JP2004147124A - Method and system for radio communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make devices small-sized and low-cost, to improve the tolerance to jamming waves, and to realize reduction of power consumption in a method and a system for radio communication which share a plurality of narrow-band radio channels to perform communication. <P>SOLUTION: A master machine patrols a plurality of preliminarily set narrow-band channels 2, 5 and 9 for use in communication to receive signals transmitted from slave machines while checking line states of channels being patrolled. When finding that the channel 5 is in an adverse line state, the master machine assigns a new channel 7 instead of the channel 5 to continue patrolling channels 7, 2 and 9. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD 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 master and a plurality of slaves.
[0002]
[Prior art]
In a wireless communication system, a control channel and a communication channel are used as communication channels. The control channel is used for making a communication request, setting a communication channel, and the like, and the communication channel is used for transmitting and receiving data to be actually exchanged.
[0003]
For example, when the master unit (base station) wants to obtain information from the slave unit (terminal), it transmits a transmission request and a communication channel number to the slave unit using the control channel, and then transmits the communication channel number from the slave unit. Wait for transmission data. The slave unit monitors the control channel at certain intervals (every several seconds) to check for a transmission request from the master unit, and when there is a transmission request, starts transmission on the specified communication channel. And so on, both channels are used. In the case of such a wireless communication system using a control channel, there is an advantage that the master unit can arbitrarily set a communication channel.
[0004]
A communication system using a control channel may be used in a simple wireless system using a specific low power standard or the like. Since 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 interfering waves or channels used by other systems This is because it is very effective that the setting can be made.
[0005]
On the other hand, a simple wireless device attached to, for example, a fire alarm or a gas meter is required to operate on a yearly basis with several dry batteries, and therefore, it is required to minimize power consumption. In the above-mentioned method using the control channel, a large amount of power is consumed in addition to transmitting and receiving the data originally intended to be transmitted and received through the communication channel, and thus a large amount of power is consumed. It is difficult to do. Therefore, by setting a communication channel number in advance (fixed channel assignment) at the time of system installation and the like, and always keeping the master unit in the receiving state, and adopting a system configuration in which the slave unit performs transmission at an arbitrary timing, Attempts have been made to reduce power consumption.
[0006]
However, although power is saved in this system configuration, the communication channel number is fixed, so communication may be interrupted if there is an interference wave or radio waves from other communication systems in the set channel. There is.
[0007]
As a method for solving this problem due to an interference wave or the like, a channel cycling method in which a plurality of channels are applied to the above 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 the plurality of channels and performs transmission, and the master unit circulates the plurality of channels in time and transmits from the slave unit. This is a method of waiting for a transmission signal.
[0008]
By using this channel cycling method, the slave unit can select a channel having a good line condition from a plurality of set channels, thereby avoiding the use of a channel where interference waves or radio waves of other communication systems exist. Accuracy can be improved.
[0009]
In addition, as another wireless communication system, based on the asymmetric circulation method using multiple communication channels, the use status of all channels is regularly monitored with high time resolution using a broadband digital receiver as a master unit. There is a configuration in which a communication channel is changed when an interference wave is detected, so that only a communication channel with less competition or interference with other systems can be used at all times (see Patent Document 2).
[0010]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H2-121093
[Patent Document 2]
JP 2002-300630 A
[Problems to be solved by the invention]
In the above-described channel cycling method (Patent Literature 1), since a plurality of set channels are fixed, when an interference wave is present in any of the set channels, the channel cannot be used because the channel cannot be used. Channel number is reduced. That is, the interference wave resistance of the system is low. 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 master unit to reliably receive the transmission signal from the slave unit, it is necessary to add a signal detection bit (preamble) for the cyclic cycle time of the master unit to the head of the transmission signal of the slave unit. Since the cycle time of the parent machine is proportional to the set number of channels, the preamble length in one complete cycle is also proportional to the set number of channels. Therefore, as the number of cyclic channels increases, the transmission time of the slave unit increases, which leads to an increase in power consumption. On the other hand, since the number of channels to be set must be reduced in order to prevent an increase in power consumption, it is impossible to avoid the above-described problem that the interference wave resistance is reduced.
