JP4762171B2 - Wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption and to secure efficient radio communication by performing control for changing a transmission power value according to a state of the radio communication. <P>SOLUTION: A wireless LAN module 20 detects C/N ratio to carrier wave received by a C/N detection circuit 21c included in an RF circuit part 21, determines the present level of wireless LAN environment based on the detected C/N ratio, simultaneously determines a transmission power value corresponding to the determined level from a power table 40. A CPU 27 controls a power control part 21a of the RF circuit part 21 so as to perform transmission by the determined power value. Thus, when a state of a wireless LAN is satisfactory, the transmission power value is lowered to reduce the power consumption within a range that a transfer bit rate is not reduced and when the state of the wireless LAN is not satisfactory, the transmission power value is enhanced to maintain predetermined communication efficiency. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a wireless communication apparatus capable of controlling transmission power at the time of transmission in wireless communication, and more particularly to a wireless communication apparatus that performs transmission power control finely corresponding to various factors that affect the state of wireless communication.

  Conventionally, there are various standards for wireless communication. For example, there is a standard regarding wireless LAN in IEEE802.11 system of IEEE (American Institute of Electrical and Electronics Engineers). As a type of wireless communication based on the wireless LAN standard, the terminal device is wireless with respect to an ad hoc mode in which wireless LAN terminal devices perform wireless communication and a wireless communication relay device (access point) connected to a wired network. There is an infrastructure mode for communication. In the infrastructure mode, the access point transmits a beacon signal including identification information (for example, transmits at a bit rate of 6 Mbit / sec), and the terminal device receives the beacon signal to confirm the presence of the access point. Detects and synchronizes wireless communication.

  Such a wireless communication apparatus is generally provided to a user in a portable form because there is no restriction on a communication line compared to a wired communication apparatus. However, since the usage time of portable devices is limited by the amount of power remaining in the built-in power supply, the transmission power when transmitting according to the situation (environment) of wireless communication can be extended as much as possible. There are wireless communication apparatuses that perform control and reduce power consumption.

Specifically, in the wireless terminal devices according to Patent Document 1 and Patent Document 2 described below, transmission power is controlled based on the received electric field strength (radio wave strength) of a beacon signal (received signal) transmitted from an access point. Specifically, when the received electric field strength is large, the wireless communication status is good, and even if the transmission power is reduced, wireless communication can be performed without any trouble. Therefore, the wireless terminal devices according to Patent Document 1 and Patent Document 2 are If the detected received electric field strength (radio wave strength) is large, transmission power is reduced to reduce power consumption. Further, in the wireless terminal device according to Patent Document 3 below, transmission power is controlled based on a total of three items: reception power level, packet error rate of a wireless signal, and communication speed of a wireless signal.
JP 2000-261392 A Japanese Patent Laid-Open No. 2005-328231 JP 2005-117303 A

  The state (environment) of wireless communication generally changes from time to time due to various factors. Factors that affect the change include the degree of noise components (for example, carrier power / noise power, hereinafter referred to as C / N ratio) included in the carrier wave, in addition to the radio wave intensity (power intensity) related to reception, and connection is possible Examples include the number of access points (wireless communication relay devices) and the number of other wireless devices located in the vicinity where wireless communication is to be performed. In addition, in the C / N ratio, which is one of these factors, the condition that the C / N ratio deteriorates is that when the distance between the devices that perform wireless communication is long, an obstacle is located between the devices that perform wireless communication. If there is a physical cause such as, but other external noise occurs randomly, unauthorized access points that do not conform to the wireless communication standard (access temporarily provided at event venues and show venues, etc.) This is also the case when there are many points).

  In addition, when there are multiple access points that can be connected, it is also possible to switch the connection destination to the access point with the best situation. Conversely, when there is one access point that can be connected, other situations Even if the power intensity (reception power intensity, C / N ratio, etc.) is poor, the access point must be selected. Furthermore, when there are a large number of other wireless devices in the vicinity that are trying to perform wireless communication, the communication access to the access point is congested. Power will be consumed.

  Therefore, since the state of wireless communication generally changes from time to time due to such various factors, the power strength (electric field strength) of the received signal is mainly used as in the wireless terminal device according to Patent Document 1 to Patent Document 3 described above. If the transmission power is controlled in this way, there is a problem that the transmission power cannot be controlled to match the actual wireless communication status. This problem also occurs when wireless communication is performed based on other standards (for example, Wireless USB, UWB (Ultra Wide Band), Wireless 1394, etc.) in addition to the wireless LAN standard.

  The present invention has been made in view of such a problem, and detects a factor that affects the state of wireless communication, and performs wireless communication control that actively increases or decreases transmission power based on the detection result. An object is to provide an apparatus.

  In order to solve the above-described problem, a wireless communication device according to the present invention includes a noise component detection unit that detects a value related to a noise component included in a carrier wave of a received signal in a wireless communication device that performs wireless communication, and the noise component. A noise comparison unit that compares a detection result detected by the detection unit with a noise reference value; a value specifying unit that specifies a value of transmission power related to signal transmission based on the comparison result of the noise comparison unit; and the value specification Transmission power control means for controlling the transmission power value so that the means has a specified value.

  In the present invention, the detection result of the value related to the noise component contained in the carrier wave of the received signal is compared with the noise reference value, and the transmission power value of the transmission signal is specified and controlled based on the comparison result. The transmission power can be controlled in accordance with the degree of the noise component contained in the carrier wave. Therefore, compared to the noise reference value, when it is determined that the noise component is less than the noise reference value, the situation in which wireless communication is performed is good, so the transmission power is reduced to a level where wireless communication can be performed normally. However, since there is no trouble in wireless communication, it is possible to perform control such as reducing transmission power. Also, when it is determined that there are more noise components than the noise reference value, the situation in which wireless communication is performed is not good, so control to increase the transmission power so that wireless communication can be performed at a normal level while ensuring communication efficiency even a little. It can also be done. Even if the control for increasing the transmission power is performed as described above, if the level of the noise component becomes low after that, the control for decreasing the transmission power can be performed to avoid unnecessary power consumption.

  According to another aspect of the present invention, there is provided a wireless communication device that performs wireless communication with a wireless communication relay device, a relay device detection unit that detects the number of wireless communication relay devices capable of wireless communication, and the relay device detection unit. Value specifying means for specifying the value of transmission power related to signal transmission, and transmission power control means for controlling the transmission power value so as to be the value specified by the value specifying means based on the number detected by It is characterized by that.

  In the present invention, the number of wireless communication relay devices capable of wireless communication is detected, and the transmission power value of the transmission signal is specified and controlled based on the detected number. The transmission power can be controlled according to the number of devices. Therefore, when there are a plurality of wireless communication relay devices that can be accessed, wireless communication can be performed using any one wireless communication relay device even if the transmission power value is reduced below the standard value. On the contrary, if there is one accessible wireless communication relay device, it must be used for that wireless communication relay device, so transmission power can be used to perform wireless communication at a normal level. You will control the value.

  Furthermore, the wireless communication device according to the present invention is a wireless communication device that performs wireless communication with a wireless communication relay device, a signal receiving unit that receives a reception preparation completion signal transmitted by another wireless device, and the signal receiving unit receives the signal. A signal number detecting unit for detecting the number of received preparation completion signals, a value specifying unit for specifying a value of transmission power related to signal transmission based on the number detected by the signal number detecting unit, and the value specifying unit Transmission power control means for controlling the transmission power value so as to have a specified value.

