JP2004254048A - Method for constructing multihop radio network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To autonomously and efficiently determine the destination radio station for a connection, a frequency channel and a master station/slave station when a new station is connected and the radio environment changes. <P>SOLUTION: When a multihop radio network is constructed, whether the master station or the slave station is made to operate is determined when the power is supplied or when restarting. In addition, the interface part of a radio station already connected autonomously makes switching from the master station to the slave station or the slave station to the master station during communication. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for constructing a multi-hop network in a multi-hop wireless network in which a plurality of wireless stations relay packets using a plurality of channels.
[Prior art]
In recent years, services using a wireless LAN have been provided not only indoors such as offices and homes, but also outdoors such as train stations. In particular, outdoors, it is necessary to cover a wide area, and for that purpose, all access points need to be connected to a wired network. Therefore, many studies have been made on a multi-hop network that wirelessly relays between a gateway and an access point and between an access point and an access point.
[0002]
In a multi-hop wireless network, a wireless station normally has one interface unit and operates in an ad hoc mode defined by IEEE 802.11.
[0003]
However, in the above-described method, since only one frequency is used, there is a problem that interference increases and an access point having a large number of hops from the gateway greatly reduces throughput. As a method for solving this, a method has been proposed in which a cluster head is selected by using a plurality of frequencies to form a cluster (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2002-044003 A
[0005]
[Problems to be solved by the invention]
However, the method of selecting a cluster head by using a plurality of frequencies and forming a cluster does not describe a frequency selection method, a master station / slave station determination algorithm at the time of a new station or topology change, and the like. poor.
[0006]
The present invention has been made in view of the above points, and it is an object of the present invention to autonomously and efficiently determine a connection destination wireless station, a frequency channel, and a master station / slave station according to a change in a wireless environment when a new station is connected. It is an object of the present invention to provide a method for constructing a multi-hop wireless network capable of performing the above.
[0007]
[Means for Solving the Problems]
The present invention is configured by a plurality of wireless stations performing wireless communication and one or more frequency channels,
The wireless station has one or more wireless interface units (hereinafter, referred to as interface units),
The interface unit includes, for each interface unit, a function of a master station capable of communicating with one or more wireless stations in one wireless interface unit, and a function of a slave station capable of communicating only with the master station in one interface unit. And has a function of selecting a used frequency channel fixedly or autonomously,
A cluster is configured with the master station as a cluster head and a plurality of slave stations connected to the master station operating on the same frequency channel as the master station as cluster members, and input from an arbitrary interface unit of the radio station. In a method for constructing a multi-hop wireless network in a network capable of communicating packets with the same or wireless stations of the same cluster using different interface units or wireless stations of different clusters,
The radio station autonomously determines whether to operate in the master station or the slave station when the power is turned on or restarts, and belongs to the network.
[0008]
The present invention is configured by a plurality of wireless stations performing wireless communication and one or more frequency channels,
The wireless station has one or more wireless interface units,
The wireless interface unit includes, for each wireless interface unit, a function of a master station capable of communicating with one or more wireless stations in one wireless interface unit, and a slave station capable of communicating only with the master station in one interface unit And a function to select the used frequency channel fixedly or autonomously,
A cluster is configured with the master station as a cluster head and a plurality of slave stations connected to the master station operating on the same frequency channel as the master station as cluster members, and input from an arbitrary interface unit of the radio station. In a method for constructing a multi-hop wireless network in a network capable of communicating packets with the same or wireless stations of the same cluster using different interface units or wireless stations of different clusters,
An arbitrary interface unit that has already been connected autonomously switches from a master station or a slave station to a master station during communication.
[0009]
The present invention also provides a wireless network,
The new station WT0 performs carrier sense on all available frequency channels for a fixed time or on a predetermined frequency channel,
When there is a wireless station WT1 having an interface unit operating as a master station in the frequency channel f0 in the cycle, the new station WT0 operates as a slave station of the wireless station WT1 at the frequency f0 in the idle interface unit,
.., WTn-1, WTn with which the new station WT0 can directly communicate when there is no wireless station having an interface unit operating as a master station in the vicinity (where n is 11 or more). One station WTm (where m is a natural number of 11 or more and n or less) is selected from among natural numbers), and usable frequency channels f0, f1,..., Fp-1, and fp (where p is 0 or more) ), One frequency channel fq (where q is an integer of 0 or more and p or less) is selected from
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
The wireless station WTn operates as a slave station of the new station WT0 in the empty interface section on the frequency channel fq.
[0010]
Further, in the present invention, when there is a wireless station WT1 having an interface section operating as a master station on the frequency channel f0, the new station WT0 is a master station WT1 and a slave station belonging to the master station WT1. .., WTn (where n is a natural number of 10 or more) having an interface unit operating as
If all the measured values are equal to or greater than the fixed value R0, the new station WT0 operates as a master station in the empty interface section of the frequency channel f0,
The master station WT1 and the wireless stations WT10, WT11,..., WTn operate as the slave stations of the new station WT0 in the frequency channel f0 in the interface section used so far in the frequency channel f0.
When any one of the received powers from the wireless stations WT10, WT11,..., WTn is equal to or less than the fixed value R0, the WT0 operates as a slave station of the master station WT1 in an empty interface section of the frequency channel f0.
[0011]
Further, the present invention does not include a wireless station WT1 having an interface unit operating as a master station on the frequency channel f0, and the reception power having an interface unit operating as a slave station is a constant value R0. One of the wireless stations WT20, WT21,..., WTm (where m is a natural number of 20 or more) WTy (where y is a natural number of 20 or more and m or less) is a parent station to which the frequency channel f0 belongs. .., WTp (p is a natural number equal to or greater than 30) having the operating interface unit and the wireless stations WT30, WT31,..., WTp having the interface unit operating as a slave station belonging to the wireless station WTz. , When the received power from the wireless station WTy is equal to or greater than the constant value R0,
The wireless station WTy operates as a master station in the interface unit used so far at the frequency f0, and the new station WT0 operates as a slave station of the wireless station WTy in the idle interface unit.
