JP2005286651A - CDMA base station apparatus and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform appropriate CQI interpolation using TPC bits, appropriately select a transmission user and determine a modulation method, and prevent a decrease in throughput. SIR comparison circuit 122 receives demodulator 107 for DPCH The likelihood of all the TPC bits thus calculated is calculated, and the TPC bit reliability determination unit 123 outputs only the TPC bits having a high likelihood to the CQI interpolation unit 112. The CQI interpolation unit 112 adds the interpolation value based on the likelihood of the TPC bit to the CQI value received by the demodulation unit 108 for HS-DPCCH. The transmission user / modulation / demodulation determination unit 113 determines the user who transmits the next packet and the modulation method / format using the interpolated CQI value received for each subframe. The adaptive encoding / modulation unit 114 encodes and modulates transmission data in accordance with the transmission user and modulation scheme / format determined by the transmission user / modulation / demodulation determination unit 113.
[Selection] Figure 1

Description

  The present invention relates to a CDMA base station apparatus and a radio communication method, and more particularly to a CDMA base station apparatus and a radio communication method suitable for use in mobile communication.

  There is HSDPA (downlink high-speed packet transmission) which is one of high-speed data transmission systems. In HSDPA, a mobile station reports a CQI (Channel Quality Indicator) included in HS-DPCCH, which is an uplink control channel, to a radio base station apparatus and transmits a packet in the radio base station apparatus. Determine the mobile unit and the modulation method, transmission format, etc. used at that time.

  CQI is propagation environment information that is reported based on a report period specific to a mobile station, and each mobile station measures the received power of CPICH, which is a common pilot channel in the downlink direction, so that it corresponds to CIR of CPICH (in dB units). ) Value (0 to 30) is encoded and transmitted to the radio base station apparatus.

  Based on this CQI, the radio base station apparatus determines the mobile device that will transmit the next packet, the modulation method used at that time, the transmission format, etc., and transmits the packet to efficiently transmit the packet. This CQI considers a reduction in power consumption of a mobile device by intermittently transmitting once at a plurality of transmission timings based on a transmission cycle.

  On the other hand, when it is assumed that the mobile device performs communication while moving, the propagation environment constantly changes over time. Therefore, the radio base station apparatus needs to estimate and interpolate the time variation of the propagation environment, instead of using the CQI reported from the mobile device as it is.

  As an interpolation method, a method of interpolating and using a CQI value using a TPC bit for power control control included in the uplink DPCH has been studied (for example, Patent Document 1).

  This TPC bit is a bit included in the DPCH. If the SIR at the time of receiving the uplink DPCH from the mobile device does not reach the desired value, the radio base station apparatus requests to increase the transmission power of the next DPCH by transmitting “0” with the TPC bit of the next slot. To do. Conversely, if the SIR value is sufficient, “1” is transmitted to request that the transmission power of the next DPCH be reduced. By performing such control between the radio base station apparatus and the mobile device, the DPCH can always be transmitted with the optimum transmission power, and the increase in interference due to excess power and the deterioration in reception quality due to lack of power are suppressed. be able to.

  Here, since the TPC bit is embedded in each slot of the DPCH, the radio base station apparatus performs interpolation processing of the CQI value using the TPC bit while the above-described CQI is not transmitted. The propagation environment of each mobile device can be estimated.

  Specifically, in the slot where the TPC bit “0” is transmitted from the mobile station, it can be estimated that the propagation environment is worse than that in the previous slot, and thus the received CQI needs to be lowered accordingly. Therefore, “−1” is added to the CQI value when the TPC bit received for each slot is “0” and “1” is added when the TPC bit is “1”. By performing this process in units of slots, it is possible to interpolate the time variation of the propagation environment until the next CQI is received.

As described above, the conventional CDMA communication apparatus suppresses the deterioration of the throughput due to the error of the CQI by interpolating the CQI that can be received only intermittently by the TPC bit that can be received every slot.
JP 2002-152228 A

  However, the conventional apparatus has a problem that the interpolation accuracy of CQI deteriorates due to a TPC bit including a demodulation error, the transmission user cannot be selected and the modulation scheme cannot be appropriately determined, and the throughput deteriorates. .

  This degradation becomes more noticeable as the CQI reporting period becomes longer due to the TPC bits including demodulation errors. Therefore, in order to maintain a constant throughput, the mobile station must increase the CQI reporting frequency, and the mobile station power consumption Leads to increase of interference and interference.