  In the present invention, the number of reception ready signals received by other wireless devices is detected, and the value of the transmission power of the transmission signal is specified and controlled based on the detected number. The transmission power can be controlled according to the number of other wireless devices in the vicinity. Therefore, when there are a large number of other wireless devices in the vicinity that are trying to perform wireless communication, the wireless communication is congested, so control is performed to reduce the value of the transmission power, and this is a waste in situations where communication cannot be performed smoothly. Power consumption can be avoided. In addition, when the number of other surrounding wireless devices that are going to perform wireless communication is small, the wireless communication itself is not congested, and thus the transmission power value is controlled so that wireless communication can be performed at a normal level.

  The wireless communication device according to the present invention is a wireless communication device that performs wireless communication with a wireless communication relay device, wherein a noise component detection unit that detects a value related to a noise component included in a carrier wave of a received signal, and the noise component detection unit includes Noise comparison means for comparing the detected detection result with a noise reference value, relay device detection means for detecting the number of wireless communication relay devices capable of wireless communication, comparison results of the noise comparison means and the relay device detection means A value specifying unit that specifies a value of transmission power related to signal transmission based on the number detected, and a transmission power control unit that controls the transmission power value so that the value specifying unit specifies a value. It is characterized by.

  In the present invention, the detection result of the value related to the noise component in the received carrier wave is compared with the noise reference value, and the number of wireless communication relay devices capable of wireless communication is detected, and the comparison result and the detection result are obtained. Since the value of the transmission power of the transmission signal is specified and controlled based on the transmission signal, the transmission power is controlled in accordance with two factors that affect the wireless communication status, such as the degree of the noise component and the number of available wireless communication relay devices. Is possible. As a result, the value of transmission power can be finely changed to match the actual situation of wireless communication, and transmission power can be reduced to reduce power consumption or ensure communication efficiency according to the state of wireless communication. Can be controlled.

  The wireless communication apparatus according to the present invention includes a noise component detection unit that detects a value related to a noise component included in a carrier wave of a received signal in the wireless communication apparatus that performs wireless communication with the wireless communication relay apparatus, and the noise component detection Noise comparison means for comparing the detection result detected by the means with a noise reference value; signal reception means for receiving a reception preparation completion signal transmitted by another wireless device; and the number of reception preparation completion signals received by the signal reception means A signal number detecting means for detecting a signal, a value specifying means for specifying a value of transmission power related to signal transmission based on a comparison result of the noise comparing means and a number detected by the signal number detecting means, and the value specifying Transmission power control means for controlling the transmission power value so that the means has a specified value.

  In the present invention, the detection result of the value related to the noise component in the carrier wave to be received is compared with the noise reference value, and the number of reception ready signals received by other wireless devices is detected. Since the value of the transmission power of the transmission signal is specified and controlled based on the detection result, the transmission power can be controlled in accordance with two factors such as the degree of the noise component and the number of other wireless devices located in the vicinity. . As a result, the transmission power value can be finely changed to match the actual wireless communication situation, and the transmission power can be controlled to reduce power consumption or ensure communication efficiency according to the wireless communication situation. .

  Furthermore, the wireless communication device according to the present invention includes a relay device detection unit that detects the number of wireless communication relay devices capable of wireless communication, and another wireless device that performs wireless communication with the wireless communication relay device. Signal reception means for receiving a reception preparation completion signal to be transmitted; signal number detection means for detecting the number of reception preparation completion signals received by the signal reception means; the number detected by the relay device detection means and the signal number detection Based on the number detected by the means, a value specifying means for specifying the value of transmission power related to signal transmission, and a transmission power control means for controlling the transmission power value so that the value specifying means specifies the value. It is characterized by providing.

  In the present invention, the number of wireless communication relay devices capable of wireless communication is detected, the number of reception ready signals received by other wireless devices is detected, and the transmission signal is determined based on the two detection results. Since the value of the transmission power is specified and controlled, the transmission power can be controlled in accordance with two factors such as the number of available wireless communication relay devices and the number of other wireless devices located in the vicinity. As a result, it is possible to finely change the value of transmission power to match factors related to the place where wireless communication is performed and the number of devices attempting wireless communication in the surrounding area, and thus consumption according to these factors as needed. Transmission power can be controlled to reduce power or to ensure communication efficiency.

  Furthermore, the wireless communication device according to the present invention is a wireless communication device that performs wireless communication with a wireless communication relay device, a noise component detection unit that detects a value related to a noise component included in a carrier wave of a received signal, and the noise component Noise comparison means for comparing the detection result detected by the detection means with a noise reference value, relay device detection means for detecting the number of wireless communication relay devices capable of wireless communication, and reception preparation completion signals transmitted by other wireless devices The signal reception means for receiving the signal, the signal number detection means for detecting the number of reception ready signals received by the signal reception means, the comparison result of the noise comparison means, the number detected by the relay device detection means, and the Based on the number detected by the signal number detection means, a value specifying means for specifying the value of transmission power related to signal transmission, and the transmission power value are controlled so that the value specifying means specifies the value. Characterized in that it comprises a transmission power control unit.

  In the present invention, the comparison result between the detection result of the noise component in the received carrier wave and the noise reference value, the result of detecting the number of wireless communication relay devices capable of wireless communication, and other wireless devices Since the transmission power value of the transmission signal is specified and controlled based on the result of detecting the number of reception ready signals received by the transmitter, the transmission power is controlled in accordance with a total of three factors that affect the wireless communication status. Is possible. That is, the value of the transmission power can be changed more finely to match the actual situation where wireless communication is to be performed, and as a result, it is possible to contribute to further reduction of power consumption or securing of communication efficiency.

  The wireless communication apparatus according to the present invention includes an intensity detection unit that detects the power intensity of a carrier wave of a received signal, and an intensity comparison unit that compares a detection result detected by the intensity detection unit with an intensity reference value. The value specifying means specifies a value of transmission power related to signal transmission based on the comparison result of the strength comparing means.

  In the present invention, the power intensity of the received carrier wave is detected, and the transmission power value is specified based on the comparison result between the detection result and the intensity reference value. The transmission power can be controlled by comprehensively determining the actual wireless communication status based on a plurality of factors.

In the present invention, the transmission power of the transmission signal is specified based on the comparison result between the detection result of the value related to the noise component contained in the carrier wave of the received signal and the noise reference value, so that wasteful power consumption and communication efficiency can be reduced. The transmission power can be controlled in accordance with the level of noise components in the carrier wave so as to avoid deterioration.
Further, in the present invention, the value of the transmission power of the transmission signal is specified based on the result of detecting the number of wireless communication relay apparatuses capable of wireless communication, so that unnecessary power consumption and deterioration of communication efficiency are avoided. In addition, transmission power can be controlled in accordance with the number of available wireless communication relay devices.
Furthermore, in the present invention, since the value of the transmission power of the transmission signal is specified and controlled based on the detection result of the number of reception ready signals received by other wireless devices, wasteful power consumption and communication efficiency are achieved. Thus, the transmission power can be controlled in accordance with the number of wireless devices located in the vicinity.

In the present invention, the value of the transmission power of the transmission signal based on two factors, the comparison result between the value relating to the detected noise component in the carrier wave and the noise reference value, and the number of wireless communication repeaters capable of wireless communication Therefore, the transmission power can be finely controlled, and can be utilized to avoid wasteful power consumption and deterioration of communication efficiency.
Further, in the present invention, the transmission signal is based on the two results of the comparison result between the value relating to the detected noise component in the carrier wave and the noise reference value and the number of reception ready signals received by other wireless devices. Since the transmission power value is specified, the transmission power can be controlled in detail, and can be utilized to avoid wasteful power consumption and deterioration of communication efficiency.
Furthermore, in the present invention, the value of the transmission power of the transmission signal is specified based on two factors: the number of wireless communication relay devices capable of wireless communication and the reception number of reception preparation completion signals transmitted by other wireless devices. Therefore, transmission power can be controlled in detail according to the degree of congestion at a place where wireless communication is to be performed, which can be utilized to avoid wasteful power consumption and deterioration in communication efficiency.

