WO2008072441A1 - Wireless communication device - Google Patents

Wireless communication device Download PDF

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Publication number
WO2008072441A1
WO2008072441A1 PCT/JP2007/071900 JP2007071900W WO2008072441A1 WO 2008072441 A1 WO2008072441 A1 WO 2008072441A1 JP 2007071900 W JP2007071900 W JP 2007071900W WO 2008072441 A1 WO2008072441 A1 WO 2008072441A1
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WO
WIPO (PCT)
Prior art keywords
channel
channels
received power
communication
free
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PCT/JP2007/071900
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French (fr)
Japanese (ja)
Inventor
Toshiya Kitagawa
Takehiro Kawai
Original Assignee
Omron Corporation
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Publication date
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Publication of WO2008072441A1 publication Critical patent/WO2008072441A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/309—Measuring or estimating channel quality parameters
    • H04B17/318—Received signal strength
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality

Definitions

  • the present invention relates to a wireless communication apparatus that performs data communication wirelessly.
  • FIG. 8 is a diagram showing an example of channel arrangement in the UHF band. As shown in the figure, in Japan, there are nine channels in the 2 MHz band divided by the 200 kHz width in Japan (or 95. 0-954. In Europe, 865. 6-867 There are 10 channels divided by 200 kHz with a 6 MHz 2 MHz band, and in areas where the usable frequency band is narrow, multiple wireless communication devices such as reader / writers should be placed close to one another. In order to avoid mutual radio wave interference between reader / writers, the carrier law is obliged by the Radio Law to prevent mutual interference between readers and writers!
  • Carrier sense is also called LBT (Listen Before Talk), and before communication between a reader / writer and an RFID tag, the received power strength of a carrier (carrier) is measured (sensed). It is checked whether it is a radio wave of a communicable frequency. That is, for the radio wave transmitted from the reader / writer to the RFID tag, the received power strength of the channel in that frequency band is measured. Then, if the measured received power strength is equal to or higher than a predetermined level, it is determined that the channel is in use and waits for transmission, and if less than the predetermined level, it is determined that the channel is not used and transmission is performed. Do. This process is designed to prevent interference with nearby reader / writers.
  • the channel evaluation is complicated in the order of (A) ⁇ (B) ⁇ (C), and as a result, the total amount of communication in the carrier sense system is increased. Is possible.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2006-197233
  • the present invention has been made to increase the total amount of communication by devising a channel evaluation method. That is, in a wireless communication apparatus having a carrier sense function, when searching for a free channel, the use channel is selected in consideration of the influence of the interference wave of the adjacent channel, and communication is performed at the optimum communication speed for the selected use channel. .
  • This processing aims to improve the communication efficiency between the wireless communication device and the data carrier. Means to solve the problem
  • a wireless communication apparatus wirelessly communicates data with a data carrier using one or more channels on a plurality of divided frequency bands.
  • a wireless communication apparatus that performs the wireless communication, and prior to wireless communication with the data carrier, an odd number of consecutive frequency bands based on the reception power strength measured in channel units in continuous channel groups within a predetermined range. It is characterized in that the free channel is searched and communication speed with the data carrier is started by setting the communication speed to be larger as the frequency bandwidth of the entire odd number of continuous free channels extracted by the search is wider. I assume.
  • the wireless communication apparatus of the present invention prior to wireless communication with the data carrier, based on the received power intensity measured in channel units in continuous channel groups in a predetermined range. Based on the received power strength below the first threshold, a free channel is searched to extract one free channel, and the received power strength of the channel adjacent to the high frequency side of the extracted free channel, and A continuous odd number of vacant channels are obtained if the received power strengths of the adjacent channels on the low frequency side of the extracted one vacant channel are both less than or equal to a second threshold that is greater than the first threshold. It may be
  • received power intensity data in units of channels is stored each time the search for the vacant channel is performed, and the vacant channel is searched for vacant channel based on the past received power strength.
  • the communication speed may be set by estimating the situation
  • the wireless communication apparatus is particularly suitable for a reader / writer used in an RFID system that requires a countermeasure against interference by carrier sense, such as a high-power UHF band or low-power UHF reader / writer. Applicable
  • the use channel when selecting the use channel among the vacant channels searched at the time of carrier sense, the use channel is selected according to the availability of the adjacent channel. .
  • communication speed is set to the maximum speed that can be communicated according to the usage status of the adjacent channel, with the selected channel used. For this reason, there are many free channels! /, In the case of high speed communication, and in the case of low free channels! /, In the case of low speed communication, communication errors and communication time increase due to radio interference of adjacent channels. You can reduce the impact of In addition, compared to the fixed channel selection method, communication efficiency can be greatly improved.
  • FIG. 1 is a view showing a configuration of a re-reader / writer which is a wireless communication apparatus of the present invention.
  • the reader / writer 1 of the present embodiment is a device that performs wireless data communication with an RFID tag, which is a data carrier, using radio waves. More specifically, the reader / writer 1 selects and uses radio waves of one channel frequency selected from the nine channels in the UHF band shown in FIG. Memory The data is read and written.
  • the reader / writer 1 is configured to include a control unit 2, a transmitter 3, a transmitting unit 4, a receiving unit 5, a circulator 6, and an antenna 7 described below.
  • the control unit 2 controls transmission and reception between the reader / writer 1 and the RFID tag, and mainly generates and outputs a transmission signal S to be transmitted to the RFID tag, and receives the reception signal received from the RFID tag.
  • the transmitter 3 sets the carrier frequency of the transmission signal S based on the control signal S from the control unit 2.
  • the present embodiment is configured by a PLL circuit.
  • the transmitting unit 4 sets a read signal or a write signal to the RFID tag as the transmission signal S.
  • the digital-to-analog converter 41 converts the transmission data output from the control unit 2 from a digital signal to an analog signal and outputs it as a baseband signal S.
  • the modulator 42 performs digital analysis on the carrier wave f of the predetermined frequency set by the transmitter 3.
  • the carrier wave f is not modulated when transmitting. Furthermore, the high frequency amplifier 43 is a modulator 42.
  • the transmission signal S outputted from the high frequency amplifier 43 is radiated from the antenna 7 through the circulator 6 and the low pass filter 8.
  • the receiving unit 5 receives the signal returned from the RFID tag as a received signal S, and includes a band limiting filter 51, a low noise amplifier 52, a demodulator 53, an amplifier 54, and an analog digital converter 55.
  • the received signal S input through the band limiting filter 51 is a weak radio wave due to the reflected wave of the RFID tag, and thus is amplified by the low noise amplifier 52 and output to the demodulator 53.
  • the demodulator 53 demodulates the input reception signal S into a baseband signal S by a carrier wave f of a predetermined frequency from the transmitter 3. Then it is demodulated
  • the baseband signal S is input to the amplifier 54 and power amplified. Furthermore, analog
  • the digital converter 55 converts the amplified baseband signal S from an analog signal into a digital signal.
  • a power supply is not built in the RFID tag! /, Using a passive tag.
  • the communication system between the reader / writer 1 and the RFID tag is a half duplex system, and the antenna 7 is shared for transmission and reception, and the circulator 6 divides the transmission signal S and the reception signal S by
  • the reception signal S received from the RFID tag by the antenna 7 is guided from the circulator 6 to the reception unit 5 through the low pass filter 8.
  • FIG. 2 is a diagram showing a configuration of a control unit in the reader / writer.
  • the control unit 2 includes a transmission data generation unit 21 and an encoding unit 22.
  • the transmission data generated by the transmission data generation unit 21 is encoded by the encoding unit 22 and its code
  • the converted transmission data is output as a digital signal to a digital-to-analog converter 41.
  • the control unit 2 includes a decoding unit 23 and a reception data processing unit 24.
  • the digitalization reception signal S input from the analog-to-digital converter 55 is decoded by the decoding unit 23, and the decoding is performed.
  • the received data processing unit 24 processes the digitized received data.
  • the control unit 2 further includes an FFT processing unit 25, a channel selection processing unit 26, and a FIFO memory 27.
  • the FFT processing unit 25 performs high-speed Fourier transform processing using the digital signal input from the analog-to-digital converter 55 at the time of carrier sensing. That is, the FFT processing unit 25 performs fast Fourier transform processing on the digital amount data input from the analog-to-digital converter 55.
  • the FFT processing unit 25 extracts each frequency component contained in the digital signal, and acquires and outputs distribution data of received power intensity for each frequency band as shown in FIG.
  • the channel selection processing unit 26 stores in the FIFO memory 27 distribution data of received power intensity for each frequency band input from the FFT processing unit 25 at the time of carrier sensing. Further, the channel selection processing unit 26 evaluates the idle channel based on the received power intensity distribution data read from the FIFO memory 27 and, when there is a plurality of continuous idle channel groups of one or more channels, among them, Perform processing for selecting an optimal channel group from further, The channel selection processing unit 26 sets the transmission rate of the carrier wave f in the selected used channel (
  • FIG. 3 is a diagram showing a communication method of passive RFID and spectrum states of each communication period.
  • the reader / writer 1 of the present embodiment adopts a communication method using a passive RFID, and the radio wave transmitted from the reader / writer 1 to the RFID tag causes an electromotive force to operate the RFID tag. As it plays the role of supplying, it is radiated from antenna 7 with high power. As shown in the figure, in the communication period from the reader / writer 1 to the RFID tag, a read command is transmitted as a modulated wave from the antenna 7 of the reader / writer 1. At this time, the RFID tag demodulates and analyzes the read command. In addition, at the time of command transmission, an option can be added to specify the transmission rate of the signal to the RFID tag, and it is possible to change the transmission rate for each communication. Note that (b) of the figure shows the modulated wave spectrum of the reader / writer 1 band-limited in the channel!
