KR102648538B1 - Method for scheduling orthogonal frequency division multiple access based on quality of service in wireless local area network - Google Patents

Abstract

The present invention relates to a short-range wireless network, and is a technology for scheduling uplink transmission with minimum delay in consideration of the quality of service (QoS) requirements of a station (STA) in an IEEE 802.11be short-range wireless network. Based on the priority of the data frame generated by the system, the priority for a plurality of stations (STAs) existing in the basic service set (BSS) is calculated, and the priority between the stations (STAs) and the station with the data frame to be transmitted ( By allocating resources to stations (STAs) with priority using the number of STAs and available resource unit (RU) information, high-priority traffic can be scheduled to be transmitted before low-priority traffic. there is.

Description

Method for quality of service based orthogonal frequency division multiple access scheduling in short-range wireless networks

The present invention relates to a short-range wireless network, and more specifically, for orthogonal frequency division multiple access scheduling with minimum delay in consideration of quality of service (QoS) requirements of traffic generated from a station (STA) in an IEEE 802.11be network. It's about method.

Recently, the use of real-time data is rapidly increasing with the development of IEEE 802.11-based wireless local area networks (WLANs). IEEE 802.11be is the potential next revision to the IEEE 802.11 wireless local area network (WLAN) family of standards. IEEE 802.11be is also known as the Extremely High Throughput (EHT) standard and is sold commercially as Wi-Fi 7. Wi-Fi 7 is essentially an evolution of Wi-Fi 6 and uses Orthogonal Frequency Division Multiple Access (OFDMA) as a resource allocation technology.

OFDMA divides a channel of several tens of MHz into N subcarriers that are orthogonal to each other. Orthogonality prevents interference between subcarriers. These subcarriers are grouped into resource units (RU). The number of resource units (RUs) determines the number of stations (STAs) that can be serviced simultaneously, and the number of resource units (RUs) varies depending on the channel bandwidth and grouping of subcarriers. For example, a 20 MHz channel consists of 256 subcarriers. These subcarriers are grouped into up to 9, 5, 3 or 1 resource units (RU) containing 26, 52, 106 and 242 subcarriers respectively. These resource units (RUs) are randomly allocated for uplink data using the Uplink OFDMA Random Access (UORA) mechanism in the IEEE 802.11ax wireless LAN standard.

However, these existing processes do not consider the quality of service (QoS) requirements of a station (STA) that must transmit a data frame to an access point (AP).

Korean Patent Publication No. 10-2012-0071217 (Publication date: July 2, 2012) Korean Patent Publication No. 10-2017-0022474 (Publication date: March 2, 2017)

The present invention has been proposed to solve the above-mentioned problems, and proposes a technology for scheduling uplink transmission with minimum delay in consideration of the quality of service (QoS) requirements of a station (STA) in an IEEE 802.11be short-range wireless network.

In order to achieve the above-mentioned technical problem, a quality of service-based orthogonal frequency division multiple access scheduling method in a short-range wireless network according to an aspect of the present invention is provided, in which an access point (AP) is a station (STA) in a basic service set (BSS). transmitting a buffer status report (BSR) polling message to the users;

An access point (AP) receiving a BSR frame including the queue size and total buffer size for each access category from stations (STAs);

An access point (AP) determining a weight for each access category (AC) of the stations (STAs);

An access point (AP) calculating priority values of stations (STAs) using weights, queue sizes, and total buffer sizes for each access category (AC) of the stations (STAs);

An access point (AP) determines priorities between stations (STAs) according to the priority values of the stations (STAs), and the priorities between the stations (STAs) and the number of stations (STAs) with data frames to transmit and allocating resources to a station (STA) with priority using available resource unit (RU) information.

In addition, according to the present invention, the step of the access point (AP) determining the weight for each access category (AC) of the stations (STAs) includes the access point (AP) determining the weight for each access category (AC) of the stations (STAs). It further includes adjusting parameter values of the medium access algorithm including arbitrary inter-frame interval (AIFS), minimum contention window (CWmin), and maximum contention window (CWmax) according to weights for categories (AC). .

