JP2013118559A - Radio communication device and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement both of carrier sense operation and demodulation operation while keeping satisfactory performance.SOLUTION: A band variable band-pass filter 106 restricts a pass band of a reception signal. A reception signal strength measurement part 107 measures the reception signal strength of a reception signal which has passed through the band variable band-pass filter 106. A carrier sense determination part 108 performs carrier sense determination on the reception signal on the basis of the reception signal strength. A demodulation part 109 demodulates the reception signal which has passed through the band variable band-pass filter 106, in parallel with measurement of the reception signal strength by the reception signal strength measurement part 107. A control part 111 controls the band variable band-pass filter 106 so that its bandwidth is a carrier sense bandwidth in a predetermined carrier sense period, and controls the band variable band-pass filter 106 so that its bandwidth is a data demodulation bandwidth which is narrower than the carrier sense bandwidth before and after the predetermined carrier sense period.

Description

  The present invention relates to a wireless communication device and a receiving device.

  In the carrier sense multiple access method (CSMA / CA) represented by IEEE 802.15.4d / e / g WPAN, a plurality of communication devices communicate by sharing one or a plurality of radio resources (radio channels). It is a communication method. In CSMA / CA in IEEE 802.15.4 or the like, communication is performed by exchanging the physical frame 1 shown in FIG. 21 between two or more communication devices. As shown in FIG. 21, the physical frame 1 includes a preamble 2, an SFD 3, a PHR 4, and a payload 5, and the preamble 2 and the SFD 3 form a synchronization header 6.

  FIG. 22 is a schematic configuration diagram of a wireless communication system for explaining a carrier sense multiplex connection method represented by IEEE 802.15.4 and the like. Referring to FIG. 22, in general, a certain communication device (for example, communication device 11) can receive a radio wave emitted by a plurality of other communication devices (for example, communication devices 12 to 16) within a certain range 17. Exists. In this case, when two or more communication devices (for example, the communication devices 12 and 13) simultaneously transmit physical frames using the same radio resource, the receiving-side communication device (for example, the communication device 11) can determine which physical frame ( Data (data) cannot be received (so-called collision).

  The communication apparatus is obliged to perform carrier sense before attempting to transmit, as defined in the Clear Channel Assessment (CCA) standard such as IEEE 802.15.4. Carrier sense refers to reception on a wireless channel to be transmitted from now on and confirming that another communication device is not using the wireless channel (not emitting radio waves). As a result of carrier sense, if the radio channel is in use (in other words, busy), the transmission of the physical frame is suspended, and if the radio channel is not in use (in other words, idle), physical Send a frame. A method for avoiding the collision in this way is shown in IEEE 802.15.4.

  FIG. 23 is a diagram for explaining a communication operation by the carrier sense multiple access method. FIG. 23 shows a state in which a plurality of wireless communication apparatuses 11 to 16 exchange physical frames while avoiding a collision with each other. For example, when the communication device 11 confirms that the wireless channel to be used is idle by carrier sense, the communication device 11 transmits a physical frame to the communication device 12. The communication device 12 receives the physical frame, and then returns a reception response to the communication device 11. While the communication devices 11 and 12 are using the wireless channel, the other communication devices 13 to 16 receive the wireless channel without exchanging the physical frame and complete the physical frame exchange between the communication devices 11 and 12. Wait to do.

  In the physical layer carrier sense in IEEE802.15.4, etc., because a physical frame of IEEE802.15.4 is detected, it is judged that it is busy, and the received signal strength (RSSI) simply exceeds a prescribed threshold. Is combined with a function that determines that the device is busy. For example, in a channel with a bandwidth of 400 kHz and a data rate of 100 kbps, a sensitivity of 88 dBm or less is defined for the former function (a condition that a physical frame payload is 250 bytes and a packet error rate is 10%), and the latter function is A reception signal strength determination threshold of 78 dBm is defined.

  FIG. 24 shows a configuration of a wireless communication system when a carrier sense multiple access method (CSMA / CA) represented by WPAN such as IEEE 802.15.4 is viewed from another viewpoint. In this wireless communication system, a so-called star-type mesh network is constructed in which a communication device as a concentrator exchanges frames with each other via a relay between nodes and a communication device as a concentrator in a communication area. According to the mesh network, communication devices as nodes can be added or exchanged automatically at any place and at any time without complicated registration procedures.

  In the receiver described in FIG. 1 of Patent Document 1 below, a band-pass filter (BPF) having a narrow band characteristic and a band-pass filter having a wide band characteristic are applied to a received signal. Then, the received signal strength (RSSI) is measured for the received signal after passing through the narrowband BPF, and the received signal after passing through the wideband BPF is demodulated.

  Further, in the receiver described in FIG. 4 of Patent Document 1 below, one band variable BPF is applied to both RSSI detection and demodulation. Specifically, the band variable BPF is controlled to narrow band characteristics, RSSI detection is performed, carrier sense determination is performed from the detection result, and the band variable BPF is determined when the existence of the carrier is recognized from the determination result. Demodulate by controlling to wideband characteristics.

  In any of the above receivers, a demodulation operation start command is input to the demodulator when the carrier is recognized by the carrier sense determination, whereby the demodulation operation is started for the received signal that has passed through the BPF having the wideband characteristics. The

  In any of the above receivers, the narrowband characteristic at the time of waiting for RSSI is a band characteristic less than one channel occupied by the modulation occupied bandwidth (passband), whereas the wideband characteristic at the time of reception demodulation operation. Is a band characteristic equal to or greater than one channel occupied by the modulation occupied bandwidth (pass band).

JP 2003-347946 A

  The receiver of FIG. 1 of Patent Document 1 requires two types of filters, a wideband BPF for RSSI measurement and a narrowband BPF for demodulation. For this reason, there is a problem that the number of parts, mounting area, apparatus cost, etc. are increased. Such a problem occurs regardless of whether two types of filters are mounted on a substrate or when they are mounted in a single integrated circuit (IC).

  In any of the above receivers of Patent Document 1, the demodulation operation is started when the carrier is recognized by the carrier sense determination. In other words, the demodulation operation is not started unless the carrier is recognized by the carrier sense determination.

  Here, as described above, according to the standards such as IEEE 802.15.4, the busy determination threshold value of the received signal strength is generally larger than the reception sensitivity. For this reason, according to the receiver of Patent Document 1, a physical frame signal stronger than the reception sensitivity but weaker than the RSSI busy determination threshold is not recognized as a carrier, and as a result, the demodulation operation is not performed.

  An object of this invention is to provide the radio | wireless communication technique for making carrier sense operation | movement and demodulation operation | movement compatible with favorable performance.

