JP4595587B2 - Mobile communication system, radio base station, and downlink control channel power control method used therefor - Google Patents

Description

  The present invention relates to a mobile communication system, a radio base station, and a downlink control channel power control method used therefor, and more particularly, to a downlink control channel power control method in EUDCH (Enhanced Uplink Dedicated Channel).

  In recent years, in various communication networks, not only a fixed communication network but also a mobile communication network is expected to greatly increase data traffic in the future. HSDPA (High Speed Downlink Packet Access) has been newly specified in Release 5 of 3GPP (3rd Generation Partnership Project) to cope with such an increase in traffic on the downlink (radio base station → mobile station) by downloading from the server, etc. (For example, refer nonpatent literature 1).

  On the other hand, in the uplink (mobile station → radio base station), the specification of an uplink high-speed packet transmission method called EUDCH is currently being developed on 3GPP. Up to now, uplink maximum rate control is performed by an RNC (Radio Network Controller).

  However, in the EUDCH, by controlling this by the radio base station, it is possible to perform high-speed uplink rate control according to fluctuations in the amount of uplink interference. Since the EUDCH can perform higher-speed control, the noise rise (reception-to-noise power) margin can be set smaller, so that an increase in uplink capacity can be expected.

  Further, in EUDCH, HARQ (Hybrid Automatic Repeat Request) technology is introduced between a radio base station and a mobile station, as in HSDPA. As a result, the retransmission delay is suppressed as compared with the retransmission by RLC (Radio Link Control) in the RNC, and the error rate in the physical layer can be set higher (10 to 20%). As a result, effects such as an increase in system throughput and a reduction in transmission delay can be obtained.

  In addition, EUDCH is a higher-level station because “a mobile station can establish a radio link with a plurality of radio base stations”, which is one of the characteristics of the uplink of W-CDMA (Wideband Code Division Multiple Access). A selective diversity effect is obtained by performing selective combining of uplink data in the RNC.

  In the EUDCH technology, E-AGCH (E-DCH Absolute Grant Channel) is one of the downlink physical channels defined in the current specifications. Here, E-DCH is an abbreviation for Enhanced Dedicated Channel, and is a transport channel added in EUDCH.

  This control channel includes information on the maximum transmission rate and power information allowed for the mobile station. Serving E-DCH Cell [A cell that controls E-DPDCH (Enhanced Dedicated Physical Data Channel) rate, power, etc. of a mobile station using E-AGCH] is used as a radio base station using E-AGCH. The mobile station performs uplink rate / power control, and in some cases, transmission timing control. Therefore, E-AGCH needs to be able to be received at a sufficient level for a mobile station that performs EUDCH.

"High Speed Downlink Packet Access (HSDPA); Overall description; Stage 2 (Release 5)" (3GPP TS 25.308 V5.4.0 (2003-03))

  In the above-described conventional mobile communication system, as the simplest method for E-AGCH power control, there is a method of fixedly allocating sufficient downlink power reaching the cell edge. In this method, downlink power resources are wasted. The problem of end up occurs.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems and suppress a waste of downlink power resources that are not desirable in a W-CDMA system, a radio base station, and a downlink control channel power control method used for them. Is to provide.

A mobile communication system according to the present invention uses an EUDCH (Enhanced Uplink Dedicated) using an E-AGCH (E-DCH (Enhanced Dedicated Channel)) that is a downlink physical channel in an uplink from a mobile station to a radio base station. A mobile communication system for performing uplink high-speed packet transmission called “Channel”,
The radio base station comprises means for monitoring the downlink radio link quality state of the mobile station that is the transmission destination of the E-AGCH, and means for performing power control of the E-AGCH based on the monitoring result ,
The mobile station includes a function of feeding back an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from a decoding result of the E-AGCH to the own station to the radio base station using an uplink physical control channel. ,
The radio base station performs power control of the E-AGCH for the mobile station based on a CRC result obtained from the mobile station .

The radio base station according to the present invention is called EUDCH (Enhanced Uplink Dedicated) using E-AGCH (E-DCH (Enhanced Dedicated Channel) Absolute Grant Channel), which is a downlink physical channel, in the uplink from the mobile station. A radio base station that performs uplink high-speed packet transmission,
Means for monitoring the downlink radio link quality state of the mobile station that is the transmission destination of the E-AGCH, and means for performing power control of the E-AGCH based on the monitoring result ;
A function in which the mobile station feeds back an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from a decoding result of the E-AGCH to the mobile station using the uplink physical control channel; ,
The E-AGCH power control for the mobile station is performed based on the CRC result obtained from the mobile station .

The downlink control channel power control method according to the present invention uses E-AGCH [E-DCH (Enhanced Dedicated Channel) Absolute Grant Channel], which is a downlink physical channel, in the uplink from a mobile station to a radio base station. A downlink control channel power control method used for a mobile communication system that performs uplink high-speed packet transmission called Enhanced Uplink Dedicated Channel),
The radio base station performs a process of monitoring a downlink radio link quality state of the mobile station that is a transmission destination of the E-AGCH, and a process of performing power control of the E-AGCH based on the monitoring result ,
The mobile station feeds back an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from the decoding result of the E-AGCH to the mobile station using the uplink physical control channel,
The radio base station performs power control of the E-AGCH for the mobile station based on a CRC result obtained from the mobile station .

