Channel access for multi-link devices

Abstract

According to example aspects of the application, there is provided a method comprising occupying a first channel for data transmission between a first multi-link device (MLD) and a second MLD for a first channel occupancy period (COP), transmitting a measurement request to a subset of MLDs to perform channel measurements on at least two channels during the first COP, transmitting at least one data message to the second MLD during the first COP, receiving at least one channel state report comprising channel state information from at least one of the subset of MLDs after the transmission of the at least one data message during the first COP, and selecting a channel from the at least two channels for data transmission between the first MLD and the MLDs for a second COP, wherein the selection is based at least in part on the channel state reports.

Description

TECHNICAL FIELD

[0001] Various example embodiments relate to channel access for wireless communication, in particular for multi-link devices. BACKGROUND

[0002] Wireless medium channel utilization can be based on sharing many frequencies in many wireless networks, such as wireless local area networks (WLANs). In the case of shared channels, users tune on the same channel to transmit data. Unlicensed channels can also be shared by networks of different radio access technologies (RATs). To avoid collisions, there are several access techniques, such as carrier sense multiple access with collision avoidance (CSMA-CA).

[0003] Multiple wireless communication channels can be used across multiple wireless networks, where one network overlaps with one or more other networks. A multi-link capable device can communicate with another wireless device over a radio connection that includes multiple radio links. A multi-link device can dynamically change from one channel to another channel. Operating concurrently on multiple links can improve throughput and / or reduce channel access delay.

[0004] For example, a collision can occur when one basic service set (BSS) of a WLAN occupies the channel of another BSS, where traffic on the channel in the first BSS collides with traffic on the channel in the second BSS. Devices within the first BSS can be hidden and otherwise not known or detected within the second BSS. The presence of hidden nodes or STAs within a BSS can cause collisions within the BSS.

[0005] As the number of wireless devices and networks increases, there are more overlapping networks, and transmissions can cause interference to neighboring networks. There is a need for further development and improvement of techniques that can facilitate channel access for multi-link devices. SUMMARY

[0006] Some aspects of the application are defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0007] According to a first aspect, there is provided a method comprising occupying, for a first multi-link device (MLD), a first channel for data transmission between the first MLD and a second MLD for a first channel occupancy period, transmitting a measurement request to a subset of MLDs to perform channel measurements on at least two channels during the first channel occupancy period, transmitting at least one data message to the second MLD during the first channel occupancy period, receiving at least one channel state report from at least one of the subset of MLDs after the transmission of the at least one data message during the first channel occupancy period, wherein the at least one channel state report comprises channel state information for the at least two channels, and selecting a channel among the at least two channels for data transmission between the first MLD and the MLDs for a second channel occupancy period, wherein the selection is based at least in part on the at least one channel state report.

[0008] According to a second aspect, there is provided a method comprising receiving a measurement request from a first MLD to perform channel measurements on at least two channels during a first channel occupancy period reserved for communication between the first MLD and a second MLD, performing channel measurements during the first channel occupancy period in response to the measurement request, and transmitting a channel state report comprising channel state information based on the channel measurements to the first MLD during the first channel occupancy period.

[0009] According to a third aspect, there is provided a method comprising receiving a measurement request from a first MLD to perform channel measurements on at least two channels during a first channel occupancy period, receiving at least one data message from the first MLD during the first channel occupancy period, performing channel measurements during the first channel occupancy period in response to the measurement request, and transmitting a channel state report comprising channel state information based on the channel measurements to the first MLD during the first channel occupancy period and after receiving the at least one data message.

[0010] There is also provided an apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform the features according to the first aspect, the second aspect, and / or the third aspect or any embodiment thereof.

[0011] There is also provided an apparatus comprising means configured to cause the apparatus to perform at least the method of the first aspect, the second aspect, and / or the third aspect, or any embodiment thereof. The apparatus can be or comprise a first MLD (and perform the method of the first aspect), a second MLD (and perform the method of the third aspect), and / or a third MLD (and perform the method of the first aspect), or be configured to control features of such MLDs. The means can comprise at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform.

[0012] According to a further aspect, there is provided a computer program and a computer readable or non-transitory computer readable medium comprising code configured to perform the features of the first aspect, the second aspect, and / or the third aspect, or embodiments thereof, when executed in a data processing apparatus. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A wireless communication scenario is shown;

[0014] Figure 2a and Figure 2b An example protocol stack of a multi-link device is shown;

[0015] Figure 3 , Figure 4 and Figure 5 A method according to at least some embodiments is shown;

[0016] Figure 6 is a signalling example according to at least some embodiments;

[0017] Figure 7 A channel access example is shown;

[0018] Figure 8 and Figure 9 is a signalling example according to at least some embodiments; and

[0019] Figure 10 An example apparatus capable of supporting at least some embodiments is shown. DETAILED DESCRIPTION

[0020] Figure 1A simplified wireless communication and network example is shown. A wireless communication device, in this example a user equipment (UE) 10, can be located in a cell or coverage area 30 of another device 20, which can be a wireless radio or access network node (hereinafter referred to as an AN), such as a NodeB, an evolved NodeB (eNB), a next generation (NG) NodeB (gNB), a distributed unit of an integrated access and backhaul (IAB) node, a base station, an access point, or other suitable wireless / radio access network device or system. The term base station can refer to any of a NodeB, eNB, gNB, or other base station type. Figure 1 Another AN 22 is also shown with a coverage area 40, UEs 12, 14, and 16.

[0021] The UEs 10, 12, 16 can be attached, connected, or associated with the AN 20 for wireless communication. The air interface between the UEs and the AN can be configured according to a radio access technology, RAT, that both the UE and the AN are configured to support. Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR (also referred to as Fifth Generation, 5G), and MulteFire. On the other hand, examples of non-cellular RATs and networks include IEEE 802.11 based networks, which can also be referred to as Wi-Fi or WLANs below. However, the principles of the present disclosure are not limited to a particular RAT. For example, in an NR context, the AN 20 can be a gNB, while in a WLAN context, the AN 20 can be an access point and the UEs can be non-access point stations (STAs).

[0022] The AN 20 can be connected, directly or via at least one intermediate node, with another network, a network management system, or a core network (not shown), such as a Next Generation Core network, an Evolved Packet Core (EPC), or other network management elements. The core network can include a set of network functions. A network function can refer to an operational and / or physical entity. A network function can be a particular network node or element, or a particular function or set of functions performed by one or more entities, such as a virtual network element. For example, a Third Generation Partnership Project (3GPP) 5G core network includes an Access and Mobility Management Function (AMF) that can be configured to terminate a RAN control plane (N2) interface and perform registration management, connection management, mobility management, access authentication, access authorization, a Security Anchor Function (SEAF), a Security Context Management (SCM), and support of untrusted non-3GPP access interfaces.

[0023] The AN 20 can be connected via an inter-AN / base station interface with at least one other AN (e.g., AN 22), in particular for supporting mobility of UEs 10 or for backhauling connections, e.g., over a 3GPP X2 or similar NG interface. A gNB can consist of a gNB -Control Unit (CU) and one or more gNB-Distributed Units (DUs), and the interface between gNB-CU and gNB-DU is referred to as Fl. One gNB-DU can support one or more cells (sectors).