  A wireless communication apparatus according to an aspect of the present invention is a wireless communication apparatus that performs packet communication using a carrier sense multiple access method, and includes a band-variable bandpass filter that limits a passband of a received signal, and the band-variable band A received signal strength measuring unit that measures received signal strength of the received signal that has passed through a pass filter, a carrier sense determining unit that performs carrier sense determination on the received signal from the received signal strength, and the band-variable bandpass filter. A demodulator that demodulates the received signal that has passed, in parallel with the measurement of the received signal strength by the received signal strength measuring unit, a transmitter that transmits a radio frame, and a pass band of the band-variable bandpass filter And a control unit for controlling the width. The control unit controls the band-variable bandpass filter to a carrier sense bandwidth during a predetermined carrier sense period, and the band-variable bandpass filter is controlled to the carrier sense band before and after the predetermined carrier sense period. The data demodulation bandwidth is controlled to be narrower than the width.

  According to the above aspect, according to the carrier sense determination based on the received signal strength (RSSI) in the carrier sense period, the carrier sense determination can be appropriately performed for a required bandwidth. On the other hand, by receiving a physical frame with the data demodulation bandwidth before and after the carrier sense period, it is possible to receive and demodulate the frame with good reception sensitivity. Thereby, carrier sense operation and demodulation operation can be made compatible with good performance.

  The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

It is a figure explaining the unit channel prescribed | regulated to ARIB STD-T96 regarding the power spectrum of a signal, and the bandwidth of a bandpass filter (BPF). It is a figure explaining the relationship between received signal power and a packet error rate when the pass bandwidth of a bandpass filter (BPF) is changed. 1 is a block diagram illustrating a configuration of a wireless communication device according to a first embodiment. 6 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the first embodiment. 6 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the first embodiment. 6 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the first embodiment. 5 is a time chart corresponding to the operation flow of FIG. 4 for the first embodiment. 6 is a time chart corresponding to the operation flow of FIG. 5 for the first embodiment. 7 is a time chart corresponding to the operation flow of FIG. 6 for the first embodiment (when a synchronization header is detected during a carrier sense period). 7 is a time chart corresponding to the operation flow of FIG. 6 for the first embodiment (when a synchronization header is detected after a carrier sense period). FIG. 10 is a block diagram illustrating a configuration of a wireless communication device according to a second embodiment. 10 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the second embodiment. 10 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the second embodiment. 10 is a flowchart illustrating band control of a band-variable bandpass filter in carrier sense operation in the second embodiment. 13 is a time chart corresponding to the operation flow of FIG. 12 for the second embodiment. 14 is a time chart corresponding to the operation flow of FIG. 13 for the second embodiment. 15 is a time chart corresponding to the operation flow of FIG. 14 for the second embodiment (when a synchronization header is detected during the carrier sense period). 15 is a time chart corresponding to the operation flow of FIG. 14 for the second embodiment (when a synchronization header is detected after a carrier sense period). FIG. 10 is a filter characteristic diagram illustrating band control of a band-variable bandpass filter in an unused channel search operation in the third embodiment. 14 is a flowchart illustrating band control of a band-variable bandpass filter in an unused channel search operation in the third embodiment. It is a figure which shows the physical frame of IEEE802.15.4 standard. It is a block diagram of the radio | wireless communications system for demonstrating the carrier sense multiple connection system represented by IEEE802.15.4 etc. FIG. It is a figure explaining the communication operation by the carrier sense multiple connection system represented by IEEE802.15.4 etc. It is a block diagram of the radio | wireless communications system for demonstrating the carrier sense multiple access system represented by WPAN, such as IEEE802.15.4.

<Embodiment 1>
In a wireless communication system employing a carrier sense multiple connection method, the quality of radio waves to be emitted and the carrier sense function to be realized must conform to the laws and technical standards of each country. For example, in the case of Japan, it is assumed that operation is performed in conformity with ARIB STD-T96, which is a standard for radio equipment of a specific low-power radio station.

  In ARIB STD-T96, the concept of unit channel is defined for radio channel allocation. The unit channel is a minimum unit channel on channel allocation in which the frequency interval and the frequency bandwidth coincide with each other as indicated by reference numerals 21a and 21b in FIG.

  In ARIB STD-T96, one unit channel or a plurality of unit channels continuous on the frequency axis can be assigned as channels to be used simultaneously. At this time, the center frequency of the band of one or more unit channels becomes the center frequency of the assigned channel.

  In addition, in ARIB STD-T96, regarding the carrier sense level, it is necessary to measure the sum of received power in all unit channels including the frequency at which radio waves are to be emitted. In other words, a communication device that transmits using a 2 unit channel must measure the received power with the bandwidth of the 2 unit channel.

  Specifically, according to the example in the upper part of FIG. 1, a communication device that emits radio waves having a spectrum extending over two unit channels, unit channels 21a and 21b, uses a band including both unit channels 21a and 21b as a carrier. It is obliged to sense. That is, when carrier sensing is performed, other transmission equipment emits a radio wave of one unit channel with a shifted center frequency as indicated by reference numerals 22a and 22b. The received power needs to be measured correctly for minutes.

  Therefore, in order to satisfy the requirements of the bandwidth subject to carrier sense and to prevent erroneous determination of radio waves outside the target bandwidth, reception through a band pass filter (BPF) 24 having a bandwidth of 2 unit channels For the signal, the received signal strength (RSSI) needs to be measured.

  On the other hand, the received signal used for data demodulation is preferably limited to be narrower than the bandwidth of the allocated number of unit channels (in the above example, the bandwidth of 2 unit channels). Specifically, the reception signal is preferably input to the data demodulator after being limited to a band having a reception center frequency as a center and narrower than two unit channels. This is because the S / N ratio of the received signal is improved by limiting the band in this way (in other words, the reception sensitivity is improved). Further, the band limitation for data demodulation is optimized by setting so as to maximize the S / N ratio. The lower part of FIG. 1 illustrates the characteristics of the band pass filter 23 in which the reception sensitivity is set to be favorable for data demodulation.

  FIG. 2 is a diagram for explaining the relationship between the received signal power and the packet error rate (PER). In FIG. 2, a characteristic line 32 indicates a packet error rate characteristic for a received signal that has passed through a BPF having a bandwidth corresponding to two unit channels (that is, BPF 24 for carrier sense (see FIG. 1)). On the other hand, the characteristic line 31 shows the packet error rate characteristic for the received signal that has passed through the BPF narrower than the bandwidth corresponding to the two unit channels (that is, the BPF 23 for data demodulation (see FIG. 1)). For example, when the bandwidth of the data demodulation BPF 23 is ½ times the bandwidth of the carrier sense BPF 24, the PER is improved by about 3 dB.

  FIG. 3 shows a block diagram of an example of the wireless communication apparatus according to the first embodiment. This wireless communication apparatus performs packet communication by a carrier sense multiple access method. In addition, this wireless communication apparatus can transmit and receive in conformity with, for example, IEEE 802.15.4, and conforms to ARIB STD-T96, which is a standard for radio equipment of specified low-power radio stations in Japan. Is assumed. Further, although not shown, a function that realizes a protocol layer higher than the media access control and a function that realizes an application layer, which are standardized by IEEE 802.15.4 or the like, may be included.

