JP6462450B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method that perform wireless communication using an adaptive modulation scheme.

  In recent years, in wireless communication between a base station and a terminal, an adaptive modulation scheme that improves a communication speed by adaptively changing a modulation scheme according to a change in a communication environment while maintaining communication quality has been adopted. Examples of the modulation method used for the adaptive modulation method include PSK modulation (Phase Shift Keying) that does not perform amplitude modulation and QAM modulation (Quadrature Amplitude Modulation) that performs amplitude modulation. More specifically, examples of PSK modulation include BPSK (Binary PSK) and QPSK (Quadrature PSK). Examples of QAM modulation include 16QAM and 64QAM.

  In the adaptive modulation method, a communication environment is estimated based on a signal to interference and noise ratio (SINR) of a received signal and a bit error rate, that is, radio wave intensity and signal quality. Then, a modulation scheme having a higher communication rate is selected under a better communication environment, and a modulation scheme having a lower communication rate is selected under a poor communication environment. As a result, stable wireless communication can be performed between the base station and the terminal.

  Also, for example, in Patent Document 1, based on channel quality information from a receiving unit, a modulation scheme that satisfies a certain communication quality with the channel quality and has the highest transmission rate is determined as the first modulation scheme, and traffic of transmission data is determined. Modulation scheme control that determines the modulation scheme that provides the lowest transmission rate at which the amount can be transmitted as the second modulation scheme, and selects the lower one of the first modulation scheme and the second modulation scheme as the transmission modulation scheme. A method is disclosed. According to Patent Literature 1, it is possible to reduce power consumption while maintaining communication quality by determining a modulation method in consideration of a traffic amount of transmission data in addition to a propagation path condition.

JP 2006-165939 A

  By the way, in the conventional wireless communication apparatus and wireless communication method, when transmitting radio waves, the transmission output value actually output by the wireless communication unit is detected and compared with a predetermined specified value and output. The indicated value (level value given to the amplifier of the wireless communication unit) is corrected. This is because the output of the wireless communication unit fluctuates due to individual differences between devices, the environment, and the like, and it is possible to output a radio wave having a desired strength by the above control.

  However, in QAM modulation in which amplitude modulation is performed (information is included in the amplitude component), the transmission output value output from the transmission output detector varies, so the difference from the specified value of the transmission output tends to increase. . Then, since a difference from the specified value of the transmission output is frequently detected, if the control method is a conventional method, the control of the transmission output becomes unstable if the difference is reflected in the transmission output value.

  In order to avoid the situation as described above, it is conceivable to increase the time constant so as not to be affected by the amplitude modulation. However, this method makes it difficult to follow the fluctuations in the transmission output and makes it difficult to perform accurate control. Alternatively, it is conceivable that the output value waveform is obtained by sampling at a higher speed and the waveform envelope is calculated. However, in this method, it is necessary to use a high-precision detector for high-speed processing, and a high-speed processor for calculation is required, so that there is a problem that the cost of parts increases.

  In view of such problems, the present invention has an object to provide a wireless communication apparatus and a wireless communication method capable of stably controlling a transmission output when performing wireless communication using an adaptive modulation method. To do.

  In order to solve the above-described problem, a typical configuration of a wireless communication apparatus according to the present invention is a wireless communication apparatus that performs wireless communication using an adaptive modulation method, and wirelessly uses the first modulation method or the second modulation method. A radio communication unit that transmits a signal; a transmission output detection unit that detects a transmission output value when transmitting the radio signal; and a control unit that controls a transmission output of the radio communication unit. When the adaptive modulation scheme is the first modulation scheme, the transmission output of the wireless communication unit is controlled using the detected transmission output value and a transmission instruction value based on a predetermined transmission output specified value. When the adaptive modulation method is the second modulation method, the transmission instruction value is corrected using a correction value obtained based on a current internal temperature or a transmission frequency when transmitting the radio signal. Wireless communication section And controlling the output.