  • the reader / writer 1 transmits a non-modulated continuous carrier wave CW from the antenna 7. Then, in the radio wave sent back from the RFID tag to the reader / writer 1 slightly later than the continuous carrier wave CW, the antenna impedance of the RFID tag changes in accordance with the data in the memory inside the tag. As a result, the amount of reflection of the radio wave from the reader / writer 1 changes in accordance with the change in the antenna impedance of the tag, and is returned as a weak signal modulated by the tag data. Also, the impedance modulation rate of the RFID tag is determined by the transmission rate specified in the transmit command. The same figure (c) shows the continuous wave CW of the reader / writer 1 and the modulation wave spectrum of a weak signal due to the change in impedance of the RFID tag.
  • FIG. 4 is a diagram showing the relationship between the communication speed and the frequency band.
  • the RFID tag in the case of carrier f power 3 ⁇ 4 channel from reader / writer 1
  • the transmission rate is set to a high speed, if there is an interference wave spectrum in the adjacent n + 1 channel, the frequency band is fogged, and the communication reliability between the reader / writer 1 and the RFID tag is reduced.
  • the reader / writer 1 of this embodiment statistically inspects the intensity of the interference wave of the adjacent reader / writer at the time of channel evaluation by carrier sense, and optimizes the communication speed according to the intensity of the interference wave. By changing it, the communication efficiency between the reader / writer 1 and the RFID tag is improved.
  • FIG. 5 is a view showing the relationship between received power intensity distribution data and idle channels.
  • the FFT processing unit 25 of the control unit 2 performs fast Fourier transform processing using the digital signal input from the analog-to-digital converter 55 at the time of carrier sensing, as shown in FIG.
  • Receive power intensity distribution data measured on a channel-by-channel basis.
  • the horizontal axis shows nine channels (CH) usable in the UHF band
  • the vertical axis shows the level of the received power (dBm) divided into three thresholds of Th1, Th2, and Th3.
  • the threshold Thl is set to one 74 dBm defined as the carrier sense level of the high power type UHF band. And, in the example shown in the figure, it is indicated that channels whose measured received power strength is less than the threshold Thl, that is, four channels of CH2, CH3, CH6 and CH9 are communicable idle channels. Then, when there are a plurality of vacant channels as in this received power intensity distribution data, the channel selection processing unit 26 evaluates the vacant channels as follows and then selects the most suitable channel, and selects the use. Determine the communication speed on the channel.
  • FIG. 6 is a flowchart showing an example of channel selection processing in the control unit.
  • the reader / writer 1 stops transmission of radio waves from the antenna 7 and performs carrier sense (step 601). That is, the reader / writer 1 measures the received power intensity in all channels (CH;! To 9) of the UHF band via the antenna 7 and the receiving unit 5. Then, based on the received power intensity distribution data from the FFT processing unit 25, the channel selection processing unit 26 searches for an available channel whose received power intensity is less than the carrier sense level (74 dBm) of the threshold value Thl. In the example of Fig. 5, four channels of CH2, CH3, CH6 and CH9 correspond to free channels.
  • the channel selection processing unit 26 checks whether or not there is a vacant channel at a medium level or more among the vacant channels searched by carrier sense (step 602).
  • the “medium level or higher free channel” means a channel that satisfies the condition that the received power strengths of at least one adjacent upper and lower channel among the free channels are both less than the threshold Th2. It will be as follows when explaining with the example of FIG.
  • CH2 has a low received power level of CH3 on the next side and a power level of CH1 on the next lower side which is less than the threshold Th2 and therefore it does not correspond to a vacant channel above medium level. It is evaluated as an empty channel.
  • CH3 corresponds to a vacant channel at a medium level or more, since the received power intensities of CH2 and CH4 both adjacent to the upper and lower sides are both less than the threshold Th2.
  • CH6 is evaluated as a low level vacant channel because it does not correspond to a vacant channel above the middle level because both received power strengths of CH5 and CH7 on both upper and lower sides exceed the threshold value Th2. Since there is no channel on the top of CH9 and the received power strength is less than the threshold Th2 and the received power strength of CH8 on the next bottom is also less than the threshold Th2, it corresponds to a vacant channel of medium or higher level.
  • the channel selection processing unit 26 checks if there is a high-level free channel among the medium level or higher level free channels (step 603).
  • “high level free channel” means a channel that satisfies the condition that the received power strength of at least two adjacent and adjacent channels among the medium level or higher level channels is less than the threshold Th3. Say. It will be as follows when explaining with the example of FIG.
  • CH3 and CH9 Two channels, CH3 and CH9, were searched as free channels at medium level or higher It is.
  • CH3 has high received signal strength because both CH2 and CH2 receive power intensities below the threshold Th3 and both CH4 and CH5 receive power intensities below the threshold Th3.
  • CH9 does not have a received power strength that is more than the threshold level Th3 on the adjacent side, but since the received power level of the second lower CH7 exceeds the threshold level Th3, it is not It does not correspond and it is evaluated as a medium level free channel.
  • the channel selection processing unit 26 evaluates which level of low, medium and high corresponds to all free channels, and then selects a channel to be used according to the following procedure, and its communication speed Decide.
  • step 604 it is determined whether there is a high level free channel (step 604).
  • select the medium use channel step 609).
  • LBF Local Beam Forming
  • CH3 which is a high level free channel exists, it is selected as a use channel, and communication is performed by setting the communication speed at a high speed.
  • the power that can be considered when there are a plurality of high level free channels is considered. In this case, since the received power strengths of all the channels are less than the threshold Thl, any channel may be selected.
  • step 605 it is judged whether there is a medium level free channel. If there is a medium level free channel here, select its medium power and its use channel (step 608). As shown in Figure 4, since the received power strength of one channel in the upper and lower adjacent channels is lower than the threshold Th2 in the middle level free channel. Even if the data transmission rate is set to a medium speed (80 kbps), the occupied bandwidths of the upper and lower sidebands are expanded only to 160 kHz, and radio interference with adjacent channels does not occur. Therefore, when using a middle level free channel, the communication speed is set to medium speed and communication is started (step 607).
  • the medium channel of the low level free channel is selected (step 606).
  • the low-level free channels have reception power strengths of upper and lower adjacent channels that are equal to or higher than the threshold Th2. Therefore, if the data transmission speed is set to low speed (40 kbps) as shown in Figure 4, the occupied bandwidth is broadened to only 80 kHz. There is no radio interference with adjacent channels. Therefore, when using a low level free channel, the communication speed is set to low and communication is started (step 607).
  • the transmission rate is changed in accordance with the availability of the adjacent channel after the level evaluation is performed on all the available channels. .
  • the transmission rate is changed in accordance with the availability of the adjacent channel after the level evaluation is performed on all the available channels. .
  • the following channel selection process may be employed instead of the channel selection process described in FIG.
  • FIG. 7 is a flowchart showing another example of channel selection processing in the control unit.
  • the reader / writer 1 stops transmission of radio waves from the antenna 7 and performs carrier sensing (step 701). That is, the reader / writer 1 measures the received power intensity in all channels (CH;! To 9) of the UHF band via the antenna 7 and the receiving unit 5. Then, based on the received power intensity distribution data from the FFT processing unit 25, the channel selection processing unit 26 searches for an available channel whose received power intensity is less than the carrier sense level (74 dBm) of the threshold value Thl (step 702). ). The free channel search based on this carrier sense is the same as in FIG.
  • the channel selection processing unit 26 stores free channel information (step 703). That is, the channel selection processing unit 26 receives each channel searched by carrier sense. Data of transmission power strength is stored in the FIFO memory 27. The storage of the free channel information is performed at each carrier sense, and the latest data of each channel is regularly and quantitatively stored in the FIFO memory 27.
  • the channel selection processing unit 26 checks channel history information (step 704).
  • the “channel history information” refers to the average value of the number of free channels calculated using the history of the past channel information stored in the FIFO memory 27.
  • past channel information it is preferable to adopt data that can reflect the radio interference condition of each latest channel depending on the number of times and time, such as the latest n data or data within n minutes from the present.
  • the channel selection processing unit 26 determines whether or not the average number of vacant channels in the past is three or more by checking the channel history information (step 705). If the past average number of vacant channels is three or more, it is next determined whether the past average number of vacant channels is five or more (step 708). As a result, when the average number of vacant channels in the past is 5 or more, the channel used is selected from the vacant channels searched by the carrier sense this time (step 710). If the average number of free channels in the past is 5 or more, it can be estimated that the number of other readers / writers that have recently executed communication is small, so LBF is used to set the transmission speed to the maximum high speed (160 kbps). Communication is started (step 707). Before the end of communication and new communication
  • step 708 even if the average number of vacant channels in the past is not 5 or more, the channel used is selected from among the vacant channels searched by this carrier sense.
  • step 705 even if the average number of vacant channels in the past does not exist three or more, the medium power of the vacant channels searched by this carrier sense is also selected, but in this case transmission Set the speed to the lowest speed (40 kbps) (Step 7 06). Then, by setting the transmission rate to a low speed, the occupied bandwidths of the upper and lower sidebands are further narrowed to prevent radio interference with adjacent channels, and then communication is started (step 707).
  • the past channel use history is held and accumulated every carrier sense, and the radio wave status of each nearest channel is determined before communication. I was able to refer to it.
  • the past statistical power accumulated in the channel situation is estimated, the ratio of the vacant channel in the past is estimated, the number of reader / writers that may cause radio interference is estimated, and the transmission speed is determined accordingly. It is supposed to decide. For this reason, it is possible to exhibit an effect more in line with the actual environment. In particular, it is preferable in an environment where the number of installed reader / writers in the system increases or decreases in operation.
