WO2004109951A1

WO2004109951A1 - Method for controlling transmitting power of at least two channels transmitting simultaneously from a transmitting station and transmitting station

Info

Publication number: WO2004109951A1
Application number: PCT/EP2004/050710
Authority: WO
Inventors: Hans Kroener; Mario Konegger; Li Yu
Original assignee: Siemens Aktiengesellschaft
Priority date: 2003-06-04
Filing date: 2004-05-05
Publication date: 2004-12-16
Also published as: DE10325306A1

Abstract

The invention relates to a method for controlling transmitting power (P1out, P2out, ..., PMout) of at least two channels (K1, K2, , KM) transmitting simultaneously from a transmitting station (BS). If the total requested transmitting power (P1in, P2in, ..., PMin) for the channels (K1, K2, ..., KM) exceeds a threshold value (G), the transmitting power of each channel is adjusted according to a transmitting property of the corresponding channel such that the total transmitting power (P1out, P2out, ..., PMout) is less than or equal to the threshold value (G).

Description

description

Method for controlling transmission powers of at least two channels transmitted simultaneously by a transmitting station and transmitting station

The invention relates to a method for controlling transmission powers of at least two channels transmitted simultaneously by a transmitting station and to a corresponding transmitting station.

In radio communication systems that are operated, for example, according to the UMTS-FDD standard (UMTS: Universal Terrestrial Telecommunications System, FDD: Frequency Division Duplex), CDMA (Code Division Multiple Access) is used for subscriber separation.

Different mobile stations are assigned different codes, so that the mobile stations contain a large number of data from a base station simultaneously with different codes, i. H. Using different channels to which mobile stations are sent, can decode the data based on the codes used that are intended for the respective mobile station.

The radio communication system has several base stations that share a finite set of codes. It can therefore happen that several base stations use the same code for different mobile stations. If the transmission power of the base stations is too high, the data from different base stations in a mobile station can interfere so strongly that the mobile station does not receive the data intended for it can separate more of the data destined for the other mobile stations.

In order to minimize such interference, an upper limit for the emitted transmission power can be specified by a radio network controller for base units.

The individual channels transmitted by a base station, which can be distinguished by the use of different codes, share the total transmission power available from the base station. Each channel has its own transmit power control, a so-called "fast closed loop power control". This transmission power control controls the transmission power of a channel in such a way that a predefinable transmission or reception quality is achieved. However, the individual transmission power controls of the channels are organized decentrally, i. H. independently of each other. This can lead to a total power that exceeds a predetermined limit value being requested by all transmission power controls that have to take into account a transmission unit of the base station. Instead of the limit value being exceeded, it can of course also happen that the maximum transmission power that an amplifier responsible for several channels can deliver in its working range of the transmission unit is exceeded.

The invention is therefore based on the object of specifying an advantageous method for controlling the transmission powers of at least two channels transmitted simultaneously by a transmitting station, in which a sum of the transmission powers is prevented from exceeding a limit value. This object is achieved with the method and the transmitting station in accordance with the independent claims.

Advantageous further developments of the invention are the subject of the dependent claims.

In the method according to the invention for controlling transmission powers of at least two channels transmitted simultaneously by a transmitting station, if a sum of the transmission powers requested exceeds a .limit value, the transmission power of each channel is dependent on a transmitter-side property of the corresponding channel is set so that the sum of the transmission powers is less than or equal to the limit value. A property on the transmitter side is any property that exists when transmitting that is suitable for distinguishing channels from one another. The transmitter-side properties include e.g. B. the current transmission power, the type of data transmitted or the type of channel.

Different codes are used in a CDMA system to distinguish between channels. In an FDMA system (FDMA: Frequency Division Multiple Access), the channels differ based on their frequency. In general, channels are distinguishable transmission paths for data transmission. As in the case of CDMA, the same physical carrier can be used for different channels.

In a first embodiment of the invention, it is advantageous that the current transmission power is used as the transmitter-side property of the corresponding channel when the limit value is exceeded by the sum of the transmission power requested. The transmission power of the channel with the largest current transmission power is advantageously reduced in percentage terms more than the transmission power of the other channel. In this way, the total transmission power available can be distributed over all channels in such a way that the transmission quality reaches a common optimum for all channels.