  The wireless communication apparatus 100 illustrated in FIG. 3 includes an antenna (ANT) 101, a local oscillator (LO) 104, a low noise amplifier (LNA) 103, a mixer (MIX) 105, a band-variable bandpass filter (BPF). ) 106, received signal strength measurement unit (RM) 107, carrier sense determination unit (CS) 108, demodulation unit (DEM) 109, synchronization header detection unit (SHR) 110, control unit (CNT) 111, , A modulation unit (MOD) 112 and a power amplifier (PA) 113 are included.

  Hereinafter, the band-variable bandpass filter 106 may be referred to as a band-variable BPF 106, a BPF 106, or the like. Further, the received signal strength may be referred to as RSSI, and the received signal strength measurement unit 107 may be referred to as RSSI measurement unit 107.

  The antenna 101 emits a high-frequency electric signal as a radio signal propagating in space, or converts a radio signal propagating in space into a high-frequency electric signal. The low noise amplifier 103 amplifies the high frequency signal received by the antenna 101.

  The local oscillator 104 generates a high-frequency signal used for transmission / reception of a radio signal, in other words, a radio frequency carrier signal. The frequency of the signal generated by the local oscillator 104 can be controlled by the control unit 111. The mixer 105 acquires the signal generated by the local oscillator 104 and the signal amplified by the low noise amplifier 103 as input signals, and multiplies these input signals.

  The band-variable BPF 106 limits the passband of the received signal after being processed by the low noise amplifier 103 and the mixer 104. More specifically, the BPF 106 acquires the multiplication signal generated by the mixer 105 as an input signal, and outputs the input signal with a band limited. The band-limited signal is input to the RSSI measuring unit 107 and the demodulating unit 109 and processed in parallel by the RSSI measuring unit 107 and the demodulating unit 109.

  The RSSI measurement unit 107 measures the RSSI of the signal input from the BPF 106, in other words, the RSSI of the received signal that has passed through the BPF 106.

  The carrier sense determination unit 108 performs carrier sense determination on the received signal from the measurement result by the RSSI measurement unit 107. The obtained carrier sense determination result is input to the control unit 111.

  For example, when the RSSI acquired from the RSSI measurement unit 107 is larger than a predetermined RSSI determination threshold (hereinafter also referred to as an RSSI threshold), the carrier sense determination unit 108 indicates that the received signal (in other words, the reception channel) is busy. judge. On the other hand, when the RSSI is equal to or less than the RSSI threshold, the carrier sense determination unit 108 determines that the received signal is idle. In addition, you may deform | transform this example so that the case where RSSI is equal to an RSSI threshold value may be included not busy but idle.

  In view of this operation, the carrier sense determination unit 108 can also be referred to as an RSSI determination unit 108.

  The demodulator 109 demodulates the signal input from the BPF 106, in other words, the RSSI of the received signal that has passed through the BPF 106. As described above, since the output signal from the BPF 106 is input to the RSSI measurement unit 107 and the demodulation unit 109, the RSSI measurement operation and the demodulation operation are performed in parallel on the same signal.

  The synchronization header detection unit 110 detects at least a part of the synchronization header (see the synchronization header 6 in FIG. 21) from the signal demodulated by the demodulation unit 109. The detection result of the synchronization header is input to the control unit 111.

  The control unit 111 controls various elements in the wireless communication device 100. For example, the control unit 111 controls the pass band of the BPF 106 to the carrier sense bandwidth 24 (see FIG. 1) or the data demodulation bandwidth 23 (see FIG. 1).

  The carrier sense bandwidth 24 is a bandwidth required for carrier sense. According to the example of ARIB STD-T96 assumed here, the carrier sense bandwidth 24 is a bandwidth corresponding to the number of unit channels used for communication (in FIG. 1, the case of two unit channels is illustrated). .

  According to the example of ARIB STD-T96, the data demodulation bandwidth 23 is narrower than the carrier sense bandwidth 24. In particular, the data demodulation bandwidth 23 is selected as a bandwidth necessary for obtaining a good reception sensitivity (in other words, a good S / N ratio), preferably a bandwidth necessary for obtaining an optimum reception sensitivity. Is done.

  The control of the pass band of the BPF 106 will be further described later.

  The modulation unit 112 modulates the high frequency signal output from the local oscillator 104 according to the data of the physical frame to be transmitted. The power amplifier 113 power-amplifies the high-frequency modulation signal generated by the modulation unit 112 and outputs the amplified signal to the antenna 101. As a result, a radio frame corresponding to the physical frame to be transmitted is emitted from the antenna 101 as a radio signal.

  In the example of FIG. 3, the modulation unit 112 and the power amplifier 113 constitute a transmission unit 114 that transmits a radio frame.

  Here, a configuration related to the reception function in the wireless communication device 100 (generally, a configuration in which the transmission unit 114 is omitted from the wireless communication device 100) can be referred to as a “reception device”. Similarly, a configuration related to the transmission function in the wireless communication device 100 can be referred to as a “transmission device”. That is, reception and transmission of a radio signal are realized by such a reception device and a transmission device. Note that the receiving device and the transmitting device may share a part of each other.

  4 to 6 illustrate flowcharts of band control of the BPF 106 in the carrier sense operation. The flow shown in FIG. 4 is connected to the flow shown in FIG. 6 through the connector C11 and is connected to the flow shown in FIG. 5 through the connector C12. Further, the flow shown in FIG. 5 is connected to the flow shown in FIG. 6 through a connector C13. As will be apparent from the following description, the operation flow 200 of FIGS. 4 to 6 can cope with data reception and demodulation even during the carrier sense operation.

  Here, it is assumed that the wireless communication apparatus 100 is waiting for a physical frame during a period other than the period in which the physical frame is transmitted. For this reason, the wireless communication device 100 is in a frame standby state even during the carrier sense operation. Specifically, the wireless communication device 100 can receive a physical frame in parallel while measuring RSSI for carrier sense determination, which is understood from the configuration illustrated in FIG. 3.

  The entire flow 200 over FIGS. 4 to 6 is roughly divided into flows 210, 230, and 250 illustrated in FIGS. 4 to 6. The operation flows 210, 230, and 250 will be described with reference to FIG.

  The operation flow 210 in FIG. 4 exemplarily shows a case where the selected radio channel is confirmed to be idle by carrier sense, and then a physical frame is transmitted. A time chart corresponding to the operation flow 210 is illustrated in FIG.

  4 and 7, first, the control unit 111 sets the pass bandwidth of the BPF 106 to the bandwidth for carrier sense (step 211). Before the operation flow 200 starts, the pass band of the BPF 106 is controlled to the data demodulation bandwidth (see FIG. 7).

  Then, a carrier sense period (which may be referred to as an RSSI measurement period) Tcs having a predetermined time length is started (step 212). Thereafter, when the carrier sense period Tcs expires (step 214), the carrier sense determination unit 108 acquires the RSSI measurement result from the RSSI measurement unit 107 (step 215).

  Here, during a predetermined carrier sense period Tcs (steps 212 and 214), in parallel with the RSSI measurement, the demodulator 109 and the sync header detector 110 detect the sync header of the physical frame (step 213). ). When at least a part of the synchronization header is detected, the operation of the wireless communication device 100 shifts to the operation flow 250 of FIG. 6 without waiting for the expiration of the carrier sense period Tcs (described later).

