JP6053177B2 - Heterogeneous network system and communication line selection method - Google Patents

Description

  The present invention relates to a heterogeneous network system and a communication line selection method.

  In recent years, mobile traffic in cellular systems using license bands has increased rapidly, and in order to distribute the load on mobile networks, the use of wireless LAN (Local Area Network) systems that use unlicensed bands as offload has attracted attention. ing.

  In addition, a communication method using an unlicensed band is being studied in LTE (Long Term Evolution), which is a cellular system standard, without using a wireless LAN. In wireless systems using these unlicensed bands, communication based on carrier sense multiple access (CSMA / CA), which is random access, is performed for coexistence with other wireless systems.

  In order to efficiently offload mobile traffic in an unlicensed band wireless system such as a wireless LAN system, the throughput of the unlicensed band wireless system in the cellular system (hereinafter referred to as “parent system”) is reduced. It is necessary to grasp.

  However, in the communication based on CSMA / CA, the throughput decreases due to inter-cell interference signals, multi-system interference, exposed terminal problem, hidden terminal problem, and the like. For this reason, there may be a large difference between the throughput predicted from information such as average received power and the number of access terminals and the actual throughput.

  In particular, the exposed terminal problem is difficult to avoid in the case where the amount of decrease in throughput varies depending on the wireless communication status of the terminal that causes the exposed terminal problem, and the exposed terminal problem occurs. As a method of avoiding the throughput reduction due to the exposed terminal problem, it is conceivable to change the frequency channel that causes the exposed terminal problem.

  However, with the widespread use of wireless LAN systems, almost all channels are used, so that there is a problem that the “exposed terminal problem” cannot be avoided even if the channel is changed to any frequency.

FIG. 32 is a diagram showing a configuration of a heterogeneous network system. Under the parent system 310, there are N base stations 3 (BS). The base station 3-k receives control signals or control signals from the terminals 1-k-1 to 1-k- _Uk ( _Uk is the number of terminals 1 communicating with the base station 3-k). Signals and data signals are communicated wirelessly.

  Further, the terminal 1 is a link capable of data communication with the access point 2 of the unlicensed band system 210 (shown by a solid line in FIG. 32), or BSSID (Basic Service Set Identifier) information and usage. It has a link (represented by a dotted line in FIG. 32) where a control signal indicating a channel or the like can be detected.

  Whether to connect to the wireless LAN system, to the parent system, or to use the wireless LAN system and the parent system together can be realized by the parent system grasping the throughput characteristics of the wireless LAN system. . If the throughput of the wireless LAN system is unknown, or if the characteristics of the throughput cannot be grasped correctly (for example, a sudden drop occurs from the expected throughput), a large drop in throughput and delay, or disconnection of the line may occur. Arise.

  FIG. 33 is a diagram showing a simulation environment (specifications). This figure is a diagram showing a simulation result in an apartment environment in order to actually see the influence of the exposed terminal problem. In this condominium, one room has 10 [m] x 10 [m], and there are 20 rooms of "2 x 10" per floor, 5 stories (each floor 3 [m], total height 15 [m]) Suppose that The access point 2 (AP) is installed in the center of the room. The terminals 1 were randomly distributed within a radius of 5 [m] from the access point 2.

  The modulation method is 256QAM, the coding rate is 3/4, the number of spatial multiplexing is 2, the number of MPDU bits is 1500 bytes, the number of A-MPDUs is 32, and the packet length is 2.3 [ms]. The propagation loss between the access point 2 and the terminal 1, between the access points 2, and between the terminals 1 is assumed to follow the model B of the IEEE 802.11n channel model. Consideration is also given to variations in propagation loss due to shadowing. Propagation loss due to the wall was given as 12 [dB] on the horizontal wall and 17 [dB] on the top and bottom ceilings or floors. The bandwidth is 20 [MHz], the number of channels is 4, and a random channel arrangement is adopted.

In order to evaluate the throughput, the base system 3 of the parent system 310 is only one, that is, only the base station 3-1. Terminal 1-1-1～ terminal _{1-1-U 1} subordinate to the base station 3-1 is located in the above apartment. Here, the number of users U ₁ is 200. Communication was limited to the downlink.

  The minimum reception sensitivity was -82 [dBm], the transmission power of the access point 2 was 23 [dBm], and the transmission power of the terminal was 17 [dBm]. The packet to be generated for each terminal has two parameters, 20 [Mbps] and 80 [Mbps], and RTS (Request to Send / CTS (Clear to Send)) An example in which a packet collision due to a hidden terminal problem was prevented by exchanging RTS / CTS signals was evaluated, respectively, when transmitting without exchanging signals (w / o RTS / CTS). When the data packet is generated, communication according to CSMA / CA in the wireless LAN is simulated, and an average value of throughput for 30 seconds is output to each terminal 1.

  The throughput in the physical link is calculated so that 140 [Mbps] is obtained in each link from the modulation scheme, coding rate, and MAC efficiency. Since the transmission is performed from one access point 2 to two terminals 1, the maximum throughput is 70 [ The calculation yields a throughput of about Mbps. However, even when data is generated so that each terminal 1 has an average of 20 [Mbps], it can be confirmed that the throughput is lower than 20 [Mbps] in more than half of the terminals.

  Although throughput characteristics have been improved to prevent packet collisions due to hidden terminals due to RTS / CTS signals, there are terminals that cannot return CTS signals due to problems with exposed terminals, etc., so there is a low value of 1 [Mbps] or less. There are 5.6 [%] without RTS / CTS, and 4.5 [%] with RTS / CTS, as the terminal 1 that has the throughput.

  Further, when 80 [Mbps] traffic is generated for each terminal 1, the proportion of the terminals 1 having characteristics lower than 1 [Mbps] increases remarkably. In both cases with and without RTS / CTS, 21% of the terminals 1 have a throughput lower than 1 [Mbps]. As described above, since the characteristics of the wireless LAN system greatly change depending on surrounding traffic and the like, it is very difficult to estimate the throughput uniquely.

Next, it will be shown how accurate the terminal 1 is when the throughput is predicted. Terminal 1-k-i (k is one of up to integers 1 to N) (i is either _.U-N to an integer I through U _N, the number of terminal 1 that communicates with the base station 3-N) Communicates with the neighboring access point 2-j (j is one of integers 1 to M), the estimated throughput T _{k, i} in the wireless LAN channel of the terminal 1-ki is given by the equation (1) expressed.

Here, L _{k, i} is the number of communication links of the same frequency channel exceeding the minimum reception sensitivity. ρ (n) is a throughput reduction function due to collision determined by the number n of links using the same frequency channel. C _{k, i} is the throughput in the physical layer that can be determined from the modulation scheme and coding rate used. K _j is the number of terminals 1 that communicate with the access point 2-j.

  The function ρ (n) uses a result obtained by simulating a situation in which a plurality of terminals 1 access by PHY / MAC (physical layer / Media Access Control) simulation. Specifically, ρ (1) = 1.000000000, ρ (2) = 1.0321555523, ρ (3) = 1.021357593, ρ (4) = 1.004838739, ρ (5) = 0.98909753, It is assumed that ρ (6) = 0.975382126.

  The value of ρ (2) to ρ (4) is more than 1.0 because the average contention window size is determined by the number of terminals 1 being accessed by a plurality of terminals 1. This is because it is slightly shorter than the case of 1, and the total throughput is increased.

μ _{k, i} is the MAC efficiency. μ _{k, i} is the ratio of the data packet to the communication to the terminal 1-ki with respect to the time width to be transmitted. μ _{k, i} is expressed by, for example, Expression (2).

Here, Φ _j communicates with the same channel as that of the access point 2-j, and other access points trying to perform communication (received power of −90 [dBm] or more) that can be observed by the access point 2-j. A set of two. τ _p is the length of time that the access point 2-p (p is any one of the integers 1 to M) occupies for one communication. τ _{D, j} is a time length occupied by the data packet of the access point 2-j in one communication.

  FIG. 34 is a diagram in which throughput evaluation results in the PHY / MAC simulator and estimated values from PHY layer conditions are plotted. The estimated throughput differs from the result obtained by actually giving traffic and considering the MAC sublayer, and a throughput of 5 [Mbps] is obtained at the minimum. Thus, even if the throughput is estimated from the conditions of the PHY layer, there is a large difference from the actual throughput.

  In this simulation, constant traffic is given to all the access points 2, but actually the generated traffic changes in real time depending on the user. In order to fully predict which terminal 1 or access point 2 will experience a decrease in throughput due to the “exposed terminal problem” or “hidden terminal problem”, it is necessary to grasp the throughput of all traffic and physical links. But this is not realistic.

  Even if the current throughput is actually measured based on the frequency bandwidth, modulation scheme, coding rate, packet error rate (PER), and the like, the surrounding traffic situation changes dynamically. For this reason, future throughput cannot be accurately predicted. In the parent system, which is a managed system, the throughput can be controlled to some extent, whereas when the parent system is used in combination with a wireless system such as a wireless LAN based on CSMA / CA, the throughput of the wireless LAN Due to the instability of the system, there was a problem that caused an unexpected decrease in throughput. In particular, when the terminal 1 that basically communicated only with the parent system 310 is switched to communication with a wireless system based on CSMA / CA, a sudden drop in throughput or disconnection significantly reduces user satisfaction. It will be.

Satoshi Fujiwara, Takatoshi Sugiyama, “Channel Allocation Method to Prevent the Exposed Terminal Problem in Wireless Mesh Networks”, NTT DoCoMo Technical Journal Vol. No. 14 4

  In a heterogeneous network including a mobile system (parent system) using a license band coexisting with a wireless system using an unlicensed band (for example, a wireless LAN system) and a terminal connected to the wireless system, There is a problem that user satisfaction may be significantly impaired due to instability of throughput of a terminal connected to a wireless system using an unlicensed band.

  The present invention is a heterogeneous network including a mobile system using a license band coexisting with a wireless system using an unlicensed band and a terminal connected to the wireless system, and is connected to the wireless system without greatly reducing the throughput. It is an object of the present invention to provide a heterogeneous network system and a communication line selection method capable of determining communication switching and combination of terminals to be used.

  One aspect of the present invention includes a wireless system that includes a plurality of access points and performs communication in an unlicensed band, a parent system that includes at least one base station and performs communication in a license band, the access point, and the base station. In a heterogeneous network system comprising a terminal capable of communicating with the terminal, the access point represents at least the access point of the access point and the terminal that communicates in an unlicensed band within a range detectable from the terminal. A first peripheral information collection unit that collects access point information, a first terminal information output unit that outputs the access point information to the base station through wireless communication, and a risk of lowering the throughput of the wireless system evaluated by the parent system Radio system risk information representing And a communication mode determining unit that determines communication with at least one of the access point and the base station, and information collection for collecting the access point information from the first terminal information output unit A terminal peripheral radio system environment information that represents at least the access point of the terminal, the access point that can be detected from the terminal, the access point that is detectable from the access point with which the terminal communicates, and the terminal Based on the access point information, an information organizing unit that stores at least access point peripheral wireless system environment information representing the access point in association with the access point and the terminal, and the information collected by the information collecting unit Terminal peripheral wireless system environment information Based on at least one of the Seth points neighboring radio system environment information, a heterogeneous network system and a parent system with, and risk assessment unit which evaluates the radio system risk information.

  In one aspect of the present invention, the information organizing unit stores identification information for identifying the access point based on the access point information collected from the terminal, and the predetermined identification information is assigned to the information organizing unit. The heterogeneous network system uses, as the access point peripheral radio system environment information, the access point information detected by the terminal that has detected another access point that can be detected from the access point with the highest received power.

  In one aspect of the present invention, the access point outputs a second peripheral information collection unit that acquires the access point information, and a second terminal information output that outputs the access point information to the base station or the terminal by wireless communication And the information collecting unit collects the access point information from the second terminal information output unit or the first terminal information output unit, and the information organizing unit includes an access point peripheral radio system environment. A heterogeneous network system that updates information based on the access point information collected by the information collection unit.

  In one aspect of the present invention, the parent system communicates with a received power value of a signal from the access point in the terminal, identification information of the access point, an available frequency bandwidth, and the access point. Radio system throughput that evaluates an expected value of throughput at the terminal of the radio system based on at least one of the number of terminals or based on an actual measured throughput value measured at the access point or the terminal An evaluation unit, and the base station has an evaluation notification unit that notifies the result of evaluation by the radio system throughput evaluation unit and the result of evaluation by the risk evaluation unit, and the terminal Result of the evaluation by the wireless system throughput evaluation unit notified from the unit and the risk evaluation Based on the results of the evaluation by a said access point and heterogeneous network system according to any one of claims 1 to 3 having a traffic selecting unit that communicates with at least one of the base station.

  According to an aspect of the present invention, the risk evaluation unit uses the same channel in the access point peripheral wireless system environment information collected by the information collection unit as to the reduction risk when the terminal connects to the access point. The number of other access points to be used, the number of terminals to which other access points using the same channel as the access point communicate, and the other access using the same channel as the terminal in the terminal peripheral wireless system environment information The number of points, the number of the terminals with which the other access point using the same channel as the terminal communicates, the identification information of the other access point using the same channel as the access point in the access point peripheral wireless system environment information No combination around the terminal The number of the access points that are not in the combination of identification information of other access points that use the same channel as the terminal in the system environment information, and the other access that uses the same channel as the terminal in the terminal peripheral wireless system environment information At least one indicator of the number of access points that are not in the combination of identification information of other access points using the same channel as the access point in the access point peripheral wireless system environment information among the combination of identification information of points, The heterogeneous network system stores the radio system risk information.

