COMMUNICATIONS DEVICE AND METHODS

Abstract

A communications device configured to communicate with a second communications device, the communications device comprising: circuitry configured to transmit to the second communications device one or more data frames requiring a response by the second communications device; wait for a first response from the second communications device confirming receipt of at least one of the one or more data frames; and change a transmission opportunity configuration and / or channel access for data frames and / or non-data frames if the first response is not received.

Description

[Technical Field]

[0001] The present disclosure relates to communication devices and methods, particularly to low latency communication in wireless LANs (WLANs). [Background technology]

[0002] Because WLANs operate in an unlicensed spectrum shared by communication devices, transmitted data units, such as Physical Layer Adaptation Procedure (PLCP) Protocol Data Units (PPDUs), may be undecodable, i.e., dropped, due to interference from another simultaneously transmitting communication device, another network, or another wireless device.

[0003] If the entire PPDU is not decodable, i.e., there is a corrupted PPDU, this has a significant impact on latency according to current channel access rules in WLANs. Communication devices, especially base stations (STAs), will extend (often double) their contention window in this case. In a busy network, this can cause a communication device to wait a long time before it can access the channel again and potentially deliver the data that was meant to be delivered in the failed PPDU.

[0004] The "Background" discussion provided herein is intended to provide a general background to the present disclosure. The works of the inventors named herein are not expressly or impliedly admitted as prior art to the present disclosure to the extent described in this Background section or in aspects of the specification that were not prior art at the time of filing. Summary of the Invention

[0005] The present invention aims to provide an enhanced channel access principle for WLANs that improves latency, as well as a corresponding communication device and method, and a corresponding computer program and a non-transitory computer-readable storage medium for implementing said method.

[0006] According to one aspect, a communication device configured to communicate with a second communication device, comprising: transmitting to the second communications device one or more data frames requiring a response by the second communications device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames. The circuit is configured as follows: A communication device is provided.

[0007] According to yet another aspect, a communication method of a communication device for communicating with a second communication device, comprising: transmitting to the second communications device one or more data frames requiring a response by the second communications device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; if the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames; include A method is provided.

[0008] According to yet another aspect, a computer program comprising program means for causing a computer to perform the steps of the methods disclosed herein; A non-transitory computer-readable recording medium is provided that is stored in a computer program product, the computer program causing a processor to execute the methods disclosed herein when executed.

[0009] The disclosed communication method, the disclosed computer program, and the disclosed computer-readable recording medium have further embodiments similar to and / or identical to the claimed communication device, which are defined in the dependent claims described and / or disclosed herein.

[0010] One aspect of the present disclosure is to limit the increase in latency due to failed PPDUs through the use of one or more rules added to the existing channel access mechanism, each rule being applied alone or in combination with other rules.

[0011] This disclosure proposes an enhanced channel access principle for wireless LANs that improves latency. More specifically, several independent rules are defined that result in timely and fast retransmission of a physical protocol data unit (PPDU; also referred to herein as a data PPDU) after an initial transmission fails. Corrupted PPDUs can occur due to interference or due to collisions, i.e., simultaneous transmissions, of two or more stations (STAs). Thus, the proposed rule is suitable for distributed channel access where collisions appear frequently. Furthermore, we propose that AP STAs may enable and require these rules for associated STAs to achieve a basic service set (BSS) with low latency services.

[0012] Thus, according to an embodiment of the present disclosure, if a first acknowledgment is not received, measures are taken to reduce the amount of time that a communications device waits before successfully retransmitting a data unit and / or the amount of time that a second communications device or other communications device waits before transmitting a data unit.

[0013] Throughout this disclosure, access points are referred to as AP STAs and base stations are referred to as non-AP STAs. The term STA is used interchangeably for non-AP STAs or AP STAs, i.e., it applies to both types of STAs.

[0014] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the claims which follow. The described embodiments, together with further advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0015] A more complete understanding of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. [Figure 1] 1A shows a schematic diagram illustrating a conventional successful frame exchange between two STAs; and FIG. 1B shows a schematic diagram illustrating conventional operation when a peer STA fails to receive the first transmitted data unit. [Figure 2] 1A and 1B are schematic diagrams illustrating conventional retransmission without excluding rate sounding and retransmission with excluding rate sounding according to an embodiment of the present disclosure, respectively. [Figure 3] 1A and 1B are schematic diagrams illustrating a conventional retransmission operation in which new data can be sent in a transmission opportunity that holds retransmitted data, respectively, and illustrating the exclusion of new data in a transmission opportunity that holds retransmitted data, according to one embodiment of the present disclosure. [Figure 4AB] 1A and 1B are schematic diagrams illustrating conventional collision resolution with normal beaconing behavior and / or length, respectively, and collision resolution with beaconing delay, according to one embodiment of the present disclosure. [Figure 4CD] Figure 4C is the same as Figure 4A. Figure 4D shows a schematic diagram illustrating collision resolution with reduced beacon length according to one embodiment of the present disclosure. [Figure 4EF]Fig. 4E is the same as Fig. 4A. Fig. 4F is a schematic diagram illustrating collision resolution involving retransmission of contention-free data frames immediately after a beacon transmission according to one embodiment of the present disclosure. [Figure 5] 1A and 1B are schematic diagrams illustrating conventional operations in a multi-link setup method and collision resolution with link selection for retransmission in a multi-link setup method according to an embodiment of the present disclosure, respectively; [Figure 6] 1A and 1B are schematic diagrams illustrating conventional operations for retransmission and collision resolution with access prioritization of block acknowledgement requests, respectively, according to one embodiment of the present disclosure; [Figure 7] 1A and 1B are schematic diagrams illustrating conventional operation for retransmission with unchanged TXOP duration and shortening of TXOP duration according to an embodiment of the present disclosure, respectively. [Figure 8] 1 is a schematic diagram illustrating a configuration of a communication device 30 according to an embodiment of the present disclosure. [Figure 9] 1 shows a flowchart of one embodiment of a communication method according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] In general, this disclosure considers the case where a STA transmits one or more data units (referred to below as, but not limited to, a PPDU) within a transmit opportunity (TXOP). One or more of these PPDUs were not decodable, i.e., there were one or more failed PPDUs. This is detected due to a missing response (e.g., Ack, BAck) from the peer STA. In this context, a missing response may be the only condition necessary for detecting a failed data PPDU, since a missing response may also occur if the response PPDU fails.

