JP2005341415A - Communication channel selection method, wireless communication device, program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue to occupy a communication channel almost in a monopoly state for a relatively long period of time (for example, while playing back video) such as communication of data requiring bandwidth guarantee (video data etc.). Even when the communication is performed on another communication channel and when the communication is performed on the used channel, a communication channel suitable for communication using the used channel is selected.
A noise information update processing unit 22 updates noise information stored in a radio wave intensity / channel storage unit 21 and indicating a steady radio wave intensity level of each empty channel. On the other hand, the use channel determination unit 41 of the use channel selection processing unit 23 selects use channel candidates based on the use status of each channel, and if there are a plurality of selected candidates, informs the comparison unit 42. The noise information of each channel is compared, and the channel to be used is determined based on the comparison result.
[Selection] Figure 1

Description

  The present invention relates to a communication channel determination method for selecting a use channel as a communication channel to be used for communication from among a plurality of communication channels, a radio communication apparatus using the same, a program thereof, and a recording medium recording the program It is about.

  In recent years, wireless LANs that construct a local area network (LAN) by communication via a wireless transmission path are becoming widespread, and devices for that purpose are being commercialized and popularized mainly in the market. Examples of the wireless LAN standard include IEEE (American Institute of Electrical and Electronics Engineers) 802.11b, IEEE 802.11g, which uses the 2.4 GHz band, and IEEE 802.11a, which uses the 5.2 GHz band. Normally, in the case of a wireless LAN that complies with these radio frequency bands and wireless communication standards, the wireless channel is subject to media access control called CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance). The wireless access point and the wireless clients such as a large number of wireless clients are sequentially used while being shared.

  Here, since communication such as data transmission between wireless communication devices is intermittent, the channel is transferred to communication between other wireless communication devices after intensively transmitting and receiving data in a short time. Therefore, even if the base of the radio spectrum of the channel used for communication leaks to the adjacent channel, it affects the communication between other radio communication devices performed on the adjacent channel as noise, and the carrier pair Even if the noise ratio is deteriorated and the communication state between the wireless communication devices of adjacent channels is deteriorated, the deterioration only occurs intermittently, and thereafter, the carrier-to-noise ratio in the adjacent channel at the time when communication is finished. Returns to a good state, and communication on the adjacent channel returns to a good state.

As described above, in the wireless LAN, when adjacent wireless channels are used at the same time, leakage to the adjacent channel of the wireless spectrum occurs at that moment, so that the carrier-to-noise ratio deteriorates in each channel, and the communication error rate As a result, the effective throughput of wireless communication within a certain period of time decreases. However, this decrease in effective throughput is intermittent and is not a major problem because it continues to function as a wireless LAN. In order to prevent leakage to adjacent channels, for example, in Patent Document 1 described later, leakage is prevented by filtering.
JP2003-347946 (release date: December 5, 2003)

  However, in the above-described conventional configuration, if data that requires QoS guarantee (Quality Of Service: service quality) is to be transmitted, QoS cannot be guaranteed due to deterioration of communication quality due to the influence of leakage from adjacent channels. In order to secure a necessary amount of carrier-to-noise ratio, there is a possibility that the communication area where communication quality can be maintained becomes narrow. The data requiring QoS guarantee includes, for example, high-definition video or audio data in the home or office.

  More specifically, for example, in order to perform HDTV video transmission wirelessly, a wireless communication device that implements a band securing standard as an upper layer is developed, and when the wireless communication device appears on the market, the wireless communication device is wireless for a long time. It is predicted that the QoS of video transmission will be secured by using the channel in a form almost monopoly.

  When performing such communication, the wireless communication device needs to repeat the required amount of data transmission within a predetermined time until transmission of the entire data is completed (for example, until video transmission is completed). Therefore, it is desirable to use an empty channel that can secure a sufficient carrier-to-noise ratio as a communication channel throughout this period.

  On the other hand, if such communication has already been performed, the bottom part of the transmission spectrum waveform continues to leak to the adjacent channel until the end of transmission of the entire data. In other words, in this case, the carrier-to-noise ratio in the adjacent channel may be deteriorated throughout. In this case, the communication state in the adjacent channel is almost always deteriorated, and even if the wireless LAN is connected in the adjacent channel, the effective throughput is extremely poor, and wireless transmission for securing the band is also performed in the adjacent channel. In this case, there is a high possibility that a desired communication state cannot be obtained.

  The present invention has been made in view of the above-mentioned problems, and its purpose is to reproduce a relatively long period of time (for example, playing back video, for example, communication of data (video data, etc.) requiring bandwidth guarantee. Use channel even if communication that continues to occupy the communication channel in a state of almost monopoly is performed on another communication channel and when the communication is performed on the use channel. The present invention provides a communication channel determination method capable of selecting a communication channel suitable for communication using the communication method, a wireless communication device using the communication channel, a program thereof, and a recording medium on which the program is recorded.

  In order to solve the above-described problem, a communication channel selection method according to the present invention includes a communication channel determination step of selecting a use channel as a communication channel to be used for communication from a plurality of communication channels. In the selection method, the communication channel determination step includes selecting a candidate for the use channel based on the use status of the plurality of communication channels, and selecting a plurality of candidates in the selection step. And a determination step of determining which of the candidates is to be used based on the detection result of the steady noise amount of each vacant channel that has become a candidate. Note that examples of the steady noise amount detection result include a plurality of noise amount measurement results.

  According to this configuration, the channel to be used can be determined based on the detection result of the steady noise amount of a plurality of empty channels. Therefore, it is possible to determine an appropriate use channel as compared with the configuration in which the use channel is determined without referring to the stationary noise amount detection result of the empty channel.

  For example, if a free channel with the smallest noise amount detection result is used, a free channel with the smallest steady noise amount and the most reliable data transmission can be used. Further, if a free channel whose noise amount detection result is lower than the threshold value is used, a free channel satisfying a desired effective throughput with a steady noise amount equal to or lower than a predetermined level can be used.

  Further, in the above determination step, the channel to be used is determined based on the detection result of the steady noise amount of each vacant channel that is a candidate. For example, data (such as video data) requiring bandwidth guarantee is determined. When communication that continues to occupy the communication channel almost in a monopoly state is performed on another communication channel for a relatively long period of time (for example, during video playback), etc. Even when the communication is performed using a channel, a communication channel suitable for communication using the used channel can be selected.

  In addition to the above-described configuration, the determination step may determine a communication channel having the smallest stationary noise amount detection result as the used channel among the candidate empty channels.

  According to this configuration, it is possible to use a vacant channel that has the least amount of steady noise and can transmit data most reliably. As a result, data can be transmitted more reliably. For example, when data (such as video data) requiring bandwidth guarantee is transmitted, if data communication is not repeated at predetermined time intervals, correct data processing ( This is particularly suitable for transmitting data that cannot be reproduced).

  Further, in addition to the above-described configuration, the selection step may include the vacant channel as a candidate when there is a vacant channel in which adjacent channels that are not used exist on both sides among the vacant channels in the plurality of communication channels. A first selection step of selecting a communication channel that includes a channel and does not include an unused channel that is not used on both sides may be included.

  Here, when communication using a certain communication channel is performed, control is performed by, for example, a transmission spectrum mask so that the amount does not affect communication using an adjacent communication channel (adjacent channel). However, transmission power due to communication on the communication channel leaks to the adjacent channel. Therefore, if a channel adjacent to a communication channel in which communication is performed is used, the carrier-to-noise ratio is reduced by the amount of leakage of the transmission power, and for example, the necessary carrier-to-noise ratio CNR can be secured. The wireless transmission distance becomes short and the wireless transmission area is reduced. On the other hand, if all the empty channels are selected as candidates, there is a possibility that the time and the amount of calculation required for determining the channel to be used among them will increase.

  On the other hand, in the above configuration, in the first selection step, when there are empty channels in which adjacent channels that are not used exist on both sides in the empty channels of the plurality of communication channels, When a communication channel that does not include an empty channel that includes the empty channel and does not include unused channels on both sides is selected, for example, in the case of a plurality of channels, the use channel is determined by the above determination step, In the case of singular, the candidate can be selected as a use channel. As a result, a free channel that does not cause a decrease in the carrier-to-noise ratio due to leakage from the communication channel to the adjacent channel (a free channel in which adjacent unused channels exist on both sides) is preferentially selected as a used channel. Can do. As a result, it is possible to determine the channel to be used in a shorter time compared to the configuration in which all the empty channels are to be compared, and to determine an idle channel with a relatively high probability and a low steady noise level as the used channel. it can.

