KR101615253B1 - Method for using dynamic bandwidth operation adaptively in mobile communication system and apparatus for same - Google Patents

Abstract

A method of adaptively using DBO in a wireless communication system and an electronic device therefor are disclosed. The apparatus collects predetermined time data through a transceiver that transmits and receives data to and from an external device and a transceiver, calculates a collision loss rate due to hidden traffic based on the collected data, and transmits the calculated collision loss rate to a predetermined reference value or And a control unit for comparing the loss rate due to the RTS / CTS transmission overhead of the calculated or updated DBO (Dynamic Bandwidth Operation), and if the collision loss rate is larger than the reference value or the loss rate due to overhead, Activate. Thus, the device efficiency can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for adaptively using a DBO in a wireless communication system,

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for adaptively using a DBO in a wireless LAN system.

Recently, various wireless communication technologies have been developed along with the development of information communication technologies. The wireless LAN (WLAN) may be a home network, an enterprise, a home network, a home network, a home network, a home network, a home network, a home network, A technology that enables wireless access to the Internet from a specific service area.

In order to overcome the limitation of the communication speed which is pointed out as a weak point in the wireless LAN, a recent technical standard introduces a system that increases the speed and reliability of the network and extends the operating distance of the wireless network.

In recent years, the bandwidth of each packet can be variably selected at the transmitting and receiving end of the wireless LAN. This technique can be called Dynamic Bandwidth Operation (DBO). DBO is an optional feature defined in the 802.11ac standard and is not necessarily implemented in a wireless LAN terminal, but it is a necessary protocol for efficiently operating a wide bandwidth of 20 MHz or more.

When the DBO is used in the wireless LAN system, the transmitter transmits a VHT (Very High Throughput) RTS (Request To Send) used in the DBO to the receiver, the receiver transmits the VHT CTS to the transmitter, .

On the other hand, when data is transmitted in the wireless LAN system, hidden traffic, which is invisible at the transmitting end and affects the receiving end, may be generated.

In the wireless LAN system, a method for preventing or reducing hidden traffic using the DBO is required.

Loss Differentiation (Moving onto High-Speed Wireless LANs)

It is an object of the present invention to provide a method and apparatus for adaptively using DBO in a wireless LAN system.

It is another object of the present invention to provide a method and apparatus for preventing or reducing hidden traffic by adaptively using DBO.

Also, there is provided a method for reducing the overhead loss rate caused by the use of DBO, reducing the frequency of unnecessary NAV (Network Allocation Vector) setting of peripheral devices due to the use of DBO, increasing the frequency reuse ratio, and an apparatus therefor have.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

A method for adaptively using Dynamic Bandwidth Operation (DBO) in a wireless local area network (WLAN) system according to an embodiment of the present invention includes a first step of collecting predetermined time data, Calculate

Step 2, calculating the collision loss rate by a predetermined reference value or a pre-

Compared with the overhead loss rate due to the updated Dynamic Bandwidth Operation (DBO).

A third step and a step of determining whether the collision loss rate is larger than the reference value or the overhead loss rate

A fourth step of DBO activation for a predetermined time period.

The method may also deactivate the DBO if the collision loss rate is less than the reference value or the rate of loss due to the overhead.

Also, the method may activate the DBO prior to the first step and calculate the loss rate due to the overhead of the activated DBO.

In addition, the method may further include a step of updating the collision loss rate when retransmission of the A-MPDU occurs.

The method may further include the step of updating the collision loss rate when the MPDU loss is continuously generated without retransmission of the A-MPDU.

The method may further comprise the step of updating the loss rate due to the DBO overhead by the activated DBO.

An electronic device adaptively using a Dynamic Bandwidth Operation (DBO) in a wireless LAN system includes a transceiver for transmitting and receiving data to and from an external device, and a transceiver for collecting predetermined time data through the transceiver, And a control unit for comparing the calculated collision loss rate with a predetermined reference value or a loss rate due to an RTS / CTS transmission overhead of a previously calculated or updated DBO, When the loss rate is larger than the reference value or the loss rate due to the overhead, DBO can be activated for a predetermined time.

Also, the control unit of the electronic device may deactivate the DBO if the collision loss rate is less than the reference value or the loss rate due to the overhead.

In addition, the controller may activate the DBO before calculating the predetermined time data, and may calculate or update the loss rate due to the overhead of the activated DBO.

In addition, the control unit may update the collision loss rate when retransmission of the A-MPDU occurs.

In addition, if the A-MPDU retransmission does not occur and the MPDU loss is continuously generated, the control unit can update the collision loss rate.

In addition, the controller can update the loss rate due to the DBO overhead by the activated DBO.

According to an embodiment of the present invention, hidden traffic can be reduced by using DBO adaptively in a wireless LAN system.

In addition, the overhead loss rate due to the use of DBO is reduced, and unnecessary frequency of NAV (Network Allocation Vector) setting of peripheral devices due to DBO use can be reduced.

Another object of the present invention is to provide a method and apparatus for reducing the overhead loss rate caused by the use of DBO and reducing the frequency of unnecessary NAV (Network Allocation Vector) setting of peripheral devices due to the use of DBO.

The effects obtained in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description .

