WO2006059725A1

WO2006059725A1 - Wireless communication apparatus and transmission output control method

Info

Publication number: WO2006059725A1
Application number: PCT/JP2005/022206
Authority: WO
Inventors: Tomohiro Matano
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-12-03
Filing date: 2005-12-02
Publication date: 2006-06-08
Also published as: JP2006165742A

Abstract

A predetermined communication quality is maintained, while the transmission output is controlled such that a minimum transmission output is obtained, thereby achieving both a reduction in power consumption and the maintenance of communication quality at the same time. A data processing part (25) calculates a transmission success rate, based on both the number of transmissions of transport signals and the number of receptions of ACK signals responsive to those transport signals in each predetermined time period. A transmission output control part (27) outputs, based on a calculation result of transmission success rate, a control signal to a transmitting part (26), thereby controlling the transmission output of the transmitting part (26). At this moment, when the transmission success rate is greater than an appropriate range, the transmission output is controlled such that it is reduced. Contrarily, when the transmission success rate becomes smaller than the appropriate range, the transmission output is controlled such that it is increased. In this way, the transmission output is reduced to such a minimum level that can maintain the communication quality, thereby reducing the power consumption.

Description

Specification

Wireless communication apparatus and transmission output control method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a radio communication apparatus and a transmission output control method used for wireless communication such as a wireless LAN and having a transmission output control function.

Background art

Conventionally, various technologies for reducing power consumption have been proposed for extending the life of a rechargeable battery used as a power source in a wireless communication device. As an example of a wireless communication device with reduced power consumption during transmission, the number of receptions of wireless signals including ACK signals (positive response signals) and the number of receptions of wireless signals including NAK signals (negative response signals) A wireless data communication apparatus that controls transmission output in response to a difference is disclosed. According to this conventional example, power consumption can be reduced by increasing or decreasing the transmission output according to the communication state, and communication can be performed against disturbances such as external noise (see Patent Document 1). ).

[0003] However, for example, in wireless communication devices used for wireless LAN (IEEE 802.11a / b / g, etc.), transmission output control is not performed in each device. If it is large, there is a risk of causing interference as a communication failure between the own device and other neighboring devices, and there is a problem that power consumption is wasted. It may be possible to reduce power consumption by providing a power save mode in the operation mode of the wireless communication device. In the power save mode, sufficient transmission output may not be obtained during transmission.

[0004] Further, in the wireless data communication device described in Patent Document 1, it is necessary to use an ACK signal and a NAK signal for transmission output control. For communication in a wireless LAN or the like that does not transmit / receive a NAK signal I can't respond. For this reason, conventionally, NAK signals such as wireless LAN have not been used, and for wireless communications, fine transmission power control has been achieved.

Patent Document 1: Japanese Patent Laid-Open No. 8-8777

Disclosure of the invention

Problems to be solved by the invention

[0006] The present invention has been made in view of the above circumstances, and maintains the predetermined communication quality while maintaining the minimum. An object of the present invention is to provide a wireless communication apparatus that can be controlled so as to have a limited transmission output and can achieve both reduction of power consumption and ensuring of communication quality.

Means for solving the problem

[0007] The wireless communication device of the present invention is a wireless communication device having a receiving unit that receives a signal and a transmitting unit that transmits the signal, the number of transmissions of a transmission signal transmitted from the transmitting unit to a transmission destination, and the receiving unit A data processing unit that calculates a transmission success rate by dividing the number of receptions of the ACK signal by the number of transmissions based on the number of receptions of the ACK signal transmitted corresponding to the transmission signal received from the transmission destination in FIG. A transmission output control unit that controls a transmission output of the transmission unit according to the transmission success rate, and the transmission output control unit reduces the transmission output when the transmission success rate is larger than a predetermined appropriate range. This is the control to be performed.

Thus, for example, by repeating the transmission output control every predetermined period, the transmission output is controlled in a stepwise manner in a state where the transmission success rate is within a predetermined appropriate range. It is possible to control the transmission power to the minimum while maintaining it. As a result, both reduction of power consumption and securing of communication quality can be achieved.

