JP5063469B2 - Wireless communication apparatus, impedance matching method, program, and recording medium thereof - Google Patents

Description

  The present invention relates to a wireless communication apparatus including a transceiver that transmits and receives signals by switching a communication frequency with a predetermined hopping pattern in broadband communication. The present invention also relates to a transmitter / receiver that transmits and receives signals by switching a communication frequency with a predetermined hopping pattern in wideband communication, and a plurality of narrowband antennas having different communication bands included in the communication band of the wideband communication. The present invention relates to an impedance matching method for matching impedances between each of the plurality of narrowband antennas and the transmitter / receiver, a program for causing a computer to execute such a method, and a recording medium thereof.

  In recent years, wireless communication systems using UWB (abbreviation of Ultra Wide Band, which means “ultra-wide band”) have attracted attention because data can be transmitted and received by spreading data over an extremely wide frequency band.

  UWB, as defined by the US Federal Communications Commission (FCC), is a wireless communication system that transmits and receives using a very wide bandwidth with a specific bandwidth of 20% or more of the center frequency or 500 MHz or more. Say. One of the standards using this wireless communication method, MultiBand OFDM (one of the digital modulation methods) recommended by WiMedia Alliance to which companies such as Microsoft (registered trademark), Intel (registered trademark) and Sony (registered trademark) belong. In the method of Orthogonal Frequency Division Multiplexing, which means “Orthogonal Frequency Division Division”, devices within a radius of several meters are wirelessly connected, and a maximum frequency of 480 Mbps is used using a frequency band of 3.1 GHz to 10.6 GHz. Data communication can be performed at a communication speed. This MultiBand OFDM system is used as a physical layer standard of the WirelessUSB standard created for the purpose of making a wired USB (Universal Serial Bus) wireless, and as a physical layer standard of the next generation Bluetooth (registered trademark) (Bluetooth v3.0). Has been decided to be.

  In particular, wireless USB control ICs (Integrated Circuits) and RF (Radio Frequency) ICs have been developed in recent years by semiconductor manufacturers competing. WirelessUSB, which is a feature of the UWB communication system, is intended to be used as an alternative to wired USB in addition to transmitting data over a wide band with low power and ultra-high speed, so it interferes with numerous wired USBs. The specifications are determined so that the communication must be secure, and the protocol and physical layer standards are stricter than the conventional wireless standards (such as Bluetooth (registered trademark) and wireless LAN (Local Area Network)). And it is made highly.

  As an example, an interference avoidance technique called a frequency hopping method that is also used in Bluetooth (registered trademark) is adopted. Frequency hopping in Bluetooth is determined in advance between a master and a device according to each packet. In the wireless USB, frequency hopping is performed at a predetermined frequency between the host and the device with each symbol instead of the packet. The relationship between packets and symbols is shown in FIG. As shown in FIG. 14, one packet is composed of a plurality of symbols, and one symbol is transmitted in one band. For example, three different bands (refer to Band1, Band2, and Band3 in FIG. 14B). Are sequentially transmitted by sequentially switching. As a result, WirelessUSB has a feature that it is more resistant to interference with other signals sharing the same band and has less packet loss than Bluetooth.

  However, unlike Bluetooth (registered trademark), when the frequency hopping method is adopted in UWB wireless communication, it is extremely difficult to ensure high-quality communication performance. This is because the frequency characteristics of the hopping frequency are different in the space, the transmission line, or the high-frequency component, so that some ingenuity is required in the antenna and the antenna peripheral circuit having extremely strong frequency dependence. Particularly problematic is an antenna for supporting a wide band. In UWB wireless communication, band overlap with other wireless standards is unavoidable due to the wide frequency band, and therefore, strict output regulation is provided. Therefore, extremely weak radio waves are demodulated on the receiving side, and high reception sensitivity is required for the antenna used. Under the condition that the ratio of the used bandwidth to the center frequency is approximately 1, it is difficult to increase the sensitivity with a single antenna. In addition, transmitting a wide frequency band signal with a single antenna is not as easy as receiving it.

  Accordingly, in order to ensure high-quality communication performance in broadband wireless communication, it has been proposed to provide a plurality of narrowband antennas instead of a single broadband antenna (for example, JP-A-2005-123753 ( Patent Document 1).). By selecting an antenna having a good reception state from a plurality of narrowband antennas, it is possible to efficiently transmit a transmitted radio wave in addition to efficiently receiving a weak radio wave.

  FIG. 15 shows the radiation efficiency and VSWR (Voltage Standing Wave Ratio, which stands for “standing wave ratio”) when a single wideband antenna is used and when a plurality of narrowband antennas are used. .)

  FIG. 15A shows the radiation efficiency for each of the case where a single wideband antenna is used and the case where a plurality of narrowband antennas are used. The radiation efficiency of the antenna is represented by a ratio of the radiation power and the incident power of the antenna, and indicates how much power incident on the antenna can be radiated. That is, the basic performance of the antenna as an antenna can be known from the radiation efficiency. In the figure, reference numeral 10a indicates the radiation efficiency of a single broadband antenna, and reference numerals 11a, 12a, 13a and 14a indicate the radiation efficiency of each of the four narrowband antennas. Each of the narrowband antennas has a different communication band in the communication band for wideband communication, and the wireless communication apparatus can cover the entire communication band of the wideband communication by using these four narrowband antennas. it can. As illustrated, the radiation efficiency 10a of the broadband antenna covers the entire communication band (f1 to f2) for broadband communication. On the other hand, the radiation efficiencies 11a, 12a, 13a, and 14a of the narrowband antenna are all higher than the radiation efficiency a11 of the wideband antenna.

  FIG. 15B shows the VSWR when a single wideband antenna is used and when a plurality of narrowband antennas are used. VSWR is represented by the ratio of the absolute values of the maximum amplitude and the minimum amplitude of the standing wave. The standing wave is generated by an input wave to the antenna and a reflected wave from the antenna, and the VSWR value is determined by how much impedance mismatch occurs in the antenna that causes signal reflection. In other words, the VSWR value indicates the degree of reflection between the transmission path leading to the antenna and the antenna. Therefore, as the VSWR value becomes lower, signal loss caused by signal reflection is reduced and communication quality is improved. In general, the communicable VSWR value is “3”. In the figure, reference number 10b indicates the VSWR of a single wideband antenna, and reference numbers 11b, 12b, 13b and 14b indicate the VSWR of each of the four narrowband antennas. As shown in the figure, the VSWR 10b of the broadband antenna takes a value lower than “3” over the entire communication band for broadband communication. On the other hand, the VSWRs 11b, 12b, 13b, and 14b of the narrow band antenna are all lower than the VSWR 11b of the wide band antenna.