[0017] If a missed response occurs within a TXOP (but not initially), the channel is considered to be detected as busy at the transmitter or TXOP initiator. In these two cases, i.e., a missed response at the start of the TXOP, or a missed response resulting in a busy channel within the TXOP, the transmitting STA shall stop transmitting and back off. In this context, the start of a TXOP is understood to be the first response to one or more PPDUs within that TXOP, while the inside of a TXOP is understood to be a non-first response to one or more PPDUs within that TXOP.

[0018] Referring now to the drawings, like reference numerals designate identical or corresponding parts throughout the several views. FIG. 1A shows a schematic diagram illustrating a conventional successful frame exchange between two STAs. STA 1 performs contention by waiting (listening) on ​​the channel for a specific time span given by the offset (AIFS) and a predefined multiple of the slot time. The multiple of the slot time is determined by the contention window (CW) value, which is initially drawn from a random uniform distribution from [0...CWmin-1] when a STA has data available to transmit.

[0019] Typically, the CW value is decremented by one after each slot time interval, and the channel becomes idle. When the CW value reaches zero and the channel becomes idle, STA 1 acquires a TXOP and transmits one or more PPDUs containing the peer STA's potential response (Block Acknowledgement (BAck) in Figure 1A). The TXOP ends when STA 1 has no more data to send or the maximum TXOP time has elapsed. Once the TXOP is finished, the STA will again go through the contention process described above to gain channel access.

[0020] FIG. 1B shows a schematic diagram illustrating conventional behavior when a peer STA, STA 2, is unable to receive the originally transmitted PPDU, for example due to interference. In this case, STA 2 does not send a response frame (i.e., an acknowledgment, also referred to here as "first acknowledgment" or "initial response") after the end of PPDU A transmitted by STA 1. STA 1 detects the lack of response after a certain timeout, stops transmitting, and terminates the associated TXOP. To access the channel again, STA 1 draws a new CW value from a uniform distribution with an increasing range from [0...2·CWmin - 1], i.e., a long contention time is likely.

[0021] Each time a particular PPDU is detected as undecodable or lost, the range of the uniform distribution of the CW is typically doubled again. Transmissions by other STAs are likely to interrupt the CW countdown, causing the CW to rise. This can cause significant latency not only because of the long contention time, but also because of the duration of other transmissions occurring before STA 1 can transmit again.

[0022] A PPDU may carry a MAC Protocol Data Unit (MPDU) or an Aggregated MPDU (A-MPDU) containing one or more MPDUs in an aggregation. Each MPDU carries MAC header information, the user data to be transmitted, and a check sequence to detect the integrity of that MPDU. A PPDU cannot be decoded or fails if the sender of the PPDU observes the following: Each MPDU contained in that PPDU is not complete, i.e., the check sequence is incorrect (this includes, for example, the case of a BAck response indicating that all MPDUs were incorrect), or an expected response frame from the peer STA is not received.

[0023] It should be noted that three different types of frames are generally distinguished: Data frames (frames that carry data such as content, user data, and communication data), control frames (eg, Ack, BAck, Ack Request, BAck Request), and management frames (eg, beacon frames).

[0024] A concept is presented for the following STA behavior after the occurrence of an undecodable or failed PPDU, i.e., for retransmission of data, i.e., for MPDUs or A-MPDUs present in the failed PPDU. The following embodiments describe rules or add-ons that augment existing rules and their application, which may be subject to AP STA decisions for all non-AP STAs or a specific set of non-AP STAs. Each rule or add-on can be applied alone or in combination with other rules. The more STAs implement a rule, the more useful it becomes. This can be important in the context of legacy STAs, since they are unaware of these rules. Therefore, for mitigation purposes, two options can be envisaged:

[0025] According to the first option, an AP STA may restrict admission to its BSS (Basic Service Set) according to one or more non-AP STA applications of these rules or add-ons. Therefore, AP STAs may create a BSS optimized for latency-sensitive data traffic. The second option provides benefits to non-AP STAs that implement one or more of the following procedures regarding Enhanced Distributed Channel Access (EDCA) parameters: This is because STAs that do not implement one or more of the following procedures may have a throughput advantage but a latency disadvantage, which may be equalized by slightly modifying the access parameters.

[0026] A first embodiment of the apparatus and method according to the present disclosure is shown in FIG. Here, FIG. 2A is a schematic diagram illustrating conventional retransmission without excluding rate tones, and FIG. 2B is a schematic diagram illustrating retransmission without rate tones according to an embodiment of the present disclosure.

[0027] According to this embodiment, after a PPDU transmission fails, the STA modifies the transmission behavior of the next PPDU by changing one or more of the following transmission parameters compared to the failed PPDU: Modulation and Coding Scheme (MCS) Transmission bandwidth Number of spatial streams Transmission method (STBC or DCM) PPDU type (SU-PPDU or MU-PPDU).

[0028] These transmission parameters affect the length of the PPDU and the number of MPDUs that can fit into it. Therefore, retransmission of a failed MPDU may require multiple PPDUs. It is up to the STA to apply the transmission parameters. However, if a STA decides to change its transmission parameters, - The first PPDU containing the retransmitted MPDU fails, or - all PPDUs containing retransmitted data units are successful, or - Other transmission parameters are known that achieve a higher ratio of failed MPDUs after the first successful PPDU. The same parameters shall be applied to all PPDUs, including retransmitted MPDUs, until the "Known" here means that the STA has recently looked at these transmission parameters.

[0029] The rules applied according to this embodiment try to avoid checking the transmission parameters of the PPDU containing the retransmitted MPDU, where such checking is done by trial and error, i.e. the PPDU is transmitted using the checked transmission parameters. The response of the peer STA allows a conclusion regarding the quality of these transmission parameters. If the quality is unknown in advance, the STA may tolerate the loss of PPDUs, which is undesirable since PPDUs containing retransmitted MPDUs will cause further retransmissions and latency.

[0030] Figure 2 shows the difference in behavior without this rule (Figure 2A) and with the rule (Figure 2B). This rule does not allow the transmission of the second part of PPDU A with an unknown transmission parameter set C, thus avoiding another retransmission and thereby reducing latency.

