JP2007281780A - Adaptive modulation control apparatus, communication apparatus, and adaptive modulation control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adaptive modulation control apparatus for selecting a proper modulation and channel coding scheme depending on the magnitude of an interference power and a noise power in addition to either a signal to interference plus noise power ratio or a carrier to interference plus noise power ratio. <P>SOLUTION: The adaptive modulation control apparatus for selecting one modulation and channel coding scheme among a plurality of modulation and channel coding schemes includes a selection section 320 that receives either the signal to interference plus noise power ratio or the carrier to interference plus noise power ratio as a received power ratio and selects the one modulation and channel coding scheme among the modulation and channel coding schemes on the basis of the received power ratio and an interference power to noise power ratio, which are received. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to communication performed by selecting a modulation scheme and a channel coding rate according to reception characteristics.

  Conventionally, in adaptive modulation communication in which communication is performed by selecting a modulation scheme and a channel coding rate (MCS: Modulation and channel coding scheme, hereinafter referred to as “MCS”) according to reception characteristics, the received signal power pair is determined from the received signal. Interference power and noise power ratio (SINR: Signal to Interference plus Noise power Ratio, hereinafter referred to as “SINR”) or carrier power to interference power and noise power ratio (CINR: Carrier to Interference plus Noise ratio, hereinafter “CNR” The MCS is selected based on the estimated value.

  In addition, interference power is not considered with respect to the above, or the received signal power to noise power ratio (SNR: Signal to Noise power Ratio, hereinafter referred to as “SNR”) as noise power without distinguishing between interference power and noise power. Alternatively, there is adaptive modulation that is performed based on a carrier power to noise power ratio (CNR).

  In the following description, since SINR and CINR are substantially equivalent in the present specification, they are representatively described in SINR.

  FIG. 12 is a block diagram showing an example of the configuration of a conventional mobile station apparatus. The mobile station apparatus shown in FIG. 12 is a communication system including a base station apparatus and a mobile station apparatus, and includes a downlink in communication from the base station apparatus to the mobile station apparatus, and from the mobile station apparatus to the base station apparatus. It is used in a system that employs frequency division duplex (hereinafter referred to as “FDD”) that uses different frequency bands for the uplink in the communication. FIG. 12 is an example assuming a case where data communication is performed by selecting a channel coding rate according to reception characteristics only in the downlink.

  12, the mobile station apparatus includes an RF (Radio Frequency) receiving unit 910, a demodulating unit 920, a channel decoding unit 930, a reception characteristic estimating unit 940, a coding rate selecting unit 950, a modulating unit 960, and an RF transmitting unit 970. . The RF receiving unit 910 receives a downlink signal from the base station apparatus from the antenna 90 and outputs a received signal. The demodulator 920 demodulates the received signal and outputs demodulated data. The channel decoding unit 930 performs channel decoding on the demodulated data and outputs received data. The reception characteristic estimation unit 940 is a component that estimates reception characteristics, and includes a signal power estimation unit 941 that estimates reception signal power Ps from the reception signal, an interference power estimation unit 942 that estimates interference power Pi from the reception signal, and a reception A noise power estimation unit 943 that estimates noise power Pn from the signal, and a SINR calculation unit 944 that obtains SINR from the estimated received signal power Ps, interference power Pi, and noise power Pn are provided.

  The coding rate selection unit 950 selects a channel coding rate from the SINR. Modulation section 960 modulates the channel coding rate information as transmission data and outputs a modulated signal in order to notify the base station apparatus of information on the selected channel coding rate. The RF transmission unit 970 transmits the modulated signal from the antenna 90 to the base station apparatus using an uplink signal.

  As a technique for estimating SINR from a received signal, a number of techniques have been proposed, such as Patent Document 1, Patent Document 2, and Non-Patent Document 1.

FIG. 13 shows an example of channel coding rate selection in the conventional example. As shown in FIG. 13, in the conventional system, the channel coding rate is selected in a one-to-one relationship with SINR (Non-Patent Document 2). Similarly, in a conventional system that selects MCS, which is a combination of a modulation scheme and a channel coding rate, MCS is selected in a one-to-one relationship with SINR. Thus, conventionally, SINR is used as a criterion for selecting a channel coding rate or MCS.
JP 2000-358079 A Japanese Patent Laid-Open No. 10-13364 Yoshinori et al., “Study on interference power estimation for multi-level transmission power control in 1-cell repetitive OFDM / TDMA system”, IEICE, RCS2002-240, January 16, 2003 Nakanishi et al. “Study on 1-cell repetitive TDMA system using OFDM with variable coding rate”, IEICE, 2004 General Conference, B-5-53, March 2004, p. 540

  However, the power of thermal noise, which is the main component of the noise component in the received signal, generally has a constant power spectral density at all frequencies, whereas interference power generally has a different power spectral density depending on the frequency. For this reason, even if the channel coding rate or MCS is the same in each SINR, there is a difference in error rate characteristics between when the interference power is large and when the interference power is small. As a result, the channel coding rate or MCS cannot be properly selected, which causes deterioration in communication characteristics.

  The present invention has been made in view of such circumstances, and in addition to either the received signal power to interference and noise power ratio or the carrier power to interference and noise power ratio, the interference power and noise power are An object of the present invention is to provide an adaptive modulation control device, a communication device, and an adaptive modulation control method that select an appropriate channel coding rate or a channel coding rate and a modulation scheme according to the size.

  (1) One aspect of an adaptive modulation control apparatus according to the present invention is an adaptive modulation control apparatus that selects one channel coding rate from a plurality of channel coding rates, and includes an interference power to noise power ratio, a received signal, and Either a power-to-interference and noise power ratio or a carrier power-to-interference and noise power ratio is input as a reception power ratio, and a plurality of channel codes are determined based on the input reception power ratio and the input interference power-to-noise power ratio. And a selection unit that selects one channel coding rate from the coding rate.

