KR102494091B1 - Apparatus and method for transmitting and receiving ACK in wireless communication system - Google Patents

Abstract

The present invention transmits a request for an ACK frame or a broadcast frame in which additional transmission of an ACK request frame requesting an ACK frame is set, and receives at least one of the broadcast frame or the ACK request frame. Each of at least one ACK transmission device ACK of a wireless communication system capable of improving reliability of a broadcast frame by determining whether to retransmit a broadcast frame based on the power of the received ACK frame when an ACK frame transmitted using the same resource is received from It is possible to provide a transmission and reception device and method.

Description

Apparatus and method for transmitting and receiving ACK in wireless communication system}

The present invention relates to an apparatus and method for transmitting and receiving an ACK in a wireless communication system, and relates to an apparatus and method for transmitting and receiving an ACK for a broadcast frame in a wireless communication system.

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

Standards using the wireless LAN are mainly developed as IEEE 802.11 standards at the Institute of Electrical and Electronics Engineers (IEEE). The IEEE 802.11 standard was developed and standardized in such a way as to revise it through subsequent versions, starting with an initial version supporting 1 to 2 Mbps. The revision of IEEE 802.11a uses Orthogonal Frequency Division Multiplexing (OFDM) in the 5 GHz band to support up to 54 Mbps, and IEEE 802.11b supports Direct Sequence Spread Spectrum (DSSS). ) method, it supports transmission rates of up to 11 Mbps in the 2.4 GHz band where the initial version operates.

Since then, due to the demand for more improved speed, the IEEE 802.11n revision including High Throughput (HT) wireless LAN technology operates in the OFDM method, and expands the channel bandwidth and MIMO (multiple input multiple output) was developed to improve the maximum transmission speed. As a result, the maximum transmission rate has been improved to support up to 600 Mbps when using 4 spatial steam (SS) and 40 MHz bandwidth.

As the wireless LAN technology is developed and popularized, applications using the wireless LAN technology diversify, resulting in a demand for a wireless LAN technology supporting a higher throughput. Accordingly, in the IEEE 802.11ac revision, the frequency bandwidth used is further expanded (up to 160 MHz or 80+80 MHz), and the number of supported spatial streams is expanded to support a high throughput of 1 Gbps or more (Very High Throughput: VHT) wireless LAN technology was reflected. In addition, the standard supports downlink transmission toward multiple terminals by utilizing MIMO.

On the other hand, among wireless LAN technologies, specific operations such as fast handoff (fast BSS transition), fast initial link setup, technology for low-power terminals operating in a band below 1 GHz, and wireless LAN technology for in-vehicle terminals are performed. The standard technology for the was also developed and reflected, and each revision of the standard was enacted. In particular, the wireless LAN technology for vehicle terminals is reflected in IEEE 802.11p, is based on a signal format in IEEE 802.11a and Enhanced Distributed Channel Access (EDCA) in IEEE 802.11e, and operates in a 5.9 GHz band. In addition, while based on a 10 MHz bandwidth to suit highly mobile terminals, the terminal does not go through authentication and coupling processes with a base station or an access point (AP). Can directly perform communication between vehicle terminals OCB (Outside Context of BSS) is supported.

On the other hand, as more sensors and operations are developed in vehicle communication operations, applications for corresponding operations are diversified, and demand for improving a higher throughput and transmission distance for the IEEE 802.11p arises, resulting in a new The need for wireless LAN technology development has increased. Accordingly, IEEE 802.11bd is being developed and standardized to establish a wireless LAN standard for next-generation vehicle communication (Next Generation V2X, NGV). The IEEE 802.11bd aims to support higher throughput, reliability and transmission distance. Accordingly, in IEEE 802.11bd, a technique for transmitting high-capacity data at a high rate using a 20 MHz bandwidth was proposed and reflected in order to support a higher throughput, and a signal type for a higher transmission distance was proposed and reflected. It became.

However, as OCB is supported in vehicle communication, communication between vehicle terminals increases, and a case in which a specific vehicle terminal transmits a broadcast frame (or multicast frame or groupcast frame) to a plurality of nearby vehicle terminals frequently occurs. do. In addition, there are frequent cases in which a roadside device or the like transmits a broadcast frame to a plurality of nearby vehicle terminals.

However, in the existing wireless communication system, even if a vehicle or a roadside device transmits a broadcast frame, it cannot be confirmed whether nearby terminals have normally received the broadcast frame. That is, an operation capable of increasing transmission reliability for broadcast frame transmission is not clearly defined. In particular, since a retransmission method for frame collision as the number of transmitting terminals increases is not defined, it needs to be improved.

Korean Registered Patent No. 10-1781194 (registered on September 18, 2017)

An object of the present invention is to provide an apparatus and method for transmitting and receiving an ACK that can increase transmission reliability of a broadcast frame by receiving an ACK frame from a plurality of terminals by transmitting an ACK frame request together when transmitting a broadcast frame in a wireless communication system. there is.

Another object of the present invention is to provide an apparatus and method for transmitting and receiving ACKs, which can minimize resource use for ACK frame transmission by allowing a plurality of terminals to simultaneously transmit a plurality of ACK frames using the same resource.

Another object of the present invention is to provide an apparatus and method for transmitting and receiving an ACK capable of determining whether a broadcast frame is normally transmitted based on the power of a plurality of ACK frames simultaneously transmitted through the same resource.

In order to achieve the above object, an ACK receiving apparatus in a wireless communication system according to an embodiment of the present invention transmits a broadcast frame in which whether to additionally transmit a request for an ACK frame or an ACK request frame requesting an ACK frame is set, and the When ACK frames transmitted using the same resource are received from at least one ACK transmitting device that has received at least one of a broadcast frame or an ACK request frame, retransmission of the broadcast frame based on the power of the received ACK frame determine whether

The ACK receiving device transmits the broadcast frame by setting at least one of a request for the ACK frame or whether to additionally transmit the ACK request frame in the MAC header of the broadcast frame, and in the MAC header of the broadcast frame If it is configured to additionally transmit the ACK request frame, the ACK request frame may be transmitted after a predetermined time from the end of transmission of the broadcast frame.

The ACK receiving device sets and transmits whether or not to additionally transmit a NAK request frame in the MAC header of the broadcast frame or the MAC header of the ACK request frame, and simultaneously from at least one ACK transmitting device receiving the NAK request frame When a NAK frame transmitted using the same resource is received, it is possible to determine whether to retransmit the broadcast frame based on a power ratio of the power of the ACK frame and the received NAK frame.

After the ACK receiving device transmits the broadcast frame or the ACK request frame, a plurality of ACK frames in a time interval in which the ACK frame is to be received or in a time interval in which the NAK frame is to be received after transmitting the NAK request frame Alternatively, when an arbitrary busy signal is detected due to asynchronous overlapping of a plurality of NAK frames, it is possible to determine whether to retransmit the broadcast frame by detecting the power of the detected busy signal.

The ACK receiver designates and transmits a time for the at least one ACK transmitter to transmit an ACK frame in the MAC header of the broadcast frame or the MAC header of the ACK request frame, and transmits the ACK in the MAC header of the NAK request frame The device may transmit the NAK frame by designating a time to transmit.

When the ACK receiving device additionally transmits the ACK request frame, the same sequence number may be set and transmitted in the MAC header of the broadcast frame and the MAC header of the ACK request frame.

