KR20150095084A - AP To control Beacon Transmission Time, And Transmission Time Control Method Thereof - Google Patents

Abstract

The present invention relates to an access point to control beacon transmission time, and a transmission time control method thereof. The present invention previously measures the beacon period of another access point when access points are located in an overlapped communication region and can change beacon period to transmit a beacon to a period for avoiding it. An access point to control beacon transmission time according to the present invention calculates an external beacon period to the external beacon when the externa beacon is received from an external beacon, and transmits a beacon to a transmission time by calculating the transmission time which is overlapped with the external beacon period.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an access point capable of managing beacon transmission time,

The present invention relates to an access point capable of managing a beacon transmission time point and a transmission time management method using the access point. More particularly, when a plurality of access points are located in an overlapping communication area, beacon periods of other access points are measured in advance, To a beacon transmission time management capable of changing a beacon transmission period so as to transmit a beacon in a period, and a transmission time management method using the same.

Wireless LANs such as WiFi are increasingly used due to their ease of use and are being used as an essential element in the use of mobile devices such as smart phones, smart pads, and notebooks. As is known, Wi-Fi provides a wireless communication channel for wireless data communication, and an access terminal or an access point (AC) is constituted as an essential component.

The access point plays a role similar to that of the base station in the mobile communication system and confirms entry of a mobile device or a wireless device (hereinafter referred to as "wireless device") entering the communication area of the access point, It exchanges data with the device. To this end, the access point typically performs communication by radio in an area where data can be transmitted and received with the wireless device. The access point itself is connected to the host devices by the wire, transfers the data received by the wireless communication to the host device, To the wireless device.

These access points typically have a limited communication radius, such as 10m or 100m. However, the radius of the communication by the access point is often restricted by obstacles such as walls, structures, and steel frames, and there is a limitation in that communication can not be performed when the floor of the building is changed. In addition, since the access point is provided with a frequency or a frequency band for forming a wireless communication channel in one or a limited range, it is somewhat difficult to use the access point efficiently when there are many simultaneous users.

Therefore, when wireless communication is provided in a wide range of space, when a communication radius is narrowed due to an obstacle or the like, and when there is a plurality of wireless devices using a communication channel in the same space, And the like.

However, since the size of the allowed ISM frequency band is limited and a plurality of access points are operated in a limited space in need of a personal user of a communication service provider, and a plurality of access points overlap a frequency band overlapping with the same space There is a problem that the communication efficiency is lowered unexpectedly due to the arrangement. Specifically, the access point periodically transmits a beacon to its own communication radius, notifies the sleep mode wireless device that there is data to be transmitted and confirmed by the beacon, and manages the connected terminal.

However, since a plurality of access points using a single frequency or a single frequency band transmit beacons in a similar time unit, collision of beacons and actual transmission time due to excessive network occupation are insufficient. Such a beacon is difficult to grasp the nature of a very important message or a broadcast message. In particular, beacon occupies most of the transmission capacity of the entire network due to dense access points.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method and apparatus for measuring a beacon period of a different access point in advance when a plurality of access points are located in an overlapping communication area, And a method of managing a transmission time using the access point.

In order to achieve the above object, an access point capable of managing a beacon transmission time according to the present invention calculates an external beacon period for the external beacon when an external beacon from an external access point is received, Calculates a transmission time point and transmits the beacon at the transmission time point.

And the beacon includes a transmission traffic indication message (DTIM).

And the transmission time is determined so that the beacon is transmitted in a period in which the interval between the external beacon reception time points is the longest in the external beacon period.

And the external beacon is received from a plurality of external access points.

And the transmission time point is determined within one period in which all the external beacons of each of the plurality of external access points are received.

And the interval between the transmission timings is variable.

The transmission time is a transmission period having a constant period.

Wherein the external beacon is received from a plurality of external access points and the period of the external beacon transmitted from any one of the plurality of external access points is different from a period of the external beacon transmitted from the remaining access point .

And the external beacon period is calculated for one cycle length of the external beacon having the longest period of the external beacons.

The external access point may further include a plurality of repeaters for transmitting traffic information of the plurality of external access points.