  Thus, according to one aspect of the adaptive modulation control apparatus of the present invention, in addition to either the received signal power to interference and noise power ratio, or the carrier power to interference and noise power ratio, the interference power and noise power. An appropriate channel coding rate can be selected according to the size of the signal, and communication characteristics due to the difference in the ratio between interference power and noise power can be reflected in the channel coding rate. Thereby, deterioration of communication characteristics can be suppressed.

  (2) In the aspect of the adaptive modulation control device according to the present invention, the selection unit may further perform one modulation from a plurality of modulation schemes based on the reception power ratio and the interference power to noise power ratio. The method is selected.

  Thus, in addition to either the received signal power-to-interference and noise power ratio or the carrier power-to-interference and noise power ratio, an appropriate channel coding rate and modulation scheme depending on the magnitude of the interference power and noise power Can be selected, and the communication characteristics due to the difference in the ratio between the interference power and the noise power can be reflected in the channel coding rate and the modulation scheme. Thereby, deterioration of communication characteristics can be suppressed.

  (3) Further, in one aspect of the adaptive modulation control apparatus according to the present invention, the selection unit is characterized in that the larger the interference power to noise power ratio, the smaller the channel coding rate value to be selected.

  As described above, the greater the interference power to noise power ratio, the greater the influence of the interference power compared to the noise power, and the selection unit has a difference in error rate characteristics depending on the frequency even when the reception power ratio is the same. Therefore, a channel coding rate with a small value is selected. Thereby, deterioration of communication characteristics can be suppressed.

  (4) In one aspect of the adaptive modulation control apparatus according to the present invention, the selection unit inputs a plurality of thresholds that specify a range of the reception power ratio and a range of the interference power to noise power ratio for each channel coding rate. The input reception power ratio and the interference power to noise power ratio are made to correspond to the plurality of threshold values to select one channel coding rate.

  In this manner, the selection unit can easily select a channel coding rate that maintains predetermined communication characteristics by setting a threshold value that reflects the reception power ratio and the interference power to noise power ratio.

  (5) In one aspect of the adaptive modulation control apparatus according to the present invention, the plurality of threshold values are set such that a value of a selectable channel coding rate becomes smaller when an interference power to noise power ratio becomes larger than a predetermined value. A range of the interference power to noise power ratio is specified.

  As described above, the selection unit causes a difference in error rate characteristics for each frequency when the interference power to noise power ratio is larger than a predetermined value. Select the coding rate. Thereby, deterioration of communication characteristics can be suppressed.

  (6) In one aspect of the adaptive modulation control apparatus according to the present invention, the selection unit selects a lower channel coding rate as the interference power to noise power ratio is larger, and the smaller the interference power to noise power ratio is, the smaller the interference power to noise power ratio is. A low modulation method is selected.

  In this way, the larger the interference power to noise power ratio, the greater the influence of the interference power compared to the noise power, the difference between the error rate characteristics depending on the frequency, the lower the channel coding rate, The smaller the interference power to noise power ratio, the greater the influence of noise power compared to the interference power, and the influence of noise power affects each frequency in the same way, so the modulation scheme is lowered. Thereby, deterioration of communication characteristics can be suppressed.

  (7) In one aspect of the adaptive modulation control apparatus according to the present invention, the selection unit specifies a plurality of first power ranges that specify a range of the reception power ratio and a range of the interference power to noise power ratio for each channel coding rate. A threshold value and a plurality of second threshold values that specify a range of the received power ratio and a range of the interference power to noise power ratio for each modulation method are input, and the received received power ratio and the interference power to noise power ratio Corresponding to the plurality of first thresholds to select one channel coding rate, and the input interference power to noise power ratio and received power ratio to correspond to the plurality of second thresholds to one A modulation method is selected.

  As described above, the selection unit can easily select a channel coding rate and a modulation method that maintain predetermined communication characteristics by setting a threshold value between the channel coding rate and the modulation method.

  (8) In one aspect of the adaptive modulation control apparatus according to the present invention, the first threshold value is set such that a value of a channel coding rate to be selected becomes small when an interference power to noise power ratio becomes larger than a predetermined value. A range of the interference power to noise power ratio is specified, and the second threshold value is set such that the level of the modulation scheme to be selected is lowered when the interference power to noise power ratio is smaller than a predetermined value. The range is specified.

  As described above, the larger the interference power to noise power ratio, the greater the influence of the interference power compared to the noise power, and the difference in the error rate characteristics depending on the frequency causes the selection unit to reduce the channel coding rate. The lower the interference power to noise power ratio, the greater the influence of noise power compared to the interference power, and the influence of noise power affects each frequency in the same way. Is set to be low. Thereby, an appropriate channel coding rate and modulation scheme can be selected.

  (9) In one aspect of the adaptive modulation control apparatus according to the present invention, the selection unit includes a range of received power ratios and interference power versus noise for each of a plurality of modulation parameters specifying a combination of a channel coding rate and a modulation scheme. A plurality of thresholds for specifying a range of power ratios are input, and one modulation parameter is selected by associating the input received power ratio and interference power to noise power ratio with the plurality of thresholds. To do.

  As described above, the selection unit sets the modulation parameter threshold value so that the higher the interference power to noise power ratio, the lower the channel coding rate, and the lower the interference power to noise power ratio, the lower the modulation scheme level. By setting, an appropriate modulation parameter can be easily selected.

