JP2008011002A - Transmission power control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission power control apparatus capable of efficiently and properly executing transmission power control of communication by A-DPCH. <P>SOLUTION: The transmission power control apparatus for communication, that uses using the A-DPCH of a mobile station apparatus receiving the HSDPA service under the W-CDMA system, sets a target SIR threshold 1 for satisfying required receiving quality to received blocks comprising 0-bit data, sets a target SIR threshold 2 for satisfying the required reception quality to received blocks comprising the DCCH, decreases the target SIR by a prescribed amount b, when CRC-OK is consecutively detected for a prescribed number of received blocks, controls the lower limit of the target SIR, when receiving blocks comprising 0-bit data, to be the target SIR threshold 1, and updates the target SIR to be the target SIR threshold 2, when a CRC error is detected at any received block. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

   The present invention relates to a transmission power control apparatus, and more particularly, to transmission power control of communication using an associated dedicated physical channel A-DPCH of a mobile station apparatus receiving a high-speed downlink packet transmission HSDPA service under a W-CDMA scheme. Therefore, it is preferable.

In W-CDMA, in order to further increase the downlink speed, a high-speed downlink packet access HSDPA (High Speed) for adding a new downlink (channel for packet transmission) is used.
Down Link Packet Access) has been proposed. In this HSDPA, HS-PDSCH (High Speed Physical Downlink Shared Channel) is a downlink shared communication channel for packet transmission, and is shared by a plurality of users between a mobile station and a base station. HS-SCCH (Shared Control Channel of HS-PDSCH) is a downlink shared control channel, and transmits resource allocation information (TFRI: Transport format and Resource related information), control information H-ARQ (Hybrid-Automatic Repeat Request), and the like. To do. Furthermore, A-DPCH (Associated Dedicated Phisycal Channel for HS-PDSCH) is an uplink-downlink dedicated individual channel for HSDPA transmission, and transmits pilot signals, TPC (Transmit Power Control) commands, etc. An ACK / NACK signal for a packet from the base station and a CQI (Channel Quality Indicator) signal indicating the modulation method and coding rate of packet data that can be demodulated by the terminal are also transmitted.

  In transmission power control in W-CDMA, a TPC (Transmission Power Control) command is generated so that the SIR (Signal to Interference power Ratio) of the received pilot measured by the mobile station matches the target SIR, and the transmission power control of the base station is performed. And an outer loop that measures the reception quality BLER (Block Error Rate) of received data over a relatively long period of time and updates the target SIR so that the reception quality matches the target quality. By the control.

  FIG. 8 shows an operation timing chart of a conventional typical outer loop control. After starting the communication, the mobile station starts measuring the reception quality BLER of the target TrCH (Transport Channel). In the outer loop control, after receiving a TB (Transport Block) of a certain section (Tmax), the CRC inspection result is referred to. When CRC-NG is not detected, the BLER higher than the target can be achieved and the target SIR is achieved. Is updated to decrease y [dB], and when one or more CRC-NGs are detected, the target SIR is updated to increase x [dB]. In addition, when CRC-NG is reached, a CRC check is performed with the next measurement interval set to Tmax × NG blocks, and thus control is performed so that the reception quality over a long period of time becomes the target quality (BLER).

  By the way, in A-DPCH communication in HSDPA, CRC is also given to 0-bit TB with no data transmitted in the non-transmission section of the control channel DCCH, so that the presence or absence of a CRC error can be checked. In an actual communication environment of HSDPA, a mobile station receives a 0-bit TB in most cases, and is assumed to receive a DCCH when a state change occurs due to a handover or the like. For this reason, it is desired that outer loop control is appropriately performed without gaps by effectively using not only DCCH but also 0-bit TB.