  As described above, it is generally known that the radiation efficiency and VSWR of the antenna deteriorate as the communication band becomes wider, and providing a plurality of narrowband antennas instead of a single wideband antenna ensures communication performance. It is effective for.

  However, when a plurality of narrow-band antennas are provided instead of a single wide-band antenna, one of the plurality of narrow-band antennas is selected according to the reception level. A band antenna may be selected. In that case, there is a problem that impedance mismatch occurs between the transceiver including the transmission path and the antenna, and the VSWR value, that is, reflection between the transceiver and the antenna increases, resulting in power loss.

On the other hand, in frequency hopping communication using a single narrowband antenna, it has been proposed to optimize antenna characteristics by establishing impedance matching between a transceiver and an antenna (for example, Japanese Patent Laid-Open No. 2003-2003). -298458 gazette (patent document 2).
JP 2005-123753 A JP 2003-298458 A

  However, the impedance matching technique for frequency hopping in a narrow band (80 MHz) described in Patent Document 2 cannot be applied to frequency hopping in a wide band as it is.

  The reception level fluctuates for each hopping frequency due to the power difference between bands originally possessed by the transmitter and the fluctuation of the power value due to spatial multipath fading. When the reception level fluctuates for each hopping frequency (Automatic Gain Control, meaning “automatic gain control”. Amplifies automatically so that a constant output can be obtained even when the amplitude of the input electric signal fluctuates. It is a circuit that adjusts the amplification factor (ie, gain) of the circuit.) Since the processing is difficult to work properly, reception may fail. Therefore, in the frequency hopping in a wide band, there is a problem that the reception level must be made as flat as possible.

  In view of the above problems, the present invention provides a wireless communication device, an impedance matching method, a program, and a recording medium thereof capable of following temporal level fluctuations of a received signal in a broadband wireless communication device using a plurality of narrowband antennas. The purpose is to provide.

  In order to achieve the above object, a wireless communication device of the present invention is a wireless communication device including a transceiver that transmits and receives a signal by switching a communication frequency with a predetermined hopping pattern in broadband communication, A plurality of narrowband antennas having different communication bands included in the communication band, antenna selection means for selecting at least one of the plurality of narrowband antennas according to the predetermined hopping pattern, and the antenna selection means A signal level detection means for detecting a level of a signal received by the selected narrowband antenna; a narrowband antenna selected by the antenna selection means based on a level of the signal detected by the signal level detection means; and Impedance matching means for matching impedance between transmitter and receiver Characterized in that it has a.

  Accordingly, it is possible to provide a wireless communication apparatus capable of following a temporal level fluctuation of a received signal in a wideband wireless communication apparatus using a plurality of narrowband antennas.

  Preferably, the wireless communication device of the present invention includes a storage unit that stores a relationship between a difference in signal level and a transmission line impedance, a signal level detected by the signal level detection unit, and a predetermined reference level. Level difference calculating means for obtaining a level difference between the two, obtaining a transmission line impedance corresponding to the level difference obtained by the level difference calculating means from the storage means, and setting the impedance matching means to the transmission line impedance. Control means for controlling the impedance between the narrowband antenna selected by the antenna selection means and the transmitter / receiver to be matched with each other.

  In this way, it is not necessary to provide a complicated circuit for performing impedance matching by previously storing a desired transmission line impedance for compensating for a difference in level of the received signal.

  In one embodiment, the impedance matching means has a variable capacitor provided between the plurality of antennas and the transceiver, and the storage means is between the capacitance of the variable capacitor and the transmission line impedance. The relationship is further stored.

  Thereby, the impedance of the transmission line can be matched by changing the capacitor capacity.

  Preferably, the wireless communication device of the present invention further includes frequency switching means for switching a communication frequency with the predetermined hopping pattern, and the frequency switching means selects a narrowband antenna that includes the communication frequency in a communication band. The antenna selection unit is instructed.

  Thus, even when a plurality of narrow-band antennas are provided instead of a single wide-band antenna, communication can be performed by selecting an appropriate antenna corresponding to the hopping frequency.

  Preferably, each communication band of the plurality of narrowband antennas includes one or more of communication frequencies constituting the predetermined hopping pattern, and the impedance matching unit is configured to select the antenna selection unit for each communication frequency. The impedance of the narrowband antenna selected by the transmitter and the transceiver is matched.

  Thereby, the number of narrowband antennas can be optimized according to the allowable scale and cost of the wireless communication device, the required performance, the characteristics of the narrowband antennas used, and the like.

  Preferably, the wireless communication apparatus of the present invention further includes a counter for measuring an elapsed time or the number of communication times from the start of communication, and the signal level detecting means is The level of the signal received by the narrowband antenna selected by the antenna selection unit is detected, and the impedance matching unit is selected by the antenna selection unit based on the level of the signal detected by the signal level detection unit The impedance between the narrow band antenna and the transceiver is matched.

  Thereby, it becomes possible to cope with a radio wave propagation environment in a space that changes from moment to moment, and high communication quality can be maintained.

  In order to achieve the above object, the impedance matching method of the present invention is included in a transmitter / receiver that transmits and receives a signal by switching a communication frequency with a predetermined hopping pattern in broadband communication, and the communication band of the broadband communication. An impedance matching method for matching impedances between each of the plurality of narrowband antennas and the transceiver in a wireless communication apparatus including a plurality of narrowband antennas having different communication bands, the predetermined hopping An antenna selection step of selecting at least one of the plurality of narrowband antennas according to a pattern, a signal level detection step of detecting a level of a signal received by the narrowband antenna selected in the antenna selection step, and the signal Based on the level of the signal detected in the level detection step There are, and an impedance matching step for matching the impedance between the narrowband antenna and the transceiver, which is selected by the antenna selecting step.

  Thereby, it is possible to provide an impedance matching method capable of following a temporal level fluctuation of a received signal in a wideband wireless communication apparatus using a plurality of narrowband antennas.

  In order to achieve the above object, the impedance matching program of the present invention is included in a transmitter / receiver that transmits and receives signals by switching a communication frequency with a predetermined hopping pattern in broadband communication, and the communication band of the broadband communication. An impedance matching program for matching impedances between each of the plurality of narrowband antennas and the transmitter / receiver in a wireless communication apparatus including a plurality of narrowband antennas having different communication bands, the computer, An antenna selection step of selecting at least one of the plurality of narrowband antennas according to a predetermined hopping pattern; and a signal level detection step of detecting a level of a signal received by the narrowband antenna selected in the antenna selection step; The signal level detecting step Based on the level of the detected signal, it is possible to perform an impedance matching step for matching the impedance between the narrowband antenna and the transceiver, which is selected by the antenna selecting step.

