JP6459508B2 - Wireless communication apparatus and control method thereof - Google Patents

Description

  The present invention relates to a wireless communication apparatus and a control method thereof.

  In order to increase the frequency usage efficiency, research on cognitive radios that are temporarily used by recognizing and recognizing so-called white spaces that are not used geographically or temporally by radio license holders is underway. . In cognitive radio, a technique for dynamically allocating frequencies is required. For example, it has been proposed to use information relating to the frequency usage status of existing peripheral wireless communication systems (primary users). There has also been proposed a method using a database having a function of calculating an available frequency for each position and time. In addition, a frequency selection method has been proposed in which a frequency is dynamically allocated to a wireless communication terminal (secondary user) using a spectrum sensing function possessed by the wireless communication terminal. Here, the frequency used for reception and transmission is also referred to as “channel”.

  When there are a plurality of cognitive radio networks that do not exchange information with each other, interference (collision) may occur when two or more radio networks use the same channel. If a wireless network detects interference, one of the wireless networks must switch channels to avoid the interference. At this time, a plurality of wireless networks may simultaneously select the same channel, and interference may occur again. A device to avoid such re-interference is required.

  For example, in Patent Document 1, when a plurality of radio base stations detect interference, each base station sets a random delay time so that channel switching does not occur simultaneously. The occurrence of re-interference can be avoided by shifting the channel switching timing for each base station.

JP 2009-523360 A

  However, the method of Patent Document 1 has a problem that the order of channel reselection becomes random. In other words, the right to continue using a channel that a wireless network is currently using has not been considered. For example, it is assumed that a new wireless network is created where one wireless network is using a certain channel, the same channel is used, and interference occurs. In this case, the priority to use the channel should be given to the previously used wireless network. That is, it is desirable to give the priority to continue using the channel in consideration of the communication status of the wireless network involved.

  The present invention has been made in view of the above problems, and provides a method for arbitrating a channel in consideration of the priority to continue using the currently used channel when a plurality of wireless networks interfere. It is aimed.

  In order to solve the above problems, a wireless communication apparatus according to the present invention includes a communication state grasping unit that grasps a communication state of a wireless network to which the wireless communication apparatus belongs, and an interference that detects interference from a radio wave source other than the wireless network to which the wireless communication apparatus belongs. Detecting means; channel reselection execution reference setting means for setting a channel reselection execution reference for determining whether or not to execute channel reselection according to the interference based on the communication status; and the channel reselection Channel reselection execution means for executing channel reselection when the execution criterion is satisfied.

  The effect of the present invention is that when a plurality of wireless networks interfere, channel arbitration can be performed in consideration of the priority to continue using the currently used channel.

It is a block diagram which shows the radio | wireless apparatus of 1st Embodiment. It is a block diagram which shows the radio | wireless apparatus of 2nd Embodiment. 6 is a flowchart illustrating an operation of the wireless device according to the second embodiment. It is a block diagram which shows the radio | wireless apparatus of 3rd Embodiment. 12 is a timing chart illustrating an operation of the wireless device according to the third embodiment. It is a block diagram which shows the radio | wireless apparatus of 4th Embodiment. It is a bar graph which shows the allowable interference amount of 4th Embodiment. It is a schematic diagram which shows the operation | movement A of 4th Embodiment. It is a schematic diagram which shows the operation | movement B of 4th Embodiment. It is a schematic diagram which shows the operation | movement C of 4th Embodiment. It is a schematic diagram which shows the operation | movement D of 4th Embodiment. It is a schematic diagram which shows the operation | movement E of 4th Embodiment.

Hereinafter, the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of the present invention. The radio apparatus 100 includes a communication status grasping unit 110, an interference detection unit 120, a channel reselection execution reference setting unit 130, and a channel reselection execution unit 140.

  The communication status grasping unit 110 grasps the communication status of the network to which it belongs.

  The interference detection unit 120 detects interference from a radio wave source other than the wireless network to which the interference detection unit 120 belongs.