[0031] As shown in FIG. 2B, after STA 1 transmits a data unit (PPDU A) to STA 2, STA 1 waits for a first acknowledgement (such as an Ack or BAck) from STA 2 of receipt of the data unit. If the initial acknowledgment is not received, measures are taken to reduce the amount of time a communication device must wait before successfully retransmitting a data unit, in which one or more transmission parameters used to retransmit the data (Tx parameter set B) differ from the transmission parameters used to initially transmit the data unit (Tx parameter set A).

[0032] In a variation, the transmission parameters for retransmitting all portions of the data unit are the same. In another variation, after the first portion of the data unit is retransmitted, STA 1 again waits for a second acknowledgment (also referred to herein as a "second response") from STA 2. If the second acknowledgment is received by STA 1, one or more subsequent portions (e.g., second portions) of the data unit are retransmitted using one or more transmission parameters that differ from the transmission parameters used to initially transmit the data unit. If STA 1 does not receive the second acknowledgment, the next portion of the data unit is transmitted with new transmission parameters (e.g., Tx parameter set C). The one or more different transmission parameters include one or more transmission parameters of a group of transmission parameters including a modulation and coding scheme, a transmission bandwidth, a number of spatial streams, a transmission method, and a type of data unit.

[0033] Thus, according to the embodiment illustrated by means of Fig. 2, if no first response is received, the transmission parameters for the transmission of the data frames are modified, in particular one or more data frames are partially retransmitted. One or more transmission parameters for retransmitting the one or more data frames are different from the transmission parameters used to initially transmit the one or more data frames, and the transmission parameters for retransmitting portions of the one or more data frames are the same.

[0034] A second embodiment of a device and method according to the present disclosure is shown in FIG. 3, where FIG. 3A shows a schematic diagram illustrating conventional operation of a retransmission operation and FIG. 3B shows a schematic diagram illustrating the elimination of new data in a transmission opportunity to preserve retransmission data according to an embodiment of the present disclosure.

[0035] After a PPDU transmission failure, a TXOP containing one or more PPDUs with retransmitted MPDUs contains the MPDUs transmitted in the failed PPDU or less. Furthermore, the MPDUs are transmitted in the same order as the failed PPDU. If the retransmitted MPDUs do not fit within one PPDU, several PPDUs are transmitted within the same or a new TXOP. This may occur due to a change in the temporal PPDU length constraint and / or transmission parameters. For example, the first transmission fully utilized the temporal PPDU length constraint. For the second transmission (retransmission), the modulation and coding scheme was set to a lower value, i.e., a lower code rate and / or modulation order. Therefore, the MPDU takes more time to transmit and a second PPDU is needed to carry the remaining MPDU that did not fit into the first retransmitted PPDU.

[0036] According to this embodiment, either after each transmitted PPDU or after the most recent PPDU containing the last part of a retransmitted MPDU has been transmitted, the STA requests an Ack or BAck indicating the reception status of the retransmitted MPDU. If an Ack or BAck is received and all retransmitted MPDUs are successfully received, the STA sends a termination notification to other STAs indicating the end of the current TXOP, e.g., a frame formation, in particular a contention-free (CF) end frame, indicating the end of a period during which the STAs cannot contend.

[0037] FIG. 3 illustrates a scenario in which STA 1 and STA 2 want to send data to STA 3. Because STA 1 and STA 2 get the same channel access, their PPDUs collide and the response of STA 3 is missing, which is detected by STA 1 and STA 2. Figure 3A shows normal operation in this situation. After STA 1 accesses the channel again, it first retransmits PPDU A, then retransmits another PPDU B containing new data, thereby utilizing the TXOP time, allowing STA 2 to deliver PPDU C, which is subsequently retransmitted. In contrast, Figure 3B shows the behavior when STA 1 terminates its TXOP after retransmitting PPDU A. Preferably, this is after receiving a second acknowledgment of receipt of the retransmitted data unit from STA 2. STA 2 may therefore have an earlier opportunity to access the channel to retransmit PPDU C. Comparing Figures 3A and 3B reveals the latency gain for the STA that retransmits later, i.e., STA 2 in this example.

[0038] In another embodiment, after transmitting PPDU A to STA 2 and missing a response, STA 1 may, for example, additionally or in addition to retransmitting PPDU A, transmit a new PPDU B having the same or higher priority as the previously transmitted PPDU A. This provides the advantage that any new data frames that arrive while STA 1 is competing for channel access to the retransmitted PPDU A will be immediately transmitted together with the retransmission of PPDU A. This helps to reduce the transmission latency of new data frames, as further competition for channel access is avoided.

[0039] In normal WLAN operation, beacon frames may be transmitted to announce the presence of the network, which can introduce latency if retransmissions are delayed. Thus, under the rules used in accordance with various embodiments of the present disclosure, if an AP STA transmits a failed PPDU, it may take one of several measures, as described with reference to Figures 4 and 5.

[0040] A third embodiment of the device and method according to the present disclosure is shown in FIG. Here, Figures 4A, 4C, and 4E (all identical) show schematic diagrams illustrating conventional collision resolution with normal beacon length, Figure 4B shows schematic diagrams illustrating collision resolution with beacon delay according to an embodiment of the present disclosure, Figure 4D shows schematic diagrams illustrating collision resolution with reduced beacon length according to an embodiment of the present disclosure, and Figure 4F shows schematic diagrams illustrating collision resolution with retransmission of data frames without direct contention after beacon transmission according to an embodiment of the present disclosure.

[0041] According to this embodiment, beacon frame transmissions are delayed or contain only essential portions of the content, or are short beacon frames coded with a high modulation and coding scheme (MCS) that is equal to or less than the lowest MCS currently applied to that BSS.

[0042] FIG. 4 shows the effect of a beacon delay (FIG. 4B) or a shorter beacon frame (FIG. 4D). A shorter beacon frame can be achieved either by less content or a higher MCS. The latency gain becomes apparent because the beacon is shifted in time or less time is used for beacon transmission. Postponing and shortening beacon transmissions need only occur if a retransmission coincides with a beacon transmission.

[0043] Figure 4F shows an embodiment of contention-free retransmission after a PPDU transmitted by the AP fails, i.e., the beacon is not postponed and time is reserved for retransmission immediately after the beacon is transmitted. Therefore, after a missed response, instead of postponing the beacon, the AP sends a contention-free retransmission immediately after the beacon / short beacon frame. To this end, the AP reserves channel time for STAs to retransmit. This is not a periodic interval, but a single reserved time interval that occurs when no response to a retransmission is received and the next transmission from the AP is a beacon transmission. The indication of a one-time contention-free interval can be indicated in the beacon, or access rules can be defined to allow channel access within CW=0 or priority inter-frame spacing (PIFS) and prohibit backoff of AP transmission retransmissions.