  As a result, it is possible to provide an impedance matching program that can follow a temporal level fluctuation of a received signal in a broadband wireless communication apparatus using a plurality of narrowband antennas.

  As one embodiment, the received signal level adjustment program of the present invention may be recorded on a computer-readable recording medium such as a compact disc (CD).

  In view of the above problems, the present invention provides a wireless communication apparatus, an impedance matching method, a program, and a recording medium for the wireless communication apparatus that can follow temporal level fluctuations of a received signal in a broadband wireless communication apparatus using a plurality of narrowband antennas. It becomes possible.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

[Constitution]
FIG. 1 shows a configuration of a wireless communication apparatus according to an embodiment of the present invention.

  The wireless communication device 1 in FIG. 1 transmits four antennas 100 to 103 having different communication bands, a receiver 10 that receives a signal via the antennas 100 to 103, and a signal via the antennas 100 to 103. The communication protocol (for example, information format and communication procedure) between the transmitter 20 and another wireless communication device that is a communication partner is defined, and the counter 131 has a counter 131, and an elapsed time and / or communication from the start of communication. It has a control unit 130 that monitors the number of times, and a storage unit 129 that stores software and data for controlling the processing of the control unit 130. Each communication band of the antennas 100 to 103 is included in a communication band for wideband communication performed by the wireless communication apparatus 1, and the wireless communication apparatus 1 uses the four narrowband antennas 100 to 103 to make the entire communication band for wideband communication. Cover.

  The wireless communication device 1 further includes a transmission / reception selector switch 106 that selects whether the device 1 operates as a receiver or a transmitter. The transmission / reception selector switch 106 is switched to form a reception path or a transmission path according to a switching signal supplied from the control unit 130.

  The wireless communication device 1 further includes an impedance matching unit 104 and an antenna selection circuit 105 between the antennas 100 to 103 and the transmission / reception changeover switch 106. The antenna selection circuit 105 can select at least one of the four antennas 100 to 103 to transmit or receive a signal. The impedance matching unit 104 is inserted between the antennas 100 to 103 and the antenna selection circuit 105 to match the impedance of each antenna selected by the selection circuit 105 with the receiver 10 or the transmitter 20.

  The receiver 10 includes a low noise amplifier (LNA) 107, two mixers 109 and 110, two bandpass filters (BPF) 112 and 113, a received signal strength detector (RSSI) 117, and two variable gains. Amplifiers 120 and 121, an automatic gain control (AGC) processing unit 123, a signal level detection unit 124, and a demodulation unit 125 are included. Further, the receiver 10 shares the frequency synthesizer 30 with the transmitter 20.

  The LNA 107 amplifies the broadband wireless signal received via the antenna 100, 101, 102 or 103 selected by the selection circuit 105. The mixers 109 and 110 are signal mixing means for multiplying the amplified wideband radio signal by the radio communication frequency signal generated by the frequency synthesizer 30, thereby generating I and Q baseband signals. The BPFs 112 and 113 extract only signals having a predetermined frequency band from the baseband signals generated by the mixers 109 and 110.

  The RSSI 117 is signal strength detection means for detecting the strength of the received signal by detecting the direct current (DC) voltage level of the baseband signal filtered by the BPFs 112 and 113. The signal level detection unit 124 can detect the signal level of the received broadband wireless signal based on the strength of the received signal detected by the RSSI 117 and output it as a digital value.

  The VGAs 120 and 121 are amplifiers capable of switching the gain every several dB steps. Based on the signal level detected by the signal level detection unit 124, the AGC processing unit 123 automatically increases the amplification factors (ie, gains) of the VGAs 120 and 121 so that a constant output can be obtained even when the amplitude of the received signal varies. .). Therefore, the VGAs 120 and 121 are controlled by the AGC processing unit 123 to switch the gain according to the input level (that is, amplitude) of the received broadband wireless signal, and are filtered by the BPFs 112 and 113 according to this gain. A baseband signal can be amplified. The baseband signals thus amplified by the VGAs 120 and 121 are input to the demodulation unit 125 and demodulated.

  The transmitter 20 includes a power amplifier (PA) 108, an adder 111, mixers 114 and 115, and a modulation unit 128.

  Data transmitted to another wireless communication apparatus is sent by the control unit 130 to the modulation unit 128 according to a predetermined protocol that satisfies the communication protocol. Modulation section 128 performs modulation processing and band control on the data, separates the data into in-phase components and quadrature components, and inputs them to mixer 114 or 115, respectively. The mixers 114 and 115 multiply the in-phase component signal or the quadrature component signal by the radio communication frequency signal generated by the frequency synthesizer 30. Adder 111 adds the signals output from mixers 114 and 115 and outputs the result to PA 108. The PA 108 amplifies the level of the signal output from the adder with a predetermined gain. The amplified signal is transmitted to another wireless communication device via the antenna 100, 101, 102, or 103 selected by the selection circuit 105.

  The frequency synthesizer 30 is a signal generating unit that generates a radio communication frequency signal multiplied by the mixers 109 and 110 of the receiver 10 and the mixers 114 and 115 of the transmitter 20, and includes a phase rotation unit 116, a phase lock loop (PLL) ) Circuit portion 118, voltage controlled oscillator (VCO) 119, and crystal oscillator 122. The PLL circuit unit 118, the VCO 1119, and the crystal oscillator 122 form a phase locked loop (PLL). The phase rotation unit 116 generates two signals whose phases are rotated by 0 degree and 90 degrees from the signal output from the PLL, and inputs the two signals to the respective mixers as radio communication frequency signals.

  In addition, when the frequency hopping method is adopted, the wireless communication device 1 further includes a frequency switching unit 127 that switches the frequency of the wireless communication frequency signal according to the reception hopping frequency. The frequency switching unit 127 instructs the frequency synthesizer 30 to switch the frequency of the radio communication frequency signal generated by the frequency synthesizer 30 in accordance with the frequency hopping pattern defined between the control unit 130 and another radio communication device. Supply a frequency switching signal. Furthermore, the frequency switching unit 127 supplies an antenna selection signal that instructs the selection circuit 105 to select at least one of the antennas 100 to 103 according to the frequency hopping pattern.