[0024] The UEs 10, 12, 14, 16 can generally be referred to as user equipment or wireless terminals. Thus, without limitation to 3GPP user equipment, the term user equipment should be broadly interpreted to encompass various mobile / wireless terminal devices, mobile stations, and user equipment for user communications and / or machine-to-machine type communications. The UE 10 can be or include, for example, a smartphone, a cellular phone, a machine-to-machine, M2M, node, a machine-type communication node, an Internet of Things, IoT, node, a car telematics unit, a laptop, a tablet, or indeed another suitable user equipment or mobile station (i.e., terminal). In some further example embodiments, the first device or UE 10 can be a station of a WLAN or a mobile terminal (MT) part of an IAB (relay) node. Figure 1 At least some of the devices in the network can be multi-antenna devices and include antenna panels or arrays for beam-based transmission and reception. Thus, the devices can be configured to utilize their spatial degrees of freedom to beamform their transmissions and / or to place nulls towards coexisting devices.

[0025] Listen before talk (LBT) is a mechanism that allows devices and systems to share unlicensed bands while maintaining the performance of each individual system and device. LBT includes channel sensing for determining whether a channel is occupied (i.e., used by another device) or is free. For example, channel sensing can include one or more measurements of energy on the channel and a comparison of the measured energy to a threshold.

[0026] There can be wireless communication networks coexisting in the same unlicensed band, which can have different RATs. Examples of multi-system or multi-RAT coexistence include IEEE 802.11 and 3GPP 5G NR based networks coexisting on unlicensed bands.

[0027] One of the main components of license-exempt operation is the shared channel occupancy time (COT) acquired by the transmitter. In a shared COT, an initiating device, such as the AN 20, reserves the wireless medium for a transmission burst or a sequence of transmission bursts after a successful LBT. The wireless medium can include certain frequency domain allocations, such as those defined for 5G NR operation and / or for WLAN operation. The wireless medium can include a set of channels for wireless communication, such as one or more channels defined for 5G NR communication and / or channels defined for WLAN communication. The channels can be frequency channels. LBT can be performed individually for each of the channels (or can be performed jointly for multiple channels). For example, 3GPP New Radio Unlicensed (NR-U) at 5 GHz operates using 20 MHz channels. At 60 GHz, 3GPP NR-U channelization is based on 2.16 GHz bandwidth. On the other hand, in IEEE 802.11 based networks, channelization at 2.4 GHz, 5 GHz, and 6 GHz bands is based on 20 MHz primary and secondary channels.

[0028] In 802.11 based networks, carrier sensing (CS) is applied to determine whether the WLAN medium is idle, and for this purpose, both physical and virtual CS functions exist in WLAN devices. Physical CS is implemented with a clear channel assessment (CCA) that includes preamble detection and energy detection functions. Preamble detection generally refers to the ability of a receiver to detect and decode a WLAN signal preamble. The network allocation vector (NAV) is a kind of virtual carrier sensing mechanism that provides a means for channel allocation for longer periods of time than a single physical transmission. A device that has acquired a transmission opportunity (TXOP) can send a frame that defines a reservation period for channel access. A wireless device listening to the wireless medium reads this information and backs off accordingly to refrain from content on that channel for the duration of the reservation period. The reservation period or TXOP is an example of a COT or channel occupancy period.

[0029] In some legacy devices, a single protocol stack is supported when there is a single protocol entity on the physical layer and upper and lower medium access control (MAC) layers. The physical layer can handle the radio frequency and baseband signal processing tasks in transmission and reception. The physical layer can also run the CCA and, in some devices, it can be able to run the CCA concurrently for multiple channels, even though it can not be able to receive / transmit frames concurrently in different channels. In some embodiments, the MAC layer can be responsible for the channel contention by the lower MAC layer based on inputs from the physical layer and in particular from the CCA. The MAC layer can be responsible for the association and authentication procedures, in some embodiments, e.g., by the upper MAC layer. In other legacy devices, multiple MAC layers and multiple physical layers can be provided, but the number of MAC layers is equal to the number of physical layers. Such devices can support multi-channel operation, conditioned on that the channel contention is performed only on the primary channel. Once the channel contention on the primary channel is successful, the device can transmit frames on the primary channel and further on one or more secondary channels. The CCA procedure can be performed on the secondary channel(s) to ensure that they can also be idle for transmission.

[0030] A multi-link device (MLD) is a device that is capable of operating dynamically on multiple links and switching between the related channels. An MLD can be capable of operating on two or more links simultaneously. The links can be in different frequency bands, such as the 2.4 GHz and 5 GHz bands reserved for unlicensed operation.

[0031] As 802.11 networks evolved, multi-link capabilities were also proposed for 802.11 based systems. The IEEE 802.11 be task group, which is the basis for future Wi-Fi 7 devices, is currently considering a multi-link feature that allows devices to operate dynamically on several channels / bands simultaneously. With multi-link capabilities, each packet can be transmitted through any of the channels / links. The main motivations for the multi-link feature include that the peak throughput increases if multiple channels / links are used simultaneously, and the channel access latency is reduced because a device can contend on multiple channels or links simultaneously and select the first channel that is available for data transmission. Providing latency and reliability guarantees can enable many use cases, including deploying industrial dedicated networks in unlicensed spectrum and enhanced / virtual reality applications.

[0032] Figure 2a An example protocol stack for an MLD is shown, which includes a single upper MAC layer 200, multiple lower MAC layers 202, 204, and a single physical layer 206 that serves the multiple lower MAC layers.

[0033] Figure 2bAn example protocol stack for an MLD is shown, which supports a single upper MAC layer 210, multiple lower MAC layers 212, 214, and a physical layer 216, 218 for each lower MAC layer 212, 214. A set of channels (not shown), such as NR-U or 802.11 channels, can be available for each physical layer 206, 216, 218.

[0034] For example, the UEs 10, 12 and the AN 20 can be MLDs and support a protocol stack of Figure 2a or Figure 2b The multiple lower protocol layers (each upper MAC layer 200, 210) enable the MLD to contend on multiple channels simultaneously and / or independently, for example, within the same 802.11 association, and to transmit on multiple channels in parallel and / or independently (depending on the support available by the physical layer). Thus, a single association can be referred to as a multi-link association enabled by multiple physical layers (and multiple lower MAC layers) per upper MAC layer. This is different from a legacy device that has multiple physical layers and multiple lower MAC layers but only a single physical layer and a single lower MAC layer per upper MAC layer. The multi-link capability also allows multiple associations between the lower MAC layers within a single association of the upper MAC layers of the wireless device.

[0035] Depending on the number of physical layers, the channels of the multi-link association can be located on different frequency bands that are close or far apart from each other. The far apart can be understood as being separated such that transmission or reception on a channel would not be possible without using a dedicated radio front-end (physical layer) for each channel. For example, an MLD that supports multiple physical layers 216, 218 can be able to transmit or receive frames on multiple channels of multiple far apart frequency bands concurrently. In the context of an 802.11 system, one of the channels can include a channel on the 2.4 GHz frequency band, while another of the channels can include a channel on the 5 GHz frequency band. Other systems can employ other frequency bands.