  In order to solve the above problems, a typical configuration of a radio communication method according to the present invention uses a first modulation scheme that does not perform amplitude modulation or an adaptive modulation scheme that includes a second modulation scheme that performs amplitude modulation. In a wireless communication method of a wireless communication apparatus having a wireless communication unit that transmits a wireless signal, when the adaptive modulation method is a first modulation method, a transmission output value detected when transmitting the wireless signal and A step of controlling a transmission output of the wireless communication unit using a transmission instruction value based on a predetermined transmission output prescribed value; and, when the adaptive modulation method is a second modulation method, a current internal temperature or Controlling the transmission output of the wireless communication unit with a transmission instruction value corrected using a correction value obtained based on a transmission frequency at the time of transmitting the wireless signal.

  According to the present invention, it is possible to provide a wireless communication apparatus and a wireless communication method capable of stably controlling transmission output when performing wireless communication using an adaptive modulation scheme.

It is a functional block diagram which illustrates the composition of the base station which is the radio communications apparatus concerning this embodiment. It is a flowchart explaining the operation | movement when the base station which is a radio | wireless communication apparatus of this embodiment performs radio | wireless communication. It is a figure explaining a control information table.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific numerical values and the like shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a functional block diagram illustrating the configuration of a base station 100 that is a wireless communication apparatus according to this embodiment. In the following description, the operation of the base station 100 shown in FIG. 1 will be described in detail, and the wireless communication method of this embodiment will also be described. In the present embodiment, the base station 100 is exemplified as the wireless communication device, but the present invention is not limited to this, and the present invention is also applied to the case where wireless communication is performed using an applicable modulation scheme in another wireless communication device. It is possible.

  The base station 100 shown in FIG. 1 uses a first modulation scheme (for example, PSK) that does not perform amplitude modulation or an adaptive modulation scheme that includes a second modulation scheme (for example, QAM) that performs amplitude modulation, Wireless communication. The base station 100 is managed and controlled by a control unit 110 including a semiconductor integrated circuit (not shown) including a central processing unit (CPU). In the present embodiment, as will be described later, the control unit 110 also functions as a transmission output control unit 112 that controls the transmission output of the wireless communication unit 120. The wireless communication unit 120 performs wireless communication (radio signal transmission / reception) with the wireless terminal 102 through the communication antenna 120a using the first modulation scheme or the second modulation scheme. The wireless communication unit 120 transmits radio waves with strength (power) corresponding to the output instruction value (level value given to the amplifier) given from the control unit 110.

  The transmission output detection unit 122 detects a transmission output value when the wireless communication unit 120 transmits a wireless signal. The temperature detection unit 124 detects the internal temperature of the wireless communication device (base station 100). The frequency detection unit 126 detects a transmission frequency when the wireless communication unit 120 transmits a wireless signal. The storage unit 130 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the control unit 110.

  In the present embodiment, the storage unit 130 stores a transmission output specified value 132 and a control information table 134. The transmission output specified value 132 is a specified value of the transmission output value when the wireless communication unit 120 transmits a wireless signal, and a value corresponding to the device (base station 100) is determined in advance based on laws and specifications. . The control information table 134 associates the internal temperature of the base station 100 detected by the temperature detection unit 124, the transmission frequency of the wireless communication unit 120 detected by the frequency detection unit 126, and a correction value for correcting the output instruction value. It is a table of information. The control information table 134 will be described in detail later.

  FIG. 2 is a flowchart illustrating an operation when the base station 100 which is the wireless communication apparatus of the present embodiment performs wireless communication. When performing wireless communication with the wireless terminal 102 (see FIG. 1), that is, when transmitting a wireless signal, the control unit 110 of the base station 100 first detects the transmission output value at that time by the transmission output detection unit 122 ( Step S202).

  Next, the control unit 110 detects the internal temperature of the base station 100 using the temperature detection unit 124 (step S204), and detects the transmission frequency when transmitting the radio signal using the transmission frequency detection unit 126 (step S206). In the present embodiment, the case where detection is performed in the order of the transmission output value, the internal temperature, and the transmission frequency is illustrated, but the present invention is not limited to this, and the detection order can be appropriately changed.

