JP2010074365A - Radio communication device - Google Patents

Abstract

A wireless communication apparatus effectively updates an adaptive modulation table (correspondence between communication quality, modulation method and error correction coding rate), and selects an optimal modulation method.
Response storage means 19 stores correspondence for each of a plurality of speeds, transmission means 20, 21, 11-14 wirelessly transmit signals to a communication partner device, and reception means 13-15 A signal including reception success / failure information and communication quality information is received from the device, and the correspondence content update unit 18 updates the correspondence content based on the reception success / failure information by the reception success / failure detection unit 15, and communication quality change detection unit 17 detects the degree of temporal change in the information related to communication quality by the communication quality detection means 16, and the update target selection means 17 sets the correspondence with the speed corresponding to the degree of temporal change as the update target.
[Selection] Figure 1

Description

  The present invention relates to a wireless communication apparatus, and more particularly to a wireless communication apparatus that effectively updates an adaptive modulation table and selects an optimal modulation scheme.

  In a wireless communication system using digital modulation / demodulation, transmission is required in an environment where the line quality peculiar to wireless communication fluctuates more than communication mainly using voice communication represented by a conventional second generation mobile phone. There is an increasing demand for realizing high-speed data communication while ensuring high reliability by a processing method that compensates for fluctuations in the line quality even if time delay is allowed. In order to maintain highly reliable and high-throughput communication in the third generation or fourth generation wireless communication systems under consideration for these requirements, multiple values are used according to the state of the propagation path (propagation path). Adaptive modulation schemes that switch between modulation schemes and error correction coding rates have been adopted or studied.

  A combination of a multi-level modulation scheme and an error correction (FEC: Forward Error Correction) scheme (hereinafter referred to as MCS (Modulation and Coding Scheme)), and its error rate is CINR (Carrier to Interference plus Noise. Ratio) vs. BER (BER). In the case of the error rate, if there is a means for detecting the CINR value of the radio propagation path as the communication quality, the error rate in the channel condition can be estimated.

  By selecting a modulation method, a coding method, and a coding rate that can obtain the maximum transmission speed while satisfying a block error rate of a required FEC unit or less in the detected CINR value, the maximum transmission efficiency can be obtained. Information communication is possible. As described above, adaptive modulation and coding (AMC), which detects a communication quality and dynamically switches a modulation scheme and a coding rate during communication, has been applied in various communication systems.

FIG. 6 shows a configuration example of an adaptive modulation transmission / reception unit according to a conventional example.
Specifically, a wireless transmission / reception device 101 corresponding to a base station device and a wireless transmission / reception device 102 corresponding to a mobile station device are shown.
In radio transmission / reception apparatus 101 corresponding to a base station apparatus, adaptive modulation section 111 receives transmission data to be transmitted, and outputs a primary modulation signal for each subcarrier according to AMC specified by MCS selection section 118. Here, MCS information is included in a part of the primary modulation signal and transmitted. An OFDM (Orthogonal Frequency Division Multiplexing) modulator 112 performs orthogonal transform from a frequency signal to a time axis signal by inverse FFT (Inverse Fast Fourier Transform) to obtain a baseband signal. The RF unit 113 converts it into a radio frequency signal and outputs it from the antenna 114 to the space.

  In the radio transmission / reception apparatus 102 corresponding to the mobile station apparatus, a radio frequency signal is received by the antenna 121. An RF (Radio Frequency) unit 122 converts the signal into a baseband signal. The OFDM demodulator 123 obtains a reception modulation signal for each subcarrier by FFT. The reception MCS detection unit 125 detects the MCS information included in the reception modulation signal and notifies the adaptive demodulation unit 124 of the MCS information. Adaptive demodulation section 124 performs demodulation based on the notified MCS information, outputs received data, detects a reception error, and outputs ACK / NACK information to modulating section 127.

  The communication quality detection unit 126 measures the quality of the received modulation signal and notifies the modulation unit 127 of DL (downlink) communication quality information from the base station apparatus to the mobile station apparatus. The modulation unit 127 primarily modulates the notified communication quality information, the above-described ACK / NACK information, and UL (uplink) transmission data from the mobile station apparatus to the base station apparatus, and generates a primary modulation signal for each subcarrier. Output. The OFDM modulation unit 128 performs orthogonal transform from a frequency signal to a time axis signal by inverse FFT to obtain a baseband signal. The RF unit 122 converts it into a radio frequency signal, and transmits and outputs it from the antenna 121 via UL.

