KR20160032400A - Method, apparatus, and system for enhancing the performance of frame aggregation algorithm in wilreless lan - Google Patents

Abstract

The present invention relates to a method to improve a frame aggregation performance in a wireless LAN system, a device thereof, and a system thereof. A new link aggregation technique is applied in introducing a frame aggregation technique so as to expect improvement in performance. The present invention is able to be used in a variety of communication devices.

Description

{METHOD, APPARATUS, AND SYSTEM FOR ENHANCING THE PERFORMANCE OF FRAME AGGREGATION ALGORITHM IN WILRELESS LAN}

The present invention relates to a method, an apparatus, and a system for improving performance of a frame aggregation technique in a wireless LAN system.

Recently, as the spread of mobile devices has expanded, wireless LAN technology capable of providing fast wireless Internet service has attracted much attention. Wireless LAN technology is a technology that allows wireless devices such as smart phones, smart pads, laptop computers, portable multimedia players, and embedded devices to wirelessly access the Internet based on wireless communication technology in close range.

Since the initial wireless LAN technology supports a speed of 1 to 2 Mbps through frequency hopping, spread spectrum, and infrared communication using a 2.4 GHz frequency through Institute of Electrical and Electronics Engineers (IEEE) 802.11, (Orthogonal Frequency Division Multiplex) can be applied to support a maximum speed of 54Mbps. In IEEE 802.11, IEEE 802.11 has also improved the quality of service (QoS), the access point (AP) protocol compatibility, security enhancement, radio resource measurement, wireless access vehicular interworking with external networks, wireless network management, and the like are being put into practical use or under development.

In IEEE 802.11, IEEE 802.11b supports communication speeds of up to 11 Mbps using frequencies in the 2.4 GHz band. IEEE 802.11a, which has been commercialized since IEEE 802.11b, uses the frequency of the 5GHz band instead of the 2.4GHz band, thereby reducing the interference effect compared to the frequency of the highly congested 2.4GHz band. Using OFDM technology, To 54Mbps. However, IEEE 802.11a has a short communication distance compared to IEEE 802.11b. IEEE 802.11g, like IEEE 802.11b, uses a frequency of 2.4GHz band to achieve a communication speed of up to 54Mbps and has received considerable attention because it meets backward compatibility. It is in the lead.

IEEE 802.11n is a technical standard established to overcome the limitation of communication speed which is pointed out as a vulnerability in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and to extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with data rates of up to 540 Mbps or higher, and uses multiple antennas at both ends of the transmitter and receiver to minimize transmission errors and optimize data rates. It is based on Multiple Inputs and Multiple Outputs (MIMO) technology. In addition, this specification uses a coding scheme for transmitting multiple duplicate copies in order to increase data reliability, and may also use Orthogonal Frequency Division Multiplex (OFDM) to increase the speed.

Recently, the need for a new wireless LAN system to support a very high throughput (VHT) that is higher than the data processing speed supported by the IEEE 802.11n has been increasing, Is emerging. IEEE 802.11ac supports wide bandwidth (80MHz ~ 160MHz) at 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, early 11ac chipsets will also support operation in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. At this time, 802.11ac supports bandwidth up to 40MHz at 2.4GHz. Theoretically, according to this specification, the wireless LAN speed of multiple terminals can be at least 1 Gbps and the maximum single link speed can be at least 500 Mbps. This is accomplished by extending the concept of wireless interfaces accepted in 802.11n, including wider radio frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multiuser MIMO, and high density modulation (up to 256 QAM). In addition, IEEE 802.11ad is a method of transmitting data using a 60 GHz band instead of the existing 2.5 GHz / 5 GHz. IEEE 802.11ad is a transmission standard that provides a maximum speed of 7Gbps using beamforming technology, and is suitable for streaming high bit rate video such as large amount of data and uncompressed HD video. However, the 60GHz frequency band has a disadvantage in that it is difficult to pass through obstacles, and therefore, it can be used only between devices in a near space.

SUMMARY OF THE INVENTION The present invention provides a method, apparatus, and system for a wireless local area network (LAN).