  The channel reselection execution criterion setting unit 130 sets a channel reselection execution criterion when interference is detected based on the communication status grasped by the communication status grasping unit 110. When there are a plurality of wireless networks, the communication status basically differs from one network to another, so the channel reselection execution criteria also differ from one network to another. At this time, in consideration of the communication status, the wireless network determined to have a higher priority to continue using the channel is set so that the channel reselection execution timing is delayed when the same interference is detected.

  The channel reselection execution means 140 executes channel reselection when the channel reselection execution criteria are satisfied. As described above, when the same interference is detected, the higher the priority of the wireless network that continuously uses the current channel, the later the timing for executing channel reselection. In other words, the wireless network with lower priority first performs channel reselection, so that the wireless network with priority can continue to use the channel.

With the above configuration, it is possible to perform channel reselection in consideration of the priority for continuously using the channel that is being used by the wireless network.
(Second Embodiment)
FIG. 2 is a block diagram showing the second embodiment. In the present embodiment, details of each part of radio apparatus 100 will be described.

  The wireless device 100 is in a position to lead channel control in the wireless network to which the wireless device 100 belongs. Specifically, a base station, a wireless access point, a leader node in an ad hoc network, and the like.

  The communication status grasping unit 110 includes a channel continuous use time grasping unit 111, a traffic amount grasping unit 112, a node number grasping unit 113, a node position grasping unit 114, and an estimated throughput grasping unit 115. The communication schedule grasping means 116 and the transmission power grasping means 117 are also provided. Note that the grasping units 111 to 117 are examples, and the communication state grasping unit 110 does not necessarily include all the grasping units illustrated. Moreover, it is not restricted to what was illustrated. What is necessary is just to provide suitably according to the communication condition to consider.

  The channel continuous use time grasping means 111 grasps the time during which the wireless network to which it belongs continues to use the currently used channel.

  The traffic amount grasping means 112 grasps the traffic amount in the wireless network to which the wireless device 100 belongs. For example, the traffic amount of the own network is grasped from the amount of messages from other nodes that can be determined as the same network.

  The node number grasping means 113 grasps the number of nodes under the wireless network to which the node belongs.

  The node position grasping unit 114 grasps the position of the node under the wireless network to which the node position grasping unit 114 belongs. For example, it is possible to perform triangulation based on the strength of radio waves from a plurality of transmission sources with different positions, and to grasp the relative positions of itself and other networks. In addition, the relative movement speed can be grasped from the change of the relative position or the inclination of the change of the radio wave intensity.

  The estimated throughput grasping means 115 grasps the estimated throughput in the wireless network to which the estimated throughput belongs.

  The communication schedule grasping means 116 grasps the communication schedule of the wireless network to which it belongs. For example, in the case of time-division communication, it is grasped as the position of the time slot or quiet period allocated to each node within the frame period.

  The transmission power grasping means 117 grasps the transmission power used in the wireless network to which it belongs.

  The interference detection unit 120 includes an interference information transmission unit 121. The interference detection unit 120 generates interference information from the detected interference, and transmits the interference information from the interference information transmission unit 121 to the channel reselection execution unit 140.

  As a method for detecting interference, for example, there is a method using a transmission / reception schedule of a network to which the apparatus belongs. In this method, the radio apparatus 100 grasps the communication schedule of each node, and detects the radio wave of the use channel received at a timing deviating from the communication schedule as an interference radio wave. There is also a method in which information specific to each network is included in a transmission message, and a radio wave for which this information cannot be acquired is determined to be an interference radio wave.

  Further, a signal-to-noise ratio (SNR), which is a ratio between the signal radio field intensity S received by the wireless device 100 and the noise N when no signal is received, can also be used. In this method, for example, the normal SNR is first calculated from the intensity S of the signal radio wave estimated from the node position to be communicated and the noise N when no signal is received. Then, the SNR of the received radio wave is calculated, and when the SNR at the time of reception becomes smaller than the normal SNR, it is determined that the interference radio wave is mixed with N. In addition, when the bit error rate exceeds a predetermined threshold value, it is determined that the received radio wave is interfered. As mentioned above, although the example of the specific interference detection method was shown, the interference detection method is not limited to these examples, Arbitrary methods can be used.