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the technical features of the invention.
1 is a diagram showing an exemplary structure of an IEEE 802.11 system to which the present invention can be applied.
2 is a diagram showing another exemplary structure of an IEEE 802.11 system to which the present invention can be applied.
3 is a diagram showing another exemplary structure of an IEEE 802.11 system to which the present invention can be applied.
4 is a diagram showing an exemplary structure of a WLAN system.
5 is a diagram illustrating a structure of a data link layer and a physical layer of an IEEE 802.11 system to which the present invention can be applied.
FIG. 6 is a diagram for explaining a general link setup process in a wireless LAN system to which the present invention can be applied.
FIG. 7 illustrates a MAC frame format of an IEEE 802.11 system to which the present invention can be applied.
FIG. 8 illustrates the HT format of the HT Control field in the MAC frame according to FIG.
FIG. 9 illustrates the VHT format of the HT Control field in the MAC frame according to FIG.
10 illustrates a PPDU frame format of an IEEE 802.11n system to which the present invention can be applied.
11 illustrates a VHT PPDU frame format of an IEEE 802.11ac system to which the present invention can be applied.
FIG. 12 is a diagram for explaining a backoff process in a wireless LAN system to which the present invention can be applied.
13 is a diagram for explaining a hidden node and an exposed node.
14 is a diagram for explaining RTS and CTS.
15 is a diagram illustrating the relationship of the IFS.
16 is a diagram illustrating DBO used in a wireless LAN system according to an exemplary embodiment of the present invention to reduce hidden traffic.
17 is a flowchart illustrating that DBO is adaptively used in a wireless LAN system according to an embodiment of the present invention.
18 is a flowchart specifically showing the flowchart shown in Fig.
19 illustrates a block diagram of a wireless device according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the IEEE 802 systems, 3GPP systems, 3GPP LTE and LTE-Advanced (LTE-Advanced) systems, and 3GPP2 systems, which are wireless access systems. That is, the steps or portions of the embodiments of the present invention that are not described in order to clearly illustrate the technical idea of the present invention can be supported by the documents. In addition, all terms disclosed in this document may be described by the standard document.

The following description is to be understood as illustrative and non-limiting, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access And can be used in various wireless access systems. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) using E-UTRA, adopting OFDMA in downlink and SC-FDMA in uplink. LTE-A (Advanced) is the evolution of 3GPP LTE.

For clarity of description, the IEEE 802.11 system is mainly described, but the technical features of the present invention are not limited thereto.

System General

1 is a diagram showing an exemplary structure of an IEEE 802.11 system to which the present invention can be applied.

The IEEE 802.11 architecture can be composed of a plurality of components, and their interaction can provide a WLAN that supports STA mobility that is transparent to the upper layer. A Basic Service Set (BSS) may correspond to a basic configuration block in an IEEE 802.11 LAN. In FIG. 1, two BSSs (BSS1 and BSS2) exist and two STAs are included as members of each BSS (STA1 and STA2 are included in BSS1 and STA3 and STA4 are included in BSS2) do. In Fig. 1, an ellipse representing a BSS may be understood as indicating a coverage area in which STAs included in the corresponding BSS maintain communication. This area can be referred to as a BSA (Basic Service Area). If the STA moves out of the BSA, it will not be able to communicate directly with other STAs in the BSA.

The most basic type of BSS in an IEEE 802.11 LAN is an independent BSS (IBSS: Independent BSS). For example, an IBSS may have a minimal form consisting of only two STAs. Also, the BSS (BSS1 or BSS2) of FIG. 1, which is the simplest form and the other components are omitted, may be a representative example of the IBSS. This configuration is possible when STAs can communicate directly. Also, this type of LAN may not be configured in advance, but may be configured when a LAN is required, which may be referred to as an ad-hoc network.

The STA's membership in the BSS can be changed dynamically, such as by turning the STA on or off, by the STA entering or leaving the BSS region, and so on. In order to become a member of the BSS, the STA can join the BSS using the synchronization process. In order to access all services of the BSS infrastructure, the STA must be associated with the BSS. This association can be set dynamically and can include the use of a Distribution System Service (DSS).

2 is a diagram showing another exemplary structure of an IEEE 802.11 system to which the present invention can be applied. In FIG. 2, components such as a distribution system (DS), a distribution system medium (DSM), and an access point (AP) are added in the structure of FIG.

The distance of the station-to-station directly from the LAN may be limited by the PHY performance. In some cases, the limits of such distances may be sufficient, but in some cases communication between stations at greater distances may be required. A distribution system (DS) can be configured to support extended coverage.

DS means a structure in which BSSs are interconnected. Specifically, instead of the BSSs existing independently as shown in FIG. 1, there may be a BSS as an extended type component of a network composed of a plurality of BSSs.

DS is a logical concept and can be specified by the characteristics of the distribution system medium (DSM). In this regard, the IEEE 802.11 standard logically distinguishes between a wireless medium (WM) and a distribution system medium (DSM). Each logical medium is used for different purposes and is used by different components. In the definition of the IEEE 802.11 standard, these media are not limited to the same or different. In this way, the flexibility of an IEEE 802.11 LAN architecture (DS structure or other network structure) can be described in that a plurality of media are logically different. That is, the IEEE 802.11 LAN structure can be variously implemented, and the LAN structure can be specified independently according to the physical characteristics of each implementation.

The DS may support the mobile device by providing seamless integration of a plurality of BSSs and by providing the logical services necessary to address the destination.

An AP refers to an entity that has access to the DS through WM and has STA functionality for the associated STAs. Data movement between the BSS and the DS can be performed through the AP. For example, STA2 and STA3 shown in FIG. 2 have a function of STA and provide a function of allowing the associated STAs (STA1 and STA4) to access the DS. Also, since all APs are basically STAs, all APs are addressable objects. The address used by the AP for communication on the WM and the address used by the AP for communication on the DSM do not necessarily have to be the same.

Data transmitted from one of the STAs associated with the AP to the STA address of the AP is always received at the uncontrolled port and can be processed by the IEEE 802.1X port access entity. Also, when the controlled port is authenticated, the transmitted data (or frame) may be forwarded to the DS.

3 is a diagram showing another exemplary structure of an IEEE 802.11 system to which the present invention can be applied. FIG. 3 conceptually illustrates an extended service set (ESS) for providing a wide coverage in addition to the structure of FIG.

A wireless network with arbitrary size and complexity may be comprised of DS and BSSs. In the IEEE 802.11 system, this type of network is referred to as an ESS network. An ESS may correspond to a set of BSSs connected to one DS. However, ESS does not include DS. The ESS network is characterized by an IBSS network in the LLC (Logical Link Control) layer. STAs included in the ESS can communicate with each other, and moving STAs can move from one BSS to another (within the same ESS) transparently to the LLC.