Conventionally, transmission is performed so that the target SIR becomes the minimum SIR necessary for maintaining synchronization by performing accurate transmission power control and measuring the error rate of the received pilot when there is no received DPDCH data. A power control method and apparatus are known (Patent Document 1).
JP-A-2005-5762

  However, when the conventional outer loop control is applied to the A-DPCH of HSDPA, the following problems may occur. That is, since the 0 bit TB generally has better reception characteristics (Ec / No) than the DCCH, if the 0 bit TB is continuously received, the target SIR converges to a low level. As a result, the transmission power of the base station becomes too low, and accordingly, fluctuations in transmission power due to erroneous detection of downlink TPC bits and loss of synchronization due to synchronization word (SW) errors occur. Also, when the mobile station reception is switched from the 0-bit TB to the DCCH, DCCH reception errors due to excessive reduction in transmission power occur frequently, and state transition failures such as handover and rate switching and state mismatch with the base station occur. appear. In addition, when A-DPCH transmission power control is not optimally performed in the mobile station, the base station transmission power per mobile station increases, interference with other users increases, and system capacity decreases.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a transmission power control apparatus capable of efficiently and accurately performing transmission power control of communication using the A-DPCH.

  A transmission power control apparatus according to a first aspect of the present invention is a transmission power control apparatus for communication using an associated dedicated physical channel A-DPCH of a mobile station apparatus that receives a high-speed downlink packet transmission HSDPA service under a W-CDMA scheme. The first target SIR threshold for satisfying the required reception quality for the transport block consisting of 0-bit data of A-DPCH and the required reception quality for the transport block consisting of the dedicated control channel DCCH And a second target SIR threshold value that is higher by a first predetermined amount than the first target SIR threshold value, and an upstream TPC bit is detected when CRC-OK is continuously detected for a predetermined number of received blocks. And lowering the target SIR for generating the second predetermined amount, and the transformer comprising the 0-bit data A lower limit of the target SIR at the time of receiving the data block is controlled as the first target SIR threshold, and the target SIR is updated to the second target SIR threshold when a CRC error is detected for any of the received blocks SIR control means is provided.

  According to the present invention, 0-bit TB can be efficiently received under low transmission power, and the target SIR when a reception error occurs quickly rises to the target SIR threshold value 2, so that the DCCH reception is also promptly appropriate. It can be done.

  In the second aspect of the present invention, the target SIR control means detects the CRC-OK for the next received block after the CRC-OK is continuously detected for a predetermined number of received blocks. The target SIR is lowered by a second predetermined amount. Therefore, the downlink transmission power when 0 bit TB continues is quickly converged to a low level.

  In the third aspect of the present invention, the target SIR control means sets the target SIR to a third predetermined amount when a CRC error is detected for a block received when the target SIR is equal to or greater than the second target SIR threshold. To raise. Accordingly, it is possible to quickly cope with deterioration of the communication environment.

According to a fourth aspect of the present invention, there is provided pilot measurement means for measuring an error rate of the received pilot, and the target SIR control means has a first target SIR threshold value when the error rate of the received pilot exceeds a predetermined threshold value. The target SIR is updated with a threshold value obtained by adding a predetermined offset value to the target SIR.

  By the way, the CRC error is an evaluation of the reception quality based on the received data after the error correction, whereas the error rate of the reception pilot is detected by the modem, and thus represents the reception quality directly connected by the fluctuation of the actual communication environment. ing. According to the present invention, the transmission power control can be performed more quickly and faithfully to the fluctuation of the actual communication environment by adding the threshold offset according to the pilot reception environment to the outer loop control of the target SIR.

  In the fifth aspect of the present invention, the received power of the downlink common pilot channel CPICH is measured, the obtained received power is classified into a plurality of CQI values according to the magnitude, and the CQI values are classified into a plurality of groups. The CQI determination means for providing an offset value corresponding to each class is provided, and the target SIR control means updates the target SIR with a threshold obtained by adding an offset value corresponding to each class to the first target SIR threshold. To do.

  According to the present invention, transmission power control can be performed more quickly and faithfully to changes in the actual communication environment by adding a threshold offset according to the received power (CQI value) of the common pilot CPICH to the outer loop control of the target SIR.