[0009] Further, in the above wireless communication apparatus, the transmission output control unit performs control to increase the transmission output when the transmission success rate is smaller than a predetermined appropriate range. As a result, for example, by repeating the transmission output control every predetermined period, when the transmission success rate becomes smaller than the predetermined appropriate range, the transmission output is controlled to be gradually increased so as to be within the predetermined appropriate range. It is possible to increase the output to ensure the required communication quality.

[0010] Further, in the above wireless communication device, the transmission output control unit performs control to maximize the transmission output when the transmission success rate is smaller than a predetermined threshold. When the transmission success rate becomes smaller than a predetermined threshold, it is possible to secure the necessary communication quality instantaneously with the transmission output as the maximum output.

[0011] Further, in the above configuration, the transmission output control unit can selectively operate operation modes including power consumption priority, communication quality priority, maximum output transmission, etc., and transmission in each operation mode It is good also as a structure which performs output control. In addition, the operation mode as described above can be selected by user settings, or can be automatically selected and executed according to the state of the device such as the remaining battery level for driving the wireless communication device. Good.

[0012] A transmission output control method of the present invention is a transmission output control method of a wireless communication apparatus that performs wireless communication, and the number of transmissions of a transmission signal to be transmitted to a transmission destination and the transmission destination corresponding to the transmission signal A transmission success rate calculating step of calculating a transmission success rate by dividing the number of receptions of the ACK signal by the number of transmissions based on the number of receptions of the ACK signal sent by the transmitter, and according to the transmission success rate, A transmission output control step for controlling the transmission output, and in the transmission output control step, when the transmission success rate is larger than a predetermined appropriate range, control for decreasing the transmission output is performed.

Thus, for example, by repeating the transmission output control every predetermined period, the transmission output is controlled in a stepwise manner in a state where the transmission success rate is within a predetermined appropriate range. It is possible to control the transmission power to the minimum while maintaining it, and to reduce power consumption.

The invention's effect

[0014] According to the present invention, a wireless communication apparatus that can control the minimum transmission output while maintaining a predetermined communication quality, and can achieve both reduction of power consumption and ensuring of communication quality, and A transmission output control method can be provided.

Brief Description of Drawings

FIG. 1 is a diagram for explaining a relationship between devices during transmission output control in a wireless communication device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing main components in the wireless communication apparatus of the present embodiment

FIG. 3 is a flowchart showing a procedure of transmission output control processing according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a procedure of transmission output control processing according to the second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the transmission output and the transmission success rate in the wireless communication apparatus of this embodiment. o

Explanation of symbols

First wireless communication device

12 Second wireless communication device

15 Transmission signal

16 Response signal (ACK signal)

21 Wireless communication device

22 Antenna

24 Receiver

25 Data processing section

26 Transmitter

27 Transmission output controller

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a diagram for explaining a relationship between devices at the time of transmission output control in a wireless communication device according to an embodiment of the present invention. In the present embodiment, an example will be described in which the present invention is applied to a wireless communication apparatus that connects to a wireless LAN (such as IEEE 802.11a / b / g) and performs wireless communication. As a communication form, communication between terminals in a wireless LAN, communication between an access point provided to connect the terminal to the network and the terminal, and the like can be assumed. Note that the present invention can be similarly applied to wireless communication apparatuses of other communication methods.

[0018] When wireless communication is performed between the first wireless communication device 11 and the second wireless communication device 12, a transmission signal 15 including transmission data transmitted from the first wireless communication device 11 is transmitted to the antenna 13 Is transmitted as radio waves and received by the antenna 14 of the second wireless communication device 12. Further, in the second wireless communication device 12, when the transmission signal 15 is received, a response signal 16 is output and transmitted as a radio wave from the antenna 14, and the response signal 16 is transmitted to the antenna of the first wireless communication device 11. Received at 13.

In communication in a wireless LAN, if the transmission signal 15 transmitted from the first wireless communication device 11 to the second wireless communication device 12 can be normally received by the second wireless communication device 12, the second wireless communication device 12 An acknowledgment signal (ACK: ACKnowledgement, hereinafter referred to as ACK signal) is returned as a response signal 16 from the communication device 12 to the first wireless communication device 11. First wireless communication device By receiving the ACK signal, the device 11 can confirm that the data has been transmitted normally.

