EP1405438A1 - Method for regulating the transmission power for the transmission of multi-cast messages in a mobile radio system - Google Patents

Abstract

The aim of the invention is to simultaneously transmit multi-cast messages intended for a group of receivers (MS1 - MS6) in a mobile radio system. To this end, the transmission power of a transmitter (BS) is regulated in such a way that all receivers (MS1 - MS6) in the group can receive the multi-cast messages with a sufficient reception quality. The receivers (MS1 - MS6) also determine the reception quality of the received multi-cast messages and based on said quality transmit at least one transmission power signal back to the transmitter (BS). The latter then evaluates the power transmission control signals of all receivers (MS1-MS6) of the group, in order to regulate the transmission power accordingly.

Description

METHOD FOR SETTING THE TRANSMISSION PERFORMANCE FOR THE TRANSMISSION OF MULTICAST-NA MESSAGES IN A RADIO SYSTEM.

The present invention relates to a method for setting the transmission power for the transmission of multicast messages in a radio system, in particular a mobile radio system, and to a correspondingly equipped radio system and correspondingly equipped transmitter and receiver.

Mobile radio technology is developing rapidly. Work is currently underway to standardize the so-called UMTS mobile radio system ("universal mobile telecommunication system") of the third mobile radio generation.

As multicast messages are called messages from a sender, for. B. in a mobile radio system from one, base station, simultaneously to a group of receivers, e.g. B. mobile stations are transmitted. The transmitter therefore sends a multicast message only once to the receivers belonging to the group, so that the effort for transmission is considerably less than with separate transmission of the multicast messages to each receiver in the group.

It is known from the mobile radio system according to the GSM standard to transmit messages which contain system information and are directed to all receivers in a radio cell with a constant transmission power. This is set in such a way that sufficient reception from the receivers is still possible even at the cell boundaries. It results in it. However, it should be noted that in the normal case, for all receivers that are closer to the center of the radio cell, the reception performance is significantly higher than that required to meet the relevant quality criteria. However, in the case of multicast messages in particular, the case may arise that the devices to which the multicast messages are directed and transmitted are not distributed up to the edge of the radio cell, so that radiation of the multicast messages with constant transmission power leads to an unnecessarily high consumption of transmission energy and leads to it unnecessarily Can cause interference in a neighboring cell.

If a code multiplex method is used in the radio system to separate different transmission channels, then an unnecessarily high transmission power leads to an unnecessary increase in interference within one radio cell and m other neighboring radio cells. This unnecessarily disturbed the connections of other participants, which would be noticeable, for example, through higher bit error rates.

It is an object of the present invention to provide a method for transmitting multicast messages in a radio system, in particular a mobile radio system, in which multicast messages can be transmitted with a high quality and low interference from other connections. Furthermore, the present invention is intended to provide a correspondingly equipped radio system with a suitable transmitter, receiver and / or subscriber device.

This object is achieved by a method having the features of claim 1 or a radio system having the features of claim 19 and a transmitter according to claim 21 or a receiver according to claim 23.

The transmitter does not emit the multicast messages with a constantly high transmission power, but adjusts them according to the actual requirements so that each recipient of the group that is to receive the multicast messages receives the multicast messages with a sufficient level Can receive reception quality. For this purpose, that the receivers of the group determine a measure of the reception quality of the multicast messages and, depending on this, send back at least one transmission power control signal to the transmitter. In the simplest case, this transmission power control signal can be, for example, an increase command ("up command") if the multicast messages are received with a poor reception quality and the transmitter is to increase the transmission power, and a decrease command ("down Command ") if the recipient receives the multicast messages with an unnecessarily high reception quality and the sender receives the

Should reduce transmission power. This makes it possible to regulate or control the transmission power in such a way that each recipient of the group can receive the multicast messages with a sufficiently high reception quality, where necessary, if some recipients receive the multicast messages with an excessively high quality Receive quality received.

To measure the reception quality, a receiver can advantageously either use the signal-to-interference

Use ratio ("SIR"), and / or a bit error rate, and / or a block error rate in block-wise transmission methods in the radio system. These values can preferably be compared in the receiver with predetermined limit values, so that the receiver generates the transmission power control signal depending on whether these limit values are exceeded or not. In particular, two variants can be used to carry out the method. In the first, all receivers in the group that is to receive the multicast messages send a transmit power control signal back to the transmitter. This evaluates all incoming transmit power control signals with regard to their content and the respective number and thus adjusts the transmit power. For example, he can increase the transmission power as soon as at least one recipient requests an increase in the transmission power. Accordingly, the transmitter can reduce the transmission power if it does not receive the signal to increase the transmission from any receiver. deleistung or receive the signal from all receivers to lower the transmission power. It may also be possible to accept poor reception from a few receivers by reducing the transmission power when the number of control signals that require an increase in the transmission power falls below a certain number.

In particular, the radio transmission in a radio system can be based on a frame structure according to which the transmission time is divided into frames of the same length. These frames can also be divided into time slots in which data packets are exchanged. For the setting of the transmission power according to the invention, it can be provided that the transmission power control signals are not transmitted by the receivers in every time slot, as can be the case, for example, with the power regulation for a transmission channel which only transmits messages directed to a receiver. Instead, the transmission power control signals for the multicast messages can advantageously be sent, for example, only once per time frame. In this way, the transmission volume from the receivers to the transmitter can be reduced. This usually has no adverse effects, since the required or optimal transmission power for multicast messages usually changes less quickly.

The time intervals in which the transmission power control signals are transmitted can advantageously be made dependent on the determination of the reception quality in the individual receivers. The distance between the transmitted transmission power control signals can thus be increased if the multicast messages can be received with a reception quality that is above the limit value. Accordingly, the frequency of the transmission power control signals can be increased if the multicast messages are received too poorly. The receivers can advantageously also be configured such that they only send transmission power control signals if they can receive the multicast messages with a reception quality that is too low. In such a case, the transmitter would only increase the transmission power if it received such transmission power control signals, and decrease the transmission power if, for example, it did not receive such a transmission power control signal within a certain time. It can also be expedient to define a certain number of transmission power control signals per unit of time as a limit value above which the transmission power is increased and below which the transmission power is reduced.

In another alternative, not all receivers in the group are used to regulate the transmission power, but rather a specific receiver or a subgroup of receivers is selected by the transmitter or radio system, which are used as examples for the rest of the group to set the transmission power. These are the receivers that are the least able to receive multicast messages broadcast by the broadcaster. As soon as the transmission power is set so that this subgroup of receivers can receive the multicast messages with sufficient quality, it can be assumed that the remaining receivers in the group, who can receive messages broadcast by the transmitter better, will also receive the multicast messages received a sufficient ordeal.

In particular, the receivers of the respective group that are furthest away from the transmitter are used, since the reception quality generally decreases with increasing distance. A position detection service of the radio system, for example, can be used to determine the distance between a receiver and the transmitter, with the aid of which the distance is determined. There is also the possibility of using a measure of the signal transit time between the transmitter and the receiver, in particular a measure that is determined by the radio system anyway. As soon as a receiver registers in the radio system, such a round time ("round tπp time") is usually determined. In particular, this round trip time thus directly represents a measure of the distance between a receiver and the transmitter and can thus serve for the selection of the receiver or the receivers, which are used as examples to set the transmission power of the multicast messages.

Since new receivers can register or deregister both in the radio system and in the group, the transmission power required to transmit the multicast messages to this group may change. The same can apply if a receiver of the group moves and its distance to the transmitter changes. In such cases, it is advisable to ensure that in particular the transmission power is set with respect to the recipient (or recipients) who currently belongs to the group and is furthest away from the transmitter.

The present invention is preferably suitable for use in a mobile radio system, in particular a UMTS

Mobile radio system. Of course, however, the present invention is generally applicable to other radio systems in which the transmission of multicast messages should be possible, it being noted that both the transmitter side and the receiver side are affected by the present invention.

Further developments of the invention are given in the subclaims.