In order to achieve the above object, an ACK transmission apparatus of a wireless communication system according to another embodiment of the present invention determines whether a request for an ACK frame or additional transmission of an ACK request frame is set in a received broadcast frame, and the ACK If additional transmission of the request frame is set, the ACK request frame is received, and the broadcast frame or the predetermined ACK frame requested by the ACK request frame is used at the same time as other ACK transmitters at a predetermined time using the same resource and send it

In order to achieve the above object, an ACK receiving method in a wireless communication system according to another embodiment of the present invention includes transmitting a broadcast frame in which whether to additionally transmit a request for an ACK frame or an ACK request frame requesting an ACK frame is set ; and when ACK frames transmitted simultaneously using the same resource are received from at least one ACK transmitter receiving at least one of the broadcast frame or the ACK request frame, based on the power of the received ACK frame, the broadcast frame It includes the step of determining whether to retransmit the.

In order to achieve the above object, an ACK transmission method in a wireless communication system according to another embodiment of the present invention includes determining whether a request for an ACK frame or an additional transmission of an ACK request frame is configured in a received broadcast frame; receiving the ACK request frame if additional transmission of the ACK request frame is configured; and transmitting a predefined ACK frame requested by the broadcast frame or the ACK request frame at a predefined time using the same resource as other ACK transmission methods.

Therefore, the apparatus and method for transmitting and receiving ACKs in a wireless communication system according to an embodiment of the present invention includes or additionally transmits an ACK frame request or a NAK frame request when transmitting a broadcast frame in a wireless communication system, and transmits an ACK frame from multiple terminals Alternatively, reliability of the broadcast frame may be improved by determining whether the broadcast frame is normally transmitted by receiving the NAK frame. In particular, when an ACK frame is requested, resource use for transmitting an ACK frame can be minimized by allowing a plurality of terminals to simultaneously transmit the ACK frame using the same resource. In addition, by analyzing the power of a plurality of ACK frames and NAK frames received using the same resource at the same time, it is possible to easily determine whether a broadcast frame is normally transmitted or not, and to perform additional operations such as retransmission.

1 shows an example of a wireless communication system environment in which vehicle terminals communicate with each other.
2 shows an example of a hierarchical structure of a terminal according to this embodiment.
3 shows an example of broadcast transmission and transmission/reception of an ACK frame.
4 shows an example of an ACK request frame structure.
5 illustrates another example of an operation of transmitting and receiving an ACK frame for broadcast for checking whether transmission of a broadcast frame is successful.
6 shows an example of a NAK request frame structure.
7 shows another example of an operation of transmitting and receiving an ACK frame for broadcast for checking whether transmission of a broadcast frame is successful.
8 shows a method for receiving an ACK in a wireless communication system according to an embodiment of the present invention.
9 shows an ACK transmission method in a wireless communication system according to an embodiment of the present invention.
10 shows an apparatus for transmitting and receiving an ACK in a wireless communication system according to an embodiment of the present invention.

In order to fully understand the present invention and its operational advantages and objectives achieved by the practice of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the described embodiments. And, in order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals in the drawings indicate the same members.

Throughout the specification, when a part "includes" a certain component, it means that it may further include other components, not excluding other components unless otherwise stated. In addition, terms such as "... unit", "... unit", "module", and "block" described in the specification mean a unit that processes at least one function or operation, which is hardware, software, or hardware. And it can be implemented as a combination of software.

1 shows an example of a wireless communication system environment in which terminals communicate with each other.

In a wireless communication system (or wireless LAN) environment according to the present embodiment, the terminal (STA) may be a vehicle terminal (STA) provided in each of a plurality of vehicles as an ACK transmitting device or a receiving device to perform mutual communication. In addition, the terminal STA may be a roadside terminal installed in a roadside device such as a street light or a traffic light to perform communication with a vehicle terminal STA installed in a nearby vehicle, or may be a terminal of another wireless communication device. In addition, a plurality of terminals (STAs) may perform mutual communication by performing a wireless LAN operation.

In the wireless communication system environment as shown in FIG. 1, a terminal (STA) may not perform scanning, authentication, and combining operations performed in existing wireless LAN operations, and data data does not belong to a specific Basic Service Set (BSS). It may be an OCB (Outside the Context of BSS) environment capable of transmitting and receiving.

In FIG. 1 , each of the plurality of vehicle terminals (STAs) may sense a specific situation or perform a designated specific operation through various sensors provided in the vehicle. In addition, as a result of the detected information or operation, data including the location, speed, acceleration, and sensor measurement result of the vehicle may be transmitted to a plurality of nearby vehicle terminals in the form of a broadcast frame. In addition, broadcast frames transmitted by other vehicle terminals (STAs) or various other frames may be received.

Meanwhile, the roadside device may transmit a map of the surrounding situation and a specific event (eg, accident and congestion information on the road ahead) in the form of a broadcast frame, and each STA receives the broadcast frame. can do.

Here, the vehicle terminal or the roadside terminal may transmit a broadcast frame for a specific event in an emergency situation (eg, accident information and failure information of the corresponding vehicle). In addition, since the broadcast frame for a specific event requires high reliability that must be received by neighboring vehicle terminals (STAs), transmission success must be guaranteed, unlike a general broadcast frame. Therefore, in this embodiment, a terminal (STA) transmitting a broadcast frame must be able to determine whether the transmitted broadcast frame is normally received by a plurality of vehicle terminals (STAs) and retransmit the broadcast frame according to the determination result.

However, in the existing wireless LAN operation, since the operation of the terminal (STA) that received the broadcast frame was not defined, the terminal (STA) that transmitted the broadcast frame could not determine whether the broadcast frame was normally transmitted.

Therefore, in this embodiment, an ACK request is transmitted together with a broadcast frame transmission so that a terminal (STA) that has received the broadcast frame transmits the ACK frame so that it can be determined whether or not the broadcast frame is normally transmitted. In this case, the ACK request may be included in the transmitted broadcast frame and transmitted together, or may be transmitted separately from the broadcast frame in the form of an ACK request frame.

Each of a plurality of STAs may transmit and receive various frames. Hereinafter, a terminal transmitting a broadcast frame is referred to as a transmitting terminal (Tx STA), and a terminal receiving a broadcast frame is referred to as a receiving terminal (Rx STA). ) is called Here, the transmitting terminal (Tx STA) may be referred to as an ACK receiving device because it receives an ACK frame for a broadcast frame transmitted later, and the receiving terminal (Rx STA) may be referred to as an ACK transmitting device since it receives an ACK frame.

That is, each of a plurality of STAs may transmit or receive a broadcast frame or an ACK frame.

2 shows an example of a hierarchical structure of a terminal according to this embodiment.

In this embodiment, a terminal (STA) may perform a communication operation in a Dedicated Short Range Communication (DSRC) method. Referring to FIG. 2, a terminal (STA) performing DSRC communication is a transport layer that guarantees transmission reliability between both ends under an application layer (not shown), which is the uppermost layer. UDP/TCP performing the operation of (110), IPv6 performing the operation of the Networking layer (120) that finds a transmission route between several nodes and forwards it to the corresponding route, and Data Link Layer (Data Link Layer) for point-to-point transmission. Layer) of LLC (Logical Link Control) layer 131, MAC (Medium Access Control) layer 132, and a physical layer (PHY) 140 that transmits actual signals.

