JP4742859B2 - Radio, control method and program - Google Patents

Description

  The present invention relates to a radio equipped with a function for detecting an empty channel, a control method, and a program.

  In the wireless communication system, in order to prevent interference, each transmitter needs to have a function of confirming whether or not the transmission channel is an empty channel before using the transmission channel.

  FIG. 8 is a block diagram of a conventional analog wireless terminal 100. Each element of the analog wireless terminal 100 in the block diagram is the same as the element of the same sign in FIG. 1 described later except for the squelch circuit 101 and the A / D converter 102, and detailed description thereof is omitted. Only the main points regarding the empty channel detection function will be described.

  The squelch circuit 101 detects the radio wave intensity of the frequency tuned in the mixer 15, that is, the frequency of the channel selected by the analog radio terminal 100, from the output of the FM detection IC 35, and outputs it. When the currently selected channel tuned in the mixer 15 is BUSY (in use), the output level of the squelch circuit 101 is equal to or higher than a predetermined value.

  The A / D converter 102 A / D converts the output of the squelch circuit 101 and outputs the result to the CPU 41. The CPU 41 determines whether or not the channel selected by the analog wireless terminal 100 is BUSY based on the input from the A / D converter 102. That is, when the radio wave intensity of the frequency of the channel selected by the analog wireless terminal 100 is equal to or higher than a predetermined value, the channel is determined to be BUSY, and when it is lower than the predetermined value, the channel is Judge as an empty channel.

  FIG. 9 is a block diagram of a conventional digital wireless terminal 110. The elements of the digital wireless terminal 110 in the block diagram are the same as those of the same reference numerals in FIG.

  The received signal of the channel selected by the digital wireless terminal 110 by tuning in the mixer 15 is detected by the FM detection IC 35 and then sent to a DSP (Digital Signal Processor) 39. The DSP 39 generates digital data from the input signal from the FM detection IC 35. When the generated digital data includes a predetermined frame synchronization code and the frame synchronization code can be received periodically, it is determined that the selected channel is BUSY.

Patent Document 1 discloses a squelch control unit that opens and closes a squelch gate. The squelch control unit pays attention to the fact that the rectified voltage obtained by rectifying the noise in the detection signal increases as the strength of the communication signal decreases, and divides the frequency range of the noise into a plurality of frequency segments. In addition, a noise rectified voltage is generated and compared with each reference value, and the squelch gate is opened and closed based on the comparison.
JP 2004-56183 A

  When shifting from an analog wireless communication system to a digital wireless communication system, it is difficult to switch all analog wireless terminals and wireless relay systems from analog to digital in terms of cost and system stability. Therefore, a method of gradually shifting to the new system over time is taken.

  During this transition period, the analog radio communication system and the digital radio communication system will coexist. Therefore, in order to prevent interference between the two, users of the digital radio communication system should use it before their communication. It is necessary to confirm the presence or absence of communication of the analog wireless communication system in the channel.

  However, as described in the analog wireless terminal 100 and the digital wireless terminal 110, the BUSY detection method is different between the analog wireless communication system and the digital wireless communication system. That is, it is difficult for the conventional digital wireless terminal 110 to detect the BUSY of the channel in the analog wireless communication system using the method of detecting BUSY from the presence or absence of the frame synchronization code.

  The squelch control device of Patent Document 1 directly relates to opening / closing control of the squelch circuit, and the squelch control unit may be applicable to BUSY detection, but in this case, for each frequency division, a band pass filter, An amplifier and a rectifier are required (see the block indicated by reference numeral 19 in FIG. 1 of Patent Document 1), and the number of parts increases.

  An object of the present invention is to provide a wireless device, a control method, and a program that can accurately detect the presence or absence of use of radio waves of each channel without providing a squelch circuit.

The wireless device of the present invention includes the following means.
Determination means for determining whether RSSI (Receive Signal Strength Indication) at the frequency of the target communication channel is non-peak in a predetermined frequency range including the frequency of the target communication channel in the middle, and the determination means is non-peak If it is determined that the target communication channel is an empty channel, the empty channel detecting means is used.