  Further, since the TPC bit has only a positive or negative expression, even when the state of the propagation environment does not change between 1 slot, the CQI increases or decreases due to the interpolation by the TPC bit, and the CQI interpolation accuracy deteriorates. There is also a problem.

  The present invention has been made in view of the above point, and a CDMA base station apparatus capable of performing appropriate CQI interpolation using TPC bits, appropriately selecting a transmission user and determining a modulation method, and preventing a decrease in throughput. It is another object of the present invention to provide a wireless communication method.

  The CDMA base station apparatus of the present invention measures the reception quality of the received TPC bits, receiving means for receiving a radio signal including TPC bits that are transmission power control information and CQI that is propagation path environment information. SIR calculating means, determining means for determining that the TPC bit is reliable when the reception quality is equal to or higher than a predetermined threshold, and determining that the TPC bit is reliable, the CQI is calculated using the TPC bit. If it is determined that the TPC bit is reliable and the interpolation is not performed, an interpolation unit that does not perform the CQI interpolation using the TPC bit, a determination unit that determines a transmission user, a modulation scheme, and a coding scheme based on the CQI after the interpolation, and Adaptive encoding / modulating means for modulating transmission data in accordance with the transmission user, modulation scheme and encoding scheme determined by the determining means, and the adaptive encoding / modulation In stage employs a configuration comprising a transmission unit configured to transmit the transmission data modulated by radio signal.

  According to this configuration, among the received TPC bits, the CQI is interpolated only by the TPC bits whose reception quality is equal to or higher than a predetermined value, so that appropriate CQI interpolation is performed by the TPC bits, and the selection of the transmission user and the modulation scheme are performed. Decisions can be made appropriately to prevent throughput degradation.

  The CDMA base station apparatus of the present invention employs a configuration in which the interpolation means interpolates using the TPC bits from the time after receiving the CQI to the time of transmission data transmission.

  According to this configuration, the present invention can be applied even when there is a difference in DPCH and HS-DPCCH timing.

  The CDMA base station apparatus of the present invention includes a buffer means for storing the reception quality of the TPC bit, a difference calculation means for taking a difference between the reception quality of the previously received TPC bit and the reception quality of the newly received TPC bit, The determination means determines whether or not the difference is within a predetermined range, and the interpolation means interpolates CQI using the TPC bit when the difference is not within the predetermined range. When the difference is within a predetermined range, a configuration is adopted in which CQI interpolation using the TPC bit is not performed.

  According to this configuration, when the propagation environment does not change between slots, unnecessary interpolation is not performed by not performing interpolation using the TPC bit, so that it is possible to prevent the interpolation accuracy from being lowered, and throughput is deteriorated. Can be improved.

  The CDMA base station apparatus of the present invention averages the reception quality of TPC demodulation results buffer means for adding a plurality of demodulated TPC bits and the TPC bits received in the TPC demodulation result buffer means. Likelihood determination threshold value calculation means for calculating the threshold value from quality, and the determination means uses the threshold value calculated by the likelihood determination threshold value calculation means to use the reception quality. When the value is equal to or greater than a predetermined threshold value, the TPC bit is determined to be reliable.

  According to this configuration, the likelihood of the TPC bit is obtained by comparing the average value of the soft value after demodulation of the TPC bit over a plurality of slots and the threshold value calculated by the average value of the communication quality SIR of the corresponding DPCH. By calculating the degree and determining whether to use for CQI interpolation, it is possible to obtain the likelihood for the soft average value of the TPC bits of a plurality of slots, so that the likelihood for each TPC bit is obtained. However, the reliability of the TPC bit can be obtained with higher accuracy, and throughput degradation due to an error in the TPC bit can be suppressed.

  The radio communication method of the present invention receives a radio signal including TPC bits that are transmission power control information and CQI that is propagation path environment information, measures the reception quality of the received TPC bits, and receives the reception quality. Is equal to or greater than a predetermined threshold value, it is determined that the TPC bit is reliable. If it is determined that the TPC bit is reliable, CQI is interpolated using the TPC bit, and the TPC bit is not determined to be reliable. In this case, the CQI interpolation using the TPC bit is not performed, the transmission user, the modulation method, and the coding method are determined by the interpolated CQI, and the transmission data is modulated by the determined transmission user, the modulation method, and the coding method. The modulated transmission data is transmitted as a radio signal.