In addition, according to the present invention, the access point (AP) determines the priority value of the stations (STAs) using the weight, queue size, and total buffer size for each access category (AC) of the stations (STAs). In the calculation stage,

The access point (AP) further includes calculating the congestion level using the size of the queue and the total buffer size for each access category (AC) of the stations (STAs), and the station based on Equation 1 below: The priority values of (STAs) can be calculated.

[Equation 1]

Here, ⅰ is a natural number, STAi is a station (STA) in the basic service set (BSS), is the priority value of each station (STA), , , , is the size of the queue for each access category (AC), , , , is the weight for each access category (AC), AC_VO is voice, AC_VI is video, VO_BE is Best Effort, AC_BK is background, and is the congestion rate of each station (STA).

In addition, according to the present invention, in the step where the access point (AP) calculates the congestion level using the queue size and total buffer size for each access category (AC) of the stations (STAs),

Congestion can be calculated based on Equation 2 below the access point (AP).

[Equation 2]

is a value that matches the buffer occupancy rate expressed as a percentage by dividing the sum of the queue sizes of each access category (AC) by the total buffer size. If the occupancy rate is less than 25 (%), is 0, if it is more than 25(%) but less than 50(%) is 1, if it is more than 50(%) but less than 75(%) is 2, if it is more than 75(%) and 100(%) is 3.

According to one of the above-described means for solving the problem of the present invention, a plurality of stations (STAs) existing in the basic service set (BSS) are provided based on the priority of the uplink data frame generated by the station (STA). Calculate priority and allocate resources to stations (STAs) with priority using the priorities between stations (STAs), the number of stations (STAs) with data frames to transmit, and available resource unit (RU) information. By implementing this, high-priority traffic can be scheduled to be transmitted before low-priority traffic.

Figure 1 is a conceptual diagram showing the structure of a wireless local area network (WLAN).
Figure 2 is a conceptual diagram showing UL MU transmission used in the present invention.
Figure 3 is a conceptual diagram showing a UL MU PPDU transmitted by a UL MU STA used in the present invention.
Figure 4 shows a station (STA) and an access point (AP) according to one embodiment of the present invention.
Figure 5 shows the operation of a method for quality of service-based orthogonal frequency division multiple access scheduling in a short-range wireless network according to the present invention.

The advantages and features of the invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to provide common knowledge in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in this specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

In this specification, terms such as “unit,” “module,” “device,” “terminal,” “server,” or “system” are intended to refer to a combination of hardware and software driven by the hardware. For example, hardware may be a data processing device that includes a CPU or other processor. Additionally, software driven by hardware may refer to a running process, object, executable, thread of execution, program, etc.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

Referring to FIG. 1, a wireless LAN system includes one or more basic service sets (Basic Service Set, BSS). BSS (Basic Service Set) is the most basic wireless network topology of a wireless LAN (WLAN), and is a set of access points (APs) and stations (STAs) and does not refer to a specific area. BSS 100 may include one STA 100-1 in one access point 125. Additionally, the BSS 105 may include one or more STAs 105-1 and 105-2 that can be combined with one access point 130.

The distributed system 110 can connect several BSSs 100 and 105 to implement an extended service set (ESS) 140, which is an extended service set. The ESS (140) indicates a network in which one or more access points (125, 230) are connected through the distributed system (110). Access points 125 and 230 included in one ESS 140 may have the same service set identification (SSID). The portal 120 may serve as a bridge that connects a wireless LAN network (IEEE 802.11) to another network (eg, 802.X).

Station (STA) is any functional medium that includes medium access control (MAC) and a physical layer interface to a wireless medium following the provisions of the IEEE 802.11 standard. In a broad sense, it is an AP Station and Non -Can be used to include all AP Stations.

A station (STA) is a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile station. It may also be called various names, such as Mobile Subscriber Unit or simply user.