And the transmission time is determined such that the beacon is transmitted between the external beacon transmission point of the external access point in which traffic is relatively small among a plurality of the external access points.

According to another aspect of the present invention, there is provided a transmission time management method using an access point capable of managing a beacon transmission time point, including: receiving an external beacon from an external access point; The access point calculating an external beacon period for the external beacon; Calculating a transmission time at which the access point does not overlap the external beacon period; And transmitting the beacon at the transmitting time point by the access point.

And the beacon includes a transmission traffic indication message (DTIM).

Wherein the calculating of the transmission time determines the transmission time so that the beacon is transmitted in a period in which the access point has a longest interval between the external beacon reception times in the external beacon period.

And the step of receiving the external beacon includes receiving the external beacon from the plurality of external access points to the access point.

The calculating of the transmission time point is characterized in that the access point is determined within one period in which all of the external beacons of each of the plurality of external access points are received.

And the interval between the transmission timings is variable.

The transmission time is a transmission period having a constant period.

Wherein the external beacon receiving step includes receiving the external beacon from a plurality of external access points and the period of the external beacon transmitted from any one of the plurality of external access points And has a period different from the period of the external beacon to be transmitted.

Calculating the external beacon period is characterized in that the access point calculates the external beacon period with respect to one cycle length of the external beacon having the longest period of the external beacons.

The step of calculating the external beacon period may further include collecting traffic information of each of the plurality of external access points, and transmitting the traffic information to the access point.

The access point determines the transmission time point so that the beacon is transmitted between the external beacon transmission point of the external access point having a relatively small amount of traffic among a plurality of the external access points.

An access point capable of managing beacon transmission time according to the present invention and a transmission time management method using the same can measure beacon periods of other access points in advance when a plurality of access points are located in an overlapping communication area, The beacon transmission period is changed and transmitted so as to prevent retransmission due to collision and collision due to beacon transmission and thus waste of resources of the access point.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a configuration of a Wi-Fi network for explaining an access point capable of managing beacon transmission time according to the present invention; FIG.
2 is an exemplary diagram for explaining superposition of beacon signals;
3 is an exemplary diagram showing a periodic spectrum when the external beacon periods are the same;
4 is an exemplary diagram illustrating a periodic spectrum when an external beacon period differs from one access point to another.
5 is a diagram illustrating a configuration of a Wi-Fi network having a repeater.
6 is a diagram illustrating an example of a beacon period for explaining the determination of a transmission time point in consideration of traffic;
FIG. 7 is a flowchart for explaining a transmission time management method using an access point capable of managing beacon transmission time according to the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be noted that the drawings denoted by the same reference numerals in the drawings denote the same reference numerals whenever possible, in other drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. And certain features shown in the drawings are intended to be illustrative, not limiting, or reduced, or simplified, and the drawings and elements thereof are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

FIG. 1 is a diagram illustrating a configuration of a Wi-Fi network for explaining an access point capable of managing beacon transmission time according to the present invention.

1, an access point 20 (20a, 20b, 20c, 20d) according to the present invention forms a wireless communication area for relaying a wireless terminal 30 within an area with an upper apparatus 10 (10a, 10b) . For this, the access point 20 may be configured as one or more and connected to the parent device 10 as shown.

The host device 10 is a device that provides data communication such as the Internet to the wireless terminal 30 connected through the access point 20, and the host device 10 may be composed of a plurality of groups. For example, the host device 10 may be an ePDG 11 (11a, 11b), a DHCP 12 (12a, 12b), a gateway 13 (13a, 13b). The Enhanced Packet Datagram (ePDG) 11 performs security and authentication for the Wi-Fi network so that the wireless network 30 connected to the access point 20 and the access point 20 can be connected to the mobile communication system. The Dynamic Host Configuration Protocol (DHCP) server 12 provides a dynamic IP (Internet Protocol) to the wireless terminal 30 connected through the access point 20 or the access point 20. The gateway 13 serves to connect a network formed by the wireless terminal 30, the access point 20 and the host device 10 to another network. Here, the host device 10 is shown as an example, and various modifications are possible.

