Communication device and method

Abstract

A communication device configured to communicate with a second communication device, the communication device comprising circuitry configured to transmit one or more data frames to the second communication device, request a response from the second communication device, listen for a first response acknowledging receipt of at least one of the one or more data frames from the second communication device, and if the first response is not received, change a transmission opportunity configuration and / or channel access for non-data frames and / or data frames.

Description

background Technical Field

[0002] This disclosure relates to communication devices and methods, particularly for low-latency communication in wireless local area networks (WLANs).

[0003] Related technical description: Since WLAN operates in unlicensed spectrum shared by communication devices, it is possible for transmitted data units (such as Physical Layer Conformance Process (PLCP) Protocol Data Units (PPDUs)) to become undecodeable or be lost, for example, due to simultaneous transmission by another communication device or interference from another network or another wireless device.

[0004] When an entire PPDU is undecodeable, i.e., a failed PPDU exists, this has a significant impact on latency because, according to the current channel access rules of WLAN, communication devices, especially stations (STAs), extend (often double) their contention window in this situation. In busy networks, this can cause communication devices to wait a long time before they can re-access the channel and transmit the data that should have been transmitted in the failed PPDU.

[0005] The “background” description provided herein is intended to generally present the context of this disclosure. Within the scope described in this background section, the work of the currently named inventors, and aspects of the description that may not constitute prior art at the time of filing, are neither explicitly nor implicitly considered to be prior art to this invention. Summary of the Invention

[0006] Its purpose is to provide enhanced channel access principles for WLANs to improve latency. Corresponding communication devices and equipment, as well as corresponding computer programs and non-transitory computer-readable recording media, are provided to implement the method.

[0007] According to the aforementioned aspect, a communication device is provided, configured to communicate with a second communication device, the communication device including circuitry configured to: transmit one or more data frames to the second communication device, requesting a response from the second communication device; listen for a first response, confirming that at least one data frame from the one or more data frames has been received from the second communication device; and, if the first response is not received, modify the transmission opportunity configuration and / or channel access for non-data frames and / or data frames.

[0008] According to another aspect, a communication method for communicating with a second communication device is provided, the communication method comprising: transmitting one or more data frames to the second communication device and requesting a response from the second communication device; listening for a first response confirming receipt of at least one of the one or more data frames from the second communication device; and, if no first response is received, modifying the transmission opportunity configuration and / or channel access for non-data frames and / or data frames.

[0009] According to another aspect, a computer program is provided, including program means for causing the computer to perform the steps of the method described herein when the computer program is executed on a computer, and a non-temporary computer-readable recording medium storing a computer program product that, when executed by a processor, will cause the method described herein to be executed.

[0010] The embodiments are defined in the dependent claims. It should be understood that the disclosed communication method, the disclosed computer program, and the disclosed computer-readable recording medium have similar and / or identical further embodiments to the claimed communication device and those defined in the dependent claims and / or disclosed in this disclosure.

[0011] One aspect of this disclosure is to limit the increase in latency due to PPDU failure by adding one or more rules to existing channel access mechanisms. Each rule can be applied alone or in combination with other rules.

[0012] This disclosure proposes enhanced channel access principles for wireless local area networks (WLANs) to improve latency. More specifically, several independent rules are defined to generate timely and rapid retransmissions after the initial transmission failure of a Physical Protocol Data Unit (PPDU; also referred to herein as data PPDU). Failed PPDUs can occur due to interference or collisions between two or more stations (STAs), i.e., simultaneous transmissions. Therefore, the proposed rules are applicable to distributed channel access, where collisions may occur frequently. Furthermore, it is proposed that an AP STA can enable and require its associated STAs to consider these rules to achieve a Basic Service Set (BSS) with low-latency service.

[0013] Therefore, according to embodiments of this disclosure, if a first confirmation is not received, measures are taken to shorten the time that the communication device must wait before successfully retransmitting the data unit and / or the time that the second communication device or another communication device must wait before transmitting the data unit.

[0014] Throughout this disclosure, access points are referred to as AP STAs, and stations as non-AP STAs. The term STA is used interchangeably for both non-AP STAs and AP STAs; that is, it applies to both types of STAs.

[0015] The foregoing paragraphs are for general description only and are not intended to limit the scope of the following claims. The described embodiments and their further advantages will be best understood by referring to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0016] A more complete understanding of this disclosure and its many accompanying advantages will be readily obtained when considered in conjunction with the accompanying drawings, by referring to the following detailed description, as the disclosure and its many accompanying advantages become better understood in the drawings:

[0017] Figure 1A A schematic diagram illustrating a routine successful frame exchange between two STAs is shown.

[0018] Figure 1B A schematic diagram illustrating the typical behavior when a peer STA cannot receive the first transmitted data unit is shown.

[0019] Figure 2A A schematic diagram illustrating a regular retransmission that does not exclude rate probing is shown.

[0020] Figure 2B A schematic diagram illustrating retransmission excluding rate detection according to an embodiment of the present disclosure is shown.

[0021] Figure 3A A schematic diagram illustrating a standard retransmission operation that allows new data to be sent while maintaining the transmission opportunity of retransmitted data is available.

[0022] Figure 3B A schematic diagram illustrating the exclusion of new data during the transmission of data retransmission opportunities according to an embodiment of the present disclosure is shown.

[0023] Figure 4A The diagram illustrates the conventional use of beacon operations and / or length to resolve conflicts.

[0024] Figure 4B A schematic diagram illustrating conflict resolution using beacon delay according to an embodiment of the present disclosure is shown.

[0025] Figure 4C and Figure 4A same.

[0026] Figure 4D A schematic diagram illustrating conflict resolution using a reduced beacon length according to an embodiment of this disclosure is shown.

[0027] Figure 4E and Figure 4A same.

[0028] Figure 4F A schematic diagram illustrating conflict resolution for contention-free retransmission of data frames directly after beacon transmission, according to an embodiment of the present disclosure, is shown.

[0029] Figure 5A A schematic diagram illustrating routine operations in a multi-link setup is shown.

[0030] Figure 5BA schematic diagram illustrating the use of link selection for retransmission to resolve conflicts in a multi-link setup according to an embodiment of the present disclosure is shown.

[0031] Figure 6A A schematic diagram illustrating the standard operations used for retransmission is shown.

[0032] Figure 6B A schematic diagram illustrating the use of access priority of block confirmation requests to resolve conflicts according to an embodiment of this disclosure is shown.

[0033] Figure 7A A schematic diagram illustrating the standard operation of retransmission with the TXOP duration unchanged is shown.

[0034] Figure 7B A schematic diagram illustrating the shortening of the TXOP duration according to an embodiment of the present disclosure is shown.

[0035] Figure 8 A schematic diagram of the configuration of a communication device 30 according to an embodiment of the present disclosure is shown.

[0036] Figure 9 A flowchart illustrating an embodiment of the communication method according to this disclosure is shown. Detailed Implementation

[0037] Generally, this disclosure considers the scenario where a STA transmits one or more data units (hereinafter referred to as, but not limited to, PPDUs) within a transmission opportunity (TXOP). One or more of these PPDUs have not yet been decoded; that is, there are one or more failed PPDUs detected due to the loss of responses (e.g., Ack, BAck) from the peer STA. In this case, the loss of responses may be the only necessary condition for detecting failed data PPDUs, since the loss of responses can also occur in the case of failed response PPDUs.

