JP2005012605A - Terminal device requesting download transmission power control, download transmission power control system and method requesting for download transmission power control - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minutely control a transmission power even to each transport channel in a system constituted of a base station and a mobile-body terminal. <P>SOLUTION: In a terminal device connected to a plurality of communication channels discretely power-controlled by the base station, the terminal device has a target signal-to-interference ratio computer 35 computing the target signal-to-interference ratio of an object channel on the basis of reception error rates at every reception transport channel and the priority informations of a plurality of kinds of the transport channels, and a signal-to-interference ratio comparison section 36 comparing the actual measured-signal-to-interference ratio of the object channel and the target signal-to-interference ratio of the object channel. The variation of the download transmission power of the object channel is required of the base station by the result of the comparison. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method or system for controlling transmission power of a communication channel sharing a traffic channel for each subscriber in a wireless communication system.
[0002]
[Prior art]
First, downlink transmission power control in a W-CDMA (Wideband Code Division Multiple Access) system will be described.
In a W-CDMA system, in order to accommodate a large number of terminals in the system, a target communication quality is given to each terminal, and the terminal requests a minimum transmission power required to satisfy the required quality. A control function is required. This downlink power control is composed of a double loop, and one of the loops compares the reception SIR (signal-to-interference ratio) (or the corresponding reception level) with a reference value, and increases the downlink transmission power at high speed. / Inner loop control that requires a decrease. The control for updating the SIR reference value is referred to as Outer loop (outer loop) control. In the transmission power control according to the prior art disclosed in Patent Document 1, when the communication qualities of a plurality of physical channels are different, the transmission power is controlled such that the communication qualities of the respective channels are satisfied. In this control, each communication quality is measured / recognized, an incremental offset value from the reception power at the time of measurement is notified to the transmission side, and the transmission power is controlled based on each value.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-69077
[Problems to be solved by the invention]
The conventional technology is configured as described above, and transmission power can be controlled for each physical channel. However, these physical channels are further divided into a plurality of transport channels (hereinafter referred to as TrCH). In addition, when the target quality is controlled for each TrCH, there is a problem that each of the TrCHs cannot be finely controlled unless there is a voluntary request from the terminal.
Furthermore, there is a problem in that the terminal requests excessive power from the base station, which reduces the number of accommodated terminals per base station.
[0005]
The present invention has been made in order to solve the above-described problem. The terminal works to control transmission power finely for each transport channel. It also requests appropriate power control from the base station and tries to contribute to increasing the terminal capacity.
[0006]
[Means for Solving the Problems]
A downlink transmission power control requesting terminal device according to the present invention is a terminal device connected to a plurality of communication channels for a communication channel whose power is individually controlled by a base station.
A target signal-to-interference ratio calculation unit that calculates a target signal-to-interference ratio of a target channel based on a reception error rate for each reception transport channel and priority information of multiple types of transport channels, and actual measurement of the target channel A signal-to-interference ratio comparing unit that compares the signal-to-interference ratio and the target signal-to-interference ratio of the target channel;
Based on the comparison result, the base station is requested to increase or decrease the downlink transmission power of the target channel.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Although the base station directly controls the downlink power, the required power is requested from the terminal, and the method or apparatus for requesting the appropriate downlink transmission power that can maintain the quality and increase the number of channels without being excessive quality. Will be explained.
An overall configuration diagram of the system is shown in FIG. In the figure, a mobile terminal apparatus 10 communicates with a base station 20 through a number of physical radio channels prepared. Further, the base station is managed by the base station control device 30 and is connected to the switching center 40. The exchange 40 communicates with other fixed terminals, telephones, or mobile terminal devices through the network 50.
In more detail, the mobile terminal apparatus 10 further divides one radio channel, is assigned a division, and as a result, communicates with the base station 20 while sharing the radio channel.
FIG. 1B is a diagram showing an overall configuration of a mobile terminal apparatus having an outer loop function. The mobile terminal device includes an antenna 1 that receives radio waves in space, a radio unit 2 that amplifies received power in a high frequency band, and transmits a transmission signal to the antenna 1; demodulation / decoding of received radio waves; and transmission data A baseband unit 4 that performs modulation / spreading, a terminal interface unit 5 that connects devices such as a microphone, a speaker, and a PDA, and a communication control unit 3 that connects these to control data flow and communication.
The part to which the present invention is applied is the communication control unit 3, and in particular, it is a technique of downlink transmission power control. For the description of the present invention, the configuration of the communication control unit 3 in the mobile terminal device and its downlink transmission power control method will be described.
