First communication device and second communication device and method for multi-link operation in wireless communication scenario

Abstract

A first communication device configured to simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device configured to simultaneously exchange data units with at least one or more third communication devices via at least two links, the first communication device includes circuitry configured to: if a second data unit is expected to be queued at the second communication device at an expected time of arrival, determine whether the first data unit is queued at the first communication device or once a third data unit is queued at the second communication device or a third communication device; two links are reserved for data exchange.

Description

Technical Field

[0001] The present disclosure relates to first and second communication devices and methods, and are particularly used in multi-link operations in wireless communication scenarios. Background Art

[0002] Multi-link Operation (MLO) is a feature introduced in WLAN that allows a base station (STA) to establish multiple links with other STAs. MLO is a feature in the ongoing standard amendment IEEE802.11be that allows a multi-link device (MLD) to establish multiple links with one or more other communication devices depending on their capabilities. By using this feature, an MLD can have two simultaneous links with different communication devices to support various applications, including applications where there is interdependency between the traffic on the two links.

[0003] The "background" description provided herein is for the purpose of generally presenting the context of the present disclosure. The work performed by the presently designated inventors described in this background section, and aspects that may not qualify as prior art at the time of filing, are not admitted, either explicitly or implicitly, to be prior art to the present disclosure. Summary of the invention

[0004] The object of this document is to provide a communication device and method capable of exchanging low latency traffic between multiple communication devices. Another object is to provide a corresponding method and a corresponding computer program and a non-volatile computer-readable recording medium storing a computer program product for implementing the method.

[0005] According to one aspect, a first communication device is provided, which is configured to simultaneously exchange data units with one or more other communication devices via at least two links, and the one or more other communication devices include a second communication device, which is configured to simultaneously exchange data units with at least one or more third communication devices via at least two links. The first communication device includes a circuit, which is configured to: if the second data unit is expected to be queued at the second communication device at an expected arrival time, once the first data unit is queued at the first communication device or once the third data unit is queued at the second communication device or the third communication device, reserve two links for data exchange.

[0006] According to another aspect, there is provided a second communication device configured to simultaneously exchange data units with the first communication device via at least a first link and with a third communication device via at least a second link, the second communication device comprising circuitry configured to:

[0007] - receiving from the first communication device a switch to a second link reserved by the first communication device at or after an expected arrival time of the second data unit queued at the second communication device, thereby allowing the second communication device to transmit the second data unit via the second link; and

[0008] - transmitting a second data unit via the second link.

[0009] According to another aspect, another first communication device is provided, configured to simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device configured to simultaneously exchange data units with the one or more other communication devices via at least two links, the first communication device comprising a circuit, the circuit being configured to:

[0010] - receiving, from the second communication device, a switch to the first link reserved by the second communication device at or after an expected arrival time at which the first data unit is expected to be queued at the first communication device, thereby allowing the first communication device to transmit the first data unit via the first link; and

[0011] - Transmitting a first data unit via the first link.

[0012] According to another aspect, there is provided a second communication device configured to simultaneously exchange data units with the first communication device via at least a first link and with a third communication device via at least a second link, the second communication device comprising circuitry configured to:

[0013] - if the first data unit is expected to be queued at the first communication device at the expected arrival time, reserving two links for data exchange once the second data unit or the third data unit is queued at the second communication device;

[0014] - using at least a second link of the two reserved links to transmit a second data unit and / or to receive a data unit from a third communication device; and

[0015] - At or after an expected arrival time of an expected first data unit queued at the first communication device, switching a first link of the two reserved links, thereby allowing the first communication device to transmit the first data unit via the first link.

[0016] According to another aspect, a corresponding method is provided, a computer program comprising program means for causing a computer to perform the steps of the method disclosed herein when the computer program is executed on a computer, and a non-transitory computer-readable recording medium having a computer program product stored therein, which, when executed by a processor, causes the method disclosed herein to be performed.

[0017] Embodiments are defined in the dependent claims. It should be understood that the disclosed method, the disclosed computer program, and the disclosed computer-readable recording medium have further embodiments similar and / or identical to the claimed apparatus and defined in the dependent claims and / or disclosed herein.

[0018] One aspect of an embodiment of the present disclosure is to utilize a joint peer-to-peer (P2P) MLO session, wherein P2P communication and MLO are used jointly to support low latency traffic that needs to be exchanged between multiple communication devices including a first communication device (e.g., an access point AP) and a second communication device (e.g., a non-AP base station STA). The proposed joint P2P MLO session includes a mechanism for coordinating channel access that can reduce latency and increase reliability of communications. In a session, these advantages are critical in applications where the quality of service (QoS) of traffic exchanged between multiple communication devices is interrelated and / or dependent on each other.

[0019] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the appended claims.The described embodiments, together with other advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] A more complete appreciation of the present disclosure and its many attendant advantages will be readily obtained as the present disclosure becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 An example of communication settings for XR applications in a WLAN environment is shown.

[0022] Figure 2 A diagram illustrating a communication setup that illustrates how current features in the IEEE 802.11 standard can be utilized to support XR applications.

[0023] Figure 3A A diagram showing queue traffic is shown.

[0024] Figure 3B A diagram showing a communication setup according to an embodiment of the present disclosure is shown.

[0025] Figure 4 An embodiment of a communication scheme according to the present disclosure is shown where traffic at a first communication device is queued first.

[0026] Figure 5 Another embodiment of a communication scheme according to the present disclosure is shown in which no traffic is queued at the second communication device and the first communication device recovers using a transmission opportunity.

[0027] Figure 6 Another embodiment of a communication scheme according to the present disclosure is shown in the case where no traffic is queued at the second communication device and the first communication device ends using the transmission opportunity.

[0028] Figure 7 Another embodiment of a communication scheme in case of traffic delay at a second communication device according to the present disclosure is shown.

[0029] Figure 8 Another embodiment of a communication scheme according to the present disclosure is shown, wherein data units are initially queued at a second communication device for transmission to a first communication device.

[0030] Fig. 9 Another embodiment of a communication scheme according to the present disclosure is shown, wherein a data unit is initially queued at a second communication device for transmission to a third communication device.

[0031] Fig.10 Another embodiment of a communication scheme according to the present disclosure is shown, wherein data units are initially queued at a third communication device for transmission to a second communication device.

[0032] Fig.11 An embodiment of a communication scheme according to the present disclosure is shown, wherein P2P traffic from a second communication device to a third communication device is queued first, and wherein a first communication device initiates channel access.

[0033] Fig.12 An embodiment of a communication scheme according to the present disclosure is shown, wherein P2P traffic from a second communication device to a third communication device is queued first, and wherein the second communication device initiates channel access.

[0034] Fig.13 An embodiment of a communication scheme according to the present disclosure is shown, wherein P2P traffic from a second communication device to a third communication device is queued first, and wherein traffic at the second communication device for transmission to the first communication device is queued first.

[0035] Fig.14 An embodiment of a communication scheme according to the present disclosure is shown, wherein P2P traffic from a second communication device to a third communication device is queued first, and wherein traffic at the second communication device for transmission to first and third communication devices is queued first.

[0036] Fig.15 An embodiment of a communication scheme for TXOP switching using reverse direction grant according to the present disclosure is shown.

[0037] Fig.16 An embodiment of a communication scheme for TXOP switching using contention-free polling according to the present disclosure is shown.

[0038] Fig.17 Another embodiment of a communication scheme according to the present disclosure is shown, wherein traffic at a first communication device is queued first.

[0039] Fig.18 Another embodiment of a communication scheme according to the present disclosure is shown, wherein traffic at the second communication device is queued first. DETAILED DESCRIPTION

[0040] Developments in the field of extended reality (XR), including virtual reality (VR) and augmented reality (AR), have enabled the rise of interactive applications between remote users and local users. Exemplary applications are: i) XR games, where remote players interact with local players in the same virtual environment; ii) remote certification, consulting or training programs for industrial processes, where remote experts can interact with local personnel at industrial facilities through a shared virtual environment.