  Further, in addition to the above configuration, the selection step is performed when a candidate is not found in the first selection step, and a second selection step of selecting an empty channel among the plurality of communication channels as a candidate is performed. May be included.

  In this configuration, if candidates are not found in the first selection process, candidates are selected in the second selection process, so even if there are no unused adjacent channels on both sides, A communication channel suitable for communication using the used channel can be selected.

  Further, in addition to the above configuration, a detection step of detecting a steady noise amount of the communication channel is included, and the determination step includes each of the candidates of the communication channel noise amount detected in the detection step. While determining the channel to be used based on the detection result of the steady noise amount of the empty channel, the detection step measures the noise amount of the communication channel a plurality of times at predetermined intervals. The steady noise amount of the communication channel may be detected.

  In this configuration, since the steady noise amount of the communication channel is detected by measuring the noise amount of the communication channel a plurality of times at predetermined intervals, intermittent communication in other communication channels is performed. Even if leakage occurs from the device, the influence of noise fluctuation caused by the leakage can be suppressed as much as possible. For example, even if the noise amount of a certain channel temporarily increases due to the influence of a device that intermittently transmits data, the channel to be used can be determined ignoring the increase in the noise amount. As a result, the used channel can be determined more appropriately.

  Further, in addition to the above configuration, when there is no communication channel that is already used, a communication channel that is one inner than the communication channel arranged at one end among the frequency bands assigned to the entire plurality of communication channels. May be included as a use channel.

  In this configuration, when there is no communication channel that is already used, the one inner communication channel is determined as the use channel, so there is another communication system that performs communication in a frequency band adjacent to the frequency band. Even in this case, a communication channel that is not easily affected by the other communication system can be determined as a use channel.

  In order to solve the above problems, the wireless communication device according to the present invention is a wireless communication device having channel determining means for selecting a communication channel to be used for communication from a plurality of communication channels. Detecting means capable of detecting a steady noise amount, and the communication channel determining means selects candidates for the use channel based on the use status of the plurality of communication channels, and a plurality of candidates are selected. In this case, it is characterized in that which of the candidates is used as a channel to be used is determined based on the steady noise amount of each of the candidate empty channels detected by the detection means.

  In this configuration, the use channel candidates are selected based on the use status of the plurality of communication channels, and when a plurality of candidates are selected, the steady noise amount of each empty channel as the candidate Based on the above, it is determined which of the above candidates is to be used.

  Therefore, unlike the above communication channel selection method, unlike the configuration in which the channel to be used is determined without referring to the detection result of the steady noise amount of the empty channel, the communication that continues to occupy the communication channel almost in a monopoly state is not possible. Even when the communication is performed using another communication channel and when the communication is performed using the use channel, a communication channel suitable for communication using the use channel can be selected without any problem.

  In addition to the above-described configuration, the communication channel determination unit may determine a communication channel having the smallest stationary noise amount detection result as the use channel among the candidate empty channels. .

  According to this configuration, it is possible to use a vacant channel that has the least amount of steady noise and can transmit data most reliably. As a result, data can be transmitted more reliably. For example, when data (such as video data) requiring bandwidth guarantee is transmitted, if data communication is not repeated at predetermined time intervals, correct data processing ( This is particularly suitable for transmitting data that cannot be reproduced).

  Further, in addition to the above configuration, when the communication channel determination means includes an empty channel in which adjacent channels that are not used exist on both sides among the empty channels in the plurality of communication channels, A communication channel that includes the empty channel and does not include an empty channel in which adjacent unused channels do not exist on both sides may be selected.

  In this configuration, a communication channel that includes the empty channel and does not include an unused channel that does not exist on both sides is selected as a candidate, so that it is the same as the communication channel selection method including the first selection step. In addition, it is possible to determine the use channel in a shorter time as compared with the configuration in which all the empty channels are compared, and it is possible to determine the empty channel having a low steady noise level as the use channel with a relatively high probability. .

  In addition to the above-described configuration, the communication channel determination unit may select a free channel from the plurality of communication channels as a candidate when an unused channel in which adjacent unused channels exist on both sides is not found. May be elected.

  In this configuration, when the channel is not found, an empty channel among the plurality of communication channels is selected as a candidate, and therefore, as in the communication channel selection method including the second selection step, an unused adjacent channel is selected. Even when a free channel existing on both sides is not found, a communication channel suitable for communication using the used channel can be selected from them.

  Further, in addition to the above configuration, the detection means may detect a steady noise amount of the communication channel by measuring the noise amount of the communication channel a plurality of times at predetermined intervals. Good.

  In this configuration, since the steady noise amount of the communication channel is detected by measuring the noise amount of the communication channel a plurality of times at predetermined intervals, intermittent communication in other communication channels is performed. Even if leakage occurs from the device, the influence of noise fluctuation caused by the leakage can be suppressed as much as possible. Therefore, the used channel can be determined more appropriately.

  In addition to the above-described configuration, the communication channel determination means may determine whether a communication channel arranged at one end of the frequency bands allocated to the entire plurality of communication channels when there is no communication channel already used. Alternatively, the inner communication channel may be determined as the use channel.

  In this configuration, when there is no communication channel that is already used, the one inner communication channel is determined as the use channel, so there is another communication system that performs communication in a frequency band adjacent to the frequency band. Even in this case, a communication channel that is not easily affected by the other communication system can be determined as a use channel.

  Moreover, the communication channel selection method according to the present invention includes a communication channel determination step of selecting a use channel as a communication channel to be used for communication from among a plurality of communication channels in order to solve the above problem. In the communication channel selection method, when the communication channel determination step finds an empty channel in which the adjacent channels on both sides are empty channels and an empty channel that is not so based on the usage status of the plurality of communication channels, A feature is that a free channel in which adjacent channels on both sides are free channels is selected as a use channel.

  Furthermore, in order to solve the above-described problem, the wireless communication device according to the present invention includes a channel determination unit that selects a communication channel to be used for communication from a plurality of communication channels. If a free channel whose adjacent channel on both sides is a free channel and a free channel that is not so are found based on the usage status of the plurality of communication channels, a free channel whose adjacent channel on both sides is a free channel is It is characterized by being selected as a use channel.

  Here, when communication that continues to occupy the communication channel in a nearly monopolistic state is performed on a certain communication channel, transmission power is almost always transmitted from the communication channel to a communication channel adjacent to the communication channel. There is a risk of leakage and lowering the carrier-to-noise ratio of the adjacent channel.

  On the other hand, in the above configuration, based on the usage status of the plurality of communication channels, based on the usage status of the plurality of communication channels, an empty channel whose adjacent channels on both sides are empty channels and an empty channel that is not so Is found, a free channel in which adjacent channels on both sides are free channels is selected as a use channel. Therefore, even if the communication that continues to occupy the communication channel in a state of almost monopoly is performed on another communication channel, and even when the communication is performed on the used channel, the communication channel However, there is a high possibility that the carrier-to-noise ratio is low, and a communication channel suitable for communication using the used channel can be selected.

  Note that a decrease in the carrier-to-noise ratio due to leakage of transmission power occurs particularly when each of the plurality of communication channels is a wideband communication channel, for example, in the case of communication using the OFDM modulation scheme. In this case, it can be used particularly suitably.

  By the way, the wireless communication device may be realized by hardware or may be realized by causing a computer to execute a program. Specifically, the program according to the present invention is a computer program capable of controlling detection means capable of detecting a steady noise amount of a plurality of communication channels, and is based on the use status of the plurality of communication channels. In addition, a candidate for a channel to be used for communication is selected from the plurality of communication channels, and when a plurality of candidates are selected, the stationary channels detected by the detection unit and each of the candidate free channels A program for operating the computer as communication channel determining means for determining which of the candidates is to be used based on the amount of noise, and the program is recorded on a recording medium according to the present invention. Yes.

  In addition, when selecting a communication channel to be used for communication from among a plurality of communication channels, the program according to the present invention determines that the adjacent channels on both sides are vacant channels based on the usage status of the plurality of communication channels. A program for operating a computer as channel determining means for selecting, as a use channel, a free channel whose adjacent channels on both sides are free channels when a free channel and a free channel that is not so are found, the recording according to the present invention The program is recorded on the medium.

  When these programs are executed by a computer, the computer operates as the wireless communication device. Therefore, as in the case of the wireless communication device, communication that continues to occupy the communication channel in a substantially monopolistic state is performed on another communication channel, and when the communication is performed on the use channel. However, a communication channel suitable for communication using the used channel can be selected without any problem.