  This UL transmission signal is converted to an uplink reception subcarrier signal via the antenna 114, the RF unit 113, and the OFDM demodulation unit 115, and the OFDM demodulation unit 115 demodulates data and ACK / NACK information by FFT. The communication quality detection unit 116 detects the DL communication quality information detected by the mobile station apparatus, and notifies the MCS selection unit 118 of it. The MCS selection unit 118 selects the MCS from the corresponding CQI (or CINR) value of the adaptive modulation table 117 using the communication quality information as an index (for example, one corresponding to CQI (Channel Quality Indicator)), and the adaptive modulation unit 111 is notified.

By executing the series of processes described above for each frame, an adaptive modulation operation based on the optimum MCS is performed following the fluctuation of the propagation path.
As a specific example, in the adaptive modulation table 117, when the CINR value of the DL propagation path received by the BS (base station apparatus) from the MS (mobile station apparatus) in the UL is 10 dB, the adaptive modulation table 117 From the column corresponding to the place where the CINR value is 10 dB, a combination in which the modulation scheme is 16QAM (Quadrature Amplitude Modulation) and the coding rate is 1/2 is selected, and this is then transmitted to the MS of the DL MCS. And
In an actual system, since one base station apparatus performs communication to a plurality of mobile station apparatuses, it is necessary to provide a plurality of MCS selection units 118 and communication quality detection units 116.

JP 2005-236709 A JP 2004-104196 A

However, the conventional example described above has the following problems.
That is, there is a time difference (control delay) between the frame in which the communication quality detection unit 126 detects the quality of the DL propagation path and the frame in which the MCS selection unit 118 selects the MCS. Therefore, there is a problem that an error of a reception block occurs when the propagation path deteriorates, and the data of the frame becomes a transmission error.
In addition, even if the propagation path is poor regardless of the cause of the time difference, the adaptive modulation table 117 of the MCS selection unit 118 itself does not correspond to the poor propagation path, Due to the difference in propagation conditions, there is a problem that reception characteristics may vary even if the signal input to the receiver of the terminal is the same CINR.

  As a countermeasure, a margin is given to the MCS value (combination of modulation / demodulation method and coding method) selected in the adaptive modulation table 117 (that is, the MCS value having a high error tolerance with respect to the detected CINR value is selected). Although it is possible to improve the reception error rate, if a large margin is taken, an MCS with a low modulation / demodulation value and a low coding rate will be selected and the transmission information rate will be reduced. Optimal transmission error rate can be obtained according to the reception characteristics of the terminal (because the overall throughput may be improved by increasing the MCS level even if a certain amount of transmission error is allowed), the margin amount is optimally controlled. It is necessary to. For this reason, the optimum adaptive modulation table 117 may change depending on characteristics of the propagation path (for example, multipath conditions, fading speed, etc.), individual differences among terminals, and the like, so that the optimum MCS is selected every time the MCS is updated. It is required to adjust the adaptive modulation table 117.

  The fading speed is one of the factors that have a particularly large influence on the fluctuation due to the characteristics of the propagation path described above, and the optimum MCS is selected in the adaptive modulation table 117 depending on whether the fading speed is fast or slow (or stationary) or its fluctuation. Failure to do so often results in performance degradation such as reduced throughput.

  The present invention has been made in view of such conventional circumstances. For example, it is possible to obtain an optimum throughput adaptively for communication with a moving terminal with respect to a reception propagation path condition, particularly fading and the like. Thus, an object of the present invention is to provide a wireless communication apparatus (for example, a transmitter / receiver of an adaptive modulation scheme) capable of selecting an optimum modulation scheme by realizing an updating method capable of obtaining an adaptive modulation table.

In order to achieve the above object, in the present invention, a signal is wirelessly transmitted to a device serving as a communication partner, information on the success or failure of reception of the signal transmitted wirelessly from the device serving as a communication partner, and communication of the signal A radio communication apparatus that receives a signal including information on quality is configured as follows.
That is, the correspondence storage means stores the correspondence between the communication quality, the modulation scheme, and the error correction coding rate for each of the plurality of speeds. The transmission means wirelessly transmits a signal to the communication partner apparatus using the modulation method determined based on the correspondence stored in the correspondence storage means and the error correction coding rate. A receiving unit receives a signal including information on the success or failure of reception and information on the communication quality transmitted from the device as the communication partner by radio. The reception success / failure detection means detects the information on the reception success / failure included in the signal received by the reception means. Correspondence content update means updates the correspondence contents stored in the correspondence storage means based on the reception success / failure information detected by the reception success / failure detection means. Communication quality detection means detects information relating to the communication quality included in the signal received by the reception means. The communication quality change detecting means detects the degree of temporal change in information relating to the communication quality detected by the communication quality detecting means. The update target selecting means is a speed corresponding to the degree of temporal change in information related to communication quality detected by the communication quality change detecting means in correspondence with a plurality of speeds stored in the correspondence storage means. Is the target of update by the corresponding content update means.