Another advantage arises when the transmission power of the other channel remains the same or is increased. While the

Transmitting power of the channel with the greatest current transmitting power can be reduced so that its transmission quality is only slightly deteriorated, the other channel can simultaneously maintain or even improve its transmission quality. In the best case, the requested transmission power can even be set for the other channel.

In a second embodiment, it is useful that the type of the transmitted data is used as the transmitter-side property of the corresponding channel.

For example, a distinction can be made between real-time and non-real-time data as the type of data transmitted. Real-time data is time-critical and should be transmitted without any delay, ie without repeated transmission due to insufficient transmission power. On the other hand, non-real-time data can be transmitted with a delay, ie with transmission pauses and / or repeated transmissions. According to the invention, real-time data can therefore receive the requested transmission power or a value that is as close as possible to the requested transmission power, while at most the transmission power is used for non-real-time data that can remain after setting the transmission power of the real-time data until the limit value is reached.

In a third embodiment of the invention, the type of the respective channel is advantageously used as the transmitter-side property.

For example, the type of channel concerned relates to the respective data rate.

By taking into account the type of channels, the transmission power for a channel which, for example, transmits a time-critical service with a high data rate, can be set in accordance with the requested transmission power, B. would provide a transmission power control (fast loop power control) that is optimized only for a transmission quality of the channel. The prerequisite here is that the transmission power set in this way does not already exceed the limit value. The transmission power that is still available until the limit value is reached can then be distributed equally among the other channels. Of course, the distribution of the transmission power still available can also be dependent on the properties of the other channels on the transmitter side.

The sending station has all the necessary features that are required to carry out the method according to the invention.

The invention is explained in more detail below with reference to exemplary embodiments shown in the figures. Show it: Fig. 1 shows a base station with an inventive

Transmission power controller

2 shows a first exemplary embodiment of a transmission power control according to the invention, in which the type of data is used,

Fig. 3 shows a second embodiment of a transmission power control according to the invention, in which the type of channel is used and

Fig. 4 shows a third embodiment of a transmission power control according to the invention, in which the transmission power of a channel is used.

The same reference symbols in the figures denote the same objects.

The invention can advantageously be used in any radio communication system. Radio communication systems are any systems in which data is transmitted between stations via a radio interface. The data transmission can take place bidirectionally as well as unidirectionally. Radio communication systems are, in particular, any mobile radio systems, for example according to the GSM (Global System for Mobile Communication) or UMTS (Universal Mobile Telecommunication System) standard. Future mobile radio systems, for example of the fourth generation as well as ad-hoc networks and wireless local area networks (WLAN), are also to be understood as radio communication systems. A sending station is any station that can send signals. In the following, a base station is considered to be the transmitting station.

Of course, a sending station can also be a mobile station. A mobile station is, for example, a cell phone or a portable device for the transmission of image and / or sound data, for fax, short message service SMS and email transmission and for Internet access. It is therefore a general transmitter and / or receiver unit of a radio communication system.

The invention is described below using the example of a mobile radio system based on the UMTS standard, but without being restricted thereto.

FIG. 1 schematically shows a base station BS according to the invention. The base station BS transmits data D1, D2, ..., DM from M channels Kl, K2, ..., KM simultaneously to a first and a second mobile station UE1, UE2. The first mobile station receives T channels, while the second mobile station UE2 receives M-T channels. The data D1, D2, ..., DM of the M channels K1, K2, ..., KM are each encoded in a coding / decoding unit CD1, CD2, ..., CDM. After encoding, the data D1, D2, ..., DM are forwarded to a transmission power controller PS of a transmission / reception unit SE. The transmitter / receiver unit SE transmits the channels with a transmission power Plout, P2out, ..., PMout to the mobile stations UE1, UE2. The mobile stations UE1, UE2 each transmit so-called TPC bits TPC1, TPC2, ..., TPCT, TPCT + 1, ..., TPCM

(TPC: Transmit Power Control) to the base station BS, with which they request a transmission power increase or a transmission power reduction for the channels received. The transmission power Plin, P2in,..., PMin requested for a channel results for the transmission / reception unit SE or for the transmission power controller PS from the current transmission power of the channel and the TPC bits received from the corresponding mobile station UE1, UE2 TPC1, TPC2, ..., TPCT, TPCT + 1, ..., TPCM.