  According to this method, among the received TPC bits, the CQI is interpolated only by the TPC bits whose reception quality is equal to or higher than a predetermined value, so that appropriate CQI interpolation is performed by the TPC bits, and the selection of the transmission user and the modulation scheme are performed. Decisions can be made appropriately to prevent throughput degradation.

  As described above, according to the CDMA base station apparatus and radio communication method of the present invention, appropriate CQI interpolation is performed using TPC bits, transmission users are selected and modulation schemes are appropriately determined, and throughput is prevented from being lowered. be able to.

  The gist of the present invention is to perform interpolation in consideration of the likelihood of the TPC bits used and the communication quality before and after the interpolation processing of the propagation environment information CQI reported intermittently from the mobile device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a CDMA base station apparatus according to Embodiment 1 of the present invention. The CDMA base station apparatus 100 of FIG. 1 includes an antenna 101, a receiving unit 102, a despreading unit 103, a despreading unit 104, a despreading unit 105, a demodulation unit 106, a demodulation unit 107, and a demodulation unit 108. The SIR calculation unit 111, the CQI interpolation unit 112, the transmission user / modulation / demodulation determination unit 113, the adaptive encoding / modulation unit 114, the modulation unit 115, the modulation unit 116, the spreading unit 117, and the spreading unit 118. And a spreading unit 119, a signal multiplexing unit 120, a transmission unit 121, an SIR comparison circuit 122, and a TPC bit reliability determination unit 123.

  In FIG. 1, the CDMA base station apparatus 100 receives each channel signal via the antenna 101, converts the radio frequency into a baseband frequency at the receiving unit 102, and performs the above-described propagation by the despreading unit 105 and the demodulation unit 108. Despreading and demodulation of HS-DPCCH, which is a channel for transmitting environment information CQI, are performed.

  Information transmitted through the HS-DPCCH includes HARQ-ACK, which is a control signal indicating whether or not a packet can be received, and CQI, which is a signal indicating propagation environment information. The radio base station apparatus performs despreading of these signals by the same despreading section 105 at the timing when each signal comes, and then performs demodulation processing in the demodulation section 108 to extract HARQ-ACK and CQI signals. .

  On the other hand, in CDMA base station apparatus 100, despreading section 103 and demodulating section 106 despread and demodulate the DPCH channel including power control information bits TPC, and extract TPC bits and others in slot units. Further, among the DPCH channel signals demodulated by the demodulator 107, the SIR calculator 111 measures the communication quality information SIR in the slot using the pilot signal bits.

  Then, the SIR comparison circuit 122 calculates the likelihood of all the TPC bits received by the demodulation unit 107 for DPCH, and the TPC bit reliability determination unit 123 outputs only the TPC bits having a high likelihood to the CQI interpolation unit 112. To do.

  The TPC bit reliability determination method is performed by comparing the measured SIR of the slot calculated by the SIR calculation unit 111 with the SIR threshold value SIRth1 that can be arbitrarily set, in the SIR comparison circuit 122. Specifically, when the measured SIR is lower than SIRth1, it is assumed that there is no reliability of the demodulated TPC bit and the CQI value is not integrated.

  The CQI interpolation unit 112 adds the interpolation value based on the likelihood of the TPC bit to the CQI value received by the demodulation unit 108 for HS-DPCCH.

  The transmission user / modulation / demodulation determination unit 113 determines the user who transmits the next packet and the modulation method / format using the interpolated CQI value received for each subframe. If no new CQI is received in the subframe, similar interpolation processing is performed on the post-interpolation CQI value in the previous subframe.

  The adaptive encoding / modulation unit 114 encodes and modulates transmission data in accordance with the transmission user and modulation method / format determined by the transmission user / modulation / demodulation determination unit 113 and outputs the result to the spreading unit 117.

  Spreading section 117 spreads the transmission data encoded and modulated by adaptive encoding / modulating section 114 and outputs the spread data to signal multiplexing section 120.

  Modulation section 115 and modulation section 116 modulate signals of other channels and output the signals to spreading section 118 and spreading section 119, respectively. The spreading unit 118 and the spreading unit 119 spread the signal and output the signal to the signal multiplexing unit 120.

