Communication devices and methods

Abstract

A first communication device that is configured to communicate with a second communication device comprising circuitry configured to schedule a service period for a second communication device to communicate with the first communication device; to transmit service period information indicating that the second communication device is entitled to communicate with the first communication device during the service period and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and to listen for data transmitted from the second communication device during the service period.

Description

COMMUNICATION DEVICES AND METHODSBACKGROUNDFIELD OF THE DISCLOSURE

[0001] The present disclosure relates to first and second communication devices and methods.DESCRIPTION OF RELATED ART

[0002] The delivery of low-latency data traffic requires scheduling from a central node, in particular an access point (AP), in a network. Especially for uplink traffic, i.e. , the case when a subscriber node, i.e., a station (STA), transmits to the AP, an advance notification about the average traffic characteristics is needed. After that, according to prior art, triggered channel access is applied in which the AP solicits an uplink data unit from a STA. The useof trigger frames to enable uplink traffic comes, however, with drawbacks including undesired overhead the need to add further parameters into the trigger frame. Those parameters are often unknown to the AP for which reason the AP needs to guess or overdesign such parameters.

[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 enable the delivery of low-latency data traffic with fewer drawbacks compared to the use of trigger frames. It is a further object to provide corresponding communication devices and methods 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 methods.

[0005] According to an aspect there is provided a first communication device configured to communicate with a second communication device, the first communication device comprising circuitry configured to: schedule a service period for a second communication device to communicate with the first communication device; transmit service period information indicating that the second communication device is entitled to communicate with the first communication device during the service period and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and listen for data transmitted from the second communication device during the service period.

[0006] According to another aspect there is provided a second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to: receive service period information from the first communication device indicating that the second communication device is entitled to communicate with the first communication device during a service period scheduled by the first communication device and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and transmit data to the first communication device during the service period.

[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 method 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 method 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 to use regular channel access instead of a triggered channel access. The regular channel access is scheduled by the AP (herein also denoted as first communication device) to avoid simultaneous channel access by various STAs (potentially ending in a collision). The AP allocates a service period (SP) such that it fulfills necessary requirements (e.g. as part of QoS characteristics in a setup phase) of the STA (herein also denoted as second communication device). The AP allocates a SP to the STA e.g. via an SP request, and the STA may optionally confirm via SP response. Following the allocation, the STA can access the channel and transmit data without waiting for a trigger to be sent from the AP.

[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 an embodiment of a known communication scheme between an STA and an AP.Fig. 2 shows a diagram of a first embodiment of a communication scheme according to the present disclosure.Fig. 3A shows a diagram of an exemplary communication scheme representing a combination of the communication schemes and shown in Figs. 1 and 2.Fig. 3B shows a diagram of a communication scheme in which collision occurs.Fig. 4 shows a flow chart of an embodiment of a communication method of the STA according to the present disclosure.Fig. 5 shows a flow chart of an embodiment of a communication method of the AP according to the present disclosure.Fig. 6A shows a diagram of an embodiment of a communication scheme according to the present disclosure that illustrates the case when a STA signals uplink traffic of a certain TID.Fig. 6B shows a diagram of an embodiment of a communication scheme according to the present disclosure that illustrates the case when the STA signals downlink traffic of a certain TID.Fig. 7 shows a diagram of an embodiment of a communication scheme illustrating the use of different channel access delay values for different STAs that are allowed to transmit in the same SP.Fig. 8A shows a diagram of a first embodiment of SP setup using SP request and SP response.Fig. 8B shows a diagram of a second embodiment of SP setup using SP request and SP response.Fig. 9A shows a diagram illustrating a combined QoS Characteristics and SP request transmission.Fig. 9B shows a diagram illustrating separate QoS Characteristics and SP request transmission.Fig. 10 shows diagrams of two further embodiments of separate SP request and QoS Characteristics transmission.Fig. 11 shows a diagram of another embodiment of a communication scheme according to the present disclosure illustrating how the AP can schedule the service period under consideration of the received QoS characteristics.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] The scheduling of low-latency data units is very important to deliver those data units with high quality of service (QoS) and / or good user experience meaning that expectations in terms of timely delivery and / or reliability to those data units are met. As illustrated in Fig. 1showing a diagram of an embodiment of a known communication scheme 10 between an STA and an AP, the STA that has low-latency data units to transmit to AP may inform the AP about the requirements of its low-latency data units for both downlink (AP -> STA) and uplink (STA -> AP). These requirements are transmitted as part of QoS Characteristics indication 11. The AP considers this information in terms of scheduling, e.g., which data units to transmit first, such that those data units are delivered within a minimum service interval (minSI) and maximum service interval (maxSI). For uplink traffic provisioning, the AP acts such that, within this interval, it transmits a trigger frame 12 to the STA for the STA to respond within SIFS (short interframe spacing) with actual uplink data units 13. The AP often indicates status of received uplink data with a (B)Ack 14 (Block-Acknowledgement) transmitted within SIFS as a response to the uplink data units.

