EP1621037A2

EP1621037A2 - Data transmission method

Info

Publication number: EP1621037A2
Application number: EP04728573A
Authority: EP
Inventors: Martin DÖTTLING; Bernhard Raaf
Original assignee: Siemens AG; Nokia Siemens Networks GmbH and Co KG
Current assignee: Nokia Solutions and Networks GmbH and Co KG
Priority date: 2003-05-06
Filing date: 2004-04-21
Publication date: 2006-02-01
Also published as: US7593363B2; WO2004100589A3; WO2004100589A2; US20060285558A1

Abstract

The invention relates to a method for transmitting data via a data transmission channel (CH2) in a communications network (CN). Said transmission channel is made available for the wireless transmission between a transmitter (S) and a receiver (R). The inventive method is characterized in that data transmission is carried out while taking into consideration the channel quality in such a manner that the channel quality data available during transmission are as current as possible and no unnecessary transmission of channel quality data is required.

Description

description

Data transmission method

The invention relates to a method for data transmission via a data transmission channel in a communication network, which is made available between a transmitter and a receiver via a radio link.

The performance of a data transmission from a transmitter to a receiver depends to a large extent on the fact that current information regarding the transmission quality of the data transmission channel used is available at the transmitter at the right time. Only then can the sender adapt transmission parameters for the data to be transmitted to the current situation in order to achieve satisfactory transmission results. The transmission parameters are, for example, transmission power or modulation or coding scheme. The current information regarding the transmission quality is obtained from so-called "channel measurements" or "channel estimates".

The problem is described below using an example from the UMTS standard (UMTS: Universal Mobile Telecommunications System). For clarification of terms, please refer to the description of the figures.

For UMTS, packet-wise high-speed data transmission for a shared channel has been proposed, the so-called HSDPA (Highspeed Downlink Packet Access). The receiver is a terminal, the transmitter a base station. This HSDPA standard sees slow signaling of control information by higher layers of the OSI Layer model before (0SI: Open System Interconnection), which control the channel measurements for HSDPA. The control information for these channel measurements is primarily the time rate of the measurements, the time offset (shift) with respect to a reference and the number of repetitions when a measurement value is transmitted. This means that after a radio connection or "radio link" is established, measurements are carried out at a fixed rate, regardless of whether and when data is actually being sent on the HSDSCH (High Speed Downlink Shared Channel) common downlink connection data channel set up for HSDPA. Therefore, on the one hand, many unnecessary measurements are carried out, on the other hand, at the time of an actual packet data transmission, the so-called "packet call", no current measurement is available. A packet data transmission can consist of several individual packet calls, each of which can consist of several individual data packets.

To remedy this, it has previously been proposed to take additional information about the state of the radio channel from the power control. However, this is not possible in the event that the terminal is in the so-called soft transfer mode or "soft handover", since there are problems with the power regulation. "Soft handover" means a state in which a terminal is connected to several base stations. The power is regulated in such a way that the mobile station or the terminal can correctly receive the transmitted data with the aid of the received signals from all base stations. In general, however, this does not mean that the terminal correctly receives the signal of the specific base station that sends the HSDPA data. Because the HSDPA only send data packets from this one base station sent to the mobile station, the power control optimized for a set of base stations does not provide satisfactory additional information. Therefore, the following suggestions have been made to solve the problem of current channel information data:

1. A so-called activity-based channel quality information (CQI) feedback. The rate of the cyclical measurements is then increased as soon as it is determined at the terminal or terminal that data is being sent. In the case of a packet data transmission in accordance with HSDPA, it is possible, in particular, with each confirmation that a received packet could be decoded or not an additional channel information message CQI can be sent. This feedback can be, for example, a so-called "ACK" (acknowledgment) or "NAK" ("no acknowledgment"). Since there is a delay between the determination of data activity at the terminal, the implementation and transmission of the measurement and the reception and evaluation of the measurement in the transmitter, i.e. the base station, this disadvantageously results in the first packets without current channel information message or channel measurement for each packet data transmission must be transferred. Furthermore, an unnecessarily large number of channel information messages may be sent during an active data transmission due to the increased transmission rate for the channel information message, as a result of which interference in the upward direction is unnecessarily generated.