  Therefore, in the configuration for storing the correspondence between the communication quality, the modulation method, and the error correction coding rate for each of a plurality of speeds, the degree of temporal change in information related to the communication quality of the signal to the communication partner device For example, the reception channel condition, particularly fading, etc. is moved by updating the correspondence for the corresponding speed (correspondence between the communication quality, the modulation method, and the error correction coding rate). An adaptive modulation table (here, communication quality, modulation scheme and error correction coding described above) so as to obtain an optimum throughput adaptively for communication with a terminal (here, the above-mentioned communication partner apparatus). A wireless communication device (for example, a transmitter / receiver of an adaptive modulation method) capable of selecting an optimum modulation method by realizing an updating method capable of obtaining a response rate) It can be realized.

Here, various types of wireless communication devices may be used. For example, a base station device can be used.
Various devices may be used as communication counterparts, and for example, a mobile station device can be used.
Various information may be used as the signal reception success / failure information. For example, in consideration of error correction, ACK (indicating that reception was successful) and NACK (indicating that reception was unsuccessful). Information).
Various kinds of information regarding signal communication quality may be used. For example, CINR or CQI may be used.

The correspondence storage means can be configured using a memory, for example.
Various communication quality may be used in correspondence with communication quality, modulation scheme, and error correction coding rate (MCS), for example, one having a stepped width (range) is used. May be.
As a modulation method, for example, a digital multi-level modulation method can be used.
Moreover, various numbers may be used as the plurality in the case where a correspondence is provided for each of the plurality of speeds.
The correspondence can be defined using a table, for example.

Various methods may be used as a method for detecting the degree of temporal change in information related to communication quality. For example, a method for detecting a moving speed (difference), a method for performing filtering, or the like. Can be used.
In addition, as a correspondence relationship between the degree of temporal change in information related to communication quality and the speed corresponding thereto, for example, it is preset in the apparatus and stored in the memory. It is possible to use a configuration in which one or more thresholds are provided for the degree of change, and the corresponding speed is determined based on the magnitude relationship between the value of the change in time and the threshold.

In addition, in correspondence with a plurality of speeds (correspondence between the communication quality, the modulation method, and the error correction coding rate), there are various timings for determining which correspondence is used for signal transmission. Any timing may be used. For example, a timing when a new communication with a device serving as a communication partner is started or a timing every time a predetermined period elapses can be used.
Further, as an example of the communication quality in the correspondence between the communication quality, the modulation scheme, and the error correction coding rate, one based on information on the communication quality notified from the communication partner apparatus can be used. .

In addition, various timings are used as timings for selecting the correspondence to be updated (correspondence between the communication quality, the modulation method, and the error correction coding rate) from among the correspondences for a plurality of speeds. For example, it is possible to use a timing when a communication is newly started with a device as a communication partner, a timing every time a predetermined period elapses, or a constant timing.
In addition, as the length of time for which a certain correspondence (correspondence between the communication quality, the modulation scheme, and the error correction coding rate) is continuously updated, various lengths of time may be used. A predetermined length of time may be used, or there is no particular time limit, and a mode may be used in which updating is performed whenever a need for updating occurs.

  As described above, according to the present invention, for example, an adaptive modulation table is obtained so that an optimum throughput can be obtained adaptively for communication with a moving terminal with respect to a reception propagation path condition, particularly fading and the like. A wireless communication device (for example, a transmitter / receiver of an adaptive modulation scheme) that can select an optimum modulation scheme by realizing an update method that can be implemented can be achieved.

Embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration example of a radio transmission / reception device 1 corresponding to a base station device as a configuration example of an adaptive modulation transmission / reception unit according to an embodiment of the present invention.
Here, in this example, the configuration and operation of the radio transmission / reception apparatus corresponding to the mobile station apparatus are the same as, for example, the configuration and operation of the radio transmission / reception apparatus 102 corresponding to the mobile station apparatus shown in FIG. For the sake of convenience, description will be made using the same reference numerals as those shown in FIG.