However, as shown in FIG. 1, when the terminal is a vehicle terminal provided in a vehicle and performs inter-vehicle communication, the transmitting terminal directly transmits the corresponding data to the receiving terminal, so the process of transmitting data to the destination through several terminals. this is not needed Therefore, since the roles of the transport layer and the data link layer in the existing network layer are not required, the functions of the transport layer 110 and the data link 120 layer as shown in FIG. (hereinafter referred to as WSMP) (150) to simplify it.

Meanwhile, for operation in each layer, corresponding data and additional information may be transmitted through a service access point (SAP) in an upper layer or a lower layer. For example, the LLC 131 transmits data and parameters such as a source address and a destination address from the WSMP 150 or IPv6 160 to a link service access point (hereinafter referred to as LSAP). ) (160). In particular, in the case where the data is transmitted through the WSMP 150, the channel load measured by the terminal may be delivered through the LSAP 160. WAVE Medium Access Control (MAC) 132 may exchange data to be transmitted and parameters for transmission operations through LLC 131, which is an upper layer, and MAC SAP 170. During frame transmission, the MAC layer 132 may transmit a frame transmission request in the form of MA-UNITDATA.request, which is a SAP parameter used in an existing wireless LAN, from the LLC 131 through the MAC SAP 170. Alternatively, it can be delivered in the form of MA-UNITDATAX.request with parameters for WAVE-related operations added to MA-UNITDATA.request. MA-UNITDATAX.request can be configured as follows.

Among the parameters included in the above MA-UNITDATAX.request, the Channel Identifier is set to the Channel Identifier included in the request primitive in WSM, indicates a channel to transmit WSM, and Time Slot is channel switching of WAVE. In conjunction with (channel switching), it can be set to 0 or 1 as a time slot in which the corresponding message will be transmitted. Data Rate represents the data rate used when transmitting the corresponding WSM, TxPwr_Level represents the transmission power to be used when transmitting the WSM, and WsmExpiryTime is an option included when transmitting to WSMP. Do not send messages. Finally, High Reliability is a parameter indicating whether reliable transmission is required when transmitting WSM, and can be set to a value of 0 or 1.

As described above, among the parameters delivered through the MAC SAP 170, High Reliability indicates whether the corresponding WSM is a message requiring high reliability, and if the corresponding parameter indicates data requiring high reliability, the MAC layer 132 ) can perform high-reliability transmission.

3 shows an example of broadcast transmission and transmission/reception of an ACK frame, and FIG. 4 shows an example of an ACK request frame structure.

Referring to FIG. 3 , a transmitting terminal (Tx STA) may transmit a broadcast frame (or multicast frame or groupcast frame) 210 to neighboring terminals (STAs). Here, the neighboring terminal (STA) may be a vehicle terminal equipped in the vehicle together with the transmitting terminal (Tx STA), or may be a terminal in a pre-grouped group.

In this embodiment, a transmitting terminal (Tx STA) may transmit a frame in an Enhanced Distributed Channel Access (EDCA) scheme. In EDCA, when a transmitting terminal (Tx STA) wants to transmit a frame, it first checks the channel state. At this time, the channel state can be confirmed through physical detection of a signal, virtual detection through a PHY preamble, network allocation vector (NAV) setting analysis through a duration field in a MAC header, and the like. The transmitting terminal (Tx STA) checks the channel state to transmit the frame during AIFS (Arbitrary Inter-frame Space) time, and transmits the frame if the channel is empty during the AIFS time. At this time, different access categories (hereinafter ACs) may be designated according to the type of frame to be transmitted, and the AIFS value may be different according to each designated AC. For example, when AIFSN (AIFS number) is set for each AC, AIFS may be calculated and set as (Short Inter-frame Space) + AIFSN ㅧ (aSlotTime).

On the other hand, if the channel becomes busy during the AIFS time, or if another frame transmission procedure is performed immediately before the frame transmission, after confirming that the channel is empty during the AIFS time, additionally waiting for a random time A backoff procedure may be performed. At this time, a backoff value is randomly set among numbers between 0 and a predetermined contention window (CW), and may additionally wait for a time corresponding to the set backoff value. Here, CW may be set to a different value for each AC. If the channel is empty, the set backoff value is reduced by 1 per aSlotTime, and frame transmission can be performed when the backoff number becomes 0. However, if the channel becomes busy during the backoff procedure, the backoff procedure is stopped, and when the corresponding channel becomes empty again, the channel is sensed during the AIFS time and the remaining backoff number is used for the time corresponding to the number of backoffs. Additionally, the frame may be transmitted by waiting.

In this embodiment, when the frame to be transmitted is a broadcast frame 210 according to a predetermined event for notifying nearby vehicles of an emergency situation, such as accident information or vehicle failure information, the transmitting terminal (Tx STA) transmits the surrounding Transmission reliability may be increased by checking whether the terminal (STA) normally receives the broadcast frame 210 . In this embodiment, the transmitting terminal (Tx STA) may request transmission of an ACK frame from the receiving terminal (Rx STA) having received the broadcast frame 210 in order to check whether transmission of the broadcast frame 210 is successful. .

For example, when the High Reliability parameter is set to 1 in MA-UNITDATAX.request transmitted through the MAC SAP 170, the transmitting terminal (Tx STA) may determine that an event requiring high reliability has occurred. Accordingly, the transmitting terminal (Tx STA) requests transmission of the ACK frame 230 from the receiving terminal (Rx STA) receiving the broadcast frame 210 while transmitting the broadcast frame 210 to the neighboring terminals (STAs). can At this time, as shown in FIG. 3, the ACK frame 230 transmission request is performed by transmitting a broadcast frame 210 and a separate ACK request frame 220, or a predetermined specific It can be performed by setting and transmitting an ACK frame request in the field.

In the case of implicitly transmitting an ACK frame request in the broadcast frame 210 without transmitting the broadcast frame 210 and the separate ACK request frame 220, the transmitting terminal (Tx STA) transmits the broadcast frame In the MAC header of 210, the duration field (Duration field) may be transmitted by including the time for the receiving terminal (Rx STA) to transmit the ACK frame 230.

However, when the broadcast frame 210 and the separate ACK request frame 220 are transmitted, the receiving terminal (Rx STA) receiving the broadcast frame 210 recognizes in advance that the ACK request frame 220 is additionally transmitted thereafter You should be able to. Therefore, when the transmitting terminal (Tx STA) wants to transmit the broadcast frame 210 and the separate ACK request frame 220, the More Data subfield value in the MAC header of the broadcast frame 210 By setting to 1 and transmitting, the receiving terminal (Rx STA) can recognize in advance that the ACK request frame 220 is transmitted and stably receive the ACK request frame 220.

In addition, the transmitting terminal (Tx STA) may transmit the ACK request frame 220 by including the time for the receiving terminal (Rx STA) to transmit the ACK frame 230 in the duration field 320 of the MAC header.