The present invention proposes a novel link adatation technique for improving performance in frame aggregation technology.

According to the embodiment of the present invention, it is expected that the application performance of the new link aggregation technology can be improved in introducing Frame Aggregation technology when performing wireless communication.

The present invention is applicable to various communication devices such as a station or an access point using a wireless LAN, a station using a cellular communication, or a base station.

1 illustrates a wireless LAN system according to an embodiment of the present invention.
2 illustrates an independent BSS that is a wireless LAN system according to another embodiment of the present invention.
3 is a block diagram illustrating a configuration of an STA according to an embodiment of the present invention.
4 is a block diagram illustrating a configuration of an AP according to an embodiment of the present invention.
5 schematically illustrates a step in which a STA associated with an embodiment of the present invention establishes a link with an AP.
6 illustrates a passive scanning method of an STA according to an embodiment of the present invention.
7 illustrates an active scanning method of an STA according to an embodiment of the present invention.
FIG. 8 shows a format of an A-MPDU frame related to Frame Aggregation technology according to an embodiment of the present invention.
FIG. 9 shows a format of a Block ACK Bitmap frame according to an embodiment of the present invention.
FIG. 10 illustrates a method of determining the transmission success and the transmission failure of the A-MPDU through the overall analysis of the Block ACK Bitmap according to an example of the present invention.
FIG. 11 illustrates a method of determining a transmission success and a transmission failure of an A-MPDU through partial analysis of a Block ACK Bitmap according to an exemplary embodiment of the present invention.
FIG. 12 is a block diagram illustrating a link adaptation algorithm newly proposed for determining a transmission mode according to an exemplary embodiment of the present invention. Referring to FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

Structure of wireless LAN system

1 illustrates a wireless LAN system according to an embodiment of the present invention.

A WLAN system includes one or more Basic Service Sets (BSSs), which represent a collection of devices that can successfully communicate and communicate with one another. In general, a BSS can be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS). FIG. 1 shows the infrastructure BSS.

1, an infrastructure BSS (BSS1, BSS2) includes one or more stations (STA-1, STA-2, STA-3, STA-4, STA-5) and a distribution service A distribution system (DS) for connecting access points (PCP / AP-1, PCP / AP-2) and a plurality of access points (PCP / AP-1 and PCP / AP- .

A station (STA) is an arbitrary device including a medium access control (MAC) conforming to the IEEE 802.11 standard and a physical layer interface for a wireless medium, And a non-AP station (STA). The station for wireless communication includes a processor and a transceiver, and may further include a user interface unit, a display unit, and the like according to an embodiment. The processor creates a frame to be transmitted over the wireless network, or processes a frame received through the wireless network, and performs various processes for controlling the other stations. The transceiver is functionally connected to the processor and transmits and receives frames over the wireless network for the station.

An access point (AP) is an entity that provides a connection to a distribution system (DS) via a wireless medium for its associated station. In the infrastructure BSS, the communication between the APs and the STAs not connected to each other is performed via the AP. However, when the direct link is established, direct communication is also possible between STAs not connected to the AP. In the present invention, the AP is used as a concept including a PCP (Personal BSS Coordination Point), and broadly includes a central controller, a base station (BS), a node-B, a base transceiver system (BTS) Controller, and the like.

A plurality of infrastructure BSSs may be interconnected via a distribution system (DS). At this time, a plurality of BSSs connected through the DS are referred to as an extended service set (ESS). STAs included in the ESS can communicate with each other, and STAs that are not connected to the AP in the same ESS can move from one BSS to another while seamlessly communicating.

2 illustrates an independent BSS that is a wireless LAN system according to another embodiment of the present invention. In the embodiment of FIG. 2, the same or corresponding parts as those of the embodiment of FIG. 1 are not described.

Since the BSS-3 shown in FIG. 2 is an independent BSS and does not include an AP, all the stations STA-6 and STA-7 are not connected to the AP. Independent BSSs are not allowed to connect to the DS and form a self-contained network. In the independent BSS, each of the stations STA-6 and STA-7 can be directly connected to each other.