[0038] If the lost response occurs within a TXOP, i.e., not at the start, it is further assumed that the channel is detected as busy at the transmitter or TXOP initiator location. In both cases—a lost response at the start of a TXOP or a lost response within a TXOP while the channel is busy—the transmitting STA should stop transmission and back off. In this context, the start of a TXOP is understood as the first response to one or more PPDUs within that TXOP, while being within a TXOP is understood as a non-first response to one or more PPDUs within that TXOP.

[0039] Referring now to the accompanying drawings, in which the same reference numerals indicate the same or corresponding parts in several views. Figure 1AA schematic diagram illustrating a typical successful frame exchange between two STAs is shown. STA 1 performs contention by listening to the channel over a specific time span, which is given by an offset (AIFS) and a multiple of a predefined slot time. The multiple of the slot time is determined by a contention window (CW) value, which is initially drawn from a random uniform distribution, ranging from [0…CWmin-1], once the STA has data to transmit.

[0040] Typically, the CW value is decremented by 1 after each time slot interval, and the channel is idle. Once the CW value reaches zero and the channel is idle, STA 1 acquires a TXOP and transmits one or more PPDUs, including any potential responses from peer STAs. Figure 1A The TXOP (Turn-Turn Opt) is a block acknowledgment process. The TXOP ends when STA1 has no more data to transmit or the maximum TXOP time expires. Once the TXOP ends, the STA will again perform the contention process described above to gain channel access.

[0041] Figure 1B The diagram illustrates the typical behavior of peer STA 2 when it is unable to receive the first transmitted PPDU due to, for example, interference. In this case, after STA 1 transmits PPDU A, STA 2 does not transmit a response frame (i.e., any acknowledgment, also referred to herein as "first acknowledgment" or "first response"). STA 1 detects the lost response after a certain timeout, stops transmission, and the associated TXOP ends. To regain access to the channel, STA 1 extracts a new CW value from a uniform distribution with an increasing range from [0…2·CWmin⁻¹], which may involve a longer contention time.

[0042] Each time a particular PPDU is detected as undecodeable or lost, the range of the CW's uniform distribution typically doubles further. The more likely other STA transmissions are to interrupt the CW countdown, the higher the CW becomes. This can lead to significant latency, not only due to longer contention times but also due to the duration of other transmissions that occur before STA1 is able to transmit again.

[0043] A PPDU can carry a MAC Protocol Data Unit (MPDU) or an aggregated MPDU (A-MPDU) containing one or more MPDUs. Each MPDU holds MAC header information, the user data to be transmitted, and a check sequence to check the integrity of the MPDU. A PPDU is undecodeable or fails if the transmitter observes that: every MPDU contained in the PPDU is incomplete (i.e., a check sequence error occurs, including cases of BAck responses, indicating that all MPDUs are incorrect); or the expected response frame from the peer STA is not received.

[0044] It is important to note that there are generally three different types of frames: data frames (frames that store data, such as content, user data, and communication data), control frames (such as Ack, BAck, Ack request, and BAck request), and management frames (such as beacon frames).

[0045] The ideas presented below address STA behavior following a failed or undecoding PPDU transmission, specifically retransmitting data residing in the failed PPDU, i.e., an MPDU or A-MPDU. The following embodiments describe rules or add-ons to existing rules and their application, which may comply with the decisions of all non-AP STAs or the AP STAs of a certain set of non-AP STAs. Each rule or add-on can be applied individually or in conjunction with other rules. The more STAs that enforce the rules, the more useful they become. This can be important in the context of legacy STAs, as they are unaware of these rules. Therefore, two options can be envisioned for mitigation purposes.

[0046] According to the first option, APSTAs can restrict access to their BSS (Basic Service Set) by applying one or more of these rules or add-ons to non-APSTAs. Therefore, APSTAs can create BSSs optimized for latency-sensitive data traffic. According to the second option, an advantage is provided to non-APSTAs that implement one or more of the following procedures regarding Enhanced Distributed Channel Access (EDCA) parameters. This is because STAs that do not perform one or more of these procedures may have throughput advantages but latency disadvantages. This advantage can be balanced by slightly modifying the access parameters.

[0047] A first embodiment of the apparatus and method according to this disclosure is shown in FIG2, wherein, Figure 2A A schematic diagram illustrating a regular retransmission that does not exclude rate probing is shown. Figure 2B A schematic diagram illustrating retransmissions that do not exclude rate detection according to an embodiment of the present disclosure is shown.

[0048] According to this embodiment, after a PPDU transmission failure, the STA modifies the transmission operation of the next PPDU by changing one or more of the following transmission parameters compared to the failed PPDU:

[0049] Modulation and coding scheme (MCS)

[0050] • Transmission bandwidth

[0051] Number of spatial flows

[0052] • Transmission method (STBC or DCM)

[0053] • PPDU type (SU-PPDU or MU-PPDU).

[0054] These transmission parameters affect the length of the PPDU and the number of MPDUs that can be included in a PPDU. Therefore, a failed retransmission of an MPDU may require multiple PPDUs. Which transmission parameters to apply depends on the STA. However, if the STA decides to change the transmission parameters, it will apply the same parameters to all PPDUs containing retransmission MPDUs, until the following condition is met.

[0055] - The first PPDU containing the retransmission MPDU failed, or

[0056] - All PPDUs containing retransmitted data units were successful, or

[0057] - After the first PPDU succeeds, it is known that there are other transmission parameters to achieve a higher ratio of successful MPDUs to failed MPDUs.

[0058] This means that the STA recently checked these transmission parameters.

[0059] The rules applied in this embodiment seek to avoid inspecting the transmission parameters of PPDUs containing retransmitted MPDUs. This inspection is done through trial and error, i.e., by transmitting the PPDU using the transmission parameters to be inspected. The response of the peer STA allows conclusions to be drawn about the quality of these transmission parameters. If the quality is unknown beforehand, the STA tolerates PPDU loss, which is undesirable for PPDUs containing retransmitted MPDUs, as it leads to further retransmissions and delays.

[0060] In Figure 2, (not used) Figure 2A ) or use ( Figure 2B The operational difference of this rule is visible. Because this rule does not allow the transmission of the second part of a PPDUA with an unknown set of transmission parameters C, another retransmission is avoided, which leads to a reduction in latency.

[0061] like Figure 2B As shown, after STA1 transmits a data unit (PPDU A) to STA2, it listens for the first acknowledgment (e.g., Ack or BAck) received from STA2. If the first acknowledgment is not received, measures are taken to shorten the time the communication device must wait before successfully retransmitting the data unit. In this embodiment, the data unit is retransmitted in parts, wherein one or more transmission parameters (Tx parameter set B) used for retransmitting data are different from the transmission parameters (Tx parameter set A) used for the initial transmission of the data unit.

[0062] In one variant, the transmission parameters used for retransmitting all parts of the data unit are the same. In another variant, after the first part of the data unit is retransmitted, STA 1 listens again for a second acknowledgment (also referred to here as the "second response") from STA 2. If STA 1 receives the second acknowledgment, one or more subsequent parts of the data unit (e.g., the second part) are retransmitted using one or more transmission parameters different from those used for the initial transmission of the data unit. If STA 1 does not receive the second acknowledgment, the next part of the data unit is transmitted using new transmission parameters (e.g., the Tx parameter set C). The one or more different transmission parameters include one or more transmission parameters from a transmission parameter group, which includes modulation and coding schemes, transmission bandwidth, number of spatial streams, transmission method, and type of data unit.

[0063] Therefore, according to the embodiment shown in FIG2, if no first response is received, the transmission parameters used to transmit the data frame are changed. Specifically, one or more data frames are retransmitted in parts. The one or more transmission parameters used for retransmitting the one or more data frames are different from the transmission parameters used for initially transmitting the one or more data frames, wherein the transmission parameters used for retransmitting the parts of the one or more data frames are the same.