[0041] In XR applications, a virtual environment is created locally for remote and local users to experience and interact with. The virtual environment can be fully digital (e.g., XR games) or mixed with the local environment in an AR manner (e.g., industrial applications). Figure 1 An example of a communication setup for an XR application in a WLAN environment is shown. An access point (AP) multi-link device (MLD) (also referred to herein as a first communication device) provides an Internet or wide area network (WAN) connection (e.g., a home network router) to communicate with remote users. Non-AP MLD A (also referred to herein as a second communication device) represents a local control unit (e.g., a game console like Playstation) that creates a virtual environment for local users to access to interact with remote users. It also controls the flow of information between local and remote users. Non-AP base station (STA) B (which can also be an MLD, also referred to herein as a third communication device) corresponds to a device used by local users to interact with the virtual environment (e.g., VR glasses, smartphones, tablets, etc.). Similar communication devices may exist at the remote user's location.

[0042] like Figure 1As shown, the data traffic of XR applications goes from / to multiple devices that require multiple links to be established. The traffic in each link is interdependent with the traffic of other links. The links between AP MLDs can be used for remote-local data exchange (e.g., video data, audio data, tactile data, control data, game status data, etc.). For example, the link between AP1 and STA1 can exchange data corresponding to the movement of a remote user in a virtual environment. The link between STA2 and STA3 can exchange rendering data, for example, data about the visualization of a remote user in a virtual environment and the movement of a local user in response to it, such as posture data.

[0043] In addition to this interdependency between traffic in multiple links, the nature of XR applications requires low latency and high reliability to operate properly. In WLAN operation, each of these links will be established independently, which may cause high latency on any of the links and undermine the performance of the entire XR application.

[0044] MLO is a feature in the ongoing standard amendment IEEE802.11be, which allows MLD STAs to establish multiple links with other STAs depending on their capabilities. By using this feature, non-AP MLD A can have two simultaneous links to support such as Figure 1 XR application shown. The first link L1 is connected with AP MLD, and the second link L2 is connected with non-AP STA B. For the latter, a point-to-point (P2P) link should be established for direct communication, otherwise non-AP MLD A will need to route traffic to STA3 via AP, and vice versa, which will cause more waiting time.

[0045] Figure 1 One aspect of the XR communication setup in is that even though the traffic on different links is interdependent, it is not synchronized. Thus, in separate devices, data units (DUs) can be queued for transmission at different times. Figure 2A diagram is shown that illustrates a communication setup that illustrates how current features in the IEEE 802.11 standard can be utilized to support XR applications. In this scenario, it is assumed that both the AP MLD and the non-AP MLD are capable of performing simultaneous transmission and reception (STR), i.e., link 1 and link 2 operate independently of each other. First, the AP MLD contends for access to the channel to transmit data (DU10) to the non-AP MLD A in link 1, which is transmitted as separate sets 10-1, 10-2, 10-3. The DU received from AP1 causes DU11 to be created at STR non-AP MLD A, intended for non-AP STA B. Therefore, shortly after the start of this frame exchange, non-AP MLD A contends for channel access to transmit data (DU11) to non-AP STA B in link 2. However, it is assumed that the channel is busy (e.g., occupied by another STA) and non-AP MLD A needs to wait until the channel is idle again to resume contention and transmit data DU11 (in Figure 2 Only the transmission of the first set 11-1 is shown in FIG. 1 ). This results in Figure 2 The undesirable delay shown degrades the overall performance of the XR application even when Link 1 is fully operational.

[0046] The present disclosure presents a mechanism for coordinating channel access and links between devices so that traffic flows have low latency across all frame exchanges from and to multiple devices belonging to the same XR application session. Interdependent traffic includes traffic that needs to be exchanged between the AP and MLD A (AP link) and traffic that needs to be exchanged between MLD A and STA B (P2P link). To refer to each of these flows separately, conventional AP traffic and P2P traffic are used here, respectively. One of the concepts of the present disclosure is that as long as XR traffic is queued at any device, two transmission opportunities (TXOPs) will be obtained to accommodate the traffic needs of other devices in the joint P2PMLO session.

[0047] For a joint P2P MLO session, initially a frame exchange may be performed in which the non-AP MLD A exchanges capabilities, requirements, and characteristics of traffic to be transported in the joint P2P MLO session. Key components in this exchange may include one or more of the following:

[0048] - an indication of a joint P2P MLO session, which indicates that two links need to be established simultaneously in this session; it may include which devices are involved, and may indicate an identifier or distinguisher of traffic belonging to this joint P2P MLO session, and not other traffic;

[0049] - The expected arrival time of traffic on each link (between AP and MLD A and between MLD A and STA B);

[0050] - QoS characteristics of the traffic, such as expected data rate, data unit size, maximum delay tolerance;

[0051] - Delay in DU generation after receiving the relevant DU;

[0052] - Channel access mechanism for joint P2P MLO sessions (as explained in more detail below) so that devices know, for example, whether they need to wait to be triggered, or access directly with some specific resource reservation (e.g., two links) once they have queued traffic; this may include information about who will start competing for channel access and when (there may be two cases: traffic between AP and non-AP MLD A arrives first, and traffic between non-AP MLD A and STA B arrives first); in addition, the characteristics of the link (i.e., STR or NSTR) may be included.

[0053] The joint P2P MLO session setup can be implemented as a variation of the QoS feature setup.

[0054] The traffic that will be exchanged by all devices within a federated P2P MLO session belongs to the same application (e.g., an XR gaming session). The characteristics of the application determine how often packets / data units will need to be exchanged between the devices, as well as the specific characteristics of the traffic. For example, in a highly dynamic XR gaming session, there may be frequent information exchanged about the user's movements with very strict time deadlines. Conversely, in a less dynamic XR training session at a factory, the focus may be on transmitting very precise and reliable data to ensure an accurate representation of the environment.

[0055] The application layer at each device understands the characteristics of the traffic based on the application, which is passed to its MAC (Media Access Control) and PHY (Physical) layers with specific parameters. In WLAN, QoS characteristics are elements that can be used by STAs to exchange information about these specific parameters that characterize the traffic, including one or more of the following: minimum and average data rate, minimum and maximum service interval, service start time, burst size, and inter-time.

[0056] The expected traffic arrival time can be indicated within the QoS characteristics as, for example, a service start time. In addition, minimum and maximum service intervals can be used to convey information about the time intervals between expected arrival times. The exchange of traffic characteristics (e.g., QoS characteristics) can be performed as part of a joint P2P MLO session set up for at least the AP and MLD A (e.g., Figure 1 ), to understand the expected arrival time of each other’s traffic. In addition, the STAs are able to update the estimated traffic arrival time at a later point in time within the joint P2P MLO session.

[0057] It should be noted that in this context, "expected arrival time" is different from the actual arrival time of a data unit, particularly due to the unpredictability of traffic and networks. In communications, the arrival of a data unit is often defined by an average arrival time and jitter. Jitter describes the variation around the arrival time, meaning how early or late a data unit may arrive around the average. Thus, the disclosed embodiments involving expected arrival time may include situations where data units are queued before the average arrival time, and the expected arrival time may be calculated based on the average delay of the traffic in the network minus a margin based on jitter.

[0058] As shown in FIG. 3 , the proposed joint P2P MLO channel access mechanism can be divided into different cases according to the following conditions. FIG. 3 shows a diagram of queued traffic according to an embodiment of the present disclosure ( Figure 3A ) and communication setup:

[0059] - Based on the device that queues first in terms of traffic: from AP to MLD A (AP link, Figure 3B 1 in the link), or from MLD A to STA B (P2P link, Figure 3B Link 2 in );

[0060] - Based on the time difference between the AP traffic queued in the first link and the expected arrival time of the P2P traffic to be exchanged in the second link, Figure 3A It is called “queue flow arrival time difference” in ;

[0061] -Based on MLD A's STR and NSTR abilities.

[0062] Joint P2P MLO channel access is usually performed after a joint P2P MLO session setup. Thus, the AP, MLD A, and STA B are aware of the information exchanged in the joint P2P MLO session setup, including the expected time arrival of DUs at different devices.

[0063] In the following, reference will be made to Figures 4 to 16 An embodiment of the present disclosure is illustrated in which the non-AP MLD A is a STR, ie, it is capable of transmitting and receiving data / frames simultaneously in different links.

