Communication device and method

Abstract

The present disclosure relates to the concept of pre-emption of a PPDU, i.e. truncating a PPDU carrying non-delay-sensitive traffic to serve a STA with delay constraints. According to embodiments, a first communication device configured to communicate with a second communication device is provided. The first communication device comprises circuitry configured to receive a truncation notification during an ongoing exchange of data units with the second communication device, the truncation notification indicating that the ongoing transmission of the data units should be truncated, and to receive and / or transmit pre-emption data units from and / or to a third communication device, terminate the ongoing transmission of the data units before an estimated transmission time of the data units, and receive and / or transmit the pre-emption data units from and / or to the third communication device for a remaining duration of the truncated data units or for a remaining duration of a transmission opportunity established between the first and second communication device for the ongoing exchange of data units.

Description

Technical Field

[0001] This disclosure relates to first and second communication devices for communication therebetween. This disclosure also relates to corresponding communication methods. Background Technology

[0002] The WLAN implementation defined in IEEE 802.11-2016 uses packet-based data transmission. When one or more input data packets or MSDUs (MAC layer service data units) are present and the wireless channel is idle, these MSDUs are processed by the MAC layer into one or more MPDUs (MAC layer protocol data units) and then processed by the PHY layer, and then transmitted as PPDUs (physical layer protocol data units) to one or more peer WLAN communication devices.

[0003] Certain limitations apply to the length of such PPDUs measured over a wireless channel. Depending on the standards considered, these limitations restrict the maximum length or transmission time to a range of 2 ms to 10 ms (sometimes 20 ms). The transmission time is determined and fixed at the start of PPDU transmission. Longer transmission times are advantageous for high efficiency in communication because the overhead of gaining channel access, preamble transmission, and / or control frame transmission becomes negligible.

[0004] In low-latency communication scenarios, access points (APs) or stations (STAs) may want to transmit both non-latency-sensitive and latency-sensitive data packets. Typically, the arrival of latency-sensitive packets is random, unknown, and unpredictable. Therefore, when one or more latency-sensitive MSDUs arrive, the transmission of one or more non-latency-sensitive MSDUs may have just begun. Depending on current WLAN behavior, ongoing PPDU transmissions need to be completed before a new PPDU transmission for a latency-sensitive MSDU can be initiated. Therefore, the transmission of latency-sensitive MSDUs may require an unacceptably long wait.

[0005] The “Background” description provided herein is intended to provide an overall overview of the context of this disclosure. To the extent described in this Background section, the work of the currently named inventors and aspects of that description that may not conform to the prior art at the time of submission are neither explicitly nor implicitly considered to be prior art of this disclosure. Summary of the Invention

[0006] One objective is to provide a communication device and method that processes information in an improved manner and with correct behavior, particularly determining parameters related to channel access and accessing the channel in the event of interruption of ongoing data transmission, so as to allow low-latency-sensitive service switching. Another objective is to provide a corresponding computer program for implementing the communication method and a non-transitory computer-readable recording medium for implementing the communication method.

[0007] According to one aspect, a first communication device is provided, the first communication device being configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to:

[0008] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0009] Terminate the ongoing transmission of the data unit before the estimated transmission time of the data unit, and

[0010] During the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity established between the first and second communication devices for the ongoing data unit exchange, receive and / or transmit preemptive data units from and / or to the third communication device.

[0011] According to one aspect, another first communication device is provided, configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to:

[0012] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0013] Before the current transmission opportunity ends, a termination notification indicating the end of the current transmission opportunity will be sent, and

[0014] Establish a new transmission opportunity with a third communication device, wherein the duration of the new transmission opportunity covers at least the transmission of preempted data to and / or the reception of preempted data from the third communication device.

[0015] According to another aspect, a third communication device is provided, the third communication device being configured to communicate with a first communication device, the third communication device including circuitry configured to;

[0016] Receive data units addressed to the second communication device.

[0017] Determine the duration indicator, which indicates the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for a data unit.

[0018] Determine whether the transmission of the data unit has terminated before the estimated transmission time of the data unit, and

[0019] During the remaining duration of the truncated data unit and / or during the remaining duration of the transmission opportunity, receive and / or transmit preemptive data units from and / or to the first communication device.

[0020] According to some other aspects corresponding to the first and second communication methods, a computer program is provided, comprising a program device for causing the computer to perform the steps of the methods disclosed herein when the computer program is executed on a computer. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the execution of the methods disclosed herein.

[0021] The implementation schemes are defined in the subsequent disclosures. It should be understood that the disclosed communication methods, computer programs, and computer-readable recording media have similar and / or identical further implementations to the claimed communication equipment and those defined and / or disclosed herein.

[0022] One aspect of this disclosure is the concept of preempting a PPDU, i.e., truncating a PPDU carrying non-latency-sensitive services to serve a STA with latency constraints. Another aspect involves enhancements to achieve the correct behavior at the STA that is the cause of the truncation, i.e., an STA that needs immediate updates or needs to be updated from it immediately.

[0023] In the context of this disclosure, the first communication device is also referred to as an "access point" or "AP", the second communication device is also referred to as an "initial station" or "sSTA", and the third communication device is also referred to as a "preemptive station" or "pSTA".

[0024] The preceding paragraphs have been provided in a general manner and are not intended to limit the scope of the embodiments described below. A better understanding of the described embodiments and further advantages will be achieved by referring to the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0025] A more complete understanding of the present disclosure and its many accompanying advantages will be readily obtained when considered in conjunction with the accompanying drawings and by referring to the following detailed description, in which:

[0026] Figure 1 A diagram illustrating the relationship and structure of data units in a traditional WLAN is provided.

[0027] Figure 2 The diagram illustrates non-delay and delay-sensitive data transmission without PPDU truncation.

[0028] Figure 3 A diagram illustrating non-delay and delay-sensitive data transmission with PPDU truncation is shown.

[0029] Figure 4 A diagram illustrating the interaction between the PHY and MAC layers transmitted in a WLAN is shown.

[0030] Figure 5 A diagram illustrating the block size in the PHY layer is shown.

[0031] Figure 6 The first scenario of the application of this disclosure is illustrated schematically.

[0032] Figure 7 A second scenario illustrating the application of this disclosure is shown schematically.

[0033] Figure 8 A third scenario illustrating the application of this disclosure is shown schematically.

[0034] Figure 9 A schematic diagram of a communication device according to this disclosure is shown.

[0035] Figure 10 A flowchart illustrating an embodiment of a communication method of a first communication device according to the present disclosure is shown.

[0036] Figure 11 A flowchart of another embodiment of the communication method of the first communication device according to this disclosure is shown.

[0037] Figure 12 A flowchart illustrating an embodiment of a communication method using a third communication device according to this disclosure is shown.

[0038] Figure 13 A diagram illustrating an implementation scheme regarding transmission limits is shown.

[0039] Figure 14 illustrates the behavior at the Ack time following the inclusion of sPPDU in the original TXOP, where TXTIME(pPPDU2) <TXTIME(Ack)( Figure 14A And TXTIME(pPPDU2)>TXTIME(Ack) Figure 14B ).

[0040] Figure 15 A diagram illustrating an implementation using TXOP truncation and reset is shown.

[0041] Figure 16 shows a diagram illustrating the traditional verification strategy setup and a new verification strategy setup proposed in an implementation scheme.

[0042] Figure 17 The diagram illustrates the session operation for a low-latency service session initiated by a non-AP station.

[0043] Figure 18 A more detailed flowchart of another embodiment of the communication method of the first communication device according to this disclosure is shown.

[0044] Figure 19 A diagram illustrating the relationship between interfaces under truncation conditions is shown. Detailed Implementation

[0045] Referring now to the accompanying drawings, in which the same reference numerals in several views denote the same or corresponding parts. Figure 1 The commonly known relationships and structures of data units in a WLAN are shown, particularly the relationships and structures of MSDU or A-MSDU (aggregated MSDU), MPDU, PSDU (physical layer service data unit), and PPDU.

[0046] According to this disclosure, PPDU transmission (i.e., transmission of data units) will be truncated (or interrupted) without losing the data already transmitted. Therefore, it can be considered a receiver-friendly truncation for ongoing PPDU transmissions.

[0047] Figure 2 and Figure 3 A diagram illustrating the benefits of PPDU truncation for low-latency communication is shown. According to... Figure 2 No PPDU truncation was used; according to Figure 3 PPDU truncation was used. It should be noted that both figures illustrate conventional WLAN behavior, and the MSDU arrival times are equal in both figures.

[0048] according to Figure 2 Before a delay-sensitive MSDU stored in PPDU 11 can be transmitted, PPDU 10, which stores non-delay-sensitive MSDUs, needs to be completed. This causes an undesirable queuing delay for delay-sensitive MSDUs, as they need to be buffered in a queue or memory until they can be transmitted. However, according to Figure 3 The PPDU 20, which stores non-delay-sensitive data, is truncated into two PPDU parts, 21 and 22, allowing for the rapid transmission of the PPDU 23, which stores delay-sensitive data. Therefore, with... Figure 2 In comparison, latency-sensitive MSDUs have lower queuing latency. Figure 2 compared to, Figure 3 Queuing delays for non-latency-sensitive data increase. PPDU truncation can provide a trade-off for queuing delays across different service types, but it does not reduce them. It should be noted that non-latency-sensitive and latency-sensitive MSDUs can target different STAs.

[0049] In one implementation, signal processing can be performed in blocks within the WLAN PHY and MAC layers. Several processing steps have different block lengths. For the intended PPDU truncation operation, possible block lengths to consider are LDPC codeword length, OFDM symbol length, and MPDU data unit.

[0050] An MPDU (Multi-Level Unit) data unit includes (i) header information, (ii) (encrypted) user data, typically an MSDU (Multi-Level Unit), and (iii) a Frame Check Sequence (FCS). The FCS is used to detect transmission errors within the user data and / or header information. Upon detection of an error, the MPDU is discarded, and a retransmission can be requested from the transmitter of that MPDU. One or more MPDUs can be aggregated into an A-MPDU for transmission within a single PPDU (Multi-Level Unit). Figure 1 Once the PSDU (i.e., MPDU or A-MPDU) is available in the MAC layer, meaning the minimum amount of data to be transmitted is known, the PHY layer is triggered for transmission.

