JP2004180230A - Radio communication apparatus using frequency hopping system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption at standby in a radio communication apparatus using a frequency hopping system, and to provide a detecting apparatus for a hopping field available to achieve this purpose. <P>SOLUTION: A hopping field detecting part 330 is incorporated into the radio communication apparatus combining a function as a mobile phone 310 and that as a Bluetooth(R) instrument 320. The hopping field detecting part 330 has a function for detecting whether a hopping field, whose frequency shifts with a frequency hopping period T based on a communication standard of Bluetooth, exists in a surrounding area. Although the mobile phone 310 is set at a regular standby mode, an oscillation circuit required for standby operation of the Bluetooth instrument 320 is set at a resting state until a detection signal from the hopping field detecting part 330 is given. The Bluetooth instrument 320 shifts to a regular standby mode only after the detection signal is given. By setting the oscillation circuit at the resting state as above, power consumption is reduced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication device using a frequency hopping method, and more particularly to a technique for detecting the presence of a hopping field in a communication standard such as Bluetooth or a wireless communication device such as a wireless LAN.
[0002]
[Prior art]
The wireless communication system is widely used mainly as a communication system for mobile objects because physical wiring for individual terminal devices is not required. In recent years, wireless LANs have started to spread in place of wired LANs for connecting personal computers, and a Bluetooth communication standard has been proposed as a wireless communication standard not only for personal computers but also for mobile phones and home appliances. It has been gradually spreading.
[0003]
As one form of such a wireless communication system, a frequency hopping method is often used. In the frequency hopping method, a plurality of communication frequencies are determined in advance, and communication is performed while switching the communication frequencies in a predetermined cycle in a predetermined order. In the case of a wireless communication system intended for a mobile object, between the base station and the mobile station, in advance, what kind of hopping cycle, according to what kind of hopping pattern, it is determined how to switch the frequency, and according to the agreement Communication is performed while switching the communication frequency between the two as needed. The Bluetooth communication standard also presupposes such frequency hopping communication. The technology of the frequency hopping method itself is already known, and for example, the following Non-Patent Document 1 describes the basic concept of communication by the frequency hopping method.
[0004]
A first advantage of the frequency hopping method is that security of communication contents can be achieved. Even if an attempt is made to intercept the communication illegally, it becomes difficult to follow the frequency switching unless the hopping pattern is known, so that such illegal interception can be suppressed. A second advantage is that mutual interference can be reduced when a plurality of communications are performed. In the case of a mobile communication system, it is often the case that a plurality of mobiles simultaneously communicate in the same area, but the effect of mutual interference can be reduced by switching the communication frequency as needed.
[Non-patent literature]
Mitsuo Yokoyama, "Spread Spectrum Communication System" Science and Technology Publishing
[0005]
[Problems to be solved by the invention]
In general, a communication terminal device needs to be in a standby state so that it can immediately respond to a call from another terminal device even when communication is not currently being performed. For example, a general mobile phone monitors the presence of a call signal so as to be able to respond immediately when an incoming call is received, and maintains a standby state in which it can be received at any time. This is the same for a communication device used in a wireless communication system using the frequency hopping method. However, when communication is performed at a fixed frequency such as a general mobile phone, it is only necessary to monitor a call signal at the fixed communication frequency. However, in a wireless communication system using a frequency hopping method, a standby mode is used. In this state, since it is necessary to monitor signals in a number of frequency bands that may cause hopping, a standby operation using a special circuit that consumes a large amount of power must be performed.
[0006]
As described above, the conventional wireless communication device using the frequency hopping method has a problem that power consumption during standby is large. In the future, when a wireless communication function based on a communication standard such as Bluetooth is added to a mobile phone, a small household electric appliance, or the like, this will be a factor to accelerate the consumption of the battery, and is an issue to be solved immediately.
[0007]
Accordingly, an object of the present invention is to reduce power consumption during standby in a wireless communication device using a frequency hopping method. It is another object of the present invention to provide a hopping field detection device that can be used to achieve such an object.
[0008]
[Means for Solving the Problems]
(1) A first aspect of the present invention is a wireless communication apparatus using a frequency hopping method of performing communication while switching a plurality of communication frequencies in a predetermined cycle in a predetermined order,
An oscillation circuit capable of oscillating at an arbitrary frequency selected from the plurality of frequencies described above, and using an AC signal generated by the oscillation circuit, wireless communication using a frequency hopping method or frequency hopping for preparation thereof Communication unit,
A hopping field detector that detects the presence of a specific electromagnetic hopping field in the surroundings,
And the oscillating circuit in the frequency hopping communication unit operates only when the hopping field detection unit detects the presence of a specific electromagnetic hopping field.
[0009]
(2) A second aspect of the present invention provides a wireless communication apparatus using the frequency hopping scheme according to the first aspect,
A portion for receiving a signal indicating a change in the surrounding electromagnetic field in the hopping field detection section and a portion for receiving a signal in the frequency hopping communication section are shared.
[0010]
(3) A third aspect of the present invention provides a wireless communication device using a frequency hopping method,
A first wireless communication unit having a function of performing communication by the first wireless communication method, a second wireless communication unit having a function of performing communication by the second wireless communication method, and a specific electromagnetic device in the surroundings. A hopping field detection unit that detects the presence of a hopping field,
At least the second wireless communication unit is selected from the plurality of frequencies in order to perform wireless communication using a frequency hopping method of performing communication while switching a plurality of communication frequencies in a predetermined cycle in a predetermined order. An oscillating circuit that can oscillate at an arbitrary frequency, has a function of performing radio communication using a frequency hopping method or preparing for the same using an AC signal generated by the oscillating circuit, and a hopping field detection unit Is configured such that the oscillation circuit operates only when the presence of a specific electromagnetic hopping field is detected.