The radio control method of the present invention includes the following steps.
Determining whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range including the frequency of the target communication channel in the middle; and the RSSI at the frequency of the target communication channel is the frequency of the target communication channel If the target communication channel is determined to be a non-peak in a predetermined frequency range including the middle, the target communication channel is set to an empty channel.

  The program of the present invention causes a computer to function as each unit of the wireless device of the present invention.

  According to the present invention, whether or not the target communication channel is an empty channel can be accurately detected based on whether or not the frequency of the target communication channel is non-peak in a predetermined frequency range including the frequency in the middle. .

  FIG. 1 is a block diagram of a digital wireless terminal 10. The reception signal input unit 11 receives a reception signal from an antenna (not shown). The received signal is not only a digital signal but also an analog signal. However, only when the received signal is a digital signal, the digital wireless terminal 10 can decode the signal in the DSP 39, which will be described later, and output the sound in the received signal. The reception signal of the reception signal input unit 11 is input to the mixer 15 through the band pass filter 12, the RF amplifier 13 and the band pass filter 14.

  In the mixer 15, the RF signal from the band pass filter 14 is mixed with the oscillation signal from the reception PLL 42 to generate an IF signal. The switch 20 includes an input terminal 21 to which the IF signal from the mixer 15 is input, and two output terminals 22 and 23. In a period for measuring whether each channel is an empty channel or BUSY, the input terminal 21 is connected to an output terminal 22 on a measurement MCF (Monolithic Crystal Filter) 26 side as a measurement wideband reception filter. When communicating with the counterpart wireless terminal, the input terminal 21 is connected to an output terminal 23 on the reception MCF 30 side as a normal communication reception filter.

  The measurement MCF 26 plays a role of accurately measuring RSSI of each frequency without attenuating the interference wave, and has a wider pass band than the reception MCF 30. The measurement IF amplifier 27 plays a role of preventing the FM detection IC 35 from being damaged by an unintended excessive reception signal during the RSSI measurement period, and has a smaller gain than the reception IF amplifier 31. The IF signal at the output terminal 22 is sent to the measurement IF amplifier 27 via the measurement MCF 26, amplified by the measurement IF amplifier 27, and then sent to the FM detection IC 35.

  The IF signal at the output terminal 23 is sent to the reception IF amplifier 31 via the reception MCF 30, amplified by the reception IF amplifier 31, and then sent to the FM detection IC 35.

  The FM detection IC 35 receives the oscillation signal 2nd having a predetermined frequency to generate a secondary IF signal, detects the secondary IF signal, and sends the detection signal to the DSP 39. The DSP 39 decodes the detection signal to generate a digital signal, and then generates an analog audio signal from the digital signal and outputs the analog audio signal to a speaker (not shown).

  The FM detection IC 35 outputs RSSI (Receive Signal Strength Indication) to the A / D converter 40. The A / D converter 40 A / D converts it and sends it to the CPU 41. The CPU 41 controls the switching position of the switch 20 and the oscillation frequency of the reception PLL 42, and obtains RSSI at each frequency from the input signal from the A / D converter 40.

  In the RSSI measurement period for finding an empty channel, the switch 20 connects the input terminal 21 to the output terminal 22. Then, the CPU 41 controls the control signal to the reception PLL 42 so that the RF signal converted into the IF signal in the mixer 15 has a frequency for measuring RSSI.

  2 and 3 are diagrams for explaining the principle of detecting an empty channel by the digital wireless terminal 10. In FIG. 2 and FIG. 3, it is examined whether or not a channel having a frequency of Fco (hereinafter referred to as “target communication channel”) is an empty channel. A low frequency side adjacent communication channel and a high frequency side adjacent communication channel that are adjacent to the target communication channel in the frequency axis direction on the low frequency side and the high frequency side are defined.

  Wc, Wl, and Wh are RSSIs of received signals of the target communication channel, the low frequency side adjacent communication channel, and the high frequency side adjacent communication channel, respectively. Fl and Fh are the frequencies of the low frequency side adjacent communication channel and the high frequency side adjacent communication channel. Fcl and Fch are frequencies separated from Fco by an appropriate amount on the negative side and the positive side in the frequency axis direction, respectively, and Fl <Fcl <and Fco <Fch <Fh. In the example of FIG. 2, the width ΔW of Wc at a predetermined RSSI level (RSSI level at the position of the vertical axis where the horizontal axis in FIG. 2 intersects) is 12.5 kHz, and ΔC = Fco−Fcl = Fch−Fco = 3 kHz. is there. For example, ΔC is approximately ½ of ΔW.

