First and second communication devices and methods

Abstract

A first communication device that is configured to communicate with one or more second communication devices comprises circuitry configured to obtain schedule parameters of a scheduled communication set up by a third communication device; receive a request for a transmission opportunity (TXOP) from a second communication device; set up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmit an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.

Description

FIRST AND SECOND COMMUNICATION DEVICES AND METHODSBACKGROUNDFIELD OF THE DISCLOSURE

[0001] The present disclosure relates to first and second communication devices that are configured to communicate with each other and to corresponding communication methods.DESCRIPTION OF RELATED ART

[0002] One of the focus areas of the new developments in WLAN is latency and jitter enhancement to enable interactive applications such as gaming, jamming or industrial applications. In order to improve low latency and jitter for such wireless transmission of traffic corresponding e.g. to real time applications, the introduction of scheduling (or scheduled)intervals has been proposed. Ensuring however that the scheduling intervals are respected in the unlicensed spectrum is challenging due to a variety of factors such as contention being the default channel access mechanism, networks being mostly unmanaged and the existence of legacy stations or stations which do not support the implementation of scheduled periods. Further, such scheduling intervals should be protected from interference.

[0003] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] It is an object to provide a mechanism for further improving the protection of scheduling intervals from interference caused by transmissions of communication devices in another basic service set. It is a further object to provide a corresponding method as well as a corresponding computer program and a non-transitory computer-readable recording medium that stores therein a computer program product for implementing said method.

[0005] According to an aspect there is provided a first communication device configured to communicate with one or more second communication devices, the first communication device comprising circuitry configured to obtain schedule parameters of a scheduled communication set up by a third communication device; receive a request for a transmission opportunity (TXOP) from a second communication device; set up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmit an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.

[0006] According to a further aspect there is provided a second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to transmit a request for a transmission opportunity (TXOP) to the first communication device; receive from the first communication device an sTXOP indication of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device; and use the adapted TXOP parameters for communication with the first communication device.

[0007] According to still further aspects corresponding methods, a computer program comprising program means for causing a computer to carry out the steps of the methods disclosed herein, when said computer program is carried out on a computer, as well as a non-transi- tory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the methods disclosed herein to be performed are provided.

[0008] Embodiments are defined in the dependent claims. It shall be understood that the disclosed methods, the disclosed computer program and the disclosed computer-readable recording medium have similar and / or identical further embodiments as the claimed devices and as defined in the dependent claims and / or disclosed herein.

[0009] One of the aspects of the disclosure is a mechanism that efficiently protects the scheduled communication between two communication devices, in particular between a third communication device (which is an AP in an embodiment) and one or more fourth communication device(s) (which are non-AP STAs in an embodiment) from the communication between neighboring communication devices, such as communication between a first communication device (which is another AP in an embodiment) and one or more second communication device(s) (which are other non-AP STAs in an embodiment) in an overlapping basic service set (oBSS). For this purpose the first communication device in the oBSS sets up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device, e.g. by initiating anew TXOP or adjusting a requested TXOP with parameters depending on the scheduling interval between the third communication device (e.g. AP) and its fourth communication devices (e.g. STA(s)) to be protected in the BSS. The proposed mechanism does not require medium reservation when no traffic is queued and only requires low complexity at the second and fourth communication devices (e.g. (non-AP) STAs), i.e., does not require the second and fourth communication devices to follow or save a large amount of scheduling information.

[0010] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWING

[0011] A more complete appreciation of the 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, wherein:Fig. 1 shows a diagram of a communication system according to an aspect of the present disclosure.Fig. 2 shows a flowchart of a first communication method according to the present disclosure.Fig. 3 shows a flowchart of a second communication method according to the present disclosure.Fig. 4 shows a first embodiment of a communication scheme according to the present disclosure.Fig. 5 shows a second embodiment of a communication scheme according to the present disclosure.Fig. 6 shows a third embodiment of a communication scheme according to the present disclosure.Fig. 7 shows a fourth embodiment of a communication scheme according to the present disclosure.Fig. 8 shows a fifth embodiment of a communication scheme according to the present disclosure.Fig. 9 shows a sixth embodiment of a communication scheme according to the present disclosure.Fig. 10 shows a seventh embodiment of a communication scheme according to the present disclosure.Fig. 11 shows an eighth embodiment of a communication scheme according to the present disclosure.Fig. 12 shows a ninth embodiment of a communication scheme according to the present disclosure.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] Communication devices, in particular access points (APs), can schedule intervals for specific purposes e.g., low latency (LL) traffic and power saving. A particular type of a scheduling interval is a restricted target wake up time (rTWT), in which a set of stations (STAs) with particular traffic characteristics are prioritized in accessing the channel. Mechanisms to decrease the probability of STAs outside of the schedule to access the medium duringthe specific intervals have been defined and include repurposing quiet elements and enforcing STAs to respect scheduling interval start times.

[0013] Assuming coordination between multiple APs is possible, then the protection of the schedules of one AP does not need to be ensured only by that specific AP, but it can also be performed by the neighboring AP. Protection from neighboring APs has been proposed via schedule coordination and distribution, however this operation can increase the complexity for the non-AP STAs which, in this case, need to save and respect a potentially large amount of scheduling information. Thus, the present disclosure presents a mechanism that protects from oBSS STAs but without the need for medium reservation when no traffic is queued and with low complexity at the non-AP STAs, i.e. , without requiring the non-AP STAs to follow or save a large amount of scheduling information. Different to known concepts, the role of the neighboring AP is not to broadcast or relay scheduling information of its neighbors to all its STAs (or service period (SP) capable STAs), but to correct in case non-AP STAs are unaware or incapable of following the scheduling information. The focus is not on coordinating schedules, but rather on defining behavior under the assumption that some coordination is possible.

[0014] Before details of various embodiments of the present disclosure are discussed, some assumptions on scenarios, in which the present disclosure takes place, shall be made. These assumptions include that APs exchange information about their schedules or negotiate schedule intervals. Further, APs negotiate the behavior within the scheduling intervals, in particular for scheduling intervals defined for coordinated transmissions. Still further, APs commit to respect each other scheduling intervals unless specific conditions are met as will be elaborated herein.