[0011]
(4) A fourth aspect of the present invention provides a wireless communication apparatus using the frequency hopping scheme according to the third aspect described above,
The portion for receiving the signal indicating the fluctuation of the surrounding electromagnetic field in the hopping field detecting portion and the portion for receiving the signal in the first or second wireless communication portion are shared.
[0012]
(5) A fifth aspect of the present invention provides a wireless communication apparatus using the frequency hopping scheme according to the first to fourth aspects,
A signal receiving unit that receives a signal indicating a change in a surrounding electromagnetic field in a hopping frequency band, a frequency / amplitude conversion circuit that converts a frequency component of the received signal into an amplitude component, and an envelope that detects an envelope of the converted signal A hopping field detection unit is configured by a line detection circuit and a time series pattern determination circuit that determines whether a time series pattern included in the detected envelope matches the frequency hopping pattern, and the time series pattern determination circuit When a coincidence determination is made, a detection signal indicating that the presence of an electromagnetic hopping field has been detected is output.
[0013]
(6) According to a sixth aspect of the present invention, in a wireless communication apparatus using the frequency hopping scheme according to the fifth aspect,
The frequency / amplitude conversion circuit is configured using a single tuning circuit or a phase change circuit.
[0014]
(7) A seventh aspect of the present invention provides a wireless communication apparatus using the frequency hopping scheme according to the fifth or sixth aspect,
A sampling circuit that samples a signal having a gain corresponding to the envelope detected by the envelope detection circuit at a predetermined sample period, and outputs the sampled signal as a sequence of sample values according to the gain; and a period of a synchronization signal synchronized with the sample period. Counter, a sample value storage circuit for storing the sample value output from the sampling circuit for a predetermined period, and a sample value output from the sampling circuit for a predetermined sample period stored in the sample value storage circuit. A comparator that compares the sample value and resets the counter when they do not match, and determines whether the time-series pattern included in the envelope matches the frequency hopping pattern based on the count value immediately before the counter is reset. And a count value determining unit for determining whether the time-series pattern determining circuit is configured. It is intended.
[0015]
(8) An eighth aspect of the present invention provides a wireless communication apparatus using the frequency hopping scheme according to the seventh aspect,
The count value judging unit judges the pattern match by recognizing whether or not the time corresponding to the count value immediately before the reset matches the frequency switching cycle in the frequency hopping method.
[0016]
(9) A ninth aspect of the present invention provides a hopping field detection unit using a hopping field detection unit described as one component of the wireless communication apparatus using the frequency hopping scheme according to the first to eighth aspects. This is to constitute a detection device.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on an illustrated embodiment.
[0018]
<<<< §1. Basic principle of frequency hopping method >>>>>
Here, for convenience of description of the present invention, the basic principle of a general frequency hopping scheme will be briefly described. FIG. 1 is a diagram showing the basic principle of a general frequency hopping method, in which the horizontal axis represents frequency f and the vertical axis represents time t. The frequency hopping system is a wireless communication system that performs communication while switching a plurality of communication frequencies in a predetermined cycle in a predetermined order. In the illustrated example, five communication frequencies f0 to f4 are defined. . Each of these five communication frequencies has a predetermined frequency band. In the figure, the five communication frequencies f0 to f4 are shown as regions having a certain spread in the horizontal axis (frequency f axis) direction. It is.
[0019]
Here, the times t0 to t4 on the time axis t are arranged at intervals of the same cycle T, and after t4, return to t0 and circulate. The communication frequency f0 is used during the period from time t0 to t1, the communication frequency f1 is used during the period from time t1 to t2, the communication frequency f2 is used during the period from time t2 to t3, and the communication frequency f2 is used during the period from time t3 to t4. It is shown that the communication frequency of f3 is used for the period, and the communication frequency of f4 is used for the period from time t4 to t0. Eventually, in this example, the communication frequency hops in a pattern of f0 → f1 → f2 → f3 → f4 → f0 → f1 →...
[0020]
FIG. 2 is a block diagram illustrating an example of a basic configuration of the communication unit 100 that performs communication using such a frequency hopping method. As shown, the communication unit 100 includes an antenna 110, a down converter 120 and an up converter 130 connected to the antenna 110, an oscillation circuit 140, signal multipliers 150 and 160, a detection circuit 170, a communication control And a circuit 180.
[0021]
The RF signal received by the antenna 110 (for example, a signal in the 2.4 GHz band in the case of the Bluetooth communication standard) is received by the down converter 120 in a lower frequency band reception signal (frequency f0 to f4 shown in FIG. 1). Is converted to a signal including a band. The signal multiplier 150 multiplies the received signal by an AC signal of a predetermined frequency (any frequency selected from the frequencies f0 to f4 shown in FIG. 1) generated by the oscillation circuit 140, and multiplies the multiplication result by Is supplied to the detection circuit 170. The detection circuit 170 performs a detection process for extracting the baseband reception signal included in the given signal, and supplies the signal to the communication control circuit 180. When the hopping frequency of the received signal output from the down converter 120 matches the frequency generated by the oscillation circuit 140, only the information in the frequency band is selectively enhanced by multiplication by the signal multiplier 150, and It will be detected.
[0022]
The communication control circuit 180 is a component that controls the entire communication unit 100, performs necessary processing on the baseband reception signal extracted by the detection circuit 170, and converts data to be transmitted to the baseband transmission signal. And a process of instructing the oscillation circuit 140 on the oscillation frequency f. In the signal multiplier 160, a process of multiplying the AC signal of a predetermined frequency generated by the oscillation circuit 140 by a baseband transmission signal is performed, and a signal resulting from the multiplication is converted into an RF signal by the up-converter 130. , From the antenna 110.