The transmission power controller PS checks whether a sum of the transmission powers Plin, P2in, ..., PMin requested for the M channels K1, K2, ..., KM exceeds a limit value G.

This limit value G is, for example, a limit value G specified by a radio network controller RNC (radio network controller) networked with a plurality of base stations. Of course, the limit value G can also be a maximum transmission power with which the transceiver unit SE of the base station BS is in the working range of a used power amplifier can send. In this case, the limit value G is not communicated by the radio network controller RNC. If the sum of the transmission powers Plin, P2in, ..., PMin requested for the M channels K1, K2, ..., KM exceeds the limit value G, the transmission power controller PS sets the individual transmission powers Plout, P2out, ..., PMout in Dependency on a transmitter-side property of the respective channel K1, K2, ..., KM in such a way that the sum of the transmission powers Plout actually used for transmission,

P2out, ..., PMout is less than or equal to the limit value G. -

In a first exemplary embodiment, which is shown schematically in FIG. 2, the transmitter-side property of the respective channel is the type of the transmitted data. The time course of the transmission powers actually used for different types of data is shown in a diagram. The transmission power controller PS distinguishes, for example, between control data CO, which are required for perfect data transmission, real-time data RT and non-real-time data NRT. A transmission power Sco of the control data CO is dotted with vertical lines, a transmission power S _{RT of} the real-time data RT is dotted and a transmission power S _{NR of} the non-real-time data NRT is marked with diagonal lines. A fixed value for the transmission power So is set for the control data, since the data transmission can only be maintained if the control data are received by at least one mobile station. The transmission powers of the real-time data RT and the non-real-time data NRT are set variably.

Control data CO are on control channels, such as. B. a broadcast channel (BCCH), a forward access channel (FACH), a paging channel (PCH), a common pilot channel (CPICH) or a synchronization channel (SCH).

The limit value G of the sum of the requested transmission powers is not exceeded during a first, third and seventh time interval tl, t3 and t7, ie in the diagram transmission power is still available between the transmission power S _{NRT of} the non-real-time data NRT and the limit value G. The transmission power actually used for data transmission is therefore the transmission power requested for the different types of data CO, RT, NRT.

In a second time interval t2, however, the limit G is exceeded by the sum of the requested transmission powers. The control data CO will continue to be fixed Transmitted power S _∞ , and the requested transmit power is used for the real-time data RT, since these are time-critical and should receive the requested transmit power if possible. However, the transmission power controller PS sets the transmission power of the non-real-time data NRT only so large that the sum of all transmission powers Sco _* - S _RT , S _{NRT is} equal to the limit value G. In a later fourth time interval t4, the transmission power of the various types of data CO, RT, NRT is set by the transmission power controller PS in the same way as described for the second time interval t2.

In a fifth time interval t5, the sum of the fixed transmission power S _C o of the control data CO and the requested transmission power of the real-time data RT is greater than the limit value G. The transmission power S _{RT of} the real-time data RT is therefore only set so high that the Sum of the transmission power Sco of the control data CO and the transmission power S _{RT of} the real-time data RT is equal to the limit value G. The Niσht real-time data NRT, which are not time-critical and therefore do not have to be transmitted continuously, are not transmitted during the fifth time interval t5.

As long as there is data for transmission in the base station, in particular during a sixth time interval tβ, the transmission powers S _C0 - S _RT , S _{NRT are set} by the transmission power controller PS in the above-described dependence on the exceeding of the limit value G by the requested total powers of the transmission powers S. _C o ^ S _RT , S _{NRT of} the different types of data CO, RT, NRT.

In a second exemplary embodiment, shown schematically in FIG. 3, the base station transmits during the first Ten to seventh time intervals tl, t2, t3, t4, t5, t6, t7 in the same manner as that described for the first exemplary embodiment with reference to FIG. 2. In the second exemplary embodiment, however, the transmission power controller PS takes into account the type of the transmitted channels as a property on the transmitter side.