The wireless terminal 30 is a smart phone, a smart pad, a mobile phone capable of data communication, a notebook, and various wireless communication terminals capable of data communication. The wireless terminal 30 enters a wireless communication area formed by the access point 20, forms a communication channel with the access point 20, and performs data communication through the formed communication channel. The wireless terminal 30 receives the beacon signal broadcasted periodically from the access point 20 and confirms the presence, the location, and the like of the accessible access point 20. [

An access point (AP) 20 plays a role of relaying the wireless terminal 30 and the upper apparatus 10. For this purpose, the access point 20 communicates with the wireless terminal 30 that has a wireless communication radius capable of forming a wireless communication channel with the wireless terminal 30 and enters or positions within the wireless communication radius, 30) can use the data communication. The access point 20 periodically transmits a beacon signal within its radio communication radius. This beacon signal is broadcast to notify the wireless terminal 30 of the presence of the access point 20, as well as to provide information for communication. The wireless terminal 30 confirms the accessible access point 20 according to the reception of the beacon signal and accesses the access point 20 by the contents of the beacon signal. In particular, the beacon signal includes a delivery traffic indication message (DTIM). The DTIM informs the specific wireless terminal 30 that there is data to be transmitted. The access point 20 communicates with the wireless terminal 30 using a designated band or a single frequency, and transmits the beacon signal through a designated frequency (hereinafter referred to as a frequency band). .

In particular, the access point 20 of the present invention may include other access points 20a, 20b, 20c, 20d (or 20a, 20b, 20c, 20d) to prevent collision due to beacon signal transmission between adjacent access points 20a, ) Beacon signal transmission period and transmits the beacon signal at a time when the collision can be minimized. Hereinafter, for the sake of convenience of description of the present invention, a main body for receiving a different beacon signal to determine a beacon transmission period will be described as an example of an access point 20a, and the remaining access points 20b, 20c, The present invention will be described as an external access point. This is for convenience of description, and all the access points 20 can thus determine the beacon transmission point of own by accumulating the beacon signal of the other access point.

In particular, the access point 20a receives the beacon signal transmitted from the external access points 20b, 20c, and 20d using the same frequency as the frequency assigned to the access point 20a, and determines a transmission time point for avoiding a collision.

The access point 20a receives an external beacon signal transmitted from the external access points 20b, 20c, and 20d, and calculates a beacon period or a beacon spectrum therefrom. Then, the access point 20a determines the transmission time so that the beacon signal of its own is transmitted in the calculated beacon period or the beacon spectrum in the longest interval between the beacon signals, or determines the transmission time . Hereinafter, this will be described in more detail.

2 is an exemplary diagram for explaining superposition of beacon signals.

Referring to FIG. 2, the access point 20 includes a plurality of access points 20 installed in a place where a large number of wireless terminals 30 exist, where a plurality of shaded areas such as diffraction, blocking, .

At this time, the communication radius 21 between the access points 20a, 20b, 20c, and 20d may be overlapped as shown in FIG. If the communication radius is overlapped in this manner, a problem may arise, especially when the access points 20a, 20b, 20c, and 20d use the same frequency. Specifically, the access points 20a, 20b, 20c, and 20d using the same frequency need to occupy the frequency during transmission of the data frame or the beacon signal, not only for transmission of the data frame but also for transmission of the beacon signal, . That is, when one of the access points 20a, 20b, 20c, and 20d transmits a beacon signal or a data frame, the other access points 20a, 20b, 20c, and 20d do not transmit beacon signals or data frames The beacon signal or the transmission / reception of the data frame can be performed smoothly.

In particular, in the case of the beacon signal, it is periodically transmitted within the communication radius 21, which is performed by each access point 20. Such a collision due to superposition of beacon periods may cause a continuous collision in a situation where the access points have a certain period, and may cause a collision between the access point and the corresponding access point such as a transmission period error of the terminal due to the beacon transmission failure, It adversely affects the transmission of all the terminals to which it belongs and increases the burden on the entire network.