[0023]
Here, it is assumed that the frequency hopping communication unit 100 shown in FIG. 2 is incorporated in a wireless communication device functioning as a mobile station, and that the mobile station receives a call from a base station and communicates with the base station. The operation will be briefly described. The wireless communication device functioning as a mobile station needs to maintain a standby state so as to be able to immediately respond to a call from the base station, but since communication from the base station is performed by a frequency hopping method, Attempts are made to tune the frequency.
[0024]
FIG. 3 is a time diagram for explaining a general operation in a standby state between a base station and a mobile station adopting the frequency hopping scheme. In this example, the base station performs an operation of obtaining a response from a nearby mobile station while switching the communication frequency in the order of f0 → f1 → f2 → at intervals of the cycle T1. In other words, the base station transmits radio waves that are frequency-hopped at intervals of the period T1. On the other hand, the mobile station performs an operation of receiving radio waves from surrounding base stations while also switching the communication frequency in the order of f0 → f1 → f2 → at the interval of the cycle T2. Specifically, in the block diagram shown in FIG. 2, a predetermined communication frequency is instructed from communication control circuit 180 to oscillation circuit 140 at intervals of cycle T2.
[0025]
As described above, if one of the frequency hopping period T1 of the transmission signal from the base station and the frequency hopping period T2 for reception at the mobile station is set to be sufficiently longer than the other, any one of Thus, the two frequencies are tuned. At this tuned timing, by using the tuned communication frequency, a call operation from the base station and a response operation from the mobile station can be performed. For example, in the case of the example of FIG. 3, there is one timing at which the base station transmits at the same frequency f0 within the period T2 in which the mobile station is waiting at the frequency f0, and similarly, the mobile station waits at the frequency f1. In the period of the next cycle, there is one timing at which the base station transmits at the same frequency f1. At these timings, the transmission and reception frequencies of both base stations tune, and the calling and response of The operation can be performed.
[0026]
Eventually, in the communication unit 100 shown in FIG. 2, when in the standby state, the communication control circuit 180 instructs the oscillation circuit 140 to perform f0 → f1 → f2 → at intervals of the cycle T2 shown in the lower part of FIG. The frequency is specified in order. Despite the operation in the standby state, if there is no base station in the vicinity, the detection circuit 170 does not detect a significant received signal. However, if a base station exists in the vicinity and a signal for paging is transmitted while performing a frequency hopping method at an interval of a period T1 shown in the upper part of FIG. 3, the mobile station performs the paging at the timing described above. Can be recognized, and a response can be made by returning a signal via the up-converter 130.
[0027]
The above is the procedure of the preparation stage performed before performing wireless communication using the frequency hopping method between the base station and the mobile station. As described above, when a response from a predetermined mobile station is obtained in response to a call from the base station, wireless communication using a normal frequency hopping method is performed between the two. Since the two have already been synchronized at the above-mentioned timing, they reset the new frequency hopping cycle to an integral multiple of T1 (twice in the case of Bluetooth) and start wireless communication. That is, the communication control circuit 180 gives an instruction to the oscillation circuit 140 to perform frequency hopping every new set cycle. In this way, both the base station and the mobile station communicate with each other while switching the communication frequency at the same cycle based on the same hopping pattern. Since the hopping frequency of the reception signal output from the down converter 120 always coincides with the frequency generated by the oscillation circuit 140, the detection circuit 170 can always detect the baseband reception signal, and , The baseband transmission signal can always be transmitted via the upconverter 130.
[0028]
<<<< §2. Basic principle of the present invention >>>>>
As already described in §1, in a wireless communication device using the frequency hopping method, a standby state is set so that even if communication is not performed at the present time, a call from another terminal device can be immediately answered. Must be kept. Moreover, in this standby state, it is necessary to monitor signals in a number of frequency bands (hopping frequency bands) that may cause hopping, and as shown in the example of the frequency hopping communication unit 100 in FIG. It is necessary to operate the oscillation circuit 140 to perform detection. The oscillation circuit 140 used for such an application is a circuit (PLL circuit) called a so-called frequency synthesizer, and is a circuit that consumes relatively large power. Therefore, as described above, the wireless communication device using the conventional frequency hopping method has a problem that the power consumption during standby is large.
[0029]
The purpose of the present invention is to reduce the power consumption during such a standby, for that purpose, in the present invention, adding a hopping field detection unit that detects the presence of a specific electromagnetic hopping field in the surroundings, Only when the hopping field detection unit detects the presence of a specific electromagnetic hopping field, a method of operating an oscillation circuit with large power consumption is adopted.
[0030]
FIG. 4 is a block diagram showing a basic configuration of a wireless communication device using the frequency hopping scheme according to the present invention. As shown in the figure, this device includes a frequency hopping communication unit 100 and a hopping field detection unit 200. As shown in FIG. 2, the frequency hopping communication unit 100 is a wireless communication unit incorporated in a wireless communication device using a conventional general frequency hopping method, and includes a plurality of frequency hopping target frequencies. Having an oscillating circuit 140 capable of oscillating at an arbitrary frequency selected from among the following, and performing a function of performing wireless communication using a frequency hopping method or a preparation thereof using an AC signal generated by the oscillating circuit 140 It is. On the other hand, the hopping field detection unit 200 is a component specific to the present invention, and detects a specific electromagnetic hopping field (a fluctuation field of a frequency corresponding to a frequency hopping scheme used by the wireless communication device) in the surroundings. Has the ability to detect presence.