  When the RSSI in Fco is compared with the reference value and is equal to or higher than the reference value and less than the reference value, it cannot be mechanically determined that the target communication channel is BUSY and an empty channel, respectively. This is because RSSI varies with temperature.

  The principle of detecting an empty channel in the digital wireless terminal 10 will be described. FIG. 2 shows a frequency-RSSI level relationship when the target communication channel, the low-frequency adjacent communication channel, and the high-frequency adjacent communication channel are all BUSY. As can be seen from FIG. 2, when the target communication channel is BUSY, RSSI in Fco has a peak in a predetermined frequency range including the center, for example, the center (frequency range of Fco ± ΔC in FIG. 2).

  First, RSSI in Fco of the high frequency side adjacent communication channel is detected. The detected value is, for example, −50 dBm. Assuming that the target communication channel is BUSY, if the RSSI in Fco is found, the curve of Wc can be roughly estimated from the band curve defined by the law relating to wireless communication. The Wc estimation curve is included between the upper limit estimation curve Eu and the lower limit estimation curve El in consideration of errors.

  In the estimation curve of Wc, for example, if the FSI RSSI level is −50 dBm, the estimated RSSI level of Fcl and Fch is −60 dBm, down 10 dBm. Further, the estimated Eu and El on the upper limit side and the adjustable side are ± 10 dBm with respect to the central estimated RSSI, and the estimated Eu and El in Fcl and Fch are −50 dBm and −70 dBm with respect to −60 dBm.

  Next, RSSI of Fcl is detected, and it is determined whether or not the detected value is within the estimated Eu to El range. When Wl does not exist, the RSSI of Fcl is the RSSI of Wc in Fcl. However, when Wl is present, the RSSI of Fcl is the RSSI of Wc in Fcl + the RSSI of Wl in Fcl. The aforementioned Eu includes the estimated RSSI of Wl in Fcl.

  If the determination in Fcl is negative, the target communication channel is determined to be an empty channel. On the other hand, if the determination in Fcl is positive, the RSSI of Fch is detected and the same process as in Fcl is performed.

  If the determination in Fch is NO, the target communication channel is determined to be an empty channel. That is, if either RSSI of Fcl or Fch is outside the estimated Eu to El range, the target communication channel is determined to be an empty channel. On the contrary, if the determination in Fch is positive, that is, if both RSSI of Fcl and Fch are within the estimated Eu to El range, the target communication channel is determined to be BUSY. In addition, although RSSI in Fcl was measured before RSSI in Fch, the reverse may be sufficient.

  FIG. 3 shows the frequency-RSSI level relationship when the target communication channel is an empty channel. In FIG. 2, the target communication channel, the low frequency side adjacent communication channel, and the high frequency side adjacent communication channel are BUSY, an empty channel, and an empty channel, respectively. First, RSSI in Fco is detected. Next, RSSI in Fcl is detected. Since RSSI in Fco <RSSI in Fcl, even if RSSI in Fch is not detected, RSSI in Fco does not peak in the adjacent frequency range including it, that is, the target communication channel is an empty channel. Becomes clear.

  In the example of FIG. 3, a case where RSSI of Fch is detected before Fcl will be described. In that case, RSSI> Fch in Fco, and RSSI of Fco may be a peak. Therefore, next, RSSI is detected for Fcl. As a result, since RSSI in Fco <RSSI in Fcl, it is found that RSSI in Fco is not a peak, that is, the target communication channel is an empty channel.

  FIG. 4 is a block diagram of the radio device 50. The wireless device 50 includes a determination unit 51 and an empty channel detection unit 52. The determination unit 51 determines whether or not the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range including the frequency of the target communication channel in the middle. When the determination by the determination unit 51 is positive, the empty channel detection unit 52 sets the target communication channel as an empty channel.