[0015] Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, Fig. 1 shows a diagram of a scenario in which the present disclosure may be applied. It shows particularly a communication system including a first communication device 10 (which in an embodiment may be a first AP, called AP2 herein) according to an aspect of the present disclosure for communicating with one (or more) second communication device(s) 20 (which in an embodiment may be a first STA, called STA2 herein) before and / or during a scheduling interval, during whichcommunication of a third communication device 30 (which in an embodiment may be a second AP, called AP1 herein) is scheduled (planned) with one (or more) fourth communication device(s) 40 (which in an embodiment may be a second STA, called STA1 herein).

[0016] The first and second communication devices 10, 20 may be part of a basic service set (BSS), and the third and fourth communication device 30, 40 may be part of a neighboring BSS, e.g., an overlapping BSS (oBSS). The first communication device 10 is generally able to exchange (receive and / or transmit) data with the second communication device(s) 20, and the third communication device 30 is generally able to exchange (receive and / or transmit) data with the fourth communication device(s) 40. While only two STAs are shown in Fig. 1 , in other embodiments of the communication system there may be more STAs.

[0017] Each of the communication devices 10, 20, 30, 40 comprises circuitry 11 , 21 , 31 , 41 that is configured to perform particular operations. The circuitries may be implemented by a respective processor or computer, i.e. , as hardware and / or software, or by dedicated units or components. For instance, respectively programmed processors may represent the respective circuitries 11 , 21 , 31 , 41.

[0018] Fig. 2 shows a flow chart of an embodiment of a first communication method 100 of the first communication device 10 according to the present disclosure, which may be performed by the circuitry 11. In a first step 101 the first communication device 10 (AP2) obtains schedule parameters of a scheduled communication set up by a third communication device 30 (AP1). In step 102 it receives a request for a transmission opportunity (TXOP) from a second communication device 20 (STA2). In step 103 it sets up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device 20. In step 104 it transmits an indication (herein also called sTXOP indication) of the adjusted TXOP (sTXOP) indicating the adapted TXOP parameters to the second communication device.

[0019] Fig. 3 shows a flow chart of an embodiment of a second communication method 200 of the second communication device 20 according to the present disclosure, which may beperformed by the circuitry 21. In a first step 201 the second communication device 20 (STA2) transmits a request for a TXOP to the first communication device 10 (AP2). In step 202 it receives from the first communication device 10 an indication (also called sTXOP indication) of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device 20. In step 203 it uses the adapted TXOP parameters for communication with the first communication device 10 if the sTXOP indication indicates that the second communication device 20 can communicate with the first communication device 10 despite of a scheduled communication set up by a third communication device 30 (AP1).

[0020] Thus, the proposed operation may be as follows in a general embodiment: AP2 adjusts the parameters of a TXOP, requested by the associated STA2, or sets up a new TXOP for STA2, according to the parameters of a schedule in which the neighboring AP1 intends to communicate with a set of associated STAs (STA1).

[0021] Upon reception of a TXOP request from STA2, AP2 may check: if there is a schedule set up by a neighboring AP (e.g. AP1), and if yes, which are the parameters of the scheduled interval, in particular the status of the schedule (e.g., active or idle), the traffic identifiers (TIDs) for which it is set, if it for downlink (DL) or uplink (UL), if coordination possible, if constraints on a worst tolerable start delay are indicated, and which is the remaining time until the start of the schedule. Further, it may be checked if STA2 has potentially traffic with low latency requirements, which needs timely delivery.

[0022] Depending on the schedule parameters of the neighboring AP1 and the STA2 traffic requirements, TXOP parameters of the TXOP are adapted or a new TXOP is set up with adapted parameters. For some scenarios, depending on traffic characteristics at STA1 and properties of the scheduling interval, a part of the scheduled traffic may be further accommodated in the adapted TXOP.

[0023] There are different possibilities to check if STA2 has potentially traffic with low latency requirements, which needs timely delivery. Preferred possibilities are:checking if, for the STA1 requesting the TXOP, a stream classification service (SCS) stream has been established, where the QoS Characteristics Element is indicating low latency traffic, delay constraints of the respective traffic, and MAC service data unit (MSDll) lifetime about to expire; checking if the STA1 has previously indicated that it has traffic with stringent delay bounds (e.g., delays on queued traffic that are about to expire) and which should be sent within a specific interval; specifically requesting information of the traffic identifier (TID) of the traffic to be transmitted; or a combination of the two or more of these possibilities.

[0024] The specific checks and corresponding actions of AP2, depending on the schedule parameters are elaborated further below.

[0025] TXOP adjustment or setup may be performed through a frame, which may be called “adjusted TXOP” frame (or “shared TXOP in some embodiments) referred to herein as sTXOP. In its most basic form, this frame can have a similar implementation as a clear-to- send (CTS) frame, but with a modified duration, which is set according to the obtained scheduling information. As consequence, the duration is smaller than D_TXOP-SIFS- TXTIME(sTXOP) as would be expected from a CTS (SIFS: short interframe space;D_TXOP: duration of the TXOP requested by STA1 ; TXTIME(sTXOP): transmission time I duration of sTXOP frame). The duration is set to the duration until the start of the scheduling interval of AP1 to be protected or to the start plus a margin. This may be sufficient to provide protection to the schedule of AP1 , but it is quite restrictive for the STA2 as it does not consider the traffic requirements for which STA2 has obtained the TXOP.

[0026] In alternative implementations, sTXOP is designed to indicate: a first duration Ts, provided as first duration information, based on which all STAs, different than the second communication device, which are not part of the scheduling interval and receive the physical layer protocol data unit (PPDll) carrying it should set the network allocation vector (NAV), i.e., should consider the channel busy and refrain from accessing it;an effective duration Ten (also called second duration), provided as second duration information, which indicates the effective duration in which the TXOP can be used by the STA2 without further constraints; the TID for which the scheduling interval of AP1 has been set up and, optionally, scheduling Information, indicating at least, if the schedule is full or not, and / or if STA2 may access the channel during the scheduling interval assuming conditions on the traffic type are met, in particular if the traffic type to be transmitted by STA2 has a similar or higher traffic priority or traffic identifier.

[0027] The STAs scheduled for communication during the scheduling interval, should refrain from accessing the channel for an interval equivalent to the second duration information. In practice, since these STAs may not necessarily be capable of decoding all the information in the sTXOP, upon reception of an sTXOP frame, the scheduled communication devices may consider the channel as busy until at least the start of the interval, in which they are scheduled to transmit.

