JP3699435B2 - Wireless communication system and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless communication system and method, and more particularly to a wireless communication system and method for performing communication by sharing a plurality of narrowband wireless channels between a parent device and a plurality of child devices.
[0002]
[Prior art]
In a wireless communication system, a control channel and a communication channel are used as channels for communication. The control channel is used for making a communication request, setting a communication channel, and the like, and the communication channel is used for transmission / reception of data to be actually exchanged.
[0003]
For example, when a master unit (base station) wants to obtain information from a slave unit (terminal), it transmits a transmission request and a communication channel number to the slave unit using the control channel, and then from the slave unit via the communication channel. Wait for send data. The slave unit monitors the control channel at certain intervals (several seconds) to check whether there is a transmission request from the master unit, and when there is a transmission request, starts transmission on the specified communication channel. Both channels are used. In the case of such a wireless communication system using a control channel, there is an advantage that the base unit can arbitrarily set a communication channel.
[0004]
Even in a simple radio system using a specific low power standard, a communication system using a control channel may be used. Because the frequency band defined by this standard is shared by various wireless devices, communication channels that avoid channels with poor line conditions, such as channels with jamming waves and channels used by other systems This is because it is very effective that the setting can be made.
[0005]
On the other hand, for example, a simple wireless device attached to a fire alarm or a gas meter is required to operate in units of years with several dry batteries, so that it is required to minimize power consumption. The above-described method using the control channel consumes a large amount of power to perform communication using the control channel in addition to transmitting / receiving data that is originally transmitted / received through the communication channel. It is difficult to do. Therefore, by adopting a system configuration in which a communication channel number is set in advance at the time of system installation (fixed channel assignment), the master unit is always in a receiving state, and the slave unit transmits at an arbitrary timing, Reduction of power consumption is being performed.
[0006]
However, in this system configuration, power saving is achieved, but the communication channel number is fixed, so communication is interrupted if there are interference waves or radio waves from other communication systems on the set channel. There is.
[0007]
As a technique for solving this problem caused by interference waves or the like, a channel circulation technique in which a plurality of channels are applied to the system configuration has been proposed (see Patent Document 1). In this method, a plurality of channels to be used for communication are set in advance, the slave unit selects an arbitrary channel from a plurality of channels, and transmission is performed. This is a technique for waiting for a transmission signal.
[0008]
By using this channel circulation method, the handset can select a channel with a good line state from a plurality of set channels, so communication using avoiding channels with jamming waves or other communication system radio waves is avoided. Accuracy can be improved.
[0009]
Another wireless communication system is based on a non-stationary circulation system that uses multiple communication channels, and a broadband digital receiver is used as the master unit to regularly monitor the usage status of all channels with high time resolution. There is a configuration in which when a jamming wave is detected, the communication channel is changed so that only a communication channel with little contention or jamming with other systems can always be used (see Patent Document 2).
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 2-121093
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-300630
[Problems to be solved by the invention]
In the above-described channel circulation method (Patent Document 1), since a plurality of set channels are fixed, if any of the set channels has an interference wave, the channel cannot be used. The number of active channels is reduced. In other words, the system has low interference wave resistance. In an extreme case where an interference wave exists in all of the set channels, communication may be completely interrupted as in the case of fixed channel assignment. Therefore, in order to improve the interference wave resistance of the system so that communication is not completely interrupted, it is necessary to increase the number of channels to be set (the number of cyclic channels).
[0013]
However, when the number of cyclic channels increases, power consumption increases as follows. In order for the parent device to reliably receive the transmission signal from the child device, it is necessary to add a signal detection bit (preamble) corresponding to the cyclic cycle time of the parent device to the head of the transmission signal of the child device. Since the cyclic cycle time of the master unit is proportional to the number of channels to be set, the pre-ampule length in one entire cycle is also proportional to the number of channels to be set. Therefore, as the number of cyclic channels increases, the transmission time by the slave unit becomes longer, leading to an increase in power consumption. On the other hand, in order to prevent an increase in power consumption, it is necessary to reduce the number of channels to be set. Therefore, the above-described problem of reduced interference wave resistance cannot be avoided.
[0014]
Further, in the system (Patent Document 2) in which the communication channel is changed in response to the detection of the interference wave based on the above-mentioned non-stationary circulation method, the above problem due to the channel circulation method can be avoided, but the base unit has a wideband digital Since a receiver is required, there is a problem that it is difficult to reduce the size and cost of the apparatus.
