JP2008172556A - Compound radio equipment and interference avoidance control method to be used therefor - Google Patents

Compound radio equipment and interference avoidance control method to be used therefor Download PDF

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JP2008172556A
JP2008172556A JP2007004153A JP2007004153A JP2008172556A JP 2008172556 A JP2008172556 A JP 2008172556A JP 2007004153 A JP2007004153 A JP 2007004153A JP 2007004153 A JP2007004153 A JP 2007004153A JP 2008172556 A JP2008172556 A JP 2008172556A
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channel
frequency
timing
wireless device
frequency band
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Kazuhiro Ando
Yuji Hayashino
Kazuhiro Ota
Hidesato Yamazaki
和廣 太田
和弘 安道
秀聡 山崎
裕司 林野
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Matsushita Electric Ind Co Ltd
松下電器産業株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To reduce the risk of detecting a carrier sense erroneous detection in a WLAN device in compound radio equipment to which both a BT device and the WLAN device are mounted, and to avoid mutual interference. <P>SOLUTION: Even if transmission is made from the BT device 3, a radio channel control part 4 stores a table that predetermines an FH channel which is not related to carrier sense in the WLAN device 2 in each WLAN channel, a WLAN channel used by the WLAN device 2 is inputted as use channel information in the radio channel control part 4, the radio channel control part 4 notifies the BT device 3 of available FH channels according to the input, and the BT device 3 determines an FH channel actually used in frequency hopping communication among the available FH channels to perform communication. Consequently, the WLAN device 2 and the BT device 3 avoid mutual interference while reducing the risk of the carrier sense erroneous detection in the WLAN device 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, in an environment where a wireless system that performs communication using a frequency hopping method in the same frequency band and a wireless system that performs communication using another wireless communication method coexist, apparatuses using different methods are arranged close to each other. The present invention relates to a wireless device that performs communication while avoiding mutual interference in an environment (for example, a composite wireless device in which both a BT device and a wireless local area network device are mounted), and an interference avoidance method used therefor.

  A 2.4 GHz band called an ISM (Industry Science Medical) band has an advantage that a user can use a wireless device without a license if the standard defined by the Radio Law is satisfied. Because of this advantage, wireless communication devices for wirelessly connecting electronic devices using the 2.4 GHz band have been actively developed in recent years. As a wireless communication system used in this type of wireless communication apparatus, IEEE802.11b / g, Bluetooth (trademark), and the like are known.

  In the 2.4 GHz band, noise emitted from other electronic devices (for example, a microwave oven) is also likely to exist. Therefore, in consideration of noise resistance, IEEE802.11b / g uses a direct spread spectrum spread (Direct Spread Spectrum; In DSSS, Bluetooth, frequency hopping spread spectrum (FHSS) technology is introduced.

  A wireless communication device compatible with Bluetooth (hereinafter referred to as BT device) is one of 79 frequency channels (hereinafter referred to as FH channels) having a 1 MHz width defined in a frequency band from 2.40 GHz to 2.48 GHz. A frequency hopping method is adopted in which one FH channel is selected and switched over time to perform wireless communication. In this frequency hopping method, FH channel selection is performed so as to repeat at a constant time interval (for example, 625 μs) based on a predetermined pseudo-random algorithm, and communication is performed by assigning one packet data to one FH channel.

  On the other hand, a wireless communication device using IEEE802.11b / g (hereinafter referred to as a WLAN device) does not perform frequency hopping, and has 13 channels (one per channel) defined in the 2.4 GHz ISM band. Communication is performed using one channel (occupied frequency bandwidth corresponding to approximately 20 channels of the BT device) in a fixed manner.

  Therefore, when a BT device and a WLAN device that communicate using the same 2.4 GHz band are present in each other's communication area, radio waves transmitted from each other interfere with each other and interfere with each other's communication. As a method of avoiding the radio wave interference, a technique called adaptive frequency hopping (AFH) is disclosed in Patent Document 1 and Patent Document 2. In this technique, in the BT device, the bit error rate and the packet error rate during communication are measured, or the received signal strength in a slot not communicating between the BT devices is measured. Observe the quality (susceptibility to interference from other systems such as WLAN devices), and perform frequency hopping while avoiding FH channels that have been determined to have radio waves that interfere with their communications. This technology prevents interference.

  However, since this conventional AFH technique is implemented considering only the quality on the BT device side, communication between WLAN devices can be performed by using an FH channel that is determined not to interfere with communication between BT devices. May cause a great deal of interference.

  An example of such a case will be described with reference to FIGS. FIG. 17 is a diagram illustrating an arrangement of an FH channel for which it is determined whether or not a BT device can be used by using a conventional AFH technology, and a channel used by a WLAN device operating in a communication area between the BT devices. In FIG. 17, the FH channel indicated by hatching is an FH channel that can be used because it is determined not to be disturbed by the BT device, and the FH channel that is not usable because it is determined that the white channel is disturbed or received. Channels and black portions schematically show signal spectra transmitted and received by the WLAN device. As shown in FIG. 17, the WLAN device transmits / receives a signal having an occupied frequency band of about ± 10 MHz centering on a frequency of 2437 MHz, and the BT device uses an FH channel excluding the band of the signal transmitted from the WLAN device. Are communicating.

  FIG. 18 shows the communication operation of the WLAN devices (STA1, STA2) and the transmission / reception operation of the BT device (BT1) at a certain time. IEEE802.11b / g employs carrier sense multiple access (CSMA) as a radio channel access method. In CSMA, each wireless device checks (carrier sense) a received signal strength in a band to be transmitted for a predetermined period before transmission, transmits if there is no signal from another device, and further determines if there is a signal. Collision is avoided by performing carrier sense for a period and giving up on transmission. In FIG. 18, the WLAN device STA1 tries to execute carrier sense for a predetermined time (T3-T1) from time T1 when transmission of the WLAN device STA2 is completed in accordance with the regulation of IEEE802.11b / g. Here, if a signal from another wireless device is not detected in STA1 between times T1 and T3, STA1 can start packet transmission at time T3, but WLAN device STA1 and BT device BT1 are close to each other. In this case, even if the BT1 transmits using the FH channel outside the use band of the WLAN device STA1, the WLAN device STA1 detects it as a signal having a signal strength exceeding a predetermined threshold (hereinafter referred to as a false detection). STA1 is further awaited for transmission as shown in FIG.