  The signal multiplexing unit 120 multiplexes the signals output from the spreading units 117, 118, and 119 and outputs the multiplexed signal to the transmission unit 121. Transmitter 121 converts the multiplexed signal from a baseband frequency to a radio frequency and transmits it from antenna 101.

  Next, the operation of the CDMA base station apparatus 100 will be described. FIG. 2 is a flowchart showing the operation of the CDMA base station apparatus according to the present embodiment. FIG. 2 shows a flow from reception of CQI to interpolation processing.

  In FIG. 2, DPCH reception processing and CQI reception processing are performed in parallel. The DPCH reception process is performed in units of slots, and the CQI reception process is performed in units of subframes (here, 3 slots).

  In the DPCH reception process, in ST201, the despreading section 104 despreads the DPCH signal. Then, ST202 and ST203 are processed in parallel.

  In ST202, SIR calculation section 111 calculates the SIR of DPCH. In ST203, demodulation section 107 demodulates the TPC bit. Then, after processing ST202 and ST203, the process proceeds to ST204.

  In ST204, the SIR comparison circuit 122 determines whether or not the measured SIR of the slot is larger than the SIR threshold SIRth1 at which a value can be arbitrarily set. If the measured SIR of the slot is larger than the SIR threshold SIRth1 at which a value can be arbitrarily set, the process proceeds to ST205, and the measured SIR of the slot is equal to or less than the SIR threshold SIRth1 at which a value can be arbitrarily set. If there is, the process proceeds to ST206.

  In ST205, assuming that the reliability of the TPC bit is sufficient for CQI interpolation, the CQI interpolation unit 112 adds the interpolation value based on the likelihood of the TPC bit to the CQI value, and proceeds to ST207. On the other hand, in ST206, assuming that the reliability of the TPC bit is not sufficient for CQI interpolation, the CQI interpolation unit 112 does not add the interpolation value based on the likelihood of the TPC bit to the CQI value, and proceeds to ST207.

  In ST207, when it is not the transmission user determination timing, the process returns to ST201, and the processes from DPCH despreading to CQI interpolation are repeated. When the transmission user determination timing is reached, the process proceeds to ST213, and the CQI interpolation process is performed.

  On the other hand, on the CQI reception processing side, the processing from ST208 to ST212 is performed in parallel with the DPCH reception processing from ST201 to ST207.

  In ST208, if it is the CQI reception timing, the process proceeds to ST209, and if it is not the CQI reception timing, the process proceeds to ST212.

  In ST209, the despreading section 105 despreads the received signal including CQI, and proceeds to ST210. In ST210, demodulation section 108 demodulates the received signal including CQI, proceeds to ST211, determines the CQI value, and proceeds to ST213.

  In ST212, CQI interpolation section 112 uses the previously received CQI as the CQI of the current process, and proceeds to ST213.

  In ST213, the CQI interpolation unit 112 adds the CQI interpolation integrated value calculated from the TPC bits to the CQI, and proceeds to ST214. The CQI added with the integrated value is transmitted from the CQI interpolation unit 112 to the transmission user / modulation / demodulation determination unit 113. Passed.

  In ST215, transmission user / modulation / demodulation determination section 113 determines the transmission user and modulation scheme.

  In FIG. 2, the DPCH reception processing side operates in slot units, and the CQI reception processing side operates in subframe (3 slots) units. Then, the interpolation process is performed once in 1 subframe (3 slots), and the likelihood of the TPC bits in each slot is calculated for each 3 slot TPC bits, and the TPC bits of the slots determined to have sufficient reliability. Is added to the CQI value.

  For example, when the received CQI value is 10, the TPC bits of 3 slots (slot # 0 to # 2) are “0”, “1”, “0”, respectively, and the reliability determination results by SIR are “OK”, “NG”. , “OK”, since the TPC bit of slot # 1 is not subject to interpolation, the integrated values “+1” and “+1” corresponding to the TPC bits “0” and “0” of slot # 0 and slot # 2 are used. The CQI value is added to 10 and the CQI value after interpolation by the 3 slot TPC bit is “12”.

  Next, the difference in CQI processing between the case where the CDMA base station apparatus of this embodiment is used and the case where the conventional CDMA base station apparatus is used will be described.