As shown in FIG. 2, when the access point 20a is located within the communication radius of the external access points 20b, 20c, and 20d using the same frequency band, the access point 20a is connected to the external access points 20b, 20c, And can analyze the beacon signal. Therefore, the access point 20a receives and records all the beacon signals transmitted from the access points 20b, 20c, and 20d using the same frequency band in which a collision may occur, so that each of the external access points 20b, 20c, and 20d ), Or a beacon signal reception time point of all the access points 20b, 20c, and 20d, in that order. By using the transmission (or reception period) or the spectrum of the external beacon, the beacon transmission point of time can be determined. This will be described in more detail below.

3 and 4 are diagrams for explaining the beacon transmission time determination according to the external beacon period. FIG. 3 shows a periodic spectrum when the external beacon periods are the same, and FIG. 4 illustrates a case where the external beacon period is different for each access point Fig. 2 is a diagram showing an example of a periodic spectrum in the case of Fig.

Referring to FIG. 3 and FIG. 4, when the reception timing of each external beacon is indicated with the lapse of time, it becomes the same as that shown in FIG. 3 and FIG. As can be seen from this, it can be confirmed that there is a time during which the beacon signal is not transmitted between each time point A. The access point of the present invention determines a beacon transmission time by searching for a time when the beacon signal is not sent, and transmits a beacon signal at the determined beacon transmission time point, thereby generating a collision caused by the plurality of access points 20 using the same frequency Can be avoided or prevented.

Referring to FIG. 3, more specifically, FIG. 3 is an exemplary diagram illustrating a method of determining a transmission time when the beacon transmission periods of the access points 20a, 20b, 20c, and 20d are the same. When the reception point of the beacon signal received by the access point 20a from the external access points ap1 to ap9 is represented in a spectrum form according to the time, it can be expressed as shown in FIG.

At this time, a blank period B in which a beacon signal is not received is formed between AP1 and AP2 and between AP2 and AP3 when the beacon signal is received, such as between AP2 and AP3. The access point selects any one of the empty periods (B) formed between the received external beacons and uses it as its beacon transmission point. For example, it can be seen that the blank period B1 formed between AP3 and AP4 is longer than the other blank periods. In this way, the access point 20a (Target AP) can select the longest period of the blank period and allow its transmission point to be located in the selected period. In addition, it is possible to acquire a plurality of blank periods (B) having a relatively long time in the blank period (B). In this case, the access point (20a) B may be arbitrarily selected to determine the transmission time, and the method of determining the transmission time may vary, but the present invention is not limited thereto.

Particularly, in order to confirm such a blank period B, the access point 20a receives all the beacon signals for all of the external access points at least once, that is, after receiving all the beacon signals of the external access points AP1 to AP9, And judges and selects the period (B).

On the other hand, FIG. 4 is an example of an example in which beacon signal transmission periods of the respective external access points AP1 to A9 are different. As shown in FIG. 3, the beacon signals transmitted from the external access points AP1 to AP9 may have the same period, and the transmission time may be the same. For example, most of the external access points AP1 to AP9 may transmit beacons at the same frequency with a beacon signal transmission period of 100 ms and a period of 100 ms at the same time. In this case, the access point 20a can determine its own transmission time by the method as shown in FIG.

As shown in FIG. 4, the beacon transmission period of all or some of the external access points AP1 to AP3 may be different. As a concrete example, it can be assumed that the beacon period of AP1 is the longest, and the beacon periods of AP2 and AP3 are of relatively short transmission periods. In this case, after one period of the beacon of the access point AP1 having the longest period is received, the transmission time point can be determined by selecting a blank period B which does not overlap with the beacon period of the external access points AP1 to AP3.

Specifically, when the beacon periods of the external access points AP1 to AP3 are different, it is necessary to select the transmission time point by receiving the beacon signal having the longest beacon period at least one cycle, that is, twice. This is because a signal of a long beacon period may not be received at a time during one period of the beacon signal having a short period and an external access point AP1 having a beacon period longer in time selected by the access point 20a Of the beacon period.