  This problem is also described in Non-Patent Document 1, section 42.4. For example, as shown in FIGS. 17 and 18, it is assumed that BT1 hops to FH channel F1 in the vicinity of the use band of STA1 and transmits in time slot S within the carrier sense interval of STA1. If STA1 and BT1 operate at intervals of 30 cm and BT1 transmits a signal from the antenna with a transmission power of 0 dBm, the free section propagation loss in the 2.4 GHz band is about 30 dB. Are received with a signal strength of about −30 dBm. In IEEE802.11, the out-of-band attenuation of the signal is determined to be 35 dB or more. Therefore, the received signal outside the band is also attenuated by about 35 dB by the filter in the WARN device STA1, and the signal strength of BT1 detected at STA1 at this time is − It becomes about 65 dBm or less.

  Note that increasing the out-of-band attenuation of the filter generally increases in-band distortion and degrades reception performance. Therefore, the out-of-band attenuation near the use band satisfies the specified value and is designed to be close to the specified value. It is usually done. Therefore, the BT1 signal transmitted through the FH channel F1 in the vicinity of the use band is detected by the STA1 with an intensity of about −65 dBm. IEEE802.11b carrier sense signal detection threshold is -76 dBm. In this case, the signal strength detection value of BT1 exceeds the threshold value even though it is out of band, and STA1 detects the signal of BT1 out of band. As a result of erroneous detection, carrier sense is continued for a predetermined period (from time T2 to time T4) as shown in FIG.

  Since the BT device BT1 uses the conventional AFH technology to select an FH channel that is not disturbed by itself as an FH channel that can be used in advance, the BT device BT1 performs communication during a period from time T3 to T4. Even if it is sent, it will not be disturbed.

  Thus, when the conventional AFH technology is used, in an environment where the BT device and the WLAN device are close to each other, the WLAN device erroneously detects a signal outside the band transmitted from the BT device by carrier sense, Even if the transmission does not cause any interference, the carrier sense is continued without transmission. This causes a problem that the communication throughput of the WLAN device is unnecessarily lowered.

  In the above example, the distance between the WLAN device and the BT device has been described as 30 cm. However, in the future, as shown in FIG. 13, communication between the mobile phone and the headset is performed via Bluetooth, and an access point (AP) between the mobile phone and the WLAN device. A system that communicates with each other using IEEE802.11b / g and makes a call via an IP line of the Internet is also being studied. In such a system, a composite wireless device in which both a WLAN device and a BT device are mounted on one mobile phone is used. In such a composite wireless device, needless to say, the WLAN device and the BT device are arranged in close proximity, and thus the above-described problem of erroneous detection of carrier sense becomes more serious.

  In addition, in the conventional AFH technology, when the use bandwidth of the WLAN device increases, the number of FH channels (hereinafter referred to as good channels) that are determined to be usable without interference by the BT device is insufficient, and the Bluetooth standard In order to satisfy the requirements, some FH channels are selected as usable channels from among the FH channels that do not satisfy the predetermined quality of the BT device due to interference with the WLAN device (hereinafter referred to as bad channels). To use it. For example, as shown in FIG. 14, the WLAN devices STA1 to STA5 and the AP use three channels ch1 (2401 to 2123 MHz), ch6 (2126 to 2148 MHz), and ch11 (2151 to 2173 MHz) of IEEE802.11b / g, respectively. When communicating, using the conventional AFH technology, the BT device BT1 has four FH channels with center frequencies of 2124 MHz, 2125 MHz, 2149 MHz, and 2150 MHz, and seven FH channels with a center frequency between 2174 MHz and 2480 MHz. A total of 11 FH channels are used as frequency hopping frequencies as good channels, but in the FCC (Federal Communications Commission), Hoppi Since it is stipulated that the number of frequency channels to be tuned is 15 channels or more, at least 4 channels are selected from the defective channels and used so that the number of frequency channels to be hopped is 15 channels or more. As a result, the resistance to the interference wave from the WLAN device also deteriorates on the BT device side.

  Non-Patent Document 1 Section 7 and Patent Document 3 disclose a method for avoiding such degradation of interference resistance of the BT device due to a lack of good channels. FIG. 15 is a block diagram showing a configuration of the composite radio apparatus disclosed in Patent Document 3. As shown in FIG. In FIG. 15, the composite wireless device 1 includes a wireless management device 201, a WLAN device 202 that uses the IEEE802.11g standard, a BT device 203, a power supply device 40, and a memory device 205.

  The wireless management device 201 performs frequency management used by the WLAN device 202 and the BT device 203. The power supply device 204 supplies power to the wireless management device 201, the WLAN device 202, and the BT device 203, respectively. In the memory device 205, a control procedure (program) of the wireless management device 201 is written. The composite wireless device 200 obtains the band information currently used from the WLAN device, and obtains the number of FH channels necessary for communication from the BT device.

  When the required number of good channels in the BT device 201 can be secured based on the bandwidth currently used by the WLAN device 202, the composite wireless device 200 can communicate from the FH channels excluding the used bandwidth of the WLAN device 202. The BT device 203 is instructed to determine the frequency hopping pattern of the BT device.