  On the other hand, when the synchronization header is not detected during the carrier sense period Tcs, the RSSI acquisition step 215 is executed when the carrier sense period Tcs expires (step 214).

  The carrier sense determination unit 108 determines whether the reception channel is busy or idle based on the acquired RSSI measurement result (step 216).

  If it is determined to be busy, the operation of the wireless communication device 100 proceeds to the operation flow 230 of FIG. 5 (described later). On the other hand, if it is determined to be idle, the control unit 111 controls the pass bandwidth of the BPF 106 to the data demodulation bandwidth (step 217). As a result, the operation flow 200 ends, and then a physical frame is transmitted as shown in the Air (Tx) column in FIG.

  The operation flow 230 of FIG. 5 is executed when the determination result of the carrier sense determination step (in other words, RSSI determination step) 216 is busy as described above. A time chart corresponding to the operation flow 230 is illustrated in FIG.

  In the operation flow 230 of FIG. 5, for example, a frequency (hereinafter also referred to as a near frequency) close to a frequency used by the own device (hereinafter also referred to as a self frequency) is used by another communication system or another communication device. Useful when using. Specifically, since the synchronization header of the physical frame based on the proximity frequency is not detected in step 213, step 216 is executed via step 215 when the carrier sense period Tcs expires (step 214).

  Here, when the BPF 106 is controlled to the data demodulation bandwidth, the RSSI may be measured with a value smaller than the actual intensity. However, according to the operation flow 200, since the BPF 106 is set to a carrier sense bandwidth wider than the data demodulation bandwidth in step 211, the RSSI is measured with the actual intensity. For this reason, as shown in FIG. 8, it is determined in step 216 that the signal of the close frequency is busy.

  In the operation flow 230 of FIG. 5, after the transition from the above step 216, the synchronization header is detected for the physical frame of the own frequency (step 231) as in the above step 213. When at least a part of the synchronization header is detected, the operation of the wireless communication device 100 proceeds to the operation flow 250 of FIG. 6 (described later). On the other hand, when the synchronization header at the own frequency is not detected, RSSI acquisition and determination are performed as in steps 215 and 216 (steps 232 and 233). If it is determined that the carrier sense determination step 233 is busy, the operation of the wireless communication device 100 returns to the synchronization header detection step 213.

  That is, steps 231, 232, and 233 are repeated until the synchronization header of the own frequency is detected or the signal of the adjacent frequency disappears. Here, the operation loop of steps 231, 232, and 233 is executed in a state where the BPF 106 is set to the carrier sense bandwidth.

  When the signal of the close frequency is lost and the carrier sense determination step 233 determines that the signal is idle, the control unit 111 controls the pass bandwidth of the BPF 106 to the data demodulation bandwidth (step 234). As a result, the operation flow 200 ends.

  Here, with RSSI alone, it is difficult to distinguish whether the signal is a signal of a desired physical frame or an interference signal from another system using a close frequency. If it is determined that the desired wave has been received simply because the RSSI is equal to or greater than the determination threshold, and the BPF 106 is controlled to the data demodulation bandwidth, the RSSI of the interference signal may be measured smaller than the actual value. In such a case, there is a possibility that the busy determination as defined in ARIB STD-T96 is erroneous.

  On the other hand, according to the operation flow 230 of FIG. 5, even if it is determined that the RSSI determination steps 215 and 233 are busy, it is not determined that the desired wave has been received unless the synchronization header of the own frequency is detected in step 231. Therefore, carrier sensing can be performed correctly while receiving interference signals from other systems having different frequencies.

  The operation flow 250 of FIG. 6 is executed when the synchronization header of the physical frame based on the own frequency is detected in the synchronization header detection steps 213 and 231 as described above. The time chart corresponding to the operation flow 250 is illustrated in FIGS. 9 and 10 according to the reception timing of the physical frame. FIG. 9 illustrates the case where the synchronization header is detected in the synchronization header detection step 213 during the carrier sense period Tcs, and FIG. 10 illustrates the case where the synchronization header is detected in the synchronization header detection step 231 after the carrier sense period Tcs. Illustrated.

  In the operation flow 250 of FIG. 6, after the transition from the above steps 213 and 231, the BPF 106 is controlled to the data demodulation bandwidth as in the above steps 217 and 234 (step 251). Then, with the controlled BPF 106, signal reception and data demodulation are continued until the end of the received frame (steps 252 and 253). Thereafter, predetermined demodulation completion processing is executed (step 254). As a result, the operation flow 200 ends.

  According to the operation flow 250 of FIG. 6, the BPF 106 set as the carrier sense bandwidth in the above step 211 is switched to the data demodulation bandwidth when at least a part of the synchronization header is detected (step 251). ). For this reason, after the change, the physical frame can be received and demodulated with better reception sensitivity.

  Here, in IEEE 802.15.4 or the like, while a physical frame is being demodulated, the channel is defined to be busy regardless of the measured value of RSSI. When the synchronization header is detected, considering that the spectral density of the received signal is concentrated on the data demodulation bandwidth of the BPF 106, even if the BPF 106 is controlled for data demodulation in step 251 above, it is in parallel with the demodulation. The RSSI measurement unit 107 that operates as described above can correctly measure the RSSI. That is, according to the operation flow 200, while the physical frame is being demodulated, it can be determined that the channel is busy.

  According to the basic idea of the operation flow 200, the BPF 106 is controlled to the carrier sense bandwidth in the carrier sense period Tcs, and the BPF 106 is used as the carrier in the period before and after the carrier sense period Tcs (including the non-execution period of the operation flow 200). The data demodulation bandwidth is controlled to be narrower than the sensing bandwidth.

  For this reason, according to the carrier sense determination based on RSSI in the carrier sense period Tcs, the carrier sense determination can be appropriately performed with respect to the bandwidth defined in ARIB STD-T96 or the like.

  On the other hand, by receiving the physical frame in the state of the data demodulation bandwidth before and after the carrier sense period Tcs, the frame can be received and demodulated with good reception sensitivity. Here, in IEEE 802.15.4 and the like, while a physical frame is demodulated, it is determined that the channel is busy regardless of the received signal strength. However, before and after the carrier sense period Tcs, since reception is possible with the data demodulation bandwidth originally, it is not necessary to control the BPF 106 to the data demodulation bandwidth by determining that it is busy.

  Therefore, it is possible to achieve both carrier sensing operation and demodulation operation with good performance.

  Further, according to the operation flow 230 (see FIG. 5) executed when the carrier sense determination result for the carrier sense period Tcs is busy, the carrier sense bandwidth remains unchanged after the end of the carrier sense period Tcs. The carrier sense determination is continued, and the BPF 106 is switched from the carrier sense bandwidth to the data demodulation bandwidth when the result of the carrier sense determination changes to idle. For this reason, as described above, it is possible to correctly perform carrier sense while receiving interference signals from other systems having different frequencies.