The wireless station WTz and the wireless stations WT30, WT31,..., WTp operate as slave stations of the wireless station WTy in the interface unit used so far at the frequency f0,
When any one of the received powers from the wireless stations WT30, WT31,..., WTp is equal to or less than the fixed value R0, one of the wireless stations WT11,. A station is selected and one of the available frequency channels f0, f1,..., Fp-1, fp (where p is an integer of 0 or more) is a frequency channel fq (q is an integer of 0 or more and p or less). ) And select
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
The wireless station WTn operates as a slave station of the new station WT0 in the empty interface section on the frequency channel fq.
[0012]
In addition, the present invention provides a method in which a new station WT0 has a radio station WT1 having an interface section operating as a master station on a frequency channel f0 and a wireless station WT1 having an interface section operating as a slave station belonging to the frequency channel f0. .., WTn (where n is a natural number of 10 or more), and when the values are all equal to or greater than a fixed value R0,
.., WTn having an interface part belonging to the frequency channel f0 are transmitted to the radio station WT1 having the interface part operating as the master station in the frequency channel f0. Measuring the level R1 and the received signal level R2 from the new station WT0,
In the wireless station WT1 having the interface section operating as the master station in the frequency channel f0, and in all the wireless stations WT10, WT11,..., WTn having the interface section operating as the slave station belonging to the frequency channel f0, If the received signal level R2 does not fall below the received signal level R1,
The new station WT0 operates as a master station in an empty interface section on the frequency channel f0,
The wireless stations WT10, WT11,..., WTn operate as slave stations of the new station WT0 in the interface section which has been used so far at the frequency f0 in the frequency channel f0,
When at least one wireless station whose reception level R2 is lower than the reception level R1 exists,
The new station WT0 operates as a slave station of the wireless station WT1 in an empty interface section on the radio frequency channel f0.
[0013]
In addition, the present invention provides that the new station WT0 includes, in the frequency channel f0, all the slave stations WT10, WT11, , WTn (n is a natural number of 10 or more), and any one of the measured values is equal to or less than a fixed value R0, and the wireless station WT1 belongs to the frequency channel f0. , WTn, WT10, WT11,..., WTn, and all the received powers from the new station WT0 have a fixed value R0 or more. If there is a natural number equal to or more than n), the wireless station WTx operates as a master station in the interface section used so far at the frequency f0. And,
The new station WT0 and the wireless stations WT10, WT11, ..., WTx-1, WTx-1, WTx + 1, ..., WTn are slave stations of the wireless station WTx in the interface section which has been used at the frequency f0 in the frequency channel f0. Works as
The wireless station WT1 operates as a slave station of the wireless station WTx in the empty interface unit,
If all the received powers from the wireless stations WT1 and WT10, WT11,..., WTn and the new station WT0 are not equal to or greater than the fixed value R0,
The new station WT0 operates as a slave station of WT1 in the empty interface section on the frequency channel f0.
[0014]
The present invention also provides the wireless station WT1 having the interface unit operating as a master station to the slave stations WT10, WT11,..., WTn belonging to the frequency channel f0 among the slave stations WT10, WT11,. .., WTn and the wireless station WTx (where x is a natural number not less than 10 and not more than n) in which all the received powers from the new station WT0 are not less than a fixed value R0.
.., WTx−1, WTx + 1, WTn, which have an interface unit belonging to the frequency channel f0 on a wireless line WT1 having an interface unit operating as a master station on the frequency channel f0, Measure the reception signal level R3 from the station WT1 and the reception level R4 from the radio station WTx having an interface section operating as a slave station of the radio station WT1 at the frequency channel f0,
.., WTx−1, WTx + 1, WTn belonging to the frequency channel f0 of the wireless line WT1, when the reception level R4 does not fall below the reception level R3.
The wireless station WTx operates as a master station in the interface section that has been used so far at the frequency f0 in the frequency channel f0, the new station WT0 operates as a slave station of WTx in the empty interface section,
The wireless station WT1 and the slave stations WT10, WT11,..., WTx−1, WTx + 1, WTn operate as slave stations of the wireless station WTX in the interface section that has been used at the frequency f0 in the frequency channel f0.
If there is at least one radio station whose reception level R4 is lower than the reception level R3,
The new station WT0 operates as a slave station of the wireless station WT1 in an empty interface section on the frequency channel f0.
[0015]
In addition, the present invention provides that when the received power from the wireless station WTy is equal to or greater than a certain value R0,
The wireless stations WT30, WT31,..., WTp measure the reception level R5 from the wireless station WTz and the reception level R4 from the wireless station WTy, and operate as a slave station belonging to the frequency channel f0 to the wireless station WTz. If the reception level R6 does not fall below the reception level R5 in all the wireless stations WT30, WT31,.
The wireless station WTy operates as a master station in the interface section that has been used so far on the frequency channel f0 at the frequency f0,
The wireless station WT1 operates as a slave station of the wireless station WTy in the idle interface section,
The wireless stations WT30, WT31,..., WTp operate as slave stations of the wireless station WTy in the interface section which has been used at the frequency f0 in the frequency channel f0.
If there is at least one radio station whose reception level R6 is lower than the reception level R5,
The new station WT0 selects one of the wireless stations WT11,..., WTn−1, WTn with which direct communication is possible, and uses the available frequency channels f0, f1,..., Fp-1, fp (where p is One frequency channel fq (where q is an integer of 0 or more and p or less) is selected from among 0 or more integers),
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
The wireless station WTn operates as a slave station of the new station WT0 in the empty interface section on the frequency channel fq.
[0016]
Further, the present invention provides a radio station WTb having an interface section operating as a slave station when a radio station WTa having an interface section operating as a master station newly occurs on the frequency channel f0. Determines whether the WTc having an interface unit operating as a dependent master station can switch the dependent station, and if it is possible, switches the dependent wireless station.