  According to the present invention, when selecting a use channel as a communication channel to be used for communication from a plurality of communication channels, the use channel candidates are selected based on the use status of the plurality of communication channels, When a plurality of candidates are selected, it is determined which of the candidates is to be used based on the steady noise amount of each vacant channel that is a candidate. Therefore, even if the communication that continues to occupy the communication channel in a nearly monopolistic state is performed on another communication channel and when the communication is performed on the use channel, the use channel is not affected. A communication channel suitable for communication using a wireless communication can be selected. For example, wireless AV stream transmission and wireless IP data transmission are widely used for wireless communication, including wireless communication using a wideband wireless channel (such as OFDM modulation / demodulation). Can be used.

  An embodiment of the present invention will be described below with reference to FIGS. That is, when the wireless communication device according to the present embodiment selects a use channel as a communication channel to be used for communication from a plurality of communication channels, for example, comparison of data communication that requires bandwidth guarantee is performed. Even if communication that continues to occupy the communication channel in a state that is almost monopolistic for a long period of time is performed on another communication channel, and even when the communication is performed on the used channel, the used channel is used. A wireless communication device capable of selecting a communication channel suitable for conventional communication, for example, a wireless communication device that wirelessly communicates a wireless AV stream transmission or wireless IP data transmission using a broadband wireless channel (such as an OFDM modulation / demodulation method) For example, it is preferably used.

  Hereinafter, before describing a configuration for determining a wireless channel (hereinafter, abbreviated as a channel) to be used during wireless communication, a schematic configuration of the wireless communication device 1 will be briefly described. That is, as shown in FIG. 1, the wireless communication device 1 according to the present embodiment receives a wireless signal transmitted through a wireless transmission path and converts a signal of a specific channel therein into a baseband signal. A receiving radio frequency processing unit 2 that outputs the baseband signal, a baseband demodulator 3 that demodulates the baseband signal to generate a digital signal, and a digital signal processing unit 4 that processes the digital signal from the baseband demodulator 3 And a control unit 5 that controls the entire radio communication device 1 including a process of instructing the reception radio frequency processing unit 2 to specify a specific channel.

  As will be described in detail later, any member may be realized only by a hardware circuit, or a combination of a hardware circuit, a calculation means such as a CPU for controlling the hardware circuit, and a program for that purpose. In the wireless communication device 1 according to the present embodiment, the reception radio frequency processing unit 2 and the baseband demodulator 3, and a baseband modulator 6 and a transmission radio frequency processing unit which will be described later are provided. 7 is realized by an electronic circuit such as a transmission / reception circuit and a modulation / demodulation circuit. The digital signal processing unit 4, the control unit 5, and members 21 to 23, 31 to 33, and 41 to 42 described later are stored in the CPU. Is a functional block that is realized by executing a program stored in and controlling peripheral circuits such as an input / output circuit (not shown).

  The wireless communication device 1 according to the present embodiment is a transceiver, and when the digital signal indicating the data to be transmitted by the digital signal processing unit 4 is output to the wireless communication device 1, the digital signal is transmitted. A baseband modulator 6 that modulates and outputs a baseband signal, and a transmission radio frequency processor 7 that converts the baseband signal into a radio signal of a specific channel and transmits the radio signal to a radio transmission path are provided. Yes. Further, the control unit 5 is configured to be able to instruct a specific channel to the transmission radio frequency processing unit 7.

  The wireless communication device 1 according to the present embodiment is configured to be communicable with OFDM (Orthogonal Frequency Division Multiplexing), more specifically, with IEEE (American Institute of Electrical and Electronics Engineers) standard IEEE802.11a. The baseband demodulator 3 and the baseband modulator 6 are an OFDM demodulator and an OFDM modulator. Further, both the radio frequency processing units 2 and 7 are configured to be able to process an OFDM-modulated radio signal.

  For example, as shown in FIG. 2, the reception radio frequency processing unit 2 includes a reception antenna 11 for the radio signal, an LNA (low noise amplifier) 12 for amplifying the radio signal received by the reception antenna 11, and the control. A local oscillator 13 for generating a local oscillation frequency signal having a frequency corresponding to a specific channel designated by the unit 5, a mixer 14 for mixing the local oscillation frequency signal and the output signal of the LNA 12, and an output signal of the mixer 14 An amplifier 15 that amplifies and outputs to the baseband modulator 6 is provided.

  Further, as shown in FIG. 1, the wireless communication device 1 according to the present embodiment shows a steady radio wave intensity (noise) level of each empty channel as a member for determining a channel used for communication. The radio wave intensity / channel storage unit 21 capable of storing noise information and the steady level of the radio wave intensity of each empty channel are detected, and noise information is generated based on the detection result and associated with each channel. The noise information update processing unit (detection means) 22 that stores the noise information in the radio wave intensity / channel storage unit 21 and the noise information of each empty channel stored in the radio wave intensity / channel storage unit 21 Among a plurality of free channels, a free channel with less stationary noise can be selected as a channel used for communication (hereinafter referred to as a used channel). Use the channel selection processing unit and the (channel determining means) 23 is provided. The stationary noise includes, for example, noise that has no noise disappearance period during the detection period that is equal to or longer than the SIFS interval (16 μsec) of the wireless LAN.

  The radio wave intensity / channel storage unit 21 according to the present embodiment stores, for example, the latest predetermined number of noise levels among the noise levels of the vacant channel repeatedly detected as noise information. In the present embodiment, the noise information of each channel is associated with each channel by storing the combination of the noise information and information indicating the empty channel (channel information) in the radio wave intensity / channel storage unit 21. ing. In addition, as the measurement by the noise information update processing unit 22 a plurality of times, for example, measurement of about 500 microseconds at intervals of 16 μs (measurement of 100 to 150 symbol periods at a physical rate of 36 Mbps in accordance with the IEEE802.11a standard; 1 Symbol length = 4 μsec).

  On the other hand, the used channel selection processing unit 23 refers to a plurality of times of noise levels corresponding to empty channels. For example, the used channel selection processing unit 23 determines a steady noise level from a plurality of times of noise levels. The steady noise level of each empty channel is determined by calculating a predetermined function. Examples of the function include addition and averaging. When calculating, each noise level may be determined with the same weight, or a weight may be given according to the time of measurement or the difference from other noise levels.

  Further, the function may be a function that counts the number of noise levels exceeding a predetermined level and generates an output in accordance with the number. For example, a channel whose noise level has been high multiple times may be output when the steady noise level is high, and may be output when the steady noise level is low otherwise. In this case, the used channel selection processing unit 23 determines that leakage from other channels is always occurring for a channel whose noise level is high several times, and can determine that the steady noise level is high. On the other hand, for channels that are not, leakage from other channels does not always occur, and it can be determined that the steady noise level is low.

  As a result, even if the noise amount of a certain channel temporarily increases due to the influence of a device that intermittently sends data, it is possible to determine the steady noise level while ignoring the temporary noise amount fluctuation.

  Here, if data communication on an intermittent wireless LAN within a short time is performed on an adjacent channel, the base of the transmission spectrum used for the data communication is intermittently used for a short time. To leak. However, in this case, even if the reception error rate is intermittently increased, wireless video transmission is not affected as long as it is within a range that can be covered by retransmission and QoS can be maintained.

  Therefore, it is possible to determine the steady noise level while ignoring the fluctuation of the temporary noise amount. In this case, intermittent data transmission is performed when the noise level of a certain communication channel is detected. It is possible to prevent the noise level leaked from the adjacent channel from being caught and erroneously determining that the steady noise level of the communication channel is high.

  The noise information update processing unit 22 according to the present embodiment includes a frequency control unit 31 that instructs the reception radio frequency processing unit 2 to sequentially receive each vacant channel, and the reception radio frequency processing unit 2. A reception level detector 32 that detects a level of a baseband signal to be output and detects a radio wave intensity of a channel (specific channel) selected by the reception radio frequency processing unit 2; and the reception level detector 32 Based on the detected radio field intensity, out of the noise information of each empty channel stored in the radio field intensity / channel storage unit 21, the noise information of the channel currently selected by the receiving radio frequency processing unit 2 is obtained. And a write processing unit 33 for updating. The radio wave intensity includes, for example, leakage at the base of the transmission spectrum of the adjacent channel and other disturbance noise in the propagation path.