  (10) In one aspect of the adaptive modulation control apparatus according to the present invention, either received signal power or carrier power, interference power, and noise power are input, and received signal power versus interference and noise power ratio or carrier power pair One of interference and noise power ratio is calculated as a reception power ratio, a reception quality information calculation unit that outputs the calculated reception power ratio to the selection unit, interference power and noise power are input, and interference power to noise power is input. An interference noise information calculation unit that calculates a ratio and outputs the calculated interference power to noise power ratio to the selection unit;

  As described above, by having the function of notifying the selection unit of the reception power ratio and the interference power to noise power ratio, it is possible to select an appropriate channel coding rate or modulation scheme.

  (11) In one aspect of the adaptive modulation control apparatus according to the present invention, a received signal is input, a signal power estimation unit that estimates either received signal power or carrier power based on the received received signal, and the received signal An interference power estimation unit that inputs and estimates the interference power based on the input received signal; and a noise power estimation unit that receives the received signal and estimates noise power based on the input received signal. Features.

  As described above, the adaptive modulation control device installed in the communication device on the receiving side has a function of estimating either the received signal power or the carrier power, the interference power, and the noise power based on the received signal. Information for selecting a suitable channel coding rate or modulation scheme can be acquired, and at least one of an appropriate channel coding rate or modulation scheme can be selected using the acquired information.

  (12) One aspect of a communication apparatus according to the present invention is a communication apparatus that transmits a channel-coded signal to a communication destination, the adaptive modulation control apparatus according to any one of (1) to (10) above, A channel encoding unit that encodes data using the channel coding rate selected by the adaptive modulation control apparatus, and a transmission unit that transmits the encoded signal to a communication destination.

  As described above, the communication device on the transmission side includes the adaptive modulation control device that selects an appropriate channel coding rate, thereby performing communication that suppresses deterioration of communication characteristics.

  (13) Another aspect of the communication apparatus according to the present invention is a communication apparatus that receives a channel-coded signal from a communication destination, and the adaptive modulation control apparatus according to any one of (1) to (11) above A transmission unit that transmits the channel coding rate selected by the adaptive modulation control apparatus to a communication destination, and a reception unit that receives a signal encoded at the selected channel coding rate from the communication destination. It is characterized by.

  As described above, the communication device on the receiving side includes an adaptive modulation control device that selects at least one of an appropriate channel coding rate and a modulation method, so that an appropriate channel coding rate or a modulation method is provided to the communication device of the communication destination. Can be notified, and communication that suppresses deterioration of communication characteristics can be performed.

  (14) One aspect of the adaptive modulation control method according to the present invention is an adaptive modulation control method for selecting one channel coding rate from a plurality of channel coding rates, including an interference power to noise power ratio, a received signal, and Either a power-to-interference and noise power ratio or a carrier power-to-interference and noise power ratio is input as a reception power ratio, and a plurality of channel codes are determined based on the input reception power ratio and the input interference power-to-noise power ratio. One channel coding rate is selected from the coding rate.

  Thus, according to one aspect of the adaptive modulation control method of the present invention, in addition to either the received signal power to interference and noise power ratio, or the carrier power to interference and noise power ratio, the interference power and noise power. An appropriate channel coding rate can be selected according to the size of the signal, and communication characteristics due to the difference in the ratio between interference power and noise power can be reflected in the channel coding rate. Thereby, deterioration of communication characteristics can be suppressed.

  According to the present invention, in addition to either the received signal power to interference and noise power ratio, or the carrier power to interference and noise power ratio, an appropriate channel coding rate according to the magnitude of the interference power and noise power, Or it becomes possible to select a channel coding rate and a modulation system, and to suppress degradation of communication characteristics.

  Next, embodiments of the present invention will be described with reference to the drawings. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals, and description thereof is omitted.

  Moreover, although each embodiment demonstrates the example in which a base station apparatus or a mobile station apparatus is provided with an adaptive modulation control apparatus, it is not restricted to these. The adaptive modulation control apparatus according to the present invention can be installed in a communication apparatus that performs communication using a channel coding rate or a modulation scheme.

(First embodiment)
FIG. 1 is a block diagram showing an example of a configuration of a communication system according to the first embodiment of the present invention.

  FIG. 1 is a communication system including a base station apparatus 100 and a mobile station apparatus 200, and is an example of a system that employs FDD. In addition, FIG. 1 illustrates an example in which data communication is performed by selecting a channel coding rate according to reception characteristics only in the downlink.

  In FIG. 1, the base station apparatus 100 includes an RF receiver 110, a demodulator 120, a channel encoder 130, a modulator 140, and an RF transmitter 150.

  The RF receiving unit 110 receives an uplink signal from the mobile station apparatus from the antenna 90 and outputs a received signal. The demodulator 120 demodulates the received signal received by the RF receiver 110 and outputs channel coding rate information included in the received signal. The channel coding rate information is information for specifying the channel coding rate selected by the mobile station apparatus 200. Channel coding section 130 performs channel coding on transmission data to be transmitted to mobile station apparatus 200 based on the channel coding rate information demodulated by demodulation section 120 and outputs coded data. Modulation section 140 modulates the encoded data encoded by channel encoding section 130 and outputs a modulated signal. The RF transmission unit 150 transmits the modulated signal modulated by the modulation unit 140 as a downlink signal from the antenna 90 to the mobile station apparatus.

  If channel coding is performed on channel coding rate information in mobile station apparatus 200, the data demodulated by demodulation section 120 is channel-decoded to obtain channel coding rate information. Also, when channel coding rate information is multiplexed with other data from mobile station apparatus 100, channel coding rate information and other data are separated after demodulation or channel decoding.