[0013] In fact, the QoS Characteristics indication 11 may hold various parameters as outlined in the following. In WLAN, the first four parameters are mandatory to include to any QoS Characteristics signaling: Minimum Service Interval, Maximum Service Interval, Minimum Data Rate, Delay Bound (= maximum acceptable latency), Maximum MSDll Size (= size of a data unit), Service Start Time (= start time of initial service), Mean Data Rate, Burst Size, MSDll Lifetime, MSDU Delivery (success) Ratio, MSDU Count Exponent, and Medium Time.

[0014] In the following, uplink traffic is considered only, because downlink traffic can be scheduled by the AP in an implementation-specific way so that no standardization is needed.

[0015] The use of trigger frame to enable uplink traffic as shown in Fig. 1 comes with multiple drawbacks. A first drawback is that the exact size of the data units to be transmitted must be known and included by the AP in the trigger frame. For this reason, often two “trigger frame, uplink data and BAck” frame exchanges are performed: The first one is for the AP to obtain size of data units (buffer status) and the second one is for the actual uplink data exchange. This clearly creates a significant amount of overhead that is not desired. A second drawback is that transmit parameters, such as MCS (modulation coding scheme), that shall be used by the STA must be included by the AP in the trigger frame. A third drawback is that the STA has no control over the potential retransmission and must rely on theAP to trigger it again to retransmit erroneous data units. A fourth drawback is that, if transmitted within a service period such as a TWT (Target Wake Time) or R-TWT (restricted TWT) SP, two trigger frames are needed. The first trigger frame is needed to ensure that the target STA is awake, indicated by a short response (not shown in Fig. 1) and the second trigger frame to solicit the uplink data unit (as shown in Fig. 1). This part is illustrated in Fig. 3A.

[0016] The first three drawbacks result from the fact that the AP does not know a STA’s preferred settings, because such data is only available at STA side. The only way for the AP to decide is to rely on information within the QoS Characteristics element that is of type average value. STA’s immediate preference such as selecting a lower MCS for more reliability in a retransmission for example cannot be considered. The fourth drawback exists because the AP cannot know if a STA is listening when triggering due to power save mode.

[0017] According to the present disclosure, the STA uses regular channel access instead of a triggered channel access. Fig. 2 shows a diagram of a first embodiment of a communication scheme 20 according to the present disclosure. The regular channel access shall be schedulable by the AP to avoid simultaneous channel access for various STAs. Therefore, the initial step of QoS Characteristic signaling 21 from STA to AP may be the same as in Fig. 1. However, subsequently the AP allocates a service period (SP) such that it fulfills the requirements signaled in QoS characteristics. The AP allocates a SP to the STA via an SP request 22 and the STA may optionally confirm via SP response 23. In the embodiment shown in Fig. 2, the AP allocates the SP such that it lies in between minimum and maximum service interval. The SP request 22 thus represents or contains service period information indicating that the STA is entitled to communicate with the AP during the SP and that the STA should (or is allowed to) initiate a transmit opportunity with the AP without being triggered by the AP. The AP then listens for data transmitted from the STA during the SP, which may include to transmit from time to time, e.g. a response (e.g. (B)Ack 25), to the STA.