[0064] Figure 4 An embodiment of a communication scheme according to the present disclosure is shown, in which AP traffic 10 (including the first DU) from the AP to the non-AP MLD A is queued first. The general operation is that the AP obtains a TXOP in link 1 and another TXOP in link 2, which can be used for AP traffic 10 and P2P traffic 11 (including the second DU) belonging to the same joint P2P MLO session. First, assuming the arrival time difference of the queued traffic (such as Figure 3A) is below a certain (e.g., user-defined or applicable or predetermined / fixed) threshold, reference Figure 4 This means that there is enough queued traffic 10 at the AP to fill both links until the expected arrival of the P2P traffic 11.

[0065] Initially, the AP obtains TXOPs in both links with sufficient resources to support the two flows (infrastructure and P2P) indicated in the joint P2P MLO session setup. The AP occupies both links with AP flow 10 (plus additional flows if needed) until the expected arrival time 20 of the P2P flow 11 minus a certain margin, specifically the time between the end of the PPDU 10b and the start of the TF 12 (essentially the time required to receive an acknowledgment and trigger the P2P flow within the time margin 21). The PPDU may be configured with aggregated flows to end at a specified time, thereby allowing the P2P flow 11 to trigger within a certain time margin 21 after the expected arrival time 20 of the P2P flow 11. Furthermore, the P2P flow 11 should not trigger before its expected arrival time 20. Aggregation, fragmentation, and / or padding operations may be included to account for the time when the P2P flow is triggered. This is done in Figure 4 , where the second group of 10 DUs of AP traffic 10 are transmitted in three different PPDUs 10a, 10b, 10c. The first 5 DUs are included in PPDU 10b, which is used to occupy the channel in link 2 until P2P traffic 11 is triggered. The remaining 10 DUs are sent on link 1 as part of PPDUs 10a and 10c. Figure 2 This reduces the total transmission time by 22 compared to the transmission time conventionally required to transmit AP traffic as shown in FIG. Thus, in this embodiment, once the first data unit is queued at the AP, the AP reserves two links for data exchange by transmitting the first data unit to MLD A once the first data unit is queued at the AP.

[0066] The DUs used to occupy link 2 may have a different priority than the DUs initially transmitted in link 1. It is also possible to repeat the transmission of some DUs to occupy link 2. This will not be very efficient in terms of channel utilization, but it can be used to increase the reliability of the selected DUs. Upon the expected arrival of P2P traffic 11, the AP sends a trigger or trigger frame (TF) 12 that allocates resources for the traffic between MLD A and STA B (via TXOP sharing), such as Figure 4 Thus, after a small signaling delay 23 (during which MLD A may transmit signaling 13 (eg, Clear to Send CTS 13) indicating its intention to start transmitting), MLD A starts transmitting PPDUs 11a, 11b containing P2P traffic 11 to STA B via link 2.

[0067] Next, assuming that the arrival time difference of the queue flow is higher than a certain threshold (which can be compared with the above Figure 4 An embodiment is described in the case where the AP does not have enough queued traffic to fill both links until the expected arrival 20 of P2P traffic 11. In this case, the AP obtains a TXOP for AP traffic on link 1. If the AP accumulates enough traffic to fill both links before the expected arrival 20 of P2P traffic 11 minus a certain margin, it may obtain a second TXOP in link 2 and use it as the AP link until it is switched to P2P traffic exchange time. Otherwise, that is, if there is not enough traffic to pre-fill both links, at the expected arrival of P2P traffic minus a certain margin, the AP will contend for channel access in link 2 to allocate P2P resources to MLD A and STA B via TXOP sharing.

[0068] Figure 5 An embodiment of a communication scheme according to the present disclosure is shown, which is similar to Figure 4 The communication scheme shown, however, there is no response to the trigger or trigger frame 12 from MLD A because there is no queued P2P traffic at MLD A. Therefore, if there is no response from MLD A during a (e.g., predetermined or set) timeout period 24, the AP may resume using link 2 to further transmit data (e.g., another PPDU 10d) to MLD A.

[0069] Alternatively, if the AP does not have enough traffic to continue to occupy both links, it will terminate the link after a timeout period 24 by transmitting Figure 6 The CF-End frame 14 shown in FIG. terminates the TXOP in link 2. Figure 6 Another embodiment of the communication scheme according to the present disclosure is shown. The communication scheme is similar to Figure 4 If there is still traffic at the AP, it can be transmitted on link 1 (eg, as shown for PPDU 10d).

[0070] Figure 7 Shown with Figure 4 The communication scheme shown is similar to another embodiment of the communication scheme according to the present disclosure, but in which the P2P traffic (second DU 11) is queued later than its expected arrival 20, i.e., delayed. In this case, MLD A does not have queued P2P traffic when the first trigger TF (P2P) 12 is sent from AP2. However, MLD A knows that P2P flow 11 will be queued shortly thereafter. In order to avoid losing the already reserved resources, MLD A can send an indication 15 (e.g., shown as Figure 7A in the MLD A frame 16) to indicate to the AP the updated expected arrival time 25 of the P2P traffic 11. The AP may then continue to utilize the channel in link 2 until such time as the P2P traffic is triggered by another trigger or trigger frame 16, in response to which MLD A begins transmitting on link 2 (by transmitting PPDU 11a, optionally prior to the transmission of CTS 13).

[0071] Figure 8 Another embodiment of the communication scheme according to the present disclosure is shown. The communication scheme is similar to Figure 4 3, but wherein the third DU 30 is initially queued at MLD A for transmission to the AP. The AP then transmits a trigger or trigger frame 31, 32 to MLD A, which then transmits PPDUs 30a, 30b containing the third DU 30 to the AP on links 1 and 2. Thereafter, after a time margin 41 after the expected arrival time 40 of the first DU 10, the AP begins transmitting the first DU 10 to MPD A on link 1. Furthermore, after a time margin 21, MLD A is triggered to begin transmitting the second DU 11 to STA B, as described above with respect to FIG. Figure 4 Thus, in this embodiment, once the third data unit is queued at MLD A (in this case for transmission to the AP), the AP reserves both links for data exchange by triggering MLD A once the third data unit is queued at MLD A.

[0072] Fig. 9 Another embodiment of the communication scheme according to the present disclosure is shown. The communication scheme is similar to Figure 8 30 , but in which the third DU 30 is initially queued at MLD A for transmission to MLD B, which is a STR device in this embodiment. After being triggered by the AP, MLD A transmits PPDUs 30a, 30b containing the third DU to MLD B on links 1 and 2, optionally after transmitting CTS frames 33, 34. Operation is then substantially as follows: Figure 8 Thus, in this embodiment, the AP reserves two links for data exchange once the third data unit is queued at MLD A (in this case for transmission to MLD B) by triggering MLD A once the third data unit is queued at MLD A.

[0073] Fig.10 Another embodiment of the communication scheme according to the present disclosure is shown. The communication scheme is similar to Fig. 935, but in which the third DU 35 is initially queued at MLD B for transmission to MLD A. After being triggered by the AP via a trigger or trigger frame 36, 37, MLD B transmits PPDU 35a, 35b containing the third DU to MLD A on links 1 and 2, optionally after transmitting CTS frames 38, 39. Operation is then substantially as follows: Figure 8 Thus, in this embodiment, once the third data unit is queued at MLD B (in this case for transmission to MLD A), the AP reserves both links for data exchange by triggering MLD B to transmit the third data unit to the AP and / or MLD A once the third data unit is queued at MLD B.

[0074] As mentioned above, the third data units may be generated at MLD A or MLD B, and they may not necessarily be part of the joint P2P MLO session. Their main purpose is to occupy two links where the first and / or second data units belonging to the joint P2P MLO session are queued for transmission.

[0075] Figures 11 to 16 An embodiment of a communication scheme according to the present disclosure is shown, where P2P traffic 11 (including the second DU) from non-AP MLD A to STA B is queued first. This case can be further divided into two sub-cases, depending on which device (AP or MLD A) starts the channel access process.