  Subsequently, the control unit 110 determines whether the modulation method used for wireless communication is the first modulation method or the second modulation method (step S208). As described above, in this embodiment, PSK is exemplified as the first modulation scheme that does not perform amplitude modulation, and QAM is exemplified as the second modulation scheme that performs amplitude modulation.

  If the modulation method for performing wireless communication is the first modulation method (PSK) (YES in step S210), that is, if the wireless communication unit 120 performs wireless communication using the first modulation method, the control unit 110 Functions as the transmission output control unit 112 and calculates the difference between the transmission output value detected by the transmission output detection unit 122 and the transmission output specified value 132 that is the specified value of the transmission output value. And the transmission output control part 112 controls the transmission output of the radio | wireless communication part 120 by adjusting the difference (step S212). That is, the output instruction value is adjusted so that the transmission output value becomes the transmission output specified value.

  The control unit 110 generates and stores control information used in the second modulation scheme (QAM) (step S214). Details of this control information will be described later.

  If the modulation method used when performing wireless communication is the second modulation method (QAM) (NO in step S210), the most recent output instruction value when wireless communication is performed using the first modulation method is used as a basis. , Correction values corresponding to temperature correction and / or frequency correction are used. In the present embodiment, as will be described later, a correction value corresponding to both is described as an example. When the wireless communication unit 120 performs wireless communication using the second modulation method, the control unit 110 functions as the transmission output control unit 112.

  The transmission output control unit 112 calculates a difference (internal temperature difference) between the current internal temperature and the latest internal temperature when wireless communication is performed using the first modulation method (step S222).

  The transmission output control unit 112 calculates a difference (transmission frequency difference) between the current transmission frequency and the latest transmission frequency when wireless communication is performed using the first modulation scheme (step S224).

  After calculating the difference in internal temperature and the difference in transmission frequency, the transmission output control unit 112 refers to the control information in the control information table 134, and outputs the latest output when wireless communication is performed using the first modulation method. The instruction value is corrected, and the transmission output of the wireless communication unit 120 is controlled with the corrected output instruction value (step S226).

  3 is a diagram illustrating the control information table 134, FIG. 3A is a diagram illustrating the control information table 134, and FIG. 3B is a diagram illustrating transmission output control with reference to the control information table 134. It is a figure illustrated.

  In the control information table 134 shown in FIG. 3A, T1 to T5 are included as differences in internal temperature, f1 to f5 are included as differences in transmission frequency, and correction values associated with these parameters are exemplified. For example, the correction value is 105 when the difference in internal temperature is T2 and the difference in transmission frequency is f3. In step S226, the transmission output control unit 112 refers to the control information in the control information table 134 and corrects (adds) the correction value to the most recent output instruction value when wireless communication is performed using the first modulation method. The transmission output of the wireless communication unit 120 is controlled with the corrected output instruction value.

  FIG. 3B illustrates specific transmission output control, and illustrates a case where the transmission output is controlled by reflecting only the difference in internal temperature in order to facilitate understanding.

  In the example shown in FIG. 3B, at the start of wireless communication (time t0), the wireless communication unit 120 performs wireless communication using PSK (first modulation scheme). At this time, the transmission output control unit 112 controls the transmission output by feedback adjusting the difference between the transmission output value detected by the transmission output detection unit 122 and the transmission output specified value.

  When the modulation method changes to QAM (second modulation method) at time t1, the transmission output control unit 112 detects the internal temperature at timings after time t1 (time t2 is illustrated in FIG. 3B). Then, a difference TA between the internal temperature and the latest internal temperature when wireless communication is performed using PSK (first modulation method) is calculated. When the difference TA is calculated, the transmission output control unit 112 refers to the control information table 134, reads the correction value corresponding to the difference TA, and wirelessly communicates the read correction value with the first modulation method. The transmission output is controlled by correcting (adding) the latest output instruction value (output instruction value at time t1).