[0018] At the beginning of an SP, the STA may use regular distributed channel access (EDCA - enhanced distributed channel access) to access the channel to transmit uplink data (which may include to receive from time to time, e.g. a response, to the AP, e.g. (B)Ack,25). In contrast to the known communication scheme, the AP performs no action at the beginning of the SP. By doing so a STA is very flexible about how to transmit as long as the SP is not exceeded. The uplink data 24 may be followed by a BAck 25. If there is remaining time in the SP, the STA may terminate it by appropriate signaling or use it for other traffic, e.g. non-low latency traffic.

[0019] An SP is reserved in such a way that any communication device that is aware of the SP schedule stops its transmission before the SP begins, at the latest just before the SP begins; hence, the likelihood that the STA may access the channel is high. If the SP is of type TWT SP, the beginning of the SP may be soft, i.e., some delay may be present. If the SP is of type R-TWT SP, the beginning of the SP is tight. Furthermore, the scheduling of an SP is often persistent and / or reoccurring such that the initiation by SP request / re- sponse in Fig. 2 creates only minor overhead. In other words, the service period information transmitted by the AP indicates to other STAs (i.e. STAs not entitled to transmit during the SP) to stop their transmit opportunity before the start of the SP and not to start a transmit opportunity during the SP.

[0020] In order for a STA to be able to transmit right after the SP begins, it should be aware of the channel conditions in terms of network allocation vector (NAV). The NAV may be included in all (received) frames and indicates the duration until the end of the current frame exchange or transmit opportunity. Therefore, a STA using the disclosed mechanism shall either be awake all the time or if it is in doze mode, it shall be awake at least NAVSyncDelay, a predefined time duration, before the SP begins. Some STAs may be awake in SPs only and consideration of NAVSyncDelay is important to be compliant with WLAN channel access rules after a power save period.

[0021] One aspect arises from the fact that in triggered channel access as shown in Fig. 1 , the AP may choose to allocate an SP to protect its trigger frame as illustrated in Fig. 3A showing a diagram of an exemplary communication scheme 30 representing a combination of the communication schemes 10 and 20 shown in Figs. 1 and 2 (and additionally comprising a first trigger 31 , a step 32 of transmitting a buffer status I awake signaling by the STA in response to the first trigger 31 and a step 33 of (B)Ack in response to step 32).

[0022] In this scheme 30 the STA needs to know what it should do at the beginning of a SP, either wait to be triggered by the AP or perform channel access on its own. Otherwise, if the STA’s role is not clear, a collision may often arise because AP and STA may access the channel at the same time as illustrated in Fig. 3B showing a diagram of a communication scheme 40 in which collision occurs. As any collision comes with latency to resolve the collision, this behavior is not desired and shall be avoided by the present disclosure.

[0023] Therefore, in the setup of an SP, the AP may, in an embodiment of the present disclosure, specify the desired channel access type to either trigger-based channel access by AP or distributed channel access by STA, e.g. by transmitting channel access information indicating the desired channel access type. A STA then acts accordingly, i.e., either waits to be triggered or performs channel access. Fig. 4 shows a flow chart of an embodiment of a communication method 50 of the STA according to the present disclosure. Initially (step 51) the STA is in a state of waiting for the beginning of the SP. If the SP is trigger-enabled, as checked in step 52, the STA waits for a trigger frame from AP (step 53) before it transmits uplink data (step 54), optionally acknowledged by (B)Ack (step 55), unless it has no data to transmit or the end of the SP is reached (step 56). If the SP in not trigger-enabled, the STA performs channel access (EDCA; step 57) and transmits uplink data (step 58), optionally acknowledged by (B)Ack (step 59), unless it has no more data to transmit or the end of the SP is reached (step 60). The coarse dashed parts (steps 56 and 60) are optional and show the termination procedure. The fine dashed parts (steps 55 and 59) are used when a STA requested acknowledgement for the data units transmitted in uplink.

[0024] As shown in Fig. 4, when the duration of the transmit opportunity (TXOP) that was obtained by the STA in step 57 by EDCA ended, a new TXOP may need to be obtained. Otherwise, further uplink data may be transmitted right after a received (B)Ack.