[0020] In the present embodiment, a transmission success rate indicating the rate of successful data transmission is calculated using the number of receptions of the ACK signal, and transmission output is controlled according to this transmission success rate. The transmission success rate is obtained by dividing the number of ACK signal receptions (number of ACK receptions) by the number of transmission signal transmissions. Here, the ACK reception count and transmission count may be calculated using the number of packets to be transmitted and received, respectively. As the transmission output control, when the transmission success rate is higher than a predetermined value that can ensure a predetermined communication quality, the transmission output level is lowered. In this way, the transmission output is controlled within a range where the transmission success rate does not fall below a predetermined value, and data transmission is performed at the minimum transmission output level that can maintain the required transmission success rate. As a result, power consumption can be reduced while ensuring sufficient communication quality.

[0021] Based on the ratio of the number of receptions of the ACK signal to the number of transmissions of the transmission signal defined as the transmission success rate, the transmission between the wireless communication device of the transmission source and the wireless communication device of the communication partner as the transmission destination is performed. The communication quality of the round-trip transmission path can be estimated. The fact that the ACK signal has been received at a predetermined rate indicates that at least the ACK signal of the transmission destination can be received in the normal state at the transmission source, and it can be confirmed that the transmission destination also has the line quality of the transmission path to the transmission source. Can be judged to be good. In addition, it can be confirmed that the transmission signal from the transmission source can be received in the normal state at the transmission destination by receiving the ACK signal, so that the channel quality of the transmission path from the transmission source to the transmission destination is considered to be good. be able to. Therefore, even when transmission output control is performed with only one wireless communication device, transmission output is maintained while maintaining a transmission success rate of a predetermined value or more according to the communication quality of the transmission path with the communication partner device. By controlling to reduce the power consumption during transmission, the required communication quality can be ensured.

[0022] In addition, by performing the transmission output control in both wireless communication apparatuses that perform communication, each wireless communication apparatus has a minimum transmission output level that can ensure necessary communication quality. The transmission output can be controlled more precisely. For example, even if the transmission output of the transmission source wireless communication device is small and the transmission success rate is low, by executing the control to increase the transmission output on the transmission destination wireless communication device side, it is possible to perform appropriate mutual transmission. Wireless communication that maintains the success rate is possible. FIG. 2 is a block diagram showing main components in the wireless communication apparatus of the present embodiment. The wireless communication device 21 includes an antenna 22 that transmits and receives wireless signals, an antenna duplexer 23 that separates transmission signals and reception signals, a reception unit 24 that performs processing such as demodulation of reception signals, and transmission data or reception A data processing unit 25 that performs various processing such as data processing of data, a transmission unit 26 that performs processing such as modulation of transmission signals and power amplification, and a transmission output control unit that controls output power of transmission signals from the transmission unit 26 And 27. The data processing unit 25 and the transmission output control unit 27 are configured to include a processor and a memory, and realize a function by executing a predetermined processing program.

The receiving unit 24 demodulates the received signal received by the antenna 22 and outputs the demodulated signal to the data processing unit 25. The data processing unit 25 performs data processing such as decoding of received received data and data processing such as encoding of transmission data to be transmitted. The transmission unit 26 modulates transmission data, etc., performs power amplification and the like of the transmission signal, and outputs the result from the antenna 22. Here, when the data processing unit 25 has successfully received the transmission data from the transmission source wireless communication device, the data processing unit 25 sends the ACK signal to the transmission unit 26 so as to transmit the ACK signal to the transmission source wireless communication device. Output the transmission data. Then, an ACK signal is output from the transmission unit 26 via the antenna 22 and transmitted to the wireless communication apparatus as the transmission source.

[0025] Further, the data processing unit 25 calculates a transmission success rate based on the number of transmissions of the transmission signal and the number of receptions of the ACK signal for the transmission signal every predetermined period, and the calculation result is transmitted to the transmission output control unit. Output to 27. The transmission output control unit 27 outputs a control signal to the transmission unit 26 based on the input transmission success rate calculation result, and controls the transmission output of the transmission unit 26.

FIG. 3 is a flowchart showing the procedure of the transmission output control process according to the first embodiment of the present invention. This transmission output control process is realized by executing a processing program in the data processing unit 25 and the transmission output control unit 27 of the wireless communication device 21. The transmission output control of the first embodiment is a process for increasing / decreasing the transmission output step by step according to the transmission success rate and lowering the transmission output level to the minimum level within a range where necessary communication quality can be maintained. .

