JP5309405B2 - Dormant base station selection system, network side device, control method, and program - Google Patents

Description

  The present invention relates to a dormant base station selection system, a network side device, a control method, and a program. In particular, the present invention relates to a dormant base station selection system for selecting a base station to be paused from among a plurality of base stations, a network side device constituting a wireless communication network, a control method for controlling the network side device, and the network The present invention relates to a program for a side device.

  Wireless LAN (Local Area Network) based on IEEE (Institut of Electrical and Electrical Engineers) 802.11 plays an important role as a communication infrastructure for Internet access with the rapid spread of portable information terminals. The range in which the wireless LAN can be used has been expanded not only to homes and businesses but also to public spaces, etc., and APs (Access Points) to be installed continue to increase. Such network devices such as wireless LAN APs are always installed in an operating state in order to respond to a communication request from a terminal. Therefore, a reduction in power consumption along with an increase in the number of installed devices becomes a major issue. With existing APs, even when the terminal is not connected, beacon signals are transmitted at regular intervals, and measures to reduce the power consumption of the entire network, such as operation with the minimum necessary resources, are not sufficient. Absent.

  The conventional power saving measures for wireless LAN devices are mainly for the purpose of extending the connection time of terminals and nodes that operate on batteries, saving APs that must transmit beacon signals at regular intervals. Sufficient studies have not been made on countermeasures for power generation.

  Non-Patent Document 1 describes a technique for reducing the power consumption of a wireless system by suspending some base stations in an operating state based on the amount of traffic in an area.

  Non-Patent Document 2 describes a technique for periodically measuring a load on a base station and suspending a base station with a low load. In this technology, the change in the load of the surrounding base stations is detected by the three-dimensional radio wave based on the ray launching method so that the base station with the smallest change in the load of the surrounding base stations can be selected and paused. Prediction using propagation estimation.

  Patent Document 1 describes a technique for suppressing power consumption of slave base stations that are not required in a group base station configuration including a master base station and slave base stations.

JP 2005-354549 A

TNO, Vodafone, 3GPP S5-092949, 2009. "Power-saving control method for controlling coverage degradation due to base station outage", Taichi Kumagai, IEICE, 2010

  The technique described in Non-Patent Document 1 activates or sleeps each base station so that the ratio of base stations operating in a certain area is equal to that of other areas. Therefore, depending on the technique described in Non-Patent Document 1, if the traffic volume in each area is not uniform, base stations are operating wastefully in a certain area, and the number of base stations operating in a certain area is insufficient. Can happen.

  Further, the radio wave propagation estimation method described in Non-Patent Document 2 must be based on the premise that all the positions of the terminals can be grasped, and the hardware of the terminals of the current wireless system is changed. Many are needed and difficult to install.

  Further, the technique described in Patent Document 1 places a transition target slave base station in a dormant state when the number of remaining resources exceeds the number of remaining dormant state transition remaining resources. At that time, the wireless communication terminal that is wirelessly connected to the base station that has been in the dormant state is wirelessly connected to another base station. However, each wireless communication terminal is not always in a state where it can always be connected to a plurality of base stations by wireless communication. In addition, other base stations may not always be able to secure resources that can allow a wireless communication terminal to be newly connected by wireless communication. Therefore, depending on the technique described in Patent Document 1, as a result of putting a base station into a dormant state, a wireless communication terminal connected to the base station may be out of service area, or an extra load on other base stations. There is a risk of hanging.

  In order to solve the above problem, according to the first aspect of the present invention, there is provided a dormant base station selection system for selecting a base station to be paused from among a plurality of base stations, and a plurality of base stations constituting a radio communication network A plurality of network-side devices on the network side including the base station, and at least one of the plurality of network-side devices pauses the base station with the lowest channel utilization rate among the plurality of base stations. When a wireless communication terminal wirelessly connected to the base station is reconnected to another base station, a change in the channel utilization rate of each other base station is simulated, A base station selection unit for selecting a base station to be paused.

  According to the second aspect of the present invention, a network-side device constituting a wireless communication network, wherein a base station with the lowest channel utilization rate among a plurality of base stations is suspended and wireless communication connection is established with the base station Select a base station to be paused from multiple base stations after simulating changes in the channel utilization rate of each other base station when a wireless communication terminal is reconnected to another base station A dormant base station selection unit is provided.

  According to a third aspect of the present invention, there is provided a control method for controlling a network side device constituting a wireless communication network, wherein a base station having the lowest channel utilization rate among a plurality of base stations is suspended, and the base station When a wireless communication terminal that is wirelessly connected to a station is reconnected to another base station, a change in the channel utilization rate of each other base station is simulated and then suspended from a plurality of base stations And a base station selection stage for selecting a base station to be operated.