[0015]
Accordingly, an object of the present invention is to reduce the size and cost of the apparatus without requiring a broadband digital receiver as a base unit, and to prevent interference by allowing the communication channel to be arbitrarily changed without using a control channel. It is an object of the present invention to provide a communication system and method capable of achieving both improved wave resistance and reduced power consumption.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, according to one aspect of the present invention, in a wireless communication system that performs communication by sharing a plurality of narrowband channels between a parent device and a plurality of child devices, the parent device is set in advance. Means for circulating a plurality of channels used for communication and a monitoring channel and receiving a signal transmitted from the slave unit while monitoring a line state of an empty channel by the monitoring channel. The featured wireless communication system was implemented.
[0018]
In another aspect of the present invention, in a wireless communication system that performs communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units, the master unit uses a plurality of preset communication units. A means for circulating a channel and a monitoring channel and receiving a signal transmitted from the slave unit while checking a circuit state of the channel being circulated; and when a channel having a bad circuit state is found, the bad channel Instead, a new channel with the best line condition is allocated according to the monitoring result of the monitoring channel, and the circulation is continued for the new channel and channels other than the bad channel among the plurality of channels. And a wireless communication system characterized by comprising means.
[0019]
Here, the packets of the master unit and the plurality of slave units include channel information used for communication, and the master unit matches all the channel information of the packets of the master unit and the plurality of slave units. Sometimes it is preferable to allocate the new channel.
[0021]
In another aspect of the present invention, in a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units, the master unit uses a plurality of preset communication units. A wireless communication method is implemented, wherein the channel and the monitor channel are circulated, and the signal transmitted from the slave unit is received while the line state of the vacant channel is monitored by the monitor channel.
[0022]
In another aspect of the present invention, in a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units, the master unit uses a plurality of preset communications. A channel and a monitoring channel are circulated, and a signal transmitted from the slave unit is received while checking a circuit state of the channel being circulated; and when a channel having a bad circuit state is found, the bad channel Instead, a new channel with the best line condition is allocated according to the monitoring result of the monitoring channel, and the circulation is continued for the new channel and channels other than the bad channel among the plurality of channels. And a wireless communication method characterized by comprising the steps.
[0023]
Here, the packets of the master unit and the plurality of slave units include channel information used for communication, and the master unit matches all the channel information of the packets of the master unit and the plurality of slave units. Sometimes it is preferable to allocate the new channel.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the present invention is applied to a system using a specific low power standard will be described below with reference to the drawings.
(First embodiment)
The wireless communication system according to the present embodiment includes a single parent device and a plurality of child devices. The main unit and the sub unit can have the same configuration.
[0025]
As will be described later, the parent device circulates a plurality of channels used for the set communication, and receives a signal transmitted from the child device while checking the line state of the channel being circulated. Then, when a channel with a bad line condition is found, a new channel is assigned instead of the bad channel, and the circulation is continued for a channel other than the new channel (a channel other than the one with a bad line condition among multiple channels). To do.
[0026]
1, 2 is a slave (master) antenna, 4 is an antenna switch, 6 is a radio receiver, 8 is a demodulator, 10 is a reception level detector, and 12 is a slave ( A sensor unit installed inside or outside the master unit, 14 is a transmission / reception control unit, 16 is a modulation unit, 18 is a wireless transmission unit, and 20 is a local oscillation unit. The operations of the slave unit and the master unit will be described in detail later, but a lock sensor can be connected to the slave unit to transmit key lock / unlock information to the master unit.
[0027]
The communication operation is performed by the slave unit, and as shown in the communication timing of FIG. 2, the master unit is basically in a standby state at all times, and the slave unit performs transmission at an arbitrary timing.
[0028]
In FIG. 2, detection information from a locking sensor (not shown) is transmitted periodically (for example, once / 30 minutes) from the slave unit, and when detection information from the locking sensor changes (for example, locking / unlocking). The non-periodic transmission performed at the time of detection of a lock is illustrated. That is, (1) and (2) in this figure are periodic transmissions, and (3) represents non-periodic transmissions.
[0029]
The slave unit performs processing in accordance with the procedure according to the flowchart shown in FIG.
In step S1, an initial allocation channel is set. In step S2, it is determined whether or not a predetermined transmission condition is satisfied (for example, has the regular time elapsed)?
[0030]
In step S3, carrier sensing is performed in order from the smaller number of allocated channels to find a free channel.
[0031]
In step S4, it is determined whether there is a free channel. If there is no empty channel (step S4: NO), predetermined abnormality 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.
[0032]
In step S6, detection information (including ID information) is transmitted to the parent device through an empty channel, and a timer is started.
[0033]
In step S7, it is determined whether or not an ack (acknowledge) is received from the parent device within a predetermined time. If it is determined that ack is not received from the parent device, the channel used for transmission is removed from the assigned channel in step S8. On the other hand, if it is determined that ack has been received from the parent device, it is determined in step S9 whether there is a change in the allocated channel. If there is a change in the assigned channel, processing for changing the assigned channel is performed in step S10.