  An example of the wireless device 50 is the digital wireless terminal 10 described above. The frequency of the target communication channel corresponds to Fco in FIGS. An example of a predetermined frequency range including the frequency of the target communication channel in the middle corresponds to Fco ± 1.5 kHz in FIG. The wireless device 50 is not limited to a wireless communication terminal, and may be a wireless relay device. The radio device 50 is, for example, a digital radio device that detects that the target communication channel is not used as an analog radio channel, but an analog radio device that detects that the target communication channel is not used as an analog radio channel. It may be a machine.

  Typically, in the radio device 50, in the period in which the RSSI of Fco, Fcl, and Fch is examined, the IF signal band-pass filter used for the period in which the audio in the received signal of the target communication channel is output and the IF signal The amplifier for amplifying the output of the band pass filter (hereinafter referred to as “first IF signal band pass filter” and “first amplifier”, respectively) is different from the IF signal band pass filter and the IF signal. Amplifiers that amplify the output of the band-pass filter (hereinafter referred to as “second IF signal band-pass filter” and “second amplifier”) amplifiers are used.

  An example of the first and second IF signal band-pass filters is the receiving MCF 30 and the measuring MCF 26, respectively. Examples of the first and second amplifiers are the reception IF amplifier 31 and the measurement IF amplifier 27, respectively. The pass band of the second IF signal band-pass filter is wider than that of the first IF signal band-pass filter. Further, the gain of the second amplifier is made smaller than that of the first amplifier.

  As described in FIG. 2, when the target communication channel is BUSY, a predetermined frequency range including the frequency Fco of the target communication channel in the middle (in the example of FIG. 2, ± 1.5 kHz centered on Fco. In the frequency range), the RSSI of Fco has a substantially peak. Therefore, if Fco is non-peak in the predetermined frequency range, it can be determined that the target communication channel is an empty channel.

  As described above, although the RSSI changes depending on the temperature, the radio device 50 does not detect whether the target communication channel is an empty channel by comparing the RSSI in Fco with the reference value, but instead of the target communication channel. Since the determination is based on whether or not the frequency is non-peak in a predetermined frequency range including the frequency, an empty channel can be accurately detected regardless of the temperature.

  FIG. 5 is a detailed block diagram of determination means 51a as a first embodiment of determination means 51. The determination unit 51 a preferably includes a reference RSSI detection unit 55, another RSSI detection unit 56, an estimated RSSI calculation unit 57, and a comparison unit 58.

  The reference RSSI detection means 55 detects the RSSI at the frequency of the target communication channel as the reference RSSI. The separate RSSI detecting means 56 detects the RSSI at another frequency as a frequency that is smaller and / or larger by a predetermined amount in the frequency axis direction than the frequency of the target communication channel.

  The estimated RSSI calculating means 57 calculates the estimated RSSI at another frequency estimated from the reference RSSI when it is assumed that the target communication channel is a non-free channel. The comparison unit 58 determines whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range based on the comparison between the other RSSI and the estimated RSSI.

  An example of another frequency is Fcl and Fch in FIG. Note that it may be necessary to determine whether or not there is a non-peak in a predetermined frequency range including the frequency of the target communication channel by comparing another RSSI and estimated RSSI in both Fcl and Fch. As shown in FIG. 3, there are cases where determination can be made only by comparing another RSSI and estimated RSSI in one of Fcl and Fch.

  An example of the estimated RSSI is Eu to El in FIG. 2 in Fcl and Fch. El needs to include only the error on the lower side of the curve of Wc, but Eu needs to appropriately consider Wl in Fcl or RSSi of Wh in Fch in addition to the error on the upper side of the curve of Wc.

  For example, if the detected other RSSI is outside the range of Eu to El, it is determined that the target communication channel is an empty channel, and if both Fcl and Fch are within the range of Eu to El, the target communication channel is BUSY. judge.

  2 and 3, each of Fcl and Fch is one. However, only a plurality of Fcl and Fch are adopted, and the target communication channel is only when another RSSI in all other frequencies is within the range of Eu to El. You may make it determine with BUSY.

  FIG. 6 is a block diagram of determination means 51b as a second embodiment of determination means 51. The determination unit 51b may include a reference RSSI detection unit 63, another RSSI detection unit 64, and a comparison unit 65.

