KR20100025946A - Terminal apparatus using wireless lan and method for allocating bandwidth thereof - Google Patents

Abstract

PURPOSE: A wireless LAN terminal and a bandwidth allocation method thereof are provided to control the tradeoff between total yield and fairness. CONSTITUTION: A parameter processing unit(210) periodically receives a beacon frame from an AP(Access Point). The beacon frame includes a scheduling index and scheduling mode. If the scheduling mode is a congestion control window base mode, a congestion control window setup unit calculates a congestion control window value of a terminal based on a preset data transfer rate and the scheduling index of the terminal. A data transmitting unit(240) performs scheduling according to the calculated congestion control window value and transmits the result to the AP.

Description

Wireless LAN terminal and bandwidth allocation method using same {Terminal Apparatus Using Wireless LAN and Method for Allocating Bandwidth}

The present invention relates to a WLAN terminal and a bandwidth allocation method using the same, and more particularly, to a carrier access multiple access collision avoidance (Carrier Sense Multiple Access / Collision Avoidance, hereinafter 'CSMA / CA') medium access control method in a WLAN. will be.

In the uplink of the WLAN according to the prior art, data is basically transmitted using a CSMA / CA medium access control method.

The CSMA / CA medium access control method waits for a predetermined waiting time in order to minimize a collision in data transmission between a plurality of terminals and an access point (hereinafter referred to as an 'AP'), and then transmits data. That is, the plurality of terminals waits for a waiting time = random [0, a congestion window (hereinafter referred to as 'CW') and transmits data.

Therefore, the plurality of terminals prevent a data transmission collision transmitted from each terminal because the waiting time is long when the CW value is large and the waiting time is short when the CW value is small before data transmission.

In addition, the CSMA / CA medium access control method uses a lot of channels when the frame length is increased by varying the transmission frame length (referred to as 'TL') transmitted from each terminal. Use less.

The basic CSMA / CA media access control method uses the same CW value or the same TL value.

As shown in FIG. 1, when each terminal transmits data to an access point, a data transmission rate varies according to distance.

That is, each terminal assumes that the maximum speed for transmitting data to the access point is 11Mbps when the distance is close, and 1Mbps when the distance is far.

In this case, the basic CSMA / CA medium access control method has the same waiting time and the frame length is the same, and the terminal with the maximum data transmission rate of 1 Mbps occupies the channel long, and the terminal with the maximum data transmission rate of 11 Mbps accesses the channel. Occupy short.

Therefore, in all terminals, the average yield (data amount / data transmission time) becomes equal to the average yield of a terminal having a minimum data transmission rate of 1 Mbps. As a result, the average yield of each terminal is adjusted to a terminal having a minimum transmission rate. Leveling).

In order to solve such a problem, the present invention is to provide a WLAN terminal using a CSMA / CA medium access control method in a wireless LAN and a bandwidth allocation method using the same.

According to an aspect of the present invention, there is provided a WLAN terminal comprising: a parameter processor configured to periodically receive a beacon frame from an access point, the beacon frame including a scheduling index and a scheduling mode; When the scheduling mode is a congestion control window based mode, a congestion control window value of the terminal based on a preset data transmission rate and the scheduling index of the terminal—the congestion control window value is proportional to the congestion control window value in proportion to the data transmission speed of the terminal. A congestion control window setting unit for calculating a smaller value; And a data transmitter for scheduling data according to the calculated congestion control window value and transmitting data to the access point.

In accordance with an aspect of the present invention, a WLAN terminal includes: a parameter processor configured to periodically receive a beacon frame from an access point, the beacon frame including a scheduling index and a scheduling mode; When the scheduling mode is a frame length based mode, the frame length value of the terminal based on a preset data transmission rate and the scheduling index of the terminal—The frame length value is proportional to the data transmission rate of the terminal. A frame length setting unit for calculating a large value; And a data transmitter for scheduling data according to the calculated frame length value and transmitting data to the access point.

According to an aspect of the present invention, there is provided a method for allocating a bandwidth by (a) periodically receiving a first beacon frame from the access point, the first beacon frame including a first scheduling index and a first scheduling mode; Extracting and storing the first scheduling index and the first scheduling mode from the received first beacon frame; (b) if the first scheduling mode is a congestion control window based mode, calculating a congestion control window value of the terminal based on a first data transmission rate of the terminal and the first scheduling index; And (c) scheduling data according to the calculated congestion control window value to transmit data to the access point.

According to the above configuration, the present invention provides a WLAN terminal and a bandwidth allocation method capable of adjusting a trade-off relationship between overall yield and fairness using the CSMA / CA medium access control method in a WLAN.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, “block”, etc. described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. It can be implemented as.