  • communication efficiency can be further improved by using the channel level evaluation of FIG. 6 in combination.
  • the present invention is not limited to the example described above in which the wireless communication apparatus of the present invention is applied to a high power UHF band reader / writer.
  • the same can be applied to low-power UHF band reader / writers and communication devices in other frequency bands, as long as they are used in systems that require interference prevention measures by carrier sensing.
  • FIG. 1 is a view showing the configuration of a reader / writer that is a wireless communication apparatus of the present invention.
  • FIG. 2 is a diagram showing the configuration of a control unit in the reader / writer.
  • FIG. 3 A diagram showing the communication method of passive RFID and the spectrum state of each communication period.
  • FIG. 5 A diagram showing the relationship between received power intensity distribution data and idle channels.
  • FIG. 6 is a flowchart showing an example of channel selection processing in the control unit.
  • FIG. 7 is a flowchart showing another example of channel selection processing in the control unit.
  • FIG. 8 A diagram showing an example of channel arrangement in the UHF band.
  • Control unit 21 Transmission data generator

Abstract

[PROBLEMS] To improve communication efficiency by preventing a radio interference with an adjacent channel. [MEANS FOR SOLVING PROBLEMS] When selecting a channel to be used from among the unoccupied channels searched during the carrier sensing, a wireless communication device selects the channel to be used according to the unoccupied state of an adjacent channel. In addition, according to the usage of the adjacent channel, the device sets the communication speed of the selected channel to the maximum speed at which communication is possible and starts the communication.

Description

明 細 書  Specification
無線通信装置  Wireless communication device
技術分野  Technical field
[0001] 本発明は無線でデータ通信を行う無線通信装置に関する。  [0001] The present invention relates to a wireless communication apparatus that performs data communication wirelessly.
背景技術  Background art
[0002] 日本や欧州では、 UHF帯の電波を利用した RFIDシステムを構築する場合、使用 可能な周波数帯域が狭い。図 8は UHF帯のチャネル配置例を示す図である。同図 ίこ示すよう ίこ、 日本で (ま 952. 0—954. ΟΜΗζの 2MHzの帯域を 200kHz幅で分 割した 9個のチャネルが配置されている。また、欧州では 865. 6— 867. 6MHzの 2 MHzの帯域を 200kHz幅で分割した 10個のチャネルが配置されている。このように 使用可能な周波数帯域が狭い地域においては、リーダライタのような無線通信装置 を複数台近接して設置する場合、リーダライタ間相互の電波干渉を回避するために、 V、わゆるキャリアセンスが電波法で義務付けられて!/、る。  In Japan and Europe, when building an RFID system using radio waves in the UHF band, the usable frequency band is narrow. FIG. 8 is a diagram showing an example of channel arrangement in the UHF band. As shown in the figure, in Japan, there are nine channels in the 2 MHz band divided by the 200 kHz width in Japan (or 95. 0-954. In Europe, 865. 6-867 There are 10 channels divided by 200 kHz with a 6 MHz 2 MHz band, and in areas where the usable frequency band is narrow, multiple wireless communication devices such as reader / writers should be placed close to one another. In order to avoid mutual radio wave interference between reader / writers, the carrier law is obliged by the Radio Law to prevent mutual interference between readers and writers!
[0003] キャリアセンスは LBT (Listen Before Talk)とも呼ばれており、リーダライタと RFIDタ グとの間で通信を行う前に、搬送波（キャリア）の受信電力強度を測定 (センス）して、 通信可能な周波数の電波であるかどうかを確認するものである。すなわち、リーダライ タから RFIDタグに向けて送信する電波について、その周波数帯域にあるチャネルの 受信電力強度を測定する。そして、測定された受信電力強度が所定レベル以上であ ればそのチャネルが使用中であると判断して送信を待ち、所定レベル未満であれば そのチャネルが未使用であると判断して送信を行う。この処理により、近接するリーダ ライタとの混信を防ぐようにしている。  Carrier sense is also called LBT (Listen Before Talk), and before communication between a reader / writer and an RFID tag, the received power strength of a carrier (carrier) is measured (sensed). It is checked whether it is a radio wave of a communicable frequency. That is, for the radio wave transmitted from the reader / writer to the RFID tag, the received power strength of the channel in that frequency band is measured. Then, if the measured received power strength is equal to or higher than a predetermined level, it is determined that the channel is in use and waits for transmission, and if less than the predetermined level, it is determined that the channel is not used and transmission is performed. Do. This process is designed to prevent interference with nearby reader / writers.
[0004] このように、キャリアセンスを行うことでリーダライタが通信を開始する前に使用可能 なチャネルの空き状況を調べ、空きチャネルがあればその周波数の電波を送信する ことが規定されている。ところ力 複数個の空きチャネルが存在する場合にどのチヤネ ルを選択して使用するのかについては特に規定されていない。そこで、空きチャネル の選択方式としては例えば次のような方式が提案されている。  [0004] As described above, by performing carrier sense, it is specified that the availability of a usable channel is checked before the reader / writer starts communication, and radio waves of that frequency are transmitted if there is a vacant channel. . However, there is no stipulation as to which channel to select and use when there are multiple vacant channels. Thus, for example, the following method has been proposed as a method for selecting an idle channel.
[0005] (A)空きチャネルを発見次第そのチャネルを選択する。複数個の空きチャネルがあ る場合には予め優先順位を決めておく。 (A) As soon as a free channel is found, that channel is selected. There are several free channels In this case, the priority order is determined in advance.
(B)全チャネルを検索し、測定された受信電力強度が最も低いチャネルを選択する  (B) Search all channels and select the channel with the lowest measured received power strength
(C)全チャネルを検索し、空きチャネルの近傍チャネルのレベルを評価し、それを 重み付けする。さらにチャネルレベル評価の際にアプリケーションの重要度に基づく 重み付けをし、その重み付けに従ってチャネルを選択する（例えば下記の特許文献 1参照)。 (C) Search all channels, evaluate the levels of neighboring channels of free channels, and weight them. Furthermore, weighting is performed based on the importance of the application in channel level evaluation, and a channel is selected according to the weighting (see, for example, Patent Document 1 below).
[0006] 従来のチャネル選択方式では、上記（A)→ (B)→ (C)の順にチャネルの評価を複 雑に行うため、結果として、キャリアセンスシステム内での総通信量を増大させること が可能となる。  In the conventional channel selection method, the channel evaluation is complicated in the order of (A) → (B) → (C), and as a result, the total amount of communication in the carrier sense system is increased. Is possible.
[0007] 特許文献 1：特開 2006— 197233号公報  Patent Document 1: Japanese Patent Application Laid-Open No. 2006-197233
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problem that invention tries to solve
[0008] 本発明はチャネル評価方法の工夫により総通信量を増大させるためになされたも のである。すなわち、キャリアセンス機能を有する無線通信装置において、空きチヤ ネルの検索時に隣接チャネルの干渉波の影響を考慮して使用チャネルを選択し、か つ選択した使用チャネルについて最適な通信速度で通信を行う。この処理によって 、無線通信装置とデータキャリアとの間の通信効率を向上させることを目的とする。 課題を解決するための手段 The present invention has been made to increase the total amount of communication by devising a channel evaluation method. That is, in a wireless communication apparatus having a carrier sense function, when searching for a free channel, the use channel is selected in consideration of the influence of the interference wave of the adjacent channel, and communication is performed at the optimum communication speed for the selected use channel. . This processing aims to improve the communication efficiency between the wireless communication device and the data carrier. Means to solve the problem
[0009] 上記の目的を達成するため、本発明の無線通信装置は、複数個に区分された周波 数帯域上のチャネルを 1個または複数個利用してデータキャリアとの間で無線による データ通信を行なう無線通信装置であって、データキャリアとの無線通信の前に、所 定範囲の連続したチャネル群において、チャネル単位で測定された受信電力強度に 基づいて、周波数帯域が連続した奇数個の空きチャネルを検索し、検索によって抽 出された前記の奇数個の連続した空きチャネル全体の周波数帯域幅が広いほど大 きな通信速度に設定して、データキャリアとの通信を開始することを特徴とする。 [0009] In order to achieve the above object, a wireless communication apparatus according to the present invention wirelessly communicates data with a data carrier using one or more channels on a plurality of divided frequency bands. A wireless communication apparatus that performs the wireless communication, and prior to wireless communication with the data carrier, an odd number of consecutive frequency bands based on the reception power strength measured in channel units in continuous channel groups within a predetermined range. It is characterized in that the free channel is searched and communication speed with the data carrier is started by setting the communication speed to be larger as the frequency bandwidth of the entire odd number of continuous free channels extracted by the search is wider. I assume.
