JP2002300630A - Radio communication system and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable radio communication system that can quickly decide a communication channel and has low power consumption, and to provide a radio communication method. SOLUTION: Although the astatic circulating system using plural communication channels is basic, the number of the communication channels is reduced for preventing a control code for identifying a transmitter from being lengthened, and the utility of the entire channels is periodically monitored with a high time resolution by a broadband digital receiver to increase reliability. When interference is detected, the communication channel is changed, and merely the communication channel having small conflict with other systems and a small amount of interference can be continuously used. Additionally, the plural communication channels are dispersed for assigning, thus preventing the entire communication channels from being affected by one interference that is spread in terms of frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wireless communication system and a wireless communication method.

More specifically, the present invention relates to a wireless communication system and a wireless communication method for performing communication by sharing a plurality of narrowband wireless channels between a master unit and a plurality of slave units.

[0003]

2. Description of the Related Art As a wireless communication system in which a plurality of wireless devices share a plurality of narrow-band channels, such as a specific low-power radio, all channels that may be used in transmission by a receiver are conventionally used. A non-local cycling system that monitors in chronological order and allows the transmitter to receive whatever channel it is transmitting; or a dedicated channel for line control is provided between the master and slave units. A common line control method for performing communication after adjusting a communication channel is widely known. Other known methods include, for example, a “security wireless system”
As described in Japanese Patent Application Laid-Open No. 6-291723, the master unit sequentially carries out carrier sense on all channels that may be used for transmission to check the channel use status, and determines the most significant amount of communication traffic. There is a method in which a small number of channels are selected and set as communication channels on a regular basis.

[0004]

However, the above-described non-stationary cyclic method has an advantage that as the number of channels waiting on the receiving side increases, channel contention between systems decreases, but it takes time to switch the frequency. Therefore, unless the control code for identifying the transmitter is long in proportion to the number of waiting channels, communication cannot be performed reliably, and as a result, power is consumed on the transmitter side in transmission other than the original data. There was a problem that would.

In the common line control method described above, since communication for channel adjustment is required in addition to the data to be transmitted, there is a problem that power is consumed excessively. In addition, since it is possible that the line control channel cannot be used, there is also a disadvantage that the processing becomes very complicated when realizing highly reliable communication.

Further, in a system typified by the "security radio system" (see Japanese Patent Application Laid-Open No. 6-291723), it is expected that the number of channel conflicts between the systems can be greatly reduced. Since only one communication channel is set between the master unit and the slave unit, there is a problem that if the channel cannot be used for any reason, communication becomes impossible.
In addition, since carrier sensing is performed sequentially while switching channels, there is a problem that the carrier sensing cycle becomes very long as the number of channels increases. As a result, for example, when data from another system is in a short packet format, the data may not be detected.

Accordingly, an object of the present invention is to provide
An object of the present invention is to provide a wireless communication system and a wireless communication method that can determine a communication channel in a short time, consume low power, and have high reliability.

[0008]

In order to achieve the above object, the present invention according to claim 1 provides communication between a parent device and a plurality of child devices by sharing a plurality of narrowband wireless channels. Wherein the slave unit is output from a predetermined detection unit via a specific vacant channel among a plurality of communication channels allocated in advance from all available channels. A narrow-band transmitting unit that transmits detection information to the master unit, and a narrow-band receiving unit that receives channel control information transmitted from the master unit via the specific free channel, the master unit includes: A narrow-band receiving unit for sequentially scanning the plurality of communication channels to receive a signal transmitted from the slave unit; a wide-band receiving unit for monitoring the radio wave usage of all available channels; By means Control means for changing the allocation of the communication channel based on the monitored radio wave use status, and narrowband transmitting means for notifying the slave unit of the change of the communication channel allocation as the channel control information. It is a thing.

According to a second aspect of the present invention, in the wireless communication system according to the first aspect, the wideband receiving means converts a wideband received signal including the usable channel into a digital signal and periodically performs a Fourier transform. Then, the signal strength of each channel is obtained from the power spectrum, and these are supplied to the control means as information indicating the radio wave use situation.

According to a third aspect of the present invention, in the wireless communication system according to the first or second aspect, the control means includes:
When the signal strength output from the wideband receiving means within a predetermined period is added for each of the available channels, the sum is greater than a preset threshold value. If the parent device and the child device do not use the channel during the period, it is determined that an interference wave exists in the channel.