2 is a diagram illustrating a configuration of a wireless LAN wireless data network according to an embodiment of the present invention.

In the following, an embodiment of the present invention describes the contents based on IEEE 802.11b, but is equally applicable to a wireless LAN network using a CSMA / CA scheme such as IEEE 802.11a / g.

The wireless data network according to the embodiment of the present invention includes an AP 100 and a plurality of terminals 200.

The AP 100 periodically transmits a beacon frame for performing synchronization and initialization with the terminal to the terminal 200. Here, the beacon frame includes a scheduling index and a scheduling mode. Here, the scheduling index is a fairness adjustment coefficient for variously adjusting the trade-off relationship between the average yield fairness of the terminal 200 and the overall yield maximized. The aforementioned scheduling mode will be described in detail with reference to FIG. 3.

Accordingly, the AP 100 may change the scheduling index and the scheduling mode in order to adjust the trade-off relationship between overall yield and fairness of the terminal 200.

The plurality of terminals 200 receive a scheduling index and a scheduling mode from the AP 100, calculate a CW value or a TL value, and transmit the scheduled data to the AP 100 based on the calculated CW value or TL value. .

Each terminal 200 transmits the scheduled data to the AP 100 at a predetermined data transmission rate, and receives a response signal ACK from the AP 100.

Each terminal 200 transmits data to the AP 100 more than a predetermined number of times (for example, 10 times) at the data transmission rate described above, and then receives a response signal ACK from the AP 100 more than a predetermined number of times. If it is determined that the channel environment is good, the data transmission rate is increased by one step and transmitted to the AP 100.

On the contrary, each terminal 200 transmits data to the AP 100 more than a predetermined number of times (for example, twice) at a data transmission rate, and thus prevents receiving the response signal ACK from the AP 100 more than a predetermined number of times. If it is determined that the channel environment is bad, the data transmission speed is lowered by one step and transmitted to the AP 100. For example, each terminal 200 may be set to a data transmission rate of 1 Mbps, 2.2 Mbps, 5 Mbps, 11 Mbps, 10 times after transmitting 1 Mbps data to the AP 100, 10 times response from the AP 100 When the signal is received, the next data is sent at 2.2Mbps.

Next, the WLAN terminal 200 in the wireless data network will be described in detail with reference to FIG. 3. Hereinafter, the plurality of terminals 200 described above refer to the WLAN terminal 200.

3 is a block diagram schematically showing an internal configuration of a WLAN terminal 200 according to an embodiment of the present invention.

The WLAN terminal 200 according to the embodiment of the present invention includes a parameter processor 210, a CW setter 220, a TL setter 230, and a data transmitter 240.

When the parameter processor 210 receives the beacon frame from the AP 100, the parameter processor 210 extracts and stores a scheduling index and a scheduling mode (CW-based mode or TL-based mode) included in the beacon frame.

In the WLAN, each terminal 200 has a CW-based mode for adjusting the size of CW and a TL-based mode for adjusting the frame length in order to efficiently distribute the fairness of the average yield.

When the scheduling mode received from the AP 100 is a CW-based mode, the CW setting unit 220 calculates a CW value through the following Equation 1.

는 스케줄링 지수,

는 i번째 단말(200)의 성공적으로 프레임을 송신할 경우의 프레임 송신 시간,

는 송신 속도가 11Mbps인 단말(200)의 성공적으로 프레임을 송신할 경우의 프레임 송신 시간을 의미한다.here,

Is the scheduling index,

Frame transmission time when the i-th terminal 200 successfully transmits a frame,

Denotes a frame transmission time when a frame is successfully transmitted by the terminal 200 having a transmission rate of 11 Mbps.

In the CW-based mode, the transmission frame length is equally applied to all the terminals 200.

The CW value may be calculated through the following [Equation 2], which is the same as that of [Equation 1] and the expression is different.

=

=

를 32로 가정하면, 데이터 전송 속도가 1Mbps인 경우, CW값이 (11/1)32 = 352이 되며, 데이터 전송 속도가 11Mbps인 경우, CW값이 (11/11)32=32가 된다. 즉, 단말(200)은 데이터 전송 속도가 빠를수록 CW값이 작아지고 이에 따라 데이터를 전송할 대기 시간이 짧아지기 때문에 단말(200)의 평균 수율(Throughput)이 커진다.For example, for 802.11b, data rates are 1 Mbps, 2.2 Mbps, 4 Mbps, 11 Mbps,

When 32 is assumed, the CW value becomes (11/1) 32 = 352 when the data transfer rate is 1Mbps, and the CW value becomes (11/11) 32 = 32 when the data transfer rate is 11Mbps. In other words, the faster the data transmission rate, the smaller the CW value and the shorter the waiting time for data transmission. Accordingly, the terminal 200 increases the average throughput of the terminal 200.

