JP5799325B2 - Wireless cordless handset that connects in consideration of traffic - Google Patents

Description

  The present invention relates to a wireless slave in a wireless network, and in particular, can be connected to an access point in consideration of wireless communication traffic.

  A general connection form of a wireless LAN network is generally called an infrastructure mode in which a wireless slave device that is a wireless client connects to an access point that is a parent device.

  In an infrastructure mode wireless LAN network, the number of access points is not limited to one, and a plurality of access points may be installed in a range where radio waves overlap. In that case, in general, access points having adjacent physical distances are operated using different channels so as not to cause radio wave interference.

  On the other hand, when the wireless slave unit can receive radio waves from a plurality of access points at a predetermined position as in the above-described environment, it is normally connected to an access point with the highest radio field intensity (RSSI). This is due to the estimation that an access point with strong radio field strength can perform wireless communication most stably.

  However, in reality, the correlation between the radio wave intensity and stable communication may be low. For example, this is the case where many wireless slave units are concentrated on one access point. In order to deal with such a problem, in Patent Document 1, when connecting to an access point, in addition to the above-described radio wave intensity, connection is performed in consideration of traffic that is a data transfer amount per unit time.

JP 2011-223178 A

  As in Patent Document 1, it is useful means to determine a connection access point in consideration of traffic when performing roaming or the like because an effect such as load balancing is obtained. However, it is not preferable that this traffic measurement is a burden on the processing of the wireless slave unit. In this sense, it can be said that the invention disclosed in Patent Document 1 has a problem.

  The data transfer amount per unit time disclosed in Patent Document 1 is an ideal parameter reflecting the actual traffic state. However, the measurement is not a process that should normally be performed by the wireless slave unit, but a process that the wireless slave unit is carrying out only for the purpose of determining a connection access point.

  The present invention solves this problem. That is, it is to provide a wireless slave device and a program thereof that can select a connection access point in consideration of traffic while keeping a burden on processing of the wireless slave device low.

  The first aspect of the present invention is a frame transmission means for transmitting a frame on a predetermined channel, a frame collision detection means for detecting a collision of frames transmitted by the frame transmission means, and a frame collision detected by the frame collision detection means. A frame collision frequency counting means for counting the number of times, a carrier sense means for detecting a carrier wave in a predetermined channel based on the frame collision frequency counted by the frame collision frequency counting means, and a carrier sense means for a predetermined time, Based on the carrier sense timeout detection means for detecting that the carrier is continuously detected, the carrier sense timeout number counting means for counting the number of carrier sense timeouts detected by the carrier sense timeout detection means, and the counted number of carrier sense timeouts , Should be connected An access point connection means for selecting the access point connection, a radio personal station comprising a.

  In the embodiment described later, the predetermined time based on the number of frame collisions in which the carrier sense means operates is expressed as a predetermined time arbitrarily determined within a back-off time (retransmission waiting time) determined by the number of frame collisions. Has been.

According to a second aspect of the present invention, there is provided a frame transmission means for transmitting a frame in a predetermined channel, a frame collision detection means for detecting a collision of frames transmitted by the frame transmission means, and a frame collision detected by the frame collision detection means. A frame collision count counting means for counting the number of times, a frame retransmission canceling means for canceling retransmission of a frame transmitted by the frame transmitting means based on the counted number of frame collisions, and a frame for counting the number of times the frame retransmission canceling means has canceled The wireless slave device includes a cancellation frequency counting unit and an access point connection unit that selects and connects an access point to be connected based on the counted number of frame cancellations.

The number of times the frame retransmission canceling means cancels is counted, and an access point to be connected is selected and connected based on the counted number of frame cancellations.

  Preferably, the access point connection means is operable as roaming means for changing an already connected access point to another access point.