An access point (AP) operating in a wireless local area network (WLAN) system can transmit data to each of a plurality of stations (STAs) through the same time resource. If transmission from an access point (AP) to a station (STA) is referred to as downlink transmission, transmission to each of a plurality of stations (STA) of the access point (AP) is DL MU transmission (downlink multi-user transmission, or downlink transmission). It can be expressed in terms of link multi-user transmission).

Transmission from a station (STA) to an access point (AP) can be called uplink transmission, and multiple stations (STAs) transmitting data to an access point (AP) on the same time resource is called UL MU transmission (uplink multi- It can be expressed in terms of user transmission, or uplink multi-user transmission. Each PPDU, frame, and data transmitted through the uplink can be expressed in terms of uplink PPDU, uplink frame, and uplink data.

When uplink transmission by each of a plurality of stations (STAs) is performed in the frequency domain, different frequency resources may be allocated to each of the plurality of STAs as uplink transmission resources based on OFDMA. Each of a plurality of stations (STA) may transmit uplink data to an access point (AP) through different allocated frequency resources. The transmission method using these different frequency resources may be expressed in terms of the UL MU OFDMA transmission method.

FIG. 2 is a conceptual diagram showing UL MU transmission used in the present invention, and FIG. 3 is a conceptual diagram showing a UL MU PPDU transmitted by a UL MU STA used in the present invention.

Referring to FIG. 2, an access point (AP) may schedule uplink transmission of stations (STAs) included in the BSS. To this end, the access point (AP) transmits a buffer status report (BSR) polling message 200 to the station (STA). Stations (STAs) must inform the access point (AP) of the demand for uplink transmission and request allocation of resources required for uplink transmission. When stations (STAs) receive a buffer status report (BSR) polling message 200, they transmit a buffer status report (BSR) frame to the access point (AP).

When the access point (AP) receives a BSR frame including the queue size and total buffer size for each access category (AC) from the stations (STAs), the access point (AP) sends a BSR frame to each access category (AC) of the stations (STAs). The priority values of stations (STAs) are calculated using the weight, queue size, and total buffer size.

The access point (AP) determines priorities between stations (STAs) according to the priority values of the stations (STAs), the priorities between the stations (STAs), the number of stations (STAs) with data frames to transmit, and Resources are allocated to stations (STAs) with priority using available resource unit (RU) information.

An access point (AP) may transmit a trigger frame 220 to a plurality of stations (STAs) to induce uplink transmission of the plurality of stations (STAs). When a plurality of stations (STAs) receive a trigger frame 220 from an access point (AP), they may transmit a UL MU PPDU to the access point (AP) on a subchannel in response to the trigger frame (TF). .

The trigger frame 220 includes information for transmission of the UL MU PPDU of each of a plurality of stations (STA), such as resource allocation information for each station (STA), identification information for each station (STA), and station (STA) information. It may include information about the modulation and coding scheme (MCS) applied to the UL MU PPDU transmitted by each. Additionally, the trigger frame 220 may include information about the transmission power of the UL MU PPDU, space time block coding (STBC) to be used for transmission of the UL MU PPDU, and information about beamforming.

Each of the plurality of stations (STAs) that received the trigger frame 220 may transmit the UL MU PPDU to the access point (AP) based on an arbitrary inter-frame interval (AIFS). The access point (AP) may transmit a block response frame (Block Ack Flame) 240 for the UL MU PPDU 220 received from the plurality of stations (STAs).

Referring to FIG. 3, the UL MU PPDU may include a PPDU header (legacy PPDU header, HE PPDU header) and MAC payload.

The legacy PPDU header may include L-STF (300), L-LTF (310), and L-SIG (320). The L-STF 300 of the UL MU PPDU may include a short training orthogonal frequency division multiplexing symbol (OFDM symbol). The L-STF 300 can be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency/time synchronization. The L-LTF 310 may include a long training orthogonal frequency division multiplexing symbol (OFDM symbol). L-LTF 310 can be used for fine frequency/time synchronization and channel prediction. L-SIG 320 may be used to transmit control information. L-SIG 320 may include information on data transmission rate and data length.