  That is, the mobile communication system of the present invention performs optimal transmission control of E-AGCH [E-DCH (Enhanced Dedicated Channel) Absolute Channel Control], which is a downlink physical channel used in EUDCH (Enhanced Uplink Dedicated Channel). In this way, it is possible to suppress the waste of downstream power resources.

  More specifically, in the mobile communication system of the present invention, the radio base station monitors the downlink radio link quality state of each or a plurality of mobile stations that are transmission destinations of E-AGCH by the following control method. The base station performs optimum E-AGCH power control for the mobile station.

  In the case of the first control method, the mobile station uses an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from the decoding result of E-AGCH to itself, for example, E-DPCCH (E-DCH Dedicated Physical). It has a function of feeding back to the radio base station using an uplink physical control channel called “Control Channel”, and the radio base station performs E-AGCH power control on the mobile station based on the obtained CRC result. There are two methods for performing feedback using E-DPCCH.

  The first method indirectly notifies the radio base station whether or not the E-AGCH has been correctly received by always transmitting the E-DPCCH at a predetermined timing after the E-AGCH has been correctly decoded. It is a method to do. In the second method, OK / NG for CRC determination of E-AGCH is mapped onto E-DPCCH as 1-bit information and notified.

  Next, in the case of the second control method, if the HS-DSCH (High Speed-Downlink Shared Channel) Serving Cell and Serving E-DCH Cell are always the same, the HS-DPCCH received from the corresponding mobile station The transmission power of E-AGCH is calculated using CQI (Channel Quality Indicator). The method for calculating the power value of E-AGCH from CQI can be easily implemented by, for example, drawing a lookup table calculated in advance. In this case, the first control method can be used together. By performing power correction using the first control method, it is possible to improve the accuracy of E-AGCH power control.

  It is also possible to use a common E-AGCH for a plurality of mobile stations. In this case, regardless of which of the first control method and the second control method is used, the maximum value (or average value) of the power values required among the mobile stations in the same group is transmitted by E-AGCH. Use as power.

  In the mobile communication system of the present invention, power consumption of the E-AGCH is controlled by adding only a few information bits and control, or by adding control, thereby suppressing unnecessary power consumption in the downstream in the W-CDMA system. It becomes possible.

  According to the present invention, by adopting the configuration and operation as described below, it is possible to obtain the effect that it is possible to suppress the waste of downstream power resources, which is undesirable in the W-CDMA system.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile communication system according to an embodiment of the present invention. In FIG. 1, between a mobile station 1 and a radio base station 2 which is a HS-DSCH (High Speed-Downlink Shared Channel) Serving Cell and a Serving E-DCH (Enhanced Dedicated Channel) Cell, FIG. Are used. However, common channels such as CPICH (Common Pilot Channel), P-CCPCH (Primary Common Control Physical Channel), and S-CCPCH (Secondary Common Control Channel CPC) are not described.

  The dedicated physical channel is a physical channel that has been conventionally used in a W-CDMA (Wideband Code Multiple Access) system. In order to perform HSDPA, the added physical channels include HS-PDSCH (High Speed Physical Downlink Shared Channel), HS-SCCH (High Speed Shared Control Channel), HS-DPCCH (High Speed Shared Control Channel), and HS-DPCCH (High Speed Shared Control Channel). There is a physical channel. The HS-DPCCH contains downlink radio link quality information called CQI (Channel Quality Indicator).

  Furthermore, when supporting EUDCH, the following physical channels are defined. E-DPDCH (E-DCH Dedicated Physical Data Channel), which is a physical channel for transmitting user data, information necessary for the radio base station to perform scheduling, and necessary for decoding E-DPDCH E-DPCCH (Enhanced Dedicated Physical Control Channel), which is a control channel for reporting information to be transmitted, information on the maximum transmission rate / power allowed by the mobile station, and information on transmission timing allowed by the mobile station E-HICH (E-DCH HARQ Acknowledge) which is HARQ Acknowledge information used when performing HARQ control of E-AGCH and E-DPDCH that are control channels for notification segment indicator channel), and E-RGCH (E-DCH Relative Grant Channel) for relatively instructing “up” and “down” of the maximum transmission rate allowed to the mobile station.

  FIG. 2 is a diagram showing a configuration example of the EUDCH system in one embodiment of the present invention. In FIG. 2, the mobile station 1 is in a SHO (Soft Hand Over) state among the radio base station 2-1, the radio base station 2-2, and the radio base station 2-3. The radio link (RL) with the radio base station 2-1 is RL # 1, the radio link with the radio base station 2-2 is RL # 2, and the radio link with the radio base station 2-3 is RL # 3. Call it. The radio base stations 2-1 to 2-3 are connected to an upper station (RNC: Radio Network Controller) 3 through an interface called Iub. In FIG. 2, for simplicity, E-HICH / E-RGCH, which is a downlink physical channel used in EUDCH, is not shown.

