JP2005064947A - Radio communication apparatus and reception quality reporting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the transmission efficiency and increase the system capacity by reducing the number of retransmission times of packets. <P>SOLUTION: An SIR measuring unit 107 measures the reception SIR from received signals. A reception quality decider 108 measures the quality of decoded data to output number of retransmission times information to a CQI selection adjuster 111. An fD estimator 109 estimates the fD from the received signals to estimate the relative moving speed to a base station apparatus. An adjustable step controller 110 selects a correction width according to the fD. The CQI selection adjuster 111 determines the final correction width and the correcting direction of a threshold for selecting the CQI, based on the number of retransmission times information and correction width information. A CQI selector 112 compares a corrected threshold according to an instruction from the CQI selection adjuster 111 with the reception SIR to select a CQI. A multiplexer 113 multiplexes transmission data to be sent to the base station apparatus with the CQI. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio communication apparatus and a reception quality report method, and more particularly to a radio communication apparatus and a reception quality report method that perform high-speed packet transmission using a shared channel.

  2. Description of the Related Art Conventionally, a downlink high-speed packet transmission scheme (for example, HSDPA (High Speed Downlink Packet Access)) in which a plurality of communication terminal apparatuses share a high-speed and large-capacity downlink channel and perform high-speed packet transmission has been developed. In this transmission method, techniques such as a scheduling technique and an adaptive modulation technique are used to increase transmission efficiency. Scheduling technology means that each communication terminal device observes the state of the downlink propagation path, the base station device compares the propagation environments reported from each communication terminal device, and packets are transmitted to communication terminal devices with good propagation environments. It is a technology to transmit. Here, the state of the downlink propagation path measured by the communication terminal apparatus is called CQI (Channel Quality Indicator). The communication terminal device stores the reception quality information in which the reception SIR and the CQI are related as shown in FIG. 17, and by referring to the reception quality information using the reception SIR measured at a predetermined timing, The maximum CQI that provides a predetermined reception quality is selected. Here, a high CQI has a high transmission rate but is vulnerable to transmission errors. A low CQI has a low transmission rate but is resistant to transmission errors.

  In addition, the base station apparatus performs sequence control such as preferentially transmitting data that needs to be retransmitted in consideration of transmission efficiency for individual communication terminal apparatuses. The adaptive modulation technique is a technique in which a base station apparatus adaptively changes a modulation scheme or a coding rate (MCS (Modulation and Coding Scheme)) according to a CQI report value. When the high-speed packet transmitted from the base station apparatus does not satisfy the predetermined reception quality in the communication terminal apparatus, the base station apparatus retransmits the packet.

Conventionally, a base station apparatus is known that changes a threshold value when selecting an MCS according to a propagation environment (for example, Patent Document 1). At this time, the base station apparatus sets an optimum modulation scheme and coding rate by adjusting a threshold value when selecting the MCS based on the number of retransmissions.
JP 2003-37554 A

  However, in the conventional wireless communication device, since MCS selection is performed based on the report by CQI, even if the threshold value at the time of MCS selection is adjusted, if CQI does not correctly reflect the propagation environment, CQI The MCS selected based on is also inaccurate. As a result, there is a problem that the transmission efficiency is lowered due to repeated retransmission of packets.

  In addition, in the conventional wireless communication apparatus, when the propagation environment fluctuates greatly, such as when the relative movement speed with respect to the communication partner is large, the CQI is selected even when the optimum CQI corresponding to the propagation environment is selected when selecting the CQI. When the received base station apparatus transmits packet data by encoding or the like based on CQI, the propagation environment may vary compared to when CQI is selected. In such a case, even if the accuracy of CQI selection is improved, an error occurs in the packet data encoded based on the CQI, and the retransmission of the packet is repeated, resulting in a decrease in transmission efficiency and transmission. There is a problem that the system capacity is limited due to a decrease in efficiency.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless communication apparatus and a reception quality reporting method capable of improving transmission efficiency and increasing system capacity by reducing the number of packet retransmissions. And

  The wireless communication apparatus according to the present invention includes a propagation environment estimation unit that estimates a propagation environment from a received signal, a propagation environment state estimated by the propagation environment estimation unit, and communication quality information that is information indicating communication quality with a communication partner. Based on the threshold value setting means for setting the threshold value variably, the reception quality report value is determined by comparing the threshold value set by the threshold value setting means with the measured value indicating the reception quality. The reception quality report value determining means for transmitting and the transmission means for transmitting information on the reception quality report value determined by the reception quality report value determining means to the communication partner are employed.

  According to this configuration, the propagation environment condition is estimated, and the threshold value correction range when selecting the reception quality report value using the measurement value indicating the reception quality is adaptive according to the estimated propagation environment condition. Because it is changed, it is possible to prevent erroneous reception quality report value selection due to threshold settings that do not accurately reflect the propagation environment, and to improve transmission efficiency and increase system capacity by reducing the number of packet retransmissions. Can be achieved.

  In the wireless communication device according to the present invention, in the configuration described above, the threshold value setting unit corrects the threshold value so that reception quality is worse as communication quality deteriorates than the communication quality information. A configuration is adopted in which the threshold value is corrected in a direction in which the reception quality is good as the communication quality is good, and the correction range of the threshold value is increased as the fluctuation of the propagation environment estimated by the propagation environment estimation means is severe.

  According to this configuration, in addition to the above effects, when the fluctuation of the propagation environment situation is severe, it is possible to shorten the time until the appropriate threshold value is set by increasing the correction width. In the case where the fluctuation of the signal is gradual, the correction range can be reduced to improve the followability to a slight fluctuation of the propagation environment state.

  In the wireless communication device according to the present invention, in the configuration, the propagation environment estimation unit measures a relative moving speed with respect to a communication partner from a received signal, and the reception quality report value determination unit is measured by the propagation environment estimation unit. In addition, the threshold value correction range is increased as the relative movement speed increases.

  According to this configuration, in addition to the above-described effect, when the relative movement speed with respect to the communication partner is large, it is possible to shorten the time until the appropriate threshold is set by increasing the correction range. When the relative movement speed with respect to is small, the correction width can be reduced to improve the followability to a slight change in the propagation environment state.

  In the wireless communication apparatus according to the present invention, in the configuration, the propagation environment estimation unit estimates a delay spread from a delay profile, and the reception quality report value determination unit has a long delay spread estimated by the propagation environment estimation unit. A configuration is adopted in which the threshold value correction width is increased.

  According to this configuration, in addition to the above-described effects, it is possible to determine a drastic change in the propagation environment state due to the multipath environment based on the spread of the delay spread, and select a threshold correction width according to the spread of the delay spread. Therefore, it is possible to select a reception quality report value that accurately corresponds to the communication quality.

  The wireless communication apparatus of the present invention comprises a setting time constant control means for setting a measurement time for measuring the communication quality in the configuration, wherein the threshold setting means is set by the setting time constant control means. Further, a configuration is adopted in which the threshold value is variably set for each measurement time based on the communication quality information and the propagation environment state estimated by the propagation environment estimation means.

  According to this configuration, in addition to the above effect, by setting an appropriate averaging time constant, it is possible to accurately measure the communication quality, so it is possible to accurately report the reception quality using accurate communication quality information. A value can be selected.

  The radio communication apparatus according to the present invention employs a configuration in which, in the configuration, the setting time constant control unit sets the measurement time to be shorter as the variation in the propagation environment state estimated by the propagation environment estimation unit is more severe.