[0051] Figure 4 This illustrates the interaction between the PHY and MAC for transmission, specifically the initiation of PPDU transmissions and data transfer between the MAC and PHY. The MAC triggers the PHY to begin transmission via the PHY-TXSTART.request(TXVECTOR) function (or primitive). This request includes TXVECTOR, which stores one or more configuration parameters of the PHY, such as the length information of the PHY Input Data Unit (PSDU), the modulation and coding scheme (MCS), i.e., the code rate and constellation size, the number of spatial streams, the MIMO mode, the bandwidth, and the RU size, etc.

[0052] Based on this information, the PHY determines the block sizes and corresponding structures for LDPC and OFDM modulation. This process involves multiple steps, which are omitted here as they are not part of the disclosed solution. Different block sizes are determined such that all block boundaries coincide, at least at the end of the PSDU (preferably also at the beginning). These block sizes and associated block structures remain fixed throughout the encoding and modulation of the corresponding PPDU. Figure 5 The block-by-block operations and block boundaries at the start and end of the PSDU were visualized.

[0053] exist Figure 4In the PHY-TXSTART.request and block size calculation, the PHY begins transmitting the channel estimation sequence (STF, LTF), training symbols, and signaling information (SIG). The receiver uses the signaling information to configure its PHY to receive the PPDU. Once the SIG field data is compiled, the PHY reports its readiness for data exchange to the MAC by issuing the PHY-TXSTART.confirm(TXSTATUS) primitive. Subsequently, the MAC sends data to the PHY using the PHY-DATA.request(DATA, USER_INDEX) primitive. Therefore, DATA holds the actual data to be transmitted for the user identified by USER_INDEX. Typically, the data size is one octet. The PHY confirms successful data transmission by issuing the PHY-DATA.confirm primitive. Data exchange continues until the MAC issues a PHY-TXEND.request, instructing the PHY to terminate transmission. Afterward, once transmission over the radio medium is no longer possible, the PHY notifies the MAC that the transmission was terminated by PHY-TXEND.confirm.

[0054] In the context of Real-Time Applications (RTA), an Access Point (AP) needs to serve STAs within its Basic Service Set (BSS), which have strict constraints regarding latency and jitter. On the other hand, PPDUs currently defined in WLANs can have relatively long transmission times, for example, up to 5ms. Therefore, the concept of PPDU preemption has emerged, whereby PPDUs carrying non-latency-sensitive services are truncated to serve STAs with latency constraints. PPDU transmission truncation can be performed by the MAC at any time via the PHY-TXEND.request primitive. However, truncation in this way results in an incomplete last OFDM symbol, partially corrupting the PPDU, preventing the receiver from demodulating it, and leading to data loss. Furthermore, the receiver is unaware of what caused the PPDU truncation; for example, it could be due to carrier loss, interference, or intentional truncation. To enable the receiver to correctly decode the PPDU content up to the point of truncation, specific padding techniques need to be designed in the event of premature PPDU termination.

[0055] This disclosure proposes further enhancements to enable the correct and fair distribution of channel access parameters and new rules for channel access for STAs, which are designed to be truncated. Furthermore, aspects related to channel access are discussed to ensure that the network allocation vector (NAV) is correctly set not only for the STAs directly involved, but also for the remaining STAs listening to the medium in order to find access opportunities.

[0056] exist Figures 6 to 8 The following describes the scenarios considered below.

[0057] exist Figure 6 The diagram schematically illustrates a first case of DL transmission to a preemptive STA (pSTA) using downlink (DL) PPDU truncation. In this case, the AP (also referred to herein as the first communication device) sends a PPDU (also referred to herein as the second communication device or the starting STA, sSTA) to the initial STA (also referred to herein as the second communication device or the starting STA, sSTA). At some point during the sPPDU transmission, the AP's upper layer indicates a need to send high-priority data to a different STA (also referred to herein as the third communication device or pSTA). As a result, after a processing delay (pDelay), the sPPDU is truncated, transmission to the sSTA stops, and after a given time interval of inter-frame space (IFS), the AP sends a new PPDU (also referred to herein as the preemptive data unit or pPPDU) to the pSTA. Figure 6 The diagram shows the duration D, which indicates the initially expected transmission time from the sPPDU to the sSTA 300. Therefore, D is the duration of the sPPDU without truncation. The initially expected duration D of the sPPDU can be estimated by the STAs (i.e., sSTA 300 and pSTA 100) capable of decoding the sPPDU's preamble, for example, based on information present in the preamble field.

[0058] exist Figure 7 The diagram schematically illustrates a second case of using a DL PPDU to truncate uplink (UL) transmissions from a pSTA. This case is an extension of the first case, where the main difference is that not only does the DL transmission from the AP occur after truncation, but the response from the pSTA also occurs after truncation. This case is described in a general sense and includes, for example, the following special cases:

[0059] i) The first pPPDU (pPPDU1) sent by the AP contains high-priority data toward the pSTA, with a normal / implicit Ack policy and / or aggregated with a BAck request frame, while pPPDU2 contains an acknowledgment or block acknowledgment.

[0060] ii) The AP requires an urgent update from the pSTA and interrupts transmission to the sSTA to obtain the update. To achieve proper channel access in this situation, according to one implementation, it is recommended to first send a frame from the AP requesting data transmission from the pSTA and setting the channel access parameters for subsequent communication. This will be done in the inter-frame space following a PPDU from the pSTA containing the required update. pPPDU1 can be a trigger frame (TF), as defined, for example, in IEEE 802.11ax, triggering the transmission of pPPDU2, or a simplified version thereof, but with similar functionality (e.g., including a start indication, requiring basic RU-BW allocation).

[0061] iii) The AP has received an indication from a different link from the pSTA that there is urgent data to transmit. Subsequently, the AP allows transmission after preempting the sPPDU; however, to ensure the correct channel access parameters, according to one implementation, it is recommended to first transmit a frame to trigger the transmission from the pSTA and inform it of the channel access parameters used for transmission. Therefore, examples of the contents of pPPDU1 and pPPDU2 are the trigger frame and the data PPDU, respectively.

[0062] When the STA has multi-link capability and the preemption request is executed on a different link than the link where the transmission will occur, a trigger frame as presented in case iii) is proposed as a simple implementation for transmission, which can ensure correct channel access and consistent duration information on the link. However, it also introduces latency, so operation without it may be necessary when latency requirements are strict. Therefore, as Figure 8 The schematic depiction suggests a third scenario where direct UL access is used for the pPPDU after the sPPDU is truncated.

[0063] One requirement in this case is that the pSTA listens to the link, where truncation is performed at least from the start of the sPPDU, ensuring that the preamble information has been decoded. Mechanisms for requesting preemption on links other than those performing DL transmission and truncation are beyond the scope of this disclosure. However, for completeness, Figure 8 The same applies to examples of multi-link relationships. The focus here is solely on channel access after a truncation occurs and ensuring consistency of transmission opportunities (TXOPs) on a particular link, where TXOPs represent the expected duration of data exchange in the absence of a truncation.

[0064] To ensure Figures 6 to 8 The correct behavior in the scenario shown should ensure the Ack behavior of pSTA channel access, AP channel access, and sSTA.

[0065] pSTA channel access refers to the mechanism that enables a pSTA to access a channel in order to transmit preempted data units or responses to preempted data units (e.g., acknowledgments). In a WLAN environment, a common mechanism is based on the Network Allocation Vector (NAV), which stores information about medium occupancy and is periodically updated based on the duration of frames received from expected or unexpected transmitters. When a STA receives a frame, it determines the duration for which the medium is occupied and prohibits access to the channel or contention for channel access during this time interval. In the event of preemption, this behavior can be restrictive. This is because once transmission to the sSTA has begun, the preempting STA will see the medium as busy and will not be allowed to transmit during data exchange between the AP and the sSTA. Therefore, according to the current rules, the sSTA cannot transmit preempted data or responses to preempted data until the originally expected transmission opportunity ends.

[0066] Furthermore, according to the dual NAV mechanism defined in IEEE 802.11ax, if the pSTA is the receiver of the trigger frame requesting its transmission, it may reset its intra-frame BSS NAV (i.e., the STA's NAV within its own BSS). However, in the current revision of this standard, resetting the intra-frame BSS NAV is only possible after the PPDU carrying the indication has ended and only as a response to the trigger frame. Before the PPDU ends, only the inter-frame BSS (or basic NAV) can be updated. Therefore, based on the current rules, after the PPDU is truncated, the pSTA cannot initiate any transmissions to the AP, especially... Figure 7 and Figure 8 As shown in the example.

[0067] In the context of this recommendation, AP channel access involves several aspects. First, it refers to sharing or truncating transmission opportunities obtained by a single STA when the AP needs to perform preemptive transmissions to a pSTA. Second, it refers to distributing the correct duration information so that STAs have similar NAV information, regardless of whether these STAs are listening for truncated transmissions. Finally, it refers to the mechanisms implemented by the AP to facilitate pSTA channel access. Regarding the first point, it involves obtaining transmission opportunities for services of a specific Access Class (AC) that are the primary access class. Current standards impose significant limitations on TXOP sharing. Regarding the second point, according to existing rules, transmission of pPPDUs must consider transmission opportunity limitations to avoid access problems, i.e., conflicts for STAs that have already updated their network allocation vectors. However, there are also limitations.

[0068] TXOP sharing is permitted only under restrictive conditions, one of the main conditions being that it does not exceed the duration of the primary AC. In some environments, such as SU, the primary AC's transfers must be completed before the remaining TXOP transfers can be shared with another AC, and the specific AC must have a higher priority.