In the present invention, the comparison result between the value relating to the detected noise component in the carrier wave and the noise reference value, the number of wireless communication relay devices capable of wireless communication, and the reception preparation completion signal transmitted by other wireless devices Since the value of the transmission power of the transmission signal is specified based on the number of received signals, the transmission power can be finely controlled according to a total of three factors that affect the wireless communication status, further reducing power consumption or improving communication efficiency. It can contribute to securing.
In the present invention, the transmission power value is specified based on the comparison result between the detection result of the power strength of the received carrier wave and the strength reference value, so that the transmission power can be controlled in consideration of the power strength. .

  FIG. 1 shows a main internal configuration of a portable music playback device 10 incorporating a wireless LAN module (corresponding to a wireless communication device) 20 according to the first embodiment of the present invention. The portable music player 10 is characterized in that it has a wireless LAN communication function in addition to the original music playback function. The main module 11 that supports the music playback function is replaced with a wireless LAN module that supports the wireless LAN communication function. 20 is connected. The portable music player 10 can easily acquire various music data via wireless LAN communication, and the acquired music data can be reproduced and output by the main module 11. In addition, the wireless LAN module 20 included in the portable music playback device 10 controls the value of transmission power when transmitting a signal so that it can be changed as needed according to the state of wireless communication, thereby reducing wasteful power consumption. In order to improve the efficiency of wireless communication. Hereinafter, the portable music player 10 will be described in the order of the main module 11 and the wireless LAN module 20.

  The main module 11 has a configuration in which a RAM 12, a ROM 13, a storage unit 14, an audio output processing unit 15, a main control unit (processor) 17, a display panel 18, and an operation unit 19 are connected through internal buses 11a and 11b. The RAM 12 temporarily stores data and files associated with the processing of the main control unit 17, and the ROM 13 stores in advance a playback program 13a defining control processing for music playback, playback menu data 13b for performing music selection, and the like. is doing. The memory | storage part 14 memorize | stores the music data D acquired via wireless LAN communication. The audio output processing unit 15 performs processing for outputting audio from the speaker 16 by performing reproduction processing and amplification of music data.

  The main control unit 17 connects the display panel 18 and the operation unit 19. The display panel 18 displays a menu screen or the like based on various menu data under the control of the main control unit 17. The operation unit 19 includes a plurality of keys such as up / down / left / right keys and an enter key. The operation unit 19 receives a user's selection instruction for a selection item on the menu screen, and sends the received instruction content to the main control unit 17. Tell. The main control unit 17 performs control related to the playback process of music data (for example, music data of an MP3 file) in accordance with the rules of the playback program 13a stored in the ROM 13, and performs various setting processes, etc. A process related to the setting of the wireless LAN is also performed by the linkage process with the wireless LAN module 20. In FIG. 1, the power supply system is not shown, but a battery (power supply) is mounted in the portable music player 10, and the main module 11 and the wireless LAN module 20 are powered by the power of the battery. Is driven.

  On the other hand, the wireless LAN module 20 performs wireless LAN communication (IEEE802.11, IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11k, etc.) determined by the American Institute of Electrical and Electronics Engineers. A wireless LAN RF (high frequency) circuit unit 21 and a MAC (Media Access Control) processing unit 25.

  The RF circuit unit 21 corresponds to a physical layer in the OSI reference model, and is connected to an antenna 24 for wireless LAN that transmits and receives various signals, and performs frequency conversion, I / Q conversion, and built-in power in wireless communication access control. Various processes such as amplification of received signals in the amplifier unit are performed. The operations related to these processes are controlled by the CPU 27 included in the MAC processing unit 25. In particular, in this embodiment, when the RF circuit unit 21 performs the transmission processing of the transmission signal, the transmission power is controlled by the CPU 27. It has become so. That is, the RF circuit unit 21 has a power control unit 21a (corresponding to transmission power control means) that performs control to freely change the transmission power value at the time of transmission. The power control unit 21a is instructed by the CPU 27. Transmission processing is performed with the transmitted power value. Note that the RF circuit unit 21 does not perform variable control on the received power at the time of reception and fixes the received power to a constant value.

  In addition, the RF circuit unit 21 includes an intensity detection circuit 21b (corresponding to intensity detection means) that detects a value related to the power intensity of the carrier wave of the received signal, and a value related to a noise component included in the carrier of the received signal. A C / N detection circuit 21c (corresponding to noise component detection means) for detecting the C / N ratio (carrier power / noise power) of the carrier is provided. Note that the strength detection circuit 21b of the present embodiment detects the power strength of the carrier in the range of about −80 dBm to −10 dBm.

  Here, the reason why the C / N ratio that is the detection target of the C / N detection circuit 21c varies will be described. First, when the propagation path of wireless LAN communication is a multi-wave propagation path, for example, when radio waves of the wireless LAN are reflected at a building, interference due to communication waves emitted from access points existing in the vicinity, etc. In addition, the received wave level fluctuates (fading phenomenon). In addition, the frequency shift of the carrier wave occurs due to the movement of the transceiver and the reflector that perform wireless LAN communication. Due to the fading phenomenon and frequency shift described above, the original C / N ratio cannot be secured on the receiving side.

  In IEEE802.11b, energy dispersion that spreads the spectrum of the primary modulated (DBPSK, DQPSK, etc.) carrier and error correction processing ensures the tolerance to interference waves, but fading phenomenon occurs when the tolerance is exceeded For example, the level of each subcarrier in the received signal is lower than that during transmission on the frequency axis (see FIG. 3A). Further, when a fading phenomenon occurs such that the level decrease is below the level at which the error correction processing on the receiving side can be performed (demodulation limit level) (second subcarrier from the right in the graph on the right side of FIG. 3A). ), Retransmission occurs, and transmission efficiency is significantly reduced, resulting in data errors.

  When such a phenomenon is seen on the time axis as shown in FIG. 3B, the waveform distortion increases on the receiving side. That is, the transmission waveform on the transmission side is affected by reflection, scattering, and interference with the communication radio wave emitted from the access point, so that the reception waveform is distorted on the time axis. Therefore, it is possible to detect the C / N ratio at the carrier level by measuring the level drop of each subcarrier on the frequency and measuring the waveform distortion of the carrier wave on the time axis. Note that the state where the detected C / N ratio value is large means that the noise component is small compared to the carrier wave, and thus the received radio wave quality is good (the state where the wireless LAN is performed is good). The state where the value of the C / N ratio is small means a state where the quality of the received radio wave is poor because the noise component is large (the state where the wireless LAN is performed is bad).

  Returning to FIG. 1, the MAC processing unit 25 will be described next. The MAC processing unit 25 has a configuration in which a memory 26, a CPU 27, a connection interface 28 for connecting to the main module 11, an RF connection interface 29 for connecting to the RF circuit unit 21, and the like are connected by an internal bus 25a. In wireless LAN communication, processing such as digital conversion / demodulation and access control is performed.

  FIG. 2 conceptually shows the contents of the CPU 27 functioning as the MAC layer 30 in the OSI reference model in this embodiment, and such functions are defined in the program P stored in the memory 26. Realized by content. The MAC layer 30 of the CPU 27 performs control processing according to an access method (for example, CSMA / CA) based on the IEEE (American Institute of Electrical and Electronics Engineers) wireless LAN standard (IEEE802.11 standard). Among them, Upper MAC 31 is included in the upper layer and Lower MAC 32 corresponding to the lower layer. Further, the Upper MAC 31 includes a CTS number detection block 31a and an AP number detection block 31b.