  According to this configuration, in addition to the above-described effects, the time for measuring communication quality can be shortened by setting a short averaging time constant when the fluctuation of the propagation environment is severe, and long when the fluctuation of the propagation environment is moderate. By setting the averaging time constant, it is possible to lengthen the time for measuring the communication quality, so it is possible to measure the accurate communication quality according to the propagation environment.

  The radio communication apparatus according to the present invention has the configuration described above, wherein the propagation environment estimation unit measures a relative moving speed with respect to a communication partner from a received signal, and the set time constant control unit measures the propagation environment estimation unit. A configuration is adopted in which the measurement time is shortened as the relative movement speed increases.

  According to this configuration, in addition to the above effects, when the relative movement speed with respect to the communication partner is large, the time for measuring the communication quality can be shortened by setting a short averaging time constant. When the relative movement speed is slow, it is possible to lengthen the communication quality measurement time by setting a long averaging time constant, so measure the accurate communication quality according to the relative movement speed with respect to the communication partner. be able to.

  In the wireless communication apparatus according to the present invention, in the configuration, the propagation environment estimation unit estimates a delay spread from a delay profile, and the set time constant control unit has a long delay spread estimated by the propagation environment estimation unit. A configuration is adopted in which the measurement time is set shorter.

  According to this configuration, in addition to the above effect, when the delay spread is long, the time for measuring the communication quality can be shortened by setting a short averaging time constant. When the delay spread is short, By setting a long averaging time constant, the time for measuring the communication quality can be lengthened, so that the accurate communication quality corresponding to the spread of the delay spread can be measured.

  In the wireless communication device according to the present invention, in the configuration described above, the propagation environment estimation means includes a power density of a power density of a received signal from a base station device of its own cell with respect to a power density of a received signal from a base station device of another cell. The reception quality report value determination means adopts a configuration in which the threshold value correction width is increased as the power density ratio is increased.

  According to this configuration, in addition to the above-described effects, for example, by calculating the power density ratio of the power density of the received signal of the base station device in the own cell to the power density of the received signal of the base station device of another cell, As well as knowing the position of the own station in the cell, multipath interference is strong when it is close to the base station apparatus of the own cell. When close to the base station apparatus, the multipath interference is not so strong, so that the fluctuation of the propagation environment can be followed by reducing the correction width. Thereby, it is possible to select an accurate reception quality report value corresponding to the distance from the base station apparatus.

  In the wireless communication device according to the present invention, in the configuration described above, the propagation environment estimation means includes a power density of a power density of a received signal from a base station device of its own cell with respect to a power density of a received signal from a base station device of another cell. The setting time constant control means adopts a configuration in which the measurement time is set shorter as the power density ratio is larger.

  According to this configuration, in addition to the above-described effects, for example, by calculating the power density ratio of the power density of the received signal of the base station device in the own cell to the power density of the received signal of the base station device of another cell, As well as knowing the position of the own station in the cell, if it is close to the base station device of the own cell, the multipath interference is strong, so the time for measuring the communication quality can be shortened by setting a short averaging time constant, Multipath interference is not so strong when it is close to the base station device of another cell adjacent to its own cell that is a distant base station device, so the time to measure communication quality is lengthened by setting a long averaging time constant be able to. Thereby, the exact communication quality according to the distance with a base station apparatus can be measured.

  A communication terminal apparatus according to the present invention employs a configuration including any one of the wireless communication apparatuses described above.

  According to this configuration, the propagation environment is estimated, and the threshold correction width when the CQI is selected using the measurement value indicating the reception quality is adaptively changed according to the estimated propagation environment. It is possible to prevent erroneous CQI selection by setting a threshold value that does not accurately reflect the environment, and it is possible to improve transmission efficiency and increase system capacity by reducing the number of packet retransmissions.

  The base station apparatus of the present invention employs a configuration including any one of the wireless communication apparatuses described above.

  According to this configuration, the propagation environment is estimated, and the correction range of the threshold value when the reception quality report value is selected using the measurement value indicating the reception quality is adaptively changed according to the estimated propagation environment. Therefore, it is possible to prevent erroneous reception quality report value selection by setting a threshold value that does not accurately reflect the propagation environment, and to improve transmission efficiency and increase system capacity by reducing the number of packet retransmissions. Can do.

  The reception quality reporting method of the present invention is based on the step of estimating the propagation environment from the received signal, the estimated propagation environment state, and the communication quality information which is information indicating the communication quality with the communication partner. Variable, a step of determining a reception quality report value by comparing the threshold value and a measurement value indicating reception quality, and information on the determined reception quality report value to the communication partner. And a step of transmitting.

  According to this method, the propagation environment is estimated, and the correction range of the threshold value when selecting the reception quality report value using the measurement value indicating the reception quality is adaptively changed according to the estimated propagation environment. Therefore, it is possible to prevent erroneous reception quality report value selection by setting a threshold value that does not accurately reflect the propagation environment, and to improve transmission efficiency and increase system capacity by reducing the number of packet retransmissions. Can do.

  The reception quality reporting method of the present invention is the above-described method, wherein the threshold is corrected in a direction in which the reception quality is worse as the communication quality is deteriorated than the communication quality information, and the communication quality is better than the communication quality information. The threshold value is corrected in a direction in which the reception quality is good, and the correction range of the threshold value is increased as the estimated propagation environment state changes more drastically.

  According to this method, in addition to the above-described effect, for example, when the relative movement speed with respect to the base station apparatus is large, it is possible to shorten the time until the appropriate threshold is set by increasing the correction width, When the relative movement speed with respect to the base station apparatus is small, the follow-up property to a slight change in the propagation environment can be improved by reducing the correction width.

  According to the present invention, it is possible to improve transmission efficiency and increase system capacity by reducing the number of packet retransmissions.

  The gist of the present invention is to estimate a propagation environment (relative movement speed) with a communication partner, and to compare with a measured value indicating reception quality using the estimated propagation environment and communication quality information (retransmission count information). It is to correct the threshold value. At this time, when the estimated propagation environment varies greatly, the threshold value correction width is increased as compared with the case where the estimated propagation environment is moderate.

  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 radio communication apparatus 100 according to Embodiment 1 of the present invention.

  The duplexer 102 outputs the reception signal received by the antenna 101 to the reception RF unit 103 and transmits the transmission data input from the transmission RF unit 116 from the antenna 101.

  The reception RF unit 103 converts the radio frequency reception signal input from the duplexer 102 into a baseband digital signal and outputs it to the despreading unit 104.

  Despreading section 104 performs despreading processing on the baseband signal input from reception RF section 103 and outputs the result to RAKE combining section 105 and maximum Doppler frequency (hereinafter referred to as “fD”) estimation section 109.

  The RAKE combining unit 105 performs RAKE combining of the despread path signals input from the despreading unit 104 and outputs the combined signals to the demodulation unit 106 and the SIR measurement unit 107.

  Demodulation section 106 demodulates the signal after RAKE combining input from RAKE combining section 105 to obtain demodulated data, and outputs the demodulated data to reception quality determining section 108.

  SIR measurement section 107 measures SIR indicating reception quality from the despread signal input from RAKE combining section 105 and outputs the measured SIR to CQI selection section 112.