[0069] Based on the duration information in the MAC header, the NAV information is updated in all frames whenever such information can be retrieved. Furthermore, the duration PHY indication is also available within the preamble used by HE STAs, which can be used when the MAC indication cannot be retrieved. Based on information about the duration of the next transmission opportunity and the length of the PPDU containing that information, the STA determines medium utilization and the next possible transmission time from its side. Therefore, the PPDU limit and transmission opportunity limit are important for the STA to correctly decide on channel access. Therefore, PPDU truncation should be implemented to allow preemption schemes to be transmitted to different STAs, such that these two boundaries coincide with the boundaries of the initial PPDU and TXOP duration.

[0070] The sSTA's Ack behavior refers to the mechanism by which the sSTA sends an acknowledgment to the AP, notifying whether all MPDUs sent by the AP have been correctly received, and if not, which MPDUs were lost. There are several mechanisms for requesting or sending an Ack. In the specific case currently recommended, this should be carefully considered to avoid conflicts between PPDUs carrying Ack frames from the sSTA and preemptive data transmission. The solution to avoid this problem according to the implementation scheme will be explained below with reference to Figure 16.

[0071] Figure 9 The diagram illustrates a first communication device 100 (e.g., an access point AP) according to one aspect of this disclosure, used for communicating over a wireless channel with a second communication device 200 (also referred to herein as an originating station sSTA) and a third communication device 300 (also referred herein as a preemptive station pSTA). Therefore, the first communication device 100 is capable of exchanging (receiving and / or transmitting) data with the second communication device 200 and the third communication device 300.

[0072] Each of communication devices 100, 200, and 300 includes circuits 101, 201, and 301 configured to perform specific operations. These circuits can be implemented by a corresponding processor or computer, i.e., as hardware and / or software, or by dedicated units or components. For example, separately programmed processors can represent corresponding circuits 101, 201, and 301.

[0073] Figure 10A flowchart illustrating an embodiment of a first communication method 110 of a first communication device 100 (AP) according to this disclosure is shown, which can be executed by circuit 101. In a first step 111, the AP receives a truncation notification during an ongoing data unit exchange with a second communication device. The truncation notification indicates that if truncation conditions are met, the ongoing transmission of the data unit should be truncated, and a preemptive data unit should be received from and / or transmitted to the third communication device. The truncation notification may indicate that during the ongoing transmission opportunity, there is a high-priority, low-latency service / a service with a higher priority than that included in the ongoing transmission. Once the truncation notification is received, it should first be determined whether truncation is possible (i.e., if the duration is fitted, the STA is eligible to handle the truncated transmission) before deciding to truncate the PPDU.

[0074] In the second step 112, the AP terminates the ongoing transmission of the data unit before the estimated transmission time of the data unit. In one implementation, the AP evaluates whether it is meaningful (i.e., useful) to perform the truncation based on the remaining duration of the TXOP and the ongoing PPDU transmission.

[0075] In the third step 113, the AP receives and / or transmits preemption data units from and / or to the third communication device (i.e., pSTA) during the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity. In one embodiment, if the truncation condition is met, the AP generates another truncation primitive that can be published by the MAC to the PHY, instructing the PHY to truncate the ongoing PPDU.

[0076] Another implementation handles the establishment of Low Latency Sensitive Service Flow (LLTS) sessions to notify users of LLTS characteristics and preemption parameters. In one implementation of this scheme, a non-AP STA with LLTS can establish a LLTS session with its associated AP. Figure 17 A diagram illustrating the operation of this type of session is shown.

[0077] When such a session is established, the non-AP STA (with a Station Management Entity (SME) and MAC) notifies its counterpart of the service characteristics (e.g., periodicity, duration) and requirements (e.g., in terms of data rate and latency limits). Additionally, the AP (with both SME and MAC) can be notified that it is preemptible. In this case, it can also indicate which preemption-related parameters it can support (e.g., whether it can continuously or only periodically listen for CCA during PPDU reception, and how often CCA can be performed during the PPDU period). Including these parameters in the delayed service session request is just one possible implementation. An alternative is to indicate preemption capabilities and parameters within the fields of the capability elements exchanged between the associated STA and AP.

[0078] The AP responds to delayed service session requests by accepting / rejecting or suggesting alternative parameters. Specifically regarding preemption, the AP can indicate whether it can truncate an ongoing PPDU toward a STA other than the LLTS requester in order to meet delay-related service requirements. Furthermore, where truncation is possible, the parameters for truncation are indicated, such as the possible truncation granularity (i.e., how many OFDM symbols after which truncation can be performed), or a set of possible values ​​indicating the exact values ​​to be used in the preamble of the potentially truncate PPDU. A schedule may be present in the response to the requesting STA, which transmits specific intervals for delay-sensitive service flows and / or when the AP can request updates. Additionally, it can be indicated whether potential truncation is possible within or outside of these specified time intervals. Specifying time intervals and ensuring that truncation is performed only within those specified time intervals helps improve the power-saving behavior of the pSTA. Otherwise, the requesting pSTA should commit to continuously listening for PPDUs belonging to other STAs, continuously evaluating whether intentional truncation has been performed, and further verifying that the identifiers of subsequent transmissions correspond to themselves.

[0079] Specific schedules and periods can be defined in Low Latency Sensitive Service Flow (LLSTS or LLTS) settings. Alternatively, these can be further announced by the AP in the establishment and / or announcement of scheduling intervals for specific STAs, such as individual or broadcast target wake-up times. To allow pSTAs to determine these intervals, the AP specifies an allocation ID, an LLTS identifier, and identifiers for both the pSTA and the AP that are mapped to that allocation ID. In the case of broadcast wake-up intervals, the AP can indicate within control frames carrying setup or update configuration information that transmissions during these intervals may be truncated.

[0080] If a low-latency sensitive service has been established between the AP and pSTA, the service flow identifier for that service, as well as the identifiers of the AP and pSTA, will be included in the truncated PPDU.

[0081] Similarly, in another implementation, an AP informed from its upper layer of the presence of low-latency-sensitive traffic toward a non-AP STA can establish a low-latency-sensitive session with the corresponding STA. In this case, the AP can include an indication in the LLSTSReservation whether preemption is supported and which parameters (e.g., granularity) are supported. The pSTA then confirms whether it accepts these parameters, for example, whether it can periodically listen at a given OFDM granularity. Low-latency-sensitive traffic information and low-latency-sensitive traffic can be established by reusing the TS establishment mechanism defined in the IEEE 802.11 standard with some modifications.

[0082] Another implementation involves truncation only during specific time intervals, where the pSTA is known to be awake and capable of handling subsequent transmissions. In this implementation, traffic flow parameters such as periodicity or delay requirements can be exchanged between the pSTA and the AP, for example, by a regular TS. However, preemption parameters are exchanged and activated within a specifically defined service period—that is, within a time interval during which more targeted data exchange is performed between the AP and a particular pSTA. An example of such a time interval is the TWT SP (Target Wake-Up Time Service Period).

[0083] The pSTA and AP establish an interval in which potential transmissions corresponding to low-latency service characteristics can be performed. During the establishment phase, the characteristics of data exchange between the AP and pSTA can be negotiated, for example, if a transmission from the pSTA should precede a trigger from the AP. Furthermore, preemption-related parameters (e.g., granularity) as described above can be selected based on latency service characteristics, the capabilities of the AP and pSTA, and other service requirements within the BSS. The selected parameters can be further negotiated between the AP and pSTA. During the established TWT SP, the pSTA also commits to being in a wake-up state, thus being able to hear PPDUs exchanged via media on a set of negotiated links. If the pSTA observes premature termination of a PPDU during the time interval established in this manner, the pSTA is allowed to immediately set the PHY-CCA to idle after determining the truncation and subsequently follow further rules defined within the corresponding time interval (i.e., wait for a subsequent PPDU from the AP containing a preemption data unit, or a frame triggering a transmission from the pSTA, or start transmission directly).

[0084] Figure 18 A more detailed flowchart of a first communication method 130 of a first communication device 100 (AP) according to the present disclosure is shown, which can be executed by circuit 101. The flowchart specifically illustrates further details regarding determining whether to perform a truncation.

[0085] In step 131, the LLTS indication can originate from the upper MAC layer of the AP (e.g., SME (System Management Entity)). When establishing a low-latency session, a service characteristic is that it takes precedence over other service classes, and ongoing transmissions may be truncated to meet the latency constraints of that service class. Notification of low-latency services with truncation capability may have already been sent from the pSTA via a different link (e.g., such as...). Figure 8 (As shown in the request frame sent by pSTA).

[0086] In step 132, it is verified whether the pSTA targeted by the LLTS service is eligible to receive preemption submissions, for example, whether it has been instructed to perform preemption and / or has participated in establishing a low-latency service flow session, wherein it is confirmed that it can handle preemption services and the session is active. If these conditions are not met, transmission to the sSTA continues; otherwise, step 133 is executed.

[0087] In step 133, it is verified whether the pSTA is in a wake-up state. This verification is optional. In the event of a loss, processing will proceed directly to either step 134 or step 135 to determine whether to perform a truncation. In this case, the choice of one or the other step can be predefined, for example, in a standard. For this case, step 135 is preferred because, based on the trigger frame, it is easy to determine whether the pSTA is awake and subsequent preemption data can be transmitted. Information about whether the STA is awake within a specific interval can be established by a target wake-up time interval or by an indication from the STA within a previously exchanged frame in which the STA committed to wake-up. In one implementation, a time interval can be defined as either part of a low-latency traffic flow session or in a subsequent scheduled session, within which transmission may occur and the pSTA commits to wake-up. This is another mechanism by which the AP can know the wake-up status of the STA.