The HE PPDU header may include HE-SIG1 (330), HE-SIG2 (340), HE-STF (350), HE-LTF (360), and HE-SIG3 (370). HE-SIG1 330 may include common information (BW, GI length, BSS index, CRC (cyclic redundancy check), tail bit, etc.) for decoding of UL MU PPDU. Specifically, HE-SIG1 330 may include a color bit for BSS identification, a bit indicating the total bandwidth size over which the UL MU PPDU is transmitted, a tail bit, a CRC bit, and a bit indicating the CP (or GI) length. You can. Some information included in HE-SIG1 330 may be determined based on control information for UL MU transmission included in the trigger frame.

HE-SIG2 340 can be encoded and transmitted over the entire bandwidth. The total bandwidth may be the total frequency bandwidth allocated for transmission of the UL MU PPDU of each of the plurality of stations (STAs) by the trigger frame. The size of the total bandwidth is 20 MHz, and HE-SIG2 340 can be encoded and transmitted in units of 20 MHz. HE-SIG2 340 may include information about each station (STA) transmitting a UL MU PPDU based on a trigger frame (TF). For example, HE-SIG2 340 may include identification information (e.g., PAID, GID) of the STA that will transmit the UL MU PPDU. In addition, HE-SIG2 (340) is provided to each STA for transmission of each STA's HE-STF (350), HE-LTF (360), HE-SIG3 (370), and MAC payload (980) on the UL MU PPDU. May contain information about allocated resources. The STA may generate HE-SIG2 340 based on information included in the trigger frame (e.g., identification information of the UL MU target STA and resource information allocated to the UL MU target STA).

HE-SIG2 340 may also be encoded and transmitted on a channel basis, and may only include identification information of a station (STA) assigned to a subchannel included in the channel and allocation information for each subchannel included in the channel. The UL MU PPDU may not include HE-SIG2 (340). Information indicating each station (STA) and resource allocation information for each station (STA) may be transmitted through a trigger frame (TF) transmitted by an access point (AP). Information indicating each station (STA) and resource allocation information for each station (STA) are information determined by the access point (AP). Accordingly, the access point (AP) does not need to receive information indicating each station (STA) and resource allocation information for each station (STA) through the HE-SIG2 (340). Therefore, the UL MU PPDU may not include HE-SIG2 (340).

In the UL MU PPDU, HE-STF 350, HE-LTF 360, HE-SIG3 370, and MAC payload 380 may be encoded and transmitted on each of a plurality of subchannels. HE-SIG3 370 may include information for decoding the MAC payload 380. Information for decoding the MAC payload 380 may include MCS, Coding, STBC, TXBF, etc. Specifically, HE-SIG3 (370) transmitted through each of a plurality of subchannels is used for information about the MCS applied to the MAC payload (380) transmitted through each of a plurality of subchannels and for transmission of the MAC payload (380). It may contain information about the STBC and TXBF used. MAC payload 380 may include uplink data of a station (STA) triggered by an access point (AP).

The PPDU header of the UL MU PPDU may include a MAC indicator field to indicate MAC header information. The MAC indicator field includes a frame control indicator (331), duration/ID indicator (332), receiver address indicator (333), sender address indicator (334), BSSID indicator (335), sequence control indicator (336), and QoS control indicator ( 337), and may include an HT control indicator 338.

The frame control indicator 331 may indicate whether the frame control field is included in the PPDU header. For example, if the frame control indicator 331 is 1, it may indicate whether the frame control field is included in the PPDU header. The AP that has received the frame control field included in the PPDU header can obtain information about the type of frame before decoding the MAC header and prepare the next operation in advance. For example, if the frame control indicator 331 included in the PPDU header indicates a data frame, the access point (AP) can pre-configure an ACK frame to be transmitted in response to the data frame. As another example, after the access point (AP) transmits a data frame, the access point (AP) determines whether the frame control indicator 331 of the received PPDU indicates an ACK frame/BA frame transmitted in response to the data frame. Depending on availability, it can be decided in advance whether or not to retransmit the data frame.