On the other hand, when the number of good channels in the BT device 201 is insufficient, the composite radio device 200 instructs to partially reduce the bandwidth used by the WLAN device 202 in order to secure the number of good channels in the BT device. The WLAN device 202 uses an OFDM (Orthogonal Frequency Division Multiplexing) system as a modulation / demodulation system, and reduces the number of carriers in accordance with the instruction. Then, the composite radio apparatus 200 determines the frequency hopping pattern using the frequency band of the gap generated by the reduction of the use band of the WLAN apparatus 202 and the FH channel included in the frequency band that was not originally used by the WLAN apparatus 202. The BT device 203 is instructed. In this way, the composite device 200 avoids interference between the WLAN device and the BT device. 16A shows a situation where the number of good channels is insufficient, and FIG. 16B shows a situation where channels are used by the WLAN device and the BT device under the situation where the lack of good channels is avoided by the interference avoidance method disclosed in Patent Document 3. It is the conceptual diagram shown. In FIG. 16B, the FH channel used by the BT device 203 and the frequency band used by the WLAN device 202 do not overlap, and the BT device 203 can perform good communication while avoiding interference from the WLAN device 202. I understand.
Japanese Patent No. 3443094 Japanese Patent No. 3770586 JP 2003-234745 A IEEE 802.15.2 standard

  However, the interference avoidance method of Patent Document 3 and the avoidance method of the good channel shortage in the BT device do not consider any carrier sense erroneous detection in the WLAN device, and again, as in the conventional AFH technology, erroneous detection of carrier sense. Therefore, the problem that the communication throughput of the WLAN device is unnecessarily lowered cannot be avoided. On the contrary, in the method of Patent Document 3, since a part of the band normally used by the WLAN device is made to be used by the BT device, the signal of the BT device can be detected at a strong level in the carrier sense period of the WLAN device. Therefore, the risk of erroneous detection of carrier sense is increased as compared with the case of using the conventional AFH technology.

  Therefore, the present invention is for solving the above-described problem, and in an environment where the WLAN device and the BT device are arranged close to each other (for example, a composite wireless device in which both the BT device and the WLAN device are mounted). Providing a composite radio apparatus capable of reducing the risk of erroneous carrier sense detection in a WLAN apparatus and avoiding mutual interference, and an interference avoidance control method used therefor, and having a better channel than conventional AFH technology An object of the present invention is to provide a composite radio apparatus capable of avoiding mutual interference while reducing the probability of shortage, and an interference avoidance control method used therefor.

  According to a first aspect of the present invention, a first wireless device (for example, a BT device) that performs spread spectrum communication by performing frequency hopping and a second wireless device (for example, a WLAN) that uses the same frequency band as the first wireless device. And a frequency included in a predetermined bandwidth adjacent to the use frequency band and the use frequency band by recognizing a use frequency band of the second radio device. It has a radio channel control part which controls so that a frequency may be hopped adaptively to the frequency channel except a channel.

  According to the present invention, in the radio channel control unit, the second radio apparatus not only uses the second radio apparatus based on the use frequency band recognition result of the second radio apparatus but also the second radio apparatus uses the first radio apparatus. Since the control is performed so that the frequency hopping pattern of the BT device is determined except for the FH channel included in a predetermined adjacent frequency band that is judged to have a high risk of erroneous detection of the signal of The risk can be reduced and mutual interference can be avoided.

  According to a second aspect of the present invention, there is provided a composite wireless device in which a first wireless device that performs spread spectrum communication by performing frequency hopping and a second wireless device that uses the same frequency band as the first wireless device are combined. And recognizing a use frequency band of the second wireless device and a timing of performing the predetermined communication operation of the second wireless device, and the frequency hopping according to the timing of performing the predetermined communication operation. And a radio channel control unit that controls to change the frequency channel that can be used and adaptively hop the frequency.

  According to the present invention, the radio channel control unit recognizes the frequency band used by the second radio apparatus and the predetermined communication operation timing such as transmission timing, reception timing, carrier sense timing, etc., and at each timing based on the recognition result. Since control is performed so that the frequency hopping pattern of the BT device is determined using the FH channel included in the predetermined frequency band that does not interfere with the communication operation of the second wireless device, the risk of erroneous detection of carrier sense is reduced. It is possible to reduce and avoid mutual interference. Furthermore, according to the present invention, the band that can be used by the first wireless device is increased or decreased according to the timing, so that the second wireless device erroneously detects the signal of the first wireless device as in the first invention. As compared with the case where the FH channel included in the band determined to have a high risk of being fixed is excluded, it is less likely that the good channel is insufficient.

  Preferably, the timing at which the predetermined communication operation is performed is the reception timing of the second radio apparatus, and the radio channel control unit includes the use frequency band and the frequency included in the predetermined bandwidth adjacent to the use frequency band at the reception timing. The frequency is adaptively hopped in the frequency band excluding the channel, and the frequency channel included in the predetermined bandwidth adjacent to the used frequency band is also used as the usable channel at the timing other than the reception timing, and the frequency is adaptively hopped. It is good to control.

  Thereby, it is possible to avoid mutual interference while reducing the probability that a good channel will be insufficient compared to the case of using the conventional AFH technology.

  Preferably, the reception timing is further preferably carrier sense timing performed by the second radio apparatus before transmission.

  As a result, mutual interference can be avoided while reducing the probability that a good channel will be insufficient and the risk of erroneous detection at the time of carrier sensing compared to the case of using the conventional AFH technology.

  Preferably, the timing for performing the predetermined communication operation is the transmission timing of the second radio apparatus, and the radio channel control unit sets all frequency channels included in the use frequency band as unusable channels at timings other than the transmission timing. The transmission timing may be controlled so as to adaptively hop the frequency as a usable frequency channel for a predetermined frequency channel included in the used frequency band in addition to the outside of the used band.

  Thereby, it is possible to avoid mutual interference while reducing the probability that a good channel will be insufficient compared to the case of using the conventional AFH technology.

  Preferably, the timing at which the predetermined communication operation is performed is the transmission timing, the reception timing, and the carrier sense timing of the second radio apparatus, and the radio channel control unit includes the transmission timing within the use frequency band in addition to the use band. The specified frequency channel included is also a usable frequency channel, the carrier frequency is used for the carrier sense timing, and the frequency channel included in the specified bandwidth adjacent to the used frequency band is the unusable frequency channel, and is transmitted at the reception timing. Of the frequency channels that can be used at the timing, a predetermined frequency channel may be used as an unusable frequency channel so that the frequency is adaptively hopped.