[0014]
Further, in the system in which the communication channel is changed in response to the detection of an interfering wave based on the above-described non-stationary circulation method (Patent Literature 2), the above-described problem due to the channel cycling method can be avoided, but the base station uses a wideband digital Since a receiver is required, there is a problem that it is difficult to reduce the size and cost of the device.
[0015]
Therefore, an object of the present invention is to reduce the size and cost of the device without requiring a broadband digital receiver in the master device, and to prevent interference by making it possible to arbitrarily change the communication channel without using a control channel. An object of the present invention is to provide a communication system and a method that can achieve both improvement in wave resistance and reduction in power consumption.
[0016]
[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 master and a plurality of slaves, the master is set in advance. Circulating through a plurality of channels used for the communication, means for receiving a signal transmitted from the slave unit while checking the line state of the circulating channel, and when a channel with a bad line state is found, A wireless communication system, comprising: means for allocating a new channel in place of the bad channel, and for continuing the tour of the new channel and channels other than the bad channel among the plurality of channels. Carried out.
[0017]
According to another aspect of the present invention, in a wireless communication system that performs communication by sharing a plurality of narrowband channels between a master and a plurality of slaves, the master includes a plurality of slaves used for predetermined communication. A wireless communication system comprising means for circulating through a channel 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. Carried out.
[0018]
According to another aspect of the present invention, in a wireless communication system that performs communication by sharing a plurality of narrowband channels between a master and a plurality of slaves, the master includes a plurality of slaves used for predetermined communication. Means for circulating through the channel and the monitoring channel, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel; and Instead, a new channel having the best line condition is allocated according to the monitoring result of the monitoring channel, and the cycling continues with respect to the new channel and channels other than the bad channel among the plurality of channels. And a wireless communication system comprising:
[0019]
Here, the packets of the master unit and the plurality of slave units include channel information used for communication, and the master unit has determined that the channel information matches all of the packets of the master unit and the plurality of slave units. Sometimes, it is preferable to allocate the new channel.
[0020]
In order to achieve the above object, 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 and a plurality of slaves, Circulating through a plurality of channels used for the set communication, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel; and Allocating a new channel in place of the bad channel, and continuing the tour for the new channel and channels other than the bad channel among the plurality of channels. Was carried out.
[0021]
According to another aspect of the present invention, in a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master and a plurality of slaves, the master includes a plurality of slaves used for predetermined communication. A wireless communication method is implemented, in which a signal transmitted from the slave unit is received while circulating through a channel and a monitoring channel, and monitoring a line state of an empty channel using the monitoring channel.
[0022]
According to another aspect of the present invention, in a wireless communication method for performing communication by sharing a plurality of narrowband channels between a master and a plurality of slaves, the master includes a plurality of slaves used for predetermined communication. Circulating through the channel and the monitoring channel, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel; and Instead, a new channel having the best line condition is allocated according to the monitoring result of the monitoring channel, and the cycling continues with respect to the new channel and channels other than the bad channel among the plurality of channels. And a wireless communication method comprising the steps of:
[0023]
Here, the packets of the master unit and the plurality of slave units include channel information used for communication, and the master unit has determined that the channel information matches all of the packets of the master unit and the plurality of slave units. Sometimes, it is preferable to allocate the new channel.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment in which the present invention is applied to a system using a specified low power standard will be described below with reference to the drawings.
(1st Embodiment)
The wireless communication system according to the present embodiment includes one master unit and a plurality of slave units. The same configuration can be used for the parent device and the child device.