[0044] In the downlink, the operation is as follows: the AP includes a single indication of the contention-free interval in the beacon. STAs that experience a missing packet should remain awake after the beacon transmission. The duration of this interval must cover retransmissions, responses (acknowledgments), and the corresponding interframe space (IFS), and may be announced in the PPDU sent by the AP. After the announcement (e.g., after a SIFS), the AP performs a retransmission and waits for a response (e.g., an acknowledgment). Similar to the embodiment shown in Figure 6B described below, the duration of this interval may be selected to cover a response request (e.g., an acknowledgment request), a response (e.g., an acknowledgment), a potential retransmission, and a response to the retransmission (e.g., an acknowledgment) if due to interference at the AP. If the response to the response request indicates a non-failed PPDU, the AP may end the current period by sending an end notification (eg, a CF End frame) as shown in FIG. 3B.

[0045] On the uplink, the operation is as follows: If an AP fails to decode a PPDU from a STA, it may send a trigger or poll at the start of the contention-free period immediately after the beacon transmission, e.g., within a PIFS to request a retransmission of the STA. A trigger or poll elicits a retransmission within the SIFS interval.

[0046] Thus, according to the embodiment described with reference to Figures 4B, 4D and 4F, if no first response is received, the channel access for non-data frames and / or data frames is changed. In particular, the transmission of the beacon frame and / or retransmissions after the transmission of the beacon frame are modified compared to the normal transmission of the beacon frame, whereby the beacon frame has a predetermined length and is transmitted after a target beacon transmission time with a predetermined modulation and coding scheme. If the first response is not received, one or more data frames are retransmitted to the second communication device, and channel access for the beacon frame is modified compared to normal transmission of the beacon frame, whereby the beacon frame has a predetermined length and is transmitted after a target beacon transmission time with a predetermined modulation and / or encoding scheme.

[0047] In one embodiment, the modulation and / or coding is selected so that all STAs associated with the AP can receive and / or decode the beacon frame. Within an AP's BSS, links between all AP-STA pairs have different link budgets due to different path losses, etc. The lower the link budget, the lower the modulation or coding scheme. If the modulation and / or coding is selected to be the minimum modulation and / or coding scheme for all AP STA pairs, the beacon can be received by any STA in the BSS. STAs outside the BSS may not be affected, as this behavior naturally limits the coverage area of ​​the beacon. Therefore, this rule may only be applied in case of retransmissions, otherwise the beacon should be transmitted with the lowest MCS to keep the coverage area maximum.

[0048] A fourth embodiment of a device and method according to the present disclosure is shown in FIG. 5, where FIG. 5A shows a schematic diagram illustrating conventional operations in a multi-link setup method, and FIG. 5B shows a schematic diagram illustrating collision resolution with link selection for retransmission in a multi-link setup method according to an embodiment of the present disclosure.

[0049] If an AP STA supports multiple links, it should use that link for retransmissions. This link allows retransmissions to occur before the next beacon is sent, making it available to STAs that need to retransmit. This behavior is illustrated in Figure 5B, which shows an example of latency reduction through link selection that avoids beacon transmissions. At some point in the retransmission, it is assumed that both links are active and link 2 is idle.

[0050] According to conventional operation, a beacon is transmitted as scheduled by a first target beacon transmission time on a first link (TBTT on link 1). Then, after another contention, the data unit is retransmitted on the first link. In parallel, another beacon may be transmitted on the second link if scheduled by a second TBTT (on link 2). According to an embodiment of the present disclosure, in contrast, the data unit is retransmitted on the second link because the second TBTT (on link 2) is later than the first TBTT (on link 1). In parallel, the beacon is transmitted on the first link after the first TBTT. This results in increased latency compared to conventional operation. In this context, it should be noted that this embodiment also works when the STA transmitting the PPDU is a non-AP STA.

[0051] Thus, according to the embodiment illustrated with reference to FIG. 5, not receiving a first response causes the channel access of the data frame to be changed.

[0052] A fifth embodiment of a device and method according to the present disclosure is shown in FIG. FIG. 6A shows a schematic diagram illustrating conventional operations for retransmission, and FIG. 6B shows a schematic diagram illustrating collision resolution with access prioritization of block confirmation requests (BARs) according to an embodiment of the present disclosure.

[0053] In a typical WLAN, a STA may send a BAR to request a block acknowledgement, which preserves the MPDU reception status at the peer STA. Before performing an action such as retransmission of data, it may be useful to obtain the BAck status, because the absence of a BAck response indicates that the transmission of the data PPDU failed, the data PPDU is not decodable, or the BAck has not been received or is not decodable.

[0054] In the second case (BAck not received or cannot be decoded), it is possible that all data was received correctly but the BAck was in error. To exclude unnecessary retransmissions, this embodiment proposes to give priority to the BAR in channel access when it is transmitted in a PPDU without an additional MPDU, i.e., only the BAR is transmitted and a BAck response is awaited before retransmission of the data PPDU is initiated. An implementation of such BAR access prioritization would look like this:

[0055] The BAR is transmitted on any access category (AC) or on an AC higher than the primary AC of the TXOP where the initial transmission of the PPDU failed. For example, a data PPDU transmitted on a best-effort AC can use the video AC for BAR transmission. Traditionally, in WLANs, the BAR is used as the AC for the initial transmission. It should be noted that in this context, the concept of access category refers to a mechanism for prioritizing different types of traffic. WLAN distinguishes between four different ACs: voice, video, best effort, and background. All may have different channel access parameters such as CWmin and / or AIFS.

[0056] For BAR transmissions, the backoff increase for failed transmissions is small, just like for regular data traffic. In a regular WLAN, each failed PPDU transmission doubles the backoff. This means that the range of random CW values ​​doubles, making small backoff periods less probable. For BAR-only transmissions and associated acknowledgments, this behavior can be adapted to less than 2x, such as a 1.5x backoff window. Following an acknowledgment with a BAck, the CW window is reset to its minimum size [0 CWmin] for the next data transmission.