The duration/ID indicator 332 may indicate whether the duration/ID field is included in the PPDU header. For example, if the duration/ID indicator 332 is 1, it may indicate that the duration/ID field is included in the PPDU header. For example, when a station (STA) transmits a PS-poll frame to request a pending frame from a DL access point (AP), the access point (AP) receives the PS-poll frame transmitted by the station (STA). It is confirmed that it is a received PS-poll frame based on the frame control indicator 331 of the PPDU header of the transmitted PPDU, and based on information about the AID of the station (STA) included in the duration/ID indicator 332 of the PPDU header. A PPDU containing downlink data pending at the station (STA) can be generated in advance.

The recipient address indicator 333 may indicate whether the recipient address field is included in the PPDU. The recipient address field may include identification information (MAC address of the AP) of the access point (AP) that will receive the PPDU (or frame). For example, if the recipient address indicator 333 is 1, the recipient address field may be included in the PPDU header. If the PPDU header includes a recipient address field, the access point (AP) can decode the PPDU header and determine whether to further decode the PPDU. For example, if the recipient address field included in the PPDU header indicates an access point (AP), the access point (AP) may additionally perform decoding on the MAC payload. Conversely, if the recipient address field included in the PPDU header does not indicate the AP, the AP may not perform decoding on the MAC payload.

The sender address indicator 334 may indicate whether the sender address field is included in the PPDU. The sender address field may include identification information (MAC address of the transmitting STA) of the STA that transmitted the PPDU (or frame). If the sender address indicator 334 is 1, the sender address field may be included in the PPDU header. The access point (AP) that received the PPDU can obtain information about the station (STA) that transmitted the PPDU in advance before decoding the MAC header based on the sender address field included in the PPDU header. The access point (AP) can obtain information about whether the PPDU (or frame) is transmitted from a station (STA) associated with the access point (AP) based on the sender address field included in the PPDU header. If the information included in the sender address field is different from the identification information of the station (STA) associated with the access point (AP), the access point (AP) may not perform decoding of the MAC payload.

The BSSID indicator 335 may indicate whether the BSSID field is included in the PPDU. The BSSID field may include information about the BSSID of the BSS including the station (STA) that transmitted the PPDU. The station (STA) can obtain information about the BSS including the transmitting station (STA) that transmitted the PPDU based on the BSSID field included in the PPDU header. The access point (AP) may set the CCA threshold differently by considering whether the BSSID of the transmitting access point (AP) and the BSSID of the STA are the same before decoding the MAC header based on the BSSID field included in the PPDU header. The CCA sensitivity level can be used to determine whether the AP's medium is idle/busy.

The sequence control indicator 336 may indicate whether the sequence control field is included in the PPDU header. If the sequence control indicator 336 is set to 1, the PPDU header may include a sequence control field. When a PPDU carries a block ACK frame or a block ACK request frame, the access point (AP) provides information in advance about the sequence of data included (or will be included) in the PPDU based on decoding of the sequence control field included in the PPDU header. It can be obtained. Therefore, the access point (AP) can have time to perform processing in the buffer and access memory in advance before decoding the MAC header based on the sequence control field included in the PPDU.

The QoS control indicator 337 may indicate whether the QoS control field is included in the PPDU header. If the QoS control indicator 337 is set to 1, the PPDU header may include a QoS control field. The QoS control field may include information about the ACK policy. Therefore, the access point (AP) can obtain an ACK policy based on the QoS control field of the PPDU header and perform operations according to the ACK policy in advance before decoding the MAC header. For example, if the ACK policy indicated based on the QoS control field of the PPDU header is No ACK, the access point (AP) does not need to prepare an ACK frame in advance. The access point (AP) can determine whether to distribute the load for generating an ACK frame in the MAC layer depending on whether the indicated ACK policy is deferred ACK or immediately transmitted ACK based on the QoS control field of the PPDU header. When the ACK policy is deferred ACK, processing for generating an ACK frame of the access point (AP) may be postponed to a relatively lower priority than when the ACK policy is an immediately transmitted ACK.