2. Another possibility is to send an additional channel information message after receiving a NAK.

The same disadvantages as described above occur here. 3. As a further option, it has been proposed to specifically request a channel information message. This solves the problem of missing up-to-date information at the start of a data transfer, but the explicit signaling on the HS-SCCH, the control channel for HSDPA, leads to an additional allocation of resources in the downward direction. It is also disadvantageous that the explicit request process results in a delayed first transmission of the first packet of a packet data transmission.

4 Another method is that the terminal sends an additional channel information message if and when the terminal determines, for example during decoding, that the coding or modulation scheme currently being used is too good or too bad. For data connections that are already active, this method ensures that channel information messages are sent exactly when and when they are required. A disadvantage of this, however, is that the receiver of these channel information messages, that is to say the base station in the case of HSDPA, does not know the times at which the channel information messages were sent. This makes the detection and decoding of these messages difficult.

In summary, the common disadvantage of all of these methods is that current channel information is not available at the same time and work is conserved in terms of resources.

Proceeding from this prior art, it is the object of the present invention to specify a method for data transmission in which current channel quality information is ensured with minimized resource allocation. This object is achieved by a method according to claims 1, 4 and 5, further by a terminal according to claim 18, a base station according to claim 19 and a communication network according to claim 20.

Advantageous further developments can be found in the dependent claims.

The invention is based on the idea that the channel quality information that is as up to date as possible is available at the transmitter without channel quality information having been transmitted unnecessarily.

In a first alternative, a wireless data transmission channel is provided in a method for wireless data transmission between a transmitter and a receiver in a communication system. So that the transmitter can send the data adapted to the current channel quality of the data transmission channel, the receiver repeatedly transmits channel quality information to the transmitter. The receiver or the sender determines an activity state of the data transmission, for example whether data is currently being transmitted or whose transmission is being signaled or whether no data is being transmitted and no arrival of data is being signaled. Furthermore, the time interval to a previous transmission is determined.

If this time interval exceeds a certain first time interval and at the same time there is a certain activity state, in particular the beginning or the presence of a data transmission, the receiver transmits a channel information message to the receiver. Exceeding the first time interval to another transmission ensures that unnecessarily many channel information messages are not transmitted. Furthermore, such a method also has the advantage that the time at which further channel quality information is transmitted and thus arrives at the transmitter is at least approximately known to the transmitter, since this time correlates with an action by the transmitter, namely, for example, the start of data transmission.

In the first alternative, the first time interval represents a maximum interval, beyond which further channel quality information is transmitted.

As an alternative to specifying a minimum time interval, it can be stipulated that the further channel quality information is only transmitted when the defined activity status has already occurred n times. This has the advantage that the number of transmitted channel quality information is adapted to whether data transmissions can take place or not.

Another alternative is to time the transmission to ensure that there are no collisions between individual transmissions of channel quality information.

Even in this way, the number of transmitted messages with channel quality information can be reduced in a manner adapted to the transmission situation. Furthermore, this alternative has the

Advantage that no minimum time interval has to be determined or determined. The data transmission can take place in particular in packets or discontinuously in the case of a circuit-switched connection. With such data transmissions, the quality can easily be adjusted gradually.

According to an advantageous embodiment, the communication network can be a mobile radio network, in particular according to the UMTS standard. The transmitter can be a fixed base station and the receiver can be a mobile terminal. In particular, such a data transmission method can be used with HSDPA.

The terminal can also represent the transmitter and the base station the receiver. This data transmission method can then be used in particular for high-speed transmission in the upward direction from the terminal to the base station, for example HSUPA (High Speed Uplink Packet Access) or EUDCH (Enhanced Uplink Dedicated CHannel).