[0017]
In addition, the present invention determines whether the wireless station WTb is a lower station of its own station,
If it is not a lower station, switch the subordinate station,
If it is a lower station, the slave station is not switched.
[0018]
Further, the present invention provides a wireless communication system in which the wireless station WTb is not a lower station of the wireless station WTa.
In the wireless station WTb, if the reception level R5 from the wireless station WTa does not fall below the reception level R6 from the wireless station WTc,
The wireless station WTb switches the dependent wireless stations from the wireless station WTc to the wireless station WTa,
When the reception level R5 is lower than the reception level R6, the slave station is not switched.
[0019]
Further, the present invention provides a method in which the wireless station WTb is not a lower station of the wireless station WTa.
The wireless station WTb measures the CIRa of the wireless link with the wireless station WTa and the CIRc of the wireless link with the WTc,
If CIRa does not fall below CIRc,
The wireless station WTb switches the dependent wireless stations from the wireless station WTc to the wireless station WTa,
If CIRa is lower than CIRc, the dependent wireless station is not switched.
[0020]
In addition, the present invention provides that, when a wireless station WTa having an interface unit operating as a master station is newly generated, the wireless station WTd having an interface unit operating as a master station on the frequency channel f0 becomes a wireless station WTd. Of all the wireless stations WT50, WT51,..., WTq (where q is a natural number of 50 or more) having an interface section operating as a slave station belonging to the frequency channel f0, the frequency channel f0 replaces WTd. Determine if there is a wireless station with an interface that can switch the master station,
When there is a wireless station WTr having an interface unit for switching to the master station, the wireless station WTr operates as a master station in an empty interface unit on the frequency channel f0,
The wireless stations WTd and the wireless stations WT50, WT51,..., WTr-1, WT + 1,..., WTq operate as slave stations of the wireless station WTr in the interface section which has been used at the frequency f0 in the frequency channel f0.
If there is no wireless station WTr having an interface that can be switched to the master station, the master station is not switched.
[0021]
As described above, in the present invention, in a multi-hop wireless network in a wireless LAN, by autonomously switching from a master station to a slave station or from a slave station to a master station from a reception result obtained by a wireless station performing carrier sense, The frequency channel can be used effectively.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a diagram for explaining the first embodiment of the present invention.
[0024]
In the present embodiment, the wireless network includes a plurality of wireless stations WT performing wireless communication and one or a plurality of frequency channels, and each wireless station WT illustrated in FIG. It has an interface unit. The wireless interface unit has a function of a master station capable of communicating with one or more wireless stations in one wireless interface unit and a function of communicating only with the master station in one interface unit. It has a function of a slave station and a function of fixedly or autonomously selecting a frequency channel to be used.
[0025]
The network shown in FIG. 1 comprises clusters A and B in which a master station is a cluster head and a plurality of slave stations connected to a master station operating on the same frequency channel as the master station are cluster members. This is a network in which packets input from an arbitrary interface unit of a wireless station can be communicated with wireless stations of the same cluster or wireless stations of different clusters using the same or different interface units.
[0026]
In the cluster A, the new station WT0 performs carrier sensing on all available frequency channels for a predetermined time or on a predetermined frequency channel. Here, if there is a wireless station WT1 having an interface unit operating as a master station on the frequency channel f0 in the cycle, the free interface unit of the new station WT0 will be It operates as a slave station of the wireless station WT1.
[0027]
On the other hand, when there is no wireless station having an interface section operating as a master station in the vicinity, the new station WT0 selects one station WTn from the wireless stations WT with which it can directly communicate, and uses the available frequency channel f0. , F1, ..., fp-1, fp (where p is an integer of 0 or more), and selects one frequency channel fq (where q is an integer of 0 or more and p or less), and the new station WT0 , Operate as a master station in the empty interface section on the frequency channel fq. The selected wireless station WTn operates as a slave station of the new station WT0 in the idle interface section on the frequency channel fq.
[0028]
[Second embodiment]
FIG. 2 is a diagram for explaining a second embodiment of the present invention.
[0029]
In the figure, as shown in a cluster C, when a carrier station WT1 having an interface unit operating as a master station on the frequency channel f0 exists as a result of performing carrier sense, the new station WT0 .., WTn (where n is a natural number of 10 or more) having an interface section operating as a master station WT1 and a slave station belonging to the master station WT1. Measure.
[0030]
If the measured values are all equal to or greater than the fixed value R0, the new station WT0 operates as a master station in the free interface section of the frequency channel f0, as shown in cluster D of FIG. , WT11,..., WTn operate as slave stations of the new station WT0 in the interface section used so far in the frequency channel f0.
[0031]
When any one of the received powers from the wireless stations WT10, WT11,. Operate.
[0032]
[Third Embodiment]
FIG. 3 is a diagram for explaining a third embodiment of the present invention.
[0033]
In the figure, as a result of performing carrier sense in cluster E, there is no wireless station WT1 having an interface unit operating as a master station on the frequency channel f0, and the interface unit operating as a slave station does not exist. WTm (where m is a natural number of 20 or more) among the wireless stations WT20,..., WTm (where m is a natural number of 20 or more) whose received power is equal to or more than a constant value R0 is a frequency channel f0 If the received power from the wireless station WTy is equal to or greater than the fixed value R0 in the wireless station WTz having an interface unit operating as a master station belonging to The new station WT0 operates as a master station in the interface section used by the wireless station W in the vacant interface section. y operates as a slave station.
[0034]
Further, the wireless station WTz operates as a slave station of the wireless station WTy in the interface unit used so far at the frequency f0.
[0035]
[Fourth Embodiment]
FIG. 4 is a diagram for explaining a fourth embodiment of the present invention.
[0036]
In the cluster G shown in the figure, the new station WT0 is a wireless station WT1 having an interface section operating as a master station on the frequency channel f0 and a wireless station WT1 having an interface section operating as a slave station belonging to the frequency channel f0. , WTn (where n is a natural number of 10 or more).