[0057] Also, as a variation, a different set of EDCA parameters may be used for BAR transmissions, meaning that two sets of EDCA parameters are maintained and configured by the AP STA: one for normal data transmissions and one dedicated to BAR frames and associated responses. These EDCA parameters typically include CWmin, CWmax, AIFS, etc.

[0058] Figure 6 shows the behavior with BAR access prioritization and latency gains. In many cases, STA 1 does not know why the BAck response is missing. Therefore, if the BAR reveals that PPDU A failed, STA 1 may retransmit PPDU A in the same TXOP a short time (e.g., short interframe space, SIFS) after the BAck without any new contention. In this case, the latency gain is smaller, but it must be greater than zero. This is a modification step that allows BAR, BAck, PPDU retransmission, and BAck to achieve lower latency on average than long contention and retransmission. Therefore, the following relationship holds:

[0059] contTime{BAR} + txTime{BAR} + 2 txTime{BAck} + txTime{PPDU A {2 nd TX)} ≦ contTime{PPDU A(2 nd TX)} + txTime{PPDU A(2 nd TX)} + txTime{BAck} this is, contTime{BAR} + txTime{BAR} + txTime{BAck} ≦ contTime[PPDU A (2 nd TX)} can be simplified to

[0060] Thus, the acknowledgement request is transmitted with a priority equal to or higher than the priority at which the data unit was originally transmitted, and may also be transmitted after a backoff that is smaller than the backoff applied to perform a retransmission of the data unit. Additionally, the acknowledgement request may be transmitted with transmission parameters, at least one of which is different from the transmission parameters used to transmit the data unit.

[0061] Thus, according to the embodiment illustrated with reference to Figure 6, failure to receive a first response results in a change of channel access for non-data frames. In particular, if a first response is not received, an acknowledgement request is sent to the second communication device and a second response from the second communication device is awaited in response to the acknowledgement request. If a second response is received indicating that no data frames were received, or if no second response is received, one or more data frames are retransmitted.

[0062] A sixth embodiment of a device and method according to the present disclosure is shown in Figure 7, where Figure 7A is a schematic diagram illustrating conventional operation for retransmission with unchanged TXOP duration, and Figure 7B is a schematic diagram illustrating shortening of TXOP duration when a failed PPDU is detected according to an embodiment of the present disclosure.

[0063] According to this embodiment, the AP STA or STAs that recognize the failed PPDU will shorten the maximum duration of the TXOP, so that the STA that sent the failed PPDU and may have a high CW value can count down its CW value faster due to the shorter TXOP time of other STAs. Since AP STAs are part of the data exchange within the BSS, they often set the TXOP time limit and recognize collisions. Therefore, if an AP STA detects a failed PPDU, it can limit the TXOP time of the communication. Furthermore, the AP STA can set a TXOP duration limit for all STAs by appropriate signaling within the PPDU (e.g., in the preamble) or MAC frame or MAC header (A-control subframe).

[0064] In most cases, it may make sense to limit the TXOP duration only for STAs that have not suffered a failed PPDU. The TXOP time limit can be set inversely relative to the increase in CW, i.e., the maximum TXOP time is halved every time the CW range is doubled. Table 1 shows the M-1 th The expected behavior is shown, including saturation after retransmission. [Table 1]

[0065] The advantage in terms of latency is illustrated in Figure 7, which shows three STAs, where STA 2 may illustratively be the AP STA. A data transfer from STA 1 to STA 2 suffers from a failed PPDU, so STA 1 draws a long CW. While STA 1 is counting down the CW, STA 3 initiates two long TXOPs, e.g., data transfers to another STA, which causes a long wait time for STA 1 to retransmit its data.

[0066] FIG. 7A shows conventional operation with the TXOP duration unchanged, while FIG. 7B shows operation with the TXOP duration halved after a corrupted PPDU according to one embodiment of the present disclosure. Also, in FIG. 7B, it is assumed that the TXOP is shortened for all STAs except for the corrupted PPDU, i.e., STA 1.

[0067] 7, the transmission opportunity configuration is changed if the first response is not received. In particular, a faulty data transmission of a data frame by the communication device or the second communication device is recognized by recognizing a missing response following the transmission of one or more data frames during the first transmission opportunity. The shortened transmission opportunity is then signaled to one or more third communication devices to transmit and / or receive during said 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 said shortened transmission opportunity. The one or more data frames are then retransmitted to the second communication device, or the one or more retransmitted data frames are received from the second communication device during one or more second transmission opportunities.

[0068] In another embodiment, the erroneous data transmission in the PPDU is detected by STA 1 or STA 2 by detecting a missing response following the transmission of one or more data frames in the PPDU during the first TXOP. The shortened TXOP is then configured to exchange data of higher and / or the same and / or lower priority with STA 2 and / or one or more other STAs during the shortened TXOP, and one or more data frames in the PPDU are retransmitted to STA 2 or received as retransmitted by STA 2 during one or more second TXOPs. Finally, the length (duration) of the shortened TXOP is restored to its original length (i.e., extended again to its original length) after a second response occurs in the second TXOP due to the retransmission of one or more data frames. This allows the shortened TXOP to be further shortened if a missing response is detected after the retransmission of one or more data frames to the STA. Every STA has a maximum TXOP time it can use. This maximum TXOP duration is defined by the AP and can be set differently for each priority. If there is no response, this length is reduced (e.g., divided by 2). If another missed response occurs, it may be reduced further (e.g., divided by 4).

[0069] This embodiment provides that retransmission can occur quickly when the STAs have mixed traffic, i.e., data frames of different priorities are available, e.g., STA 1 transmits a low-latency data frame to STA 2 with a higher priority, but the response by STA 2 is missing. This means that STA 1 initiates a random backoff procedure for the high-priority queue that may last longer than the backoff of the low-priority queue, thus preventing STA 1 from retransmitting high-priority data frames because the low-priority data frames are transmitted a long time ago. With the proposed TXOP reduction, when a response loss occurs for the high-priority queue, the TXOP of the low-priority queue is lowered, so the high-priority queue may transmit earlier because the maximum time for low-priority data frames on the wireless medium is shorter. The TXOP of the low-priority queue prevents immediate retransmission of high-priority data frames, but for a shorter time.