According to a third aspect of the present invention, there is provided a radio slave unit comprising: a frame transmission unit that transmits a frame on a predetermined channel; a frame collision detection unit that detects a collision between frames transmitted by the frame transmission unit; and a frame collision detection unit. Frame collision number counting means for counting the number of detected frame collisions, carrier sense means for detecting a carrier wave in a predetermined channel for a predetermined time based on the number of frame collisions counted by the frame collision number counting means, and carrier sense means Carrier sense timeout detecting means for detecting that the carrier has been detected for a predetermined time, carrier sense timeout count counting means for counting the number of carrier sense timeouts detected by the carrier sense timeout detecting means, and the carrier sense counted. Based on timeouts An access point connection means for connecting select an access point to be connected, a program to function with.

  In the embodiment described later, the predetermined time based on the number of frame collisions in which the carrier sense means operates is expressed as a predetermined time arbitrarily determined within a back-off time (retransmission waiting time) determined by the number of frame collisions. Has been.

According to a fourth aspect of the present invention, there is provided a wireless slave device comprising: a frame transmission unit that transmits a frame on a predetermined channel; a frame collision detection unit that detects a collision between frames transmitted by the frame transmission unit; and a frame collision detection unit. Frame collision frequency counting means for counting the number of detected frame collisions, frame retransmission cancellation means for canceling retransmission of frames transmitted by the frame transmission means based on the counted number of frame collisions, and frame retransmission cancellation means canceling This is a program that functions as a frame cancel count counting means for counting the number of times and an access point connection means for selecting and connecting an access point to be connected based on the counted number of frame cancels.

The number of times the frame retransmission canceling means cancels is counted, and an access point to be connected is selected and connected based on the counted number of frame cancellations.

  Preferably, the access point connection means is operable as roaming means for changing an already connected access point to another access point.

  The wireless slave device disclosed in the present invention uses parameters related to functions normally provided as a wireless slave device such as carrier sense, back-off, or discard of a frame based on the carrier sense, back-off, and the like for traffic estimation in a predetermined channel. As a result, the wireless slave unit can select and connect to an access point suitable for connection with little additional processing.

Embodiments according to the present invention will be described below with reference to the drawings.
[Example]
[System overview]

  FIG. 1 is an overall view of a system according to the present invention. Many wireless slave units and access points 102 to 104 are arranged in a predetermined space. The wireless slave device 101 is a wireless slave device according to the present invention, and the other wireless slave devices (no code) are those of the prior art that are connected to the access point having the strongest received radio wave intensity.

  As can be seen from the figure, the physical distance from each access point to the wireless slave device 101 is that the access point 102 is closest, then the access point 103, and the farthest is the access point 104. Therefore, the radio wave intensity from the access point received by the wireless slave device 101 should be strongest at the access point 102 and weakest at the access point 104. For this reason, if it is a prior art, the wireless subunit | mobile_unit 101 will be connected to the access point 102. FIG.

However, in the present invention, the access point to be connected is not determined based solely on the radio wave intensity. Hereinafter, the operation of the wireless slave device 101 according to the present invention will be described in detail using the functional block (FIG. 2) and the operation flow (FIG. 3) of the wireless slave device 101.
[Function block of wireless slave unit]

FIG. 2 is a functional block diagram of the wireless slave device 101. The channel scanning unit 201 checks the traffic of all channels by the wireless slave unit 101.
It is a means for setting channels in order. Therefore, the means described below is implemented in the channel set by the channel scanning means 201. The channels set by this means are all channels that can be used by the wireless slave device 101.

  The carrier sense means 202 is means for detecting whether or not there is a carrier (carrier wave) in a predetermined channel. This operation is performed at a back-off time described later.

  The back-off time management means 203 manages the time for the wireless slave device 101 to transmit a wireless frame. Note that the wireless slave device 101 cannot transmit a frame during the back-off time.

  The carrier sense timeout detection means 204 is a means for detecting that the carrier sense means 202 has continued to sense a carrier for a predetermined time based on the back-off time described above. When a carrier is detected during the predetermined time, it means that communication is frequently performed by another wireless device and traffic is congested.

  The timeout occurrence count counting means 205 is a means for counting (counting) the number of times the above-described carrier sense timeout has occurred.

  The frame transmission unit 206 is a unit that transmits a radio frame. Note that this frame is transmitted after the back-off time has ended.