  Thereby, it is possible to avoid mutual interference while reducing the probability that a good channel is insufficient compared to the case of using the conventional AFH technology and reducing the risk of erroneous detection during carrier sensing.

  According to the present invention, in an environment where a WLAN device and a BT device are arranged close to each other, the risk of erroneous carrier sense detection in the WLAN device can be reduced, and the probability that a good channel is insufficient compared to the conventional AFH technology. Provided are a composite radio apparatus capable of avoiding mutual interference while reducing the interference avoidance control method used therefor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a composite radio apparatus to which an interference avoidance control method according to Embodiment 1 of the present invention is applied. In FIG. 1, the composite wireless device 1 includes a WLAN device 2, a BT device 3, and a wireless channel control unit 4. The WLAN device 2 further includes a WLAN radio unit 21, a carrier sense unit 22, and a WLAN communication control unit 23.

  This interference avoidance control method is used to prevent signal interference between a plurality of types of wireless communication systems using the same frequency band. In this embodiment, as a plurality of types of wireless communication methods, the WLAN device 2 performs communication using a method compliant with the IEEE802.11b standard, and the BT device 3 uses a method compliant with the Bluetooth standard.

  In the wireless communication system of the Bluetooth standard, spread spectrum communication of frequency hopping (FH: Frequency Hopping) is used as described in the related art section. The 2.4 GHz frequency band is divided into 79 frequency channels (hereinafter referred to as FH channels) at 1 MHz intervals, and is basically used in a time division manner for each time slot based on the hopping pattern. Communication is performed by switching the frequency channel to be performed. The wireless communication system of the Bluetooth standard is performed by a master / slave system, and management of a hopping pattern is performed by a master. Using the same hopping pattern, a wireless network called a piconet can be formed and communicated between one master and up to seven slaves.

  In the wireless communication system of the IEEE802.11b standard, a spread spectrum communication of a direct spread (DS) system is used. In the 2.4 GHz frequency band, 14 frequency channels (hereinafter referred to as WLAN channels) are allocated at intervals of about 5 MHz, and one or more arbitrary frequency channels are selected from the 14 frequency channels. Can be used. The form of the wireless network includes an ad hoc network mode used for communication between wireless terminals in an area called BSA (Basic Service Area), and an infrastructure composed of a plurality of wireless terminals and an access point (AP). There is a structure mode. In order to prevent a signal collision on a wireless network, a carrier sense / collision avoidance function called CSMA / CA (carrier sense multiple access collision avidity: CSMA / CA) is provided.

  In the WLAN device 2, the WLAN radio unit 21 includes an antenna, a transmission / reception signal amplifier, a filter, a modem, a PLL (Phase Locked Loop) synthesizer, a baseband processing circuit, and the like. Demodulate the spread spectrum radio signal. At the time of transmission, transmission data input from the WLAN communication control unit 23 is generated into a packet of a predetermined format. When a transmission start signal is input from the WLAN communication control unit 23, the generated packet is subjected to modulation processing and a DS spectrum. Output from the antenna as a spread radio signal. Further, the WLAN radio unit 21 detects the signal strength of the signal input from the antenna at a timing other than the transmission timing, and outputs the detected value to the carrier sense unit 22. The carrier sense unit 22 sends a transmission OK signal indicating that the channel is free to the WLAN communication control unit 23 when the value is equal to or less than the predetermined time of −76 dBm. The carrier sense unit is implemented as a functional block of the baseband unit that is a component of the WLAN radio unit 21 in mounting. However, since the carrier sense unit is an important function taken up as a problem in the present invention, the WLAN radio unit It is clearly indicated from 21.

  The WLAN communication control unit 23 is a media access controller (MAC: Media Access Control) having an interface function (corresponding to a data link layer function in TCP / IP) with a host computer (not shown) or the WLAN wireless unit 21. It is composed of a memory or the like in which a wireless access method (program) is written, outputs transmission data to the WLAN wireless unit 21, and transmits a transmission start signal to the WLAN wireless unit 21 when a transmission OK signal is input from the carrier sense unit 22. Is output. Note that if the transmission OK signal has already been input before the transmission request signal is input, the WLAN communication control unit 23 outputs a transmission start signal to the WLAN radio unit 21 simultaneously with the transmission data output.

  After the power is turned on, the WLAN device 2 first enters a reception state, sequentially switches the WLAN channel to be received, searches for which WLAN channel is used by other peripheral WLAN devices, and communicates with the peripheral WLAN device that is the communication partner. Determines which WLAN channel it uses to communicate with. Then, the WLAN channel used by itself and the WLAN channel estimated to be used by other peripheral WLAN devices are transmitted to the wireless channel control unit 4 as usage channel information.

  The WLAN device 2 changes the WLAN channel to be used in accordance with a predetermined protocol when it becomes necessary to change the WLAN channel to be used because the quality of the WLAN channel being used deteriorates. In that case, the WLAN communication control unit 23 outputs the used channel information to the radio channel control unit 4 every time a change in the used WLAN channel occurs.

  As shown in FIG. 2, the wireless channel control unit 4 determines, for each WLAN channel, a channel that cannot be used as an FH channel (unusable channel in FIG. 2) when a peripheral WLAN device uses that frequency channel. When the WLAN device 2 in the composite device uses the frequency, it has a channel table in which channels that cannot be used as the FH channel (error detection risk channel in FIG. 2) are set in advance. The wireless channel control unit 4 collates the used channel information input from the WLAN communication control unit 23 with the channel table of FIG. 2 and uses the 79 FH channels each having a bandwidth of 2402 MHz to 2480 MHz as a WLAN device. 2 is determined as an available FH channel, except for an erroneously detected danger channel corresponding to a WLAN channel used by the network 2 and an unusable channel corresponding to a WLAN channel presumed to be used by other neighboring WLAN devices. And output to the BT device 3 as usable FH channel information.