In IEEE 802.11, nothing is assumed for the relative physical location of the BSSs in FIG. 3, and both of the following forms are possible. BSSs can be partially overlapping, which is a form commonly used to provide continuous coverage. Also, the BSSs may not be physically connected, and there is no limitation on the distance between the BSSs logically. Also, the BSSs can be physically located at the same location, which can be used to provide redundancy. Also, one (or more) IBSS or ESS networks may physically exist in the same space as one (or more than one) ESS network. This may be the case when the ad-hoc network is operating at the location where the ESS network is located or when IEEE 802.11 networks physically overlap by different organizations are configured, or when two or more different access and security policies are required at the same location And the ESS network type in the case of the ESS.

4 is a diagram showing an exemplary structure of a WLAN system. In Fig. 4, an example of an infrastructure BSS including DS is shown.

In the example of FIG. 4, BSS1 and BSS2 constitute the ESS. In a WLAN system, the STA is a device that operates according to the IEEE 802.11 MAC / PHY specification. The STA includes an AP STA and a non-AP STA. Non-AP STAs are devices that are typically handled by the user, such as laptop computers and mobile phones. In the example of FIG. 4, STA1, STA3, and STA4 correspond to non-AP STA, and STA2 and STA5 correspond to AP STA.

In the following description, the non-AP STA includes a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS) , A mobile subscriber station (MSS), or the like. Also, the AP may be a base station (BS), a node-B, an evolved Node-B (eNB), a base transceiver system (BTS) , A femto base station (Femto BS), and the like.

5 is a diagram illustrating a structure of a data link layer and a physical layer of an IEEE 802.11 system to which the present invention can be applied.

5, the physical layer 520 may include a PLCP entity (Physical Layer Convergence Procedure Entity) 521 and a PMD entity (Physical Medium Dependent Entity) 522. The PLCP entity 521 connects the MAC sublayer 510 and the data frame. The PMD entity 522 wirelessly transmits and receives data to and from two or more STAs using the OFDM scheme.

Both the MAC sublayer 510 and the physical layer 520 may include conceptual management entities and may be referred to as a MLME (Media Sublayer Management Entity) 511 and a PLME (Physical Layer Management Entity) 523, respectively. These entities 511, 521 provide a hierarchical management service interface through the operation of a hierarchical management function.

In order to provide correct MAC operation, a Station Management Entity (SME) 530 may exist within each STA. The SME 530 collects the layer-based state information from the various layer management entities as a management entity independent of each layer or sets the values of specific parameters of each layer. The SME 530 may perform these functions on behalf of general system management entities and may implement standard management protocols.

These various entities can interact in various ways, and FIG. 5 shows an example of exchanging GET / SET primitives. The XX-GET.request primitive is used to request a value of a management information base attribute (MIB attribute), and the XX-GET.confirm primitive returns a corresponding MIB attribute value if the status is 'SUCCESS' ), Otherwise returns an error indication in the status field. The XX-SET.request primitive is used to request that the specified MIB attribute be set to the given value. If the MIB attribute implies a particular action, then this request requests execution of that particular action. And, if the XX-SET.confirm primitive has a status of 'SUCCESS', this means that the specified MIB attribute is set to the requested value. Otherwise, the status field indicates an error condition. If this MIB attribute implies a specific action, this primitive can confirm that the action has been performed.

As shown in FIG. 5, the MLME 511, the SME 530, the PLME 523, and the SME 530 transmit various primitives through an MLME_SAP (MLME_Service Access Point) 550 and a PLME_SAP (PLME_Service Access Point) Exchangeable. A primitive can be exchanged between the MLME 511 and the PLME 523 through an MLME-PLME_SAP (MLME-PLME_Service Access Point) 570.

Link Setup Process

FIG. 6 is a diagram for explaining a general link setup process in a wireless LAN system to which the present invention can be applied.

In order for a STA to set up a link to a network and transmit and receive data, the STA first discovers the network, performs authentication, establishes an association, establishes an authentication procedure for security, . The link setup process may be referred to as a session initiation process or a session setup process. Also, the processes of discovery, authentication, association, and security setting of the link setup process may be collectively referred to as an association process.

An exemplary link setup process will be described with reference to FIG.

In step S610, the STA may perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. That is, the STA must find a participating network in order to access the network. The STA must identify a compatible network before joining the wireless network. The process of identifying a network in a specific area is called scanning.

The scanning methods include active scanning and passive scanning.

FIG. 6 illustrates a network discovery operation that includes an exemplary active scanning process. The STA performing the scanning in the active scanning transmits the probe request frame and waits for a response in order to search for the existence of an AP in the surroundings while moving the channels. The responder sends a probe response frame in response to the probe request frame to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted the beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs in the IBSS transmit the beacon frame while the beacon frame is transmitted. For example, the STA that transmits the probe request frame on channel 1 and receives the probe response frame on channel 1 stores the BSS-related information included in the received probe response frame and transmits the next channel (for example, Channel) and perform scanning in the same manner (i.e., transmitting / receiving a probe request / response on the second channel).

Although not shown in Fig. 6, the scanning operation may be performed in a passive scanning manner. In passive scanning, the STA performing the scanning waits for the beacon frame while moving the channels. A beacon frame is one of the management frames in IEEE 802.11, and is transmitted periodically to notify the presence of a wireless network and allow the STA performing the scanning to find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame. In the IBSS, the beacon frames are transmitted while the STAs in the IBSS are running. Upon receiving the beacon frame, the scanning STA stores information on the BSS included in the beacon frame and records beacon frame information on each channel while moving to another channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame, moves to the next channel, and performs scanning in the next channel in the same manner.

Comparing active scanning with passive scanning, active scanning has the advantage of less delay and less power consumption than passive scanning.

After the STA discovers the network, the authentication procedure may be performed in step S620. This authentication process may be referred to as a first authentication process in order to clearly distinguish it from the security setup operation in step S640 described later.

