first step by data transmission unit 10. Availability determination unit 40 then determines the availability of communication channel 15. As part of the data transmission request, information concerning the amount of data and/or the maximum permissible data transmission time and/or the maximum permissible transmission error rate may be transmitted by real-time application 20 as reliability requirements to data transmission unit 10, in particular to availability determination unit 40.

(11) Availability determination unit 40 determines, taking account of the communicated reliability requirements for the data to be transmitted, the availability of communication channel 15.

(12) The availability may then be transmitted to real-time application 20 with the aid of availability output unit 41. Availability determination unit 40 essentially establishes whether the data transmission request by real-time application 20 can be granted because the requested data transmission can be carried out with the required reliability.

(13) The availability of communication channel 15 is indicated for example by the availability indicator, which may assume a binary value AI, wherein the value AI=1 describes that communication channel 15 may be made available with the required reliability. The output of the value AI=0, on the other hand, indicates that communication channel 15 cannot be made available with the required reliability.

(14) In the described embodiment, real-time application 20 wants to communicate with real-time application 20 with specific reliability requirements via a communication channel 15. Real-time application 20 wants for example to transmit specific information to real-time application 20. Real-time application 20 may also transmit information to real-time application 20. For example, it is possible for real-time application 20 to request data cyclically from real-time application 20 using data transmission unit 10.

(15) The methods for data transmission proposed here are explained below by way of example on the assumption that first data transmission unit 10 as a transmitter wants to transmit data to second data transmission unit 10. With regard to the examples in FIG. 2, the corresponding reference numbers of FIG. 2 are used below for a better understanding.

(16) In the first place (step a), first data transmission unit 10 receives a data transmission request for a data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 from real-time application 20 operatively connected to data transmission unit 10. Then (step b), data output/data reception unit 30 transmits, under control of availability determination unit 40, a first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 to receiver-side second data transmission unit 10 via communication channel 15.

(17) First of all (step i), first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 is received at second data transmission unit 10 with second data output/data reception unit 30 there, said first portion having been transmitted via communication channel 15 by transmitter-side first data transmission unit 10. Then (step ii), second availability determination unit 40 of second data transmission unit 10 determines the availability of communication channel 15 on the basis of parameters of communication channel 15 measured during the reception of first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 and on the basis of estimated parameters of communication channel 15 for the still available remainder of a predetermined maximum permissible data transmission time T for the transmission of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33. Thereafter (step iii), second availability determination unit 40 transmits an availability indicator AI for indicating the availability of communication channel 15 to transmitter-side first data transmission unit 10 via second data output/data reception unit 30 and first data output/data reception unit 30 of first data transmission unit 10 to first availability determination unit 40.

(18) The determination of the availability of communication channel 15 by second availability determination unit 40 may take place inter alia depending on parameters of communication channel 15. Communication channel parameters suitable for this are for example one or more of the following: an ACK statistic, a NACK statistic, an SINR value, transmission fluctuation values of the communication channel in a defined time range, the coherence time of the communication channel, an amount of an intercarrier interference in an orthogonal frequency multiplex system (OFDM), a Doppler frequency, a CQI value, an RSSI value, an RSRQ value, an RSCP value, a MIMO-Rank value, an Ec/Io value, a QCI value. For the monitoring and/or determination of an optional number of these stated parameters, data transmission units 10, 10 and/or availability determination units 40, 40 each comprise a corresponding communication channel parameter unit 50, 50.

(19) At first data transmission unit 10, availability indicator AI for communication channel 15 is then (step c) received by data output/data reception unit 30 from receiver-side second data transmission unit 10.

(20) Now (step d), under the control of first availability determination unit 40, if availability indicator AI shows that communication channel 15 is available, first data output/data reception unit 30 is configured for data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 for a successful transmission within the still available remainder of maximum permissible data transmission time T of the data of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 yet to be transmitted, said maximum permissible data transmission time being determined by real-time application 20 or 20. The rest of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 is then transmitted by first data output/data reception unit 30 to second data output/data reception unit 30. There (step iv), the rest of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 is duly received by second data output/data reception unit 30.

(21) The configuration of first data output/data reception unit 30 for the transmission of the data of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 yet to be transmitted preferably includes an adjustment of the number and length of data blocks of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 yet to be transmitted taking account of transmission repetitions of individual data blocks that are to be expected.

(22) In step a), information concerning the amount of data and/or maximum permissible data transmission time T and/or a maximum permissible transmission error rate is communicated by real-time application 20 to transmitter-side first data transmission unit 10. This information can also be transmitted to receiver-side second data transmission unit 10 with the one first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33. Alternatively or in addition, this information can also already be pre-configured in transmitter-side first or receiver-side second data transmission unit 10 or respectively 10. It is also possible for this information to be stored at a central point in the communication system, e.g. on a central server, and for it to be able to be retrieved from there by data transmission units 10, 10.

(23) The transmission of first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 serves as a basis for the receiver-side prediction of the availability of communication channel 15 for the transmission horizon still available. The still remaining transmission horizon is determined as the difference arising from required maximum permissible data transmission time T for data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 less the time interval for one or if applicable more (still to be explained in connection with FIG. 2) transmissions of first portion .sub.1, .sub.2, .sub.3 that have already taken place within maximum permissible data transmission time T.