[0025]
As will be described later, the master unit circulates through a plurality of channels used for the set communication, and receives a signal transmitted from the slave unit while checking the line state of the circulating channel. Then, when a channel with a bad line condition is found, a new channel is allocated in place of the bad channel, and the continuation of the new channel and another channel (a channel other than the channel with a bad line condition among a plurality of channels) is continued. I do.
[0026]
In the slave unit (or master unit) of FIG. 1, 2 is a slave unit (master unit) antenna, 4 is an antenna switch, 6 is a wireless reception unit, 8 is a demodulation unit, 10 is a reception level detection unit, and 12 is a slave unit ( Reference numeral 14 denotes a transmission / reception control unit, 16 denotes a modulation unit, 18 denotes a radio transmission unit, and 20 denotes a local oscillation unit. The operation of the slave unit and the master unit will be described later in detail. However, a lock sensor can be connected to the slave unit to transmit key locking / unlocking 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 always in a standby state, and the slave unit transmits at an arbitrary timing.
[0028]
In FIG. 2, the detection information from the lock sensor (not shown) is transmitted from the slave unit periodically (for example, once / 30 minutes), and the detection information from the lock sensor changes (for example, lock / release). Non-periodical transmission performed when a lock is detected). That is, (1) and (2) in this figure indicate periodic transmission, and (3) indicates non-periodic transmission.
[0029]
The slave unit performs processing according to a procedure according to the flowchart shown in FIG.
In step S1, an initial assignment channel is set. In step S2, it is determined whether a predetermined transmission condition is satisfied (for example, whether a regular time has elapsed).
[0030]
In step S3, carrier sense is performed sequentially from the smaller number of allocated channels to find an empty channel.
[0031]
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.
[0032]
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.
[0033]
In step S7, it is determined whether an acknowledgment (acknowledge: acknowledgment) has been received from the parent device within a predetermined time. If it is determined that no ack is received from the master unit, the channel used for transmission is excluded from the allocated channels in step S8. On the other hand, if it is determined that the ack has been received from the master unit, it is determined in step S9 whether or not the assigned channel has changed. If there is a change in the assigned channel, a process 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.
The master unit circulates through the set channels while temporally changing the channel setting for the local oscillator 20 (selecting the reception frequency F in step S401 and setting the local oscillator to the frequency F in step S402). Do standby. For example, as shown in FIG. 5, the standby is performed by circulating through the set three channels 2, 5, and 9. “Reception” in FIG. 5 is a process of using the signal strength (RSSI) output from the reception level detection unit 10 to determine the presence or absence of a radio wave of the channel.
[0035]
When the RSSI exceeds a predetermined threshold, it is determined that there is a possibility that a signal (slave unit packet) from the slave unit exists in the channel, and reception is continued as shown in FIG. 6 (step S403). . In this continuation of reception, the received data is decoded, and first, a slave unit packet identification signal (sync word) is searched (step S404). If the sync word is detected, it is determined to be a slave unit packet and 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, if the RSSI exceeds a predetermined threshold but a sync word is not detected by a search for a certain period of time (basically the same time as the preamble length of the slave unit packet), radio waves of other communication systems or It is determined that the channel has an interference wave, and the interference count value of the channel is incremented by +1 (steps S403, S404, S406).
[0037]
If the interference count value is equal to or greater than the predetermined count value, it is determined that the channel state is not good, and an interference channel flag is set for the channel (steps S407 and S408).
[0038]
At the same time, the reception of the channel is stopped, and the waiting by the channel patrol is continued with the number of channels one channel less than the initial number. However, if an interfering channel is established during a tour with the minimum number of cyclic channels, the channel is continued to be visited to secure the lowest level of communication with the slave unit (steps S409 and S410).
[0039]
When there is a channel with the interference channel flag set, another new channel is assigned in place of this channel. This assignment is performed when the master unit receives a slave unit packet.