[0025] Fig. 5 illustrates the related flow chart of an embodiment of a communication method 70 of the AP. This flow chart does not include the operation according to Fig. 1, in which case there is only a trigger frame and no SP. Initially (step 71) the AP is in a state of waiting for the beginning of the SP. If the SP is trigger-enabled, as e.g. determined by the AP in step 72, the AP performs channel access (EDCA; step 73) and transmits a trigger frame to the STA (step 74) to trigger the STA to transmit uplink data received in step 75), optionallyacknowledged by (B)Ack (step 76), unless the STA has no data to transmit or the end of the SP is reached (step 77). If the SP in not trigger-enabled, the AP waits to receive uplink data from the STA (step 78). Once it receives uplink data (step 79) it may optionally acknowledge them by (B)Ack (step 80). If the STA has more data to transmit or the end of the SP is not yet reached (step 81), the process continues with step 78. Similar as in Fig. 4, the coarse dashed parts (steps 77 and 81) are optional and show the termination procedure. The fine dashed parts (steps 76 and 80) are used when a STA requested acknowledgement for the data units transmitted in uplink.

[0026] When the AP is allocating an SP (e.g. an R-TWT SP) in order for a STA to contend for channel access, the AP should make sure that the one or more traffic identifier (TID) which are signaled in the QoS Characteristics are enabled for the respective SP within the SP settings (e.g. R-TWT SP settings). Similarly, the AP shall identify the direction of traffic, i.e. downlink and / or uplink, by respective setting in the SP. It shall be noted that the direction of traffic refers to data units but not control units. For example, an AP may transmit a trigger frame although the SP is restricted to uplink.

[0027] By using this mechanism, the AP may steer at which time a STA transmits what type of traffic if the STA has traffic of several TIDs and / or traffic directions that are signaled within the QoS characteristics. If the traffic direction indicates downlink only, a STA shall not access the channel but wait for the AP to access the channel and deliver downlink data to the STA. In this regard, the STA is generally not completely free to transmit any type of data unit in steps 54, 57, and 58. Further, the initial step 51 refers to SPs that allow uplink data to be transmitted.

[0028] Fig. 6A shows a diagram of an embodiment of a communication scheme 90 according to the present disclosure that illustrates the case when a STA signals in QoS Characteristics 91 uplink traffic of TID x. The AP performs corresponding setup of the R-TWT SP and transmits a corresponding R-TWT SP request 92, optionally followed by an R-TWT SP response 93 from the STA. Once the R-TWT starts, the STA starts to contend for channel access and transmits the uplink data 94 of TID x, optionally followed by a (B)Ack 95.

[0029] Fig. 6B shows a diagram of an embodiment of a communication scheme 100 according to the present disclosure that illustrates the case when the STA signals downlink traffic of a certain TID 101 followed by a corresponding T-TWT SP request 102 and an optional R- TWT SP response 103. In this case the STA does not contend for channel access but waits for the AP to transmit data 104 (optionally followed by a (B)Ack 105) once the related R-TWT SP begins.

[0030] In order to avoid that downlink and uplink traffic are transmitted at same time, the AP may ensure according to an embodiment that only downlink or only uplink traffic is enabled in a R-TWT SP if the traffic is not trigger enabled. Otherwise, simultaneous channel access attempts by AP and STA may collide. Alternatively, the channel access delay mechanism described below may be used to avoid collisions.

[0031] Up to now, it was assumed that only a single STA is entitled to transmit in a SP and performs channel access when the SP starts. In case multiple STAs are entitled to transmit in a SP and both have similar TIDs, collisions may arise. To avoid such collisions, it is proposed in an embodiment to add within the SP setup a channel access delay value for each STA. The channel access delay value indicates a time span after the beginning of a SP that a STA shall wait until it starts channel access. Thus, STAs having zero or low channel access delay are prioritized compared to other STAs having a higher value of the channel access delay.

[0032] Fig. 7 shows a diagram of an embodiment of a communication scheme 110 illustrating the use of different channel access delay values for different STAs that are allowed to transmit in the same SP. As shown in Fig. 7, the AP allocates a respective channel access delay value D1 (step 112) to STA1 and D2 (step 115) to STA2 during scheduling. This may preferably be done after corresponding QoS Characteristics have been received (steps 111 and 114) from STA1 and STA2, respectively, and the STAs may respond with corresponding SP responses (steps 113 and 116).