[0010] また、本発明の無線通信装置において、データキャリアとの無線通信の前に、所定 範囲の連続したチャネル群において、チャネル単位で測定された受信電力強度に基 づいて、第 1の閾値以下の受信電力強度である空きチャネルを検索して 1つの空きチ ャネルを抽出し、抽出した前記 1つの空きチャネルの高周波数側に隣接したチャネル の受信電力強度と、抽出した前記 1つの空きチャネルの低周波数側に隣接したチヤ ネルの受信電力強度が、共に前記の第 1の閾値よりも大なる第 2の閾値以下である 場合に、連続した奇数個の空きチャネルとするようにしてもよい。 Further, in the wireless communication apparatus of the present invention, prior to wireless communication with the data carrier, based on the received power intensity measured in channel units in continuous channel groups in a predetermined range. Based on the received power strength below the first threshold, a free channel is searched to extract one free channel, and the received power strength of the channel adjacent to the high frequency side of the extracted free channel, and A continuous odd number of vacant channels are obtained if the received power strengths of the adjacent channels on the low frequency side of the extracted one vacant channel are both less than or equal to a second threshold that is greater than the first threshold. It may be
[0011] さらに、本発明の無線通信装置において、前記の空きチャネルの検索の度にチヤ ネル単位の受信電力強度データを蓄積し、空きチャネルの探索時に過去の受信電 力強度に基づいて空きチャネル状況を推定して通信速度を設定するようにしてもよいFurthermore, in the wireless communication apparatus of the present invention, received power intensity data in units of channels is stored each time the search for the vacant channel is performed, and the vacant channel is searched for vacant channel based on the past received power strength. The communication speed may be set by estimating the situation
〇 Yes
[0012] 本発明の無線通信装置は、特に高出力型 UHF帯や低出力型 UHF帯のリーダラ イタのような、キャリアセンスによる混信防止対策が必要な RFIDシステムに使用され るリーダライタに好適に適用できる。  The wireless communication apparatus according to the present invention is particularly suitable for a reader / writer used in an RFID system that requires a countermeasure against interference by carrier sense, such as a high-power UHF band or low-power UHF reader / writer. Applicable
発明の効果  Effect of the invention
[0013] 本発明の無線通信装置によれば、キャリアセンス時に検索された空きチャネルの中 力、ら使用チャネルを選択する際に、隣接チャネルの空き状況に応じて使用チャネル を選択するようにした。また、選択した使用チャネルでの通信速度を隣接チャネルの 使用状況に応じて通信可能な最大速度に設定して通信するようにした。このため、空 きチャネルが多!/、場合には高速で通信し、空きチャネルが少な!/、場合には低速で通 信することによって、隣接チャネルの電波干渉による通信エラーや通信時間の増大 などの影響を抑えることができる。また、固定でのチャネル選択方式に比べて大幅に 通信効率を高めることが可能になる。  According to the wireless communication apparatus of the present invention, when selecting the use channel among the vacant channels searched at the time of carrier sense, the use channel is selected according to the availability of the adjacent channel. . In addition, communication speed is set to the maximum speed that can be communicated according to the usage status of the adjacent channel, with the selected channel used. For this reason, there are many free channels! /, In the case of high speed communication, and in the case of low free channels! /, In the case of low speed communication, communication errors and communication time increase due to radio interference of adjacent channels. You can reduce the impact of In addition, compared to the fixed channel selection method, communication efficiency can be greatly improved.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0014] 以下、本発明の実施の形態について、図面を参照しながら説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015] 図 1は本発明の無線通信装置であるリ一ダライタの構成を示す図である。 FIG. 1 is a view showing a configuration of a re-reader / writer which is a wireless communication apparatus of the present invention.
[0016] 同図に示すように、本実施形態のリーダライタ 1は、電波を利用してデータキャリア である RFIDタグとの間で無線によるデータ通信を行う装置である。より具体的には、 リーダライタ 1は、図 8に示した UHF帯における 9個のチャネルのうちから選択した 1 個のチャネル周波数の電波を選択して使用し、 RFIDタグに対してそのメモリに記憶 されているデータの読み出しや書き込みを行うものである。リーダライタ 1は、以下に 説明する制御部 2、発信器 3、送信部 4、受信部 5、サーキユレータ 6、アンテナ 7を備 えて構成されている。 As shown in the figure, the reader / writer 1 of the present embodiment is a device that performs wireless data communication with an RFID tag, which is a data carrier, using radio waves. More specifically, the reader / writer 1 selects and uses radio waves of one channel frequency selected from the nine channels in the UHF band shown in FIG. Memory The data is read and written. The reader / writer 1 is configured to include a control unit 2, a transmitter 3, a transmitting unit 4, a receiving unit 5, a circulator 6, and an antenna 7 described below.
[0017] 制御部 2は、リーダライタ 1と RFIDタグとの間の送受信を制御するものであり、主に RFIDタグへ送信する送信信号 Sを生成して出力し、 RFIDタグから受信した受信信  The control unit 2 controls transmission and reception between the reader / writer 1 and the RFID tag, and mainly generates and outputs a transmission signal S to be transmitted to the RFID tag, and receives the reception signal received from the RFID tag.
1  1
号 Sを入力して処理する。なお、制御部 2の構成については図 2において詳しく説明 する。  Enter S to process. The configuration of the control unit 2 will be described in detail in FIG.
[0018] 発信器 3は、制御部 2からの制御信号 Sに基づいて送信信号 Sの搬送周波数を設  The transmitter 3 sets the carrier frequency of the transmission signal S based on the control signal S from the control unit 2.
3 1  3 1
定するものであり、本実施形態では PLL回路によって構成されている。  In the present embodiment, it is configured by a PLL circuit.
[0019] 送信部 4は、 RFIDタグへの読み出し信号または書き込み信号を送信信号 Sとして The transmitting unit 4 sets a read signal or a write signal to the RFID tag as the transmission signal S.
1 出力するものであり、ディジタルアナログ変換器 41、変調器 42、高周波増幅器 43を 備えてなる。まずディジタルアナログ変換器 41は、制御部 2から出力された送信デー タをディジタル信号からアナログ信号に変換してベースバンド信号 Sとして出力する  1 output, and includes a digital-to-analog converter 41, a modulator 42, and a high frequency amplifier 43. First, the digital-to-analog converter 41 converts the transmission data output from the control unit 2 from a digital signal to an analog signal and outputs it as a baseband signal S.
4  Four
。次に変調器 42は、発信器 3で設定された所定周波数の搬送波 f をディジタルアナ  . Next, the modulator 42 performs digital analysis on the carrier wave f of the predetermined frequency set by the transmitter 3.
0  0
ログ変換器 41から入力されたベースバンド信号 Sで変調するとともに、読み出し信号  Modulate with the baseband signal S input from the log converter 41 and read
4  Four
を送信する場合には搬送波 f を無変調とする。さらに高周波増幅器 43は、変調器 42  The carrier wave f is not modulated when transmitting. Furthermore, the high frequency amplifier 43 is a modulator 42.
0  0
から入力された RF信号の電力増幅を行う。そして、高周波増幅器 43から出力された 送信信号 Sはサーキユレータ 6と低域通過フィルタ 8を介してアンテナ 7から放射され  Perform power amplification of the RF signal input from. Then, the transmission signal S outputted from the high frequency amplifier 43 is radiated from the antenna 7 through the circulator 6 and the low pass filter 8.
1  1
[0020] 受信部 5は、 RFIDタグから返信された信号を受信信号 Sとして入力するものであり 、帯域制限フィルタ 51、ローノイズアンプ 52、復調器 53、増幅器 54、アナログデイジ タル変換器 55を備えてなる。帯域制限フィルタ 51を介して入力された受信信号 Sは RFIDタグの反射波による微弱な電波であるため、ローノイズアンプ 52で増幅されて 復調器 53に出力される。ここで復調器 53は、入力された受信信号 Sを発信器 3から の所定周波数の搬送波 f によってベースバンド信号 Sに復調する。次に、復調され The receiving unit 5 receives the signal returned from the RFID tag as a received signal S, and includes a band limiting filter 51, a low noise amplifier 52, a demodulator 53, an amplifier 54, and an analog digital converter 55. Become. The received signal S input through the band limiting filter 51 is a weak radio wave due to the reflected wave of the RFID tag, and thus is amplified by the low noise amplifier 52 and output to the demodulator 53. Here, the demodulator 53 demodulates the input reception signal S into a baseband signal S by a carrier wave f of a predetermined frequency from the transmitter 3. Then it is demodulated
0 4  0 4
たベースバンド信号 Sは増幅器 54に入力されて電力増幅される。さらにアナログディ  The baseband signal S is input to the amplifier 54 and power amplified. Furthermore, analog
4  Four
ジタル変換器 55は、増幅されたベースバンド信号 Sをアナログ信号からディジタル信  The digital converter 55 converts the amplified baseband signal S from an analog signal into a digital signal.
4  Four
号に変換して出力する。そして、アナログディジタル変換器 55から出力された受信信 号 S2は制御部 2へ入力されて処理される。 Convert to the issue and output. Then, the received signal output from the analog-to-digital converter 55 The number S 2 is input to the control unit 2 and processed.
[0021] 本実施形態では RFIDタグに電源を内蔵しな!/、パッシブタグを使用してレ、る。この ため、リーダライタ 1と RFIDタグとの間の通信方式は半二重方式であり、アンテナ 7を 送信用と受信用とで共用し、サーキユレータ 6によって送信信号 Sと受信信号 Sを分 In the present embodiment, a power supply is not built in the RFID tag! /, Using a passive tag. For this reason, the communication system between the reader / writer 1 and the RFID tag is a half duplex system, and the antenna 7 is shared for transmission and reception, and the circulator 6 divides the transmission signal S and the reception signal S by
1 2 離するようになっている。すなわち、送信時には送信部 4から出力された送信信号 S  1 2 It is supposed to separate. That is, at the time of transmission, the transmission signal S output from the transmission unit 4
1 がサーキユレータ 6から低域通過フィルタ 8を介してアンテナ 7へと導かれ、アンテナ 7 力も外部の RFIDタグに向けて放射される。一方、受信時にはアンテナ 7で受信した RFIDタグからの受信信号 Sが低域通過フィルタ 8を介してサーキユレータ 6から受信 部 5へと導かれる。  1 is led from the circulator 6 through the low pass filter 8 to the antenna 7 and the antenna 7 power is also radiated towards the external RFID tag. On the other hand, at the time of reception, the reception signal S received from the RFID tag by the antenna 7 is guided from the circulator 6 to the reception unit 5 through the low pass filter 8.