For example, each terminal 200 has an average yield proportional to the data transmission rate, such as 7 Mbps, 3 Mbps, 2 Mbps, 0.5 Mbps when the data transmission speed of the terminal 200 is 1Mbps, 2.2Mbps, 4Mbps, 11Mbps. Yield is high.

The CW-based mode allocates a smaller CW value to the high speed terminal 200 so that the high speed terminal 200 waits a short time before data transmission, and the high speed terminal 200 frequently transmits data. This allows higher average yields.

When the scheduling mode received from the AP 100 is a TL-based mode, the TL setting unit 230 calculates a TL value through Equation 3 below.

는 i번째 단말(200)의 데이터 전송 속도이고,

는 데이터 전송 속도가 11Mbps인 단말(200)의 프레임 길이를 의미한다(예를 들어,

는 4096, 10000등으로 설정할 수 있다.). TL 기반 모드에서는 CW값을 모든 단말(200)에 동일하게 적용한다.here,

Is the data transmission rate of the i-th terminal 200,

Means the frame length of the terminal 200 having a data transmission rate of 11 Mbps (for example,

Can be set to 4096, 10000, etc.). In the TL-based mode, the CW value is equally applied to all the terminals 200.

In the TL-based mode, the average yield of the high-speed terminal 200 is increased by allocating a larger TL value to the terminal 200 having a high data transmission rate.

If the data transmitter 240 applies the CW value or TL value calculated by the CW setting unit 220 and the TL setting unit 230 to the CSMA / CA protocol, the data transmitter 240 transmits data according to the scheduling index and the scheduling mode. To send.

Next, the bandwidth allocation method will be described in detail with reference to FIG. 4.

4 is a diagram illustrating a bandwidth allocation method according to an embodiment of the present invention.

The parameter processor 210 receives the first beacon frame from the AP 100, extracts and stores the first scheduling mode and the first scheduling index included in the received first beacon frame (S100).

When the first scheduling mode is the CW-based mode, the CW setting unit 220 calculates a first CW value using the above-described Equation 2, based on the first data transmission rate and the first scheduling index. (S102).

When the first scheduling mode is the TL-based mode, the TL setting unit 230 calculates a first TL value using the above-described Equation 3, ie, based on the first data transmission rate and the first scheduling index. (S104).

The data transmitter 240 transmits the data to the AP 100 by applying the calculated first CW value or the first TL value to the CSMA / CA protocol (S106).

Thereafter, if necessary, the AP 100 may change one or both of a scheduling method and a scheduling index in order to adjust a tradeoff relationship between the overall yield and fairness of the terminal 200.

The parameter processor 210 receives the second beacon frame from the AP 100, extracts and stores a second scheduling mode and a second scheduling index included in the received second beacon frame (S108). Here, the second scheduling mode and the second scheduling index mean a scheduling mode and a scheduling index in which the first scheduling mode and the first scheduling index are changed in order to adjust the trade-off relationship between overall yield and fairness.

When the second scheduling mode is the CW-based mode, the CW setting unit 220 calculates the second CW value using the above-described Equation 1, ie, based on the second data transmission rate and the second scheduling index. (S110).

When the second scheduling mode is the TL-based mode, the TL setting unit 230 calculates a second TL value by using the above Equation 3, ie, based on the second data transmission rate and the second scheduling index. (S112).

The data transmitter 240 transmits the data to the AP 100 by applying the calculated second CW value or the second TL value to the CSMA / CA protocol (S114).

5 is a view showing a trade-off relationship between the overall yield and fairness of the terminal 200 according to an embodiment of the present invention.

In order to adjust the trade-off relationship between overall yield and fairness, the AP 100 changes one or both of a scheduling method and a scheduling index and periodically transmits the changed information in a beacon frame.

The WLAN terminal 200 receives a new scheduling method and an index from the AP 100 to calculate a CW value or a TL value.

> 1인 경우, 1보다 큰 정수배의 CW값 또는 TL값으로 증감한다(예를 들면,

). At this time, the scheduling index is

> 1, increase or decrease by an integer multiple of CW value or TL value greater than 1 (for example,

).

In this case, the WLAN terminal 200 has a lower average yield in the case of the low speed terminal 200 and an average yield in the high speed terminal 200. Here, the high speed terminal 200 and the low speed terminal 200 are determined as the high speed terminal 200 when the speed is higher than the reference data transmission rate in proportion to the data transmission speed, and the low speed terminal 200 when the speed is small.

In other words, when the scheduling index is larger than the reference value, the WLAN terminal 200 increases the overall yield of the terminal 200 and decreases the fairness of the terminal 200.