  In FIG. 1, a mobile station apparatus 200 includes an RF receiver 210, a demodulator 220, a channel decoder 230, a modulator 240, an RF transmitter 250, a reception characteristic estimator 310, and a selector (coding rate selector). 320. In addition, reception characteristic estimation section 310 and selection section 320 constitute applied modulation control apparatus 300. The applied modulation control apparatus 300 shown in FIG. 1 selects one channel coding rate from a plurality of channel coding rates based on the received signal.

  The RF reception unit 210 receives a downlink signal from the base station apparatus from the antenna 90 and outputs a reception signal. The demodulator 220 demodulates the received signal received by the RF receiver 210 and outputs demodulated data. Channel decoding section 230 performs channel decoding on the demodulated data demodulated by demodulation section 220 and outputs received data.

  The reception characteristic estimation unit 310 estimates the estimated values of the received signal power Ps, the interference power Pi, and the noise power Pn based on the received signal received by the RF receiving unit 210, and receives the received signal power pair from each estimated value. Interference and noise power ratio (hereinafter referred to as “SINR”) Ps / (Pi + Pn) and interference power to noise power ratio (hereinafter referred to as “INR”) Pi / Pn are obtained. Here, an example in which the reception characteristic estimation unit 310 estimates SINR will be described. However, instead of SINR, there may be a case where carrier power-to-interference and noise power ratio (hereinafter referred to as “CINR”) are estimated. . Reception characteristic estimation section 310 outputs either SINR or CINR to selection section 320 as a reception power ratio.

  Selection section 320 selects one channel coding rate from a plurality of channel coding rates based on SINR and INR estimated by reception characteristic estimation section 310. In addition, when the reception characteristic estimation unit 310 estimates SINR or CINR, the selection unit 320 inputs either SINR or CINR as a reception power ratio, and based on the received reception power ratio and interference power to noise power One channel coding rate is selected from a plurality of channel coding rates. A plurality of coding rates to be selected are stored in advance in a storage area in the selection unit 320 or a predetermined storage area, and the selection unit 320 stores (holds) a plurality of channel coding rates in the storage area. Select one from

  The modulation unit 240 modulates the channel coding rate information as transmission data to notify the base station apparatus 100 of channel coding rate information that identifies the channel coding rate selected by the selection unit 320, and converts the modulation signal into a modulated signal. Output. The RF transmission unit 250 transmits the modulation signal modulated by the modulation unit 240 from the antenna 90 to the base station apparatus 100 as an uplink signal.

  Modulation section 240 may perform channel coding at a channel coding rate predetermined by the system before modulation of channel coding rate information. Further, it may be transmitted by adding to other transmission data to the base station apparatus.

  FIG. 2 is a functional block diagram illustrating an example of the adaptive modulation control apparatus 300 according to the present embodiment. 2 includes a reception characteristic estimation unit 310 and a selection unit 320. The reception characteristic estimation unit 310 includes a signal power estimation unit 311, an interference power estimation unit 312, a noise power estimation unit 313, and a reception. A quality information calculation unit (SINR calculation unit) 314 and an interference noise information calculation unit (INR calculation unit) 315 are provided.

  The signal power estimation unit 311 estimates the reception signal power Ps from the reception signal received by the RF reception unit 210. The signal power estimation unit 311 may estimate carrier power instead of reception signal power, and outputs either reception signal power or carrier power as signal power information. In the following description, the signal power estimation unit 311 will describe a case where the received signal power is output. The interference power estimation unit 312 estimates the interference power Pi from the reception signal received by the RF reception unit 210. The noise power estimation unit 313 estimates the noise power Pn from the reception signal received by the RF reception unit 210.

  The reception quality information calculation unit 314 receives the received signal power Ps (or carrier power) estimated by the signal power estimation unit 311, the interference power Pi estimated by the interference power estimation unit 312, and the noise power estimated by the noise power estimation unit 313. SINR (or CINR) is calculated from Pn, and the calculated SINR (or CINR) is output to selection section 320 as a received power ratio. The reception quality information calculation unit 314 may be referred to as a SINR calculation unit when SINR is calculated, and a CINR calculation unit when CINR is calculated.

  The interference noise information calculation unit 315 calculates INR from the estimated interference power Pi and noise power Pn and outputs the calculated INR to the selection unit 320. Since the interference noise information calculation unit 315 calculates INR, it may be called an INR calculation unit.

  The selection unit 320 receives the reception power ratio (either SINR or CINR) from the reception quality information calculation unit 314, inputs INR from the interference noise information calculation unit 315, and determines the channel based on the reception power ratio and INR. Select the coding rate.

  FIG. 3 shows an example of channel coding rate selection in the present embodiment. FIG. 3 shows an example of selecting one channel coding rate from three types of channel coding rates (1/8, 1/4, and 1/2), with the horizontal axis representing SINR and the vertical axis representing INR. Is shown. In FIG. 3, S31 indicates an example of the SINR value, and T31 and T32 indicate examples of the INR value. A channel coding rate is selected from the relationship between SINR and INR obtained by reception characteristic estimation section 310. As shown in FIG. 3, even in the same SINR, selection is performed so that the channel coding rate is gradually reduced as the INR increases. Therefore, the larger the INR, the smaller (lower) the channel coding rate value (maximum value) to be selected. FIG. 3 shows an example in which the channel coding rate changes in three stages. However, if there are more channel coding rates, the channel coding rate selected in more stages will change. .