  The CTS number detection block 31a corresponds to means (signal number detection means) for detecting the number of CTS receptions from other wireless devices that receive via the antenna 24 and the RF circuit unit 21 (corresponding to signal reception means). CTS means a signal transmitted in order to prevent disruption of wireless communication by a plurality of wireless devices. In the wireless LAN standard, a wireless device that is going to start wireless communication in response to reception of an RTS (Request to Send transmission request signal) issued from an access point or the like transmits a CTS (reception preparation completion signal). When another wireless device receives, the other wireless device is stipulated to refrain from communication until the next communicable time. Therefore, when the number of times of receiving CTS within a predetermined time is large, the situation of wireless communication at that place is high, and when the number of times of receiving CTS within a predetermined time is small, The state of wireless communication at that location is low in congestion.

  Further, the AP number detection block 31b (corresponding to the relay device detecting means) in the UpperMAC 31 detects the number of access points (corresponding to the wireless communication relay device) capable of wireless communication. Specifically, identification information (for example, SSID (Service Set Identifier)) included in a beacon signal transmitted at a fixed interval (for example, 500 msec) from the access point (AP) received by the antenna 24 and the RF circuit unit 21. Based on this, the access point that can be connected at the location is identified, and the number of access points is determined.

  The CPU 27 has a clock function in addition to the MAC layer 30 described above, and performs control processing related to the MAC layer 30 and various control processes of the wireless LAN module 20 according to the time to be measured. This is performed based on the specified contents of the program P stored in the memory 26.

  Further, the memory 26 shown in FIG. 1 includes a program P, menu data 33, reference value data 34 for comparison with the detected C / N ratio, and power that defines the value of the transmission power associated with the C / N ratio. A table 40 and the like are stored.

  The reference value data 34 stored in the memory 26 is used to classify the detected C / N ratio into a plurality of levels representing the state of wireless communication. Reference value 34a, second reference value 34b, and third reference value 34c). The first reference value 34a is the largest, the second reference value 34b is the second largest, and the third reference value 34c is the smallest (the first reference value 34a to 34c). 34a> second reference value 34b> third reference value 34c).

  Each of these reference values 34a to 34c is compared with the C / N ratio (detection result) detected by the C / N detection circuit 21c with respect to the carrier of the received signal according to the definition of the program P stored in the memory 26. Thus, the CPU 27 performs processing for determining the current wireless LAN status (wireless LAN environment) from a plurality of levels based on the detected C / N ratio. In the present embodiment, when the detected C / N ratio exceeds the first reference value 34a, the wireless LAN environment is determined to be the first level corresponding to “good”. When the C / N ratio is equal to or lower than the first reference value 34a but exceeds the second reference value 34b, the wireless LAN environment is determined to be the second level corresponding to “medium (normal)”. Furthermore, when the C / N ratio is equal to or lower than the second reference value 34b and exceeds the third reference value 34c, the wireless LAN environment is determined to be the third level corresponding to “bad”. Furthermore, when the C / N ratio is equal to or less than the third reference value 34c, the wireless LAN environment is determined to be the fourth level corresponding to the “communication limit”. These level determination processes are performed at any time while the wireless LAN module 20 tries to communicate, and detect changes in the wireless LAN environment according to the C / N ratio.

  FIG. 4 shows the contents of the power table 40 stored in the memory 26. The power table 40 has contents in which the values of the transmission power when the wireless LAN module 20 transmits a transmission signal are associated with the first to fourth levels described above. The power table 40 of the present embodiment associates 10 dBm with the first level, 13 dBm with the second level, 15 dBm with the third level, and 9 dBm with the fourth level. Note that the value of the transmission power associated with each level described in the present embodiment is merely an example, and various values can be applied according to the product features, specifications, and the like.

  The concept of the set value of the transmission power for each level in the power table 40 of the present embodiment is as follows. First, the first level in which the wireless LAN environment is “good” is a situation where wireless communication can be performed immediately if wireless communication is attempted. Therefore, the transmission power is reduced to the extent that the transfer bit rate does not decrease, thereby reducing power consumption. (10 dBm). In addition, the second level where the wireless LAN environment is “medium” allows wireless communication at a normal level. Therefore, in order to improve the balance between securing a predetermined transfer bit rate and suppressing power consumption, It is higher than the level (13 dBm).

  Further, the third level where the wireless LAN environment is “bad” has a value higher than 13 dBm of the second level and is set to 15 dBm, giving priority to increasing the efficiency of wireless communication. Furthermore, the fourth level at which the wireless LAN environment is “communication limit” corresponds to the limit bit rate at which wireless communication can be used regularly, so priority is given to not consuming power over the efficiency of wireless communication. The power is reduced most to 9 dBm. In other words, even if the carrier level is high, if the external noise becomes high, the result is that the wireless state becomes inefficient, so the transfer bit rate is lowered with the deterioration of the C / N ratio, and the limit transfer bit rate is reached. In some cases, the present embodiment adopts a design philosophy that minimizes transmission power and reduces power consumption. In this embodiment, the limit of the transfer bit rate that can withstand normal use is set to a value that is 1/8 of the maximum transfer bit rate of the wireless LAN module 20.

  The menu data 33 stored in the memory 26 is data for displaying various setting menus for the wireless LAN. These data are transmitted from the main module 11 to the CPU 27 of the MAC processing unit 25 when an instruction to set the wireless LAN is received by the operation unit 19 of the main module 11, and sent to the main module 11 under the control of the CPU 27. It is done. As a result, various setting menus are displayed on the display panel 18.

  The program P stored in the memory 26 defines a control process for changing the transmission power of the transmission signal, which is a feature of the present invention, as needed according to the situation of the wireless communication, in addition to the processes related to the basic wireless LAN communication. ing. As specific contents related to transmission power control, when the C / N ratio related to the carrier of the received signal received by the RF circuit unit 21 is detected by the C / N detection circuit 21c, the CPU 27 serves as a noise comparison means. The program P defines that a process of comparing the reference value 34a to 34c stored in the memory 26 is performed. Further, based on the comparison result, the program P determines which level the current wireless LAN environment (situation) belongs to, and the transmission power value corresponding to the determined level is stored in the power table 40. It is specified that the processing specified based on the value specifying means is performed. Further, the program P specifies that the CPU 27 sends the specified value to the power control unit 21a of the RF circuit unit 21 from the CPU 27 and that the CPU 27 issues an instruction to change the value to the power control unit 21a.

  Receiving this instruction, the power control unit 21a changes the transmission power value to the transmitted value and performs transmission processing of the transmission signal, thereby realizing transmission control processing according to the current wireless LAN environment. Since a series of these control processes are performed as needed in response to signal reception, it is possible to quickly cope with a wireless LAN environment that is likely to change.

  FIG. 5A shows the control status of transmission power in the portable music playback device 10 (wireless LAN module 20) of this embodiment with the passage of time under the control of the CPU 27 based on the above-described definition of the program P. It is the shown graph. Specifically, in order to be able to perform the next process quickly in the standby state, the wireless LAN module 20 supplies a certain amount of power to predetermined portions of the internal MAC processing unit 25 and the RF circuit unit 21, thereby 300 mW Electricity is consumed. In addition, when transmitting a signal at time T1, the wireless LAN module 20 controls transmission power based on the detection of the C / N ratio described above. Therefore, in the case shown in FIG. It shows that power consumption changes in the range of 500 mW to 800 mW depending on the situation (environment).

  As shown in FIG. 5B, the relationship between the transmission power and the power consumption changes in a quadratic curve. For example, when the transmission power is 10 dBm, the power consumption is 400 mW and the transmission power is 12 dBm. Power consumption increases to 500 mW, and when the transmission power is 15 dBm, the power consumption increases to 800 mW.