[0031]
Here, when the hopping field detection unit 200 detects a corresponding specific electromagnetic hopping field, a detection signal is given from the hopping field detection unit 200 to the frequency hopping communication unit 100. The frequency hopping communication unit 100 is configured to execute its original operation only when the detection signal is given. For example, if the power supply for operating the frequency hopping communication unit 100 is performed only when the detection signal is supplied from the hopping field detection unit 200, in a state where the detection signal is not supplied, It is sufficient that the frequency hopping communication unit 100 is supplied with only reserve power for operating a monitor circuit for recognizing a detection signal when it is provided. In an actual circuit, as described above, the power consumption of the oscillation circuit 140 functioning as a frequency synthesizer is extremely large. Therefore, in practice, at least the oscillation circuit 140 may be configured to operate only when a detection signal from the hopping field detection unit 200 is given. Then, in the wireless communication device shown in FIG. 4, in the standby state, at least the oscillation circuit 140 in the frequency hopping communication unit 100 is in the sleep state, so that the power consumption in the standby state can be significantly reduced. it can.
[0032]
For example, when the wireless communication device shown in FIG. 4 is used as the Bluetooth communication device of the mobile station, when no base station exists around the mobile station, at least the oscillation circuit 140 in the frequency hopping communication unit 100 is in the idle state. And power consumption can be reduced. In addition, even in this state, the hopping field detection unit 200 is functioning, so if the mobile station moves and enters a communicable area of a specific base station, hopping is performed within the area. The presence of the field is detected, and a detection signal is given to the frequency hopping communication unit 100. At this point, the oscillation circuit 140 in the frequency hopping communication unit 100 starts operating, and the frequency hopping communication unit 100 shifts to the normal operation state, so that this mobile station can communicate with the specific base station without any trouble. It can be performed. In other words, even if the oscillation circuit 140 is in the halt state and the frequency hopping communication unit 100 is not operating normally, the hopping field detection unit 200 detects the surrounding hopping field (that is, the presence detection of the surrounding base station). ) Is always performed, so that a standby state similar to that of the conventional wireless communication device can be realized.
[0033]
<<<< §3. Specific configuration example of hopping field detector >>>
FIG. 5 is a block diagram showing a specific configuration example of the hopping field detection unit 200 shown in FIG. In this configuration example, the hopping field detection unit 200 includes an antenna 210, a down converter 220, a frequency / amplitude conversion circuit 230, an envelope detection circuit 240, and a time-series pattern determination circuit 250. The hopping field detection unit 200 can be regarded as a device that recognizes the transition phenomenon of the communication frequency itself due to hopping as a kind of FM signal and detects the hopping field from a change in the frequency pattern. Therefore, the antenna 210, the down converter 220, the frequency / amplitude conversion circuit 230, and the envelope detection circuit 240 in the hopping field detection unit 200 shown in FIG. 5 are realized by diverting those used in a general FM reception circuit. It is possible to do.
[0034]
First, the antenna 210 and the downconverter 220 are the same components as the antenna 110 and the downconverter 120 in the frequency hopping communication unit 100 shown in FIG. 2, and receive a signal indicating the fluctuation of the surrounding electromagnetic field in the hopping frequency band. Functions as a signal receiving unit. As described above, the frequency component of the RF signal is removed by the down converter 220, and a signal including a hopping frequency band (for example, a frequency band from f0 to f4 in the example shown in FIG. 3) is used as a reception signal. Will be obtained. Note that a filter circuit may be used instead of the down converter 220.
[0035]
The frequency / amplitude conversion circuit 230 is a circuit that performs a process of converting a frequency component of a signal received by the signal receiving unit (the antenna 210 and the down converter 220) into an amplitude component. As the frequency / amplitude conversion circuit 230, any circuit may be used as long as an output signal having an amplitude corresponding to the frequency of the input signal can be obtained. The frequency / amplitude conversion circuit 230 can be configured by a single tuning circuit. FIG. 6 is a graph showing operating characteristics of the single tuning circuit. The horizontal axis indicates the frequency f of the input signal, and the vertical axis indicates the amplitude of the output signal. Fmin on the frequency axis indicates the minimum value of the hopping target frequency, and fmax indicates the maximum value of the hopping target frequency. A on the amplitude axis indicates the maximum amplitude. As shown, in this single tuning circuit, when a signal having a hopping maximum frequency fmax is provided, an output signal having an amplitude of 0 is obtained, and when a signal having a hopping minimum frequency fmin is provided, When an output signal having a maximum amplitude A is obtained and a signal having an arbitrary intermediate frequency fi is given, an output signal having an intermediate amplitude Ai is obtained.
[0036]
On the other hand, FIG. 7 is a block diagram illustrating an example in which the frequency / amplitude conversion circuit 230 is configured using a phase change circuit. The phase change circuit 231 is a circuit having operation characteristics as shown in FIG. 8, and is a circuit for obtaining an output signal having a phase corresponding to the frequency of the input signal. The horizontal axis of FIG. 8 indicates the frequency f of the input signal as in FIG. 6, and the vertical axis indicates the phase of the output signal. In the phase change circuit 231, when a signal having the maximum hopping frequency fmax is provided, an output signal of phase 0 is obtained. When a signal having the minimum hopping frequency fmin is provided, the phase π is output. Is obtained, and when a signal having an arbitrary intermediate frequency fi is given, an output signal having an intermediate phase φi is obtained. As shown in FIG. 7, as a result of multiplying the original signal and the signal after the phase change by the signal multiplier 232, an output signal having an amplitude corresponding to the frequency of the input signal is obtained. .
[0037]
The envelope detection circuit 240 is a circuit that detects an envelope of the signal output from the frequency / amplitude conversion circuit 230. As described above, since the amplitude of the signal output from the frequency / amplitude conversion circuit 230 depends on the frequency of the original received signal, the envelope detected by the envelope detection circuit 240 is Of the received signal. Since a general envelope detection circuit can be realized by a known circuit such as a filter circuit, the detailed description is omitted here.