According to a fourth aspect of the present invention, in the wireless communication system according to any one of the first to third aspects, the communication channels in the initial state are separated from each other by a predetermined number of channel intervals or more. Assigned to
The control means is configured such that, when an interference wave is present in the current communication channel, a channel that is separated from the current communication channel by a predetermined number of channel intervals or more and has no interference wave is detected. Among them, the channel having the smallest accumulated value of signal strength is assigned as a new communication channel instead of the communication channel in which the interference wave exists.

According to a fifth aspect of the present invention, in the wireless communication system according to any one of the first to fourth aspects, when the plurality of allocated communication channels cannot all be used due to interfering waves, The channels are switched in a predetermined order, and data of a length determined for each channel is transmitted to the master unit to notify an abnormal state, and the master unit uses the broadband receiving means to detect an abnormality of the slave unit. Detect the state.

[0013] The present invention according to claim 6 is a slave unit that transmits predetermined detection information via a specific free channel among a plurality of communication channels allocated in advance from all available channels, A wireless communication method for performing communication using a plurality of narrow-band wireless channels with a base unit, comprising: a monitoring step of monitoring radio wave usage of all available channels; and Controlling the communication channel allocation change based on the radio wave use situation.

According to a seventh aspect of the present invention, in the wireless communication method according to the sixth aspect, in the monitoring step, a wideband received signal including the usable channel is converted into a digital signal and periodically Fourier-transformed. The signal strength of each channel is obtained from the power spectrum, and in the control step, the signal strength of each channel is used as information indicating the radio wave use status.

According to an eighth aspect of the present invention, in the wireless communication method according to the sixth or seventh aspect, in the control step, the signal strength obtained in the monitoring step within a predetermined period is converted into the total number of available channels. When the sum is greater than a preset threshold when the sum is added for each channel, and the master unit and the slave unit do not use the channel during the period. , It is determined that an interference wave exists in the channel.

According to a ninth aspect of the present invention, in the wireless communication method according to any one of the sixth to eighth aspects, the communication channels in the initial state are separated from each other by a predetermined number of channel intervals or more. In the control step, when an interfering wave is present in the current communication channel, if a channel that is separated from the current communication channel by a predetermined number of channel intervals and has no interfering wave is found, The channel having the smallest accumulated signal strength among the channels having no waves is assigned as a new communication channel in place of the communication channel having the interfering wave.

The present invention according to claim 10 is the invention according to claims 6 to 9.
In the wireless communication method according to any one of the above,
If all of the assigned communication channels cannot be used due to interference waves, the channels are switched in a predetermined order, and data of a length determined in each channel is transmitted to the master unit to notify an abnormal state, The master unit detects an abnormal state of the slave unit using the broadband receiving unit.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention are based on an asymmetric circulation method using a plurality of communication channels, but control for identifying a transmitter while keeping the number of communication channels small. To prevent code lengthening and increase reliability, use a wideband digital receiver to periodically monitor the usage status of all channels with high time resolution. The channel is changed so that only a communication channel with less competition or interference with other systems can be used at all times.

Furthermore, by distributing and allocating a plurality of communication channels, it is possible to prevent the entire communication channel from being affected by one interference wave that is spread in frequency.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present embodiment will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory diagram schematically showing the operation principle of the radio communication system according to the present embodiment. In the present embodiment, a plurality of slave units and a single master unit communicate with each other via a narrow band transmission channel of channel 1 to channel 40. As will be described in detail later with reference to FIG. 4, the master unit includes a narrow band transceiver that scans and communicates with each channel, a wide band receiver that collectively monitors all channels,
And a control unit for deciding to change the communication channel.

The broadband receiver included in the master unit is shown in FIG.
As shown below, after A / D conversion of a received signal obtained from a wideband signal including channel 1 to channel 40, spectrum (power) for each channel is collectively detected by FFT analysis.

In the example shown in this figure, three channels (3 ch) are allocated as communication channels, and a communication is performed by finding an empty channel from the three channels. And the parent machine,
Separately, the radio wave use status of all the channels (ch1 to ch40) is constantly monitored, and when a collision with another system or an interference wave is detected, the communication channel assignment is changed.

FIG. 2 is an explanatory diagram exemplifying the communication timing between the slave unit and the master unit. In this figure, detection information from a lock sensor (not shown) is periodically (for example, once / 30
Minutes) transmission and non-periodic transmission performed when a change occurs in the detection information from the lock sensor (for example, when locking / unlocking is detected). That is,
Indicates periodic transmission, and indicates irregular transmission.