At this time, the transmitting terminal (Tx STA) transmits the ACK request frame 220 to the neighboring terminal (STA) after a predetermined time (eg, Short Inter-frame Space: SIFS) from the transmission end point of the broadcast frame. can

In addition, in some cases, the transmitting terminal (Tx STA) transmits the time at which the receiving terminal (Rx STA) receives the ACK request frame 220 and the ACK frame 230 in the duration field of the MAC header of the broadcast frame 210. ) may be transmitted including the time to transmit. That is, even if the transmitting terminal (Tx STA) transmits the ACK request frame 220 separately, the time to receive the ACK request frame 220 and the time to transmit the ACK frame 230 are all assigned to the MAC header of the broadcast frame 210. may be transmitted including

In addition, the transmitting terminal (Tx STA) transmits the MAC of the broadcast frame 210 and the ACK request frame 220 so that the receiving terminal (Rx STA) can transmit the ACK frame 230 corresponding to the transmitted broadcast frame 210 It can be transmitted by including a sequence number in the sequence number subfield of the header. Even if the receiving terminal (Rx STA) receives the ACK request frame 220, the transmitting terminal (Tx STA) receives the broadcast frame 210 previously transmitted, and the sequence number and sequence number of the received broadcast frame 210 This is to transmit the ACK frame 230 only when the sequence numbers of the ACK request frame 220 match.

The ACK request frame 220 may be configured identically or similarly to the existing Block Ack Request (BAR) frame. Referring to FIG. 4, the ACK request frame 220 includes a frame control field 310, a persistence field 320, a receiver address (RA) field 330, a transmitter address (TA) field 340, and a BAR control field ( 350), a BAR information field 360 and an FCS field 370. At this time, the frame control field 310, the duration field 320, and the FCS field 370 may be configured identically or similarly to the existing Block Ack Request (BAR) frame. However, a time for the receiving terminal (Rx STA) to transmit the ACK frame 230 may be set in the duration field 320 . In the RA field 330, when the current frame is the ACK request frame 220 for the broadcast frame 210, all bits of the corresponding field may be set to 1. However, when the current frame is not the ACK request frame 220 for the broadcast frame 210, but an ACK request frame for a group cast frame for a terminal in a pre-determined group, a group address may be set in the RA field 330. .

The BAR control field 350 may include a BAR ACK policy subfield 351, a BAR type subfield 352, a TID information subfield 354, and the like. In this case, the response of the receiving terminal (Rx STA) To request, the BAR ACK policy subfield 351 may be set to 0, and the BAR type subfield 352 may be set to 4 when receiving terminals (Rx STAs) request simultaneous transmission of the ACK frame 430. It can be. And the TID information subfield 354 may indicate the TID of the transmitted broadcast frame or group cast frame.

The BAR information field 360 may indicate a Fragment Number subfield 361 indicated as 0 and a Start Sequence Number field 362. At this time, if the value of the sequence number field of the transmitted broadcast frame or groupcast frame is not 0, the start sequence number field 362 will contain the same value as the value of the sequence number field of the broadcast frame or groupcast frame. can

Meanwhile, the receiving terminal (Rx STA) that has received the broadcast frame 210 can check the duration field of the received broadcast frame 210 to implicitly check whether there is an ACK frame transmission request. Alternatively, the receiving terminal (Rx STA) may check the More Data subfield of the broadcast frame 210 to determine whether the ACK request frame 220 is separately transmitted.

When transmission of the ACK frame 230 is implicitly requested by the duration field of the broadcast frame 210, the receiving terminal (Rx STA) transmits the time specified in the duration field from the end of transmission of the broadcast frame 210 (or The ACK frame 230 may be transmitted after a predetermined time (eg, SIFS). At this time, the transmitted ACK frame 230 may be a block ACK (BlockACK) frame.

Since the transmitting terminal (Tx STA) transmits the broadcast frame 210 to a plurality of neighboring terminals (STAs), the plurality of receiving terminals (Rx STAs) receiving the broadcast frame 210 transmit the ACK frame 230. can However, in this embodiment, a plurality of receiving terminals (Rx STAs) transmit the ACK frame 230 simultaneously using the same resource at the time designated in the duration field (or a predetermined time (eg, SIFS)) can

Meanwhile, when the receiving terminal (Rx STA) confirms that the ACK request frame 220 is separately transmitted by the More Data subfield of the received broadcast frame 210, from the transmitting terminal (Tx STA) It waits until the ACK request frame 220 is transmitted. As described above, the transmitting terminal (Tx STA) may transmit the ACK request frame 220 after a predetermined time (eg, SIFS) from the transmission end point of the broadcast frame 210, and the ACK request frame The receiving terminal (Rx STA) receiving 220 may transmit the ACK frame 230 after a predetermined time (eg, SIFS) from the transmission end point of the ACK request frame 220 . However, the receiving terminal (Rx STA) may transmit the ACK frame 230 at the time set in the duration field 320.

At this time, when the sequence number is included in the ACK request frame 220, the receiving terminal (Rx STA) determines whether a frame including the previous same sequence number has been received, and determines that a frame including the same sequence number has been received ACK frame 230 can be transmitted only when it is done. At this time, the transmitted ACK frame 230 may also be a block ACK frame similar to the ACK request frame 220.

In this embodiment, a plurality of receiving terminals (Rx STAs) may simultaneously transmit ACK frames 230 using the same resource in response to the broadcast frame 210 or the ACK request frame 220. This is to minimize resource consumption for transmitting the ACK frame 230.

Although a plurality of receiving terminals (Rx STAs) transmit the ACK frame 230 using the same resource, since the plurality of receiving terminals (Rx STAs) transmit the ACK frame 230 at the same time, the transmitting terminal (Tx STA) Simultaneous ACK (Simultaneous-ACK) frames 230 transmitted simultaneously by a plurality of receiving terminals (Rx STAs) may be received without collision between the plurality of ACK frames 230 .

The transmitting terminal (Tx STA) requests transmission of the ACK frame 230 to the receiving terminal (Rx STA) using the broadcast frame 210 or the ACK request frame 220, and the broadcast frame 210 or ACK It is determined whether the ACK frame 230 is detected within a predetermined time (eg, distributed coordination function inter-frame space time (DIFS)) from the time point at which the request frame 220 ends transmission.

The transmitting terminal (Tx STA) detects the power of the received ACK frame 230 when the ACK frame 230 is received, and if the power of the detected ACK frame 230 is greater than or equal to a predetermined reference power, a broadcast frame ( 210) is determined to have been normally transmitted. However, if the ACK frame 230 is not received or the detected power of the ACK frame 230 is less than the reference power, it is determined that the broadcast frame 210 is not normally transmitted. That is, it is determined that the STA has not received the broadcast frame 210 .

As described above, in this embodiment, a plurality of receiving terminals (Rx STAs) simultaneously transmit the same ACK frame 230 using the same resource. Therefore, in the case of simply detecting whether or not the ACK frame 230 has been received, even if only one receiving terminal (Rx STA) receives the broadcast frame 210 and transmits the ACK frame 230, the transmitting terminal (Tx STA) broadcasts It is determined that the frame 210 is normally transmitted. However, this is not a case where the broadcast frame 210 to be propagated to a plurality of STAs is normally transmitted. Therefore, in this embodiment, the transmitting terminal (Tx STA) uses the ACK frame 230 to determine whether multiple terminals (STAs) have received the broadcast frame 210 from the ACK frame 230 transmitted using the same resource at the same time. ), and determines whether the broadcast frame 210 is normally transmitted based on the detected power.