First, the transmission output control unit 27 performs processing for setting the transmission output to the maximum output (step Sl). That is, at first, the transmission unit 26 performs transmission at the maximum output of the device. The Next, after the lapse of a predetermined period, the transmission success rate is calculated by calculating the number of ACK reception times the number of transmissions for the transmitted and received data (step S2).

[0028] Then, it is determined whether or not the transmission success rate is greater than a predetermined appropriate range (step S3).

Here, the predetermined appropriate range refers to the range of the minimum transmission success rate that can maintain the required communication quality. For example, a transmission success rate of 95 to 96% is set as an appropriate range. If the transmission success rate is larger than the appropriate range, the transmission output control unit 27 performs control to reduce the transmission output by one step as a transmission output reduction process (step S4). As a result, the output level of the transmission signal output from the transmission unit 26 is reduced by one step.

On the other hand, if the transmission success rate is not greater than the appropriate range, it is determined whether or not the transmission success rate is smaller than the predetermined appropriate range (step S5). If the transmission success rate is smaller than the appropriate range, the transmission output control unit 27 performs control to increase the transmission output by one step as a transmission output increase process (step S6). As a result, the output level of the transmission signal output from the transmitter 26 is increased by a step. If NO in steps S3 and S5 and the transmission success rate is within a predetermined appropriate range, the process returns to step S2, and the transmission success rate is calculated again after a predetermined period. Thereafter, by repeating the above process, the transmission success rate is controlled to be within a predetermined appropriate range, and the transmission output is controlled to a minimum level. As a specific example of the above transmission output control, for example, the control range is set to 20 dB, and the transmission output level is adjusted to increase or decrease by 4 dB within this control range.

FIG. 4 is a flowchart showing the procedure of the transmission output control process according to the second embodiment of the present invention. This transmission output control process is realized by executing a processing program in the data processing unit 25 and the transmission output control unit 27 of the wireless communication device 21. In the transmission output control of the second embodiment, the transmission output is increased or decreased stepwise according to the transmission success rate, and the transmission output level is reduced to the minimum level within a range where necessary communication quality can be maintained, and the transmission succeeds. When the rate falls below the specified value, processing to return the transmission output to the maximum is performed.

[0031] First, similarly to the first embodiment, the transmission output control unit 27 performs a process of setting the transmission output to the maximum output, and first, the transmission unit 26 performs transmission at the maximum output of the apparatus. (Step Sl l). Next, after a predetermined period of time, ACK reception The number ÷ the number of transmissions is calculated to calculate the transmission success rate (step S12).

Then, it is determined whether or not the transmission success rate is larger than a predetermined appropriate range (step S13). If the transmission success rate is larger than the appropriate range, the transmission output control unit 27 performs control to reduce the transmission output by one step as a transmission output reduction process (step S14). As a result, the output level of the transmission signal output from the transmission unit 26 is reduced by one step. On the other hand, if the transmission success rate is not larger than the appropriate range, it is determined whether or not the transmission success rate is smaller than the predetermined appropriate range (step S15). If the transmission success rate is smaller than the appropriate range, it is further determined whether or not the transmission success rate is smaller than a predetermined threshold value that is smaller than the appropriate range (step S16). For example, the threshold is 90%.

Here, if the transmission success rate is smaller than the appropriate range and equal to or greater than the threshold, the transmission output control unit 27 performs control to increase the transmission output by one step as the transmission output increase process (step S 17). As a result, the output level of the transmission signal output from the transmission unit 26 is increased by one step. On the other hand, if the transmission success rate is smaller than the threshold value, the process returns to step S11 to perform processing for setting the transmission output to the maximum output.

[0034] If NO in steps S13 and S15 and the transmission success rate is within a predetermined appropriate range, the process returns to step S12, and the transmission success rate is calculated again after a predetermined period. Thereafter, by repeating the above processing, the transmission success rate is controlled to be within a predetermined appropriate range, and the transmission output is controlled to a minimum level. In the second embodiment, when the transmission success rate falls below a predetermined value, processing to return to the maximum output is performed, so that the transmission output level is increased at a time so that communication quality can be secured quickly.