[0088] Steps 134 and 135 are performing operations that determine whether the remaining duration of the TXOP is sufficient to allow preemptive transmission or to allow triggering a preemptive transmission from the STA. Furthermore, these steps determine whether a frame with immediate acknowledgment should be sent (if the acknowledgment transmission still fits within the TXOP duration) or a frame with delayed acknowledgment (which will occur in the next TXOP). If the remaining duration is sufficient to transmit at least one preemptive data unit or a preemptive data unit schedule or CF END frame, a truncation indication primitive is issued to the PHY (steps 136 and 137), stating that the sPPDU will be truncated. Otherwise, the STA continues transmission to the sSTA (step 138). Therefore, steps 132 through 135 essentially determine what is expressed above by whether truncation is meaningful. The truncation indication here refers to issuing a truncation primitive to the MAC and / or PHY to perform truncation.

[0089] In steps 139 and 140, the sPPDU is truncated. Then, in step 141, as shown in step 131, the pPPDU is transmitted using LLTS. In step 142, after the IFS, a transmission indication triggers the transmission of a preemptive data unit containing a service corresponding to the LLTS and / or pPPDU, where the LLTS ID corresponds to a step 131.

[0090] Figure 19 A diagram illustrating the relationship between interfaces under truncation conditions is shown, specifically the AP MAC interface and the APSME interface. Low-latency services with truncation notification originate from the SME and are handled by... Figure 19 The primitive marked as `TruncationNotification.request` is passed to the MAC. The MAC determines, for example, based on steps 132 through 135, whether truncation can be performed. Based on this determination, it accepts the truncation and provides further instructions to the PHY to perform the truncation, or rejects the truncation request and continues the ongoing transmission to the sSTA. The result of the determination is... Figure 19 The primitive marked as TruncationNotification.confirm is transmitted from MAC to SME.

[0091] Figure 11 A flowchart of another embodiment of a first communication method 120 according to a first communication device 100 (AP) of the present disclosure is shown, which can be executed by circuit 101. In the first step 121, the AP receives a truncation notification, for example, an indication of an LLTS with a truncation notification, during an ongoing data unit exchange with a second communication device. In the second step 122, while performing... Figure 18Following similar verification of the truncation condition, i.e., if the receiver of the LLTS with the truncation notification is eligible to receive the preempted transmission, and the remaining duration of the transmission opportunity is sufficient to send at least an end notification frame, then the AP transmits an end notification indicating the end of the current transmission opportunity before the current transmission opportunity ends. In the third step 123, the AP establishes a new transmission opportunity with the third communication device. Therefore, the duration of the new transmission opportunity at least covers the transmission of preempted data to and / or the reception of preempted data from the third communication device. If a new transmission opportunity is obtained before the initially expected end of the sPPDU, in one embodiment, in the case of pSTA, it is recommended that the content of the newly obtained TXOP be limited to containing only the traffic corresponding to the LLTS that needs to be truncated. Alternatively, depending on the requirements of the traffic truncated for sSTA, the new TXOP can be defined as limited to the LLTS of pSTA and the remaining traffic of sSTA from the initially expected TXOP.

[0092] Figure 12 A flowchart illustrating an embodiment of a third communication method 310 of a third communication device 300 (pSTA) according to the present disclosure, which can be executed by circuit 301. In a first step 311, the pSTA receives a data unit addressed to a second communication device 200 (sSTA). In a second step 312, the pSTA determines a duration indication indicating the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for the data unit. As part of this step, the pSTA can check the duration of an ongoing PPDU based on length information in the preamble of a received packet, which can be further used to determine whether an early termination of the PPDU has occurred. Furthermore, as part of this step, a duration indication of a transmission opportunity is determined based on the MAC header or an indication in the PHY preamble, within which data exchange occurs. This information is further used when the pSTA needs to transmit a preempted data unit or a response to a preempted data unit and therefore must select transmission parameters to take into account TXOP boundaries. In a third step 313, the pSTA determines whether the transmission of the data unit has terminated before the estimated transmission time of the data unit. Then, in the fourth step 314, pSTA receives and / or transmits preemptive data units to the first communication device during the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity.

[0093] Typically, the length of a PHY data unit is information indicated in the PHY preamble of a PPDU, enabling the receiver to calculate the length of the PPDU and implicitly, how long the medium is busy with ongoing PPDU transmissions. Furthermore, the duration of a transmission opportunity can imply an exchange of more than an ongoing PPDU and can be indicated in the PHY and / or MAC headers. In the context of this disclosure, the length of a truncated data unit refers to the length of a data unit effectively transmitted from the first communication device to the second communication device. Furthermore, the expected length of a truncated data unit refers to the expected length of the data unit to the second communication device, i.e., without considering truncation, and corresponds to the information within the preamble of the PPDU sent from the first communication device to the second communication device. The duration of a data unit refers to the processing time of a data unit of a given length; the dependency between the two is given in the standard, therefore the terms length and duration are used interchangeably when referring to data units. Furthermore, the expected duration of a TXOP refers to the expected duration of a transmission opportunity obtained for communication between the first and second communication devices before considering any truncation.

[0094] According to one aspect, this disclosure proposes a solution regarding TXOP boundary and duration information. Currently, the duration information is set based on the duration of pending PPDUs to be exchanged within the acquired TXOP, i.e., the PPDU following the PPDU carrying the duration information. However, in the case of truncation, an additional parameter should be considered: the expected length of the original packet intended for the sSTA, assuming no truncation (hereinafter denoted as oTXTIME) and / or the remaining time after truncation (hereinafter denoted as rTXTIME). This may be necessary for STAs that might miss the original PPDU or TXOP information to prevent them from setting incorrect NAVs. Furthermore, a new duration setting and pPPDU length should be chosen to avoid unfairness or confusion, as many STAs may be in a waiting period until the expected end of the PPDU. Similarly, for TXOPs exchanged across multiple frames, the duration should point to the same end of the shared TXOP, but the estimated processing time of truncated PPDUs should be taken into account.

[0095] In one implementation, the truncated PPDU is considered to be the last one in its TXOP. Figure 13 A diagram illustrating this implementation scheme is shown. Specifically, for Figure 6 and Figure 7In the first and second scenarios shown, when pPPDU or pPPDU1 is a DL PPDU from the TXOP holder, duration information is readily available. Once a preemption instruction is received, the AP determines the earliest potential PPDU cutoff time. Based on this, rTXTIME, the remaining duration of the PPDU, is calculated, and the estimated duration of the PPDU intended for use in pSTA is determined. If...

[0096] TXTIME(pPPDU)+IFS1 <rTXTIME,(1)

[0097] Then a pPPDU can be sent to pSTA. In (1), TXTIME(pPPDU) represents the duration of the pPPDU transmission, and IFS1 is the inter-frame spatial duration, which can be selected as SIFS or even shorter, such as RIFS, because in this case, there is no need to switch between receive and transmit modes. The duration indication in the MAC header of the MPDU contained in the pPPDU is equal to d in this case. p =rTXTIME-TXTIME(pPPDU)-IFS1.

[0098] An additional optional measure to ensure all STAs understand the TXOP boundary is to fill the pPPDU to the original time of the PPDU, in which case d p =0. In this case, the STA that cannot decode the MAC header is prevented from starting the backoff process when the pPPDU is prematurely terminated, instead of waiting for the correct TXOP boundary.

[0099] Similarly, in another implementation scheme, particularly for Figure 7 In the second scenario shown, if the pPPDU contains a frame requiring acknowledgment, the AP determines whether an immediate Ack can be sent within the same time interval. Therefore, if

[0100] TXTIME(pPPDU1)+IFS1+SIFS+TXTIME(pPPDU2) <rTXTIME,(2)

[0101] Wherein, pPPDU2 is the PPDU carrying the Ack frame. The Ack policy of the MPDU in pPPDU1 can be set to normal Ack, and pSTA will reply within SIFS from the time pPPDU1 is received. In (2), TXTIME(pPPDU1) and TXTIME(pPPDU2) represent the transmission duration of pPPDU1 and PPDU2, respectively. IFS1 is the inter-frame spatial duration, which, similar to the above, can be set to SIFS or RIFS, where SIFS is short inter-frame spatial time. Otherwise, the AP sets the Ack policy toward delayed Ack, and pSTA will send an acknowledgment within a future transmission opportunity after an appropriate request. Equation (2) is also used when pPPDU1 intends to carry the trigger frame. In this case, the AP determines whether there is enough time in the remaining rTXTIME for it to send the trigger frame itself and for pSTA to send the response frame. Similar to the previous implementation, padding pPPDU2 ensures additional protection in the case of termination earlier than the TXOP boundary.

[0102] It should be noted that rTXTIME can be calculated until the end of the PPDU, or rTXTIME can be calculated to allow for a small margin after the PPDU. This variation can be limited by a certain threshold, and the variation can be selected, for example, similar to the TXOP limit extension, or simply overriding the nominal value of the wake-up time of the RX PHY.

[0103] It should also be noted that if pPPDU1 contains a CF-END frame, pSTA may need to contend for the transmission of pPPDU2. If pSTA can account for the end of oTXTIME (optionally with a margin), then pPPDU2 can be transmitted.

[0104] To enable a pSTA to transmit a preemptive data unit or a response to a preemptive data unit within a transmission opportunity corresponding to data exchange between an AP and an sSTA, the following solutions are conceivable. One optional solution is to send a trigger-like frame in the first PPDU after truncation, identify the pSTA and request it to reset its NAV, and transmit the preemptive data unit. Intra-BSS NAV rules may also be adapted to allow a directly addressed pSTA after an sPPDU with a preemption indication to ignore the intra-BSS NAV. In addition, if there is any indication corresponding to its own low-latency traffic, for example, if PPDU transmission is performed during a time interval previously indicated as a possible truncation of transmission, if the time interval corresponds to a schedule already negotiated between the AP and the pSTA, if an indication of a traffic identifier corresponding to LLTS setup between the AP and the pSTA is present in the pPPDU, if an assignment identifier corresponding to LLTS is present in the sPPDU or a control frame, a pSTA involved in an active low-latency sensitive traffic flow session may be allowed to reset the NAV upon determining that the PPDU is intentionally terminated early. In both cases, the STA may still need to follow the inter-BSS rules.