  The reference RSSI detection means 63 detects the RSSI at the frequency of the target communication channel as the reference RSSI. The separate RSSI detecting means 64 detects the RSSI at another frequency as a frequency that is smaller and / or larger by a predetermined amount in the frequency axis direction than the frequency of the target communication channel.

  The comparing means 65 determines whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range based on the comparison between the reference RSSI and another RSSI.

  Examples of different frequencies in the determination unit 51b are Fcl and Fch, as in the case of the determination unit 51a. As can be seen from FIG. 3, by appropriately selecting Fcl or Fch, if the reference RSSI <another RSSI, it can be determined that the reference RSSI is non-peak in the predetermined frequency range. In both Fcl and Fch, the reference RSSI can be regarded as a peak in the predetermined frequency range only when the reference RSSI> different RSSI.

  FIG. 7 is a flowchart of the wireless device control method 75. The radio control method 75 includes S76 and S77.

  In S76, it is determined whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range including the frequency of the target communication channel in the middle. If the determination is positive (non-peak), the process proceeds to S77, and if not (substantially peak), the process proceeds to S78.

  In S77, it is determined that the target communication channel is an empty channel. In S78, it is determined that the target communication channel is being used (BUSY) by another wireless device.

  The specific determination method in S76 corresponds to FIG. 5 or FIG. That is, in the first determination method (method corresponding to FIG. 5), the RSSI at the frequency of the target communication channel is detected as the reference RSSI, and is smaller and / or larger by a predetermined amount in the frequency axis direction than the frequency of the target communication channel. An RSSI at another frequency as a certain frequency is detected as another RSSI. Furthermore, when it is assumed that the target communication channel is a non-free channel (BUSY), an estimated RSSI at another frequency estimated from the reference RSSI is calculated. And determining whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range based on a comparison between another RSSI and the estimated RSSI.

  In the second determination method (method corresponding to FIG. 6), the RSSI at the frequency of the target communication channel is detected as the reference RSSI, and the frequency is smaller and / or larger by a predetermined amount in the frequency axis direction than the frequency of the target communication channel. The RSSI at another frequency is detected as another RSSI. Then, it is determined based on the comparison between the reference RSSI and another RSSI whether the RSSI at the frequency of the target communication channel is a non-peak in a predetermined frequency range.

  The program to which the present invention is applied causes a computer to function as each unit of the radio device 50. Another program to which the present invention is applied causes a computer to execute each step of the radio control method 75.

  Although the present invention has been described with respect to the best mode, the present invention is not limited to this, and each constituent element in the best mode can be modified and embodied without departing from the spirit of the invention. In addition, a plurality of constituent elements disclosed in the best mode are conveniently combined and added, or some constituent elements are deleted to form various inventions without departing from the gist of the invention. can do. Furthermore, various inventions can be formed by selecting predetermined components among a plurality of disclosed embodiments and combining them.

It is a block diagram of a digital wireless terminal. It is a figure which shows the relationship of the frequency-RSSI level in case all of the target communication channel, the low frequency side adjacent communication channel, and the high frequency side adjacent communication channel are BUSY. It is a figure which shows the relationship of the frequency-RSSI level in case a target communication channel is an empty channel. It is a block diagram of a radio. It is a detailed block diagram of a 1st determination means. It is a block diagram of the 2nd determination means. It is a flowchart of the radio equipment control method. It is a block diagram of a conventional analog wireless terminal. It is a block diagram of a conventional digital wireless terminal.

Explanation of symbols

50: Radio, 51, 51a, 51b: Determination means, 52: Empty channel detection means, 55: Reference RSSI detection means, 56: Separate RSSI detection means, 57: Estimated RSSI calculation means, 58: Comparison means, 63: Reference RSSI detection means, 64: separate RSSI detection means, 65: comparison means, 75: radio equipment control method.