The invention and its developments are explained in more detail below with reference to drawings. Show it:

FIG. 1 shows a simplified illustration of a mobile radio cell of a mobile radio system to explain the transmission of multicast messages according to the invention,

FIG. 2 shows a layer model to explain the transmission of multicast messages according to the invention,

3 shows a schematic representation of the generation of a transmission power control signal by a subscriber device of a group of subscriber devices for the inventive control of the transmission power of at least one transmitter station of a radio communication system, the radio cell of which the subscriber device and other members of the group are currently in, and the associated, thereupon measured reception quality of message or data signals to be received in this subscriber device,

FIG. 4 shows a schematic representation of a radio cell of the radio communication system with a group of subscriber devices, of which at least one subscriber device controls the transmission power of the transmission station of this radio cell according to the method according to the invention,

5 shows a schematic representation of the structure of a so-called DPCCH burst (Dedicated Physical Control Channel), which is group-specific, i.e. for all subscriber devices of the respective group in the current residential radio cell as the only radio channel for controlling the transmission power of the local one

Transmitting station is used, FIG. 6 shows a frame structure of the uplink control channel MC-DPCCH for multicast applications,

FIG. 7 shows a sketched representation of a mobile radio cell with spatially selective packet data transmission from a base station NodeB to several mobile stations UE1 to UE6 as a simplified block diagram,

FIG. 8 shows a structure of a physical multicast channel PMcCH in the downlmk frame structure m TD-

SCDMA,

Figure 9 in a table examples of slot formats for the MC-DPCCH, and

FIG. 10 shows a table multicast TPC commands according to the present invention.

Elements with the same function and mode of operation are consistently provided with the same reference numerals in FIGS. 1 with 10.

The radio cell Z shown schematically in FIG. 1 has a base station BS in its center, which represents the transmitter m in the radio system. This base station BS can be assigned a network control unit, not shown, which regulates, for example, the transmission to further radio cells. Furthermore, there are several receivers in the form of mobile stations MSI to MSβ within the radio cell Z. The receivers MSI to MSβ are randomly distributed over the area of the radio cell Z, so that the receivers MSI to MSβ can have different distances from the base station BS.

In the radio system described, the information is transmitted digitally, the data transmission being based on a layer model. This layer model is shown in FIG. 2. Each recipient consists of MSI to MSβ as well the transmitter BS from a physical layer PL ("physical layer"), which is responsible on the transmitter and receiver side for processing the data for transmission via the air interface via physical channels 1. In the following consideration, it is assumed that higher layers are also accommodated on the transmitter side m of the base station, although these can also be accommodated in function blocks separate from the base station BS. On the transmitter and receiver side, there is a media access control layer MAC ("medium access control") above the physical layer, which is connected to the physical layer PL. The connections between the physical layer PL and the MAC layer are called transport channels 2 and indicate how the data is transmitted (for example on general channels or on channels which are dedicated only to a specific mobile station). The MAC layer has tasks such as For example, the identification of the users for which data is intended, if they are transmitted on general channels, and the mapping of logical channels 3 onto the transport channels 2. For this purpose, the MAC layer adds control information on the transmitter side (eg via the Identity of the mobile station) to the transmitted data which it has received from a radio link control layer RLC ("radio link control") arranged above it. At the receiving end, these control formats are evaluated and removed from the data again before they are forwarded via logic channels 3 to the RLC layer. The connections between the MAC layer and the RLC layer are referred to as logical channels 3.

The RLC layer is responsible for monitoring the data transmission, ie for detecting missing data and possibly requesting it again. Several units can be defined in the RLC layer. Each RLC unit is connected to a connection between higher layers and RLC (e.g. radio bearer). The RLC layer can also add control information on the transmitter side to data it has received from higher layers. This control format tions are used at the receiving end to e.g. For example, to assess whether data is missing and are removed from the data before it is passed back to the higher layers.

The data are transmitted in the radio system in time slots, which in turn are embedded in a fixed frame structure. The frames each last 10 milliseconds and contain 15 time slots over which the data transmitted over a physical channel 1 are distributed. A so-called burst is transmitted in each of these time slots, which represents a sequence of bits that can be divided into m different data fields.

The multicast messages to be transmitted are mapped according to the layer model onto a physical channel 1, which is transmitted via the air interface from the transmitter BS to at least one receiver MSI to MSβ. With the help of the present invention, the transmission power of this physical channel 1 is now regulated in such a way that all those of the receivers MSI to MSβ who are to receive the multicast night can receive it with at least a certain minimum reception quality. In the following it is now assumed that the receivers MS4 to MSβ form a reception group for multicast messages which are sent out by the transmitter BS. Furthermore, all receivers MSI to MSβ should be equipped in such a way that they can determine the reception quality of received multicast messages and compare them with predefined limit values. Depending on this, they generate a transmission power control signal which is an up command to increase the transmission power if the reception quality is too poor and a down command if the reception quality is above the limit value.

According to a first exemplary embodiment, all receivers MS4 to MSβ in the group send the transmission power control signals to the transmitter BS. The transmitter BS is set up so that it has the transmission power for the transmission of the multicast messages as long as it receives an up command from a receiver MS4 to MSβ in the group. Starting from a state in which the transmission power is too low for all receivers MS4 to MSβ in the group, the setting of the transmission power will now be described. At the beginning, all receivers MS4 to MSβ send up commands, so that the transmitter BS gradually increases the transmission power. This also increases the reception quality for the receivers MS4 to MSβ, the reception quality first reaching the required value for the closest receivers MS4 and MS5. Once this happens, these receivers MS4 and MS5 send down commands, whereas the more distant receiver MSβ continues to send up commands. The transmitter BS now continues to increase the transmission power until a time at which the reception quality at the receiver MSβ is sufficiently high so that the latter stops sending up commands and sends down commands when the transmission power increases further. In this case, the transmitter BS was only given down commands, so that it reduces the transmission power again, but it only reduces the transmission power until the most distant receiver MSβ again receives the multicast messages with a poor quality receives and starts sending up commands. The transmission power of the transmitter BS for the transmission of multicast messages to the receivers MS4 to MSβ is set in this method in such a way that it leads to a fluctuation in the reception quality around the required limit value for the most distant receiver MSβ. The receiver MSβ alternately sends up and down commands, whereas the other, closer receivers MS4, MS5 constantly send only down commands. The latter receive the multicast messages with an unnecessarily high quality, but this is inevitable if the recipient MSβ is also to receive the multicast messages with a sufficient quality.

In this exemplary embodiment it can additionally be provided that down commands with a larger time interval are sent as up commands or that even down commands are not sent at all, only up commands. In such a case, the transmitter BS is expediently set up in such a way that it also reduces the transmission power if it does not receive an up command for a certain time.

According to a second exemplary embodiment, not all of the receivers in a group are used to set the transmission power, but rather the receiver BS is selected by the transmitter who is furthest away and the transmission power is set exclusively on the basis of its transmission power control signal. In this exemplary embodiment, the receivers MSI to MS4 now form a group which is to receive multicast messages together. First of all, the transmitter BS determines a measure for the distance of the various receivers MSI to MS4 in the group. For this purpose, the size of the round trip time (RTT) can be used by the transmitter BS. With the help of this measurement which already exists in the radio system and which is carried out when a receiver MSI to MSβ registers in the radio system, the transmitter can estimate the distance of each receiver MSI to MS4 in the group from the transmitter BS. This allows the most distant MSI receiver to be selected for power control. In this case, the transmitter BS regulates the power in such a way that the power is increased when the receiver sends MSI up commands and is decreased when the receiver sends MSI down commands. The other receivers MS2 to MS4 are located closer to the transmitter BS, so that they can generally receive the multicast messages with a better quality than the receiver MSI, so that one for all receivers MSI to MS4 in the group Minimum reception quality is ensured.

If a new recipient, for example the recipient MSβ, is added to the group for the multicast messages in this exemplary embodiment, the transmission power may be readjusted. For example it should be provided that the newly added receiver MSβ gives feedback to the radio system as to whether the multicast messages are already being received well enough. An unnecessary change in the transmission power of the transmitter BS can thereby be avoided.

The statements made about FIGS. 1 and 2 are generally valid within the scope of the invention.

The invention further relates to a method for controlling the transmission power of at least one transmission station of a radio communication system, an associated subscriber device and an associated transmission station.

In modern radio communication systems such as According to the UMTS standard (Universal Mobile Telecommunication Standard), subscriber devices in the respective radio cell as well as across radio cells can be assigned to one or more groups. The subscriber devices of such a group are then jointly supplied with information or data via a group message signal. In particular, in a UMTS radio communication system, so-called multicast groups of subscriber devices per radio cell or across cells can be distributed over several radio cells, which then receive common services, user data / user messages, signaling signals, etc., group-selectively sent. A group-specific classification or classification of subscriber devices can, for example, with regard to the respective type of message, such as in sports news, weather news, traffic news, etc.