  One aspect of the present invention is the access point in the access point peripheral wireless system environment information stored in the information organizing unit, wherein the risk evaluating unit stores the decrease risk when the terminal connects to the access point. In the first group consisting of the other access points and the access points that use the same channel that can be detected from the access point, it is obtained by determining whether or not they can be detected from each other based on the access point peripheral radio system environment information. Based on the access point peripheral wireless system environment information, the number of the access points, which are conditions that cannot be detected within one group, and whether the second group of access points using the same channel that can be detected from the terminal can detect each other. Judgment Obtained a heterogeneous network system and the number of access points as a condition can not be detected with each other, that at least one of the indicators of the stores as a wireless system risk information.

  One aspect of the present invention is a heterogeneous network system in which the risk evaluation unit stores a value obtained from at least one of a sum, a maximum value, a minimum value, and a function of a plurality of indices as the radio system risk information. is there.

  In one aspect of the present invention, the risk evaluation unit selects a plurality of indices from the wireless system risk information, and performs determination based on the selected plurality of indices for each terminal, whereby the terminal using the wireless system It is a heterogeneous network system that controls the number.

  One aspect of the present invention is that the first terminal information output unit notifies the base station when communication with the access point is interrupted for a certain period of time, and stores the access point peripheral radio stored in the information organizing unit. This is a heterogeneous network system that stores discontinuity information and cause information in the system environment information.

  One aspect of the present invention is a heterogeneous network system including a plurality of access points, a wireless system that performs communication based on carrier sense multiple access, and a parent system that includes at least one base station and communicates in a license band. A communication line selection method in which a first peripheral information collection unit of a terminal collects access point information representing the detectable access point, and a first terminal information output unit of the terminal includes the access point Outputting the information to the base station by wireless communication, and the access point determination unit based on wireless system risk information representing a risk of a decrease in throughput of the wireless system evaluated by the parent system And decides to communicate with at least one of said base stations A step of collecting the access point information from the first terminal information output unit by the information collection unit of the parent system, and the access point detectable by the information organizing unit of the parent system from the terminal and Terminal peripheral wireless system environment information representing at least the access point of the terminal, access point detectable by the access point with which the terminal communicates, and access point peripheral wireless system environment information representing at least the access point of the terminal Based on the access point information, and storing the information in association with the access point and the terminal, and the terminal peripheral radio system environment information collected by the information collecting unit by the risk evaluation unit of the parent system And around the access point Based on at least one of the system environment information, a communication line selection method and a step of evaluating the radio system risk information.

  According to the present invention, the risk evaluation unit evaluates the radio system risk information based on at least one of the terminal peripheral radio system environment information and the access point peripheral radio system environment information collected by the information collection unit. Accordingly, in a heterogeneous network including a mobile system that coexists with a radio system and a terminal that is connected to the radio system, the heterogeneous network system and the communication line selection method can reduce the throughput without significantly reducing the throughput. It is possible to determine switching and combination of communication of terminals connected to the network.

It is a figure which shows the structure of the heterogeneous network system in 1st Embodiment. It is a flowchart which shows the operation | movement procedure of the 1st method of acquiring radio system environment information in 1st Embodiment. It is a figure which shows the terminal periphery radio | wireless system environment information collected from the terminal in 1st Embodiment with a table | surface. It is a figure which shows the radio | wireless system environment information organized for every BSSID of the terminal periphery radio | wireless system environment information in 1st Embodiment. It is a figure which shows the relationship between distance and propagation loss in 1st Embodiment. It is a figure which shows the problem in the case of creating radio system environment information from the terminal periphery radio system environment information which the terminal estimated in 1st Embodiment. It is a figure which shows the relationship between the distance from an access point, and the average received power error which an estimated distance shift | offset | difference causes in 1st Embodiment. It is a figure which shows the relationship between the average received power in the terminal selected for every BSSID, and the error of the average received power which can arise in 1st Embodiment. It is a flowchart which shows the operation | movement procedure of the 2nd method of acquiring radio | wireless system environment information in 1st Embodiment. It is a figure which shows the structure of the heterogeneous network system in 2nd Embodiment. It is a flowchart which shows the operation | movement procedure of the 3rd method of acquiring radio system environment information from an access point in 2nd Embodiment. It is a flowchart which shows the case where a 1st method and a 2nd method or a 3rd method are used together. It is a figure which shows the example of the radio | wireless system environment information by which AP periphery radio | wireless system environment information and traffic information which were collected from the access point in 2nd Embodiment were arranged for every BSSID. It is a figure which shows the radio | wireless system environment information updated in 2nd Embodiment. It is a figure which shows the radio | wireless system environment information creation / update part of a parent system in 2nd Embodiment. 10 is a flowchart illustrating an operation procedure for evaluating downlink throughput in the second embodiment. 10 is a flowchart illustrating an operation procedure for evaluating uplink throughput in the second embodiment. It is a flowchart which shows the operation | movement procedure which detects a hidden terminal problem in 2nd Embodiment. In the second embodiment, AP peripheral wireless system environment information collected from access points is wireless system environment information organized for each BSSID. It is a flowchart which shows the operation | movement procedure which detects a tethering terminal and a mobile router in 2nd Embodiment. An operation procedure for evaluating a risk due to communication failure due to an exposed terminal problem, a hidden terminal problem, interference from a radar, interference from another system, interference from a tethering terminal or a mobile router in the first embodiment and the second embodiment. It is a flowchart to show. It is a figure which shows the structure of the heterogeneous network system which performs traffic selection by initiative of a terminal in 1st Embodiment and 2nd Embodiment. It is a figure which shows the structure of the heterogeneous network system which performs traffic selection by initiative of a radio | wireless system in 1st Embodiment and 2nd Embodiment. It is a figure which shows the throughput characteristic by control restrict | limited with the number of access points of the same channel of AP periphery radio | wireless system environment information in the case of the production | generation packet rate 20 [Mbps] in 1st Embodiment and 2nd Embodiment. It is a figure which shows the throughput characteristic by control restrict | limited by the number of access points of the same channel of AP periphery radio | wireless system environment information in the case of the production | generation packet rate of 80 [Mbps] in 1st Embodiment and 2nd Embodiment. In the case of the generated packet rate of 20 [Mbps] in the first embodiment and the second embodiment, the number of access points on the same channel in the AP peripheral radio system environment information and the number of access points on the same channel in the terminal peripheral radio system environment information It is a figure which shows the throughput characteristic by the control restrict | limited by the larger number among these. In the case of the generated packet rate of 80 [Mbps] in the first embodiment and the second embodiment, the number of access points on the same channel in the AP peripheral wireless system environment information and the number of access points on the same channel in the terminal peripheral wireless system environment information It is a figure which shows the throughput characteristic in the control restrict | limited by the larger number among these. In the case of the generated packet rate of 20 [Mbps] in the first embodiment and the second embodiment, the control is performed on the condition that there is no difference between the access point and the terminal that can be detected, and the access point and the terminal. It is a figure which shows the throughput characteristic by the control on condition that the access point which can each be detected does not belong to the group which operate | moves independently. In the case of the generated packet rate of 80 [Mbps] in the first embodiment and the second embodiment, the control is performed under the condition that there is no difference between the access points that can be detected by the access point and the terminal, and the access point and the terminal. It is a figure which shows the throughput characteristic by the control on condition that the access point which can each be detected does not belong to the group which operate | moves independently. In the case of the generated packet rate of 20 [Mbps] in the first embodiment and the second embodiment, the access points that can be detected by the access point and the terminal satisfy the condition that they do not belong to the group that operates independently, and are the same It is a figure which shows the throughput characteristic by control that the number of the other access points detected by a channel is one or less at each of an access point and a terminal. In the case of the generated packet rate of 80 [Mbps] in the first embodiment and the second embodiment, the access points that can be detected by the access point and the terminal satisfy the condition that they do not belong to the group that operates independently, and are the same It is a figure which shows the throughput characteristic by control that the number of the other access points detected by a channel is one or less at each of an access point and a terminal. It is a figure which shows the structure of a heterogeneous network system. It is a figure which shows a simulation environment (specification). It is the figure which plotted the throughput evaluation result in a PHY / MAC simulator, and the estimated value from PHY layer conditions.

[First Embodiment]
A first embodiment of the present invention will be described in detail with reference to the drawings. Hereinafter, an example in which a wireless LAN system is used as a wireless system based on CSMA / CA will be described. The heterogeneous network system according to the first embodiment collects wireless system environment information, which is information on a wireless system based on neighboring CSMA / CA, and executes throughput estimation using the collected wireless system environment information H. In the first embodiment, a first method and a second method for collecting wireless system environment information will be described.

FIG. 1 is a diagram showing a configuration of a heterogeneous network system in the first embodiment. Heterogeneous Network system includes a terminal 10-1-1～ terminal _10-N-U N, a radio system 200, a parent system 300. The wireless system 200 includes access points 20-1 to 20-M (M is an integer of 1 or more). The wireless system 200 is, for example, a wireless LAN system or a cellular system that operates in an unlicensed band. The parent system 300 includes base stations 30-1 to 30-N (N is an integer of 1 or more). The parent system 300 communicates with a license band.

Base station 30-k (k is any integer between 1 to N) is, between the terminal 10-k-1~ terminal _10-k-U k, the control signal or control signal and a data signal Wireless communication. U _k is the number of terminals that can communicate with the base station 30-k.

Hereinafter, the terminal for 10-1-1～ terminals _10-N-U N items common to (wireless LAN terminal), and a second code representing the number of the base station 30 of the parent system 300 to be connected, the base station The 3rd code | symbol used as the serial number of the terminal 10 which communicates with 30 is abbreviate | omitted, and it describes with "terminal 10". The terminal 10 can detect a control signal indicating a link capable of data communication with the access point 20 of the wireless system 200 (shown by a solid line in FIG. 1) or BSSID information and a used channel. It has a link (represented by a dotted line in FIG. 1).

  In the first method of the first embodiment, peripheral wireless system environment information (access point information) detected by the terminal 10 is notified to the parent system 300 and is transmitted from the terminal 10 that communicates with the access point 20 at the closest distance. By selecting the terminal peripheral wireless system environment information, the wireless system environment information (AP peripheral wireless system environment information) that can be detected from the access point 20 (AP) that is the connection destination (communication destination) of the terminal 10 is estimated.

  In the second method of the first embodiment, the wireless system environment information (access point information) detected by the access point 20 is notified to the terminal 10 through a beacon or a communication packet, and the terminal 10 notifies the parent system 300. The system 300 acquires AP peripheral wireless system environment information.

FIG. 2 is a flowchart showing the operation procedure of the first method for acquiring the wireless system environment information in the first embodiment. In the first method of collecting wireless system environment information, the parent system 300 collects from the terminal 10 at least one of terminal peripheral wireless system environment information and AP peripheral wireless system environment information (access point peripheral wireless system environment information). And remember. The terminal peripheral wireless system environment information is information for creating the wireless system environment information, and is information that represents the peripheral access point 20.
(Step S000) The terminal 10 obtains “detectable from the access point 20” obtained from information on the wireless system communication device (at least one of the access point 20 and the terminal 10) that can be detected or a received signal from the access point 20. The wireless system communication device information ”is output to the parent system 300.

  FIG. 3 is a table showing terminal peripheral wireless system environment information collected from the terminal 10 according to the first embodiment. The first line from the top of the table shown in FIG. 3 shows the identification information (BSSID) of the access point 20 from which the terminal 10-1 can detect (hear) the terminal peripheral wireless system environment information, the channel used, The average value (average received power) [dBm] of the received power of the channel is collected.

  For example, the first item “BSSID1” in the first row “1-1” from the top of the table shown in FIG. 3 uses C1, that is, the channel “No. 1”. The average received power of the signal from BSSID1 in terminal 10-1-1 is -55 [dBm]. In addition, BSSIDs having SSIDs that can be accessed by the terminal 10-1-1 (which is an identifier of the access point 20 and prevents interference by communicating only with the access point 20 having the same SSID) are within the frame in the table. Shaded. The channel number conforms to the channel number defined by IEEE. The channel numbers “1 to 13” correspond to the 2 [GHz] band. Channel numbers “36 to 140” correspond to the 5 [GHz] band.

Returning to FIG. 2, the description of the flowchart of the first method will be continued.
(Step S001) When the base station 30 of the parent system 300 acquires the terminal peripheral wireless system environment information from the terminal 10, the BSSID included in the terminal peripheral wireless system environment information is stored in the parent system 300. To see if it is already included. If already included in the wireless system environment information (step S001: YES), the base station 30 advances the process to step S002. On the other hand, when it is not already included in the wireless system environment information (step S001: NO), the base station 30 advances the process to step S003.

(Step S002) The base station 30 newly registers the BSSID in the wireless system environment information. The base station 30 returns the process to step S001.
(Step S003) The base station 30 confirms the BSSID of the acquired terminal peripheral wireless system environment information. The base station 30 determines whether or not the value of the average received power associated with the BSSID exceeds the already stored BSSID update power (update threshold).

  (Step S004) The base station 30 stores the terminal peripheral radio system environment information of the terminal 10 associated with the BSSID as the terminal peripheral radio system environment information of the BSSID. The base station 30 returns the process to step S003.

  Note that the value of the average received power of the terminal 10 previously stored as the terminal peripheral wireless system environment information of the BSSID can be used as the “update threshold value” in the above step S003. Also, the higher the average received power, the higher the accuracy of the information, but the longer the estimated time, the lower the accuracy of the information. For this reason, the value of the update threshold value may be lowered as time elapses from the estimated time or the storage time of information. The update threshold is expressed by Expression (3).

Here, _PTH is an update threshold value. P _BSSID is a received signal from the BSSID at the terminal 10 that estimated the terminal peripheral wireless system environment information of the BSSID. Δt is the elapsed time. P ₀ is the update threshold offset. ρ is a time lapse threshold value reduction coefficient. By introducing a positive value in P ₀ , the update threshold can give priority to new information even if it is a little in time.