  As described above, according to the present invention, the transmission power of A-DPCH can be reduced and optimized as compared with the prior art, and the reception quality of DCCH including synchronization words and downlink TPC bits can be properly maintained, and handover, rate switching, etc. The process at the time of state transition can be performed smoothly. Further, the reduction in transmission power can contribute to the reduction of interference to other users and the securing of system capacity.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 1 is a block diagram of a mobile station apparatus according to the first embodiment. A first target SIR threshold 1 suitable for reception of a block not including information (0 bit TB) and a block including information (DCCH, etc.) In this case, the target SIR is optimally updated with the second target SIR threshold value 2 suitable for reception of. In this specification, the dedicated physical control channel HS-DPCCH is also referred to as a unit DCCH.

  In the figure, 11 is an antenna, 12 is a radio unit, 20 is a modem (MODEM) that performs transmission / reception signal modulation / demodulation processing, 21 is a despread demodulation unit that despreads the received signal, and 22 is an inner loop control of transmission power. An inner loop processing unit (IN) that performs SIR, 23 is a SIR measuring unit that measures the SIR (Signal to Interference power Ratio) of the received pilot signal, 24 is a SIR comparing unit that compares the measured SIR and the target SIR, and 25 is a measured SIR. And TPC generator for generating uplink TPC bits for making the received SIR close to the target SIR based on the comparison result between the target SIR and the target SIR, 26 is a spread modulation unit for performing spread modulation by multiplexing the TPC bits on the transmission signal, and 30 is transmission / reception data A codec (CODEC) that performs the encoding / decoding processing of the received data, 31 is a decoding unit of the received data, and 32 is a transport block of the received block. -A BTFD (Blind Transport Format Detection) processing unit that blindly detects a mat TF from a predetermined TF pattern using a CRC result, and 33 receives information such as a 0-bit TB according to the BTFD processing result. A data presence / absence determination unit 34a for determining whether a reception block does not include or a reception block including information such as DCCH, and the target SIR update process (corresponding to outer loop control) for obtaining required reception quality based on the determination result of data presence / absence A target SIR updating unit 35 to perform is a coding unit for coding transmission data.

With this configuration, the reception signal from the radio unit 12 is despread and demodulated by the despreading demodulation unit 21 and decoded by the decoding unit 31 to be received data. The transmission data of the mobile station is encoded by the encoding unit 35 and spread-modulated by the spread modulation unit 26 and transmitted to the base station via the radio unit 12. In the inner loop control, the reception SIR of the pilot signal separated and demodulated by the despreading demodulator 21 is measured, and the measured SIR is compared with the target SIR for obtaining the required reception quality, and based on the comparison result A TPC bit is generated and transmission power control of the base station is performed. That is, when the measured SIR is lower than the target SIR, a TPC bit for increasing the transmission power is transmitted, thereby increasing the transmission power of the base station, and when the measured SIR is higher than the target SIR, the TPC bit for decreasing the transmission power is set. Transmit and lower the transmission power of the base station.

  In the outer loop control, the target SIR for obtaining the required reception quality is updated based on the reception signal from the decoding unit 31. That is, the BTFD processing unit 32 determines whether the received block is a block without information (a 0-bit TB composed of 0-bit data and CRC) or a block with information (DCCH or the like) by BTFD processing. The target SIR updating unit 34a updates the target SIR based on the reception quality (CRC inspection result) of these blocks.

  FIG. 2 is a flowchart of the target SIR update process according to the first embodiment, and inputs to this process every time a certain block is received. In step S11, the possible transport format TF is sequentially decoded by the BTFD process for the received block, and the CRC-OK format is processed as the TF of the received block. In step S12, it is determined whether or not the CRC calculation performed in step S11 for the reception block is OK. If CRC-OK, the block counter N is incremented by 1 in step S13. In step S14, it is determined whether or not the block counter N is equal to or greater than the predetermined number of blocks K. If not, the process is exited.

  In this way, when N ≧ K eventually, CRC-OK (reception quality higher than target) is obtained for a predetermined number of blocks K or more, and therefore the target SIR is set to a predetermined amount (b [dB]) in step S15. ) In step S16, it is determined whether the received block is a 0-bit TB without information or a DCCH with information. In the case of 0 bit TB, it is determined in step S17 whether or not the target SIR has fallen below the target SIR threshold value 1 that is optimal for receiving 0 bit TB. On the other hand, if it falls below, the target SIR is returned to the target SIR threshold 1 in step S18, and this process is exited. Therefore, the target SIR when the 0-bit TB is normally received does not fall below the target SIR threshold value 1.