Even when determining whether the broadcast frame 210 is normally transmitted based on the power of the ACK frame 230, the number of receiving terminals (Rx STAs) that have received the broadcast frame 210 cannot be accurately determined. Nevertheless, since the approximate number of receiving terminals (Rx STAs) that have received the broadcast frame 210 can be estimated from the power of the ACK frame 230, whether or not the broadcast frame 210 is normally transmitted can be sufficiently determined. there is.

If the power of the ACK frame 230 is greater than or equal to the reference power, the transmitting terminal (Tx STA) determines that the broadcast frame 210 is normally transmitted and does not retransmit the broadcast frame 210.

However, when the ACK frame 230 is not received or the power of the ACK frame 230 is less than the reference power, the transmitting terminal (Tx STA) determines that transmission of the broadcast frame 210 has failed. In addition, when it is determined that transmission of the broadcast frame 210 has failed, a retransmission operation of the broadcast frame 210 may be performed. In this case, the CW for setting the backoff value for the retransmitted broadcast frame 210 may be set to CWx2-1 based on the CW for the previous broadcast frame 210.

In the above, it has been described that the transmitting terminal (Tx STA) determines whether the broadcast frame 210 is normally transmitted based on the power of the received ACK frame 230. However, in an actual wireless communication environment, in particular, as shown in FIG. 1, in a wireless LAN environment between vehicle terminals, due to various factors such as vehicle movement, even if a plurality of receiving terminals (Rx STAs) transmit simultaneous ACK frames 230, the transmitting terminal In (Tx STA), a plurality of ACK frames 230 may be received with a time difference. In this case, it is difficult for the transmitting terminal (Tx STA) to detect the ACK frame 230, and therefore, it may be determined that a random busy signal is received through the channel. However, in the present invention, since the transmitting terminal (Tx STA) detects the power of the ACK frame 230 only to determine whether the broadcast frame 210 is normally transmitted, there is no need to restore the received ACK frame 230. . Therefore, even if a plurality of ACK frames 230 are received in the form of an arbitrary busy signal with a time difference, the transmitting terminal (Tx STA) detects the power of the busy signal so that the broadcast frame 210 It is possible to determine whether transmission is normal.

As a result, in the ACK frame transmission and reception operation according to FIG. 3, the transmitting terminal (Tx STA) transmits an ACK request in the broadcast frame 210 or transmits an ACK request frame 220 separately from the broadcast frame 210 to , A plurality of receiving terminals (Rx STAs) receiving the broadcast frame 210 simultaneously transmit the ACK frame 230 using the same resource, and the ACK frame 230 transmitted from the plurality of receiving terminals (Rx STAs) ), it is possible to easily determine whether or not the broadcast frame 210 is normally transmitted. In addition, transmission reliability can be greatly improved by retransmitting the broadcast frame 210 according to the determination result.

FIG. 5 shows another example of an ACK frame transmission/reception operation for broadcast to check transmission success of a broadcast frame, and FIG. 6 shows an example of a NAK request frame structure.

In FIG. 5 , the transmitting terminal (Tx STA) transmits an ACK request frame 420 separately from the broadcast frame 410 similar to FIG. 3 . However, in FIG. 5, the transmitting terminal (Tx STA) may additionally request a NAK request frame 440 for checking whether the broadcast frame 410 is not received as well as the ACK request frame 420.

5, the transmitting terminal (Tx STA) may include the time for the receiving terminal (Rx STA) to transmit the ACK frame 230 in the duration field 320 of the broadcast frame 410 and transmit the broadcast frame 410 ) by setting the value of the additional data subfield (More Data subfield) to a predetermined value, at least one of the ACK request frame 420 or the NAK request frame 440 is transmitted. Can be notified to the receiving terminal (Rx STA) there is.

According to the setting of the broadcast frame 410, the transmitting terminal (Tx STA) may transmit the ACK request frame 420 after a predetermined time (eg, SIFS) from the end of transmission of the broadcast frame 410. . And, as shown in (a), when the transmitting terminal (Tx STA) receives the ACK frame 430 from the receiving terminal (Rx STA), a predetermined time (eg, SIFS), the NAK request frame 440 may be additionally transmitted.

At this time, the transmitting terminal (Tx STA) detects the power of the received ACK frame 430, determines whether the power of the ACK frame 430 is equal to or greater than a predetermined reference power, and if it is greater than or equal to the reference power, additionally sends a NAK request frame 440 can transmit In addition, the transmitting terminal (Tx STA) does not receive the NAK frame 450 from the receiving terminal (Rx STA), or even if the NAK frame 450 is received, the power of the ACK frame 430 and the power of the received NAK frame 450 If the ratio is less than the predetermined reference power ratio, the transmitting terminal (Tx STA) may determine that the broadcast frame 410 is not normally transmitted and retransmit the broadcast frame 410 .

On the other hand, the transmitting terminal (Tx STA) If the power ratio of the ACK frame 430 and the NAK frame 450 is greater than or equal to the reference power ratio, it is determined that the broadcast frame 410 is normally transmitted, and the broadcast frame 410 may not be retransmitted.

However, in some cases, the transmitting terminal (Tx STA) has a time difference between the plurality of ACK frames 430 transmitted from the plurality of receiving terminals (Rx STA), as in (b), and in the form of an arbitrary busy signal If the power of the transmitted and detected busy signal is greater than or equal to the reference power, the NAK request frame 440 can be additionally transmitted after a predetermined time (eg, SIFS) from the end of transmission of the busy signal. there is.

In addition, the transmitting terminal (Tx STA) may transmit the broadcast frame 410, the ACK request frame 420, and the NAK request frame 440 by including the sequence number in the sequence number subfield of the MAC header, respectively.

Since the structure of the ACK request frame 420 has already been described with reference to FIG. 4, it will not be described here. And, like the ACK request frame 420, the NAK request frame 440 may be configured identically or similarly to the existing Block Ack Request (BAR) frame. Referring to FIG. 6 , the NAK request frame 440 may basically have almost the same configuration as the ACK request frame 420 . In the duration field 320 of the NAK request frame 440, a time for the receiving terminal (Rx STA) to transmit the ACK frame 230 may be set. However, in the NAK request frame 440, the TA field 340 included in the ACK request frame 420 may be omitted. In the BAR control field 350, the BAR type subfield 352 may be set to 5 when receiving terminals (Rx STAs) request simultaneous transmission of the NAK frame 450.

When the receiving terminal (Rx STA) that has normally received the broadcast frame 410 determines that the ACK request frame 420 is separately transmitted by the More Data subfield of the received broadcast frame 410 , Waits until the ACK request frame 420 is transmitted from the transmitting terminal (Tx STA).

When the ACK request frame 420 is transmitted after a predetermined time (eg, SIFS) from the transmission end point of the broadcast frame 410 from the transmitting terminal (Tx STA), the broadcast frame 410 and the ACK request Upon receiving the frame 420, the receiving terminal (Rx STA) sends the ACK frame 430 to the transmitting terminal (Tx STA) after a predetermined time (eg, SIFS) from the transmission end point of the ACK request frame 420. transmit

When the NAK request frame 440 is received, the STA that does not normally receive the broadcast frame 410 receives a NAK after a predetermined time (eg, SIFS) from the transmission end point of the NAK request frame 440. The frame 450 is transmitted to the transmitting terminal (Tx STA).