(24) The length of first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 is determined for example by specifying or setting a specific number of information symbols and/or timeslots.

(25) During the transmission of first portion .sub.1, .sub.2, .sub.3 of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33, parameters of communication channel 15 are measured at receiver-side data transmission unit 10. The measured parameters, in particular their time variance, function as a basis for the prediction of the availability of communication channel 15 in respect of transmission horizon T still available. First portion .sub.1, .sub.2, .sub.3 is preferably set short in the case of very rapidly fluctuating parameters of communication channel 15. First portion .sub.1, .sub.2, .sub.3 is preferably set long in the case of slowly fluctuating parameters of communication channel 15. The length of the first portion is preferably determined on the basis of the coherence time of communication channel 15.

(26) When availability indicator AI shows that communication channel 15according to the required reliability requirements of real-time applications 20, 20is not available, transmitter-side first data transmission unit 10 is preferably configured to terminate the current transmission of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 (step e).

(27) After a predetermined pause , transmitter-side first data transmission unit 10 is preferably further configured to repeat the method from step b), if sufficient time is still available for a transmission of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 up to the lapse of maximum permissible data transmission time T for data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33. That is to say that transmitter-side first data transmission unit 10 attempts in this embodiment as long as a transmission of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 within maximum permissible data transmission time T is still possible with available communication channel 15.

(28) In an alternative embodiment, transmitter-side first data transmission unit 10 is configured, if availability indicator AI shows that communication channel 15 is not available (AI=0), to terminate the data transmission link to the associated receiver-side second data transmission units 10 and to release assigned communication channel 15 for use by other data transmission units.

(29) In a another embodiment, the receiver-side second data transmission unit 10 is configured in step iv) to calculate a value for the accumulated mutual information content (accumulated mutual information), ACMI, after each transmission repetition of a data block of data packet T.sub.11, T.sub.21, T.sub.22, T.sub.23, T.sub.31, T.sub.32, T.sub.33 to be transmitted and to compare the calculated ACMI value with an ACMI value which has been calculated on the basis of estimated parameters for communication channel 15. On the basis of the comparison, receiver-side second data transmission unit 10 then transmits an adapted data block size to transmitter-side first data transmission unit 10, which then uses this value for the configuration of the data blocks. Deviations between the calculated ACMI value and the estimated ACMI value may thus be compensated for.

(30) Finally, the data transmission between data transmission units 10 and 10 proposed here is illustrated in FIG. 1 on the basis of three different cases in FIG. 2.

Example 1

(31) At time t.sub.i in first time interval [t.sub.0, t.sub.0+T], a data packet m.sub.1 is ready for transmission at first data transmission unit 10. During the transmission of first portion .sub.1 (sub-frame) of coded data packet .sub.11, it would ascertained at receiver-side data transmission unit 10 that communication channel 15 is not sufficiently reliable. Receiver-side data transmission unit 10 thus transmits to receiver-side data transmission unit 10 availability indicator AI=0, which shows that communication channel 15 is not available. After a predetermined pause with timeslots, transmitter-side data transmission unit 10 attempts to re-transmit data packet .sub.11. During the second attempt, transmitter-side data transmission unit 10 ascertains that communication channel 15 is sufficiently reliably available for the time interval required for the transmission of the data packet within the permissible maximum transmission time and communicates this to transmitter-side data transmission unit 10 by means of availability indicator AI=1. The data transmission is then prefixed up to the end of data block .sub.11.

Example 2

(32) At the time of the transmission of data packet m.sub.2 in second time interval [t.sub.0+T, t.sub.0+2T], communication channel 15 is shown as reliable by receiver-side data transmission unit 10 by availability indicator AI=1 of transmitter-side data transmission unit 10. Accordingly, three data packets .sub.21, .sub.22 and .sub.23 are transmitted up to the lapse of maximum transmission time T. As already mentioned, the size of data packets .sub.21, .sub.22 and .sub.23 is set according to the properties of communication channel 15 and the remaining time up to the end of maximum transmission time T.

Example 3

(33) The transmission of data packet m.sub.3 in third time interval [t.sub.0+2T, t.sub.0+3T] differs from the two preceding examples 1 and 2 solely in that, on account of the non-availability of communication channel 15 in the first transmission attempt, the total data transmission has been delayed by predetermined pause .

(34) Finally, it should be noted that the data transmission in each of the time intervals in FIG. 2 may belong to the same subscriber or to different subscribers within the service area of a base station of the cellular radio communication network. In the latter case, first data packet m.sub.1 may be intended for a first subscriber, second data packet m.sub.2 for a second subscriber, and so forth.

(35) Furthermore, maximum permissible transmission time T does not necessarily have to be constant, but rather can be different in different time intervals. For example, the data transmission of the first subscriber may require as a reliability requirement a maximum transmission time T.sub.1, whereas the data transmission of the second subscriber requires as a reliability requirement a maximum transmission time T.sub.2, wherein T.sub.1T.sub.2 applies. Finally, it is possible, once communication channel 15 has been classified as not available for a specific subscriber on the basis of the reliability requirements (AI=0), to assign communication channel 15 as a radio resource during pause to other subscribers for whom the channel is classified as available (AI=1). The capacity of the entire communication system may thus be improved.

(36) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.