  According to a fourth aspect of the present invention, there is provided a program for a network side device constituting a wireless communication network, in which a network side device is suspended from a base station having the lowest channel utilization rate among a plurality of base stations. When a wireless communication terminal wirelessly connected to the base station is reconnected to another base station, a change in the channel utilization rate of each other base station is simulated, To function as a dormant base station selection unit that selects a base station to be paused.

  In addition, as described above, the summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  As is apparent from the above description, according to the present invention, it is possible to provide a radio system that satisfies the user's required quality while saving power.

It is a figure which shows an example of the utilization environment of the dormant base station selection system 100 which concerns on one Embodiment. 2 is a diagram illustrating an example of a block configuration of a station 110. FIG. It is a figure which shows an example of the block configuration of AP120. It is a figure which shows an example of the block configuration of AP control apparatus. It is a figure which shows an example of a connectable AP list in a table format. It is a figure which shows an example of a connection station list in a table format. It is a figure which shows an example of the operation | movement sequence of the station 110, AP120, and AP control apparatus 130. FIG. It is a figure which shows an example of the operation | movement flow of the dormant AP selection part. It is a figure which shows an example of the utilization environment of the dormant base station selection system 200 which concerns on other embodiment. It is a figure which shows an example of the block configuration of AP220. It is a figure which shows an example of the utilization environment of the dormant AP selection system 300 which concerns on other embodiment. It is a figure which shows an example of the block configuration of the channel notification apparatus 340.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and are combinations of features described in the embodiments. Not all are essential to the solution of the invention.

  In order to save power in the wireless LAN device, the inventor of the present invention shifts an AP that is not communicating to a low power consumption sleep state, and sends a wake-up signal from the terminal when communication is required. We are working on research and development to transmit and switch APs to operation.

  In the present invention, after the AP transitions to the sleep state, a method for keeping the sleep state for as long as possible and reducing the power consumption is examined. For this purpose, first, an AP control device that centrally manages a plurality of APs is introduced inside the network, and when a communication request directed to a terminal connected to a sleeping AP is detected, the associated AP of the terminal is activated. We propose a method to change to another AP.

  The inventor of the present invention newly developed an on-demand network access method that allows a wireless LAN terminal to switch an AP from a sleep state to an operating state by using a special signal, thereby A scheme that makes it possible to transition to a sleep state as appropriate has been proposed.

  The present invention is a system that aims to reduce the use of APs, reduce wastefulness, save power, and effectively use radio resources. Some existing APs have a sleep function for reducing power consumption. However, the AP according to the present invention actively transitions the AP to a sleep state depending on the communication status of surroundings, thereby reducing the power consumption of the network. Plan. Here, the AP has a Wake-up Receiver that can stand by with ultra-low power consumption, and when there is no data to be transmitted and received and communication becomes unnecessary, the AP automatically enters the sleep state within a range that does not affect the communication quality. Migrate to At the same time, the AP waits for a Wake-up signal from the station. When the AP receives a Wake-up signal from a station that desires communication using a Wake-up Receiver, the AP provides a wireless access environment based on a wireless LAN system after transitioning from a sleep state to an operating state. Thereby, it is possible to eliminate the application of the AP.

  FIG. 1 shows an example of a usage environment of a dormant AP selection system 100 according to an embodiment. The dormant AP selection system 100 is a system that selects an AP to be paused from a plurality of APs. In addition, the dormant AP selection system 100 may be an example of the “pause base station selection system” in the present invention.

  The dormant AP selection system 100 includes a plurality of stations 110a, b, c,... (Hereinafter collectively referred to as stations 110) and a plurality of APs 120a, b, c,. , And an AP control device 130. The station 110 may be an example of a “wireless communication terminal” in the present invention. The AP 120 and the AP control device 130 may be an example of the “network side device” in the present invention. The AP 120 may be an example of a “base station” in the present invention. The AP control apparatus 130 may be an example of “one network side apparatus” in the present invention.

  The station 110 is a computer provided with a wireless LAN adapter. The station 110 is communicatively connected to the AP 120 via a wireless LAN. The wireless LAN may be an example of “wireless communication” in the present invention.

  The AP 120 is a network device including a wireless LAN adapter, and operates as a bridge between the station 110 and a wired network. The AP 120 is communicatively connected to the station 110 via a wireless LAN. The AP 120 is connected for communication with the AP control device 130 via a wired network.