  When the operation flow 230 is executed, the BPF 106 is controlled to the data demodulation bandwidth after further carrier sense determination (see steps 232 and 233) after the carrier sense period Tcs. Therefore, even when the operation flow 230 is executed, the above basic idea of controlling the BPF 106 to the data demodulation bandwidth after the carrier sense period Tcs is satisfied.

  In addition, the adoption of the variable bandwidth BPF 106 can reduce the number of components, the mounting area, the device cost, and the like as compared with the configuration in which separate components of the carrier sense bandwidth BPF and the data demodulation bandwidth BPF are mounted.

  Further, as described above, according to the receiver of Patent Document 1, a signal of a physical frame that is stronger than the reception sensitivity but weaker than the RSSI busy determination threshold is not recognized as a carrier, and as a result, a demodulation operation is not performed. . On the other hand, since the radio communication apparatus 100 can perform RSSI measurement and demodulation in parallel (see FIG. 3), it can also demodulate a physical frame that is stronger than the reception sensitivity but weaker than the RSSI busy determination threshold.

<Embodiment 2>
FIG. 11 shows a block diagram of an example of a wireless communication apparatus according to the second embodiment. This wireless communication apparatus performs packet communication by a carrier sense multiple access method. In addition, this wireless communication apparatus can transmit and receive in conformity with, for example, IEEE 802.15.4, and conforms to ARIB STD-T96, which is a standard for radio equipment of specified low-power radio stations in Japan. Is assumed. Further, although not shown, a function that realizes a protocol layer higher than the media access control and a function that realizes an application layer, which are standardized by IEEE 802.15.4 or the like, may be included.

  11 includes an antenna (ANT2) 102, an antenna switch (ANTSW) 121, an antenna switch control unit (ANTSEL) 122, in addition to the components of the wireless communication device 100 illustrated in FIG. Is included.

  The antenna 102 is used for diversity together with the antenna (ANT1) 101. These antennas 101 and 102 constitute a diversity system (spatial diversity, polarization diversity, etc.) adopted in advance, and the correlation of received signals is less than a predetermined value (more preferably, no correlation is present). To be implemented).

  The antenna switch 121 switches between the antennas 101 and 102. Specifically, the antenna switch 121 selectively connects one of the antennas 101 and 102 to the input terminal of the low noise amplifier 103 or the output terminal of the power amplifier 113. Thereby, either one of the antennas 101 and 102 is validated.

  The antenna switch control unit 122 instructs the antenna switch 121 to switch between the antennas 101 and 102. Specifically, the antenna switch control unit 122 acquires an RSSI measurement result from the RSSI measurement unit 107, acquires a carrier sense determination result from the carrier sense determination unit 108, and acquires a synchronization header (or physical frame) from the synchronization header 110. ) And the switching of the antennas 101 and 102 is instructed based on the acquired information.

  FIGS. 12 to 14 illustrate flowcharts of bandwidth control of the BPF 106 in the carrier sense operation. The flow shown in FIG. 12 is connected to the flow shown in FIG. 14 through a connector C21, and is connected to the flow shown in FIG. 13 through a connector C22. Further, the flow shown in FIG. 13 is connected to the flow shown in FIG. 14 through a connector C23. As will be apparent from the following description, the operation flow 200B of FIGS. 12 to 14 can support data reception and demodulation even during the carrier sense operation.

  Here, it is assumed that the wireless communication device 100B waits for a physical frame during a period other than the period in which the physical frame is transmitted. For this reason, the wireless communication device 100B is in a frame standby state even during the carrier sense operation. Specifically, the wireless communication device 100B can receive a physical frame in parallel while measuring RSSI for carrier sense determination, which can be understood from the configuration illustrated in FIG.

  12 to 14 is roughly divided into flows 210B, 230B, and 250B illustrated in each of FIGS. These operation flows 210B, 230B, and 250B correspond to the operation flows 210, 230, and 250 of FIGS. 4 to 6, respectively, but are modified according to the adoption of antenna selection diversity. The operation flows 210B, 230B, and 250B will be described with reference to FIG.

  The operation flow 210B of FIG. 12 includes steps 218 and 219 in addition to steps 211 to 217 of the operation flow 210 of FIG. However, as will be described below, the execution order of steps 211 to 217 is changed. FIG. 15 illustrates a time chart corresponding to the operation flow 210B.

  In the operation flow 210B, steps 211 and 212 are executed as in the operation flow 210, and the carrier sense period Tcs starts. In particular, during the carrier sense period Tcs (steps 212 and 214), the antennas 101 and 102 are switched, and the RSSI is measured by the antennas 101 and 102, respectively.

  According to the example of FIG. 12, the RSSI is measured by the antenna used earlier in the RSSI measurement, in other words, the antenna enabled at the start of the carrier sense period Tcs (here, the antenna 101 is illustrated), and the predetermined time. When the measurement time Tant per length of the antenna expires (step 218), the carrier sense determination unit 108 acquires the measurement result of RSSI measured using the antenna 101 from the RSSI measurement unit 107 (step 215).

  Thereafter, the antenna is switched (step 219), the RSSI is measured by the enabled antenna 102, and when the measurement time Tant for each antenna expires (step 218), the carrier sense determination unit 108 receives the antenna 102 from the RSSI measurement unit 107. The measurement result of RSSI measured by using is acquired (step 215).

  That is, every time the measurement time Tant for each antenna expires (step 218), the RSSI measured with the antenna 101 or 102 enabled at that time is read. Thereby, the carrier sense determination unit 108 acquires both the RSSI measured by the antenna 101 and the RSSI measured by the antenna 102 (step 215).

  The time length of each antenna measurement period Tant is set to ½ or less of the preset time length of the carrier sense period Tcs before the start of the carrier sense period Tcs. Alternatively, the time length of the carrier sense period Tcs is set to at least twice the preset time length of the measurement period Tant for each antenna before the start of the carrier sense period Tcs. With this setting, it is possible to switch all the antennas (here, two antennas 101 and 102) during the carrier sense period Tcs.

  Here, also in the operation flow 210B, in parallel with the RSSI measurement, the demodulator 109 and the sync header detector 110 detect the sync header of the physical frame (step 213). When at least a part of the synchronization header is detected, the operation of the wireless communication device 100B shifts to an operation flow 250B in FIG. 14 (described later) without waiting for the expiration of the measurement time for each antenna Tant and the carrier sense period Tcs.

  On the other hand, when the synchronization header is not detected during the carrier sense period Tcs, the carrier sense determination step 216 is executed when the carrier sense period Tcs expires (step 214).

  In particular, the carrier sense determination unit 108 determines whether the measured channel is busy or idle based on both the RSSI measured by the antenna 101 and the RSSI measured by the antenna 102 (step 216). ). Specifically, if both RSSIs are equal to or less than a predetermined RSSI threshold, it is determined to be idle, otherwise (ie, if at least one RSSI is greater than the predetermined RSSI threshold), it is determined to be busy (step 216).

  If it is determined to be busy, the operation of the wireless communication device 100B shifts to an operation flow 230B in FIG. 13 (described later). On the other hand, if it is determined to be idle, the control unit 111 controls the pass bandwidth of the BPF 106 to the data demodulation bandwidth (step 217). As a result, the operation flow 200B ends, and thereafter, a physical frame is transmitted as shown in the Air (Tx) column in FIG.