[0008]
FIG. 2 is a diagram showing a detailed configuration of the communication control unit 3 of the mobile terminal device 10. In the figure, the demodulator 31 demodulates the radio frequency signal received by the radio unit 2, inputs the demodulated received data to the SIR measuring unit 32, and receives the downlink DPCCH and DPDCH received data to the decoder 33. input. The reception signal decoded by the decoding unit 33 is output to the necessary part as reception data. Further, the number of receptions and the number of reception errors for each reception transport block (hereinafter referred to as TB) are measured by the measurement unit 34 and output as a reception error rate for each TB. The determination unit 38 determines and outputs the priority order of a plurality of TrCHs as priority order information based on the target quality for each transport channel (hereinafter referred to as TrCH) input from the upper layer. In principle, TrCH with high target quality obtains high priority, but the user can also specify it in particular. The TARGET SIR (target signal-to-interference ratio) calculation unit 35 sets the TrCH whose priority is set high based on the priority information obtained from the determination unit 34 out of the reception error rates for each TrCH obtained by the measurement unit 34. The reception error rate is extracted, and the SIR target value (Target SIR) for obtaining the TrCH reception quality instructed by the mobile terminal device from the higher order is updated from the reception error rate of this high priority TrCH, and output to the SIR comparison unit 36 To do.
The SIR measurement unit 32 measures the SIR and outputs it to the SIR comparison unit 36. The SIR comparison unit 36 compares these two inputs, and if the SIR reference value is larger than the SIR measurement value, it requests the base station 20 to increase the transmission power, and conversely, the SIR measurement value is greater than the SIR reference value. If larger, the base station 20 is requested to reduce the transmission power. That is, the SIR comparison unit 36 outputs the comparison result to the downlink transmission power control information generation unit 37, and the downlink transmission power control information generation unit 37 outputs this information to the radio unit 2 via the modulation unit 41. Of course, the modulation unit 41 encodes the transmission data by the encoding unit 39, and similarly transmits the transmission data.
[0009]
An outline of downlink transmission power control will be described with reference to FIG.
In FIG. 3, the weak electric signal received by the antenna 1 in FIG. 1 is RAKE-received and amplified by the radio unit 2 and the amplified electric signal is sent to the baseband unit 4. The baseband unit 4 demodulates and decodes the electrical signal in order to extract information from the electrical signal.
In the downlink power control in the mobile terminal device, for example, a process for requesting the base station to increase or decrease the power so as to achieve the defined communication quality represented by the reception error rate is required.
In order to realize this process, two loop controls are used, which are referred to as inner loop (inner loop) control and outer loop (outer loop) control, respectively. In the inner loop control, a power request is made so that the SIR (Signal / Inference Ratio; signal-to-interference ratio) of the dedicated channel (hereinafter referred to as DPCH) converges to the control target SIR (hereinafter referred to as Target SIR). Do it. That is, in the detailed configuration of FIG. 2, as an essential point of the inner loop, the SIR measurement unit 32, the SIR comparison unit 36, and the downlink transmission power control information generation unit 37 are configured, and a power increase / decrease request is performed by a loop including the base station. . This control is performed in slot units, and is evaluated 1500 times per second. The Target SIR that is the control target value of the inner loop is determined by the outer loop control.
[0010]
In Outer loop control, when demodulating and decoding a received signal, a reception error rate in units of transport blocks (hereinafter referred to as TB), that is, Target SIR is used to converge the communication quality to a target value. decide. That is, in the configuration of FIG. 2, the target SIR value is determined by the measurement unit 34, the determination unit 38, and the Target SIR calculation unit 35. Then, it is compared by the SIR comparison unit 36, and the two loops are combined to make a total downlink transmission power increase / decrease request.
[0011]
The downlink transmission power control in the mobile terminal device is control for converging to a request state for a base station whose communication quality is not too much or insufficient by two loop controls as described above. TB is obtained for each transport channel (TrCH), and generally the target quality is different. In addition, the downlink transmission power control to the base station is controlled only by increasing / decreasing the transmission power, and the influence thereof extends to all TrCHs. For this reason, it is not easy to simultaneously control the quality of each of the plurality of TrCHs so as to satisfy all the required standards. According to the following method, control is performed so that a plurality of TrCHs in a mobile terminal device have values close to their respective target communication qualities.
