WO2022078587A1

WO2022078587A1 - Channel access mechanism selection for wireless communications

Info

Publication number: WO2022078587A1
Application number: PCT/EP2020/078875
Authority: WO
Inventors: Kari Juhani Hooli; Esa Tiirola; Sami-Jukka Hakola
Original assignee: Nokia Technologies Oy
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2022-04-21

Abstract

According to an example aspect of the present invention, there is provided a method, comprising: determining a transmission beamwidth and a transmission power for a transmission, determining a threshold based at least partly on the transmission beamwidth, selecting a first channel access mechanism for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold, and selecting a second channel access mechanism for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold.

Description

CHANNEL ACCESS MECHANISM SELECTION FOR WIRELESS COMMUNICATIONS

FIELD

[0001] Various example embodiments relate to arranging channel access for wireless communications, particularly in unlicensed spectrum.

BACKGROUND

[0002] Wireless medium channel utilization may be based on sharing many frequencies in many wireless networks, such as wireless local area networks. In case of shared channels, users tune on the same channel and try to transmit data. To avoid collisions, several access techniques exist, such as the carrier sense multiple access (CSMA).

[0003] In unlicensed access different networks may share an unlicensed channel. The unlicensed channel may be shared by networks of different radio access technologies (RATs). Operation in unlicensed spectrum is regulated by certain channel access rules that target at fair spectrum use among different RATs on the same shared unlicensed spectrum. Various listen-before-talk (LBT) methods have been developed for arranging channel access and coexistence in wireless networks. Current regulations for 60 GHz unlicensed frequency bands require use of a spectrum sharing or co-channel coexistence mechanism, but do not require any specific type of a mechanism. In some regions, separate regulatory spectrum sharing requirements are defined for different use cases or deployments, e.g. for fixed outdoor equipment or point-to-point communications or for indoor-only use.

[0004] Spatial reuse enables to improve network capacity, and algorithms have been studied and proposed for enabling spatial reuse. Directional antennas may be applied for mitigating co-channel interference by using narrow RF radiation patterns, i.e. narrow beams, for transmissions. In beamforming, phases of the antennas are aligned such that they add up constructively, to provide gain of the signal in a desired direction. In null-steering the phases are aligned to decrease interference caused to devices in other directions.

[0005] With the increasing number of wireless devices and networks, there are more overlapping networks, and transmissions causing interference to neighbouring networks. There is a demand to further develop and improve technologies facilitating channel access for beam based access in unlicensed spectrum.

SUMMARY

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

[0007] According to a first aspect of the present invention, there is provided a method, comprising: determining a transmission beamwidth and a transmission power for a transmission, determining a threshold based at least partly on the transmission beamwidth, selecting a first channel access mechanism for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold, and selecting a second channel access mechanism for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold.

[0008] According to a second aspect, there is provided an apparatus, comprising: means for determining a transmission beamwidth and a transmission power for a transmission, means for determining a threshold based at least partly on the transmission beamwidth, means for selecting a first channel access mechanism for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold, and means for selecting a second channel access mechanism for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold. The means may comprise at least one processor, and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the performance of the apparatus.

[0009] 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 being configured to, with the at least one processor, cause the apparatus at least to carry out the method, or an embodiment thereof.

[0010] According to still further aspects, there is provided a computer program (product), a computer-readable medium, or a non-transitory computer-readable medium, comprising code configured, when executed in a data processing apparatus, to carry out the method, or an embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGURE 1 illustrates a wireless communication system in accordance with at least some embodiments;

[0012] FIGURE 2 illustrates a communications example;

[0013] FIGURES 3 to 5 illustrate methods in accordance with at least some embodiments;

[0014] FIGURE 6 illustrates an example communications timing diagram;

[0015] FIGURE 7 illustrates examples of UE transmissions;

[0016] FIGURE 8 illustrates a WLAN transmission example; and

[0017] FIGURE 9 illustrates an example apparatus capable of supporting at least some embodiments.