[0036] However, the channels can also be provided on the same frequency band. In this case, an MLD with a single physical layer 206 serving multiple lower MAC layers can be able to transmit or receive frames on multiple channels of a single frequency band (e.g., the 2.4 GHz frequency band or the 5 GHz frequency band) concurrently. These embodiments alleviate channel access in the sense that the MLD is not necessarily limited by congestion on one of the channels or frequency bands (e.g., a primary channel) of the wireless network. When the channels are on the same frequency band, device implementation can impose some limitations on the ability to transmit simultaneously over multiple links. The device can have the ability to indicate such limitations to other devices, for example, via one or more information elements in data frames and / or management frames.

[0037] At least some multi-link wireless devices can be designed as low-cost devices with limited signal processing capabilities. While such devices can transmit or receive concurrently on multiple channels and through multiple links, they may have limited capacity to concurrently process two frames received over two different links. This MLD (Multi-Link Device) can concurrently sense two channels but cannot concurrently decode multiple frames received over different channels. This situation may arise from the device's design; for example, the device may have low signal processing capabilities, preventing it from concurrently processing two (or more) received frames. However, this situation can occur when the device's processing resources are temporarily occupied by another task. The device may have sufficient processing power to concurrently process two (or more) frames, but this capability is temporarily unavailable. Other scenarios where limited processing power restricts the concurrent processing of two (or more) frames received over different links can be envisioned.

[0038] like Figure 1 As shown, AN 20 can first communicate with UE 10 via channel A. AN 20 can then continue communication, for example, transmitting (multiple) additional frames via channel B (A->B), without needing to transfer all BSS operations from channel A to channel B as in traditional channel handover scenarios. However, AN 22 can communicate with UE 14 via channel B, interfering with UE 10 after the transmission to channel B. Since AN 22 is outside the coverage area 30 of AN 20, AN 20 will not detect AN 22 when performing LBT in link B.

[0039] The presence of hidden nodes can cause significant delays and affect reliability. In this situation, multi-link operation can introduce some robustness against interference, although it does not solve the hidden node problem. This is because one or more links can be dynamically selected for subsequent transmissions. Figure 1 The MLD in AN 20 may perceive the medium as idle and perform incorrect link selection, meaning that some relevant devices (UE 10) may be unable to receive / transmit data.

[0040] The presence of hidden nodes can hinder the practical implementation of multi-link solutions designed to provide a certain level of throughput, particularly latency and reliability, in unlicensed frequency bands. The initiator of MLD may not be interested in or able to utilize the entire available bandwidth for active transmission / reception simultaneously and may dynamically switch between links. Therefore, in cases where, for example, the first portion of the bandwidth is occupied or backed off, the initiator of MLD may want to quickly select and use the second portion of the bandwidth for subsequent transmission / reception.

[0041] Improvements are now provided to facilitate ensuring that an MLD selects a channel and link that is idle and ready for access by devices involved in the communication.

[0042] Figure 3 A method for arranging channel access is shown, in particular for selecting a method for directional channel occupancy detection, which can also be referred to as channel sensing type or method. The method can be performed by an apparatus, which can be a wireless communication device or a controller thereof. The method can be performed by a first MLD, which can be a (communication) initiating device in communication with a second (responding) MLD, such as a UE 10, such as an AN 20, as also referred to in subsequent embodiments.

[0043] The method comprises occupying 300 a first channel for data transmission between the first MLD and a second MLD for a first channel occupancy period. A measurement request is transmitted 310 to a subset of MLDs to perform channel measurements on at least two channels during the first channel occupancy period, which can also be referred to as channel occupancy time (COT), as described below. At least one data message is transmitted 320 to the second MLD during the first COT. During the first COT, at least one channel status report is received 330 from at least one MLD of the subset of MLDs after transmission of the at least one data message. The channel status report(s) can comprise channel status information for the at least two channels. A channel is selected 340 of the at least two channels for data transmission between the first MLD and the MLD for a second COT. The selection is based at least in part on the received channel status report(s), and can involve selection of a link to be applied by the first MLD during the second COT.

[0044] Figure 4 A method for facilitating channel access is shown. The method can be performed by an apparatus, which can be a wireless communication device or a controller thereof. The method can be performed by a second MLD, which can be a responding device in communication with a first MLD, such as a UE 10, which can be a communication initiating device performing the method, such as an AN 20. Figure 3

[0045] ​The method comprises receiving 400, from a first MLD, a measurement request to perform channel measurements on at least two channels during a first COT reserved between the first MLD and a second MLD. The measurement request can be addressed to a subset of MLDs. At least one data message is received 410 from the first MLD during the first COT. The channel measurements are performed 420 during the first COT in response to the measurement request. A channel status report comprising channel state information based on the channel measurements is transmitted 430 to the first MLD during the first COT. The channel status report can be used to select a channel among the at least two channels for data transmission between the first MLD and the MLD within a second COT.

[0046] Figure 5 A method for facilitating channel access is shown. The method can be performed by an apparatus, which can be a wireless communication device or a controller thereof. The method can be performed by a third MLD, which can be a responding device, such as a UE 10, responding to a communication of a first MLD, such as an AN 20.

[0047] The method comprises receiving 500, by a third MLD, from a first MLD, a measurement request to perform channel measurements on at least two channels during a first COT reserved for communication between the first MLD and a second MLD. The measurement request can be addressed to a subset of MLDs. The first COT is used for transmitting at least one data message from the first MLD to the second MLD. The channel measurements are performed 510 during the first COT in response to the measurement request. A channel status report comprising channel state information based on the channel measurements is transmitted 520 to the first MLD during the first COT. The channel status report can be used to select 340 a channel among the at least two channels for data transmission between the first MLD and the MLD within a second COT.

[0048] It is noted that an end user device or an infrastructure network device or components thereof can be configured to selectively operate as an initiating or responding MLD and to perform one of the methods of Figure 3 ) or responding device Figure 4 or Figure 5 ) according to the currently assumed role of the initiating Figure 3 to Figure 5 It will be appreciated that in relation to the methods of Figure 3 to Figure 5 various other features and blocks can exist. Some example embodiments are shown below.

[0049] The measurement request can be transmitted before the first channel 300 is used for transmission (i.e., before the first COT). Therefore, block 310 can be performed before block 300. In another embodiment, the measurement request is transmitted after block 300. In some embodiments, the measurement request is transmitted during the first COT. The measurement request can be transmitted at the beginning of the first COT, for example, in the first frame that begins the first COT. The measurement request can be embedded in or appended to a data frame transmitted during the first COT.

[0050] Measurement requests in blocks 310, 400, and 500 can be addressed and can identify subsets of MLDs(s). In some embodiments, the subset may include multiple MLDs, while in other embodiments, the subset may consist of a single MLD. Measurement requests can be transmitted 320 to multiple MLDs(s) that support multi-link measurement capabilities. This capability can be reported by the MLDs, thereby allowing a first MLD to select an MLD for transmission 310 of the measurement request. MLD selection may occur in a separate block preceding block 310. MLDs can be selected into the subset based on their attributes or requirements, in one embodiment based on delay and / or reliability requirements. Thus, MLDs with stringent delay and / or reliability requirements can be selected into the subset. However, other criteria can be applied alternatively or additionally to select MLDs for channel measurements. For example, in Figure 1 In this scenario, AN 20 can select UE 10 and 12 to perform measurements, but not UE 16.