[0034]
Next, the operation of the master unit will be described with reference to the flowchart of FIG.
While changing the channel setting for local oscillator 20 in time (selecting reception frequency F in step S401 and setting the local oscillator to frequency F in step S402), the base unit circulates the set channels. And wait. For example, as shown in FIG. 5, it waits by circulating around the set three channels 2, 5, and 9. “Reception” in FIG. 5 is processing for determining the presence or absence of radio waves on the channel using the signal strength (RSSI) output from the reception level detection unit 10.
[0035]
When the RSSI exceeds a predetermined threshold, it is determined that there is a possibility that a signal (child device packet) from the child device exists in the channel, and reception is continued as shown in FIG. 6 (step S403). . In this continuation of reception, received data is decoded, and first, a handset packet identification signal (sync word) is searched (step S404). If a sync word is detected, it is determined as a slave unit packet, all bits are received (step S405), and the mode is switched to a transmission mode for transmitting a response signal (ack) to the slave unit.
[0036]
On the other hand, when the RSSI exceeds a predetermined threshold but no sync word is detected by searching for a certain time (basically the same time as the preamble length of the handset packet), It is determined that the channel has a jamming wave, and the jamming count value of that channel is incremented by +1 (steps S403, S404, and S406).
[0037]
If this disturbance count value is equal to or greater than a certain count value, it is determined that the channel state is not good, and a disturbance channel flag is set for that channel (steps S407 and S408).
[0038]
At the same time, the reception of the channel is stopped, and standby by the channel circulation is continued with the number of channels that is one channel less than the original. However, if a disturbing channel is established during the tour with the minimum number of patrol channels, the patrol of that channel is continued in order to ensure the lowest level of communication with the slave unit (steps S409 and S410).
[0039]
If there is a channel in which the disturbing channel flag is set, another new channel is assigned instead of this channel, but this assignment is performed when the master unit receives the slave unit packet.
[0040]
For example, as shown in FIG. 7, when an interference wave is first detected in the channel 5 during the patrol, instead of this, the channel 7 of the empty channels 1, 3, 4, 6, 7, 8, and 10 is newly set. If the disturbance is detected on channel 9 after the assignment, the channel 1 is newly assigned to the empty channel 1, 3, 4, 6, 8, 10 instead. continue. Which empty channel is to be a new channel is randomly assigned. When a disturbing wave is detected in a new channel, any other free channel is newly assigned instead.
[0041]
The slave unit packet includes channel information set in the slave unit. The master unit stores the channel information of all slave units as a table. As shown in the flowchart of FIG. 8, every time a slave unit packet is received, channel information is extracted from the slave unit packet and the channel information table is updated. (Steps S801 and S802).
[0042]
When there is a channel for which the jamming channel flag is set when the master unit receives the slave unit packet, the channel information table of this slave unit is referenced and the channel information of all the slave units is If the channel matches the channel, a new channel is assigned (steps S804 and S805), and then the parent device tour channel is changed (step S806). The newly added channel is presented as channel information in the ack signal packet to the slave unit, and the channel information of the slave unit that has received the ack signal is updated to the new channel information.
[0043]
Even if there is a channel with the disturbing channel flag set when the master unit receives the slave unit packet, if the channel information of all the slave units does not match the cyclic channel of the master unit, the channel will be changed. Since there is a possibility that a slave unit that cannot follow up may occur, it waits for the channel information of all slave units to match. When it is confirmed that the channel information of all the slave units matches the cyclic channel of the master unit, a new channel is assigned.
[0044]
FIG. 9 shows the channel information sharing method and new channel assignment timing between the slave unit and the master unit described above. In FIG. 9, the slave unit packet has channel information of the channel to be used (here, 3 channels) at the tip of the packet. Channel information is identified by hatching.
[0045]
FIG. 9 shows that when a disturbance wave is detected in the leftmost channel of the operation channel 90 and the circulation of the interference channel is stopped, the interference wave is detected in the center one channel of the operation channel 92 and the interference channel is circulated. The assignment timing of a new channel in the case where is canceled is shown.
[0046]
In this way, every time the master unit receives one packet, it is checked whether there is a disturbing channel. If there is a disturbing channel, a new channel is assigned when the traveling channels of all the slave units are the same.
[0047]
In the present embodiment, in addition, in order to select a channel with a better line state when assigning a new channel as described above, a monitor channel is added to the cyclic channel used for communication, and the cyclic channel and the monitor channel are circulated. Thus, it is possible to monitor the line status of the empty channel by the monitor channel.