  If it is determined in step S16 that the received block is a DCCH, it is determined in step S19 whether or not the target SIR has fallen below a target SIR threshold value 2 that is optimal for DCCH reception. Exit. On the other hand, if it falls below, the target SIR is returned to the target SIR threshold 2 in step S20, and this process is exited. Therefore, the target SIR when the DCCH is normally received does not fall below the target SIR threshold value 2. For this reason, there is a high possibility that these can be normally received even if the DCCH is continuously received.

  If it is not CRC-OK in the determination in step S13, the block counter N is reset to 0 in step S21. In step S22, it is determined whether or not the target SIR is lower than the target SIR threshold value 2. If the target SIR is lower than the target SIR threshold value 2, the target SIR threshold value 2 is set in the target SIR in step S23, and the process is exited. Thereby, when it is CRC-NG, the target SIR quickly rises to the target SIR threshold value 2, and thus there is a high possibility that the subsequent reception block can be normally received. If it is determined in step S22 that the target SIR threshold value 2 is not below, the target SIR is increased by b [dB] in step S24, and this process is exited. Thereby, there is a high possibility that the subsequent reception block can be normally received.

FIG. 3 shows an operation timing chart of the target SIR update process according to the first embodiment.
After starting communication by HSDPA, outer loop control is started. Normally, reception of the 0-bit TB is continued and CRC-OK continues, so that the target SIR is quickly drawn from the initial value to the target SIR threshold 1 and enters a convergence (steady state). In this state, when the CRC becomes NG, the target SIR is quickly raised to the target SIR threshold 2. Accordingly, there is a high possibility that the next 0 bit TB is normally received. In addition, even when the DCCH is received next, there is a high possibility of normal reception.

  The target SIR threshold 1 is a threshold at which 0-bit TB can be received with the required reception quality (BLER), and the target SIR threshold 2 is a threshold at which the DCCH can be received with the required reception quality (BLER). Statistically determined based on Also, the difference a [dB] between the target SIR threshold 1 and the target SIR threshold 2 results in the ratio of the received power per one desired wave chip to the noise power (Ec / No) between the 0-bit TB and the DCCH. ) To compensate for the difference.

  If the target SIR is the target SIR threshold 2 and CRC-OK continues for a predetermined number k of blocks, in this example, the target SIR is lowered by a predetermined amount (b [dB]) by receiving 0 bit TB normally. Finally, the target SIR threshold value is lowered to 1. Although not shown, if the DCCH is normally received while the target SIR is being lowered to the target SIR threshold value 1, the target SIR is returned to the target SIR threshold value 2 by the process of step S20. Therefore, even if the next DCCH continues, there is a high possibility that this will be received normally, and the block counter N will not be reset. Begins to fall quickly. Therefore, the outer loop signal control can be performed quickly and efficiently.

  Thereafter, in the example of the figure, the DCCH of the 17th block becomes CRC-NG, so the target SIR is raised to the target SIR threshold 2 at a stroke, but the DCCH of the following 18th block is also CRC-NG, Furthermore, it is raised by b [dB]. As a result, the DCCH retransmitted in the 20th block is normally received, and then the target SIR is lowered by b [dB] due to the normal reception of the 0-bit TB up to the 22nd block. Therefore, it is possible to respond promptly and appropriately to unexpected changes (deterioration) in the communication environment (mobile station speed, propagation environment, etc.).

  FIG. 4 is a block diagram of a mobile station apparatus according to the second embodiment, in which the TrCH reception quality (corresponding to BLER) is supplementally estimated from the pilot signal error rate, and correction (offset) is added to the target SIR threshold 1 Is shown. In the inspection by CRC, the reception quality is determined based on the data after error correction, whereas the synchronization word error is the reception quality detected by the MODEM 20, so that information more faithful to changes in the radio environment can be obtained quickly. . Therefore, by adding the determination of the reception quality as MODEM to the reception quality (corresponding to BLER) as a decoder, it is possible to appropriately update the target SIR more quickly and finely.