That is, the access point AP1 receives the external beacon during one beacon period of the external access point AP1 having the longest beacon period to check the blank period B between the beacon signals, Lt; RTI ID = 0.0 > beacon < / RTI >

The proposed beacon transmission point may be configured as a transmission period having a predetermined period, or may be a variable point in time not having a constant period and fixed at each transmission, but the present invention is not limited thereto.

Meanwhile, the transmission time may be affected by the traffic of the access points 20a, 20b, 20c, and 20d AP1 to AP9. Specifically, when traffic is concentrated on specific access points 20a, 20b, 20c, 20d, AP1 to AP9, frequency occupation and beacon transmission delay may occur due to transmission of data frames. Therefore, the transmission time may be determined in consideration of this. A specific example of this is shown in Figs. 5 and 6. Fig.

5 and 6 are diagrams for explaining the determination of a transmission time in consideration of traffic. FIG. 5 is a diagram illustrating a configuration of a Wi-Fi network having a repeater, and FIG. Fig. 7 is an exemplary diagram showing a beacon cycle for explanation. Fig.

5 and 6, a Wi-Fi network including a repeater collects traffic information from the access points 120 (120a, 120b, 120c, and 120d) in the configuration shown in FIG. 1, And a repeater 150 for delivering the signal to the base station. Hereinafter, the second embodiment will be described with reference to FIG. 5 and FIG. 6, and detailed description of the same configuration as the above embodiment will be omitted.

The repeater 150 communicates with each access point 120 to request a communication to the access point 120, that is, a connection request by the wireless terminal 30, Collect information. Then, the repeater 150 generates the traffic data of the access point 120 and the degree of convergence of traffic through the collected information, and transmits the traffic data to the access point 120 that requires the traffic data.

The access point 120 receives the traffic data from the repeater 150 and applies it to the method of FIGS. 1 to 4 to determine the transmission time point. This will be described in more detail with reference to FIG. 6 separately.

Here, the repeater 150 may be a relay device that simply collects traffic information to generate traffic data and transmits the traffic data to the access point 120, or the access point 120 may be configured to include such a role.

Meanwhile, referring to FIG. 6, AP1 and AP2 among AP1 to AP3 denote access points where traffic is concentrated. AP1 and AP2 have delayed beacon transmission time due to concentration of traffic or have a relatively long vacancy period B between beacon transmission. When the transmission time is determined between AP1, AP2, and AP2 and another beacon signal reception time, the beacon signal and data collide due to the data transmitted by AP1 to AP2, so that transmission of the beacon signal can be failed and delayed.

Therefore, the access point 120a receives the beacon signal or the beacon signal received from the external access points relatively less traffic concentration among the external access points 120b, 120c, 120d, and AP1 to AP3, Determines its own transmission time point in a blank period Bx formed between beacon periods, and transmits a beacon signal at a determined transmission time point.

The access point 120a can efficiently transmit its own beacon signal while avoiding collision with data or beacon signals exchanged between the external access points 120b, 120c, 120d, AP1 to AP3 and the wireless terminal 30 It becomes possible to transmit it.

FIG. 7 is a flowchart for explaining a transmission time management method using an access point capable of managing beacon transmission time according to the present invention.

Referring to FIG. 7, the transmission time management method according to the present invention includes an external beacon reception step S10, an external beacon period calculation step S20, and a transmission time calculation step S30, S40). ≪ / RTI >

The external beacon reception step S10 is a step in which the access points 20a and 120a receive all the external beacons transmitted from the plurality of external access points 20b, 20c, 20d, 120b, 120c and 120d.

The external beacon period calculating step S20 is a step in which the access points 20a and 120a calculate the external beacon period or the reception time spectrum of the external beacon using a plurality of external beacons. Particularly, in the external beacon period calculating step S20, the traffic data collected by the repeater 150 can be received as described in the second embodiment.

The transmission time calculating step S30 is a step in which the access point determines its own beacon transmission time point using the calculated external beacon period or spectrum. In the transmission time calculating step S30, the access points 20a and 120a transmit the transmission data to the mobile station at any one time point or at a predetermined condition (for example, a blank period having a time length longer than a predetermined time) It is possible to determine that the transmission time point is located in any one of the blank periods B that satisfy. Particularly, the access points 20a and 120a transmit the beacon transmission point of time between the beacon transmission points of the external access points 20 and 120 having low traffic according to the traffic data collected and transmitted by the repeater in the traffic data reception step S40 Can be determined.