  The reception quality judgment unit 108 measures the quality of the demodulated data input from the demodulation unit 106 for a predetermined time, and information on the number of packets whose quality is poor every predetermined time and needs to be retransmitted every time the predetermined time has passed, that is, the number of retransmissions Information (communication quality information) is output to CQI selection adjustment section 111. The quality of the demodulated data is determined by using a result obtained by decoding an error detection code (CRC (Cyclic Redundancy Check) or the like) included in the received signal. Note that the method of determining the quality of the demodulated data is not limited to using an error detection code, and can be determined by any method.

  Based on the despread signal input from the despreading section 104, the fD estimation section 109, which is a propagation environment estimation means, estimates fD of the propagation environment in the downlink. The estimated fD corresponds to the relative movement speed between the communication terminal apparatus and the base station apparatus. The higher the fD, the faster the relative movement speed, and the more rapid the propagation environment changes, and the lower the fD, the relative movement speed. Means that the propagation environment is slow and slow. The fD estimation unit 109 outputs the fD estimation result to the adjustment step control unit 110. For the fD estimation method, the technique disclosed in Japanese Patent Application Laid-Open No. 2002-152088 can be used.

  The adjustment step control unit 110 determines the correction width of the threshold set in the CQI selection adjustment unit 111 described later based on the fD estimation result of the propagation channel input from the fD estimation unit 109, and the determined correction width information Is output to the CQI selection adjustment unit 111. That is, when the adjustment step control unit 110 estimates that fD is high, the fluctuation of the propagation path is abrupt, so that it takes a long time to set an appropriate threshold value with a gradual adjustment. The correction width information to be output is output. On the other hand, when it is estimated that fD is low, adjustment step control unit 110 outputs correction width information for making a small correction width in order to accurately follow a gentle fluctuation. A method for determining the adjustment step in the adjustment step control unit 110 will be described later.

  The CQI selection adjustment unit 111 serving as a threshold setting unit determines a CQI as a reception quality report value from the number of retransmissions information input from the reception quality determination unit 108 and the correction width information input from the adjustment step control unit 110. At this time, the threshold value to be compared with the received SIR is corrected. That is, the CQI selection adjustment unit 111 determines whether to correct the threshold value to the higher reception SIR or to correct the threshold value to the lower reception SIR from the number of retransmissions information, and in advance to the determined direction. It is determined to move the threshold value by the set correction width (hereinafter referred to as “reference correction width”). Furthermore, the CQI selection adjustment unit 111 adds or subtracts a correction width according to the relative movement speed with the base station device from the correction width information input from the adjustment step control unit 110 with respect to the reference correction width. The final correction width corresponding to the relative movement speed with the base station apparatus is determined, and the determined final correction width information is output to the CQI selection unit 112. Note that a threshold value correction method in the CQI selection adjustment unit 111 will be described later.

  The CQI selection unit 112, which is a reception quality report value determination means, has a reference table that stores reception quality information in which reception SIRs and CQIs are associated with each other. In this reference table, the reception SIR is delimited in advance by a predetermined interval threshold value, and different CQIs are selected for each range delimited by the threshold value. The CQI selection unit 112 corrects the threshold value of the reception quality information based on the final correction width information input from the CQI selection adjustment unit 111. Then, CQI selection section 112 selects the CQI and outputs it to multiplexing section 113 by referring to the reference table using received SIR input from SIR measurement section 107 and comparing it with a threshold value.

  Multiplexer 113 multiplexes the CQI input from CQI selector 112 and the transmission data, and outputs the multiplexed data to modulator 114.

  Modulating section 114 modulates transmission data including CQI input from multiplexing section 113 and outputs the modulated transmission data to spreading section 115.

  Spreading section 115 spreads the modulated transmission data input from modulation section 114 and outputs the result to transmission RF section 116.

  The transmission RF unit 116 converts the spread baseband frequency transmission data input from the spreading unit 115 into a radio frequency analog signal and outputs the analog signal to the duplexer 102. In general, the CQI is transmitted as the reception quality report value when the radio communication apparatus 100 is applied to a communication terminal apparatus. When the radio communication apparatus 100 is applied to a base station apparatus, the radio communication apparatus 100 A reception quality report value different from the CQI and corresponding to the CQI is transmitted to the communication terminal apparatus.

  Next, the operation of the wireless communication apparatus 100 will be described using FIG. 2 and FIG. FIG. 2 is a flowchart showing the operation of the wireless communication apparatus 100, and FIG. 3 shows a reference table for storing correction width information relating the fD and the adjustment step of the adjustment step control unit 110. .

  First, fD estimation section 109 estimates fD from the received signal subjected to the despreading process (step ST201).

  Next, adjustment step control section 110 determines whether or not estimated fD is smaller than 60 Hz (step ST202).

  When fD is smaller than 60 Hz, adjustment step control unit 110 refers to correction width information in FIG. 3 and selects 0.1 dB as adjustment step H (step ST203).

  If fD is not smaller than 60 Hz, adjustment step control section 110 determines whether or not estimated fD is smaller than 120 Hz (step ST204).

  When fd is smaller than 120 Hz, the adjustment step control unit 110 selects 0.2 dB as the adjustment step H by referring to the correction width information in FIG. 3 (step ST205).

  When fD is not smaller than 120 Hz, the adjustment step control unit 110 selects 0.5 dB as the adjustment step H by referring to the correction width information in FIG. 3 (step ST206).

  Next, reception quality determination section 108 determines whether or not the number of retransmissions is greater than or equal to the first threshold value based on the number of retransmissions information (step ST207).

  When the number of retransmissions is equal to or greater than the first threshold, the CQI selection adjustment unit 111 determines that the communication quality has deteriorated, and adds the adjustment step H to the preset reference correction width (step ST208).

  Then, CQI selection adjustment section 111 corrects the threshold for selecting CQI in the direction of higher reception SIR by the correction width obtained by adding adjustment step H to the reference correction width (step ST209).

  If the number of retransmissions is not greater than or equal to the first threshold, CQI selection adjustment section 111 determines whether or not the number of retransmissions is less than or equal to the second threshold (first threshold ≧ second threshold). Is determined (step ST210). When the number of retransmissions is equal to or smaller than the second threshold value, CQI selection adjustment section 111 subtracts adjustment step H from a preset reference correction width (step ST211).

  Then, CQI selection adjustment section 111 corrects the threshold for CQI selection in the direction of lower reception SIR by the correction width obtained by subtracting adjustment step H from the reference correction width (step ST212).

  On the other hand, when the number of retransmissions is not less than or equal to the second threshold value in step ST210, CQI selection adjustment section 111 does not correct the threshold value. That is, if the number of retransmissions is less than the first threshold value and greater than the second threshold value, the CQI selection adjustment unit 111 is not abrupt and gradual in the propagation environment. The value is not corrected.

  Next, SIR measurement section 107 measures the received SIR from the received signal (step ST213).

  Next, CQI selecting section 112 selects the CQI corresponding to the measured received SIR by comparing the measured received SIR with the threshold value of the corrected reference table (step ST214).

  Next, a method for changing the threshold correction width according to fD in CQI selection section 112 will be described in more detail with reference to FIG.