[0038]
Next, what kind of signal the envelope signal output from the envelope detection circuit 240 looks like will be specifically considered. Now, assume that a hopping field having a pattern as shown in FIG. 1 exists in a certain area. In this hopping field, the frequency of the transmission signal transits in each cycle T in the order of f0 → f1 → f2 → f3 → f4. Such a signal is actually up-converted to a 2.4 GHz RF signal band and transmitted in the Bluetooth communication standard, for example, but the hopping field detection unit 200 shown in FIG. The signal is down-converted by the converter 220 and supplied to the frequency / amplitude conversion circuit 230. The transition information f0 → f1 → f2 → f3 → f4 of the frequency included in the transmission signal is converted into amplitude information by the frequency / amplitude conversion circuit 230, so that the envelope signal output from the envelope detection circuit 240 Is a signal having a voltage value as shown in the graph of FIG. 9, for example.
[0039]
The characteristics of the hopping pattern shown in FIG. 1 clearly appear in the graph of FIG. That is, the times t0 to t4, which are the timings at which the voltage value of the envelope E changes as shown in FIG. 9, correspond to the timings t0 to t4 of the frequency hopping shown in FIG. The voltage values V0 to V3 of the envelope E shown in FIG. 9 correspond to the frequencies f0 to f3 shown in FIG. In the case of the embodiment shown here, as shown in the graph of FIG. 6, in the frequency / amplitude conversion circuit 230, conversion is performed such that the higher the frequency is, the smaller the amplitude is. Therefore, in the graph of FIG. The smaller the voltage value of E, the higher the frequency of the original signal.
[0040]
As shown in FIG. 5, the envelope signal thus obtained is provided to the time-series pattern determination circuit 250. The time-series pattern determination circuit 250 predicts that a time-series pattern (a pattern as shown in the graph of FIG. 9) included in the detected envelope E is transmitted from a predetermined frequency hopping pattern (a base station). This is a circuit having a function of determining whether or not the frequency hopping pattern matches the frequency hopping pattern (for example, the pattern as shown in FIG. 1). A detection signal indicating that the detection has been performed is output.
[0041]
The first method for determining whether a time-series pattern included in the envelope E detected by the envelope detection circuit 240 matches or does not match a predetermined frequency hopping pattern is based on the frequency expected to be transmitted from the base station. Is sequentially compared with the transition pattern of the voltage value included in the envelope E. For example, when a frequency transition pattern as shown in FIG. 1 is transmitted from the base station, the frequency should adopt a transition pattern of f0 → f1 → f2 → f3 → f4, so that V0 → V1 → V2 → V3 If the transition pattern of the voltage values in the order of V4 is included in the envelope E, the coincidence determination can be performed. In this case, a change pattern of voltage values in the order of V0 → V1 → V2 → V3 → V4 may be stored in advance in the time-series pattern determination circuit 250 as data, and comparison may be sequentially performed.
[0042]
The second determination method of the match / mismatch is a method of confirming the match of the transition period T1. That is, in the example shown in FIG. 1, since it is known that frequency hopping occurs at every cycle T, this cycle T is stored in advance in the time-series pattern determination circuit 250, and the voltage value changes at this cycle T. When the envelope E is obtained, a match can be determined.
[0043]
In practice, it is sufficient to employ the above-described second determination method. For example, in the Bluetooth communication standard, the frequency hopping cycle when calling a mobile station from a base station is defined as 317.5 μsec, and the frequency hopping cycle during communication is defined as 625 μsec, so as shown in the graph of FIG. When the envelope E is obtained and the transition period T of the voltage value is 317.5 μsec or 625 μsec, it is determined that the hopping field according to the Bluetooth communication standard has been detected.
[0044]
FIG. 10 is a block diagram illustrating a configuration example of the time-series pattern determination circuit 250 when performing the above-described second determination method. In this example, the time-series pattern determination circuit 250 includes elements including a sampling circuit 251, a sample value storage circuit 252, a comparator 253, a counter 254, and a count value determination unit 255.
[0045]
The sampling circuit 251 is a circuit that samples a signal having a gain corresponding to the envelope E detected by the envelope detection circuit 240 at a predetermined sample period, and outputs the sampled signal as a sequence of sample values according to the gain. In the illustrated example, sampling is performed at a timing synchronized with a predetermined synchronization signal (clock signal), and the sample value is output as digital data. For example, when a signal having a gain corresponding to the envelope E shown in FIG. 9 is sampled at a predetermined sampling period, sample values S1, S2, S3, S4,... Shown in FIG. Will be. In the illustrated example, the sample values S1, S2, and S3 are digital values corresponding to the voltage V0, the sample values S4, S5, and S6 are digital values corresponding to the voltage V1, and so on. If the signal output from the envelope detection circuit 240 is an analog signal, the A / D converter can be used as it is as the sampling circuit 251.
[0046]
The sample value storage circuit 252 has a function of storing the sample value output from the sampling circuit 251 for a predetermined period. In this embodiment, the sample value storage circuit 252 stores the sample value output by the sampling circuit 251 for one sample period. Has a function. For example, when the sample value S1 is output from the sampling circuit 251, the sample value storage circuit 252 fetches the sample value and temporarily stores the sample value. However, when the sample value S2 is output in the next sample period, The operation of outputting the stored sample value S1 to the comparator 253, retrieving a new sample value S2 and temporarily storing the same is repeated.