[0070] In one embodiment using MU PPDU transmission, the operation is as follows. Initially, there is a first set of two or more STAs that are addressed, each with one or more data frames. A subset (i.e., at least one) of the one or more data frames may require a response. A further subset (i.e., at least one) of the one or more data frames are acknowledged. If the last subset is empty, the steps disclosed herein are performed, i.e., the transmission opportunity configuration and / or channel access for non-data frames and / or data frames are changed. If the last subset is not empty, these steps are not performed.

[0071] FIG. 8 is a schematic diagram of a configuration of a communication device 10 according to an embodiment of the present disclosure. Generally, each AP and STA can be configured as shown in FIG. 8, and may include a data processing unit 11, a wireless communication unit 12, a control unit 13, and a storage unit .

[0072] The data processing unit 11 processes data to be transmitted and received as part of the communication device 10. Specifically, the data processing unit 11 generates frames based on data from an 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 packets, particularly MAC packets) from data, and performs processing such as adding a MAC header for MAC (Media Access Control) and adding an error detection code to the generated frames. Furthermore, the data processing unit 11 extracts data from the received frame and provides the extracted data to an upper layer of the communication device 10. For example, the data processing unit 11 acquires data by analyzing the MAC header, detecting and correcting code errors, and performing reordering processing on the received frame.

[0073] In this context, in WLAN terminology, a frame is called a service data unit from which higher layer data is subjected to further processing such as fragmentation, aggregation, header addition, etc. to create a MAC layer frame. Furthermore, in WLAN terminology, a packet is called a PHY Protocol Data Unit (PPDU), which is further understood as a physical layer packet.

[0074] The wireless communication unit 12 has a signal processing function, a wireless interface function, and the like as part of the communication unit.

[0075] The signal processing function is a function of performing signal processing such as modulation on frames. Specifically, the wireless communication unit 12 performs encoding, interleaving, and modulation on the frames provided by the data processing unit 11 in accordance with the encoding and modulation method set by the control unit 13, adds a preamble and a PHY header, and generates a symbol stream. Furthermore, the wireless communication unit 12 acquires frames by performing demodulation, decoding, etc. on the symbol stream obtained by processing the wireless interface function, and provides the acquired frames to the data processing unit 11 or the control unit 13.

[0076] The wireless interface function transmits and receives signals via one or more antennas. Specifically, the wireless communication unit 12 converts the symbol stream signal obtained through the signal processing function into an analog signal, amplifies the signal, filters it, and up-converts the frequency. Next, the wireless communication unit 12 transmits the processed signal via an antenna. Furthermore, with respect to the signal obtained via the antenna, the wireless communication unit 12 performs processing that is the reverse of the processing performed during signal transmission, such as frequency conversion and down-conversion in digital signal conversion.

[0077] As part of the communication device, the control unit 13 (often referred to as a station management entity (SME)) controls the overall operation of the communication device 10. Specifically, the control unit 13 performs processes in the data processing unit 11, such as exchanging information between functions, setting communication parameters, and scheduling frames (or packets).

[0078] The storage unit 14 stores information used in processing performed by the data processing unit 11 or the control unit 13. Specifically, the storage unit 14 stores information stored in a transmission frame, information acquired from a reception frame, information on communication parameters, and the like.

[0079] In an alternative embodiment, each of the AP and the STA may be configured by using a circuit that implements the units and functions to be performed shown in Figure 8. The circuit may be realized, for example, by a programmed processor. In general, the functions of the AP and STAs and units of the communication device 10 shown in FIG. 8 can be realized in software, hardware or a mixture of software and hardware.

[0080] FIG. 9 illustrates a flowchart of one embodiment of a communication method for a first communication device to communicate with a second communication device according to the present disclosure. In a first step (S10), one or more data frames are transmitted from the first communication device to the second communication device requiring a response from the second communication device. In a second step S11, the first communication device waits for a first response (e.g., Ack or BAck) from the second communication device acknowledging receipt of at least one or more data frames. In a third step S12, if the first response is not received, the first communication device changes the transmission opportunity configuration and / or channel access for non-data frames and / or data frames, particularly in accordance with one or more of the embodiments disclosed herein, before the one or more data frames are retransmitted (step S13). If not (step S14), the transmission of (normal) data frames continues, or, if there are no more data frames, the transmission is stopped.

[0081] The presented embodiments of the present disclosure provide rules for channel access in unlicensed bands to reduce latency in the event of failure of data carrying PPDUs. This rule sacrifices throughput to reduce latency. AP STAs can enable these rules to achieve low-latency data transfer within a Basic Service Set (BSS) or cell.

[0082] Accordingly, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure, and as will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, the disclosure of this disclosure, as well as the other claims, is intended to be illustrative, but not limiting, of the scope of the disclosure, and the disclosure will include any readily identifiable variations of the teachings herein, and will in part define the scope of the foregoing claim terms, so that the subject matter of the invention is not exclusive to the public.

[0083] Furthermore, in the claims, the words "comprise" and "include" do not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recommended in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0084] To the extent that embodiments of the present disclosure are described as being implemented, at least in part, by a software-controlled data processing apparatus, it will be understood that a non-transitory machine-readable medium carrying such software, such as an optical disk, magnetic disk, semiconductor memory, or the like, is also considered to represent an embodiment of the present disclosure. Furthermore, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0085] The elements of the devices, apparatus, and systems disclosed herein may be realized by corresponding hardware and / or software elements, such as suitable circuitry, which is a structural assembly of electronic components, including conventional circuit elements, integrated circuits, including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. Furthermore, the circuitry includes a central processing unit, a graphics processing unit, and a microprocessor that is programmed or configured according to the software code. The circuitry does not include pure software, but the circuitry includes the above-mentioned hardware executing software.