The traffic data reception step S40 is a step in which the repeater collects traffic information from a plurality of external access points 20 and 120 to create traffic data for each of the access points 20 and 120 and transmits the traffic data to the access points 20a and 120a .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, . ≪ / RTI > Accordingly, such modifications are deemed to be within the scope of the present invention, and the scope of the present invention should be determined by the following claims.

10: host device
11: EPDG
12: DHCP
13: GW
20, 120: access point
21: Communication radius
30: wireless terminal
150: Repeater

Claims (22)

And when the external beacon from the external access point is received, calculates an external beacon period for the external beacon, calculates a transmission time not overlapping with the external beacon period, and transmits the beacon at the transmission time point Point-of-access-capable access points. The method according to claim 1,
Wherein the beacon includes a transmission traffic indication message (DTIM). 3. The method of claim 2,
The transmission time
And the beacon is determined to be transmitted in a period in which the interval between external beacon reception points in the external beacon period is the longest. The method of claim 3,
Wherein the external beacon is received from a plurality of external access points. 5. The method of claim 4,
The transmission time
Wherein the external beacon of each of the plurality of external access points is determined within one cycle in which all of the external beacons are received. The method of claim 3,
Wherein an interval between the transmission time points is variable. The method of claim 3,
Wherein the transmission time is a transmission period having a predetermined period. 3. The method of claim 2,
Wherein the external beacon is received from a plurality of external access points,
Wherein the period of the external beacon transmitted from any one of the plurality of external access points is different from the period of the external beacon transmitted from the other access points. point. 9. The method of claim 8,
Wherein the external beacon period is calculated for one period length of the external beacon having the longest period of the external beacons. 3. The method of claim 2,
Wherein the external access point comprises a plurality of external access points,
Further comprising: a repeater for transmitting traffic information of a plurality of the external access points. 11. The method of claim 10,
The transmission time
Wherein the beacon transmission time point is determined such that the beacon is transmitted between the external beacon transmission point of the external access point in which traffic is relatively small among a plurality of the external access points. Receiving an external beacon from an external access point;
The access point calculating an external beacon period for the external beacon;
Calculating a transmission time at which the access point does not overlap the external beacon period; And
And transmitting the beacon at the time of transmission of the beacon from the access point. 13. The method of claim 12,
Wherein the beacon includes a transmission traffic indication message (DTIM). 14. The method of claim 13,
The step of calculating the transmission time
Wherein the beacon transmission time determination unit determines the transmission time point so that the beacon is transmitted in a period in which the access point has a longest interval between the external beacon reception time points in the external beacon period. . 15. The method of claim 14,
The step of receiving the external beacon
And the external beacon is received from the plurality of external access points at the access point. 16. The method of claim 15,
The step of calculating the transmission time
Wherein the access point is determined within one cycle of the reception of all of the external beacons of each of the plurality of external access points. 15. The method of claim 14,
And the interval between the transmission time points is variable. 15. The method of claim 14,
Wherein the transmission time is a transmission period having a predetermined period. 14. The method of claim 13,
The external beacon receiving step
Wherein the external beacon is received from a plurality of external access points,
Wherein the period of the external beacon transmitted from any one of the plurality of external access points is different from the period of the external beacon transmitted from the other access point. A method for managing transmission time using a point. 20. The method of claim 19,
The step of calculating the external beacon period
Wherein the access point calculates the external beacon period for one cycle length of the external beacon having the longest period among the external beacons. 14. The method of claim 13,
The step of calculating the external beacon period
Collecting traffic information of each of the external access points having a plurality of repeaters; and
And transmitting the traffic information to the access point. The method of claim 1, wherein the beacon transmission time management method comprises: 22. The method of claim 21,
The transmitting time determining step
Wherein the access point determines the transmission time point so that the beacon is transmitted between the external beacon transmission point of the external access point in which traffic is relatively small among a plurality of the external access points Point Access Point A method of managing one transmission point.

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