EMBODIMENTS

[0018] Fig. 1 illustrates a simplified example in accordance with at least some embodiments. A first communications device, 10, such as a user equipment (UE) in the present example communicates wirelessly with a second communication device 20. The second device may be a wireless radio or access network node, hereafter referred to as AN, 20, such as a NodeB, an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a distributed unit of 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 may refer to any one of NodeB, eNB, gNB, or other base station type.

[0019] The UE 10 may be attached, connected or associated to a cell and/or network of the AN 20 for wireless communications. The air interface between UE and AN may be configured in accordance with a RAT, which both the UE 10 and AN 20 are configured to support. Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which is also known as fifth generation, 5G, and MulteFire. On the other hand, examples of non-cellular RATs include wireless local area network (WLAN) based RATs. Principles of the present disclosure are not limited to a specific RAT though. For example, in the context of NR, AN 20 may be a gNB while in the context of WLAN, AN 20 may be an access point (or non-access point) station (STA).

[0020] The AN 20 may be connected, directly or via at least one intermediate node, with a core network (not shown), such as a Next Generation core network, Evolved Packet Core (EPC), or other network management element. The core network may comprise a set of network functions. A network function may refer to an operational and/or physical entity. The network function may be a specific network node or element, or a specific function or set of functions carried out by one or more entities, such as virtual network elements. For example, a Third Generation Partnership Project (3GPP) 5G core network comprises Access and Mobility Management Function (AMF) which may be configured to terminate RAN control plane (N2) interface and perform registration management, connection management, reachability management, mobility management, access authentication, access authorization, Security Anchor Functionality (SEAF), Security Context Management (SCM), and support for interface for non-3GPP access. The AMF is in charge for managing handovers between gNBs.

[0021] The AN 20 may be connected with at least one other AN as well via an interbase station interface, particularly for supporting mobility of the UE 10 or for backhaul connection, e.g. by 3GPP X2 or similar NG interface. A gNB may 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 called FL One gNB-DU may support one or more cells.

[0022] The UE 10 may be referred to as a user device or wireless terminal in general. Hence, without limiting to 3GPP User Equipment, the term user equipment is herein to be understood broadly to cover various mobile/wireless terminal devices, mobile stations and user devices for user communication and/or machine to machine type communication. The UE 10 may be or be comprised by, for example, a smartphone, a cellular phone, a Machine- to-Machine, M2M, node, machine-type communications node, an Internet of Things, loT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, another kind of suitable user device or mobile station, i.e., a terminal. In some further example embodiments, the UE 10 may be a station of a wireless local area network or a mobile termination (MT) part of an IAB (relay) node.

[0023] The devices 10, 20 may be multi-antenna devices and comprise an antenna panel or array for beam-based transmission and reception. The devices may thus be configured to utilize their spatial degrees of freedom for beamforming their transmitted signals and/or placing nulls towards coexisting devices. In general, beamforming uses multiple antennas to control the direction of a wave-front by appropriately weighting the magnitude and phase of individual antenna signals in an array of multiple antennas. In beambased communication, a directional signal may be transmitted in desired spatial direction by a beam.

[0024] Beamwidth is generally indicative of spatial width of a beam. Beamwidth may be represented by angle of a sector extended or covered by the beam. Beams may span over the entire cell coverage area and the UE 10 may be switched from one beam to another e.g. due to mobility of the UE (referred also to as beam level mobility). A beam and the beamwidth may be selected or configured for transmission or reception by a transmitting/receiving device itself or by co-operation or control with another device (e.g. the gNB), depending on the system and/or use of the beam. For example, the UE 10 may communicate with the AN 20 using beam 12 and the AN 20 may communicate with the UE using beam 22 the beam.