[0033] Depending on the channel access delay value, the channel access procedure of counting down backoff time slots starts with a different delay. The backoff time may even be zerounder some circumstances. In the example illustrated in Fig. 7, it is assumed that both STAs draw the same backoff time of two slots, which would result in a collision when D1 would be equal to D2. However, because D1<D2, STA1 gets channel access first and starts transmitting (step 117) first (optionally followed by (B)Ack (step 118)). This is detected by STA2, which in turn suspends its channel access attempt (after one slot). Once the frame exchange of STA1 ended (as e.g. detected by STA2 from the (B)Ack (step 118), STA2 counts down its remaining backoff time (one slot) and accesses the channel afterwards, i.e. transmits data (step 119) and receives an (optional) (B)Ack (step 120).

[0034] The selection of the channel access delay may be decided by the AP based on the QoS characteristics of each STA. The STA that has traffic with highest priority indicated by the TID value and / or strictest delay constraints should be the one having a low or zero channel access delay. If several STAs have traffic with the highest priority, the AP can alternate the channel access delay among those STAs when changing from one SP to the next. Different delays can be given to each STA based on the level of priority indicated by their TIDs.

[0035] The AP can signal the channel access delay values within the SP setup, i.e., in the SP requests as shown in Fig. 7) or in an SP modification, as will be explained below, preferably after the QoS characteristics of one or all STAs that should be served in the same SP have been received. Further, the channel access delay values can be selected based on the channel access (EDCA) parameters used by the STAs in order to minimize the probability of a collision.

[0036] In the above explanation, in particular referring to Figs. 2-3, it was assumed that the AP, after it received QoS characteristics, allocates an SP by an SP request with appropriate settings that fit the created schedule. The STA may subsequently respond by an SP response. This is illustrated in Fig. 8A showing a diagram of a first embodiment of SP setup using SP request 120 (corresponding to step 22) and SP response 121 (corresponding to step 23). The SP response by the STA is optional, but it is often transmitted.

[0037] However, it is also possible that the STA requests an SP by an SP request 130 and the AP subsequently transmits an SP response 131 as illustrated in Fig. 8B diagram of a second embodiment of the SP setup. In this case, the SP response may always be sent by the AP.

[0038] Generally, the SP request holds parameters to indicate the desired SP configuration, whereas the SP response holds one or more of accept information, reject information, and / or an alternative suggestion.

[0039] There are generally different options for the point in time of the QoS Characteristics transmission or reception. As a first option the SP request is transmitted by the STA at same time as the QoS Characteristics. As a second option the SP request is transmitted by the STA after the QoS Characteristics. As third option the SP request is transmitted by the STA before the QoS Characteristics and the SP is aligned or modified to fit the QoS Characteristics once the related schedule is created by the AP.

[0040] According to the first option, the SP request may be included into the QoS Characteristics as shown in Fig. 9A showing a combined QoS Characteristics and SP request transmission 140 and an SP response 141. This option can be realized by the STA transmitting the SP request and the AP responding to it with the SP response. In case the AP cannot accept the suggested SP, it may suggest different parameters in which case at least another SP request and / or SP response is required by STA.

[0041] According to the second option, the SP request may be sent by the AP and the STA responds as shown in Figs. 2-3. Alternatively, the STA may transmit an SP request 151 after it has sent its QoS Characteristics 150 as shown in Fig. 9B. Afterwards, the AP may transmit an SP response 152. This option implies a certain risk that AP and STA transmit an SP request at the same time. To lower the collision risk, an improved signaling may be present in QoS Characteristics that defines if the AP or the STA sends the SP request and if the STA or the AP await the SP request, respectively.

[0042] According to the third option, as illustrated in Fig. 10 for two embodiments, the AP (Fig. 10A) or the STA (Fig. 10B) may transmit an SP request 160, 170 (optionally followed by an SP response 161 , 171) before any QoS Characteristics 162, 172 are received or transmitted. Such behavior may be required when an AP mandates any STA to setup a SP before transmitting any data. Therefore, such a SP request / response is often part of the (re)association process. The third option may also be appropriate if QoS Characteristics change such that the SP may be modified.

[0043] Once the AP received the QoS Characteristics, the AP may subsequently modify an existing SP to fit its properties to the signaled QoS characteristics. Such an SP modification may be done by another SP request 163, 173 by the AP and an optional SP response 164, 174 by the STA or by a different schedule announcement in a beacon frame transmitted by AP. Signaling within the beacon may point to the upcoming start time of an SP.