[0051] In another embodiment, the measurement request does not specifically identify the MLD(s), but is transmitted, for example, as a broadcast-type message in the relevant radio access network. However, the measurement request may only be applied to devices with multi-link capabilities. The MLDs may belong to the same radio access network, such as an 802.11-based network or a 3GPP-based NR-U network. A second MLD and at least one / third MLD may be associated with a first MLD. The (initiating) first MLD may specify the channels or links that the (responding) MLD(s) should report, and indicate these specified channels or links in the measurement request. In one example, the first MLD may request the responding MLD to perform measurements only on channels that the first MLD deems available, thus further reducing the use of resources for measurement.

[0052] Upon reception of the measurement request, which can request a multi-link medium state report for hidden node prevention, the MLDs can perform channel measurements in blocks 420 and 510 to determine the medium state of a set of channels and links in which the devices can be subsequently served. The MLDs can include information indicating the medium state in transmissions prior to the start of data transmission / reception during the second COT (as a channel state report), which can thus be performed in different channels and links.

[0053] The first MLD can dedicate time and frequency resources for the reception of channel state reports during the first COT. Such resources can be indicated to the subset of MLDs in the measurement request. Then, in block 430 / 520, the second / third MLD adapts the transmission of channel state reports according to the received resource information. There can be multiple downlink and uplink portions in the COT, the uplink herein referring to the transmission direction from the other (second / third) MLDs to the first MLD (e.g., UE 10 or AP 20). The specific uplink transmission in which the channel state report should be provided can be identified according to the scheduling indication of the first MLD in the measurement request. Preferably, the last uplink transmission is controlled to be used for transmitting the channel state report. For example, in case of communication between a (MLD) UE and a gNB, which plays the role of the first MLD / initiating device, the gNB can reserve resources that the UE should use to transmit its channel state report.

[0054] Thus, (also) in block 330, one or more channel state reports can be received from the (multiple) (third) MLDs, which are not recipients of the data message(s) 310 transmitted by the first MLD during the first COT. For example, a channel state report from UE 12 can be relevant to avoid selecting channel B used by AN 22 to UE 14.

[0055] The first MLD can perform LBT procedures and channel measurements, which can be additional blocks prior to block 340. Then, the first MLD can select, in block 340, channels and links for subsequent transmission / reception within the second COT further based on the medium state based on its own performed measurements of the channels. A (sub)set of unoccupied channels (among the channels for which measurement results are available) can be determined based on all available channel measurement information, and a channel and related link can be selected among the unoccupied channels in the set.

[0056] Then, after block 340, during a second COT after the first COT, the first MLD can transmit (a) further data message(s) to the second MLD, third MLD, or another (fourth) MLD at a channel selected based on the channel status report of block 330, 430, 520. Thus, the second MLD / third MLD / fourth MLD receives (a) data message(s) from the first MLD at the channel (selected by the first MLD) based on the channel status report after block 430 / 520.

[0057] This feature facilitates improving channel state awareness for the first MLD to select a channel and link for a subsequent data transmission, thereby enabling further mitigation or avoidance of the hidden node problem. The first MLD can acquire channel state information from other (third) MLDs during the first COT with the second MLD and thus has relevant channel state as seen by the third MLDs readily available for the second COT communication with such third MLDs. The first MLD has up-to-date channel state information already available when the first COT ends, thereby enabling avoidance of delay caused by channel state measurement after the first COT or at the beginning of the second COT. This feature enables identification and utilization of availability of MLD-specific medium state information that can also be applied to resolve a subsequent data transmission during the second COT.

[0058] Figure 6 Signaling between a first MLD (MLD#1), a second MLD (MLD#2), and a third MLD (SLD#3) performing the methods of Figure 3 , Figure 4 or Figure 5 is shown.

[0059] MLD#1 can activate a multi-link hidden node prevention mode and transmit a measurement request(s) 602 to a subset of MLDs, in this example MLD#2 and MLD#3. For example, the hidden node prevention model engine can set a hidden node prevention model flag as input and cause MLD#1 to enter block 602. The measurement request can be a request to activate a multi-link medium state report mode in the receiving MLDs. It will be appreciated that the measurement request 602 can be transmitted to MLD#2 and #3 by a single transmission or by separate messages.

[0060] A channel access engine of MLD#1 acquires a (first) COT, COT#1 604, which in this example starts after the transmission of the measurement request 602. In another embodiment, the measurement request is transmitted during COT#1. MLD#1 communicates with MLD#2 during COT#1 and can transmit data frame(s) 606 to MLD#2.

[0061] The measurement request 602 causes MLD#2 and MLD#3 to perform channel measurements 608, 612 on at least two channels during COT#1 604. In one embodiment, in response to the measurement request 602, MLD#2 and #3 enter a multi-link hidden node prevention mode to control the measurements. MLD#1 can force an uplink transmission in the second half of COT#1, preferably near the end of COT#1, to transmit a channel state report including channel measurement information based on the channel measurements.

[0062] The channel measurements and / or reporting timing of MLD#2 and #3 can be controlled based on timing information in the measurement request 602 and / or by configuration of the (multi-link hidden node prevention) mode activated by the measurement request. MLD#2 and #3 can be caused or configured to check whether a last uplink transmission is to be performed and perform channel measurements, including a channel state report, immediately before initiating the last uplink transmission. For example, MLD#2 and #3 can be controlled to perform measurements 608, 612 on a configured set of channels during a DL time slot or symbol of the ongoing COT#1 604.

[0063] MLD#2 and #3 transmit respective channel state reports 610, 614 to MLD#1 during COT#1. MLD#1 selects 616 a channel in which it has received at least one of its measurement reports 610, 618 for communication during a second COT#2 618. Based on a successful LBT procedure on the available channel(s), i.e., upon detecting that the wireless medium is not occupied, MLD#1 can thus reserve the wireless medium for subsequent transmissions. COT#2 and the selected channel can be used by MLD#1 for communication with MLD#2, MLD#3, or another MLD that has been involved or not involved in the channel measurement reports during COT#1 604. Figure 6 An example shows transmission of a data frame 620 to MLD#2. In another example embodiment, MLD#1 can select another receiving MLD (e.g., MLD#3) and / or another channel for transmission of a data frame during COT#2 based at least in part on one or more of the received channel state reports.

[0064] Thus, MLD#1 can dynamically change from one channel to another channel and from one link to another link based on channel measurements performed from multiple measurements on multiple channels. Since the channel measurements have been performed during the ongoing COT#1, MLD#2 can reserve COT#2 on the selected channel immediately after the end of COT#1.

[0065] A channel and link can be randomly selected 340, 616 from the set of channels detected as unoccupied by the first MLD #1 based on the received channel state report(s) and measurement information. The first MLD can prioritize channel state reports from one or more responding MLDs (such as the second MLD #2) of the method of Figure 4 In example embodiments, the first MLD can prioritize channel state reports from MLD(s) based on latency and / or reliability requirements of the MLDs. Thus, reports from MLDs with more stringent latency or reliability requirements can be prioritized. Such prioritization can be applied, for example, if no channel and link is detected as unoccupied for both the first MLD and the responding MLD(s).