[0105] In another embodiment, the truncated PPDU is not considered to be the last one within its TXOP, for example, the TXOP includes the response time for the Ack from the sSTA. When the truncated PPDU is not the last one of the TXOP, but was originally supposed to be followed by, for example, an Ack / Block Ack, possible operations are depicted in the diagram shown in Figure 14. If the expected duration of pPPDU1 satisfies equation (1) but does not satisfy equation (2), the pPPDU is padded up to rTXTIME minus some margin, and pPPDU2 containing the Ack is transmitted within the terminated SIFS. The margin may be selected such that the end of pPPDU2 is within the TXOP limit, and after the SIFS at which the pPPDU terminates, the start of pPPDU2 can be decoded by other STAs to obtain correct information about the PPDU length.

[0106] Depending on the relationship between the length of pPPDU2 and the remaining duration of the TXOP, two examples are illustrated in Figure 14. Figure 14A A diagram illustrating the behavior in the case where the original TXOP includes the Ack time after the sPPDU and the transmission time of pPPDU2 is less than the transmission time of the originally expected Ack, that is, TXTIME(pPPDU2) < TXTIME(Ack), is shown. In Figure 14AIn the illustrated implementation, pPPDU1 is padded to align the transmission of pPPDU1 with the original expected end of sPPDU. This padding is to ensure that all STAs, including legacy STAs and those already in intra-frame PPDU power-saving mode, have the same reference to the end of the media occupancy of the PPDU from the AP, thus avoiding conflicts. Figure 14B A diagram illustrating the behavior when the Ack time follows the original TXOP containing the sPPDU and the transmission time of pPPDU2 is greater than the original expected transmission time TXTIME(pPPDU2) > TXTIME(Ack). In this case, the transmission of pPPDU2 can be allowed to begin before the initial expected end of the sPPDU, with the risk of collision. It should be noted that defining the TXOP as containing only the sPPDU, an ACK, and an applicable SIFS is merely an example. The descriptions and techniques described herein generally apply to situations where the transmission opportunity is longer than the duration of the sPPDU. More precisely, when the duration of pPPDU2 and the applicable SIFS is less than the difference between the transmission opportunity boundary and the expected duration of the sPPDU without truncation, or equivalently, when the difference between the duration indication within the sPPDU and the SIFS is longer than the duration of the pPPDU, it is recommended to perform padding of pPPDU1 to align it with the original expected end of the sPPDU.

[0107] If equation (2) can be considered and an Ack is sent within oTXTIME, then the AP can send a CF_end frame to terminate the TXOP.

[0108] To enable the pSTA to access the channel and transmit pPPDU2 in the TXOP of the sSTA, this paper proposes in one embodiment that the control frame used to obtain the TXOP includes user information of the pSTA, such as an allocation identifier, and may have preemptible information, including an indication of an empty resource allocation field or a preemption flag, and a service identifier of the low-latency traffic flow identifier known at the pSTA from the low-latency session establishment. An example implementation of such a control frame is an RTS trigger modified as described above to include a field of user information about the pSTA. This frame is referred to as an enhanced RTS, such as... Figure 14A and Figure 14B As shown. The pSTA can respond to the eRTS, which provides the AP with additional information about the fact that the pSTA is awake and can receive preemptive transmissions, and can notify the STA in the corresponding channel that it can perform a preemptive transmission from the STA.

[0109] If TXTIME(pPPDU2) > TXTIME(Ack_sSTA), but pPPDU1 can complete before sPPDU, then only consider...

[0110] TXTIME(pPPDU1)+IFS1+TXTIME(pPPDU2) <rTXTIME+TXTIME(Ack_sSTA),

[0111] pPPDU2 transfers can begin SIFS after unpadded pPPDU1.

[0112] Since preempting a data unit truncates an ongoing transmission, rules should be considered to avoid unfairness or abuse on the wireless medium. To this end, as one implementation, this document proposes that preempted transmissions carried within pPPDU1 and / or pPPDU2 correspond only to the LLTS that needs to be truncated. Furthermore, a trigger frame requesting the transmission of a pPPDU from the pSTA can also be defined as an indication that the service carried in the pPPDU from the pSTA corresponds only to the service of the LLTS. In another implementation, it is proposed to restrict pSTA service but allow at least a portion of the remaining service of the sSTA to be transmitted within the TXOP, for example, allowing simultaneous transmission of pPPDU2 and data units from the sSTA in TB PPDU mode. If there is remaining time within the TXOP after the data exchange corresponding to the preempted data unit has terminated, data exchange between the sSTA and the AP should resume.

[0113] In another implementation scheme, it is necessary to base on Figure 8 In the third scenario shown, sending an updated pSTA to the AP should first decode the sPPDU preamble and, if possible, the MAC header of the MPDU included therein to determine the initial expected duration of the just-truncated PPDU and TXOP. Based on this information, it is determined that an early termination of the sPPDU has occurred, and thus the remaining duration of the transmission opportunity is determined. Based on this, it is estimated whether the pPPDU can be transmitted without exceeding oTXTIME. Essentially, equation (1) with the corresponding IFS1 is also followed. In this case, IFS1 is likely to be at least as long as SIFS (not smaller).

[0114] When transmitting pPPDU, the duration indicator can be set as follows:

[0115] Duration indication (pPPDU) = d + oTXTIME - IFS

[0116] 1-RXTlME(pPPDU)-RXTlME(sPPDU)

[0117] Where d is the duration indicator, determined by the MAC header of the sPPDU; it is 0 if the sPPDU is the last in the TXOP, otherwise strictly positive. oTXTIME is determined based on the information in the length field of the PHY preamble of the sPPDU. RXTIME(sPPDU) here represents the duration of the effective transmission from the expected sPPDU to the AP at the sSTA, and from the pSTA's perspective, it represents the time elapsed from the moment the sPPDU packet is detected to the moment premature termination is detected. RXTIME(pPPDU) represents the estimated duration of the pPPDU sent by the pSTA to the AP. The pSTA can select the transmission parameters of the pPPDU to satisfy the equation above.

[0118] The duration of a pPPDU should preferably be chosen to not exceed the expected end of an sPPDU, even when transmission opportunity boundaries are still considered, i.e., the original TXOP duration is greater than the sum of oTXTIME, a SIFS, and additional time. This is because conventional STAs will not be able to decode the correct duration information and can only block access to the channel based on the conventional length information in the preamble. Therefore, they block access to the channel during oTXTIME, then listen to the channel, and if idle, they can compete or transmit if the backoff counter is 0. When a pPPDU transmission is completed with parameters different from those of the transmitted sPPDU—for example, different spatial directions from the AP, different power, or when the transmission is completed from the pSTA side—the conventional STA may incorrectly detect the channel as idle and, if their backoff counter is 0, begin competing or even transmitting. This transmission will conflict with the pPPDU transmission and is therefore detrimental to both parties involved. To avoid this problem, it is recommended that pPPDU transmissions not exceed the expected boundaries of the sPPDU. Alternatively, if they do exceed these boundaries, the time interval should be less than the expected boundary, which may lead to conflicts. The time interval can be a SIFS or a function of SIFS and a time slot, where the time slot corresponds to the shortest duration after the estimated end of the sPPDU, at which point a transmission from another STA with a standard SIFS tolerance can access the channel.

[0119] Intra-frame BSS NAV can be applied to pSTAs that are allowed to send pPPDUs in a third scenario. After sending a PPDU with a preemptible flag, if the pSTA has at least correctly decoded the PHY preamble and has correct information about the duration of the TXOP on the link, the pSTA is allowed to ignore the intra-frame BSS NAV; however, if direct addressing is used, the inter-frame BSS rules may still need to be followed. Furthermore, if there are any indications corresponding to its own low-latency traffic—for example, if a PPDU transmission is performed during a time interval previously indicated as potentially truncated, if these intervals correspond to a schedule negotiated between the AP and pSTA, if an indication of a traffic identifier corresponding to an LLTS setting between the AP and pSTA exists within the pPPDU, if an allocation identifier corresponding to an LLTS exists within the sPPDU, or if negotiation has already been performed on a different link—the pSTA involved in an active low-latency sensitive traffic flow session can reset the NAV if it is determined that the PPDU is intentionally terminated prematurely.

[0120] The duration indicator is preferably transmitted within the header of pPPDU1. The duration indicator being transmitted is not exactly the same as the duration indicator based on a decision (it may be conceptually similar, but can take different forms, for example, determining whether the pPPDU fits within the full pPPDU duration of oTXTIME, while the indicator appearing within the transmitted frame is relative to the end of the pPPDU).

[0121] The following discusses channel access from AP and TXOP sharing, which can be used in other implementations. For a specific access class of service, the AP has acquired the TXOP, which is referred to as the TXOP's master AC. To enable sharing of the TXOP with services from pSTAs that have different ACs, the following solutions are envisioned in implementations.

[0122] Figure 15 A diagram illustrating an implementation using TXOP truncation and reset is shown. The AP terminates the current TXOP by sending CF_end within pPPDU1. The AP can then compete for the medium for the low-latency service AC of the pSTA and acquire a new TXOP when the medium is idle. If a new TXOP is acquired before oTXTIME, the first pPPDU1 is sent to the pSTA aligned with the oTXTIME boundary, and transmission continues within pPPDU2, indicating the new, correct TXOP duration information to the STA that was already in waiting mode during the expected transmission of the original PPDU. If a new TXOP is acquired after oTXTIME, PPDU splitting is not required. A new TXOP is acquired for the pSTA's AC, but may include additional sharing opportunities for truncated services of the sSTA.

[0123] Figure 16 illustrates another implementation scheme for providing confirmation of strategy changes. Figure 16A A diagram illustrating the setup of a traditional confirmation strategy is shown. Figure 16B A diagram illustrating the new confirmation strategy settings provided in this implementation is shown.

[0124] Typically, every MAC data unit holds an Ack policy field, which defines the acknowledgment behavior for that specific data unit. There are three related options for setting this field:

[0125] i) "Normal Ack or Implicit Block Ack": After receiving one or more data units, the receiver transmits an acknowledgment or block acknowledgment. This means that once the PPDU containing one or more data units with this Ack policy ends, the SIFS transmits an acknowledgment or block acknowledgment after the PPDU ends.