[0076] Fig.11 An embodiment of a communication scheme according to the present disclosure is shown, in which the AP starts channel access. The AP is able to obtain two TXOPs (one in link 1 and the other in link 2) at the expected arrival 20 of P2P traffic 11 (within a certain time margin to account for processing and channel access delays), and trigger P2P traffic in link 2 via TXOP sharing. Link 1 should be used by other STAs oSTA ( Fig.11 The first PPDU 50 is occupied by infrastructure traffic (shown as PPDU 50) of the AP1 in the link 1 (not shown). The confirmation return (RX) 51 is received by AP1 in link 1 from oSTA. In this case, the TXOP in link 1 can be broadcast so that more than one STA (e.g., oSTA and STA1) can listen to the PPDU sent by AP1. Since the first PPDU 50 is not addressed to STA1, according to the standard behavior, STA1 can stop decoding the DU from AP1 in link 1, which will cause STA1 to miss the following traffic. To avoid this, STA1 participating in the joint P2P MLO session can stay awake during the broadcast TXOP even when the first PPDU is not addressed to itself.

[0077] When DU10 for AP traffic to MLD A is queued within a certain margin 41 to meet the delay constraint, the traffic to oSTA in link 1 should end. Similar to the above operation, if there is no other AP traffic, link 2 can only be occupied first. After that, if there is enough traffic (and time), TXOP can be obtained in link 1 to transmit other AP traffic before AP traffic reaches MLD A.

[0078] In the case where STA B is an MLD, the AP can allocate both links to P2P traffic 11 via TXOP sharing before the arrival of AP traffic 10. P2P allocation (in the P2P trigger or trigger frame TF12) can be provided to MLD A to control both links, or one link can be provided to STA B and the other link can be provided to MLD A to allow bidirectional traffic. The base station that gains access to link 1 can occupy it with traffic until the expected arrival of AP traffic within some margin.

[0079] Next, something like Fig.11 To describe an embodiment, but in which MLD, A starts channel access. A simple scheme ( Fig.12 , which is not shown separately in the figure, is that MLD A waits for a trigger because the AP should know the expected P2P traffic arrival time. Alternatively, if the traffic unexpectedly queues earlier, MLD A can obtain the TXOP on each link and switch the TXOP to the AP and wait for a trigger. The TXOP switching mechanism will be explained in more detail below. A joint P2P MLO session start frame can be defined, which can be used by the MLD A to share some additional information about the required resources, for example, according to the current channel conditions, such as information that was not previously known (e.g., modulation and coding scheme (MCS), number of spatial streams (NSS), bandwidth, etc.).

[0080] Fig.12 An embodiment of a communication scheme according to the present disclosure is shown, which is similar to Fig.11 The communication scheme shown in is similar to that shown in , but wherein MLD A starts channel access (e.g., using enhanced distributed channel access (EDCA)). MLD A is able to obtain one TXOP in each link. The TXOP in link 1 can be used for infrastructure traffic and the TXOP in link 2 can be used for P2P traffic. In link 1, the TXOP should be switched to the AP at some point before the expected start of AP traffic 10 in link 1. In the case where STA B is an MLD, MLD A is able to use both links to send data to STA B (shown as PPDUs 11a, 11b, and 11c). MLD A should then switch (indicated by arrow 60) the TXOP in link 1 to the AP within a certain margin 41 when the expected AP traffic arrives 40.

[0081] Since P2P traffic 11 may face hidden node issues, a "P2P MLO Start" frame 52, 53 (also referred to as a "Reservation Indication") may be sent by MLD A in both links, and the AP may then reply with a "P2P MLO Response" 54, 55 (also referred to as a "Reservation Confirmation") or it may repeat the "P2P MLO Start" frame to provide a medium reservation that will protect P2P traffic 11 in link 2. Although the AP is responding to the P2P MLD Start, when STA1 initiates a TXOP transmission 60, the AP does not immediately participate in data exchange, but participates in data exchange later. The "Reservation Indication" may also be used to notify other STAs in the same basic service set (BSS) that the first link is occupied (i.e., enabling network allocation vector (NAV) allocation).

[0082] Therefore, in Fig.11 and Fig.12 In the illustrated embodiment, once the second data unit is queued at the second communication device, both links are reserved by transmitting the second data unit to the third communication device.

[0083] Fig.13 Another embodiment of the communication scheme according to the present disclosure is shown. The communication scheme is similar to Fig.12 The communication scheme shown, but in which the third DU 30 is initially queued at MLD A for transmission to the AP. The third DU (in PPDUs 30a and 30b) is transmitted to the AP by transmitting "P2P MLO Start" frames 52, 53 in both links and replied by the AP by transmitting "P2P MLO Response" 54, 55. Then, at the expected arrival time 40 of the first DU 10, MLD A switches link 1 to the AP and transmits the second DU 11 (in PPDUs 11a and 11b) to STA B within a margin 21 after the arrival time 20 of the second DU 11.

[0084] Fig.14 Another embodiment of the communication scheme according to the present disclosure is shown. Fig.12The communication scheme shown is similar, but in which the third DU 30 is initially queued at MLD A for transmission to the AP and STA B. After the "P2P MLO Start" frames 52, 53 are transmitted by MLD A in both links and replied by the AP by transmitting "P2P MLO Response" 54, 55, the third DU 30 is transmitted to the AP (PPDU 30a on Link 1) and STA B (PPDU 30b on Link 2), respectively. Thereafter, at the expected arrival time 40 of DU 10, MLD A switches link 1 (arrow 60) to the AP, and at the expected arrival time 42 of DU 56, MLD A switches link 2 (arrow 61) to STA B. The AP then transmits the first DU 10 (in PPDUs 10a and 10b) to STA 1 of MLD A on Link 1, and STA B then sends DU 56 (in PPDUs 56a and 56b) to STA 2 of MLD A on Link 2 within the margin 43.

[0085] Therefore, in Fig.13 and Fig.14 In the illustrated embodiment, once the third data unit is queued at the second communication device, both links are reserved by transmitting the third data unit to the first communication device (and optionally, the third communication device).

[0086] Fig.15 and Fig.16 An embodiment of a communication scheme using different options for TXOP switching according to the present disclosure is shown, which can be applied to Figure 12 to Figure 14 The communication scheme shown in Figure 2. Both options use the transmission of a transmission grant to another device to which the TXOP (for one or both links) should be switched. Fig.15 , the reverse direction grant (RDG) is used as a transmission grant, and according to Fig.16 ,Content-Free Poll (CF-Poll) message is used as transmission grant.

[0087] When using RDG ( Fig.15 ), STA1 sends a PPDU 62 (which may carry AP1's data) to AP1, which contains an RDG indication 63 allowing AP1 to send DUs to STA1, for example, in burst form. Alternatively, a separate RDG information may be sent by STA1 to the AP. In each PPDU 10a, 10b, AP1 may include a continue indication 64 ("more DUs") or 65 ("no more DUs") to indicate whether it wants to send more DUs in another PPDU, or whether it has completed its transmission and STA1 is able to regain TXOP ownership. In order to send several PPDUs one after another, AP1 may support delayed acknowledgment for these PPDUs. Once the RDG ends, an acknowledgment will be sent by STA1.

[0088] When using CF-Poll ( Fig.16 ), STA1 as the TXOP holder alone sends a CF-Poll frame / message 66 addressed to AP1 to allocate the TXOP to AP1 within a specific time limit.

[0089] In the above, reference has been made to Figures 4 to 16 An embodiment of the present disclosure is described, wherein the non-AP MLD A is a STR. Fig.17 and Fig.18 An embodiment of the present disclosure is described in which a non-AP MLD A is a non-STR (NSTR), i.e., it cannot transmit and receive data / frames in different links simultaneously. Thus, in order to use several links, the NSTR MLD transmits or receives in all links simultaneously. Therefore, transmissions to or from the NSTR MLD in all links should be aligned in time. In the following, it is assumed that the channel access mechanism supports joint P2P MLO sessions when MLD A only supports NSTR operation.

[0090] Fig.17 An embodiment of a communication scheme according to the present disclosure is shown, in which AP traffic 10 (including the first DU) from the AP to the non-AP MLD A is queued first. Figure 4 . If the AP has enough traffic to fill both links, it obtains a TXOP in link 1 and another TXOP in link 2. The key difference in this case is that the transmission to MLD A and the expected response are aligned in time, as shown by the dashed line with rounded ends (e.g., line 70).