FIG. 3 is a block diagram showing a detailed configuration of the slave unit shown in FIG. In this figure, 2 is a slave unit antenna, 4 is an antenna switch, 6 is a radio reception unit, 8 is a demodulation unit, 10 is a reception level detection unit, 12 is a sensor unit installed inside or outside the slave unit, 14 is Transmission / reception control unit, 1
6 is a modulator, 18 is a radio transmitter, and 20 is a local oscillator. The operation of the slave unit will be described later in detail with reference to FIG.

FIG. 4 is a block diagram showing a detailed configuration of the master unit shown in FIG. In the figure, reference numeral 30 denotes a narrowband transmission / reception antenna, 32 denotes an antenna switch, 34 denotes a radio reception unit, 36 denotes a demodulation unit, 38 denotes a reception level detection unit, 40 denotes a transmission / reception control unit, 42 denotes a modulation unit, and 44 denotes a radio transmission unit. , 46
Is a local oscillator, which is a narrow band transceiver 10 as a whole.
0.

Reference numeral 50 denotes a broadband receiving antenna; 52, a radio receiving unit; 54, a frequency analyzing unit for performing FFT analysis;
Reference numeral 6 denotes a calculation unit, which constitutes the wideband receiver 200 as a whole. 300 is a control unit.

The operation of the master unit will be described later with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 5 is a flowchart showing a processing procedure on the slave unit side.

In step S1, an initially assigned channel is set.

In step S2, it is determined whether or not a predetermined transmission condition is satisfied (for example, whether a regular time has elapsed).

In step S3, carrier sense is performed sequentially from the smaller number of allocated channels to find an empty channel.

In step S4, it is determined whether there is an empty channel. If there is no free channel (step S4: NO), predetermined abnormal processing is performed in step S5. On the other hand, if there is an empty channel (step S4: YES), the control proceeds to step S6.

In step S6, the detection information (including the ID information) is transmitted to the parent device through the vacant channel, and the timer is started.

In step S7, it is determined whether an acknowledgment (acknowledge: acknowledgment) has been received from the master unit within a predetermined time. If acknowledgment is not received from the master unit, the channel used for transmission is excluded from the allocated channels in step S8. On the other hand, acknowledgment
Is received, in step S9, it is determined whether there is a change in the assigned channel. If there is a change in the assigned channel, in step S10,
Perform processing for changing the assigned channel.

Next, the processing procedure of the master unit will be described with reference to the flowcharts shown in FIGS.

However, in these flowcharts,
As a precondition, the number of slave units is “M”. Also, the “assigned channel”, “ch change request flag”, and “ack transmission flag” set by the control unit can be referred to by the narrowband transceiver. Further, the data demodulated by the narrow-band transceiver and information on which assigned channel it is detected can be referred to by the control unit. Similarly, the accumulated signal strength calculated by the broadband receiver can be referred to the control unit.

FIG. 6 is a flowchart showing a processing procedure in the narrow band transceiver 100 (see FIG. 4) of the master unit.

In step S21, the assigned channels are sequentially subjected to carrier sense. Steps S21 and S22 are repeated until a signal is detected.

In step S23, the signal is demodulated and passed to the control unit.

In step S24, it is determined whether the ack transmission request flag is "1".

In step S25, it is determined whether or not the ch (channel) change request flag is "1". If the channel change request flag is not “1”, step S26
Sends an ack to the slave. On the other hand, if the channel change request flag is “1”, the acknowledgment and the contents of the change of the assigned channel are transmitted to the child device in step S27.

FIG. 7 shows a master broadband receiver 200 (FIG. 4).
9 is a flowchart showing a processing procedure in the second embodiment.

In step S31, the accumulated signal strength for each channel is cleared.

In step S32, the baseband signal including all channel frequencies is A / D-converted and frequency-converted.

In step S33, the cumulative signal strength in the past predetermined period is calculated for each channel from the power spectrum, and the calculation result is reported to the control unit.

FIG. 8 shows a control unit 300 of the master unit (see FIG. 4).
6 is a flowchart showing a processing procedure in.

In step S41, an initial assigned channel is set.

In step S42, the channel change request flag = 0, the ack transmission request flag = 0, and the channel change notification flag (i) = 0. Here, i = 1... M.