  The AP control device 130 is a device that controls the suspension of the AP 120. The AP control device 130 is communicatively connected to the AP 120 via a wired network.

  In the present embodiment, for the purpose of preventing the explanation from becoming complicated, a configuration in which the dormant AP selection system 100 includes one AP control device 130 will be described. AP controller 130 may be provided.

  FIG. 2 shows an example of a block configuration of the station 110. FIG. 5 shows an example of a connectable AP list in a table format. The station 110 includes a wireless communication unit 111 and a connectable AP list holding unit 112.

  The station 110 has the configuration shown in FIG. 2, and the connectable AP list holding unit 112 holds a connectable AP list as shown in FIG. 5, for example, and the connectable AP list passes through the wireless communication unit 111. And transmitted to the wirelessly connected AP 120.

  The connectable AP list includes information about the connectable AP 120, the channel information that can be communicated with the AP 120, and the received signal strength information of the beacon signal received from the connectable AP 120. Have. The channel information may be acquired from the result of a beacon signal scan performed when the station 110 connects to the AP 120, or the station 110 may periodically monitor all channels.

  FIG. 3 shows an example of the block configuration of the AP 120. FIG. 6 shows an example of the connection station list in a table format. The AP 120 has the configuration shown in FIG. 3, and the connectable AP list aggregating unit 123 aggregates and aggregates a plurality of connectable AP lists received from the wirelessly connected stations 110 via the wireless communication unit 122. The connectable AP list is sent to the AP control device 130 via the communication unit 121.

  The connection station management unit 124 holds a list of connected stations 110 (connection station list) as shown in FIG. 6, and the connection station list is sent to the AP control device 130 via the communication unit 121. .

  The connected station list has information on the station 110 wirelessly connected to the AP 120 holding the list, the transmission rate (connection rate) for each connection link, and the actual traffic volume.

  FIG. 4 shows an example of a block configuration of the AP control device 130. The AP control apparatus 130 has the configuration shown in FIG. 4, and the connectable AP list aggregating unit 131 aggregates a plurality of connectable AP lists received from the AP 120 via the communication unit 133. The connected station list aggregating unit 134 aggregates a plurality of connected station lists received from the AP 120 via the communication unit 133. The dormant AP selection unit 132 uses the connectable AP list aggregated in the connectable AP list aggregating unit 131 and the connected station list aggregated in the connected station list aggregating unit 134 to select the dormant AP 120.

  FIG. 7 shows an example of an operation sequence of the station 110, the AP 120, and the AP control device 130. First, the station 110 that has received the beacon signal (S101) issued by the AP 120 generates a connectable AP list from the address of the AP 120 included in the beacon signal and the received signal strength of the beacon signal (S102). Thereafter, the station 110 transmits the generated connectable AP list to the AP 120 (S103).

  The AP 120 that has received the connectable AP list from the station 110 aggregates the received connectable AP list (S104) and transmits it to the AP control device 130 together with the connected station list (S105).

  The AP control apparatus 130 aggregates the connectable AP list and the connected station list (S106), and selects the AP 120 to be suspended by the algorithm shown in FIG. 8 (S107). The selected AP 120 is notified to transmit a message for requesting a change of belonging to the station 110 connected to the AP 120 (S108), and the AP 120 that has received the notification notifies the connected station 110. On the other hand, a message for requesting attribution change having the AP information of the change destination is transmitted (S109).

  The station 110 that has received the message disconnects from the connected AP 120 (S110), and connects to the AP 120 indicated by the message.

  Upon confirming that all the connected stations 110 have been disconnected, the AP 120 transmits an attribution change completion message indicating that the attribution change of the stations 110 has been completed to the AP control device 130 (S111).

  When the AP control device 130 receives the attribution change completion message from the AP 120, the AP control device 130 transmits a pause message to the AP 120 (S112), and the AP 120 that has received the message shifts to a pause state.

  FIG. 8 shows an example of the operation flow of the dormant AP selection unit 132. Finally, the algorithm of FIG. 8 for determining which AP 120 is to be suspended will be described. First, the AP 120 having the lowest channel utilization rate is selected as a dormant candidate using the aggregated connection station list (S201). The channel utilization rate is a ratio of time during which radio waves are actually transmitted within a certain period of time, and is expressed by the following equation (1).

  Formula (1) may be generalized to formula (2). The frame transmission time of Equation (2) may be a data frame transmission time, a control frame transmission time, or an ACK frame transmission time.