[0066] The MLDs can perform LBT procedures in accordance with the applied RAT. Some examples of available channel access schemes include: a) immediate transmission after a short switching gap from receiving a transmission, b) LBT with no random backoff, c) LBT with random backoff with a fixed size contention window, and d) LBT with random backoff with a variable size contention window.

[0067] The measurement request 310, 400, 500, 602, channel state report(s) 330, 430, 520, 610, 614, and data transmission (during the first COT and / or the second COT) 320, 340, 410, 606, 620 use the same radio technology. That is, the respective transmission / reception events can be performed by a single RAT unit of the apparatus performing the method of Figure 3 , Figure 4 or Figure 5 The responding MLDs can be able to simultaneously receive / transmit data in one channel / link and sense the medium (e.g., by energy detection) in different channels / links with the same RAT.

[0068] In some embodiments, the wireless access network is a NR-U or 802.11 based network, and the MLDs comprise NR-U transceivers and / or WLAN transceivers. The first MLD can be (configured to operate as) a gNB and / or an access point (AP), while the other MLDs #2, #3 can be (configured to operate as) non-AP stations and / or user equipment. For example, the AN 20 is performing the method of Figure 3 and is configured to operate as a gNB comprising an NR-U transceiver (i.e., configured to operate a communication unit in the unlicensed spectrum on a basis of 3GPP NR based access). The AN 20 can also be configured to operate as a WLAN AP.

[0069] In another example embodiment, the first MLD is a non-AP station or user equipment that can communicate with an AP or gNB, or a non-AP station or user equipment that communicates with another non-AP station and / or user equipment that can operate as a second MLD or a third MLD. Some other example embodiments are shown below for 802.11-based WLAN and 3GPP 5G-based systems.

[0070] There can be coexisting wireless communication networks that coexist in the same unlicensed band, which can belong to different RATs. Figure 7 An example is shown in which a WLAN and a cellular network, such as an NR-U network, coexist in the same unlicensed band. Multi-RAT MLDs, i.e., MLDs that support more than one RAT, can operate at least partially on the same channel through different RATs. For example, various coexistence scenarios are facilitated in which a gNB is a neighbor of a WLAN AP. These methods also bring benefits for relay-type network nodes. For example, 3GPP Integrated Access Backhaul (IAB) relays and WLAN relays / bridges can be configured to apply at least some of the above-described embodiments.

[0071] In Figure 7 example, an NR-U compliant gNB operates as a first / initiating MLD that performs the method of Figure 3 The multi-link gNB in this example can be capable of simultaneously operating in 6 channels, which can at least partially have different links, but can only transmit / receive on a subset of the channels at a time. At a first downlink (D) transmission 700, the gNB requests channel state feedback by transmitting a measurement request. At time 702, channel sensing (LBT) is performed, which can indicate that channels B, D, and F are occupied by WLAN traffic. During an uplink (U) slot 704, the scheduled MLD(s) transmit their channel state report(s) to the gNB, which indicates channel state in candidate channels / links (at least some of A-F). The gNB also performs 706 channel sensing in channel A in the last uplink slot of the COT, and selects 708 the next channel D based on the received channel state information and its own measurements. The gNB can then immediately acquire the subsequent COT of channel D and start transmission 710. Similarly, in the last uplink slot, a channel state report is received 712. The gNB detects that channel B is not occupied, and selects 714 channel B for a subsequent transmission 716.

[0072] Depending on the signaling interface applied between the MLDs, the above signaling messages can be included in a burst or a frame. At least some of the above information can be added in a new information element or in an existing information element of applicable messages.

[0073] There are many options that can be used to schedule the transmission of the measurement request and the channel state report. In some example embodiments, the measurement request is included in system information within a physical downlink control channel (PDCCH) transmission, in a dedicated radio resource control (RRC) signal, or in a groupcast message. In one example, the gNB includes the measurement information in a system information block (SIB) of the PDCCH transmitted to all devices within the coverage of the gNB. The subset of MLDs can thus refer to MLDs associated with or reachable to the first MLD. The measurement request message can also convey information about a specific set of channels / links in which the configured MLDs should perform measurements.

[0074] For example, if the first MLD is a UE, e.g., UE 10, and the destination of the communication is another UE, e.g., UE 12, i.e., there can be a sidelink or device-to-device (D2D) communication stream, the measurement request can be transmitted to the other UE or group of UEs at least by, e.g., groupcast. Thus, the initiating UE 10 can reserve resources that the responding MLDs (UEs) should use to transmit their channel state reports.

[0075] In some embodiments, the channel state report in block / message 330, 430, 520, 610, 614 provided by the responding device can include a binary indication of the channel state, i.e., free or busy. Thus, blocks 420, 510, 608, 612 can include performing channel sensing and indicating the results of the channel sensing as channel state information in the channel state report. In another embodiment, the channel state report and channel state information indicates the measured power level of each channel. The channel measurements can include (and the channel state report can indicate) a one-time measurement, a measurement averaged over a time window, or a measurement based on a specific measurement sample, i.e., a sample vector. However, it should be understood that these represent only some examples of how the measurement information can be included in the channel state report.

[0076] In some embodiments, as already explained, the presently disclosed features are applied to access an unlicensed wireless medium by 3GPP 5G systems. NR Release 15 defines operation up to frequencies of 52.6 GHz. In addition, unlicensed band access beyond 52.6 GHz (around 60 GHz) is also being studied. In example embodiments, at least some (as-is or modified) of the LBT type or category 5G channel access schemes are applied. Such access schemes can include category 1 immediate transmission and one or more of two or more additional LBT categories that can be defined in the channel access schemes of 3GPP TR 38.889.

[0077] In example embodiments, reference is made to the simplified Figure 8, the gNB transmits a measurement request (which can be an activation message for a multi-link hidden node prevention mode) at the beginning of each COT / TXOP as a PDCCH message 800 or part thereof. The measurement request can be included in a group common PDCCH transmission, e.g., by applying downlink control information (DCI) format 2_0 or another appropriate format. The DCI fields indicating the measurement request and its potential further parameters (e.g., channels to be measured) can be included in the PDDCH message 800.

[0078] In example embodiments, the channel status report is included in physical uplink control channel (PUCCH) signaling from the NR-U UE to the gNB. Thus, based on the channel measurements 802, the UE can transmit a PUCCH message including a channel status report 804, based on which the gNB selects 806 channels and links for subsequent data transmissions and COT based on the PUCCH (and its own channel measurements). For example, the channel status report can be included in other uplink control information, such as channel quality indicators (CQI) and hybrid automatic repeat request (HARQ) ack / nack (A / N) feedback.

[0079] IEEE 802.11be (also known as Extremely High Throughput (EHT) Wi-Fi) is one example of an 802.11 version / system in which at least some of the above-described features can be applied.

[0080] Figure 9 A simplified example of an embodiment of a WLAN-based system is shown. The AP can transmit a measurement request in an 802.11 management frame 900.

[0081] In response to the frame 900, the STA performs channel measurements 902. The STA can then transmit a frame 904 including a channel status report during the ongoing TXOP. Based on the report (and its own channel measurements), the AP selects 906 WLAN channels and links for subsequent data transmissions and TXOP. Changes to the newly selected channels can be arranged without transmitting BSS operations between the channels.