[0037]
If all the measured values are equal to or greater than the fixed value R0, the wireless station WT1 having the interface unit operating as the master station on the frequency channel f0 is connected to all the slave stations WT10 having the interface unit belonging to the frequency channel f0. , WTn measure the received signal level R1 from the wireless station WT1 and the received signal level R2 from the new station WT0.
[0038]
.., WTn that belong to the frequency channel f0 and have an interface part that operates as a child station. If the signal level R2 does not fall below the received signal level R1, as shown in cluster H, the new station WT0 operates as a master station in the free interface section of the frequency channel f0, and the wireless stations WT10, WT11,. Operates as a slave station of the new station WT0 in the interface section which has been used so far on the frequency channel f0 at the frequency f0.
[0039]
If at least one radio station whose reception level R2 is lower than the reception level R1 exists, the new station WT0 operates as a slave station of the radio station WT1 in the empty interface section of the radio frequency channel f0.
[0040]
[Fifth Embodiment]
FIG. 5 is a diagram for explaining a fifth embodiment of the present invention.
[0041]
In the cluster I shown in the figure, the new station WT0 has all the slave stations WT10, WT11,... Having the interface section belonging to the frequency channel f0 to the WT1 having the interface section operating as the master station in the frequency channel f0. , WTn (n is a natural number of 10 or more).
[0042]
If any one of the measured values is equal to or less than the fixed value R0, all the stations belonging to the frequency channel f0 are transmitted to the radio station WT1 having the interface unit operating as the master station in the frequency channel f0. , WTn among the stations WT10, WT11,..., WTn, and all the received powers from the new stations WT0 and WT10, WT11,. When a (natural number) exists, as shown in the cluster J, the wireless station WTx operates as a master station in the interface unit used so far at the frequency f0.
[0043]
The new station WT0 and the wireless stations WT10, WT11,..., WTx-1, WTx-1, WTx + 1,..., WTn are connected to the wireless station WTx in the interface used so far at the frequency f0 in the frequency channel f0. It operates as a slave station.
[0044]
The wireless station WT1 operates as a slave station of the wireless station WTx in the idle interface unit.
[0045]
If there is no wireless station whose received power from the wireless stations WT1 and WT10, WT11,..., WTn and the new station WT0 is equal to or greater than the constant value R0, the new station WT0 is It operates as a slave station of WT1.
[0046]
[Sixth Embodiment]
FIG. 6 is a diagram for explaining the sixth embodiment of the present invention.
[0047]
In the cluster K shown in FIG. 7, the wireless station WT1 having the interface unit operating as the master station is given the slave stations WT10, WT11 among all the slave stations WT10, WT11,..., WTn belonging to the frequency channel f0. ,..., WTn and the wireless station WTx (where x is a natural number not less than 10 and not more than n) in which all the received powers from the new station WT0 are equal to or more than the constant value R0, operate as the master station in the frequency channel f0. .., WTx-1, WTx + 1, WTn having an interface belonging to the frequency channel f0 to the wireless line WT1 having the interface, the received signal level R3 from the wireless station WT1. And a radio having an interface unit operating as a slave station of the radio station WT1 in the frequency channel f0 Measuring the reception level R4 from WTX.
[0048]
As a result of the measurement, if the reception level R4 does not fall below the reception level R3 in all the slave stations WT10, WT11,... WTx-1, WTx + 1, WTn belonging to the frequency channel f0 on the wireless line WT1, the cluster L As shown in (1), the wireless station WTx operates as a master station in the interface unit which has been used at the frequency f0 in the frequency channel f0, and the new station WT0 operates as a slave station of the WTx in the idle interface unit.
[0049]
Further, the wireless station WT1 and the slave stations WT10, WT11,..., WTx-1, WTx + 1, WTn operate as slave stations of the wireless station WTX in the interface unit which has been used at the frequency f0 in the frequency channel f0.
[0050]
When at least one radio station whose reception level R4 is lower than the reception level R3 exists, the new station WT0 operates as a child station of the radio station WT1 in the vacant interface section of the frequency channel f0.
[0051]
[Seventh Embodiment]
FIG. 7 is a diagram for explaining a seventh embodiment of the present invention.
[0052]
In the cluster M shown in the figure, when the received power from the wireless station WTy is equal to or greater than the fixed value R0, the wireless station WTm measures the received level R5 from the wireless station WTz and the received level R4 from the wireless station WTy, If the reception level R6 does not fall below the reception level R5 at all the wireless stations WTm having an interface unit operating as a slave station belonging to the frequency channel f0, the wireless station WTz performs the wireless communication as shown in the cluster N. The station WTy operates as a master station in the interface section that has been used so far on the frequency channel f0 at the frequency f0.
[0053]
The new station WT0 operates as a slave station of the wireless station WTy in the idle interface section.
[0054]
Further, the wireless station WTm operates as a slave station of the wireless station WTy in the interface section which has been used at the frequency f0 in the frequency channel f0.
[0055]
[Eighth Embodiment]
FIG. 8 is a diagram for explaining the eighth embodiment of the present invention.
[0056]
In the cluster O shown in the figure, when a radio station WTa having an interface section operating as a master station newly occurs in the frequency channel f0, the radio station WTb having an interface section operating as a slave station is set to the radio station WTb. It is determined whether the WTc having the interface unit that operates as the master station on which WTb is dependent can switch the dependent station from the WTc, and if it is determined that the dependent station can be switched, the dependent wireless station is set to the cluster P as shown in cluster P. Switch.
[0057]
The wireless station WTb determines whether the wireless station WTa is a lower station of its own station. If not, the wireless station WTb switches the dependent wireless station. If not, the wireless station WTb switches the dependent wireless station. Do not switch stations.
[0058]
In addition, when the reception level R5 from the wireless station WTa does not fall below the reception level R6 from the wireless station WTc in the wireless station WTb when the wireless station WTb is not a lower station of the wireless station WTa, the wireless station WTb switches from the wireless station WTc. When the reception level R5 is lower than the reception level R6, the slave station is not switched when the reception level R5 is lower than the reception level R6.