[0022] 図 2はリーダライタにおける制御部の構成を示す図である。 FIG. 2 is a diagram showing a configuration of a control unit in the reader / writer.
[0023] 同図に示すように、制御部 2は送信データ生成部 21と符号化部 22を備えており、 送信データ生成部 21で生成した送信データを符号化部 22で符号化し、その符号化 された送信データをディジタル信号としてディジタルアナログ変換器 41に出力する。 また、制御部 2は復号化部 23と受信データ処理部 24を備えており、アナログディジタ ル変換器 55から入力されるディジタル化された受信信号 Sを復号化部 23で復号化 し、その復号化された受信データを受信データ処理部 24で処理する。  As shown in the figure, the control unit 2 includes a transmission data generation unit 21 and an encoding unit 22. The transmission data generated by the transmission data generation unit 21 is encoded by the encoding unit 22 and its code The converted transmission data is output as a digital signal to a digital-to-analog converter 41. Further, the control unit 2 includes a decoding unit 23 and a reception data processing unit 24. The digitalization reception signal S input from the analog-to-digital converter 55 is decoded by the decoding unit 23, and the decoding is performed. The received data processing unit 24 processes the digitized received data.
[0024] さらに、制御部 2は FFT処理部 25、チャネル選択処理部 26、 FIFOメモリ 27を備え ている。まず FFT処理部 25は、キャリアセンス時においてアナログディジタル変換器 55から入力されたディジタル信号を用いて高速フーリエ変換処理を行うものである。 すなわち、 FFT処理部 25ではアナログディジタル変換器 55から入力されたディジタ ル量のデータに対して高速フーリエ変換処理を実行する。この高速フーリエ変換処 理により、 FFT処理部 25は、ディジタル信号に含まれる各周波数成分を抽出し、図 5 に示すような周波数帯域ごとの受信電力強度の分布データを取得して出力する。  The control unit 2 further includes an FFT processing unit 25, a channel selection processing unit 26, and a FIFO memory 27. First, the FFT processing unit 25 performs high-speed Fourier transform processing using the digital signal input from the analog-to-digital converter 55 at the time of carrier sensing. That is, the FFT processing unit 25 performs fast Fourier transform processing on the digital amount data input from the analog-to-digital converter 55. By this fast Fourier transform processing, the FFT processing unit 25 extracts each frequency component contained in the digital signal, and acquires and outputs distribution data of received power intensity for each frequency band as shown in FIG.
[0025] 次に、チャネル選択処理部 26は、キャリアセンス時に FFT処理部 25から入力され た周波数帯域ごとの受信電力強度の分布データを FIFOメモリ 27に記憶させる。また 、チャネル選択処理部 26は、 FIFOメモリ 27から読み出した受信電力強度分布デー タに基づいて空きチャネルを評価し、 1チャネル以上の連続した空きチャネル群が複 数個存在する場合にはその中から最適なチャネル群を選択する処理を行う。さらに、 チャネル選択処理部 26は、選択した使用チャネルにおける搬送波 f の伝送速度（通 Next, the channel selection processing unit 26 stores in the FIFO memory 27 distribution data of received power intensity for each frequency band input from the FFT processing unit 25 at the time of carrier sensing. Further, the channel selection processing unit 26 evaluates the idle channel based on the received power intensity distribution data read from the FIFO memory 27 and, when there is a plurality of continuous idle channel groups of one or more channels, among them, Perform processing for selecting an optimal channel group from further, The channel selection processing unit 26 sets the transmission rate of the carrier wave f in the selected used channel (
0  0
信速度）を通信可能な最大速度に変更するために、発信器 3に対して送信信号 Sの  Transmission rate S to the transmitter 3 to change the transmission rate
1 搬送周波数を設定する制御信号 sを出力する。なお、チャネル選択処理については  1 Output the control signal s to set the carrier frequency. In addition, about channel selection processing
3  3
図 5において詳しく説明する。  This will be described in detail with reference to FIG.
[0026] 図 3はパッシブ型 RFIDの通信方式と各通信期間のスペクトル状態を示す図である [0026] FIG. 3 is a diagram showing a communication method of passive RFID and spectrum states of each communication period.
[0027] 上述したように、本実施形態のリーダライタ 1はパッシブ型 RFIDによる通信方式を 採用しており、リーダライタ 1から RFIDタグへと送信される電波は RFIDタグを動作さ せる起電力を供給する役割を担うので、アンテナ 7から高出力で放射される。同図に 示すように、リーダライタ 1から RFIDタグへの通信期間においては、リーダライタ 1の アンテナ 7から読取コマンドが変調波として送信される。このとき、 RFIDタグでは読取 コマンドの復調、解析が行われる。また、コマンド送信時には RFIDタグへの信号の 伝送速度を指定するオプションを付加することができ、毎通信ごとにその伝送速度を 変更することが可能である。なお、同図（b)はチャネル内に帯域制限されたリーダライ タ 1の変調波スペクトルを示して!/、る。 As described above, the reader / writer 1 of the present embodiment adopts a communication method using a passive RFID, and the radio wave transmitted from the reader / writer 1 to the RFID tag causes an electromotive force to operate the RFID tag. As it plays the role of supplying, it is radiated from antenna 7 with high power. As shown in the figure, in the communication period from the reader / writer 1 to the RFID tag, a read command is transmitted as a modulated wave from the antenna 7 of the reader / writer 1. At this time, the RFID tag demodulates and analyzes the read command. In addition, at the time of command transmission, an option can be added to specify the transmission rate of the signal to the RFID tag, and it is possible to change the transmission rate for each communication. Note that (b) of the figure shows the modulated wave spectrum of the reader / writer 1 band-limited in the channel!
[0028] 一方、 RFIDタグからリーダライタ 1への通信期間において、リーダライタ 1はアンテ ナ 7から無変調の連続搬送波 CWを送信している。そして、連続搬送波 CWより少し 遅れて RFIDタグからリーダライタ 1へと返信される電波は、 RFIDタグのアンテナイン ピーダンスがタグ内部のメモリのデータに応じて変化する。これにより、リーダライタ 1 からの電波はタグのアンテナインピーダンスの変化に応じて反射量が変わり、タグの データで変調された微弱な信号として返信される。また、 RFIDタグのインピーダンス 変調速度は、送信コマンド内で指定された伝送速度によって決定される。なお、同図 (c)はリーダライタ 1の連続搬送波 CWと RFIDタグのインピーダンス変化による微弱 な信号の変調波スペクトルを示してレ、る。  On the other hand, in the communication period from the RFID tag to the reader / writer 1, the reader / writer 1 transmits a non-modulated continuous carrier wave CW from the antenna 7. Then, in the radio wave sent back from the RFID tag to the reader / writer 1 slightly later than the continuous carrier wave CW, the antenna impedance of the RFID tag changes in accordance with the data in the memory inside the tag. As a result, the amount of reflection of the radio wave from the reader / writer 1 changes in accordance with the change in the antenna impedance of the tag, and is returned as a weak signal modulated by the tag data. Also, the impedance modulation rate of the RFID tag is determined by the transmission rate specified in the transmit command. The same figure (c) shows the continuous wave CW of the reader / writer 1 and the modulation wave spectrum of a weak signal due to the change in impedance of the RFID tag.
[0029] 図 4は通信速度と周波数帯域の関係を示す図である。  FIG. 4 is a diagram showing the relationship between the communication speed and the frequency band.
[0030] 同図に示すように、リーダライタ 1から RFIDタグへのデータの伝送速度が大きくなる と、影響を受ける周波数帯域が広くなるという特性がある。つまり、通信速度が高速の 場合、使用チャネルに隣接するチャネルにまで上下側波帯の占有帯域が広がり、そ の隣接チャネルで使用されている搬送波の影響を受けやすくなる。 [0030] As shown in the figure, when the data transmission speed from the reader / writer 1 to the RFID tag is increased, there is a characteristic that the affected frequency band is widened. That is, when the communication speed is high, the occupied bands of the upper and lower sidebands extend to the channel adjacent to the used channel, and It is susceptible to the carrier used in the adjacent channel of.
[0031] 例えば図示した例は、リーダライタ 1からの搬送波 f 力 ¾チャネルのときの RFIDタグ For example, in the illustrated example, the RFID tag in the case of carrier f power 3⁄4 channel from reader / writer 1
0  0
の変調波スペクトルを示したものである。データ伝送速度が 40kbps (低速）の場合は 符号化により上側波帯（USB : Upper Side Band)と下側波帯（Lower Side Band)の占 有帯域幅がそれぞれ 80kHzまで広がり、 80kbps (中速）の場合は符号化により同帯 域幅が 160kHzまで広がり、 160kbps (高速）の場合は同帯域幅が 320kHzまで広 力 こと力 Sわ力、る。特に伝送速度を高速に設定した場合には、隣接する n+ 1チヤネ ルに妨害波スペクトルがあると周波数帯域がかぶり、リーダライタ 1と RFIDタグとの間 の通信信頼性が低下してしまう。  The modulated wave spectrum of When the data transmission speed is 40 kbps (low speed), the occupied bandwidth of the upper side band (USB: Upper Side Band) and lower side band (Lower Side Band) is extended to 80 kHz by encoding and 80 kbps (medium speed) In this case, the same bandwidth is extended to 160 kHz by coding, and in the case of 160 kbps (high speed), the bandwidth is extended to 320 kHz. In particular, when the transmission rate is set to a high speed, if there is an interference wave spectrum in the adjacent n + 1 channel, the frequency band is fogged, and the communication reliability between the reader / writer 1 and the RFID tag is reduced.