  User data carried by the E-DPDCH is transmitted to the radio base stations 2-1 to 2-3 along with the E-DPCCH that is a control channel. The E-DPCCH transmitted along with the E-DPDCH includes E-TFCI (E-DCH Transport Format Combination Indicator) that is transmission rate information of the E-DPDCH. The radio base stations 2-1 to 2-3 first decode the E-TFCI in the E-DPCCH, and based on the E-TF obtained from the decoding result, the E-DPDCH SF (Spreading Factor), data size, By obtaining information necessary for decoding the E-DPDCH such as the number of codes, the E-DPDCH can be decoded.

  The decryption OK user data is transmitted to the upper station 3 via Iub, and the upper station 3 performs selective synthesis and order control. Therefore, since the decoding result only needs to be OK in at least one of the radio base stations 2-1 to 2-3, a selection diversity effect can be obtained. In the example illustrated in FIG. 2, the radio base station 2-3 is an HS-DSCH Serving Cell for the mobile station 1 and describes HS-PDSCH, HS-SCCH, and HS-DPCCH, which are physical channels for HSDPA. Yes.

  The mobile station 1 calculates the downlink radio link quality from the reception level of CPICH (Common Pilot Channel) transmitted from the radio base station 2-3, and sends it to the radio base station 2-3 as CQI information in the HS-DPCCH. Notify this. Further, in the example illustrated in FIG. 2, the radio base station 2-3 is a Serving E-DCH Cell for the mobile station 1. The radio base station 2-3 controls the information on the maximum transmission rate / power of the mobile station 1 by transmitting E-AGCH to the mobile station 1.

  FIG. 3 is a block diagram showing the configuration of the mobile station 1 of FIG. In FIG. 3, the mobile station 1 includes a CPU (central processing unit) 11 that controls each unit in the apparatus, a main memory 12 that stores a control program 12a executed by the CPU 11, a storage device 13 that includes a transmission buffer 131, A radio communication control unit 14 that controls radio communication with the radio base station 2 and an antenna 15 are configured. In the mobile station 1, the CPU 11, the main memory 12, the storage device 13, and the wireless communication control unit 14 are connected to each other via an internal bus 110.

  FIG. 4 is a block diagram showing a configuration of the radio base station 2 of FIG. In FIG. 4, the radio base station 2 includes a CPU 21 that controls each unit in the apparatus, a main memory 22 that stores a control program 22a executed by the CPU 21, a parameter holding unit 231 that stores parameters set by the host station, A storage device 23 having a lookup table 232, an upper station side communication control unit 24 that controls communication with the upper station side, a radio communication control unit 25 that controls radio communication with the mobile station 1 side, and an antenna 26. In the radio base station 2, the CPU 21, the main memory 22, the storage device 23, the upper station side communication control unit 24, and the radio communication control unit 25 are connected to each other via an internal bus 210.

  FIG. 5 is a diagram showing a process for realizing the first method of the first control method for E-AGCH downlink power control according to an embodiment of the present invention, and FIG. 6 is a diagram of the mobile station 1 shown in FIG. FIG. 7 is a flowchart showing the operation of the radio base station 2 shown in FIG. The first method of the first control method for E-AGCH downlink power control according to an embodiment of the present invention will be described with reference to FIGS. 6 is realized by the CPU 11 executing the control program 12a in the mobile station 1, and the process shown in FIG. 7 is realized by the CPU 21 executing the control program 22a in the radio base station 2.

  The mobile station 1 notifies the radio base station 2 using the E-TF in the E-DPCCH whether or not the E-AGCH information transmitted to the mobile station 1 with the radio base station 2 can be notified to the own station. To do. Since the E-AGCH has a CRC, the mobile station 1 always monitors the E-AGCH and recognizes that the E-AGCH has been notified to itself by checking the CRC. Can do.

  The mobile station 1 always transmits the E-DPCCH to the radio base station 2 at a predetermined E-DPCCH transmission timing after the E-AGCH CRC check is OK. At this time, the value of E-TF, which is an information element included in E-DPCCH, is encoded as E-TFCI as “Reserved value” and mapped to E-DPCCH. Further, when the CRC check of E-AGCH is OK, the transmission of E-DPDCH immediately after that is not performed. When the mobile station 1 performs this operation, the radio base station 2 realizes E-AGCH power control.

  A specific control of the mobile station 1 related to the first method of the first control method will be described. The mobile station 1 performing EUDCH monitors whether the E-AGCH addressed to itself is transmitted every subframe (Sub-Frame) (E-AGCH transmission unit: 2 ms) (step S1 in FIG. 6). It is determined whether the CRC of the E-AGCH is OK (step S2 in FIG. 6).