  The channel reselection execution criterion setting unit 130 includes a communication status acquisition unit 131 and a channel reselection execution criterion transmission unit 132. The communication status acquisition unit 131 acquires the communication status grasped by the communication status grasping unit 110. Specifically, a parameter representing the communication status acquired by each grasping means (111, 112,...) Is acquired. The interference tolerance limit transmission unit 131 transmits the interference tolerance limit set by the interference tolerance limit setting unit 130 to the channel reselection execution unit 140.

  The channel reselection execution reference setting unit 130 sets an allowable interference limit based on the communication status acquired by the communication status acquisition unit 131. The channel reselection execution criterion is set so that the channel reselection timing of the wireless network in the communication state to be prioritized is later than that of the non-prioritized wireless network when the same interference is detected. That is, the setting is made so that the amount of interference allowed by the wireless network to be prioritized is increased. A specific channel reselection execution reference method will be described later. For example, the channel reselection execution reference method can be set by using, for example, the number of times interference is detected or the integral value of the time when the interference is received.

  The channel reselection execution unit 140 includes a channel reselection execution reference holding unit 141, an interference information holding unit 142, and an interference information resetting unit 143. The channel reselection execution criterion holding unit 141 holds the channel reselection execution criterion transmitted from the channel reselection execution criterion transmission unit 131. The interference information holding unit 142 holds the interference information transmitted from the interference information transmitting unit 121. Then, the channel reselection execution unit 140 executes channel reselection when the channel reselection execution criterion is satisfied. The interference information reset unit 143 resets the held interference information when it is determined that the interference has disappeared during the channel reselection operation. The determination that the interference has disappeared can be made on condition that no interference is detected for a predetermined time, for example.

  The channel to be reselected by the channel reselection execution unit 140 can be determined based on, for example, the channel occupation status obtained by environment recognition performed proactively or reactively and an arbitrary index. However, the present embodiment is not limited to the channel selection method of the channel reselection execution unit 140.

  FIG. 3 is a flowchart showing the operation of the wireless device.

  First, the communication status grasping means grasps the communication status (S1). Next, the channel reselection execution criterion setting means sets a channel reselection execution criterion based on the communication status (S2). As described above, the channel reselection execution criterion is set such that the channel reselection timing is delayed as the wireless network has a higher priority to continue using the current channel. Next, the interference detection means detects interference (S3). Then, it is determined whether the channel reselection execution criteria are satisfied (S4). If the channel reselection execution criteria are satisfied (S4_Yes), it is checked whether there is interference (S5). If there is interference (S5_Yes), channel reselection is executed (S6). On the other hand, if there is no interference (S5_No), the interference information is reset (S7), and the process ends.

  If the channel reselection execution criterion is not satisfied in S4 (S4_No), it is determined whether there is interference within a predetermined time (S8). If there is interference within the predetermined time (S8_Yes), the process returns to S3 and the detection of interference is continued. If there is no interference within the predetermined time (S8_No), the interference information is reset (S7), and the process ends.

  With the above operation, when a plurality of wireless networks cause interference, a wireless network with a low priority for continuing to use the current channel first performs channel reselection. Since a high-priority wireless network has no source of interference, the current channel can be used continuously.

As described above, according to the present embodiment, when interference occurs, a radio network with low priority to continue using a channel first performs channel reselection. As a result, a wireless network having a high priority for continuous channel use can continue to use the channel.
(Third embodiment)
In the present embodiment, a specific example of channel reselection execution criteria will be described. Here, a method for setting the standby time from the detection of interference to the execution of channel reselection as the channel reselection execution reference will be described.