  The frequency hopping pattern is stored in the storage unit 129, for example, in the format shown in FIG. In FIG. 2, a plurality of various hopping patterns 22 are given different hopping numbers (No) 21 and can be identified thereby. The frequency hopping pattern to be used is determined in a connection / authentication process performed in advance with another wireless communication apparatus as a communication partner. The control unit 130 notifies the frequency switching unit 127 of the frequency to be hopped (herein referred to as “hopping frequency”) according to the determined frequency hopping pattern. Note that the format shown in FIG. 2 is an example, and the frequency hopping pattern may be stored in the storage unit 129 in another manner without being limited to the table format as long as it is associated with a specific hopping number.

  FIG. 3 shows details of the configuration of the frequency switching unit 127.

  The frequency switching unit 127 in FIG. 3 includes a switching signal generation unit 31 and a frequency setting storage unit 32. The switching signal generation unit 31 includes a frequency switching signal for instructing the frequency synthesizer 30 to switch the frequency of the generated radio communication frequency signal to the hopping frequency notified from the control unit 130, and the hopping frequency notified from the control unit 130 An antenna selection signal for instructing the selection circuit 105 to select an antenna having a communication band is generated. The frequency setting storage unit 32 stores, for example, information related to the setting value and the antenna number corresponding to the hopping frequency notified from the control unit 130 in the format shown in FIG.

  In FIG. 4, a plurality of different hopping frequencies 41 are assigned different setting values 42, respectively. For example, the setting value 0x00 is assigned to the hopping frequency of 3432 MHz. The switching signal generation unit 31 reads a setting value corresponding to the hopping frequency notified by the control unit 130 from the frequency setting storage unit 32, and uses the setting value as a frequency switching signal to the frequency synthesizer 30, specifically, the PLL 118. Notify a register (not shown).

  In FIG. 4, a plurality of different hopping frequencies 41 are assigned different antenna numbers for each set, with three consecutive different frequencies as a set. For example, three consecutive hopping frequency sets of 3432 MHz, 3960 MHz, and 4488 MHz are assigned antenna number 1, and three consecutive hopping frequency sets of 5016 MHz, 5544 MHz, and 6072 MHz are assigned antenna number 2. The antenna number 3 is assigned to the set of three consecutive hopping frequencies of 6600 MHz, 7128 MHz, and 7656 MHz, and the antenna number 4 is assigned to the set of three consecutive hopping frequencies of 8184 MHz, 8712 MHz, and 9240 MHz. The antenna numbers 1 to 4 correspond to the antennas 100 to 103, respectively. The switching signal generation unit 31 reads the antenna number corresponding to the hopping frequency notified by the control unit 130 from the frequency setting storage unit 32 and notifies the antenna selection circuit 105 of the antenna number as an antenna selection signal. Therefore, the antenna 100 corresponding to the antenna number 1 is selected by the selection circuit 105 notified of the antenna number when the hopping frequency is set to 3432 MHz, 3960 MHz, or 4488 MHz, and the antenna 101 corresponding to the antenna number 2 is selected. The antenna 102 corresponding to the antenna number 3 is selected when the hopping frequency is set to 5016 MHz, 5544 MHz or 6072 MHz, and the antenna 102 corresponding to the antenna number 3 is selected when the hopping frequency is set to 6600 MHz, 7128 MHz or 7656 MHz. The corresponding antenna 103 is selected when the hopping frequency is set to 8184 MHz, 8712 MHz, or 9240 MHz.

  The format shown in FIG. 4 is an example, and the hopping frequency, the set value, and the antenna number may be stored in the frequency setting storage unit 32 in other forms as well as the table format as long as they are stored in association with each other. good.

  Returning to FIG. 1 again, the signal level detection unit 124 detects the level of the signal received by the antenna selected by the antenna selection circuit 105 as described above. In this example, since three hopping frequencies are assigned to one antenna, the signal level detection unit 124 detects the level of the signal received by the selected antenna for each hopping frequency.

  The control unit 130 further includes a level difference calculation unit 132 that compares the level of the signal detected by the signal level detection unit 124 with a predetermined reference level to obtain the difference. For example, the reference level is the lowest level among the signal levels detected by the signal level detection unit 124. The control unit 130 selects the impedance matching unit 104 by the selection circuit 105 so that the level of the signal received at another hopping frequency other than the hopping frequency indicating the lowest level matches the lowest level as the reference level. Control is performed so that the impedance of the antenna and the receiver 10 or the transmitter 20 is matched. Specifically, for such control, the storage unit 129 stores the relationship between the signal level difference and the transmission line impedance, and the control unit 130 calculates the level calculated by the level difference calculation unit 132. The transmission line impedance corresponding to the difference is acquired from the storage unit 129, and the impedance matching unit 104 determines the impedance between the antenna selected by the selection circuit 105 and the receiver 10 or the transmitter 20 so as to match the transmission line impedance. Control to match.

  FIG. 5 shows details of the configuration of the impedance matching unit 104.

  The impedance matching unit 104 in FIG. 5 is inserted between the antennas 100 to 103 and the antenna selection circuit 105 as shown in FIG. 1, and has a variable capacitor 51 and a voltage for changing the capacitance of the capacitor 51. And a voltage generator 52 for generating the voltage. The voltage generation unit 52 changes the capacitance of the capacitor 51 in accordance with the control signal from the control unit 130, thereby matching the impedance of the antenna selected by the selection circuit 105 and the receiver 10 or the transmitter 20 with a predetermined transmission line impedance. Can be matched.

  Further, the impedance matching unit 104 can further have a configuration in which the transmission line impedance is infinite. This configuration can be realized, for example, by providing a switch (not shown) that opens a transmission path between each antenna and the selection circuit 105. When the transmission line impedance is infinite, the carrier wave can be totally reflected, so that it is possible to prevent radio waves from being instantaneously transmitted into the air during data transmission. This is advantageous in situations where, for example, when a radar for military use is detected, transmission of a radio wave in a specific hopping frequency band must be stopped immediately due to regulations in the Radio Law.

  FIG. 6 shows parameters for impedance matching stored in the storage unit 129.

  As shown in FIG. 6, the storage unit 129 includes, for each antenna, a control voltage 61 (unit millivolt [mV]) generated by the voltage generation unit 52 to change the capacitance of the capacitor 51, and a control voltage. Notification level 62 that represents 61 in digital form, capacitance 63 of capacitor 51 (unit picofarad [pF]), transmission line impedance 64 (unit ohm [Ω]), and adjustment value for compensating for level difference 65 (unit decibel [dB]) and a received signal level difference 66 (unit millivolt [mV]) are stored in association with each other.