[0028] The scheduling information may include only a reduced portion of the complete scheduling information that is advertised within the rTWT and may be related only to the specific interval that is about to start and may be further compressed to only contain the information that is necessary for the STA2. Ts is generally larger than or equal to Teff. The TID settings and scheduling information determine if STA2 can use the TXOP for a duration of Teff, Ts or a value in between.

[0029] The following exemplary embodiments illustrate how these parameters are set and used. Within the examples and the following figures rTWT(AP1, STA1) refers to the scheduling interval set up by AP1, in which communication with the STA1 is planned.

[0030] Fig. 4 shows a schematic diagram of a first embodiment of a communication scheme 300 according to the present disclosure, in particular for use if AP2 has no QoS information of STA2 and the time up to the schedule start is short. If there is no information regarding the existence of an SCS stream for STA2 and the remaining time until the start of the schedule of AP1 is short, then AP2 can send an indication (sTXOP indication) to defer thetransmission of the STA2 until a predefined protection margin from the start of the respective schedule. This is illustrated in Fig. 4, where STA2 requests a TXOP, in this exemplary embodiment using a ready-to-send (RTS) frame representing a TXOP request 301 . STA2 transmits the TXOP request 301 requesting a TXOP with duration DTX0Pwhich is larger than the remaining duration DpreSPuntil the schedule start. Based on the scheduling information obtained from the third communication device, AP2 determines that the duration until the start if the scheduling interval is smaller than a minimum duration required for transmitting data, i.e. , it holds that: DpreSP- TXTIME (sTXOP) - 2SIFS < Preamble + Datamin-), where Data-in) is the minimum payload size.

[0031] In response, AP2 sets up an adjusted TXOP, herein also called sTXOP, based on the schedule parameters of the scheduled communication set up by AP1 that have been obtained from AP1. The sTXOP is set up with adapted TXOP parameters for use by STA21. Then, AP2 transmits the sTXOP indication 302 including the adapted TXOP parameters, in particular first duration information indicating a first time duration Ts and, optionally, a second duration information indicating a second time duration Ten. If there is no protection set up otherwise by AP1 for its scheduling interval, the two timers Ts and Ten are equal. Otherwise, Ten indicates the duration until the start of the rTWT and Ts is set as Ten + Tp, where Tpis a short protection interval which may be chosen equal to PIFS or quiet element duration. The sTXOP indication 302 may further include the TIDs for which the communication (the rTWT) is scheduled and / or may further indicate if SP is full. The information if the SP (i.e., the scheduling interval = rTWT) is full or not indicates if STAs other than the scheduled ones may be allowed to access with similar priority, under particular conditions, e.g., if the traffic type they transmit is the same or higher than the one for which the schedule has been set up.

[0032] The described implementation is an implicit indication that STA2 should defer the transmission, because the effective duration for which it is allowed to transmit is smaller than the smallest duration, which would be required for a transmission. An explicit implementation can, however, be designed in the form of a defer to send frame, which indicates as first duration the duration for which STA2 should not transmit, and, optionally, scheduling information in the form of second duration indicating the start of the scheduling intervaland the TID, indicating the TID for which the scheduling interval is set. AP2 may indicate to the STA2, that if STA2 has traffic corresponding to the TID or higher, then it may re-at- tempt channel access after the second duration. In particular, this operation requires scheduling information from AP1 , indicating that the schedule is not full and STAs other than the scheduled STAs may access under particular conditions on the traffic type.

[0033] The STAs (shown is only STA1) participating in the schedule are allowed to start contending at the Teff border. STA2 and other STAs not participating in the schedule, can only start contention at the expiration of the Ts border. Thus, in this way AP2 is extending the start protection of the schedule of AP1 within its BSS. To start transmitting during the TXOP, AP1 sends a trigger frame (TF) 303, in response to which STA1 starts transmitting data, e.g., in the form of one or more PPDll(s) 304, which may contain data and / or control information and which may be trigger-based (TB-) PPDll(s).

[0034] Fig. 5 shows a schematic diagram of a second embodiment of a communication scheme 400 according to the present disclosure, in particular for use if DPresp - TXTIME(sTXOP) > responseMPDUmin).

[0035] Similar to the first embodiment shown in Fig. 4, the sTXOP indication 302 indicates the two pieces of duration information Ts and Tetr, where Ten has the practical significance for STA2, that it can use the TXOP for a time corresponding to Teff. The sTXOP indication 302 further indicates the TID for which the rTWT was set up and scheduling information of the SP. After the sTXOP indication 302, STA2 can use the Ten duration to send data to the AP2, either directly or after a short response PPDll, depicted as rPPDll 305 (herein also referred to as sTXOP response).

[0036] The rPPDll 305, which can be just a simple CTS frame, with the adapted duration, indicates that STA2 accepts the AP2 suggestion and may be needed particularly in the case in which the sTXOP is used to start a new TXOP rather than directly continuing the TXOP initiated by the STA2. Additionally, rPPDll 305 may contain an indication 306 of whether LL traffic with stringent delay constraints is queued, which is impacted by the incomingschedule. If this is not the case, the rPPDll 305 is followed by the transmission of data 307 and, optionally, an acknowledgement (Ack) exchange as needed (not shown).

[0037] The simplest implementation of this behavior is the use of a modified CTS, which adjusts the duration to the maximum allowed TXOP duration, based on scheduling information (e.g., start of the scheduling interval). In this case only one duration information can be indicated (Ts= Teff) and there is no possibility to extend the protection inside the scheduling interval. For this particular case, the rPPDll 305 can be omitted, as no further confirmation to the modified CTS is necessary. This option is less versatile than the solution depicted in Fig. 5, and it cannot be easily extended to adjust in case STA2 has LL traffic requirements.

[0038] If STA2 has the capability to understand and operate based on sTXOP frames, Ts can correspond to the minimum between a duration D1 , equaling the updated duration of the originally requested TXOP and a duration D2, equaling the remaining duration until the start of the SP boundary 310 plus a maximum tolerable delay for the start of the scheduled traffic as indicated in e.g. scheduling Information. STA2 shall respect the request from AP2 that the effective use of the TXOP by STA2 for any traffic with TID < the TID for which the schedule was defined is only for a duration corresponding to Tetr, which should be also the duration indicated in the rPPDll 305 unless further conditions apply as elaborated further below.