STA (station) configuration

3 is a block diagram illustrating a configuration of a station according to an embodiment of the present invention.

The STA 100 according to the embodiment of the present invention includes a processor 110, one or more network interface cards (NIC) 120, a user interface unit 140, a display unit 150, Memory 160 may be included.

First, the network interface card 120 is a module for performing wireless LAN connection, and may be embedded in the STA 100 or externally. According to an embodiment of the present invention, the network interface card 120 may include a plurality of network interface card modules 120_1 to 120_n using different frequency bands. For example, the network interface card modules 120_1 to 120_n may include network interface card modules of different frequency bands such as 2.4GHz, 5GHz, and 60GHz. According to an embodiment of the present invention, the STA 100 may include at least one network interface card module using a frequency band of 6 GHz or more and at least one network interface card module using a frequency band of 6 GHz or less. Each of the network interface card modules 120_1 to 120_n can perform wireless communication with an AP or an external STA according to a wireless LAN standard of a frequency band supported by the corresponding network interface card module 120_1 to 120_n. The network interface card 120 operates only one network interface card module 120_1 to 120_n at a time or simultaneously connects a plurality of network interface card modules 120_1 to 120_n together according to the performance and requirements of the STA 100 .

3, the plurality of network interface card modules 120_1 to 120_n of the STA 100 are shown separately from each other, and the MAC / PHY layers of the network interface card modules 120_1 to 120_n are connected to each other It operates independently. However, the present invention is not limited to this, and the STA 100 may be provided with a plurality of network interface card modules of different frequency bands integrated into one chip.

Next, the user interface unit 140 includes various types of input / output means provided in the STA 100. That is, the user interface unit 140 can receive user input using various input means, and the processor 110 can control the STA 100 based on the received user input. Also, the user interface unit 140 may perform output based on the instruction of the processor 110 using various output means.

Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects such as a content executed by the processor 110 or a user interface based on a control command of the processor 110. [ In addition, the memory 160 stores a control program used in the STA 100 and various data corresponding thereto. Such a control program may include an access program necessary for the STA 100 to make an access to an AP or an external STA.

The processor 110 of the present invention may execute various instructions or programs and process data within the STA 100. [ In addition, the processor 110 controls each unit of the STA 100 described above, and can control data transmission / reception between the units. According to an embodiment of the present invention, the processor 110 controls the communication operation such as the sector sweep signal transmission / reception of the STA 100 and the corresponding feedback signal transmission / reception.

In addition, the processor 110 executes a program for making a connection with the AP stored in the memory 160, receives the communication setup message transmitted by the AP, and transmits the communication setup message to the STA 100 included in the communication setup message, And requests access to the AP according to the information on the priority condition of the STA 100 (n). A detailed description thereof will be described later.

The STA 100 shown in FIG. 3 is a block diagram according to an exemplary embodiment of the present invention. Blocks shown separately are logically distinguished from elements of a device. Thus, the elements of the device described above can be mounted as one chip or as a plurality of chips depending on the design of the device. In addition, some components of the STA 100, such as the mobile communication module 130, the user interface unit 140, and the display unit 150, may be selectively provided to the STA 100 in the exemplary embodiment of the present invention. have.

AP (Access Point) Configuration

4 is a block diagram illustrating a configuration of an AP according to an embodiment of the present invention.

As shown, an AP 200 according to an embodiment of the present invention may include a processor 210, a NIC (Network Interface Card) 220, and a memory 160. In FIG. 4, the same or corresponding parts as those of the STA 100 of FIG. 3 among the configurations of the AP 200 will be omitted.