[0040]
For example, as shown in FIG. 7, when an interfering wave is first detected in channel 5 during the tour, channel 7 is newly added to empty channels 1, 3, 4, 6, 7, 8, and 10 instead. If an interference wave is detected in the channel 9 after the assignment, the channel 1 is newly assigned to the vacant channels 1, 3, 4, 6, 8, and 10 instead, and the tour is performed. continue. Which empty channel is to be a new channel is randomly assigned. If an interference wave is detected in the new channel, any other free channel is newly assigned instead.
[0041]
Note that the slave unit packet includes channel information set in the slave unit. The master unit stores the channel information of all the slave units as a table. As shown in the flowchart of FIG. 8, every time a slave unit packet is received, the master unit extracts the channel information from the slave unit packet and updates the channel information table. (Steps S801 and S802).
[0042]
If there is a channel with a disturbing channel flag set at the time when the master unit receives the slave unit packet, the channel information table of this slave unit is referred to, and the channel information of all the slave units is read by the master unit. If the channel coincides with the channel, a new channel is assigned (steps S804 and S805), and then the parent device cyclic channel is changed (step S806). The newly added channel is presented as channel information in an ack signal packet to the slave, and the channel information of the slave that has received the ack signal is updated to the new channel information.
[0043]
When the master unit receives the slave unit packet, even if there is a channel with the interference channel flag set, if the channel information of all slave units does not match the cyclic channel of the master unit, the channel change Since there is a possibility that a slave unit that cannot follow up may occur, wait until the channel information of all slave units match. When it is confirmed that the channel information of all the slaves matches the traveling channel of the master, a new channel is assigned.
[0044]
FIG. 9 shows a method of sharing channel information between the child device and the parent device and the new channel assignment timing described above. In FIG. 9, the slave unit packet has channel information of a channel to be used (here, three channels) at the leading end of the packet. Channel information is identified by hatching.
[0045]
FIG. 9 shows that, when an interference wave is detected in one channel at the left end of the operation channel 90 and the circulating of the interference channel is stopped, an interference wave is detected in one channel in the center of the operation channel 92 and the cycling of the interference channel is performed. 4 shows the assignment timing of a new channel when is stopped.
[0046]
In this way, each time the master unit receives one packet, it checks whether there is an interfering channel, and if there is an interfering channel, a new channel is assigned if the cyclic channels of all slave units are the same.
[0047]
(2nd Embodiment)
In the present embodiment, further, at the time of the above-described new channel assignment, in order to select a channel having a better line condition, a monitor channel is added to the cyclic channel used for communication, and the cyclic channel and the monitor channel are cyclically arranged. Thus, the line state of an empty channel can be monitored 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 three cyclic reception channels of cyclic channels 2, 5, and 9. The frequencies of the monitor channels are sequentially set to the empty channels, and the line states of all the empty channels are checked in order. One cycle is performed between the cyclic channels 2, 5, 9 and the monitor channel 1, and the monitor channel in the second cycle is the channel 3, and the available channels are sequentially monitored.
[0049]
Investigation of the line state corresponds to a process of determining the presence / absence of radio waves of the channel using the received signal strength (RSSI) output from the reception level detection unit 10 of the parent device, as in the case of the cyclic channel. However, even when the RSSI exceeds a predetermined threshold and it is determined that a radio wave is present, sync word detection is not performed. Since this channel is an empty channel and is not a channel used by a slave, reception continues. Never. Instead, when it is determined that the RSSI exceeds the predetermined threshold value and the radio wave is present, the interference count value is incremented by +1.
[0050]
This interference count value is stored in a table as a line state of an empty channel, and a channel with a good line state can be assigned by selecting a channel having the minimum interference count value during a cyclic channel assignment.
[0051]
Note that this embodiment can be implemented in combination with the first embodiment.
[0052]
【The invention's effect】
As described above, according to the wireless communication system and method according to the present invention, the channel state of a channel is checked by circulating through a plurality of channels without requiring a broadband digital receiver in a master unit, and a new channel is used instead of a channel having a poor line state. Since allocated channels are allocated, the size and cost of the apparatus can be reduced. In addition, without using a control channel, a plurality of channels used for communication set in advance are circulated, and a communication channel having an interference wave can be arbitrarily changed to another channel, thereby improving interference immunity. There is an effect that both reduction in power consumption can be achieved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a master unit or a slave unit used in a wireless communication system according to the present invention.