  ρ may be relatively increased according to the environment around the access point 20, the channel used by the access point 20, or the environment in which tethering or mobile routers go in and out and the temporal change is large. Also, ρ may be relatively small at the access point 20 where there is no change in the usage pattern of the surrounding wireless system.

  In the first method of collecting wireless system environment information, the parent system 300 does not have means for directly collecting information on wireless system communication detectable by the access point 20 from the access point 20. For this reason, the parent system 300 collects terminal peripheral radio system environment information estimated by the terminal 10 as information representing the access points 20 around the terminal 10 from the terminal 10, thereby detecting AP peripheral radio that can be detected from the access point. Estimate system environment information.

  Specifically, terminal peripheral wireless system environment information estimated by the terminal 10-ki located closest to the access point 20-j is information on wireless system communication that the access point 20-j will detect. Take advantage of the closeness. To give an extreme example, if the terminal 10-ki exists at the same position as the access point 20-j and has the same antenna configuration, it can be expected that the two match completely. Although it is unlikely that the terminal 10-k-i and the access point 20-j are in the same place, if the two are close to each other, that is, the signal from the access point 20-j is received with high power. If the terminal 10-ki exists, the wireless system communication information that would be detected from the access point 20-j can be replaced with the wireless system communication information detected by the terminal 10-ki. For this reason, the parent system 300 selects the terminal 10 having the highest average received power for each BSSID. Conversely, when the average received power from the BSSID is very high, the terminal peripheral wireless system environment information can be output from the terminal 10 to the parent system 300.

  The parent system 300 selects the terminal 10-1-1 having the highest average received power for the BSSIDs 1, 2, and 5. The parent system 300 selects the terminal 10-1-3 having the highest average received power for the BSSIDs 3, 6, and 7. Parent system 300 selects terminals 10-1-6 having the highest average received power for BSSIDs 4 and 8. The parent system 300 makes the terminal peripheral radio system environment information estimated by the selected terminal 10 the same as the AP peripheral radio system environment information estimated by the access point 20 having the BSSID with the highest average received power in the terminal 10. .

  FIG. 4 is a diagram illustrating radio system environment information arranged for each BSSID of terminal peripheral radio system environment information in the first embodiment. In FIG. 4, the value indicated under the BSSID is the average received power [dBm] of the signal of the BSSID at the referred terminal 10. As the average received power value is larger, the distance between the access point 20 of the BSSID and the terminal 10 is closer and the reliability of information is higher.

  In FIG. 4, BSSID 9 and BSSID 10 which are shaded in the table in the table are assigned to access points 20 which appear locally or temporarily such as tethering or mobile router based on the BSSID distributed for each vendor. Indicates the BSSID assigned. A BSSID using the same frequency channel (same CH) as that BSSID is shown on the left side of the table. Other BSSIDs are shown on the right side of the table as different channels (different CHs).

  Here, a certain BSSID and an uncertain BSSID can be separated. For example, the propagation loss with respect to the distance d between the access point 20 and the terminal 10 is expressed by Equation (4) (unit: [dB]). Here, f is a carrier frequency.

FIG. 5 is a diagram illustrating the relationship between the distance and the propagation loss in the first embodiment. Average received power R _{1, k at} terminal 10-1-k is expressed by equation (5). Here, P _t is transmission power [dBm].

  When the transmission power of the access point 20 is 17 [dBm], the average received power “−55 [dBm]” of the BSSID 1 is about 12 [m] when converted to a distance based on the equation (5). . Therefore, it is considered that the information of BSSID1 includes an error of ± 12 [m]. This error is effective for extracting BSSIDs that cannot actually be received. This is because the BSSID of the access point 20 in the range where the BSSID can be detected needs to be correctly grasped in order to determine whether or not the exposed terminal problem has occurred.

  The error given by the distance error with respect to the average received power between the access point 20 having a predetermined BSSID and the access point 20 having another BSSID needs to be considered. The error given by the distance error is when the terminal 10 that has received the terminal peripheral wireless system environment information is closer to the access point 20 having the BSSID estimated based on the BSSID included in the terminal peripheral wireless system environment information. Especially problematic.

  FIG. 6 is a diagram illustrating a problem when the wireless system environment information is created from the terminal peripheral wireless system environment information estimated by the terminal 10 in the first embodiment. The terminal 10-1-1 receives the signal received from the access point 20-2 as a signal from the access point 20-2 having BSSID2. The terminal 10-1-1 estimates the average received power of BSSID2 as −80 [dBm]. The terminal 10-1-1 is closer to the access point 20-1 than the access point 20-2. Therefore, the parent system 300 uses the BSSID information estimated by the terminal 10-1-1 as the terminal peripheral wireless system environment information at the access point 20-1.

  As in Case 1 shown in the upper part of FIG. 6, when the access point 20-1 is located farther than the terminal 10-1-1 with respect to the access point 20-2, the terminal 10-1-1 is connected to the access point 20--1. The terminal peripheral wireless system environment information received from 1 may not include information representing the access point 20-2. On the other hand, when the access point 20-1 and the access point 20-2 are close to each other as in the case 2 shown in the lower part of FIG. 6, the periphery of the terminal received by the terminal 10-1-1 from the access point 20-1 The wireless system environment information may include information representing the access point 20-2.

  When the access point 20 is installed at a higher location than the terminal 10, the access point 20 can easily acquire signals from other peripheral access points 20 than the terminal 10. Thus, it is necessary to consider that the terminal peripheral wireless system environment information received by the terminal 10-1-1 is not necessarily detectable even at the access point 20-1 closest to the terminal 10-1-1. There is.

  FIG. 7 is a diagram illustrating the relationship between the distance from the access point 20 and the average received power error caused by the estimated distance shift in the first embodiment. When the distance from the access point 20 is assumed for the cell edge of the wireless system 200 in which the problem illustrated in FIG. 6 occurs, the error amount with respect to the average received power can be estimated.

  FIG. 8 is a diagram illustrating the relationship between the average received power in the terminal 10 selected for each BSSID and the error in the average received power that can occur in the first embodiment. In FIG. 8, the distance from the access point 20 is assumed to be 40 [m], 50 [m], and 60 [m] for the cell edge (cell edge) of the wireless system 200 in the relationship illustrated in FIG. 7.

When the cell edge is assumed, an error with respect to the average received power in the terminal 10 selected for each BSSID can be estimated for each BSSID. The relationship between “average received power at the terminal” shown in FIG. 8 and average received power error (RSSI (Received Signal Strength Indicator) error) is stored in advance. As a result, the terminal peripheral wireless system environment information of the access point 20 having another BSSID that may not be received by the access point 20 having the predetermined BSSID can be extracted. For example, when the cell edge is 40 [m], the relationship between the average received power R _p [dBm] in the terminal 10 and the average received power error ΔR _AP [dB] can be approximated by a quadratic function.

As shown in FIG. 4, in BSSID1, the average received power of the selected terminal 10 is −55 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 3.8 [dB]. In BSSID2, the average received power of the selected terminal 10 is −58 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 4.5 [dB]. In BSSID3, the average received power of the selected terminal 10 is −52 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 3.1 [dB]. In BSSID4, the average received power of the selected terminal 10 is −66 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 6.9 [dB].

In BSSID5, the average received power of the selected terminal 10 is −60 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 5.0 [dB]. In BSSID6, the average received power of the selected terminal 10 is −52 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 3.1 [dB]. In BSSID7, the average received power of the selected terminal 10 is −51 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 2.9 [dB]. In BSSID8, the average received power of the selected terminal 10 is −56 [dBm]. Average received power error [Delta] R _AP using Formula (6), a 4.0 [dB].

  When the minimum detection sensitivity is −90 [dBm], the average received power becomes −90 [dBm] or less due to an error because the other access having BSSID5 estimated to be detectable from the access point 20 having BSSID4. This is information (terminal peripheral wireless system environment information) representing the point 20. This BSSID5 is shown in the row labeled BSSID4 in FIG. This terminal peripheral wireless system environment information is determined to have low reliability.

  As described above, the heterogeneous network system according to the present embodiment includes the terminal 10, the wireless system 200, and the parent system 300. Wireless system 200 includes a plurality of access points 20. The parent system 300 includes at least one base station 30.

  FIG. 9 is a flowchart showing an operation procedure of the second method for acquiring the wireless system environment information in the first embodiment. In the second method of collecting wireless system environment information, the parent system 300 collects AP peripheral wireless system environment information from the terminal 10 and stores it.

  First, the access point 20-j estimates at least information of the access point 20 among the access point 20 and the terminal 10 that communicate around the access point 20-j. The estimated contents include, for example, the BSSID of the peripheral access point 20, the channel used by the peripheral access point 20, the average received power value of the signal from the peripheral access point 20, the packet occupation rate of the peripheral access point 20, and communication with the peripheral access point 20. And at least one of the BSSIDs of the access points 20 that can be detected from the peripheral access points 20.

(Step S800) The access point 20-j notifies the detected AP peripheral wireless system environment information to the peripheral terminals 10.
(Step S801) The AP peripheral radio system environment information is acquired by the terminal 10, and at least one of the AP peripheral radio system environment information and the BSSID and channel information of the access point 20 is output to the base station 30 of the parent system 300.
(Step S802) The information organizing unit of the parent system 300 updates the AP peripheral wireless system environment information.

  The terminal 10 relates to a first peripheral information collection unit that acquires wireless system environment information around the access point 20-j from the access point 20-j that is within a detectable range of the wireless system 200, and the access point 20-j A first terminal information output unit that outputs information to the base station 30 by wireless communication.

  The parent system 300 includes an information collection unit that collects information on the access point 20-j from the first terminal information output unit, and other access points that can be detected from the access point 20 by the first method or the second method. The wireless system 200 is based on at least one of an information organizing unit that stores information (AP peripheral wireless system environment information) 20 and AP peripheral wireless system environment information and terminal peripheral wireless system environment information collected by the information collecting unit. And a risk evaluation unit that evaluates a risk of lowering throughput (wireless system risk information) when the terminal 10 accesses.

  The communication line selection method according to the present embodiment is performed by the steps executed by the first peripheral information collection unit of the terminal 10, the steps executed by the first terminal information output unit of the terminal 10, and the information collection unit of the parent system 300. A step performed by the information organizing unit of the parent system 300, a step performed by the risk evaluating unit of the parent system 300, and a step performed by the first traffic selecting unit of the parent system 300, the base station 30 or the terminal 10 And have.

  The first peripheral information collection unit of the terminal 10 includes information on the access point 20 existing in a detectable range and “information on the access point 20 detected from the access point 20-j notified from the access point 20-j”. At least one of them. The first terminal information output unit of the terminal 10 outputs the acquired wireless system environment information by wireless communication.

  The information collection unit of the parent system 300 collects the wireless system environment information input from the terminal 10 from the first terminal information output unit. The information organizing unit of the parent system 300 uses the information of other access points 20 that can be detected from the access point 20 as AP peripheral wireless system environment information for each access point 20 based on the first method or the second method. Remember. Further, the information organizing unit of the parent system 300 stores the information of the access point 20 that can be detected from the terminal 10 as the terminal peripheral wireless system environment information for each access point 20 based on the first method or the second method. To do.

  The risk evaluation unit of the parent system 300 evaluates the risk of throughput reduction of the wireless system 200 based on at least one of the AP peripheral wireless system environment information and the terminal peripheral wireless system environment information collected by the information collecting unit. The first traffic selection unit of the parent system 300 includes the access point 20 and the base that are partners of wireless communication with the terminal 10 based on the result of the throughput evaluation by the throughput evaluation unit and the result of the risk evaluation by the risk evaluation unit. At least one of the stations 30 is defined.

  The first traffic selection unit selects at least one of the access point 20 of the wireless system 200 and the base station 30 of the parent system 300 based on the “risk of throughput reduction of the wireless system 200” estimated by the parent system 300. Select as the connection destination.

  The first traffic selection unit is an average value of signal reception power (average reception power) between the access point 20-j performing data communication with the terminal 10 and the access point of the same channel detected from the access point 20-j. The throughput is evaluated and estimated in at least one of the number of BSSIDs, the number of terminals 10 connected to the access point 20-j, and the traffic volume of the terminal 10 connected to the access point 20-j. Based on both the throughput value and the stability, at least one of the access point 20 of the wireless system 200 and the base station 30 of the parent system 300 can be selected as a connection destination.

  Thus, the heterogeneous network system and the communication line selection method are wireless systems in a heterogeneous network including the parent system 300 coexisting with the wireless system 200 and the terminal 10 connected to the wireless system 200 or the parent system 300. It is possible to estimate the instability of the throughput of the terminal 10 connected to the terminal 200 and to select data communication with the wireless system 200 for a terminal that does not cause a rapid decrease in throughput. In this way, it is possible to prevent a decrease in user satisfaction by preventing a rapid decrease in throughput, and to allow a terminal corresponding to a QoS class and an application usage that cannot allow an unpredictable decrease in throughput to a carrier sense multiple access (CSMA / Although the communication is based on CA), a stable throughput can be provided.

  That is, the heterogeneous network system according to the present embodiment detects a terminal 10 whose throughput may vary greatly by predicting instability of the throughput of the wireless system 200 in advance. The heterogeneous network system according to the present embodiment can prevent the terminal 10 that cannot tolerate unpredictable throughput reduction from communicating with the access point 20 of the wireless system 200. In the heterogeneous network system according to the present embodiment, a terminal 10 that uses an application that cannot tolerate a rapid decrease in throughput, that is, a terminal 10 that has a problem when the throughput decreases, is connected to the base station 30 or the base station. 30 and the access point 20.