Referring to FIG. 4, an AP 200 according to the present invention includes a network interface card 220 for operating a BSS in at least one frequency band. 3, the network interface card 220 of the AP 200 may also include a plurality of network interface card modules 220_1 to 220_m using different frequency bands. That is, the AP 200 according to the embodiment of the present invention may include two or more network interface card modules of different frequency bands, for example, 2.4 GHz, 5 GHz, and 60 GHz. Preferably, the AP 200 may include at least one network interface card module using a frequency band of 6 GHz or more and at least one network interface card module using a frequency band of 6 GHz or less. Each of the network interface card modules 220_1 to 220_m can perform wireless communication with the STA according to a wireless LAN standard of a frequency band supported by the corresponding network interface card modules 220_1 to 220_m. The network interface card 220 operates only one network interface card module 220_1 to 220_m at a time or simultaneously connects a plurality of network interface card modules 220_1 to 220_m together according to the performance and requirements of the AP 200 .

Next, the memory 260 stores a control program used in the AP 200 and various data corresponding thereto. Such a control program may include an access program for managing the connection of the STA. In addition, the processor 210 controls each unit of the AP 200, and can control data transmission / reception between the units.

In addition, the processor 210 executes a program for making a connection with a station stored in the memory 260, and transmits a communication setup message to one or more STAs 100. In response to a connection request of the STA 100, The communication setup message includes information on the connection preference condition of each station. A detailed description thereof will be described later.

Link setting step

5 schematically illustrates a step in which a STA associated with an embodiment of the present invention establishes a link with an AP.

Referring to FIG. 5, the STA 100 according to the present invention may be divided into three stages of scanning, authentication, and association. The scanning step is a step in which the STA 100 acquires access information of the BSS operated by the AP 200. [ As a method for performing scanning, a passive scanning technique (S101) for acquiring information using only a beacon message periodically transmitted by the AP and a STA transmits a probe request to the AP (S103), an active scanning method for receiving a probe response from the AP (S105) and acquiring access information.

Upon receiving the wireless access information successfully in the scanning step, the STA 100 transmits an authentication request (S107a) and receives an authentication response (S107b) to perform the authentication procedure.

After performing the authentication procedure at the successful IEEE 802.11 layer,  Steps S109a and S109b may be performed, and the step 802 of performing 802.1X-based authentication and step S113 of acquiring an IP address through DHCP may be performed. The AS 300 is an authentication server that processes STA 100 and 802.1X-based authentication, and may be physically coupled to the AP 200 or exist as a separate server.

6 illustrates a passive scanning method of an STA according to an embodiment of the present invention.

Referring to FIG. 6, the first STA 110 according to the present invention receives a beacon message periodically transmitted from a first AP 210 and a second AP 220 located nearby, .

7 illustrates an active scanning method of an STA according to an embodiment of the present invention.

Referring to FIG. 7, the first STA 110 according to the present invention transmits a probe request message to acquire information of an AP located nearby and transmits a corresponding probe response message to the first AP 210 and the first AP 210, respectively. 2 AP 220 to obtain wireless access information of APs.

o New Link Adatpation Techniques to Improve Frame Aggretaion Technology

The IEEE 802.11n standard improves the transmission rate by introducing Aggreated MAC Protocol Data Unit (A-MPDU) and Block ACK to the MAC layer. A-MPDU is a collection of a plurality of MPDUs having the same Receiver Address, Modulation and Colding Scheme (MCS), and ACK Policy to form a single direct frame. Each MPDU integrated in the A-MPDU is called a sub-frame. 8 and 9 are diagrams illustrating formats of an A-MPDU and a Block ACK frame according to an embodiment of the present invention. A process of exchanging an A-MPDU and a Block ACK can be described as follows.

8, the A-MPDU is generated and transmitted to the receiving side. The receiver receives the MPDU's success and failure, and records the result in the Block ACK bitmap To the transmitter. Thereafter, the transmitter aggregates the failed transmission frames and the frames to be newly transmitted through the bitmap of the received Block ACK to generate a new A-MPDU and transmit the new A-MPDU. The A-MPDU can have up to 64 subframes, and the Block ACK has a 64-bit bitmap to represent the transmission result. The bitmap element is set to 1 when the transmission of the corresponding subframe is successful, It has a value of 0.

The IEEE 802.11 PHY layer supports multiple transmission modes in which different modulation schemes and channel coding schemes (MCS) are combined and transmitted. However, the current WLAN standard does not define a standard mechanism for rate adaptation technology that appropriately selects the multiplex transmission mode according to the state of the wireless channel. In ARF (Automatic Rate Fallback) technology, which is applied to most wireless LAN devices, the transmission mode is sequentially adjusted using the success of the frame and the timer.