  The synchronization determination is performed by monitoring the synchronization word pattern (pilot bit) of each slot, thereby determining the initial synchronization when the individual channel is opened and monitoring synchronization during communication. In the present embodiment, correction processing of the target SIR threshold is performed using this synchronization monitoring function. That is, the synchronization word error measurement unit 41 compares the received pilot (synchronization word SW) for each slot detected from the despread demodulation unit 21 with a known synchronization word pattern, and measures the synchronization word error. The DSP 42 calculates a rate matching rate RM, and calculates a synchronization pull-in determination threshold value Qin and a loss-of-synchronization determination threshold value Qout according to the RM. Further, the DSP 42 integrates the number of SW error bits for each frame, compares the number of SW error bits for n frames with the threshold values Qin and Qout using a synchronization establishment time designated from the network and a counter, and The SW normal / SW error is determined.

  FIG. 5 shows an operation timing chart of target SIR update processing based on synchronous word monitoring. When a SW error is detected as the MODEM 20, it is considered that the reception state of the SW bit and the downlink TPC bit is deteriorated due to a significant change in the radio environment or an excessive decrease in the A-DPCH transmission power. With the offset d [dB] added to the target SIR threshold 1 at the update timing, the target SIR update process according to the first embodiment is performed. When the offset d [dB] is added to the target SIR threshold 1, the target SIR threshold 2 is also increased by the offset d [dB] in conjunction with this. Thus, by increasing the transmission power of the A-DPCH, it becomes possible to improve reception of SW and downlink TPC bits.

  Note that a threshold p bit may be provided for the SW error bit number, and an offset d [dB] may be added to the target SIR threshold 1 at the target SIR update timing when the SW error bit number exceeds the p bit. Since the synchronization establishment time designated from the network is in units of 100 ms, the number of SW error bits is accumulated for 10 frames or more. When slot format = 4, the SW bit for each slot is 4 bits. Therefore, when SW error bits are accumulated for 10 frames, the number of SW error bits is 40 bits.

  Since A-DPCH is interleaved with 4 frames, for example, when an offset d [dB] is added to the target SIR threshold 1 at the SIR update timing when SW errors are detected for 4 consecutive frames, and SW errors are detected for 8 consecutive frames By adding the offset e [dB] to the target SIR threshold 1 at the SIR update timing, the target SIR is updated and the A-DPCH transmission power is controlled.

  FIG. 6 is a block diagram of a mobile station apparatus according to the third embodiment, and shows a case where correction (offset) is applied to its own target SIR threshold 1 in accordance with the CQI value reported by the mobile station. In the figure, the SIR measurement unit 45 measures the reception quality during HSDPA communication by the SIR of the downlink common pilot channel CPICH. One CPICH exists in each cell, and is mainly used for channel estimation of a downlink channel, cell search for a mobile station, timing reference for other physical channels in the same cell, and the like.

  The CQI determination unit 46 uses a SIR-CQI conversion table (not shown) to convert the measured SIR into a CQI value of 0 to 30, and the obtained CQI value is reported to the base station via a route (not shown). . Since this CQI value varies and varies depending on the reception environment, preferably, the CQI determination unit 46 obtains a moving average of the reported CQIs, and among the obtained average CQIs, 30-20 is a high CQI, 19-10. Are classified into three classes, with medium CQI and 9-0 as low CQI. The target SIR update unit 34c performs target SIR update processing according to the first embodiment, and performs update control with a value obtained by adding a threshold offset corresponding to the CQI class to the target SIR threshold 1 at that time. When an offset is added to the target SIR threshold 1, the same offset is also added to the target SIR threshold 2.

  An inset (A) in FIG. 7 shows a relationship between an example CQI class and an offset to be added to the target SIR threshold 1. When the average CQI is a high CQI of 30 to 20, the reception state is good, and therefore there is no offset added to the target SIR threshold value 1. On the other hand, in the medium CQI (10 to 19), since the reception environment is deteriorated as compared with the high CQI, an offset f [dB] having a size that compensates for the CPICH_SIR difference is added. Further, since the reception environment is further deteriorated at low CQI (0 to 9) than that at medium CQI, an offset g [dB] having a magnitude that compensates for the difference from that at high CQI is added.