[0126] ii) "No Ack": The receiver does not take any action when it receives the data unit.

[0127] iii) "Block Ack": The receiver takes no action upon receiving a data unit except to internally record the reception status. The receiver can expect to respond with a block acknowledgment in a future block acknowledgment request frame, i.e., after the end of the PPDU that stores the block acknowledgment request frame at SIFS.

[0128] Therefore, if an ongoing data unit exchange is truncated, and at least one data unit defines "normal Ack or implicit block Ack" as its Ack policy, an acknowledgment will be transmitted in response to the truncated PPDU. This obviously stops or hinders the transmission of preemptive data units to different communication devices (pSTAs). It is undesirable to need to receive an acknowledgment before transmitting the pPPDU, or to have a conflict with the pPPDU and Ack. This problem is as follows... Figure 16A As shown.

[0129] For this reason, the Ack policy for any data unit within a truncated data unit exchange will use either a "no Ack" or "block Ack" Ack policy. Therefore, it avoids or, upon request, provides acknowledgment from sSTA to AP, such as... Figure 16B As shown.

[0130] According to another implementation, when establishing a TXOP that may require truncation (e.g., when there is an RTA STA with an active session), this is done as a MU TXOP, where the MU RTS indicates both the sSTA and pSTA. After truncation, fragments of the pPPDU and the remaining sPPDU are transmitted simultaneously, with sufficient padding chosen to account for the oTXTIME boundary as described above. In this case, pPPDU1 is a MU PPDU, whose duration information is considered... Figure 14A and Figure 14B The rules and corresponding equations are shown.

[0131] According to another implementation, the TXOP sharing rules are redesigned to allow early TXOP truncation when the pSTA's access category corresponds to a low-latency sensitive service, or to allow TXOP sharing when an indication of a low-latency service appears on the MAC interface.

[0132] In another implementation, transmission continuation within a TXOP for an sSTA can be applied. The AP can request an Ack for both STAs simultaneously. This can be indicated by a delayed BA request with an expected SIFS response after the pPPDU terminates. The response may be within a TBPPDU. Since the pPPDU is sent from the AP, the sSTA can decode the TXTIME of the pPPDU and synchronize with it to ensure it can participate in the TBPPDU transmission. This operation can be particularly effective if the preempted transmission ends at the end of the TXOP and / or the truncated PPDU is the last one within the TXOP.

[0133] This disclosure can utilize one or more of the following implementations:

[0134] During the TXOP of the sSTA, a truncation request originates from the pSTA on a different link. As discussed in detail above, the first pPPDU can be a trigger frame requesting or allowing the pSTA to transmit the preempted data unit. The truncated transmission can proceed simultaneously with the sSTA to the pSTA, taking into account both the TXOP boundary and the PPDU boundary conditions. An initial RTS is sent to enable the TXOP, ensuring that the pSTA (or the set to which the pSTA belongs) is also addressed in the user field (with some form of preemption indication, but not necessarily an RU). This appears in the first part regarding early discarding but is also important for channel access.

[0135] Truncation can occur within predetermined time intervals, which are announced to STAs (primarily pSTAs or the set to which pSTAs belong, but can be done for all STAs associated with the AP), where low-latency services have priority, and STAs other than low-latency services are more likely to terminate early. In one implementation, in the case of a short preemption unit, the original transmission resumes after the preemption data unit is transmitted.

[0136] The advantages of this disclosure include improved latency for RTA stations with higher priority traffic than the ongoing transmission and one or more of the enablement of PPDU truncation. PPDU truncation provides gain in delay-sensitive traffic; however, the current lack of channel access mechanisms supporting PPDU truncation makes it impossible to implement these types of schemes. This disclosure addresses this limitation.

[0137] Therefore, this disclosure proposes a mechanism for channel access in the event of preemptive transmission, wherein the initial PPDU intended for one STA is truncated to allow data transmission from another STA with high-priority traffic. The presented implementation is particularly suitable for applications requiring real-time, low-latency communication. A method is proposed to ensure the proper distribution of information regarding channel occupancy, sharing, and fairness in channel access for STAs considering transmission boundaries and listening media.

[0138] Therefore, the foregoing discussion has only disclosed and described exemplary embodiments of this disclosure. Those skilled in the art will understand that this disclosure may be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the content of this disclosure is intended to be illustrative, and not to limit, the scope of this disclosure and other embodiments. This disclosure (including any readily identifiable variations taught herein) partially defines the scope of the foregoing claimed terminology, such that no inventive subject matter is intended for public consumption.

[0139] In the claimed content, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple. A single element or other unit can perform the function of several items listed in the claimed content. The fact that certain measures are cited in other, dissimilar claimed content does not mean that a combination of these measures cannot be used advantageously.

[0140] Up to this point, embodiments of the present disclosure have been described as being implemented at least in part by a software-controlled data processing apparatus. It should be understood that non-transitory machine-readable media (e.g., optical discs, magnetic disks, semiconductor memories, etc.) carrying such software are also considered to represent embodiments of the present disclosure. Furthermore, such software may also be distributed in other forms, for example, via the Internet or other wired or wireless telecommunications systems.

[0141] The components of the disclosed devices, apparatuses, and systems can be implemented using corresponding hardware and / or software components, such as dedicated circuits or circuit systems. A circuit is a structural collection of electronic components, including conventional circuit elements, integrated circuits including application-specific integrated circuits (ASICs), standard integrated circuits, dedicated standard products, and field-programmable gate arrays (FPGAs). Furthermore, circuits include central processing units, graphics processing units, and microprocessors programmed or configured according to software code. Although circuits include the hardware that executes the aforementioned software, circuits do not include pure software. A circuit or circuit system can be implemented by a single device or unit, or by multiple devices or units, chipsets, or processors.

[0142] Below is a list of further implementation schemes for the disclosed topic:

[0143] 1. A first communication device configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to:

[0144] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0145] Terminate the ongoing transmission of the data unit before the estimated transmission time of the data unit, and

[0146] During the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity established between the first and second communication devices for the ongoing data unit exchange, receive and / or transmit preemptive data units to the third communication device.

[0147] 2. The first communication device according to any of the foregoing implementation schemes,

[0148] Specifically, the circuit is configured to set the acknowledgment policy of the data unit to no acknowledgment or acknowledgment upon request during data unit exchange with the second communication device.

[0149] 3. The first communication device according to any of the foregoing embodiments, wherein the circuit is configured as follows:

[0150] As part of the ongoing data unit exchange with the second communication device, a first duration indicator is transmitted, indicating the expected duration of the transmission opportunity, and

[0151] After the ongoing transmission of the data unit is interrupted, and as part of receiving or transmitting the data unit from or to the third communication data unit, a second duration indicator is transmitted or received, indicating the remaining duration of the expected transmission opportunity after the transmission of the preempted data unit is completed.

[0152] 4. The first communication device according to implementation scheme 3,

[0153] The second duration indicator is determined based on one or more of the following: the length of the truncated data unit, the expected length of the truncated data unit, the expected duration of the transmission opportunity, and the length of at least one preempted data unit.

[0154] 5. The first communication device according to any of the foregoing embodiments, wherein,

[0155] The circuit is configured to terminate the ongoing transmission of a data unit only if the remaining duration of the expected transmission opportunity after the truncation of the data unit being transmitted is equal to or greater than the expected duration of the following:

[0156] The preemption of the transmission or reception of a data unit and any necessary response to the transmitted or received preempted data unit, or

[0157] The frame that triggers or schedules the transmission of a data unit and any required response to the transmitted or received frame.

[0158] 6. The first communication device according to implementation scheme 3,

[0159] The circuit is configured to generate a second duration indicator that indicates the difference between the remaining duration of the truncated data unit and the duration of the preempted data unit, or between the duration of the trigger frame that triggers the transmission or scheduling of the data exchange with the third communication device and the preempted data exchange with the third communication device, or between the duration of the contention-free end frame and an inter-frame space interval.

[0160] 7. The first communication device according to any of the foregoing embodiments, wherein the circuit is configured as follows:

[0161] Subtract the duration of the preempted data unit and the duration of the acknowledgment and / or inter-frame space from the remaining duration of the truncated data unit; or subtract the duration of the first preempted data unit to be transmitted to the third communication device, the duration of the second preempted data unit to be received from the third communication device, and the two inter-frame spaces from the remaining duration of the truncated data unit.

[0162] Generate a second duration indicator to indicate the result of the subtraction.

[0163] 8. The first communication device according to any of the foregoing embodiments,

[0164] The circuit is configured to add a safety margin to a calculated duration indicated by a second duration indicator based on the short frame time, time slot and / or short frame time tolerance level, the safety margin corresponding to the wake-up time or transmission opportunity extension or set value of the third communication device.

[0165] 9. The first communication device according to any of the foregoing embodiments,

[0166] The circuit is configured to transmit the first preemptive data unit to the third communication device or receive the second preemptive data unit from the third communication device if a first preemptive data unit is to be transmitted to or received from the third communication device, and a second preemptive data unit is to be received from or transmitted to the third communication device, and if the expected transmission opportunity of the second communication device includes the transmission time of one or more additional PHY data units, then transmit the first preemptive data unit to the third communication device and receive the second preemptive data unit from the third communication device.

[0167] If the duration of the second preemptive data unit is shorter than the duration of the transmission time of one or more other PHY data units, a certain amount of padding data is added to the first preemptive data unit so that, without truncation, the end of the first preemptive data unit corresponds to the end of the expected duration of the data unit transmitted to the second communication device.

[0168] 10. The first communication device according to any of the foregoing embodiments,

[0169] The circuit is configured to initiate the transmission of the preemptive data unit before the estimated duration of the ongoing data unit plus the inter-frame spatial time interval, if the first preemptive data unit is to be transmitted to or received from the third communication device, and if the expected transmission opportunity of the second communication device includes the transmission time of one or more additional PHY data units, and if the duration of the second preemptive data unit is longer than the transmission time of one or more additional PHY data units.