In step S43, it is determined whether or not there is demodulated data.

In step S44, the demodulated data analysis (I
Based on the D information, whether the data is data from a slave unit in the system is performed, and the channel change request flag = 0 and the ack transmission request flag = 0.

In step S45, it is determined whether or not the detection information from the slave unit K has been received (1 ≦ K ≦ M).

In step S46, the ack transmission request flag is set to "1".

In step S47, it is determined whether or not the channel change notification flag (K) = 1.

In step S48, the channel change request flag = 1 and the channel change notification flag (K) = 0.

On the other hand, if a negative determination (NO) is made in step S45, it is determined that the interference wave (from another system), and in step S49, whether or not the channel change notification flag (i) = 0. (Where i = 1... M).

In step S50, a channel having the smallest cumulative signal strength other than the currently assigned channel is selected and replaced with the assigned channel in which the interference wave is detected. Further, the channel change notification flag (i) is set to 1 (i = 1...
-M).

FIG. 9 is an explanatory diagram exemplifying a communication channel changing operation (that is, a channel switching operation) in the present embodiment. In this figure, six channels ch1
~ Ch6 can be shared by the three systems A, B, and C, and systems B and C operate as systems other than the present system with respect to system A (the present system). Therefore, when radio waves from the system B or the system C are mixed into the communication channel of the system A (the present system), the radio waves from the systems B and C become disturbance waves for the system A (the present system).

As shown in FIG. 9, in the system A (this system), the number of allocated channels is two, and ch1 and ch4 are allocated as communication channels in an initial state. FIG. 10 illustrates the communication state at this time more specifically.

FIG. 10 shows a procedure for changing the assignment of the communication channel due to the intrusion of the interfering wave during the communication process of the system A shown in FIG. 9, and for notifying the slave unit of the change in the assignment. I have. (A) When the radio wave C1 (jam 1) from the system C is detected and the communication channel is changed from ch4 to ch5: (b) The radio wave B2 (jam 2) from the system B is detected and communication is performed. When the channel is changed from ch1 to ch3:
It shows in detail the communication procedure in the case of occurrence. The details are clear from FIG. 10, and a detailed description will be omitted.

[0061]

As described above, according to the present invention, the communication channel can be determined in a short time, the power consumption is low,
In addition, a highly reliable wireless communication system and wireless communication method can be realized.

In other words, according to the present invention, by suppressing the number of communication channels in the non-localized circulation system and switching communication channels based on the result of detection of an interference wave, the effects of channel competition with other systems and interference waves can be obtained. It is possible to realize a highly reliable wireless communication system and wireless communication method with less power consumption.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing an operation principle of a wireless communication system to which the present invention is applied.

FIG. 2 is an explanatory diagram exemplifying communication timing between a slave unit and a master unit;

FIG. 3 is a block diagram illustrating a detailed configuration of a slave unit illustrated in FIG. 1;

FIG. 4 is a block diagram showing a detailed configuration of a master unit shown in FIG.

FIG. 5 is a flowchart illustrating a processing procedure on the slave device side.

FIG. 6 is a flowchart showing a processing procedure in the narrowband transceiver 100 of the parent device.

FIG. 7 is a flowchart showing a processing procedure in the broadband receiver 200 of the parent device.

FIG. 8 is a flowchart showing a processing procedure in the control unit 300 of the master unit.

FIG. 9 is an explanatory diagram exemplifying a communication channel changing operation, that is, a channel switching operation in the present embodiment.

FIG. 10 changes the communication channel assignment due to the intrusion of an interference wave during the communication process of the system A shown in FIG. 9;
FIG. 9 is a diagram showing a procedure for notifying the slave unit of the change in assignment.

[Explanation of symbols]

 Reference Signs List 2 slave unit antenna 4 antenna switch 6 wireless receiving unit 8 demodulation unit 10 reception level detecting unit 12 sensor unit installed inside or outside slave unit 14 transmission / reception control unit 16 modulation unit 18 wireless transmission unit 20 local oscillation unit 30 narrow band Transmission / reception antenna 32 Antenna switch 34 Radio reception unit 36 Demodulation unit 38 Reception level detection unit 40 Transmission / reception control unit 42 Modulation unit 44 Radio transmission unit 46 Local oscillation unit 50 Broadband reception antenna 52 Radio reception unit 54 Frequency analysis unit 56 Operation unit 100 Narrow band Transceiver 200 Broadband receiver 300 Control unit