The authentication process includes an STA transmitting an authentication request frame to the AP, and an AP transmitting an authentication response frame to the STA in response to the authentication request frame. The authentication frame used for the authentication request / response corresponds to the management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), a finite cyclic group Group), and the like. This corresponds to some examples of information that may be included in the authentication request / response frame, may be replaced by other information, or may include additional information.

The STA may send an authentication request frame to the AP. Based on the information included in the received authentication request frame, the AP can determine whether or not to allow authentication for the STA. The AP can provide the result of the authentication process to the STA through the authentication response frame.

After the STA is successfully authenticated, the association process may be performed in step S630. The association process includes an STA transmitting an association request frame to the AP, and in response, the AP transmitting an association response frame to the STA.

For example, the association request frame may include information related to various capabilities, a listening interval, a service set identifier (SSID), supported rates, supported channels, an RSN, , Supported operating classes, TIM broadcast request, interworking service capability, and the like.

For example, the association response frame may include information related to various capabilities, a status code, an association ID (AID), a support rate, an enhanced distributed channel access (EDCA) parameter set, a Received Channel Power Indicator (RCPI) A timeout interval (association comeback time), a overlapping BSS scan parameter, a TIM broadcast response, and a Quality of Service (QoS) map.

This corresponds to some examples of information that may be included in the association request / response frame, may be replaced by other information, or may include additional information.

After the STA is successfully associated with the network, a security setup procedure may be performed in step S640. The security setup process in step S640 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response. The authentication process in step S620 may be referred to as a first authentication process, May also be referred to simply as an authentication process.

The security setup process of step S640 may include performing a private key setup through a 4-way handshaking over an Extensible Authentication Protocol over LAN (EAPOL) frame, for example . In addition, the security setup process may be performed according to a security scheme not defined in the IEEE 802.11 standard.

Evolution of WLAN

In order to overcome the limitation of the communication speed in the wireless LAN, IEEE 802.11n exists as a relatively recently established technical standard. 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 a maximum data rate of 540 Mbps or higher, uses multiple antennas at both ends of a transmitter and a receiver to minimize transmission error and optimize data rate It is based on Multiple Inputs and Multiple Outputs (MIMO) technology.

With the spread of wireless LANs and the diversification of applications using them, there is a need for a new wireless LAN system to support higher throughput than the data processing rate supported by IEEE 802.11n. The next generation wireless LAN system supporting very high throughput (VHT: Very High Throughput) is a next version (IEEE 802.11ac, for example) of IEEE 802.11n wireless LAN system and has a MAC service access point (SAP) The IEEE 802.11 wireless LAN system is one of the newly proposed wireless LAN systems.

The next generation wireless LAN system supports multi-user multiple input multiple output (MU-MIMO) transmission in which a plurality of STAs simultaneously access a channel in order to utilize a wireless channel efficiently. According to the MU-MIMO transmission scheme, an AP can simultaneously transmit a packet to one or more MIMO-paired STAs. It is also discussed to support the operation of a wireless LAN system in whitespace. For example, the introduction of a WLAN system in a TV white space (TV WS), such as an idle frequency band (e.g., 54 MHz to 698 MHz band) due to the digitization of an analog TV, has been discussed as an IEEE 802.11af standard . However, this is merely an example, and the whitespace may be an authorized band that a licensed user may prefer to use. An authorized user is a user who is authorized to use an authorized band, and may be referred to as a licensed device, a primary user, an incumbent user, or the like.

For example, an AP and / or STA operating on a WS must provide protection for an authorized user. For example, if an authorized user such as a microphone already uses a specific WS channel, which is a frequency band that is divided in regulation so as to have a specific bandwidth in the WS band, And / or the STA can not use the frequency band corresponding to that WS channel. In addition, the AP and / or the STA should stop using the frequency band currently used for frame transmission and / or reception when the authorized user uses the frequency band.

Therefore, the AP and / or the STA must precede the process of determining whether a specific frequency band in the WS band can be used, in other words, whether or not there is an authorized user in the frequency band. Knowing whether or not there is a user authorized in a specific frequency band is called spectrum sensing. The spectrum sensing mechanism uses energy detection method and signature detection method. If the strength of the received signal is equal to or greater than a predetermined value, it is determined that the authorized user is in use, or it is determined that the authorized user is using the DTV preamble when the preamble is detected.

In addition, M2M (Machine-to-Machine) communication technology is being discussed as a next generation communication technology. In IEEE 802.11 wireless LAN system, a technical standard for supporting M2M communication is being developed as IEEE 802.11ah. The M2M communication means a communication method including one or more machines, and may be referred to as MTC (Machine Type Communication) or object communication. Here, a machine means an entity that does not require direct manipulation or intervention of a person. For example, a user device such as a smart phone capable of automatically connecting to a network and performing communication without a user's operation / intervention, such as a meter or vending machine equipped with a wireless communication module, This can be an example. M2M communication may include communication between devices (e.g., device-to-device communication (D2D)), communication between a device and a server (application server) Examples of device and server communications include vending machines and servers, Point of Sale (POS) devices and servers, and electricity, gas or water meter and server communication. In addition, applications based on M2M communication may include security, transportation, health care, and the like. Given the nature of these applications, M2M communications in general should be able to support the transmission and reception of small amounts of data occasionally at low rates in environments with very large numbers of devices.

Specifically, M2M communication must be capable of supporting the number of STAs. In the currently defined WLAN system, it is assumed that a maximum of 2007 STAs are connected to one AP. However, in the case of M2M communication, schemes for supporting a case in which a larger number (about 6000) of STAs are connected to one AP Are being discussed. In addition, M2M communication is expected to support many applications requiring / supporting low transmission speed. In order to smoothly support this, for example, in a wireless LAN system, STA can recognize whether there is data to be transmitted to itself based on a TIM (Traffic Indication Map) element, and measures for reducing the bitmap size of TIM are discussed . Also, in M2M communication, it is expected that there will be many traffic with a very long transmission / reception interval. For example, a very small amount of data is required to be exchanged over a long period (for example, one month), such as electricity / gas / water usage. Accordingly, in the wireless LAN system, even if the number of STAs that can be associated with one AP becomes very large, it is possible to efficiently support a case in which the number of STAs having a data frame to be received from the AP is small during one beacon period Are discussed.