[0082] In some embodiments, Figure 3 , Figure 4 or Figure 5 At least some of the transmission and / or reception events, or embodiments thereof, are performed by two different RATs.

[0083] In an example embodiment, the transmission / reception of the measurement request 310, 400, 500, 602 and the channel state report 330, 430, 520, 610, 614 is performed via a first RAT, and the channel measurement 420, 510, 608, 612 is performed via a second RAT. This can be beneficial in case the responding (second / third) MLD is equipped with multiple RATs (e.g., NR-U and WLAN), the first RAT (e.g., NR-U) is used for communication with the initiating (first) MLD (where the first RAT cannot transmit / receive in one link and sense the medium in a different link), and the second RAT (i.e., WLAN) can be utilized for multi-link medium sensing purposes. Thus, when a measurement request is received via the NR-U interface, the WLAN interface is activated (via the inter-RAT interface) for multi-channel / link state sensing. Channel measurement information is provided from the WLAN interface / unit to the NR-U interface / unit, which transmits the information in a channel state report to the gNB.

[0084] In another example embodiment, the transmission / reception of the measurement request 310, 400, 500, 602 and at least one channel state report 330, 430, 520, 610, 614 is performed via a first RAT (such as WLAN), and the data transmission 320, 340, 410, 606, 620 is performed via a second RAT (such as NR-U). The channel measurement 420, 510, 608, 612 can be performed via the first RAT or the second RAT. Thus, after receiving the measurement report via the first RAT and detecting or selecting the available channels and links, the first MLD can inform or trigger the available channels and links to the second RAT (via the inter-RAT interface). Thereby, the second RAT can reserve the available channels and start data transmission in response to the received information. Thus, the first RAT can be used to enable the hidden node prevention mode, while the second RAT can be used to enable data transmission / reception. This allows, among other potential benefits, to reduce the communication overhead in the wireless interface used for data transmission / reception.

[0085] In one embodiment, in accordance with the dynamic multi-link operation discussed in one or more of the above embodiments, the change to the newly selected channel does not include transmitting a channel switch announcement frame / element or an extended channel switch announcement frame. In one embodiment, no channel switch frame is transmitted prior to initiating data transmission on the newly selected channel.

[0086] In one embodiment, the MLD is a device with more than one affiliated STA and with one MAC SAP to a logical link control (LLC) that includes one MAC data service. In such an embodiment, the first device / MLD and / or the second device / MLD can include multiple affiliated STAs. In one embodiment, a first affiliated STA of the MLD can operate on a first channel of the multi-link association, while a second affiliated STA of the MLD can operate on a second channel of the multi-link association, and the change to the newly selected channel can include selecting the second affiliated STA for transmission of the additional data frame.

[0087] While some embodiments have been described in the context of systems based on 5G NR-U and WLAN / IEEE 802.11, it is to be understood that these or other embodiments of the application can be applicable in connection with other technologies configured to operate on licensed or unlicensed bands, such as wireless devices operating according to other local connectivity technologies, 6G cellular systems, or other existing or future technologies that facilitate dynamic multi-link operation.

[0088] An electronic device comprising electronic circuitry can be an apparatus for implementing at least some embodiments of the application. The apparatus can be a computer, a laptop, a tablet, a cellular phone, a machine-to-machine (M2M) device (e.g., an IoT sensor device), a base station, an access point or node device, or any other apparatus provided with radio communication capabilities, or can be included therein. In another embodiment, an apparatus performing the above-described functions is included in such a device, e.g., the apparatus can comprise circuitry such as a chip, a chipset, a microcontroller, or a combination of such circuitry in any of the above-listed devices.

[0089] The apparatus can comprise communication circuitry providing the apparatus with the ability to communicate in at least one wireless network. The communication circuitry can employ a radio interface providing the apparatus with radio communication capabilities. The radio interface can comprise radio-modem RF circuitry providing at least part of the above-mentioned physical layer(s) of the wireless device. In embodiments where the apparatus is a wireless device, the radio interface can be included in the apparatus. In other embodiments where the apparatus is a chipset of a wireless device, the radio interface can be external to the apparatus.

[0090] According to the principles described above, the radio interface can support transmission and reception. The RF circuitry can include radio frequency converters and components such as amplifiers, filters, and one or more antennas. The radio modem can include baseband signal processing circuitry such as (de)modulator and encoder / decoder circuitry. The communication circuitry can perform at least some of the functions of the MAC layer(s) described above. In embodiments in which the apparatus employs multiple physical layer entities, the radio modem and RF circuitry can employ separate transmitter and receiver branches for each of the multiple links supported by the apparatus. The radio modem and RF circuitry can include dedicated circuitry for the physical layer and another dedicated circuitry for the physical layer, although the dedicated circuitry can employ some of the same physical components in transmission and / or reception. The communication circuitry can include multiple channel sensing circuitry, each configured to perform channel sensing on a channel.

[0091] As used in this application, the term“circuitry” can refer to one or more or all of the following:

[0092] (a) hardware-only circuitry implementations (such as implementations in only analog and / or digital circuitry) and

[0093] (b) combinations of hardware circuits and software, such as (as applicable):

[0094] (i) combinations of analog and / or digital hardware circuit(s) with software / firmware and

[0095] (ii) any portions of hardware processor(s) with software (including digital signal processors), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and

[0096] and

[0097] (c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but need not necessarily have such software present to operate. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation that has a hardware circuit or processor (or multiple processors) and software (or firmware) that works together to cause an apparatus to operate a device. For example, and if applicable to the particular claim element, the term circuitry also covers, for a mobile device or server or similar, a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in server, cellular network device, or other computing or network device.

[0098] Figure 10 An example apparatus capable of supporting at least some embodiments of the application is shown. Shown is a device 1000, which can comprise a communication device, such as a UE 10, 12 or an AN 20, arranged to operate as a first MLD, a second MLD and a third MLD. The device can comprise one or more controllers configured to perform operations in accordance with at least some of the above-described embodiments, such as the above-described methods, some or more features of which are shown. For example, the device can be configured to operate as an apparatus configured to perform the methods shown in Figure 3 to Figure 9 Figure 3 , Figure 4 and / or Figure 5 .

[0099] The device 1000 comprises a processor 1002, which can comprise, for example, a single-core or multi-core processor, where a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. The processor 1002 can comprise more than one processor. The processor can comprise at least one application-specific integrated circuit, ASIC. The processor can comprise at least one field-programmable gate array, FPGA. The processor can be a means for performing method steps in a device. The processor can be configured, at least partly by computer instructions, to perform actions.

[0100] The device 1000 can comprise a memory 1004. The memory can comprise a random access memory and / or a persistent memory. The memory can comprise at least one RAM chip. For example, the memory can comprise solid-state, magnetic, optical and / or holographic memory. The memory can be accessible, at least partly, by the processor 1002. The memory can be comprised, at least partly, in the processor 1002. The memory 1004 can be a means for storing information. The memory can comprise computer instructions that the processor is configured to execute. When computer instructions configured to cause the processor to perform certain actions are stored in the memory, and the device is generally configured to run using computer instructions from the memory under direction of the processor, the processor and / or at least one processing core thereof can be considered configured to perform the particular actions. The memory can be comprised, at least partly, in the processor. The memory can be at least partly external to the device 1000, but accessible by the device. For example, control parameters affecting operations related to acquiring channel and link state information can be stored in one or more parts of the memory, and used to control operation of the apparatus. Furthermore, the memory can comprise device-specific cryptographic information, such as secret and public keys of the device 1000.