[0044] Fig. 11 shows a diagram of another embodiment of a communication scheme according to the present disclosure illustrating how the AP can schedule the service period under consideration of the received QoS characteristics. An SCS (stream classification service) request 180 is transmitted from the STA to the AP. The SCS request, optionally confirmed by an Ack 181 , carries one or more QoS Characteristics elements and a request to “Add” or “Change” or even “Remove”. The AP, after receiving the SCS request, decides if it can fulfill the request such that QoS Characteristics are met. Subsequently, it transmits a SCS response 182 to the STA, optionally confirmed by an Ack 183. The SCS response 182 includes a response indicating “Success” or “Decline”. If success, the AP creates at the same time a schedule to serve the STA according to its signaled needs. At any time, a STA can “change” or “terminate” its SCS request by running the same procedure as explained above. At any time, an AP can “terminate” an earlier accepted SCS request. Any SCS request and response may hold an ID (SCS ID) to identify and differentiate different requests. Further, the SCS request may hold identifiers indicating how data units belonging to the SCS request shall be identified.

[0045] In summary, according to the present disclosure a service period is allocated by the AP to the STA. The STA may use EDCA just after the allocated SP begins to deliver uplink dataunits. In contrast to triggered access, this approach does not require the AP to have detailed knowledge of a STA’s requirements such as modulation coding scheme and actual data length. Furthermore, the overhead of triggered access can be avoided, and channel access scheduling and protection are provided by the SP.

[0046] It is noted that it is referred herein to “SP request” and “SP response” in a temporal fashion, i.e. , the “SP request” is followed by a “SP response” if present. However, according to standard specifications, the “SP request” is generally transmitted from STA and the “SP response” is generally transmitted from AP as the STA is considered to be a SP requester and the AP is considered to be a SP responder. Often, an AP is called AP STA and an STA is referred to as non-AP STA.

[0047] According to embodiments, by use of the present disclosure there are different options for enabling the transmission of uplink data frames: by using Basic Trigger frames, or alternatively by using Mll-RTS TXS Trigger frames if both EHT STAs (extremely high throughput STAs) have dot1 lEHTTXOPSharingTFOptionlmplemented equal to true, or alternatively by aligning a negotiated R-TWT SP if the EHT STA is an r-TWT scheduled STA, or alternatively by aligning a negotiated TWT SP if the EHT STA is a TWT scheduled STA.

[0048] If the related TWT SP or R-TWT SP is trigger-enabled, the transmission of uplink data frames may be enabled by using Basic Trigger or MU RTS TXS Trigger frames. If the related TWT SP or R-TWT SP is not trigger-enabled, the transmission of uplink data frames may be initiated by the respective non-AP EHT STAs using EDCA and the EHT. The AP may ensure that TIDs contained in the QoS Characteristics element of the respective non- AP EHT STAs are enabled during the R-TWT SPs by appropriate setting within Restricted TWT UL TID Bitmap.

[0049] 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 present disclosure 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.

[0050] 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.

[0051] 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.

[0052] 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).