  When the CRC is OK, the mobile station 1 sets the E-TF in the E-DPCCH to the “Reserved value”, encodes the E-TFCI, maps the E-TFCI to the E-DPCCH, and sets the radio base Transmission to the station 2 is performed (step S3 in FIG. 6). Further, the mobile station 1 determines whether or not it is desired to transmit the E-DPDCH at the next timing due to data accumulated in a transmission buffer (not shown) (step S4 in FIG. 6).

  When the mobile station 1 wants to transmit the E-DPDCH, the timing at which the E-TF is transmitted to the radio base station 2 as a “Reserved value”, that is, the predetermined timing at which the E-DPCCH is transmitted after receiving the E-AGCH. (Step S5 in FIG. 6), and if so, control is performed so that E-DPDCH is not transmitted at the corresponding timing (step S7 in FIG. 4). If the result of step S5 is No, E-DPDCH / E-DPCCH is transmitted (step S6 in FIG. 6). Note that the E-TF value in the E-DPCCH at this time is a value determined depending on the SF of the E-DPDCH, the data size, the number of multicodes, and the like.

Next, specific control of the radio base station 2 relating to the first method of the first control method will be described. In the radio base station 2 that has become the Serving E-DCH Cell for the mobile station 1 described above, Delta_e is set in advance from the upper station (step S11 in FIG. 7). Here, Delta_e is a value indicating the initial transmission power value of E-AGCH as an offset with respect to CPICH transmission power. Therefore, if the CPICH transmission power value is P_CPICH, the initial transmission power of E-AGCH for the mobile station 1: P_e_agch_ini is
P_e_agch_ini = P_CPICH + Delta_e
It is shown by the formula.

The radio base station 2 determines whether or not to transmit E-AGCH to the mobile station 1 (step S12 in FIG. 7).
P_e_agch_req
= P_CPICH + Delta_e + Delta_offset
Is calculated (step S13 in FIG. 7). Here, the initial value of “Delta_offset” is “0”. Also, E-AGCH power control is realized by updating the “Delta_offset”.

The radio base station 2 performs clipping with the maximum E-AGCH power set by the upper station: P_e_agch_max based on the power value: P_e_agch_req calculated by the above formula and required for the mobile station 1 (step in FIG. 7). S14) to prevent transmission with too much power. In this case, the calculation formula is
P_e_agch
= MIN (P_e_agch_req, P_e_agch_max)
It becomes. Thereby, the radio base station 2 transmits E-AGCH with the power value of P_e_agch. If it is determined in step S12 that E-AGCH is not transmitted to the mobile station 1, the processes in steps S13 and S14 described above are not performed.

  Next, after transmitting E-AGCH, the radio base station 2 determines whether it is time to receive the E-DPCCH notified from the mobile station 1 (step S15 in FIG. 7). If it is not the reception timing, the radio base station 2 ends the process for each subframe without performing the power correction process.

If the reception timing is notified, the radio base station 2 determines whether the correlation result of E-TFCI in the E-DPCCH is higher than a threshold (Threshold) (step S16 in FIG. 7), and the correlation value is lower than the threshold. If it is lower, it is determined that the mobile station 1 has not taken E-AGCH,
Delta_offset
= Delta_offset + Delta_step
× (1-BLER_target) [dB]
The power correction process shown by the equation is performed (step S18 in FIG. 7).

  If the CRC of the E-DPCCH is assigned to the operation of step S16, it can be determined whether the CRC decoding result of the E-DPCCH is OK or NG. In this case, if the CRC decoding result of E-DPCCH is OK, the process branches to “YES” in step S16, and if the CRC decoding result is NG, the process branches to “NO” in step S16.

  Here, Delta_step is a step width (dB), BLER_target is a target BLER (Block Error Rate) of E-AGCH, and is a parameter set from a higher station.

If the E-TFCI correlation result in the E-DPCCH is higher than the threshold, the radio base station 2 determines whether the E-TF value, which is the E-TFCI decoding result, is a “reserved value”. (FIG. 7, step S17), if it is “Reserved value”, it can be determined that the mobile station 1 has taken E-AGCH.
Delta_offset
= Delta_offset-Delta_step
× BLER_target [dB]
The power correction process shown by the equation is performed (step S19 in FIG. 7). If it is not “Reserved value”, the radio base station 2 determines that the mobile station 1 has not taken E-AGCH, and performs the power correction processing shown in step S18.

  In the first method of the first control method described above, the E-DPCCH must be transmitted by the mobile station 1 when the E-AGCH reception is OK, and there is a restriction that the E-DPDCH cannot be transmitted at this time. is there. Furthermore, in the first method of the first control method, the transmission timing of the E-DPCCH that can be transmitted by the mobile station 1 is when data is transmitted using the E-DPDCH or immediately after receiving the E-AGCH. It is limited only to the timing. However, in the first method of the first control method, there is no need to add an information bit to the E-DPCCH, and it is a great merit that the power control of the E-AGCH can be performed with easy control.

  As a method for eliminating the restriction on the E-DPCCH transmission timing generated in the first method of the first control method, the second method of the first control method related to E-AGCH downlink power control is described below. Show.