  It is assumed that fD is 130 Hz and the number of retransmissions is less than the threshold value at time t1. At this time, the CQI selection adjustment unit 111 determines that the communication quality is good, and determines to correct the threshold value in the direction of lower reception SIR (downward in FIG. 4). Then, the CQI selection adjustment unit 111 selects 0.5 dB as the adjustment step H with reference to the reference table of FIG. 3 because fD is 130 Hz, and the reference correction is performed because the number of retransmissions is less than the threshold value. Since the width is 0 dB, 0.5 dB is output to the CQI selection unit 112 as final correction width information. The CQI selection unit 112 newly sets threshold values at positions of 1.5 dB and 0.5 dB, which are 0.5 dB smaller, for each of 2 dB and 1 dB which are the current threshold setting values.

  It is assumed that fD is 30 Hz and the number of retransmissions is less than the threshold value at time t2. At this time, the CQI selection / adjustment unit 111 determines that the communication quality is good and determines to correct the threshold value in the direction of lower reception SIR. The CQI selection / adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table in FIG. 3 because fD is 30 Hz, and the standard correction width is 0 dB. 0.1 dB is output to the CQI selection unit 112. The CQI selection unit 112 newly sets threshold values at positions of 1.4 dB and 0.4 dB, which are 0.1 dB smaller, for each of the current threshold setting values of 1.5 dB and 0.5 dB.

  It is assumed that fD is 140 Hz and the number of retransmissions is equal to or greater than a threshold value at time t3. At this time, the CQI selection adjustment unit 111 determines that the communication quality has deteriorated, and determines to correct the threshold value in the direction of higher reception SIR (upward in FIG. 4). Since the fD is 140 Hz, the CQI selection / adjustment unit 111 selects 0.5 dB as the adjustment step H with reference to the reference table in FIG. 3, and the standard correction width is 0.1 dB. As information, 0.6 dB is output to the CQI selection unit 112. The CQI selection unit 112 newly sets threshold values at positions of 2 dB and 1 dB larger by 0.6 dB for each of the current threshold setting values of 1.4 dB and 0.4 dB.

  It is assumed that fD is 10 Hz and the number of retransmissions is equal to or greater than a threshold value at time t4. At this time, the CQI selection / adjustment unit 111 determines that the communication quality has deteriorated, and determines to correct the threshold value in the direction of higher reception SIR. Since the fD is 10 Hz, the CQI selection adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table in FIG. 3, and the standard correction width is 0.1 dB. 0.2 dB is output to the CQI selection unit 112 as information. The CQI selection unit 112 newly sets threshold values at positions of 2.2 dB and 1.2 dB, which are 0.2 dB larger, for each of 2 dB and 1 dB which are the current threshold setting values.

  It is assumed that fD is 0 Hz and the number of retransmissions is equal to or greater than a threshold value at time t6. At this time, the CQI selection / adjustment unit 111 determines that the communication quality has deteriorated, and determines to correct the threshold value in the direction of higher reception SIR. The CQI selection adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table of FIG. 3 because fD is 0 Hz, and the standard correction width is 0.1 dB, so the final correction width 0.2 dB is output to the CQI selection unit 112 as information. The CQI selection unit 112 newly sets a threshold value at positions of 2.4 dB and 1.4 dB which are 0.2 dB larger for each of the current threshold value setting values of 2.2 dB and 1.2 dB.

  In FIG. 4, when CQI # 3 is selected between time t0 and time t1, even if the reception SIR measured between time t1 and time t3 is less than 2 dB, CQI # 2 and CQI # Since the threshold value between 3 and 3 is set low, CQI # 3 can continue to be selected. Furthermore, between time t1 and time t2, the relative movement speed with respect to the base station apparatus increases, but by increasing the threshold correction width according to the relative movement speed, the relative movement speed with respect to the base station apparatus is increased. Since the follow-up threshold value can be set, CQI # 3 can be reliably selected from time t1 to time t2.

  On the other hand, when the measured reception SIR becomes small at time t6, CQI # 2 is selected at 2.4 dB before the reception SIR drops to 2 dB. Therefore, as soon as reception quality starts to deteriorate, CQI # 2 can be selected, and a CQI accurately reflecting the reception quality at that time can be transmitted to the base station apparatus. Furthermore, when the relative movement speed with respect to the base station apparatus is 0 at time t6, the correction width is reduced, so that an accurate CQI can be selected even for a slight change in the measured reception SIR.

  Incidentally, MCS represents a combination of several types of modulation schemes, tens of types of coding rates, tens of types of multiplexed codes, and the like, and there are many variations in the combinations. Therefore, when selecting an MCS, it is difficult to uniquely select an MCS with a threshold based on some index. On the other hand, since CQI is a subset of MCS and is set in several tens of stages in the order of reception quality, it is relatively easy to set a threshold for selecting CQI, and further adjust the threshold. That is effective.

  Thus, according to the first embodiment, when the relative movement speed is high, the threshold correction width is increased, and when the relative movement speed is low, the threshold correction width is decreased. Since the threshold correction width for selecting the CQI can be adaptively set according to the propagation environment, it is possible to prevent retransmission due to erroneous CQI selection, and to retransmit the packet. By reducing the number of times, it is possible to improve transmission efficiency and increase system capacity.

(Embodiment 2)
FIG. 5 is a block diagram showing a configuration of radio communication apparatus 500 according to Embodiment 2 of the present invention. In FIG. 5, parts having the same configuration as in FIG.

  The CQI selection adjustment unit 111 recognizes the CQI selected by the CQI selection unit 112 from the CQI selection information input from the CQI selection unit 112. Then, the CQI selection adjustment unit 111 uses the retransmission number information input from the reception quality determination unit 108 and the correction width information input from the adjustment step control unit 110 to select the selected CQI and the next lower CQI of the selected CQI. Only the threshold is corrected. That is, the CQI selection / adjustment unit 111 corrects the threshold value between the selected CQI and the next lower CQI of the selected CQI so that the reception SIR is higher than the retransmission count information or the reception SIR. It is determined whether the threshold value is corrected to a lower value, and it is determined to move the threshold value by the reference correction width in the determined direction. Furthermore, the CQI selection adjustment unit 111 adds or subtracts a correction width according to the relative movement speed with the base station device from the correction width information input from the adjustment step control unit 110 with respect to the reference correction width. The final correction width corresponding to the relative movement speed with the base station apparatus is determined, and the determined final correction width information is output to the CQI selection unit 112. Note that a threshold value correction method in the CQI selection adjustment unit 111 will be described later.

  The CQI selection unit 112 has a reference table that stores reception quality information in which reception SIR and CQI are related. In this reference table, the reception SIR is delimited in advance by a predetermined interval threshold value, and different CQIs are selected for each range delimited by the threshold value. The CQI selection unit 112 corrects the threshold value of the reception quality information between the last selected CQI and the CQI next to the last selected CQI based on the final correction width information input from the CQI selection adjustment unit 111. . Then, the CQI selection unit 112 selects the CQI and outputs it to the multiplexing unit 113 by referring to the reference table using the received SIR input from the SIR measurement unit 107 and comparing it with the threshold value. The CQI selection information that is CQI information is output to the CQI selection adjustment unit 111.

  Next, a method of changing the threshold correction width according to fD in CQI selection section 112 will be described with reference to FIG.