  Here, the antennas 101 and 102 are switched by the antenna switch 121 during the carrier sense period Tcs, both RSSI when connected to the antenna 101 and RSSI when connected to the antenna 102 are measured, and whether both RSSIs are idle. The example used for determining whether busy is described.

  On the other hand, among the antennas 101 and 102, an antenna to be connected during the carrier sense period Tcs can be determined in advance, and it can be determined whether the antenna is idle or busy based on the RSSI when the antenna is connected to the determined antenna. . In such an example, the wireless communication device 100B operates in the same manner as the operation flow 210 illustrated in FIG.

  The operation flow 230B of FIG. 13 is executed when the determination result of the carrier sense determination step (in other words, RSSI determination step) 216 is busy as described above. A time chart corresponding to the operation flow 230B is illustrated in FIG.

  The operation flow 230B of FIG. 13 is executed, for example, when another communication system or another communication device uses a close frequency close to the own frequency. Specifically, since the synchronization header of the physical frame based on the proximity frequency is not detected in step 213, step 216 is executed when the carrier sense period Tcs expires (step 214).

  Here, when the BPF 106 is controlled to the data demodulation bandwidth, the RSSI may be measured with a value smaller than the actual intensity. However, according to the operation flow 200B, since the BPF 106 is set to the carrier sense bandwidth in the above step 211, the RSSI is measured with the actual intensity. For this reason, as shown in FIG. 16, it is determined in step 213 that a signal having a close frequency is busy.

  The operation flow 230B of FIG. 13 includes step 235 in addition to steps 231 to 234 of the operation flow 230 of FIG. The added step 235 is executed prior to steps 231 to 234. In the added step 235, the antenna switch control unit 122 compares the RSSI measured by the antenna 101 with the RSSI measured by the antenna 102, selects the antenna that provided the larger RSSI among the antennas 101 and 102, and The antenna switch 121 is controlled according to the selection result.

  After step 235, steps 231 to 234 are executed as in the operation flow 230 of FIG. That is, steps 231 to 234 are executed using the antenna selected in step 235.

  Here, an example in which RSSI is measured using only the antenna selected in the antenna selection step 235 has been described.

  On the other hand, even in the operation flow 230B of FIG. 13, even if the antennas 101 and 102 are switched every predetermined time (for example, the measurement time Tant per antenna (see FIG. 12)) and the RSSI is measured by both the antennas 101 and 102, Good. In this case, in the RSSI determination step 233, the carrier sense determination unit 108 determines that the RSSI measurement value of two consecutive times is equal to or less than the RSSI threshold (in other words, the RSSI measured with one antenna and the other antenna immediately thereafter. If both the measured RSSI is below the threshold), it is determined to be idle, otherwise it is determined to be busy.

  The operation flow 250B of FIG. 14 is executed when a synchronization header of a physical frame at its own frequency is detected in the synchronization header detection steps 213 and 231 as described above. A time chart corresponding to the operation flow 250B is illustrated in FIGS. 17 and 18 according to the reception timing of the physical frame. FIG. 17 illustrates the case where the synchronization header is detected in the synchronization header detection step 213 during the carrier sense period Tcs, and FIG. 18 illustrates the case where the synchronization header is detected in the synchronization header detection step 231 after the carrier sense period Tcs. Illustrated.

  The operation flow 250B of FIG. 14 includes steps 255 to 258 in addition to steps 251 to 254 of the operation flow 250 of FIG. As can be seen from FIG. 14, the added steps 255 to 258 are steps 251 to 251 when the operation flow 210 </ b> B of FIG. 12 is shifted (that is, when a synchronization header is detected in step 213 during the carrier sense period Tcs). While being executed prior to H.254, it is not executed when the operation flow 230B of FIG.

  In step 255, RSSI is measured by the antenna that detected the synchronization header in step 213. Thereafter, in step 256, the antennas 101 and 102 are switched. That is, an antenna different from the antenna that detected the synchronization header in step 213 is validated. In step 257, RSSI is measured by the antenna set in step 256. In step 258, the same processing as in the antenna selection step 235 (see FIG. 13) is performed. That is, in step 258, the antenna switch control unit 122 compares the RSSI before and after switching in the antenna switching step 256, selects an antenna that provides a larger RSSI, and controls the antenna switch 121 according to the selection result.

  After step 238 and after the transition from the operation flow 230B in FIG. 13, steps 251 to 254 are executed as in the operation flow 250 in FIG. That is, steps 251 to 234 are executed using the antenna selected in step 258.

  In the synchronization header detection step 213, there is a possibility that the synchronization header detection has succeeded by the antenna whose timing coincides with the head of the physical frame. In other words, the reception sensitivity may be better for the antenna that was not connected when the synchronization header was detected. On the other hand, according to steps 255 to 258, an antenna with a large RSSI is selected, so that the remaining physical frames can be received using an antenna with better reception conditions. That is, an improvement in reception sensitivity can be expected.

  Here, as described above, in the case of shifting from the operation flow 230B of FIG. 13, steps 255 to 258 are not executed. However, the antenna having the larger RSSI has already been selected in the antenna selection step 235 of the operation flow 230B. For this reason, the same effect as Steps 255-258 can be expected.

  According to radio communication apparatus 100B, the same operation as radio communication apparatus 100 according to Embodiment 1 can be realized even in a configuration employing antenna selection diversity. For this reason, the effect similar to the wireless communication apparatus 100 can be acquired also by the wireless communication apparatus 100B.

  In the above description, the two antennas 101 and 102 are exemplified, but three or more antennas may be used.

<Embodiment 3>
Here, the WPAN wireless communication system such as IEEE 802.15.4 illustrated in FIG. 24 will be described. Consider an example in which the communication area 42 covered by the concentrator 41 and the communication area 45 covered by the concentrator 44 perform communication using the same frequency. At the initial stage of network construction, radio waves emitted by the nodes 43 belonging to the communication area 42 are operated so as not to reach the nodes 46 belonging to the communication area 45 or the probability thereof is very low. The

  However, as a result of adding nodes in the communication areas 42 and 45 with the passage of time, the probability that radio waves emitted by the node 47 belonging to the communication area 4 will reach the node 48 belonging to the communication area 45 may increase. Conceivable. In other words, it can be considered that a part of the communication area 42 and a part of the communication area 45 overlap each other.

  In such a state, a node (for example, the node 47) located in a place where the communication areas 42 and 45 overlap each other is not only the time when the node in the communication area to which the node belongs belongs but also the adjacent communication area. The frame must be transmitted while avoiding the time for the node to emit radio waves. In addition, the probability that a frame transmitted from a certain node belonging to the communication area 42 (for example, the node 43) to the node 47 collides with a frame transmitted from a node belonging to the communication area 45 (for example, the node 46) to the other party. Goes up. These cause a reduction in system throughput.