[0064] A second embodiment of the apparatus and method according to this disclosure is shown in FIG3, wherein, Figure 3A A schematic diagram illustrating the standard operation of a retransmission is shown, and... Figure 3B A schematic diagram illustrating the exclusion of new data during the transmission of data retransmission opportunities according to an embodiment of the present disclosure is shown.

[0065] After a PPDU transmission fails, the TXOP containing one or more PPDUs with retransmitted MPDUs should contain no more MPDUs than those already transmitted in the failed PPDU. Furthermore, the MPDU transmission order is the same as the failed PPDU. If a retransmitted MPDU is not suitable for transmission within a single PPDU, multiple PPDUs are transmitted in the same or a new TXOP. This may occur due to time PPDU length limitations and / or because transmission parameters have changed. For example, in the first transmission, the time PPDU length limit is fully utilized. For the second transmission (retransmission), the modulation and coding scheme is set to a lower value, i.e., a lower coding rate and / or modulation order. Therefore, the MPDU requires more time to transmit, and a second PPDU is needed to transmit the remaining MPDUs that were not suitable for the first retransmitted PPDU.

[0066] According to this embodiment, after each transmitted PPDU or after the latest PPDU containing the last part of a retransmitted MPDU is transmitted, the STA requests an Ack or BAck indicating the reception status of the retransmitted MPDU. Upon receiving an Ack or BAck and after all retransmitted MPDUs have been successfully received, the STA transmits a termination notification to indicate the end of the current TXOP to other STAs. The termination notification may be in the form of a frame, particularly a contention-free (CF) end frame, indicating the end of the period during which the STA cannot contend.

[0067] Figure 3 illustrates a scenario where STA1 and STA2 want to transmit data to STA3. Since STA1 and STA2 obtain channel access simultaneously, their PPDUs collide. Due to the loss of STA3's response, STA1 and STA2 detect this collision. Figure 3A This illustrates the typical operation in this situation: after STA1 regains channel access rights, it first retransmits the PPDUA, then another PPDUB containing new data, to take advantage of the TXOP duration. This results in STA2 transmitting its retransmitted PPDUB significantly later. Conversely, Figure 3B This illustrates the operation when STA 1 terminates its TXOP after retransmitting PPDU A, preferably after it has received a second acknowledgment of reception of the retransmitted data unit from STA 2. Therefore, STA 2 has the opportunity to access the channel more quickly to retransmit PPDU C. (Comparison) Figure 3A and 3B The delay gain of the STA (i.e., STA2 in this example) that is retransmitted later is clearly revealed.

[0068] In another embodiment, after transmitting the PPDUA and loss response to STA2, STA1 can transmit (e.g., additionally or appended to the retransmitted PPDUA) a new PPDUB with the same and / or higher priority than the previously transmitted PPDUA. This provides the advantage that new data frames arriving with the same or higher priority (e.g., low-latency priority) while STA1 is contending for channel access to retransmit the PPDUA can be transmitted immediately along with the PPDUA retransmission. This helps reduce the transmission delay of new data frames because further contention for channel access is avoided.

[0069] In normal WLAN operation, beacon frames are occasionally transmitted to announce the presence of the network. If the beacon frame is delayed and retransmitted, it can cause latency. Therefore, the rule used according to various embodiments of this disclosure is that if the AP STA fails to send a PPDU, one of several measures can be taken, as illustrated with reference to Figures 4 and 5.

[0070] A third embodiment of the device and method disclosed herein is shown in FIG4, wherein... Figure 4A , 4C The diagrams 4E and 4E (which are identical) illustrate the conventional method of resolving conflicts using rule-based beacon lengths. Figure 4B A schematic diagram illustrating conflict resolution using beacon delay according to an embodiment of this disclosure is shown. Figure 4D A schematic diagram illustrating conflict resolution using reduced beacon length according to an embodiment of this disclosure is shown, and... Figure 4F A schematic diagram illustrating how to resolve collisions by directly and contention-free retransmission of data frames after beacon transmission, according to an embodiment of the present disclosure.

[0071] According to this embodiment, beacon frame transmission is delayed, or only the mandatory portion of the content is transmitted, or SMS beacon frames encoded using a high modulation and coding scheme (MCS) less than or equal to the lowest MCS currently applied in its BSS are transmitted.

[0072] Figure 4 illustrates the beacon delay ( Figure 4B or short beacon frames ( Figure 4D The impact of beacon frames. Shorter beacon frames can be achieved with less content or a higher MCS. The delay gain is revealed because the beacon is shifted in time or less time is spent on beacon transmission. Beacon transmission should only be delayed and shortened if retransmission occurs concurrently with beacon transmission.

[0073] Figure 4F An embodiment of contention-free retransmission after a failed PPDU transmission by the AP is illustrated, i.e., the beacon is not delayed, but time is reserved for retransmission immediately after the beacon has been transmitted. Therefore, after missing a response, the AP does not delay the beacon but sends a retransmission directly after the beacon / short message frame without contention. For this purpose, the AP reserves channel time for retransmission or allows the STA to retransmit. This is not a periodic interval but a reserved time interval that occurs when no response to the retransmission is received and subsequent transmissions from the AP are beacon transmissions. An indication of a one-time contention-free interval can be given in the beacon, or access rules can be defined to allow channel access within the Priority Inter-Frame Space (PIFS) or CW=0 and no backoff for AP transmission retransmissions.

[0074] In the downlink, the operation might be as follows: The AP includes an indication of a contention-free interval in the beacon. STAs that have lost packets should remain awake after the beacon transmission. The duration of this interval should cover retransmission, response (acknowledgment), and the corresponding inter-frame interval (IFS), and can be published in a PPDU sent by the AP. After publication (e.g., after SIFS), the AP performs a retransmission and waits for a response (e.g., acknowledgment). Alternatively, a similar approach will be explained below. Figure 6BIn the embodiment shown, if the reason for the response failure may be due to interference at the AP, the duration of the interval can be selected to cover the response request (e.g., acknowledgment request), the response (e.g., acknowledgment), potential retransmissions, and response (e.g., acknowledgment) retransmissions. If the response to the response request indicates a non-failure PPDU, the AP can terminate the current period by a transmission termination notification (e.g., a CF end frame), such as... Figure 3B As shown.

[0075] In the uplink, the operation might be as follows: If the AP fails to decode the PPDU from the STA, it can send a trigger or poll at the start of the contention-free period immediately after the beacon is sent, for example within the PIFS, to request a retransmission from the STA. The trigger or poll will then trigger a retransmission within the SIFS interval.

[0076] Therefore, according to the reference Figure 4B , Figure 4D and Figure 4F In the illustrated embodiment, if a first response is not received, the channel access for non-data frames and / or data frames is changed. Specifically, the transmission and / or retransmission of beacon frames are altered compared to regular beacon frame transmission, whereby the beacon frame has a predetermined length and is transmitted after the target beacon transmission time using a predetermined modulation and coding scheme. If the first response is not received, one or more data frames are retransmitted to a second communication device, and the channel access for the beacon frame is changed compared to regular beacon frame transmission, whereby the beacon frame has a predetermined length and is transmitted after the target beacon transmission time using a predetermined modulation and / or coding scheme.