  Next, based on the connectable AP list, it is confirmed whether the station 110 connected to the selected AP 120 can connect to another AP 120 (S202). For calculating the change in channel utilization rate, information on the received signal strength of the connectable AP list and the traffic volume of the connected station list can be used. For example, the connection rate after the attribution change can be estimated from the received signal strength information of the connectable AP list, and the change in the channel utilization rate can be calculated from the information of the connection rate and the traffic volume.

  When all the stations 110 connected to the selected AP 120 can be connected to another AP 120 (S203: Yes), the channel when the attribution of the station 110 is changed for the other AP 120 to which the station 110 can connect. A change in usage rate is calculated (S206).

  If the station 110 connected to the selected AP 120 is not connectable to another AP 120 (S203: No), and there is another AP 120 in the wireless system connected to the AP control device 130 (S204: Yes). Then, the AP 120 having the next lowest channel utilization rate is selected as a candidate for suspension (S205). If not (S204: No), the algorithm is terminated assuming that there is no AP 120 that can be suspended.

  As a result of calculating the change in the channel utilization rate at the change-destination AP 120 when the attribution of the station 110 is changed, the channel utilization rate is set to a threshold value (which is equal to or lower than the channel utilization rate limit value described later). If it is less than (Yes) (S207: Yes), the AP 120 that can be paused is determined (S209), and the station 110 connected to the AP 120 is connected to another AP 120.

  As a result, the attribution of the station 110 can be changed without reducing the throughput of the station 110. For example, when an AP 120 has a channel utilization rate limit value (the access method of a wireless system, for example, CSMA / CA in a wireless LAN affects the channel utilization rate, there is a limit value, and when trying to communicate beyond that, Through the contention of access, there is a high possibility that throughput will decrease, and the channel utilization rate limit value may be calculated from the connection rate for each link, in which case the channel utilization rate limit value increases as the connection rate increases. If a new station 110 is connected to the AP 120, the throughput of not only the newly connected station 110 but also the originally connected station 110 is likely to decrease. Become.

  When the change of the channel usage rate is calculated in the AP 120 as the change destination when the attribution of the station 110 is changed, if the channel usage rate is equal to or higher than the threshold (S207: No), it is assumed to belong to the other AP 120. (S208). If belonging to another AP 120 is possible (S208: Yes), S206 is executed again, and if belonging to another AP 120 is impossible (S208: No), another AP 120 is set as a pause candidate (S204). : Yes → S205), S202 is executed.

  As described above, the present invention has the following effects. The first effect is that a power-saving wireless system can be provided because the AP 120 that does not need to operate is suspended.

  The second effect is that there is no influence on the communication quality according to the utilization rate of the radio channel, or the attribution of the station 110 is changed within a small range. It can be provided.

  The third effect is that the AP 120 that the AP control apparatus 130 pauses can be selected without adding hardware to either the station 110 or the AP 120 because the beacon signal generated by the existing AP 120 is mainly used. .

  FIG. 9 shows an example of a usage environment of a dormant AP selection system 200 according to another embodiment. FIG. 10 shows an example of a block configuration of the AP 220. In this configuration, it is assumed that a network is configured from the station 210 and the AP 220. The station 210 has the configuration shown in FIG. The AP 220 has the configuration shown in FIG.

  The connectable AP list aggregating unit 223 aggregates a plurality of connectable AP lists received from the wirelessly connected stations 210 via the wireless communication unit 222, and stores the aggregated connectable AP lists in the wireless communication unit 222. To the neighboring AP 220.

  The connected station management unit 224 holds a list of connected stations 210 (connected station list) as shown in FIG. 6, and the connected station list is sent to the neighboring AP 220 via the wireless communication unit 222. .

  The dormant AP selection unit 225 includes a connectable AP list received from the neighboring AP 220 via the wireless communication unit 222, a connection station list, a connectable AP list of the connectable AP list aggregation unit 223, and a connection station management unit. The AP 220 to be suspended is selected using the connection station list inside the H.224.

  FIG. 11 shows an example of a usage environment of a dormant AP selection system 300 according to still another embodiment. In this configuration, it is assumed that a network is configured by the station 310, the AP 320, the AP control device 330, and the channel notification device 340. The station 310 has the configuration shown in FIG. The AP 320 has the configuration shown in FIG.

  The AP control device 330 has the configuration shown in FIG. 4 and transmits a connectable AP list to the channel communication device 340 via the communication unit 133.

  FIG. 12 shows an example of a block configuration of the channel notification device 340. After receiving the connectable AP list from the AP control device 330 via the communication unit 341, the notification channel determination unit 343 confirms the channel used by the AP 320 from the connectable AP list, and for all these channels The wireless communication unit 342 transmits a frame for instructing the station 310 to periodically scan the beacon signal.