[0059]
If the wireless station WTb is not a lower station of the wireless station WTa, the wireless station WTb measures the CIRa of the wireless link with the wireless station WTa and the CIRc of the wireless link with the WTc, and the CIRa falls below the CIRc. If not, the wireless station WTb switches the dependent wireless station from the wireless station WTc to the wireless station WTa, and does not switch the dependent wireless station when CIRa is below CIRc.
[0060]
[Ninth embodiment]
FIG. 9 is a diagram for explaining the ninth embodiment of the present invention.
[0061]
In the cluster Q of FIG. 7, when a wireless station WTa having an interface unit operating as a master station newly occurs, the wireless station WTd having an interface unit operating as a master station on the frequency channel f0 is replaced by the wireless station WTd. Of all the wireless stations WT50, WT51,..., WTq (where q is a natural number of 50 or more) having an interface unit operating as a slave station belonging to the frequency channel f0, the frequency channel f0 replaces the WTd. It is determined whether there is a wireless station having an interface unit that can switch the master station. As a result, when there is a wireless station WTr having an interface unit that switches to the master station, the wireless station WTr operates as the master station in the vacant interface unit in the frequency channel f0 as shown in the cluster S.
[0062]
The wireless stations WTd and WT50, WT51,..., WTr-1, WTr + 1,..., WTq operate as slave stations of the wireless station WTr in the interface section which has been used at the frequency f0 in the frequency channel f0. I do.
[0063]
If there is no wireless station WTr having an interface that can be switched to the master station, the master station is not switched.
[0064]
【Example】
Hereinafter, examples of the present invention will be described.
[0065]
FIG. 10 is a flowchart of a series of operations when a new station is added according to one embodiment of the present invention.
[0066]
When a new station is added (step 101), carrier sensing is performed on the common frequency channel f0, and it is measured which mode of the master station / slave station is operating (step 102).
[0067]
If there is a wireless station operating as a master station (step 103, Yes) (... first embodiment), it is determined whether the new station can communicate with all slave stations. (Step 104, Yes) (... second embodiment), it is determined whether the RRSI has been improved in all the radio stations in the cluster, and if it has been improved (Step 105, Yes) (...) (Fourth embodiment) Switching between parent and child is performed (step 106), and operation is performed as a parent station (step 107).
[0068]
If there is a wireless station operating as a master station (step 103, yes) (... first embodiment), and if the new station cannot communicate with all slave stations (step 104, no), It is determined whether there is a slave station that can communicate with all the wireless stations in the cluster. If there is no slave station (step 108, no) (..., The fifth embodiment), it operates as a slave station (step 109).
[0069]
In addition, there is a wireless station operating as a master station (step 103, yes) (... first embodiment), and the new station can communicate with all slave stations (step 104, yes) (... In the second embodiment), if the RRSI has not been improved in all the radio stations in the cluster (step 105, no) (fourth embodiment), it operates as a slave station (step 109).
[0070]
If there is a wireless station operating as a master station (step 103, yes) (... first embodiment), and if the new station cannot communicate with all slave stations (step 104, no) ( In the second embodiment), if there is a slave station that can communicate with all the wireless stations in the cluster (step 108, Yes) (... the fifth embodiment), in all the wireless stations in the cluster It is determined whether the RRSI has been improved. If the RRSI has been improved (step 113, Yes) (..., The sixth embodiment), parent-child switching is performed (step 114), and the mobile station operates as a slave station (step 115). )
If there is a wireless station operating as a master station (step 103, yes) (... first embodiment), and if the new station cannot communicate with all slave stations (step 104, no) ( ... in the second embodiment), if there is a slave station that can communicate with all the wireless stations in the cluster (step 108, Yes) (... in the fifth embodiment), all the wireless stations in the cluster If the RRSI is not improved in step (step 113, no) (..., The sixth embodiment), it operates as a slave station (step 109).
[0071]
If there is no wireless station operating as a master station (step 103, no) (... First embodiment) and there is a slave station that can communicate with all wireless stations in the cluster (step 110, yes) (3rd Embodiment), it is determined whether the RRSI has been improved in all the radio stations in the cluster, and if the RRSI has been improved (Step 112, Yes) (... 7th Embodiment) ), Switching of parent and child is performed (step 114), and operation is performed as a child station (step 115).
[0072]
If there is no radio station operating as a master station (step 103, no) (... first embodiment) and there is no slave station that can communicate with all the radio stations in the cluster (step 110, no) ) (Third Embodiment), operates as a master station on a new channel (step 111).
[0073]
FIG. 11 is a flowchart of a series of operations in the existing station according to one embodiment of the present invention.
[0074]
If the existing station is operating as a master station (step 201), if a new station is added (step 202), it is determined whether the master station is adjacent. If the master station is adjacent (step 203). , Yes), if there is a slave station that can communicate with all the wireless stations in the cluster (step 204, yes) (... in the ninth embodiment), the parent / child switching is performed (step 205), It operates (step 206).
[0075]
If the master station is not adjacent (step 203, no), the current state is maintained (step 207).
[0076]
If the existing station is operating as a slave station (step 210) and a new station is added (step 211), it is determined whether the new station is a lower station of the own station and the new station is a lower station. In this case (step 212, Yes) (eighth embodiment), the current state is maintained (step 213) (... the eighth embodiment).
[0077]
If the existing station is operating as a slave station (step 210), a new station is added (step 211), and if the added new station is not a lower station of the own station (step 212, step 212). No), and if a master station whose RSSI has been improved compared to the current wireless station appears (step 214, Yes), the connected wireless station is switched back (step 215) (... in the eighth embodiment). ).
[0078]
If the existing station is operating as a slave station (step 210), a new station is added (step 211), and if the added new station is not a lower station of the own station (step 212, step 212). (No), and if no master station whose RSSI has been improved compared to the current wireless station does not appear (Step 214, No), the current state is maintained (Step 213) (... the eighth embodiment).