[0047]
The comparator 253 compares the sample value output from the sampling circuit 251 with the sample value one sample cycle earlier stored in the sample value storage circuit 252, and resets the counter 254 when they do not match. have. In the case of the above example, when the sample value S2 is output from the sampling circuit 251, a process of comparing the sample value S2 with the sample value S1 one sample cycle earlier stored in the sample value storage circuit 252 is performed. Is reset, the reset signal is output.
[0048]
For example, in the case of the example shown in FIG. 11, first, the sample value S2 is compared with the immediately preceding S1, but since both match, the reset signal is output from the comparator 253. Absent. Subsequently, the comparison between the sample value S3 and the immediately preceding S2 is performed. However, since they both match, the reset signal is not output from the comparator 253. However, next, when the sample value S4 is compared with the immediately preceding sample value S3, they do not match, so that the comparator 253 outputs a reset signal. Thus, in the case of the example shown in FIG. 11, the reset signal is output from the comparator 253 in the cycle of the sample values S1, S4, S7 and S10. The cycle at which this reset signal is output is the cycle T at which the voltage value of the envelope E shown in FIG. 9 changes.
[0049]
The counter 254 has a function of counting the period of the synchronization signal provided to the sampling circuit 251, and the count value is reset by a reset signal output from the comparator 253. Eventually, the counter 254 performs the function of counting the sample period until a reset signal is given, and the obtained count value is a value indicating the period T shown in FIG.
[0050]
The count determination unit 255 determines whether the time-series pattern included in the envelope E matches the frequency hopping pattern based on the count thus obtained (the count immediately before the counter 254 is reset). It has a function to do. As described above, the count value immediately before the reset of the counter 254 is a value indicating the period T related to the envelope E shown in FIG. 9, which coincides with the frequency switching period in the frequency hopping method (the period T in FIG. 1). Can be recognized, pattern matching can be determined. Therefore, data corresponding to the cycle T in FIG. 1 is stored in advance in the count value determination unit 255, and it is determined whether or not the count value obtained from the counter 254 matches this value. Is obtained, a detection signal may be output. This detection signal is a signal indicating the detection of the hopping field by the frequency hopping method shown in FIG.
[0051]
In the above-described embodiment, only one sample value one sample cycle earlier is stored in the sample value storage circuit 252, and the comparator 253 compares one sample value with the immediately preceding sample value. However, the comparison of the sample values does not necessarily have to be performed on a one-to-one basis, and a plurality of samples may be compared at the same time. For example, the sample values up to n sample periods before are stored in the sample value storage circuit 252, and the comparator 253 stores the sample values output from the sampling circuit 251 and the sample values stored in the sample value storage circuit 252. It is also possible to compare the respective n sample values with each other and output a reset signal when they do not match with a probability equal to or higher than a predetermined threshold value.
[0052]
Further, the coincidence determination in the count value determination unit 255 can be performed more strictly. That is, even if the count value obtained from the counter 254 coincides with the previously stored predetermined period T only once, the detection signal is not output yet, and the count value indicating the period T continues for the predetermined number of times. If the detection signal is output from the counter 254 for the first time, if the target hopping field does not originally exist, the period E coincidentally matches the period T even though the target hopping field does not exist. This can prevent a phenomenon in which a detection signal is erroneously output when a voltage fluctuation occurs.
[0053]
As described above, the use of the hopping field detection unit 200 having the configuration shown in FIG. 5 effectively detects the electromagnetic hopping field in an environment where wireless communication using a predetermined frequency hopping method is performed. It becomes possible. Although pulse noise generated in a short time is often mixed in an electromagnetic field in a real environment, such pulse noise is not generated continuously, and is excluded in the detection method according to the present invention. No problem occurs. Further, even if noise that constantly stays in a certain frequency band is mixed, such noise does not change its frequency pattern, so that the noise is eliminated in the detection method according to the present invention, and no problem occurs. Even in an environment in which random noise is generated, such random noise does not have a periodic frequency transition component, and is similarly excluded by the detection method according to the present invention.
[0054]
When the wireless communication device shown in FIG. 4 is configured, in practice, a portion that receives a signal indicating a change in the surrounding electromagnetic field in the hopping field detection unit 200 and a portion that receives a signal in the frequency hopping communication unit 100 And may be shared. For example, FIG. 5 shows an antenna 210 and a down-converter 220 as components of the hopping field detection unit 200, and these components are components that receive a signal indicating a fluctuation of a surrounding electromagnetic field. Are components that perform the same functions as the signal receiving unit (the antenna 110 and the down converter 120 in FIG. 2) in the frequency hopping communication unit 100. Therefore, in practical use, for example, the antenna 210 and the antenna 110 may be shared by the same antenna, and the down converter 220 and the down converter 120 may be shared by the same circuit.
[0055]
<<<< §4. Application to a wireless communication device having a plurality of communication units >>>>>
Here, an embodiment in which the present invention is applied to a wireless communication device having a plurality of communication units will be described. FIG. 12 is a block diagram showing such an embodiment. The wireless communication device shown here has a first wireless communication unit 310 having a function of performing communication by a first wireless communication method and a second wireless communication unit having a function of performing communication by a second wireless communication method. Unit 320. Specifically, the first wireless communication unit 310 is a communication unit that performs communication by a mobile phone, and the second wireless communication unit 320 is a communication unit that performs communication by Bluetooth, wireless LAN, or the like. In this way, it is expected that the form of incorporating a plurality of different communication units in one wireless communication device and performing communication with external devices based on different communication standards will continue to increase in the future. Here, when at least the second wireless communication unit 320 is a communication unit that employs the frequency hopping method, the technical idea according to the present invention can be applied.