In this way, the wireless LAN technology is rapidly evolving. In addition to the above-mentioned examples, techniques for direct link setup, improvement of media streaming performance, support for high-speed and / or large-scale initial session setup, support for extended bandwidth and operating frequency Is being developed.

Frame structure

FIG. 7 illustrates a MAC frame format of an IEEE 802.11 system to which the present invention can be applied.

Referring to FIG. 7, the MAC frame format includes a MAC header, a MAC payload, and a MAC footer. The MHR includes a Frame Control field, a Duration / ID field, an Address 1 field, an Address 2 field, an Address 3 field, a Sequence Control field, Field, an Address 4 field, a QoS Control field, and an HT Control field. A frame body field is defined as a MAC payload, and data to be transmitted is located in an upper layer and has a variable size. The frame check sequence (FCS) field is defined as a MAC footer and is used for error detection of a MAC frame.

The first three fields (frame control field, duration / identifier field, address 1 field) and the last field (FCS field) constitute the minimum frame format and exist in all frames. Other fields may exist only in a specific frame type.

The information contained in each of the above-described fields may follow the definition of the IEEE 802.11 system. In addition, each of the fields described above corresponds to an example of fields that can be included in the MAC frame, and may be replaced with another field, or an additional field may be further included.

FIG. 8 illustrates the HT format of the HT Control field in the MAC frame according to FIG.

Referring to FIG. 8, the HT control field includes a VHT subfield, a link adaptation subfield, a calibration position subfield, a calibration sequence subfield, a CSI / A channel state information / steering subfield, an NDP Announcement sub-field, an AC category constraint sub-field, a reverse direction grant / add (PPDU) More PPDU) subfields, and Reserved subfields.

The link adaptation subfield includes a training request (TRQ) subfield, an MCS request or an MAI (Modulation and Coding Scheme) Request or ASEL (Antenna Selection) Indication subfield, an MCS feedback sequence indication An MCS Feedback Sequence Identifier subfield, an MCS feedback and an MCS Feedback and Antenna Selection Command / data (MFB / ASELC) subfield.

The TRQ subfield is set to 1 when requesting a responder to send a sounding PPDU (sounding PPDU), and set to 0 when the responder is not requesting a sounding PPDU transmission. When the MAI subfield is set to 14, it indicates an antenna selection indication (ASELD indication), and the MFB / ASELC subfield is interpreted as an antenna selection command / data. Otherwise, the MAI subfield indicates an MCS request and the MFB / ASELC subfield is interpreted as an MCS feedback. When the MAI subfield indicates an MCS request (MRQ: MCS Request), it is set to 0 if no MCS feedback is requested, and to 1 when the MCS feedback is requested. Sounding PPDU means a PPDU that delivers a training symbol that can be used for channel estimation.

Each of the sub-fields described above corresponds to an example of sub-fields that can be included in the HT control field, and may be replaced with another sub-field, or may further include additional sub-fields.

FIG. 9 illustrates the VHT format of the HT Control field in the MAC frame according to FIG.

9, the HT control field includes a VHT subfield, an MRQ subfield, an MSI subfield, an MCS feedback sequence indication / group ID least significant bit (MFSI / GID-L) A Coding Type sub-field, a FB Tx Type sub-field, a spontaneous MFB (Unsolicited MFB) sub-field, a GID- An AC Constraint subfield, and an RDG / More PPDU subfield. The MFB subfield includes a subfield of VHT space-time streams (N_STS), an MCS subfield, a bandwidth (BW) subfield, a signal to noise ratio (SNR) . ≪ / RTI >

Table 1 shows a description of each subfield in the VHT format of the HT control field.

Table 1

Each of the sub-fields described above corresponds to an example of sub-fields that can be included in the HT control field, and may be replaced with another sub-field, or may further include additional sub-fields.

Meanwhile, the MAC sublayer transmits a MAC protocol data unit (MPDU) as a physical service data unit (PSDU) to the physical layer. The PLCP entity generates a PLCP protocol data unit (PPDU) by adding a physical header (PHY header) and a preamble to the received PSDU.

10 illustrates a PPDU frame format of an IEEE 802.11n system to which the present invention can be applied.

FIG. 10A illustrates a PPDU frame according to a non-HT format, an HT mixed format, and an HT-green field format.

The non-HT format represents a frame format for an existing legacy system (IEEE 802.11 a / g) STA. The non-HT format PPDU includes a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy- Field. ≪ / RTI >

HT mixed format permits the communication of the existing legacy system STA and represents a frame format for the IEEE 802.11n STA. HT mixed format PPDU includes a legacy format preamble composed of L-STF, L-LTF and L-SIG, an HT short training field (HT-STF), an HT long training field And an HT format preamble composed of an HT-Long Training field and an HT-SIG (HT-SIG) field. L-STF, L-LTF and L-SIG refer to the legacy field for backward compatibility, so it is the same as the non-HT format from L-STF to L-SIG, It can be seen that the STA is a mixed format PPDU.

The HT-Greenfield format represents a frame format for IEEE 802.11n STA in a format incompatible with existing legacy systems. The HT-Greenfield format PPDU includes a Greenfield preamble consisting of HT-Greenfield-STF (HT-GF-STF), HT-LTF1, HT-SIG and one or more HT- .

The Data field includes a SERVICE field, a PSDU, a tail bit, and a pad bit. All bits of the data field are scrambled.

10 (b) shows a service field included in the data field. The service field has 16 bits. Each bit is assigned from 0 to 15 and sequentially transmitted from 0 bit. Bits 0 to 6 are set to 0 and are used to synchronize descramblers in the receiver.

11 illustrates a VHT PPDU frame format of an IEEE 802.11ac system to which the present invention can be applied.