[0079]
If the existing station is operating as a slave station (step 210), a new station is added (step 211), and if the added new station is not a lower station of the own station (step 212, step 212). No), and if the CIR is improved compared to the current wireless station (step 216, yes), the wireless station to be connected is switched (step 215) (... the eighth embodiment).
[0080]
If the existing station is operating as a slave station (step 210), a new station is added (step 211), and if the added new station is not a lower station of the own station (step 212, step 212). No), and if the CIR is not improved compared to the current wireless station (step 216, no), the current state is maintained (step 213) (... the eighth embodiment).
[0081]
FIG. 12 shows a configuration of a multi-hop wireless network according to one embodiment of the present invention, and FIG. 13 shows a packet sequence according to one embodiment of the present invention.
[0082]
In FIG. 12, a wireless station having a gateway function to an external wired network is designated as WT1, and the wireless station WT1 operates as a master station on the frequency channel f1. Further, the wireless stations operating as slave stations of the wireless station WT1 are referred to as WT2, WT3, and WT4, and constitute a cluster T. The wireless stations WT1 to WT4 operate as master stations in the common frequency channel f0, and transmit advertisement packets at regular intervals.
[0083]
The newly started wireless station WT0 (hereinafter, a new station) first performs carrier sensing on the common frequency channel f0 (step 301), and determines which of the frequency channel used by the surrounding wireless stations and the master station / slave station. Or the power value of the propagation from the surrounding radio station or the like is received from the packet.
[0084]
After a lapse of time sufficient to receive the advertisement packet a sufficient number of times, the new station WT0 determines the connection destination radio station, the connection frequency channel, and the connection mode (master station or slave station) according to the algorithm shown in FIG. 10 ( Step 302). In this case, it is assumed that it is determined that the new station WT0 operates as the master station on the frequency channel f1, and the wireless stations WT1 to WT4 operate as slave stations of the new station WT0.
[0085]
Next, an assignment is once made to the connection destination wireless station WT1 on the common frequency channel f0 (step 303). After the connection, a connection request packet is sent to the wireless station WT1 (step 304).
[0086]
Further, the wireless station WT1 repeatedly transmits an indirect connection determination packet for a certain period. Upon receiving the connection request packet from the new station WT0, the wireless station WT1 changes the subordinate wireless stations WT2 to WT4 on the frequency channel f1, including a request to leave the wireless station WT1 and a request to belong to the new station WT0. A request packet is transmitted (step 305).
[0087]
The wireless stations WT2 to WT4 that have received the change request packet receive the connection determination packet from the new station WT0 on the frequency channel f0 (step 306), and check whether the received power from the new station WT0 or the CIR is equal to or more than a certain value. Is determined, and if it is possible to connect to the new station WT0, data indicating that the connection is possible is provided in the change response packet. If it is not possible to connect to the new station WT0, it is impossible to connect to the change response packet. Is transmitted and transmitted to the wireless station WT1 (step 307).
[0088]
The wireless station WT1 receives the change response packet from all the slave stations WT2 to WT4 of the own station, determines whether or not the request described in the connection request packet is possible, and if possible, sends a request to the new station WT0. Send a connection response packet. If it is impossible, a connection rejection packet is transmitted to the new station WT0 (step 308).
The wireless station WT1 that has received the connection response packet from the new station WT0 leaves the new station WT0 on the frequency channel f0 (step 309).
[0089]
After the new station WT0 leaves the wireless station WT1, the wireless station WT1 transmits to its subordinate wireless stations WT2 to WT4 a membership change packet indicating a request to leave the wireless station WT1 and to request membership to the new station WT0. The wireless stations WT2 to WT4, which have received the belonging change packet, leave the wireless station WT1 and wait on the frequency channel f1 as slave stations. On the other hand, the wireless station WT1 similarly stands by as a slave station on the frequency channel f1 (step 310).
[0090]
After leaving the wireless station WT1, the new station WT0 operates as a master station on the frequency channel f1 and transmits a beacon packet (step 311).
[0091]
Upon receiving the beacon packet from the new station WT0, the wireless stations WT1 to WT4 transmit an association request to the new station WT0, perform the association, and form a cluster U (step 312).
[0092]
Note that the present invention is not limited to the above-described embodiments and examples, and various modifications and applications are possible within the scope of the claims.
[0093]
【The invention's effect】
As described above, according to the present invention, when a new station is accommodated in the network, a new frequency channel is not allocated as much as possible, so that the frequency channel can be used effectively.
[0094]
Further, according to the present invention, a radio station already connected is connected to a channel and a radio station with higher radio link quality, so that a high quality radio network can be constructed.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment of the present invention.
FIG. 2 is a diagram for explaining a second embodiment of the present invention.
FIG. 3 is a diagram for explaining a third embodiment of the present invention.
FIG. 4 is a diagram for explaining a fourth embodiment of the present invention.
FIG. 5 is a diagram for explaining a fifth embodiment of the present invention.
FIG. 6 is a diagram for explaining a sixth embodiment of the present invention.
FIG. 7 is a diagram for explaining a seventh embodiment of the present invention.
FIG. 8 is a diagram for explaining an eighth embodiment of the present invention.
FIG. 9 is a diagram for explaining a ninth embodiment of the present invention.
FIG. 10 is a flowchart of a series of operations when a new station is added according to an embodiment of the present invention.
FIG. 11 is a flowchart of a series of operations in an existing station according to an embodiment of the present invention.
FIG. 12 is a configuration diagram of a multi-hop wireless network according to an embodiment of the present invention.
FIG. 13 is a packet sequence according to an embodiment of the present invention.