  The wireless transmission / reception apparatus 1 corresponding to the base station apparatus of this example includes an adaptive modulation unit 11, an OFDM modulation unit 12, an RF unit 13, an antenna 14, an OFDM demodulation unit 15, a communication quality detection unit 16, and a high-speed / Low speed determination and table selection unit 17, table update unit 18, adaptive modulation table unit 19, MCS selection unit 20, and MAP generation unit 21.

First, an example of a transmission operation performed in the wireless transmission / reception apparatus 1 corresponding to the base station apparatus of this example will be described.
Data to be transmitted (transmission data) is input to the MAP generation unit 21.
The MAP generation unit 21 maps the input transmission data to subcarriers, and outputs the resulting data to the adaptive modulation unit 11.
The adaptive modulation unit 11 modulates the data input from the MAP generation unit 21, generates a primary modulation signal for each subcarrier allocated by the MAP generation unit 21, and outputs the primary modulation signal to the OFDM modulation unit 12.

  Here, in this example, the adaptive modulation unit 11 generates a primary modulation signal for each subcarrier according to the AMC specified by the MCS selection unit 20, and in this case, information on MCS is included in a part of the primary modulation signal. Include.

The OFDM modulation unit 12 performs orthogonal transform from a frequency signal to a time axis signal by inverse FFT on the primary modulation signal for each subcarrier input from the adaptive modulation unit 11, and converts the generated baseband signal into the RF unit 13. Output to.
The RF unit 13 converts the signal input from the OFDM modulation unit 12 into a radio frequency signal and outputs the signal to the antenna 14. This signal is output (wireless transmission) from the antenna 14 to the space in DL.

Next, an example of reception and transmission operations performed in the wireless transmission / reception apparatus 102 corresponding to the mobile station apparatus will be described.
A radio frequency signal wirelessly transmitted from the wireless transmission / reception device 1 corresponding to the base station device of this example is received by the antenna 121 and input to the RF unit 122.
The RF unit 122 converts the input reception signal into a baseband signal and outputs the baseband signal to the OFDM demodulation unit 123.
The OFDM demodulator 123 obtains a reception modulation signal (corresponding to the primary modulation signal described above) for each subcarrier from the reception signal input from the RF unit 122 by FFT, and the adaptive demodulation unit 124 and the reception MCS detection unit 125 and the communication quality detection unit 126.

Reception MCS detection section 125 detects MCS information included in the reception modulation signal input from OFDM demodulation section 123 and notifies adaptive demodulation section 124 of the MCS information.
Based on the MCS information notified from reception MCS detection section 125, adaptive demodulation section 124 demodulates the reception modulation signal for each subcarrier input from OFDM demodulation section 123, and outputs the reception data obtained thereby. In addition, a reception error is detected and ACK / NACK information is output to the modulation unit 127.

The communication quality detection unit 126 measures the quality of the reception modulation signal based on the reception modulation signal for each subcarrier input from the OFDM demodulation unit 123, and performs DL (downlink) from the base station device to the mobile station device. Communication quality information (for example, CQI information) is notified to modulation section 127.
Data to be transmitted (transmission data) is input to the modulation unit 117.
The modulation unit 127 receives the communication quality information notified from the communication quality detection unit 126, the ACK / NACK information input from the adaptive demodulation unit 124, and the UL (uplink) from the mobile station device to the base station device. The transmission data is subjected to primary modulation, and a primary modulation signal for each subcarrier is generated and output to OFDM modulation section 128.

The OFDM modulation unit 128 performs orthogonal transform from a frequency signal to a time axis signal by inverse FFT on the primary modulation signal for each subcarrier input from the modulation unit 127, generates a baseband signal, and outputs the baseband signal to the RF unit 122. To do.
The RF unit 122 converts the signal input from the OFDM modulation unit 128 into a radio frequency signal and outputs the signal to the antenna 121. This signal is output (wireless transmission) from the antenna 121 to the space in UL.