In order to adapt the transmission to the activity status of the data transmission, the first time interval can be determined depending on the activity status. In particular, different activity states are provided for the start of a data transmission and an ongoing data transmission and no "active" data transmission. Active means here that not only control data but also user data is transmitted.

If no active data connection is provided, a certain first time interval is selected. This first time interval can then be reduced at the start of a data transmission, so that current channel quality information is initially available at the transmitter. If the data transmission is then in progress, this first time interval can be increased in order to be increased again to the even larger value mentioned at the beginning after the data transmission.

In particular, repeated, in particular cyclical, transmission of channel quality information can be provided at certain points in time, to which further measurements defined by the above conditions are added. The point in time for these repeated, in particular cyclical, measurements can be predetermined by the communication network, as a result of which unnecessary interference between receivers, in particular terminals, can be avoided.

In an advantageous embodiment, if the time interval to the previous transmission exceeds the first time interval, the time interval to a subsequent transmission whose time is already known, that is to say transmissions at predetermined times, is determined. Only if this time interval also exceeds a specified second time interval is a further transmission of channel quality information carried out.

This second time interval can also be determined depending on the activity status of the data transmission.

A wireless data transmission channel can be formed by a radio connection or an optical transmission.

The invention further relates to a terminal and a base station and a communication network with which or by which this method is carried out. The invention is explained below using examples, some of which are also shown in the figures:

Figure 1 shows the schematic relationship between transmitter, receiver and network;

FIG. 2 shows the timing of transmissions of the channel quality information and data transmission;

Figure 3 shows the timing of signaling at HSDPA.

FIG. 4 shows the timing of the transmission of channel quality information when only every nth channel quality information is transmitted.

Before a detailed representation of the figures is used, the terms used should first be clarified:

A communication system or communication network is a structure for exchanging data. This can be, for example, a cellular mobile radio network, such as the GSM network (Global System of Mobile Communications) or the UMTS network (Universal Mobile Telecommunications System). A communication network comprises at least two connection nodes, so that so-called "point to point" connections also fall under this term.

Terminals and base stations are generally provided in a communication system and connect to one another via a radio interface. In UMTS, the communi- cation system or radio transmission network at least base stations, here also called NodeB, and radio network control units or radio network controller (RNC) for connecting the individual base stations. The terrestrial radio access network or "Universal Terrestrial Radio Access Network" UTRAN is the radio-technical part of a UMTS network in which, for example, the radio interface is also made available. A radio interface is always standardized and defines the entirety of the physical and protocol specifications for data exchange, for example the modulation process, the bandwidth, the frequency swing, access procedures, security procedures or switching techniques. The UTRAN thus comprises at least base stations and at least one RNC. A base station is a central unit in a communication network which, in the case of a cellular mobile radio network, serves terminals or communication terminals within a cell of the mobile radio network via one or more radio channels. The base station provides the air interface between the base station and the terminal. It handles the handling of radio operations with the mobile participants and monitors the physical radio connection. It also transmits the user and status messages to the terminals. The base station has no switching function, but only a supply function. A base station comprises at least one transmitting / receiving unit.

A terminal can be any communication terminal via which a user communicates in a communication system. There are, for example, mobile radio terminals such as mobile telephones or portable computers with a radio module. A terminal is often also referred to as a "mobile station" (MS) or in UMTS "user equipment" (UE). In mobile communications, a distinction is made between two connection directions. The downlink or "downlink" (DL) denotes the direction of transmission from the base station to the terminal. The uplink or "uplink" (UL) denotes the opposite direction of transmission from the terminal to the base station.

In broadband transmission systems, such as a UMTS mobile radio network, a channel is a sub-area of one

Total transfer capacity available. In the context of this application, a wireless communication path is referred to as a radio channel.