[0101] ​The device 1000 can comprise at least one transmitter 1006 and at least one receiver 1008. The transmitters and receivers can comprise, for example, the communication circuitry as shown above and be configured to operate according to wireless, cellular or non-cellular standards, such as Wideband Code Division Multiple Access, WCDMA, Long Term Evolution, LTE, 5G or other cellular communication systems, and / or WLAN standards. The device 1000 can comprise a transceiver of another RAT or a Near Field Communication, NFC, transceiver 1010. The NFC transceiver can support at least one NFC technology, such as NFC, Bluetooth, Wibree or similar technologies.

[0102] The device 1000 can comprise a user interface, UI, 1012. The UI can comprise at least one of a display, a keypad, a touchscreen, a vibrator arranged to signal to a user by causing the device to vibrate, a loudspeaker and a microphone. A user can be able to operate the device, e.g., configure or control the device, via the UI.

[0103] The device 1000 can comprise or be arranged to accept a user identity module or other type of memory module 1014. For example, the user identity module can comprise a Subscriber Identity Module, SIM, and / or a Personal Identity IC Card, which can be installed in the device 1000. The user identity module 1014 can comprise information identifying a user subscription of the device 1000. The user identity module 1014 can comprise cryptographic information that can be used to verify the identity of a user of the device 1000 and / or to facilitate encryption and decryption of communications implemented via the device 1000.

[0104] The processor 1002 can be equipped with a transmitter arranged to output information from the processor to other devices comprised in the device 1000 via electrical leads inside the device 1000. Such a transmitter can comprise a serial bus transmitter arranged to output information, e.g., to the memory 1004 for storage therein, via at least one electrical lead. As an alternative to a serial bus, the transmitter can comprise a parallel bus transmitter. Likewise, the processor can comprise a receiver arranged to receive information in the processor from other units comprised in the device 1000 via electrical leads inside the device 1000. Such a receiver can comprise a serial bus receiver arranged to receive information, e.g., from the receiver 1008 for processing in the processor, via at least one electrical lead. As an alternative to a serial bus, the receiver can comprise a parallel bus receiver.

[0105] The device 1000 can comprise Figure 10The device can include at least one digital camera. Some devices can include a rear-facing camera and a front-facing camera. The device can include a fingerprint sensor arranged to at least partially authenticate a user of the device. In some embodiments, the device lacks at least one of the aforementioned devices. For example, some devices can lack the NFC transceiver 1010 and / or the user identity module 1014.

[0106] The processor 1002, the memory 1004, the transmitter 1006, the receiver 1008, the NFC transceiver 1010, the UI 1012, and / or the user identity module 1014 can be interconnected through electrical leads inside the device 1000 in a variety of different ways. For example, each of the aforementioned devices can be individually connected to a main bus inside the device to allow the devices to exchange information. However, as will be appreciated by those skilled in the art, this is merely one example, and various ways of interconnecting at least two of the aforementioned devices can be selected without departing from the scope of the application, depending on the embodiment.

[0107] It should be understood that the disclosed embodiments of the present application are not limited to the particular structures, process steps, or materials disclosed herein but are extended to equivalents thereof The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0108] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. In cases where the terms "approximately," "about," or the like are used to modify a numerical value, exact numerical values are also contemplated.

[0109] As used herein, a plurality of items, structural elements, compositional elements, and / or functional features can be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on its presence therein. Further, various embodiments and examples of the present application can be referenced by "a" or "an" herein. This is done merely for convenience and to give a general sense of the draft to the reader. This description should be read to include the plural as well as the singular, both of which together encompass the meaning of the term "one" in the context of the description.

[0110] Furthermore, in one or more embodiments, the described features, structures, or characteristics can be combined in any suitable manner. In the preceding description, numerous specific details were provided to provide a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the application can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the application.

[0111] In this document, the terms“comprise to comprise” and“comprise to include” are used in an open-ended way to mean includes, but is not limited to. Unless otherwise specified, the use of the ordinal adjectives (e.g., first, second, etc.) to describe a particular noun (e.g., element, component, region, layer, or section) should not be construed to mean that two or more such specifically identified nouns are present. Rather, these terms are used interchangeably and are merely used to more clearly describe one element, component, region, layer, or section compared to another element, component, region, layer, or section. The terms“first,”“second,” and the like, do not imply a sequence or order unless specifically stated.

Claims

1. A method of communication for an apparatus, comprising: - occupying a first channel for data transmission between a first multi-link device and a second multi-link device for a first channel occupancy period, - transmitting a measurement request to a subset of multi-link devices to perform channel measurements on at least two channels during the first channel occupancy period, - transmitting at least one data message to the second multi-link device during the first channel occupancy period, - receiving at least one channel state report from at least one multi-link device of the subset of multi-link devices during the first channel occupancy period after transmission of the at least one data message, wherein the at least one channel state report comprises channel state information for the at least two channels, and - selecting a channel of the at least two channels for data transmission between the first multi-link device and a multi-link device for a second channel occupancy period, wherein the selection is based at least in part on the at least one channel state report.

2. The method of claim 1, wherein the measurement request is transmitted prior to the occupying the first channel for data transmission.

3. The method of claim 1, wherein the at least one channel state report is received from a third multi-link device.

4. The method of claim 1, wherein the measurement request, the at least one channel state report, and transmission of the at least one data message use a same radio technology.

5. The method of claim 1, wherein transmission of the measurement request and reception of the at least one channel state report are performed via a first radio technology, and transmission of the at least one data message is performed via a second radio technology.

6. The method of claim 1, wherein the channel is further selected based on measurements performed by the first multi-link device.

7. The method of claim 1, wherein the second multi-link device and the at least one multi-link device are associated with the first multi-link device.

8. The method of claim 1, wherein the measurement request is included in system information within a physical downlink control channel transmission, a dedicated radio resource control signal, or a groupcast message.

9. The method of any one of claims 1-8, wherein the first multi-link device has dedicated time and frequency resources for reception of channel state reports during the first channel occupancy period, and indicates the resources to the subset of multi-link devices.

10. A method of communication for an apparatus, comprising: - receiving a measurement request from a first multi-link device to perform channel measurements on at least two channels during a first channel occupancy period reserved for communication between the first multi-link device and a second multi-link device, - performing channel measurements during the first channel occupancy period in response to the measurement request, and - transmitting at least one channel state report to the first multi-link device during the first channel occupancy period, wherein the at least one channel state report comprises channel state information for the at least two channels. - transmitting, to the first multi-link device, a channel state report comprising channel state information based on the channel measurements during the first channel occupancy period, wherein the channel state report is used to select a channel among the at least two channels for data transmission between the first multi-link device and a multi-link device in a second channel occupancy period.

11. The method of claim 10, further comprising: - receiving, from the first multi-link device, at least one data message at a channel based on the channel state report during a second channel occupancy period after the first channel occupancy period.

12. The method of claim 10, wherein the measurement request indicates a set of channels in which the channel measurements should be performed.