[0077] In this embodiment, the modulation and / or coding scheme is selected such that all STAs associated with the AP can receive and / or decode beacon frames. Within the AP's BSS, the links between all AP-STA pairs have different link budgets due to, for example, different path losses. The lower the link budget, the lower the modulation and / or coding scheme. If the modulation and / or coding scheme is selected as the smallest among all AP-STA pairs, then any STA within the BSS can receive the beacon. STAs outside the BSS may be unaffected, as this behavior naturally limits the beacon's coverage area. Therefore, this rule may only apply to retransmission cases. In all other cases, the beacon should be transmitted with the lowest MCS to maintain the maximum coverage area.

[0078] A fourth embodiment of the apparatus and method according to this disclosure is shown in FIG5, wherein, Figure 5A A diagram illustrating routine operations in a multi-link setup is shown, and Figure 5B A schematic diagram illustrating the use of link selection for retransmission to resolve conflicts in a multi-link setup according to an embodiment of the present disclosure is shown.

[0079] If the AP STA supports multiple links, it will use that link for retransmission. Retransmission can be completed before sending the next beacon, and is enabled for the STA that needs to retransmit. This operation is... Figure 5B The diagram illustrates an example of reduced latency due to link selection that avoids beacon transmission. Assume that at some point during the retransmission, both links are active and link 2 is idle.

[0080] In conventional operation, beacons are transmitted according to the schedule of the first target beacon transmission time (TBTT) on the first link. After another contention, the data unit is retransmitted on the first link. In parallel, if scheduled by the second TBTT (on link 2), another beacon can be transmitted on the second link. Conversely, according to embodiments of this disclosure, since the second TBTT (on link 2) is later than the first TBTT (on link 1), the data unit is retransmitted on the second link. In parallel, the beacon is transmitted on the first link after the first TBTT. This provides a significant delay gain compared to conventional operation. It should be noted in this context that this embodiment also applies if the STA transmitting the PPDU is a non-AP STA.

[0081] Therefore, according to the embodiment shown in FIG5, if the first response is not received, the channel access of the data frame is changed.

[0082] A fifth embodiment of the apparatus and method according to this disclosure is shown in FIG6, wherein, Figure 6A A schematic diagram illustrating the standard operation of retransmission is shown, and Figure 6B A schematic diagram illustrating the use of Block Acknowledgment Request (BAR) access priority to resolve conflicts according to an embodiment of this disclosure is shown.

[0083] In a typical WLAN, a STA can transmit a BAR to request a block acknowledgment to maintain the MPDU receive state at the peer STA. Obtaining the BAck state can be helpful before taking any action (such as retransmitting data), as a lost BAck response can have various causes: a data PPDU transmission failure, an undecodeable data PPDU, or a BAck not received or undecodeable.

[0084] In the second scenario (BAck not received or undecodeable), it may happen that all data has been successfully received, but the BAck is incorrect. To eliminate unnecessary retransmissions, this embodiment proposes that when the BAR is sent in the PPDU without an attached MPDU, the BAR should be given priority in channel access; that is, only the BAR is transmitted, and a BAck response is waited for before initiating any retransmission of the data PPDU. This BAR access priority can be implemented as follows.

[0085] A BAR can be transmitted using any Access Class (AC) or an AC higher than the primary AC of the TXOP whose initial transmission of the PPDU failed. For example, a data PPDU sent with a best-effort AC can be transmitted using a video AC. Typically, in a WLAN, any BAR uses the AC of its initial transmission as its AC. In this context, it should be noted that the concept of Access Class refers to a mechanism for prioritizing various types of traffic. WLANs distinguish four different ACs: Voice, Video, Best-Effect, and Background. All of these may have different channel access parameters, such as CWmin and / or AIFS.

[0086] For BAR transmissions, the backoff increment for failed transmissions is smaller than for regular data traffic. In a regular WLAN, each failed PPDU transmission results in a doubling of the backoff. This means the range of random CW values ​​doubles, which reduces the probability of small backoff durations. For BAR-only transmissions and associated responses, this behavior can be adapted to a backoff window increment of less than double, such as 1.5 times. After a positive response using BAck, the CW window is reset to its minimum size [0CWmin] for the next data transmission.

[0087] Furthermore, in the variant, different sets of EDCA parameters can be used for BAR transmissions. This means that the AP STA maintains and sets two sets of EDCA parameters: one for regular data transmission and the other only for BAR frames and related responses. These EDCA parameters typically include CWmin, CWmax, AIFS, etc.

[0088] Figure 6 illustrates the operation using BAR access priority and latency gain. Typically, STA 1 is unaware of the cause of the lost BAck response. Therefore, if BAR reveals a PPDUA failure, STA 1 can retransmit the PPDUA in the same TXOP within a short time after the BAck (e.g., a short inter-frame interval, SIFS) without new contention. In this case, the latency gain is smaller but should still be greater than zero. This is a modification to ensure that BAR, BAck, PPDU retransmission, and BAck retransmission achieve a smaller average latency than long contention and retransmission. Therefore, the following relationship holds:

[0089] contTime{BAR}+txTime{BAR}+2·txTime{BAck}+txTime{PPDU A(2 nd TX)}≤contTime{PPDU A(2 nd TX)}+txTime{PPDU A(2 ndTX)}+txTime{BAck}

[0090] It can be simplified to

[0091] contTime{BAR}+txTime{BAR}+txTime{BAck}≤contTime{PPDU A(2 nd TX)}.

[0092] Therefore, the acknowledgment request can be transmitted with a priority equal to or higher than the priority at which the data unit was initially transmitted. Furthermore, the acknowledgment request can be transmitted after a smaller backoff than that applied to perform the retransmission of the data unit. Moreover, the acknowledgment request can be transmitted using transmission parameters, wherein at least one transmission parameter differs from the transmission parameters used to transmit the data unit.

[0093] Therefore, according to the embodiment shown with reference to FIG6, if the first response is not received, the channel access for non-data frames is changed. Specifically, if the first response is not received, an acknowledgment request is transmitted to the second communication device, and a second response from the second communication device in response to the acknowledgment request is monitored. If a second response indicating that no data frames have been received is received, or if no second response is received, one or more data frames are retransmitted.

[0094] A sixth embodiment of the apparatus and method according to this disclosure is shown in FIG7, wherein, Figure 7A A schematic diagram illustrating the standard operation of retransmission while keeping the TXOP duration constant is shown, and Figure 7B A schematic diagram illustrating the shortening of the TXOP duration when a failed PPDU is detected, according to an embodiment of the present disclosure.

[0095] According to this embodiment, an AP STA or STA that becomes aware of a failed PPDU will reduce the maximum duration of the TXOP. This allows STAs transmitting failed PPDUs with potentially high CW values ​​to count down their CW values ​​more quickly, since the TXOP durations of other STAs are shorter. Typically, the AP STA sets the TXOP duration limit, and it is usually aware of the conflict because the AP STA is part of any data exchange within the BSS. Therefore, the AP STA can limit the TXOP duration of its communication once it detects a failed PPDU. Furthermore, the AP STA can set the TXOP duration limit for all STAs via appropriate signaling within the PPDU (e.g., in the preamble) or MAC frame or MAC header (A-control subframe).

[0096] In most cases, it may be meaningful to limit the TXOP duration only for STAs that have not suffered a failed PPDU. The TXOP duration limit can be set inversely to the increase in CW. This means that the maximum TXOP duration is halved each time the CW range doubles. Table 1 shows the intended operation, including saturation after the (M-1)th retransmission.