[0039] If STA2 does not have the capability to operate based on the new behavior introduced by sTXOP but can operate based on TXOP Sharing initiated by an Mll-RTS, then sTXOP can be implemented as an Mll-RTS with TXOP Sharing field set to 1 , and indication of T eff.

[0040] Fig. 6 shows a schematic diagram of a third embodiment of a communication scheme 500 according to the present disclosure, in particular for use if only acknowledgments would overlap to rTWT(AP1 , STA1). Since, the acknowledgements are in general short frames, these may be allowed to be transmitted after the scheduling interval boundary. In particular, as shown in Fig. 6, the acknowledgement (BAck) 308 can be transmitted after theboundary 310 of the rTWT start. Alternatively, if the prerequisites for a coordinated SR transmission are met, i.e. , signal-to-interference-plus-noise-ratio (SINR), pathloss or received signal strength indicator (RSSI) levels of the links between AP2 to STA2 and AP1 to STA1 , are available. AP2 can adjust a transmission power such that no potential interference at the STAs within the schedule is produced. In this case, the Acknowledgements or other remaining frames could be sent after the boundary of the scheduling interval, without creating interference to the scheduled communication.

[0041] Fig. 7 shows a schematic diagram of a fourth embodiment of a communication scheme 600 according to the present disclosure, in particular for use if STAs have the capability to understand the sTXOP indication 302 but cannot comply with an adjusted TXOP at a particular moment in time. STA2 may inform this, in the rPPDll 305, particularly in the Ind flag 306. If AP2 receives the rPPDll 305 with this setting of the Ind flag 306, or if AP2 does not receive any response from STA2 (in particular not within a wait time), then it stops the adjusted TXOP, e.g., by transmitting a contention free (CF) end frame 309.

[0042] Fig. 8 shows a schematic diagram of a fifth embodiment of a communication scheme 700 according to the present disclosure, in particular for use if QoS information is available about potential LL traffic with stringent delay constraints and scheduling information indicates that the scheduled interval is not full. Similar to the previous embodiments, Ts, referred to as third time duration T in this embodiment (which may also be regarded as another implementation of the first time duration), can be defined as the updated duration of the originally requested TXOP or as the minimum between a duration D1 , equaling the updated duration of the originally requested TXOP, and a duration D2, equaling the remaining duration until the start of the SP boundary 310 plus optionally a maximum tolerable delay for the start of the scheduled traffic as indicated in e.g. scheduling information. Ten is the effective time in which a traffic can be exchanged, regardless of the traffic type e.g., also for TIDs smaller than the ones for which the rTWT was defined.

[0043] If the intended traffic for which the sTXOP was requested was Low Latency with stringent delay constraints, STA2 may be allowed to continue beyond the boundary 310 of the SP, and consequently Ten. Particularly this operation may be possible if the scheduling information of the established TWT indicates that the SP is not full. Alternatively, AP1 mayindicate allowance for such a behavior, depending on the status of the rTWT(AP1 , STA1), e.g., traffic requirements. If the schedule is full or the delay requirements indicated within the rTWT setup would be violated, then STA2 may not be allowed within the SP, e.g. by setting the Ts to the boundary 310 of the rTWT.

[0044] Fig. 9 shows a schematic diagram of a sixth embodiment of a communication scheme 800 according to the present disclosure, in particular for use with overlapped transmission. This embodiment represents an alternative implementation to the fifth embodiment 700 shown in Fig. 8. After the sTXOP indication 302, AP2 requests only information about the traffic for which the TXOP was obtained. If the traffic is low latency, a further adjusted TXOP will be initiated and a further TXOP indication 311 , e.g. , an Mll-RTS frame or another sTXOP frame, will be transmitted, which allows the traffic of STA2 and protects the start of the schedule of AP1 . More specifically, this is a further TXOP with duration Ts,2=Teff,j+Tp, where Tpis ignored by the members of the rTWT. Teff,i, which is also referred to a fourth time duration, has essentially a similar meaning to Teff, i.e. , the effective time that the STA2 can use the medium within the TXOP. The subscript “i” is only used to clarify that in this case the LL traffic is not allowed to extend beyond the Teff duration. This is then giving priority to the members of the scheduled interval to access. STA2 may then transmit the further data 307 beyond the boundary 310. Ts,2 has similar definition as Ts, i.e., it represents a duration during which STAs other than STA2 and the scheduled STAs (STA1) should consider the medium busy. In this context it shall be noted that sTXOP can be implemented using the Mll-RTS framework, i.e., in an implementation an sTXOP may be a (modified) Mll-RTS.

[0045] In the implementation shown in Fig. 9, the Mll-RTS 311 may require a new contention, and, if sTXOP follows an implementation similar to Mll-RTS, i.e., initiating a new TXOP for the rPPDll transmission, then there may be delays and an increase in the probability that the traffic delivery may not be possible because AP2 does not gain access to the medium. The rPPDll 305 shall be allowed as long as possible to increase the probability that the Mll-RTS 311 gets fully transmitted (basically if is transmitted close to the border 310 of the rTWT).

[0046] A more efficient implementation in this case can be to allow the first adjusted TXOP (i.e. , the one initiated by sTXOP 302) until close to the rTWT boundary 310 and start the MU- RTS 311 as close to the start of the schedule as possible. Due to already defined protection mechanisms by the AP1 , the STAs belonging to AP1 should stop their TXOPs at the boundary of the TXOP or refrain from accessing if the condition cannot be respected. Thus, fewer STAs from the oBSS (of AP1 and STA1) contend for the channel at that point. Also, due to the TXOP in place by the AP2, STAs belonging to BSS and oBSS may not have sufficient time to win contention. Therefore, the probability that the contention for the shared TXOP is successful is increased.

[0047] The TXOP started by the adapted Mll-RTS 311 is not a shared TXOP per se, as it only indicates a protection interval after Tetr, in which only STAs belonging to the schedule may contend. However, it can be easily adapted to the purpose of the present disclosure because it already contains the two duration indications.