The HT control indicator 338 may indicate whether the HT control field is included in the PPDU header. If the HT control indicator 338 is set to 1, the PPDU header may include a HE control field. The HT control field may include information related to feedback. For example, if the AP acquires the HT control field in advance based on decoding of the PPDU header before decoding the MAC header, the AP may perform processing related to rate adaptation in advance.

Figure 4 shows a station (STA) and an access point (AP) according to one embodiment of the present invention.

The STA (400) includes a physical layer circuit (PHY) 402 and a transceiver (405). The STA 400 uses the antenna 401 to transmit and receive signals to and from the AP 450, other APs, other STAs, or other devices. The physical layer circuit (PHY) 402 performs various encoding and decoding functions. Transceiver 405 performs various transmit and receive functions between the baseband range and the high frequency signal band range. The physical layer circuit (PHY) 402 and the transceiver 405 may be separate components or may be part of a combined component. STA 400 includes a media access control circuit (MAC) 404 and processing circuitry 406 and memory 408 arranged to perform the operations described herein.

The AP 450 may include a physical layer circuit (PHY) 452 and a transceiver circuit 455, one or both of which use one or more antennas 451 to communicate with the STA 400 and other APs. , may enable transmission and reception of signals with other STAs or other devices. The physical layer circuit (PHY) 452 and the transceiver circuit 455 may perform various functions similar to those previously described for the STA 400. Accordingly, the physical layer circuit (PHY) 452 and the transceiver circuit 455 may be separate components or part of a combined component. Additionally, some of the functions described in relation to the transmission and reception of signals may include one, any, or all of the physical layer circuitry (PHY) 452, transceiver circuitry 455, and other components or layers. It can be performed by combination.

AP 450 includes media access control circuitry (MAC) 454 for controlling access to wireless media, processing circuitry 456 arranged to perform the operations described herein, memory 458, and other APs. It may include one or more interfaces 460 that enable communication with other components. Interfaces 460 may be wired or wireless, or a combination thereof.

The processing circuit 406 of the STA 400 may be implemented to receive a trigger frame from the AP 450 and transmit a UL MU PPDU to the AP on a subchannel in response to the trigger frame. Additionally, the processing circuit 406 of the station (STA) may be implemented to generate a PPDU header of the UL MU PPDU that includes a medium access control (MAC) indicator field and at least one MAC header field. The MAC indicator field includes at least one sub-indicator, each of the at least one sub-indicator indicates the presence or absence of each of at least one MAC header field, and each of the at least one MAC header field is included in the MAC header of the UL MU PPDU It may correspond to each of at least one field.

In addition, the processing circuit 406 of the STA 400 provides instructions based on the MAC indicator field according to the load situation of the AP 450, the processing performance of the AP 450, the AP's request, the channel situation, and the characteristics of the frame transmission and reception procedure. It can be implemented to adaptively change each control information (or MAC header field) included in the UL MU PPDU.

Hereinafter, the operation of the processing circuit 406 of the station (STA) and the processing circuit 456 of the access point (AP) will be described.

Figure 5 shows the operation of a method for quality of service-based orthogonal frequency division multiple access scheduling in a short-range wireless network according to the present invention. In this specification, it is assumed that a short-range wireless network includes one access point (AP) and three stations (STA1, STA2, and STA3).

When the access point (AP) obtains a transmission opportunity (TXOP), it transmits a buffer status report (BSR) polling message (501). In the IEEE 802.11be wireless LAN system, to enable multiple users to transmit uplink signals on a specific channel at the same time, the access point (AP) schedules uplink transmission of stations (STAs) in the basic service set (BSS). can do. At this time, in order to properly schedule the uplink transmission of the three stations (STA1, STA2, and STA3), the access point (AP) requires information related to the buffer status, and the three stations (STA1, STA2, and STA3) also need uplink transmission. It is necessary to notify the access point (AP) of the demand for transmission and request allocation of the resources required for uplink transmission.