Next, an example of a reception operation performed in the wireless transmission / reception apparatus 1 corresponding to the base station apparatus of this example will be described.
A UL transmission signal wirelessly transmitted from the wireless transmission / reception device 102 corresponding to the mobile station device is received by the antenna 14 and output to the RF unit 13.
The RF unit 13 converts the input received signal into a baseband signal and outputs it to the OFDM demodulator 15.
The OFDM demodulator 15 performs data demodulation and ACK / NACK information demodulation on the signal input from the RF unit 13 by FFT, and outputs the received data obtained thereby to the outside of the apparatus (this example) Then, the received data and communication quality information are output to the communication quality detection unit 16, and the ACK / NACK information obtained thereby is output to the outside of the apparatus, and the high-speed / low-speed determination and table selection unit 17 and the table are updated. The data is output to the processing unit 18.

The communication quality detection unit 16 detects DL communication quality information detected by the mobile station apparatus based on the information input from the OFDM demodulation unit 15, and performs high-speed / low-speed determination and table selection unit 17, MCS selection unit 20. And the MAP generation unit 21.
The MCS selection unit 20 selects the MCS from the corresponding CQI (or CINR) value of the adaptive modulation table unit 19 using the communication quality information notified from the communication quality detection unit 16 as an index (for example, equivalent to CQI). Then, the adaptive modulation unit 11 is notified via the MAP generation unit 21.
Here, in this example, the MCS is selected from the selected one of the high-speed adaptive modulation table and the low-speed adaptive modulation table included in the adaptive modulation table unit 19.

  The MAP generation unit 21 assigns transmission data to downlink subframes. Specifically, the MAP generation unit 21 determines each mobile station device selected by the MCS selection unit 20 based on the DL communication quality information received from each mobile station device detected by the communication quality detection unit 16. Burst modulation processing is performed according to the MC level.

Further, feature points in this example will be described in detail.
The high-speed / low-speed determination and table selection unit 17 acquires high-speed / low-speed information on the fading speed (for example, depending on the magnitude of the fluctuation of the received signal) based on the information input from the communication quality detection unit 16. Information indicating whether the table corresponding to the case where the fading speed is high or the table corresponding to the case where the fading speed is low is output to the table update processing unit 18.
The table update processing unit 18 updates the selected table (high-speed adaptive modulation table or low-speed adaptive modulation table) based on the information input from the high-speed / low-speed determination and table selection unit 17. The adaptive modulation table unit 19 is controlled.

Here, the ACK / NACK information is input from the OFDM demodulator 15 to the high-speed / low-speed determination and table selection unit 17 and the table update processing unit 18, and for example, count processing of the number of ACKs and NACKs can be performed. .
In this example, the adaptive modulation table unit 19 stores a high-speed adaptive modulation table and a low-speed adaptive modulation table in a memory. Each adaptive modulation table stores a correspondence between an index of communication quality information (for example, CQI or CINR) and MCS (for example, an MC level including a modulation scheme and a coding rate).

In this example, as the communication quality information, a CINR value used for MCS selection during DL transmission or a CQI value obtained by hierarchically converting the CINR value is used.
As the ACK / NACK information, ACK and NACK information, which is the reception result of the burst transmission described above, is used.
Further, based on the information from the communication quality detection unit 16, the high / low speed information of the fading speed is acquired.

FIG. 2 shows an example of an adaptive modulation table for high speed.
FIG. 3 shows an example of an adaptive modulation table for low speed (normal in this example).
In each adaptive modulation table, an index, a C / N value, an MC level modulation scheme and coding rate, the number of ACKs, and the number of NACKs are stored in association with each other.
In this example, it is possible to take statistical values of the above three types of information. By using this, it is possible to individually acquire statistical values and update the adaptive modulation table for two types of adaptive modulation tables prepared for high speed and low speed.

With reference to FIG. 4, an example of the procedure of the update process of the adaptive modulation table is shown.
Here, the process shown in FIG. 4 is performed after the ACK / NACK is counted up.
First, when processing is started (step S1), an adaptive modulation table to be updated is selected by high / low speed determination of input information. Specifically, the CINR (or CQI) difference is detected by the high speed / low speed determination table selection unit 17 (step S2), and if the detection result is low speed, the update target table is subjected to low-speed adaptive modulation. A table (step S3), and if the detection result is high speed, the update target table is a high speed adaptive modulation table (step S4).

Next, whether or not the number of ACKs and NACKs combined (number of ACKs + number of NACKs) for the C / N targeted by the table to be updated by the table update processing unit 18 is equal to or greater than a preset number of N times. Is determined (step S5), and if it is less than N times, this process is terminated (step S11).
On the other hand, when the total number of ACKs / NACKs corresponding to the counted CI communication CINR index value (the number of times described above) is N or more, the subsequent processing (steps S6 to S11) is performed. .