  For example, in the environment as shown in FIG. 14, the WLAN device 2 (STA1 in FIG. 14) communicates with the AP on the sixth channel (2426 MHz to 2448 MHz) of the WLAN channel, and the other STA2 and STA3 communicate with the first channel (2401 MHz to 2423 MHz), when it is estimated that STA4 and STA5 are communicating with each other at the 14th channel (2473 MHz to 2495 MHz), the radio channel control unit 4 checks the table of FIG. The BT apparatus 3 is notified as usable FH channel information that there are 19 FH channels currently available from 2454 MHz to 2473 MHz.

  The erroneous detection danger channel stored in the channel table described above is, for example, which channel out of 76 FH channels for each WLAN channel is used before the factory shipment, and the carrier sense unit 22 does not output the transmission OK signal. An FH channel that is measured for each WLAN channel and does not output a transmission OK signal due to erroneous detection of carrier sense may be determined as a false detection risk channel. The unusable channel stored in the channel table is, for example, the WLAN device 2 communicated at a predetermined communication distance (for example, 10 m) before shipment from the factory, and which FH channel is used for a predetermined packet error rate (for example, 1 %) May not be satisfied, and the FH channel that cannot be satisfied may be determined as an unusable channel for each WLAN channel. Alternatively, the strength with which the transmission signal of the BT device 3 enters the WLAN device 2 varies slightly depending on the usage environment due to differences in the reflection of radio waves on the wall. Alternatively, every time the power is turned on, an erroneous detection risk channel for each WLAN channel may be determined and written in the table.

  FIG. 3 is a block diagram showing a configuration of the BT device 3 of FIG. In FIG. 3, the BT device 3 includes a frequency hopping channel determination unit 30, an RF unit 31, a baseband unit 32, a link management unit 33, a host controller interface unit 34, a power supply unit 35, a memory unit 36, It is composed of

  The RF unit 31 includes an antenna, a transmission / reception signal amplifier, a filter, a modem, a PLL synthesizer, and the like, and modulates and demodulates a radio signal.

  The frequency hopping channel determination unit 30 uses the usable FH channel input from the radio channel control unit 4 as a good channel, and if the required number of good channels is necessary, the FH channel that is actually used as a communication channel from among the good channels To decide. If the number of good channels is less than the required number, an FH channel shortage signal indicating the number of good channels shortage is output to the radio channel controller 4. The radio channel control unit 4 that has received the FH channel shortage signal determines the shortage of FH channels as quasi-usable FH channels in accordance with a predetermined determination rule, and notifies the BT device 3 thereof. The BT device 3 notified of the quasi-usable FH channel determines that the quasi-usable FH channel is a quasi-good channel and the good channel and the quasi-good channel are FH channels used for communication.

  As the semi-usable FH channel determination rule of the wireless channel control unit 4, for example, it is estimated that other WLAN devices are used except for a false detection danger channel corresponding to the WLAN channel used by the WLAN device 2. Out of the FH channels included in each WLAN channel, the FH channel is selected as a semi-usable FH channel in order of increasing distance from the center frequency of the WLAN channel until the shortage is alternately high and low. What is necessary is to make up for the shortage of channels.

  According to the rules of this example, the WLAN channel 2 uses the 6th channel (2426 MHz to 2448 MHz) of the WLAN device 2 as in the previous example, and the other STA2 and STA3 are the first channel (2401 MHz to 2423 MHz), STA4 and When it is estimated that the STA 5 is using each of the 14th channels (2473 MHz to 2495 MHz), the usable FH channels are 19 from 2454 MHz to 2473 MHz, but the FH that needs to be used in the BT device 3 If the number of channels is 22, the BT device 3 notifies that the number of good channels is insufficient. The radio channel control unit 4 notifies the BT apparatus 3 of three FH channels of 2475 MHz, 2402 MHz, and 2474 MHz as quasi-usable FH channels except for 2421 MHz to 2453 MHz of the first channel and the 14th channel, and the BT device 3 Twenty-two FH channels, which are all usable FH channels (19 from 2454 MHz to 2473 MHz) previously notified as semi-good channels, are actually used for frequency hopping communication.

  The baseband unit 32 is configured by a DSP or the like, and is connected to another BT device that transmits and receives data, exchanges data, and the frequency of the FH channel actually used for frequency hopping communication determined by the frequency hopping channel determination unit 30 Set the hopping pattern.

  The link management unit 33 is configured by a DSP or the like, and establishes a link between devices and controls security. The host controller interface unit 34 is an interface for an application to access the BT device 3 side.

  The power supply unit 35 supplies power to the RF unit 31, the baseband unit 32, the link management unit 33, the host controller interface unit 34, and the memory unit 36, respectively. The memory unit 36 is composed of a flash memory or the like, and a connection procedure for the baseband unit 32 and the link management unit 33 is written therein.

  In this embodiment, the BT device 3 functions as a master station, and the BT device 3 stores information on the FH channel actually used for frequency hopping communication determined by the frequency hopping channel determination unit 30 in a packet of a predetermined frame format. , And transmit to the peripheral slave station that is the communication partner. The peripheral slave station that has received the packet and the BT device 3 that is the master station use the determined FH channel as a communication channel and perform frequency hopping communication.

  As described above, according to the present embodiment, the wireless channel control unit 4 holds a table in which FH channels that are not subject to carrier sense in the WLAN device 2 even if transmitted from the BT device 3 are predetermined for each WLAN channel. The WLAN channel used by the device 2 is input to the wireless channel control unit 4 as usage channel information, and the FH channel that can be used by the wireless channel control unit 4 is transmitted to the BT device 3 according to the input, and the BT device 3 uses the FH channel. Communication is performed by determining an FH channel to be actually used for frequency hopping communication from among possible FH channels. Thereby, the WLAN device 2 and the BT device 3 can perform communication while avoiding the risk of erroneous carrier sense detection in the WLAN device 2 and avoiding mutual interference.