FIG. 5 is a diagram showing the relationship between the transmission output and the transmission success rate in the wireless communication apparatus of this embodiment. As shown in the graph of Fig. 5, as the transmission output of the wireless communication device increases, the CZN increases in the receiving device (when interference is negligible), so the transmission success rate seen on the transmitting side increases. Approaching%. If the propagation characteristics of the air interface between the transmitting device and the receiving device can be regarded as constant without fluctuation, (transmission output on the transmitting side) = (reception on the receiving side) Electric field strength). In this embodiment, when the transmission success rate is larger than the predetermined appropriate range, the transmission output is reduced, for example, while ensuring the necessary communication quality with a transmission success rate of 95% or more, the transmission success rate is Power consumption can be reduced. In addition, when the transmission success rate becomes smaller than a predetermined appropriate range, sufficient communication quality can be maintained by increasing the transmission output.

[0036] As described above, in this embodiment, the transmission success rate of the wireless communication apparatus is sufficiently high! When the transmission success rate is reduced, the transmission output is reduced so that the transmission success rate becomes small within a range that does not fall below a certain threshold. By controlling, it is possible to perform transmission at the minimum transmission output level maintaining a predetermined communication quality. As a result, the power consumption can be reduced while maintaining the communication quality, and the power consumption of the wireless communication apparatus can be reduced. Further, by reducing the transmission output, there is an advantage that interference that causes communication failure to other wireless communication systems can be reduced.

[0037] It should be noted that the present invention is not limited to the above-described embodiment, and it is obvious that the embodiment can be appropriately changed within the scope of the technical idea of the present invention. The present invention is applicable to a wireless communication system such as a wireless LAN and other wireless communication systems in general as long as an ACK signal is used for a communication response.

[0038] In the above embodiment, the power consumption decreases as the transmission output decreases, but the communication quality decreases. Therefore, priority is given to power consumption, communication quality is prioritized, and the maximum output is always set according to user settings. A function may be provided that allows selection of an operation mode such as transmission. In addition, a function for automatically executing operation mode selection settings of the wireless communication device such as power consumption priority, communication quality priority, and maximum output transmission may be provided depending on the remaining amount of the battery that drives the wireless communication device.

[0039] While the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. is there.

This application is based on Japanese Patent Application (Japanese Patent Application No. 2004-350947) filed on December 3, 2004, the contents of which are incorporated herein by reference.

Industrial applicability

[0040] The present invention can be controlled so as to achieve a minimum transmission output while maintaining a predetermined communication quality, and has the effect of reducing both power consumption and ensuring communication quality. Wireless communication device with transmission output control function used for wireless communication such as LAN It is useful for transmission output control methods and the like.

Claims

The scope of the claims

[1] A wireless communication apparatus having a reception unit that receives a signal and a transmission unit that transmits the signal, the number of transmissions of a transmission signal transmitted from the transmission unit to a transmission destination, and the transmission received from the transmission destination in the reception unit A data processing unit that calculates a transmission success rate by dividing the number of receptions of the ACK signal by the number of transmissions based on the number of receptions of the ACK signal transmitted corresponding to the signal;

A transmission output control unit for controlling the transmission output of the transmission unit according to the transmission success rate,

The transmission output control unit is a wireless communication apparatus that performs control to reduce the transmission output when the transmission success rate is larger than a predetermined appropriate range.

[2] The wireless communication device according to claim 1,

The transmission output control unit is a wireless communication apparatus that performs control to increase the transmission output when the transmission success rate is smaller than a predetermined appropriate range.

[3] The wireless communication device according to claim 1,

The transmission output control unit is a wireless communication apparatus that performs control to maximize the transmission output when the transmission success rate is smaller than a predetermined threshold.

[4] A transmission output control method for a wireless communication device that performs wireless communication,

Successful transmission by dividing the number of receptions of the ACK signal by the number of transmissions based on the number of transmissions of the transmission signal transmitted to the transmission destination and the number of receptions of the ACK signal transmitted from the transmission destination corresponding to the transmission signal. A transmission success rate calculating step for calculating a rate;

A transmission output control step for controlling the transmission output of the transmission unit according to the transmission success rate,

A transmission output control method, wherein, in the transmission output control step, control is performed to decrease the transmission output when the transmission success rate is larger than a predetermined appropriate range.