A transmission power S _C c of control data CO transmitted via so-called “common channels” CC is with vertical lines, a transmission power S _DCH of so-called “dedicated channels”

DCH is dotted and a transmission power S _DSCH from so-called “downlink shared channels” DSCH is marked with diagonal lines. A fixed value for the transmission power S _C c is set for the common channels CC, since the data transmission can only be maintained if the control data CO transmitted via the common channels CC are received by at least one mobile station. The transmission powers of the dedicated channels DCH and the downlink shared channels DSCH are set variably. The downlink shared channels can in particular be so-called “high-speed downlink shared channels "(HS-DSCH) act.

Different services are usually transmitted via different types of channels. Since DCH can transmit all types of services via dedicated channels

(eg time-critical services such as voice and video transmissions with high data rates or non-time-critical services such as software transmissions), the transmission power controller PS Dedicated Channels DCH treats them like the real-time data RT in FIG. 1, but without checking whether time-critical services are actually used be transmitted. Downlink shared channels DSCH are usually not time-critical services such as background services, interactive services or transmit so-called "streaming services". A streaming service starts at a receiver received by this service before all data is loaded, ie while the service is being executed, the required data is continuously loaded (eg streaming) Streaming video). Streaming services are only time-critical to a limited extent and are designed in such a way that longer delay times can be tolerated for data transmission than with time-critical services. The transmission power controller PS therefore treats downlink shared channels DSCH like the non-real-time data NRT, but without checking what kind of service is actually being transmitted.

In addition or as an alternative to a distinction between dedicated channels DCH and downlink shared channels DSCH, the transmission power controller PS can of course also take service quality parameters into account when determining the transmission powers of the M channels, such as a so-called “allocation / retention priority”, a “traffic handling priority” or a "transfer delay" (Chapter 6.4.3 of the technical specification 23.107v5.8.0 of the 3GPP [3rd Generation Partnership Project]).

In a third exemplary embodiment, shown schematically in FIG. 4, the base station BS transmits to the two mobile stations UE1, UE2 on six channels DCH1, DCH2, DCH3, DCH4, DCH5, DCH6. Overall, the base station can provide a maximum transmission power of 20 watts for all six channels DCH1, DCH2, DCH3, DCH4, DCH5, DCH6. This limit value of 20 watts was specified for the base station BS by the radio network controller RNC. Of course, in another embodiment, this limit can also be the maxi Male transmit power correspond to which the base station BS can radiate due to its construction.

The first mobile station UE1 receives a first channel DCH1 and requests an increase in transmission power to 22 watts by means of a TPC bit, while 0.44 each for the further five channels DCH2, DCH3, DCH4, DCH5, DCH6 received by the second mobile station UE2 Watts can be requested. With a transmission power of 0.44 watts, a setpoint value, for example 10 ^{~ 3,} specified by the base station BS for a block error rate BLER can be achieved in the mobile station. Alternatively, the setpoint of the block error rate BLER of the base station BS can also be known in that certain setpoints of the block error rate are fixed in the radio communication system, for example depending on the type of channel or the type of data being transmitted.

The transmission power controller PS now calculates how the block error rate BLER in the first channel DCH1 and in the other five channels DCH2, DCH3, DCH4, DCH5, DCH6 and how the

Sum of the block error rates of all channels DCH1, DCH2, DCH3, DCH4, DCH5, DCHβ depends on a transmission power used for the first channel DCHl. The corresponding block error rates BLER are shown in FIG. 4. The same value is assumed in this exemplary embodiment for the transmission power of the five further channels DCH2, DCH3, DCH4, DCH5, DCHβ.

The transmission power controller PS determines a value of 17.8 watts as the transmission power of the first channel DCH1, since the sum SUM of the block error rates has a minimum for this transmission power. The remaining transmit power of 2.2 watts is transferred to the other five channels DCH2, DCH3, DCH4, DCH5, DCH6 distributed. This means that the whole

Transmission quality of all channels DCH1, DCH2, DCH3, DCH4,

DCH5, DCH6 reached an optimal value with the transmission powers set in this way. Each channel DCH1, DCH2, DCH3, DCH4,

DCH5, DCH6 receive less transmission power than originally requested and thus also a lower block error rate

BLER than desired, but overall this is for all channels

DCHl, DCH2, DCH3, DCH4, DCH5, DCH6 the common optimum of

Transmission powers have been set.