  First, an example in which the CQI interpolation process is not applied is shown in FIG. FIG. 3 is a diagram illustrating a relationship between CQI and CIR when CQI interpolation processing is not applied. In the example of FIG. 3, since the CQI transmission cycle is an example of 4 subframes, the radio base station apparatus uses the same CQI value after receiving CQI in subframe # 0 until subframe # 5 receiving the next CQI. User selection and adaptive modulation must be performed. As a result, until a new CQI value is reported from the mobile station, the propagation environment fluctuates as shown in FIG. 3, and even if the CIR of the CPICH channel fluctuates, the CQI value cannot follow it.

  As a result, since there is a difference between the actual propagation environment and the CQI value, the base station cannot accurately perform user selection and adaptive modulation in consideration of the propagation environment of each mobile device, and the overall throughput deteriorates. End up.

  FIG. 4 shows an example in which the CQI value is interpolated by the TPC bit with respect to the example of FIG. FIG. 4 is a diagram illustrating the relationship between CQI and CIR when CQI interpolation processing is applied. As shown in FIG. 4, even in a subframe in which CQI has not been reported, the radio base station apparatus predicts the fluctuation of the propagation environment based on the demodulation result of the TPC bit, so that the radio base station apparatus can select and adapt the user with a CQI value closer to the actual propagation environment. Modulation can be performed.

  In FIG. 4, when the upward arrow indicates that the TPC bit received in that slot is “1”, that is, a request to increase transmission power, the downward arrow indicates that the TPC bit is “0”, that is, a request to decrease transmission power. Since this example shows an example in which 3 slots are included per 1 subframe, there are also 3 TPC bits per 1 subframe.

  In the example of FIG. 4, since the actual propagation environment is improved in Subframe # 0, the CICH of CPICH is increasing. For this reason, the TPC bit is sent with all three slots “0” requesting to lower the transmission power. As a result, the radio base station apparatus adds +3 to reflect the change in the CQI value.

  Next, in Subframe # 1, the CICH of the CPICH indicating the actual propagation environment is once increased and then decreased, so that the TPC bits are set to “0”, “0”, “1”, that is, transmission power. A request for lowering is sent in 2 slots, and a request for raising is sent in 1 slot.

  In such a case, the radio base station apparatus adds “+1” obtained by integrating “+1”, “+1”, and “−1” to the CQI value. By performing such an operation up to the subframe in which the next CQI is transmitted, that is, subframe # 5 in this example, the temporal fluctuation of the propagation environment in the section where the CQI is not received is estimated and reflected in the CQI value. It becomes possible to make it. Note that the value integrated with the CQI value is not limited to “+1” and “−1”, but can be similarly applied when set to an arbitrary value.

  However, in the example of FIG. 4, the CQI interpolation process is based on the premise that the received TPC bit correctly represents the state of the propagation path. Therefore, when the TPC bit includes a bit error, the interpolation process does not function correctly, and the CQI There may be a case where the value is erroneously interpolated.

  As a result, the reliability of the CQI value is lowered, and the modulation scheme and the next packet transmission user are determined based on incorrect channel estimation information. Therefore, there is a possibility that the throughput is deteriorated as compared with the case where the interpolation process is not performed. is there.

  Examples in which errors are included in the TPC bits used for interpolation are also shown in FIGS. FIG. 4 shows a case where the CQI reporting period is 4 subframes, and FIG. 5 shows a case where the reporting period is 8 subframes. Here, an example in which three TPC bits are included per subframe is illustrated, but the present invention can be similarly applied to cases where the number of TPC bits is different.

  Various interpolation methods are conceivable, but in this case, the number of bits (downward arrow in FIG. 4) requested to reduce the power among the 3 TPC bits per subframe is larger ( Subframe # 0), it is estimated that the propagation environment is improved, and the latest CQI value received is corrected by an interpolation value “+3” corresponding to 3 bits as a CQI value.

  Conversely, if the number of bits (upward arrow in FIG. 4) requesting to increase the power is larger (Subframe # 2), the propagation environment is estimated to be worse and the latest received A CQI value is obtained by correcting the CQI value by “−3”, which is an interpolation value for 3 bits. The purpose is to bring the CQI value closer to the actual propagation environment fluctuation curve (equivalent to the CIR of CPICH) by performing such subframes every time until such CQI is newly received from the mobile device.

  However, in this method of interpolating all TPC bits, as described above, when the TPC bits shown in FIG. 4 and FIG. There is a problem that the CQI value may be interpolated in the direction.