That is, firstly, under the use of a plurality of TrCHs, in consideration of the data flow rate / line method for each different TrCH, transmission power control can be realized relatively stably (from high data reception frequency). In order, control priority is provided, and when the target quality of all TrCHs is not satisfied at the same time, downlink transmission power control is performed using a correction function using the priority.
Second, considering the influence of the number of accommodating stations in the W-CDMA system, in addition to the above-described prioritized TrCH control, the channel that has obtained an excessive quality is monitored, and an excessive downlink transmission power request is made. Get a relaxed control scheme.
[0012]
In the present embodiment, an apparatus or a method having a function for determining the priority order of TrCHs to be subjected to downlink transmission power control and a function for monitoring the communication quality of TrCHs with priorities and determining the Target SIR will be described. To do.
The function of determining the priority order of TrCHs to be subject to downlink transmission power control is to select a TrCH to be controlled mainly depending on the number and format of TrCHs used by the call type, and for other TrCHs that can be controlled. This is a function for determining the priority order of TrCHs to be applied according to the type and parameter, and is all performed by the terminal control unit 3.
[0013]
The function for determining the Target SIR is a function for monitoring the downlink TrCH of each frame and determining the Target SIR according to the communication quality. This function gives a difference value for obtaining a Target SIR value in the next frame section with respect to a Target SIR value in a certain frame section. The calculation of the difference value is roughly determined by two indexes. First, the reception quality of TrCH to be controlled, for example, the number of receptions for each transport block (TB) received for each transport and the reception error rate are measured, and the Target SIR value is set so that this becomes equal to the target value. To control. Next, the communication quality of TrCHs other than the TrCH to be controlled is measured, and the target SIR value determined by the TrCH to be controlled is corrected when there is a difference that exceeds the allowable value for each target quality. To do. In other words, a TB reception error occurrence interval is derived for each TrCH based on the target communication quality, and thresholds for insufficient quality determination and excessive quality determination are determined. When each threshold is exceeded, the correction value correction amount in the Target SIR correction process is changed. All of this is also performed by the terminal control unit 3.
On the other hand, the base station 20 performs transmission power control of the corresponding radio channel.
With these functions, the reception quality of TrCH to be controlled mainly is satisfied with priority, and the communication quality of all TrCHs can be obtained satisfactorily.
[0014]
The conceptual configuration of the overall system of the apparatus having the above functions is as shown in FIG. 1, and the outline of the operation is as described above. However, specifically, the communication control unit 3 has a function of controlling the operations shown in FIGS.
First, a function for determining the priority order of TrCH (hereinafter referred to as TrCH priority order) to be subjected to downlink transmission power control will be described with reference to FIG. This is activated when the TrCH configuration is changed.
S11: TrCHs that cannot be used for downlink transmission power control are excluded from control targets. The corresponding TrCH is as follows.
(A) Not activated (b) Target reception quality designation is “Invalid” (c) No CRC bit S12: Circuit Switch (hereinafter abbreviated as CS) TrCH existence is checked.
S13: If there is a TrCH of CS, priorities are set in descending order of the required quality from the TrCH (in order of small target BLER value).
S14: The presence of TrCH in Packet Switch is checked.
S15: If there is a Packet Switch TrCH, priorities are set in the order from the highest required quality of the TrCH (in the order of smaller target BLER values).
S16: Prioritize the remaining Dedicated Control Channel (DCCH) in descending order of target communication quality.
[0015]
Next, a function for determining the Target SIR using the TrCH priority order obtained here is shown in FIG. 5 as a Target SIR update processing flow, and the operation will be described using this. This is executed for each frame when data can be received on the TrCH having the highest priority.
S21: Target SIR is controlled for each TTI of the TrCH having the highest priority among TrCHs to be subjected to transmission power control. Therefore, it is checked whether or not there is a received TB number.
S22: When there is a reception TB, it is checked whether or not there is a CRC error in the reception TB of the TrCH subject to transmission power control.
S23: If a CRC error occurs in TTI, ΔSIR_up is added to TargetSIR.
S24: Otherwise, it is subtracted by ΔSIR_down.
Also, if there is no received data, the Target SIR is not updated.
[0016]
Here, ΔSIR_down is given by the following (formula 1) using the target communication quality of the TrCH to be controlled (here, it is assumed that the block error rate (BLER) is a reception error rate in units of transport blocks). .
ΔSIR_down = ΔSIR_up × BLER × α (Formula 1)
α = (Number of received TBs of TrCH with highest priority) ÷ (Maximum number of received TBs of TrCH with highest priority)
ΔSIR_up is a reception power increase command value when a reception error occurs, and can take an arbitrary value, but is often set to about 1 dB, for example.