[0091] The initial PPDUs 10a, 10b from AP1 to STA1 and from AP2 to STA2 have aligned starts and ends, respectively. In addition, the response acknowledgements (Back) 71a, 71b are also aligned in time. To transmit a TXOP to MLD A for P2P traffic 11, the AP sends two triggers or trigger frames TF 12a, 12b, one in each link, to share the TXOP with STA1 and STA2. This gives NSTR MLD A control over the start of transmissions to allow their time alignment.

[0092] PPDUs 11a, 30a and 11b, 30b transmitted by MLD A are aligned. Optionally, RDG is enabled in link 1 to allow traffic from AP to MLD A (PPDU 10c). At the same time, due to NSTR operation, RDG can also be enabled in link 2, allowing STA3 to send data 35 (PPDU 35a) to MLD A. In addition, the start time and duration of the reverse PPDU 10c from AP1 and the reverse PPDU 35a from STA3 are aligned. The alignment information 72a, 72b can be signaled by MLD A in the previous frame. The start time can be implicitly obtained by counting the fixed inter-frame space (IFS) time after the previous PPDU because these PPDUs have aligned ends.

[0093] A variation of the Single Response Schedule (SRS) field may be used to indicate the duration that the response PPDUs 10c, 35a from AP1 and STA3 should have. If the actual response is too short, padding may be used.

[0094] Since MLD A (from the joint P2P MLO setup) knows the traffic that needs to be sent by AP1 and STA B, it can estimate the response PPDU duration based on one or more of the following:

[0095] -The minimum amount of data that the AP and STA B need to send to meet the latency requirement;

[0096] - Maximum expected queue data volume at AP and STA B to minimize the need for padding;

[0097] - Channel conditions PHY configuration parameters that affect PPDU duration, such as MCS, NSS, bandwidth.

[0098] The SRS field is defined for a single response. Depending on the amount of queued traffic at the AP and STA B, this field may be modified to allow bursts of several PPDUs in each link to end simultaneously. After receiving the last PPDU in the RDG, MLD A sends an aligned acknowledgement 73a, 73b and continues to send aligned frames (PPDU11b, 30b) to the AP and STA B until the TXOP ends.

[0099] Fig.18An embodiment of a communication scheme according to the present disclosure is shown, where P2P traffic 11 (including the second DU) from MLD A to STA B is queued first. In this case, MLD A obtains a TXOP in link 1 and another TXOP in link 2, where P2P MLO start frames 52, 53 and response frames 54, 55 may be exchanged between MLD A and the AP at the beginning for wireless medium reservation and sharing of channel conditions and / or other information in PHY configuration.

[0100] In the case where STA B is also an MLD, MLD A starts sending frames to STA B in both links with aligned PPDUs 11a, 11b to support NSTR operation. If STA B is not an MLD, MLD A sends data to STA B on link 2 (PPDUs 11c, 11d) and occupies link 1 with data to the AP (PPDUs 30a, 30b) or another STA as long as the PPDUs are aligned in both links. If there is not enough data to occupy both links before the expected arrival of AP traffic 10, MLD A may obtain only one TXOP in link 2. Once there is queued traffic to occupy both links and two TXOPs have been established, MLD A continues as described with respect to Fig.17 The operation explained.

[0101] It should be noted that the terms "transmit" (or "send") and "receive" should not be understood here so as to exclude reception in the case of transmission and exclude transmission in the case of reception. On the contrary, transmission may also include reception, and reception may also include transmission as in the case of exchange of data or frames. For example, when a communication unit transmits data, it may receive feedback from the receiver, for example in the form of an acknowledgment Ack or Back.

[0102] Different options of how one or more links can be reserved are disclosed herein. Typically, reservation of links for data traffic may be accomplished by performing channel access on all links and exchanging frames (eg, from another data traffic) until the first data traffic is queued for transmission.

[0103] In summary, the present disclosure proposes communication devices and methods for joint P2P MLO sessions, wherein P2P communication and MLO are jointly utilized to support low latency traffic that needs to be exchanged by multiple communication devices. Further, mechanisms for coordinating channel access that can reduce latency and increase communication reliability are disclosed. These mechanisms can be advantageously used in applications where the QoS of traffic exchanged by multiple devices within a session is interrelated and / or dependent on each other.

[0104] Therefore, the above discussion only discloses and describes exemplary embodiments of the present disclosure. As will be appreciated by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from the spirit or essential features of the present disclosure. Therefore, the disclosure of the present disclosure is intended to be illustrative, rather than limiting, the scope of the present disclosure and other claims. The present disclosure (including any readily discernible variations of the teachings herein) partially defines the scope of the aforementioned claim terms, so that no inventive subject matter is dedicated to the public.

[0105] 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.

[0106] To the extent that the embodiments of the present disclosure are described as being implemented at least in part by a data processing apparatus controlled by software, it should be understood that non-transitory machine-readable media carrying such software, such as optical disks, magnetic disks, semiconductor memories, etc., are also considered to embody embodiments of the present disclosure. Further, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0107] The elements of the disclosed devices, apparatuses and systems may be implemented by corresponding hardware and / or software elements (e.g., appropriate circuits or circuits). A circuit is a structural assembly of electronic components including conventional circuit elements, integrated circuits including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. In addition, the circuit includes a central processing unit, a graphics processing unit, and a microprocessor that are programmed or configured according to software code. The circuit does not include pure software, although the circuit includes the hardware that executes the software as described above. The circuit or circuit may be implemented by a single device or unit or multiple devices or units, or a chipset or processor.

[0108] A list of further embodiments of the disclosed subject matter follows:

[0109] 1. A first communication device, the first communication device being configured to: simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices comprising a second communication device, the second communication device being configured to simultaneously exchange data units with at least one or more third communication devices via at least two links,

[0110] The first communication device includes a circuit configured to reserve two links for data exchange once the first data unit is queued at the first communication device or once the third data unit is queued at the second communication device or the third communication device if the second data unit is expected to be queued at the second communication device at the expected arrival time.

[0111] 2. The first communication device defined in embodiment 1,

[0112] The circuit is configured as follows:

[0113] - once the first data unit is queued at the first communication device, using at least a first link of the two reserved links for transmitting the first data unit; and

[0114] - At or after the expected arrival time, switching a second link of the two reserved links, thereby allowing the second communication device to transmit the second data unit via the second link.

[0115] 3. A first communication device as defined in any one of the preceding embodiments,

[0116] The circuit is configured to reserve two links by one or more of the following:

[0117] - once the first data unit is queued at the first communication device, transmitting the first data unit to the second communication device;

[0118] - once the third data unit is queued at the second communication device, triggering the second communication device to transmit the third data unit to the first communication device and / or the third communication device; and

[0119] - Once the third data unit is queued at the third communication device, triggering the third communication device to transmit the third data unit to the first communication device and / or the second communication device.

[0120] 4. A first communication device as defined in any one of the preceding embodiments,

[0121] The circuit is configured to switch the second link by transmitting a trigger or a trigger frame to the second communication device.

[0122] 5. The first communication device defined in embodiment 2,

[0123] The circuit is configured to: in response to the trigger or the trigger frame, if there is a switching response, receive the switching response from the second communication device, where the switching response indicates a state of the second data unit at the second communication device.

[0124] 6. A first communication device as defined in any one of the preceding embodiments,

[0125] The circuit is configured to determine the expected arrival time based on traffic information received from the second communication device, the traffic information including one or more of requirements, characteristics, and content information of the second data unit expected to be queued.

[0126] 7. A first communication device as defined in any one of the preceding embodiments,

[0127] The circuit is configured to: if a first data unit has been queued at the first communication device for transmission to the second communication device before the expected arrival time of the second data unit at the second communication device, use the second link to transmit part of the first data unit to the second communication device before the second link is switched to the second communication device.

[0128] 8. The first communication device as defined in embodiment 7,

[0129] The circuit is configured to include one or more first data units and / or one or more copies of the first data unit in the portion of the first data unit.