  In order to avoid such a situation, it is preferable that the communication areas 42 and 45 use different frequencies. However, in order to change the frequency used for communication, a channel that is not used by another user is being operated. Must be discovered. For example, it is necessary to periodically measure the received signal strength of other channels by using the time during which each node does not need to receive or transmit.

  The IEEE 802.15.4 d / e / g CSMA / CA standard exemplifies a predetermined period after receiving a frame addressed to another device as the time when the above reception and transmission are not required. Specifically, according to the standard, each communication device enters a frame standby state in preparation for arrival of a frame addressed to itself, except during a frame transmission period. Here, in order for the communication device that has received the frame addressed to itself to send back an ACK, the channel is reserved for the ACK return. For this reason, a communication apparatus that has received a frame addressed to another apparatus cannot transmit a frame and does not receive a frame from the reception of the frame until the completion of the ACK reply. That is, for a communication device that has received a frame addressed to another device, such a predetermined period corresponds to a time during which neither the above reception nor transmission is necessary.

  Using one or both of the wireless communication apparatuses 100 and 100B according to the first and second embodiments, a WPAN wireless communication system such as IEEE 802.15.4 illustrated in FIG. 24 can be configured.

  As described above, there is a problem of radio wave interference between adjacent communication areas. In order to avoid interference, a search for another unused channel and switching to a found unused channel are performed. Since radio communication apparatuses 100 and 100B according to Embodiments 1 and 2 can control the pass bandwidth of BPF 106 as described above, an example of searching for an unused channel using such band control will be described.

  FIG. 19 is a filter characteristic diagram illustrating band control of the BPF 106 in the unused channel search operation.

  Interference occurs not only in the situation where there is a radio signal serving as an interference source in the same channel, but also in the situation where there is a radio signal serving as an interference source due to high power in the adjacent channel. Therefore, for example, when communication is performed using 2 unit channels, it is preferable to search for unused channels having a total bandwidth of 4 unit channels including the 1 unit channels on both sides of the used channel.

  In this example, two RSSI measurements are required according to a BPF with a passband width of 2 unit channels. On the other hand, in the case of the band variable BPF 106 according to the first and second embodiments, only one RSSI measurement is required by controlling the pass bandwidth to 4 unit channels. For this reason, the time required for RSSI measurement can be shortened and an unused channel can be searched efficiently. Note that the search target is not limited to the 4-unit channel.

  As described above, the bandwidth control of the BPF 106 can be used not only for the carrier sense described in the first and second embodiments, but also for searching for unused channels or for other purposes.

  FIG. 20 illustrates a flowchart of bandwidth control of the BPF 106 in the unused channel search operation. Here, a case where the operation flow 300 illustrated in FIG. 20 is executed by the wireless communication apparatus 100 according to the first embodiment (see FIG. 3) is illustrated, but the wireless communication apparatus 100B according to the second embodiment (see FIG. 11). It is also possible to execute the operation flow 300 in FIG.

  The operation flow 300 is performed, for example, in a situation where the wireless communication apparatus 100 does not need to receive or transmit on its own channel. According to the example of FIG. 20, first, the control unit 111 controls the local oscillator 104 so that the reception frequency becomes the center frequency of the other channel to be searched (step 301). Next, the control unit 111 controls the pass bandwidth of the BPF 106 to a bandwidth corresponding to the search target bandwidth, that is, the number of channels simultaneously performing RSSI measurement (step 302).

  Next, the RSSI measurement unit 107 starts measurement of RSSI (step 303), and waits until the period allowed for channel search (referred to as a carrier sense period for channel search) expires (step 304). ), And obtain the RSSI measurement result (step 305). Then, the carrier sense determination unit 108 determines whether the search target channel is unused (idle) or in use (busy) by comparing the acquired RSSI with a predetermined RSSI threshold (step) 306).

  Thereafter, the control unit 111 controls the local oscillator 104 so that the reception frequency becomes the center frequency of the own channel (step 307), and controls the bandwidth of the BPF 106 to the data demodulation bandwidth (step 308). Thereby, standby and reception of the physical frame in the own channel are resumed.

  Here, when it is difficult to determine whether or not the search target channel is in use by one RSSI measurement, a large number of measurements are required. Also, since the ratio of the time that the wireless communication device does not have to receive or transmit on its own channel is small, RSSI measurement over a long period of time is necessary to collect measurement values at a level necessary for determining whether or not it is unused. Cost.

  In this regard, in the carrier sense period Tch for other channels, the BPF 106 has a wider bandwidth than the carrier sense bandwidth used in the carrier sense period Tcs (see FIG. 4) for the own channel described in the first and second embodiments. Control to width. Thereby, the period required to collect RSSI measurement values can be shortened, and an unused channel can be searched efficiently. In the carrier sense determination step 306, a determination criterion (that is, an RSSI threshold) corresponding to the wider bandwidth extended for other channels is used.

  In the above, the case where the search for unused channels is performed in a period in which neither reception nor transmission is required is illustrated, but the present invention is not limited to this example. For example, it is possible to search for an unused channel during the frame standby period. In this case, if the carrier sense operation flows 200 and 200B of the first and second embodiments are applied, it is possible to cope with an interrupt process or the like by detecting a synchronization header (that is, receiving a frame). For example, a flow in which the above steps 301, 302, 307, 308, etc. are applied to the carrier sense operation flows 200, 200B of the first and second embodiments can be considered.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  1 physical frame, 6 synchronization header, 23 data demodulation bandwidth (narrow band), 24 carrier sense bandwidth (broadband), 100, 100B wireless communication device, 101, 102 antenna, 106 band-variable bandpass filter, 107 Received signal strength measurement unit, 108 carrier sense determination unit, 109 demodulation unit, 110 synchronization header detection unit, 111 control unit, 114 transmission unit, 200, 200B carrier sense operation, 300 other channel search operation, Tcs carrier sense period, Tant antenna Every measurement period, carrier sense period for Tch channel search.

Claims (16)