  More specifically, as described above, in the present embodiment, since the noise information and the channel are associated with each other by a combination of the noise information and the channel information, the write processing unit 33 includes the radio wave intensity / channel storage unit 21. Are extracted from the combinations stored in the channel information including the channel information currently selected by the receiving radio frequency processing unit 2, and the noise information included in the combinations is updated. Noise information. In the present embodiment, since the latest predetermined number of noise levels are stored as noise information, the write processing unit 33 sets the oldest noise level among the noise information specified as the update target. Instead, the level of the radio wave intensity detected by the reception level detector 32 is written. When determining the oldest noise level, the write processing unit 33 stores, for example, a combination of each noise level and information indicating the newness (such as the acquisition time and the order of writing) and compares them. Alternatively, each noise level may be stored in the order of newness, and the newness may be determined based on the stored order (position on the list, position on the address, etc.).

  On the other hand, in the used channel selection processing unit 23 according to the present embodiment, for example, based on the usage status of each channel, the candidate for the above used channel is selected. The used channel determination unit 41 is determined. Furthermore, the use channel selection processing unit 23 according to the present embodiment is provided with a comparison unit 42 that reads out noise information of each channel to be compared from the radio wave intensity / channel storage unit 21 and compares the noise information. In the case where there are a plurality of selected candidates, the used channel determination unit 41 informs the comparison unit 42 of these candidate channels as comparison targets, and compares the noise information of each channel, and also compares the comparison results. The channel to be used can be determined based on

  Furthermore, when there are a plurality of candidates, the used channel selection processing unit 23 according to the present embodiment is configured to determine the channel with the smallest stationary noise as the used channel among them, The comparison unit 42 uses the channel associated with the noise information having the minimum stationary noise level indicated by the noise information read from the radio wave intensity / channel storage unit 21 as a comparison result to the used channel determination unit 41. In response, the used channel determination unit 41 determines the channel as the used channel.

  Here, as will be described in detail later, it is sufficient that noise information is stored in the radio wave intensity / channel storage unit 21 before determining the use channel. However, in this embodiment, a request to select the use channel is made. After being received, the noise information update processing unit 22 is configured to update (acquire) the noise information of the empty channel.

  More specifically, when the use channel selection processing unit 23 according to the present embodiment is instructed to select a use channel by the control unit 5 or the like, for example, a use channel candidate is selected and a plurality of candidates are selected. In this case, for example, all candidates are notified at once, or switching to each candidate is instructed at a predetermined timing, and the frequency control unit 31 is sequentially informed of each candidate communication channel. You can direct the selection.

  As described above, the use channel selection processing unit 23 according to the present embodiment determines the use channel by comparing the steady noise levels indicated by the noise information of a plurality of channels. The possibility of determining an empty channel having a low steady noise level as a use channel is higher than that of the configuration to be performed. As a result, a wireless transmission path with higher transmission quality can be used, and data that requires QoS guarantee can be transmitted more reliably.

  In addition, the used channel determination unit 41 according to the present embodiment includes an empty channel in which both adjacent channels (upper frequency is higher and lower frequency is lower) and an empty channel in which one or both are used. In some cases, an empty channel in which both adjacent channels are empty can be given priority, and an empty channel in which both adjacent channels are empty can be compared.

  Here, in the wireless communication standard that employs the frequency division multiplexing method, in order to prevent communication between adjacent channels from interfering with each other, the transmission spectrum is regulated by a transmission spectrum mask, and each channel is connected to an adjacent channel. The amount of leakage to an adjacent channel that leaks into the channel is defined to be a predetermined value or less. However, even if the transmission spectrum mask is satisfied, the leakage to the adjacent channel is not zero. Therefore, the steady noise level in the empty channel in which one or both of the adjacent channels are used is often higher than the empty channel in which the adjacent channels are empty channels, and the channel is selected as the used channel. Less likely. As a result, when the channel is also set as a comparison target, the time required for the comparison process becomes long although the possibility of determining the channel as a use channel is low.

  On the other hand, the used channel selection processing unit 23 according to the present embodiment gives priority to a free channel in which both adjacent channels are vacant for comparison. As a result, it is possible to determine the channel to be used in a shorter time compared to the configuration in which all the empty channels are to be compared, and to determine an idle channel with a relatively high probability and a low steady noise level as the used channel. it can.

  Furthermore, when there is no empty channel in which both adjacent channels are empty, the used channel determination unit 41 according to the present embodiment can set other empty channels as comparison targets as the next best candidate. Therefore, even when there is no free channel in which both adjacent channels are free, it is possible to determine a free channel with a relatively low probability as a use channel with a relatively high probability. In addition, as the other vacant channels, the vacant channels in which one or both of the adjacent channels are used, or, among the selectable channel groups, the channels at both ends as viewed in the frequency domain (the highest frequency or , The channel with the lowest frequency).

  In addition, the used channel determination unit 41 according to the present embodiment, in the selectable channel group, when both ends of the channel group in the frequency domain are vacant channels than when the other channels are vacant channels. The priority is lowered, and if possible, other channels can be selected as candidates.

  Here, the channels at both ends are set to a frequency band of a channel group that can be used by the wireless communication device 1 by a wireless communication device that communicates with another communication method (a frequency band used in the communication method adopted by the wireless communication device 1). There are cases where adjacent frequency bands are used and other noise sources exist in the frequency band.

  However, the used channel selection processing unit 23 according to the present embodiment lowers the priority order of the channels at both ends and, if possible, uses other unused channels as the used channels. The possibility that the communication of 1 is hindered can be reduced.

  In addition, when there is no communication channel that is already used, the use channel determination unit 41 according to the present embodiment is more than the communication channel arranged at one end among the frequency bands assigned to the entire plurality of communication channels. One inner communication channel can be determined as a use channel.

  If there is no communication channel that is already used, if the used channel selection processing unit 23 can determine one of the channels as the used channel, substantially the same effect can be obtained. There is a possibility that communication of the wireless communication device 1 is hindered due to leakage from the source. Moreover, if a communication channel inside the used channel selected above is selected as the used channel, there is a possibility that the amount of calculation when searching for candidates for determining the next used channel becomes large.

  On the other hand, since the used channel selection processing unit 23 according to the present embodiment selects the communication channel as the used channel, the amount of calculation when determining the used channel this time, and the next used channel It is possible to determine, as a use channel, a communication channel that is unlikely to hinder communication of the wireless communication device 1 due to leakage from the noise source while maintaining a low calculation amount when searching for candidates when determining the.

  Here, it is only necessary to determine in advance which one of the above-mentioned communication channels to select the inner communication channel, but in the wireless communication device 1 according to the present embodiment, details will be described later. Thus, the shape of the spectrum of transmission power leaking from a certain communication channel is not vertically symmetrical in the frequency domain, and the upper adjacent channel is more likely to secure a carrier-to-noise ratio than the lower adjacent channel. Considering this, the use channel selection processing unit 23 selects, for example, a communication channel located on the upper side adjacent to the lower limit communication channel as the first communication channel.

  The operation of the use channel selection processing unit 23 at the time of use channel determination will be described as follows. That is, in step 1 shown in FIG. 3 (hereinafter abbreviated as S1), the used channel selection processing unit 23, for example, makes an inquiry to the control unit 5 to select a channel group that can be selected by the wireless communication device 1. Search for channels that are already in use.

  If the channel is not found as a result of the search (YES in S2), that is, if no channel is used, the used channel selection processing unit 23 can select the wireless communication device 1 as the used channel. A channel of the second frequency band from the lower one is selected from the lowest channel group (S3).

  On the other hand, when one of the channels is already used and the number is singular (NO in S2 and NO in S4), in S5, the used channel selection processing unit 23 uses It is confirmed whether the channel next to the adjacent channel (the next adjacent channel) can be secured on both the upper side and the lower side. If the channel used is Ch (i), the upper next adjacent channel is Ch (i + 2) and the lower next adjacent channel is Ch (i + 2). The selection processing unit 23 confirms whether these secondary adjacent channels Ch (i + 2) · Ch (i-2) exist and can be secured (free).

  If the secondary adjacent channel can be secured (YES in S5), the used channel selection processing unit 23 determines that the secondary adjacent channel Ch (i + 2) · Ch (i-2) The noise levels are compared, and the smaller one is selected as the use channel (S6). On the other hand, when there is only one next adjacent channel that can be secured (NO in S5), the used channel selection processing unit 23 selects the next adjacent channel as a used channel (S7). .