Here, as the predetermined value N, various numerical values may be used. For example, a set value of 100 or more is used.
Also, for example, as shown in FIG. 2 and FIG. 3, the CINR index value assigns an appropriate MCS by adding an index for each CINR range.

When the total number of ACK / NACK (the above-mentioned number) is N times or more, the table update processing unit 18 determines whether or not the number of NACK is equal to or less than a predetermined M1 (step S6). When the number of times exceeds M1, the process proceeds to step S8.
Here, a value corresponding to a prescribed NACK rate is set as M1.
On the other hand, when the number of NACKs is less than or equal to a predetermined M1 (that is, when the NACK rate is less than a prescribed rate), in this example, the block error is considered to be less than the prescribed value, and the table is updated. The processing unit 18 shifts the MC level up by one column in parallel in the adaptive modulation table that is the update target table (step S7), and proceeds to the process of step S8. In other words, since the error rate is less than the assumed value, the transmission data rate is shifted in the direction of increasing at the same C / N even if the error rate increases.

In the process of step S8, the table update processing unit 18 determines whether or not the number of NACKs is equal to or greater than a predetermined M2 (step S8). If the number of NACKs is less than M2, the process proceeds to step S10. Transition to processing.
Here, a value larger than M1 is set as M2 (M2> M1).

On the other hand, when the number of NACKs is equal to or greater than the predetermined M2 (that is, when the NACK rate is equal to or higher than a specified rate), in this example, the block error is considered to be equal to or higher than the specified value, and the table is updated. The processing unit 18 shifts the MC level downward by one column in parallel in the adaptive modulation table serving as the update target table (step S9), and proceeds to the process of step S10. That is, since the error rate is too high above the assumed value, the MC level of the adaptive modulation table is shifted in parallel by one column so as to lower the error rate.
In the process of step S10, the table update processing unit 18 sets the number of ACKs and the number of NACKs to 0 (clears the count value to 0) for the target CINR index (C / N). (Step S10), this process is terminated (Step S11).

Here, the method of updating the MC level of the adaptive modulation table is not necessarily limited to the method of shifting in parallel as in this example, and various methods may be used. What is necessary is just to be able to update so that it may approach.
With the above table update process, it is possible to select a modulation method that allows a certain amount of errors and increases the amount of transmission data, and can improve the throughput as a whole.

  In the processing flow, if the content of the processing is substantially the same, for example, the processing for determining whether the processing is greater than or less than a predetermined value is greater than or less than the predetermined value. It may be replaced with a process for determining whether or not, and vice versa.

With reference to FIGS. 5A and 5B, two examples of methods of high speed / low speed determination and table selection processing are shown.
With reference to FIG. 5A, an example of the method of the high speed / low speed determination and table selection processing performed by the high speed / low speed determination and table selection unit 17 will be described.
The communication quality detection unit 16 reads several frames in units of frames or in an appropriate unit time (processing T1).
Here, communication quality information is not obtained from mobile station devices that have completed registration in all the same base station devices during the unit time during which reading to the base station device is performed, but intermittent communication quality Information may be obtained. For this reason, with respect to the signal input from the communication quality detection unit 16, the amount of data that can be processed by a frame unit in the reading process or several frames in an appropriate unit time, or a moving speed (difference) detection process and an averaging process described later (For example, depending on the moving speed, range, etc. to be detected) is input, and it is determined whether or not the signal is continuous by the level detection process (process T2). Interpolation is performed at (T3).

  In the above, when the signal is continuous and when the signal is discontinuous but interpolated, the difference between the acquired data unit time and the data that has passed an appropriate delay time is the moving speed (difference) Obtained by the detection process (process T4), averaged by the averaging process (process T5), and selected either a high-speed table or a low-speed table by the level determination process (process T6). Specifically, if the averaged result level is equal to or higher than a certain threshold (or exceeds a certain threshold), a high-speed table is selected, and the averaged result level is less than a certain threshold (or below a certain threshold). ), A low-speed table is selected.

With reference to FIG. 5B, another example of the method of the high speed / low speed determination and table selection processing performed by the high speed / low speed determination and table selection unit 17 will be described.
First, the read process (process T11), the level detection process (process T12), and the interpolation process (process T13) are the same as the processes T1, T2, and T3 shown in FIG.