[0053] It follows a list of further embodiments of the disclosed subject matter:1. First communication device configured to communicate with a second communication device, the first communication device comprising circuitry configured to: schedule a service period for a second communication device to communicate with the first communication device; transmit service period information indicating that the second communication device is entitled to communicate with the first communication device during the service period and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and listen for data transmitted from the second communication device during the service period.2. First communication device as defined in embodiment 1, wherein the circuitry is further configured to indicate service period information that indicates to other communication devices to stop their transmit opportunity before the start of the service period and not to start a transmit opportunity during the service period.3. First communication device as defined in embodiment 1 or 2, wherein the circuitry is further configured to transmit, before the start of the service period, channel access information indicating whether or not a trigger will be transmitted after the start of the service period.4. First communication device as defined in any one of the preceding embodiments, wherein the circuitry is further configured to indicate, before the start of the service period, one or more traffic identifiers for which the service period is enabled and / or the allowed direction of communication between the first and second communication devices allowed during the service period.5. First communication device as defined in any one of the preceding embodiments,wherein the circuitry is configured to control if the second communication device is accessing the channel after the start of a service period by setting the direction of communication to uplink, uplink indicating data communication from the second communication device to the first communication device.6. First communication device as defined in any one of the preceding embodiments, wherein the circuitry is further configured to receive quality of service (QoS) characteristics from the second communication device and to schedule the service period under consideration of the received QoS characteristics.7. First communication device as defined in embodiment 6, wherein the circuitry is configured to transmit the service period information before, at the same time or after the QoS information is received from the second communication device.8. First communication device as defined in any one of the preceding embodiments, wherein the circuitry is configured to schedule the service period for use by one or more second communication devices to communicate with the first communication device and to transmit delay information indicating for the two or more second communication devices individual time spans after the start of the SP the respective second communication device shall wait before it is allowed to transmit data to the first communication device.9. First communication device as defined in embodiment 8, wherein the circuitry is configured to set the individual time span assigned to one second communication device to zero.10. First communication device as defined in embodiments 6 and 8, wherein the circuitry is configured to set the delay information for a second communication device based on the QoS information and / or distributed channel access parameters of said second communication device.11. First communication device as defined in any one of the preceding embodiments, wherein the circuitry is further configured toreceive a request from the second communication device to schedule a service period, and schedule the service period according to the request.12. First communication device defined in any one of the preceding embodiments, wherein the transmitted service period information indicates that the second communication device should initiate a transmit opportunity with the first communication device by using distributed channel access.13. Second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to: receive service period information from the first communication device indicating that the second communication device is entitled to communicate with the first communication device during a service period scheduled by the first communication device and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and transmit data to the first communication device during the service period.14. Second communication device as defined in embodiment 13, wherein the circuitry is further configured to transmit a service period confirmation to the first communication device in response to the received service period information from the first communication device.15. Second communication device as defined in embodiment 13 or 14, wherein the circuitry is further configured to use distributed channel access to initiate a transmit opportunity with the first communication device for transmitting the data to the first communication device.16. Second communication device as defined in any one of the embodiments 13 to 15, wherein the circuitry is further configured to transmit, if intended data transmission ended, a signaling to the first communication device to end the service period or to use remaining time of the service period for transmitting further data.17. Second communication device as defined in any one of the embodiments 13 to 16, wherein the circuitry is further configured to be awake at least a predetermined time before the start of the service period to observe channel conditions.18. Second communication device as defined in any one of the embodiments 13 to 17, wherein the circuitry is further configured to listen, before the start of the service period, to channel access information indicating whether or not a trigger will be transmitted before the start of the service period, if the channel access information indicates that a trigger will be transmitted after the start of the service period, to wait for reception of the trigger before transmitting data, and if the channel access information indicates that a trigger will not be transmitted after the start of the service period, to initiate a transmit opportunity by distributed channel access for transmitting data after the start of the service period to the first communication device.19. Second communication device as defined in any one of the embodiments 13 to 18, wherein the circuitry is further configured to indicate, before the start of the service period, one or more traffic identifiers and / or the desired direction of communication between the first and second communication devices allowed during the service period.20. Second communication device as defined in any one of the embodiments 13 to19, wherein the circuitry is further configured to request the first communication device to schedule a service period and transmit service period information and / or to transmit the request at the same time or after the QoS characteristics are transmitted.21. First communication method of a first communication device configured to communicate with a second communication device, the first communication method comprising: scheduling a service period for a second communication device to communicate with the first communication device; transmitting service period information indicating that the second communication device is entitled to communicate with the first communication device during the serviceperiod and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and listening for data transmitted from the second communication device during the service period.22. Second communication method of a second communication device configured to communicate with a first communication device, the second communication method comprising: receiving service period information from the first communication device indicating that the second communication device is entitled to communicate with the first communication device during a service period scheduled by the first communication device and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and transmitting data to the first communication device during the service period.23. 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 21 or 22 to be performed.24. A computer program comprising program code means for causing a computer to perform the steps of said method according to embodiment 21 or 22 when said computer pro-gram is carried out on a computer.

Claims

CLAIMS1. First communication device configured to communicate with a second communication device, the first communication device comprising circuitry configured to: schedule a service period for a second communication device to communicate with the first communication device; transmit service period information indicating that the second communication device is entitled to communicate with the first communication device during the service period and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and listen for data transmitted from the second communication device during the service period.