Here, the terminal (STA) that has received the ACK request frame 420 or the NAK request frame 440 transfers the frame including the same sequence number as the sequence number included in the ACK request frame 420 or the NAK request frame 440 It is determined whether or not the frame has been received, and if it is determined that the frame including the same sequence number has not been received, the NAK frame 450 may be transmitted.

Here, each of the terminals (STAs) receiving the ACK request frame 420 may simultaneously transmit the ACK frame 430 using the same resource. In addition, each STA that has received the NAK request frame 440 may simultaneously transmit the NAK frame 450 through the same resource.

The transmitting terminal (Tx STA) determines whether the ACK frame 430 and the NAK frame 450 are detected. When the ACK frame 430 is detected and the NAK frame 450 is not detected, the transmitting terminal (Tx STA) may determine that the broadcast frame 410 is normally transmitted.

However, when the ACK frame 430 and the NAK frame 450 are detected, the transmitting terminal (Tx STA) detects the power of each of the detected ACK frame 430 and the NAK frame 450. Here, the ACK frame 430 is a frame transmitted by the receiving terminal (Rx STA) that has received the broadcast frame 410, whereas the NAK frame 450 is a terminal (STA) that has not received the broadcast frame 410 This is the transmitted frame. Therefore, the transmitting terminal (Tx STA) can determine the transmission success rate of the broadcast frame 410 by comparing the detected power of the ACK frame 430 and the power of the NAK frame 450 . If the ratio between the power of the ACK frame 430 and the power of the NAK frame 450 is greater than or equal to a predetermined reference power ratio, the transmitting terminal (Tx STA) determines that the broadcast frame 410 is normally transmitted. However, if the power ratio is less than the reference power ratio, it is determined that the broadcast frame 410 is not normally transmitted and the broadcast frame 410 may be retransmitted.

In addition, even if a plurality of terminals (STAs) transmit the ACK frame 430 or the NAK frame 450 at the same time, each of the ACK frame 430 and the NAK frame 450 is transmitted as shown in (b), the transmitting terminal (Tx It may be received in the form of an arbitrary busy signal with a time difference to the STA.

Accordingly, even when the transmitting terminal (Tx STA) does not accurately detect the ACK frame 430 and the NAK frame 450 and is detected in the form of a busy signal, the busy signal detected after transmitting the ACK request frame 420 ( Whether to retransmit the broadcast frame 410 may be determined based on a power ratio of a busy signal and a power ratio of a busy signal detected after transmission of the NAK request frame 440 .

Also here, the CW for setting the backoff value for the retransmitted broadcast frame 410 may be set to CWx2-1 based on the CW for the previous broadcast frame 410.

7 shows another example of an operation of transmitting and receiving an ACK frame for broadcast for checking whether transmission of a broadcast frame is successful.

Also in FIG. 7 , the transmitting terminal (Tx STA) transmits a broadcast frame 610 . However, as shown in (a) of FIG. 7, the transmitting terminal (Tx STA) does not transmit the ACK request frames 220 and 432 or the NAK request frame 440. In addition, the receiving terminal (Rx STA) that has received the broadcast frame 610 does not transmit the separately configured ACK frames 230 and 430 or the NAK frame 450, unlike in FIGS. 3 to 6, and the received broadcast frame Copy and transmit (610). That is, the received broadcast frame 610 can be transmitted using the ACK frame.

To this end, the transmitting terminal (Tx STA) sets a period until the operation of copying and transmitting the broadcast frame 610 ends in the duration field 320 of the MAC header of the broadcast frame 610, or Copying and retransmission of the broadcast frame 610 may be indicated through the type subfield of the frame control field 310. For example, the transmitting terminal (Tx STA) may set the type subfield of the frame control field 310 in the MAC header to 0101 to request copying and retransmission of the broadcast frame 610.

Accordingly, the receiving terminal (Rx STA) receiving the broadcast frame 610 can confirm that copying and retransmission of the broadcast frame 610 received from the MAC header of the broadcast frame 610 have been requested. The receiving terminal (Rx STA) may simultaneously transmit the received broadcast frame 610 using the same resource after a predetermined time (eg, SIFS) from the transmission end point of the broadcast frame 610. In addition, a terminal (STA) that has not received the broadcast frame 610 transmitted from the transmitting terminal (Tx STA) also transmits the broadcast frame 610 by the broadcast frame 610 retransmitted from the receiving terminal (Rx STA) is given an opportunity to receive However, in order to prevent transmission of the broadcast frame 610 by a plurality of terminals (STAs) from repeatedly occurring in a chain, the receiving terminal (Rx STA) partially modifies the MAC header of the received broadcast frame 610 can be retransmitted.

The transmitting terminal (Tx STA) may determine whether the broadcast frame 610 is normally transmitted based on the power of the broadcast frame 610 retransmitted from the receiving terminal (Rx STA).

However, as shown in (b), if the broadcast frame 610 retransmitted from the receiving terminal (Rx STA) is not received, the transmitting terminal (Tx STA) determines that the broadcast frame 610 is not normally transmitted Thus, the broadcast frame 610 can be retransmitted.

8 shows a method for receiving an ACK in a wireless communication system according to an embodiment of the present invention.

Referring to FIGS. 2 to 7, the ACK receiving method of the wireless communication system of FIG. 8 will be described. A transmitting terminal (Tx STA), that is, an ACK receiving device determines whether a broadcast frame to be transmitted exists (S11). And if it is determined that there is a broadcast frame to be transmitted, the broadcast frame is transmitted (S12). At this time, the ACK receiving device determines in advance whether the broadcast frame to be transmitted is a broadcast frame for a specific event requiring high reliability according to the High Reliability parameter value of MA-UNITDATAX.request transmitted through the MAC SAP (170). can be identified.

When the broadcast frame to be transmitted is determined to be a high reliability broadcast frame, the ACK receiving device may include an ACK request in the MAC header of the broadcast frame to be transmitted or notify that an ACK request frame will be additionally transmitted. When transmitting an ACK request by including an ACK request in the MAC header of the broadcast frame, the ACK receiving device may include a time for the transmitting device to transmit the ACK frame in a duration field of the MAC header and transmit the broadcast frame. However, if an ACK request frame is to be additionally transmitted, the value of the additional data subfield in the MAC header of the broadcast frame may be set to a predetermined value and transmitted.

Accordingly, the ACK receiving device determines whether transmission of the ACK request frame is necessary by setting an ACK request frame to be additionally transmitted using the MAC header of the broadcast frame and confirming whether the broadcast frame has been transmitted (S13).

When it is determined that transmission of the ACK request frame is necessary, the ACK receiving device transmits the ACK request frame (S14). The ACK receiving device may transmit the ACK request frame after a predetermined time (for example, SIFS) from the broadcast frame transmission end point. At this time, the ACK receiving device has a broadcast frame and an ACK request frame so that the receiving terminal (Rx STA) receiving the broadcast frame, that is, the ACK transmitting device, can identify whether the ACK request frame is an ACK request frame for a specific broadcast frame. The same sequence number may be included in the sequence number subfield of the MAC header and transmitted.