  From FIG. 6, the level difference calculated by the level difference calculation unit 132 can be compensated for the level difference, and the adjustment value 65 that makes the level of the received signal equal to the reference level can be known. The transmission line impedance 64 represents the impedance value of the transmission line between the selected antenna and the receiver 10 or the transmitter 20 in order to obtain this adjustment value. The capacitance 63 is a capacitance value of the variable capacitor 51 for realizing the corresponding transmission line impedance. In order to set the capacitance of the variable capacitor 51 to a desired capacitance value, the control unit 130 transmits a control signal having a notification level 62 representing the control voltage 61 corresponding to the capacitance value to the voltage generating unit 52.

  In FIG. 6, the notification level 62 is only 1 to 5. However, when the bit width of the impedance matching unit 104 is 8 bits, 256 notification levels are possible.

  Moreover, the format shown in FIG. 6 is an example, and as long as each parameter is stored in association with each other, it is not limited to the table format and may be stored in the storage unit 129 in another manner. For example, the storage unit 129 can alternatively store the correspondence between parameters as shown in FIG.

  7A shows the relationship between the capacitance of the variable capacitor 51 and the transmission line impedance, and FIG. 7B shows the relationship between the transmission line impedance and the transmission loss. In FIG. 7A, the horizontal axis represents the capacitance of the variable capacitor 51 in terms of the picofarad [pF], and the vertical axis represents the transmission line impedance in unit ohms [Ω]. In FIG. 7B, the horizontal axis represents transmission line impedance in unit ohm [Ω], and the vertical axis represents transmission loss in unit decibel [dB]. Since the input impedance of the antenna is generally fixed at 50Ω, the transmission loss is 0 dB when the transmission line impedance is 50Ω. However, it takes a negative value when the transmission line impedance is other than 50Ω. In other words, when the transmission line impedance is other than 50Ω, a loss occurs in the transmission line, and the signal level decreases by the amount of the loss. By utilizing this fact, when the lowest level among the signal levels detected by the signal level detection unit 124 is set as the reference level, the signal is received at a hopping frequency other than the hopping frequency indicating the lowest level. The signal level can be adjusted to the lowest level as the reference level.

  Hereinafter, the operation of the wireless communication apparatus 1 of the present invention in the embodiment shown in FIG. 1 will be described.

[Connection / Authentication]
The wireless communication device 1 first performs a connection / authentication operation in order to transmit and receive signals to and from other wireless communication devices that are communication partners.

  The control unit 130 starts a scanning operation in accordance with an instruction from an upper layer protocol. As described above, the antennas 100 to 103 have different communication bands in the communication band of the broadband communication performed by the wireless communication device 1. Therefore, when performing the scanning operation over the entire communication band of the broadband communication, the antenna selection circuit 105 selects the antennas 100 to 103 according to the antenna selection signal supplied from the control unit 130 via the frequency switching unit 127. It switches as follows.

  During the scan operation, since the communication rate is low and high transmission / reception performance is not required, the need for impedance matching by the impedance matching unit 104 is low. Therefore, in this case, the control unit 130 does not instruct the impedance matching unit 104 to perform impedance matching, and the impedance matching unit 104 remains at a default setting (for example, 50Ω which is a normal antenna impedance).

  When another wireless communication device as a communication partner is found by the scanning operation, the wireless communication device 1 performs a connection / authentication process in accordance with the communication protocol with the other wireless communication device. At this time, the wireless communication device 1 also exchanges frequency hopping patterns with other wireless communication devices at the same time. The hopping pattern is usually exchanged with a pattern number according to the communication protocol. As shown in FIG. 2, since a plurality of various hopping patterns 22 are stored in the storage unit 129 in association with a specific hopping number, the control unit 130 refers to the storage unit 129 and other types The corresponding frequency hopping pattern can be known from the hopping number obtained by exchanging with the wireless communication device.

[Transmission operation]
A flow of a transmission operation by the wireless communication device 1 of the present embodiment is shown in FIG. 8 as an example.

  After the above connection / authentication process is completed, in step S101, the control unit 130 notifies the frequency switching unit 127 of the hopping frequency according to the frequency hopping pattern determined in the connection / authentication process. The hopping frequency notified from the control unit 130 is received by the switching signal generation unit 31 of the frequency switching unit 127.

  As shown in FIG. 4, the frequency setting storage unit 32 of the frequency switching unit 127 stores information related to setting values and antenna numbers corresponding to hopping frequencies. Accordingly, in step S102, the switching signal generation unit 31 reads a setting value corresponding to the hopping frequency notified by the control unit 130 from the frequency storage unit 32, and notifies the frequency synthesizer 30 of this setting value as a frequency switching signal. Thereby, the frequency synthesizer 30 can generate a radio communication frequency signal at the hopping frequency. In addition, in step S103, the switching signal generation unit 31 reads the antenna number corresponding to the hopping frequency notified by the control unit 130 from the frequency storage unit 32, and notifies the antenna selection circuit 105 of the antenna number as an antenna selection signal. To do. As a result, the antenna selection circuit 105 can be switched to select an antenna that includes the hopping frequency in the communication band.

  Before the transmission is started, in step S104, the control unit 130 switches the transmission / reception selector switch 106 with a switching signal to form a transmission path.

  At the time of transmission, in step 105, the control unit 130 transmits the data transmitted from the higher layer protocol to the modulation unit 128 according to a predetermined communication protocol that satisfies the communication protocol. In step S106, the modulation unit 128 performs modulation processing and band control on the data, separates the data into in-phase components and quadrature components, and inputs them to the mixer 114 or 115, respectively. In step S <b> 107, the mixers 114 and 115 convert the radio communication frequency signal generated by the frequency synthesizer 30 into the in-phase component signal or the quadrature component signal (the radio communication frequency signal input to the mixer 115 is input to the mixer 114. Is rotated 90 degrees relative to the object). In step S108, the adder 111 adds the signals output from the mixers 114 and 115, and the PA 108 amplifies the level of the signal added by the adder 111 with a predetermined gain. In step S109, the amplified signal is transmitted to another wireless communication device via the antenna 100, 101, 102, or 103 selected by the selection circuit 105.

  After that, if there is still data to be transmitted in step S110, the series of processing in steps S101 to S109 is repeated.

  Here, when the wireless communication device 1 transmits by itself, an appropriate antenna corresponding to the hopping frequency is selected by the antenna selection circuit 105. Therefore, the impedance matching unit 104 is used to perform impedance matching. The need to do is low.