  In the present embodiment, when there are not enough good channels, the radio channel control unit 4 selects a high frequency and a low frequency alternately according to the rules described above until the number of shortage becomes a quasi-usable FH channel. The BT device 3 is notified and all the semi-usable FH channels notified by the BT device 3 are used as semi-good FH channels. However, the present invention is not limited to this, and the radio channel control unit 4 can use the semi-usable FH channels. May be selected and used as a quasi-good FH channel from the quasi-usable FH channels notified by the BT device 3 and selected.

  The BT device 3 is notified, and the BT device 3 selects the number of FH channels that exactly match the shortage from the quasi-usable FH channels to make the quasi-good FH channel. Not limited to this. For example, the radio channel control unit 4 may be used.

(Embodiment 2)
FIG. 4 is a diagram showing a configuration of a composite radio apparatus to which the interference avoidance control method according to Embodiment 2 of the present invention is applied. 4, blocks having the same reference numerals as those in FIG. 1 and FIG. 2 have the same functions and operations as those in FIG. 1 and FIG.

  The composite radio apparatus 11 of the present embodiment differs from the first embodiment in the functions of the radio channel control unit and the WLAN communication control unit. The WLAN communication control unit 231 according to the second embodiment gives communication timing information indicating what communication state the WLAN device 2 is currently in to the radio channel control unit 41 in addition to the use channel information.

  Although there are various communication states of the WLAN device, in this embodiment, the communication state given from the WLAN communication control unit 231 to the wireless control unit 41 is a state in which transmission data is transmitted as a wireless signal (hereinafter referred to as transmission timing). ), There is no data to be transmitted, waiting for a signal from another WLAN device or receiving a signal from another WLAN (hereinafter referred to as reception timing), there is data to be transmitted and transmission is performed Therefore, there are three states in which carrier sense is performed (hereinafter referred to as carrier sense timing).

  As shown in FIG. 7, the radio channel control 41 includes an FH channel that cannot be used at the transmission timing of the WLAN device 20 (unusable channel at the time of transmission), an FH channel that cannot be used at the carrier sense timing of the WLAN device 20 (an erroneous detection risk channel), In addition, an FH channel that cannot be used at the reception timing of the WLAN device 20 (a channel that cannot be used during reception) is internally stored in a channel table that is predetermined for each WLAN channel. Then, based on the used channel information and the communication timing information given from the WLAN communication control unit 231, the FH channel that can be used is determined by checking the channel table. Note that, for the WLAN channel presumed to be used by another WLAN device that is not communicating with the WLAN device 20, in this embodiment, reference is made to the unusable channel at the time of reception.

  Also here, when the number of usable FH channels notified by the radio channel control unit 41 is less than the number of FH channels that the BT device 3 wants to use, that is, when there are not enough good channels, as in the first embodiment, Except for the false detection danger channel corresponding to the WLAN channel used by the WLAN device 20, among the FH channels included in each WLAN channel estimated to be used by other WLAN devices, from the center frequency of the WLAN channel The FH channel is selected as the quasi-usable FH channel until the shortage of alternating high and low frequencies in order from the far side, and notified to the BT device 3, and the quasi-usable FH channel notified by the BT device 3 Are all used as quasi-good FH channels.

  As an example, in the environment as shown in FIG. 14, the WLAN device 20 (STA1 in FIG. 14) communicates with the AP on the sixth channel (2426 MHz to 2448 MHz) of the WLAN channel, and the other STA2 and STA3 communicate with the first channel (2401 MHz). To 2423 MHz), and when the STA4 and STA5 are estimated to communicate with each other on the 13th channel (2461 MHz to 2483 MHz), the usable FH channel notified from the radio channel control unit 41 to the BT device 3 and semi-usable FIG. 8 shows an arrangement relationship between the FH channel and the used channel of the WLAN device. Here, the minimum number of FH channels required for performing frequency hopping communication in the BT device 3 is 15 or more.

  At the transmission timing of the WLAN device 20 as shown in FIG. 8A, the wireless channel control unit 41 compares the table of FIG. 7 with 16 currently available FH channels from 2424 MHz to 2426 MHz and 2448 MHz to 2460 MHz. (The hatched channel in FIG. 8a) is notified to the BT device 3 as usable FH channel information. The BT device 3 actually uses the notified 16 usable FH channels as good channels for frequency hopping communication.

  Further, as shown in FIG. 8B, at the reception timing of the WLAN device 20, the wireless channel control unit 41 compares the table of FIG. 7 with the currently available FH channels of 2424 MHz, 2425 MHz, 2449 MHz to 2460 MHz. It is notified to the BT device 3 as usable FH channel information that there are 14 (the hatched channel in FIG. 8b). Then, the BT device 3 notifies the radio channel control unit 41 that one good channel is insufficient. Then, the radio channel control unit 41 selects 2461 MHz as the semi-usable FH channel (white channel in FIG. 8B) as the semi-usable FH channel, and notifies the BT device 3 of it. The BT device 3 actually uses 15 FH channels including the notified 14 good FH channels as the semi-good FH channel and the previously notified 14 good FH channels for frequency hopping communication.

  Further, at the time of carrier sense timing of the WLAN device 20 as shown in FIG. 8C, the fact that there are eight currently available FH channels from 2453 MHz to 2460 MHz (the hatched channel in FIG. 8C) is usable FH channel information. The BT device 3 is notified. Then, the BT device 3 notifies the radio channel control unit 41 that seven good channels are insufficient. Then, the radio channel control unit 41 selects 7 of 2461 MHz, 2462 MHz, 2402 MHz, 2463 MHz, 2403 MHz, 2480 MHz, and 2404 MHz (white-painted channels in FIG. 8B) as the semi-usable FH channels, and notifies the BT device 3 of them. The BT device 3 actually uses 15 FH channels, which are the notified 7 quasi-usable FH channels as the quasi-good FH channels, and the 8 good FH channels previously notified for frequency hopping communication.

  FIGS. 9 to 12 are flowcharts showing the operations of the carrier sense unit 22, the WLAN control unit 23, the radio channel control unit 41, and the frequency hopping channel determination unit 30.