In a mobile radio system, for example UMTS, there are two types of physical channels for the transmission of data: permanently assigned channels or "dedicated channels" and shared or "common channels". With dedicated channels, a physical resource is reserved only for the transmission of information for a specific terminal. The common channels can transmit information that is intended for all terminals, for example the primary common physical control channel or "Primary Common Control Physical Channel" (P-CCPCH) in the downlink, or all terminals share a physical resource. This is the case with the HS-PDSCH, via which data is sent to a terminal depending on the connection quality to the terminal.

In mobile radio systems such as UMTS, in addition to circuit-switched or “circuit switched” services, in which a connection is permanently allocated over their duration, packet-oriented or “packet switched” services are also provided hen. Circuit-switched services can also be carried out discontinuously.

1 shows a transmitter S and a receiver R in a communication system CN. The transmitter S sends data to the receiver R via a first channel connection CH1. The receiver R can send data to the transmitter S via a second channel connection CH2.

The transmitter S can be a base station, for example, the receiver R a terminal. The communication network system can be a system according to UMTS, GSM or other standards, for example. The first channel connection CH1 can comprise several channels, for example a data transmission channel for the transmission of useful data or “load bits” and a control channel for the transmission of control information. The second channel connection CH2 can comprise only one control channel or, like the first channel connection CH1, can also consist of a control channel and a data transmission channel.

For the transmission of user data via the data transmission channel of the first channel connection CH1 from the transmitter to the receiver, it is important that the channel quality of this data transmission channel is known. For this purpose, the receiver, for example the terminal, determines a channel quality information or "channel quality information" CQI from data of the first channel connection.

The receiver R can also determine this channel quality information from data from general control channels. In the case of HSDPA, this would be, for example, the general pilot channel CPICH (Common Pilot Channel). This channel quality information or “channel quality information” CQI is transmitted from the receiver R to the transmitter S, for example via the control channel of the second channel connection CH2.

Now it is important for the data transmission via the first channel connection that the channel quality information CQI is available as soon as possible at the transmitter S. At the same time, channel quality information CQI should not be sent unnecessarily, since, as already mentioned, this leads to interference. Therefore, a timing of the transmission of this channel quality information CQI is proposed within the scope of the invention.

FIG. 2 shows an example of this time coordination under the boundary condition that there are regular, predetermined transmissions of the channel quality information CQI. A time axis labeled T is now shown in FIG. 2; the regular transmissions CQI-TX take place at specific times. A first data transmission DTX1 should now take place. For this purpose, it is determined whether the time interval t_delta between the first data transmission DTX1 and a regular transmission CQI-TX is greater than a defined first time interval. If this is the case, the transmitter additionally transmits the channel quality information CQI to the receiver.

It is generally checked whether a minimum time interval to the previous or the next known measurement is exceeded. This can be seen on the second data transmission DTX2, where the time interval t delta 'to fol channel quality information transmission CQI-TX is determined.

As shown on the basis of the third data transmission DTX3, a data transmission can also extend over a number of regular channel quality information transmissions CQI-TX. During the duration of the transmission, it is ensured that no further transmission of channel quality information takes place, which takes place too close to regular transmissions.

In order to distinguish between the state "start of a data transmission" and "existence of a data transmission", the time since the last transmission of a data packet or the length of the pause can be used in the case of a packet data transmission or a discontinuous line-switched transmission. If this time period is greater than a predetermined value, which is called the activity time in the following, this denotes the "start of a data transmission". A transition criterion between the two states can thus also be specified.

This inactivity time is preferably chosen to be greater than a round trip delay. A round trip delay is the time it takes to decode a message sent by a sender in the receiver, to notify the sender of the result of this decoding, which the sender then decodes again and then, depending on this result, the message times to send.