The invention is particularly based on the object of demonstrating a way in which the transmission power of at least one transmission station of the radio communication system in which one or more subscriber devices of the respective group are currently located can be controlled in a simple and efficient manner in such a way that the subscriber devices are to be transmitted - Ten- / Nachrιchtensιgnale and other signaling signals can still receive with sufficient, ie not with insufficient reception quality. This task is solved in an advantageous manner by the following method:

Method for controlling the transmission power of at least one transmission station of a radio communication system, the radio cell of which contains at least one predefinable group of one or more subscriber devices, in particular according to one of the preceding claims, characterized in that the transmission station of at least one subscriber device of the group using at least one transmission power - The control signal is only communicated as long as the transmission power is increased as long as the measured reception quality of this subscriber device is below a predefinable threshold value, and that no control signal of this subscriber device is sent to the transmitting station if its measured reception level reaches the threshold value or is above it.

The fact that the transmitting station m of the respective radio cell, in which one or more subscriber devices of the respective group are present, is only informed by at least one of these subscriber devices with the aid of at least one transmit power control signal for as long as the transmit power increases as the measured reception quality of this subscriber device is below a predeterminable threshold value, and otherwise no control signal is sent to the transmitting station, the transmitting power of this transmitting station can be controlled in an efficient manner. At the same time, it is largely ensured that the respective subscriber device of the group can detect night signals, data signals and other signaling signals of the transmitting station arriving with a sufficient reception power level.

The invention further relates to a subscriber device for carrying out this method explained above. The invention also relates to a transmitting station of a radio communication system which is designed to carry out this method.

For the sake of clarity, FIG. 4 shows only a single radio cell representative of a large number of further radio cells of a cellular radio communication system and is designated CE1. This radio cell CE1 is supplied with radio technology from a transmitting station BS1, in particular a base station, i.e. clamped. Within each radio cell, a base station is responsible for radio communication with the one or more subscriber devices that are located there. Preferably the respective base station is e.g. BSl approximately in the center of the respective radio cell, e.g. CE1 arranged. The respective base station is preferably formed by at least one radio transmitter and at least one radio receiver. In particular, it has at least one transmitting antenna. In addition to or independently of their function of providing a radio connection to subscriber devices of the radio communication system, the respective base station serves to establish connections to coordinating, controlling components of the radio communication system and / or to an existing fixed network.

In the simplified radio communication system according to FIG. 4, night / data and / or other signaling signals are transmitted via at least one predefined air interface between at least one subscriber device and at least one base station, e.g. BSl m of the radio cell CE1 by a time division multiple access transmission method, in particular by a combined TDMA-CDMA multiple access transmission method, transmitted (TDMA = Time Division Multiple Access, CDMA = Code Division

Multiple access). In order to be able to carry out a subscriber separation, it is simply printed out at the radio transmission transmission over the air interface of the respective subscriber device to the assigned base station (and vice versa), a temporal division of the message signals into a large number of successive time slots of a predefinable period of time with a predefinable time frame structure. Several subscribers who communicate with the base station in the same radio cell at the same time are expediently separated from one another with regard to the message data connections by orthogonal codes, in particular according to the CDMA principle, in combination with the time division multiplex division. Several subscribers who simultaneously access the network resources, that is to say send and / or receive message signals simultaneously in the same radio cell, are thus separated from one another in terms of radio technology by means of so-called orthogonal codes, preferably using the CDMA method (Code Division Multiple Access).

Here in the exemplary embodiment, the radio communication system is preferably designed as a mobile radio system according to the so-called UMTS standard (= Universal Mobile Telecommunication System). In particular, it is operated in the so-called FDD mode (FDD = Frequency Division Duplex). In FDD mode, separate signal transmission in the uplink and downlink direction (uplink = signal transmission from the respective subscriber device to the respectively assigned base station, Downlmk = signal transmission from the respectively assigned base station to the respective subscriber device) by means of a correspondingly separate assignment of different frequencies or frequency bands frequency division multiplexing. In particular, two different carrier frequencies are advantageously used for signal transmission in the uplink and downlink direction.

In FIG. 4, there are currently several subscriber devices MSI with MS5 in the radio cell CE1. These subscriber devices are preferably mobile stations, in particular mobile radio telephones or cell phones. The same applies to the other radio Lines of the radio communication system which, for the sake of clarity, have not been shown in FIG. 4. The subscriber devices are preferably mobile, ie at different locations in the different radio lines of the radio communication system. If necessary, some of the subscriber devices can also be arranged in a stationary, ie stationary, manner in one or more radio cells.

Other message and / or data transmission devices with an associated radio unit for communication traffic "on air", i.e. be provided via an air interface. These can be, for example, Internet computers, television sets, notebooks, fax machines, etc.

In modern radio communication systems, e.g. According to the UMTS standard, it is desirable to assign one or more subscriber devices to a group. The member-subscriber devices of such a group can all be in the same radio cell as well as distributed in several radio cells of the radio communication system. One or more group messages can then be sent to the members of the respective group from the base station m of the respective residential radio cell of these subscriber devices using only one radio resource provided, which is particularly efficient. In other words, when group-wise notification of member-subscriber devices of predefined groups, it is no longer necessary to set up an extra individual radio connection for each individual member device. It is therefore no longer necessary to signal, set up and provide n individual connections for n subscriber devices in a radio cell to which the base station there is to send the same message.

In FIG. 4 there is an example of a first group MCI in the radio cell CE1 through the three mobile radio devices MSI with MS3 educated. A group-specific subdivision can take place, for example, with regard to the function (multicast, broadcast), the news topic (sports, weather, politics, business) and other types of classification.

In the case of mobile radio systems, various services are offered, for example the voice service, sending and receiving SMS messages (short message system), calling up information using WAP (Wireless Application Protocol), etc. For special services or applications, the transmit the same information to several users or subscriber devices simultaneously. Pay e.g. News groups, video conferences, video-on-demand, radio, etc. In order to save resources in the transmission via the air interface, it is expedient to use the technique of so-called multicast transmission for such services. Instead of transmitting the same information to each individual user via a separate channel of the air interface, the information that is to be given to all participants in such a group is only transmitted to all users simultaneously via only a single radio channel. This is how normal television reception works, for example: a transmitter broadcasts all channels at the same time, and each recipient chooses the radio channel that the viewer would like to see. In this way, a single transmitter can supply up to several million receivers and uses only a minimum amount of bandwidth.

What is problematic in practice is how the transmission power

(Power Control) of the base station in the respective current stay radio cell of members of the respective group for the transmission of one or more group messages, in particular multicast messages, via which the air interface can be controlled in an efficient and reliable manner. In mobile communications system UMTS, the transfer of infor mation ^¬ takes place to a user or Teilnehmergerat preferably in that in each specific case a physical resource, in particular a physical radio channel is reserved. When transmitting data, no matter what type, a distinction is made between two transmission directions in mobile radio. In general, the data transmission from the generally fixed base station to the subscriber devices, in particular mobile radio stations, is referred to as the transmission in the downlink direction. In contrast, data transmission in the opposite direction from the respective mobile radio station to the respectively assigned base station is referred to as transmission in the uplink direction. In the so-called FDD mode, the transmission m up and down is carried out on different frequencies. Several subscribers per radio cell are separated by stamping orthogonal codes (channelization codes) on the information data. This multiple access method is known as the CDMA method. According to the current specifications (TS25.211, V3.7.0: Physical Channels and mapping of transport Channels onto physical Channels, 3GPP-TSG-RAN, 2001) des

UMTS-FDD-Modes is a physical channel in the downlink direction, in particular defined by a carrier frequency, scrambling code, the channelization code and a start and stop time. The purpose of the scramble codes is to scramble the already spread data signals. Among other things, this is intended to minimize the interference (interference) from and neighboring cells.