[0130] 9. A first communication device as defined in embodiment 7 or 8,

[0131] The circuit is configured to stop using the second link to transmit part of the first data unit to the second communication device after the expected arrival time of the second data unit at the second communication device or its updated arrival time or in a time period after the expected arrival time or the updated arrival time.

[0132] 10. A first communication device as defined in embodiment 7, 8 or 9,

[0133] The circuit is configured to: continue to use the second link to transmit part of the first data unit to the second communication device, or stop using the second link if no second data unit is queued at the second communication device for transmission to the third communication device at the expected arrival time or a predetermined time period after the expected arrival time.

[0134] 11. A first communication device as defined in any one of the preceding embodiments,

[0135] The circuit is configured to: align the start and / or end of transmission of corresponding parts of the first data unit on the first link and the second link to the second communication device.

[0136] 12. A first communication device as defined in any one of the preceding embodiments,

[0137] The circuit is configured to: switch the first link and the second link to the second communication device at or after the expected arrival time, thereby allowing the second communication device to simultaneously transmit the data unit to the first communication device via the first link and transmit the second data unit to the third communication device via the second link.

[0138] 13. A first communication device as defined in any one of the preceding embodiments,

[0139] The circuit is configured to: after receiving a transmission authorization and / or transmission timing information from the second communication device, transmit the first data unit to the second communication device.

[0140] 14. The first communication device as defined in embodiment 13,

[0141] The circuit is configured to: align the start and / or end of transmission of a first data unit on a first link to a second communication device with transmission of a data unit on a second link from a third communication device to the second communication device based on transmission timing information.

[0142] 15. A first communication device as defined in any one of the preceding embodiments,

[0143] Wherein, the circuit is configured to: if at the expected arrival time of the second data unit at the second communication device, no first data unit has been queued at the first communication device for transmission to the second communication device,

[0144] - using the first link for data exchange with another communication device or for broadcasting a data unit;

[0145] - at the same time, switching the second link to the second communication device; and

[0146] - once the first data unit is queued at the first communication device, ceasing to use the first link for data exchange with another communication device or for broadcasting data units, and starting to use the first link to transmit the first data unit to the second communication device.

[0147] 16. A second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least the first link and with the third communication device via at least the second link, the second communication device comprising circuitry configured to:

[0148] - receiving, from the first communication device, a switch to a second link reserved by the first communication device at or after an expected arrival time at which the second data unit is expected to be queued at the second communication device, thereby allowing the second communication device to transmit the second data unit via the second link; and

[0149] - transmitting the second data unit via the second link.

[0150] 17. The second communication device as defined in embodiment 16,

[0151] The circuit is configured to: once the third data unit is queued at the second communication device, transmit the third data unit to the first communication device and / or the third communication device after the second communication device is triggered by the first communication device.

[0152] 18. A second communication device as defined in any one of embodiments 16 to 17,

[0153] The circuit is configured to: once the third data unit is queued at the third communication device, receive the third data unit transmitted by the third communication device after the third communication device is triggered by the first communication device.

[0154] 19. A second communication device as defined in any one of embodiments 16 to 18,

[0155] The circuit is configured to: before switching to the second link, receive a first data unit from the first communication device via at least the first link.

[0156] 20. A second communication device as defined in any one of embodiments 16 to 19,

[0157] The circuit is configured to: after the second link has been switched, transmit a switching response to the first communication device, the switching response indicating that the state of the second data unit includes one or more of the following:

[0158] - a second data unit has been queued at the second communication device for transmission to the third communication device,

[0159] - no second data unit has been queued at the second communication device for transmission to the third communication device,

[0160] - the second data unit will be queued later than the expected arrival time, and

[0161] - Updated expected arrival time.

[0162] 21. A second communication device as defined in any one of embodiments 16 to 20,

[0163] The second communication device is configured to: simultaneously transmit data units on the first link and the second link or simultaneously receive data units on the first link and the second link, but not simultaneously transmit data units on one of the two links and receive data units on the other of the two links.

[0164] 22. The second communication device as defined in embodiment 21,

[0165] The circuit is configured as follows:

[0166] - before or simultaneously with switching the second link from the first communication device to the second communication device, receiving a switching of the first link, and,

[0167] - after switching the first link and the second link from the first communication device to the second communication device, simultaneously transmitting a data unit to the first communication device via the first link and transmitting a second data unit to a third communication device via the second link.

[0168] 23. A second communication device as defined in embodiment 21 or 22,

[0169] The circuit is configured to: align the start and / or end of transmission of the data unit on the first link to the first communication device, and align the start and / or end of transmission of the data unit on the second link to the third communication device.

[0170] 24. A second communication device as defined in any one of embodiments 21, 22 or 23,

[0171] The circuit is configured to: transmit a transmission authorization to the first communication device and the third communication device, thereby allowing the first communication device and the third communication device to transmit the data unit to the second communication device.

[0172] 25. A second communication device as defined in embodiment 24,

[0173] The circuit is configured to transmit the transmission grant in the form of a reverse direction grant RDG included in a data unit or by transmitting separate contention-free (CF) polling messages to the first communication device and the third communication device.

[0174] 26. A second communication device as defined in any one of embodiments 21 to 25,

[0175] The circuit is configured to transmit transmission timing information to the first communication device and the third communication device, wherein the transmission timing information indicates a start time, a stop time, and / or a duration of transmitting a data unit from the first communication device and the third communication device to the second communication device.

[0176] 27. A first communication method for a first communication device, the first communication device being configured to: simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device, the second communication device being configured to simultaneously exchange data units with at least one or more third communication devices via at least two links, the first communication method comprising: if the second data unit is expected to be queued at the second communication device at an expected arrival time, then once the first data unit is queued at the first communication device or once the third data unit is queued at the second communication device or the third communication device, reserving two links for data exchange.

[0177] 28. A second communication method of a second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least a first link and with a third communication device via at least a second link, the second communication method comprising:

[0178] - receiving, from the first communication device, a switch to a second link reserved by the first communication device at or after an expected arrival time at which the second data unit is expected to be queued at the second communication device, thereby allowing the second communication device to transmit the second data unit via the second link; and

[0179] - transmitting the second data unit via the second link.

[0180] 29. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the method according to embodiment 27 or 28 to be performed.

[0181] 30. A computer program comprising program code means for causing a computer to perform the steps of the method according to embodiment 27 or 28 when the computer program is executed on the computer.

[0182] A1. A first communication device, the first communication device being configured to: simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device, the second communication device being configured to simultaneously exchange data units with one or more other communication devices via at least two links, the first communication device comprising a circuit, the circuit being configured to:

[0183] - receiving, from the second communication device, a switch to the first link reserved by the second communication device at or after the expected arrival time at which the first data unit is expected to be queued at the first communication device, thereby allowing the first communication device to transmit the first data unit via the first link; and

[0184] - Transmitting a first data unit via the first link.

[0185] A2. A first communication device as defined in embodiment A1,

[0186] The circuit is configured to transmit the first data unit to the second communication device once the first data unit is queued at the first communication device.

[0187] A3. A first communication device defined according to any one of the preceding embodiments,

[0188] The circuit is configured to: in response to receiving a reservation indication from the second communications device indicating that the second communications device is to reserve at least two links, transmit a reservation confirmation indicating that the at least two links are reserved or a copy of the reservation indication.

[0189] A4. A first communication device defined according to any one of the preceding embodiments,

[0190] The circuit is configured to receive the switching of the first link by receiving a transmission authorization from the second communication device, and indicate in one or more of the first data units subsequently transmitted whether other data units should be transmitted and / or whether the transmission of the first data unit is completed.

[0191] A5. A first communication device defined according to any one of the preceding embodiments,

[0192] The circuit is configured to: receive a switch to the first link by receiving a polling message from the second communication device, and then transmit the first data unit within a time limit indicated by the polling message.

[0193] A6. A second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least a first link and with a third communication device via at least a second link, the second communication device comprising a circuit configured to:

[0194] - if the first data unit is expected to be queued at the first communication device at the expected arrival time, reserving two links for data exchange once the second data unit or the third data unit is queued at the second communication device;

[0195] - using at least a second link of the two reserved links to transmit a second data unit and / or to receive a data unit from a third communication device; and

[0196] - At or after an expected arrival time at which the first data unit is expected to be queued at the first communication device, switching a first link of the two reserved links, thereby allowing the first communication device to transmit the first data unit via the first link.