The choice of the time period larger than a round trip delay has the following background: Requires the last packet of a pa ketdatenübertragung or a "packet calls" due to insufficient reception quality several transmissions, then they always take place at a time interval that is at least one round trip delay, because the sender of the data packet could not know beforehand that the packet could not be received. If the time period is now chosen to be longer than a round trip delay, then this case of the data transmission packet sent several times is not erroneously referred to as the start of a new data transmission. This specification can be used in particular for HARQ (Hybrid Automatic Repeat Request) processes, for example for HSDPA. There the round trip delay is typically six transmission time intervals or "transmission time intervals" TTI. With HSDPA, a TTI specifies a time interval within which a base station sends to a terminal. As described, the round trip delay also depends on the reaction speed of the base station, which, in contrast to the reaction speed of the mobile station, is not standardized, but can be selected by any manufacturer depending on the capabilities of the implementation used. It may therefore be necessary to select the time period depending on the base station currently being used and to notify the mobile station. Terminals are also provided which cannot receive data via HSDPA in every transmission time interval TTI. In this case, the inactivity time is preferably adapted to the round trip delay changed thereby.

In the following, the invention is based on examples

HSDPA explained in more detail. The invention is also, for example, with a corresponding high-speed super in the upward direction, for example a procedure according to HSUPA or EUDCH.

In Figure 3, the timing of the signaling at HSDPA can be seen. Control information is sent in the downward direction on the so-called common high-speed control channel HS-SCCH or "high-speed shared control channel". Two time slots or "timeslots" later begins the transmission of the actual data or user data on the associated data transmission channel, the physical high-speed downlink connection channel HS-PDSCH or "high-speed physical downlink shared channel". An arrow indicates when the associated acknowledgment AN takes place via correct decoding (ACK) or incorrect decoding (NAK) from the terminal in the waiting direction to the base station. This confirmation or feedback AN is marked in the drawing with a running index n and with hatching. The duration of the measurement of the data for the channel quality information CQI is referred to as the measurement period MP.

The second arrow from the feedback AN, n in the HS-DPCCH to the HS-SCCH indicates from what point in time this confirmation is available again at the transmitter, i.e. at the base station, and thus a corresponding reaction can take place on the HS-SCCH. The

When the HS-PDSCH and HS-SCCH react, a point in time is grayed out.

With this configuration, three different reasons are now used for transmission of the channel quality information or "CQI feedback": 1. CQI feedback predetermined by the communication network, in particular cyclically recurring. The predetermination can in particular be carried out by a central unit such as a base station or RNC. Predetermination by the base station has the advantage that radio traffic can be easily regulated, particularly with regard to interference within a radio cell; in the case of regulation with the RNC, regulation with regard to several radio cells can also take place. 2. Additional CQI feedback at the start of a data transfer

3. Additional CQI feedback during active data transmission.

Time intervals are now defined for events 2 and 3, which determine the time interval between CQI feedbacks from these events and at least the cyclical CQI feedbacks. Optionally it can be regulated that predetermined CQI feedbacks are given priority. This priority can be regulated, for example, by aborting, postponing or temporarily prohibiting CQI feedback according to 2nd and 3rd. Alternatively, the priority can be regulated depending on parameters that affect data traffic.

In the different conditions, different conditions can be selected for sending CQI feedback. For example, CQI feedbacks can be sent immediately at the start of a data transmission after the terminal determines this state, whereas otherwise (for example according to method 2 of the prior art) CQI feedbacks are only sent if a NACK is sent has been. The first CQI feedback can then be sent earlier than in method 2, ie not only at time m as shown in FIG. 3, but earlier, for example at time m-1 or m-2, in extreme cases even time m -3 possible. The advantage is that the transmitter already has one or two, in extreme cases even 3, packets earlier (than e.g. in method 2) with current channel status information and can noticeably improve the data throughput, especially for shorter data transmissions. However, this improvement could also be applied to method 1, which has not yet been described. This method can also be combined with method 1, both alone and in combination with additional other exemplary embodiments. A maximum number of CQT feedbacks can optionally be defined at the start of a data transmission. This embodiment variant is advantageous if the first CQI feedback sent at the start of a data transmission is lost, ie cannot be received correctly. Then the information is still available at the transmitter through another CQI sent. Alternatively, the time interval to previous CQI feedbacks at the beginning of a data transmission can be chosen to be smaller than during an active data transmission. The start of a data transmission may not be defined as the first TTI in which a data packet was transmitted after no data packets were transmitted for a predetermined time (inactivity time). Rather, after this first TTI, this state must continue to apply for a certain predetermined time (hereinafter referred to as the hold time) until the system then switches to the active data transmission state (or, if necessary, to the no data transmission state if no further ones) More data packets were sent and the hold time was chosen to be longer than the inactivity time).