[0025] LBT is a mechanism that allows systems to share an unlicensed band while maintaining the performance of each individual system and device. LBT comprises channel sensing for determining whether a channel is occupied, that is, used by another device or vacant. The channel sensing may comprise measurement or measurements of energy on the channel and comparison of the measured energy against a threshold, for example.

[0026] In beam-based systems, such as IEEE 802.11 and/or 3GPP 5G NR. beam-based networks coexisting on an unlicensed band, relying on omnidirectional channel sensing may easily lead to overprotective behavior, impairing spatial reuse. Improved channel sensing may be achieved applying directional channel sensing. The device 10, 20 may be configured to perform channel sensing from the intended transmit direction, i.e. using a beam it intends to use for scheduled or planned transmission. [0027] With reference to the example of Fig. 2, an initiating device, such as the AN 20, reserves the wireless medium after a successful LBT (LBT1) for a transmission burst or a sequence of transmission bursts. The wireless medium may comprise certain frequency domain allocation, such as a frequency domain defined for 5G NR operation and/or for WLAN operation. The wireless medium may comprise a set of channels for wireless communications, such as one or more channels defined for 5G NR communication and/or channels defined for WLAN communication. The LBT may be performed separately for each of the channels (or it may be possible to carry out LBT jointly for a plurality of channels). For example, 3GPP NR-U at 5GHz operates with 20 MHz channels. At 60 GHz, the 3GPP NR-U channelization is based on 2.16 GHz bandwidth.

[0028] The initiating device may perform LBT method (LBT1) using the intended transmit beam as a receive beam. Receive beam here refers to beam pattern used by the device in receiving mode, here to perform the sensing by the LBT method. This receive beam pattern used for the sensing may then be used as transmit beam (pattern) in the transmitting mode of the device. Upon successful beam based LBT1, i.e. upon during LBT1 detecting the wireless medium to be unoccupied, the device actually reserves the wireless medium “within” the transmit beam for the subsequent downlink (DL) transmission.

[0029] The example of Fig. 2 may thus illustrate a shared channel occupancy time (COT), whereby the COT may be shared by the AN 20 and one or more served node(s), such as the UE 10. Channel access conditions or requirements may be relaxed for UE transmitting within such shared COT, such as a COT acquired and initiated by a gNB, as compared to a case where the transmission does not relate to such (shared) COT acquired by the AN 20. For example, the UE may need to perform a single clear channel assessment (CCA) check when accessing channel within a gNB initiated shared COT, and more comprehensive or “full” LBT with a contention window comprising multiple CCA checks when accessing channel outside a shared COT.

[0030] In the shared COT it is assumed that the uplink (UL) portion can start after the DL portion. A responding device, such as the UE 10, may thus, after a short DL to UL switching gap 200, perform an LBT method (LBT2) to determine if the wireless medium is occupied. The responding device may then initiate UL transmission upon determining that the wireless medium is not occupied. Although not shown in Fig. 2, there can be multiple DL and UL portions in a COT. It is also to be noted that there may be various UL (or DL) transmission scenarios, which may involve use of different (types of) channels or signals or durations.

[0031] User devices and base stations, such as 3GPP UEs and gNBs, may have very different antenna configurations, e.g. due to different form factors, power consumption requirements, and regulations. gNB’s and UE’s antenna arrays are typically having very different size in terms of antenna elements, and thus also the achievable beamwidths are different. Transmission reception point (TRP) refers generally to an antenna array available to the network located at a specific geographical location. An NR cell may have one or multiple TRPs. One example antenna array in gNB is a 16x16 -element array while for UE side the array may be 4x2 -element array. If antenna elements are spaced in X/2 from each other, where X equals wavelength, then 3 dB beamwidth can be approximated by 102 degrees / number of antenna elements per dimension (horizontal and vertical). For example, 102 degrees/16 antenna elements -> ~ 6.4 degrees. Thus, achievable beamwidths may be as illustrated in Table 1 :

Table 1: Example of achievable 3dB beamwidths at gNB and UE

[0032] As a consequence, the spatial domain “affected spatial area” may be very different. This is further illustrated in Fig. 1, wherein reference 12 illustrates beam and spatial domain “affected area” of the UE 10 and 22 the beam and spatial domain “affected area” of the AN 20 (in one dimension, e.g. in azimuth).