[0097] PPDU transmission type CW range TXOP duration <![CDATA[1 st Tx(initial Tx)]]> 0, ..., CWmin-1 TXOP <![CDATA[2 nd Tx (first retransmission) 0, ..., 2·CWmin-1 TXOP / 2 <![CDATA[3 rd Tx (Second retransmission) 0, ..., 4·CWmin-1 TXOP / 4 … … … <![CDATA[M th Tx (M-1th retransmission) <![CDATA[0,...2, M-1 ·CWmin-1]]> <![CDATA[TXOP / 2 M-1 ]]> <![CDATA[M+1 th Tx (Mth retransmission) <![CDATA[0,...2, M-1 ·CWmin-1]]> <![CDATA[TXOP / 2 M-1 ]]>

[0098] The benefits in terms of latency are illustrated in Figure 7, which shows three STAs, where STA 2 can be exemplarily an AP STA. Data transmission from STA1 to STA2 encounters a failed PPDU, causing STA1 to draw a long CW. While STA1 is counting down on its CW, STA3 is initiating two long TXOPs, for example, transmitting data to another STA, which causes STA1 to wait a long time before retransmitting its data.

[0099] Figure 7A This illustrates the normal operation with a constant TXOP duration, while Figure 7B The operation of halving the TXOP duration after a failed PPDU, according to an embodiment of this disclosure, is illustrated. Additionally, in Figure 7B In this context, it is assumed that the TXOP of all STAs, except for the STA that suffered the PPDU failure (i.e., STA 1), is shortened.

[0100] Therefore, according to the embodiment shown with reference to FIG7, if no first response is received, the transmission opportunity configuration is changed. Specifically, the failed data transmission of data frames by the communication device or the second communication device is identified by recognizing a lost response after the transmission of one or more data frames during the first transmission opportunity. Then, a shortened transmission opportunity is transmitted to one or more third communication devices to transmit and / or receive signals during the shortened transmission opportunity, and / or the shortened transmission opportunity is configured to exchange data with one or more second and / or third communication devices during the shortened transmission opportunity. Subsequently, one or more data frames are retransmitted to the second communication device or one or more data frames retransmitted from the second communication device are received during one or more second transmission opportunities.

[0101] In another embodiment, STA 1 or STA 2 detects failed data transmission of the PPDU by detecting a lost response following the transmission of one or more data frames within the PPDU during the first TXOP. The shortened TXOP is then configured to exchange data of higher and / or equal and / or lower priority with STA 2 and / or one or more other STAs during the shortened TXOP. Furthermore, when STA 2 retransmits during one or more second TXOPs, one or more data frames within the PPDU are retransmitted to STA 2 or received. Finally, after the retransmission of one or more data frames results in a second response within the second TXOP, the length (duration) of the shortened TXOP is restored (i.e., extended back to the original length). Thus, the TXOP can be further shortened if a lost response is detected after retransmitting one or more data frames to the STA. Each STA has a maximum TXOP duration that it can use. This maximum TXOP duration is defined by the AP and can be set differently for each priority. If a lost response occurs, this length is shortened, for example, by dividing by 2. If another lost response occurs, it may be further shortened, for example, by dividing by 4.

[0102] This embodiment specifies that if STAs have mixed traffic, meaning data frames of different priorities are available, retransmissions can occur earlier. For example, STA 1 transmits a low-latency data frame to STA 2 with high priority, but STA 2's response is lost. This means that STA 1 invokes a random backoff procedure for the high-priority queue, the duration of which may be longer than the backoff time for the low-priority queue. Therefore, the low-priority queue is transmitted earlier, which prevents STA 1 from retransmitting the high-priority data frame because the low-priority data frame was transmitted a long time ago. With the recommendation of TXOP shortening, if the TXOP of the low-priority queue is shortened when a lost response occurs in the high-priority queue, the high-priority queue may be transmitted earlier due to the shortened maximum time of the low-priority data frame on the radio medium. The TXOP of the low-priority queue still prevents the immediate retransmission of the high-priority data frame, but for a shorter time.

[0103] In embodiments using MU PPDU transmission, the operation may proceed as follows: Initially, there is a first group of two or more addressed STAs, each with one or more data frames. A subset of one or more data frames (i.e., at least one subset) may require a response. Another subset of one or more data frames (i.e., at least one additional subset) is acknowledged. If the last subset is empty, the steps disclosed herein are performed, namely, changing the transmission opportunity configuration and / or channel access of non-data frames and / or data frames. If the last subset is not empty, these steps are not performed.

[0104] Figure 8A schematic diagram of the configuration of a communication device 10 according to an embodiment of the present disclosure is shown. Typically, each AP and STA can be configured as follows: Figure 8 The configuration shown may include a data processing unit 11, a wireless communication unit 12, a control unit 13, and a storage unit 14.

[0105] As part of the communication device 10, the data processing unit 11 performs processing on data used for transmission and reception. Specifically, the data processing unit 11 generates frames based on data from the upper layer of the communication device 10 and provides the generated frames to the wireless communication unit 12. For example, the data processing unit 11 generates frames (or data packets, particularly MAC data packets) based on the data and performs processing on the generated frames, such as adding a MAC header for Media Access Control (MAC), adding error detection codes, etc. Furthermore, the data processing unit 11 extracts data from received frames and provides the extracted data to the upper layer of the communication device 10. For example, the data processing unit 11 acquires data by performing MAC header analysis, error detection and correction, and reordering processing on the frames received by MAC.

[0106] In this context, in WLAN terminology, a frame is referred to as a Service Data Unit from higher-layer data, which undergoes further processing such as segmentation, aggregation, and header addition to create a MAC layer frame. Furthermore, in WLAN terminology, a data packet is referred to as a PHY Protocol Data Unit (PPDU). Data packets can also be understood as physical layer data packets.

[0107] The wireless communication unit 12 has signal processing functions and wireless interface functions as part of the communication unit.

[0108] The signal processing function performs signal processing such as frame modulation. Specifically, the wireless communication unit 12 encodes, interleaves, and modulates the frame provided by the data processing unit 11 according to the encoding and modulation scheme set by the control unit 13, adds a preamble and a PHY header, and generates a symbol stream. In addition, the wireless communication unit 12 obtains frames by performing demodulation, decoding, etc., on the symbol stream obtained through the processing via the wireless interface function, and provides the obtained frames to the data processing unit 11 or the control unit 13.

[0109] The wireless interface function is the function of transmitting / receiving signals via one or more antennas. Specifically, the wireless communication unit 12 converts the signal associated with the symbol stream obtained through processing performed by the signal processing function into an analog signal, amplifies the signal, filters the signal, and up-converts the frequency. Next, the wireless communication unit 12 transmits the processed signal through the antenna. In addition, the wireless communication unit 12 performs the opposite processing to the signal transmission processing on the signal obtained through the antenna, such as frequency down-conversion or digital signal conversion.

[0110] As part of the communication unit, the control unit 13 (usually referred to as the station management entity (SME)) controls the overall operation of the communication equipment 10. Specifically, the control unit 13 performs processes such as information exchange between functions, setting communication parameters, or scheduling frames (or packets) within the data processing unit 11.

[0111] Storage unit 14 stores information for processing performed by data processing unit 11 or control unit 13. Specifically, storage unit 14 stores information stored in transmission frames, information obtained from received frames, information about communication parameters, etc.

[0112] In another embodiment, each of the AP and STA can be implemented using... Figure 8 The units shown are configured with circuitry to perform the functions to be executed. This circuitry can be implemented, for example, by a programmed processor. Typically, the functions of the AP and STA, as well as... Figure 8 The units of the communication device 10 shown can be implemented in software, hardware, or a combination of software and hardware.