[0056]
In this case, the second wireless communication unit 320 can oscillate at an arbitrary frequency selected from the plurality of frequencies in order to perform communication while switching a plurality of communication frequencies in a predetermined cycle in a predetermined order. An oscillation circuit is provided, and has a function of performing wireless communication using a frequency hopping method or preparing for the wireless communication using an AC signal generated by the oscillation circuit. Therefore, as shown in the figure, the hopping field detection unit 330 (which may have the same configuration as the hopping field detection unit 200 described above) is incorporated in this wireless communication device to detect the presence of a specific electromagnetic hopping field in the surroundings. In this way, at least the oscillation circuit in the second wireless communication unit 320 may be configured to operate only when the hopping field detection unit 330 detects the presence of a specific electromagnetic hopping field.
[0057]
When the wireless communication device is in a standby state, the first wireless communication unit 310 and the hopping field detection unit 330 perform a normal operation. However, in the second wireless communication unit 320, since at least the operation of the oscillation circuit is in a pause state, a normal standby operation is not performed. Here, if there is an incoming call to the mobile phone functioning as the first wireless communication unit 310, the mobile phone is in a normal standby state, and the incoming call operation is executed as it is. On the other hand, when a call is made to the Bluetooth device that functions as the second wireless communication unit 320, the second wireless communication unit 320 itself is not in the standby state, but the hopping field detection unit 330 detects the hopping field. Then, the detection signal is given to the second wireless communication unit 320. The second wireless communication unit 320 that has received the detection signal operates the oscillation circuit and shifts to a normal standby state, so that it is possible to respond as a Bluetooth device.
[0058]
In the future, it is expected that various functions will be incorporated into a mobile phone, and an important role will be given as a Bluetooth device as in the example shown in FIG. In this case, the mobile phone is generally kept in a standby state, and currently commercially available mobile phones are equipped with a battery having a sufficient capacity to maintain the standby state for a long time. . However, in the Bluetooth communication standard, since the frequency hopping method is adopted, the battery consumption becomes considerably large in the standby state, and it is difficult to maintain the standby state for a long time. The present invention is extremely effective in solving such a problem. Since the oscillation circuit is not incorporated in the hopping field detection unit 330, the power consumption thereof is almost the same as that of the first wireless communication unit 310, and the standby state can be maintained for a long time by a normal battery. It is.
[0059]
In the future, it is expected that a number of Bluetooth base stations will be installed in stations, public facilities, restaurants, and the like, and various services will be provided. Therefore, a mobile phone that also functions as a Bluetooth device as shown in FIG. 12 plays a large role as a mobile station that receives such a service. However, the function as a Bluetooth device can be performed only when the terminal enters the vicinity of a Bluetooth base station (within a communicable area). It is a waste of power. By applying the present invention, such waste can be eliminated, and when the mobile terminal enters an area near a Bluetooth base station, a hopping field in the area is detected and communication is immediately started as a Bluetooth device. It becomes possible to do.
[0060]
In practice, as in the example shown in FIG. 13, the hopping field detection unit 330 is incorporated in the second wireless communication unit 320, and a signal indicating the fluctuation of the surrounding electromagnetic field in the hopping field detection unit 330 is received. It is preferable to share the part that performs the operation and the part that receives the signal in the second wireless communication unit 320. As described above, if the hopping field detection unit 330 is incorporated in the component as the second wireless communication unit 320, components such as an antenna and a down converter can be shared by both. Alternatively, as in the example shown in FIG. 14, the hopping field detection unit 330 can be incorporated in the first wireless communication unit 310 to share necessary components.
[0061]
<<<< §5. Use as a hopping field detection device >>>>>
In the embodiments described above, the hopping field detection unit 200 shown in FIG. 5 is incorporated in a wireless communication device using the frequency hopping method, and is used for on / off control of the operation of the oscillation circuit 140 in the frequency hopping communication unit 100. An example of use was described. However, since the hopping field detection unit 200 illustrated in FIG. 5 has a function of determining the presence or absence of a communication environment using a frequency hopping method such as Bluetooth, the hopping field detection unit 200 is used alone as a hopping field detection device. It is also possible.
[0062]
For example, when wireless communication using a frequency hopping method is to be performed, the present invention can be used for an application in which it is detected in advance whether a hopping field having a sufficient strength necessary for communication exists.
[0063]
Alternatively, if a plurality of wireless communication systems coexist and they share the same frequency band, the communication state of another system can be efficiently known, and the effect of preventing interference between systems can be obtained. Can be That is, if the hopping field detection unit 200 is used, it is possible to recognize whether or not a predetermined hopping field exists in the surroundings. Therefore, another communication system currently performs wireless communication using the frequency hopping method. For example, when another system is performing wireless communication, it is possible to refrain from communicating and prevent interference from occurring between different communication systems. Become.
[0064]
【The invention's effect】
As described above, according to the wireless communication apparatus using the frequency hopping scheme according to the present invention, it is possible to reduce power consumption during standby. Further, the use of the hopping field detection device according to the present invention makes it possible to confirm the presence of a surrounding hopping field.
[Brief description of the drawings]
FIG. 1 is a diagram showing the basic principle of a general frequency hopping scheme.
FIG. 2 is a block diagram illustrating an example of a basic configuration of a communication unit 100 that performs communication by a frequency hopping method.
FIG. 3 is a time diagram for explaining a general operation in a standby state between a base station and a mobile station adopting the frequency hopping scheme.
FIG. 4 is a block diagram showing a basic configuration of a wireless communication device using a frequency hopping scheme according to the present invention.
FIG. 5 is a block diagram showing a specific configuration example of a hopping field detection unit 200 shown in FIG.
FIG. 6 is a graph showing operating characteristics of a single tuning circuit used as the frequency / amplitude conversion circuit 230 shown in FIG.