  On the other hand, when there are a plurality of channels that are already used (NO in S2 and YES in S4), the used channel selection processing unit 23 can use the wireless communication device 1 in S8. An empty channel that is more than the next adjacent channel is searched for from any of the already used channels in the channel group.

  When a plurality of such vacant channels are found (YES in both S9 and S10), the used channel selection processing unit 23 uses the channel having the lowest steady noise level among these vacant channels in S10. The channel is selected (S11). On the other hand, when only one empty channel that is more than the next adjacent channel is found in any of the used channels (YES in S9 and NO in S10) The used channel selection processing unit 23 selects the unused channel as a used channel (S12).

  On the other hand, when no free channel that is more than the next adjacent channel is found from any of the used channels (NO in S9), the used channel selection processing unit 23 sets each The steady noise levels of the empty channels are compared, and the channel with the lowest noise level is selected as the used channel (S13).

  Here, in the channel selection method of S1 to S13, data transmission in the channel is performed with high quality by setting the channel to be used as described above. Therefore, the channel selection method is already used when the channel is selected. There is no need to change the channel.

  In the above description, the operation of the used channel selection processing unit 23 is changed depending on whether one or a plurality of communication channels are already used (the determination result in S4). However, the present invention is not limited to this. If it is possible to give priority to an empty channel that has an unused adjacent channel on both sides over an empty channel that does not have an adjacent channel, for example, the processing of S4 to S7 is omitted, regardless of the number of communication channels that are already used. The same processing (the processing of S8 to S13) may be performed, and the threshold value for changing the operation may be set to a number larger than one.

  Furthermore, in S8 described above, a case has been described in which all available channels that are more than the next adjacent channel are searched from any of the already used channels among the channel groups that can be used by the wireless communication device 1. However, the search range may be limited more than this, and “a channel that is the next adjacent channel and not the adjacent channel with respect to the used radio channel” may be searched. In this case, if it is found, the channel may be a candidate. On the other hand, if it is not found, before comparing the steady noise level of all the empty channels, “If it is not the next adjacent channel to the used radio channel, It is desirable to search for “channels that are not adjacent channels”.

  Also, in the above, assuming that the wireless communication device 1 mainly communicates data that requires QoS guarantee, three or more consecutive free channels regardless of whether or not data that requires QoS guarantee is transmitted. The communication channel selection method in which the middle empty channel is preferentially used as a use channel has been described. However, the use channel selection processing unit 23 performs data communication that requires QoS guarantee and data communication that does not require QoS guarantee. Thus, the channel selection method may be switched.

  Here, as a channel selection method when transmitting data that does not require QoS guarantee, any available channel may be selected. More preferably, when data that does not require QoS guarantee is transmitted, As described above, it is possible to select a communication channel that does not reduce the number of communication channels (empty channel in the middle of three or more consecutive empty channels) suitable for data transmission requiring QoS guarantee.

  As a selection method in this case, for example, an empty channel in which an adjacent channel is used is preferentially used as a communication channel (for example, a channel for best effort communication) for transmitting data that does not require QoS guarantee. The method of selecting is mentioned.

  More specifically, a channel adjacent to a channel where a beacon is thrown from another access point (an already used channel) is a channel (a free channel) where a beacon is not thrown from another access point. If the free channel is used for best-effort communication, the next time a search is made for a communication channel for data transmission that requires QoS guarantee, a clean channel whose adjacent channel is a free channel is used. The possibility of increasing the number of options can be improved.

  Further, as another selection method, the number of communication channels suitable for transmission of data that requires the QoS guarantee, which remains when each unused channel is selected as a use channel, is compared with the number of available channels. A method of selecting as a use channel may be employed.

  According to these configurations, in the case of communication that does not require QoS guarantee, the number of communication channels suitable for data transmission requiring QoS guarantee can be maintained at a large value. Necessary data communication can be performed with higher quality.

  As described above, when the channel selection method is switched between data communication that requires QoS guarantee and data communication that does not require QoS guarantee, the selected channel determination processing unit 23 performs, for example, as follows. Thus, the switching timing can be determined.

  Specifically, when the wireless communication device 1 is a device that transmits video data, a command signal for starting wireless video transmission is transmitted from the device on the video receiving side to the device on the video source side. Therefore, the wireless communication device 1 as the video source side device or the video receiving side device triggers the recognition of the command by the video source side device, and uses the channel selection method as data that requires QoS guarantee. It is possible to switch to a communication method. In this case, for example, even when communication using a certain used channel is performed with the same communication partner for the best effort type communication, the used channel selection processing unit 23 It is desirable to reselect a use channel for data communication that requires QoS guarantee at the switching timing.

  As described above, in the wireless communication device 1 according to the present embodiment, a wireless channel that is least affected by the other wireless transmission channels is quickly searched from among a plurality of wireless channels, and the wireless channels are used for wireless video transmission. Selected and used as a radio channel.

  Specifically, the communication channel selection method in the above embodiment is a communication channel selection method in a wireless communication system that can be selected from a plurality of wideband communication channels, the step of confirming the presence or absence of a plurality of free channels, The method includes a step of comparing steady noise amounts of a plurality of idle channels and a step of selecting an idle channel with the least stationary noise as a communication channel based on the comparison.

  Further, in the present embodiment, in addition to the above-described configuration, a channel that is not occupied by adjacent channels on both sides among a plurality of empty channels is first searched, and a steady noise amount is compared among them, and a steady noise amount is compared. An empty channel with the least amount of noise is selected as a communication channel.

  Furthermore, in this embodiment, in addition to the above configuration, when a channel that is not occupied by adjacent channels on both sides among a plurality of empty channels is not found and compared, the steady noise amount of the empty channel itself is compared, An empty channel with the smallest steady noise amount is selected as a communication channel.

  In addition to the above configuration, when comparing the amount of steady noise, in order to minimize the effects of noise fluctuations caused by leakage from intermittent communication on other channels, the noise is reduced multiple times over a predetermined period. The quantity is measured and used to compare stationary noise.

  In addition to the above configuration, if it is found that there is no channel being used in the step of confirming the presence or absence of a plurality of empty channels, select the channel located on the upper side adjacent to the lower limit channel. Yes.

  In this configuration, when a new wireless video transmission is to be performed when a wireless channel is already used, the channel that the user himself / herself intends to use for communication is also vacant, and adjacent to both sides. Search for a wireless channel that is not in use. If it is found, wireless video transmission is performed using the channel.

  On the other hand, as a wireless channel, a wireless channel in which adjacent channels on both sides are unused is searched, but if it does not exist, the noise level of the empty channel itself is compared and the channel with the lowest noise level Select to use.

  Note that the noise level indicates leakage from the radio transmission transmission wave on the adjacent channel on one side or both sides, and depending on the case, the radio transmission transmission wave on the next adjacent channel on one side or both sides or a further distant channel. This includes everything that causes noise for the carrier when transmitting on that channel, such as leakage from the receiver.

  Here, when communication is performed on a certain radio channel, leakage to other radio channels (especially adjacent channels) occurs, and even if communication is performed on the adjacent channel, the carrier-to-noise ratio is determined on the adjacent channel. There is a possibility that a sufficient CNR cannot be secured.

  For example, a case where a 5.2 GHz band frequency is used will be described as an example. When using IEEE802.11a in the 5 GHz band, the bandwidth occupied by one channel is about 18 MHz, and since this is used for OFDM modulation, the adjacent channel satisfies the IEEE802.11a transmission spectrum mask specification. Leaks with a maximum intensity of -40 to -20 dBr. Therefore, when communication is performed on the adjacent channel, the carrier-to-noise ratio is not good.

  Therefore, as described above, by searching whether adjacent channels on both sides are free and searching for the noise level of the free channel, other specific channels are almost exclusively occupied and wirelessly transmitted. And whether there is an adjacent channel to the wireless transmission channel that is almost always affected by large transmission power leakage etc. from the wireless transmission of the system, and the influence from them It is possible to select a channel that reduces as much as possible.

  As a result, when a radio transmission / reception apparatus adopting the above-described radio channel selection method is used to perform transmission while ensuring QoS in most of the time zones, when performing radio transmission with a large transmission band, another radio A radio channel that is least susceptible to leakage from an already used radio channel under the condition that a radio transmission with a large transmission band is already performed on the channel, in other words, a carrier-to-noise ratio The radio channel with the highest value can be selected. As a result, it is possible to create a good wireless transmission state in which the wireless transmission distance or wireless transmission area of wireless video transmission can be increased.