[0170] 11. The first communication device according to implementation scheme 5,

[0171] The circuit is configured as follows:

[0172] Subtract the duration of the first preempted data unit to be transmitted to the third communication device, the duration of the second preempted data unit to be received from the third communication device, and the inter-frame space from the sum of the expected length of the truncated data unit and the data unit indicator. The data unit indicator is a positive integer indicating that the truncated data unit is not the last data unit to be transmitted within the current transmission opportunity, and indicates the expected duration of the ongoing transmission.

[0173] Based on the result of the subtraction, it is determined whether to truncate the data unit transmission to the second communication device. The truncation notification indicates that the ongoing data unit should be truncated.

[0174] 12. The first communication device according to any of the foregoing embodiments, wherein the circuit is configured as follows:

[0175] If the truncated data unit is the last data unit to be transmitted within the current transmission opportunity, then the reception duration of the preempted data unit and the inter-frame space are subtracted from the expected duration of the truncated data unit.

[0176] Based on the result of the subtraction, it is determined whether to truncate the data unit transmission to the second communication device. The truncation notification indicates that the ongoing data unit should be truncated.

[0177] 13. The first communication device according to any of the foregoing embodiments,

[0178] The circuit is configured to, as a result of receiving a notification from the third communication device during a transmission opportunity of the second communication device indicating a request to transmit or receive low-latency sensitive services, truncate the data exchange that is taking place with the second device, wherein the notification is received on a link different from the link on which the data exchange is taking place between the first and second communication devices.

[0179] 14. The first communication device according to any of the foregoing embodiments,

[0180] The circuit is configured to act as a first preemptive data unit, transmit a trigger frame, request and / or allow a third communication device to transmit additional preemptive data units during a transmission opportunity obtained for data exchange between the first and second communication devices, or transmit a frame to schedule preemptive data exchange with the third communication device.

[0181] 15. The first communication device according to any of the foregoing embodiments,

[0182] The circuit is configured to transmit a frame of preemptive data unit to a third communication device while transmitting and / or receiving data units to a second communication device, and / or receive preemptive data units from the third communication device simultaneously with data units from the second communication device, and / or transmit preemptive data units to the third communication device, wherein the preemptive data unit contains only the service corresponding to the low-latency service flow identifier established between the first and third communication devices prior to the ongoing data exchange.

[0183] 16. The first communication device according to any of the foregoing embodiments,

[0184] Specifically, the circuit is configured to, as part of establishing a transmission opportunity with the second communication device, transmit a control frame indicating one or more potential preemptions, a user field indicating the third communication device as the intended recipient of the preempted data unit, and one or more user fields indicating a group of communication devices, perform an ongoing data exchange within the second communication device, identify itself as an intended participant in the potential preemption data exchange, and / or, before the ongoing transmission opportunity, truncate the ongoing transmission of the data unit within a predefined time interval negotiated with the third communication device.

[0185] 17. The first communication device according to any of the foregoing embodiments,

[0186] The circuit is configured to truncate the ongoing transmission of a data unit within a predefined time interval negotiated with a third communication device, prior to an ongoing transmission opportunity.

[0187] 18. The first communication device according to any of the foregoing embodiments,

[0188] The circuit is configured to resume the exchange of original data units with the second communication device after transmitting or receiving preempted data units and any required response to the transmitted or received preempted data units.

[0189] 19. The first communication device according to any of the foregoing embodiments,

[0190] The circuit is configured to transmit a duration indicator in the MAC header of the MPDU included in the preemptive data unit.

[0191] 20. The first communication device according to any of the foregoing embodiments,

[0192] Specifically, the circuit is configured to add padding data to the preemptive data unit before transmitting the preemptive data unit.

[0193] 21. The first communication device according to any of the foregoing embodiments,

[0194] The circuit is configured to add a certain amount of padding data to the preempted data unit, such that if it is not truncated, the end of the preempted data unit corresponds to the end of the truncated data unit.

[0195] 22. A first communication device configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to:

[0196] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0197] Before the current transmission opportunity ends, a termination notification indicating the end of the current transmission opportunity will be sent, and

[0198] Establish a new transmission opportunity with a third communication device, wherein the duration of the new transmission opportunity covers at least the transmission of preempted data to and / or the reception of preempted data from the third communication device.

[0199] 23. The first communication device according to implementation scheme 22,

[0200] Wherein, if the duration of preempting the data unit is longer than the duration of the current transmission opportunity (if it is not truncated) minus the duration of the end indication and minus the duration of establishing a transmission opportunity with the third communication device, the difference represents the remaining net duration, then the first part of the preempting data unit is transmitted before the remaining net duration, and the second part of the preempting data unit is transmitted after the remaining net duration.

[0201] 24. The first communication device according to any one of embodiments 22 to 23,

[0202] The duration of a new transmission opportunity is configured to not exceed the duration of the current transmission opportunity without truncation minus the duration of the end indication and minus the duration of the transmission opportunity established with the third communication device.

[0203] 25. The first communication device according to embodiment 24,

[0204] The circuit is configured such that if the first portion of the preempted data unit is not truncated, the first portion is transmitted in alignment with the end of the current transmission opportunity.

[0205] 26. The first communication device according to embodiment 24 or 25,

[0206] The circuit is configured to transmit a first portion and / or a second portion of a preemptive data unit in a multi-user PPDU that includes a data unit for a second communication device and a data unit for a third communication device.

[0207] 27. The first communication device according to any one of embodiments 22 to 26,

[0208] The new transmission opportunity can be shared with a second communication device to exchange at least a portion of the remaining traffic intended for use with the current transmission opportunity.

[0209] 28. The first communication device according to any of the foregoing embodiments,

[0210] Specifically, the circuit is configured to terminate or share the current transmission opportunity with the third communication device if the access category of the service to be exchanged with the third communication device indicates a low latency sensitive access category and / or if a low latency sensitive session has been established between the first and third communication devices before the ongoing data exchange.

[0211] 29. The first communication device according to any of the foregoing embodiments,

[0212] The preemptive data unit includes low-latency services and has parameters established during a setup phase that is performed before ongoing data transmission.

[0213] 30. The first communication device according to any of the preceding embodiments,

[0214] The transmission of a preempted data unit shall not exceed the initial expected duration of the expected data unit, or shall not exceed a function of the short inter-frame space or the short inter-frame space, the time slot time, and the inter-frame tolerance level.

[0215] 31. A third communication device configured to communicate with a first communication device, the third communication device including circuitry configured to;

[0216] Receive data units addressed to the second communication device.

[0217] Determine the duration indicator, which indicates the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for a data unit.

[0218] Determine whether the transmission of the data unit has terminated before the estimated transmission time of the data unit, and

[0219] During the remaining duration of the truncated data unit and / or during the remaining duration of the transmission opportunity, receive and / or transmit preemptive data units from and / or to the first communication device.

[0220] 32. The third communication device according to implementation scheme 31,

[0221] The circuit is configured as follows:

[0222] Subtract the estimated reception duration of the truncated data unit, the reception duration of the preempted data unit, and the inter-frame space from the sum of the expected duration of the truncated data unit and the data unit indicator. The data unit indicator is a positive integer indicating that the truncated data unit is not the last data unit to be transmitted within the current transmission opportunity, and indicates the expected duration of the ongoing transmission.

[0223] Transmit preempted data units with a duration indication equal to the subtraction.

[0224] 33. The third communication device according to implementation scheme 31 or 32,

[0225] The circuit is configured to transmit preemptive data units such that the transmission of the preemptive data unit does not exceed the initial expected end of the truncated data unit, or does not exceed the initial expected end of the data unit from the first communication device to the second communication device, which is a function of the short inter-frame space or the short inter-frame space, the time slot time, and the inter-frame tolerance level.

[0226] 34. The third communication device according to any one of the embodiments 31 to 33,

[0227] Specifically, the circuit is configured to reset the network allocation vector (NAV) before the end of an ongoing transmission opportunity and / or before the expected duration of a data unit from the first communication device to the second communication device ends, upon determining one or more of the following:

[0228] Intending to prematurely terminate the ongoing data exchange.

[0229] Receive a trigger frame from the third communication device requesting to preempt data unit transmission.

[0230] Receive preemption data units with response requests, and

[0231] The time interval is defined by the potential truncation indicator.

[0232] 35. The third communication device according to any one of the embodiments 31 to 34,

[0233] The circuit is configured to determine whether an indication of a low-latency service identifier exists in a preemptive data unit or whether a trigger frame requesting the transmission of a preemptive data unit has been received.

[0234] 36. The third communication device according to any one of the embodiments 31 to 35,

[0235] In this process, low-latency service identifiers and preemption parameters have been negotiated prior to the ongoing data exchange.

[0236] 37. The third communication device according to any one of the embodiments 31 to 36,

[0237] The circuit is configured to transmit or receive a second duration indicator after interrupting the ongoing transmission of a data unit, and as part of receiving or transmitting a data unit from or to a third communication data unit, indicating the remaining duration of the expected transmission opportunity after the completion of the transmission of the preempted data unit.

[0238] 38. The third communication device according to any one of the embodiments 31 to 37,

[0239] The circuit is configured as a first preemptive data unit to receive a trigger frame, request and / or allow a third communication device to transmit additional preemptive data units during a transmission opportunity obtained for data exchange between the first and second communication devices, or to transmit frames and schedule preemptive data exchange with the third communication device.

[0240] 39. A first communication method for communicating with a second communication device and a third communication device, the first communication method comprising:

[0241] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0242] Before the estimated transmission time of the data unit, terminate the ongoing transmission of the data unit, and

[0243] During the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity established between the first and second communication devices for the ongoing data unit exchange, receive and / or transmit preemptive data units to the third communication device.