11, the VHT format PPDU includes a legacy format preamble composed of L-STF, L-LTF and L-SIG and a VHT-SIG-A and HT- Format preamble. L-STF, L-LTF and L-SIG refer to the legacy field for backward compatibility, so it is the same as the non-HT format from L-STF to L-SIG, It can be seen that it is a VHT format PPDU.

L-STF is a field for frame detection, automatic gain control (AGC), diversity detection, coarse frequency / time synchronization, and the like. L-LTF is a field for fine frequency / time synchronization, channel estimation, and the like. L-SIG is a field for transmitting legacy control information. VHT-SIG-A is a VHT field for transmitting common control information of VHT STAs. VHT-STF is a field for AGC, beamformed streams for MIMO. VHT-LTFs are fields for channel estimation, beamformed streams for MIMO. VHT-SIG-B is a field for transmitting control information specific to each STA.

Medium access mechanism

In a wireless LAN system compliant with IEEE 802.11, the basic access mechanism of Medium Access Control (MAC) is a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also referred to as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, which basically adopts a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or the STA may sense a radio channel or medium for a predetermined time interval (e.g., DCF Inter-Frame Space (DIFS) If the medium is judged to be in an idle status, the frame transmission is started through the corresponding medium, whereas if the medium is occupied status, The AP and / or the STA does not start its own transmission but sets a delay period (for example, an arbitrary backoff period) for the medium access and waits for a frame transmission after waiting With the application of an arbitrary backoff period, several STAs are expected to attempt frame transmission after waiting for different time periods, so that collisions can be minimized.

In addition, the IEEE 802.11 MAC protocol provides HCF (Hybrid Coordination Function). The HCF is based on the DCF and the PCF (Point Coordination Function). The PCF is a polling-based, synchronous access scheme that refers to periodically polling all receiving APs and / or STAs to receive data frames. In addition, HCF has EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). EDCA is a contention-based access method for a provider to provide data frames to a large number of users, and HCCA uses a contention-based channel access method using a polling mechanism. In addition, the HCF includes a medium access mechanism for improving the QoS (Quality of Service) of the WLAN, and can transmit QoS data in both a contention period (CP) and a contention free period (CFP).

FIG. 12 is a diagram for explaining a backoff process in a wireless LAN system to which the present invention can be applied.

An operation based on an arbitrary backoff period will be described with reference to FIG.

When a medium that is in an occupy or busy state is changed to an idle state, several STAs may attempt to transmit data (or frames). At this time, as a method for minimizing the collision, each of the STAs may attempt to transmit after selecting an arbitrary backoff count and waiting for a corresponding slot time. An arbitrary backoff count has a pseudo-random integer value, and may be determined to be one of a value in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but it can take a value twice in the case of a transmission failure (for example, in the case of not receiving an ACK for a transmitted frame). If the CW parameter value is CWmax, the data transmission can be attempted while maintaining the CWmax value until the data transmission is successful. If the data transmission is successful, the CWmin value is reset to the CWmin value. CW, CWmin and CWmax are preferably set to 2n-1 (n = 0, 1, 2, ...).

When an arbitrary backoff process is started, the STA continuously monitors the medium while counting down the backoff slot according to the determined backoff count value. When the medium is monitored in the occupied state, the countdown is stopped and waited, and when the medium is idle, the remaining countdown is resumed.

In the example of FIG. 12, when a packet to be transmitted to the MAC of the STA3 arrives, the STA3 can confirm that the medium is idle by the DIFS and transmit the frame immediately. Meanwhile, the remaining STAs monitor and wait for the medium to be in a busy state. In the meanwhile, data to be transmitted may also occur in each of STA1, STA2 and STA5, and each STA waits for DIFS when the medium is monitored as idle, and then counts down the backoff slot according to the arbitrary backoff count value selected by each STA. Can be performed. In the example of FIG. 12, STA2 selects the smallest backoff count value, and STA1 selects the largest backoff count value. That is, the case where the remaining backoff time of the STA5 is shorter than the remaining backoff time of the STA1 at the time when the STA2 finishes the backoff count and starts the frame transmission is illustrated. STA1 and STA5 stop countdown and wait for a while while STA2 occupies the medium. When the occupation of STA2 is ended and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the stopped backoff count. That is, the frame transmission can be started after counting down the remaining backoff slots by the remaining backoff time. Since the remaining backoff time of STA5 is shorter than STA1, STA5 starts frame transmission. On the other hand, data to be transmitted may also occur in the STA 4 while the STA 2 occupies the medium. At this time, in STA4, when the medium becomes idle, it waits for DIFS, counts down according to an arbitrary backoff count value selected by the STA4, and starts frame transmission. In the example of FIG. 12, the remaining backoff time of STA5 coincides with the arbitrary backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 receive an ACK, and data transmission fails. In this case, STA4 and STA5 can double the CW value, then select an arbitrary backoff count value and perform a countdown. On the other hand, the STA1 waits while the medium is occupied due to the transmission of the STA4 and the STA5, waits for the DIFS when the medium becomes idle, and starts frame transmission after the remaining backoff time.

STA sensing behavior

As described above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing in which the AP and / or STA directly senses the medium. Virtual carrier sensing is intended to compensate for problems that may occur in media access, such as hidden node problems. For the virtual carrier sensing, the MAC of the wireless LAN system may use a network allocation vector (NAV). The NAV is a value that indicates to another AP and / or STA the time remaining until the AP and / or STA that is currently using or authorized to use the media is available. Therefore, the value set to NAV corresponds to the period in which the medium is scheduled to be used by the AP and / or the STA that transmits the frame, and the STA receiving the NAV value is prohibited from accessing the medium during the corresponding period. The NAV may be set according to the value of the duration field of the MAC header of the frame, for example.

In addition, a robust collision detection mechanism has been introduced to reduce the probability of collision. This will be described with reference to Figs. 13 and 14. Fig. The actual carrier sensing range and the transmission range may not be the same, but are assumed to be the same for convenience of explanation.

13 is a diagram for explaining a hidden node and an exposed node.