[0197] A7. A second communication device as defined in embodiment A6,

[0198] The circuit is configured to reserve the two links by performing one or more of the following:

[0199] - once the second data unit is queued at the second communication device, transmitting the second data unit to the third communication device, and

[0200] - Once the third data unit is queued at the second communication device, transmitting the third data unit to the first communication device.

[0201] A8. A second communication device as defined in any one of embodiments A6 and A7,

[0202] The circuit is configured to: before reserving the two links, transmit a reservation indication to the first communication device, wherein the reservation indication indicates that the second communication device is to reserve the two links.

[0203] A9. A second communication device as defined in any one of embodiments A6 to A8,

[0204] The circuit is configured to switch the first link by transmitting a transmission authorization or a polling message to the first communication device.

[0205] A10. A second communication device as defined in embodiment A9,

[0206] The circuit is configured to transmit the transmission grant in the form of a reverse direction grant RDG included in a data unit or by transmitting a separate contention-free CF polling message to the first communication device.

[0207] A11. A second communication device as defined in any one of embodiments A6 to A10,

[0208] The circuit is configured to determine the expected arrival time based on traffic information received from the first communication device, the traffic information including one or more of requirements, characteristics, and content information of the first data unit expected to be queued.

[0209] A12. A second communication device as defined in any one of embodiments A6 to A11,

[0210] The circuit is configured to: use the first link to transmit part of the second data unit to the third communication device and / or transmit the first data unit to the first communication device before the first link is switched to the first communication device.

[0211] A13. A second communication device as defined in embodiment A12,

[0212] The circuit is configured to include one or more second data units and / or one or more copies of the second data unit in the portion of the second data unit.

[0213] A14. A second communication device as defined in embodiment A12 or A13,

[0214] The circuit is configured to stop using the first link to transmit part of the second data unit to the third communication device after the expected arrival time or the updated arrival time of the first data unit at the first communication device or in a time period after the expected arrival time or the updated arrival time.

[0215] A15. A second communication device as defined in embodiments A12, A13 or A14,

[0216] The circuit is configured to continue to use the first link to transmit part of the second data unit to the third communication device, or stop using the first link if no first data unit is queued at the first communication device for transmission to the second communication device at the expected arrival time.

[0217] A16. A second communication device as defined in any one of embodiments A6 to A15,

[0218] The second communication device is configured to: simultaneously transmit data units on the first link and the second link or simultaneously receive data units on the first link and the second link, but not simultaneously transmit data units on one of the two links and receive data units on the other of the two links.

[0219] A17. A second communication device as defined in embodiment A16,

[0220] The circuit is configured to: after switching the first link to the first communication device, transmit timing information to the first communication device and the third communication device, the timing information indicating the start time, and / or stop time, and / or duration of the first communication device and the third communication device transmitting the data unit to the second communication device.

[0221] A18. A second communication device as defined in embodiment A16 or A17,

[0222] The circuit is configured to: before switching the first link to the first communication device, simultaneously transmit the data unit to the first communication device or the third communication device via the first link and transmit the second data unit to the third communication device via the second link.

[0223] A19. A second communication device as defined in any one of embodiments A16, A17 or A18,

[0224] The circuit is configured to: align the start and / or end of transmission of the corresponding part of the second data unit on the first link and the second link to the third communication device.

[0225] A20. A second communication device as defined in embodiment A8,

[0226] The circuit is configured to: align the start and / or end of the transmission of the reservation indication to the first communication device.

[0227] A21. A first communication method of a first communication device, the first communication device being configured to: simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device, the second communication device being configured to simultaneously exchange data units with one or more other communication devices via at least two links, the first communication method comprising:

[0228] - receiving, from the second communication device, a switch to the first link reserved by the second communication device at or after the expected arrival time at which the first data unit is expected to be queued at the first communication device, thereby allowing the first communication device to transmit the first data unit via the first link; and

[0229] - transmitting the first data unit via the first link.

[0230] A22. A second communication method of a second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least a first link and with a third communication device via at least a second link, the second communication method comprising:

[0231] - if the first data unit is expected to be queued at the first communication device at the expected arrival time, reserving two links for data exchange once the second data unit or the third data unit is queued at the second communication device;

[0232] - using at least a second link of the two reserved links to transmit a second data unit and / or to receive a data unit from a third communication device; and

[0233] - At or after an expected arrival time at which the first data unit is expected to be queued at the first communication device, switching a first link of the two reserved links, thereby allowing the first communication device to transmit the first data unit via the first link.

[0234] A23. A non-transitory computer-readable recording medium storing a computer program product which, when executed by a processor, causes the method according to embodiment A21 or A22 to be performed.

[0235] A24. A computer program comprising program code means, which is used to make the computer perform the steps of the method described in embodiment A21 or A22 when the computer program is executed on the computer.

Claims

1. A first communication device, configured to simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices including a second communication device, the second communication device being configured to simultaneously exchange data units with at least one or more third communication devices via at least two links, The first communication device comprises a circuit configured to reserve two links for data exchange once a first data unit is queued at the first communication device or once a third data unit is queued at the second communication device or the third communication device if a second data unit is expected to be queued at the second communication device at an expected arrival time.

2. The first communication device according to claim 1, in, The circuit is configured as: - once the first data unit is queued at the first communication device, using at least a first link of the two reserved links for transmitting the first data unit; and - at or after the expected arrival time, switching a second link of the two reserved links, thereby allowing the second communication device to transmit the second data unit via the second link.

3. The first communication device according to claim 1, in, The circuit is configured to reserve the two links by one or more of: - once the first data unit is queued at the first communication device, transmitting the first data unit to the second communication device; - once the third data unit is queued at the second communication device, triggering the second communication device to transmit the third data unit to the first communication device and / or the third communication device; and - Once the third data unit is queued at the third communication device, triggering the third communication device to transmit the third data unit to the first communication device and / or the second communication device.

4. The first communication device according to claim 1, in, The circuit is configured to switch the second link by transmitting a trigger or a trigger frame to the second communication device.

5. The first communication device according to claim 4, in, The circuit is configured to, in response to the trigger or the trigger frame, receive a switching response from the second communication device, if present, the switching response indicating a state of the second data unit at the second communication device.

6. The first communication device according to claim 1, in, The circuit is configured to determine the expected arrival time based on traffic information received from the second communication device, the traffic information including one or more of requirements, characteristics, and content information of the second data unit expected to be queued.

7. The first communication device according to claim 1, in, The circuit is configured to, if the first data unit has been queued at the first communication device for transmission to the second communication device before the second link is switched to the second communication device, use the second link for transmission of a portion of the first data unit to the second communication device before the second link is switched to the second communication device.

8. The first communication device according to claim 1, in, The circuit is configured to align a start and / or end of transmission of respective portions of the first data unit on the first link and the second link to the second communication device.

9. The first communication device according to claim 1, in, The circuit is configured to switch the first link and the second link to the second communication device at or after the expected arrival time, thereby allowing the second communication device to simultaneously transmit a data unit to the first communication device via the first link and transmit the second data unit to the third communication device via the second link.

10. The first communication device according to claim 1, in, The circuit is configured to transmit a first data unit to the second communication device after receiving a transmission grant and / or transmission timing information from the second communication device.

11. The first communication device according to claim 1, in, The circuit is configured to, if no first data unit is already queued at the first communication device for transmission to the second communication device at the expected arrival time of the second data unit at the second communication device, then: - using the first link for data exchange with another communication device or for broadcasting a data unit; - at the same time, switching the second link to the second communication device; and - once the first data unit is queued at the first communication device, ceasing to use the first link for data exchange with the other communication device or for broadcasting data units and starting to use the first link for transmitting the first data unit to the second communication device.

12. A second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least the first link and with the third communication device via at least the second link, the second communication device comprising circuitry configured to: - receiving from the first communication device a switch to the second link reserved by the first communication device at or after an expected arrival time at which the second data unit is expected to be queued at the second communication device, thereby allowing the second communication device to transmit the second data unit via the second link; and - transmitting the second data unit via the second link.