  For each channel coding rate, a plurality of threshold values for specifying the SINR (or CINR) range and the INR range are set. The selection unit 320 selects one channel coding rate by associating the SINR (or CINR) and INR estimated by the reception characteristic estimation unit 310 with a plurality of threshold values. In FIG. 3, two threshold values indicated by reference numerals B1 and B2 are shown as an example. When SINR is equal to or greater than threshold value B1 and INR is equal to or less than threshold value B1, selection unit 320 selects channel coding rate 1/2. When SINR is greater than or equal to threshold B2 and INR is less than or equal to threshold B2, and SINR is smaller than B1 and INR is greater than B1, selection section 320 selects channel coding rate 1/4. Furthermore, when SINR is smaller than threshold B2 and INR is larger than threshold B2, selection section 320 selects channel coding rate 1/8. As described above, the selection unit 320 selects one channel coding rate by associating SINR and INR with a range specified by a plurality of thresholds (which can be said to be an area specified by the thresholds in FIG. 3). . Here, when SINR is equal to or higher than threshold value B1 and INR is equal to or lower than threshold value B1, it can be said that selection unit 320 can also select channel coding rates 1/4 and 1/8. When the coding rate is selectable, the selection unit 320 selects a large channel coding rate.

  How to set the INR that is the threshold for channel coding rate selection for each SINR (for example, thresholds T31 and T32 for SINR = S31 in FIG. 3) differs depending on the system configuration and performance. For this reason, for example, a target bit error rate (BER: Bit Error Rate, hereinafter referred to as “BER”), a packet error rate, a frame error rate, or a block error rate are determined, and SINR and INR that can satisfy the target values. Is obtained by simulation or experiment to determine the threshold value.

A specific threshold determination procedure using simulation or experiment will be described with reference to an example in which the target BER is 10 ⁻⁴ . FIG. 4 is a diagram illustrating an example of a technique for determining a threshold value. First, for each selectable channel coding rate (in this example, three types of 1/8, 1/4, and 1/2), BER characteristics when SINR is changed are acquired. At this time, INR is fixed. Next, the BER characteristics when the SINR is fixed and the INR is changed are acquired for various SINRs, and a graph (three-dimensional graph) of SINR vs. INR vs. BER characteristics as shown in FIG. 4 is created. The solid line is the SINR vs. INR vs. BER characteristics at a coding rate of 1/8, the one-dot chain line is the SINR vs. INR vs. BER characteristics at a coding rate of 1/4, and the two-dot chain line is the SINR vs. the coding rate of 1/2. The INR vs. BER characteristics are shown.

This graph is cut out in the plane of 10 ⁻⁴ which is the target BER, and as shown in FIG. 4, the relationship between SINR and INR that can achieve the target BER at each channel coding rate is derived. Those boundaries are set as channel coding rate selection thresholds. An area where the target BER cannot be achieved at any channel coding rate is set as an area where transmission is not performed. In FIG. 4, the coding rate 1/8 leads to a right-upward hatched portion, the coding rate 1/4 leads to a right-falling shaded portion, and the coding rate 1/2 leads to a lattice pattern portion. it can. FIG. 4 is a diagram illustrating an example of a method for determining a threshold value, and does not indicate actual measurement values such as experimental data.

  The channel coding rate selection threshold set in this way is stored in a predetermined storage area in adaptive modulation control apparatus 300, and is read out by selection section 320 as necessary. The selection unit 320 may hold a threshold value.

  1 and 2 show an example in which the estimation of reception characteristics and the selection of the channel coding rate are performed in the mobile station apparatus 200, the following configuration is also possible.

  FIG. 5 is a diagram illustrating an example of another configuration of the communication system according to the present embodiment. In FIG. 5, the adaptive modulation control apparatus 301 is an example in which the selection section 320 is provided and the reception characteristic estimation section 310 is not provided. The adaptive modulation control apparatus 301 is installed in the base station 101, and the reception characteristic estimation section A configuration example in which 310 is installed in the mobile station apparatus 201 is shown. In this case, the mobile station apparatus 201 transmits the SINR (or CINR) and INR obtained by the reception characteristic estimation unit 310 to the base station apparatus 101 as reception characteristic information. In the base station apparatus 101, the demodulation unit 121 demodulates the reception signal received by the RF reception unit 110 and outputs reception characteristic information included in the reception signal, and the selection unit 320 receives the reception signal output by the demodulation unit 121. A channel coding rate is selected based on the characteristic information.

  FIG. 6 is a diagram illustrating an example of still another configuration of the communication system according to the present embodiment. In FIG. 6, the adaptive modulation control device 302 is an example in which a selection unit 320 and a reception characteristic information calculation unit 330 are provided. The reception characteristic information calculation unit 330 has a partial function of the reception characteristic estimation unit 310 illustrated in FIG. 2 and includes a reception quality information calculation unit 314 and an interference noise information calculation unit 315. Is provided.

  2, the signal power estimator 311, the interference power estimator 312 and the noise power estimator 313 are provided as the power estimator 260 in the mobile station device 202, and the reception quality is received in the base station device 102. A reception characteristic calculation unit 330 and a selection unit 320 including an information calculation unit 314 and an interference noise information calculation unit 315 are provided. In this case, mobile station apparatus 202 transmits each estimated value (power information) of received signal power Ps (or carrier power), interference power Pi, and noise power Pn obtained by power estimation section 260 to base station apparatus 102. In the base station apparatus 102, the demodulator 122 demodulates the received signal received by the RF receiver 110, outputs each estimated value included in the received signal, and the demodulator 122 receives the reception characteristic information calculator 330. Based on each output estimation value, SINR (or CINR) and INR are calculated and output to the selection unit 320. The selection unit 320 outputs the SINR (or CINR) and INR output from the reception characteristic information calculation unit 330. Based on the above, the channel coding rate is selected.

  5 and 6, components having the same reference numerals as those in FIG. 1 and FIG.