[Explanation of symbols]
WTa to WTd, WTp, WTq, WTr, WTm, WTn, WTy, WTz, WT0 to WT30 Radio stations
AU cluster

Claims (14)

It is configured by a plurality of wireless stations performing wireless communication and one or a plurality of frequency channels,
The wireless station has one or more wireless interface units (hereinafter, referred to as interface units),
The interface unit includes, for each of the interface units, a function of a master station capable of communicating with one or more wireless stations in one wireless interface unit, and a child station capable of communicating only with the master station in one interface unit. It has the function of a station and the function of fixedly or autonomously selecting the used frequency channel,
The master station is a cluster head, and a plurality of slave stations connected to the master station operating on the same frequency channel as the master station are configured as cluster members, and
In a method for constructing a multi-hop wireless network in a network capable of communicating with a wireless station of the same cluster or a wireless station of a different cluster using the same or a different interface unit, packets input from an arbitrary interface unit of the wireless station ,
The radio station comprises:
A method for constructing a multi-hop wireless network, comprising: determining whether to operate autonomously at a master station or a slave station at power-on or restart, and belonging to the network. It is configured by a plurality of wireless stations performing wireless communication and one or a plurality of frequency channels,
The wireless station has one or more wireless interface units,
The wireless interface unit includes, for each wireless interface unit, a function of a master station capable of communicating with one or more wireless stations in one wireless interface unit, and capable of communicating only with the master station in one interface unit With the function of a child station and the function of selecting the used frequency channel fixedly or autonomously,
The master station is a cluster head, and a plurality of slave stations connected to the master station operating on the same frequency channel as the master station are configured as cluster members, and
In a method for constructing a multi-hop wireless network in a network capable of communicating with a wireless station of the same cluster or a wireless station of a different cluster using the same or a different interface unit, packets input from an arbitrary interface unit of the wireless station ,
A method for constructing a multi-hop wireless network, comprising: autonomously switching from a master station or a slave station to a master station during communication in an arbitrary interface unit already connected. In the wireless network,
The new station WT0 performs carrier sense on all available frequency channels for a fixed time or on a predetermined frequency channel,
When there is a wireless station WT1 having an interface unit operating as a master station on the frequency channel f0 in the cycle, the new station WT0 operates as a slave station of the wireless station WT1 at the frequency f0 in the idle interface unit;
.., WTn-1, WTn with which the new station WT0 can directly communicate, where n is 11 or more. WTm (where m is a natural number equal to or greater than 11 and equal to or less than n) is selected from the available frequency channels f0, f1,..., Fp-1, and fp (where p is 0). One frequency channel fq (where q is an integer of 0 or more and p or less) from the following integers),
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
2. The method according to claim 1, wherein the wireless station WTn operates as a slave station of the new station WT0 in a free interface section on a frequency channel fq. When there is a wireless station WT1 having an interface unit operating as a master station on the frequency channel f0, the new station WT0 operates as the master station WT1 and a slave station belonging to the master station WT1. , WTn (where n is a natural number of 10 or more), and the reception power is measured from all the wireless stations WT10, WT11,.
When all the measured values are equal to or greater than the fixed value R0, the new station WT0 operates as a master station in the free interface section of the frequency channel f0,
The master station WT1 and the wireless stations WT10, WT11,..., WTn operate as slave stations of the new station WT0 in the interface section used so far in the frequency channel f0 in the frequency channel f0,
WTn operates as a slave station of the master station WT1 in a vacant interface section of the frequency channel f0 when any one of the received powers from the wireless stations WT10, WT11,. 3. The method for constructing a multi-hop wireless network according to 3. There is no wireless station WT1 having an interface unit operating as a master station on the frequency channel f0 around the wireless station WT20 and the reception power of the interface unit operating as a slave station is equal to or higher than a fixed value R0. , WT21,..., WTm (where m is a natural number not less than 20), and an interface unit in which one station WTy (where y is a natural number not less than 20 and not more than m) operates as a parent station belonging to the frequency channel f0. , And WTp (p is a natural number of 30 or more) having an interface unit operating as a slave station belonging to the wireless station WTz, and If the received power of is equal to or greater than the fixed value R0,
The wireless station WTy operates as a master station in an interface unit that has been used at the frequency f0 so far, and the new station WT0 operates as a slave station of the wireless station WTy in an empty interface unit.
The wireless station WTz and the wireless stations WT30, WT31,..., WTp operate as slave stations of the wireless station WTy in the interface unit used so far at the frequency f0,
When any one of the received powers from the wireless stations WT30, WT31,..., WTp is equal to or less than a fixed value R0, the wireless stations WT11,. From the available frequency channels f0, f1,..., Fp-1, fp (where p is an integer of 0 or more), and one frequency channel fq (q is 0 or more and p or less) Integer), and
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
4. The multi-hop wireless network construction method according to claim 3, wherein the wireless station WTn operates as a slave station of the new station WT0 in an empty interface unit on a frequency channel fq. The new station WT0 is connected to all the wireless stations WT10 having the interface section operating as a slave station belonging to the frequency channel f0 to the wireless station WT1 having the interface section operating as the master station on the frequency channel f0. WTn (where n is a natural number of 10 or more) is measured, and when all the values are equal to or more than a constant value R0,
.., WTn having an interface unit belonging to the frequency channel f0 are transmitted to the radio station WT1 having the interface unit operating as the master station in the frequency channel f0. Measuring the signal level R1 and the received signal level R2 from the new station WT0,
All the wireless stations WT10, WT11,..., WTn having an interface section operating as a slave station belonging to the frequency channel f0 are provided to the wireless station WT1 having an interface section operating as the master station in the frequency channel f0. In the above, when the received signal level R2 does not fall below the received signal level R1,
The new station WT0 operates as a master station in an empty interface section on the frequency channel f0,
The wireless stations WT10, WT11,..., WTn operate as slave stations of the new station WT0 in the interface section which has been used at the frequency f0 in the frequency channel f0.