< 1인 경우, 1보다 작은 정수배의 CW값 또는 TL값으로 증감한다(예를 들면,

). 이러한 경우, 무선랜 단말(200)은 저속도 단말(200)인 경우 평균 수율이 소폭으로 떨어지고, 고속도 단말(200)인 경우 평균 수율이 소폭으로 증가하게 된다.In contrast, the scheduling index

If <1, increase or decrease by an integer multiple of CW value or TL value smaller than 1 (for example,

). In this case, in the case of the low speed terminal 200, the WLAN terminal 200 slightly decreases the average yield, and in the case of the high speed terminal 200, the average yield slightly increases.

In other words, when the scheduling index is smaller than the reference value, the WLAN terminal 200 decreases the overall yield of the terminal 200 and increases the fairness of the terminal 200.

As a result, the scheduling index means that more resources are allocated to the high speed terminal 200 when the reference value is larger than the reference value, and more resources are allocated to the low speed terminal 200 when the scheduling index becomes smaller than the reference value. Here, the reference value means a specific point where the overall yield and fairness meet, as shown in FIG.

In consideration of this point, the AP 100 may efficiently use the network resource in consideration of the network resource environment and the data transmission speed of the terminal 200 using the scheduling index.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiments of the present invention, a recording medium on which the program is recorded, and the like. Such implementations may be readily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram illustrating a configuration in which each conventional terminal transmits data to an access point at different data transmission rates.

2 is a diagram illustrating a configuration of a wireless LAN wireless data network according to an embodiment of the present invention.

3 is a block diagram schematically illustrating an internal configuration of a WLAN terminal according to an embodiment of the present invention.

4 is a diagram illustrating a bandwidth allocation method according to an embodiment of the present invention.

5 is a view showing a trade-off relationship between the overall yield and fairness of the terminal according to an embodiment of the present invention.

Claims (8)

A parameter processor configured to periodically receive a beacon frame from the access point, the beacon frame including a scheduling index and a scheduling mode; When the scheduling mode is a congestion control window based mode, a congestion control window value of the terminal based on a preset data transmission rate and the scheduling index of the terminal—the congestion control window value is proportional to the congestion control window value in proportion to the data transmission speed of the terminal. A congestion control window setting unit for calculating a smaller value; And A data transmitter for scheduling data according to the calculated congestion control window value and transmitting the data to the access point. WLAN terminal comprising a. According to claim 1, The access point is a wireless LAN terminal, characterized in that for transmitting the modified scheduling index and the changed scheduling mode in the first beacon frame to the terminal to adjust the trade-off relationship between the overall yield and fairness of the terminal. According to claim 1, The congestion control window setting unit is a wireless LAN terminal, characterized in that when the scheduling index is greater than the reference value, the overall yield of the terminal is increased and the fairness of the terminal is reduced. According to claim 1, The congestion control window setting unit, when the scheduling index is smaller than the reference value, the wireless terminal, characterized in that the overall yield of the terminal is reduced and the fairness of the terminal is increased. A parameter processor configured to periodically receive a beacon frame from the access point, the beacon frame including a scheduling index and a scheduling mode; When the scheduling mode is a frame length based mode, the frame length value of the terminal based on a preset data transmission rate and the scheduling index of the terminal—The frame length value is proportional to the data transmission rate of the terminal. A frame length setting unit for calculating a large value; And A data transmitter for scheduling data according to the calculated frame length value and transmitting data to the access point. WLAN terminal comprising a. The method of claim 5, The access point is a wireless LAN terminal, characterized in that for transmitting the modified scheduling index and the changed scheduling mode in the first beacon frame to the terminal to adjust the trade-off relationship between the overall yield and fairness of the terminal. (a) periodically receiving a first beacon frame from the access point, wherein the first beacon frame includes a first scheduling index and a first scheduling mode, and in the received first beacon frame Extracting and storing a first scheduling index and the first scheduling mode; (b) if the first scheduling mode is a congestion control window based mode, calculating a congestion control window value of the terminal based on a first data transmission rate of the terminal and the first scheduling index; And (c) scheduling data according to the calculated congestion control window value and transmitting data to the access point Bandwidth allocation method comprising a. The method of claim 7, wherein After step (c), Receive a second beacon frame from the access point to adjust a trade off relationship between the overall yield and fairness of the terminal, the second beacon frame including a second scheduling index and a second scheduling mode; Extracting and storing the second scheduling index and the second scheduling mode in a second beacon frame; If the second scheduling mode is a frame length based mode, calculating a frame length value of the terminal based on a second data transmission rate of the terminal and the second scheduling index; And Scheduling according to the calculated frame length value and transmitting data to the access point Bandwidth allocation method further comprising.

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