S25: Clear the transmission power increase / decrease request flag.
S27: The received TB is investigated for an error. This is because the CRC error occurrence interval of each TrCH is used as a quality index.
S28: The quality is estimated from the generation interval from the previous CRC error. If the threshold is not exceeded, the process branches to S29, and if not, the process branches to S30.
S29: Considering that the corresponding TrCH is insufficient in quality, the transmission power increase request flag is set.
S30: The quality is estimated from the occurrence interval from the previous CRC error. If the threshold is exceeded, the process branches to S31, and if not, the process branches to S32.
S31: Considering that the quality of the corresponding TrCH is excessive, a transmission power reduction request flag is set.
S32: It is determined whether or not the transmission power is increased. If it is decreased, the process branches to S35. Otherwise, the process branches to the end of the Target SIR update process.
S33: Increase the offset value for correction. However, the upper limit is not exceeded.
S34: It is determined whether or not the transmission power is increased. If it is decreased, the process branches to the process of S35, and if not, the process branches to the end of the Target SIR update process.
S35: The offset value for correction is decreased. However, the lower limit is not exceeded.
[0017]
Here, one or both of the following two methods can be applied as a method of correcting the Target SIR values of S33 and S35.
1) Among TrCHs to be controlled, the target communication quality of a TrCH whose communication quality is determined to be excessive is lowered by one step from the indicated value, and the target communication of the TrCH whose communication quality is determined to be largely insufficient Increase the quality one step above the indicated value.
This process is applied in a relatively long period with respect to the frame period to limit the range in which the indicated value is raised or lowered. The steps described here are the minimum resolution of the target communication quality notified from the network side, for example, 0.1 dB.
2) A fixed offset value corresponding to the amount of communication quality error is added to the Target SIR value obtained by the transmission power control function.
The balance of communication quality among a plurality of TrCHs will be described. When the communication quality deteriorates in any of the channels to be controlled by the downlink power control, priority is given to the improvement and maintenance of the communication quality. Therefore, even if any other TrCH becomes excessive quality, its value Is adopted.
In the above methods 1) and 2), as a method for determining TrCH priority, the CS that is always carrying data is given priority, and then PS is selected so that transmission power control by DCCH is performed if none is present. This is a result of selecting a TrCH so that the update rate of the Target SIR is relatively fast because the reception environment of the mobile terminal device changes from moment to moment.
In this way, power control can be performed on the target communication quality of a plurality of TrCHs so that a large communication quality error does not occur in each channel.
[0018]
In the above description, the Target SIR update processing method performed by the communication control unit 3 has been described as having the function of FIG. According to this method, when the TrCH having the highest priority does not receive data, the Target SIR is not updated. Instead, the update frequency of the target Target SIR can be improved by controlling the priority using the reception data of the TrCH to be controlled.
The method of determining the TrCH priority order to be subjected to downlink transmission power control is performed by the method of FIG. The function for determining the Target SIR will be described with reference to FIG.
[0019]
S40: Target SIR is controlled for each TTI of the TrCH having the highest priority among the TrCHs to be subjected to transmission power control.
S41: In the corresponding TTI in S40, the TrCH with received data is searched in order from the TrCH with the highest priority.
S42: Check whether a CRC error has occurred in the received TB in the TrCH first searched for the presence of received data.
S43: As a result, if a reception error occurs, ΔSIR_up is added to TargetSIR.
S44: Otherwise, subtract by ΔSIR_down. However, ΔSIR_down is given by the above equation (1) using the target communication quality of the TrCH.
S45: Clear the transmission power increase / decrease request flag.
S47 to S55 perform the same processing as S27 to S35 of FIG.
[0020]
Originally, power control that satisfies the quality of a plurality of TrCHs should be designed so that when the quality of one channel is satisfied, the quality is uniformly satisfied in other channels. However, this is not the case in reality, and the communication quality deteriorates or the number of channels decreases due to excessive quality. Therefore, this method is effective.
[0021]
【The invention's effect】
As described above, according to the present invention, priority is set for communication that occupies a transport channel in one communication channel, and there is a reception error in communication with a predetermined setting priority, or target communication quality. Therefore, even if the transport channel is mapped to DPDH and the quality target value of each transport channel is different, the control target of the object to be controlled is finely controlled. There is an effect that the quality of communication can be guaranteed. That is, the communication quality can be maintained while increasing the number of accommodated channels.