Stations (STA1, STA2, STA3) transmit a BSR frame to an access point (AP) (502). The BSR frame serves to request resources for uplink transmission and at the same time transmits information related to the buffers of stations (STA1, STA2, and STA3). The BSR frame may include a 2-byte frame control field, a frame check sequence field used for error detection, an STA identification information field, a receiver address field, a transmission power field, and a queue size field. The receiver address field contains information related to the AP's Media Access Control (MAC) address, the transmit power field contains information related to the transmit power used to transmit the BSR frame, and the queue size field contains information related to each access category (AC). It can include the size of the queue and the total buffer size.

The access point (AP) stores information related to the buffers of the stations (STA1, STA2, and STA3) and determines a weight for each access category (AC) of the stations (STAs) (503). The Enhanced Distributed Channel Access (EDCA) algorithm maps traffic according to eight user priority levels into four access categories (AC). AC_VO is a type of application traffic related to multiple VoIP call processing, AC_VI is multiple video stream processing, VO_BE is Internet browsing (search, etc.), and AC_BK is a type of application traffic related to file transfer and printing.

The access point (AP) has a medium containing an arbitrary inter-frame interval (AIFS), minimum contention window (CWmin), and maximum contention window (CWmax) according to the weights for each access category (AC) of stations (STAs). Parameter values of the access algorithm can be adjusted.

Parameters used in hybrid media access (EDCA) may include an arbitrary inter-frame interval (AIFS), minimum contention window (CWmin), and maximum contention window (CWmax). Contention Window is a time range divided by slots that waits for a certain period of time (IFS) even after knowing that the shared medium is available, and waits randomly from then on.

The access point (AP) calculates the priority value of the stations (STAs) using the weight, queue size, and total buffer size for each access category (AC) of the stations (STAs) (504). The access point (AP) ignores stations (STAs) that do not have data frames to transmit in the priority calculation process. The access point (AP) can calculate the priority values of stations (STAs) using Equation 1 below.

Here, ⅰ is a natural number, STAi is a station (STA) in the basic service set (BSS), is the priority value of each station (STA), , , , is the size of the queue for each access category (AC), , , , is the weight for each access category (AC), AC_VO is voice, AC_VI is video, VO_BE is Best Effort, AC_BK is background, and is the congestion level of each station (STA).

An access point (AP) can calculate congestion using Equation 2 below.

here, is a value that matches the buffer occupancy rate expressed as a percentage by dividing the sum of the queue sizes of each access category (AC) by the total buffer size. For example, if the occupancy rate is less than 25 (%), is 0, if it is more than 25(%) but less than 50(%) is 1, if it is more than 50(%) but less than 75(%) is 2, if it is more than 75(%) and 100(%) can be 3. Accordingly, in the case of the same access category, a station (STA) with many packets in the buffer can obtain a higher priority than a station (STA) with relatively few packets.

The weight for each access category (AC) is determined based on the application traffic type. For example, multiple VoIP call processing (AC_VO) has a weight of 4, multiple video stream processing (AC_VI) has a weight of 3, Internet browsing (search, etc.) processing (VO_BE) has a weight of 2, and file transfer and printing processing (AC_BK). The weight of can be determined to be 1.

The relationship between weights for each access category (AC) is as shown in Equation 3 below.

The meaning of Equation 3 is that the priority of one traffic type affects the priorities of other traffic types.

The access point (AP) determines priorities between stations (STAs) according to the priority values of the stations (STAs), the priorities between the stations (STAs), the number of stations (STAs) with data frames to transmit, and Resources are allocated to stations (STAs) with priority using available resource unit (RU) information (505).

If the number of stations (STAs) with data frames to transmit is greater than the number of available resource units (RUs), the access point (AP) can allocate resources to the stations (STAs) in order of higher priority. The access point (AP) can calculate the bandwidth of the resource unit (RU) using Equation 4 below.

Here, RUCBW is the approximate bandwidth that can be allocated to a station (STA) based on the value of n, t is the number of available resource units (RU), and r is the number of stations (STAs) with data frames to transmit. An access point (AP) may correspond an approximate bandwidth (RUCBW) to a bandwidth value (MHz) associated with a resource unit (RU) type. The relationship between resource unit (RU) type and bandwidth is shown in Table 1.