Claims (7)

Whether RSSI at the frequency of the target communication channel, which is a predetermined channel, is non-peak in a predetermined frequency range including a frequency larger and lower than the frequency of the target communication channel with the frequency of the target communication channel as the center. A determining means for determining, and an empty channel detecting means for determining that the target communication channel is an empty channel when the determining means determines that it is non-peak,
With
The determination means includes
Reference RSSI detection means for detecting RSSI at the frequency of the target communication channel as reference RSSI;
The RSSI at the first different frequency, which is a specific one frequency smaller by a predetermined amount than the frequency of the target communication channel , is detected as the first other RSSI, and the predetermined amount predetermined from the frequency of the target communication channel Another RSSI detecting means for detecting the RSSI at the second different frequency which is a specific one frequency which is only as large as the second different RSSI;
Assuming that the target communication channel is a non-free channel, an upper limit estimation curve in which the RSSI is increased by a predetermined amount from the frequency-RSSI characteristic curve estimated according to the detected reference RSSI ; The estimated RSSI range at the first different frequency is calculated as the first estimated RSSI range from the lower limit estimated curve obtained by lowering the RSSI by a predetermined amount from the characteristic curve , and at the second different frequency. An estimated RSSI calculating means for calculating an estimated RSSI range as a second estimated RSSI range ;
Whether RSSI at the frequency of the target communication channel is non-peaks in the predetermined frequency range, whether the first alternative RSSI is within the range of the first guess RSSI, and the second Contrast means for determining whether two other RSSIs are within the range of the second estimated RSSI ;
A wireless device comprising: The estimated RSSI calculating means calculates the upper limit estimation curve and the lower limit estimation curve by taking into account an upper error portion and a lower error portion including correction amounts corresponding to vacancy and non-vacancy of adjacent communication channels, respectively. The wireless device according to claim 1. The separate RSSI detection means is configured such that when the first separate RSSI is not within the range of the first estimated RSSI , or when the second separate RSSI is not within the range of the second estimated RSSI, The radio device according to claim 1 or 2, wherein the RSSI at the frequency of the target communication channel is determined to be non-peak in the predetermined frequency range. The wireless device according to claim 1 or 2 , wherein the wireless device is a digital wireless device that detects that a target communication channel is not used as an analog wireless channel. The IF signal band-pass filter and the amplifier for amplifying the output of the IF signal band-pass filter used during the period of outputting the audio in the received signal of the target communication channel are respectively the first IF signal band-pass filter and the first IF signal band-pass filter. If the amplifier is 1,
In a period for investigating whether or not the target communication channel is an empty channel, a second IF signal bandpass filter and a second IF signal bandpass filter different from the first amplifier and the first amplifier are used. Use the amplifier of
The passband of the second IF signal bandpass filter is wider than that of the first IF signal bandpass filter,
5. The radio apparatus according to claim 4, wherein a gain of the second amplifier is smaller than that of the first amplifier. Whether RSSI at the frequency of the target communication channel, which is a predetermined channel, is non-peak in a predetermined frequency range including a frequency larger and lower than the frequency of the target communication channel with the frequency of the target communication channel as the center. A determination step for determining, and when determining that the target communication channel is a non-peak in the determination step, an empty channel detection step in which the target communication channel is an empty channel;
With
The determination step includes
A reference RSSI detection step of detecting an RSSI at a frequency of the target communication channel as a reference RSSI;
The RSSI at the first different frequency, which is a specific one frequency smaller by a predetermined amount than the frequency of the target communication channel , is detected as the first other RSSI, and the predetermined amount predetermined from the frequency of the target communication channel Another RSSI detection step of detecting RSSI at the second different frequency which is a specific one frequency which is only as large as the second different RSSI;
Assuming that the target communication channel is a non-free channel, an upper limit estimation curve in which the RSSI is increased by a predetermined amount from the frequency-RSSI characteristic curve estimated according to the detected reference RSSI ; The estimated RSSI range at the first different frequency is calculated as the first estimated RSSI range from the lower limit estimated curve obtained by lowering the RSSI by a predetermined amount from the characteristic curve , and at the second different frequency. An estimated RSSI calculating step for calculating the estimated RSSI range as the second estimated RSSI range ;
Whether RSSI at the frequency of the target communication channel is non-peaks in the predetermined frequency range, whether the first alternative RSSI is within the range of the first guess RSSI, and the second A comparison step for determining whether two other RSSIs are within the range of the second estimated RSSI ;
A radio control method comprising: The program for functioning a computer as each means of the radio | wireless machine in any one of Claims 1-5 .

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