  As described above, in the decoding apparatus according to the present embodiment, not only the information on the channel used on the WLAN side (including the channel estimated to be used) but also the communication status of the WLAN apparatus is taken into account. Since the FH channel to be used in the apparatus is determined, the period for prohibiting the use of a band larger than the WLAN use band on the BT side as a false detection prohibition channel can be limited to avoid erroneous detection of carrier sense. Even in an environment where many are used, communication avoiding erroneous carrier sense detection of the WLAN device and mutual interference is performed as in the first embodiment, while avoiding the shortage of good channels compared to the first embodiment. be able to.

  In the first and second embodiments, the BT apparatus determines the FH channel that is actually used for communication based only on the usable channel information and the quasi-usable channel information obtained from the radio channel control unit. It is also possible to use interference avoidance control that combines the interference avoidance control method of Patent Documents 1 and 2 described in the prior art and the method of the present invention.

(Embodiment 3)
FIG. 5 is a diagram showing a configuration of a composite radio apparatus according to Embodiment 3 of the present invention that uses interference avoidance control in which the interference avoidance control methods of Patent Documents 1 and 2 and the method of the present invention are combined. 5, blocks having the same reference numerals as those in FIG. 1 perform the same functional operations as those in FIG.

  The present embodiment and the first embodiment are different in the BT apparatus. FIG. 6 is a configuration diagram of the BT apparatus 301 according to Embodiment 2 of the present invention. It differs from the BT device 3 of the first embodiment in that the BT device 301 has a channel quality detection unit 37.

  Hereinafter, the operation of the BT device 301, which is a difference from the first embodiment, will be described.

  The frequency hopping channel determination unit 301 determines each FH channel used for communication based on the BER of each communication channel obtained by the channel quality detection unit 37 and the usable FH channel information obtained from the radio channel control unit 4. .

  The channel quality detection unit 37 is, for example, a baseband unit for evaluating the communication performance for each communication channel used by the BT device 301, similarly to the BER detection unit and the interference channel discrimination described in Patent Document 1. The error rate (BER) of the data demodulated in (1) is monitored for each communication channel, and if the BER of a certain communication channel is continuously higher than a reference value for a certain period, the communication channel interferes with other wireless communication systems. Is determined to be an interference channel.

  The frequency hopping channel determination unit 301 performs control for stopping the use of the communication channel that is determined to be an interference channel by the channel quality detection unit 37. As a result, the communication channel determined to be an interference channel is excluded from the hopping target communication channel.

  In the BT device according to the present embodiment, at the start of a so-called communication connection phase in which communication for data transfer between BT devices is performed, the radio channel control unit 4 uses the 79 communication channels. Since all the FH channels that can be used are used while being switched, BER monitoring is performed for each of the FH channels that can be used from the radio channel control unit 4 out of 79 communication channels. . Therefore, unlike the method of Patent Document 1, it is not necessary to randomly check the quality of the communication channel across all 79 in the initial stage of communication, and a channel with quality degradation due to an interference wave from a limited communication channel. Therefore, compared with the method of Patent Document 1, an interference channel can be found early and excluded from the hopping target channel with a high probability. Therefore, even if interference occurs with surrounding WLAN devices or BT devices that are not communicating with the BT device 301 and communication quality deteriorates, the method of Patent Document 1 returns from the interference state to the state without interference. It can be done earlier.

  Also, according to the interference avoidance control method of the present embodiment, the FH channel to be used is determined in consideration of the reception quality at the BT device, so that the WLAN device 2 has been transmitting for a long period of time, or the WLAN device 2 Even when the communication channel usage status of the surrounding WLAN device is not known for a long period of time due to the power being turned off or in the sleep state, it is possible to perform communication while avoiding interference between the BT device 301 and the surrounding WLAN.

  In the first to third embodiments described above, the composite device has a configuration in which the wireless channel control unit of the WLAN device and the BT device is interposed, and in the wireless channel control unit, channel information and WLAN device used on the WLAN device side. If the BT device uses it for frequency hopping communication, it will not only avoid normal interference but also avoid misdetection of carrier sense based on the information obtained. Although no usable FH channel is determined and the usable FH channel is notified to the BT device, the configuration is not limited to this. For example, a radio channel control unit having the above-described functions is built in the BT device. Alternatively, it may be built in the WLAN device.

  The present invention avoids the risk of erroneous carrier sense detection in a WLAN device in an environment where the WLAN device and the BT device are arranged close to each other (for example, a composite wireless device in which both the BT device and the WLAN device are mounted), and It is useful as a composite radio apparatus capable of avoiding mutual interference and an interference avoidance control method used therefor.

The figure which shows the structure of the composite radio | wireless apparatus in Embodiment 1 of this invention. Frequency channel table diagram possessed by radio channel controller in Embodiment 1 of the present invention The figure which shows the structure of BT apparatus in Embodiment 1 of this invention. The figure which shows the structure of the composite radio | wireless apparatus in Embodiment 2 of this invention. The figure which shows the structure of the composite radio | wireless apparatus in Embodiment 3 of this invention. The figure which shows the structure of BT apparatus in Embodiment 3 of this invention. Frequency channel table diagram possessed by radio channel controller in Embodiment 2 of the present invention Arrangement of usable FH channels in the second embodiment of the present invention The figure which shows the timing relationship between the communication timing of the WLAN apparatus in Embodiment 2 of this invention, and the frequency hopping pattern of a BT apparatus. The flowchart which shows the procedure in which the composite apparatus in Embodiment 2 of this invention determines a frequency hopping pattern. The flowchart which shows operation | movement of the radio channel control part 41 in Embodiment 2 of this invention. The flowchart which shows the operation | movement of the frequency hopping channel determination part 30 in Embodiment 2 of this invention. System diagram showing scenes of use of the present invention System diagram showing scenes of use of the present invention The figure which shows the structure of the conventional compound apparatus described in patent document 3 Frequency channel arrangement diagram when avoiding interference in the conventional composite device described in Patent Document 3 Frequency channel layout when BT device avoids interference with WLAN device using conventional AFH technology Explanatory diagram of problems when interference avoidance is implemented using conventional technology