By checking whether the minimum distances to the preceding and following cyclical CQI have been exceeded, the sending of an unnecessarily large number of feedback can additionally be prevented. In particular, however, it can also be used to ensure that in the case of multiple transmissions of a CQI feedback, such retransmissions do not overlap with the subsequent transmissions of the next determined channel quality information. If the transmission conditions are such that the transmission of a CQI feedback in the uplink is not well secured, the suggestion is to send the CQI feedback repeatedly, that is, exactly the same CQI feedback several times in succession. The sender can then take all received copies into account during decoding and is therefore more likely to be able to correctly decode the CQT feedback than if only one copy were available. Of course, you cannot send a CQI feedback in every TTI, but, for example, with triple sending, at most every third TTI. However, if additional CQI feedbacks are sent in addition to the cyclical CQI feedbacks, there is the possibility that a repetition of a non-cyclical CQI feedback collides with a cyclical CQI feedback. This is disadvantageous because then either the additional CQI feedback or the cyclical CQI feedback cannot be repeated often enough and the detection of the CQI feedback is thus made more difficult. To prevent this, it is advisable to choose the time interval between predetermined and additional CQI feedbacks in such a way that such a collision cannot occur. To do this, the time interval must be at least as large as the number of repetitions. This setting of time Maximum distances can also be carried out without taking into account the activity status of the data transmission, that is to say for all non-predetermined CQI feedbacks.

The transmitter also knows the transmission times of the predetermined, in particular cyclical, CQI feedback during active data transmission. Again, checking for minimum distances from the preceding and following predetermined, in particular cyclic, CQI helps to avoid sending an unnecessarily large number of feedbacks and to avoid overlapping transmissions of different CQI feedbacks.

A suitable choice of these intervals can also ensure that cyclical CQT feedback takes precedence. This is also indicated for reasons of backward compatibility with previous standard specifications. Minimum distances to the cyclical CQI feedbacks are defined for non-cyclical CQI feedbacks, whereas there are no restrictions for the cyclical CQI feedbacks.

In another exemplary embodiment, minimum distances are also provided between non-cyclical CQI feedbacks. On the one hand, these minimum distances must be at least as large as the number of repetitions of a single, non-cyclical CQI feedback. On the other hand, larger minimum distances can also be selected. For example, a minimum distance can be selected such that a maximum or at most every third TTI, a CQI feedback is sent, although every CQI feedback is sent without additional repetitions. This prevents CQI feedback from being sent more often than the channel can change significantly. In this case it would be superfluous to send a CQI feedback for every TTI. This exemplary embodiment can be combined with all of the methods for sending out CQI feedback, which were initially listed under 1. to 4. under the description of the prior art. This combination would also be independent of the activity status of the data transmission.

In a further exemplary embodiment, it is specified that not every additional CQI feedback is sent, but only every nth, where n represents a natural number, e.g. every third. If packets are sent to the terminal in each TTI, then this procedure is equivalent to the previous exemplary embodiment when using activity-based CQI feedback (described under method 1), but otherwise fewer CQI feedbacks are generated by this exemplary embodiment. This situation is shown in Fig. 4. The boundaries of a subframe or subframe or “subframe” SF are marked on a time axis t by markings.

The fixed first time interval corresponds to a time period T, which in FIG. 4 corresponds to the length of 3 subframes.