13. The second communication device according to claim 12, in, The circuit is configured to transmit the third data unit to the first communication device and / or the third communication device after the second communication device is triggered by the first communication device once the third data unit is queued at the second communication device.

14. The second communication device according to claim 12, in, The circuit is configured to receive a third data unit transmitted by the third communication device after the third communication device is triggered by the first communication device once the third data unit is queued at the third communication device.

15. The second communication device according to claim 12, in, The circuit is configured to receive a first data unit from the first communication device via at least the first link prior to switching to the second link.

16. The second communication device according to claim 12, in, The circuit is configured to, after the second link has been switched, transmit a switching response to the first communication device, the switching response indicating that the state of the second data unit includes one or more of the following: - said second data unit has been queued at said second communication device for transmission to said third communication device, - no second data unit has been queued at said second communication device for transmission to said third communication device, - the second data unit will be queued later than the expected arrival time, and - Updated expected arrival time.

17. The second communication device according to claim 12, in, The second communication device is configured to simultaneously transmit data units on the first link and the second link or simultaneously receive data units on the first link and the second link, but not simultaneously transmit data units on one of the two links and receive data units on the other of the two links.

18. The second communication device according to claim 17, in, The circuit is configured to align a start and / or end of transmission of data units on the first link to the first communication device and to align a start and / or end of transmission of data units on the second link to the third communication device.

19. The second communication device according to claim 17, in, The circuit is configured to transmit a transmission grant to the first communication device and the third communication device, thereby allowing the first communication device and the third communication device to transmit a data unit to the second communication device.

20. The second communication device according to claim 19, in, The circuit is configured to transmit the transmission grant in the form of a reverse direction grant RDG included in a data unit or by transmitting separate contention-free (CF) polling messages to the first communication device and the third communication device.

21. The second communication device according to claim 17, in, The circuit is configured to transmit transmission timing information to the first communication device and the third communication device, wherein the transmission timing information indicates a start time, a stop time, and / or a duration of transmission of a data unit by the first communication device and the third communication device to the second communication device.

22. A first communication method of a first communication device, wherein the first communication device is configured to simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices include a second communication device, and the second communication device is configured to simultaneously exchange data units with at least one or more third communication devices via the at least two links, the first communication method comprising: If a second data unit is expected to be queued at the second communication device at an expected arrival time, two links are reserved for data exchange once a first data unit is queued at the first communication device or once a third data unit is queued at the second communication device or the third communication device.

23. A second communication method of a second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least the first link and with the third communication device via at least the second link, the second communication method comprising: - receiving, from the first communication device, a switch to the second link reserved by the first communication device at or after an expected arrival time at which the second data unit is expected to be queued at the second communication device, thereby allowing the second communication device to transmit the second data unit via the second link; and - transmitting the second data unit via the second link.

24. A first communication device, the first communication device being configured to simultaneously exchange data units with one or more other communication devices via at least two links, the one or more other communication devices comprising a second communication device, the second communication device being configured to simultaneously exchange data units with one or more other communication devices via the at least two links, the first communication device comprising circuitry configured to: - receiving, from the second communication device, a switch to a first link reserved by the second communication device at or after an expected arrival time at which a first data unit is expected to be queued at the first communication device, thereby allowing the first communication device to transmit the first data unit via the first link; and - transmitting said first data unit via said first link.

25. The first communication device according to claim 24, in, The circuit is configured to transmit the first data unit to the second communication device once the first data unit is queued at the first communication device.

26. The first communication device according to claim 24, in, The circuit is configured to, in response to receiving a reservation indication from the second communications device indicating that the second communications device is to reserve the at least two links, transmit a reservation confirmation indicating that the at least two links are reserved or a copy of the reservation indication.

27. The first communication device according to claim 24, in, The circuit is configured to receive a switch to the first link by receiving a transmission grant from the second communication device and indicate in one or more subsequently transmitted first data units whether additional data units should be transmitted and / or whether transmission of the first data unit is complete.

28. The first communication device according to claim 24, in, The circuit is configured to receive a switch to the first link by receiving a polling message from the second communication device, and then transmit the first data unit within a time limit indicated by the polling message.

29. A second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least the first link and with the third communication device via at least the second link, the second communication device comprising circuitry configured to: - if the first data unit is expected to be queued at the first communication device at the expected arrival time, reserving two links for data exchange once the second data unit or the third data unit is queued at the second communication device; - using at least a second link of the two reserved links to transmit the second data unit and / or to receive a data unit from the third communication device; and - at or after an expected arrival time at which the first data unit is expected to be queued at the first communication device, switching the first link of the two reserved links, thereby allowing the first communication device to transmit the first data unit via the first link.

30. The second communication device according to claim 29, in, The circuit is configured to reserve the two links by performing one or more of the following: - transmitting the second data unit to the third communication device once the second data unit is queued at the second communication device, and - Once the third data unit is queued at the second communication device, transmitting the third data unit to the first communication device.

31. The second communication device according to claim 29, in, The circuit is configured to: before reserving the two links, transmit a reservation indication to the first communication device, the reservation indication indicating that the second communication device is to reserve the two links.

32. The second communication device according to claim 29, in, The circuit is configured to switch the first link by transmitting a transmission grant or polling message to the first communication device.

33. The second communication device according to claim 32, in, The circuit is configured to transmit the transmission grant in the form of a reverse direction grant RDG included in a data unit or by transmitting a separate contention-free CF poll message to the first communication device.

34. The second communication device according to claim 29, in, The circuit is configured to determine the expected arrival time based on traffic information received from the first communication device, the traffic information including one or more of requirements, characteristics, and content information of the first data unit expected to be queued.

35. The second communication device according to claim 29, in, The circuit is configured to use the first link for transmitting part of the second data unit to the third communication device and / or for transmitting the first data unit to the first communication device before the first link is switched to the first communication device.

36. The second communication device according to claim 29, in, The second communication device is configured to simultaneously transmit data units on the first link and the second link or simultaneously receive data units on the first link and the second link, but not simultaneously transmit data units on one of the two links and receive data units on the other of the two links.

37. The second communication device according to claim 36, in, The circuit is configured to: after switching the first link to the first communication device, transmit timing information to the first communication device and the third communication device, the timing information indicating the start time, and / or stop time, and / or duration of the first communication device and the third communication device transmitting a data unit to the second communication device.

38. The second communication device according to claim 36, in, The circuit is configured to simultaneously transmit a data unit to the first communication device or the third communication device via the first link and transmit the second data unit to the third communication device via the second link before switching the first link to the first communication device.

39. The second communication device according to claim 36, in, The circuit is configured to align a start and / or end of transmission of respective portions of the second data unit on the first link and the second link to the third communication device.

40. The second communication device according to claim 31, in, The circuit is configured to align a start and / or end of transmission of the reservation indication to the first communications device.

41. A first communication method of a first communication device, wherein the first communication device is configured to simultaneously exchange data units with one or more other communication devices via at least two links, wherein the one or more other communication devices include a second communication device, and the second communication device is configured to simultaneously exchange data units with the one or more other communication devices via at least two links, the first communication method comprising: - receiving, from the second communication device, a switch to a first link reserved by the second communication device at or after an expected arrival time at which a first data unit is expected to be queued at the first communication device, thereby allowing the first communication device to transmit the first data unit via the first link; and - transmitting said first data unit via said first link.

42. A second communication method of a second communication device, the second communication device being configured to simultaneously exchange data units with the first communication device via at least the first link and with the third communication device via at least the second link, the second communication method comprising: - if the first data unit is expected to be queued at the first communication device at the expected arrival time, reserving two links for data exchange once the second data unit or the third data unit is queued at the second communication device; - using at least a second link of the two reserved links to transmit the second data unit and / or to receive a data unit from the third communication device; and - at or after an expected arrival time at which the first data unit is expected to be queued at the first communication device, switching the first link of the two reserved links, thereby allowing the first communication device to transmit the first data unit via the first link.

43. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the method according to any one of claims 22, 23, 41 or 42 to be performed.

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