  Thereafter, when the modulation scheme returns to PSK at time t3, the transmission output control unit 112 controls the transmission output by a control method corresponding to the first modulation scheme. When the modulation scheme is changed to QAM again at time t4, the transmission output control unit 112 controls the transmission output by a control method corresponding to the second modulation scheme.

  In the example illustrated in FIG. 3B, the transmission output control unit 112 also detects the internal temperature and calculates the internal temperature difference TB at timings after time t4 (exemplifies time t5). Then, the transmission output control unit 112 refers to the control information table 134, reads a correction value corresponding to the difference TB, and outputs the read correction value as the latest output instruction when wirelessly communicating with the first modulation method. It is corrected (added) to a value (transmission output value at time t4).

  In step S214, the control unit 110 generates and stores control information used in the second modulation scheme (QAM), but this step is optional, and the control information may be determined in advance. Hereinafter, an operation for generating control information that is not determined in advance will be described.

  In step S212, the control unit 110 controls the transmission output of the wireless communication unit 120 when the modulation method is the first modulation method (PSK), and then performs wireless communication with the current internal temperature and the first modulation method. The difference between the internal temperature when performing (difference between the internal temperatures), the difference between the current transmission frequency and the transmission frequency when performing wireless communication with the first modulation scheme (the difference between the transmission frequencies), and Control information that associates a difference (correction value) between the current transmission instruction value and the transmission instruction value when wireless communication is performed using the first modulation method is generated, and the control information table 134 (FIG. 3) of the storage unit 130 is generated. (See (a)).

  That is, in the base station 100 and the wireless communication method thereof according to the present embodiment, the control information is generated while wireless communication is performed using the first modulation scheme. Thereby, since the control information according to the state of each base station 100 can be generated dynamically, in other words, not the catalog value of the base station 100 (wireless communication apparatus), there is an individual difference for each device. Even if it exists, accurate control can be performed. In addition, since the control information is periodically regenerated, correct output control can be performed even when the output characteristics change due to aging of components.

  As described above, according to the radio communication apparatus and radio communication method of the present embodiment, in the case of QAM modulation in which amplitude modulation is performed (information is included in the amplitude component), feedback control based on a transmission output specified value is not performed. The output instruction value when PSK modulation is performed is used after being corrected. Thereby, it is possible to stably control the transmission output during QAM modulation as compared with the conventional feedback control. As a result, in an area such as an area fringe where the transmission output affects the communication target (in this embodiment, the wireless terminal 102), it is possible to stabilize the communication and improve the frequency utilization efficiency.

  In particular, in this embodiment, the existing transmission output detection unit 122 provided in the base station 100 can be used, and it is not necessary to use a high-precision detector with high-speed processing, so that the equipment cost is reduced. However, the above-described effects can be obtained.

  In the control information table 134, the difference between each temperature and the internal temperature may be associated with the correction value. In this case, in step S226, the transmission output control unit 112 refers to the control information from the difference between the current internal temperature and the internal temperature, and controls the wireless communication unit 120 using the obtained correction value. In the control information table 134, each transmission frequency may be associated with a difference between the transmission frequency and a correction value. In this case, in step S226, the transmission output control unit 112 refers to the control information from the difference between the current transmission frequency and the transmission frequency, and controls the wireless communication unit 120 using the obtained correction value.

  In the embodiment described with reference to FIG. 3B, the configuration in which the transmission output control method is changed each time the first modulation scheme and the second modulation scheme are switched is exemplified, but this is also limited. It is not a thing. For example, even when the transmission output control unit 112 instantaneously switches to the first modulation method during wireless communication using the second modulation method, the transmission output control unit 112 performs wireless communication using the second modulation method. You may continue control of the transmission output in performing. This makes it possible to perform stable control without frequently changing transmission output control. For example, when a section of a packet while the wireless communication unit 120 performs wireless communication with the second modulation method is instantaneously switched to the first modulation method and returned to the second modulation method. It is.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention relates to a wireless communication device that performs wireless communication using an adaptive modulation method, and a wireless communication device that uses an adaptive modulation method including a first modulation method that does not perform amplitude modulation or a second modulation method that performs amplitude modulation. Can be used for a wireless communication method when performing wireless communication.