[0113] Figure 9 A flowchart illustrating a communication method for communication between a first communication device and a second communication device according to an embodiment of this disclosure is shown. In a first step (S10), one or more data frames are transmitted from the first communication device to the second communication device, requesting a response from the second communication device. In a second step (S11), the first communication device listens for and confirms receipt of a first response (e.g., Ack or BAck) from at least one of the one or more data frames from the second communication device. In a third step (S12), if no first response is received, the first communication device changes the transmission opportunity configuration and / or channel access of non-data frames and / or data frames, particularly according to one or more embodiments disclosed herein, before retransmitting one or more data frames (step S13). Otherwise (step S14), the (normal) transmission of data frames continues, or if no further data frames are available, the transmission stops.

[0114] The embodiments presented in this disclosure provide rules for channel access in unlicensed frequency bands to reduce latency in the event of data failure carrying PPDUs. These rules sacrifice throughput to reduce latency. AP STAs can enable these rules to achieve low-latency data transmission within their Basic Service Set (BSS) or cell.

[0115] Therefore, the foregoing discussion merely discloses and describes exemplary embodiments of this disclosure. As those skilled in the art will understand, this disclosure may be practiced in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, this disclosure is intended to be illustrative and not to limit the scope of this disclosure and the other claims. This disclosure, including any readily identifiable variations of the teachings herein, partially defines the scope of the foregoing claims so that no inventive subject matter is offered to the public.

[0116] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "an" or "a" do not exclude a plurality. A single element or other unit can perform the function of several items listed in the claims. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0117] As the embodiments of this disclosure have been described as implementations, at least in part, through a software-controlled data processing apparatus, it should be understood that non-transitory machine-readable media carrying such software, such as optical discs, magnetic disks, semiconductor memories, etc., are also considered representative of embodiments of this disclosure. Furthermore, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0118] The components of the disclosed devices, apparatuses, and systems can be implemented by corresponding hardware and / or software components (e.g., suitable circuits). A circuit is a structural combination of electronic components, including conventional circuit elements, integrated circuits including application-specific integrated circuits (ASICs), standard integrated circuits, application-specific 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. Circuits do not include pure software, although circuits include the aforementioned hardware executing software.

[0119] It follows a list of further embodiments of the disclosed subject matter:

[0120] 1. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0121] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0122] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device, and,

[0123] - If no first response is received, change the transport opportunity configuration and / or channel access for non-data frames and / or data frames.

[0124] 2. The communication device as defined in Example 1,

[0125] The circuit is configured as follows:

[0126] If no first response is received, an acknowledgment request is transmitted to the second communication device.

[0127] - Listen for a second response to the response confirmation request from the second communication device, and

[0128] - If the received second response indicates that no data frame has been received, or if no second response is received, then retransmit the one or more data frames.

[0129] 3. The communication device as defined in Example 2,

[0130] The circuit is configured to transmit an acknowledgment request with a channel access priority higher than that of the first data frame in one or more initially transmitted data frames.

[0131] 4. The communication device as defined in Embodiment 2 or 3,

[0132] The circuit is configured to transmit the acknowledgment request after a channel access backoff less than the channel access backoff applied for retransmission of one or more data frames.

[0133] 5. The communication device as defined in any one of Embodiments 2 to 4,

[0134] The circuit is configured to retransmit the one or more data frames during the same transmission opportunity in which the acknowledgment request is transmitted.

[0135] 6. The communication device as defined in any one of Embodiments 2 to 5,

[0136] The circuit is configured to transmit an acknowledgment request with channel access parameters, wherein at least one channel access parameter is different from the channel access parameters used for transmitting and / or retransmitting one or more data frames.

[0137] 7. The communication device as defined in any of the foregoing embodiments,

[0138] The circuit is configured as follows:

[0139] - Configuration: If no first response is received, the next transmission opportunity obtained by the communication device will only include:

[0140] i) retransmit one or more data frames to the second communication device, and receive a second response from the second communication device acknowledging receipt of the retransmitted one or more data frames, and / or,

[0141] ii) Transmitting one or more data frames to the second communication device, the one or more data frames having the same priority as and / or a higher priority than the one or more previously transmitted data frames or the one or more data frames to be retransmitted, and / or,

[0142] iii) If a second response is received, a notification instructing the communication device not to transmit any more data frames in the same transmission opportunity.

[0143] 8. The communication device as defined in Example 7,

[0144] The notification further instructs the second communication device to use the current transmission opportunity for data transmission.

[0145] 9. The communication device as defined in Embodiment 7 or 8,

[0146] The circuit is configured to transmit a contention-free end frame as a notification.

[0147] 10. The communication device as defined in any of the foregoing embodiments,

[0148] The circuit is configured as follows:

[0149] - Transmit the one or more data frames to the second communication device on the first link.

[0150] - Listen for a first response confirming receipt of the one or more data frames from the second communication device on the first link.

[0151] - If no first response is received, channel access is switched to a second link to retransmit the one or more data frames to the second communication device on the second link with a second target beacon transmission time or without beacon transmission, the second target beacon transmission time being later than the first target beacon transmission time of the first link, and beacon frames are transmitted on the first link after the first target beacon transmission time has elapsed.

[0152] 11. The communication device as defined in any of the foregoing embodiments,

[0153] The circuit is configured to retransmit the one or more data frames to the second communication device if no first response is received, and to change the channel access of the beacon frame compared to the regular transmission of the beacon frame, wherein the beacon frame has a predetermined length and is transmitted after the target beacon transmission time with a predetermined modulation and / or coding scheme.

[0154] 12. The communication device as defined in Example 11,

[0155] The circuit is configured to change channel access to delay the transmission of beacon frames and to retransmit one or more data frames before transmitting the beacon frames.

[0156] 13. The communication device as defined in Embodiment 11 or 12,

[0157] The circuit is configured to transmit shortened beacon frames shorter than a predetermined length and to retransmit data units after transmitting the shortened beacon frames.

[0158] 14. The communication device as defined in any one of Embodiments 11 to 13,

[0159] The circuit is configured to transmit the beacon frame using a modulation and / or coding scheme different from the predetermined modulation and coding scheme, and to retransmit the one or more data frames after transmitting the beacon frame.

[0160] 15. The communication device as defined in Example 14,

[0161] The circuit is configured to select the modulation and / or encoding such that all second communication devices associated with the communication device are able to receive and / or decode the beacon frame.

[0162] 16. The communication device as defined in any of the foregoing embodiments,

[0163] The circuit is configured to retransmit one or more data frames to the second communication device without contention after a beacon frame has been transmitted.

[0164] 17. The communication device as defined in Example 16,

[0165] The contention-free interval between the transmission of a beacon frame and the retransmission of one or more data frames is published in the beacon.

[0166] 18. The communication device as defined in any of the foregoing embodiments,

[0167] The circuit is configured to partially retransmit the one or more data frames and to retransmit one or more data frames that are different from the transmission parameters used for the initial transmission of the one or more data frames, wherein the transmission parameters used for retransmitting the portions of the one or more data frames are the same.

[0168] 19. The communication device as defined in any of the foregoing embodiments,

[0169] The circuit is configured as follows:

[0170] - Retransmit the first portion of the one or more data frames.

[0171] -A second response confirming receipt of the first portion of the transmitted one or more data frames from the second communication device.

[0172] - If a second response is received, one or more additional portions of the one or more data frames are retransmitted, the one or more additional portions of the one or more data frames using one or more transmission parameters different from the transmission parameters used for the initial transmission of the one or more data frames.

[0173] 20. The communication device as defined in Embodiment 18 or 19,

[0174] The transmission parameters used for retransmitting one or more data frames are different from the transmission parameters used for the initial transmission of one or more data frames, while the transmission parameters used for retransmitting one or more data frames are the same.