2. First communication device as claimed in claim 1, wherein the circuitry is further configured to indicate service period information that indicates to other communication devices to stop their transmit opportunity before the start of the service period and not to start a transmit opportunity during the service period.

3. First communication device as claimed in claim 1, wherein the circuitry is further configured to transmit, before the start of the service period, channel access information indicating whether or not a trigger will be transmitted after the start of the service period.

4. First communication device as claimed in claim 1, wherein the circuitry is further configured to indicate, before the start of the service period, one or more traffic identifiers for which the service period is enabled and / or the allowed direction of communication between the first and second communication devices allowed during the service period.

5. First communication device as claimed in claim 1,wherein the circuitry is configured to control if the second communication device is accessing the channel after the start of a service period by setting the direction of communication to uplink, uplink indicating data communication from the second communication device to the first communication device.

6. First communication device as claimed in claim 1, wherein the circuitry is further configured to receive quality of service (QoS) characteristics from the second communication device and to schedule the service period under consideration of the received QoS characteristics.

7. First communication device as claimed in claim 1, wherein the circuitry is configured to schedule the service period for use by one or more second communication devices to communicate with the first communication device and to transmit delay information indicating for the two or more second communication devices individual time spans after the start of the SP the respective second communication device shall wait before it is allowed to transmit data to the first communication device.

8. First communication device as claimed in claims 6 and 7, wherein the circuitry is configured to set the delay information for a second communication device based on the QoS information and / or distributed channel access parameters of said second communication device.

9. First communication device as claimed in claim 1, wherein the transmitted service period information indicates that the second communication device should initiate a transmit opportunity with the first communication device by using distributed channel access.

10. Second communication device configured to communicate with a first communication device, the second communication device comprising circuitry configured to: receive service period information from the first communication device indicating that the second communication device is entitled to communicate with the first communication device during a service period scheduled by the first communication device andthat the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and transmit data to the first communication device during the service period.

11. Second communication device as claimed in claim 10, wherein the circuitry is further configured to transmit a service period confirmation to the first communication device in response to the received service period information from the first communication device.

12. Second communication device as claimed in claim 10, wherein the circuitry is further configured to use distributed channel access to initiate a transmit opportunity with the first communication device for transmitting the data to the first communication device.

13. Second communication device as claimed in claim 10, wherein the circuitry is further configured to transmit, if intended data transmission ended, a signaling to the first communication device to end the service period or to use remaining time of the service period for transmitting further data.

14. Second communication device as claimed in claim 10, wherein the circuitry is further configured to be awake at least a predetermined time before the start of the service period to observe channel conditions.

15. Second communication device as claimed in claim 10, wherein the circuitry is further configured to listen, before the start of the service period, to channel access information indicating whether or not a trigger will be transmitted before the start of the service period, if the channel access information indicates that a trigger will be transmitted after the start of the service period, to wait for reception of the trigger before transmitting data, and if the channel access information indicates that a trigger will not be transmitted after the start of the service period, to initiate a transmit opportunity by distributed channelaccess for transmitting data after the start of the service period to the first communication device.

16. Second communication device as claimed in claim 10, wherein the circuitry is further configured to indicate, before the start of the service period, one or more traffic identifiers and / or the desired direction of communication between the first and second communication devices allowed during the service period.

17. Second communication device as claimed in claim 10, wherein the circuitry is further configured to request the first communication device to schedule a service period and transmit service period information and / or to transmit the request at the same time or after the QoS characteristics are transmitted.

18. First communication method of a first communication device configured to communicate with a second communication device, the first communication method comprising: scheduling a service period for a second communication device to communicate with the first communication device; transmitting service period information indicating that the second communication device is entitled to communicate with the first communication device during the service period and that the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and listening for data transmitted from the second communication device during the service period.

19. Second communication method of a second communication device configured to communicate with a first communication device, the second communication method comprising: receiving service period information from the first communication device indicating that the second communication device is entitled to communicate with the first communication device during a service period scheduled by the first communication device andthat the second communication device should initiate a transmit opportunity with the first communication device without being triggered by the first communication device; and transmitting data to the first communication device during the service period.

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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