  In addition, although the adaptive modulation control apparatuses 301 and 302 shown in FIG. 5 and FIG. 6 showed the example installed in the base station apparatuses 101 and 102, the adaptive modulation control apparatuses 301 and 302 are functions of the adaptive modulation control apparatus 300. If the adaptive modulation control device 301 is installed in the case of having the configuration of the mobile station apparatus 201, the mobile station apparatus 200 has the same function as the mobile station apparatus 200. It is possible to install the adaptive modulation control apparatus 302 in 202, and in this case, the present invention is applied.

  Thus, according to the present embodiment, it is possible to select an appropriate channel coding rate according to the magnitude of interference power and noise power in addition to either SINR or CINR. The communication characteristics due to the difference in the ratio can be reflected in the channel coding rate. Thereby, deterioration of communication characteristics can be suppressed. Also, the channel coding rate selection function can be distributed to either the transmission side (base station apparatus side) or the reception side (mobile station apparatus side) in consideration of the processing load.

(Second Embodiment)
FIG. 7 is a block diagram showing an example of a configuration of a communication system according to the second embodiment of the present invention.

  FIG. 7 is a communication system including the base station apparatus 103 and the mobile station apparatus 203 as in the first embodiment, and is an example of a system that employs FDD. FIG. 7 shows an example in which data communication is performed by selecting a modulation scheme and a channel coding rate according to reception characteristics only in the downlink. The base station apparatus 103 in FIG. 7 is different from the base station apparatus 100 shown in FIG. 1 in a demodulation unit 123, a channel encoding unit 133, and a modulation unit 143.

  Demodulator 123 demodulates the received signal received by RF receiver 110 and outputs MCS information included in the received signal to channel encoder 133 and modulator 143. In this specification, MCS (modulation parameter) is information for specifying a combination of a channel coding rate and a modulation scheme. Channel coding section 133 performs channel coding on transmission data to be transmitted to mobile station apparatus 203 based on the channel coding rate included in the MCS information demodulated by demodulation section 123, and outputs the coded data. Modulation section 143 modulates the encoded data encoded by channel encoding section 133 based on the modulation scheme included in the MCS information demodulated by demodulation section 123, and outputs a modulated signal.

  When channel coding is performed on the channel coding rate information in mobile station apparatus 203, the data demodulated in demodulation section 123 is channel-decoded to obtain channel coding rate information. Further, when the MCS information is multiplexed with other data from the mobile station device 203, the MCS information and other data are separated after demodulation or channel decoding.

The mobile station apparatus 203 in FIG. 7 is different from the mobile station apparatus 200 shown in FIG. 1 in the selection unit (MCS selection unit) 340, and accordingly, the configuration of the adaptive modulation control apparatus 303 is also different.
Selection section 340 selects MCS, which is a combination of modulation scheme and channel coding rate, based on SINR and INR estimated by reception characteristic estimation section 310. In addition, the modulation unit 240 modulates the MCS information as transmission data and outputs a modulated signal in order to notify the base station apparatus 103 of MCS information specifying the selected MCS.

  Modulation section 240 may perform channel coding at a channel coding rate predetermined by the system before modulation of MCS information. Moreover, you may transmit by adding to other transmission data to the base station apparatus 103. FIG.

  FIG. 8 is a functional block diagram illustrating an example of the adaptive modulation control apparatus 303 according to the present embodiment. The adaptive modulation control device 303 shown in FIG. 8 is different from the adaptive modulation control device 300 shown in FIG. 2 in that the output of the selection unit (MCS selection unit) 340 and the adaptive modulation control device 303 is MCS. Other components are the same as those in FIG. Also, the reception quality information calculation unit 314 is the same as the first embodiment in that either one of SINR and CINR is output.

  FIG. 9 shows an example of MCS selection in the second embodiment of the present invention. In FIG. 9, the horizontal axis is INR, the left side of the vertical axis is the modulation scheme, the right side is the channel coding rate, and three types of modulation schemes BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), and 16QAM (Quadrature Amplification). In this example, MCS is selected from combinations of (Modulation) and three types of channel coding rates 1/8, 1/4, and 1/2. The MCS is selected from the relationship between SINR and INR obtained by the reception characteristic estimation unit 310.

FIG. 9 shows the relationship between INR and the selected MCS when the SINR is fixed to a certain representative value (for example, SINR = S61). The alternate long and short dash line indicates the target performance (for example, BER = 10). ^-4 ) indicates the boundary value of the channel coding rate (channel coding rate threshold value), and the solid line indicates the boundary value of the modulation method (modulation method threshold value) that achieves the target performance (for example, BER = 10 ^-4 ). Indicates. As illustrated in FIG. 9, the selection unit 340 performs selection such that MCS is a stepwise combination of a high modulation scheme and a low channel coding rate even with the same SINR, and the INR decreases. Accordingly, the selection is performed so that the MCS is a combination of a low modulation scheme and a high channel coding rate. In this example, the selection unit 340 selects the channel coding rate and the modulation scheme so that the transmission rates are the same, but the present invention is not limited to this, and the channel coding rate threshold and the modulation are selected. The transmission rate may change depending on the relationship with the system threshold. Further, in FIG. 9, when INR is T62, the threshold values of the modulation scheme and the channel coding rate are set to change. However, the threshold values may be changed in different INRs. The threshold of the modulation scheme may be changed at T62, and the threshold of the channel coding rate may be changed when INR is larger than T62.

  In FIG. 9, the threshold values for the modulation scheme and the channel coding rate are set separately, but it is also possible to set the MCS threshold value and select the MCS value based on the SINR and INR values. . The selection unit 340 sets a plurality of threshold values that specify the SINR range and the INR range for each of the plurality of modulation parameters. For example, in the relationship between the channel coding rate and SINR and INR shown in FIG. 3, the channel coding rate threshold value can be changed to the MCS threshold value, and the MCS can be selected based on the SINR and INR.