[0032] そこで、本実施形態のリーダライタ 1は、キャリアセンスによるチャネル評価時に、隣 接するリーダライタの干渉波の強度を統計的に検査し、干渉波の強度に応じて通信 速度を最適値に変化させることにより、リーダライタ 1と RFIDタグとの間の通信効率を 高めるようにしている。 Therefore, the reader / writer 1 of this embodiment statistically inspects the intensity of the interference wave of the adjacent reader / writer at the time of channel evaluation by carrier sense, and optimizes the communication speed according to the intensity of the interference wave. By changing it, the communication efficiency between the reader / writer 1 and the RFID tag is improved.
[0033] 図 5は受信電力強度分布データと空きチャネルの関係を示す図である。 FIG. 5 is a view showing the relationship between received power intensity distribution data and idle channels.
[0034] 上述したように、制御部 2の FFT処理部 25は、キャリアセンス時にアナログディジタ ル変換器 55から入力されたディジタル信号を用いて高速フーリエ変換処理を実行す ることにより、同図のようなチャネル単位で測定された受信電力強度分布データを取 得する。同図において、横軸は UHF帯で使用可能な 9個のチャネル（CH)を示し、 縦軸は受信電力強度（dBm)のレベルを Thl、 Th2、 Th3の 3段階の閾値に分けて 示してめる。 As described above, the FFT processing unit 25 of the control unit 2 performs fast Fourier transform processing using the digital signal input from the analog-to-digital converter 55 at the time of carrier sensing, as shown in FIG. Receive power intensity distribution data measured on a channel-by-channel basis. In the figure, the horizontal axis shows nine channels (CH) usable in the UHF band, and the vertical axis shows the level of the received power (dBm) divided into three thresholds of Th1, Th2, and Th3. I
[0035] ここで、閾値 Thlは高出力型 UHF帯のキャリアセンスレベルとして規定された一 74 dBmに設定されている。そして、図示した例では、測定された受信電力強度が閾値 Thl未満のチャネル、つまり CH2、 CH3、 CH6、 CH9の 4個のチャネルが通信可能 な空きチャネルであることを表わしている。そして、この受信電力強度分布データのよ うに空きチャネルが複数個存在する場合、チャネル選択処理部 26では次のように空 きチャネルの評価をしてから最適なチャネルを選択するとともに、選択した使用チヤ ネルにおける通信速度を決定する。  Here, the threshold Thl is set to one 74 dBm defined as the carrier sense level of the high power type UHF band. And, in the example shown in the figure, it is indicated that channels whose measured received power strength is less than the threshold Thl, that is, four channels of CH2, CH3, CH6 and CH9 are communicable idle channels. Then, when there are a plurality of vacant channels as in this received power intensity distribution data, the channel selection processing unit 26 evaluates the vacant channels as follows and then selects the most suitable channel, and selects the use. Determine the communication speed on the channel.
[0036] 図 6は制御部でのチャネル選択処理の一例を示すフローチャート図である。 [0037] 同図において、まずリーダライタ 1は RFIDタグとの通信に先立ち、アンテナ 7から電 波の送信を停止してキャリアセンスを行う（ステップ 601)。すなわち、リーダライタ 1は 、アンテナ 7と受信部 5を介して UHF帯の全チャネル（CH；!〜 9)で受信電力強度を 測定する。そして、チャネル選択処理部 26は FFT処理部 25からの受信電力強度分 布データに基づレ、て受信電力強度が閾値 Thlのキヤリアセンスレベル（ 74dBm) 未満である空きチャネルを検索する。図 5の例でいえば、 CH2、 CH3、 CH6、 CH9 の 4個のチャネルが空きチャネルに相当する。 FIG. 6 is a flowchart showing an example of channel selection processing in the control unit. In the figure, first, prior to communication with the RFID tag, the reader / writer 1 stops transmission of radio waves from the antenna 7 and performs carrier sense (step 601). That is, the reader / writer 1 measures the received power intensity in all channels (CH;! To 9) of the UHF band via the antenna 7 and the receiving unit 5. Then, based on the received power intensity distribution data from the FFT processing unit 25, the channel selection processing unit 26 searches for an available channel whose received power intensity is less than the carrier sense level (74 dBm) of the threshold value Thl. In the example of Fig. 5, four channels of CH2, CH3, CH6 and CH9 correspond to free channels.
[0038] 次に、チャネル選択処理部 26は、キャリアセンスによって検索された空きチャネル のうち、中レベル以上の空きチャネルが存在するかどうかのチェックを行う（ステップ 6 02)。ここで「中レベル以上の空きチャネル」とは、空きチャネルの中で、隣接した少 なくとも上下両側 1個ずつのチャネルの受信電力強度が共に閾値 Th2未満の条件を 満たすチャネルのことをいう。図 5の例で説明すると次のとおりになる。  Next, the channel selection processing unit 26 checks whether or not there is a vacant channel at a medium level or more among the vacant channels searched by carrier sense (step 602). Here, the “medium level or higher free channel” means a channel that satisfies the condition that the received power strengths of at least one adjacent upper and lower channel among the free channels are both less than the threshold Th2. It will be as follows when explaining with the example of FIG.
[0039] 空きチャネルとして検索されたのは CH2、 CH3、 CH6、 CH9の 4個のチャネルで ある。このうち CH2は、隣上の CH3の受信電力強度が閾値 Th2未満である力 隣下 の CH1の受信電力強度が閾値 Th2を超えているので中レベル以上の空きチャネル に相当せず、低レベルの空きチャネルであると評価される。 CH3は、上下両隣の CH 2と CH4の受信電力強度が共に閾値 Th2未満であるので、中レベル以上の空きチヤ ネルに相当する。 CH6は、上下両隣の CH5と CH7の受信電力強度が共に閾値 Th 2を超えているので、中レベル以上の空きチャネルに相当せず、低レベルの空きチヤ ネルであると評価される。 CH9は、隣上にチャネルがなく受信電力強度が閾値 Th2 未満であり、かつ隣下の CH8の受信電力強度も閾値 Th2未満であるので、中レベル 以上の空きチャネルに相当する。  [0039] Four channels, CH2, CH3, CH6, and CH9, were searched as free channels. Among them, CH2 has a low received power level of CH3 on the next side and a power level of CH1 on the next lower side which is less than the threshold Th2 and therefore it does not correspond to a vacant channel above medium level. It is evaluated as an empty channel. CH3 corresponds to a vacant channel at a medium level or more, since the received power intensities of CH2 and CH4 both adjacent to the upper and lower sides are both less than the threshold Th2. CH6 is evaluated as a low level vacant channel because it does not correspond to a vacant channel above the middle level because both received power strengths of CH5 and CH7 on both upper and lower sides exceed the threshold value Th2. Since there is no channel on the top of CH9 and the received power strength is less than the threshold Th2 and the received power strength of CH8 on the next bottom is also less than the threshold Th2, it corresponds to a vacant channel of medium or higher level.
[0040] 次に、チャネル選択処理部 26は、中レベル以上の空きチャネルの中に、高レべノレ の空きチャネルが存在するかどうかのチェックを行う（ステップ 603)。ここで「高レベル の空きチャネル」とは、中レベル以上の空きチャネルの中で、隣接した少なくとも上下 両隣 2個ずつのチャネルの受信電力強度がすべて閾値 Th3未満の条件を満たすチ ャネルのことをいう。図 5の例で説明すると次のとおりになる。  Next, the channel selection processing unit 26 checks if there is a high-level free channel among the medium level or higher level free channels (step 603). Here, “high level free channel” means a channel that satisfies the condition that the received power strength of at least two adjacent and adjacent channels among the medium level or higher level channels is less than the threshold Th3. Say. It will be as follows when explaining with the example of FIG.
[0041] 中レベル以上の空きチャネルとして検索されたのは CH3、 CH9の 2個のチャネル である。このうち CH3は、隣下 2個の CHIと CH2の受信電力強度が共に閾値 Th3未 満であり、かつ隣上 2個の CH4と CH5の受信電力強度も共に閾値 Th3未満である ので、高レベルの空きチャネルに相当する。一方、 CH9は、隣上には受信電力強度 が閾直 Th3以上のものはないが、隣下 2個目の CH7の受信電力強度が閾直 Th3を 超えているので、高レベルの空きチャネルに相当せず、中レベルの空きチャネルであ ると評価される。 [0041] Two channels, CH3 and CH9, were searched as free channels at medium level or higher It is. Among them, CH3 has high received signal strength because both CH2 and CH2 receive power intensities below the threshold Th3 and both CH4 and CH5 receive power intensities below the threshold Th3. Corresponds to the free channel of On the other hand, CH9 does not have a received power strength that is more than the threshold level Th3 on the adjacent side, but since the received power level of the second lower CH7 exceeds the threshold level Th3, it is not It does not correspond and it is evaluated as a medium level free channel.
[0042] このように、チャネル選択処理部 26は、すべての空きチャネルについて低.中.高の どのレベルに該当するかの評価をした後、次の手順に従って使用チャネルを選択し 、その通信速度を決定する。  Thus, the channel selection processing unit 26 evaluates which level of low, medium and high corresponds to all free channels, and then selects a channel to be used according to the following procedure, and its communication speed Decide.