There is preferably a specific radio channel for transmitting cell-specific information that each mobile radio station or mobile radio device requires in order to be able to operate within the radio system. This is referred to as a broadcast channel (BCH = Broadcast Channel) and can preferably be received by any mobile radio station anywhere in its respective location radio cell. The special thing about this radio channel is that the transmitted information is not specifically sent to a specific, ie special, mobile radio station are directed. As soon as, for example, a mobile radio station is switched on, the information of the broadcast channel is read out from it, without any signaling of the radio network. This radio channel cannot be used for the transmission of multicast information or can only be used to a limited extent, since its limited capacity (according to the current specification m UMTS of approximately 30 kbps) is already occupied by the cell-specific information. In UMTS there are two types of radio channels for the transmission of information: so-called dedicated channels and so-called

Common channels. With dedicated channels, a physical radio resource is reserved only for the transmission of information for a specific subscriber. With the common channels, information can be transmitted that is intended for all participants in the respective radio cell

(e.g. the BCH) or only for a specific user. In the latter case, the common channel also transmits for which subscriber the information is intended.

To control the transmission power of the respectively assigned base station in the sojourn radio cell of the respective subscriber device, which is assigned to a certain group in advance, a SIR (Signal to Interference Ratio) based power control with closed control loop can be used, which is particularly detailed in the specification TS 25.214 V3.5.0 Physical layer procedures, 3GPP-TSG-RAN, 2001). The respective mobile radio station makes an estimate of the so-called SIRs (= signal-to-interference ratio) for the dedicated channels it receives. This value represents a quality criterion for the radio signal received in each case. A so-called TPC command (TPC = Transmit Power Control) is generated by comparison with a predefined target value SIRtarget, and the result is transmitted to the associated via an upmk channel. ordered base station sent. The value for the target value SIRtarget is expediently specified individually by the radio network for each mobile radio station in such a way that for the respective wavy radio connection an adequate reception quality is guaranteed. In addition to or independently of this, the radio network for each transport channel DCH possibly also a desired target value BLER _ta rget value as so-called "block error rate * (block error rate) or BER _target value as so-called" bit error rate * Specify (bit error rate). In a constant comparison with the BLERs actually achieved, the mobile radio station independently determines the SIR target) In UMTS, the TPC commands are preferably purely Boolean information and merely represent the information as to whether the measured SIR value is below or above the specified value SIRtarget lies. Therefore, the TPC commands can also be equated with the commands "UP" (= SIR is below SIRtarget), ie "increased transmission power *, and" DOWN "(= SIR is above SIRtarget) / ie" decrease the transmission power " The "UP" command means that the reception quality in the respective mobile radio device is not sufficient, and therefore an increase in the transmission power is necessary for the transmission unit of the base station. The Down command means that the transmission power of the transmission unit of the base station is too strong for the particular station measuring mobile radio device sends, so that the transmission power can be reduced.

In practice, the transmission power of the base stations there for the message transmission of one or more group messages, in particular multicast groups, is of interest, such as for a group of one or more subscriber devices which can be located in a single radio cell or in an area distributed over several radio cells - straighten, can be controlled as efficiently and reliably as possible. For this purpose, the respective base station is informed by at least one subscriber device of the group in its local radio cell with the aid of at least one transmission power control signal only as long as it increases its transmission power as long as the measured reception quality of the received radio signals m requesting mobile radio device transmitting control signal below one predefinable threshold value lies. On the other hand, no control signal from this subscriber device is sent to the transmitting station if the measured reception level of the respective subscriber device reaches or exceeds the threshold value. This type of control is illustrated schematically in FIG. 3. Time t is plotted there along the abscissa. In the upper half of FIG. 3, the exemplary received power level DP of radio signals in the subscriber device MSI of group MCS1 of FIG. 4 is shown along ord RP. Below this first diagram, the time profile of the transmission power level of a control signal sequence SL1 of the mobile radio device MSI for the desired setting of the transmission power of the assigned base station is shown. The strength, ie the transmission power level TP, for the control signal sequence SL1 is plotted along the ordmats. Generally speaking, RP in the first, upper diagram is some measure of the reception quality in the respective subscriber device, such as MSI, and TP in the lower, second diagram, the power with which the subscriber device MSI sends one or more control signals to the base station BS1. The dotted horizontal line in the upper, first diagram shows a desired, predeterminable reception quality SW, which should suitably be maintained for the subscriber device as the minimum quality for the measured reception level. As soon as this threshold SW is undershot, for example at time tA, the subscriber device MSI sends one or more control signals SSI, SS2,..., SSk, SSi at certain time intervals TZ, preferably with increasing transmission power. Here in the exemplary embodiment, the control signal sequence SL1 can only be detected by the base station BSl from the moment tS onwards from its pulse SSk (in particular, tS is shortly before or at least simultaneously with the transmitted control signal SSk), whereupon this in turn transmits the transmission power or Radiation power for group signals is preferably increased in stages. The control signals SSk to SSi, which are sent from the subscriber device MSI to the base station BS1 and from the base station BS1 with a continuously or stepwise increased transmission power from the time tS can also be received are identified by hatching in the lower diagram of FIG. 3. Characterized in that the base station BS from the time tS also turn its transmission power during the transmission of th Gruppennachπch- or group of signals increases, also increases the Empfangsqua ^¬ LITAT in Teilnehmergerat MSI. The reception power curve DP rises again in the upper diagram after its drop between the times tA and tS below the threshold value SW from the time tS. From the time tE after the control signal SSi, the reception level curve DP finally reaches the desired target threshold value SW, which has been specified as sufficient for a perfect reception quality. From this point in time tE, from which the predetermined reception quality is reached again, the subscriber device MSI ends the transmission of control signals, so that a rest phase or dead time PA occurs. At the same time, the base station also advantageously stops increasing its transmission power when transmitting group messages.

If a multicast information, which is sent from the base station BS1 m FIG. 4 to all mobile stations MSI with MS3 of the same multicast group MCI m of the radio cell CE1, is to be made sufficiently receivable for all mobile stations in this group with at the same time minimal allocation of radio resources the following types of regulation or control of the transmission power for the physical radio channel on which the multicast information is to be transmitted is expedient. The multicast radio channel is referred to below in particular as the Physical Multicast Channel DMCCHS. It is therefore desirable that the multicast information can be detected by all mobile stations of the respective multicast group whose current location radio cell is of sufficient reception quality (with at the same time minimal use of transmission resources). For this purpose, it is expedient that each of the mobile stations that is to receive the same multicast service measures the reception quality. As a measure of the reception quality, the signal for interference Ratio are determined (SIR value = signal to interference ratio). In the case of block-by-block radio transmission in the radio communication system, it may be expedient to determine the reception quality m of the respective mobile station by determining the so-called block error rate (BLER = Block Error Rate). Additionally or independently of this, in the case of bitwise radio transmission in the radio communication system, the degree of reception quality can also be classified on the basis of the so-called bit error rate (BER = bit error rate). The measured Empfangsqualitatsmesswert is in each case with a predetermined, desired threshold value, such as SIR _T arget / BLER _Ta rget / BER _target or a similar Sollmaßwert for the reception quality compared. When receiving in the respective mobile radio device, two cases in particular must then be distinguished:

1st case:

The reception quality is better than the specified threshold, e.g. SW (see Figure 3) or equal to the specified threshold. Then the respective mobile radio station should not do anything, i.e. no longer send a control signal to the relevant base station, since reception is guaranteed with sufficient quality.

2nd case:

The reception quality in the respective mobile radio device is worse than the predetermined target threshold value, which could be the case, for example, with the mobile radio device MSI from FIG. 4, since it is the furthest away from the base station BS1 from all mobile radio bones of the MCI group. Only in this case is the mobile station to signal the base station according to the above method, i.e. send at least one control signal to increase the transmission power of the base station, whereupon the base station in turn increases its transmission power until the reception quality even in the most distant subscriber device reaches the threshold value or lies above this. Version 1:

For each multicast group, a so-called preamble is defined in a group-specific manner, which can be specified as a predefinable chip sequence via the mobile radio channel (for UMTS, a physical channel is defined, among other things, via a channelization code. Such a code should not be used in variant 1) of each Mobile radio device is sent to the base station, the reception quality of which is poorer than the predetermined threshold value. This preamble signal is known both to the relevant base station and to all mobile radio stations belonging to the respective multicast group. The predefinable preamble signal as a chip sequence is preferably different from the orthogonal codes for subscriber device separation. An example of a preamble signal sequence is given in particular in the specification TS 25.211 V3.7.0 Physical Channels and mappmg of transport Channels onto physical Channels, 3GPP-TSG-RAN, 2001 in chapter 5.2.2.1.2 and there in connection with the so-called physical

Random Access Channel (PRACH). Alternatively, however, other, similarly constructed and / or longer or shorter preamble signals can also be used. If the reception quality for a mobile radio station is now worse than the predetermined threshold value, the respective mobile radio station sends the preamble signal pattern to the base station with a specific transmission power, that is to say preamble signal start power. This is preferably repeated regularly at certain intervals (preamble transmission intervals), each time with a transmission power increased by a certain value (power increase increment). Concrete values for preamble start power, preamble transmission interval and power increase increment can preferably be determined by each mobile radio station itself, but may also be specified by at least one component of the radio network by prior radio signaling. This first method advantageously ensures that the base station can detect the significant, predefined preamble signal pattern at some point. The detection can be carried out, for example, with the aid of a simple correlator in the base station. How long it takes for the base station to detect this preamble control signal depends in particular on the start values for the three parameters listed above. The detection of the preamble control signal is synonymous for the base station as a TBC command "UP". At the time of detection of the preamble control signal, the base station continues to increase its transmission power for multicast messages at selectable time intervals, until the transmission (on the mobile station side) or the detection (on the base station side) of this preamble signal - there is no pattern. This will be the case when the mobile radio station that sent the preamble signal pattern has a sufficiently good reception quality due to the increased transmission power of the multicast messages. This is achieved when the reception quality is at or above the predefinable threshold.