  In the heterogeneous network system according to the present embodiment, the number of access points 20 using the same channel that can be detected from the access point 20-j that is going to perform data communication can be used as risk information for reducing the throughput of the wireless system 200. . In the heterogeneous network system according to the present embodiment, the communication packet occupancy rate related to the access point 20 using the same channel that can be detected from the access point 20-j to be connected is used as the risk reduction risk information of the wireless system 200. it can. In the heterogeneous network system according to this embodiment, the number of access points 20 that cannot be detected from each other among the access points 20 that use the same channel that can be detected from the access point 20-j to be connected is determined as a risk of a reduction in throughput of the wireless system 200. It can be used as information. In the heterogeneous network system according to the present embodiment, the number of access points 20 other than the access point 20-j that uses the same channel as the access point 20-j that attempts to perform data communication that can be detected by the terminal 10-ki, It can be used as risk information for reducing the throughput of the wireless system 200. In the heterogeneous network system according to the present embodiment, the number of access points 20 that use the same channel as the access point 20-j that can be detected at the access point 20-j that is going to perform data communication but cannot be detected by the terminal 10-ki. Can be used as the risk information for reducing the throughput of the wireless system 200. In the heterogeneous network system according to the present embodiment, the number of access points 20 that use the same channel as the access point 20-j that can be detected by the terminal 10-ki but cannot be detected by the access point 20-j that performs data communication. Can be used as the risk information for reducing the throughput of the wireless system 200. In the heterogeneous network system according to the present embodiment, the number of access points 20 that cannot be detected from each other among the access points 20 that can be detected by the terminal 10 -k-i can be used as risk reduction information for throughput of the wireless system 200.

  The terminal 10 can also include a position information output unit that outputs position information indicating the position of the terminal. The information organizing unit stores information representing the access point 20 in association with the position information of the terminal 10. The risk evaluation unit evaluates the reduction risk based on the estimation result based on the position information indicating the position of the terminal 10 that is not operating.

The first terminal information output unit succeeds in transmission and reception from the terminal 10 for a certain period of time due to radio system-specific problems such as exposed terminal problems and hidden terminal problems, interference signals from other electronic devices, or channel movement due to radar detection. If not, the base station 30 is notified of non-communication information (non-communication information for a certain period of time) with respect to the access point 20-j that is a partner for data communication.
The information organizing unit stores the disconnection information and cause information from the terminal 10 for each access point 20-j. The stored non-communication information can be used as information indicating a risk that the throughput of the access point 20-j of the wireless system 200 is reduced.

  The parent system 300 includes a received power value of a signal from the access point 20 in the terminal 10, access point identification information (ID), an available frequency bandwidth, and the number of terminals 10 accessing by wireless communication. A radio system throughput evaluation unit that evaluates an expected value of throughput at the terminal 10 of the radio system 200 based on at least one or based on an actual throughput value measured at the access point 20 or the terminal 10. The base station 30 includes an evaluation notification unit that notifies the evaluation result by the wireless system throughput evaluation unit and the evaluation result by the risk evaluation unit. The terminal 10 includes a traffic selection unit that communicates with at least one of the access point 20 and the base station 30 based on the result of evaluation by the wireless system throughput evaluation unit notified from the evaluation notification unit and the result of risk evaluation.

[Second Embodiment]
The second embodiment is different from the first embodiment in that the access point 20 communicates with the parent system 300. In the second embodiment, only differences from the first embodiment will be described.

  In the second embodiment, a third method for collecting wireless system environment information will be described. The access point 20 can communicate directly with the parent system 300. Further, the access point 20 may communicate with the parent system 300 via the base station 30. Further, the access point 20 may communicate with the parent system 300 via another network.

  FIG. 10 is a diagram showing a configuration of a heterogeneous network system in the second embodiment. In the second embodiment, the parent system 300 can directly acquire communication information (AP peripheral wireless system environment information) of the wireless system that can be detected by the access point 20 and traffic information at the access point 20 from the access point 20. More accurate radio system environment information can be collected. The AP peripheral wireless system environment information may include traffic information of the access point 20. Here, the frequency at which at least one of the AP peripheral wireless system environment information and traffic information at the access point 20 is collected from the access point 20 and the frequency at which the terminal peripheral wireless system environment information is collected from the terminal 10 are determined independently. It shall be possible.

  The parent system 300 collects terminal peripheral wireless system environment information (see, for example, FIG. 3) from the terminal 10 whose wireless system is turned on. Further, the parent system 300 collects AP peripheral wireless system environment information from at least one access point 20.

  FIG. 11 is a flowchart showing an operation procedure of the third method for acquiring the wireless system environment information from the access point 20 in the second embodiment. The third method can be used in combination with the first method or the second method shown in the first embodiment.

  (Step S100) The access point 20-j collects at least one of communication information (AP peripheral wireless system environment information) of the wireless system around the access point 20 and traffic information of transmission / reception of the own device. The wireless system communication information around the access point 20 is, for example, the BSSID of the access point 20 that can be detected, the channel to be used, the received power, the number of subordinate terminals, or the time occupancy information of the packet. The traffic information of the own device includes, for example, the number of terminals with which the access point 20-j communicates, the average throughput, the packet time occupancy, the amount of packet signal data to be stored in the buffer, and the amount of data remaining in the buffer. Information including at least one of a time ratio to be transmitted, backhaul communication capacity, non-communication information, or information for each of the upper and lower lines.

(Step S101) The collected information is output to the parent system 300 via wireless or wired communication.
(Step S102) The parent system 300 stores the collected information as AP peripheral wireless system environment information.

  The information of the access point 20 obtained in the second embodiment can also be obtained by the second method of the first embodiment, but the point and frequency with which traffic information can be obtained are different from the second method. Different. Which frequency is higher than the second method depends on the usage mode and is not uniquely determined. However, the parent system 300 is based on the second method and the first method of the first embodiment based on the communication load and frequency. Information on the access point 20 can be collected by at least one of the third methods of the second embodiment.

  Originally, in the third method of the second embodiment and the second method of the first embodiment, the access point 20-j (that is, the own device) of the AP peripheral wireless system environment information of the access point 20-j is used. The corresponding average received power cannot be measured. When the first method of the first embodiment, the second method of the first embodiment, and the third method of the second embodiment are used in combination, the parent system 300 uses the AP of the access point 20-j. The average received power corresponding to the access point 20-j (that is, the own device) of the peripheral wireless system environment information can be determined as a very large value. For example, the parent system 300 defines the average received power equivalent of the information acquired from the access point 20 as 0 [dBm] or the like, so that an update threshold value (determination threshold value) is obtained as in Expression (3). May be defined for each elapsed time.

  Also, unlike the first method for estimating environmental information according to the first embodiment, the parent system 300 can set an update threshold value for each item of information related to BSSID. The parent system 300 does not decrease the update threshold with the passage of time, such as a BSSID that can be detected from devices installed in the vicinity, and an average received power of the BSSID that changes little in time. . On the other hand, for the BSSID of the tethering terminal or mobile router, the parent system 300 can decrease the update threshold with the passage of time, and can easily update even information with low average received power.

  FIG. 12 is a flowchart showing a case where the first method and the second method or the third method are used in combination. Steps S900, S901, and S902 are the same as in the first method.

(Step S903) When the parent system 300 acquires the terminal peripheral wireless system environment information from the terminal 10, the parent system 300 compares the average received power with the update threshold value for each BSSID and terminal peripheral wireless system environment information. Parent system 300 determines whether the corresponding average received power is high relative to the update threshold. When the corresponding average received power is higher than the update threshold (step S903: YES), the parent system 300 advances the process to step S904. When the corresponding average received power is not high with respect to the update threshold (step S903: NO), the parent system 300 ends the process.
(Step S904) The parent system 300 updates the item of the wireless system environment information based on the terminal peripheral wireless system environment information collected from the terminal 10. The parent system 300 returns the process to step S903.

  FIG. 13 is a diagram illustrating an example of wireless system environment information in which AP peripheral wireless system environment information and traffic information collected from the access point 20 are arranged for each BSSID in the second embodiment. The parent system 300 creates the wireless system environment information of the access point 20 based on the terminal peripheral wireless system environment information from the terminal 10 and the AP peripheral wireless system environment information from the access point 20.

  In the wireless system environment information shown in FIG. 13, “AP-1” is a multicarrier access point (AP) that can simultaneously use 2 [GHz] and 5 [GHz], and has BSSID1 and BSSID2. Since the access point 20 can have a plurality of BSSIDs, different BSSIDs measured by the terminal 10 do not necessarily correspond to different access points 20.

  In addition to the BSSID information that can be received and decoded by the information from the access point 20, as shown in FIG. 13, the number of terminals 10 belonging to the BSSID, the data in the buffer, and waiting for transmission. The percentage of busy status, the throughput capacity of the backbone line, etc. can be collected.

  Further, based on information from the access point 20, average received power for the target terminal, uplink line occupancy, application information, terminal mobility information, radar detection information of a dynamic radio frequency selection (DFS) band, 2 [GHz] other system interference detection information, tethering / mobile router AP observation information, location information, communication usage parameter information (modulation method and coding rate index, MIMO communication spatial multiplexing number, multiuser MIMO mode usage information, short guard) Interval use information, channel feedback method information, etc.), non-communication information, and time and day-of-week characteristic information of these information can be collected. Further, the access point 20 may estimate the temporal occupancy rate of the packet for each terminal 10 or each BSSID for the busy rate, and output the estimation result to the parent system 300.

  The parent system 300 obtains the wireless system environment information shown in FIG. 13 directly from the access point 20, so that the wireless system environment information arranged for each BSSID of the terminal peripheral wireless system environment information received from the terminal 10 (see FIG. 4). More accurate wireless system environment information.

  The terminal peripheral wireless system environment information collected from the access point 20 is not necessarily collected in real time. For this reason, the reliability of the parameter that can be dynamically changed in the terminal peripheral wireless system environment information is low. For example, for a device operating as an access point 20 such as a tethering terminal or a mobile router that appears on a scale of several minutes to several hours, and another access point 20 having a BSSID that dynamically changes a channel, The AP peripheral wireless system environment information collected from the point 20 is considered to be less accurate than the terminal peripheral wireless system environment information collected from the terminal 10.

  Therefore, the parent system 300 has organized the wireless system environment information (see FIG. 13) in which the AP peripheral wireless system environment information received from the access point 20 is organized, and the terminal peripheral wireless system environment information received from the terminal 10. The wireless system environment information (see FIG. 4) is compared. By this comparison, the parent system 300 can improve the estimation accuracy of the surrounding wireless system communication environment.

  In the parent system 300, for example, when there is a deviation (difference) in the presence of the access point 20 (BSSID 9 and BSSID 10 in FIG. 13) such as a tethering terminal or a mobile router, and there is a deviation in the frequency channel used for the same BSSID. In some cases, priority is given to new terminal peripheral wireless system environment information.

  In the table (see FIG. 13) showing the radio system environment information in which the AP peripheral radio system environment information received from the access point 20 is arranged, the use channel of the BSSID 7 in the row of the access point 20-1 “AP-1” is No. 100 (C100). On the other hand, in the table (see FIG. 13) showing the radio system environment information in which the terminal peripheral radio system environment information received from the terminal 10 is arranged, the use channel of BSSID 7 is No. 120 (C120). When the terminal peripheral wireless system environment information received from the terminal 10 is newer than the terminal peripheral wireless system environment information received from the access point 20, the parent system 300, based on the terminal peripheral wireless system environment information received from the terminal 10, The channel used by BSSID7 in the wireless system environment information is number 100.

  In FIG. 13, the BSSID 10 that the tethering terminal or mobile router has is new information and is received by the terminal 10. For this reason, it can be considered that BSSID10 is currently detected based on BSSID1 and BSSID2. Other BSSID observation information and average received power values may be accurate as measured by the access point 20.

  When combining the information, after collecting the value of average received power in the terminal 10 that acquired the terminal peripheral wireless system environment information for each BSSID shown in FIG. 4 and the terminal peripheral wireless system environment information or AP peripheral wireless system environment information Based on the elapsed time, the wireless system environment information shown in FIG. 4 and the wireless system environment information shown in FIG. 13 can be integrated.

  When the terminal 10 outputs the terminal peripheral wireless system environment information to the parent system 300 so that the parent system 300 can accurately grasp the time elapsed since the terminal peripheral wireless system environment information or the AP peripheral wireless system environment information was collected. The time when the terminal peripheral wireless system environment information is estimated can be output. Similarly, when the AP peripheral wireless system environment information is output to the parent system 300, the access point 20 can output the estimated time of the AP peripheral wireless system environment information.

  Further, even if the parent system 300 does not know the estimated time, based on the time when the terminal peripheral wireless system environment information or the AP peripheral wireless system environment information is acquired by performing feedback immediately after the estimation, for example, The time estimated by the terminal 10 or the access point 20 can also be roughly estimated.

  When the elapsed time Δt from the time when the terminal peripheral wireless system environment information or the AP peripheral wireless system environment information is estimated to the present time can be estimated, the wireless system environment information includes the collected information as shown in FIGS. Is included in the elapsed time Δt [minutes]. Therefore, the parent system 300 selects information having a shorter elapsed time Δt from the terminal peripheral wireless system environment information and the AP peripheral wireless system environment information for information that requires real-time performance. On the other hand, the parent system 300 can select the AP peripheral wireless system environment information or the terminal peripheral wireless system environment information received from the terminal 10 having a high average reception power as probable information for information that does not require real-time performance. .

  Similar to the first method and the second method for collecting the wireless system environment information in the first embodiment, the parent system 300 also has the BSSID by the third method for collecting the wireless system environment information in the second embodiment. Create radio system environment information organized for each.

  FIG. 14 is a diagram illustrating the updated wireless system environment information in the second embodiment. That is, FIG. 14 is wireless system environment information in which the wireless system environment information shown in FIG. 4 is updated based on the wireless system environment information shown in FIG. The location to be updated is described as “same as BSSID” in FIG.