  In FIG. 9, a plurality of first threshold values (channel coding rate threshold values) specifying SINR (or CINR) ranges and INR ranges for each channel coding rate, and SINR (or CINR) for each modulation scheme And a plurality of second threshold values (modulation method threshold values) that specify the range of INR and the range of INR. The selection unit 320 selects one channel coding rate by associating the SINR (or CINR) and INR estimated by the reception characteristic estimation unit 310 with a plurality of first threshold values, and also selects the SINR (or CINR). And INR are associated with a plurality of second threshold values to select one modulation method. In FIG. 9, when SINR is S61 and INR is T61 or less, selection section 320 selects channel coding rate 1/2 and modulation scheme BPSK. When INR is equal to or less than T62 and greater than T61, selection section 320 selects channel coding rate ¼ and modulation scheme QPSK. When INR is larger than T62, selection section 320 selects channel coding rate 1/8 and modulation scheme 16QAM. FIG. 9 shows the case where the SINR is S61. For each SINR or a predetermined range of SINR, the same threshold value (boundary value) as in FIG. Select a method. The SINR in a predetermined range means a SINR in a range in which the same value is used as a threshold for INR (that is, a range of INR corresponding to a channel coding rate and a modulation scheme).

  For each SINR, how to set an INR that is a threshold for selecting an MCS (threshold for channel coding rate and threshold for modulation scheme) (thresholds T61 and T62 for SINR = S61 in FIG. 9) depends on the system It depends on. For this reason, for example, a target bit error rate, packet error rate, frame error rate or block error rate is determined, and a relationship between SINR and INR that can satisfy the target value is obtained by simulation or experiment, and the boundary value is determined. decide. The threshold determination method can be determined in the same manner as the method described with reference to FIG. 4 in the first embodiment. The threshold for MCS selection is held in a predetermined storage area as in the first embodiment.

  7 and 8 show an example in which reception characteristics estimation and MCS selection are performed in the mobile station apparatus 203, the following configurations are also possible.

  FIG. 10 is a diagram illustrating an example of another configuration of the communication system according to the present embodiment. In FIG. 10, the adaptive modulation control device 304 is an example in which the selection unit 340 is provided and the reception characteristic estimation unit 310 is not provided. The adaptive modulation control device 304 is installed in the base station 104, and the reception characteristic estimation unit. A configuration example in which 310 is installed in the mobile station device 204 is shown. In this case, mobile station apparatus 204 transmits SINR (or CINR) and INR obtained by reception characteristic estimation section 310 to base station apparatus 104. In the base station apparatus 104, the demodulation unit 124 demodulates the reception signal received by the RF reception unit 110 and outputs reception characteristic information included in the reception signal, and the selection unit 340 receives the reception signal output by the demodulation unit 124. An MCS is selected based on the characteristic information.

  FIG. 11 is a diagram illustrating an example of still another configuration of the communication system according to the present embodiment. In FIG. 11, the adaptive modulation control apparatus 305 is an example in which a selection unit 340 and a reception characteristic information calculation unit 330 are provided. The reception characteristic information calculation unit 330 has a partial function of the reception characteristic estimation unit 310 illustrated in FIG. 8 (or FIG. 2), and includes a reception quality information calculation unit 314 and an interference noise information calculation unit 315. 330 and a selection unit 340.

  2, the signal power estimator 311, the interference power estimator 312, and the noise power estimator 313 are provided as the power estimator 260 in the mobile station device 204, and the reception quality is received in the base station device 104. An information calculation unit 314, an interference noise information calculation unit 315, and an MCS selection unit 340 are provided. Other points that are the same as in FIG. 6 are not described here.

  10 and 11, components having the same reference numerals as those in FIG. 7 and FIG.

  In addition, although the adaptive modulation control apparatuses 304 and 305 shown in FIG. 10 and FIG. 11 have shown the example installed in the base station apparatuses 104 and 105, the adaptive modulation control apparatuses 304 and 305 are functions of the adaptive modulation control apparatus 300. If the adaptive modulation control device 304 is installed when the mobile station device 204 is configured, the mobile station device 203 has the same function as that of the mobile station device 203. Similarly, the mobile station device It is possible to install the adaptive modulation control device 305 in 205, and in this case, the present invention is applied.

  As described above, according to the present embodiment, it is possible to select an appropriate MCS according to the magnitude of interference power and noise power in addition to either SINR or CINR, and the ratio of the interference power to noise power can be selected. Communication characteristics due to the difference can be reflected in the channel coding rate and the modulation scheme. Thereby, deterioration of communication characteristics can be suppressed. Further, when there are a plurality of MCSs that realize the same transmission rate, a more appropriate MCS is selected by selecting according to the magnitude of interference power and noise power in addition to either SINR or CINR. It becomes possible. Further, the MCS selection function can be distributed to either the transmission side (base station apparatus side) or the reception side (mobile station apparatus side) in consideration of the processing load.

It is a block diagram which shows an example of a structure of the communication system which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows an example of the adaptive modulation control apparatus of 1st Embodiment. It is a figure which shows an example of the channel coding rate selection in 1st Embodiment. It is a figure which shows an example of the method of determining a threshold value. It is a block diagram which shows an example of another structure of the communication system of 1st Embodiment. It is a block diagram which shows an example of another structure of the communication system of 1st Embodiment. It is a block diagram which shows an example of a structure of the communication system which concerns on the 2nd Embodiment of this invention. It is a functional block diagram which shows an example of the adaptive modulation control apparatus of 2nd Embodiment. It is a figure which shows an example of MCS selection in 2nd Embodiment. It is a block diagram which shows an example of another structure of the communication system of 2nd Embodiment. It is a block diagram which shows an example of another structure of the communication system of 2nd Embodiment. The block diagram which shows an example of a structure of the conventional mobile station apparatus. It is a figure which shows an example of the channel coding rate selection in a prior art example.