[0048] Fig. 10 shows a schematic diagram of a seventh embodiment of a communication scheme 900 according to the present disclosure, in particular for use with power adjustment. Assuming overlapped transmission with adjusted power parameters can be performed within the rTWT, then AP1 and STA1 can start faster the operation in the rTWT, as it is depicted in Fig. 10. Based on the Mll-RTS 311 and the PPDll 307 sent by AP2 and STA1 respectively, interference levels to these STAs can be computed, e.g. , by performing power measurements by AP1 as indicated by the arrows 312 in Fig. 10. Based thereon, it can be inferred if, e.g., AP1 can start the transmission to STA1 with adjusted power level for the data exchange between AP1 and STA1. Hence, it can be checked if an overlap with power adjustment works. In this case, there is no need for AP1 to delay the start of the rTWT and the two data exchanges can be performed in parallel, i.e., the rTWT can start as planned and the NAV from AP2 can be ignored by STA2.

[0049] To facilitate this implementation, the Mll-RTS 311 may further contain information on the UL and DL SINR levels from and respectively to STA2, such that AP1 can adjust the transmit power of the TF 303. The Mll-RTS 311 may need to inform of SINR levels from the STAs in the schedule interval, if this information has been gathered in a coordinated measurement phase, performed before the respective TXOP.

[0050] Fig. 11 shows a schematic diagram of an eighth embodiment of a communication scheme 1000 according to the present disclosure, in particular for use with coordinated Time Division Multiple Access (TDMA). According to this embodiment, AP2 may alternatively create a further adjusted TXOP 313 with a duration Ts,2=Teff+Tsp, where TSP corresponds to the duration or partial duration of the scheduling interval. After the Ten boundary 310, the TXOP is handed over by an indication frame, depicted as handover (HO) frame 314, to AP1. AP1 uses the remaining part of the TXOP as a regular trigger-based SP.

[0051] Fig. 12 shows a schematic diagram of a ninth embodiment of a communication scheme 1100 according to the present disclosure, in particular for avoiding increased contention time. The embodiments 700, 800 and 900 described with reference to Figs. 8-10 comprise essentially two transmit opportunities because AP2 cannot know initially for sure for which traffic type STA2 has requested the TXOP and avoids deferring low latency streams. However, this design can incur some delays due to increased contention time.

[0052] In this case, AP2, upon receiving the RTS 301 from STA2 initiates a TXOP and transmits the sTXOP indication 302 with potentially the requested duration or a maximum allowed duration i.e., not exceeding the maximum delay tolerance at AP1. The Tetr, as before, indicates the effective time STA2 can use for transmitting the PPDll 307.

[0053] If STA2 indicates it has remaining low latency traffic at the Ten boundary 310, AP2 will trigger it by sending another PPDll 315 at Ten boundary 310, denoted as continuation PPDll (cPPDll). This PPDll 315 can be any type of trigger frame or a simplified sTXOP frame. The duration can extend until end of Ts. If the traffic duration is less than the Ts boundary, the initiated TXOP can be handed over to AP1 . Thus, the initiated TXOP is a shared TXOP. Similar to the description of Fig. 10, power measurements can be performed and AP1 can start the operation faster in the scheduled interval. This embodiment may be more versatile than the embodiment illustrated in Fig. 8 as it allows a coordinated operation during the scheduling interval.

[0054] The cPPDU can act as a frame indicating to AP1 that it can use the remaining duration of the TXOP under certain conditions. In general, a cPPDU indicates how the remaining partof the TXOP, in particular the one after the boundary of the scheduled communication, will be used. It can indicate one or more of the following: a termination of the TXOP if TID or traffic priority of the remaining traffic is lower than that of the scheduled traffic; a continuation of the TXOP with adjusted transmit parameters, e.g., reduced transmit power, more robust MOS in order to keep interference towards the scheduled communication devices below a threshold; indication of parameters, in particular interference levels or reception levels or spatial reuse parameters, based on which STA2 can determine adapted transmit parameters e.g., transmit power; a continuation of the TXOP, if the remaining traffic of the STA2 has a similar or higher priority to the one in the scheduled interval;-an indication to the AP1 that it can use the remaining part of the TXOP for the scheduled communication.

[0055] The cPPDll frame should not be sent later than the start of the scheduling interval, but it may be sent before the start of the scheduling interval, in order to ensure a timely start of the scheduled communication. Thus, a cPPDll frame may be sent within an interval [t1, t2], where t1=rTWT_start-TXTIME(cPPDU) and t2=rTWT_start+Margin. rTWT_start is the start time of the scheduled interval, TXTIME(cPPDU) is the processing time of the cPPDll frame and Margin is a tolerance margin, which can be defined in a standard.

[0056] If traffic for which the TXOP was obtained was not low latency, at the Ten boundary 310 AP2 can hand over the TXOP to AP1 (similar to the operation illustrated in Fig. 11) and can indicate a continuation with reduced power and frame alignment, if AP1 allows and SINR levels have been obtained by all STAs.

[0057] In summary, AP2 sets up a TXOP or adjusts a TXOP with parameters depending on a scheduling interval between a neighbor AP and its STAs. These parameters may include one or more of a first duration Ts which is the duration based on which all STAs other than STA2 and the scheduled STAs update the NAV. It can be:• remaining duration until the start of the scheduling interval;• remaining duration until the start of the scheduling interval plus a protection interval, wherein the protection interval may be ignored by the scheduled STAs in order to start contention; or• the minimum between (the updated duration requested by STA2) and remaining duration until the start of the scheduling interval plus a maximum delay tolerance, particularly in case AP2 has information about potential existence of an LL traffic stream with delay constraints; a second duration Teff, which is the duration that can be used by STA2 without other constraints.

[0058] AP2 may indicate to the STA2 that it may ignore Ten indication and use entire Ts duration of the TXOP, in case the TID of the traffic to be transmitted is larger or equal than the one indicated within the sTXOP frame. Further, AP2 may transmit to STA2 after the Ten boundary a downlink frame containing e.g., ACK, Back, or potential TXOP continuation indication under power constraints. Still further, AP2 may start the adjusted TXOP by transmitting a frame, indicating a shared transmit opportunity, based on which AP1 and associated STAs may compute adjusted transmit power to be used in a coordinated manner, and AP2 may handover the TXOP to the AP1 , within the Ts duration. Within the shared TXOP, after the first duration expires and there is remaining traffic of low latency category to be transmitted, AP2 may send a frame to indicate to the STA2 to continue the transmission until Ts boundary. Within the shared TXOP, after the first duration expires, AP2 may send a frame to indicate a continuation with adjusted transmission power.