Generally speaking, the transmission power control signal of the respective subscriber device is transmitted as a common, group-specific preamble signal to the respectively assigned base station, which is based on the pre-reserved code multiplex signals which are used for the actual message / data transmission of the various subscriber devices in the respective radio cell. is different.

In this way, in particular in UMTS radio communication systems, it is ensured that the pre-reserved CDMA codes for the subscriber device separation remain largely untouched or unaffected and thus no radio resources for the actual message / data transmission are otherwise deducted, i.e. get lost.

Version 2: This variant is functionally similar to variant 1. The difference is in particular that instead of a preamble control signal e, a group-shared code multiplex signal from the respective mobile radio device, whose reception quality is below a predefinable threshold, is sent to the relevant base station for setting its transmission power accordingly is that the reception quality in this mobile radio device is increased to the threshold value or above. A so-called DPCCH burst, which is transmitted on a dedicated physical control channel already provided in the UMTS, is preferably used as the group-shared code multiplex control signal. The time division or sectorization of such a burst is shown in FIG. 5. The local burst TS can send 10 bits per slot, i.e. time slot, which are distributed over different fields or time windows: PL (= training sequence, which can be used, for example, to determine the SIR value), TFCI (= transport format Combmation Indicator), FBI (= Feedback Information) and TPC (= Transmit Power

Control). The DPCCH burst TS of FIG. 5 has in particular a time length of 0.667 milliseconds (msec) in UMTS, which corresponds to a time slot that is once again divided into 2560 chips. For the so-called TPC command in UMTS, em or two bits e can be made available depending on the configuration. This field can also be used in this variant for the "UP" command and can be set with bit values such as 1. Since the other fields have no use in this case, the transmission of other information in the fields PL, TFCI, FBI can, if necessary, be dispensed with entirely, and these empty fields can then be used for additional information on the control signal TPC. In total, 10 bits can be used for the control signal in this way, so that an increase in the transmission power of the base station can be indicated with an "UP" command, and further additional information can also be supplied if necessary. It would also be conceivable, for example, with the number of the bits which are assigned 1 (the rest of the bits are then assigned the logical 0) to give an indication of how large the selectable step size should be with the steadily increasing transmission power on the part of the respective base station. If, for example, all 10 bits are assigned the value 1, the distinction between the reception quality and the specified value is very high and the base station should expediently carry out larger steps to adapt the transmission power. However, if only a single bit or no bit is assigned the value 1, there is only a slight distinction between the threshold values, and only minor steps are necessary in adapting the transmission power. In the case of all intermediate values, an appropriate step-by-step is then expediently selected to adapt the transmission power. This second variant also applies: as soon as that

If there is no transmission of the burst as a control signal, the increase in the transmission power in the base station is stopped, since this is an indicator or indication that the reception quality of the mobile radio device which issues the control signal again corresponds to the predetermined threshold value or exceeds it again.

Viewed overall, e.g. a different number of ones ("1") in the burst of the base station m advantageously give an indication of how strongly / m how it should increase your transmission power (e.g. with higher increments and / or with more frequent increases).

In both variants of the method according to the invention, the regulation or control of the transmission power m of the respective base station is expediently carried out automatically as follows: if the base station receives no command within a certain time, that is to say no control signal for increasing the transmission power (the base station thus detects within a certain time) no preamble signal pattern or a weak or no burst), it automatically reduces the transmission power in a selectable range Step size and in selectable time intervals until it receives such a control command again (since any mobile radio station from the multicast group has poor reception quality and therefore starts to send a preamble signal pattern or a burst).

The following applies in particular to both variants:

Transmitting power TP of the first, i.e. Initial control signal such as SSI (with what power do you start to send the control signals),

Pause time TZ between two successive control signals, and

ΔTP (difference in the transmission power of two successive control signals) can preferably either be freely selected by the respective mobile radio station or, if appropriate, also specified by the base station (that is, signaled beforehand).

In the case of a transmission power control carried out in this way according to the various design variants, a separate radio resource for transmitting transmission power control signals in the uplink (= from the respective subscriber device to the assigned transmitting station) is advantageously not allocated for each subscriber device, in particular for each mobile radio station. Depending on the method (“preamble” or “burst”), preferably no radio resource or in particular only one radio resource per multicast group (or a number of multicast groups) is used in the uplink.

The present invention advantageously also relates to a method, a transmitting and / or receiving unit and a communication system for controlling the transmission of data via a mobile radio link in a mobile radio system according to the Universal Mobile Telecommunications System standard UMTS, in particular for efficient power control for future multicast Applications in UMTS FDD mode according to claims 33, 44, 45. The current version of the UMTS standard, referred to as Release 4, as of 06/2001, contains three radio transmission technologies: the frequency domain duplex or FDD mode, the 3.84 Mcps time domain duplex or TDD mode and the 1.28 Mcps TDD mode. The following explanations refer exclusively to the FDD mode (see [l] - [5] at the end of the description).

In FDD mode, data transmission from uplink and downlink takes place on different frequencies. The term uplink is understood to mean the transmission of the data from a mobile subscriber terminal, for example a cell phone or the like, to a base station. The mobile subscriber terminal is called UE below, the base station is referred to as NodeB. Accordingly, the transmission of the data from the NodeB to the UE is referred to as a downlink. The channels or the individual participants are separated by applying orthogonal codes, see above. Spreading codes on the information data.

In FDD mode, power control is an important element. The task of power control is to set the transmission power for each connection direction, that is to say both for uplink and for downlink, so that the data can be transmitted efficiently via the physical channels with a ner certain transmission quality are transmitted without disturbing other participants.

[4] specifies the power control procedures for the various physical channels. A distinction is made between the so-called common channels and the so-called dedicated channels. In the downlink common channels, for example, data is sent unidirectionally from the NodeB to all UEs or to a specific UE in the cell. For this purpose, the common channels are transmitted with a constant transmission power so that they can be received well in the entire cell. The dedicated channels, on the other hand, are used for bidirectional data transmission between the NodeB and a specific UE. The transmission power for these channels is set in the form of a SIR-based power control. The task of the SIR-based power control is to set the transmission power of the channels individually for each connection direction in such a way that a predetermined value of the signal-to-interference ratio SIR is maintained at the respective receiving antenna. For example, the SIR-based power control in the downlmk direction is carried out as follows.

The NodeB initially sends data via a downlink dedicated channel to the UE with a constant transmission power. The UE carries out a measurement of the SIR on the received data on the dedicated channel. This value represents a quality criterion for the channel received. By comparison with a specified value SIRtarget, a transmit power control or TPC command for changing the power is generated at the NodeB and the result is sent back to the NodeB via an associated uplink dedicated channel. The value for SIRtarget is specified individually by the UMTS network for each UE in such a way that sufficient quality is guaranteed for the respective connection.