Resource Unit (RU) Type Resource Unit (RU) Bandwidth 26-tone 2 MHz 52-tone 4 MHz 106-tone 8 MHz 242-tone 20 MHz 484-tone 40 MHz 996-tone 80 MHz

The access point (AP) calculates the approximate bandwidth (RUCBW) based on Equation 4 and then corresponds to the bandwidth value (MHz) related to the resource unit (RU) type in Table 1 to obtain n resource unit (RU) types. is assigned to stations (STAs) with n priorities.

The access point (AP) transmits a trigger frame (TF) to induce uplink transmission of the stations (STA1, STA2, and STA3) (506). When the stations (STA1, STA2, and STA3) receive a trigger frame (TF) from the access point (AP), they transmit an uplink data frame to the AP on a subchannel in response (507). The trigger frame (TF) is the length of the uplink data frame for each of the stations (STA1, STA2, STA3), the uplink bandwidth that determines the number of resource units (RU) that can be allocated in a given transmission opportunity (TXOP), and the guard interval. It may include the length of , information about the modulation and coding scheme (MCS) used for uplink transmission, and information about transmission power.

In the above, the present invention has been described with specific details such as specific components and limited embodiments and drawings, but this is only provided to facilitate a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , a person skilled in the art to which the present invention pertains can make various modifications and variations from this description.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and the scope of the patent claims described below as well as all modifications equivalent to or equivalent to the scope of the claims fall within the scope of the spirit of the present invention. They will say they do it.

Claims (4)

A quality of service-based orthogonal frequency division multiple access scheduling method in short-range wireless networks,
An access point (AP) transmitting a buffer status report (BSR) polling message to stations (STAs) in a basic service set (BSS);
An access point (AP) receiving a BSR frame including the queue size and total buffer size for each access category from stations (STAs);
An access point (AP) determining a weight for each access category (AC) of the stations (STAs);
An access point (AP) calculating priority values of stations (STAs) using weights, queue sizes, and total buffer sizes for each access category (AC) of the stations (STAs);
An access point (AP) determines priorities between stations (STAs) according to the priority values of the stations (STAs), and the priorities between the stations (STAs) and the number of stations (STAs) with data frames to transmit and allocating resources to a station (STA) with priority using available resource unit (RU) information,
In the step where the access point (AP) calculates the priority value of the stations (STAs) using the weight, queue size, and total buffer size for each access category (AC) of the stations (STAs),
The access point (AP) further includes calculating the congestion level using the queue size and total buffer size for each access category (AC) of the stations (STAs),
The priority value is calculated by Equation 1 below. A quality of service-based orthogonal frequency division multiple access scheduling method in a short-range wireless network.
[Equation 1]

ⅰ is a natural number, STAi is a station (STA) in the basic service set (BSS),
is the priority value of each station (STA),
, , , is the size of the queue for each access category (AC),
, , , is the weight for each access category (AC),
AC_VO is voice, AC_VI is video, VO_BE is Best Effort, AC_BK is background,
and is the congestion rate of each station (STA).
In claim 1,
The step of the access point (AP) determining a weight for each access category (AC) of the stations (STAs),
The access point (AP) includes an arbitrary inter-frame interval (AIFS), minimum contention window (CWmin), and maximum contention window (CWmax) according to weights for each access category (AC) of the stations (STAs). Further comprising adjusting parameter values of the medium access algorithm,
Quality of service based orthogonal frequency division multiple access scheduling method in short-range wireless networks. delete In claim 1,
In the step where the access point (AP) calculates congestion using the queue size and total buffer size for each access category (AC) of the stations (STAs),
A quality of service-based orthogonal frequency division multiple access scheduling method in a short-range wireless network, wherein the congestion is calculated by Equation 2 below.
[Equation 2]

is a value that divides the sum of the queue sizes of each access category (AC) by the total buffer size and matches the buffer occupancy rate expressed as a percentage,
If the market share is less than 25 (%) is 0,
If it is 25(%) or more but less than 50(%) is 1,
If it is more than 50(%) but less than 75(%) is 2,
If it is 75(%) or more and 100(%) is 3.

Images