[0086] The following follows a list of further embodiments of the subject matter disclosed herein. 1. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames. The circuit is configured as follows: Communication devices. 2. A communication device according to claim 1, The circuit comprises: If the first response is not received, sending an acknowledgement request to the second communication device; awaiting a second response from the second communication device in response to the acknowledgment request; and If the second response is received, retransmitting an indication that none of the data frames have been received, or if the second response is not received, retransmitting an indication that one or more data frames have been received. It is configured as follows: Communication devices. 3. The communication device according to claim 2, The circuitry is configured to transmit the acknowledgment request at a channel access priority higher than a channel access priority at which a first of the one or more data frames was originally transmitted. Communication devices. 4. A communication device according to 2 or 3, The circuitry is configured to transmit the acknowledgment request after a channel access backoff that is less than a channel access backoff that is applied to perform retransmission of one or more data frames. Communication devices. 5. A communication device according to any one of 2 to 4, The circuitry is configured to retransmit the one or more data frames within the same transmission opportunity in which the acknowledgment request is transmitted. Communication devices. 6. A communication device according to any one of 2 to 5, The circuitry is configured to transmit the acknowledgment request using a plurality of channel access parameters, at least one of the plurality of channel access parameters being different from a channel access parameter used to transmit and / or retransmit the one or more data frames. Communication devices. 7. A communication device according to any one of 2 to 6, The circuit comprises: If the first response is not received, the next transmission opportunity available to the communication device is i) retransmission of the one or more data frames to the second communication device and receiving a second response from the second communication device confirming receipt of the retransmission of the one or more data frames; and / or ii) transmitting one or more data frames to said second communication device with the same or higher priority than one or more previously transmitted or retransmitted data frames; and / or iii) if the second response is received, an indication that no additional data frames are being transmitted in the same transmission opportunity by the communication device; Set it to include only It is configured as follows: Communication devices. 8. The communication device according to 7, The notification further indicates that the second communication device may use the current transmission opportunity for data transmission. Communication devices. 9. A communication device according to claim 7 or 8, The circuitry is configured to transmit a contention-free end frame as a notification. Communication devices. 10. A communication device according to any one of 1 to 9, The circuit comprises: transmitting one or more data frames to the second communication device on a first link; awaiting a first response from the second communication device on the first link acknowledging receipt of the one or more data frames; If the first response is not received, switch channel access to the second link to retransmit the one or more data frames to the second communication device on the second link having a second target beacon transmission time that is later than the first target beacon transmission time of the first link or that has no beacon transmission time, and transmit a beacon frame on the first link after the first target beacon transmission time has elapsed. It is configured as follows: Communication devices. 11. A communication device according to any one of 1 to 10, the circuitry, if not receiving the first response, retransmits the one or more data frames to the second communication device and changes a beacon access channel for normal transmission of beacon frames; The beacon frame has a predetermined length and is transmitted after a target beacon transmission time with a predetermined modulation and / or coding scheme. It was configured as Communication devices. 12. A communication device according to any one of 1 to 11, The circuitry is configured to modify channel access to postpone transmission of the beacon frame and to retransmit the one or more data frames before the beacon frame is transmitted. Communication devices. 13. A communication device according to 11 or 12, The circuitry is configured to transmit a shortened beacon frame having a length shorter than the predetermined length and to retransmit the data unit after the shortened beacon frame is transmitted. Communication devices. 14. A communication device according to any one of 11 to 13, The circuitry is configured to transmit the beacon frame with a modulation and / or coding scheme different from the predetermined modulation and coding scheme, and to retransmit the one or more data frames after the beacon frame is transmitted. Communication devices. 15. The communication device according to claim 14, The circuitry is configured to select modulation and / or coding such that all second communication devices associated with the communication device can receive and / or decode the beacon frame. Communication devices. 16. A communication device according to any one of 1 to 15, The circuitry is configured to retransmit the one or more data frames to the second communication device without contention after a beacon frame is transmitted. Communication devices. 17. The communication device according to claim 16, A contention-free interval between transmission of the beacon frame and retransmission of the one or more data frames is announced in the beacon. Communication devices. 18. A communication device according to any one of 1 to 17, the circuitry retransmits a portion of the one or more data frames and uses one or more transmission parameters for retransmitting the one or more data frames that differ from transmission parameters used to initially transmit the one or more data frames; The transmission parameters for retransmitting the portion of the one or more data frames are the same. It is configured as follows: Communication devices. 19. A communication device according to any one of 1 to 18, The circuit comprises: retransmitting a first portion of the one or more data frames; awaiting a second response acknowledging receipt of the first portion of the one or more data frames transmitted from the second communication device; If the second response is received, retransmitting one or more additional portions of the one or more data frames using one or more transmission parameters that differ from the transmission parameters used to originally transmit the one or more data frames. It is configured as follows: Communication devices. 20. A communication device according to 18 or 19, one or more transmission parameters used to retransmit the one or more data frames are different from transmission parameters used to initially transmit the one or more data frames; The transmission parameters for retransmitting a portion of the one or more data frames are the same. Communication devices. 21. A communication device according to any one of items 18 to 20, The one or more different transmission parameters include one or more transmission parameters in a group of transmission parameters including a modulation and / or coding scheme, a transmission bandwidth, a number of spatial streams, a transmission method, and a type of data frame. Communication devices. 22. A communication device according to any one of 1 to 21, The circuit comprises: Recognizing a failed data transmission of one data frame by the communication device or the second communication device by recognizing that a subsequent transmission of one or more data frames is missing during a first transmission opportunity; signaling a reduced transmission opportunity to one or more third communication devices to transmit and / or receive during said reduced transmission opportunity, and / or configuring said reduced transmission opportunity to exchange data with one or more second and / or third communication devices during said reduced transmission opportunity; and retransmitting the one or more data frames to the second communication device or receiving the one or more retransmitted data frames from the second communication device during one or more second transmission opportunities. It is configured as follows: Communication devices. 23. A communication device according to any one of 1 to 22, The circuitry is configured to receive an indication from the second or third communication device indicating whether and / or how a transmission opportunity setting and / or channel access is to be changed if the first response is not received. Communication devices. 24. A communication device according to any one of 1 to 23, The circuit comprises: transmitting the one or more data frames to two or more second communication devices; awaiting a first response confirming receipt of at least one of the one or more data frames from the two or more second communication devices; and modifying the transmission opportunity configuration and / or the channel access for non-data frames and / or data frames if the first responses are not received from the two or more second communication devices; It is structured as follows: At least one of the one or more data frames requires a response Communication devices. 25. A communication device according to any one of 1 to 24, The circuit comprises: if a channel is detected as idle at the end of a predetermined backoff time, wait for the channel for the predetermined backoff time; and If the channel is detected in a non-idle state, subtract the time span until the channel is detected in a non-idle state from the predetermined backoff time and wait until the channel is again detected in an idle state. It is configured as follows: Communication devices. 26. A communication device according to any one of 1 to 25, If the first response is not received, the circuitry is configured to change a transmission opportunity configuration and / or channel access for non-data frames and / or data frames until at least one of the one or more data frames is successfully retransmitted or a timeout is reached. Communication devices. 27. A communication method of a communication device for communicating with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; waiting for a first response from the second communication device confirming receipt of at least one of the one or more data frames; if the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames; include method. 28. A computer program product that, when stored in the computer program product and executed by a processor, causes the method of claim 27 to be performed. A non-transitory computer-readable recording medium. 29. A computer program comprising program code means for causing a computer to perform the steps of the method of embodiment 27 when the computer program is run on the computer. Computer program. 30. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, sending an acknowledgement request to the second communication device; awaiting a second response from the second communication device in response to the acknowledgement request; and If the second response is received, retransmitting an indication that none of the data frames have been received, or if the second response is not received, retransmitting an indication that one or more data frames have been received. The circuit is configured as follows: Communication devices. 31. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, the next transmission opportunity available to the communication device is i) retransmission of the one or more data frames to the second communication device and receiving a second response from the second communication device confirming receipt of the retransmission of the one or more data frames; and / or ii) if the second response is received, an indication that no additional data frames are being transmitted in the same transmission opportunity by the communications device; Configure it to include only The circuit is configured as follows: Communication devices. 32. A communications device configured to communicate with a second communications device, comprising: transmitting one or more data frames to the second communication device on a first link; awaiting a first response from the second communication device on the first link acknowledging receipt of the one or more data frames; If the first response is not received, switch channel access to the second link to retransmit the one or more data frames to the second communication device on the second link having a second target beacon transmission time that is later than the first target beacon transmission time of the first link or that has no beacon transmission time, and transmit a beacon frame on the first link after the first target beacon transmission time has elapsed. The circuit is configured as follows: Communication devices. 33. A communications device configured to communicate with a second communications device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; if the first response is not received, retransmitting the one or more data frames to the second communication device and changing a beacon access channel for normal transmission of beacon frames; The beacon frame has a predetermined length and is transmitted after a target beacon transmission time with a predetermined modulation and / or coding scheme. The circuit is configured as follows: Communication devices. 34. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; if the first response is not received, retransmitting a portion of the one or more data frames and using one or more transmission parameters for retransmitting the one or more data frames that differ from transmission parameters used to initially transmit the one or more data frames; The transmission parameters for retransmitting the portion of the one or more data frames are the same. The circuit is configured as follows: Communication devices. 35. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; retransmitting a first portion of the one or more data frames if the first response is not received; awaiting a second response acknowledging receipt of the first portion of the one or more data frames transmitted from the second communication device; If the second response is received, retransmitting one or more additional portions of the one or more data frames using one or more transmission parameters that differ from the transmission parameters used to originally transmit the one or more data frames. The circuit is configured as follows: Communication devices. 36. A communication device configured to communicate with a second communication device, comprising: Recognizing a failed data transmission of one data frame by the communication device or the second communication device by recognizing that a subsequent transmission of one or more data frames is missing during a first transmission opportunity; signaling a reduced transmission opportunity to one or more third communication devices to transmit and / or receive during said reduced transmission opportunity, and / or configuring said reduced transmission opportunity to exchange data with one or more second and / or third communication devices during said reduced transmission opportunity; and retransmitting the one or more data frames to the second communication device or receiving the one or more retransmitted data frames from the second communication device during one or more second transmission opportunities. The circuit is configured as follows: Communication devices. 37. A communication device according to any one of 1 to 26, wherein the circuitry comprises: detecting an unsuccessful data transmission of a data frame by the communication device or the second communication device by detecting a lack of a response following transmission of the one or more data frames during a first transmission opportunity; setting abbreviated transmission opportunities for preferably lower priority data transmissions and exchanging higher and / or the same and / or lower priority data with one or more second and / or third communication devices during said abbreviated transmission opportunities; retransmitting the one or more data frames to the second communication device or receiving the one or more retransmitted data frames from the second communication device during one or more second transmission opportunities; and Restoring the length of the transmission opportunity after retransmission of the one or more data frames to generate a second response within the second transmission opportunity, and / or further shortening the shortened transmission opportunity if a missing response is detected after retransmission of the one or more data frames to the second communication device. It is configured as follows: Communication devices.