  Also, in the graph of FIG. 5A, at time T2, the wireless LAN module 20 sends an ACK signal (a signal that informs the data transmission source that data has been received) issued from the access point in response to the transmission signal. Although received, the received power at the time of reception is constant, so the power consumption is also a constant value (400 mW). Furthermore, in the graph of FIG. 5A, the wireless LAN module 20 receives a signal from the access point after the standby state (power consumption 300 mW) that continues from time T3 ends at time T4. The electric power becomes a constant value (400 mW). Furthermore, when the wireless LAN module 20 transmits an ACK signal to the access point in response to the received signal, the wireless LAN module 20 changes the value of the transmission power as needed based on the detection of the C / N ratio described above. The graph of FIG. 5A shows that the power consumption changes in the range of 400 mW to 800 mW.

  At time T6 after the transmission of the ACK signal, the wireless LAN module 20 enters a standby state (power consumption 300 mW), disconnects the connected access point at time T7, and the average consumption required for the processing at this time The power will be 800 mW. After disconnecting from the access point (after time T8), the wireless LAN module 20 enters a sleep state, and power consumption in the sleep state is suppressed to 0.2 mW.

  As described above, the wireless LAN module 20 according to the present embodiment changes the transmission power to a value corresponding to the level indicating the state of the wireless LAN specified based on the detection of the C / N ratio at the time of transmission. In this case, priority can be given mainly to suppression of transmission power, and when transmission power is increased, priority can be given mainly to securing predetermined transmission efficiency, and transmission power that can flexibly respond to changes in the wireless LAN environment. Control can be realized.

  In addition, this invention is not limited to the form of the wireless LAN module 20 mentioned above, There exist various modifications. First, the number of reference values (noise reference values) 34a to 34c included in the reference value data 34 used to determine the level of the wireless LAN environment based on the detection result of the C / N ratio is limited to three. Instead, it can be appropriately increased or decreased according to the specifications, grades, etc. of the wireless LAN module 20.

  For example, when the number of reference values is more than three, the level of the wireless LAN environment that can be discriminated can be increased, and power saving processing and efficient transmission control processing are performed according to the wireless LAN environment by further finely dividing the level. Can be done. In addition, when the number of reference values is less than 3, the processing burden related to leveling can be reduced. In particular, when the reference value is 1, the detection result based on the detection result of the C / N ratio. The transmission power value can be specified by performing level division by a simple process of whether or not is greater than the reference value or less than the reference value. Further, in the level division, the association may be changed according to the type of signal to be transmitted. For example, when a substantial signal is transmitted, the level division is performed in the range from the first level to the third level. When a formal signal such as an ACK signal is transmitted, the level may be divided in the range from the first level to the fourth level by lowering the lower limit of the level. Thus, by changing the range of level division, a substantial signal can be sent to the transmission destination more reliably. Furthermore, the control of the transmission power value based on the detection result of the C / N ratio as in the first embodiment can be applied to the ad hoc mode in addition to the infrastructure mode.

  FIG. 6 shows a wireless LAN module 50 according to a modification of the first embodiment. The wireless LAN module 50 according to the modification has a configuration in which processing performed by software of the CPU 27 in FIG. 2 is replaced with a hardware circuit. More specifically, various hardware circuits 51 to 54 corresponding to the RF circuit unit 21 shown in FIG. 1 and the upper MAC 31 and the lower MAC 32 including the CTS number detection block 31a and the AP number detection block 31b that function as software. The wireless LAN module 50 is provided with a circuit control unit 55 for controlling the circuits 51 to 54 and a connection interface 57 with the main module 11.

  The RF circuit 51 is a circuit that performs processing corresponding to the RF circuit unit 21 in FIG. 1, a power control unit 51 a that controls transmission power related to a transmission signal, and a value detection process that relates to the power strength of the carrier of the reception signal An intensity detector 51b corresponding to the means for performing the above and a C / N detector 51c for performing a C / N ratio detection process are included. The access control circuit 52 is a portion corresponding to the Lower MAC 32 and the portion excluding the blocks 31a and 31b of the Upper MAC 31 of FIG. The CTS number detection circuit 53 is a circuit that performs processing corresponding to the CTS number detection block 31a and the like in FIG. 2, and the AP number detection circuit 54 is a circuit that performs processing corresponding to the AP number detection block 31b in FIG. It is.

  Further, the circuit control unit 55 has an internal memory 56, which stores a program, menu data, reference value data, a power table, and the like. The circuit control unit 55 classifies the level based on the detection result of the C / N ratio based on the program stored in the internal memory 56, specifies the value of the transmission power, and saves power during transmission and improves the transmission efficiency. Maintain.

  The wireless communication apparatus according to the first embodiment of the present invention is not limited to being incorporated in the portable music player 10 in the form of wireless LAN modules 20 and 50 as shown in FIGS. However, the present invention can also be applied to information processing devices such as personal computers, PDAs, and television devices, and various devices such as mobile phones and portable image display devices. The wireless communication apparatus according to the first embodiment may be configured as an independent wireless communication apparatus in addition to being incorporated in various devices and combined. For example, it may be configured in a card shape corresponding to various connection standards (PCMCIA standard, CF card standard, USB standard, IEEE 1394, etc.) and can be connected and mounted to various information processing apparatuses. Further, the wireless communication targeted by the wireless communication apparatus of the first embodiment is not limited to the wireless LAN, but for various wireless communication such as Wireless USB, UWB (Ultra Wide Band), BLUETOOTH (registered trademark), and the like. Is also applicable.

  FIG. 7 shows a power table 58 applied to a wireless LAN module (corresponding to a wireless communication device) according to the second embodiment of the present invention. The basic configuration of the wireless LAN module of the second embodiment is the same as that of the first embodiment shown in FIG. 1, but it is detected by counting the number of CTS receptions and referring to the power table 58 of FIG. The feature of the second embodiment is that the value of the transmission power is specified based on the detected number of receptions. In addition, since the substantial structure of 2nd Embodiment is equivalent to 1st Embodiment, the code | symbol equivalent to 1st Embodiment is used in the description regarding the following 2nd Embodiment.

  In the second embodiment, the memory 26 of the wireless LAN module 20 stores the power table 58 shown in FIG. 7 instead of the power table 40 shown in FIG. 4 and omits the storage of the reference value data 34. . Further, the program P stored in the memory 26 has a content for specifying the value of transmission power based on the number of CTS receptions.

  The program P used in the second embodiment is the CTS count detection block 31a of FIG. 2 and sets the number of CTS receptions received from the other radio apparatus received by the antenna 24 and the RF circuit unit 21 for a predetermined time (for example, for 30 seconds). (Time values other than 30 seconds can also be applied.) When detected, it is specified that the CPU 27 specifies the value of transmission power corresponding to the detected number of receptions using the power table 58 of FIG. ing. Further, the program P stipulates that the CPU 27 transmits an instruction to set the transmission power to the specified value to the power control unit 21a of the RF circuit unit 21 as in the first embodiment.

  Note that the power table 58 of FIG. 7 used in the second embodiment associates 10 dBm as the value of the transmission power when the number of CTSs received in 30 seconds is 0 to 5. This is because if the number of CTS is 0-5, there is almost no influence of other wireless devices that try to perform wireless communication around the place at the same time, and wireless communication is easy to perform, thus reducing power consumption. In order to give priority to the transmission power, the transmission power is reduced and the transmission power value is set to 10 dBm. The power table 58 associates 15 dBm as the transmission power value when the number of CTSs received in 30 seconds is 6 to 9. This is because if there are 6 to 9 CTS times, there are other wireless devices that are trying to perform wireless communication at the same time, and the carrier is in a slightly busy state, so the CTS signal transmitted by itself, etc. The transmission power value is increased to 15 dBm so that the transmission signal can easily reach surrounding wireless devices and access points.