[0059] The communications devices may be implemented by respective units or circuitry, e.g. a processor, processing circuitry, a computer, dedicated hardware, etc., that carries out the functions of the device. Alternatively, a common unit or circuitry, e.g. a common processor or computer, may implement the various functions of the device, or separate units or elements may be used that together represent the circuitry.

[0060] Thus, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the presentdisclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present disclosure is intended to be illustrative, but not limiting of the scope of the disclosure, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, defines, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

[0061] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" 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 recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0062] In so far as embodiments of the disclosure have been described as being implemented, at least in part, by software-controlled data processing apparatus, it will be appreciated that a non-transitory machine-readable medium carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure. Further, such a software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0063] The elements of the disclosed devices, apparatus and systems may be implemented by corresponding hardware and / or software elements, for instance appropriate circuits or circuitry. A circuit is a structural assemblage 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. Further, a circuit includes central processing units, graphics processing units, and microprocessors which are programmed or configured according to software code. A circuit does not include pure software, although a circuit includes the above-described hardware executing software. A circuit or circuitry may be implemented by a single device or unit or multiple devices or units, or chipset(s), or processor(s).

[0064] It follows a list of further embodiments of the disclosed subject matter:1 . First communication device configured to communicate with one or more second communication devices, the first communication device comprising circuitry configured to obtain schedule parameters of a scheduled communication set up by a third communication device; receive a request for a transmission opportunity (TXOP) from a second communication device; set up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmit an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.2. First communication device according to any preceding embodiment, wherein the circuitry is further configured to use the adapted TXOP parameters for the requested TXOP or a newly initiated TXOP.3. First communication device according to any preceding embodiment, wherein the circuitry is further configured to adapt the TXOP parameters based on one or more of: the start time of the scheduled communication, in particular if the third communication device has a scheduled communication with a planned start time overlapping with the requested TXOP, the status of the scheduled communication, in particular if it is active or idle, for which traffic identifiers it is set up, if it is set up for downlink and / or uplink traffic, and / or if there are any constraints on the maximally tolerable start delay, and traffic requirements of the second communication device, from which the TXOP request is received.4. First communication device according to any preceding embodiment, wherein the circuitry is further configured to obtain traffic requirements from the second communication device by one or more ofestablishing with the second communication device, prior to the requested TXOP, a stream classification service, SCS, stream including one or more of a low latency traffic indication, delay constraints of the respective traffic, and an indication of the lifetime of a MAC service data unit, MSDll; an indication, received prior to the requested TXOP, from the second communication device indicating that it has traffic with stringent delay bounds and / or traffic which should be sent within a transmission interval; and requesting information on the traffic type to be transmitted within the requested TXOP, in particular a traffic identifier.5. First communication device according to embodiment 4, wherein the circuitry is further configured to give priority to traffic of the second communication device based on the obtained traffic requirements.6. First communication device according to any preceding embodiment, wherein the circuitry is further configured to include into the adapted TXOP parameters one or more of: a first duration information indicating a first duration for which non-scheduled communication devices, other than the second communication device, shall not access the channel, a second duration information indicating a second duration up to the start of the scheduled communication set up by the third communication device and / or indicating that for the second duration the second communication device can use the sTXOP for communication, and a traffic identifier for which the schedule of the third communication device has been set up and / or scheduling information indicating if the schedule is full and / or if the second communication device may access, in particular if conditions on the traffic type are met.7. First communication device according to embodiment 6, up to the start of the scheduled communication set up by the third communication device plus a protection interval, during which non-scheduled communication devices other than the second communication device shall refrain from accessing the channel, orup to the start of the scheduled communication interval plus a maximum tolerable delay, or up to the start of the scheduled communication interval plus the duration of the scheduled communication interval, or corresponding to the initially requested TXOP duration.8. First communication device according to embodiment 6, wherein the sTXOP contains signaling indicating to the scheduled communication devices that they shall not access the channel after the reception of the sTXOP indication for a duration equal to the first duration or for an interval starting from the reception of the sTXOP indication up to the start of the scheduled communication interval.9. First communication device according to embodiment 7, wherein, if the first duration corresponds to a duration up to the start of the scheduled communication interval plus the duration of the scheduled communication interval or the initially requested TXOP duration, the adapted TXOP parameters are used in a newly initiated TXOP, which is shared with the third communication device.10. First communication device according to embodiment 7, wherein, if the first duration corresponds to a duration up to the start of the scheduled communication interval plus the duration of the scheduled communication interval or the initially requested TXOP duration, the first communication device is configured to send a continuation indication after the expiration of the second duration, indicating one of: continue if the traffic to be transmitted has a TID corresponding to the one in the scheduling interval, continue the communication with the second device with adjusted power, end the TXOP if traffic has a TID smaller than the one in the scheduling interval or interference level towards scheduled devices cannot be guaranteed, and indicate the remaining time of the TXOP can be used by the third communication device.11. First communication device according to any one of embodiments 6 to 10,wherein the circuitry is configured to indicate if the second communication device is allowed to transmit for an interval longer than the second duration but shorter than or equal to the first duration if the traffic to be transmitted has the same or a higher traffic identifier or the same or higher priority as the one indicated in the scheduling information, and / or to indicate to the second communication device to defer channel access until a duration corresponding to the first duration indicated in the adapted TXOP parameters.12. First communication device according to any one of embodiments 6 to 11 , wherein the circuitry is configured to indicate to the second communication device to defer channel access until a duration corresponding to the first duration indicated in the sTXOP scheduling information.13. First communication device according to any preceding embodiment, wherein the circuitry is further configured to transmit, in response to traffic received from the second communication device, an acknowledgement to the second communication device after the start of the scheduled communication between the third communication device and one or more fourth communication devices, in particular with adjusted transmission power.14. First communication device according to any preceding embodiment, wherein the circuitry is further configured to end the adjusted TXOP if an sTXOP response has been received from the second communication device indicating that the second communication device cannot respect the adapted TXOP parameters or if no sTXOP response indicating that the second communication device accepts the adapted TXOP parameters and / or if the second communication device has traffic with low latency requirements has been received from the second communication device.15. First communication device according to any preceding embodiment, wherein the circuitry is further configured to include into the sTXOP indication a third duration information indicating a third duration beyond the start of the scheduled communication between the third communication device and one or more fourth communication devices and indicating that for this duration the second communication device is allowed to transmit traffic,wherein the third duration extends beyond the start of said scheduled communication not more than a tolerable delay of the start of the data communication between the third communication device and one or more fourth communication devices, and wherein the third duration information is included into the sTXOP indication if the scheduled communication is not full and / or if the third communication device indicated allowance of transmission of traffic beyond the start of the scheduled communication.16. First communication device according to any preceding embodiment, wherein the circuitry is further configured to set up, if the second communication device has traffic with low latency requirements, a further TXOP based on the obtained schedule parameters; and transmit a further TXOP indication of the further TXOP indicating a fourth duration plus a protection interval extending beyond the start of said scheduled communication allowing the second communication device to transmit traffic during the fourth duration.17. First communication device according to embodiment 16, wherein the circuitry is further configured to include into the further TXOP indication transmission information about communication with the second communication device, in particular information regarding adjusted transmission power and / or modulation coding scheme (MOS) to be used during remaining duration and / or signal-to-noise ratio.18. First communication device according to embodiment 16 or 17, wherein the circuitry is further configured to hand over the further TXOP to the third communication device after the fourth duration for use of the remaining part of the further TXOP by the third communication device.19. First communication device according to any preceding embodiment, wherein the circuitry is further configured to set up, if the second communication device has traffic with low latency requirements at the start of the scheduled communication between the third communication device and one or more fourth communication devices, a further TXOP; andtransmit a further TXOP indication of the further TXOP allowing the second communication device to transmit traffic during a fifth duration and signaling to the third communication device to delay the start of the scheduled communication for a fifth duration.20. First communication device according to any preceding embodiment, wherein the circuitry is configured that in case STA2 has low latency traffic, the transmission of the low latency traffic will not be cut, in particular if a valid second duration representing the effective time that second communication device can initially use the medium and a continuation decision, which is sent at the boundary of the second duration and which can be a decision to: continue if TID corresponds to the one from the scheduling interval; continue with adjusted transmit power If interference is not disturbing the scheduled communication devices; stop if TID is smaller than the scheduled TID and / or the interference level cannot be guaranteed; or hand over the TXOP to the third communication device at second duration border or within a time of the second duration border plus a maximum tolerable delay.21. Second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to transmit a request for a transmission opportunity (TXOP) to the first communication device; receive from the first communication device an sTXOP indication of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device; and use the adapted TXOP parameters for communication with the first communication device.22. Second communication device according to embodiment 21 , wherein the circuitry is configured to use the received adapted TXOP parameters to perform one of: to communicate with the first communication device for a duration corresponding to a second duration information;to communicate with the first communication device for a duration corresponding to a first duration if the exchanged traffic type has a TID which is higher or equal to the one indicated in the sTXOP indication; to transmit within the second duration and indicate if more traffic of a type corresponding to the identifier indicated in the sTXOP indication is in the queue; to continue communication with the first communication device for a duration larger than the second duration and smaller than the first duration if a continuation indication has been received from the first communication device; to continue communication with the first communication device with adjusted transmission parameters, in particular transmission power and / or modulation coding scheme (MCS) if indicated by the first communication device within the sTXOP or continuation indication; and to defer accessing the channel to communicate with the first communication device for an interval at least equal to the first or the second duration information.23. Second communication device according to embodiment 21 or 22, wherein the circuitry is configured to transmit, at the start of the communication with the first communication device, an sTXOP response indicating that the second communication device accepts the adapted TXOP parameters and / or if the second communication device has traffic with low latency requirements.24. Second communication device according to any one of embodiments 21 to 23, wherein the circuitry is configured to use the adapted TXOP parameters for communication with the first communication device if the sTXOP indication indicates that the second communication device can communicate with the first communication device despite of a scheduled communication set up by a third communication device.25. Second communication device according to any one of embodiments 21 to 24, wherein the circuitry is configured to use the adapted TXOP parameters for communication with the first communication device if the sTXOP indication indicates that the adapted TXOP should be used within an indicated interval which corresponds to one of the requested TXOP, an immediately succeeding TXOP, initiated by the first communication device or an interval signaled by the first communication device in the sTXOP indication.26. Second communication device according to any one of embodiments 21 to 25, wherein the circuitry is further configured to receive, included into the sTXOP indication, a third duration information indicating a third duration beyond the start of the scheduled communication between the third communication device and one or more fourth communication devices and indicating that for this duration the second communication device is allowed to transmit traffic, and transmit traffic during the third duration.27. First communication method of a first communication device configured to communicate with one or more second communication devices, the first communication method comprising: obtaining schedule parameters of a scheduled communication set up by a third communication device; receiving a request for a transmission opportunity (TXOP) from a second communication device; setting up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmitting an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.28. Second communication method of a second communication device configured to communicate with a first communication device, the second communication method comprising: transmitting a request for a transmission opportunity (TXOP) to the first communication device; receiving from the first communication device an sTXOP indication of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device; and using the adapted TXOP parameters for communication with the first communication device if the sTXOP indication indicates that the second communication device can communicate with the first communication device despite of a scheduled communication set up by a third communication device.29. A non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method according to embodiment 27 or 28 to be performed.30. A computer program comprising program code means for causing a computer to perform the steps of said method according to embodiment 27 or 28 when said computer pro-gram is carried out on a computer.