Then, the ACK receiving device simultaneously receives the ACK frame transmitted through the same resource from the ACK transmitting device that has received the broadcast frame (S15). Here, the ACK frame may receive an ACK frame transmitted simultaneously after a predetermined time (for example, SIFS) from the point in time when transmission of the broadcast frame or the ACK request frame is terminated. If the time to transmit the ACK frame is specified in the broadcast frame or the ACK request frame, the ACK frame transmitted at the specified time is received. The ACK receiving device detects the power of the received ACK frame (S16). Then, the ACK receiving device determines whether the detected power of the ACK frame is greater than or equal to a predetermined reference power (S17). If the power of the ACK frame is less than the reference power, it is determined that the broadcast frame was not normally transmitted, and the broadcast frame is retransmitted (S24).

On the other hand, if the power of the ACK frame is greater than or equal to the reference power, the ACK receiving device determines whether to additionally transmit a NAK request frame (S18). Whether to request an additional NAK request frame may be specified in advance in the ACK receiving device. If it is determined that there is no need to additionally transmit the NAK request frame, it is determined that the broadcast frame was normally transmitted, and the broadcast frame is not retransmitted (S19).

And when it is determined that the ACK receiving device needs to additionally transmit the NAK request frame, it transmits the NAK request frame (S20). At this time, the ACK receiving device may transmit the NAK request frame after a predetermined time (for example, SIFS) from the time when the transmission of the ACK frame from the ACK transmitting device is terminated. Then, the ACK receiving device determines whether NAK frames transmitted through the same resource are received from the ACK transmitting device that has not received the broadcast frame (S21). At this time, the NAK frame may receive the NAK frame transmitted simultaneously after a predetermined time (eg, SIFS) from the time when the transmission of the NAK request frame is terminated. If the time to transmit the NAK frame is specified in the NAK request frame, the NAK frame transmitted at the specified time can be received.

If the NAK frame is not received, the ACK receiving device determines that the broadcast frame is normally transmitted and does not retransmit the broadcast frame (S19). However, if it is determined that the NAK frame has been received, the ACK receiving device detects the power of the received NAK frame (S22). Then, it is determined whether the power ratio of the ACK frame and the NAK frame is greater than or equal to a predetermined reference power ratio. If the power ratio of the ACK frame and the NAK frame is equal to or greater than the reference power ratio, the ACK receiving device determines that the broadcast frame is normally transmitted and does not retransmit the broadcast frame (S19). However, if the power ratio of the ACK frame and the NAK frame is less than the reference power ratio, it is determined that the broadcast frame was not normally transmitted, and the ACK receiving device retransmits the broadcast frame (S24).

In the above, it has been described that the ACK receiving device receives simultaneously transmitted ACK frames or simultaneously transmitted NAK frames, but due to an unavoidable time difference, the ACK frames or NAK frames are not normally received and any busy signal type In this case, it is possible to determine whether the broadcast frame is normally transmitted by detecting the power of a busy signal.

9 shows an ACK transmission method in a wireless communication system according to an embodiment of the present invention.

Referring to FIGS. 2 to 7, the ACK transmission method of the wireless communication system of FIG. 9 will be described. A receiving terminal (Rx STA), that is, an ACK transmitting device determines whether a broadcast frame is received (S31). When the broadcast frame is received, the MAC header of the broadcast frame is analyzed to determine whether to wait for the ACK request frame (S32). If it is configured to additionally transmit an ACK request frame to the MAC header of the analyzed broadcast frame, the ACK transmitting device receives the ACK request frame transmitted from the ACK receiving device (S33).

In addition, when an ACK frame request is directly included in the MAC header of the broadcast frame or an ACK request frame is received, the broadcast frame or the ACK request frame is transmitted based on the MAC header setting of the received broadcast frame. An ACK frame is transmitted at a designated time (for example, SIFS) (S34). In this case, the ACK frame may be simultaneously transmitted through the same resource in a plurality of ACK transmitting apparatuses, and when the time to transmit the ACK frame is designated in the broadcast frame or the ACK request frame, the ACK frame may be transmitted at the designated time.

In addition, when sequence numbers are included in the received broadcast frame and the ACK request frame, the ACK transmission device may transmit the ACK frame only when the sequence numbers included in the broadcast frame and the ACK request frame are the same.

Meanwhile, the ACK transmitter determines whether to wait for the reception of the NAK request frame (S35). Here, the ACK transmitter may analyze the MAC of the broadcast frame or the ACK request frame to determine whether to wait for reception of the NAK request frame.

If it is determined that the NAK request frame is waiting to be received, the NAK request frame transmitted from the ACK receiving device is received (S36). In response to the received NAK request frame, the NAK frame is transmitted at a predetermined time (for example, SIFS) from the time when the transmission of the NAK request frame is terminated (S37). In this case, the NAK frame may also be simultaneously transmitted on the same resource by multiple ACK transmitters, and if the time to transmit the NAK frame is designated in the NAK request frame, the NAK frame may be transmitted at the designated time.

10 shows an apparatus for transmitting and receiving an ACK in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 10 , an ACK transmitter or an ACK receiver according to the present embodiment may include a processor 710, a memory 720, and a communication unit 730. The processor 710 may execute functions, operations, and methods performed by the ACK transmitting device or the ACK receiving device. For example, the processor 710 of the ACK receiving device may generate and transmit a broadcast frame, an ACK request frame, and a NAK request frame requiring high reliability, and transmit the ACK frame and the NAK request frame through the communication unit 730. By receiving the frame, it is possible to determine whether to retransmit the broadcast frame. And the processor 710 of the ACK transmission device analyzes the broadcast frame, ACK request frame, and NAK request frame received through the communication unit 730, generates an ACK frame and a NAK frame, and generates the ACK frame and the NAK frame It can be transmitted through the communication unit 730.

The memory 720 stores various data required for functions or operations to be executed by the processor 710 . The communication unit 730 transmits the frame transmitted from the processor 710 to another ACK receiving device or ACK transmitting device, or transmits the frame transmitted from the ACK receiving device or another ACK transmitting device to the processor 710. In this case, the communication unit 730 may detect power of a frame or a busy signal transmitted from an ACK receiving device or another ACK transmitting device and transmit the detected power to the processor 710 .

In the above, the ACK receiving device and the ACK transmitting device are separately described, but the ACK receiving device and the ACK sending device are short-term functionally divided into a device for receiving an ACK frame and a device for transmitting an ACK frame, and the same terminal is an ACK receiving device It may be the ACK transmission/reception device 700 that operates as an ACK transmission device or operates as an ACK transmission device.