FIG. 7 shows an operation timing chart of the target SIR update process according to the third embodiment. When the moving average value of the CQI changes from a high CQI to a medium CQI, the target SIR update process according to the first embodiment is added to the target SIR threshold 1 with an offset f [dB] added thereto. The transmission power control of the accompanying A-DPCH is performed. In this example, the target SIR threshold 2 increases by f [dB] at the timing when the sixth 0-bit TB is received, but the target SIR is at the timing when the 10th 0-bit TB becomes CRC-NG. The level has risen to the target SIR threshold value 2 + f [dB].

  When the moving average value of the CQI changes from the middle CQI to the low CQI, the target SIR update process according to the first embodiment is performed with the offset g [dB] added to the target SIR threshold 1, A-DPCH transmission power control is performed. Further, when the moving average value of the CQI changes from a low CQI to a high CQI, there is no offset added to the target SIR threshold 1, but the target SIR decreases by b [dB] by t according to the first embodiment. Therefore, it decreases stepwise and promptly.

  In addition, although several embodiment suitable for the said invention was described, it cannot be overemphasized that the structure of each part, control, a process, and these combinations can be variously changed within the range which does not deviate from this invention. .

It is a block diagram of the mobile station apparatus by 1st Embodiment. It is a flowchart of the target SIR update process by 1st Embodiment. It is an operation | movement timing chart of the target SIR update process by 1st Embodiment. It is a block diagram of the mobile station apparatus by 2nd Embodiment. It is an operation | movement timing chart of the target SIR update process by 2nd Embodiment. It is a block diagram of the mobile station apparatus by 3rd Embodiment. It is an operation | movement timing chart of the target SIR update process by 3rd Embodiment. It is a figure explaining a prior art.

Explanation of symbols

11 Antenna 12 Radio Section 20 Modem (MODEM)
22 Inner loop processing section (IN)
26 Spread Modulation Unit 30 Codec (CODEC)
32 BTFD (Blind Transport Format Detection) processing unit 33 Target SIR update unit 41 Synchronization word error (SWE) measurement unit 42 DSP

Claims (5)

In a transmission power control apparatus for communication using an associated dedicated physical channel A-DPCH of a mobile station apparatus receiving a high-speed downlink packet transmission HSDPA service under the W-CDMA scheme,
The first target SIR threshold for satisfying the required reception quality for the transport block composed of 0-bit data of A-DPCH and the required reception quality for the transport block composed of the dedicated control channel DCCH A second target SIR threshold that is a first predetermined amount higher than the first target SIR threshold of
When CRC-OK is continuously detected for a predetermined number of received blocks, the target SIR for generating the uplink TPC bit is lowered by a second predetermined amount, and the transport block including the 0-bit data is received. The target SIR control means for controlling the lower limit of the target SIR at the time as the first target SIR threshold and updating the target SIR to the second target SIR threshold when a CRC error is detected for any one of the received blocks A transmission power control apparatus comprising: The target SIR control means sets the target SIR to the second predetermined amount every time CRC-OK is detected for the next received block after the CRC-OK is detected for the predetermined number of received blocks continuously. The transmission power control apparatus according to claim 1, wherein the transmission power control apparatus is lowered step by step. 3. The target SIR control means increases the target SIR by a third predetermined amount when a CRC error is detected for a block received when the target SIR is equal to or greater than the second target SIR threshold. The transmission power control device described. A pilot measurement means for measuring the error rate of the received pilot;
2. The target SIR control means updates the target SIR with a threshold obtained by adding a predetermined offset value to the first target SIR threshold when the error rate of the received pilot exceeds the predetermined threshold. Transmission power control device. The received power of the downlink common pilot channel CPICH is measured, and the obtained received power is classified into a plurality of CQI values according to the magnitude, and the CQI values are classified into a plurality of groups to correspond to each class. CQI determination means for providing an offset value,
The transmission power control apparatus according to claim 1, wherein the target SIR control means updates the target SIR with a threshold obtained by adding an offset value corresponding to each class to the first target SIR threshold.

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