Claims (10)

[Claims] 1. A wireless communication system for performing communication by sharing a plurality of narrow-band wireless channels between a master unit and a plurality of slave units, wherein the slave unit is selected from all available channels. Among a plurality of communication channels allocated in advance, via a specific vacant channel, a narrow band transmitting unit for transmitting detection information output from a predetermined detecting unit to the master unit, and via the specific vacant channel Narrow-band receiving means for receiving channel control information transmitted from the master unit, wherein the master unit sequentially scans the plurality of communication channels and receives signals transmitted from the slave unit. A narrow-band receiving unit that performs monitoring; a broadband receiving unit that monitors the radio wave usage of all available channels; and a division of the communication channel based on the radio wave usage monitored by the wideband receiving unit. Wireless communication system comprising: the control means for abutting change, and a narrow-band transmission means for notifying the slave unit assignment changes the communication channel as the channel control information. 2. The wireless communication system according to claim 1, wherein the wideband receiving unit converts the wideband reception signal including the usable channel into a digital signal, performs a Fourier transform on a regular basis, and calculates a power spectrum from the power spectrum. A wireless communication system, wherein signal strengths of respective channels are obtained and supplied to the control unit as information indicating the radio wave use status. 3. The wireless communication system according to claim 1, wherein the control unit calculates a signal strength output from the wideband receiving unit within a predetermined period for each of the available channels. If the sum is greater than a preset threshold when the sum is added, and the master unit and the slave unit do not use the channel during the period, the channel A wireless communication system, wherein it is determined that an interference wave exists. 4. The wireless communication system according to claim 1, wherein the communication channels in the initial state are allocated such that their communication channels are separated by a predetermined number of channel intervals or more. The control means, when an interference wave is present in the current communication channel, when a channel that is separated from the current communication channel by a predetermined number of channel intervals or more and has no interference wave is found, when the interference wave is not present, A wireless communication system according to claim 1, wherein a channel having the smallest accumulated value of signal strength is assigned as a new communication channel instead of a communication channel in which an interference wave exists. 5. The wireless communication system according to claim 1, wherein the slave sets the channels in a predetermined order when all of the plurality of allocated communication channels cannot be used due to an interference wave. Switching, transmitting data of a length determined in each channel to the master unit to notify an abnormal state, and the master unit detects the abnormal state of the slave unit using the broadband receiving means. A wireless communication system, characterized by: 6. A slave unit transmitting predetermined detection information via a specific vacant channel among a plurality of communication channels allocated in advance from all available channels, and a master unit, A wireless communication method for performing communication using a plurality of narrowband wireless channels, comprising: a monitoring step of monitoring the radio wave usage of all available channels; and a radio communication method based on the radio wave usage obtained in the monitoring step. And a control step of changing the assignment of the communication channel. 7. The wireless communication method according to claim 6, wherein, in the monitoring step, a wideband received signal including the usable channel is converted into a digital signal and periodically Fourier-transformed, and each power spectrum is converted from a power spectrum to a digital signal. A wireless communication method, wherein a signal strength for each channel is obtained, and in the control step, a signal strength for each channel is used as information indicating the radio wave use situation. 8. The wireless communication method according to claim 6, wherein, in the control step, a signal strength obtained in the monitoring step within a predetermined period is added for each of the available channels. When they are combined, if the sum is greater than a preset threshold, and if the parent device and the child device do not use the channel during that period, the A wireless communication method comprising determining that an interference wave exists. 9. The wireless communication method according to claim 6, wherein the communication channels in the initial state are allocated such that the communication channels are separated from each other by a predetermined number of channel intervals or more. In the control step, when an interference wave is present in the current communication channel, if a channel that is separated from the current communication channel by a predetermined number of channel intervals or more and has no interference wave is found, a channel in which no interference wave exists is detected. 2. The wireless communication method according to claim 1, wherein a channel having the smallest accumulated signal strength is assigned as a new communication channel instead of a communication channel in which an interference wave exists. 10. The wireless communication method according to claim 6, wherein the slave sets the channels in a predetermined order in a case where all of the allocated communication channels cannot be used due to an interference wave. Switching, transmitting data of a length determined in each channel to the master unit to notify an abnormal state, and the master unit detects the abnormal state of the slave unit using the broadband receiving means. Characteristic wireless communication method.