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration and a configuration of a mobile terminal apparatus in Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a detailed configuration of a communication control unit in the first embodiment.
FIG. 3 is a diagram for explaining a control loop operation in the mobile terminal device in the first embodiment.
FIG. 4 is an operation flowchart showing priority setting operation of transport channel communication performed by a communication control unit in the mobile terminal device.
FIG. 5 is an operation flow diagram showing detection and reference value setting operation of the main transport channel communication to be controlled, performed by a communication control unit in the mobile terminal device.
FIG. 6 is an operation flow diagram showing another transport channel communication detection and reference value setting operation performed by the communication control unit in the mobile terminal device.
[Explanation of symbols]
3 communication control unit, 4 baseband unit, 10 mobile terminal device, 20 base station, 30 base station control device, 40 switching center, S11 target narrowing step, step of detecting presence / absence of transport channel communication in S12CS , S13 priority assigning step, S14 detecting presence / absence of transport channel communication in PS, S15 priority assigning step, S21 detecting highest order communication in received TB, S22 CRC error detecting step, S23 Predetermined value adding step, S24 Predetermined value subtracting step, S25 Error number integrating step, S26 Difference detection step with target quality, S27 Correction value adding step, S31 Detecting predetermined communication within reception TB, S32 CRC error detecting step, S33 predetermined value addition step, S34 predetermined Value subtraction step, S35 error number integration step, S36 difference detection step with target quality, S37 correction value addition step.

Claims (9)

For a communication channel whose power is individually controlled by a base station, in a terminal device connected to the plurality of communication channels,
A target signal-to-interference ratio calculating unit that calculates a target signal-to-interference ratio of the target channel based on a reception error rate for each reception transport channel and priority information of the plurality of types of transport channels;
A signal-to-interference ratio comparison unit that compares an actual measurement signal-to-interference ratio of the target channel and a target signal-to-interference ratio of the target channel;
A downlink transmission power control request terminal apparatus that requests the base station to increase or decrease downlink transmission power of the target channel based on the comparison result. The target signal-to-interference ratio calculation unit calculates the target signal-to-interference ratio from the reception error rate of the transport channel designated as the highest priority in the priority information among the reception error rates of the respective reception transport channels. The downlink transmission power control request terminal apparatus according to claim 1, characterized in that it is configured as described above. The target signal-to-interference ratio calculation unit calculates the target signal-to-interference ratio based on the reception error rate of the transport channel with the best actual measurement reception quality among the reception error rates of each reception transport channel. The downlink transmission power control request terminal apparatus according to claim 1, wherein: The target signal-to-interference ratio calculation unit sets priorities in the order of transport channels in which the reception error rate target value becomes higher in order from the transport channel having the lowest reception error rate target value as priority information. 2. The downlink transmission power control request terminal apparatus according to claim 1, wherein a target signal-to-interference ratio is set based on The target signal-to-interference ratio calculation unit sets priority levels in order from the first specific transport channel as priority information in order of the second and third specific transport channels, and sets the target signal based on the priority levels. The downlink transmission power control requesting terminal apparatus according to claim 1, wherein an interference ratio is set. In a communication system comprising a base station control device, a base station and a mobile terminal device, and providing a plurality of wireless communication channels and performing power control of the communication channel by loop control,
Each of the above-mentioned one communication channel is divided into a plurality of transport channels, and priorities are set for communications that occupy the transport channels.
The mobile terminal device detects whether the highest priority communication with the set priority is in a reception transport block and whether there is a reception error or a difference with a target communication quality, and the result is the base station or A communication control unit for notifying the base station controller,
A downlink transmission power control system, wherein the base station performs downlink power control according to a request from the mobile terminal device. As a method of providing a plurality of communication channels and requesting the base station to control the power of the communication channels,
At the terminal, each of the above-mentioned one communication channel is divided into a plurality of transport channels, and priority is set for the communication that occupies the transport channel, and the highest order communication of the set priority is received. Checking if it is in the transport block and there is a reception error or a difference from the target communication quality;
And a step of increasing / decreasing the downlink power request based on the error or the quality difference. The terminal is provided with a step of monitoring communication of a plurality of transport channels so that all priority-level communications to be controlled are within a predetermined value with respect to a predetermined target communication quality. 8. The downlink transmission power control request method according to 7. The terminal comprises: setting a control target communication instead of the highest level communication in the transport channel; and monitoring whether the set control target communication is at a predetermined target communication quality. Item 8. The downlink transmission power control request method according to Item 7.

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