  When the parent system 300 cannot acquire the terminal peripheral wireless system environment information from the terminal 10 via the base station 30, the parent system 300 creates the wireless system environment information based only on the AP peripheral wireless system environment information received from the access point 20. Further, the access point 20 may receive the terminal peripheral radio system environment information estimated by the terminal 10 and transfer it to the parent system 300 as the terminal peripheral radio system environment information estimated by the terminal 10.

  The parent system 300 collects the number of control signals such as beacons on the same channel as the BSSID communication from the terminal 10 or the access point 20 as shown in the table added to the lower part of FIG. The parent system 300 can estimate how much transmission time the control signal occupies with respect to the total time based on the number of beacons.

  FIG. 15 is a diagram illustrating a radio system environment information creation / update unit of the parent system in the second embodiment. The parent system 300 includes a terminal radio system information collection unit 100, an AP radio system information collection unit 101, and a radio system environment information creation / update unit 102.

  The terminal radio system information collection unit 100 collects terminal peripheral radio system environment information from the communicable terminals 10. AP wireless system information collection unit 101 collects at least one of AP peripheral wireless system environment information and traffic information from communicable access point 20. The wireless system environment information creation / update unit 102 stores the wireless system environment information illustrated in FIGS. 4 and 13. Also, the wireless system environment information creation / update unit 102 updates the wireless system environment information shown in FIGS. 4 and 13.

  The terminal radio system information collection unit 100, the AP radio system information collection unit 101, and the radio system environment information creation / update unit 102 are provided in a computer included in the parent system 300. The terminal radio system information collection unit 100, the AP radio system information collection unit 101, and the radio system environment information creation / update unit 102 may be provided in the base station 30 included in the parent system 300. In addition, the terminal radio system information collection unit 100, the AP radio system information collection unit 101, and the radio system environment information creation / update unit 102 are macro cell base stations that communicate control signals separately from the base station 30 that performs data communication. May be provided.

  The target areas for which the throughput is evaluated are as follows: each functional block is provided in the parent system 300, each functional block is provided in the macro cell base station, and each functional block is provided in the base station 30. Get smaller. As the target area for which throughput is evaluated becomes smaller, it becomes difficult to estimate the throughput of all terminals 10 communicating with the access point 20 included in the wireless system 200. On the other hand, the capacity of the storage unit for storing the wireless system environment information can be reduced as the target area for which the throughput is evaluated becomes smaller. The frequency and communication bit amount at which the terminal peripheral wireless system environment information and the AP peripheral wireless system environment information are output to the parent system 300 decrease as the target area whose throughput is evaluated becomes smaller. Further, the frequency and communication bit amount at which the AP peripheral wireless system environment information and traffic information are output to the parent system 300 also decrease as the target area whose throughput is evaluated becomes smaller.

Next, a method for estimating the minimum throughput as the instability of the throughput will be described.
The parent system 300 evaluates the expected value of throughput based on Expression (1). The parent system 300 may evaluate the expected value of the throughput based on the measured throughput. The parent system 300 considers only the access point 20-j that is the access destination even when the time τ _p that the signal occupies from other access points 20 in the signal detectable range and the access frequency is unknown. Evaluate the expected throughput.

The parent system 300 uses the data packet length τ _D used in the application, SIFS (Short IFS), DIFS (Distributed Inter-Frame Space), and the average value of the contention window size for random access. The MAC efficiency η _j is calculated based on the overhead τ _CW and the time length τ _p that the access point 20-p occupies for one communication. The MAC efficiency η _j is expressed by Expression (7).

The parent system 300 calculates the estimated throughput T _{k, i} (expected value of throughput) in the radio system channel of the terminal 10-ki by substituting the MAC efficiency η _j into the equation (1). Parent system 300 may estimate the expected value of throughput by dividing MAC efficiency η _j by the number L _j of access points 20 using the same channel as access point 20-j.

  The minimum throughput and its frequency that seriously affect user satisfaction cannot be calculated by these methods. Knowing how much the throughput is reduced from the expected values of these throughputs and the frequency and duration, the parent system 300 determines whether or not the expected values of the throughputs match the communication conditions of the user terminal 10. It can be determined in advance.

  Factors that cause a significant decrease in throughput include (i) exposed terminal problem, (ii) hidden terminal problem, (iii) change in the number of access points 20 by tethering terminal or mobile router, (iv) from radar and other systems Interference.

(I) Exposed terminal problem In the parent system 300, there are a plurality of wireless system devices using the same frequency channel, whether or not the plurality of wireless system devices can detect signals from each other, and to what extent the plurality of wireless system devices are The risk of the exposed terminal problem is determined based on information on whether to transmit a signal at a predetermined time. Hereinafter, based on the radio system environment information shown in FIG. 14, the description will be divided into downlink and uplink.

<Downlink>
In FIG. 14, the terminal 10 is connected to an access point 20-1 “AP-1”, an access point 20-3 “AP-3”, and an access point 20-4 “AP-4”. Therefore, the influence of the “exposed terminal problem” experienced by the access points 20-1, 20-3, and 20-4 is considered.

  In FIG. 14, it is BSSID1 and BSSID3 that are expected to receive BSSIDs having the same channel. For BSSID1, BSSID9 and BSSID10 exist on the same channel. The exposed terminal problem is a condition that the signals can be detected from each other. Therefore, each access point 20 having BSSID1, BSSID9, and BSSID10 has a frequency resource of about 3 minutes even in a state where each access point 20 has a signal to always transmit in a full buffer state (busy state). 1 is assigned. In this case, a major problem due to the exposed terminal problem does not occur.

  Next, the access point 20 having BSSID3 shares a channel with the access point 20 having BSSID4 and the access point 20 having BSSID5. There is a high possibility that the access point 20 having the BSSID 4 and the access point 20 having the BSSID 5 cannot receive signals from each other as shown in FIG.

  That is, the access point 20 having BSSID4 cannot receive a signal from the access point 20 having BSSID5. Further, the access point 20 having BSSID5 cannot receive a signal from the access point 20 having BSSID4. Therefore, the access point 20 having BSSID4 and the access point 20 having BSSID5 operate independently of each other, and can transmit signals from the own apparatus even when the other is transmitting signals. For this reason, the case where the access point 20 which has BSSID3 cannot access at all is considered.

  The parent system 300 uses the data packet of how long the access point 20 having the BSSID 4 and the access point 20 having the BSSID 5 perform communication in the full buffer state, and a beacon ( Based on the Beacon number and the like, it can be estimated how much the throughput can actually decrease.

  For example, when the access point 20 having BSSID4 performs transmission with a probability (access probability) of 80 [%] for the access point 20 having BSSID5 and 70 [%] for the access point 20 having BSSID5, the access point 20 having BSSID3 in CSMA / CA The probability of acquiring the transmission right is 6 [%] (= 20 [%] × 30 [%]). That is, the minimum throughput is obtained by multiplying Equation (1) by the value 0.06.

  When many control signals such as beacons are received from the access point 20 having BSSID3, the throughput for reducing the access probability between the access point 20 having BSSID4 and the access point 20 having BSSID5 is as follows. And depending on the communication status with the access point 20 having BSSID5. For this reason, it is difficult to estimate the throughput.

  The parent system 300 can confirm that a rapid decrease in throughput may occur in the downlink of the access point 20 having BSSID3. The parent system 300 causes the terminal 10 performing downlink communication with the access point 20-j to report the timing and duration when the throughput is reduced.

  The parent system 300 causes the channel of the access point 20-j to be changed when a sudden decrease in throughput may occur. In addition, the parent system 300 reduces the transmission right acquisition frequency at the access point 20 having the BSSID 4 that causes the throughput to decrease. The parent system 300 also increases the contention window size. Further, the parent system 300 designates a non-transmission time interval for the access point 20 having BSSID4.

<About Uplink>
Referring to FIG. 14, it is confirmed whether or not the access point 20 with which the terminal 10 is a communication partner and the access point 20 having another BSSID that uses the same channel as the access point 20 can detect signals with each other. .

  It is assumed that the terminal 10-1-3 and the terminal 10-1-4 are connected to the access point 20 having BSSID3, respectively. Since the terminal 10-1-3 can detect the signal from the access point 20 having BSSID4 and the signal from the access point 20 having BSSID5, it is considered that it is difficult to acquire the access right. On the other hand, since the terminal 10-1-4 can detect only the signal from the access point 20 having BSSID4, it is considered that it is difficult to acquire the access right.

  Therefore, it can be said that the terminal 10-1-3 has a risk that the throughput decreases in both the uplink and the downlink. The parent system 300 instructs the terminal 10-1-3 to communicate with the access point 20 having another BSSID.

  FIG. 16 is a flowchart illustrating an operation procedure for evaluating downlink throughput in the second embodiment. That is, FIG. 16 is a flowchart showing an operation procedure for detecting a decrease in downlink throughput due to an exposed terminal problem.

  (Step S301) The parent system 300 extracts other BSSIDs that can be detected from the access point 20 that uses the same channel as the BSSID of the access point 20 that the terminal 10-ki wants to access.

  (Step S302) The parent system 300 determines whether or not the number of other BSSIDs extracted is one or less. When the number of other BSSIDs extracted is one or less (step S302: YES), the parent system 300 advances the process to step S305. On the other hand, when the number of other BSSIDs extracted is two or more (step S302: NO), the parent system 300 advances the process to step S303.

  (Step S303) The parent system 300 refers to the extracted BSSID information and determines whether signals can be detected from each other. When signals can be detected from each other (step S303: YES), the parent system 300 advances the process to step S305. On the other hand, if the signals cannot be detected from each other (step S303: NO), the parent system 300 advances the process to step S304.

  (Step S304) In the downlink communication from the access point 20 having the extracted BSSID, the parent system 300 determines that a large throughput decrease due to the exposed terminal problem can occur. The parent system 300 validates flag information indicating a throughput decrease due to an exposed terminal problem for access from the terminal 10-ki to the access point 20 having the extracted BSSID. The parent system 300 estimates the specific minimum throughput based on the communication status of the access point 20 having another BSSID.

  (Step S305) The parent system 300 determines that stable communication is possible with the downlink of the access point 20 having the extracted BSSID. Although the frequency resource allocation ratio is reduced by the presence of the same BSSID, a throughput that can be estimated based on the BSSID in the channel and the number of terminals 10 under the channel is expected.

  FIG. 17 is a flowchart showing an operation procedure for evaluating uplink throughput in the second embodiment. That is, FIG. 16 is a flowchart showing an operation procedure for detecting a decrease in uplink throughput due to an exposed terminal problem.

  (Step S401) The parent system 300 extracts another BSSID that can be detected from the access point 20 that uses the same channel as the BSSID of the access point 20 that the terminal 10-ki wants to access.

  (Step S402) The parent system 300 determines whether the number of other BSSIDs extracted is one or less. When the number of other BSSIDs extracted is one or less (step S402: YES), the parent system 300 advances the process to step S405. On the other hand, when the number of other BSSIDs extracted is two or more (step S402: NO), the parent system 300 advances the process to step S403.

  (Step S403) The parent system 300 refers to the extracted BSSID information and determines whether or not signals can be detected from each other. When signals can be detected from each other (step S403: YES), the parent system 300 advances the process to step S405. On the other hand, if the signals cannot be detected from each other (step S403: NO), the parent system 300 advances the process to step S404.

  (Step S404) The parent system 300 determines in the uplink communication from the access point 20 having the extracted BSSID that a large throughput decrease due to the exposed terminal problem may occur. The parent system 300 validates flag information indicating a throughput decrease due to an exposed terminal problem for access from the terminal 10-ki to the access point 20 having the extracted BSSID. The parent system 300 estimates the specific minimum throughput based on the communication status of the access point 20 having another BSSID.

  (Step S405) The parent system 300 determines that stable communication is possible with the uplink of the access point 20 having the extracted BSSID. Although the frequency resource allocation ratio is reduced by the presence of the same BSSID, a throughput that can be estimated based on the BSSID in the channel and the number of terminals 10 under the channel is expected.

  16 and 17, the downlink and uplink have been described separately, but in the case of RTS / CTS (request to send / clear to send) exchange, RTS / CTS is used on the uplink for FIG. In some cases, it may be replaced with a problem that CTS does not return. In addition, FIG. 17 may be replaced with a problem that CTS does not return when RTS / CTS is used in the downlink.

(Ii) Hidden terminal problem The parent system 300 has a BSSID that can be detected in the channel used by the BSSID of the access point 20 that is the connection destination of the terminal 10-ki and the access point 20 that is the connection destination. It is determined whether or not.

  If the detectable BSSID does not match between the terminal 10-ki and the access point 20 to which the terminal 10-ki is connected, communication from a device that cannot detect an extra BSSID to a device that can detect an extra BSSID May cause a hidden terminal problem.

  When the frequency with which non-matching BSSIDs are communicated is greater than a predetermined frequency, the hidden terminal problem may be solved by using the RTS / CTS signal. However, if a non-matching BSSID is always transmitted as in the full buffer state, the CTS cannot be transmitted, so the hidden terminal may not be resolved.

  FIG. 18 is a flowchart illustrating an operation procedure for detecting a hidden terminal problem in the second embodiment. That is, FIG. 18 is a flowchart showing an operation procedure for detecting a decrease in throughput due to the hidden terminal problem.

  (Step S501) The parent system 300 uses other BSSIDs that can be detected by the access point 20 in the same channel as the channel used for communication by the BSSID of the access point 20 that the terminal 10-ki is trying to access. The other BSSIDs that can be detected by the terminal 10-ki are extracted.

  (Step S502) The parent system 300 determines whether or not the extracted BSSIDs match. If the extracted BSSIDs match (step S502: YES), the parent system 300 advances the process to step S505. On the other hand, when the extracted BSSIDs do not match (step S502: NO), the parent system 300 advances the processing to step S503.