  It is assumed that fD is 130 Hz and the number of retransmissions is less than the threshold value at time t1. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 3 was selected from the selection CQI information input from the CQI selection unit 112, determines that the communication quality is good, and has a low reception SIR. It is decided to correct the threshold value in the direction (downward direction in FIG. 4). Since the fD is 130 Hz, the CQI selection adjustment unit 111 selects 0.5 dB as the adjustment step H with reference to the reference table of FIG. 3, and the standard correction width is 0 dB. 0.5 dB is output to the CQI selection unit 112 as the final correction width information of the threshold value S1 between 2 and the CQI # 3 next lower than the previously selected CQI. The CQI selection unit 112 newly sets a threshold value between CQI # 3 and CQI # 2 at a position of 1.5 dB which is 0.5 dB smaller than 2 dB which is the current threshold setting value. Set. Note that the CQI is also selected at times other than the times t1 to t6.

  It is assumed that fD is 30 Hz and the number of retransmissions is less than the threshold value at time t2. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 3 was selected from the selection CQI information input from the CQI selection unit 112, determines that the communication quality is good, and has a low reception SIR. Decide to correct the threshold in the direction. Since the fD is 30 Hz, the CQI selection / adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table of FIG. 3, and the standard correction width is 0 dB. Therefore, the CQI # 2 and CQI 0.1 dB is output to the CQI selection unit 112 as the final correction width information of the threshold value S1 with # 3. The CQI selection unit 112 newly sets a threshold value between CQI # 3 and CQI # 2 at a position of 1.4 dB, which is 0.1 dB smaller than the current threshold setting value of 1.5 dB. Set the threshold.

  It is assumed that fD is 140 Hz and the number of retransmissions is equal to or greater than a threshold value at time t3. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 3 was selected from the CQI selection information input from the CQI selection unit 112, determines that the communication quality has deteriorated, and has a higher reception SIR direction. It is determined to correct the threshold value (upward in FIG. 4). The CQI selection adjustment unit 111 selects 0.5 dB as the adjustment step H with reference to the reference table in FIG. 3 because fD is 140 Hz, and the standard correction width is 0.1 dB. And 0.6Q as the final correction width information of the threshold value S1 between CQI # 3 and CQI # 3. The CQI selector 112 newly sets the threshold value between CQI # 3 and CQI # 2 at a position 2 dB that is 0.6 dB larger than the current threshold setting value of 1.4 dB. Set.

  It is assumed that fD is 10 Hz and the number of retransmissions is equal to or greater than a threshold value at time t4. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 3 was selected from the selection CQI information input from the CQI selection unit 112, determines that the communication quality has deteriorated, and determines the reception SIR. Decide to correct the threshold in the higher direction. Since the fD is 10 Hz, the CQI selection / adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table of FIG. 3, and the standard correction width is 0.1 dB, so CQI # 2 And CQI # 3, 0.2 dB is output to the CQI selector 112 as the final correction width information of the threshold value S1. The CQI selecting unit 112 newly sets a threshold value between CQI # 3 and CQI # 2 at a position of 2.2 dB that is 0.2 dB larger than 2 dB that is the current threshold setting value. Set.

  It is assumed that fD is 10 Hz and the number of retransmissions is equal to or greater than a threshold value at time t5. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 2 was selected from the selection CQI information input from the CQI selection unit 112, determines that the communication quality has deteriorated, and determines the reception SIR. Decide to correct the threshold in the higher direction. The CQI selection adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table of FIG. 3 because fD is 10 Hz, and the standard correction width is 0.1 dB. And 0.2Q as the final correction width information of the threshold value S2 between CQI # 2 and CQI # 2. The CQI selection unit 112 sets the threshold value between the previously selected CQI # 2 and the lower-order CQI # 1 next to the previously selected CQI to 0.2 dB from 1 dB that is the current threshold setting value. A new threshold value is set at a large 1.2 dB position.

  It is assumed that fD is 0 Hz and the number of retransmissions is equal to or greater than a threshold value at time t6. At this time, the CQI selection adjustment unit 111 recognizes that the previous CQI # 2 was selected from the selection CQI information input from the CQI selection unit 112, determines that the communication quality has deteriorated, and determines the reception SIR. Decide to correct the threshold in the higher direction. The CQI selection adjustment unit 111 selects 0.1 dB as the adjustment step H with reference to the reference table of FIG. 3 because fD is 0 Hz, and the standard correction width is 0.1 dB. And 0.2Q as the final correction width information of the threshold value S2 between CQI # 2 and CQI # 2. The CQI selection unit 112 newly sets a threshold value between CQI # 2 and CQI # 1 at a position of 1.4 dB, which is 0.2 dB larger than the current threshold setting value of 1.2 dB. Set the threshold.

  As described above, according to the second embodiment, in addition to the effect of the first embodiment, only the threshold value between the CQI selected last time and the CQI next to the CQI selected last time is used as the propagation environment. Since the correction is adaptively performed accordingly, it is possible to prevent erroneously selecting a low CQI when the reception quality does not vary greatly and the reception SIR is low. In addition, when the reception quality varies greatly and the reception SIR is low, a low CQI can be reliably selected. Further, according to the second embodiment, only the threshold value used for CQI selection is corrected, so that the process of correcting the threshold value can be simplified. In particular, when 30 types of CQI are used according to reception quality in HSDPA, it is only necessary to correct one of 29 threshold values, so the threshold value in HSDPA is corrected. The processing at the time can be made extremely simple.

  In the second embodiment, only the threshold value between the CQI selected last time and the CQI next to the CQI selected last time is adaptively corrected. However, the present invention is not limited to this. Only the threshold value between the selected CQI and the next higher CQI of the previously selected CQI may be adaptively corrected. In this case, when the reception quality does not vary greatly and the reception SIR is high, a high CQI can be selected early, and when the reception quality varies greatly and the reception SIR is high, the low CQI is low. Can be selected early. Furthermore, in the second embodiment, only the threshold value between the previously selected CQI and the CQI before and after the previously selected CQI may be adaptively corrected.

(Embodiment 3)
FIG. 7 is a block diagram showing a configuration of radio communication apparatus 700 according to Embodiment 3 of the present invention.

  Radio communication apparatus 700 according to Embodiment 3 is similar to radio communication apparatus 100 according to Embodiment 1 shown in FIG. 1, as shown in FIG. 7, multipath estimation section 701, geometry estimation section 702, and set time constant. A control unit 703 is added. In FIG. 7, parts having the same configuration as in FIG.

  The adjustment step control unit 110 is set in the CQI selection adjustment unit 111 based on the fD estimation result input from the fD estimation unit 109, the delay spread information input from the multipath estimation unit 701, and the geometry information input from the geometry estimation unit 702. The threshold correction width is determined, and the determined correction width information is output to the CQI selection adjustment unit 111. That is, when the adjustment step control unit 110 estimates that fD is high, the fluctuation of the propagation path is abrupt, so that it takes a long time to set an appropriate threshold value with a gradual adjustment. In addition, when fD is estimated to be low, a coefficient with a small correction width is selected in order to accurately follow a gentle fluctuation. Furthermore, the adjustment step control unit 110 selects a coefficient corresponding to the estimated spread of the delay spread, selects a coefficient corresponding to the estimated geometry, and multiplies the selected coefficient according to each fD by the selected coefficient. To calculate the adjustment range. Then, adjustment step control section 110 outputs the calculated adjustment width to CQI selection adjustment section 111 as adjustment width information. A method for determining the adjustment step in the adjustment step control unit 110 will be described later.