The method according to the present invention may be implemented as a computer program stored in a medium for execution on a computer. Here, computer readable media may be any available media that can be accessed by a computer, and may also include all computer storage media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, including read-only memory (ROM) dedicated memory), random access memory (RAM), compact disk (CD)-ROM, digital video disk (DVD)-ROM, magnetic tape, floppy disk, optical data storage device, and the like.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is only exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (20)

In a wireless communication system,
Transmitting a broadcast frame in which whether to additionally transmit a request for an ACK frame or an ACK request frame requesting an ACK frame is set;
When ACK frames transmitted using the same resource are received from at least one ACK transmitting device that has received at least one of the broadcast frame or the ACK request frame at the same time,
detecting only power without restoring the received ACK frame;
Determining that the broadcast frame is normally transmitted when the power of the detected ACK frame is greater than or equal to a predetermined reference power, and determining that the broadcast frame is not normally transmitted when the power of the detected ACK frame is less than the predetermined reference power ACK receiving device. The method of claim 1, wherein the ACK receiving device
Transmitting the broadcast frame by setting at least one of a request for the ACK frame or whether to additionally transmit the ACK request frame in the MAC header of the broadcast frame,
If it is set to additionally transmit the ACK request frame in the MAC header of the broadcast frame, the ACK receiving device transmits the ACK request frame after a predetermined time from the transmission end point of the broadcast frame. The method of claim 2, wherein the ACK receiving device
Setting whether to additionally transmit a NAK request frame in the MAC header of the broadcast frame or the MAC header of the ACK request frame and transmitting it;
When NAK frames transmitted using the same resource are received from at least one ACK transmitter that has received the NAK request frame at the same time,
ACK receiving device for determining whether to retransmit the broadcast frame based on the power ratio of the ACK frame and the received NAK frame. The method of claim 3, wherein the ACK receiving device
After transmitting the broadcast frame or the ACK request frame, a plurality of ACK frames or a plurality of NAK frames in a time interval in which the ACK frame is to be received or in a time interval in which the NAK frame is to be received after transmitting the NAK request frame When an arbitrary busy signal is detected due to asynchronous overlap of , the ACK receiving device determines whether to retransmit the broadcast frame by detecting the power of the detected busy signal. The method of claim 3, wherein the ACK receiving device
The at least one ACK transmitter designates and transmits a time to transmit an ACK frame in the MAC header of the broadcast frame or the MAC header of the ACK request frame, and the ACK transmitter transmits a NAK frame in the MAC header of the NAK request frame An ACK receiving device that transmits by specifying the transmission time. The method of claim 2, wherein the ACK receiving device
When the ACK request frame is additionally transmitted, the same sequence number is set in the MAC header of the broadcast frame and the MAC header of the ACK request frame and transmitted. In a wireless communication system,
Determine whether a request for an ACK frame or additional transmission of an ACK request frame is set in the received broadcast frame;
If additional transmission of the ACK request frame is configured, the ACK request frame is received,
Transmitting a predetermined ACK frame requested by the broadcast frame or the ACK request frame at a predetermined time using the same resource as another ACK transmitter at the same time;
If a request for the ACK frame is set in the MAC header of the broadcast frame, the ACK frame is transmitted at a predetermined time after transmission of the broadcast frame is terminated;
If additional transmission of the ACK request frame is set in the MAC header of the broadcast frame, the ACK frame is transmitted at a predetermined time after transmission of the ACK request frame is terminated;
The MAC header of the broadcast frame and the sequence number set in the MAC header of the ACK request frame are compared, and the ACK frame is transmitted when the sequence numbers are the same;
ACK transmission apparatus for comparing the MAC header of the broadcast frame with the sequence number set in the MAC header of the ACK request frame, and transmitting the ACK frame when the sequence numbers are the same.
delete delete The method of claim 7, wherein the ACK transmitter
If additional transmission of a NAK request frame is set in the MAC header of the ACK request frame, the NAK request frame is received;
If the broadcast frame is not received before the NAK request frame is received, the ACK transmitter transmits a predetermined NAK frame at a predetermined time simultaneously with other ACK transmitters using the same resource. In the ACK receiving method of the ACK receiving apparatus of the wireless communication system,
Transmitting a broadcast frame in which whether to additionally transmit a request for an ACK frame or an ACK request frame requesting an ACK frame is set;
receiving ACK frames simultaneously transmitted using the same resource from at least one ACK transmitting apparatus that has received at least one of the broadcast frame and the ACK request frame;
detecting only power without restoring the received ACK frame;
determining that the power of the detected ACK frame is greater than or equal to a predetermined reference power and that the broadcast frame is normally transmitted; and
and determining that the broadcast frame is not normally transmitted if the power of the detected ACK frame is less than a predetermined reference power.
12. The method of claim 11, wherein transmitting the broadcast frame
setting and transmitting at least one of a request for the ACK frame or whether to additionally transmit the ACK request frame in the MAC header of the broadcast frame; and
If it is set to additionally transmit the ACK request frame in the MAC header of the broadcast frame, transmitting the ACK request frame after a predetermined time from the end of transmission of the broadcast frame. 13. The method of claim 12, wherein the ACK receiving method
Setting whether to additionally transmit a NAK request frame in the MAC header of the broadcast frame or the MAC header of the ACK request frame and transmitting the same; and
When NAK frames transmitted simultaneously using the same resource are received from each of the at least one ACK transmitter that has received the NAK request frame, whether to retransmit the broadcast frame is determined by the power ratio of the power of the ACK frame and the received NAK frame ACK receiving method further comprising the step of determining based on. 14. The method of claim 13, wherein determining based on the power ratio
After transmitting the broadcast frame or the ACK request frame, a plurality of ACK frames or a plurality of NAK frames in a time interval in which the ACK frame is to be received or in a time interval in which the NAK frame is to be received after transmitting the NAK request frame ACK receiving method for determining whether to retransmit the broadcast frame by detecting power of the detected busy signal when an arbitrary busy signal is detected due to asynchronous overlap of . 14. The method of claim 13, wherein transmitting the broadcast frame
Specifying and transmitting a time for the at least one ACK transmitter to transmit an ACK frame in a MAC header of the broadcast frame or a MAC header of the ACK request frame,
The step of setting and transmitting whether or not to additionally transmit the NAK request frame
An ACK receiving method in which the at least one ACK transmitting device designates and transmits a time to transmit a NAK frame in the MAC header of the NAK request frame. 13. The method of claim 12, wherein the transmitting of the broadcast frame comprises, when the ACK request frame is additionally transmitted, an ACK transmitted by setting the same sequence number to a MAC header of the broadcast frame and a MAC header of the ACK request frame. How to receive. In the ACK transmission method of an ACK transmission device in a wireless communication system,
determining whether a request for an ACK frame or an additional transmission of an ACK request frame is set in the received broadcast frame;
receiving the ACK request frame if additional transmission of the ACK request frame is configured; and
Transmitting a predetermined ACK frame requested by the broadcast frame or the ACK request frame at a predetermined time using the same resource as another ACK transmission method,
The step of transmitting using the same resource at the same time
comparing a MAC header of the broadcast frame with a sequence number set in a MAC header of the ACK request frame; and
Transmitting the ACK frame when the MAC header of the broadcast frame and the sequence number set in the MAC header of the ACK request frame are the same,
Transmitting the ACK frame
transmitting the ACK frame at a predetermined time after transmission of the broadcast frame ends when a request for the ACK frame is set in the MAC header of the broadcast frame; and
and transmitting the ACK frame at a predetermined time after transmission of the ACK request frame is terminated, if additional transmission of the ACK request frame is set in the MAC header of the broadcast frame.
delete delete 18. The method of claim 17, wherein the ACK transmission method
determining whether additional transmission of a NAK request frame is set in the MAC header of the ACK request frame;
If additional transmission of the NAK request frame is configured, receiving the NAK request frame; and
If the broadcast frame is not received before the NAK request frame is received, transmitting a pre-determined NAK frame at a pre-determined time using the same resource as another ACK transmission method at the same time.

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