  Hereinafter, as an example, leakage from other channels in the wireless communication device 1 of the IEEE802.11a standard that communicates in the 5.2 Ghz band using OFDM modulation as an example will be described with reference to FIGS. 4 to 8. This will be described in detail. That is, in the above standard, as shown in FIG. 4, the transmission spectrum mask SPM has a spectrum density in a frequency band other than the frequency band of a certain communication channel Ch (i) that is equal to the spectrum density of the communication channel Ch (i). It is set to be −40 dBr to −20 dBr on the basis of the size L (i). In the above standard, each communication channel is arranged at intervals of 20 MHz, and the frequency band other than the frequency band of the certain communication channel Ch (i) uses the center frequency fc (i) of the communication channel Ch (i). As a reference, a band of +10 MHz or more and a band of -10 MHz or less.

  Therefore, even if the transmission spectrum mask SPM is satisfied, the frequency band B (i + 1) of the upper adjacent channel Ch (i + 1) and the lower adjacent channel Ch (i-1) in the frequency domain. In the frequency band B (i−1), there is a possibility that leakage of a maximum spectral density of −20 dBr may occur on the basis of the magnitude of the spectral density of the communication channel. In the standard, each communication channel Ch (i) occupies a frequency band of about 18 MHz, and the frequency bands B (i + 1) and B (i-1) With reference to the center frequency fc (i) of Ch (i), the frequency bands are set to +11 MHz to +29 MHz and −29 MHz to −11 MHz, respectively.

  For example, SP (i) in FIG. 4 shows an example of the actual transmission spectrum of the wireless communication device 1, but the spectrum SP (i) satisfies the transmission spectrum mask SPM, while Leakage indicated by hatched areas A1 (i) and A2 (i) has occurred. In addition, the height in the figure at each frequency of each region A1 (i) · A2 (i) indicates the amount of leakage (spectrum density) at that frequency.

  As a result, when communication is performed on the adjacent channel Ch (i + 1) and Ch (i-1) when communication is performed on the communication channel Ch (i), the adjacent channel Ch (i + 1) And the carrier-to-noise ratio CNR when communicating with Ch (i-1) is lowered. As a result, when communicating on the adjacent channels Ch (i + 1) and Ch (i-1), the wireless transmission distance capable of securing the necessary carrier-to-noise ratio CNR is shortened, and the wireless transmission area is reduced. End up.

  In the transmission spectrum mask SPM, the amount of leakage from a certain communication channel Ch (i) to the adjacent channel Ch (i + 1) · Ch (i-1) is equal to the adjacent channel Ch (i + 1) · Ch (i -1) If the level of the carrier power of the signal received and the frequency of communication are as expected, the communication in the adjacent channel Ch (i + 1) and Ch (i-1) should not be hindered. Is set. However, when the carrier power is smaller than the assumed level, the carrier-to-noise ratio CNR required for normal radio transmission is set in the adjacent channel Ch (i + 1) · Ch (i-1). In some cases, the radio transmission area may be reduced because the radio transmission area cannot be secured. In addition, as the case where the carrier power becomes small, for example, when the position of the transmitter that communicates in the adjacent channel Ch (i + 1) · Ch (i-1) is located far from the position of the receiver, For example, when the transmission power from the transmitter is low or there is an obstacle between the two.

  The frequency of the communication is set so that the wireless system can function as a whole in the case where a data string that does not require QoS guarantee is intermittently transmitted. That is, it is unlikely that the transmission time point of the data string on a certain communication channel Ch (i) and the transmission time point of the data string on the adjacent channel Ch (i + 1) · Ch (i-1) overlap. At a certain moment, the adjacent channel Ch (i + 1) .Ch (i-) is leaked from the communication channel Ch (i) to the adjacent channel Ch (i + 1) .multidot.Ch (i-1) at a certain moment. Even if the transmission quality of 1) decreases, after the moment, the transmission quality of the adjacent channel Ch (i + 1) .Ch (i-1) is at the normal level (when both time points do not overlap). It is expected to return to (level). In other words, the frequency of the communication is relatively longer (for example, the time until viewing of AV data is terminated) than the frequency of occupying the communication channel Ch (i) almost in a monopoly manner. Estimated low. In addition, as described above, as a use for occupying the communication channel Ch (i) for a relatively long time almost in a monopoly manner, for example, high-definition video (for example, HDTV video) in a home or office Or the use which carries out radio | wireless communication of an audio | voice etc. is mentioned. Moreover, as a protocol occupied in this way, IEEE802.11e etc. are mentioned, for example. As in these examples, when transmitting the HDTV video, the HDTV video requires a bandwidth of 24 Mbps, and the maximum transmission rate (maximum transmission physical rate) in the physical layer of IEEE802.11a is 54 Mbps. If transmission is performed using a protocol that can secure a band to guarantee QoS, such as IEEE802.11e, the wireless channel is substantially monopolized during HDTV video transmission.

  Therefore, when data communication is performed in such a manner that the communication channel Ch (i) is occupied almost in a monopoly manner for a relatively long period of time, adjacent channels Ch (i + 1) .Ch ( Since leakage from the communication channel Ch (i) continues to occur in i-1), carrier-to-noise required for normal wireless transmission in the adjacent channel Ch (i + 1) · Ch (i-1) The period during which the specific CNR can be secured is shortened. As a result, even if the connection can be established, the effective throughput of the adjacent channels Ch (i + 1) .multidot.Ch (i-1) is greatly reduced.

  On the other hand, the used channel selection processing unit 23 according to the present embodiment uses an empty channel in which both of the adjacent channels (the upper side with the higher frequency and the lower side with the lower frequency) are vacant and one or both of them. When there is an empty channel, priority is given to an empty channel in which both of the adjacent channels are empty, and an empty channel in which both of the adjacent channels are empty is set as a candidate for use channel. For example, in FIG. 5, Ch (1) to Ch (8) are provided as communication channels in which the wireless communication device 1 can communicate, and the communication channels Ch (2) and Ch (6) are used for video transmission, for example. For the purpose of the above, the case where it is used in a state that is almost always in time is shown. In this case, the communication channel Ch (4) is selected as a candidate and transmitted to the comparison unit 42 as a comparison target. Therefore, in a shorter time compared to the configuration in which all free channels Ch (1), Ch (3), Ch (4), Ch (5), Ch (7), and Ch (8) are compared. In addition, a vacant channel having a relatively low probability and a low steady noise level can be selected as a use channel.

  More specifically, in the state of FIG. 5, each communication channel Ch (1), Ch (3), Ch (4), Ch (5), Ch (7), and Ch (8) are all free channels. Leakage N (2) from the communication channel Ch (2) to the empty channel Ch (1) and Ch (3) and the communication channel Ch (6) to the empty channel Ch (5) and Ch (7) The leakage ratio N (6) causes each free channel Ch (1), Ch (3), Ch (5), Ch (7) to have a carrier-to-noise ratio CNR of other free channels Ch (4), Ch (8 ) Is higher than Therefore, when free channels Ch (4) and Ch (8) are selected as used channels and used for wireless video transmission or the like, noise power such as leakage is small even for relatively small carrier reception power. It is easy to ensure a noise-to-noise ratio CNR.

  Further, since the communication channel Ch (8) is located at one end of a group of communication channels that can be selected by the wireless communication device 1, it is possible to receive leakage of a wireless transmission wave spectrum from a wireless communication device adopting another wireless standard. The magnitude of this leak is unknown. Therefore, when both communication channels Ch (4) and Ch (8) are compared, if the communication channel Ch (4) is selected as a use channel, it is easy to obtain a relatively large radio transmission distance or radio transmission area.

  As a result, by selecting the communication channel Ch (4) as described above, a relatively large wireless transmission distance or wireless transmission area can be easily obtained.

  On the other hand, as shown in FIG. 6, when there is no free channel in which both adjacent channels are free, the used channel selection processing unit 23 according to the present embodiment uses each free channel as the next best option. Select as a channel candidate.

  Here, the actual amount of leakage from a certain communication channel Ch (i) to the adjacent channel Ch (i + 1) .Ch (i-1) is the transmission power of the transmitter communicating on the communication channel Ch (i). It varies depending on various factors such as the distance to the transmitter or the presence or absence of an obstacle between the two. Therefore, when there are two or more communication channels Ch (i) used, leakage to adjacent channels may occur depending on the distance between the two or more transmitters used for the communication channel Ch (i). Even if each transmitter includes the same transmission spectrum, the level of leakage in adjacent channels is often different.