  In the above, when the signal is continuous and when the signal is discontinuous but interpolated, a process of extracting a high frequency component by HPF (High Pass Filter) is performed (process T14), and an absolute value thereof A process of detecting an absolute value by the detection process is performed (process T15). The absolute value (positive) signal is smoothed by LPF (Low Pass Filter) (Process T16), and the high frequency (high speed) component is extracted by the level determination process. In this case, extraction is desired. By setting an appropriate HPF cutoff frequency and level determination threshold for high speed, it is possible to determine high speed / low speed (process T17). Specifically, when the level of the smoothing result is equal to or higher than a certain threshold (or exceeds a certain threshold), a high-speed table is selected, and the level of the smoothing result is less than the certain threshold (or below a certain threshold). ), A low-speed table is selected.

Here, as another configuration example, instead of HPF, a plurality of update tables are detected for each required speed range, whether as a bandpass filter (BPF) or a combination of BPF and HPF. It is possible. In this case, since the number of filters and the processing increase, it is necessary to select a processing method according to the application.
Further, in the processing method 1 shown in FIG. 5A, if there are two types of detection, high speed and low speed, movement speed (difference) detection, averaging (for example, a primary filter may be used), and level determination processing Therefore, it is possible to reduce the processing compared to the processing method 2 as shown in FIG.

Also, in this example, the base station apparatus receives the communication quality information from the mobile station apparatus in the UL based on the communication quality information (CINR or CQI) detected by the mobile station apparatus based on the preamble or the like in the DL, and the MCS in the DL. Therefore, for example, it is possible even if the duplexing method between the base station apparatus and the mobile station apparatus is time division multiplexing (TDD), or frequency division multiplexing (FDD: Frequency Division). Duplexing) is also possible. The multiple access method is not limited to OFDM, and any of TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access), and the like can be used.
Further, depending on the communication system to be applied, the base station apparatus can be realized by using CINR as communication quality information, and can also be realized by using CQI.

As described above, in this example, a radio transmission apparatus including the base station apparatus 1 and the mobile station apparatus 102 is provided. In a radio system using digital modulation / demodulation in which a radio signal to be transmitted has a frame configuration, This is a wireless transmission scheme that uses an adaptive modulation scheme that adaptively controls the modulation scheme according to the situation, and performs the following processing.
That is, the communication quality (in this example, CINR (signal to noise + interference signal) or CQI corresponding to CINR) measured by the mobile station device 102 in transmission from the base station device 1 to the mobile station device 102 is the base station device 1. And a plurality of update tables for each speed corresponding to the communication quality of the adaptive modulation and the MCS are provided for selecting a combination of modulation scheme and error correction coding rate (MCS). Thus, the success / failure (ACK / NACK) information of communication when transmitted from the base station apparatus 1 to the mobile station apparatus 102 is transmitted from the mobile station apparatus 102 to the base station apparatus 1, and the communication quality at the time of transmission and the success / failure information Based on the statistical value and the success / failure rate, the result of detecting the speed of the mobile station device 102 based on the amount of change in communication quality (by speed, such as high speed, low speed, etc.) To update separately selected and.

  As described above, in this example, when the adaptive modulation coding (AMC) table is corrected (adjusted) by ACK / NACK, a plurality of AMC tables are respectively used for high / low speed (or medium speed, etc.) of Doppler frequency. Provided to roughly detect the Doppler frequency (high speed / low speed, medium speed, etc.) and correct the AMC table corresponding to each case. Furthermore, the detection of the high / low speed (or medium speed, etc.) of the Doppler frequency is obtained from the change in CQI.

  Therefore, in this example, a plurality of adaptive modulation tables are prepared corresponding to the moving speed of the mobile station apparatus 102, and the transmission environment around the installed base station apparatus 1 is obtained by grasping the transmission result by ACK / NACK. By updating to the optimum adaptive modulation table according to the change in (moving speed), there is an advantage that the throughput in the cell or the whole sector of the base station apparatus can be improved.