Explanation of symbols

90 Antenna 100 to 105 Base station apparatus 110 RF receiver 120, 123 to 125 Demodulator 130, 133 Channel encoder 140, 143 Modulator 150 RF transmitter 200 to 205 Mobile station apparatus 210 RF receiver 220 Demodulator 230 Channel Decoding unit 240 Modulation unit 250 RF transmission unit 260 Power estimation unit 300 to 305 Applied modulation control device 310 Reception characteristic estimation unit 311 Signal power estimation unit 312 Interference power estimation unit 313 Noise power estimation unit 314 Reception quality information calculation unit 315 Interference noise Information calculation unit 320 selection unit (coding rate selection unit)
330 Reception Characteristic Information Calculation Unit 340 Selection Unit (MCS Selection Unit)

Claims (14)

An adaptive modulation control apparatus that selects one channel coding rate from a plurality of channel coding rates,
Input either interference power-to-noise power ratio and received signal power-to-interference and noise power ratio or carrier power power-to-interference and noise power ratio as received power ratio, and input received power ratio and input interference power to noise power An adaptive modulation control apparatus comprising: a selection unit that selects one channel coding rate from a plurality of channel coding rates based on the ratio.   The adaptive modulation control apparatus according to claim 1, wherein the selection unit further selects one modulation scheme from a plurality of modulation schemes based on the reception power ratio and the interference power to noise power ratio. .   3. The adaptive modulation control apparatus according to claim 1, wherein the selection unit reduces the value of the channel coding rate to be selected as the interference power to noise power ratio increases.   The selection unit inputs a plurality of thresholds that specify a range of the reception power ratio and a range of the interference power to noise power ratio for each channel coding rate, and the received reception power ratio and the interference power to noise power ratio The adaptive modulation control apparatus according to claim 1, wherein one channel coding rate is selected in correspondence with the plurality of threshold values.   The plurality of threshold values are characterized in that a range of interference power to noise power ratio is specified so that a selectable channel coding rate value decreases when the interference power to noise power ratio becomes larger than a predetermined value. The adaptive modulation control apparatus according to claim 4.   The adaptation according to claim 2, wherein the selection unit selects a lower channel coding rate as the interference power to noise power ratio is larger, and selects a lower modulation scheme as the interference power to noise power ratio is smaller. Modulation control device.   The selection unit includes a plurality of first threshold values that specify a range of a reception power ratio and a range of an interference power to noise power ratio for each channel coding rate, and a range of the reception power ratio and an interference power pair for each modulation scheme. A plurality of second threshold values that specify a range of the noise power ratio are input, and the received reception power ratio and the interference power to noise power ratio are associated with the plurality of first threshold values to form a single channel code. 7. The adaptation according to claim 6, wherein a modulation rate is selected, and one modulation scheme is selected by making the input received power ratio and interference power to noise power ratio correspond to the plurality of second threshold values. Modulation control device.   The first threshold value is a range of the interference power to noise power ratio specified so that a channel coding rate value to be selected decreases when the interference power to noise power ratio is greater than a predetermined value. 8. The range of the interference power to noise power ratio is specified such that the level of the modulation scheme to be selected is lowered when the interference power to noise power ratio is smaller than a predetermined value. Adaptive modulation controller.   The selection unit inputs a plurality of thresholds that specify a range of a reception power ratio and a range of an interference power to noise power ratio for each of a plurality of modulation parameters that specify a combination of a channel coding rate and a modulation scheme, and the input The adaptive modulation control apparatus according to claim 6, wherein one modulation parameter is selected in accordance with the received power ratio and the interference power to noise power ratio corresponding to the plurality of threshold values. Input either received signal power or carrier power, interference power, and noise power, and calculate either received signal power to interference and noise power ratio or carrier power to interference and noise power ratio as received power ratio, A reception quality information calculation unit that outputs the calculated reception power ratio to the selection unit;
An interference noise information calculation unit that inputs interference power and noise power, calculates an interference power to noise power ratio, and outputs the calculated interference power to noise power ratio to the selection unit; The adaptive modulation control apparatus according to any one of claims 1 to 9. A signal power estimator that inputs a received signal and estimates either received signal power or carrier power based on the received received signal;
An interference power estimation unit that inputs a reception signal and estimates interference power based on the input reception signal;
The adaptive modulation control apparatus according to claim 10, further comprising: a noise power estimation unit that inputs a reception signal and estimates noise power based on the input reception signal. A communication device that transmits a channel-coded signal to a communication destination,
An adaptive modulation control apparatus according to any one of claims 1 to 10,
A channel encoder that encodes data using the channel coding rate selected by the adaptive modulation controller;
And a transmission unit that transmits the encoded signal to a communication destination. A communication device that receives a channel encoded signal from a communication destination,
An adaptive modulation control apparatus according to any one of claims 1 to 11,
A transmission unit for transmitting the channel coding rate selected by the adaptive modulation control device to a communication destination;
And a receiving unit that receives a signal encoded at the selected channel coding rate from a communication destination. An adaptive modulation control method for selecting one channel coding rate from a plurality of channel coding rates,
Input either interference power to noise power ratio and received signal power to interference and noise power ratio or carrier power to interference and noise power ratio as reception power ratio,
An adaptive modulation control method, wherein one channel coding rate is selected from a plurality of channel coding rates based on an inputted reception power ratio and an inputted interference power to noise power ratio.

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