When at least one radio station whose reception level R2 is lower than the reception level R1 exists,
5. The method according to claim 4, wherein the new station WT0 operates as a slave station of the wireless station WT1 in an empty interface section of the radio frequency channel f0. The new station WT0 has all the slave stations WT10, WT11,..., WTn having the interface unit belonging to the frequency channel f0 to the wireless station WT1 having the interface unit operating as the master station in the frequency channel f0. n is a natural number greater than or equal to 10), and any one of the measured values is equal to or less than a fixed value R0 and all the stations belonging to the frequency channel f0 to the wireless station WT1. , WTn among the slave stations WT10, WT11,..., WTn, and the wireless station WTx in which all the received powers from the new stations WT0 and WT10, WT11,. The following natural numbers)
The wireless station WTx operates as a master station in the interface unit used so far at the frequency f0,
The new station WT0 and the wireless stations WT10, WT11,... WTx-1, WTx-1, WTx + 1,. Operates as a child station of
The wireless station WT1 operates as a slave station of the wireless station WTx in an empty interface unit,
.., WTn and the new stations WT0, when there is no radio station whose received power is equal to or greater than a fixed value R0,
5. The method according to claim 4, wherein the new station WT0 operates as a slave station of the WT1 in an empty interface section of the frequency channel f0. .., WTn belonging to the frequency channel f0 among the slave stations WT10, WT11,..., WTn, and the wireless station WT1 having the interface section operating as the master station. When there is a wireless station WTx (where x is a natural number not less than 10 and not more than n) in which all received powers from the new station WT0 are equal to or more than a constant value R0,
.., WTx−1, WTx + 1, WTn having the interface unit belonging to the frequency channel f0 on the wireless line WT1 having the interface unit operating as the master station on the frequency channel f0. Measuring a reception signal level R3 from the radio station WT1 and a reception level R4 from the radio station WTx having an interface unit operating as a slave station of the radio station WT1 in the frequency channel f0;
.., WTx−1, WTx + 1, WTn belonging to the frequency channel f0 of the wireless line WT1, if the reception level R4 does not fall below the reception level R3,
The wireless station WTx operates as a master station in the interface section that has been used so far on the frequency channel f0 at the frequency f0, and the new station WT0 operates as a slave station of WTx in the idle interface section.
The wireless station WT1 and the slave stations WT10, WT11,..., WTx-1, WTx + 1, and WTn operate as slave stations of the wireless station WTX in the interface unit which has been used at the frequency f0 in the frequency channel f0. ,
If at least one radio station whose reception level R4 is lower than the reception level R3 exists,
The method for constructing a multi-hop wireless network according to claim 7, wherein the new station WT0 operates as a slave station of the wireless station WT1 in an empty interface unit in a frequency channel f0. If the received power from the wireless station WTy is equal to or greater than a fixed value R0,
, WTp measure the reception level R5 from the radio station WTz and the reception level R4 from the radio station WTy, and as a slave station belonging to the frequency channel f0 to the radio station WTz. When the reception level R6 does not fall below the reception level R5 in all the wireless stations WT30, WT31,.
The wireless station WTy operates as a master station in the interface section that has been used so far on the frequency channel f0 at the frequency f0,
The wireless station WT1 operates as a slave station of the wireless station WTy in an empty interface unit,
The wireless stations WT30, WT31,..., WTp operate as slave stations of the wireless station WTy in the interface section that has been used so far on the frequency channel f0 at the frequency f0,
When there is at least one wireless station whose reception level R6 is lower than the reception level R5,
The new station WT0 selects one of the wireless stations WT11,..., WTn-1, WTn with which direct communication is possible, and uses the available frequency channels f0, f1,..., Fp-1, fp (where p Selects one frequency channel fq (where q is an integer of 0 or more and p or less) from among 0 or more integers)
The new station WT0 operates as a master station in an empty interface section on the frequency channel fq,
6. The multi-hop wireless network construction method according to claim 5, wherein the wireless station WTn operates as a slave station of the new station WT0 in an empty interface unit on the frequency channel fq. In the frequency channel f0, when a wireless station WTa having an interface unit operating as a master station newly occurs, the wireless station WTb having an interface unit operating as a slave station depends on the wireless station WTb. The multi-hop wireless network construction according to claim 1, wherein it is determined whether the WTc having the interface unit operating as the master station can switch the slave station, and if it is determined that the slave station can be slaved, the slave station is switched. Method. The wireless station WTb determines whether the wireless station WTa is a lower station of its own,
If it is not a lower station, switch the subordinate station,
11. The multi-hop wireless network construction method according to claim 10, wherein the subordinate station is not switched when the station is a lower station. When the wireless station WTb is not a lower station of the wireless station WTa,
In the wireless station WTb, when the reception level R5 from the wireless station WTa does not fall below the reception level R6 from the wireless station WTc,
The wireless station WTb switches a dependent wireless station from the wireless station WTc to the wireless station WTa,
12. The multi-hop wireless network construction method according to claim 11, wherein when the reception level R5 is lower than the reception level R6, the dependent radio station is not switched. If the wireless station WTb is not a lower station of the wireless station WTa,
The wireless station WTb measures a CIRa of a wireless link with the wireless station WTa and a CIRc of a wireless link with the WTc,
If CIRa does not fall below said CIRc,
The wireless station WTb switches a dependent wireless station from the wireless station WTc to the wireless station WTa,
12. The multi-hop wireless network construction method according to claim 11, wherein when the CIRa is lower than the CIRc, the dependent wireless station is not switched. When a wireless station WTa having an interface unit operating as a master station newly occurs, the wireless station WTd having an interface unit operating as a master station on the frequency channel f0 belongs to the frequency channel f0 of the wireless station WTd. , WTq (where q is a natural number of 50 or more) among the wireless stations WT50, WT51,..., WTq having an interface unit operating as a slave station, which can switch the master station instead of WTd in the frequency channel f0. Determine if there is a wireless station with an interface part,
When there is a wireless station WTr having an interface unit for switching to the master station, the wireless station WTr operates as a master station in an empty interface unit on the frequency channel f0,
The wireless stations WTd and the wireless stations WT50, WT51,..., WTr-1, WTr + 1,. Work,
10. The multi-hop wireless network construction method according to claim 1, wherein the master station is not switched when there is no wireless station WTr having an interface unit that can be switched to the master station.

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