FIG. 4 is a block diagram showing radio apparatus 100 used in the present embodiment. The channel reselection execution reference setting unit 130 includes a standby time setting unit 133. The standby time setting unit 133 sets a standby time used when performing channel reselection. The other components, 110, 120, and 130 are the same as those in the first embodiment, and thus description thereof is omitted.
Next, a method for setting the standby time will be described. First, a function for calculating the standby time is created using each parameter representing the communication status as a variable. Then, weighting is performed according to the priority order of the parameters to be considered, the sum of each function is taken, and the final waiting time is determined. For example, the standby time ST calculated from the same channel continuous use time T can be expressed as the following equation, where A is the minimum standby time that does not depend on the communication status and f (T) is a function.

ST (T) = A + f (T) (1)
Similarly, the standby time based on the number of nodes N, traffic volume C, and network moving speed V is expressed by the following equation.

ST (N) = A + g (N) (2)
ST (C) = A + h (C) (3)
ST (V) = A + k (V) (4)
Using the above four formulas and the weighting coefficients w, x, y, z determined according to the priority order of parameters, the final standby time ST expressed by the following formula is determined.

ST = A + wf (T) + xg (N) + yh (C) + zk (V) (5)
As a specific example, a channel reselection execution criterion and operation when a first wireless network having a first wireless device and a second wireless network having a second wireless device interfere with each other will be described.

  The channel continuous use times of the first wireless network and the second wireless network are T1 and T2, respectively, the number of nodes is N1 and N2, the traffic amounts are C1 and C2, and the moving speeds are V1 and V2. And each waiting time ST1, ST2 is calculated using (5) Formula.

ST1 = A + wf (T1) + xg (N1) + yh (C1) + zk (V1) (6)
ST2 = A + wf (T2) + xg (N2) + yh (C2) + zk (V2) (7)
FIG. 5 is a timing chart showing operations of the first wireless device and the second wireless device. Here, although there is not much difference with respect to other parameters, the channel continuous use time is assumed to be longer in the second radio apparatus. That is, T1 <T2. From this, and equations (6) and (7), ST1 <ST2. For this reason, the first wireless device ends the standby time first (that is, satisfies the channel reselection execution criterion). Then, interference detection is performed, and channel reselection is performed in order to detect interference. On the other hand, the second wireless device ends the standby time after the first wireless device performs channel reselection. For this reason, no interference is detected after the end of the standby time. As a result, the interference information can be reset and the currently used channel can be continuously used. Note that if the standby time is extended indefinitely, if a plurality of wireless networks interfere with each other, there is a risk that none of the wireless networks will switch channels, so an upper limit value may be provided for the standby time.

  In the above description, the parameters indicating the communication status are four parameters of channel continuous use time, the number of nodes, the traffic volume, and the moving speed. However, the present invention is not limited to this, and various parameters may be combined. it can. In addition, the standby time is started when the interference is detected once. However, the standby time may be started on the condition that a predetermined number of interferences are detected or a predetermined number of interferences are detected within a predetermined period. .

As described above, according to the present embodiment, when two wireless networks interfere with each other, a low-priority wireless network that continues to use a channel performs channel reselection first. As a result, the wireless network with high priority can continue to use the channel being used. Note that only the difference in usage is that “a wireless network with low priority to continue using channels performs channel reselection first”, “a wireless network with high channel switching priority performs reselection first” Can also be expressed.
(Fourth embodiment)
In the present embodiment, a specific example using an allowable interference amount as a channel reselection execution criterion will be described.

  Prior to the description of the channel reselection execution criteria, the interference amount and the allowable interference amount will be described. First, the interference amount is a value indicating the amount of interference experienced by the communication apparatus, and is defined as an integrated value of interference. Specifically, for example, the number of times of interference, the total length of time in which interference was confirmed, the time-integrated received radio wave intensity of interference, the time change rate of the received radio wave intensity of interference, and the like can be used. .