  When the station 310 receives a frame instructed to periodically scan a beacon signal for a specific channel via the wireless communication unit 111, the station 310 transmits a beacon signal in a channel other than its own communication channel at regular intervals. to scan.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

100 dormant base station selection system 110 station 111 wireless communication unit 112 connectable base station list holding unit 120 AP
121 Communication Unit 122 Wireless Communication Unit 123 Connectable Base Station List Aggregation Unit 124 Connected Terminal Management Unit 130 AP Controller 131 Connectable Base Station List Aggregation Unit 132 Dormant Base Station Selection Unit 133 Communication Unit 134 Terminal List Aggregation Unit 200 Dormant Base Station Selection system 210 Station 220 AP
222 wireless communication unit 223 connectable AP list aggregation unit 224 connection station management unit 225 dormant AP selection unit 300 dormant base station selection system 310 station 320 AP
330 AP control device 340 Channel notification device 341 Communication unit 342 Wireless communication unit 343 Notification channel determination unit

Claims (7)

A dormant base station selection system for selecting a base station to be paused from a plurality of base stations,
A plurality of network-side devices on the network side including a plurality of base stations constituting a wireless communication network;
Among the plurality of network side devices, at least one network side device is:
The first base station having the lowest channel utilization rate among the plurality of base stations is selected as a suspension candidate, and a radio communication terminal connected to the first base station by radio communication can be connected to another second base station. Calculate the channel utilization rate when connected to the second base station at a certain time, and if the result of the calculation is less than the threshold value, select the first base station as a base station to be paused, When the result does not become less than the threshold value, the wireless communication terminal connected to the first base station by wireless communication is connected to the third base station when the wireless communication terminal can be connected to another third base station. A dormant base station selection system having a dormant base station selection unit that calculates the channel utilization rate of the channel . If it is not possible to connect to the third base station, the dormant base station selection unit selects the fourth base station with the next lowest channel utilization rate as a dormant candidate, and is connected to the fourth base station by radio communication resting base station selection system as claimed in claim 1 for calculating a channel utilization when connected to the fifth base station when the radio communication terminal is connectable to the other of the fifth base station. If it is not possible to connect to the second base station, the dormant base station selection unit selects the sixth base station with the next lowest channel utilization rate as a dormant candidate and is connected to the fourth base station by radio communication. The dormant base station selection system according to claim 1 or 2 , wherein when the wireless communication terminal is connectable to another seventh base station , a channel utilization rate is calculated when the wireless communication terminal is connected to the seventh base station. The dormant base station selection system according to claim 3 , wherein if the sixth base station does not exist, the dormant base station selection unit does not select any base station as a base station to be paused. A network side device constituting a wireless communication network,
The first base station having the lowest channel utilization rate among the plurality of base stations is selected as a suspension candidate, and a radio communication terminal connected to the first base station by radio communication can be connected to another second base station. Calculate the channel utilization rate when connected to the second base station at a certain time, and if the result of the calculation is less than the threshold value, select the first base station as a base station to be paused, When the result does not become less than the threshold value, the wireless communication terminal connected to the first base station by wireless communication is connected to the third base station when the wireless communication terminal can be connected to another third base station. A network-side device comprising a dormant base station selection unit that calculates the channel utilization rate of the network. A control method for controlling network side devices constituting a wireless communication network,
The first base station having the lowest channel utilization rate among the plurality of base stations is selected as a suspension candidate, and a radio communication terminal connected to the first base station by radio communication can be connected to another second base station. Calculate the channel utilization rate when connected to the second base station at a certain time, and if the result of the calculation is less than the threshold value, select the first base station as a base station to be paused, When the result does not become less than the threshold value, the wireless communication terminal connected to the first base station by wireless communication is connected to the third base station when the wireless communication terminal can be connected to another third base station. A control method comprising the step of selecting a dormant base station for calculating the channel utilization rate . A program for a network side device constituting a wireless communication network, wherein the network side device is
The first base station having the lowest channel utilization rate among the plurality of base stations is selected as a suspension candidate, and a radio communication terminal connected to the first base station by radio communication can be connected to another second base station. Calculate the channel utilization rate when connected to the second base station at a certain time, and if the result of the calculation is less than the threshold value, select the first base station as a base station to be paused, When the result does not become less than the threshold value, the wireless communication terminal connected to the first base station by wireless communication is connected to the third base station when the wireless communication terminal can be connected to another third base station. A program that functions as a dormant base station selection unit that calculates the channel usage rate .

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