  FIG. 8 is a diagram showing a process for realizing the second method of the first control method for E-AGCH downlink power control according to an embodiment of the present invention, and FIG. 9 is an operation of the mobile station 1 of FIG. FIG. 10 is a flowchart showing the operation of the radio base station 2 of FIG. A second method of the first control method related to E-AGCH downlink power control according to an embodiment of the present invention will be described with reference to FIGS. The process shown in FIG. 9 is realized by the CPU 11 executing the control program 12a in the mobile station 1, and the process shown in FIG. 10 is realized by the CPU 21 executing the control program 22a in the radio base station 2.

  A CRC bit (OK / NG of 1-bit CRC) mapped in the E-DPCCH indicates whether the E-AGCH information transmitted to the mobile station 1 with the radio base station 2 has been notified to the mobile station 1. Information) is notified to the radio base station 2. Similar to the first method of the first control method described above, since the CRC is attached to the E-AGCH, the mobile station 1 always monitors the E-AGCH and checks the CRC to thereby check the E-AGCH. -It is possible to recognize that the AGCH has been notified to the local station.

  If the E-AGCH CRC check is OK and the E-DPCCH transmission is performed, the mobile station 1 notifies the radio base station 2 of the CRC bit in the E-DPCCH as “OK”, and the CRC check is NG. If there is E-DPCCH transmission, the radio base station 2 is notified of the CRC bit in the E-DPCCH as “NG”. The mobile station 1 does not necessarily need to transmit the result of the CRC check of the E-AGCH to the radio base station 2, but in order to improve the accuracy of this control, a predetermined value after receiving the E-AGCH by CRC OK It is better to transmit the E-DPCCH at the timing. When transmitting only the E-DPCCH, the mobile station 1 transmits the E-TF value to the radio base station 2 as a “Reserved value”. When the mobile station 1 performs this operation, the radio base station 2 implements E-AGCH power control.

  A specific control of the mobile station 1 relating to the second method of the first control method will be described. The mobile station 1 that performs EUDCH monitors whether the E-AGCH addressed to itself is transmitted every subframe (E-AGCH transmission unit: 2 ms) (step S21 in FIG. 9), and performs CRC of the E-AGCH. Whether or not is OK is determined (step S22 in FIG. 9). When the CRC is OK, the mobile station 1 determines whether or not the E-DPDCH can be transmitted (step S23 in FIG. 9).

  When transmitting the E-DPDCH, the mobile station 1 transmits the E-DPCCH with E-TF set to the E-DPDCH transmission rate and the CRC bit set to “OK” (step S24 in FIG. 9). If the mobile station 1 does not transmit E-DPDCH, it determines whether or not to transmit only E-DPCCH (step S25 in FIG. 9). When transmitting the E-DPDCH, the mobile station 1 transmits the E-DPCCH using the “reserved value” for the E-TF and the CRC result of the E-AGCH as the CRC bit (here, “OK”) ( FIG. 9 step S26).

  If the E-DPCCH is not transmitted under the condition in step S25, nothing is transmitted. However, when the CRC of the E-AGCH is “OK”, an improvement in accuracy by this control can be expected if the E-DPCCH is always transmitted at a predetermined timing after receiving the E-AGCH.

  On the other hand, from the above step S22, when the CRC is NG, the mobile station 1 determines whether or not the E-DPDCH can be transmitted (step S27 in FIG. 9). When transmitting the E-DPDCH, the mobile station 1 transmits the E-DPCCH with E-TF set to the E-DPDCH transmission rate and the CRC bit set to “NG” (step S28 in FIG. 9).

  If the mobile station 1 does not transmit E-DPDCH, it determines whether or not to transmit only E-DPCCH (step S25 in FIG. 9). When transmitting the E-DPDCH, the mobile station 1 transmits the E-DPCCH using the “reserved value” for the E-TF and the CRC result of the CRC of the E-AGCH (here, “NG”) ( FIG. 9 step S26). If the E-DPCCH is not transmitted under the condition in step S25, nothing is transmitted.

  Specific control of the radio base station 2 relating to the second method of the first control method will be described. In the radio base station 2 that has become the Serving E-DCH Cell for the mobile station 1, Delta_e is set in advance from the upper station (step S31 in FIG. 10). Here, Delta_e is a value indicating the initial transmission power value of E-AGCH as an offset with respect to CPICH transmission power.

Therefore, if the CPICH transmission power value is P_CPICH, the initial transmission power of the E-AGCH for the mobile station: P_e_agch_ini is
P_e_agch_ini = P_CPICH + Delta_e
It is shown by the formula.

Next, the radio base station 2 determines whether or not to transmit E-AGCH to the mobile station 1 (step S32 in FIG. 10).
P_e_agch_req
= P_CPICH + Delta_e + Delta_offset
Is calculated (step S33 in FIG. 10). Here, the initial value of Delta_offset is 0. Also, E-AGCH power control is realized by updating this Delta_offset.