Currently the TPC commands TPC_cmd are pure 1-bit information. TPC commands merely represent the information as to whether the measured SIR is below or above the specified value SIRtarget. After receiving a TPC command, the transmission power for the next downlink dedicated channel is then changed in the NodeB by a specific amount Δ _T pc x

TPC_cmd, e.g. by + ldB. The process is as follows:

• If the measured SIR is below the SIR target, the TPC command "Up" with TPC_cmd = 1 is generated in the UE and transmitted via an uplink connection to the NodeB. After receiving the Up command, the transmit power of the De - transmit dedicated channels at the next downlmk connection increased by the amount Δ _TPC . • If the measured SIR is above SIRta _r , the TPC command "Down" with TPC_cmd = -1 is generated in the UE and transmitted to the NodeB via an Uplmk connection. After receiving the Down command, the transmission power of the Dedicated channels transmitted at the next downlmk connection reduced by the amount Δ _TP C.

Various services and applications, such as News groups, video conferences, video-on-demand, etc. can be used in the downlink via the common channels or dedicated channels. However, the previous possibilities are in the case of future multicast services or applications in which the same information is to be sent from the NodeB to a group of UEs, see above. Pomt-to-multipot transmissions, inefficient. Instead of, for example, transmitting the same information to each UE via a separate physical channel via the air interface, it is more efficient to transmit this information simultaneously to all UEs in question in the group via a common channel.

A basic concept of multicast transmission in the downlmk direction is described above with the aid of FIGS. 1 to 5. The main content is the implementation of the physical downlink multicast channel and the associated procedures for power control.

A further development of this invention is based on the object of proposing a method and a device which, based on this multicast concept, provide efficient power control for future multicast applications in UMTS FDD mode. This also includes the implementation of an associated uplink channel and the definition of TPC commands that are to be generated in the UE. This object is achieved according to the invention by em method with the features of claim 33. Furthermore, a transmitting and / or receiving unit according to claim 44 and a communication system with the features of claim 45 are solutions to this problem.

The following describes three advantageous exemplary embodiments for realizing an efficient power control for future multicast applications in UMTS FDD mode:

• Definition of an uplink multicast channel for the transmission of control data for the optimal implementation of multicast applications;

• Definition of an uplink TPC command to implement efficient SIR-based power control;

• Procedure for combining several TPC commands into one TPC command in the uplink.

A first method for realizing an efficient power control for future multicast applications in UMTS FDD mode is characterized by the fact that an uplink multicast channel is used for the transmission of control data for the optimal implementation of multicast applications. Via this uplink multicast channel as the physical channel, each subscriber terminal UE of a multicast group transmits the control information that is necessary for the optimal implementation of multicast applications. The uplink multicast channel basically has the same appearance as the uplink DPCCH, which is already used in FDD. The multicast channel is therefore referred to here as MC-DPCCH. The following pilot bits are transmitted on each time slot: Transport Format Combination Indicator or TFCI bits, Feedback Information or FBI bits and Transmit Power Control or TPC bits. For future multicast applications, these FBI bits are now advantageously used to transmit the multicast information or MCI bits in the uplink. The MCI bits are used to represent the NodeB informs about which multicast services the respective UE uses. The exact number of bits to be transmitted in the individual fields of the MC-DPCCH is variable, reference being made to the description of an exemplary embodiment with reference to the drawing.

Furthermore, an efficient power control for future multicast applications in UMTS FDD mode is created by introducing a new SIR-based power control. The goal of any SIR-based power control is that all UEs of the multicast group can receive the downlink multicast channel within the cell in sufficient quatttat. For this reason, it is necessary that a regulation of the transmission power in the downlink is designed for the UE h which receives the downlink multicast channel with the worst quality. On the other hand, in order to protect the high-frequency components of the NodeB em, frequent changes in the transmission powers should be avoided. For this reason, new TPC commands TPC_cmd, which preferably represent 2-bit information, are defined for multicast. Each UE continues to perform a measurement of the SIR per time slot on the received data on the downlink multicast channel. A TPC command for changing the power at the NodeB is generated slot by slot by comparison with predefined SIR thresholds and the result is transmitted to the NodeB via the MC-DPCCH. After receiving the TPC commands from all UEs of the multicast group, the NodeB combines them into one TPC command per slot and changes the transmission power for the next downlmk connection by a certain amount Δ _TPC x TPC_cmd. In contrast to the status of the, the new TPC commands TPC_cmd with 2-bιt information content

However, technology can now display up to four different modulation symbols, two of which are used for up and down regulation and two of which are used equally for the system to remain in a current power state. The system is considerably relieved by the introduction of this new state without a change in performance. According to a further development, the 2 bits of the TPC command that are now available for representing the two opposite control commands are each assigned the same value, i.e. as values 00 and 11. The modulation symbols associated with the bit sequence for increasing and decreasing the transmission power are the furthest in the signal space away. This has a positive effect on the accident rate. Each transmission error causes the system to remain in the current state, whereas according to the prior art a regulation was triggered in the opposite and therefore wrong direction.

Furthermore, in a preferred embodiment of the invention, an amount Δ _{SIR is introduced} as a tolerance interval around a preset value SIRtarget, which is in particular formed symmetrically on two sides. Thus, deviations from the set value SIR _ta rget are now without causing a control step accepts that lie within this tolerance band. This measure also increases the efficiency of the power control by reducing the control interventions.

As a further solution to the above task, a method for creating a combined TPC command as a function f of the N TPC commands of all UEs of a multicast group in the uplink is proposed. Depending on the size of the multicast group, the NodeB receives a variety of TPC commands to change the transmission power for the downlink multicast channel. The task of the NodeB is now to process the weighting of individual N TPC commands of all UEs with appropriate control so that the data on the downlink multicast channel of each UE of the multicast group within the cell is sufficient can be received. For efficient power control, it is proposed in particular that a combined TPC command is created as a function f of the N TPC commands of all UEs of a multicast group which • triggers an increase in the transmission power for the entire multicast group if at least an "Up" command is received, regardless of what the other NI TPC commands say; • does not provide for a change in the transmission power if all N TPC commands as "Do nothing" commands are received and

• which causes a reduction in the transmission power for the entire multicast group if at least one "down" command is received under the N TPC commands and there is no "up" command among the remaining N-1 TPC commands.

The following three versions are particularly advantageous for implementing efficient power control for future multicast applications in UMTS FDD mode:

1. Uplink multicast channel

FIG. 6 shows the frame structure of the uplink control channel for multicast applications.

Each UE of the multicast group transmits the control information on this physical channel, which is necessary for the optimal implementation of multicast applications. This uplink multicast channel has the same appearance as the uplink DPCCH, which already has FDD. The multicast channel is therefore referred to here as MC-DPCCH. The following pilot bits are transmitted on each time slot or slot: Transport Format Combination Indicator or TFCI bits, Feedback Information or FBI bits and Transmit Power Control or TPC bits. The spreading factor SF of 256 is provided for the MC-DPCCH, so that 10 control bits can be transmitted in the uplink per slot.

An extension of the already existing DPCCH in the MC-DPCCH is the use of the FBI bits. So far, such FBI bits in FDD mode have been used to implement techniques such as closed loop mode transmit diversity CL-TxD or site selection To support diversity transmission SSDT, see [4]. These will now be used for future multicast applications FBI bits used according to the invention to also transmit the multicast information or MCI bits in the uplink. The MCI bits inform the NodeB which multicast services the respective UE uses. The exact number of bits to be transmitted in the individual fields of the MC-DPCCH is variable. As an example, some slot formats for the channel are shown in the table in FIG.

2. Uplink multicast commands The aim of the SIR-based power control is that all UEs of the multicast group can receive the downlink multicast channel within the cell in sufficient quality. For this reason, it is necessary that the regulation of the downlink transmission power must be designed for the “weakest” UE. The term “weakest” UE means the UE that receives the downlink multicast channel with the poorest quality. On the other hand, in order to protect the high-frequency parts, frequent changes in the transmission power at the NodeB should be avoided.

For this reason, new TPC commands TPC_cmd are defined for multicast, which now represent 2-bit information. As before, each UE carries out a measurement of the SIR per time slot on the received data on the downlink multicast channel. A TPC command for changing the power at the NodeB is generated slot by slot by comparison with predefined SIR thresholds and the result is transferred to the NodeB via the MC-DPCCH. After receiving the TPC commands from all UEs of the multicast group, the NodeB combines them into one TPC command per slot and changes the transmission power for the next downlink connection by a certain amount Δ _T pc x TPC_cmd. Each UE should generate the new Multicast TPC commands in the following way:

- If SIR <SIR _tar get - Δ _S ι _R , the TPC command "Up"

(TPC_cmd = 1) generated in the UE and transmitted to the NodeB via the MC-DPCCH. After receiving the up- Command transmit the transmission power of the downlink multicast channel increased by the amount Δ _T PC.