DESCRIPTION OF SYMBOLS 100 ... Base station, 102 ... Wireless terminal, 110 ... Control part, 112 ... Transmission output control part, 120 ... Wireless communication part, 120a ... Communication antenna, 122 ... Transmission output detection part, 124 ... Temperature detection part, 126 ... Frequency detection Part, 130 ... storage part, 132 ... transmission output specified value, 134 ... control information table

Claims (8)

In a wireless communication apparatus that performs wireless communication using an adaptive modulation method,
A wireless communication unit that transmits a wireless signal by the first modulation method or the second modulation method;
A transmission output detection unit for detecting a transmission output value when transmitting the wireless signal;
A control unit for controlling the transmission output of the wireless communication unit,
The controller is
When the adaptive modulation scheme is the first modulation scheme, the transmission output of the wireless communication unit is controlled using a transmission instruction value based on the detected transmission output value and a predetermined transmission output specified value;
When the adaptive modulation method is the second modulation method, the wireless communication is performed with a transmission instruction value corrected using a correction value obtained based on a current internal temperature or a transmission frequency when transmitting the wireless signal. A wireless communication device for controlling the transmission output of the unit. Control information that associates the difference between the current internal temperature and the latest internal temperature when wireless communication is performed in the first modulation method and the correction value;
When the adaptive modulation method is a second modulation method, the control unit controls a transmission output of the wireless communication unit using a correction value obtained based on a current internal temperature with reference to the control information. Item 2. The wireless communication device according to Item 1.   When the adaptive modulation scheme is the first modulation scheme, the control information includes a difference between a current internal temperature and an internal temperature when wireless communication is performed using the first modulation scheme, and a current transmission instruction value. The wireless communication device according to claim 2, wherein the wireless communication device is generated in association with a correction value that is a difference between a transmission instruction value when wireless communication is performed using the first modulation method. Control information that associates the difference between the current transmission frequency and the most recent transmission frequency when performing wireless communication with the first modulation scheme and the correction value,
When the adaptive modulation method is a second modulation method, the control unit controls a transmission output of the wireless communication unit using a correction value obtained based on a current transmission frequency with reference to the control information. Item 2. The wireless communication device according to Item 1.   When the adaptive modulation scheme is the first modulation scheme, the control information includes a difference between a current transmission frequency and a transmission frequency when wireless communication is performed using the first modulation scheme, and a current transmission instruction value. The wireless communication device according to claim 4, wherein the wireless communication device is generated in association with a correction value that is a difference between a transmission instruction value when wireless communication is performed using the first modulation method.   6. The wireless communication apparatus according to claim 1, wherein the first modulation method is a modulation method that does not perform amplitude modulation, and the second modulation method is a modulation method that performs amplitude modulation.   While the wireless communication unit is wirelessly communicating with the second modulation method, the control unit is configured to detect the current internal temperature or the wireless signal even when the first modulation method is instantaneously performed. The radio according to any one of claims 1 to 6, wherein a transmission output of the radio communication unit is controlled by a transmission instruction value corrected using a correction value obtained based on a transmission frequency at the time of transmitting a signal. Communication device. In a wireless communication method of a wireless communication apparatus having a wireless communication unit that transmits a wireless signal using an adaptive modulation method including a first modulation method that does not perform amplitude modulation or a second modulation method that performs amplitude modulation,
When the adaptive modulation method is the first modulation method, the wireless communication is performed using a transmission output value detected when transmitting the wireless signal and a transmission instruction value based on a predetermined transmission output specified value. Controlling the transmission output of the unit;
When the adaptive modulation method is the second modulation method, the wireless communication is performed with a transmission instruction value corrected using a correction value obtained based on a current internal temperature or a transmission frequency when transmitting the wireless signal. Controlling the transmission output of the unit;
A wireless communication method comprising:

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