  In the example of FIG. 4, the actual propagation path condition is improved in the subframe # 0 section, and all three TPC bits indicate a request to reduce power. In this case, as the CQI interpolation process, +3 is added to the received CQI value. On the other hand, in the case where an error is included in the TPC bit, an example in which 1 bit out of 3 bits is received in error is shown. In this case, as the CQI interpolation process, +1 is added to the received CQI value, and it becomes difficult to accurately reflect the actual propagation path situation, and an error between the CQI value and the actual propagation path situation. Becomes larger.

  Also, this error becomes more prominent as the CQI reporting period is longer. FIG. 5 shows an example in which the CQI reporting period is longer than that in FIG. 4. In this case, since the error of the TPC bit has a longer time effect, the CQI interpolation error is larger. It can be seen from the comparison.

  As described above, according to the CDMA base station apparatus of the present embodiment, by interpolating CQI with only TPC bits having a reception quality equal to or higher than a predetermined value among the received TPC bits, appropriate CQI interpolation with TPC bits is performed. Thus, it is possible to appropriately select the transmission user and determine the modulation method, thereby preventing a decrease in throughput.

  In the above description, an ideal example in which the head of the DPCH slot including the TPC bit is synchronized with the head of the subframe of the HS-DPCCH signal including the CQI, and there is no processing delay or propagation delay of the TPC and CQI. Although shown, even if there is a difference between the DPCH and HS-DPCCH timings, the same applies.

  FIG. 6 is a diagram illustrating an example of transmission timing and reception timing of each channel. FIG. 6 shows a method of applying the present invention when the DPCH and HS-DPCCH timings are shifted.

  The mobile device measures the reception power of the CPICH transmitted from the radio base station apparatus in the CQI measurement section (Subframe # 1) shown in FIG. 6, and determines the CQI transmission value indicating the current reception environment. Thereafter, the CQI determined in Subframe # 2 is transmitted to the radio base station apparatus. The radio base station apparatus determines the user who transmits the packet and the modulation method from the received CQI value of each mobile device. Next, it is necessary to notify the user of the determined transmission user and modulation scheme through a channel called HS-SCCH.

  An example of application of interpolation of the CQI value indicated by the CQI interpolation process 601 will be described. In this case, the radio base station apparatus selects a transmission user / modulation method using CQI # 0 reported from the mobile station in Subframe # 2, and transmits the information to the mobile station using the HS-SCCH of Subframe # 5. There is a need. In this example, in order to interpolate the time variation between the CQI measurement end timing t0 and the actual HS-SCCH transmission timing t1, the TPC bits from CFN # 0 slots # 6 to # 12 of DPCH received during that time are used. Is possible.

  In this way, by adding the TPC bits from t0 when the mobile station measures CQI to t1 which is the HS-SCCH transmission timing to interpolation, it is possible to perform interpolation of CQI values in consideration of propagation delay and processing delay. It becomes.

  Similarly, in CQI interpolation processing 602, since CQI # 1 has not been received yet at the time of Subframe # 8 HS-SCCH transmission, propagation between t0 and t2 depends on the value of CQI # 0 and the corresponding TPC bit. Interpolate environmental fluctuations. The TPC bits used here are CFN # 0 slot # 6 to CFN # 1 slot # 6.

  It should be noted that there may be situations where it is difficult to reflect all the TPC bits shown here due to restrictions on processing time, etc. in implementation, but interpolation is also performed using TPC bits in a range that can be reflected in this case as well. This is a configuration that can be substituted. The reliability determination of the TPC bit can also be performed using information other than SIR.

(Embodiment 2)
FIG. 7 is a block diagram showing a configuration of a CDMA base station apparatus according to Embodiment 2 of the present invention. 1 identical to those in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed descriptions thereof are omitted. The CDMA base station apparatus 700 of FIG. 7 includes a previous slot SIR buffer unit 701, a difference calculation unit 702, an SIR comparison circuit 703, and a CQI interpolation unit 704, and measures the previous slot when performing CQI interpolation. The difference between the SIR and the measured SIR of the current slot is calculated, and when this value is equal to or smaller than a predetermined threshold, the TPC bit of the current slot is not used for CQI interpolation, which is different from the CDMA base station apparatus of FIG.

  In FIG. 7, the previous slot SIR buffer unit 701 stores the SIR value calculated by the SIR calculation unit 111 via the difference calculation unit 702.