[Receive operation]
Next, FIG. 9 shows an example of a flow of a reception operation performed by the wireless communication device 1 according to this embodiment.

  After the above connection / authentication process is completed, in step S201, the control unit 130 notifies the frequency switching unit 127 of the hopping frequency according to the frequency hopping pattern determined in the connection / authentication process. The hopping frequency notified from the control unit 130 is received by the switching signal generation unit 31 of the frequency switching unit 127.

  As shown in FIG. 4, the frequency setting storage unit 32 of the frequency switching unit 127 stores information related to setting values and antenna numbers corresponding to hopping frequencies. Accordingly, in step S202, the switching signal generation unit 31 reads the setting value corresponding to the hopping frequency notified by the control unit 130 from the frequency storage unit 32, and notifies the frequency synthesizer 30 of this setting value as a frequency switching signal. Thereby, the frequency synthesizer 30 can generate a radio communication frequency signal at the hopping frequency. In addition, in step S203, the switching signal generation unit 31 reads the antenna number corresponding to the hopping frequency notified by the control unit 130 from the frequency storage unit 32, and notifies the antenna selection circuit 105 of the antenna number as an antenna selection signal. To do. As a result, the antenna selection circuit 105 can be switched to select an antenna that includes the hopping frequency in the communication band.

  Before the reception is started, in step S204, the control unit 130 switches the transmission / reception selector switch 106 with a switching signal to form a reception path.

  In step S205, the broadband wireless signal is received by the antenna 100, 101, 102, or 103 selected by the antenna selection circuit 105, and is input to the LNA 107 after passing through a switch, a diplexer, and / or a BPF (not shown). Is done. In step S206, the reception signal amplified by the LNA 107 is input to the two mixers 109 and 110, and the radio communication frequency signal generated by the frequency synthesizer 30 (the radio communication frequency signal input to the mixer 110 is 90 degrees phase rotated with respect to what is input to the mixer 109). As a result, a beat (difference frequency) signal is generated as a baseband signal of the I and Q channels. In step S207, these signals are input to the BPFs 112 and 113, respectively, and signal components outside the predetermined band are removed. The two filtered signals are then detected for their DC voltage levels by RSSI 117 in step S208. In step S209, the two filtered signals are amplified by the VGAs 120 and 121, respectively, and then demodulated by the demodulation unit 125 in step S210.

  Thereafter, if a broadband wireless signal is still received in step S211, a series of processing in steps S201 to S210 is repeated.

  However, at the time of reception, there is a problem that the reception level varies for each hopping frequency due to the power difference between bands originally possessed by the communication partner and the fluctuation of the power value due to spatial multipath fading. Therefore, the wireless communication device 1 needs to optimize the impedance matching unit 104 according to the reception level. FIG. 10 shows an example of a flow of impedance matching operation at the time of reception by the wireless communication device 1 of the present embodiment.

  When the broadband wireless signal is received, the RSSI 117 detects the DC level (representing the strength of the received signal) in step S301 as described with reference to FIG. In step S302, the signal detection unit 124 detects the signal level of the received broadband wireless signal based on the strength of the received signal detected by the RSSI 117, and outputs it as a digital value. Thereafter, the processing in steps S301 and S302 is repeated until the received signal level is detected for all hopping frequencies included in the current frequency hopping pattern in step S303. At this time, the antenna selection circuit 105 switches to select an antenna that includes a predetermined hopping frequency in the communication band from the antennas 100 to 103 in accordance with an antenna selection signal supplied from the control unit 130 via the frequency switching unit 127. . After the received signal levels are detected for all the hopping frequencies, in step S304, the level difference calculation unit 132 of the control unit 130 obtains a level difference between each of the received signal levels and a predetermined reference level. As described above, the predetermined reference level may be the lowest level among the signal levels detected by the signal level detection unit 124.

  As shown in FIG. 6 and FIG. 7, the storage unit 129 stores parameters for impedance matching corresponding to the level difference. Therefore, the control unit 130 refers to the storage unit 129 in step S305. The transmission line impedance corresponding to the calculated level difference is known. In step S306, the control unit 130 sets the capacitance of the variable capacitor 51 of the impedance matching unit 104 to a desired capacitance value in order to realize this transmission line impedance, and the control voltage corresponding to the capacitance value. Is transmitted to the voltage generator 52 of the impedance matching unit 104.

  In step S307, the voltage generation unit 52 changes the capacitance of the capacitor 51 in accordance with the control signal from the control unit 130, thereby matching the impedance between each antenna and the receiver 10 so as to match a predetermined transmission line impedance. . Since the impedance of the antenna is generally fixed at 50Ω, the reflected wave at the antenna input end can be obtained by shifting the characteristic impedance of the transmission path between each of the antennas 100 to 103 and the receiver 10 or the transmitter 20 from 50Ω. The ratio becomes relatively large, and the VSWR deteriorates. As a result, the level of the signal received at a hopping frequency other than the hopping frequency indicating the lowest level as the reference signal is adjusted to this lowest level, and the level difference is compensated.

  The concept of level difference compensation realized by this impedance matching operation is shown in FIG. In FIG. 11, to simplify the description, it is assumed that one hopping frequency is assigned to each of the four antennas 100 to 103 of the wireless communication apparatus 1.

  In FIG. 11, (a) shows the reception level of each antenna in an ideal case, and (b) shows the actual reception level of each antenna. The reception levels of each antenna are ideally all equal, as shown in (a), but in practice, as shown in (b), due to the difference in characteristics between hopping frequencies, Different for each antenna.

  FIG. 11C shows the VSWR of each antenna before and after performing impedance matching. Prior to performing impedance matching, all VSWRs of each antenna have equal values. However, impedance matching is performed in order to match other reception levels to the lowest reception level X among the reception levels of each antenna shown in FIG. The VSWR of other antennas deteriorates depending on the degree of impedance matching. As a result, as shown in FIG. 11D, the reception levels of the respective antennas are all equal at the reception level X.

  The transmission operation may be performed using the impedance matching unit 104 optimized as described above as it is. However, in a state where neither transmission nor reception is performed, the impedance matching unit 104 is controlled by the control unit 130 to shift to a default state (that is, impedance = 50Ω).

  In order to obtain good communication performance, in most cases, it is necessary that both apparatuses that perform communication have some same means. However, as is clear from the above-described embodiment, in the wireless communication device of the present invention, it is not necessary that another device serving as a communication partner has the same configuration as the wireless communication device.