- If SIRtarget - Δ _S ι _R <SIR <SIRtarget + Δ _SIR , the TPC command "Do nothmg" (TPC_cmd = 0) is generated in the UE and transmitted to the NodeB via the MC-DPCCH. Then in the NodeB After receiving this command, the transmission power of the downlink multicast channel is not changed.

- If SIR> SIR _targ et + Δ _S IR, the TPC command "Down" (TPC_cmd = -1) is generated in the UE and transmitted via the MC-DPCCH to the NodeB. In the NodeB, after receiving the Down - Command transmit the transmission power of the downlink multicast channel decreased by the amount Δ _T pc.

This table for generating the new multicast TPC commands is summarized in the table in FIG.

3. Combination of TPC commands in the uplink

Depending on the size of the multicast group, the NodeB receives one

Numerous TPC commands to change the transmission power for the downlink multicast channel. The task of the NodeB is now to combine the various TPC commands into one TPC command, so that the data on the downlink multicast channel can be received by any UE of the multicast group within the cell with sufficient quality. Assuming that the multicast group is composed of N UEs, a combined TPC command will be generated as a function f of the N TPC commands of all UEs:

TPC_cmd = f (TPC_cmd_l, TPC_cmd_2, ..., TPC_cmd_N)

For efficient power control, the NodeB should generate the combined TPC command in the following way:

- TPC_cmd = 1: At least one "Up" command is received, regardless of what the other NI TPC commands say. - TPC_cmd = 0: All N TPC commands are received as "Do nothing" commands.

- TPC_cmd = -1: If at least one "Down" command is received under the N TPC commands and there is no "Up" command among the remaining N-1 TPC commands.

In the following, a multicast scenario is assumed to represent an exemplary embodiment according to the present invention, as shown in FIG. 7. A UMTS radio cell with a NodeB and 6 UEs, UEl to UE6 is assumed. To transmit the multicast data in the downlink, the physical multicast channel PMcCH is used in accordance with the principle of the embodiment variants of FIGS. 1 to 5, see FIG. 8.

The NodeB now sends the multicast data in the data part of the PMcCH to all β UEs of the multicast group initially with a constant transmission power. All UEs performed a measurement of the SIR per time slot on the received data on the PMcCH. Em TPC command is then generated for each time slot to a Leistungsanderung Δ _PMC C _H at the NodeB and the result is transmitted via the MC-DPCCH to the Node B by comparison with predetermined SIR threshold according to the table of FIG 10th After receiving the TPC commands from all UEs of the multicast group, the NodeB combines these slot by slot to form a TPC command and changes the transmission power accordingly from one time slot to the next for the next PMcCH by a certain amount Δ _PMC CH = Δ _T PC X TPC_cmd through.

The following three cases will now be considered as examples:

Case 1:

Here it is assumed that the 6 UEs generate the following TPC commands per slot after evaluating the PMcCH:

- UEl → TPC cmd 1 = 1 ("Up") - UE2 → TPC_cmd_2 = 1 ("Up")

- UE3 → TPC_cmd_3 = 1 ("Up")

- UE4 → TPC_cmd_4 = 0 ("Do nothing")

- UE5 → TPC_cmd_5 = -1 ("Down")

- UE6 → TPC_cmd_6 = 0 ("Do nothing")

Since the regulation of the downlink transmission power is designed for the "weakest" UE, the NodeB combines the various TPC commands into a TPC_cmd = 1, ie the "Up" command

Case 2:

Here it is assumed that the 6 UEs after evaluating the

PMcCH generate the following TPC commands per slot:

- UEl → TPC_cmd_l 0 ("Do nothing")

- UE2 → TPC_cmd_2 0 ("Do nothing")

- ÜE3 -> TPC_cmd_3 0 ("Do nothing")

- UE4 → TPC_cmd_4 -1 ("Down")

- UE5 → TPC_cmd_5 -1 ("Down") - UE6 -> TPC cmd β 0 ("Do nothing")

In this case, the NodeB combines the various TPC commands to a TPC_cmd = -1, ie the "Down" command.

Case 3:

Here it is assumed that the 6 UEs generate the following TPC commands per slot after evaluating the PMcCH:

- UEl → TPC_cmd_l 0 ("Do nothing") - UE2 → TPC_cmd_2 0 ("Do nothing")

- UE3 → TPC_cmd_3 0 ("Do nothing *)

- UE4 → TPC_cmd_4 0 ("Do nothing *)

- ÜE5 → TPC_cmd_5 0 ("Do nothing *)

- UE6 - TPC cmd 6 0 ("Do nothing *)

In this case the NodeB combines the various TPC commands to a TPC_cmd = 0, ie the command “Do nothing * It is clear from the above description that the features specified for solving the problem mentioned at the outset can be combined with one another in an advantageous manner.

Background information on UMTS can be found in particular at the following points referenced in the text above: [1] 3GPP TR 25.211 V4.0.0 (2001-03): Physical Channels and apping of transport Channels onto physical Channels (FDD) [2] 3GPP TR 25.212 V4 .0.0 (2000-12): Multiplexing and Channel coding (FDD) [3] 3GPP TR 25.213 V4.0.0 (2001-03): Spreading and modulation (FDD) [4] 3GPP TR 25.214 V4.0.0 (2001- 03): Physical layer procedures (FDD) [5] 3GPP TR 25.215 V4.0.0 (2001-03): Physical layer - Measurements (FDD)

Claims

claims

1. Method for setting the transmission power for the transmission of multicast messages in a radio system, wherein multicast messages to be transmitted by a transmitter (BS) are intended for a group of receivers (MS), in which

the transmitter (BS) sends the multicast messages to the receivers (MS) belonging to the group,

at least one receiver (MS) in the group determines the reception quality for the multicast messages and, depending on the reception quality, sends at least one transmission power control signal to the transmitter (BS), and

the transmitter (BS) sets the transmission power for the transmission of the multicast messages in such a way that the at least one receiver (MS), which transmits an emitted power control signal, receives the multicast messages with a reception quality that is at or above a limit value.

2. The method according to claim 1, characterized in that the at least one receiver (MS) as a transmit power control signal sends an increase command to the transmitter (BS) as long as the at least one receiver (MS) the multicast messages with one under the Received quality limit value received, and sends a decrease command to the transmitter (BS) as long as the at least one receiver (MS) receives the multicast messages with a received quality value above the limit value.

3. The method according to any one of the preceding claims, characterized in that all receivers (MS) of the respective group receive the Determine the quality of the multicast messages and send a transmission power control signal to the transmitter (BS).

4. The method according to claim 3, characterized in that the transmitter (BS) increases the transmission power for the transmission of the multicast messages when a first number of receivers (MS) receives the multicast messages with a reception quality below the limit, and lowered if a second number of receivers (MS) receives the multicast messages with a reception quality above the limit value, the first number being less than the second number.

5. The method according to claim 4, characterized in that the first number is 1 and the second number is the number of remaining receivers (MS) m of the group.

6. The method according to any one of the preceding claims, characterized in that m further messages are transmitted to the radio system, the transmission power of which is set with the aid of further transmission power control signals sent by the receiver (MS) receiving these further messages to the transmitter (BS). are sent, the frequency with which the transmission power control signal for the further messages are transmitted being higher than the frequency with which the transmission power control signal for the multicast messages is transmitted.

7. The method according to any one of the preceding claims, characterized in that the at least one receiver (MS), when it receives the multicast messages with a reception quality above the limit value, transmits the transmission power control signal at greater time intervals than if it were the mul- ticast messages received with a reception quality below the limit.

8. The method according to any one of claims 1 to 6, characterized in that the at least one receiver (MS) sends only em transmit power control signal when it receives the multicast messages with a reception quality below the limit, and the transmitter (BS) the transmission power for the multicast messages is reduced if it receives only the transmission power control signal or only a few transmission power control signals within a certain period of time, and the transmission power is increased if it receives at least the transmission power control signal or at least a certain number of transmission power control signals ,

9. The method according to any one of the preceding claims, characterized in that the transmitter (BS) determines a measure of the distance of the receivers (MS) from the group, selects a subgroup of receivers (MS) furthest from the transmitter (BS) and only this instructs to send transmit power control signals.