Claims

CLAIMS1 . First communication device configured to communicate with one or more second communication devices, the first communication device comprising circuitry configured to obtain schedule parameters of a scheduled communication set up by a third communication device; receive a request for a transmission opportunity (TXOP) from a second communication device; set up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmit an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.

2. First communication device according to claim 1 , wherein the circuitry is further configured to use the adapted TXOP parameters for the requested TXOP or a newly initiated TXOP.

3. First communication device according to claim 1 , wherein the circuitry is further configured to adapt the TXOP parameters based on one or more of: the start time of the scheduled communication, in particular if the third communication device has a scheduled communication with a planned start time overlapping with the requested TXOP, the status of the scheduled communication, in particular if it is active or idle, for which traffic identifiers it is set up, if it is set up for downlink and / or uplink traffic, and / or if there are any constraints on the maximally tolerable start delay, and traffic requirements of the second communication device, from which the TXOP request is received.

4. First communication device according to claim 1 , wherein the circuitry is further configured to obtain traffic requirements from the second communication device by one or more ofestablishing with the second communication device, prior to the requested TXOP, a stream classification service, SCS, stream including one or more of a low latency traffic indication, delay constraints of the respective traffic, and an indication of the lifetime of a MAC service data unit, MSDll; an indication, received prior to the requested TXOP, from the second communication device indicating that it has traffic with stringent delay bounds and / or traffic which should be sent within a transmission interval; and requesting information on the traffic type to be transmitted within the requested TXOP, in particular a traffic identifier.