  The spectrum SP (i) may not be vertically symmetrical in the frequency domain. In this case, the amount of leakage to the upper adjacent channel Ch (i + 1) and the lower adjacent channel Ch ( The amount of leakage to i-1) is different.

  Furthermore, in a communication channel in which both sides are already used and both of them are adjacent channels, the noise level is the sum of the leakage levels from both sides located on both sides. The noise level is determined by tangling the difference in the side leakage level and the difference in the position of the transmitter used in the already used communication channel. As a result, the noise levels of the communication channels that are already used on both sides vary from case to case.

  Therefore, the used channel selection processing unit 23 according to the present embodiment selects each unused channel as a candidate for the used channel as the next best option, and determines the used channel based on the steady noise amount of each unused channel. By doing so, the wireless communication device 1 can actually select and use an empty channel that is likely to have a large carrier-to-noise ratio CNR. As a result, a wireless transmission path with higher transmission quality can be used, and data requiring bandwidth guarantee can be transmitted more reliably.

  The case where it is not vertically symmetrical will be described in more detail. For example, FIG. 7 shows a case where communication is performed on the upper adjacent channel Ch (i + 1) simultaneously with communication on the communication channel Ch (i). In this case, the carrier-to-noise ratio of the adjacent channel Ch (i + 1) is a leakage amount N1 (i) from the communication channel Ch (i) as compared with the original value (value when there is no other communication). , And becomes a value indicated by CNR (i + 1) in the figure.

  On the other hand, FIG. 8 shows a case in which communication is performed on the lower adjacent channel Ch (i−1) simultaneously with communication on the communication channel Ch (i). Also in this case, as in the case of FIG. 7, the carrier-to-noise ratio of the adjacent channel Ch (i-1) is less than the original value of the leakage amount N2 (i) from the communication channel Ch (i). Decrease by the amount and become the value indicated by CNR (i-1) in the figure.

  Further, in the example of FIG. 8, the condition of the size of the transmission spectrum is the same as that of FIG. 7, that is, the size of the spectrum SP (i) of the communication channel Ch (i) that is already used is 8 is the same, and the size of the spectrum SP (i + 1) and SP (i-1) of the communication channel Ch (i + 1) and Ch (i-1) to be used are the same. However, the shape of the spectrum SP (i) of the communication channel Ch (i) is not vertically symmetrical, and the leakage amount N2 (i) to the adjacent channel Ch (i-1) on the lower side is larger. . Therefore, in the examples of FIGS. 7 and 8, the lower adjacent channel is more likely to be used when the upper adjacent channel Ch (i + 1) is used even though the transmission spectrum size conditions are the same. A larger carrier-to-noise ratio CNR (i + 1) can be ensured than when Ch (i-1) is used. In the above, the case where the amount of leakage on the upper side is smaller is illustrated, but which amount of leakage is larger, and the shape of the spectrum of the leakage portion varies depending on the frequency of the communication channel, the circuit configuration, and the like.

  In the above description, the configuration in which the noise information update processing unit 22 acquires the noise information after the used channel selection processing unit 23 receives the selection instruction of the used channel has been described. However, the present invention is not limited to this. For example, regardless of whether there is an instruction to select a channel to be used, it may be a time before the start of transmission of the entire data (such as the entire AV data) requiring QoS guarantee or a time after the end of transmission. In the transmission period of the entire data, it may be between the transmission periods of part of the data. If the noise information can be acquired before the use channel selection processing unit 23 determines the use channel (before the comparison unit 42 compares the noise information), substantially the same effect can be obtained.

  However, at present, the transmission rate that can be transmitted by wireless communication often competes with the transmission rate required by the data, and as described above, the wireless communication device 1 according to the present embodiment, While transmitting data, the communication channel often continues to occupy near monopoly. As a result, in such a case, if the noise information is updated during the transmission period of the entire data, there is a possibility that the transmission of the data is hindered. Therefore, when the communication speed is not sufficient, the noise information is sent at a time before the transmission start time of the entire data requiring QoS guarantee or at a time after the transmission end time, as in this embodiment. It is desirable to update.

  In recent years, there has been a strong demand for the wireless communication device 1 to reduce power consumption, and the wireless communication device 1 according to the present embodiment can be used as a part of the wireless communication device 1 or when communication is unnecessary. Power supply to all circuits is stopped. In such a case, if noise information is to be updated even though communication is not being performed, it is necessary to supply power to the circuit required for the update during the update, thus sufficiently reducing power consumption. There is a risk that it will not be possible. Therefore, when a reduction in power consumption is strongly demanded, it is desirable to acquire noise information at a time point after an instruction to select a channel to be used as in this embodiment.

  When the wireless communication device 1 transmits not only data that requires QoS guarantee but also data that does not require QoS guarantee, the noise information may be updated during the transmission of the data.

  In the above description, in the adjacent channel state search and the empty channel state search, the empty channel is determined based on the usage status of each channel from the control unit 5, but the present invention is not limited to this. The noise information update processing unit 22 stores the noise information of each channel in the radio wave intensity / channel storage unit 23, and the used channel selection processing unit 23 determines the usage status of each channel based on the noise information, A channel that intermittently sends data may be regarded as an empty channel.

  More specifically, as described above, the wireless communication device 1 according to the present embodiment, when selecting a channel to be used, is a system in which a specific channel is almost exclusively occupied and transmitted wirelessly almost exclusively. An empty channel that is not substantially affected by the radio transmission of the system is selected with priority over an empty channel that is almost always affected by a large transmission power leakage from the radio transmission.

  Therefore, the wireless communication device 1 (used channel selection processing unit 23) regards the intermittent transmission of data such as a conventional wireless LAN as an unused channel in the adjacent channel state search and the empty channel state search, It may be excluded from the target. In this case, it may be determined by observing whether the channel state is almost always the state or only the state from the result of performing a plurality of searches as well as a single search.

  In the above description, the reception level detector 32 detects the level of the baseband signal (for example, the output of the amplifier 15 shown in FIG. 2) output from the reception radio frequency processing unit 2. It is not limited. If the radio field intensity of the channel (specific channel) selected by the receiving radio frequency processing unit 2 can be detected, the same effect can be obtained even if detection is performed based on signals from other parts such as the output of the mixer 14. It is done.

  Further, in the above, the frequency control unit 31 sequentially changes the oscillation frequency of the local oscillator 13 also used for signal reception, and the reception radio frequency processing unit 2 sequentially changes the channel selected. The radio wave intensity of each channel is detected based on the signal from the reception radio frequency processing unit 2. For example, the radio wave intensity of each channel is detected independently of the reception radio frequency processing unit 2. Even if the member for providing is provided, the same effect is acquired. However, if the reception radio frequency processing unit 2 is shared as in the present embodiment, the wireless communication device 1 with a smaller circuit scale and lower power consumption can be realized.

  In the above embodiment, the members 21 to 23, 31 to 33, and 41 to 42 constituting the wireless communication device 1 indicate that the program code stored in a recording medium such as a ROM or a RAM is calculated by a calculation unit such as a CPU. The case where “the functional block is realized by execution” has been described as an example, but may be realized by hardware that performs the same processing. Further, it can also be realized by combining hardware that performs a part of the processing and the above-described calculation means that executes the program code for controlling the hardware and the remaining processing. Further, even among the members described above as hardware, the hardware for performing a part of the processing and the arithmetic means for executing the program code for performing the control of the hardware and the remaining processing It can also be realized by combining them. The arithmetic means may be a single unit, or a plurality of arithmetic means connected via a bus inside the apparatus or various communication paths may execute the program code jointly. The storage unit (the radio wave intensity / channel storage unit 21) among the above members may be a storage device such as a memory.

  The program code itself that can be directly executed by the computing means, or a program as data that can be generated by a process such as decompression described later, stores the program (program code or the data) in a recording medium, A recording medium is distributed, or the program is distributed by being transmitted by a communication means for transmitting via a wired or wireless communication path, and is executed by the arithmetic means.

  In the case of transmission via a communication path, each transmission medium constituting the communication path propagates a signal sequence indicating a program, whereby the program is transmitted via the communication path. Further, when transmitting the signal sequence, the transmission device may superimpose the signal sequence on the carrier by modulating the carrier with the signal sequence indicating the program. In this case, the signal sequence is restored by the receiving apparatus demodulating the carrier wave. On the other hand, when transmitting the signal sequence, the transmission device may divide and transmit the signal sequence as a digital data sequence. In this case, the receiving apparatus concatenates the received packet groups and restores the signal sequence. Further, when the transmission apparatus transmits a signal sequence, the signal sequence may be multiplexed with another signal sequence and transmitted by a method such as time division / frequency division / code division. In this case, the receiving apparatus extracts and restores individual signal sequences from the multiplexed signal sequence. In any case, the same effect can be obtained if the program can be transmitted via the communication path.