  The frame collision detection unit 207 is a unit that detects a collision of transmitted frames. When a collision is detected, a back-off time (retransmission standby time) corresponding to the number of times is calculated by a known calculation formula. Note that this calculation formula is generally expressed as a product of a random value corresponding to the number of collisions and a fixed time (slot time).

  In other words, the backoff occurrence number counting means 208 is a means for counting the number of transmitted frame collisions. When the wireless device detects the collision of the frames transmitted by the frame transmission means 206, the wireless device waits for retransmission of the collided frames for the time specified by the back-off time.

  The retransmission number determination means 209 is a means for determining whether or not the number of retransmissions of a lost frame due to a collision has reached a predetermined number.

  The frame discarding unit 210 is a unit that discards the frame when the retransmission of the frame has reached a predetermined number of times. A discarded frame is a frame whose retransmission has been canceled.

  The frame discard number counting means 211 is a means for counting the number of discarded frames.

  The table updating unit 212 updates an access point management table 213 to be described later based on information from the timeout occurrence number counting unit 205, the backoff occurrence number counting unit 208, and the frame discard number counting unit 211.

  The access point management table 213 is a table stored in a storage area (not shown) provided in the wireless slave device 101, and manages predetermined parameters for each access point as shown in FIG.

  Specifically, in addition to the BSSID (MAC address), channel used, radio wave intensity, timeout occurrence count, backoff occurrence count, and frame discard count for each access point, points calculated based on these parameters are stored. .

  The calculation formula for points is arbitrary, but the number of timeout occurrences, the number of backoff occurrences, and the number of frame discards have a negative correlation with points. This point is a value for estimating whether or not the target access point is preferable as the connection destination, and indicates that the higher the point, the more preferable as the connection destination. That is, this point is a value calculated using the fact that timeouts, backoffs, and frame discards are more likely to occur in situations where traffic is congested. In addition to these parameters, it is also possible to take into account conventionally used radio wave intensity in calculating points. Furthermore, it is possible to select an access point to be connected from only one of the parameters. Alternatively, an access point to be connected may be selected by calculating points by assigning different weights to each parameter.

  These parameters are not values acquired only for traffic measurement, but are acquired by processing that the wireless slave device 101 should originally perform. For this reason, there is almost no need to cause the wireless slave device 101 to perform additional processing, and traffic can be estimated.

The access point connection unit 214 is a unit that determines and connects an access point to be connected based on information in the access point management table 213. Of course, the access point connected here is the access point with the most traffic. In the example of FIG. 4, the BSSID with the highest point is the access point with 667788. Note that the access point connection unit 214 can execute a similar function in roaming for switching the connection from an already connected access point to another access point in addition to the function of simply connecting to the access point.
[Operation flow of wireless slave unit]

  The operation flow of the wireless slave device 101 will be described with reference to FIG. This is particularly the case when the wireless slave device 101 tries to transmit a predetermined wireless frame.

  In step 301, channel setting is performed. Below, the traffic of the channel set here is measured.

  In step 302, a back-off time is started. Specifically, the above-described back-off time management unit 203 starts counting.

In step 303, the carrier is sensed, and in step 304, it is determined whether a timeout has occurred. If it is determined that a timeout has occurred, the process proceeds to step 308; otherwise, the process proceeds to step 305.
[When carrier sense timeout has not occurred]

  In step 305, it is determined whether the back-off time has ended. If it has ended, the process proceeds to step 306. Otherwise, the process returns to step 302. This determination is performed by the back-off time management means 203 described above.

  In step 306, the frame is transmitted. In step 307, it is determined whether or not a frame collision has occurred. If there is a collision, the process proceeds to step 315; otherwise, the operation flow ends.

In step 315, the number of back-off occurrences is counted, and the process proceeds to step 309.
[When carrier sense timeout has occurred]

  In step 308, the number of times of occurrence of timeout is counted, and in step 309, it is determined whether or not the number of retransmissions of the frame has reached the upper limit. As a result of the determination, if it has reached, the process proceeds to step 310; otherwise, the process returns to step 302. Here, the number of retransmissions refers to the number of retransmissions of the frame in which collision occurred in step 307.