  Further, the power table 58 associates 9 dBm as the transmission power value when the number of CTSs received in 30 seconds is 10 or more. This is because if the number of CTS is 10 times or more, there are many other wireless devices attempting to perform wireless communication at the same time, and the carrier is considerably busy. In order to create a situation where it is not necessary to connect to the mobile phone, the transmission power value is lowered to 9 dBm so as to reduce power consumption. Note that a large number of CTS receptions indicates that a large number of wireless devices are attempting to access one access point, and that a plurality of access points can be accessed at a place where wireless communication is attempted. , May indicate that a plurality of wireless devices are attempting to access each access point.

  As described above, in the second embodiment, by controlling the transmission power value at the time of transmission based on the number of receptions of CTS, the transmission power value is changed at any time according to the wireless communication status of other wireless devices existing in the vicinity. This can reduce power consumption during transmission and ensure efficient wireless communication. The wireless communication apparatus according to the second embodiment is the same as that of the first embodiment except for the contents described above, and thus description of other parts is omitted. Also in the second embodiment, various modifications described in the first embodiment can be applied. Furthermore, in the power table 58 of the second embodiment, the number of CTS receptions is divided into three stages, and the transmission power values are associated with each. However, the number of CTS receptions is divided into more stages, and the power table 58 is finer. It is also possible to control the transmission power value, and conversely, the transmission power value can be controlled by a simple discrimination process by dividing the number of CTS receptions into one threshold or more and less than the threshold.

  FIG. 8 shows a power table 59 applied to a wireless LAN module (corresponding to a wireless communication device) according to the third embodiment of the present invention. The basic configuration of the wireless LAN module of the third embodiment is the same as that of the first embodiment shown in FIG. 1, but the number of access points capable of wireless communication is detected, and the power table 59 in FIG. 8 is referred to. Thus, it is a feature of the third embodiment that the value of the transmission power is specified based on the detected number. In addition, since the substantial structure of 3rd Embodiment is equivalent to 1st Embodiment, the code | symbol equivalent to 1st Embodiment is used also in the description regarding the following 3rd Embodiment.

  The wireless LAN module 20 of the third embodiment has a configuration in which the power table 58 of FIG. 8 is stored in the memory 26 instead of the power table 40 of FIG. 4 and the storage of the reference value data 34 is omitted. The program P stored in the memory 26 has a content for specifying the value of transmission power based on the number of available access points.

  The program P used in the third embodiment is based on the SSID included in the beacon signal received by the antenna 24 and the RF circuit unit 21, and the AP number detection block 31b shown in FIG. When it is detected, the CPU 27 stipulates that the value of the transmission power corresponding to the detected number of access points (number of APs) is specified as a value specifying means using the power table 59 of FIG. Further, the program P stipulates that the CPU 27 transmits an instruction to set the transmission power value to the specified value to the power control unit 21 of the RF circuit unit 21 as in the first embodiment.

  The power table 59 of FIG. 8 used in the third embodiment associates 15 dBm as the value of the transmission power when the number of detected access points is one. In this case, if there is one access point that can be used, wireless communication must be performed using that access point, so the transmission power value is set to the maximum value (15 dBm). Further, the power table 59 associates 13 dBm as the transmission power value when the number of available access points is two. This is based on the idea that if there are two access points available, one of the access points can be used even if the transmission power value is lowered. Therefore, the number of access points is one. 13 dBm, which is lower than 15 dBm corresponding to the case.

  Furthermore, the power table 59 associates 12 dBm as the transmission power value when the number of available access points is three or more. This is based on the idea that if there are three or more access points that can be used, one of them is likely to be available when performing wireless communication. Is set to 12 dBm, which is further lower than 13 dBm corresponding to the case of two. Note that when the number of available access points is 0, wireless communication at a normal level cannot be performed, so that it is specified that transmission is performed again with a default transmission power value (for example, 15 dBm) by processing of the program P. ing.

  As described above, in the third embodiment, transmission is performed according to the number of access points that can be used in a place where wireless communication is performed by controlling the transmission power value at the time of transmission based on the number of available access points. The power value is changed as needed to reduce power consumption during transmission and ensure efficient wireless communication. The wireless communication apparatus according to the third embodiment is the same as that of the first embodiment except for the contents described above, and thus the description of other parts is omitted. Also in the third embodiment, the various modifications described in the first embodiment can be applied. Furthermore, also in the power table 59 of the third embodiment, the number of access points associated with transmission power values can be increased or decreased as appropriate.

  FIG. 9 shows a power table 60 applied to a wireless LAN module (corresponding to a wireless communication device) according to the fourth embodiment of the present invention. The basic configuration of the wireless LAN module of the fourth embodiment is the same as that of the first embodiment shown in FIG. 1, but the transmission power is controlled based on a plurality of factors that affect the state of wireless communication. It is a feature. Specifically, in the fourth embodiment, based on the C / N ratio detection result and the detection result of the CTS count number (CTS count) received in a certain time (for example, a required time of about 3 to 40 seconds), The transmission power value is specified. In the fourth embodiment, the substantial configuration of the wireless communication device is the same as that of the first embodiment, and therefore, the same reference numerals as those of the first embodiment are used in the following description of the fourth embodiment.

  The wireless LAN module 20 of the fourth embodiment stores the power table 60 of FIG. 9 in the memory 26 instead of the power table 40 of FIG. 4 and newly receives the number of CTS receptions in a certain time (for example, 30 seconds). The threshold value (for example, the value is 6) is stored. Further, the program P stored in the memory 26 has a content for specifying the value of transmission power based on the detected C / N ratio and the number of CTS receptions.

  The program P of the fourth embodiment stipulates that the CPU 27 performs level determination processing similar to that of the first embodiment for the C / N ratio, and the CTS count detection block for processing of the number of CTS receptions. It is defined that the number of receptions within a predetermined time detected at 31a is compared with a threshold value stored in the memory 26 to determine whether or not it is equal to or greater than the threshold value. Further, for each level result determined based on the detection result of the C / N ratio, the program P determines the discrimination based on the threshold value based on the number of CTSs by the CPU 27, and sets the transmission power value corresponding to the discriminated result in the power table 60 of FIG. It is specified that it is specified with reference to. The specified transmission power value is transmitted to the power control unit 21a by the CPU 27 as in the above embodiments.

  The power table 60 distinguishes whether the detected number of received CTSs is greater than or less than a threshold for each of the first to fourth levels determined according to the detection result of the C / N ratio. Are associated with two types of transmission power values for each level.

  Specifically, in the first level where the wireless LAN environment is “good”, when the number of CTS receptions is equal to or greater than the threshold, the transmission power is associated with a numerical value of 12 dBm, and the number of CTS receptions is the threshold at the first level. If it is less than 11, 11 dBm is associated. Also, in the second level where the wireless LAN environment is “medium”, when the number of CTS receptions is equal to or greater than the threshold, 14 dBm is associated as the transmission power, and the number of CTS receptions is less than the threshold in the second level. In this case, 13 dBm is associated.

  Furthermore, in the third level where the wireless LAN environment is “bad”, when the number of CTS receptions is equal to or greater than the threshold, 15 dBm is associated as the transmission power, and the number of CTS receptions is less than the threshold in the third level. In this case, 14 dBm is associated. Furthermore, in the fourth level where the wireless LAN environment is “communication limit”, 9 dBm is associated regardless of whether the number of CTS receptions is greater than or less than the threshold and less than the threshold. The numerical values of the transmission power in these power tables 60 are merely examples as in the first embodiment, and other numerical values can of course be applied.