Based on the power value calculated in step S33 and required for the mobile station 1: P_e_agch_req, clipping is performed with the maximum power of E-AGCH set in advance from the upper station: P_e_agch_max (step S34 in FIG. 10). Prevent transmission with too much power. In this case, the calculation formula is
P_e_agch
= MIN (P_e_agch_req, P_e_agch_max)
It becomes. Thereby, the radio base station 2 transmits E-AGCH with the power value of P_e_agch. If it is determined in step S32 that E-AGCH is not transmitted to the mobile station 1, the processes in steps S33 and S34 described above are not performed.

  Next, the radio base station 2 determines whether it is a predetermined timing for receiving the E-DPCCH from the mobile station after transmitting the E-AGCH (step S35 in FIG. 10). If it is not the reception timing, the radio base station 2 ends the process for each subframe without performing the power correction process.

  The radio base station 2 determines whether or not the E-TFCI correlation result in the E-DPCCH is higher than the threshold at a predetermined reception timing (step S36 in FIG. 10). If the CRC is assigned to the E-DPCCH, the operation in step S36 can be determined based on whether the CRC decoding result of the E-DPCCH is OK or NG. In this case, if the CRC decoding result of the E-DPCCH is OK, the process branches to “YES” in step S36, and if the CRC decoding result is NG, the process branches to “NO” in step S36.

  If the correlation result of E-TFCI in the E-DPCCH is lower than the threshold value, the radio base station 2 does not transmit the E-DPCCH, and the process for each subframe is terminated without performing the power correction process. To do. However, if the mobile base station 1 performs the operation of always transmitting the E-DPCCH at a predetermined timing after the reception of the E-AGCH when the CRC of the E-AGCH is “OK”, the radio base station 2 moves to the broken line arrow. This control (see FIG. 10) can improve the accuracy of this control.

If the correlation value is higher than the threshold value, the radio base station 2 confirms whether the CRC bit in the E-DPCCH is OK (step S37 in FIG. 10). If the CRC bit is “NG”, the radio base station 2 determines that the mobile station 1 has not taken E-AGCH,
Delta_offset
= Delta_offset + Delta_step
× (1-BLER_target) [dB]
The power correction process shown by the equation is performed (step S38 in FIG. 10). Here, Delta_step is a step width (dB), BLER_target is a target BLER (Block Error Rate) of E-AGCH, and is a parameter set from a higher station.

Since the radio base station 2 can determine that the mobile station 1 has taken E-AGCH if the CRC bit in the E-DPCCH is “OK”,
Delta_offset
= Delta_offset-Delta_step
× BLER_target [dB]
The power correction process shown by the equation is performed (step S39 in FIG. 10).

  By this control, the mobile station 1 can transmit only E-DPCCH / E-DPDCH or E-DPCCH at an arbitrary timing. However, in order to further improve the accuracy of this control, when the mobile station 1 receives the E-AGCH with the CRC OK, there is a restriction that the E-DPCCH is always transmitted at a predetermined timing after the reception of the E-AGCH. To do.

  FIG. 11A is a diagram illustrating operations of the mobile station 1 and the radio base station 2 in order to realize the second control method related to E-AGCH downlink power control according to an embodiment of the present invention, and FIG. FIG. 12 is a flowchart showing operations of the mobile station 1 and the radio base station 2 for realizing a second control method related to E-AGCH downlink power control according to an embodiment of the present invention, and FIG. 12 is a flowchart according to an embodiment of the present invention. It is a figure which shows the example of a calculation table of the electric power correction value (Delta_req) used with the 2nd control method. A second control method related to E-AGCH downlink power control according to an embodiment of the present invention will be described with reference to FIGS.

  As a condition for performing this control, the radio base station 2 is a Serving E-DCH Cell for the mobile station 1 and an HSDPA Serving Cell. The outline of the second control method is shown below.

  The mobile station 1 maps downlink radio link quality information (CQI) obtained by measuring the CPICH reception level of the radio base station 2 which is an HSDPA Serving Cell to the HS-DPCCH and notifies the radio base station 2 . The radio base station 2 can calculate the E-AGCH downlink transmission power based on the notified CQI. A method of calculating the power value of E-AGCH from CQI can be easily implemented by, for example, drawing a pre-calculated lookup table (for example, the table shown in FIG. 10). In this case, the first control method described above can be used in combination. By performing power correction using the first control method, it is possible to improve the accuracy of E-AGCH power control.

  A specific control of the mobile station 1 relating to the second control method will be described. The mobile station 1 determines whether or not it is the CQI transmission timing from the parameters designated in advance by the host (step S41 in FIG. 11), and if it is the CQI transmission timing, transmits the CQI to the radio base station 2 (step S42 in FIG. 11). . The operation of the mobile station 1 conforms to the specification defined by HSDPA.

  A specific control of the radio base station 2 related to the second control method will be described. The radio base station 2 performs an operation of receiving CQI from the mobile station 1 (step S51 in FIG. 11). Here, the received valid CQI is defined as CQI_Rec. From the obtained CQI_Rec, the radio base station 2 uses the lookup table calculated in advance (for example, the table shown in FIG. 12) to transmit E-AGCH with the transmission power of P_CPICH + Gamma + Delta_req. A value that is a transmission power value that can acquire E-AGCH with a desired BLER is obtained (step S52 in FIG. 11). Here, P_CPICH is the transmission power of CPICH and is set by the upper station. Gamma is Measurement Power Offset [dB] defined by HSDPA, and is set by the upper station.