  A multipath estimation unit 701 as a propagation environment estimation unit creates a delay profile from the despread received signal input from the despreading unit 104, estimates a delay spread from the created delay profile, and obtains the estimated delay spread information. This is output to the geometry estimation unit 702, the set time constant control unit 703, and the adjustment step control unit 110. Here, the longer the delay spread, the stronger the influence of the delayed wave, so there is a high possibility that the propagation environment will change due to multipath interference.

  Based on the total received signal input from the reception RF unit 103, the despread received signal input from the despreading unit 104, and the multipath estimation result input from the multipath estimation unit 701, the geometry estimation unit 702 serving as a propagation environment estimation unit Then, a geometry which is a power ratio representing the position of the wireless communication device 700 in the cell is measured, and the measured geometry information is output to the setting time constant control unit 703 and the adjustment step control unit 110. Here, the geometry can be obtained from Equation (1).

  As wireless communication apparatus 700 gets closer to the base station apparatus of its own cell (not shown), the power density of the received signal from the base station apparatus of its own cell increases and the power density of the received signal from the base station apparatus of the other cell decreases. As a result, the value of the geometry increases. On the other hand, as the wireless communication device 700 moves away from the base station device of the own cell and approaches the cell edge, the power density of the received signal from the base station device of the own cell decreases and the received signal from the base station device of another cell As the power density increases, the value of the geometry decreases. When the geometry is large, the multipath interference of the own cell is strong and the propagation environment is likely to change.

  The geometry can also be obtained from equation (2).

  However, in cellular mobile communication, interference power is dominant in comparison with receiver thermal noise in a normal environment, so the calculation result of Equation (1) and the calculation result of Equation (2) are almost the same value. become.

  The setting time constant control unit 703 uses the fD estimation result input from the fD estimation unit 109, the delay spread information input from the multipath estimation unit 701, and the geometry information input from the geometry estimation unit 702 to perform averaging for reception quality determination The time constant is determined, and the determined average time constant information is output to the reception quality determination unit 108. That is, the setting time constant control unit 703 shortens the averaging time constant when the possibility that the propagation environment changes is high, and lengthens the averaging time constant when the possibility that the propagation environment changes is low.

  The reception quality judgment unit 108 measures the number of retransmissions within the set measurement time by using the averaging time constant input from the set time constant control unit 703, and obtains the number of retransmission times information measured every time the measurement time elapses as CQI. The data is output to the selection adjustment unit 111.

  Next, the operation of the wireless communication apparatus 700 will be described. First, the operation of wireless communication apparatus 700 excluding the operation of setting the setting time constant will be described with reference to FIGS. 8 and 9 are flowcharts showing the operation of the wireless communication apparatus 700, and FIG. 10 shows a reference table that stores adjustment step basic value information that associates fD with the adjustment step basic value α. 11 shows a reference table for storing delay spread information that associates the delay spread of the multipath estimation unit 701 with the coefficient β, and FIG. 12 shows the geometry and coefficient of the geometry estimation unit 702. A reference table for storing geometry information related to γ is shown.

  First, fD estimation section 109 estimates fD from the received signal subjected to the despreading process (step ST801).

  Next, adjustment step control section 110 determines whether or not estimated fD is smaller than 60 Hz (step ST802).

  When fD is smaller than 60 Hz, adjustment step control section 110 refers to adjustment step basic value information in FIG. 10 to select 0.1 dB as adjustment step basic value α (step ST803).

  If fD is not smaller than 60 Hz, adjustment step control section 110 determines whether or not estimated fD is smaller than 120 Hz (step ST804).

  When fd is smaller than 120 hz, adjustment step control section 110 selects 0.2 dB as adjustment step basic value α by referring to the adjustment step basic value information in FIG. 10 (step ST805).

  If fD is not smaller than 120 Hz, adjustment step control section 110 selects 0.5 dB as adjustment step basic value α by referring to the adjustment step basic value information in FIG. 10 (step ST806).

  Next, adjustment step control section 110 determines whether or not the estimated delay spread is smaller than 500 ns (step ST807).

  When the estimated delay spread is smaller than 500 ns, adjustment step control section 110 selects 0.7 as coefficient β by referring to the delay spread information in FIG. 11 (step ST808).

  If the estimated delay spread is not smaller than 500 ns, adjustment step control section 110 selects 1.3 as coefficient β by referring to the delay spread information in FIG. 11 (step ST809).

  Next, adjustment step control section 110 determines whether or not the estimated geometry is smaller than 5 dB (step ST810).

  When the estimated geometry is smaller than 5 dB, adjustment step control section 110 selects 0.7 as coefficient γ by referring to the geometry information of FIG. 12 (step ST811).

  If the estimated geometry is not smaller than 5 dB, adjustment step control section 110 selects 1.3 as coefficient γ by referring to the geometry information in FIG. 12 (step ST812).

  Next, adjustment step control section 110 obtains adjustment step H by multiplying adjustment step basic value α, coefficient β, and coefficient γ (step ST813). Then, the obtained adjustment step H is output to the CQI selection adjustment unit 111 as correction width information.

  Next, reception quality determination section 108 determines whether or not the number of retransmissions is greater than or equal to the first threshold value based on the number of retransmissions information (step ST814).

  When the number of retransmissions is equal to or greater than the first threshold, the CQI selection adjustment unit 111 determines that the communication quality has deteriorated, and adds the adjustment step H to the preset reference correction width (step ST815). Then, CQI selection adjustment section 111 corrects the threshold value for CQI selection by a correction width obtained by adding adjustment step H to the reference correction width in the direction of higher reception SIR (step ST816).

  If the number of retransmissions is not greater than or equal to the first threshold, CQI selection adjustment section 111 determines whether or not the number of retransmissions is less than or equal to the second threshold (first threshold ≧ second threshold). Is determined (step ST817). When the number of retransmissions is equal to or smaller than the second threshold value, CQI selection adjustment section 111 subtracts adjustment step H from a preset reference correction width (step ST818). Then, CQI selection adjustment section 111 corrects the threshold for CQI selection in the direction of lower reception SIR by the correction width obtained by subtracting adjustment step H from the reference correction width (step ST819).

  On the other hand, when the number of retransmissions is not less than or equal to the second threshold value in step ST817, CQI selection adjustment section 111 does not correct the threshold value. That is, if the number of retransmissions is less than the first threshold value and greater than the second threshold value, the CQI selection adjustment unit 111 is not abrupt and gradual in the propagation environment. The value is not corrected.

  Next, SIR measurement section 107 measures the received SIR from the received signal (step ST820).

  Next, CQI selecting section 112 selects the CQI corresponding to the measured received SIR by comparing the measured received SIR with the threshold value of the corrected reference table (step ST821).

  Thereby, the adjustment step control unit 110 can determine that the relative movement speed with respect to the base station apparatus is large because fD is large, can determine that the influence of the delayed wave is large due to the spread of the delay spread, or has a large geometry. Therefore, when it can be determined that the own cell multipath interference is strong, it is possible to increase the threshold correction width when selecting the CQI and to follow a rapid change in the propagation path. On the other hand, the adjustment step control unit 110 can determine that the relative moving speed with respect to the base station apparatus is low because fD is small, the case where it can be determined that the influence of the delayed wave is small because the delay spread is not widened, or the geometry is If it can be determined that the communication is with a base station apparatus other than its own cell due to the small size, the threshold value correction range at the time of CQI selection is reduced to accurately follow the gentle fluctuation of the propagation path. be able to.