Of course, the transmission power controller PS can also perform calculations in which the transmission power remaining up to the maximum transmission power of 20 watts is distributed differently to the further five channels DCH2, DCH3, DCH4, DCH5, DCH6. In this case, the transmission power is reduced for some of the five further channels, while other of the five further channels receive more transmission power than before according to the request.

The transmission power controller can of course also optimize the transmission powers in such a way that the transmission power is varied by at least two channels, while the remaining transmission power is distributed over the further channels. Such an optimization is carried out, for example, with reference to the third exemplary embodiment when two channels DCH1, DCH2 request 11 watts each and the further four channels DCH3, DCH4, DCH5, DCHβ each request 0.54 watts.

In an embodiment not shown, the transmission power controller differentiates the type of channels between the data rates that use the channels transmitted by it. It treats channels with high data rates like real-time data RT and channels with low data rates like non-real-time data NRT. A control device, for example a radio network controller of the radio communication system, can specify which data rates are considered high or low.

A base station BS can have a plurality of transmission / reception units SE, each with a transmission power controller PS. Of course, a common transmission power controller can also be used for all transmission / reception units of the base station BS. This common transmission power controller is advantageously integrated in a switch unit, which distributes data encoded by means of coding / decoding units to the individual transmission / reception units.

The invention can also be carried out advantageously if a common limit value for the transmission power is not used for all transmitted channels. Instead, the channels can be grouped into groups of channels, and an individual limit is used for each group. In this way, different limit values can be used, for example, for different traffic classes (e.g. voice services, interactive services or streaming video). The transmission power of each channel of the group is then set within the groups depending on a transmitter-side property of the corresponding channel.

Claims

claims

1. Method for controlling transmission power (Plout, P2out, ..., PMout; Sccc SDCH, SD _S CH, 'S _C OS _RT , S _N R _T ) of at least two channels transmitted simultaneously by a transmitting station (BS) ( Kl, K2, ..., KM; CC, DCH, DSCH; DCHl, DCH2, DCH3, DCH4, DCH5, DCH6), where if a sum for the channels (Kl, K2, ..., KM; CC, DCH, DSCH; DcHl, DCH2, DCH3, DCH4, DCH5, DCH6) requested transmission services (Plin, P2in, ..., PMin) exceeds a limit value (G), the transmission power of each channel depending on a transmitter-side property of the corresponding channel is set so that the sum of the transmission powers (Plout, P2out, ..., PMout; S _c , SDCH, S _DSC H; S _CO , S _RT , S _NRT ) is less than or equal to the limit value (G) ,

2. The method according to claim 1, in which the current transmission power when the limit value (G) is exceeded by the sum of the requested transmission powers is used as the transmitter-side property of the corresponding channel (DCH1, DCH2, DCH3, DCH4, DCH5, DCH6).

3. The method according to claim 2, wherein the transmission power of the channel (DCHl) with the largest current transmission power is reduced more percentage than the transmission power of the other channel (DCH2, DCH3, DCH4, DCH5, DCH6).

4. The method as claimed in claim 3, in which the transmission power of the other channel (DCH2, DCH3, DCH4, DCH5, DCH6) is either activated or increased.

5. The method according to claim 1, wherein as a sender property of the corresponding channel (Kl,

K2, ..., KM) the type of data transmitted is used.

6. The method according to claim 5, in which a distinction is made between real-time (RT) and non-real-time data (NRT) as the type of data transmitted.

7. The method according to claim 1, in which the type of the respective channel (CC, DCH, DSCH) is used as the transmitter-side property.

8. The method according to claim 7, wherein the type of the respective channel (CC, DCH, DSCH) relates to the respective data rate.

9. Sending station (BS)

- with means (SE) for the simultaneous transmission of at least two channels (Kl, K2, ..., KM; CC, DCH, DSCH; DcHl, DCH2, DCH3, DCH4, DCH5, DCH6), - with means (PS) for Determine if a sum for the

Channels (Kl, K2, ..., KM; CC, DCH, DSCH; DcHl, DCH2, DCH3, DCH4, DCH5, DCH6) requested transmission power exceeds a limit (G), and with means (PS) for setting the transmission power each - The channel as a function of a transmitter-side property of the corresponding channel such that the sum of the transmission powers (Plout, P2out, ..., PMout; S _C CS _{DH »} - S _DSCH / S _CO S _RT , S _NRT ) is less than or equal to the limit (G).