13 (a) is an example of a hidden node, and STA A and STA B are in communication and STA C has information to be transmitted. Specifically, STA A is transmitting information to STA B, but it can be determined that STA C is idle when performing carrier sensing before sending data to STA B. This is because the STA A transmission (ie, media occupancy) may not be sensed at the STA C location. In this case, STA B receives information of STA A and STA C at the same time, so that collision occurs. In this case, STA A is a hidden node of STA C.

FIG. 13B is an example of an exposed node, and STA B is a case where STA C has information to be transmitted in STA D in a state of transmitting data to STA A. FIG. In this case, if the STA C carries out the carrier sensing, it can be determined that the medium is occupied due to the transmission of the STA B. Accordingly, even if STA C has information to be transmitted to STA D, it is sensed that the media is occupied, and therefore, it is necessary to wait until the medium becomes idle. However, since the STA A is actually out of the transmission range of the STA C, the transmission from the STA C and the transmission from the STA B may not collide with each other in the STA A. Therefore, the STA C is not necessary until the STA B stops transmitting It is to wait. In this case, STA C can be regarded as an exposed node of STA B.

14 is a diagram for explaining RTS and CTS.

A short signaling packet such as RTS (request to send) and CTS (clear to send) can be used in order to effectively utilize the collision avoidance mechanism in the exemplary situation as shown in FIG. The RTS / CTS between the two STAs may allow the surrounding STA (s) to overhear, allowing the surrounding STA (s) to consider whether to transmit information between the two STAs. For example, if an STA to which data is to be transmitted transmits an RTS frame to an STA receiving data, the STA that receives the data can notify that it will receive data by transmitting a CTS frame to surrounding terminals.

Fig. 14 (a) is an example of a method for solving a hidden node problem, and it is assumed that both STA A and STA C try to transmit data to STA B. Fig. When STA A sends RTS to STA B, STA B transmits CTS to both STA A and STA C around it. As a result, STA C waits until the data transmission of STA A and STA B is completed, thereby avoiding collision.

FIG. 14B is an illustration of a method for solving the exposed node problem, wherein STA C overrides the RTS / CTS transmission between STA A and STA B, D, the collision does not occur. That is, STA B transmits an RTS to all surrounding terminals, and only STA A having data to be transmitted transmits CTS. Since STA C only receives RTS and does not receive CTS of STA A, it can be seen that STA A is outside the carrier sensing of STC C.

Inter-Frame Space (IFS)

The time interval between two frames is defined as IFS (Inter-Frame Space). The STA determines whether the channel is used during the IFS through carrier sensing. The DCF MAC layer defines four IFSs, which determine the priority of occupying the wireless medium.

The IFS is set to a specific value according to the physical layer irrespective of the bit rate of the STA. The types of IFS are the same as SIFS (Short IFS), PIFS (PCF IFS), DIFS (DCF IFS), and EIFS (Extended IFS). SIFS (Short IFS) is used for RTS / CTS, ACK frame transmission and has the highest priority. PIFS (PCF IFS) is used for PCF frame transmission and DIFS (DCF IFS) is used for DCF frame transmission. EIFS (Extended IFS) is used only when a frame transmission error occurs, and does not have a fixed interval.

The relationship between each IFS is defined as a time gap on the medium, and the related attributes are provided by the physical layer as shown in FIG. 15 below.

15 is a diagram illustrating the relationship of the IFS.

The ending point of the last symbol of the PPDU in all media timings indicates the end of transmission, and the first symbol of the preamble of the next PPDU indicates the start of transmission. All MAC timings can be determined with reference to the PHY-TXEND.confirm primitive, the PHYTXSTART.confirm primitive, the PHY-RXSTART.indication primitive, and the PHY-RXEND.indication primitive.

Referring to FIG. 15, the SIFS time (aSIFSTime) and the slot time (aSlotTime) may be determined for each physical layer. The SIFS time has a fixed value, and the slot time can change dynamically according to the radio delay time (aAirPropagationTime). The SIFS time and the slot time are defined by the following equations (a) and (b), respectively.

[Mathematical expression a]

[Mathematical expression b]

PIFS and SIFS are defined by the following equations (c) and (d), respectively.

[Mathematical expression c]

(D)

EIFS is calculated from the SIFS, DIFS, and ACK transmission time (ACKTxTime) as shown in the following equation (e). The ACK transmission time (ACKTxTime) is expressed in microseconds required for ACK frame transmission including the preamble, PLCP header and additional physical layer dependent information at the mandatory minimum physical layer rate.

(E)

The SIFS, PIFS, and DIFS illustrated in FIG. 15 are measured on different MAC slot boundaries (TxSIFS, TxPIFS, TxDIFS) from the medium. This slot boundary is defined as the time that the transmitter is turned on by the MAC layer to match different IFS timings on the medium after detection of the CCA result of the previous slot time. Each MAC slot boundary for SIFS, PIFS, and DIFS is defined as Equation (f) to (h) below.

[Mathematical expression f]

[Mathematical expression g]

[Equation h]

An example of overcoming Hidden Traffic using DBO

16 is a diagram illustrating a method for reducing hidden traffic using DBO in a wireless LAN system according to an embodiment of the present invention.

Prior to the description, Hidden Traffic means that invisible traffic is affecting the receiving end in the transmitting end. For example, when a transmitting end (AP) tries to transmit a packet using 80 MHz, the transmitting end tries to transmit all the 80 MHz signals. However, in the receiving end (STA, for example) Can be. In this case, the receiving end can not perform signal decoding.

16, when a DBO is used in a wireless LAN system, a transmitting terminal (AP) transmits a 20 MHz duplicate VHT RTS to 80 MHz, and a receiving terminal (clean) When VHT CTS is transmitted to a transmitter through a channel, hidden traffic generated at a receiver may be reduced.

17 is a flowchart illustrating that DBO is adaptively used in a wireless LAN system according to an embodiment of the present invention. Prior to the description, a device that can adaptively use the DBO can be a transmitting end and a receiving end. The apparatus may be an AP or an STA of FIG. 19 to be described later.