  Next, the operation of wireless communication apparatus 700 when setting the setting time constant will be described using FIG. 13 and FIG. FIG. 13 is a flowchart showing the operation of the wireless communication apparatus 700 when obtaining the set time constant, and FIG. 14 is a reference table storing set time constant information that associates fD with the set time constant basic value a. Is shown.

  First, fD estimation section 109 estimates fD from the received signal subjected to the despreading process (step ST1301).

  Next, set time constant control section 703 determines whether or not estimated fD is smaller than 60 Hz (step ST1302).

  When fD is smaller than 60 Hz, set time constant control section 703 refers to the set time constant information in FIG. 14 to select 1 / 10,000 as set time constant basic value a (step ST1303). .

  When fD is not larger than 60 Hz, setting time constant control section 703 determines whether or not estimated fD is smaller than 120 Hz (step ST1304).

  When fd is smaller than 120 Hz, set time constant control section 703 refers to the set time constant information in FIG. 14 and selects 1/20000 as set time constant basic value a (step ST1305). .

  If fD is not smaller than 120 Hz, setting time constant control section 703 refers to the setting time constant information in FIG. 14 to select 1 / 50,000 as setting time constant basic value a (step ST1306). ).

  Next, setting time constant control section 703 determines whether or not the estimated delay spread is smaller than 500 ns (step ST1307).

  When the estimated delay spread is smaller than 500 ns, setting time constant control section 703 refers to the delay spread information in FIG. 11 to select 0.7 as coefficient β (step ST1308).

  If the estimated delay spread is not smaller than 500 ns, setting time constant control section 703 refers to the delay spread information in FIG. 11 to select 1.3 as coefficient β (step ST1309).

  Next, the set time constant control unit 703 determines whether or not the estimated geometry is smaller than 5 dB (step ST1310).

  When the estimated geometry is smaller than 5 dB, the set time constant control unit 703 selects 0.7 as the coefficient γ by referring to the geometry information in FIG. 12 (step ST1311).

  When the estimated geometry is not smaller than 5 dB, the setting time constant control unit 703 selects 1.3 as the coefficient γ by referring to the geometry information of FIG. 12 (step ST1312).

  Next, the set time constant control unit 703 obtains an average time constant by dividing the set time constant basic value a, the coefficient β, and the coefficient γ (step ST1313). Then, set time constant control section 703 outputs the obtained average time constant to reception quality determination section 108 as average time constant information.

  Thereby, the setting time constant control unit 703 can determine that the relative moving speed with respect to the base station apparatus is large because fD is large, can determine that the influence of the delayed wave is large due to the spread of the delay spread, or has a large geometry. Accordingly, when it can be determined that the multipath interference of the own cell is strong, the averaging time constant can be reduced to shorten the averaging time when determining the reception quality. On the other hand, the setting time constant control unit 703 can determine that the relative movement speed with respect to the base station apparatus is low because fD is small, the case where it can be determined that the influence of the delayed wave is small because the delay spread is not widened, or the geometry When it can be determined that the communication is performed with the base station apparatus of another cell due to the small, it is possible to increase the averaging time constant and lengthen the averaging time when determining the reception quality.

  As described above, according to the third embodiment, in addition to the effect of the first embodiment, the correction width is adaptively changed according to the propagation environment using the delay spread information and the geometry information. Since the threshold value correction range can be increased when the influence of the cell is strong or when the multipath interference of the own cell is strong, the threshold value for CQI selection can be set with extremely high accuracy. Further, according to the third embodiment, since the averaging time constant is changed according to the delay spread information and the geometry information, when the influence of the delay wave is strong or when the multipath interference of the own cell is strong, the averaging time constant Since the constant can be reduced, the reception quality can be determined with extremely high accuracy.

  In the third embodiment, the adjustment step basic value α selected using the fD estimation result is multiplied by the coefficient selected using the delay spread estimation result and the geometry estimation result. Not limited to this, the adjustment step basic value selected using the delay spread may be multiplied by the coefficient selected using the fD estimation result and the geometry estimation result, or the geometry estimation result. The adjustment step basic value selected by using may be multiplied by the coefficient selected using the estimation result of fD and the estimation result of delay spread.

  In the third embodiment, the adjustment step basic value α is multiplied by the coefficients β and γ. However, the present invention is not limited to this, and the coefficient β and γ may be added to or subtracted from the adjustment step basic value α. Alternatively, the adjustment step basic value α and the coefficients β and γ may be divided, and an arbitrary calculation method can be applied. In the third embodiment, the set time constant basic value a and the coefficients β and γ are divided. However, the present invention is not limited to this, and the coefficients β and γ are added to and subtracted from the set time constant basic value a. Alternatively, the set time constant basic value a and the coefficients β and γ may be multiplied, and an arbitrary calculation method can be applied. In Embodiment 3, the geometry is used for estimating the propagation environment. However, the present invention is not limited to this, and the propagation environment is estimated using an arbitrary parameter whose value changes according to the position of the wireless communication device. can do.

  Furthermore, although the delay spread is used as the multipath estimation result in the third embodiment, the present invention is not limited to this, and the number of paths detected from the created delay profile can be applied.

(Embodiment 4)
FIG. 15 is a flowchart showing an operation of the radio communication apparatus according to Embodiment 4 of the present invention. The configuration of the wireless communication apparatus is the same as that shown in FIG.

  First, fD estimation section 109 estimates fD from the received signal subjected to the despreading process (step ST1501).

  Next, adjustment step control section 110 determines whether or not estimated fD is smaller than 60 Hz (step ST1502).

  When fD is smaller than 60 Hz, adjustment step control unit 110 refers to correction width information in FIG. 3 and selects 0.1 dB as adjustment step H (step ST1503).

  If fD is not smaller than 60 Hz, adjustment step control section 110 determines whether or not estimated fD is smaller than 120 Hz (step ST1504).

  When fd is smaller than 120 Hz, adjustment step control section 110 selects 0.2 dB as adjustment step H by referring to the correction width information in FIG. 3 (step ST1505).

  If fD is not smaller than 120 Hz, adjustment step control section 110 selects 0.5 dB as adjustment step H by referring to the correction width information in FIG. 3 (step ST1506).

  Next, reception quality determination section 108 determines whether or not the number of retransmissions is greater than or equal to the first threshold value based on the number of retransmissions information (step ST1507).

  When the number of retransmissions is equal to or greater than the threshold value, CQI selection adjustment section 111 corrects the threshold value for CQI selection in the direction of higher reception SIR by the correction width of adjustment step H (step ST1508).

  On the other hand, when the number of retransmissions is not equal to or greater than the threshold value, CQI selection adjustment section 111 corrects the threshold value for CQI selection in the direction of lower reception SIR by the correction width of adjustment step H (step ST1509).

  Next, SIR measurement section 107 measures the received SIR from the received signal (step ST1510).

  Next, CQI selecting section 112 selects the CQI corresponding to the measured received SIR by comparing the measured received SIR with the threshold value of the corrected reference table (step ST1511).

  As described above, according to the fourth embodiment, in addition to the effect of the first embodiment, the comparison result between the number of retransmissions and the threshold value is used to determine the direction for correcting the threshold value for CQI selection. Since the adjustment step H only performs an operation of adding to the reference correction value, the process of correcting the threshold value can be simplified.

(Embodiment 5)
FIG. 16 is a diagram showing a reference table for storing correction width information in the adjustment step control unit of the wireless communication apparatus according to Embodiment 5 of the present invention. The configuration of the wireless communication apparatus according to the fifth embodiment is the same as that shown in FIG. 1 and the operation is the same as that shown in FIG.