[0048]
For example, as shown in FIG. 10, a monitor channel is added to the cyclic channel. FIG. 10 shows an example in which one monitor channel is added to the three-channel cyclic reception channels of cyclic channels 2, 5, and 9. The frequency of the monitor channel is set to the empty channel in order, and the line states of all the empty channels are checked in order. The cyclic channels 2, 5, 9 and the monitor channel 1 make a round, and the second monitor channel becomes the channel 3, and the empty channels are sequentially monitored.
[0049]
The investigation of the line state corresponds to a process of using the received signal strength (RSSI) output from the reception level detection unit 10 of the base unit to determine the presence / absence of radio waves on the channel, as with the cyclic channel. However, even if it is determined that the RSSI exceeds a predetermined threshold and radio waves are present, sync word detection is not performed, and since this channel is an empty channel and not a channel used by the slave unit, reception continues. There is nothing. Instead, if the RSSI exceeds a predetermined threshold and it is determined that radio waves are present, the disturbance count value is incremented by +1.
[0050]
This disturbance count value is stored in the table as a line state of an empty channel, and a channel having a good line state can be assigned by selecting a channel having the minimum disturbance count value at the time of cyclic channel assignment.
[0052]
【The invention's effect】
As described above, according to the wireless communication system and method of the present invention, the channel state of a channel is checked by visiting a plurality of channels without requiring a broadband digital receiver as a base unit. Therefore, it is possible to reduce the size and cost of the apparatus. Moreover, without using a control channel, it is possible to cycle through a plurality of channels used for preset communication and to arbitrarily change a communication channel in which an interfering wave exists to another channel, thereby improving the interference wave resistance. There is an effect that both power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a parent device or a child device used in a wireless communication system according to the present invention.
FIG. 2 is a diagram illustrating communication timings of a master unit and a slave unit in a wireless communication system according to the present invention.
FIG. 3 is a flowchart showing a processing procedure on the handset side.
FIG. 4 is a flowchart showing a processing procedure on the base unit side (interruption channel pausing stop processing).
FIG. 5 is a timing chart showing an example in which standby is performed by circulating around three channels.
FIG. 6 is a timing diagram showing an example in which reception is continued by circulating around three channels.
FIG. 7 is a timing diagram showing an example in which a new channel is allocated by circulating around three channels.
FIG. 8 is a flowchart showing a processing procedure (new channel assignment processing) on the base unit side.
FIG. 9 is an explanatory diagram showing a channel information sharing method and a new channel assignment timing between a slave unit and a master unit.
FIG. 10 is a timing chart showing an example in which a monitor channel is provided and a standby operation is performed by circulating around three channels.
[Explanation of symbols]
2 Slave unit (base unit) antenna 4 Antenna switch 6 Radio reception unit 8 Demodulation unit 10 Reception level detection unit 12 Sensor unit installed inside or outside the slave unit (base unit) 14 Transmission / reception control unit 16 Modulation unit 18 Wireless transmission Part

Claims (6)

In a wireless communication system that performs communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units,
The base unit is
There is provided means for circulating a plurality of channels used for communication set in advance and a monitor channel and receiving a signal transmitted from the slave unit while monitoring a line state of an empty channel by the monitor channel. A wireless communication system. In a wireless communication system that performs communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units,
The base unit is
Means for circulating a plurality of channels and a monitoring channel used for communication set in advance, and receiving a signal transmitted from the slave unit while checking a circuit state of the channel under circulation;
When a channel with a poor line condition is found, a new channel with the best line condition is allocated according to the monitoring result of the monitoring channel instead of the bad channel, and the new channel and the plurality of channels are allocated. A wireless communication system comprising: means for continuing the circulation of channels other than the bad channel. The wireless communication system according to claim 2,
Packets of the master unit and the plurality of slave units include channel information used for communication,
The base unit is
A wireless communication system, wherein the new channel is allocated when the channel information matches for all packets of the parent device and the plurality of child devices. In a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units,
The parent device circulates a plurality of channels and a monitoring channel used for communication set in advance, and receives a signal transmitted from the child device while monitoring a line state of an empty channel by the monitoring channel. A wireless communication method. In a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master unit and a plurality of slave units,
The master unit is
Circulating a plurality of channels and a monitoring channel used for communication set in advance, and receiving a signal transmitted from the slave unit while checking a circuit state of the channel being cycled;
When a channel with a poor line condition is found, a new channel with the best line condition is allocated according to the monitoring result of the monitoring channel instead of the bad channel, and the new channel and the plurality of channels are allocated. A wireless communication method comprising: continuing the circulation for channels other than the bad channel among the channels. The wireless communication method according to claim 5, wherein
Packets of the master unit and the plurality of slave units include channel information used for communication,
The base station assigns the new channel when the channel information matches all the packets of the base unit and the plurality of slave units.

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