Explanation of symbols

1, 11, 12, 200 Compound device 2, 20, 202 WLAN device 3, 301, 203 BT device 4, 41 Wireless channel control unit 21 WLAN radio unit 22 Carrier sense unit 23 WLAN communication control unit 30 Frequency hopping channel determination unit 31 RF unit 32 Baseband unit 33 Link management unit 34 Host controller interface unit 35 Power supply unit 36 Memory 37 Channel quality detection unit 201 Wireless management device 204 Power supply device 205 Memory device

Claims (12)

  1. A composite wireless device that combines a first wireless device that performs spread spectrum communication by performing frequency hopping and a second wireless device that uses the same frequency band as the first wireless device,
    Recognizing the use frequency band of the second radio apparatus and adaptively hopping the frequency channels except for the use frequency band and a frequency channel included in a predetermined bandwidth adjacent to the use frequency band. A composite radio apparatus comprising a radio channel controller for controlling.
  2. A composite wireless device that combines a first wireless device that performs spread spectrum communication by performing frequency hopping and a second wireless device that uses the same frequency band as the first wireless device,
    Recognizing the use frequency band of the second wireless device and the timing for performing the predetermined communication operation of the second wireless device,
    A composite radio apparatus comprising: a radio channel control unit that controls a frequency channel that can be used for the frequency hopping to be changed and adaptively hopped according to a timing at which the predetermined communication operation is performed. .
  3. The timing at which the predetermined communication operation is performed is a reception timing of the second wireless device,
    The radio channel controller is
    In the reception timing, the frequency band is adaptively hopped to a frequency band excluding a frequency channel included in the use frequency band and a predetermined bandwidth adjacent to the use frequency band,
    3. The timing other than the reception timing is controlled so that a frequency channel included in a predetermined bandwidth adjacent to the use frequency band is adaptively hopped as an available channel. Composite wireless device.
  4. 4. The composite radio apparatus according to claim 3, wherein the reception timing is a carrier sense timing that is performed by the second radio apparatus before transmission.
  5. The timing for performing the predetermined communication operation is a transmission timing of the second wireless device,
    The radio channel controller is
    At timings other than the transmission timing, all frequency channels included in the use frequency band are unusable channels,
    3. The composite radio apparatus according to claim 2, wherein at the transmission timing, control is performed so that a predetermined frequency channel included in the use frequency band is adaptively hopped as a usable frequency channel.
  6. The timing for performing the predetermined communication operation is a transmission timing, a reception timing, and a carrier sense timing of the second wireless device,
    The radio channel controller is
    In the transmission timing, a predetermined frequency channel included in the use frequency band is a usable frequency channel,
    In the carrier sense timing, a frequency channel included in the use frequency band and a predetermined bandwidth adjacent to the use frequency band is an unusable frequency channel, and the reception timing is usable at the transmission timing. 3. The composite radio apparatus according to claim 2, wherein control is performed so that a predetermined frequency channel among the frequency channels thus used is an unusable frequency channel and the frequency is hopped adaptively.
  7. In a composite wireless device in which a first wireless device that performs spread spectrum communication by performing frequency hopping and a second wireless device that uses the same frequency band as the first wireless device are combined, interference between each other is prevented. An interference avoidance control method to avoid,
    Recognizing a used frequency band of the second wireless device;
    Selecting a recognized frequency channel and a frequency channel excluding a frequency channel included within a predetermined bandwidth adjacent to the used frequency band as a good frequency hopping channel,
    An interference avoidance control method, comprising: selecting a communication channel to be actually used for communication from among the good frequency hopping channels and performing control so as to adaptively hop the frequency.
  8. In a composite wireless device in which a first wireless device that performs spread spectrum communication by performing frequency hopping and a second wireless device that uses the same frequency band as the first wireless device are combined, interference between each other is prevented. An interference avoidance control method to avoid,
    Recognizing a use frequency band of the second wireless device and a timing for performing a predetermined communication operation of the second wireless device;
    Changing a good frequency hopping channel that can be used for the frequency hopping according to the recognized timing of performing the predetermined communication operation,
    An interference avoidance control method, comprising: selecting a communication channel to be actually used for communication from among the good frequency hopping channels and performing control so as to adaptively hop the frequency.
  9. The timing at which the predetermined communication operation is performed is a reception timing of the second wireless device,
    The radio channel controller
    In the reception timing, the frequency band is adaptively hopped to a frequency band excluding a frequency channel included in the use frequency band and a predetermined bandwidth adjacent to the use frequency band,
    9. The timing other than the reception timing is controlled so that a frequency channel included in a predetermined bandwidth adjacent to the use frequency band is adaptively hopped as an available channel. Interference avoidance control method.
  10. The interference avoidance control method according to claim 9, wherein the reception timing is a carrier sense timing that is performed by the second radio apparatus before transmission.
  11. The timing for performing the predetermined communication operation is a transmission timing of the second wireless device,
    The radio channel controller
    At timings other than the transmission timing, all frequency channels included in the use frequency band are unusable channels,
    9. The interference avoidance control method according to claim 8, wherein, at the transmission timing, control is performed so that a predetermined frequency channel included in the use frequency band is adaptively hopped as a usable frequency channel.
  12. The timing for performing the predetermined communication operation is a transmission timing, a reception timing, and a carrier sense timing of the second wireless device,
    The radio channel controller
    In the transmission timing, a predetermined frequency channel included in the use frequency band is a usable frequency channel,
    In the carrier sense timing, a frequency channel included in the use frequency band and a predetermined bandwidth adjacent to the use frequency band is an unusable frequency channel, and the reception timing is usable at the transmission timing. 9. The interference avoidance control method according to claim 8, wherein control is performed so that a predetermined frequency channel among the frequency channels thus used is an unusable frequency channel and the frequency is hopped adaptively.
JP2007004153A 2007-01-12 2007-01-12 Compound radio equipment and interference avoidance control method to be used therefor Pending JP2008172556A (en)

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