13. The method of claim 10, wherein the measurement request indicates that a multi-link medium state report for hidden node prevention should be enabled for the multi-link device.

14. The method of claim 10, wherein the multi-link devices belong to a same wireless access network.

15. The method of claim 14, wherein the wireless access network is a New Radio unlicensed based network or an 802.11 based wireless local area network.

16. The method of claim 10, wherein the first multi-link device is a next generation nodeB and / or an access point.

17. The method of any one of claims 10-16, wherein the first multi-link device comprises a non-access point station and / or a user equipment.

18. A communication method for an apparatus, comprising: - receiving, from a first multi-link device, a measurement request to perform channel measurements on at least two channels during a first channel occupancy period, - receiving, from the first multi-link device, at least one data message during the first channel occupancy period, - in response to the measurement request, performing channel measurements during the first channel occupancy period, and - transmitting, to the first multi-link device, a channel state report comprising channel state information based on the channel measurements during the first channel occupancy period, wherein the channel state report is used to select a channel among the at least two channels for data transmission between the first multi-link device and a multi-link device in a second channel occupancy period.

19. The method of claim 18, further comprising: - receiving, from the first multi-link device, at least one data message at a channel based on the channel state report during a second channel occupancy period after the first channel occupancy period.

20. The method of claim 18, wherein the measurement request indicates a set of channels in which the channel measurements should be performed.

21. The method of claim 18, wherein the measurement request indicates that a multi-link medium state report for hidden node prevention should be enabled for the multi-link device.

22. The method of claim 18, wherein the multi-link devices belong to a same wireless access network.

23. The method of claim 22, wherein the wireless access network is a New Radio unlicensed based network or an 802.11 based wireless local area network.

24. The method of claim 18, wherein the first multi-link device is a next generation nodeB and / or an access point.

25. The method of any of claims 18-24, wherein the first multi-link device comprises a non-access point station and / or a user equipment.

26. A communication apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: occupying, for a first multi-link device, a first channel for data transmission between the first multi-link device and a second multi-link device for a first channel occupancy period, transmitting a measurement request to a subset of multi-link devices to perform channel measurements of at least two channels during the first channel occupancy period, transmitting at least one data message to the second multi-link device during the first channel occupancy period, receiving at least one channel status report from at least one of the subset of multi-link devices during the first channel occupancy period after transmission of the at least one data message, wherein the at least one channel status report comprises channel status information of the at least two channels, and selecting a channel of the at least two channels for data transmission between the first multi-link device and a multi-link device for a second channel occupancy period, wherein the selection is based at least in part on the at least one channel status report.

27. The apparatus of claim 26, wherein the measurement request is transmitted prior to the occupying the first channel for data transmission.

28. The apparatus of claim 26, wherein the at least one channel status report is received from a third multi-link device.

29. The apparatus of claim 26, wherein the measurement request, the at least one channel status report, and the transmission of the at least one data message use a same radio technology.

30. The apparatus of claim 26, wherein the transmission of the measurement request and the reception of the at least one channel status report are performed via a first radio technology, and the transmission of the at least one data message is performed via a second radio technology.

31. The apparatus of claim 26, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further select the channel based on measurements performed by the first multi-link device.

32. The apparatus of claim 26, wherein the second multi-link device and the at least one multi-link device are associated with the first multi-link device.

33. The apparatus of claim 26, wherein the measurement request is included in system information within a physical downlink control channel transmission, a dedicated radio resource control signal, or a groupcast message. ​ ​ ​ ​ ​ 34. The apparatus of any one of claims 26-33, wherein the at least one memory and the computer program code are configured, with the at least one processor, to further cause the apparatus to dedicate time and frequency resources to reception of channel state reports during the first channel occupancy period and to indicate the resources to the subset of the multi-link devices.

35. A communication apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: - receiving a measurement request from a first multi-link device to perform channel measurements on at least two channels during a first channel occupancy period reserved for communication between the first multi-link device and a second multi-link device, - performing channel measurements during the first channel occupancy period in response to the measurement request, and - the channel state report is for selecting a channel among the at least two channels for data transmission between the first multi-link device and a multi-link device within a second channel occupancy period.

36. The apparatus of claim 35, wherein the at least one memory and the computer program code are configured, with the at least one processor, to further cause the apparatus to receive at least one data message from the first multi-link device at a channel based on the channel state report during a second channel occupancy period after the first channel occupancy period.

37. The apparatus of claim 35, wherein the measurement request indicates a set of channels in which the channel measurements should be performed. - transmitting, during the first channel occupancy period, a channel state report comprising channel state information based on the channel measurements to the first multi-link device, wherein, 38. The apparatus of claim 35, wherein the measurement request indicates that multi-link devices for multi-link medium state reporting for hidden node prevention should be enabled.

39. The apparatus of claim 35, wherein the multi-link devices belong to a same wireless access network.

40. The apparatus of claim 39, wherein the wireless access network is a New Radio unlicensed based network or a wireless local area network based on 802.

11.

41. The apparatus of claim 35, wherein the first multi-link device is a next generation nodeB and / or an access point.

42. The apparatus of claim 35, wherein the first multi-link device comprises a non- access point station and / or a user equipment.

43. The apparatus of any one of claims 35-42, wherein the apparatus comprises at least one of a New Radio unlicensed transceiver and a wireless local area network transceiver.

44. A communication apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: - receiving a measurement request from a first multi-link device to perform channel measurements on at least two channels during a first channel occupancy period, - performing channel measurements during the first channel occupancy period in response to the measurement request, and - the channel state report is for selecting a channel among the at least two channels for data transmission between the first multi-link device and a multi-link device within a second channel occupancy period. ​ ​ ​ ​ - receiving at least one data message from the first multi-link device during the first channel occupancy period, - in response to the measurement request, performing channel measurements during the first channel occupancy period, and - transmitting, during the first channel occupancy period, and after receiving the at least one data message, a channel state report comprising channel state information based on the channel measurements to the first multi-link device, wherein, the channel status report is used to select a channel among the at least two channels for data transmission between the first multi-link device and a multi-link device in a second channel occupancy period.

45. The apparatus according to claim 44, wherein the at least one memory and the computer program code are configured, with the at least one processor, to further cause the apparatus to receive at least one data message from the first multi-link device at a channel based on the channel status report during a second channel occupancy period following the first channel occupancy period.

46. The apparatus according to claim 44, wherein the measurement request indicates a set of channels in which the channel measurements should be performed.

47. The apparatus according to claim 44, wherein the measurement request indicates that multi-link devices for multi-link medium status reporting for hidden node prevention should be enabled.

48. The apparatus according to claim 44, wherein the multi-link devices belong to a same wireless access network.

49. The apparatus according to claim 48, wherein the wireless access network is a New Radio unlicensed based network or an 802.11 based wireless local area network.

50. The apparatus according to claim 44, wherein the first multi-link device is a next generation nodeB and / or an access point.

51. The apparatus according to claim 44, wherein the first multi-link device comprises a non-access point station and / or a user equipment.

52. The apparatus according to any one of claims 44-51, wherein the apparatus comprises at least one of a New Radio unlicensed transceiver and a wireless local area network transceiver.

53. A non-transitory computer readable medium comprising code for causing, when executed in a data processing apparatus, the method according to at least one of claims 1 to 25 to be performed.

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