[0244] 40. A first communication method for communicating with a second communication device and a third communication device, the first communication method comprising:

[0245] During the ongoing data unit exchange with the second communication device, a cutoff notification is received, indicating that the ongoing transmission of the data unit should be cut off, and that the preemptive data unit should be received from and / or transmitted to the third communication device.

[0246] Before the current transmission opportunity ends, a termination notification indicating the end of the current transmission opportunity will be sent, and

[0247] Establish a new transmission opportunity with a third communication device, wherein the duration of the new transmission opportunity covers at least the transmission of preempted data to and / or the reception of preempted data from the third communication device.

[0248] 41. A third communication method for communicating with a first communication device, the third communication method comprising:

[0249] Receive data units addressed to the second communication device.

[0250] Determine the duration indicator, which indicates the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for a data unit.

[0251] Determine whether the transmission of the data unit has terminated before the estimated transmission time of the data unit, and

[0252] During the remaining duration of the truncated data unit and / or during the remaining duration of the transmission opportunity, receive and / or transmit preemptive data units from and / or to the first communication device.

[0253] 42. A non-transitory computer-readable recording medium in which a computer program product is stored, which, when executed by a processor, causes to perform the method according to embodiment 39, 40 or 41.

[0254] 43. A computer program, including a program code device, for causing the computer to perform the steps of the method according to embodiments 39, 40 or 41 when the computer program is executed on a computer.

Claims

1. A first communication device configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to: During ongoing data unit exchange with the second communication device, a truncation notification is received, indicating that the ongoing transmission of the data unit should be truncated, and that a preemptive data unit should be received from and / or transmitted to the third communication device. The ongoing transmission of the data unit is terminated before the estimated transmission time of the data unit, and During the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity established between the first and second communication devices for exchanging the ongoing data unit, receive and / or transmit preemptive data units from and / or to the third communication device.

2. The first communication device according to claim 1, in, The circuit is configured to set the acknowledgment policy for data units to no acknowledgment or acknowledgment upon request during ongoing data unit exchanges with the second communication device.

3. The first communication device according to claim 1, in, The circuit is configured as follows: As part of the ongoing data unit exchange with the second communication device, a first duration indicator is transmitted, indicating the expected duration of the transmission opportunity, and After the ongoing transmission of the data unit is interrupted, and as part of receiving or transmitting a data unit from or to the third communication data unit, a second duration indicator is transmitted or received, the second duration indicator indicating the remaining duration of the expected transmission opportunity after the transmission of the preempted data unit is completed.

4. The first communication device according to claim 1, in, The circuit is configured to terminate the ongoing transmission of the data unit only if the remaining duration of the expected transmission opportunity after the truncation of the ongoing data unit is equal to or greater than the expected duration of the following: The transmission or reception of the preempted data unit and any required response to the transmitted or received preempted data unit, or The frames that trigger or schedule the transmission of the preemptive data unit and any necessary responses to the transmitted or received frames.

5. The first communication device according to claim 1, in, The circuit is configured to transmit the first preemptive data unit to the third communication device and receive the second preemptive data unit from the third communication device if a first preemptive data unit is to be transmitted to or received from the third communication device, and a second preemptive data unit is to be received from or transmitted to the third communication device, and if the expected transmission opportunity of the second communication device includes the transmission time of one or more additional PHY data units. If the duration of the second preemptive data unit is shorter than the duration of the transmission time of the one or more other PHY data units, a certain amount of padding data is added to the first preemptive data unit so that, without truncation, the end of the first preemptive data unit corresponds to the end of the expected duration of the data unit transmitted to the second communication device.

6. The first communication device according to claim 1, in, The transmission of the preempted data unit does not exceed the initial expected duration of the expected data unit, or does not exceed a function of the short inter-frame space or the short inter-frame space, time slot and inter-frame tolerance level.

7. The first communication device according to claim 1, in, The circuit is configured to, as a result of receiving a notification from the third communication device during a transmission opportunity of the second communication device indicating a request to transmit or receive low-latency sensitive services, truncate the ongoing data exchange with the second communication device, wherein the notification is received on a link different from the link on which the ongoing data exchange between the first and second communication devices is being performed.

8. The first communication device according to claim 1, in, The circuit is configured to, as a first preemptive data unit, transmit a trigger frame, request and / or allow the third communication device to transmit additional preemptive data units during a transmission opportunity obtained for data exchange between the first and second communication devices, or transmit a frame, schedule preemptive data exchange with the third communication device and / or transmit a frame of preemptive data units to the third communication device while transmitting and / or receiving data units to the second communication device, and / or receive preemptive data units from the third communication device simultaneously with data units from the second communication device, and / or transmit preemptive data units to the third communication device, wherein the preemptive data unit contains only the service corresponding to a low-latency service flow identifier established between the first and third communication devices prior to the ongoing data exchange.

9. The first communication device according to claim 1, in, The circuit is configured to, as part of establishing a transmission opportunity with the second communication device, transmit a control frame indicating one or more potential preemptions, a user field indicating the third communication device as the intended recipient of the preempted data unit, and one or more user fields indicating a group of communication devices, perform the ongoing data exchange within the second communication device, the third communication device identifying itself as an intended participant in the potential preempted data exchange, and / or, prior to the ongoing transmission opportunity, truncate the ongoing transmission of the data unit within a predefined time interval negotiated with the third communication device.

10. The first communication device according to claim 1, in, The circuit is configured to terminate or share the current transmission opportunity with the third communication device if the access category of the service to be exchanged with the third communication device indicates a low latency sensitive access category and / or if a low latency sensitive session has been established between the first communication device and the third communication device before the ongoing data exchange.

11. A first communication device configured to communicate with a second communication device and a third communication device, the first communication device including circuitry configured to: During ongoing data unit exchange with the second communication device, a truncation notification is received, indicating that the ongoing transmission of the data unit should be truncated, and that a preemptive data unit should be received from and / or transmitted to the third communication device. Before the current transmission opportunity ends, a termination notification indicating the end of the current transmission opportunity is transmitted, and Establish a new transmission opportunity with the third communication device, wherein, The duration of the new transmission opportunity covers at least the transmission of preempted data to and / or the reception of preempted data from the third communication device.

12. The first communication device according to claim 11, in, If the duration of the preempted data unit is longer than the current transmission opportunity duration minus the end indication duration and the duration of establishing a transmission opportunity with the third communication device if it is not truncated, and the difference represents the remaining net duration, then the first part of the preempted data unit is transmitted before the remaining net duration, and the second part of the preempted data unit is transmitted after the remaining net duration.

13. The first communication device according to claim 12, in, The circuit is configured to transmit the first portion aligned with the end of the current transmission opportunity if the first portion of the preemptive data unit is not truncated, and / or transmit the first and / or second portions of the preemptive data unit in a multi-user PPDU including data units for the second communication device and data units for the third communication device.

14. The first communication device according to claim 11, in, The circuit is configured to terminate or share the current transmission opportunity with the third communication device if the access category of the service to be exchanged with the third communication device indicates a low latency sensitive access category and / or if a low latency sensitive session has been established between the first communication device and the third communication device before the ongoing data exchange.

15. A third communication device configured to communicate with a first communication device, the third communication device including circuitry configured to; Receive data units addressed to the second communication device. Determine the duration indicator, which indicates the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for a data unit. Determine whether the transmission of the data unit has terminated before the estimated transmission time of the data unit, and During the remaining duration of the truncated data unit and / or during the remaining duration of the transmission opportunity, receive and / or transmit preemptive data units from the first communication device to the first communication device.

16. The third communication device according to claim 15, in, The circuit is configured as follows: Subtract the estimated reception duration of the truncated data unit, the reception duration of the preempted data unit, and the inter-frame space from the sum of the expected duration of the truncated data unit and the data unit indicator. The data unit indicator is a positive integer indicating that the truncated data unit is not the last data unit to be transmitted within the current transmission opportunity, and indicates the expected duration of the ongoing transmission. Transmit preempted data units with a duration indication equal to the subtraction.

17. The third communication device according to claim 15, in, The circuit is configured to reset the network allocation vector (NAV) before the end of an ongoing transmission opportunity and / or before the expected duration of a data unit from the first communication device to the second communication device ends, upon determining one or more of the following: Intending to prematurely terminate the ongoing data exchange. The third communication device receives a trigger frame requesting to preempt data unit transmission. Receive preemption data units with response requests, and The time interval is defined by the potential truncation indicator.

18. A first communication method for communicating with a second communication device and a third communication device, the first communication method comprising: During ongoing data unit exchange with the second communication device, a truncation notification is received, indicating that the ongoing transmission of the data unit should be truncated, and that a preemptive data unit should be received from and / or transmitted to the third communication device. Before the estimated transmission time of the data unit, terminate the ongoing transmission of the data unit, and During the remaining duration of the truncated data unit or during the remaining duration of the transmission opportunity established between the second and third communication devices for exchanging the ongoing data unit, receive and / or transmit preemptive data units from and / or to the third communication device.

19. A first communication method for communicating with a second communication device and a third communication device, the first communication method comprising: During ongoing data unit exchange with the second communication device, a truncation notification is received, indicating that the ongoing transmission of the data unit should be truncated, and that a preemptive data unit should be received from and / or transmitted to the third communication device. Before the current transmission opportunity ends, a termination notification indicating the end of the current transmission opportunity is transmitted, and A new transmission opportunity is established with the third communication device, wherein the duration of the new transmission opportunity covers at least the transmission of preemptive data to and / or the reception of preemptive data from the third communication device.

20. A third communication method for communicating with a first communication device, the third communication method comprising: Receive data units addressed to the second communication device. Determine the duration indicator, which indicates the expected duration of an ongoing transmission and / or an ongoing transmission opportunity for a data unit. Determine whether the transmission of the data unit has terminated before the estimated transmission time of the data unit, and During the remaining duration of the truncated data unit and / or during the remaining duration of the transmission opportunity, receive and / or transmit preemptive data units from the first communication device to the first communication device.

21. A non-transitory computer-readable recording medium in which a computer program is stored, which, when executed by a processor, causes to perform the method according to claim 18, 19 or 20.

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