7 is a block diagram illustrating an example in which a frequency / amplitude conversion circuit 230 illustrated in FIG. 5 is configured using a phase change circuit 231.
8 is a graph showing operation characteristics of the phase change circuit 231 shown in FIG.
9 is a graph showing an example of an envelope signal output from the envelope detection circuit 240 shown in FIG.
FIG. 10 is a block diagram showing a configuration example of a time-series pattern determination circuit 250 shown in FIG.
11 is a graph showing a state in which the envelope signal shown in FIG. 9 is sampled by the sampling circuit 251 shown in FIG. 10;
FIG. 12 is a block diagram of an embodiment in which the present invention is applied to a wireless communication device having a plurality of communication units.
FIG. 13 is a block diagram showing a modification of the embodiment shown in FIG.
FIG. 14 is a block diagram showing another modification of the embodiment shown in FIG.
[Explanation of symbols]
100: frequency hopping communication unit
110 ... antenna
120 ... Down converter
130 ... Up Converter
140 ... oscillation circuit
150 ... Signal multiplier
160 ... signal multiplier
170 ... Detection circuit
180 ... communication control circuit
200: Hopping field detector
210 ... antenna
220 ... Down converter
230: frequency / amplitude conversion circuit
231 phase change circuit
232 ... Signal multiplier
240 ... Envelope detection circuit
250: time-series pattern determination circuit
251 ... Sampling circuit
252: Sample value storage circuit
253 ... Comparator
254 ... Counter
255: count value determination unit
310: first wireless communication unit (mobile phone)
320: second wireless communication unit (Bluetooth, wireless LAN, etc.)
330 hopping field detector
A: Maximum amplitude
Ai: Intermediate amplitude
E: Envelope
f0 to f4: frequencies to be hopped
fmax: maximum value of the frequency to be hopped
fmin: minimum value of the hopping target frequency
fi: Any intermediate frequency
S1 to S12: sample values
T, T1, T2 ... cycle
t0 to t4: Time at which frequency hopping is performed
V0-V3 ... voltage value
φi: Intermediate phase value

Claims (9)

A wireless communication device using a frequency hopping method of performing communication while switching a plurality of communication frequencies according to a predetermined order in a predetermined cycle,
An oscillation circuit capable of oscillating at an arbitrary frequency selected from the plurality of frequencies, and using an AC signal generated by the oscillation circuit, wireless communication using a frequency hopping method or frequency hopping for preparing the same. Communication unit,
A hopping field detector that detects the presence of a specific electromagnetic hopping field in the surroundings,
A radio communication apparatus using a frequency hopping method, wherein the oscillation circuit is operated only when the hopping field detection unit detects the presence of a specific electromagnetic hopping field. . The wireless communication device according to claim 1,
A radio part using a frequency hopping scheme characterized by sharing a part for receiving a signal indicating a fluctuation of a surrounding electromagnetic field in a hopping field detection part and a part for receiving a signal in a frequency hopping communication part. Communication device. A first wireless communication unit having a function of performing communication by the first wireless communication method, a second wireless communication unit having a function of performing communication by the second wireless communication method, and a specific electromagnetic device in the surroundings. A hopping field detection unit that detects the presence of a hopping field,
At least the second wireless communication unit is selected from the plurality of frequencies to perform wireless communication using a frequency hopping method of performing communication while switching a plurality of communication frequencies in a predetermined cycle according to a predetermined order. An oscillating circuit capable of oscillating at an arbitrary frequency, using an AC signal generated by the oscillating circuit, having a function of performing wireless communication using a frequency hopping method or preparing for the same, and A wireless communication device using a frequency hopping method, wherein the oscillation circuit operates only when a detection unit detects the presence of a specific electromagnetic hopping field. The wireless communication device according to claim 3,
A frequency hopping method, wherein a portion for receiving a signal indicating a change in a surrounding electromagnetic field in a hopping field detector and a portion for receiving a signal in a first or second wireless communication unit are shared. Wireless communication device using the. The wireless communication device according to any one of claims 1 to 4,
A hopping field detection unit configured to receive a signal indicating a change in a surrounding electromagnetic field in a hopping frequency band; a frequency / amplitude conversion circuit configured to convert a frequency component of the received signal into an amplitude component; An envelope detection circuit that detects an envelope, and a time-series pattern determination circuit that determines whether or not a time-series pattern included in the detected envelope matches a frequency hopping pattern. Outputting a detection signal indicating that the presence of an electromagnetic hopping field has been detected when a match is determined. The wireless communication device according to claim 5,
A wireless communication device using a frequency hopping method, wherein a frequency / amplitude conversion circuit is configured using a single tuning circuit or a phase change circuit. The wireless communication device according to claim 5, wherein
A time-series pattern determination circuit, which samples a signal having a gain corresponding to the envelope detected by the envelope detection circuit at a predetermined sample period, and outputs the sampled signal as a sequence of sample values according to the gain; and A counter that counts the period of the synchronization signal synchronized with the period, a sample value storage circuit that stores a sample value output from the sampling circuit for a predetermined period, and a sample value storage circuit that stores the sample value output from the sampling circuit. And a comparator that resets the counter when the two values do not match, and a counter value immediately before the counter is reset. Count value determination to determine whether the included time-series pattern matches the frequency hopping pattern Wireless communication devices using frequency hopping, characterized in that it comprises a and. The wireless communication device according to claim 7,
The frequency hopping method, wherein the count value determination unit performs a pattern match determination by recognizing whether a time corresponding to the count value immediately before resetting matches a frequency switching cycle in the frequency hopping method. Wireless communication device using the. A hopping field detection device comprising a hopping field detection unit described as one component of the wireless communication device according to claim 1.

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