  In the power table 60 of FIG. 9, the value of the transmission power is set based on the idea that is basically equivalent to the above-described embodiments. For example, when the number of CTS receptions is less than the threshold value at the first level, the C / N ratio is good, and there are few other wireless devices that try to perform wireless communication in the surrounding area. Therefore, the lower 11 dBm is set with priority given to the reduction of power consumption. Further, when the number of CTS receptions at the first level is equal to or greater than the threshold value, the C / N ratio is good, but there are other wireless devices that attempt to perform wireless communication around. The transmission power value is set slightly higher (12 dBm) in favor of the establishment of.

  Furthermore, when the number of CTS receptions is less than the threshold value at the second level, the C / N ratio is normal and there are few other wireless devices in the surroundings to perform wireless communication. Is set to a value of 13 dBm. Further, when the number of CTS receptions at the second level is equal to or greater than the threshold, the wireless communication status is a little bad, so the transmission power is set to be increased to avoid a decrease in communication efficiency (14 dBm).

  Furthermore, when the number of CTS receptions is less than the threshold at the third level, the overall wireless communication situation is slightly worse, so the transmission power is increased (14 dBm). In addition, when the number of CTS receptions at the third level is equal to or greater than the threshold value, the C / N ratio is poor, and there are a plurality of other wireless devices that are attempting to perform wireless communication. Since it is generally worse, it is set to increase the transmission power value to the maximum to avoid a decrease in communication efficiency as much as possible (15 dBm). At the fourth level, regardless of the number of CTS receptions, the wireless communication status is at the communication limit based on the detection result of the C / N ratio. The value is set to decrease (9 dBm).

  The wireless communication apparatus according to the fourth embodiment is the same as that of the first embodiment except for the contents described above, and the description of the other parts is omitted. Also in the fourth embodiment, the various modifications described in the first embodiment can be applied. Further, in the power table 60 of the fourth embodiment, the method of associating the transmission power values is changed by appropriately increasing or decreasing the level division based on the detection result of the C / N ratio and the case division based on the number of CTSs. It is also possible.

  In the modification of the fourth embodiment, the transmission power value is specified based not only on the combination of the C / N ratio detection result and the number of CTS receptions, but also on other combinations of factors affecting the wireless communication status. It is also possible to apply. In addition to the C / N ratio and the number of CTS receptions, factors that affect the state of wireless communication include the number of access points capable of wireless communication and the power intensity of the carrier wave of the received signal.

  The power table 61 of FIG. 10 is applied in the wireless communication apparatus of the modification of the fourth embodiment, and the transmission power value corresponding to the detection result of the C / N ratio and the number of available access points. Is set. The power table 61 is a combination of the power table 40 of FIG. 4 and the power table 59 of FIG. 8, and the value of the transmission power is different for each number of access points that can be used corresponding to each level. Is set. The transmission power value in the power table 61 is merely an example, and can be set based on the same concept as each of the embodiments described above.

  FIG. 11 shows a power table 62 applied to one wireless communication apparatus according to a modification of the fourth embodiment. This power table 62 is a table in which the value of the transmission power value is set corresponding to the detection result of the C / N ratio and the power strength (carrier strength) of the received carrier. When the power table 62 of FIG. 11 is used, it is necessary to store an intensity reference value for comparison with the power intensity of the carrier detected by the intensity detection circuit 21b in the memory 26 of FIG. Specifically, since the power table 62 is divided into four classes based on the carrier strength, the first strength reference value, the second strength reference value, and the third strength reference value having different values are stored in the memory 26. (First intensity reference value> second intensity reference value> third intensity reference value).

  Furthermore, in this modified example, the program P stored in the memory 26 also compares the above-described reference values with the power intensity detected by the intensity detection circuit 21b by the CPU 27 corresponding to the intensity comparison unit, thereby obtaining the carrier intensity. It is specified that the classification will be performed. Specifically, if the detected carrier strength is equal to or greater than the first strength reference value, the CPU 27 determines that the carrier strength is strong and the wireless communication status is good, and the CPU 27 determines the first class. On the other hand, when the detected carrier strength is equal to or greater than the second strength reference value and less than the first strength reference value, the CPU 27 determines that the state is a normal wireless communication state and is the second class. Furthermore, when the detected carrier strength is equal to or greater than the third strength reference value and less than the second strength reference value, the CPU 27 determines that the wireless communication status is slightly worse and is the third class. Furthermore, when the detected carrier strength is less than the third strength reference value, the CPU 27 determines that the wireless communication situation is bad and determines that it is the fourth class. Note that the carrier strength and the C / N ratio are related to some extent, and the classification related to the carrier strength and the level classification related to the C / N ratio can be understood as substantially equivalent meanings. That is, it can be understood that the first class is a wireless communication situation equivalent to the first level. Hereinafter, the second class is equivalent to the second level, the third class is equivalent to the third level, and the fourth class is the fourth level. It can be grasped as a situation equivalent to the level.

  Therefore, when the power table 62 of FIG. 11 is used, the CPU 27 classifies the current wireless communication status by the classification based on the carrier strength described above for each level determined corresponding to the detection result of the C / N ratio. The CPU 27 performs processing for specifying the value of the transmission power corresponding to the classified wireless communication status with reference to the power table 62. Note that the power table 62 in FIG. 11 is set so that the transmission power value becomes smaller for the better level of each class corresponding to each level except for the fourth level. Regardless of whether the power table 40 of FIG. 4 of the first embodiment is set to 9 dBm. Further, these contents are merely examples, and the table contents can be appropriately changed according to the device specifications to be applied.

  Furthermore, FIG. 12 shows a power table 63 applied to one wireless communication apparatus according to a modification of the fourth embodiment. This power table 63 is a table in which the value of the transmission power value is set corresponding to the detection result of the C / N ratio, the number of CTSs received within the required time, and the number of access points (number of APs). Specifically, the content is a combination of the power table 60 of FIG. 9 and the power table 61 of FIG. That is, the power table 63 is divided into the number of CTS receptions for each level based on the C / N ratio, which is divided into a threshold value and less than the threshold value, and the number of access points that can be used for each division divided by the threshold value. The value of the transmission power corresponding to is set. Note that the transmission power values in the power table 63 are only examples, and specific values can be appropriately changed based on the same idea as the above-described embodiments (the same applies to the power tables 64-66 and the like listed below). . Therefore, by using the power table 63 of FIG. 12, fine transmission power control can be performed in accordance with the wireless communication status determined by a total of three factors such as the C / N ratio, the number of CTS receptions, and the number of access points. .

  FIG. 13 shows a power table 64 applied to one wireless communication apparatus according to a modification of the fourth embodiment. In this power table 64, the value of the transmission power value is set corresponding to the detection result of the C / N ratio, the number of CTSs received within the required time, and the carrier strength. 11 power tables 62 are combined. In other words, the power table 64 is divided into the number of CTS receptions for each level based on the C / N ratio and is divided into a threshold value and a threshold value that are less than the threshold value. The transmission power value corresponding to each class is set. Therefore, by using the power table 64 of FIG. 13, fine transmission power control can be performed in accordance with the wireless communication status determined by a total of three factors including the C / N ratio, the number of CTS receptions, and the carrier strength.

  FIG. 14 shows a power table 65 applied to a wireless communication apparatus that is one of the modifications of the fourth embodiment. This power table 65 is a table in which the value of the transmission power value is set corresponding to the detection result of the C / N ratio, the number of access points, and the carrier strength. The power table 61 in FIG. 10 and the power table 62 in FIG. It is the content that combines. That is, the power table 65 performs classification according to the number of access points for each level based on the C / N ratio, and each class based on the carrier strength is assigned corresponding to each classification, and according to each class. The transmission power value is set. Therefore, by using the power table 65 of FIG. 14, fine transmission power control can be performed in accordance with the wireless communication status determined by a total of three factors such as C / N ratio, number of access points, and carrier strength.