  (Step S503) The parent system 300 determines which device can detect an extra BSSID. When the terminal 10-ki can detect an extra BSSID (step S503: terminal 10-ki), the parent system 300 advances the process to step S507. If the access point 20 can detect an extra BSSID (step S503: BSSID), the parent system 300 advances the process to step S504. If the terminal 10-ki and the access point 20 can detect an extra BSSID (step S503: both), the parent system 300 advances the process to step S506.

  (Step S504) When the parent system 300 has a risk that a transmission packet in uplink communication from the terminal 10-ki to the access point 20 collides with a transmission packet from the access point 20 having another BSSID that does not match. judge. The terminal 10 may be able to prevent a decrease in throughput by transmitting an RTS signal and acquiring a CTS from the access point 20 having a predetermined BSSID.

  (Step S505) The parent system 300 determines that there is a low risk that the throughput due to the hidden terminal problem is lowered in communication with the access point 20 having the predetermined BSSID.

  (Step S506) The parent system 300 determines that there is a risk of packet collision in the uplink and downlink between the terminal 10-ki and the access point 20 having a predetermined BSSID. The terminal 10-ki and the access point 20 having a predetermined BSSID may be able to prevent a decrease in throughput by performing communication using RTS / CTS.

  (Step S507) When the parent system 300 has a risk that a transmission packet in downlink communication from the access point 20 to the terminal 10-ki collides with a transmission packet from the access point 20 having another BSSID that does not match. judge. The access point 20 having a predetermined BSSID may be able to prevent a decrease in throughput by transmitting an RTS signal and acquiring a CTS from the terminal 10.

  However, if an access point 20 having a BSSID that does not match is constantly transmitting in a state close to a full buffer, the access point 20 having a predetermined BSSID cannot transmit a CTS when performing RTS / CTS, and MAC efficiency is increased. It may be further reduced. For this reason, the parent system 300 can also determine the use of RTS / CTS in accordance with the traffic of the access point 20 having a BSSID that does not match.

  In (i) the exposed terminal problem and (ii) the hidden terminal problem, the traffic actually generated is greatly affected. In other words, even if the condition to become a hidden terminal or the condition to become an exposed terminal is established, it is difficult to obtain access rights unless the wireless system device that causes these problems is communicating at that moment. Never become. Further, even if the condition for becoming a hidden terminal and the condition for becoming an exposed terminal are satisfied, if the wireless system device causing these problems is not performing communication at that moment, packet collision will not occur.

  Therefore, the parent system 300 stores the traffic tendency of the neighboring access points 20 to determine whether or not the current throughput is reduced due to (i) the exposed terminal problem and (ii) the hidden terminal problem. Can be evaluated.

  FIG. 19 is wireless system environment information in which AP peripheral wireless system environment information collected from the access point 20 is arranged for each BSSID in the second embodiment. The parent system 300 stores traffic trends per time period as radio system environment information divided into days of the week (weekdays, Saturdays, Sundays). In addition, the parent system 300 evaluates the time occupancy rate of the wireless communication packet with respect to the peripheral channels in units of 0.1 from 0.0 to 1.0, and stores the evaluation result as wireless system environment information. Yes.

  The parent system 300 collects terminal peripheral wireless system environment information from the terminal 10 and stores it in the storage unit of the server device. The parent system 300 collects AP peripheral wireless system environment information from the access point 20 and stores it in the storage unit of the server device.

  When the parent system 300 has a lot of traffic of the access point 20 causing the “exposed terminal problem” or the “hidden terminal problem”, that is, when the time occupancy rate of the access point 20 is high, a large throughput is likely to be reduced. Greatly assess risk. (See step S304 in FIG. 16 or step S404 in FIG. 17). On the other hand, when the traffic of the access point 20 causing the “exposed terminal problem” or the “hidden terminal problem” is small, that is, when the time occupancy rate of the access point 20 is low, the parent system 300 is unlikely to cause a large decrease in throughput. As a risk assessment.

(Iii) Change in Number of Access Points 20 by Tethering Terminal or Mobile Router In FIG. 14, BSSIDs of access points 20 that are considered tethering terminals or mobile routers are BSSID 9 and BSSID 10. In FIG. 14, only the tethering terminal and the mobile router that use channel 1 (C1), that is, channels 1 to 13 that are 2 [GHz] are shown. Tethering terminals and mobile routers have started to use 5 GHz, and are expected to increase in the future. Thus, the number of tethering terminals and mobile routers that appear in a limited time and the risks caused by tethering terminals and mobile routers need to be considered.

  When the parent system 300 causes the “exposed terminal problem” or the “hidden terminal problem” when the appearing tethering terminal or mobile router causes the “exposed terminal problem” or the “hidden terminal problem”, information indicating that the parent system 300 has caused the “exposed terminal problem” or “hidden terminal problem”. It is stored as information different from normal information. For example, when the parent system 300 updates the wireless system environment information illustrated in FIG. 14, the number of tethering terminals and mobile routers, channel information, or the caused problem is “exposed terminal problem” or “hidden terminal problem”. Information indicating which one is stored.

  The parent system 300 determines the risk when communicating with the access point 20 having a predetermined BSSID for each channel and position by extracting feature values from the wireless system environment information based on time zone, date, day of the week, etc. To do. When the tethering terminal or mobile router causing the problem is connected to the parent system 300, the parent system 300 controls the operation of the tethering terminal and the mobile router on which channel based on the wireless system environment information shown in FIG. Specify what to do.

  Since the parent system 300 can grasp traffic in real time when the tethering terminal or mobile router and the parent system 300 are connected, the influence on the throughput by the terminal 10 connected to the parent system 300 is estimated in advance. it can. Here, when the tethering terminal or the mobile router contributes to a decrease in the throughput of other terminals due to the “exposed terminal problem” or the “hidden terminal problem”, the parent system 300 changes from the parent system 300 to the tethering terminal. Or restrict data transmission to the mobile router. The parent system 300 switches the terminal 10 affected by the tethering terminal or the mobile router to communication with the parent system 300 or communication with the access point 20 having another BSSID.

  FIG. 20 is a flowchart illustrating an operation procedure for detecting a tethering terminal and a mobile router in the second embodiment. When detecting a tethering terminal and a mobile router, there are two triggers: a first trigger and a second trigger. The first trigger is a trigger mainly composed of the access point 20 or the terminal 10 that has enabled the wireless system function.

(Step S601) The access point 20 or the terminal 10 detects the BSSID.
(Step S602) The access point 20 or the terminal 10 determines whether or not the BSSID notified to the parent system 300 until the previous time is different from the BSSID detected this time. When the BSSIDs are different (step S602: YES), the access point 20 or the terminal 10 advances the process to step S603. On the other hand, when the BSSIDs are the same (step S602: NO), the access point 20 or the terminal 10 ends the process of detecting the tethering terminal and the mobile router.

  (Step S603) The access point 20 or the terminal 10 notifies the parent system 300 of the BSSID detected this time. The access point 20 or the terminal 10 stores the BSSID detected this time as dynamic BSSID information.

The second trigger is a trigger mainly composed of the parent system 300.
(Step S604) The parent system 300 periodically acquires at least one of the AP peripheral wireless system environment information and the traffic information including the BSSID information from the specific access point 20. The parent system 300 periodically acquires terminal peripheral wireless system environment information including BSSID information from the specific access point 20 and the terminal 10. For example, the parent system 300 requests BSSID information from the specific access point 20 and the terminal 10 when the predetermined timing comes. The parent system 300 stores the wireless system environment information including the acquired BSSID information in the storage unit. The parent system 300 advances the process to step S603.

(Iv) Interference from Radar and Other Systems Radar detection of the DFS band at 5 [GHz] and other system interference due to microwave oven or Bluetooth (registered trademark) at 2 [GHz] also cause unexpected throughput reduction. The parent system 300 also stores the occurrence frequency and duration for each time zone, date, and day of the week for information representing interference from these radars and other systems. The risk of communicating with the access point 20 having a predetermined BSSID through a channel used by a radar or another system can be determined.

  When the collection source of the radio system environment information is the terminal 10, that is, when the terminal peripheral radio system environment information is collected, a function for identifying signals of radar and other systems is not necessary for the determination criterion. The parent system 300 estimates interference from another system when the terminal 10 receives information indicating that a channel change notification has been received from the access point 20. In addition, the parent system 300 receives information from the access point 20 that indicates that a signal that cannot be determined as a wireless system packet is continuously received at a power level of a certain level or more, so that the parent system 300 receives information from other systems. Interference may be estimated.

  When the collection source of the radio system environment information is the access point 20, that is, when at least one of the AP peripheral radio system environment information and the traffic information is collected, the parent system 300 indicates that the channel change has been notified. By receiving information from the access point 20, the interference detected by the radar is estimated. Further, the parent system 300 estimates the interference detected by detecting the radar by receiving from the access point 20 information indicating that a signal that cannot be determined as a radio system packet is continuously received at a power of a certain level or higher. May be. In this case, the parent system 300 performs a new access to the access point 20 by updating the flag information associated with the access point 20 that is executing the process of moving or returning the channel accompanying the detection of the radar. The terminal 10 may be controlled to stop.

  FIG. 21 evaluates risks due to communication failure due to exposed terminal problem, hidden terminal problem, interference from radar, interference from other systems, interference from tethering terminal or mobile router in the first and second embodiments. It is a flowchart which shows the operation | movement procedure to perform. The terminal 10 starts communication with the wireless system 200.

  (Step S701) The access point 20-j or the terminal 10-ki that performs data communication with the access point 20-j is an uplink or downlink between the access point 20-j and the terminal 10-ki. If a significant drop in throughput or a disconnection state occurs on the line (step S701: YES), the parent system 300 advances the process to step S702. On the other hand, when the disconnected state does not occur in the wireless system 200 (step S701: NO), S701 is repeated as long as the communication in the wireless system 200 continues.

  (Step S702) The access point 20-j or the terminal 10-ki notifies the parent system 300 of information indicating that the throughput has decreased or information indicating that the access has been lost. When the access point 20-j moves through the channel, the destination channel can be notified to the parent system 300. In the case of interference from a radar, information indicating the duration of the radar observation and the observation channel can be added. These pieces of information are organized for each time zone as shown in FIG.

  FIG. 22 is a diagram illustrating a configuration of a heterogeneous network system that performs traffic selection under the initiative of the terminal 10 in the first embodiment and the second embodiment. The parent system 300 includes a wireless system communication risk evaluation unit 206 and a wireless system environment information storage unit 205. The base station 30-k includes a risk notification unit 201 and a wireless system environment information acquisition unit 204. The terminal 10-ki includes a communication form determination unit 202, a wireless system environment information output unit 203, a traffic selection unit 207, and a terminal communication form information output unit 208.

  The wireless system environment information output unit 203 of the terminal 10-ki outputs the terminal peripheral wireless system environment information detected by the terminal 10-ki to the base station 30-k communicating with the parent system 300 by wireless communication. To do. The radio system environment information acquisition unit 204 of the base station 30-k creates radio system environment information based on the received terminal peripheral radio system environment information, and uses the created radio system environment information as the radio system environment information of the parent system 300. The data is output to the storage unit 205.

  Based on the wireless system environment information stored in the wireless system environment information storage unit 305, the wireless system communication risk evaluation unit 206 of the parent system 300 can correspond to the access point 20-j and the terminal 10 -ki corresponding to the wireless system 200. Evaluate the risk of decreased throughput between The radio system communication risk evaluation unit 206 outputs the evaluation result of the throughput reduction risk to the risk notification unit 201 of the base station 30-k. The risk notification unit 201 outputs the evaluation result of the throughput reduction risk to the terminal 10-ki.

  The traffic selection unit 207 of the terminal 10-ki determines at least one of the access point 20 and the base station 30 as a connection destination based on the evaluation result of the throughput reduction risk. Based on the determination by the traffic selection unit 207, the communication mode determination unit performs data communication with the selected connection destination of the access point 20 and the base station 30. Here, in the traffic selection unit, application information used by the terminal 10-ki from the terminal communication form information output unit can be used for determination of traffic selection. For example, in an application that cannot tolerate the interruption of data communication or a rapid decrease in traffic, if there is even a slight risk of the wireless system, it can be determined to avoid communication by the wireless system 200 alone. In other words, control is performed so as not to use an application in which real-time performance is important and instantaneous interruption is not allowed. An application in which real-time property is important and cannot allow an interruption is, for example, a telephone call, a video call, a telephone conference, or an online game. Further, considering the terminal peripheral wireless system environment information detected by the terminal 10-ki or the contract form with the parent system 300 of the terminal 10-ki, the traffic selection unit 207 determines the data communication partner (connection destination). ) Can be determined.

  FIG. 23 is a diagram illustrating a configuration of a heterogeneous network system that performs traffic selection under the initiative of the wireless system 200 in the first embodiment and the second embodiment. The parent system 300 includes a wireless system communication risk evaluation unit 306 and a wireless system environment information storage unit 205. The access point 20 includes a terminal communication form information output unit 307. The base station 30-k includes a traffic selection unit 301 and a wireless system environment information acquisition unit 304. The terminal 10-ki includes a communication form determination unit 302 and a wireless system environment information output unit 303.

  The wireless system environment information output unit 303 of the terminal 10-ki outputs the terminal peripheral wireless system environment information detected by the terminal 10-ki to the base station 30-k communicating with the parent system 300 by wireless communication. To do. The radio system environment information acquisition unit 304 of the base station 30-k creates radio system environment information based on the received terminal peripheral radio system environment information, and uses the created radio system environment information as the radio system environment information of the parent system 300. The data is output to the storage unit 305.

  The terminal communication form information output unit 307 of the wireless system 200 outputs the AP peripheral wireless system environment information detected by the access point 20 to the wireless system communication risk evaluation unit 306 of the parent system 300. The wireless system communication risk evaluation unit 306 updates the wireless system environment information stored in the wireless system environment information storage unit 305 based on the received AP peripheral wireless system environment information.