[Implementation of impedance matching operation after elapse of a predetermined time or a predetermined number of communications]
As illustrated in FIG. 1, the wireless communication device 1 includes a counter 131 in the control unit 130. By measuring the elapsed time and / or the number of communications from the start of communication by this counter 131, the impedance matching operation described with reference to FIG. 10 is performed every time a predetermined time elapses and / or every predetermined number of communications. Is possible.

  FIG. 12 shows an example of the flow of impedance matching operation for every predetermined time and the predetermined number of times of communication performed by the wireless communication apparatus 1 of the present embodiment.

  First, in step S <b> 401, the wireless communication device 1 starts communication with a transmission-side device (not shown) according to the communication protocol defined in the control unit 130.

  In step S402, the control unit 130 monitors communication with the transmission-side apparatus and determines whether communication is established. For example, when communication is not established at the time of step S402 due to completion of data transmission from the transmission side device, the control unit 130 performs communication end processing in step S408.

  On the other hand, if communication has been established, in step S403, the control unit 130 uses the counter 131 to measure the time elapsed since the communication with the transmission side apparatus was started. In addition, in step S404, the control unit 130 causes the counter 131 to count the number of packets received from the transmission side device.

  Thereafter, in step S405, the control unit 130 refers to the counter 131 to determine whether a predetermined time has elapsed. If the predetermined time has elapsed, in step S407, the control unit 130 controls each unit of the wireless communication device 1 to perform an impedance matching operation as shown in the flowchart of FIG.

  If the predetermined time has not yet elapsed, in step S406, the control unit 130 refers to the counter 131 and determines whether or not the number of received packets has reached the predetermined number. When a predetermined number of packets are received, the control unit 130 controls each unit of the wireless communication device 1 in step S407, and performs an impedance matching operation as illustrated in FIG.

  Note that the wireless communication device 1 may perform the impedance matching operation based only on either the elapsed time from the start of communication or the number of times of communication.

  Thus, by providing the counter and performing the impedance matching operation every predetermined time or every predetermined number of times of communication, it becomes possible to cope with a radio wave propagation environment in a space that changes every moment, and high communication quality can be maintained.

[Modification]
Although the best mode for carrying out the invention has been described above, the present invention is not limited to the embodiment described in the best mode. Modifications can be made without departing from the spirit of the present invention.

  For example, in the embodiment described above as an example, the wireless communication apparatus covers the entire communication band of wideband wireless communication by using four narrowband antennas. However, the number of antennas used can be appropriately selected according to the allowable size and cost of the wireless communication device, the required performance, the characteristics of the narrowband antenna, and the like. For example, one antenna can be provided for each hopping frequency when there is a sufficient device size and high communication quality is required. On the other hand, when an increase in device size and cost becomes a problem, a plurality of continuous hopping frequencies can be assigned to one antenna within a range permitted by the antenna characteristics.

  The impedance matching operation of the present invention is stored in a memory such as a hard disk (HDD), a read-only memory (ROM), or a computer-readable recording medium such as a compact disk (CD) of the information processing apparatus. It may be realized by a program or as hardware in the information processing apparatus. For example, FIG. 6 shows the configuration of a computer that executes the impedance matching program of the present invention.

  The computer 200 in FIG. 13 includes a drive device 60, an auxiliary storage device 62, a memory device 64, an arithmetic processing device 66 such as a microprocessor, and an interface device 68 that are connected to each other by a bus 70.

  The drive device 60 is a device for reading the recording medium 300. When the recording medium 300 in which a program for realizing processing in the computer 200 (that is, an impedance matching program) is recorded is set in the drive device 60, the program is transferred from the recording medium 300 to the auxiliary storage device 62 via the drive device 60. Installed.

  The interface device 68 is a device for connecting the computer 200 to an external network. The computer 200 can also obtain a program from a server or the Internet via an external network. Alternatively, the computer 200 may have a program recorded in advance in a built-in memory.

  The auxiliary storage device 62 is a device that stores programs that are installed or acquired via a network, and that stores necessary files, data, and the like. The memory device 64 is a device that reads a program from the auxiliary storage device 62 and stores it when there is an instruction to start the program. The arithmetic processing unit 66 is a device that causes the computer 200 to execute a function according to a program stored in the memory device 64.

  Alternatively, the arithmetic processing unit 66 may be a dedicated semiconductor IC for light intensity detection according to the present invention. In that case, the arithmetic processing unit 66 executes the program recorded in the internal or external memory to perform the impedance matching operation.

  As described above, the computer can cause the computer to execute the impedance matching method of the present invention.

  Finally, the present invention can be applied to a wireless communication apparatus compatible with broadband wireless communication, and is useful not only for WirelessUSB but also for other wireless communication systems in which temporal level fluctuations in received signals are a problem. .

1 illustrates a configuration of a wireless communication device according to an embodiment of the present invention. An example of a frequency hopping pattern is shown. The detail of a structure of the frequency switching part of FIG. 1 is represented. The content of the frequency setting memory | storage part of FIG. 3 is represented. 2 shows details of the configuration of the impedance matching device of FIG. 1 represents parameters for impedance matching stored in a table format in the storage unit of FIG. FIG. 3 shows impedance matching parameters stored in another format in the storage unit of FIG. 4 shows a flow of a transmission operation by the wireless communication apparatus of the present embodiment. 6 shows a flow of a receiving operation by the wireless communication apparatus of the present embodiment. The flow of the impedance matching operation | movement at the time of reception by the wireless communication apparatus of this embodiment is shown. A concept of level difference compensation realized by an impedance matching operation by the wireless communication apparatus of this embodiment will be described. The flow of the impedance matching operation | movement for every predetermined time progress by the radio | wireless communication apparatus of this embodiment and predetermined frequency | count of communication is shown. 2 shows a configuration example of a computer that executes an impedance matching program of the present invention. It represents the relationship between packets and symbols in wireless communication. The radiation efficiency and VSWR are shown for a case where a single wideband antenna is used and a case where a plurality of narrowband antennas are used, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 10 Receiver 20 Transmitter 100-103 Antenna 104 Impedance matching device 105 Antenna selection circuit 124 Signal level detection part 127 Frequency switching part 129 Memory | storage part 130 Control part 131 Counter 132 Level difference calculation part 51 Variable capacitor 52 Voltage generation Part 200 computer 300 recording medium 66 arithmetic processing unit

Claims (19)