  FIG. 15 shows a power table 66 applied to a wireless communication apparatus that is one of the modifications of the fourth embodiment. This power table 66 is a table in which transmission power values are set corresponding to the detection result of the C / N ratio, the number of CTS receptions within the required time, the number of access points, and the carrier strength. The table 60, the power table 61 in FIG. 10, and the power table 62 in FIG. 11 are just combined. In other words, the power table 66 performs classification according to the threshold value based on the number of CTS receptions for each level based on the C / N ratio, and performs further classification according to the number of access points for each classification. Corresponding to each class, each class based on carrier strength is assigned, and a value of transmission power corresponding to each class is set. Therefore, by using the power table 66 of FIG. 15, in response to the detailed wireless communication situation determined by a total of four factors such as C / N ratio, number of CTS receptions, number of access points, and carrier strength, Fine transmission power control can be performed.

  In the fourth embodiment, power tables other than those described above can also be applied as modified examples. For example, the number of CTS receptions and the number of access points are combined, and the value of transmission power is set corresponding to them. Combining the contents, the number of CTS receptions and the carrier strength, and setting the transmission power value corresponding to them, combining the number of CTS receptions, the number of access points and the carrier strength, Corresponding contents in which the value of the transmission power is set correspondingly, and the contents of setting the value of the transmission power corresponding to the number of access points combined with the carrier strength are conceivable. Also in these power tables, it is possible to control transmission power appropriately according to the actual wireless communication status, thereby reducing power consumption and ensuring efficient wireless communication.

It is a block diagram which shows the main internal structures of the portable music reproducing apparatus incorporating the wireless LAN module which concerns on 1st Embodiment of this invention. It is a block diagram showing the content which CPU functions as a MAC layer. (A) is a graph which shows the level of the transmission side and reception side with respect to each subcarrier on a frequency axis, (b) is a graph which shows the waveform of the transmission side and reception side with respect to the subcarrier on a time axis. . It is a graph which shows the electric power table of 1st Embodiment. (A) is a graph which shows the control condition of the transmission power with progress of time, (b) is a chart which shows the power consumption value in the wireless LAN module with respect to a transmission power value. It is a block diagram which shows the main internal structures of the wireless LAN module which concerns on the modification of 1st Embodiment. It is a graph which shows the electric power table used for the wireless LAN module of 2nd Embodiment of this invention. It is a graph which shows the electric power table used for the wireless LAN module of 3rd Embodiment of this invention. It is a chart which shows the electric power table used for the wireless LAN module of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention. It is a chart which shows the electric power table used for one wireless LAN module of the modification of 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Portable music player 20 Wireless LAN module 21 RF circuit part 21a Power control part 21b Strength detection circuit 21c C / N detection circuit 25 MAC processing part 26 Memory 27 CPU
31 UpperMAC
31a CTS count detection block 31b AP count detection block 32 LowerMAC
34 reference value data 34a first reference value 34b second reference value 34c third reference value 40, 58 to 66 power table P program

Claims (8)

In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the number of reception preparation completion signals, a table in which transmission power values are associated,
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
A value specifying means for specifying a value of transmission power according to the number detected by the signal number detecting means from the table ;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the level related to noise and the number of reception preparation completion signals, a table in which transmission power values are associated,
Noise component detection means for detecting a value related to a noise component included in a carrier wave of a received signal;
Noise comparison means for comparing the detection result detected by the noise component detection means with a noise reference value;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Value specifying means for specifying from the table a level related to noise determined from the comparison result of the noise comparing means and a value of transmission power according to the number detected by the signal number detecting means;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the number of wireless communication relay devices and the number of reception preparation completion signals, a table that associates transmission power values,
Relay device detecting means for detecting the number of wireless communication relay devices capable of wireless communication;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Value specifying means for specifying from the table a value of transmission power corresponding to the number detected by the relay device detecting means and the number detected by the signal number detecting means;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the level related to noise, the number of wireless communication relay devices, and the number of reception preparation completion signals, a table in which transmission power values are associated,
Noise component detection means for detecting a value related to a noise component included in a carrier wave of a received signal;
Noise comparison means for comparing the detection result detected by the noise component detection means with a noise reference value;
Relay device detecting means for detecting the number of wireless communication relay devices capable of wireless communication;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
A value that specifies from the table the level related to noise determined from the comparison result of the noise comparison unit, the number detected by the relay device detection unit, and the value of transmission power according to the number detected by the signal number detection unit Specific means,
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the class related to the number of reception preparation completion signals and the power intensity of the carrier wave, a table in which transmission power values are associated,
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Intensity detecting means for detecting the power intensity of the carrier wave of the received signal;
Intensity comparison means for comparing the detection result detected by the intensity detection means with an intensity reference value;
A value specifying means for specifying from the table a value of transmission power according to a class related to the power intensity of a carrier determined from the number detected by the signal number detecting means and the comparison result of the intensity comparing means ;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
A table in which transmission power values are associated with each other in accordance with a level relating to noise, a number of reception ready signals and a class relating to power intensity of a carrier wave,
Noise component detection means for detecting a value related to a noise component included in a carrier wave of a received signal;
Noise comparison means for comparing the detection result detected by the noise component detection means with a noise reference value;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Intensity detecting means for detecting the power intensity of the carrier wave of the received signal;
Intensity comparison means for comparing the detection result detected by the intensity detection means with an intensity reference value;
Transmission level according to the class related to the level related to the noise determined from the comparison result of the noise comparison unit, the number detected by the signal number detection unit , and the power intensity of the carrier wave determined from the comparison result of the strength comparison unit Value specifying means for specifying the value of the table from the table ;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
A table in which transmission power values are associated according to the number of wireless communication relay devices, the number of reception preparation completion signals, and the class related to the power strength of a carrier wave,
Relay device detecting means for detecting the number of wireless communication relay devices capable of wireless communication;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Intensity detecting means for detecting the power intensity of the carrier wave of the received signal;
Intensity comparison means for comparing the detection result detected by the intensity detection means with an intensity reference value;
Number by the relay device detection unit detects the number of detected said signal number detecting means, and the value of the transmission power corresponding to the class according to the power strength of the carrier is determined from the comparison result of the intensity comparison means from said table A value identification means to identify;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means. In a wireless communication device that performs wireless communication with a wireless communication relay device,
According to the level related to noise, the number of wireless communication relay devices, the number of reception preparation completion signals, and the class related to the power strength of the carrier wave, a table in which transmission power values are associated,
Noise component detection means for detecting a value related to a noise component included in a carrier wave of a received signal;
Noise comparison means for comparing the detection result detected by the noise component detection means with a noise reference value;
Relay device detecting means for detecting the number of wireless communication relay devices capable of wireless communication;
Signal receiving means for receiving a reception preparation completion signal transmitted by another wireless device;
Signal number detecting means for detecting the number of reception preparation completion signals received by the signal receiving means;
Intensity detecting means for detecting the power intensity of the carrier wave of the received signal;
Intensity comparison means for comparing the detection result detected by the intensity detection means with an intensity reference value;
The level of noise determined from the comparison result of the noise comparison means, the number detected by the relay device detection means, the number detected by the signal number detection means , and the carrier wave determined from the comparison result of the intensity comparison means Value specifying means for specifying a value of transmission power according to a class relating to power intensity from the table ;
Transmission power control means for controlling a transmission power value so as to have a value specified by the value specifying means.

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