  The base station device 1 (an example of a wireless communication device) of this example performs wireless communication with a mobile station device 102 (an example of a device that is a communication partner), and each of a plurality of speeds is transmitted by the adaptive modulation table unit 19. The correspondence storage means is configured by the function of storing the adaptive modulation table as shown in FIG. 2 and FIG. 3, and the MCS selection unit 20, the MAP generation unit 21, the adaptive modulation unit 11, the OFDM modulation unit 12, and the RF unit. 13 and the antenna 14 constitute a transmission means by the function of wirelessly transmitting a signal by the adaptive modulation method, and the antenna 14, the RF section 13 and the OFDM demodulator 15 constitute a reception means by the function of receiving a radio signal. The OFDM demodulator 15 constitutes a reception success / failure detection means by the function of detecting ACK / NACK. The correspondence content update means is configured by the function of updating the contents of the adaptive modulation table as shown in FIG. 5, and the communication quality detection means is configured by the function of detecting information related to communication quality by the communication quality detection unit 16, As shown in FIG. 5 (a) or FIG. 5 (b), the high / low speed determination and table selection unit 17 constitutes a communication quality change detecting means with a function of detecting the degree of temporal change in information related to communication quality. The update target selection means is configured by the function of selecting an adaptive modulation table to be updated from among a plurality of speed adaptive modulation tables by the high speed / low speed determination and table selection unit 17.

Here, the configuration of the system and apparatus according to the present invention is not necessarily limited to the configuration described above, and various configurations may be used. The present invention can also be provided as, for example, a method or method for executing the processing according to the present invention, a program for realizing such a method or method, or a recording medium for recording the program. It is also possible to provide various systems and devices.
The application field of the present invention is not necessarily limited to the above-described fields, and the present invention can be applied to various fields.
In addition, as various processes performed in the system and apparatus according to the present invention, for example, the processor executes a control program stored in a ROM (Read Only Memory) in hardware resources including a processor and a memory. A controlled configuration may be used, and for example, each functional unit for executing the processing may be configured as an independent hardware circuit.
The present invention can also be understood as a computer-readable recording medium such as a floppy (registered trademark) disk or a CD (Compact Disc) -ROM storing the control program, and the program (itself). The processing according to the present invention can be performed by inputting the program from the recording medium to the computer and causing the processor to execute the program.

It is a figure which shows the structural example of the adaptive modulation transmission / reception part which concerns on one Example of this invention. It is a figure which shows an example of the adaptive modulation table for high speeds. It is a figure which shows an example of the adaptive modulation table for low speeds. It is a figure of the flowchart which shows an example of the procedure of the update process of an adaptive modulation table. (A) And (b) is a figure which shows the example of the method of a high speed / low speed determination and a table selection process. It is a figure which shows the structural example of the adaptive modulation transmission / reception part which concerns on a prior art example.

Explanation of symbols

  1, 101... Base station apparatus (radio transmission / reception apparatus) 11, 111.. Adaptive modulation section 12, 112.. OFDM modulation section 13, 113... RF section 14, 114. ..OFDM demodulation unit 16, 116..Communication quality detection unit 17..High speed / low speed determination and table selection unit 18..Table update processing unit 19..Adaptive modulation table unit 20, 118..MCS Selection unit, 21 ·· MAP generation unit, 117 ·· Adaptive modulation table, 102 ·· Mobile station device (wireless transmission / reception device), 121 ·· Antenna, 122 ·· RF unit, 123 ·· OFDM demodulation unit, 124 ··· Adaptive demodulator 125 ・ ・ Reception MCS detector 126 ・ Communication quality detector 127 ・ Modulator 128 ・ OFDM modulator

Claims (1)

Wireless communication that transmits a signal wirelessly to a communication partner device and receives a signal including information on the success or failure of reception of the signal transmitted wirelessly from the communication partner device and information on the communication quality of the signal In the device
Corresponding storage means for storing correspondence between communication quality, modulation scheme, and error correction coding rate for each of a plurality of speeds;
Transmission means for wirelessly transmitting a signal to the communication partner device using a modulation scheme determined based on the correspondence stored in the correspondence storage means and an error correction coding rate;
Receiving means for receiving a signal including information on the success or failure of transmission and information on the communication quality transmitted from the device as the communication partner by radio;
Reception success / failure detection means for detecting information of the reception success / failure included in the signal received by the reception means;
Correspondence content update means for updating the correspondence contents stored in the correspondence storage means based on the information of the reception success / failure detected by the reception success / failure detection means;
Communication quality detection means for detecting information relating to the communication quality included in the signal received by the reception means;
Communication quality change detecting means for detecting the degree of temporal change in information relating to communication quality detected by the communication quality detecting means;
Among the correspondences with respect to a plurality of speeds stored in the correspondence storage means, the correspondence with respect to the speed according to the degree of temporal change of the information regarding the communication quality detected by the communication quality change detection means An update target selection means to be updated by the update means;
A wireless communication apparatus comprising:

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