  In step 310, the number of discarded frames is discarded. In step 311, the number of discarded frames is counted. In step 312, the number of discarded frames managed in the access point management table 213 is updated.

  In step 313, it is determined whether or not all channels have been scanned. If scanning has been performed, the process proceeds to step 314. If not, the process returns to step 301.

In step 314, the access point management table 213 is referenced to connect to the access point with the most traffic margin.
[Summary]

  The wireless slave device disclosed in the present invention uses parameters related to functions normally provided as a wireless slave device such as carrier sense, back-off, or discard of a frame based on the carrier sense, back-off, and the like for traffic estimation in a predetermined channel. As a result, the wireless slave unit can select and connect to an access point suitable for connection with little additional processing.

Overall system diagram Functional block diagram of wireless handset Wireless slave unit operation flow Access point management table

202 Carrier sense means 204 Carrier sense timeout detection means 205 Timeout occurrence count counting means 206 Frame transmission means 207 Frame collision detection means 208 Backoff frequency count means 210 Frame discard means 211 Frame discard number count means 214 Access point connection means

Claims (6)

Frame transmission means for transmitting a frame in a predetermined channel;
Frame collision detection means for detecting a collision of frames transmitted by the frame transmission means;
Frame collision frequency counting means for counting the number of frame collisions detected by the frame collision detection means;
Carrier sensing means for detecting a carrier wave on the predetermined channel for a predetermined time based on the number of frame collisions counted by the frame collision frequency counting means;
Carrier sense timeout detecting means for detecting that the carrier sense means has continued to detect a carrier wave for the predetermined time; and
A carrier sense timeout number counting means for counting the number of carrier sense timeouts detected by the carrier sense timeout detection means;
An access point connection means for selecting and connecting an access point to be connected based on the counted number of carrier sense timeouts;
Wireless handset equipped with. Frame transmission means for transmitting a frame in a predetermined channel;
Frame collision detection means for detecting a collision of frames transmitted by the frame transmission means;
Frame collision frequency counting means for counting the number of frame collisions detected by the frame collision detection means;
Frame retransmission canceling means for canceling retransmission of the frame transmitted by the frame transmitting means based on the counted number of frame collisions;
Frame cancellation frequency counting means for counting the number of times the frame retransmission cancellation means cancels;
An access point connection means for selecting and connecting an access point to be connected based on the counted number of frame cancellations;
Wireless handset equipped with. The access point connection means is operable as a roaming means for changing an already connected access point to another access point.
The wireless slave device according to claim 1 or 2 , characterized in that Wireless cordless handset
Frame transmission means for transmitting a frame in a predetermined channel;
Frame collision detection means for detecting a collision of frames transmitted by the frame transmission means;
Frame collision frequency counting means for counting the number of frame collisions detected by the frame collision detection means;
Carrier sensing means for detecting a carrier wave on the predetermined channel for a predetermined time based on the number of frame collisions counted by the frame collision frequency counting means;
Carrier sense timeout detecting means for detecting that the carrier sense means has continued to detect a carrier wave for the predetermined time; and
A carrier sense timeout number counting means for counting the number of carrier sense timeouts detected by the carrier sense timeout detection means;
An access point connection means for selecting and connecting an access point to be connected based on the counted number of carrier sense timeouts;
Program to make it work. Wireless cordless handset
Frame transmission means for transmitting a frame in a predetermined channel;
Frame collision detection means for detecting a collision of frames transmitted by the frame transmission means;
Frame collision frequency counting means for counting the number of frame collisions detected by the frame collision detection means;
Frame retransmission canceling means for canceling retransmission of the frame transmitted by the frame transmitting means based on the counted number of frame collisions;
Frame cancellation frequency counting means for counting the number of times the frame retransmission cancellation means cancels;
An access point connection means for selecting and connecting an access point to be connected based on the counted number of frame cancellations;
Program to make it work. The access point connection means is operable as a roaming means for changing an already connected access point to another access point.
The program according to claim 4 or 5 , characterized by the above-mentioned.