[0175] 21. The communication device as defined in any one of Examples 18 to 20,

[0176] One or more distinct transmission parameters include one or more transmission parameters in a transmission parameter group, which includes modulation and / or coding schemes, transmission bandwidth, spatial stream number, transmission method, and data frame type.

[0177] 22. The communication device as defined in any of the foregoing embodiments,

[0178] The circuit is configured as follows:

[0179] - By identifying a lost response after the transmission of one or more data frames during the first transmission opportunity, the failed data transmission of data frames by the communication device or the second communication device can be identified.

[0180] - To transmit a signal for a shortened transmission opportunity to one or more third communication devices for transmission and / or reception during the shortened transmission opportunity, and / or to configure the shortened transmission opportunity for exchanging data with one or more second and / or third communication devices during the shortened transmission opportunity, and

[0181] - Retransmit the one or more data frames to the second communication device or receive the one or more data frames retransmitted from the second communication device during one or more second transmission opportunities.

[0182] 23. The communication device as defined in any of the foregoing embodiments,

[0183] The circuit is configured to receive instructions from a second or third communication device, indicating whether and / or how to change the transmission opportunity configuration and / or channel access if a first response is not received.

[0184] 24. The communication device as defined in any of the foregoing embodiments,

[0185] The circuit is configured as follows:

[0186] - Transmit the one or more data frames to two or more second communication devices, wherein at least one of the one or more data frames requests a response.

[0187] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the two or more second communication devices, and

[0188] - If no first response is received from the two or more second communication devices, the transmission opportunity configuration and / or channel access for non-data frames and / or data frames are changed.

[0189] 25. The communication device as defined in any of the foregoing embodiments,

[0190] The circuit is configured as follows:

[0191] - Monitor a channel for a predetermined backoff time, and check if the channel is detected to be idle at the end of the predetermined backoff time.

[0192] If the channel is detected as non-idle, the time span prior to the detection of the non-idle channel is subtracted from the predetermined backoff time, and the system waits until idleness is detected again.

[0193] 26. The communication device as defined in any of the foregoing embodiments,

[0194] The circuit is configured to change the transmission opportunity configuration and / or channel access for non-data frames and / or data frames if no first response is received, until at least one of one or more data frames has been successfully retransmitted or a timeout has been reached.

[0195] 27. A communication method for a communication device to communicate with a second communication device, the communication method comprising:

[0196] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0197] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device, and,

[0198] - If no first response is received, change the transport opportunity configuration and / or channel access for non-data frames and / or data frames.

[0199] 28. A non-transitory computer-readable recording medium storing the computer program product, which, when executed by a processor, causes the method according to embodiment 27 to be performed.

[0200] 29. A computer program, including program code, which, when executed on a computer, causes the computer to perform the steps of the method according to embodiment 27.

[0201] 30. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0202] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0203] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device.

[0204] If no first response is received, an acknowledgment request is transmitted to the second communication device.

[0205] - Listen for a second response to the response confirmation request from the second communication device, and

[0206] - If the received second response indicates that no data frame has been received, or if no second response is received, then retransmit the one or more data frames.

[0207] 31. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0208] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0209] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device.

[0210] - Configuration: If no first response is received, the next transmission opportunity obtained by the communication device will only include:

[0211] i) retransmit one or more data frames to the second communication device, and receive a second response from the second communication device acknowledging receipt of the retransmitted one or more data frames, and / or,

[0212] ii) If a second response is received, a notification instructing the communication device not to transmit any more data frames in the same transmission opportunity.

[0213] 32. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0214] - Transmit the one or more data frames to the second communication device on the first link.

[0215] - Listen for a first response confirming receipt of the one or more data frames from the second communication device on the first link.

[0216] - If no first response is received, channel access is switched to a second link to retransmit the one or more data frames to the second communication device on the second link, which has a second target beacon transmission time or no beacon transmission time, the second target beacon transmission time being later than the first target beacon transmission time of the first link, and beacon frames are transmitted on the first link after the first target beacon transmission time has elapsed.

[0217] 33. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0218] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0219] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device, and,

[0220] - If the first response is not received, one or more data frames are retransmitted to the second communication device and the channel access of the beacon frame is changed compared with the regular transmission of the beacon frame, wherein the beacon frame has a predetermined length and is transmitted after the target beacon transmission time with a predetermined modulation and / or coding scheme.

[0221] 34. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0222] - Transmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0223] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device, and,

[0224] If no first response is received, the one or more data frames are partially retransmitted, and the one or more data frames are retransmitted using one or more transmission parameters that are different from the transmission parameters used for the initial transmission of the one or more data frames, wherein the transmission parameters used for the portion of the one or more data frames to be retransmitted are the same.

[0225] 35. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0226] - Retransmit one or more data frames to the second communication device, requesting a response from the second communication device.

[0227] - Listen for a first response confirming receipt of at least one data frame from the one or more data frames from the second communication device, and,

[0228] - If no first response is received, retransmit the first portion of the one or more data frames.

[0229] -A second response confirming receipt of the first portion of the transmission of the one or more data frames from the second communication device.

[0230] - If a second response is received, one or more additional portions of the one or more data frames use one or more transmission parameters that are different from the transmission parameters used for the initial transmission of the one or more data frames.

[0231] 36. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to:

[0232] - By identifying a lost response after the transmission of one or more data frames during the first transmission opportunity, the failed data transmission of data frames by the communication device or the second communication device can be identified.

[0233] - To transmit a signal for a shortened transmission opportunity to one or more third communication devices for transmission and / or reception during the shortened transmission opportunity, and / or to configure the shortened transmission opportunity for exchanging data with one or more second and / or third communication devices during the shortened transmission opportunity, and

[0234] - Retransmit the one or more data frames to the second communication device or receive the one or more data frames retransmitted from the second communication device during one or more second transmission opportunities.

[0235] 37. The communication device as defined in any one of Embodiments 1 to 26,

[0236] The circuit is configured as follows:

[0237] - By detecting a loss response after the transmission of one or more data frames during the first transmission opportunity, the communication device or the second communication device detects failed data transmission of data frames.

[0238] - Configure shortened transmission opportunities, preferably for lower-priority data transmission, to exchange higher and / or equal and / or lower-priority data with one or more second and / or third communication devices during said shortened transmission opportunity.

[0239] - During one or more second transmission opportunities, retransmit the one or more data frames to the second communication device, or receive the one or more data frames retransmitted by the second communication device, and

[0240] - The length of the transmission opportunity restored after the retransmission of the one or more data frames, causing a second response within the second transmission opportunity, and / or further shortening the shortened transmission opportunity if a lost response is detected after the retransmission of the one or more data frames to the second communication device.

Claims

1. A communication device configured to communicate with a second communication device, the communication device including circuitry configured to: - Transmit one or more data frames to the second communication device, requesting a response from the second communication device. - Listening to confirm the receipt of at least one data frame from the one or more data frames from the second communication device in a first response, and, - If no first response is received, change the transport opportunity configuration and / or channel access for non-data frames and / or data frames. in, The changes include at least one of the following: a) Adjust one or more transmission parameters used for retransmitting the one or more data frames, including one or more of the modulation and / or coding scheme, transmission bandwidth, number of spatial streams, transmission method, and data frame type; b) Configure transmission opportunities, which include transmitting one or more data frames with the same or higher priority as the one or more data frames being transmitted; c) Delay or shorten the transmission of beacon frames; d) Select different communication links with a later or non-existent target beacon transmission time for retransmission; e) Change the access parameters used for the acknowledgment request frame, including using a higher access class, a shorter backoff, or different Enhanced Distributed Channel Access (EDCA) parameters, or f) Reduce the maximum transmission opportunity duration of one or more communication devices.