[0043] はじめに、高レベルの空きチャネルがあるかどうかを判断する（ステップ 604)。ここ で、高レベルの空きチャネルがある場合、その中力 使用チャネルを選択する（ステツ プ 609)。高レベルの空きチャネルについては、図 4で説明したようにデータ伝送速 度を高速（160kbps)に設定して上下側波帯の占有帯域幅が 320kHzまで広がった としても、使用チャネルの上下両隣 2個ずつのチャネルの受信電力強度がすべて閾 値 Th3未満であるので、隣接するチャネルとの電波干渉は起こらない。したがって、 高レベルの空きチャネルを使用する場合には、 LBF (Local Beam Forming)で発信器 3の Lo信号に重み付けをし、変調器 42から出力される RF信号に重み付けを行うこと によって通信可能な最大速度を高速に設定して通信を開始する（ステップ 607)。な お、通信が終了して新たな通信を行う前には必ずステップ 601のキャリアセンスを実 行する。  [0043] First, it is determined whether there is a high level free channel (step 604). Here, if there is a high level free channel, select the medium use channel (step 609). For high-level free channels, as described in Fig. 4, even if the data transmission rate is set to high speed (160 kbps) and the occupied bandwidth of the upper and lower sidebands is extended to 320 kHz, both adjacent upper and lower sides of the used channel 2 Since all the received power strengths of the individual channels are less than the threshold value Th3, radio interference with adjacent channels does not occur. Therefore, when using a high level free channel, it is possible to communicate by weighting the Lo signal of the transmitter 3 with LBF (Local Beam Forming) and weighting the RF signal output from the modulator 42. Set the maximum speed to high speed and start communication (step 607). In addition, before communication is completed and new communication is performed, the carrier sense in step 601 is always performed.
[0044] 図 5の例でいえば、高レベルの空きチャネルである CH3が存在するので、これを使 用チャネルとして選択し、通信速度を高速に設定して通信を行う。なお、高レベルの 空きチャネルが複数個ある場合も考えられる力 この場合にはすべてのチャネルの受 信電力強度が閾値 Thl未満であるので、任意のチャネルを選択すればよい。  In the example of FIG. 5, since CH3 which is a high level free channel exists, it is selected as a use channel, and communication is performed by setting the communication speed at a high speed. In addition, the power that can be considered when there are a plurality of high level free channels is considered. In this case, since the received power strengths of all the channels are less than the threshold Thl, any channel may be selected.
[0045] 一方、高レベルの空きチャネルがない場合には、中レベルの空きチャネルがあるか どうかを判断する（ステップ 605)。ここで中レベルの空きチャネルがある場合には、そ の中力、ら使用チャネルを選択する（ステップ 608)。中レベルの空きチャネルは上下 両隣 1個のチャネルの受信電力強度が閾値 Th2未満であるため、図 4に示したように データ伝送速度を中速（80kbps)に設定しても上下側波帯の占有帯域幅が 160kH zまでしか広がらず、隣接するチャネルとの電波干渉は起こらない。したがって、中レ ベルの空きチャネルを使用する場合には、通信速度を中速に設定して通信を開始す る（ステップ 607)。 On the other hand, if there is no high level free channel, it is judged whether there is a medium level free channel (step 605). If there is a medium level free channel here, select its medium power and its use channel (step 608). As shown in Figure 4, since the received power strength of one channel in the upper and lower adjacent channels is lower than the threshold Th2 in the middle level free channel. Even if the data transmission rate is set to a medium speed (80 kbps), the occupied bandwidths of the upper and lower sidebands are expanded only to 160 kHz, and radio interference with adjacent channels does not occur. Therefore, when using a middle level free channel, the communication speed is set to medium speed and communication is started (step 607).
[0046] さらに、中レベルの空きチャネルもない場合には、低レベルの空きチャネルの中力、 ら使用チャネルを選択する（ステップ 606)。低レベルの空きチャネルは上下両隣の チャネルの受信電力強度が閾値 Th2以上であるため、図 4に示したようにデータ伝 送速度を低速（40kbps)に設定すれば占有帯域幅が 80kHzまでしか広がらず、隣 接するチャネルとの電波干渉は起こらない。したがって、低レベルの空きチャネルを 使用する場合には、通信速度を低速に設定して通信を開始する（ステップ 607)。  Furthermore, if there is no medium level free channel, the medium channel of the low level free channel is selected (step 606). The low-level free channels have reception power strengths of upper and lower adjacent channels that are equal to or higher than the threshold Th2. Therefore, if the data transmission speed is set to low speed (40 kbps) as shown in Figure 4, the occupied bandwidth is broadened to only 80 kHz. There is no radio interference with adjacent channels. Therefore, when using a low level free channel, the communication speed is set to low and communication is started (step 607).
[0047] このように、上述した機能を有するリーダライタ 1によれば、すべての空きチャネルに ついてレベル評価をした後に、隣接チャネルの空き状況に応じて伝送速度を変化さ せるようになつている。これにより、空きチャネルが多い場合は高速でデータを伝送し 、少ない場合は低速でデータ伝送することによって、隣接チャネルの電波干渉による 通信エラーや通信時間の増大などの影響を抑えることができる。このため、固定での チャネル選択方式に比べて大幅に通信効率を高めることが可能になる。なお、同図 で説明したチャネル選択処理に替えて、次のようなチャネル選択処理を採用してもよ い。  As described above, according to the reader / writer 1 having the above-described function, the transmission rate is changed in accordance with the availability of the adjacent channel after the level evaluation is performed on all the available channels. . In this way, by transmitting data at high speed when there are many free channels and transmitting data at low speed when there are few free channels, it is possible to suppress the effects of communication errors and increases in communication time due to radio interference in adjacent channels. As a result, it is possible to greatly improve communication efficiency compared to the fixed channel selection method. The following channel selection process may be employed instead of the channel selection process described in FIG.
[0048] 図 7は制御部でのチャネル選択処理の他の例を示すフローチャート図である。  FIG. 7 is a flowchart showing another example of channel selection processing in the control unit.
[0049] 同図において、まずリーダライタ 1は RFIDタグとの通信に先立ち、アンテナ 7から電 波の送信を停止してキャリアセンスを行う（ステップ 701)。すなわち、リーダライタ 1は 、アンテナ 7と受信部 5を介して UHF帯の全チャネル（CH；!〜 9)で受信電力強度を 測定する。そして、チャネル選択処理部 26は FFT処理部 25からの受信電力強度分 布データに基づレ、て受信電力強度が閾値 Thlのキヤリアセンスレベル（ 74dBm) 未満である空きチャネルを検索する（ステップ 702)。なお、このキャリアセンスによる 空きチャネル検索は、図 6のときと同様である。 In the figure, first, prior to communication with the RFID tag, the reader / writer 1 stops transmission of radio waves from the antenna 7 and performs carrier sensing (step 701). That is, the reader / writer 1 measures the received power intensity in all channels (CH;! To 9) of the UHF band via the antenna 7 and the receiving unit 5. Then, based on the received power intensity distribution data from the FFT processing unit 25, the channel selection processing unit 26 searches for an available channel whose received power intensity is less than the carrier sense level (74 dBm) of the threshold value Thl (step 702). ). The free channel search based on this carrier sense is the same as in FIG.
[0050] 次に、チャネル選択処理部 26は空きチャネル情報を蓄積する（ステップ 703)。す なわち、チャネル選択処理部 26はキャリアセンスによって検索された各チャネルの受 信電力強度のデータを FIFOメモリ 27に蓄積する。この空きチャネル情報の蓄積は キャリアセンスの度に行うようにし、 FIFOメモリ 27に最新の各チャネルのデータを規 定量蓄積していく。 Next, the channel selection processing unit 26 stores free channel information (step 703). That is, the channel selection processing unit 26 receives each channel searched by carrier sense. Data of transmission power strength is stored in the FIFO memory 27. The storage of the free channel information is performed at each carrier sense, and the latest data of each channel is regularly and quantitatively stored in the FIFO memory 27.
[0051] 次!/、で、チャネル選択処理部 26はチャネル履歴情報のチェックを行う（ステップ 70 4)。ここで「チャネル履歴情報」とは、 FIFOメモリ 27に蓄積されている過去のチヤネ ル情報の履歴を用いて算出された空きチャネルの数の平均値のことをいう。過去の チャネル情報は、例えば最新の n回分のデータや現在から n分以内のデータのように 、回数や時間によって直近の各チャネルの電波干渉状態を反映できるデータを採用 するのが好ましい。  At next! /, The channel selection processing unit 26 checks channel history information (step 704). Here, the “channel history information” refers to the average value of the number of free channels calculated using the history of the past channel information stored in the FIFO memory 27. As past channel information, it is preferable to adopt data that can reflect the radio interference condition of each latest channel depending on the number of times and time, such as the latest n data or data within n minutes from the present.
[0052] そして、チャネル選択処理部 26は、チャネル履歴情報のチェックによって過去の平 均空きチャネル数が 3個以上存在するかどうかを判断する（ステップ 705)。ここで過 去の平均空きチャネル数が 3個以上存在する場合には、次に、過去の平均空きチヤ ネル数が 5個以上存在するかどうかを判断する (ステップ 708)。その結果、過去の平 均空きチャネル数が 5個以上存在する場合には、今回のキャリアセンスによって検索 された空きチャネルの中から使用チャネルを選択する（ステップ 710)。過去の平均空 きチャネル数が 5個以上存在すれば、最近に通信を実行した他のリーダライタの台数 が少ないことが推定できるので、 LBFによって伝送速度を最大の高速（160kbps)に 設定して通信を開始する（ステップ 707)。なお、通信が終了して新たな通信を行う前  Then, the channel selection processing unit 26 determines whether or not the average number of vacant channels in the past is three or more by checking the channel history information (step 705). If the past average number of vacant channels is three or more, it is next determined whether the past average number of vacant channels is five or more (step 708). As a result, when the average number of vacant channels in the past is 5 or more, the channel used is selected from the vacant channels searched by the carrier sense this time (step 710). If the average number of free channels in the past is 5 or more, it can be estimated that the number of other readers / writers that have recently executed communication is small, so LBF is used to set the transmission speed to the maximum high speed (160 kbps). Communication is started (step 707). Before the end of communication and new communication
[0053] 一方、ステップ 708において、過去の平均空きチャネル数が 5個以上存在しない場 合にも、今回のキャリアセンスで検索された空きチャネルの中から使用チャネルを選 択するが、ここでは伝送速度を最大よりも低下させた中速（80kbps)に設定する（ステ ップ 709)。そして、伝送速度を中速に設定することにより、上下側波帯の占有帯域 幅を狭めて隣接チャネルとの電波干渉が起こらないようにしてから通信を開始する（ ステップ 707)。 On the other hand, in step 708, even if the average number of vacant channels in the past is not 5 or more, the channel used is selected from among the vacant channels searched by this carrier sense. Set the speed to medium speed (80 kbps) lower than the maximum speed (step 709). Then, by setting the transmission speed to a medium speed, the occupied bandwidths of the upper and lower sidebands are narrowed to prevent radio interference with the adjacent channel, and then communication is started (step 707).