In brief, if the transmission fails in two consecutive frames in the current transmission mode, the transmission mode is lowered to the next lower transmission mode in the current transmission mode. If successive transmission of 10 frames is successful, Mode, the transmission rate is increased in a higher transmission mode. In addition, when a certain time elapses after the decrease of the transmission rate, the transmission mode is automatically increased by one step, and the transmission is attempted in the high mode. However, the ARF technology has a high probability that the transmission mode will be lowered when the channel state change is large, and it takes a long time to adjust to the appropriate transmission mode. This causes a problem of degrading the efficiency of wireless channel use, but it is relatively easy to implement and is currently being introduced in most wireless LAN devices.

In the case of applying ARF technology to A-MPDU transmission, all subframes are successfully transmitted without any error through Block ACK Bitmap on transmission side. If an error occurs even in one subframe, it is regarded as transmission failure do. In order to maximize the transmission rate, it is necessary to increase the integration ratio. However, even if the channel state is the same, when the frame length is short, the error rate of the subframe located in the latter half increases. MCS) may be set low to cause performance degradation.

In this specification, a modified ARF technique is proposed to solve the above problems. In the present invention, the ARF scheme is used as it is, and a transmission failure or transmission failure determination part of a previously transmitted frame is newly proposed for setting a transmission mode (MCS) in a wireless LAN system to which a frame aggregation scheme is applied.

As shown in FIG. 10, when N subframes are integrated and transmitted, it is determined that the transmission is successful if the block ACK bitmap has a number of '1' or more among the N bits, and otherwise, the transmission is determined to be unsuccessful. The corresponding a value changes according to the channel state, and the number exceeding '1' can be compared with the a value based on all of the N bits. Alternatively, as shown in FIG. 11, 'Can be compared with a value.

12, an operation scheme of the Link Adaptation algorithm will be described based on the above-described technology. The transmitter transmits the Block ACK bitmap information received from the receiver to the bitmap analysis decision unit and the bitmap information transmission unit. The bitmap analysis method decision unit decides whether to analyze all of Nbit or upper or lower part of Nbit. The decision criterion can be changed depending on the place where the wireless LAN is installed (outdoors, indoor, subway station, etc.) or the number of the floating population, and it can be determined based on the distribution of the RSSI value of the receiver as a recognition method for the surrounding environment. The bitmap information transfer unit transfers all or part of Nbit to the transfer success / failure judgment unit based on the information received from the bitmap analysis decision unit. If the number of '1' s is greater than a, the transmission success / failure determination unit determines that the transmission is successful. If the number of '1' s is greater than a, the transmission success / failure determination unit determines that the transmission is unsuccessful. To the decision part. In the MCS decision section, the transmission mode is lowered by one step in case of 2 transmission failures consecutively in the same manner as the existing ARF technology. In case of 10 successful transmission, the transmission mode is increased by one step and the determined transmission mode To the signal modulation section.

The setting criterion of the 'a' value, which is the threshold for determining the transmission success or the transmission failure, can be determined as follows. Similar to the bitmap analysis plan decision section, it can be changed depending on the place where the current wireless LAN is installed (outdoor, indoor, subway station, etc.) or the number of the floating population. The default value, a, is operated with the value of N, which is the Frame Aggregation Size. However, if the transmitter exceeds the specific reference point based on statistics such as standard deviation or dispersion of RSSI values of multiple receivers, . It is possible to set the range of the statistical value such as the standard deviation or the variance of the RSSI value step by step and to reduce the value of the a value. The statistics of RSSI can be set in 1 day or 1 hour, but it does not limit the specific range.

One embodiment of the present invention may also be embodied in the form of a recording medium including instructions executable by a computer, such as program modules, being executed by a computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium can include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

While the methods and systems of the present invention have been described in connection with specific embodiments, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (1)

Method, apparatus and system for wireless LAN

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