2. The communication device according to claim 1, in, The circuit is configured to - If no first response is received, an acknowledgment request is transmitted to the second communication device. - Listen for a second response from the second communication device to the confirmation request, and - If the received second response indicates that no data frame has been received, or if no second response is received, then retransmit the one or more data frames.

3. The communication device according to claim 2, in, The circuit is configured to transmit the acknowledgment request with a higher channel access priority than the channel access priority of the first data frame in the one or more data frames initially transmitted and / or with channel access parameters, wherein at least one channel access parameter is different from the channel access parameters used for transmitting and / or retransmitting the one or more data frames.

4. The communication device according to claim 2, in, The circuit is configured to transmit the acknowledgment request after a channel access backoff less than the channel access backoff applied for retransmission of one or more data frames.

5. The communication device according to claim 2, in, The circuit is configured to retransmit the one or more data frames during the same transmission opportunity in which the acknowledgment request is transmitted.

6. The communication device according to claim 1, in, The circuit is configured to - Configuration: If no first response is received, the next transmission opportunity obtained by the communication device includes only: i) retransmit one or more data frames to the second communication device, and receive a second response from the second communication device acknowledging receipt of the retransmitted one or more data frames, and / or, ii) Transmitting one or more data frames to the second communication device, the one or more data frames having the same priority as one or more previously transmitted data frames or one or more data frames to be retransmitted and / or having a higher priority than one or more previously transmitted data frames or one or more data frames to be retransmitted, and / or, iii) If a second response is received, a notification instructing the communication device not to transmit any more data frames in the same transmission opportunity.

7. The communication device according to claim 6, in, The notification further instructs the second communication device or another communication device to use the current transmission opportunity to transmit data.

8. The communication device according to claim 1, in, The circuit is configured to - Transmit the one or more data frames to the second communication device on the first link. - Listen for a first response confirming receipt of the one or more data frames from the second communication device on the first link. - If no first response is received, channel access is switched to a second link to retransmit the one or more data frames to the second communication device on the second link with a second target beacon transmission time or without beacon transmission, the second target beacon transmission time being later than the first target beacon transmission time of the first link, and beacon frames are transmitted on the first link after the first target beacon transmission time has elapsed.

9. The communication device according to claim 1, in, The circuit is configured to retransmit the one or more data frames to the second communication device if no first response is received, and to change the channel access of the beacon frame compared to the regular transmission of the beacon frame, wherein the beacon frame has a predetermined length and is transmitted after the target beacon transmission time with a predetermined modulation and / or coding scheme.

10. The communication device according to claim 9, in, The circuit is configured to change channel access to delay the transmission of the beacon frame, and retransmit the one or more data frames before transmitting the beacon frame, and / or transmit a shortened beacon frame with a length shorter than the predetermined length, and retransmit data units after transmitting the shortened beacon frame.

11. The communication device according to claim 9, in, The circuit is configured to transmit the beacon frame using a modulation and / or coding scheme different from the predetermined modulation and coding scheme, and to retransmit the one or more data frames after transmitting the beacon frame. The circuit is configured to select the modulation and / or encoding such that all second communication devices associated with the communication device are able to receive and / or decode the beacon frame.

12. The communication device according to claim 1, in, The circuit is configured to partially retransmit the one or more data frames and to retransmit one or more data frames using one or more transmission parameters that are different from the transmission parameters used for the initial transmission of the one or more data frames, wherein the transmission parameters used for retransmitting the portions of the one or more data frames are the same.

13. The communication device according to claim 1, in, The circuit is configured to - Retransmit the first portion of the one or more data frames. - Listen for a second response confirming receipt of the first portion of the transmitted one or more data frames from the second communication device. - If a second response is received, one or more additional portions of the one or more data frames are retransmitted, the one or more additional portions of the one or more data frames using one or more transmission parameters different from the transmission parameters used for the initial transmission of the one or more data frames.

14. The communication device according to claim 12, in, One or more transmission parameters used for retransmitting the one or more data frames are different from the transmission parameters used for the initial transmission of the one or more data frames, wherein the transmission parameters used for retransmitting a portion of the one or more data frames are the same, and / or wherein the one or more different transmission parameters include one or more transmission parameters in a transmission parameter group, the transmission parameter group including modulation and / or coding scheme, transmission bandwidth, spatial stream number, transmission method, and data frame type.

15. The communication device according to claim 1, wherein, The circuit is configured to - By identifying a lost response following the transmission of one or more data frames during the first transmission opportunity, the failed data transmission of data frames by the communication device or the second communication device can be identified. - To transmit a signal for a shortened transmission opportunity to one or more third communication devices for transmission and / or reception during the shortened transmission opportunity, and / or to configure the shortened transmission opportunity for exchanging data with one or more second and / or third communication devices during the shortened transmission opportunity, and - Retransmit the one or more data frames to the second communication device or receive the one or more data frames retransmitted from the second communication device during one or more second transmission opportunities.

16. The communication device according to claim 1, in, The circuit is configured to - By detecting a loss response after the transmission of one or more data frames during the first transmission opportunity, the communication device or the second communication device detects failed data transmission of data frames. - Configure shortened transmission opportunities for lower-priority data transmission, during which higher and / or equal and / or lower-priority data can be exchanged with one or more second and / or third communication devices. - During one or more second transmission opportunities, retransmit the one or more data frames to the second communication device, or receive the one or more data frames retransmitted by the second communication device, and - Restore the transmission opportunity length after retransmitting the one or more data frames, induce a second response within the second transmission opportunity, and / or further shorten the shortened transmission opportunity if a lost response is detected after retransmitting the one or more data frames to the second communication device.

17. The communication device according to claim 1, in, The circuit is configured to - Transmit the one or more data frames to two or more second communication devices, wherein at least one of the one or more data frames requests a response. - A first response confirming receipt of at least one data frame from the one or more data frames received from the two or more second communication devices, and - If no first response is received from the two or more second communication devices, the transmission opportunity configuration and / or channel access for non-data frames and / or data frames are changed.

18. The communication device according to claim 1, in, The circuit is configured to - Monitor a channel for a predetermined backoff time, check if the channel is detected to be idle at the end of the predetermined backoff time, and, If the channel is detected as non-idle, the time span prior to the detection of the non-idle channel is subtracted from the predetermined backoff time, and the system waits until idleness is detected again.

19. A communication method for a communication device to communicate with a second communication device, the communication method comprising: - Transmit one or more data frames to the second communication device, requesting a response from the second communication device. - Listening to confirm the receipt of at least one data frame from the one or more data frames from the second communication device in a first response, and, - If no first response is received, change the transport opportunity configuration and / or channel access for non-data frames and / or data frames. The changes include at least one of the following: a) Adjust one or more transmission parameters used for retransmitting the one or more data frames, including one or more of the modulation and / or coding scheme, transmission bandwidth, number of spatial streams, transmission method, and data frame type; b) Configure transmission opportunities, which include transmitting one or more data frames with the same or higher priority as the one or more data frames being transmitted; c) Delay or shorten the transmission of beacon frames; d) Select different communication links with a later or non-existent target beacon transmission time for retransmission; e) Change the access parameters used for the acknowledgment request frame, including using a higher access class, a shorter backoff, or different Enhanced Distributed Channel Access (EDCA) parameters, or f) Reduce the maximum transmission opportunity duration of one or more communication devices.

20. A non-transitory computer-readable recording medium storing a computer program product that, when executed by a processor, causes to perform the method according to claim 19.

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