  The difference calculation unit 702 calculates a difference between the SIR value of the current slot calculated by the SIR calculation unit 111 and the SIR value of the previous slot previously buffered by the previous slot SIR buffer unit 701 and outputs the difference to the SIR comparison circuit 703. To do.

  The SIR comparison circuit 703 compares the SIR difference value calculated by the difference calculation unit 702 with a threshold value SIRth2 that can be arbitrarily set, and if the SIR difference value falls below SIRth2, the CQI interpolation unit 704 An instruction not to add the slot TPC bit to the interpolation target is issued.

  The CQI interpolation unit 704 adds the interpolation value based on the likelihood of the TPC bit to the CQI value received by the demodulation unit 108 for HS-DPCCH. When the SIR comparison circuit 703 gives an instruction not to add the TPC bit of the current slot to the interpolation target, the CQI interpolation unit 704 adds the TPC bit of the current slot to the CQI value received by the demodulation unit 108 for the HS-DPCCH. Do not add interpolation values based on likelihood.

  As described above, according to the CDMA base station apparatus of the present embodiment, when the propagation environment does not vary between the slots, the interpolation accuracy is lowered because the interpolation by the TPC bit is not performed and unnecessary interpolation is not performed. This can be suppressed, and the degradation of throughput can be improved.

(Embodiment 3)
FIG. 8 is a block diagram showing a configuration of a CDMA base station apparatus according to Embodiment 3 of the present invention. 1 identical to those in FIG. 1 are assigned the same reference numerals as in FIG. 1, and detailed descriptions thereof are omitted. The CDMA base station apparatus 800 in FIG. 8 includes a TPC bit demodulation result buffer unit 801, a likelihood determination unit 802, a likelihood determination threshold value calculation unit 803, and a CQI interpolation unit 804. The likelihood of the TPC bit is calculated by comparing the average value of the soft values after demodulation over a plurality of slots and the threshold value calculated by the average value of the communication quality SIR of the corresponding DPCH, and is used for CQI interpolation. 1 is different from the CDMA base station apparatus in FIG.

  In FIG. 8, a TPC bit demodulation result buffer unit 801 temporarily accumulates the soft values of the TPC bit demodulation results for each slot extracted by the demodulation unit 107, and averages the soft values among arbitrary slots.

  The likelihood determination threshold value calculation unit 803 averages the SIR of the corresponding slot calculated by the SIR calculation unit 111 in the same interval as the averaging interval of the TPC demodulation result, and multiplies by an arbitrary coefficient to determine the likelihood. The value α is calculated and output to the likelihood determination unit 802.

  The likelihood determination unit 802 compares the soft value average value of the TPC demodulation result with the likelihood determination threshold value α. In the comparison result, when the average value of the soft values is lower than the likelihood determination threshold value α, the likelihood determination unit 802 performs CQI interpolation in the CQI interpolation unit 804 for all the TPC bits in a plurality of slots to be averaged. An instruction to exclude it from processing is issued.

  The CQI interpolation unit 804 adds the interpolation value based on the likelihood of the TPC bit to the CQI value received by the demodulation unit 108 for HS-DPCCH. When an instruction to exclude all TPC bits in a plurality of slots targeted for averaging from being subjected to CQI interpolation processing in the CQI interpolation unit 804 is issued, the CQI interpolation unit 804 performs TPC in a plurality of slots targeted for averaging. Do not accumulate interpolation values using bits.

  As described above, according to the CDMA base station apparatus of the present embodiment, the threshold value calculated by the average value of the soft values after demodulation of the TPC bits over a plurality of slots and the average value of the communication quality SIR of the corresponding DPCH. By calculating the likelihood of the TPC bit by comparing the value and determining whether to use for the CQI interpolation, it is possible to obtain the likelihood for the soft value average value of the TPC bits of a plurality of slots. Thus, the reliability of the TPC bit can be obtained with higher accuracy than when the likelihood for the TPC bit is obtained, and throughput degradation due to an error in the TPC bit can be suppressed.

  The first to third embodiments of the present invention have been described by taking the case where they are used singly as an example, but it is also possible to combine the respective embodiments.

  The present invention is not limited to the above-described embodiment, and can be implemented with various modifications. For example, in the above-described embodiment, the case of performing as a CDMA base station apparatus has been described. However, the present invention is not limited to this, and this wireless communication method can also be performed as software.