  The radio system communication risk evaluation unit 306 of the parent system 300 evaluates the risk of throughput reduction of the base station 30-k radio system 200 based on the radio system environment information stored in the radio system environment information storage unit 305. The radio system communication risk evaluation unit 306 outputs the evaluation result of the throughput reduction risk to the traffic selection unit 301 of the base station 30-k. The traffic selection unit 301 selects at least one of the parent system 300 and the wireless system 200 as a connection destination based on the evaluation result of the throughput reduction risk. The traffic selection unit 301 outputs information indicating the selected connection destination to the terminal 10-ki.

  The communication form determination unit 202 of the terminal 10-ki selects at least one of the parent system 300 and the wireless system 200 as a connection destination based on the information indicating the connection destination selected by the traffic selection unit 301.

  As a result, the parent system 300 should switch which terminal 10 to communication with the wireless system 200 when one of the terminals 10 has to be offloaded to the wireless system 200 because the line of the parent system 300 is tight. Can be determined. In addition, the parent system 300 can switch the terminal 10 that has a low risk of throughput reduction due to communication with the wireless system 200 to communication with the wireless system 200. In addition, the parent system 300 uses the terminal 10 that has a high risk of throughput reduction due to communication with the wireless system 200 to perform communication with the wireless system 200 and communication with the parent system 300 together, thereby increasing the rapid throughput. It is also possible not to cause a decrease in the above.

  As described above, the access point 20 includes the second peripheral information collection unit that acquires information representing the other access point 20, and the second terminal information output unit that outputs information representing the other access point 20 by wireless communication. And having. The information collection unit of the parent system 300 collects information representing another access point 20 from the second terminal information output unit. The information organizing unit of the parent system 300 updates the stored information representing the other access points 20 based on the terminal peripheral wireless system environment information and the AP peripheral wireless system environment information.

  Thereby, since the parent system 300 can directly acquire the AP peripheral wireless system environment information corresponding to the terminal peripheral wireless system environment information from the access point 20, it can create more accurate wireless system environment information.

  Hereinafter, the effect of evaluating the throughput instability of the wireless system 200 when the access point 20 is installed at the center of each room using the simulation specifications shown in FIG. 33 will be described.

  Using the wireless LAN environment information in the parent system 300, the effect of selecting a terminal 10 that can obtain a stable throughput was evaluated. The simulation specifications are the same as the specifications shown in FIG. 33. One access point 20 is provided in each of 100 rooms, a total of 100 access points 20 and a total of 200 terminals 10 in each room. And the throughput was evaluated.

  First, as the simplest scenario, the number of other access points 20 in the same channel detected by the terminal 10-ki in the AP peripheral wireless system environment information from the access point 20-j that is to perform data communication. Shows the result of evaluating the instability.

  FIG. 24 is a diagram illustrating throughput characteristics by control in which the number of access points on the same channel in the AP peripheral wireless system environment information is limited when the generated packet rate is 20 [Mbps] in the first embodiment and the second embodiment. .

  The more access points on the same channel, the more unstable it is evaluated. For this reason, the radio system communication risk evaluation unit 206 or the radio system communication risk evaluation unit 306 of the parent system 300 provides a stable throughput to the terminal 10 that accesses the access point 20 in which the number of other access points is a certain value or less. Is a terminal 10 that can be expected.

  Whether the RTS / CTS is not used (solid line) or used (dotted line), the terminal 10 corresponding to the access point 20 with a small number of other access points reduces the probability of the terminal 10 having low throughput. be able to.

  In particular, the effect is greater when RTS / CTS is used. In this simulation specification, when the number of other access points is 3 or less, 2 or less, 1 or less, and 0, the ratio of the number of selected terminals 10 is 82.0 [%], 64. They were 0 [%], 34.2 [%], and 9.2 [%].

  When it is a condition that the surrounding access points 20 cannot be seen from the access point 20 (the number of other access points is 0), the terminal 10 is in a condition of “hidden terminal problem” or “exposed terminal problem”. A decrease in throughput has occurred. In addition, when it is a condition that the surrounding access point 20 cannot be seen from the access point 20, the ACK or CTS signal transmitted from the other terminal 10 is set to packet collision or NAV (Network allocation vector). As a result, the throughput is reduced.

  When the number of other access points 20 that can be heard by the access point 20 is 1 or less, the throughput of 10 [%] outage was 4.3 [Mbps] without RTS / CTS. On the other hand, when the number of other access points 20 that can be heard by the access point 20 is 1 or less, the throughput of the 10 [%] outage is 8.6 [Mbps] with RTS / CTS.

  When the number of other access points 20 that can be heard by the access point 20 is 0, the throughput of 10 [%] outage is 7.3 [Mbps] without RTS / CTS. On the other hand, when the number of other access points 20 that can be heard by the access point 20 is 0, the throughput of the 10 [%] outage is 15.9 [Mbps] with RTS / CTS.

  FIG. 25 is a diagram illustrating throughput characteristics by control in which the number of access points of the same channel in the AP peripheral wireless system environment information is limited when the generated packet rate is 80 [Mbps] in the first embodiment and the second embodiment. . Similarly, in this case, by setting the number of other access points 20 to a certain level or less, it is possible to select the terminal 10 that does not significantly reduce the throughput.

  When it is determined that the number of other access points is 1 or less and the terminal 10 of 34.2 [%] is stable, the throughput of the 10 [%] outage is 0.87 [Mbps] with RTS / CTS. On the other hand, when the number of other access points is 1 or less and the terminal 10 of 34.2 [%] is determined to be stable, the throughput of 10 [%] outage is 0.97 [Mbps] without RTS / CTS. .

  When the number of other access points is set to 0 and the terminal 10 of 9.1 [%] is determined to be stable, the throughput of the 10 [%] outage is 6.1 [Mbps] with RTS / CTS. On the other hand, when the number of other access points is 0 and the terminal 10 of 9.1 [%] is determined to be stable, the throughput of the 10 [%] outage is 10.1 [Mbps] without RTS / CTS. .

  In this way, the number of other access points 20 that can be detected by the access point 20 can be simply used as a basis. However, by making the wireless system environment information more complex, the ratio of the number of terminals 10 to be selected is increased. Thus, the proportion of outage terminals with low throughput can be reduced.

  Next, the number of other access points 20 of the same channel detected from the access point 20-j that the terminal 10-ki intends to perform data communication (the access point 20- in the AP peripheral wireless system environment information) j) and the number of access points 20 using the same channel that are detected from other than the access point 20-j that is a data communication partner that can be detected from the terminal 10-ki. The result of evaluating instability based on the larger value (hereinafter referred to as “the maximum value of the number of other access points”) of the information on the terminal 10-ki in the peripheral wireless system information) Show.

  FIG. 26 shows the number of access points of the same channel in the AP peripheral wireless system environment information and the same channel of the terminal peripheral wireless system environment information when the generated packet rate is 20 [Mbps] in the first embodiment and the second embodiment. It is a figure which shows the throughput characteristic by the control restrict | limited by the larger number among the number of access points.

  By considering both the information detected from the access point 20 and the information detected from the terminal 10, the instability evaluation system can be further enhanced. By selecting the terminal 10 so that the maximum value of the number of other access points is 3 or less, 2 or less, 1 or less, or 0, 71.2 [%] and 48. Terminals 10 of 5 [%], 20.0 [%], and 5.0 [%] can be selected.

  Since the ratio of the selected terminal 10 is different from the number of other access points of the same channel detected by the access point 20, a simple comparison with the case shown in FIG. 24 is not possible, but the characteristics are greatly improved. Yes. For example, the throughput of 10 [%] outage when the maximum number of other access points is 1 or less and 20 [%] terminal 10 is selected is 11.2 [Mbps] and 17.6 [Mbps]. is there. Therefore, the characteristics are greatly improved as compared with the case where the number of the other access points shown in FIG.

  FIG. 27 shows the number of access points of the same channel of the AP peripheral wireless system environment information and the same channel of the terminal peripheral wireless system environment information when the generated packet rate is 80 [Mbps] in the first embodiment and the second embodiment. It is a figure which shows the throughput characteristic in the control restrict | limited by the larger number among access point numbers.

  When the maximum number of other access points is set to 1 or less and 20 [%] of terminals 10 are selected, the throughput of 10 [%] outages is 5.6 [Mbps] and 6.7 [Mbps]. . Therefore, although the 9.2 [%] terminal 10 shown in FIG. 25 is selected, the characteristics are close.

  FIG. 28 shows the control on condition that there is no difference between the access point 20 and the terminal 10 that can be detected in the case of the generated packet rate 20 [Mbps] in the first embodiment and the second embodiment. It is a figure which shows the throughput characteristic by the control on condition that the access point 20 which can each be detected by the access point 20 and the terminal 10 does not belong to the group which operates independently.

  Here are two examples of instability definitions. The first is to use the detected shift of the access point 20. A combination of other access points 20 of the same channel detected from the access point 20-j that the terminal 10-ki intends to perform data communication (information of the access point 20-j in the AP peripheral wireless system environment information) ) And the access point 20 using the same channel other than the access point 20-j to be the data communication partner detected from the terminal 10-ki (terminal 10-ki in the terminal peripheral wireless system information) ) Is selected as a terminal 10 that can be expected to have a stable throughput.

  The second uses the existence of a group of access points 20 that operate independently. The AP peripheral radio system detects whether the access point 20 of the same channel detected by the terminal 10-ki from the access point 20-j that is going to perform data communication includes the access point 20-j. Judgment based on environmental information.

  Similarly, whether the access points 20 that can be detected from the terminal 10-ki are in a relationship that can be detected from each other is determined based on the AP peripheral wireless system environment, and the access point 20-j and the terminal 10-ki A terminal 10 is selected that has a condition that the detected access points 20 of the same channel can detect each other.

  The independent access point 20 group is determined only for the access point 20 of the same channel detected by the access point 20-j or the terminal 10-kj. That is, when the access points 20-2 to 20-4 are detected on the same channel from the access point 20-1, the access points 20-2 to 20-4 are detected on the same channel in the AP peripheral wireless system environment information. The access point 20 to be checked is confirmed.

  For example, for the access points 20-2 to 20-4, the access points 20-1, 20-3, 20-4 and 20-5, and the access points 20-1, 20-2, 20-4 and 20-6 Assume that the access points 20-1, 20-2, and 20-3 are detected on the same channel, respectively.

  In this case, although the extra access point 20 such as the access point 20-5 and the access point 20-6 is detected, at least the access points 20-1, 20-2, and 20 in the range detected from the access point 20-1 are detected. Since −3 and 20-4 are conditions detected from each other, it can be determined that there is no group of access points 20 that operate independently.

  However, for the terminal 10 connected to the access point 20-2 under the same conditions, the access points 20-1, 20-3, 20-4 and 20-5 detected by the access point 20-2 on the same channel. , Mutually confirm the detection conditions. Therefore, for example, when the access point 20 detected on the same channel at the access point 20-5 is the access point 20-2, 20-3 and 20-4, the access point 20-1 is not detected. It can be determined that there is a group of operating access points 20, that is, there is a terminal 10 whose throughput is unstable.

  If the determination is made based on the detected shift of the access point 20, the terminal 10 of 31.2 [%] can be selected as the terminal 10 having a stable throughput under this simulation condition. In this case, the throughput of the 10 [%] outage is 14.5 [Mbps] and 17.6 [Mbps]. This is because the number of other access points shown in FIG. 24 where the terminal 10 of 9.2 [%] is selected is 0, and the other access points shown in FIG. 26 where the terminal 10 of 20 [%] is selected. Compared with any of the cases where the maximum value of the number is 1 or less, improved or equivalent characteristics are obtained.

  If it is determined that there is no group of access points 20 that operate independently, 22.4 [%] of the terminals 10 are selected, but the characteristics particularly without RTS / CTS are remarkably improved. The throughput of 10% outage is 18.7 [Mbps] without RTS / CTS. On the other hand, the throughput of an outage of 10 [%] is 19.2 [Mbps] with RTS / CTS. Compared with either the case of FIG. 24 or the case of FIG. 26, 22.4 [%] of the terminals 10 are selected, and very high characteristics can be obtained.

  FIG. 29 shows the control on the condition that there is no difference in the access points that can be detected by the access point 20 and the terminal 10 when the generated packet rate is 80 [Mbps] in the first embodiment and the second embodiment. It is a figure which shows the throughput characteristic by the control on condition that the access point 20 which can each be detected by the access point 20 and the terminal 10 does not belong to the group which operate | moves independently.

  Through the determination that there is no deviation of the detected access point 20 and the determination that there is no group of access points 20 that operate independently, there is no RTS / CTS, and throughput (2.9 [Mbps], 1.8 [ Mbps]). Through the determination that there is no deviation of the detected access points 20 and the determination that there is no group of access points 20 that operate independently, with RTS / CTS, throughput (15.8 [Mbps], 9.1 [ Mbps]).

  The result of the number of other access points shown in FIG. 25 for selecting terminals 10 having the same ratio is 1 or less, and the result that the maximum number of other access points is 1 or less (see FIG. 27), It can be seen that high characteristics can be obtained even if these are compared.

  Also, the conditions can be combined. For example, it is possible to select an access point 20 that satisfies both conditions by determining whether there is no deviation of other access points 20 and determining that there is no group of access points 20 that operate independently. In this case, the terminal 10 of 17.9 [%] is selected, which is more than in the case where it is determined that there is no group of access points 20 that operate independently (the terminal 10 of 20 [%] is selected). However, the characteristics are slightly improved.

  These conditions can be considered by replacing them with numbers. For example, a deviation in the number of detected access points 20 can be detected as the number of access points 20 that can be detected by the terminal 10-ki but not detected by the base station 30-j, or a terminal that can be detected by the base station 30-j. It can be evaluated as a number of 10-ki. The results shown in FIGS. 28 and 29 correspond to setting these numbers to zero.