Next, the radio base station 2
P_e_agch_req
= P_CPICH + Gamma + Delta_req
+ Delta_offset
The required transmission power value of E-AGCH is calculated by the following formula (step S53 in FIG. 11).

  Here, Delta_offset is used when the value obtained by the correction processing of FIG. 5 to FIG. 7 or FIG. 8 to FIG. In this control, it is possible to use both the first method and the second method of the first control method described above. In this case, the correction processing of FIG. 5 to FIG. 7 or FIG. 8 to FIG. 10 is performed as Delta_e = Gamma + Delta_req. When not used together, Delta_offset = 0.

The radio base station 2 performs clipping with the required transmission power value of E-AGCH obtained in the above step S53: P_e_agch_req and the maximum power of E-AGCH preset by the upper station: P_e_agch_max (FIG. 11). Step S54) prevents transmission with too much power. In this case, the calculation formula is
P_e_agch
= MIN (P_e_agch_req, P_e_agch_max)
It becomes. When transmitting the E-AGCH to the mobile station 1, the radio base station 2 uses the latest calculation result of step S54 calculated for each mobile station 1 as the transmission power value of the E-AGCH.

  As described above, in this embodiment, power control of the E-AGCH is performed by adding only a few information bits and control, or by adding control, thereby undesirably wasting downstream power resources in the W-CDMA system. Can be suppressed.

  Note that the same method as described above can be used to determine the downlink transmission power of E-HICH / E-RGCH. Since the ratio between the power required for E-AGCH and the power required for E-HICH / E-RGCH can be calculated in advance, transmission of E-HICH / E-RGCH is possible using this power ratio. It can also be used for power control. However, since E-HICH / E-RGCH is information-multiplexed with information for up to 20 mobile stations, a method of assigning the maximum value (or average value) of required power values to each mobile station is available. Applicable.

It is a block diagram which shows the structure of the mobile communication system by one Example of this invention. It is a figure which shows the structural example of the EUDCH system in one Example of this invention. FIG. 2 is a block diagram showing a configuration of a mobile station in FIG. 1. FIG. 2 is a block diagram showing a configuration of a radio base station in FIG. 1. It is a figure which shows the process for implement | achieving the 1st method of the 1st control method regarding E-AGCH downlink power control by one Example of this invention. 6 is a flowchart showing the operation of the mobile station of FIG. It is a flowchart which shows operation | movement of the wireless base station of FIG. It is a figure which shows the process for implement | achieving the 2nd method of the 1st control method regarding E-AGCH downlink power control by one Example of this invention. 9 is a flowchart showing the operation of the mobile station of FIG. It is a flowchart which shows operation | movement of the wireless base station of FIG. (A) is a figure which shows operation | movement of a mobile station and a radio base station in order to implement | achieve the 2nd control method regarding E-AGCH downlink power control by one Example of this invention, (b) is one Example of this invention. It is a flowchart which shows operation | movement of a mobile station and a radio base station in order to implement | achieve the 2nd control method regarding E-AGCH downlink power control. It is a figure which shows the example of a calculation table of the electric power correction value (Delta_req) used with the 2nd control method by one Example of this invention.

Explanation of symbols

1 mobile station 2,2-1 to 2-3 radio base station
3 upper stations
11,21 CPU
12, 22 Main memory 12a, 22a Control program
13,23 storage device
14, 25 Wireless communication control unit
15, 26 Antenna 110, 210 Internal bus
131 Send buffer
231 Parameter holding unit
232 lookup table

Claims (21)