Claims

1. a communication device configured to communicate with a second communication device, transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames. The present invention provides a circuit configured as follows: The circuit comprises: transmitting one or more data frames to the second communication device on a first link and waiting for a first response from the second communication device on the first link acknowledging receipt of the one or more data frames; If the first response is not received, switch channel access to the second link to retransmit the one or more data frames to the second communication device on the second link having a second target beacon transmission time that is later than the first target beacon transmission time of the first link or that has no beacon transmission time, and transmit a beacon frame on the first link after the first target beacon transmission time has elapsed. It is configured as follows: Communication devices.

2. A communication device configured to communicate with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; awaiting a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames. The present invention provides a circuit configured as follows: the circuitry, if not receiving the first response, retransmits the one or more data frames to the second communication device and changes a beacon access channel for normal transmission of beacon frames; The beacon frame has a predetermined length and is transmitted after a target beacon transmission time with a predetermined modulation and / or coding scheme. It was configured as Communication devices.

3. A communication device as claimed in claim 2, The circuit comprises: modifying channel access to postpone transmission of the beacon frame and retransmitting the one or more data frames before the beacon frame is transmitted; and / or Transmitting a shortened beacon frame having a length shorter than the predetermined length, and retransmitting the data unit after the shortened beacon frame is transmitted. It is configured as follows: Communication devices.

4. 1. A communication method of a communication device for communicating with a second communication device, comprising: transmitting to the second communication device one or more data frames requiring a response by the second communication device; waiting for a first response from the second communication device confirming receipt of at least one of the one or more data frames; If the first response is not received, modifying the transmission opportunity configuration and / or channel access for data frames and / or non-data frames. The present invention provides a circuit configured as follows: the circuitry transmits one or more data frames to the second communication device on a first link and waits for a first response from the second communication device on the first link acknowledging receipt of the one or more data frames; If the first response is not received, switch channel access to the second link to retransmit the one or more data frames to the second communication device on the second link having a second target beacon transmission time that is later than the first target beacon transmission time of the first link or that has no beacon transmission time, and transmit a beacon frame on the first link after the first target beacon transmission time has elapsed. The communication method of the communication device.

5. A program stored therein that, when executed by a processor of a communication device configured to communicate with a second communication device, causes the communication method of claim 5 to be performed. A computer-readable recording medium.

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