  Also, for the group of access points 20 that operate independently, the number that is a condition under which at least one of the access points of the same channel detected by the access point 20-j cannot be detected can be used. The results shown in FIGS. 28 and 29 correspond to setting this number to zero.

  As an example of a combination of conditions, the result of adding the condition that the maximum number of other access points shown in FIGS. 26 and 27 is 1 or less is added to the condition that there is no group of access points 20 that operate independently. Is shown in FIG. 30 and FIG.

  As a reference, a result of a combination of a condition that the maximum number of other access points is 2 or less and a condition that there is no group of access points 20 that operate independently is shown. This is the same as the case where the number of selected terminals 10 does not include a group of access points 20 that operate independently, and the result is the same as the case where there is no group of access points 20 that operate independently. It is. In this way, the result may not change even if the conditions are combined.

  FIG. 30 shows that, in the case of the generated packet rate 20 [Mbps] in the first embodiment and the second embodiment, the access point 20 that can be detected by the access point 20 and the terminal 10 does not belong to a group that operates independently. It is a figure which shows the throughput characteristic by control which satisfy | fills conditions and the number of other access points detected by the same channel is one or less at each of the access point 20 and the terminal 10.

  FIG. 31 shows that in the first embodiment and the second embodiment, when the generated packet rate is 80 [Mbps], the access point 20 that can be detected by the access point 20 and the terminal 10 does not belong to a group that operates independently. It is a figure which shows the throughput characteristic by control which satisfy | fills conditions and the number of other access points detected by the same channel is one or less at each of the access point 20 and the terminal 10.

  In FIG. 31, the value of 10 [%] outage is not greatly different in the degree of improvement compared to the case where there is no group of access points 20 that operate independently. Even in this case, there is a terminal 10 in which the characteristics are improved. In the example shown in FIG. 30 in which the traffic of 20 [Mbps] is generated, the terminal 10 of 2.2 [%] is 1 on the condition that there is no group of access points 20 that operate independently in the presence of RTS / CTS. Low throughput below [Mbps] or disconnected. By assigning a condition that the maximum value of the number of other access points is 1 or less, the number of low-throughput terminals 10 that are 1 [Mbps] or less is reduced to 0.3 [%]. . Further, when 80 [Mbps] traffic is generated, the throughput of the terminal 10 of 20 to 50 [%] is improved by about 1 to 10 [Mbps] with CDF.

  As described above, by using a combination of AP peripheral wireless system environment information, terminal peripheral wireless system environment information, and the like, it is possible to select the terminal 10 having a stable throughput. By selecting in this way, it is possible to predict a terminal 10 whose throughput can be reduced by fluctuations in surrounding traffic, instead of selecting a communication line after the throughput has changed.

  However, the proportion of the terminals 10 predicted to be able to expect stable throughput depends on a given communication environment. Therefore, the wireless system communication risk evaluation unit 206 or the wireless system communication risk evaluation unit 306 of the parent system 300 holds risk evaluations based on a plurality of criteria, and evaluates the proportion of terminals selected based on each criterion in advance. Can do. When it is desired to newly allocate the terminal 10 to the wireless system 200 due to the tightness of the radio resources of the parent system 300, a risk determination criterion that is a convenient ratio is selected from a plurality of risk determination criteria, and the base station 30 The risk notification unit 201 or the traffic selection unit 301 can be notified.

  Since the simulation results shown so far make the throughput of the PHY layer uniform, the risk evaluation also corresponds to the throughput. When the terminal 10 that can be regarded as a disconnected state in which the throughput is 1 [Mbps] or less is selected, the terminal 10 having a low throughput can be controlled not to perform data communication only with the wireless system 200 even by the above-described method.

  However, it is more effective to consider the division of radio resources based on the throughput in the PHY layer and the number of terminals 10 accessing the same access point 20. Therefore, the received power value of the signal from the access point 20-j in the terminal 10-ki, the identification information of the access point 20 (traffic information such as the backhaul communication capacity of the access point 20-j), and the usable frequency Bandwidth (for example, in wireless LAN, there are modes using 20 [MHz], 40 [MHz], 80 [MHz], and 160 [MHz], and the expected value of throughput increases as the bandwidth increases), and Based on the number of terminals 10 accessing the access point 20-j in the unlicensed band, it is possible to predict the throughput as an expected value in consideration of the effect of radio resource division. In addition, an actually measured throughput value measured at the access point 20-j or the terminal 10-ki can be used.

  By considering the throughput value and the instability evaluated in this way, a terminal 10 that can expect a stable throughput can be selected. For example, the terminal 10 having a low expected throughput value does not use the radio system 200 by setting an expected value of the minimum throughput allowable for the terminal 10-ki and controlling so as to satisfy the stability index. Can be controlled.

  Also, by using multiple numbers obtained from the AP peripheral wireless system environment information and terminal peripheral wireless system environment information used for the evaluation so far, a function is created by comparing indicators indicating whether or not the throughput actually decreases Risk assessment. For example, information in which the throughput is greatly reduced with respect to the estimated expected value of the throughput is collected from the terminal 10 or the base station 30, and the amount of deviation from the expected value of the throughput is used as an index for reducing the throughput. Thus, the function expressing the risk evaluation information can be derived based on the number obtained from the AP peripheral wireless system environment information and the terminal peripheral wireless system environment information, and used as a risk evaluation value.

  When at least one of the throughput and instability evaluation of the wireless system 200 does not satisfy the standard, the case of communicating only with the parent system 300 and the case of communicating with the wireless system 200 and the parent system 300 can be used in combination. For example, in the license band of the base station 30-k of the parent system 300, at least the usage status of radio resources, the allowable power consumption of the terminal 10-ki, and the application used by the terminal 10-ki It can be determined based on one.

  The terminal 10-ki can always perform control signal communication with the parent system 300 regardless of the selected communication circuit.

  An unlicensed band wireless communication system that operates based on CSMA / CA, which is an example of the wireless system 200, need not be a single system. For example, even when a wireless LAN system and a cellular system using an unlicensed band coexist, the terminal 10 obtains an identification number (ID) of an access point similar to a BSSID from at least one system. The parent system 300 can store wireless system environment information.

  The radio system communication risk evaluation unit 206 or the radio system communication risk evaluation unit 306 stores, as radio system risk information, a value obtained from at least one of a sum, a maximum value, a minimum value, and a function of a plurality of indices.

  The heterogeneous network system according to the present embodiment evaluates the risk of lowering the throughput of the wireless system 200 in a heterogeneous network that uses the wireless system 200 as an offload for the parent system 300 (for example, a mobile system). Thereby, the heterogeneous network system according to the present embodiment can prevent a significant decrease in throughput due to the terminal 10 switching the connection destination to the wireless system 200.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  You may make it implement | achieve the terminal, access point, base station, and heterogeneous network system in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. You may implement | achieve using programmable logic devices, such as PLD (Programmable Logic Device) and FPGA (Field Programmable Gate Array).

DESCRIPTION OF SYMBOLS 1 ... Terminal, 2 ... Access point, 3 ... Base station, 10 ... Terminal, 20 ... Access point, 30 ... Base station, 100 ... Terminal wireless system information collection part, 101 ... AP wireless system information collection part, 102 ... Wireless system Environmental information creation / update unit, 200 ... wireless system, 201 ... risk notification unit, 202 ... communication form determination unit, 203 ... wireless system environment information output unit, 204 ... wireless system environment information acquisition unit, 205 ... wireless system environment information storage , 206 ... Wireless system communication risk evaluation part, 210 ... Unlicensed band system, 300 ... Parent system, 301 ... Traffic selection part, 302 ... Communication form determination part, 303 ... Wireless system environment information output part, 304 ... Wireless system environment Information acquisition unit, 305 ... wireless system environment information storage unit, 306 ... wireless system communication list Evaluation unit, 307 ... terminal communication mode information output unit, 310 ... parent system

Claims (10)

A wireless system that includes a plurality of access points and communicates in an unlicensed band; a parent system that includes at least one base station and communicates in a license band; and a terminal capable of communicating with the access points and the base station In a heterogeneous network system comprising:
A first peripheral information collection unit that collects access point information representing at least the access point among the access point and the terminal, and communicates by an unlicensed band within a range detectable from the access point and the terminal;
A first terminal information output unit for outputting the access point information to the base station by wireless communication;
A communication mode determination unit that determines to communicate with at least one of the access point and the base station, based on radio system risk information representing a risk of a decrease in throughput of the radio system evaluated by the parent system;
A terminal having
An information collection unit for collecting the access point information from the first terminal information output unit;
The access point detectable from the terminal and terminal peripheral wireless system environment information representing at least the access point of the terminal, and the access point detectable from the access point with which the terminal communicates and at least the access of the terminal An information organizing unit for storing the access point peripheral wireless system environment information representing a point in association with the access point and the terminal based on the access point information;
A risk evaluation unit that evaluates the radio system risk information based on at least one of the terminal peripheral radio system environment information collected by the information collection unit and the access point peripheral radio system environment information;
A parent system having
A heterogeneous network system.   The information organizing unit stores identification information for identifying the access point based on the access point information collected from the terminal, and can be detected from the access point to which predetermined identification information is assigned. The heterogeneous network system according to claim 1, wherein the access point information detected by the terminal that has detected the access point at the highest received power is used as the access point peripheral wireless system environment information. The access point has a second peripheral information collection unit that acquires the access point information, and a second terminal information output unit that outputs the access point information to the base station or the terminal by wireless communication,
The information collection unit collects the access point information from the second terminal information output unit or the first terminal information output unit,
The heterogeneous network system according to claim 1 or 2, wherein the information organizing unit updates the access point peripheral wireless system environment information based on the access point information collected by the information collecting unit. The parent system is
Based on at least one of the received power value of the signal from the access point at the terminal, the identification information of the access point, the available frequency bandwidth, and the number of terminals communicating with the access point Or a wireless system throughput evaluation unit that evaluates an expected value of throughput at the terminal of the wireless system based on an actual measured throughput value measured at the access point or the terminal,
The base station
An evaluation notification unit for notifying the result of evaluation by the wireless system throughput evaluation unit and the result of evaluation by the risk evaluation unit;
The terminal
A traffic selection unit that communicates with at least one of the access point and the base station based on an evaluation result by the radio system throughput evaluation unit and an evaluation result by the risk evaluation unit notified from the evaluation notification unit; The heterogeneous network system according to any one of claims 1 to 3. The risk assessment unit
The decrease risk when the terminal connects to the access point is the number of other access points using the same channel in the access point peripheral wireless system environment information collected by the information collection unit, and the access point The number of terminals with which the other access point using the same channel communicates, the number of other access points using the same channel as the terminal in the terminal peripheral wireless system environment information, and the other using the same channel as the terminal The number of the terminals with which the access point communicates, the combination of identification information of other access points using the same channel as the access point in the access point peripheral wireless system environment information, the terminal peripheral wireless system environment information in the terminal peripheral wireless system environment information Same as terminal Of the number of access points that are not in the combination of identification information of other access points that use channels, and the combination of identification information of other access points that use the same channel as the terminal in the terminal peripheral wireless system environment information At least one indicator of the number of access points not included in the combination of identification information of other access points using the same channel as the access point in the access point peripheral radio system environment information is stored as the radio system risk information The heterogeneous network system according to any one of claims 1 to 4. The risk assessment unit
The other access point using the same channel that can be detected from the access point in the access point peripheral wireless system environment information stored in the information organizing unit, the reduction risk when the terminal connects to the access point, and In the first group of the access points, the access points of the access points that are conditions that cannot be detected in the first group, obtained by determining whether or not they can be detected from each other based on the access point peripheral wireless system environment information. And a condition incapable of being detected from each other obtained by determining based on the access point peripheral wireless system environment information whether the second group of access points using the same channel that can be detected from the terminal can detect each other. Na The number of access points, at least one of the indicators of, heterogeneous network system according to any one of claims 1 to 4 for storing a wireless system risk information. The risk assessment unit
The heterogeneous network system according to claim 5 or 6, wherein a value obtained from at least one of a sum, a maximum value, a minimum value, and a function of a plurality of indices is stored as the radio system risk information. The risk assessment unit
The number of the terminals using the radio system is controlled by selecting a plurality of indices from the radio system risk information and performing determination based on the selected indices for each of the terminals. The heterogeneous network system according to claim 1. The first terminal information output unit includes:
The communication information and cause information are stored in the access point peripheral wireless system environment information which is notified to the base station when communication with the access point is interrupted for a certain period of time and stored in the information organizing unit. The heterogeneous network system according to any one of claims 1 to 8. A communication line selection method in a heterogeneous network system including a wireless system including a plurality of access points and performing communication based on carrier sense multiple access and a parent system including at least one base station and performing communication in a license band. And
A first peripheral information collection unit of a terminal collecting access point information representing the detectable access point;
The first terminal information output unit of the terminal outputs the access point information to the base station by wireless communication;
The communication form determination unit of the terminal determines to communicate with at least one of the access point and the base station based on wireless system risk information representing a risk of lowering the throughput of the wireless system evaluated by the parent system. Steps,
The information collection unit of the parent system collects the access point information from the first terminal information output unit;
The information organizer of the parent system detects the access point that can be detected from the terminal and terminal peripheral wireless system environment information that represents at least the access point of the terminal, and can be detected from the access point with which the terminal communicates Storing the access point peripheral wireless system environment information representing at least the access point of the access point and the terminal in association with the access point and the terminal based on the access point information;
The risk evaluation unit of the parent system evaluates the radio system risk information based on at least one of the terminal peripheral radio system environment information collected by the information collection unit and the access point peripheral radio system environment information Steps,
A communication line selection method comprising:

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