A wireless communication device that performs packet communication by a carrier sense multiple connection method,
A band-variable bandpass filter that limits the passband of the received signal;
A received signal strength measuring unit that measures received signal strength of the received signal that has passed through the band-variable bandpass filter;
A carrier sense determination unit that performs carrier sense determination on the received signal from the received signal strength;
A demodulator that demodulates the received signal that has passed through the band-variable bandpass filter in parallel with the measurement of the received signal strength by the received signal strength measuring unit;
A transmission unit for transmitting a radio frame;
A control unit for controlling a pass bandwidth of the band-variable bandpass filter,
The control unit controls the band-variable bandpass filter to a carrier sense bandwidth during a predetermined carrier sense period, and the band-variable bandpass filter is controlled to the carrier sense band before and after the predetermined carrier sense period. A wireless communication apparatus that controls a data demodulation bandwidth narrower than the width.   When the result of the carrier sense determination for the predetermined carrier sense period is busy, the control unit continues the carrier sense determination while maintaining the carrier sense bandwidth, and the result of the carrier sense determination becomes idle. The radio communication apparatus according to claim 1, wherein the variable band-pass filter is switched from the carrier sense bandwidth to the data demodulation bandwidth due to the change. A synchronization header detection unit for detecting at least a part of the synchronization header for the demodulated data output from the demodulation unit;
The control unit may detect the bandwidth variable bandpass by detecting at least a part of the synchronization header even when the bandwidth variable bandpass filter is set to the carrier sensing bandwidth. The wireless communication apparatus according to claim 1, wherein a filter is switched to the data demodulation bandwidth.   In the predetermined carrier sense period for another channel, the control unit controls the band-variable bandpass filter to have a wider bandwidth than the carrier sense bandwidth used in the predetermined carrier sense period for its own channel. The wireless communication apparatus according to claim 1, wherein the carrier sense determination unit performs the carrier sense determination based on a reference corresponding to the wider bandwidth. A wireless communication device that performs packet communication by a carrier sense multiple connection method,
A plurality of antennas conforming to the diversity method adopted in advance;
A band-variable bandpass filter that limits the passband of the received signal;
A received signal strength measuring unit that measures received signal strength of the received signal that has passed through the band-variable bandpass filter;
A carrier sense determination unit that performs carrier sense determination on the received signal from the received signal strength;
A demodulator that demodulates the received signal that has passed through the band-variable bandpass filter in parallel with the measurement of the received signal strength by the received signal strength measuring unit;
A transmission unit for transmitting a radio frame;
A control unit for controlling a pass bandwidth of the band-variable bandpass filter,
The received signal strength measuring unit is configured according to antenna selection reception diversity, and measures a plurality of received signal strengths corresponding to the plurality of antennas by measuring the received signal strength for each antenna,
The carrier sense determination unit makes a busy determination with a state where at least one of the plurality of received signal strengths exceeds a determination threshold,
The control unit controls the band-variable bandpass filter to a carrier sense bandwidth during a predetermined carrier sense period, and the band-variable bandpass filter is controlled to the carrier sense band before and after the predetermined carrier sense period. A wireless communication apparatus that controls a data demodulation bandwidth narrower than the width.   When the result of the carrier sense determination for the predetermined carrier sense period is busy, the control unit continues the carrier sense determination while maintaining the carrier sense bandwidth, and the result of the carrier sense determination becomes idle. The wireless communication apparatus according to claim 5, wherein the variable band-pass filter is switched from the carrier sensing bandwidth to the data demodulation bandwidth due to the change. A synchronization header detection unit for detecting at least a part of the synchronization header for the demodulated data output from the demodulation unit;
The control unit may detect the bandwidth variable bandpass by detecting at least a part of the synchronization header even when the bandwidth variable bandpass filter is set to the carrier sensing bandwidth. The wireless communication apparatus according to claim 5 or 6, wherein a filter is switched to the data demodulation bandwidth.   In the predetermined carrier sense period for another channel, the control unit controls the band-variable bandpass filter to have a wider bandwidth than the carrier sense bandwidth used in the predetermined carrier sense period for its own channel. The wireless communication apparatus according to claim 5, wherein the carrier sense determination unit performs the carrier sense determination based on a reference corresponding to the wider bandwidth. A receiving device that performs packet communication by a carrier sense multiple connection method,
A band-variable bandpass filter that limits the passband of the received signal;
A received signal strength measuring unit that measures received signal strength of the received signal that has passed through the band-variable bandpass filter;
A carrier sense determination unit that performs carrier sense determination on the received signal from the received signal strength;
A demodulator that demodulates the received signal that has passed through the band-variable bandpass filter in parallel with the measurement of the received signal strength by the received signal strength measuring unit;
A control unit for controlling a pass bandwidth of the band-variable bandpass filter,
The control unit controls the band-variable bandpass filter to a carrier sense bandwidth during a predetermined carrier sense period, and the band-variable bandpass filter is controlled to the carrier sense band before and after the predetermined carrier sense period. A receiving apparatus that controls a data demodulation bandwidth narrower than the width.   When the result of the carrier sense determination for the predetermined carrier sense period is busy, the control unit continues the carrier sense determination while maintaining the carrier sense bandwidth, and the result of the carrier sense determination becomes idle. The receiving device according to claim 9, wherein the band-variable bandpass filter is switched from the carrier sense bandwidth to the data demodulation bandwidth due to the change. A synchronization header detection unit for detecting at least a part of the synchronization header for the demodulated data output from the demodulation unit;
The control unit may detect the bandwidth variable bandpass by detecting at least a part of the synchronization header even when the bandwidth variable bandpass filter is set to the carrier sensing bandwidth. The receiving device according to claim 9 or 10, wherein a filter is switched to the data demodulation bandwidth.   In the predetermined carrier sense period for another channel, the control unit controls the band-variable bandpass filter to have a wider bandwidth than the carrier sense bandwidth used in the predetermined carrier sense period for its own channel. The receiving apparatus according to claim 9, wherein the carrier sense determination unit performs the carrier sense determination based on a reference corresponding to the wider bandwidth. A receiving device that performs packet communication by a carrier sense multiple connection method,
A plurality of antennas conforming to the diversity method adopted in advance;
A band-variable bandpass filter that limits the passband of the received signal;
A received signal strength measuring unit that measures received signal strength of the received signal that has passed through the band-variable bandpass filter;
A carrier sense determination unit that performs carrier sense determination on the received signal from the received signal strength;
A demodulator that demodulates the received signal that has passed through the band-variable bandpass filter in parallel with the measurement of the received signal strength by the received signal strength measuring unit;
A control unit for controlling a pass bandwidth of the band-variable bandpass filter,
The received signal strength measuring unit is configured according to antenna selection reception diversity, and measures a plurality of received signal strengths corresponding to the plurality of antennas by measuring the received signal strength for each antenna,
The carrier sense determination unit makes a busy determination with a state where at least one of the plurality of received signal strengths exceeds a determination threshold,
The control unit controls the band-variable bandpass filter to a carrier sense bandwidth during a predetermined carrier sense period, and the band-variable bandpass filter is controlled to the carrier sense band before and after the predetermined carrier sense period. A receiving apparatus that controls a data demodulation bandwidth narrower than the width.   When the result of the carrier sense determination for the predetermined carrier sense period is busy, the control unit continues the carrier sense determination while maintaining the carrier sense bandwidth, and the result of the carrier sense determination becomes idle. The receiving apparatus according to claim 13, wherein the band-variable band-pass filter is switched from the carrier sensing bandwidth to the data demodulation bandwidth due to the change. A synchronization header detection unit for detecting at least a part of the synchronization header for the demodulated data output from the demodulation unit;
The control unit may detect the bandwidth variable bandpass by detecting at least a part of the synchronization header even when the bandwidth variable bandpass filter is set to the carrier sensing bandwidth. The receiving apparatus according to claim 13 or 14, wherein a filter is switched to the data demodulation bandwidth.   In the predetermined carrier sense period for another channel, the control unit controls the band-variable bandpass filter to have a wider bandwidth than the carrier sense bandwidth used in the predetermined carrier sense period for its own channel. The receiving apparatus according to claim 13, wherein the carrier sense determination unit performs the carrier sense determination based on a reference corresponding to the wider bandwidth.

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