It is now determined whether there is a certain first activity state, for example a current transmission. The times at which this first activity state AI is present are indicated by arrows in FIG. 4. In the exemplary embodiment shown in FIG. 4, additional channel quality information is only transmitted in the context of a message CQI '-TX if the activity state has occurred three times. Instead of the number 3, any other natural number can be chosen. As a result of this additional condition that the activity state has occurred n times, the transmission of the channel quality information can be adapted even more flexibly to the current transmission situation and, in particular, further transmission capacities that are not absolutely necessary can be saved.

Another exemplary embodiment provides for the first CQI feedback to be sent at the start of a data transmission, but then only for every nth additional CQI feedback. This ensures that an updated value is quickly available at the start of a data transmission, but only a few CQI feedback is sent during the data transmission and therefore less interference is generated than in the methods according to the prior art. This exemplary embodiment can be implemented, for example, by measuring the time T since the last transmission of the last CQI feedback, and in addition the number of occurrences of the activity state under consideration. In contrast to the previous exemplary embodiment, a CQI feedback is not sent if both the time period T and the number of occurrences of the activity state under consideration exceeds a predetermined threshold, but already if only one of these parameters exceeds the threshold. During a data transmission, the time threshold will not be exceeded, but rather the number of times the activity state under consideration occurs. The start of a data transfer will generally be characterized by the fact that no data has been transferred for a certain time beforehand and that the activity status under consideration did not occur. However, this is only one possible implementation of this exemplary embodiment. There is also the possibility that in the different states even different intervals can be selected for the cyclical CQI feedback. It is not only possible to use shorter intervals for times of data activity, with the aim of shortening the interval of the cyclical CQI feedbacks during the data transmission. In contrast to this, with the method proposed here, the interval of the cyclical CQI feedbacks during the data transmission can be increased, or the cyclical CQIs can be set completely. Additional CQIs are available during data activity

Grouting, e.g. according to method 2 when a NAK is sent, which enables a significantly higher correlation between the change in reception quality and the time of the CQI feedback than the predetermined cyclical CQI feedback.

In summary, this combination results in a very flexible instrument for controlling the CQI feedback. During inactivity on the data channel, information about the channel status of a subscriber can optionally be obtained by cyclical CQI feedback. At the start of a data transmission, an updated value is transmitted as quickly as possible, if there is not one in the immediate vicinity. The explicit request for CQI feedback is dispensed with because of the associated disadvantages, in particular the resource allocation in the downward direction. Furthermore, when performing the CQI feedback, a distinction is made between different activity states of the data transmission channel, the states “no active data connection”, “start of an active data connection” and “existence of an active data connection” being used in particular. It can also be considered to transmit further channel quality information (CQI-TX) from the receiver (R) to the transmitter (S) if either there is a first activity state and the time interval (t_delta) to the last transmission of channel quality information (CQI- TX exceeds a specified first time interval, or there is a first activity state and this state has already occurred n times.

LIST OF REFERENCE NUMBERS

S: broadcaster

R: Receiver

CN: communication network

CH1: First channel connection

CH2: Second channel connection

DTX1: First data transfer

DTX2: Second data transfer

DTX3: Third data transfer

CQI-TX: Regular transmission of channel quality information

TS: time slot

MP: measurement period

TB: Transport block

ON: feedback

Claims

claims

1. Method for data transmission via a data transmission channel (CH2) in a communication network (CN), which is provided between a transmitter (S) and a receiver (R) for wireless transmission and in which the data transmission takes into account the channel quality , with the following steps:

Repeated transmission of channel quality information (CQI-TX) from the receiver (R) to the transmitter (S);

Determining an activity state of the data transmission by the receiver (R);

Determining a time interval (t_delta) from the last transmission of channel quality information (CQI-TX);

Transmission of further channel quality information (CQI-TX) from the receiver (R) to the transmitter (S) when there is a first activity state and the time interval exceeds a specified first time interval.