  For example, a program for executing the wireless communication method may be stored in advance in a ROM (Read Only Memory), and the program may be operated by a CPU (Central Processor Unit).

  A program for executing the above wireless communication method is stored in a computer-readable storage medium, the program stored in the storage medium is recorded in a RAM (Random Access Memory) of the computer, and the computer operates according to the program. You may make it let it.

  The present invention is suitable for use in wireless communication that performs mobile communication.

FIG. 1 is a block diagram showing a configuration of a CDMA base station apparatus according to Embodiment 1 of the present invention. The flowchart which shows operation | movement of the CDMA base station apparatus of the said embodiment. The figure which shows the relationship between CQI and CIR when not applying the interpolation process of CQI The figure which shows the relationship between CQI and CIR at the time of applying the interpolation process of CQI The figure which shows the relationship between CQI and CIR at the time of applying the interpolation process of CQI The figure which shows an example of the transmission timing and reception timing of each channel Block diagram showing the configuration of a CDMA base station apparatus according to Embodiment 2 of the present invention Block diagram showing the configuration of a CDMA base station apparatus according to Embodiment 3 of the present invention

Explanation of symbols

103, 104, 105 Despreading unit 106, 107, 108 Demodulation unit 111 SIR calculation unit 112, 704, 804 CQI interpolation unit 113 Transmission user / modulation / demodulation determination unit 114 Adaptive encoding / modulation unit 115, 116 Modulation unit 117, 118, 119 Spreading unit 120 Signal multiplexing unit 121 Transmission unit 122, 703 SIR comparison circuit 123 TPC bit reliability determination unit 701 Previous slot SIR buffer unit 702 Difference calculation unit 801 TPC demodulation result buffer unit 802 Likelihood determination unit 803 Likelihood determination threshold Value calculator

Claims (5)

Receiving means for receiving a radio signal including a TPC bit that is transmission power control information and a CQI that is propagation path environment information;
SIR calculation means for measuring the reception quality of the received TPC bits;
A determination means for determining that the TPC bit is reliable when the reception quality is equal to or higher than a predetermined threshold;
Interpolating means for interpolating CQI using the TPC bit when the TPC bit is determined to be reliable, and not performing CQI interpolation using the TPC bit when the TPC bit is not determined to be reliable;
A determining means for determining a transmission user, a modulation method, and a coding method by the CQI after interpolation;
An adaptive encoding / modulating means for modulating transmission data in accordance with a transmission user and a modulation method and an encoding method determined by the determining means;
The adaptive encoding / modulating means comprises: a transmitting means for transmitting modulated transmission data as a radio signal.   2. The CDMA base station apparatus according to claim 1, wherein the interpolating means interpolates using a TPC bit from the reception of CQI to the transmission of transmission data. Buffer means for storing the reception quality of the TPC bits;
Difference calculating means for taking a difference between the reception quality of the previously received TPC bit and the reception quality of the newly received TPC bit;
The determination means determines whether the difference is within a predetermined range;
The interpolation means interpolates CQI using the TPC bit when the difference is not within a predetermined range, and does not perform CQI interpolation using the TPC bit when the difference is within the predetermined range. The CDMA base station apparatus according to claim 1 or 2, characterized in that: TPC demodulation result buffer means for adding a plurality of demodulated TPC bits;
A likelihood determination threshold value calculation means for averaging the reception quality of the TPC bits in the section added in the TPC demodulation result buffer means and calculating the threshold value from the averaged reception quality;
The determining means uses the threshold value calculated by the likelihood determination threshold value calculating means to determine that the TPC bit is reliable when the reception quality is equal to or higher than a predetermined threshold value. The CDMA base station apparatus according to any one of claims 1 to 3. A radio signal including a TPC bit that is transmission power control information and a CQI that is propagation path environment information is received,
Measure the reception quality of the received TPC bit,
If the reception quality is equal to or higher than a predetermined threshold, it is determined that the TPC bit is reliable,
If it is determined that the TPC bit is reliable, the CQI is interpolated using the TPC bit. If the TPC bit is not determined to be reliable, the CQI interpolation using the TPC bit is not performed.
The CQI after interpolation determines the transmission user, modulation method and coding method,
Modulate the transmission data with the determined transmission user and modulation method, coding method,
A wireless communication method characterized by transmitting modulated transmission data as a wireless signal.

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