  FIG. 16 can be applied in place of the reference table storing the correction width information of FIG. As shown in FIG. 16, the adjustment step H related to fD is different depending on the threshold value between CQI # 1 and CQI # 2, and the threshold value between CQI # 2 and CQI # 3. It is possible.

  As described above, according to the fifth embodiment, the adjustment step H is made different for each threshold value. Therefore, when the reception quality is deteriorated by reducing the correction width of the threshold value of the low CQI. , The CQI selection can be made to follow slight variations in the reception SIR to prevent the deterioration of the error rate characteristics, and when the reception quality is good by increasing the correction range of the high CQI threshold value, Transmission efficiency, such as increasing the coding rate so that the selected CQI is not changed when the SIR is slightly changed, can be prioritized, and both error rate characteristics and transmission efficiency can be achieved.

  In Embodiments 1 to 5, the correction width selected in accordance with the number of retransmissions is fixed to a preset reference correction width (0.1 dB). However, the correction width may be changed according to the number of retransmissions. In the first to fifth embodiments, the correction width finally determined by the CQI selection adjusting unit 111 is added to or subtracted from a predetermined reference correction width. However, the present invention is not limited to this. Instead, the reference correction width may be multiplied or divided by the correction width finally determined by the CQI selection / adjustment unit 111, or any calculation method may be applied. In the first to fifth embodiments, the propagation environment is estimated based on fD, delay spread, and geometry. However, the present invention is not limited to this, and arbitrarily selected elements that can be used for estimating the propagation environment are used. It is possible to estimate the propagation environment by appropriately combining.

  The wireless communication apparatus and the reception quality reporting method according to the present invention have the effect of improving transmission efficiency and system capacity by reducing the number of packet retransmissions, and setting a threshold value when selecting reception quality information. Useful for adaptive change.

1 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 1 of the present invention. FIG. 3 is a flowchart showing the operation of the wireless communication apparatus according to the first embodiment of the present invention. The figure which shows the relationship between fD which concerns on Embodiment 1 of this invention, and an adjustment step. The figure which shows the relationship between reception SIR and time which concerns on Embodiment 1 of this invention. FIG. 2 is a block diagram showing a configuration of a wireless communication apparatus according to Embodiment 2 of the present invention. The figure which shows the relationship between reception SIR and time which concerns on Embodiment 2 of this invention. Block diagram showing the configuration of a wireless communication apparatus according to Embodiment 3 of the present invention FIG. 9 is a flowchart showing the operation of the wireless communication apparatus according to the third embodiment of the present invention. FIG. 9 is a flowchart showing the operation of the wireless communication apparatus according to the third embodiment of the present invention. The figure which shows the relationship between fD which concerns on Embodiment 3 of this invention, and an adjustment step basic value. The figure which shows the relationship between the delay spread which concerns on Embodiment 3 of this invention, and a coefficient. The figure which shows the relationship between the geometry which concerns on Embodiment 3 of this invention, and a coefficient. FIG. 9 is a flowchart showing the operation of the wireless communication apparatus according to the third embodiment of the present invention. The figure which shows the relationship between fD which concerns on Embodiment 3 of this invention, and a setting time-constant basic value. FIG. 7 is a flowchart showing the operation of the wireless communication apparatus according to the fourth embodiment of the present invention. The figure which shows the relationship between fD which concerns on Embodiment 5 of this invention, and an adjustment step. The figure which shows the relationship between the conventional reception SIR and CQI

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Wireless communication apparatus 107 SIR measurement part 108 Reception quality determination part 109 fD estimation part 110 Adjustment step control part 111 CQI selection adjustment part 112 CQI selection part

Claims (14)

A propagation environment estimation means for estimating a propagation environment from a received signal;
Threshold setting means for variably setting a threshold based on the propagation environment status estimated by the propagation environment estimation means and communication quality information that is information indicating communication quality with a communication partner;
Reception quality report value determining means for determining a reception quality report value by comparing a threshold value set by the threshold setting means with a measurement value indicating reception quality;
Transmission means for transmitting information on the reception quality report value determined by the reception quality report value determination means to the communication partner;
A wireless communication apparatus comprising:   The threshold value setting means corrects the threshold value so that the reception quality is worse as communication quality deteriorates than the communication quality information, and receives the threshold value as communication quality is better than the communication quality information. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus corrects in a direction in which the quality is good and increases the correction range of the threshold value as the fluctuation of the propagation environment estimated by the propagation environment estimation unit increases.   The propagation environment estimation unit measures a relative movement speed with respect to a communication partner from a received signal, and the reception quality report value determination unit determines the threshold value as the relative movement speed measured by the propagation environment estimation unit increases. The wireless communication apparatus according to claim 1, wherein the correction range is increased.   The propagation environment estimation means estimates a delay spread from a delay profile, and the reception quality report value determination means increases the threshold correction width as the delay spread estimated by the propagation environment estimation means is longer. The wireless communication apparatus according to any one of claims 1 to 3, wherein:   It comprises setting time constant control means for setting a measurement time for measuring the communication quality, and the threshold value setting means includes the communication quality information and the communication quality information for each measurement time set by the setting time constant control means. 5. The wireless communication apparatus according to claim 1, wherein the threshold value is variably set based on a propagation environment state estimated by the propagation environment estimation unit.   6. The wireless communication apparatus according to claim 5, wherein the set time constant control means sets the measurement time to be shorter as the fluctuation of the propagation environment state estimated by the propagation environment estimation means is more severe.   The propagation environment estimation means measures a relative movement speed with respect to a communication partner from a received signal, and the set time constant control means shortens the measurement time as the relative movement speed measured by the propagation environment estimation means increases. 7. The wireless communication apparatus according to claim 5 or 6, wherein:   The propagation environment estimation means estimates a delay spread from a delay profile, and the set time constant control means sets the measurement time to be shorter as the delay spread estimated by the propagation environment estimation means is longer. The wireless communication apparatus according to any one of claims 5 to 7.   The propagation environment estimation means measures the power density ratio of the power density of the received signal from the base station apparatus of its own cell to the power density of the received signal from the base station apparatus of another cell, and the received quality report value determining means 5. The wireless communication apparatus according to claim 1, wherein the correction range of the threshold value is increased as the power density ratio is increased.   The propagation environment estimation means measures the power density ratio of the power density of the received signal from the base station apparatus of its own cell to the power density of the received signal from the base station apparatus of another cell, and the set time constant control means The wireless communication apparatus according to claim 5, wherein the measurement time is set shorter as the power density ratio is larger.   A communication terminal apparatus comprising the wireless communication apparatus according to claim 1.   A base station apparatus comprising the wireless communication apparatus according to claim 1. Estimating propagation environment from received signal;
A step of variably setting a threshold based on the estimated propagation environment state and communication quality information which is information indicating communication quality with a communication partner;
Determining a reception quality report value by comparing the threshold value with a measurement value indicating reception quality;
Transmitting information of the determined reception quality report value to the communication partner;
A reception quality reporting method comprising:   As the communication quality deteriorates from the communication quality information, the threshold value is corrected in a direction in which the reception quality is worse. 14. The reception quality reporting method according to claim 13, wherein the correction range of the threshold value is increased as the estimated propagation environment state changes more severely.

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