10. The method according to any one of claims 1 to 8, characterized in that the transmitter (BS) determines a measure of the distance of the receiver (MS) of the group, selects the most distant receiver (MS) from the transmitter (BS) and only instructs this to send transmit power control signals.

11. The method according to claim 9 or 10, characterized in that the transmitter (BS) by means of a localization service provided by the radio system determines the positions of the receivers (MS) and, depending on the positions, the distances of the receivers (MS) from the transmitter (BS ) determined.

12. The method according to any one of claims 9 or 10, characterized in that when a receiver (MS) registers in the radio system, a transit time (RTT) is determined which is a measure of the signal transit time between the receiver (MS) and the transmitter ( BS), and the transit time (RTT) is used as a measure of the distance between the receiver (MS) and the transmitter (BS).

13. The method according to any one of claims 9 to 12, characterized in that the transmitter (BS), as soon as the receiver (MS) registered in the radio system logs off from the radio system, registers a new receiver (MS) in the radio system or em receiver (MS) its position changed, the dimensions for the distances of the

The group's receiver (MS) is updated and, depending on it, selects the receiver (MS) furthest from the transmitter (BS) and instructs it to send transmit power control signals.

14. The method according to any one of the preceding claims, characterized in that the receiver (MS) determines the reception quality on the basis of the signal-to-interference ratio.

15. The method according to any one of the preceding claims, characterized in that the radio transmission m carried out in blocks in the radio system, and the receiver (MS) determines the reception quality on the basis of the block error rate.

lβ. Method according to one of the preceding claims, characterized in that the radio transmission in the radio system is carried out bit by bit, and the receiver (MS) determines the reception quality on the basis of the bit error rate.

17. The method according to any one of the preceding claims, characterized in that the radio system is a mobile radio system, wherein the transmitter (BS) corresponds to the network side of the mobile radio system and the receiver (MS) each correspond to a mobile station.

18. The method according to claim 17, characterized in that a UMTS mobile radio system (universal mobile telecommunication system) is used as the radio system.

19. Radio system for transmitting multicast messages, with a transmitter (BS) for transmitting multicast messages, which are intended for a group of receivers (MS), the transmitter (BS) being set up in such a way that it Sends multicast messages to the receivers (MS) belonging to the group, and at least one receiver (MS) of the group is set up in such a way that it determines the reception quality for the received multicast messages and, depending on the reception quality, at least one transmission power control signal for Transmitter (BS) transmits, and the transmitter (BS) is set up in such a way that it sets the transmission power for the transmission of the multicast messages in such a way that the at least one receiver (MS), which transmits a transmission power control signal, transmits the multicast Receives messages with a reception quality that is at or above a limit.

20. Radio system according to claim 19, characterized in that the radio system is designed to carry out the method according to one of claims 1 to 18.

21. Transmitter for transmitting multicast messages to a radio system, in particular according to one of the preceding claims, the multicast messages being intended for a group of receivers (MS) in the radio system, the transmitter (BS) being set up in such a way that it sends the multicast messages to the receivers (MS) belonging to the group and in Depending on transmission power control signals which are transmitted by at least one receiver of the group depending on the reception quality of the multicast messages, the transmission power for the transmission of the multicast messages is set such that the at least one receiver transmitting at least one transmission power control signal (MS) receives the multicast messages with a reception quality that is at or above a limit value.

22. Transmitter according to claim 21, characterized in that the transmitter is designed to carry out the method according to one of claims 1 to 18.

23. Receiver for receiving multicast messages in a radio system, in particular according to one of the preceding claims, which are intended for transmitting multicast messages from a transmitter (BS) to a group of receivers (MS), the receiver (MS) is set up in such a way that it determines the reception quality for the multicast messages and, depending on the reception quality, sends at least one transmission power control signal to the transmitter (BS).

24. Receiver according to claim 23, characterized in that the receiver (MS) is designed to carry out the method according to one of claims 1 to 18.

25. Method for controlling the transmission power (TP) of at least one transmission station (BS1) of a radio communication system, in the radio cell (CE1) of which at least one predefinable right group (MCI) of one or more subscriber devices (MSI with MS3), in particular according to one of the preceding claims, characterized in that the transmitting station (BSl) of at least one subscriber device (MSI) of the group (MCI) with the aid of at least one transmitting power Control signal (SL1) is only communicated as long as the transmission power increases as the measured reception quality (DP) of this subscriber device (MSI) lies below a predefinable threshold value (SW), and that none

Control signal (SL1) of this subscriber device (MSI) is sent to the transmitting station (BS1) when its measured reception level (DP) reaches or exceeds the threshold value (SW).

26. The method according to claim 25, characterized in that the transmission power control signal (SL1) is transmitted as a common, group-specific preamble signal to the respectively assigned base station (BS1), which is different from code multiplex signals pre-reserved for message / data signal transmission.

27. The method according to / claim 25, characterized in that the control signal (SL1) of the respective subscriber device (MSI) of the group (MCI) is transmitted via a group-shared, pre-reserved code multiplex signal to the respectively assigned base station.

28. The method according to any one of claims 25 to 27, characterized in that the radio communication system in FDD mode (Frequency Division Duplex) is operated by UMTS.

29. The method according to any one of claims 25 to 28, characterized in that that the transmission power of the control signal (SL1) of the respective subscriber device (MSI) is increased until the respectively assigned transmission station (BSl) has increased its transmission power to such an extent that the measured reception quality of this subscriber device (MSI) is at or above a predefinable threshold value ( SW).

30. The method according to any one of claims 25 to 29, characterized in that the transmission power is automatically reduced by the transmitting station (BS1) if no transmitting power control signal (SL1) is received by at least one subscriber device of the group (MCI) within a predeterminable period of time ,

31. Participant device which is designed to carry out the method according to one of claims 25 to 30.

32. transmitting station of a radio communication system, which is designed to carry out the method according to any one of claims 25 to 30.

33. The method according to any one of the preceding claims, wherein to implement an efficient power control for multicast applications in UMTS FDD mode at least one uplink multicast channel is used for the transmission of control data for carrying out multicast applications, the uplink multicast channel is constructed analogously to an uplink DPCCH of the UMTS-FDD mode, but in which one or more feedback information bits (FBI) are now used to transmit at least one multicast information in the uplink.

34. The method according to claim 33, characterized in that multicast information form of e or more multicast information bits (MCI) are transmitted.

35. Method according to one of claims 33 or 34, characterized in that one or more TPC commands (TPC_cmd) are used for multicast applications in UMTS FDD mode, which represent 2-bit information.

36. The method according to claim 35, characterized in that four modulation symbols are shown, two of which are used for up and down commands and also two of the same value are used for the system to remain in a current power state.

37. The method according to any one of claims 35 and 36, characterized in that the 2 bits of the TPC command available for representing the two opposite control commands are each assigned the same value.

38. The method according to any one of claims 33 to 37, characterized in that in a SIR-based control of the transmission power of a base station (NodeB) a tolerance interval (Δ _SIR ) around a default value (SIRtarget) is used.

39. The method according to claim 38, characterized in that the tolerance interval (Δ _S ι _R ) is bilateral and in particular symmetrical about the default value (SIR target).

40. The method according to any one of claims 33 to 39, characterized in that a combined TPC command (TPC_cmd) as a function (f) of N TPC commands of all members (UE) of a multicast group in the uplink is generated by weighting.

41. The method according to claim 40, characterized in that the weighting e causes the transmission power to be up-regulated if at least an “Up” command is received, regardless of a command content of the other N-1 TPC commands.

42. The method according to any one of claims 40 or 41, characterized in that no change in the transmission power is made when all N TPC commands are received as "Do nothmg" commands.

43. The method according to any one of claims 40 to 42, characterized in that a reduction in the transmission power for the entire multicast group is initiated if at least one “Down” command is received under the N TPC commands, and among the rest Nl TPC commands no "Up" command is located.

44. Sending, receiving unit and / or em subscriber device with efficient power control for multicast applications in a mobile radio system according to the universal mobile telecommunications system standard UMTS in UMTS FDD mode, the sending, receiving unit and / or the subscriber device for Implementation of a method according to one of claims 33 to 43 is formed.

45. Communication system with efficient power control for multicast applications according to a mobile radio system

Universal mobile telecommunications system standard UMTS in UMTS FDD mode, the communication system comprising at least one transmitting, receiving unit and / or em subscriber device according to claim 44.