  Here, it is preferable that the recording medium for distributing the program is removable, but it does not matter whether the recording medium after distributing the program is removable. In addition, the recording medium can be rewritten (written), volatile, or the recording method and shape as long as a program is stored. Examples of recording media include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks and hard disks, CD-ROMs, magneto-optical disks (MO), mini-discs (MD) and digital A disk such as a video disk (DVD) may be mentioned. The recording medium may be a card such as an IC card or an optical card, or a semiconductor memory such as a mask ROM, EPROM, EEPROM, or flash ROM. Or the memory formed in calculating means, such as CPU, may be sufficient.

  The program code may be a code for instructing the arithmetic means of all the procedures of the processes, or a basic program capable of executing a part or all of the processes by calling according to a predetermined procedure. If (for example, an operating system or a library) already exists, a part or all of the entire procedure may be replaced with a code or a pointer that instructs the arithmetic means to call the basic program.

  The format for storing the program in the recording medium may be a storage format that can be accessed and executed by the arithmetic means, for example, as in a state where the program is stored in the real memory, or is stored in the real memory. Installed in the local recording medium from the storage format after being installed in a local recording medium (for example, real memory or hard disk) that is always accessible by the computing means, or from a network or a transportable recording medium The previous storage format may be used. Further, the program is not limited to the compiled object code, but may be stored as source code or intermediate code generated during interpretation or compilation. In any case, the above calculation is performed by a process such as decompression of compressed information, decoding of encoded information, interpretation, compilation, linking, allocation to real memory, or a combination of processes. If the means can be converted into an executable format, the same effect can be obtained regardless of the format in which the program is stored in the recording medium.

  According to the present invention, when selecting a use channel as a communication channel to be used for communication from a plurality of communication channels, the use channel candidates are selected based on the use status of the plurality of communication channels, When a plurality of candidates are selected, it is determined which of the candidates is to be used based on the steady noise amount of each vacant channel that is a candidate. Therefore, even if the communication that continues to occupy the communication channel in a nearly monopolistic state is performed on another communication channel and when the communication is performed on the use channel, the use channel is not affected. A communication channel suitable for communication using a wireless communication can be selected. For example, wireless AV stream transmission and wireless IP data transmission are widely used for wireless communication, including wireless communication using a wideband wireless channel (such as OFDM modulation / demodulation). Can be used.

1, showing an embodiment of the present invention, is a block diagram illustrating a configuration of a main part of a wireless communication device. FIG. It is a block diagram which shows the principal part structure of the radio frequency processing part for reception of the said radio | wireless communication apparatus. It is a flowchart which shows the channel selection method by the use channel selection process part of the said radio | wireless communication apparatus. It is the graph which shows the transmission power which leaks to an adjacent channel, and shows the relationship between the magnitude | size of a spectral density, and a frequency. It is a figure which shows the use condition of each communication channel, and shows the case where there exists an empty channel which has the adjacent channel which is not used on both sides. It is a drawing showing the use status of each communication channel, and showing a case where there is no empty channel having adjacent unused channels on both sides. It is a figure which shows the relationship between the magnitude | size of the transmission power leaked to an adjacent channel, and the carrier-to-noise ratio in an adjacent channel, and shows the case where the said adjacent channel is an upper side. It is a figure which shows the relationship between the magnitude | size of the transmission power which leaks to an adjacent channel, and the carrier-to-noise ratio in an adjacent channel, and shows the case where the said adjacent channel is a lower side.

Explanation of symbols

1 Wireless communication device 22 Noise information update processing unit (detection means)
23 Use channel selection processing unit (channel determination means)

Claims (17)

In a communication channel selection method of a wireless communication system including a communication channel determination step of selecting a use channel as a communication channel used for communication from among a plurality of communication channels.
The communication channel determination step selects a candidate for the use channel based on the use status of the plurality of communication channels;
If a plurality of candidates are selected in the selection step, which of the candidates is to be used is determined based on the stationary noise amount detection result of each empty channel that is a candidate. A communication channel selection method including a determination step.   2. The communication channel selection according to claim 1, wherein the determining step determines a communication channel having the smallest stationary noise amount detection result as the use channel among the candidate empty channels. Method.   In the selection step, when there is an empty channel in which adjacent channels that are not used exist on both sides among the empty channels in the plurality of communication channels, the selection process includes the empty channel and is not used. 3. The communication channel selection method according to claim 1, further comprising a first selection step of selecting a communication channel that does not include an empty channel that does not have adjacent channels on both sides.   The selection step is performed when no candidate is found in the first selection step, and includes a second selection step of selecting an empty channel among the plurality of communication channels as a candidate. The communication channel selection method according to claim 3. Including a detection step of detecting a steady noise amount of the communication channel;
The determination step determines a channel to be used based on a detection result of a steady noise amount of each empty channel that is a candidate among the noise amounts of the communication channel detected in the detection step,
The detection step detects a steady noise amount of the communication channel by measuring the noise amount of the communication channel a plurality of times at predetermined intervals. 3. The communication channel selection method according to 3 or 4.   When there is no communication channel already used, the step of determining, as a use channel, a communication channel that is one inner than the communication channel arranged at one end among the frequency bands assigned to the entire plurality of communication channels. The communication channel selection method according to claim 1, further comprising: In a wireless communication device having channel determining means for selecting a communication channel to be used for communication from a plurality of communication channels,
A detecting means capable of detecting a steady noise amount of each communication channel;
The communication channel determination means selects candidates for the use channel based on the use status of the plurality of communication channels, and when a plurality of candidates are selected, the candidate detected by the detection means A wireless communication device that determines which of the candidates is used as a channel to be used based on a steady noise amount of each empty channel.   8. The radio according to claim 7, wherein the communication channel determining means determines a communication channel having the smallest stationary noise amount detection result as the used channel among the candidate empty channels. Communication machine.   The communication channel determination means includes the empty channel as the candidate and is used when there is an empty channel in which an unused adjacent channel exists on both sides among the empty channels of the plurality of communication channels. 9. The wireless communication apparatus according to claim 7, wherein a communication channel that does not include an empty channel in which no adjacent channel exists on both sides is selected.   The communication channel determination means selects an empty channel of the plurality of communication channels as a candidate when no empty channel in which the unused adjacent channel exists on both sides is found. Item 10. A wireless communication device according to Item 9.   The detection means detects a steady noise amount of the communication channel by measuring the noise amount of the communication channel a plurality of times at predetermined intervals. , 9 or 10.   When there is no communication channel already used, the communication channel determination means is a communication channel that is one inner than the communication channel arranged at one end among the frequency bands allocated to the plurality of communication channels. The wireless communication device according to claim 7, wherein: is determined as a use channel. A computer program capable of controlling detection means capable of detecting a steady noise amount of a plurality of communication channels,
Based on the use status of the plurality of communication channels, a candidate for a use channel to be used for communication is selected from the plurality of communication channels, and when a plurality of candidates are selected, the detection unit detects A program that causes the computer to operate as a communication channel determination unit that determines which of the candidates is to be used based on the steady noise amount of each empty channel that is a candidate. In a communication channel selection method of a wireless communication system including a communication channel determination step of selecting a use channel as a communication channel used for communication from among a plurality of communication channels.
In the communication channel determination step, when a free channel whose adjacent channel on both sides is a free channel and a free channel that is not the same are found based on the usage status of the plurality of communication channels, the adjacent channel on both sides is a free channel. A communication channel selection method comprising: selecting an empty channel as a use channel. In a wireless communication device having channel determining means for selecting a communication channel to be used for communication from a plurality of communication channels,
The channel determination means determines whether the adjacent channel on both sides is an empty channel when a free channel whose adjacent channel on both sides is a free channel and a free channel that is not so are found based on the usage status of the plurality of communication channels. A wireless communication device, wherein a certain empty channel is selected as a use channel.   When selecting a communication channel to be used for communication from among a plurality of communication channels, based on the use status of the plurality of communication channels, an empty channel whose adjacent channels on both sides are empty channels, and an empty channel that is not Is found, a program for operating a computer as channel determining means for selecting a free channel whose adjacent channel on both sides is a free channel as a used channel.   A recording medium on which the program according to claim 13 or 16 is recorded.

Images