  The allowable interference amount is a value serving as a reference for starting an operation in which the radio apparatus avoids interference when the interference amount reaches the value. That is, it is a specific example of channel reselection criteria. Here, the allowable interference amount is written as TI. When the number of times of interference is used as the amount of interference, the allowable amount of interference can be, for example, TI = n [times]. Further, when the interference amount is the sum of the time lengths when interference is confirmed, for example, the time length of the s-th interference can be expressed as TI = ΣIT (s) [sec]. Further, when the intensity of interference is represented by the received radio wave intensity R and the amount of interference is an integrated value thereof, it can be represented as TI = ∫Rdt [V / m · sec].

  Although three specific examples of the interference amount have been described above, the present invention is not limited to this example, and any index that quantitatively represents interference can be used.

  FIG. 6 is a block diagram illustrating a wireless device used in this embodiment. The channel reselection execution reference setting unit 130 includes an allowable interference amount setting unit 134. The allowable interference amount setting unit 134 sets the above-described allowable interference amount. The other components, 110, 120, and 130 are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, a method for setting the allowable interference amount will be described. The allowable interference amount TI can be set by the same method as in the third embodiment. Here, the allowable interference amount is calculated independently for each parameter representing the communication status, and the total allowable interference amount is defined as a sum obtained by weighting each allowable interference amount.

  First. A function for calculating the allowable interference amount using each parameter representing the communication status as a variable is created. Then, weighting is performed according to the priority order of the parameters to be considered, the sum of each function is taken, and the final allowable interference amount is determined. For example, the allowable interference amount TI calculated from the same channel continuous use time T can be expressed by the following equation, where l (T) is a function.

TI (T) = l (T) (11)
Similarly, the standby time based on the number of nodes N, traffic volume C, and network moving speed V is expressed by the following equation.

TI (N) = m (N) (12)
TI (C) = n (C) (13)
TI (V) = o (V) (14)
The final standby time ST expressed by the following equation is determined using the above four equations and the weighting coefficients p, q, r, and s determined according to the priority order of the parameters.

TI = A + pl (T) + qm (N) + rn (C) + so (V) (15)
As a specific example, a channel reselection execution criterion and operation when a first wireless network having a first wireless device and a second wireless network having a second wireless device interfere with each other will be described.

  The channel continuous use times of the first wireless network and the second wireless network are T1 and T2, respectively, the number of nodes is N1 and N2, the traffic amounts are C1 and C2, and the moving speeds are V1 and V2. And each waiting time ST1, ST2 is calculated using (5) Formula.

TI1 = pl (T1) + qm (N1) + rn (C1) + so (V1) (16)
TI2 = pl (T2) + qm (N2) + rn (C2) + so (V2) (17)
FIG. 7 is a bar graph showing the allowable interference amount TI between the first radio apparatus and the second radio apparatus. Here, it is assumed that the second wireless device has a larger number of nodes and more traffic. From this assumption and equations (16) and (17), TI1 <TI2. In other words, it can be said that the second wireless device does not release the channel being used even if it receives more interference than the first wireless device. Therefore, when the same amount of interference is incurred, the first radio apparatus reaches the allowable interference amount earlier (meeting the channel reselection criteria), and the channel reselection is executed first.

  As a specific operation example, a case where the second wireless device uses channel 1ch1 first, a new first wireless network is created there, and ch1 is also started to be used is illustrated. 8A, 8B, 8C, 8D, and 8E are schematic diagrams showing this operation in time series.

  First, the second wireless device in FIG. 8A uses ch1. In this state, no interference is detected. Further, the allowable interference amount TI increases according to the continuous use time.

  After that, it is assumed that the first wireless device newly starts using ch1. Then, as shown in FIG. 8B, interference occurs because the interference ranges 1 and 2 overlap. Assume that the amount of interference I experienced by both is the same. At this time, the interference amount I has not reached the allowable interference amount in both cases.

  Thereafter, the allowable interference amount increases with the passage of time, but since the first wireless device has a short continuous use time of ch1, the allowable interference amount is smaller than that of the second wireless device. That is, TI1 <TI2. For this reason, at a certain point in time, as shown in FIG. 8C, the interference amount I of the first radio apparatus reaches the allowable interference amount TI. Then, the first wireless device performs channel reselection. Here, it is assumed that ch2 is selected.