[0054] さらに、ステップ 705において、過去の平均空きチャネル数が 3個以上存在しない 場合にも、今回のキャリアセンスで検索された空きチャネルの中力も使用チャネルを 選択するが、この場合には伝送速度を最小の低速（40kbps)に設定する（ステップ 7 06)。そして、伝送速度を低速に設定することにより、上下側波帯の占有帯域幅をよ り一層狭めて隣接チャネルとの電波干渉が起こらないようにしてから通信を開始する (ステップ 707)。 Furthermore, in step 705, even if the average number of vacant channels in the past does not exist three or more, the medium power of the vacant channels searched by this carrier sense is also selected, but in this case transmission Set the speed to the lowest speed (40 kbps) (Step 7 06). Then, by setting the transmission rate to a low speed, the occupied bandwidths of the upper and lower sidebands are further narrowed to prevent radio interference with adjacent channels, and then communication is started (step 707).
[0055] このように、図 7に示したチャネル選択処理では、キャリアセンスの度に過去のチヤ ネル使用履歴を保持して蓄積してレ、き、通信前に直近の各チャネルの電波状態を参 照できるようにした。これにより、キャリアセンスによって測定した瞬時の空きチャネル 状況ではなぐ蓄積された過去の統計力 空きチャネルの割合を推測し、電波干渉 する恐れがあるリーダライタの台数を推定してそれに応じた伝送速度を決定するよう になっている。このため、より実際の環境に即した効果を発揮することができる。特に 、運用上システム内のリーダライタの設置台数が増減するような環境において好適で ある。また、本例のようなチャネル履歴情報を用いたチャネル選択処理において、図 6のチャネルレベル評価を併用すれば通信効率をより一層向上させることができる。  As described above, in the channel selection process shown in FIG. 7, the past channel use history is held and accumulated every carrier sense, and the radio wave status of each nearest channel is determined before communication. I was able to refer to it. In this way, in the case of instantaneous channel situation measured by carrier sense, the past statistical power accumulated in the channel situation is estimated, the ratio of the vacant channel in the past is estimated, the number of reader / writers that may cause radio interference is estimated, and the transmission speed is determined accordingly. It is supposed to decide. For this reason, it is possible to exhibit an effect more in line with the actual environment. In particular, it is preferable in an environment where the number of installed reader / writers in the system increases or decreases in operation. Also, in channel selection processing using channel history information as in this example, communication efficiency can be further improved by using the channel level evaluation of FIG. 6 in combination.
[0056] なお、上述した実施形態では、本発明の無線通信装置を高出力型 UHF帯のリー ダライタに適用した例を挙げて説明した力 本発明はこれに限られない。キャリアセン スによる混信防止対策が必要なシステムに使用されるものであれば、低出力型 UHF 帯のリーダライタやその他の周波数帯域の通信機器にも同様に適用できる。  Note that in the above-described embodiment, the present invention is not limited to the example described above in which the wireless communication apparatus of the present invention is applied to a high power UHF band reader / writer. The same can be applied to low-power UHF band reader / writers and communication devices in other frequency bands, as long as they are used in systems that require interference prevention measures by carrier sensing.
図面の簡単な説明  Brief description of the drawings
[0057] [図 1]本発明の無線通信装置であるリーダライタの構成を示す図。  FIG. 1 is a view showing the configuration of a reader / writer that is a wireless communication apparatus of the present invention.
[図 2]リーダライタにおける制御部の構成を示す図。  FIG. 2 is a diagram showing the configuration of a control unit in the reader / writer.
[図 3]パッシブ型 RFIDの通信方式と各通信期間のスペクトル状態を示す図。  [Fig. 3] A diagram showing the communication method of passive RFID and the spectrum state of each communication period.
[図 4]通信速度と周波数帯域の関係を示す図。  [Figure 4] Figure showing the relationship between communication speed and frequency band.
[図 5]受信電力強度分布データと空きチャネルの関係を示す図。  [FIG. 5] A diagram showing the relationship between received power intensity distribution data and idle channels.
[図 6]制御部でのチャネル選択処理の一例を示すフローチャート図。  FIG. 6 is a flowchart showing an example of channel selection processing in the control unit.
[図 7]制御部でのチャネル選択処理の他の例を示すフローチャート図。  FIG. 7 is a flowchart showing another example of channel selection processing in the control unit.
[図 8]UHF帯のチャネル配置例を示す図。  [FIG. 8] A diagram showing an example of channel arrangement in the UHF band.
符号の説明  Explanation of sign
[0058] 1 リーダライタ（無線通信装置） 1 Reader / writer (wireless communication device)
2 制御部 21 送信データ生成部 2 Control unit 21 Transmission data generator
22 符号化部  22 Encoding unit
23 復号化部  23 Decryption unit
24 受信データ処理部  24 Received data processing unit
25 FFT処理部  25 FFT processing unit
26 チャネル選択処理部 26 channel selection processing unit
27 FIFOメモリ 27 FIFO memory
3 発信器  3 Transmitter
4 送信部  4 Transmitter
41 ディジタルアナログ変換器 41 Digital to Analog Converter
42 変調器 42 Modulator
43 高周波増幅器  43 High frequency amplifier
5 受信部  5 Receiver
51 帯域制限フィルタ  51 Band-limiting filter
52 ローノイズアンプ 52 Low noise amplifier
53 復調器 53 demodulator
54 増幅器 54 amplifier
55 アナログディジタル変換器 55 Analog to Digital Converter
6 サーキユレータ 6 Circulator
7 アンテナ  7 antenna
8 低域通過フィルタ  8 low pass filter
S 送信信号  S transmission signal
1  1
s 受信信号 s Received signal
s 制御信号 s control signal
3  3
S ベースバンド信号  S baseband signal
4  Four
f 搬送波 f carrier

Claims

請求の範囲 The scope of the claims
[1] 複数個に区分された周波数帯域上のチャネルを 1個または複数個利用してデータ キャリアとの間で無線によるデータ通信を行なう無線通信装置であって、  [1] A wireless communication apparatus for performing wireless data communication with a data carrier using one or more channels on a plurality of divided frequency bands,
データキャリアとの無線通信の前に、所定範囲の連続したチャネル群において、チ ャネル単位で測定された受信電力強度に基づレ、て、周波数帯域が連続した奇数個 の空きチャネルを検索し、  Prior to wireless communication with the data carrier, in a continuous channel group of a predetermined range, based on the received power strength measured on a channel basis, an odd number of free channels having continuous frequency bands are searched,
検索によって抽出された前記の奇数個の連続した空きチャネル全体の周波数帯域 幅が広いほど大きな通信速度に設定して、データキャリアとの通信を開始することを 特徴とする無線通信装置。  A wireless communication apparatus characterized in that the communication speed with a data carrier is set by setting the communication speed to a larger communication speed as the frequency bandwidth of the entire odd number of continuous vacant channels extracted by the search is wider.
[2] データキャリアとの無線通信の前に、所定範囲の連続したチャネル群にお!/、て、チ ャネル単位で測定された受信電力強度に基づいて、第 1の閾値以下の受信電力強 度である空きチャネルを検索して 1つの空きチャネルを抽出し、  [2] Prior to wireless communication with the data carrier, based on the received power strength measured in channel units in continuous channels in a predetermined range, the received power strength below the first threshold is strong. Search for free channels, which are degrees, and extract one free channel,
抽出した前記 1つの空きチャネルの高周波数側に隣接したチャネルの受信電力強 度と、抽出した前記 1つの空きチャネルの低周波数側に隣接したチャネルの受信電 力強度が、共に前記の第 1の閾値よりも大なる第 2の閾値以下である場合に、連続し た奇数個の空きチャネルとすることを特徴とする請求項 1に記載の無線通信装置。  The received power intensity of the channel adjacent to the high frequency side of the one vacant channel extracted and the received power intensity of the channel adjacent to the low frequency side of the one vacant channel extracted are both the first. The radio communication apparatus according to claim 1, wherein when the number is equal to or less than a second threshold value which is larger than the threshold value, a continuous odd number of free channels are used.
[3] 前記の空きチャネルの検索の度にチャネル単位の受信電力強度データを蓄積し、 空きチャネルの探索時に過去の受信電力強度に基づいて空きチャネル状況を推定 して通信速度を設定することを特徴とする請求項 1または 2に記載の無線通信装置。  [3] It is possible to accumulate received power strength data in units of channels each time the search for the above-mentioned free channel, and to estimate the free channel condition based on the received power strength in the past when setting up free channel, and to set the communication speed. The wireless communication device according to claim 1, wherein the wireless communication device is characterized.
PCT/JP2007/071900 2006-12-13 2007-11-12 Wireless communication device WO2008072441A1 (en)

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