A wireless communication device including a transceiver for transmitting and receiving signals by switching a communication frequency with a predetermined hopping pattern in broadband communication,
A plurality of narrowband antennas having different communication bands included in the communication band of the broadband communication;
Antenna selection means for selecting at least one of the plurality of narrowband antennas according to the predetermined hopping pattern;
Signal level detection means for detecting the level of the signal received by the narrowband antenna selected by the antenna selection means;
A wireless communication apparatus comprising: an impedance matching unit configured to match an impedance between a narrowband antenna selected by the antenna selection unit and the transceiver based on a level of a signal detected by the signal level detection unit. Storage means for storing the relationship between the difference in signal level and the transmission line impedance;
A transmission line corresponding to the level difference obtained by the level difference calculating means, comprising level difference calculating means for obtaining a level difference between the level of the signal detected by the signal level detecting means and a predetermined reference level; Impedance is acquired from the storage means, and the impedance matching means is controlled to match the impedance between the narrowband antenna selected by the antenna selection means and the transceiver so as to match the transmission line impedance. The wireless communication apparatus according to claim 1, further comprising a control unit. The impedance matching means includes a variable capacitor provided between the plurality of antennas and the transceiver.
The wireless communication apparatus according to claim 2, wherein the storage unit further stores a relationship between a capacitance of the variable capacitor and the transmission line impedance. A frequency switching means for switching a communication frequency with the predetermined hopping pattern;
The radio communication apparatus according to claim 1, wherein the frequency switching unit instructs the antenna selection unit to select a narrowband antenna that includes the communication frequency in a communication band. Each communication band of the plurality of narrowband antennas includes one or more of the communication frequencies constituting the predetermined hopping pattern,
The radio according to any one of claims 1 to 4, wherein the impedance matching unit matches the impedance between the narrowband antenna selected by the antenna selection unit and the transceiver for each communication frequency. Communication device. It further has a counter for measuring the elapsed time from the start of communication or the number of communication,
Every time a predetermined time passes or every predetermined number of communications,
The signal level detection means detects the level of the signal received by the narrowband antenna selected by the antenna selection means,
The impedance matching means matches the impedance between the narrowband antenna selected by the antenna selection means and the transceiver based on the level of the signal detected by the signal level detection means. The wireless communication device according to any one of 5. Radio communication apparatus comprising: a transmitter / receiver that transmits and receives signals by switching a communication frequency with a predetermined hopping pattern in broadband communication; and a plurality of narrowband antennas having different communication bands included in the communication band of the broadband communication An impedance matching method for matching impedance between each of the plurality of narrowband antennas and the transceiver,
An antenna selection step of selecting at least one of the plurality of narrowband antennas according to the predetermined hopping pattern;
A signal level detection step of detecting a level of a signal received by the narrowband antenna selected in the antenna selection step;
An impedance matching method comprising: an impedance matching step for matching impedance between the narrowband antenna selected in the antenna selection step and the transceiver based on the level of the signal detected in the signal level detection step. A level difference calculating step for obtaining a level difference between the level of the signal detected in the signal level detecting step and a predetermined reference level;
The impedance matching step acquires the transmission line impedance corresponding to the level difference obtained in the level difference calculation step from the storage means of the wireless communication device that stores the relationship between the signal level difference and the transmission line impedance, The impedance matching method according to claim 7, wherein the impedance between the narrowband antenna selected in the antenna selection step and the transceiver is matched so as to match the transmission line impedance.   The impedance matching method according to claim 7 or 8, wherein the impedance matching step includes a step of changing a capacitance of a variable capacitor provided between the plurality of antennas and the transceiver. A frequency switching step of switching a communication frequency with the predetermined hopping pattern;
The impedance matching method according to claim 7, wherein the antenna selection step selects a narrowband antenna that includes a communication frequency switched in the frequency switching step in a communication band. Each communication band of the plurality of narrowband antennas includes one or more of the communication frequencies constituting the predetermined hopping pattern,
The impedance according to any one of claims 7 to 10, wherein the impedance matching step matches impedance between the narrowband antenna selected by the antenna selection unit and the transceiver for each communication frequency. Alignment method. The method further includes a step of measuring an elapsed time from the start of communication or the number of communication.
12. The impedance matching method according to claim 7, wherein the signal level detection step and the impedance matching step are repeated every time a predetermined time elapses or every predetermined number of times of communication. Radio communication apparatus comprising: a transmitter / receiver that transmits and receives signals by switching a communication frequency with a predetermined hopping pattern in broadband communication; and a plurality of narrowband antennas having different communication bands included in the communication band of the broadband communication An impedance matching program for matching impedance between each of the plurality of narrowband antennas and the transceiver,
On the computer,
An antenna selection step of selecting at least one of the plurality of narrowband antennas according to the predetermined hopping pattern;
A signal level detection step of detecting a level of a signal received by the narrowband antenna selected in the antenna selection step;
Impedance matching for executing the impedance matching step of matching the impedance between the narrowband antenna selected in the antenna selection step and the transceiver based on the level of the signal detected in the signal level detection step program. In the computer,
A level difference calculating step for obtaining a level difference between the level of the signal detected in the signal level detecting step and a predetermined reference level;
In the impedance matching step, acquire the transmission line impedance corresponding to the level difference obtained in the level difference calculation step from the storage means of the wireless communication device that stores the relationship between the signal level difference and the transmission line impedance; 14. The impedance matching program for executing the step of matching impedance between the narrow band antenna selected in the antenna selection step and the transceiver so as to match the transmission line impedance. In the computer,
15. The impedance matching program according to claim 13 or 14, wherein, in the impedance matching step, a step of changing a capacitance of a variable capacitor provided between the plurality of antennas and the transceiver is executed. Causing the computer to further execute a frequency switching step of switching a communication frequency with the predetermined hopping pattern;
The impedance matching program according to any one of claims 13 to 15, wherein, in the antenna selecting step, a step of selecting a narrowband antenna including a communication frequency switched in the frequency switching step in a communication band is executed. When each communication band of the plurality of narrowband antennas includes one or more of communication frequencies constituting the predetermined hopping pattern,
17. The impedance matching step according to claim 13, wherein the step of matching the impedance between the narrowband antenna selected by the antenna selection means and the transceiver is executed for each communication frequency. The impedance matching program according to one item. In the computer,
Further executing the step of measuring the elapsed time or the number of communication since the start of communication,
The impedance matching program according to any one of claims 13 to 17, wherein the signal level detecting step and the impedance matching step are repeatedly executed every time a predetermined time elapses or every predetermined number of times of communication.   A computer-readable recording medium on which the impedance matching program according to any one of claims 13 to 18 is recorded.

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