2. The method according to claim 1, in which a single channel quality information (CQI-TX) is transmitted several times identically, the time interval between two of these transmissions being selected so that it is at least equal to a time period which is identical for the multiple ones Total channel quality information (CQI-TX) transmissions are required.

3. The method according to claim 2, wherein a repeated transmission of channel quality information (CQI-TX) from the receiver (R) to the transmitter (S) takes place, wherein individual channel quality information (CQI-TX) is transmitted several times identically and the specified first time interval is selected such that no collisions between repeated transmissions, further transmissions of channel quality information (CQI-TX) or multiple identical transmissions occur.

4. Method for data transmission via a data transmission channel (CH2) in a communication network (CN), which is made available between a transmitter (S) and a receiver (R) for wireless transmission and in which the data transmission takes into account the channel quality following steps:

- repeated transmission of channel quality information (CQI-TX) from the receiver (R) to the transmitter (S); - multiple identical transmission of individual channel quality information (CQI-TX);

- Determining an activity state of the data transmission by the receiver (R);

- Transmission of further channel quality information (CQI-TX) from the receiver (R) to the transmitter (S) when there is a first activity state and there are no collisions between repeated and further transmissions of channel quality information (CQI-TX) or their multiple identical transmissions.

5. Method for data transmission via a data transmission channel (CH2) in a communication network (CN), which is made available between a transmitter (S) and a receiver (R) for wireless transmission and in which the data transmission takes into account the channel quality , with the following steps:

Repeated transmission of channel quality information (CQI-TX) from the receiver (R) to the transmitter (S); - Determining an activity state of the data transmission by the receiver (R);

- Transmission of further channel quality information (CQI-TX) from the receiver (R) to the transmitter (S) when there is a first activity state and this state has already occurred n times.

6. The method according to any one of the preceding claims, wherein the transmitter (S) is a base station and the receiver (R) is a terminal or vice versa.

7. The method according to any one of the preceding claims 1 to 4 and 6, in which the further channel information (CQI-TX) is sent when the first activity state has already occurred n times.

8. The method according to any one of claims 5 to 7, in which a time interval (t_delta) to the last successful transmission is determined and a transmission takes place if this time interval (t_delta) exceeds a predetermined first time interval.

9. The method according to any one of the preceding claims, in which the data transmission takes place in packets.

10. The method according to any one of the preceding claims, wherein the activity state comprises a first status in which at least one data packet arrives at the receiver (R) or whose arrival is signaled and a second state in which no data packet arrives at the receiver (R) and no arrival is also signaled.

11. The method according to any one of the preceding claims, wherein the first time interval is determined depending on the activity state.

12. The method according to any one of the preceding claims, in which the repeated transmission of the channel quality information takes place at predetermined times.

13. The method according to any one of the preceding claims, wherein the repeated transmission takes place at least partially cyclically.

14. Method according to one of the preceding claims, in which the time interval to the next predetermined transmission of channel quality information is determined and if this time interval falls below a second specified time interval, the transmission of the further channel quality information is omitted.

15. The method according to any one of the preceding claims, wherein the predetermined times or the number n of a transmitter (S) in the form of a base station and / and the communication network (CN) are predetermined.

16. The method according to any one of the preceding claims, in which the channel quality information (CQI) is determined via at least one measurement, in particular immediately before a transmission of channel quality information (CQI) in the receiver (R).

17. The method according to any one of the preceding claims, wherein the communication network is a mobile radio network, which according to works according to the UMTS standard and the data transmission method is HSDPA.

18. Terminal with a transmitting / receiving unit for transmitting and receiving data via a radio link and a processor unit which is set up to carry out a method according to one of claims 1 to 17.

19. Base station with a transmitter / receiver unit for transmitting and receiving data over a radio link, with one

Connection to a communication network and a processor unit which is set up to carry out a method according to one of claims 1 to 16.

20. Communication network with a terminal according to claim 18 and a base station according to claim 19.