In the uplink from the mobile station to the radio base station, E-AGCH (Enhanced Dedicated Channel (E-DCH)) is used as an downlink physical channel (E-DCH (Enhanced Dedicated Channel)). A mobile communication system that performs transmission,
The radio base station, possess means for monitoring the downlink radio link quality state of the mobile station which is the destination of the E-AGCH, and means for performing power control of the E-AGCH based on the monitoring result ,
The mobile station includes a function of feeding back an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from a decoding result of the E-AGCH to the own station to the radio base station using an uplink physical control channel. ,
The radio base station performs power control of the E-AGCH for the mobile station based on a CRC result obtained from the mobile station . The mobile communication system according to claim 1, wherein the uplink physical control channel is E-DPCCH [E-DCH (Enhanced Dedicated Channel) Dedicated Physical Control Channel] . The function of feeding back indicates whether the E-AGCH has been correctly received by the radio base station by always transmitting the E-DPCCH at a predetermined timing after successfully decoding the E-AGCH. The mobile communication system according to claim 2 , wherein the notification is made indirectly . 3. The mobile communication according to claim 2 , wherein the feedback function maps OK / NG for CRC determination of the E-AGCH onto the E-DPCCH as 1-bit information and notifies the radio base station. system. The means for monitoring the downlink radio link quality state of the mobile station is received from the mobile station when the HS-DSCH (High Speed-Downlink Shared Channel) Serving Cell and Serving E-DCH (Enhanced Dedicated Channel) Cell are the same. Calculating the transmission power of the E-AGCH using CQI (Channel Quality Indicator) in the HS-DPCCH,
The means for performing power control of the E-AGCH performs power control of the E-AGCH based on the calculated transmission power of the E-AGCH. Mobile communication system. The means for monitoring the downlink radio link quality state of the mobile station calculates the transmission power of the E-AGCH using the CQI by drawing a lookup table calculated in advance. The mobile communication system described. The mobile communication system according to any one of claims 1 to 6, wherein a common E-AGCH is used for a plurality of mobile stations. On the uplink from the mobile station, E-AGCH [E-DCH (Enhanced Dedicated Channel) Abbreviated Grant Channel] is used as a downlink physical channel, and an uplink high-speed packet called EUDCH (enhanced uplink dedicated channel) is used. A base station,
Means for monitoring the downlink radio link quality state of the mobile station that is the transmission destination of the E-AGCH, and means for performing power control of the E-AGCH based on the monitoring result;
A function in which the mobile station feeds back a CRC (Cyclic Redundancy Check) OK / NG determination result obtained from the decoding result of the E-AGCH to the mobile station using the uplink physical control channel; ,
A radio base station that performs power control of the E-AGCH for the mobile station based on a CRC result obtained from the mobile station. 9. The radio base station according to claim 8, wherein the uplink physical control channel is E-DPCCH [E-DCH (Enhanced Dedicated Channel) Dedicated Physical Control Channel]. The function of feeding back indicates whether the E-AGCH has been correctly received by the radio base station by always transmitting the E-DPCCH at a predetermined timing after successfully decoding the E-AGCH. The radio base station according to claim 9, which is indirectly notified. 10. The radio base station according to claim 9, wherein the feedback function maps OK / NG of CRC determination of the E-AGCH onto the E-DPCCH as 1-bit information and notifies the radio base station. Bureau. The means for monitoring the downlink radio link quality state of the mobile station is received from the mobile station when the HS-DSCH (High Speed-Downlink Shared Channel) Serving Cell and Serving E-DCH (Enhanced Dedicated Channel) Cell are the same. Calculating the transmission power of the E-AGCH using CQI (Channel Quality Indicator) in the HS-DPCCH,
The means for performing power control of the E-AGCH performs power control of the E-AGCH based on the calculated transmission power of the E-AGCH. Wireless base station. The means for monitoring the downlink radio link quality state of the mobile station calculates the transmission power of the E-AGCH using the CQI by drawing a lookup table calculated in advance. The radio base station described. The radio base station according to any one of claims 8 to 13, wherein a common E-AGCH is used for a plurality of mobile stations. In the uplink from the mobile station to the radio base station, E-AGCH (Enhanced Dedicated Channel (E-DCH)) is used as an downlink physical channel (E-DCH (Enhanced Dedicated Channel)). A downlink control channel power control method used in a mobile communication system that performs transmission,
The radio base station performs a process of monitoring a downlink radio link quality state of the mobile station that is a transmission destination of the E-AGCH, and a process of performing power control of the E-AGCH based on the monitoring result ,
The mobile station feeds back an OK / NG determination result of CRC (Cyclic Redundancy Check) obtained from the decoding result of the E-AGCH to the mobile station using the uplink physical control channel,
A downlink control channel power control method, wherein the radio base station performs power control of the E-AGCH for the mobile station based on a CRC result obtained from the mobile station. 16. The downlink control channel power control method according to claim 15, wherein the uplink physical control channel is E-DPCCH [E-DCH (Enhanced Dedicated Channel) Dedicated Physical Control Channel]. Whether the mobile station has received the E-AGCH correctly or not by transmitting the E-DPCCH at a predetermined timing after correctly decoding the E-AGCH. The downlink control channel power control method according to claim 16, wherein the downlink control channel power control method is configured to perform notification in an automatic manner. The downlink control channel according to claim 16, wherein the mobile station maps the E / AGCH CRC determination OK / NG as 1-bit information onto the E-DPCCH and notifies the radio base station. Power control method. The process of monitoring the downlink radio link quality state of the mobile station is received from the mobile station when the HS-DSCH (High Speed-Downlink Shared Channel) Serving Cell and Serving E-DCH (Enhanced Dedicated Channel) Cell are the same. Calculating the transmission power of the E-AGCH using CQI (Channel Quality Indicator) in the HS-DPCCH,
The process for performing power control of the E-AGCH performs power control of the E-AGCH based on the calculated transmission power of the E-AGCH. Downlink control channel power control method. The process of monitoring the downlink radio link quality state of the mobile station calculates the transmission power of the E-AGCH using the CQI by drawing a lookup table calculated in advance. The downlink control channel power control method described. 21. The downlink control channel power control method according to claim 15, wherein a common E-AGCH is used for a plurality of mobile stations.

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