First, the control units 421 and 431 collect data transmitted and received for a predetermined time (S1610).

Next, the control units 421 and 431 calculate the collision loss rate due to the hidden traffic based on the collected data (S1620).

Specifically, the control unit 421 may calculate or update the collision loss rate when retransmission of the A-MPDU occurs. In addition, the controller 421 may calculate or update the collision loss rate when the retransmission of the A-MPDU does not occur but the MPDU loss is continuously generated.

Thereafter, the control unit 421 compares the collision loss rate with the reference value or the collision loss rate with the DBO overhead (S1630).

Here, the reference value may be preliminarily set by the user input as the last line of the collision loss rate. For example, when the collision loss rate exceeds 50%, the control unit 421 can assume that the reference value is exceeded.

Also, the control unit 421 can use the DBO. However, when DBO is used, overhead may occur due to the exchange of VHT RTS / CTS.

If the collision loss rate is larger than the reference value or the overhead loss rate due to the use of the DBO (S1630), the DBO can be activated for a predetermined time (S1640).

That is, the controller 421 activates and deactivates the DBO for a predetermined period of time.

As described above, when the control unit 421 uses the DBO, the collision loss rate due to hidden traffic can be reduced.

The control unit 421 calculates an overhead loss rate by the DBO (S1650).

Then, the control unit 421 can repeat steps S1610 to S1650 repeatedly.

In this specification, the collision loss rate due to hidden traffic is first calculated and compared with the loss rate due to the overhead due to the use of the DBO. However, this is merely an example, and the loss rate due to the overhead due to the use of the DBO is calculated, And can be compared with the collision loss rate.

In addition, collision loss rate due to hidden traffic and overhead loss rate due to DBO can be updated repetitively.

18 is a flowchart specifically showing the flowchart shown in Fig.

First, the control unit 421 may collect data transmission statistics for a predetermined time T1 (S1730). At the same time, the control unit 421 can detect whether the MPDU loss is continuously generated although the A-MPDU is retransmitted or not retransmitted (S1720).

The control unit 421 may calculate or update the collision loss rate due to the hidden traffic based on the above-described contents.

After the collision loss rate is calculated for the first time, the control unit 421 can update the collision loss rate based on the data collected for another T1.

19 illustrates a block diagram of a wireless device according to an embodiment of the present invention.

19, an AP 420 includes a processor 421, a memory 422, and a transceiver 423. Processor 421 implements the proposed functionality, process and / or method. The layers of the air interface protocol (see FIG. 5) may be implemented by the processor 421. The memory 422 is coupled to the processor 421 and stores various information for driving the processor 421. [ Transceiver 423 is coupled to processor 421 to transmit and / or receive wireless signals.

The STA 430 includes a processor 431, a memory 432, and a transceiver 433. Processor 431 implements the proposed functionality, process and / or method. The layers of the air interface protocol (see FIG. 5) may be implemented by the processor 431. The memory 432 is connected to the processor 431 and stores various information for driving the processor 431. [ The transceiver 433 is coupled to the processor 431 to transmit and / or receive wireless signals.

The memories 422 and 432 may be internal or external to the processors 421 and 431 and may be coupled to the processors 421 and 431 in various well known means. Also, the AP 420 and / or the STA 430 may have a single antenna or multiple antennas.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in memory and driven by the processor. The memory is located inside or outside the processor and can exchange data with the processor by various means already known.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. Accordingly, the foregoing detailed description is to be considered in all respects illustrative and not restrictive. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

While various embodiments of the present invention have been described with reference to an example applied to an IEEE 802.11 system, the present invention can be equally applied to various wireless access systems other than the IEEE 802.11 system.

420: AP 430: STA

Claims (12)

A method for adaptively using Dynamic Bandwidth Operation (DBO) in a wireless LAN system,
A first step of collecting predetermined time data;
A second step of calculating a collision loss rate due to hidden traffic based on the collected data;
And compares the calculated collision loss rate with a predetermined reference value or a loss rate due to a Request-To-Send (CTS) / Clear-To-Send (CTS) transmission overhead of the previously calculated or updated Dynamic Bandwidth Operation A third step; and
And activating the DBO for a predetermined time if the collision loss rate is greater than the reference value or the loss rate due to the overhead. The method according to claim 1,
And deactivating the DBO if the collision loss rate is less than the reference value or the loss rate due to the overhead. The method according to claim 1,
Activating the DBO and calculating a loss rate due to the overhead of the activated DBO prior to the first step. The method according to claim 1,
The second step comprises:
And updating the collision loss rate when retransmission of the A-MPDU (Aggregate-MAC Protocol Data Unit) occurs. 5. The method of claim 4,
The second step comprises:
And updating the collision loss rate if the A-MPDU retransmission does not occur and the MPDU loss is consecutively generated. The method according to claim 1,
And updating the loss rate due to the DBO overhead by the activated DBO. In an electronic device adaptively using a Dynamic Bandwidth Operation (DBO) in a wireless LAN system,
A transceiver for transmitting and receiving data to and from an external device;
A collision loss rate due to Hidden Traffic is calculated based on the collected data, and the calculated collision loss rate is compared with a preset reference value or a RTS / And a loss rate due to CTS transmission overhead,
Wherein,
And activates DBO for a predetermined time when the collision loss rate is larger than the reference value or the loss rate due to the overhead. 8. The method of claim 7,
Wherein,
Wherein the collision loss rate is smaller than the reference value or the loss rate due to the overhead
, The DBO is deactivated. 8. The method of claim 7,
Wherein,
Activates the DBO before collecting the predetermined time data, and calculates or updates the loss rate due to the overhead of the activated DBO. 8. The method of claim 7,
Wherein,
And when the retransmission of the A-MPDU occurs, updates the collision loss rate. 11. The method of claim 10,
Wherein,
Wherein when the A-MPDU retransmission does not occur and the MPDU loss continuously occurs, the collision loss rate is updated. 8. The method of claim 7,
Wherein,
And updates the loss rate due to the DBO overhead by the activated DBO.

Images