  FIG. 8D shows a state where the first wireless device has selected ch2. At this time, the second radio apparatus has not reset the interference amount I2. However, after the first wireless device selects ch2, the interference amount I2 has not increased.

  After that, when a predetermined time has elapsed, the second wireless device resets the interference amount I2 because there was no interference during the period. This state is shown in FIG. 8E.

  With the above operation, the first wireless device that does not have priority regarding the continued use of ch1 performs channel reselection to select ch2, avoids interference, and the second wireless device continues to use ch1. can do. If the allowable interference amount is increased without limitation, there is a possibility that none of the wireless networks will switch channels when a plurality of wireless networks interfere, and therefore an upper limit value may be provided for the allowable interference amount.

  As described above, according to the present embodiment, a large allowable interference amount can be set in a wireless network having a priority for continuous use of a channel. Thereby, it is possible to cause the wireless network having no priority to execute channel reselection first, and to continue using the channel being used by the wireless network having the priority.

  The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above embodiment. That is, the present invention can apply various modes that can be understood by those skilled in the art within the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Wireless apparatus 110 Communication condition grasping means 111 Channel continuous use time grasping means 112 Traffic amount grasping means 113 Node number grasping means 114 Node position grasping means 115 Estimated throughput grasping means 116 Communication schedule grasping means 117 Transmission power grasping means 120 Interference detecting means 121 Interference information transmission means 130 Channel reselection execution reference setting means 131 Communication status acquisition means 132 Channel reselection execution reference transmission means 133 Standby time setting means 134 Allowable interference amount setting means 140 Channel reselection execution means 141 Channel reselection execution reference holding means 142 interference information holding means 143 interference information resetting means

Claims (6)

Communication status grasping means for grasping at least the same channel continuous use time of the wireless network to which the wireless network belongs, as the communication status of the wireless network to which the wireless device belongs
Interference detecting means for detecting interference from a radio wave source other than the wireless network to which the device belongs;
Channel reselection execution criterion setting means for setting a channel reselection execution criterion for determining whether to perform channel reselection according to the interference based on the communication status;
Channel reselection execution means for executing channel reselection triggered by the channel reselection execution criteria being satisfied;
The waiting time from the reference time determined based on the detection of the interference until performing channel reselection, possess a wait time setting means for setting the channel reselection execution criteria based on the communication situation,
The wireless communication apparatus, wherein the standby time setting means sets the standby time longer as the continuous use time of the same channel is longer . An allowable interference amount setting means for setting the integrated value of the interference allowed before the channel reselection as the allowable interference amount in the channel reselection execution reference,
The allowable interference amount setting means determines the allowable interference amount based on the communication status;
The wireless communication apparatus according to claim 1. The integrated value of the interference is
Calculate using at least one of the number of times of detection of the interference, the sum of the time lengths in which the interference was detected, the integrated value of the radio field intensity of the interference for a predetermined time, and the time change rate of the radio field intensity of the interference,
The wireless communication apparatus according to claim 2 . The allowable interference amount setting means,
The longer the same channel continuous use time, the larger the allowable interference amount ,
The wireless communication apparatus according to claim 3. A wireless communication device according to any one of claims 1 to 4, a wireless communication terminal that performs wireless communication with the wireless communication device,
A wireless communication system comprising: As the communication status of the wireless network to which it belongs, at least grasp the same channel continuous usage time of the wireless network to which it belongs,
Detects interference from radio sources other than the wireless network to which it belongs,
A channel reselection execution criterion for determining whether to perform channel reselection according to the interference is set based on the communication status,
Execute channel reselection when the channel reselection execution criteria are satisfied,
Based on the detection of the interference, a waiting time from the reference time until the channel reselection is executed is set as the channel reselection execution reference based on the communication status,
The standby time setting means sets the standby time longer as the same channel continuous use time is longer.
A method for controlling a wireless communication apparatus.

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