5. First communication device according to claim 1 , wherein the circuitry is further configured to include into the adapted TXOP parameters one or more of: a first duration information indicating a first duration for which non-scheduled communication devices, other than the second communication device, shall not access the channel, a second duration information indicating a second duration up to the start of the scheduled communication set up by the third communication device and / or indicating that for the second duration the second communication device can use the sTXOP for communication, and a traffic identifier for which the schedule of the third communication device has been set up and / or scheduling information indicating if the schedule is full and / or if the second communication device may access, in particular if conditions on the traffic type are met.

6. First communication device according to claim 5, wherein the first duration is a duration up to the start of the scheduled communication set up by the third communication device plus a protection interval, during which non-scheduled communication devices other than the second communication device shall refrain from accessing the channel, or up to the start of the scheduled communication interval plus a maximum tolerable delay, orup to the start of the scheduled communication interval plus the duration of the scheduled communication interval, or corresponding to the initially requested TXOP duration.

7. First communication device according to claim 6, wherein, if the first duration corresponds to a duration up to the start of the scheduled communication interval plus the duration of the scheduled communication interval or the initially requested TXOP duration, the adapted TXOP parameters are used in a newly initiated TXOP, which is shared with the third communication device.

8. First communication device according to claim 6, wherein, if the first duration corresponds to a duration up to the start of the scheduled communication interval plus the duration of the scheduled communication interval or the initially requested TXOP duration, the first communication device is configured to send a continuation indication after the expiration of the second duration, indicating one of: continue if the traffic to be transmitted has a TID corresponding to the one in the scheduling interval, continue the communication with the second device with adjusted power, end the TXOP if traffic has a TID smaller than the one in the scheduling interval or interference level towards scheduled devices cannot be guaranteed, and indicate the remaining time of the TXOP can be used by the third communication device.

9. First communication device according to claim 5, wherein the circuitry is configured to indicate if the second communication device is allowed to transmit for an interval longer than the second duration but shorter than or equal to the first duration if the traffic to be transmitted has the same or a higher traffic identifier or the same or higher priority as the one indicated in the scheduling information, and / or to indicate to the second communication device to defer channel access until a duration corresponding to the first duration indicated in the adapted TXOP parameters.

10. First communication device according to claim 1 ,wherein the circuitry is further configured to transmit, in response to traffic received from the second communication device, an acknowledgement to the second communication device after the start of the scheduled communication between the third communication device and one or more fourth communication devices, in particular with adjusted transmission power.

11. First communication device according to claim 1 , wherein the circuitry is further configured to end the adjusted TXOP if an sTXOP response has been received from the second communication device indicating that the second communication device cannot respect the adapted TXOP parameters or if no sTXOP response indicating that the second communication device accepts the adapted TXOP parameters and / or if the second communication device has traffic with low latency requirements has been received from the second communication device.

12. First communication device according to claim 1 , wherein the circuitry is further configured to set up, if the second communication device has traffic with low latency requirements, a further TXOP based on the obtained schedule parameters; and transmit a further TXOP indication of the further TXOP indicating a fourth duration plus a protection interval extending beyond the start of said scheduled communication allowing the second communication device to transmit traffic during the fourth duration.

13. First communication device according to claim 12, wherein the circuitry is further configured to include into the further TXOP indication transmission information about communication with the second communication device, in particular information regarding adjusted transmission power and / or modulation coding scheme (MOS) to be used during remaining duration and / or signal-to-noise ratio.

14. Second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to transmit a request for a transmission opportunity (TXOP) to the first communication device;receive from the first communication device an sTXOP indication of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device; and use the adapted TXOP parameters for communication with the first communication device.

15. Second communication device according to claim 14, wherein the circuitry is configured to use the received adapted TXOP parameters to perform one of: to communicate with the first communication device for a duration corresponding to a second duration information; to communicate with the first communication device for a duration corresponding to a first duration if the exchanged traffic type has a TID which is higher or equal to the one indicated in the sTXOP indication; to transmit within the second duration and indicate if more traffic of a type corresponding to the identifier indicated in the sTXOP indication is in the queue; to continue communication with the first communication device for a duration larger than the second duration and smaller than the first duration if a continuation indication has been received from the first communication device; to continue communication with the first communication device with adjusted transmission parameters, in particular transmission power and / or modulation coding scheme (MCS) if indicated by the first communication device within the sTXOP or continuation indication; and to defer accessing the channel to communicate with the first communication device for an interval at least equal to the first or the second duration information.

16. Second communication device according to claim 14, wherein the circuitry is configured to transmit, at the start of the communication with the first communication device, an sTXOP response indicating that the second communication device accepts the adapted TXOP parameters and / or if the second communication device has traffic with low latency requirements.

17. Second communication device according to claim 14,wherein the circuitry is further configured to receive, included into the sTXOP indication, a third duration information indicating a third duration beyond the start of the scheduled communication between the third communication device and one or more fourth communication devices and indicating that for this duration the second communication device is allowed to transmit traffic, and transmit traffic during the third duration.

18. First communication method of a first communication device configured to communicate with one or more second communication devices, the first communication method comprising: obtaining schedule parameters of a scheduled communication set up by a third communication device; receiving a request for a transmission opportunity (TXOP) from a second communication device; setting up, based on the obtained schedule parameters, adapted TXOP parameters for an adjusted TXOP (sTXOP) for use by the second communication device; and transmitting an sTXOP indication of the sTXOP indicating the adapted TXOP parameters to the second communication device.

19. Second communication method of a second communication device configured to communicate with a first communication device, the second communication method comprising: transmitting a request for a transmission opportunity (TXOP) to the first communication device; receiving from the first communication device an sTXOP indication of an adjusted TXOP (sTXOP) with adapted TXOP parameters for use by the second communication device; and using the adapted TXOP parameters for communication with the first communication device if the sTXOP indication indicates that the second communication device can communicate with the first communication device despite of a scheduled communication set up by a third communication device.

20. A non-transitory computer-readable recording medium that stores therein a computer program product, which, when executed by a processor, causes the method according to claim 18 or 19 to be performed.

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