FIG. 2 is a diagram illustrating a communication timing between a master unit and a slave unit in the wireless communication system according to the present invention.
FIG. 3 is a flowchart illustrating a processing procedure on the slave device side.
FIG. 4 is a flowchart showing a processing procedure on the parent device side (interruption channel cyclic stop processing).
FIG. 5 is a timing chart showing an example of performing a standby by circulating through three channels.
FIG. 6 is a timing chart showing an example in which reception is continued by circulating through three channels.
FIG. 7 is a timing chart showing an example in which a new channel is allocated by circulating through three channels.
FIG. 8 is a flowchart showing a processing procedure (new channel assignment processing) on the parent device side.
FIG. 9 is an explanatory diagram showing a method of sharing channel information between a child device and a parent device and a new channel assignment timing.
FIG. 10 is a timing chart showing an example in which a monitor channel is provided and three channels are circulated for standby.
[Explanation of symbols]
2 slave unit (base unit) antenna 4 antenna switch 6 wireless reception unit 8 demodulation unit 10 reception level detection unit 12 sensor unit 14 installed inside or outside the slave unit (master unit) transmission / reception control unit 16 modulation unit 18 wireless transmission Department

Claims (8)

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 is
Means for circulating through a plurality of channels used for communication set in advance, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel,
Means for allocating a new channel in place of the bad channel when the channel having the bad channel condition is found, and continuing the tour for the new channel and the channels other than the bad channel among the plurality of channels. A wireless communication system comprising: 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 is
Means for circulating through 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 the line state of an empty channel using the monitor channel. A wireless communication system, comprising: 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 is
Means for circulating through 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 the line state of the circulating channel;
When a channel having the bad line condition is found, a new channel having the best line condition is assigned in place of the bad channel according to the monitoring result of the monitoring channel, and the new channel and the plurality of channels are assigned. Means for continuing a tour with respect to channels other than the bad channel among the channels. The wireless communication system according to claim 1 or 3,
The packets of the master unit and the plurality of slave units include channel information used for communication,
The master unit is
The wireless communication system according to claim 1, wherein the new channel is assigned when the channel information matches all of the packets of the master unit and the plurality of slave units. In a wireless communication method for performing communication by sharing a plurality of narrowband channels between a parent device and a plurality of child devices,
The master unit, circulating through a plurality of channels used for communication set in advance, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel,
When a channel with a bad line condition is found, assigning a new channel in place of the bad channel, and continuing the tour for the new channel and the channels other than the bad channel among the plurality of channels; A wireless communication method comprising: In a wireless communication method for performing communication by sharing a plurality of narrowband channels between a parent device and a plurality of child devices,
The master unit circulates through a plurality of channels used for communication set in advance and a monitoring channel, and receives a signal transmitted from the slave unit while monitoring a line state of an empty channel using the monitoring channel. A wireless communication method, comprising: In a wireless communication method for performing communication by sharing a plurality of narrowband channels between a parent device and a plurality of child devices,
The parent machine,
Circulating through a plurality of channels and monitoring channels used for communication set in advance, receiving a signal transmitted from the slave unit while checking the line state of the circulating channel;
When a channel having the bad line condition is found, a new channel having the best line condition is assigned in place of the bad channel according to the monitoring result of the monitoring channel, and the new channel and the plurality of channels are assigned. Continuing the tour for channels other than the bad channel among the channels. The wireless communication method according to claim 5, wherein
The packets of the master unit and the plurality of slave units include channel information used for communication,
The wireless communication method, wherein the master unit allocates the new channel when the channel information matches all the packets of the master unit and the plurality of slave units.

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