[0033] To initiate channel occupancy, two or even more channel access mechanisms may be available for a transmitting (initiating or responding) device, such as one or more of omni-directional LBT, directional LBT, receiver-assisted LBT, and direct channel access (without LBT), e.g. in presence of automatic transmit power control (ATPC), dynamic frequency selection (DFS), long term sensing, or other interference mitigation mechanisms. [0034] There are now provided improvements for channel access facilitating spatial reuse, in which advantage of multiple available channel access methods can be better utilized, by a dynamic channel access method selection and switching between transmissions. Such dynamic channel access method selection is based on transmission power and beamwidth for a transmission.

[0035] Fig. 3 illustrates a method for arranging channel access, particularly for selecting a method for directional channel access. The term channel access method or mechanism (CAM) is applied below, and it is to be appreciated that the selection of CAM may refer to or comprise selection of (un-directional or directional) channel occupancy detection method, which may also be referred to as a channel sensing type or method. The method may be performed in or caused by a wireless communications apparatus/device or a controller thereof, such as the UE 10, which may be communicating with a second device, such as the AN 20.

[0036] The method comprises determining 300 a transmission beamwidth and a transmission power for a transmission. Block 300 may be entered to prepare for an intended transmission, in response to obtaining an uplink resource allocation grant, for example.

[0037] Block 320 comprises determining a threshold based at least partly on the transmission beamwidth. The transmission power is compared to the threshold. A first channel access mechanism (CAM), such as a CAM with LBT, is selected 330 for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold. A second CAM, such as a CAM without channel sensing or measurement prior to transmission, is selected 340 for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold.

[0038] The determining 300, 310 may refer to generating or computing a value for the respective parameter, such as the threshold, or receiving a (preconfigured) value from a memory or another entity, unit, or device.

[0039] The present features facilitate improved and dynamic channel access and occupancy method selection, since the threshold for transmission power based CAM selection is dependent on the transmission beamwidth. Both transmission power and transmission beamwidth reflect amount of interference or interfered area due to the transmission: the smaller the interference created, or interfered area impacted, the lighter channel access mechanisms can be used (and vice versa). When the intended beamwidth is wider / narrower than a reference value, the threshold (for transmission power) may be reduced / increased, respectively.

[0040] A communications device, such as a user device/the UE 10, applying the method of Fig. 3 may after block 330/340 use the selected CAM to access a channel, e.g. with or without LBT, and subsequently perform the transmission using the determined transmission beamwidth and power.

[0041] The communications device may thus autonomously select between available CAMs per transmission based on intended transmission parameters and relative to amount of interference the transmission may cause. Associated CAM selection related control signaling and functionality at network side, e.g. the gNB, may be at least reduced. The present features allow for dynamic switching to less-resource consuming CAM, such as a CAM without LBT, on sufficiently low interfered areas/transmission events causing sufficiently low interference. This allows for more efficient UL operation and use of channel. Further, the present features may enable a mechanism to maintain UL connection with UE heavily exposed to interference (while gNB is observing frequently vacant channel).

[0042] The device may apply the method of Fig. 3 when operating as a responding device, e.g. by 3GPP UE within a gNB initiated COT (in the example of Fig. 2 select the LBT2), and/or when operating as an initiating device, i.e. proactively initiating its own COT, e.g. for configured grant-physical uplink shared channel (CG-PUSCH).

[0043] It will be appreciated that there may be various further features and blocks in connection with the method of Fig. 3. Below some example embodiments are illustrated, with references to UE or UE 10, without however limiting application of the features to such referred devices or systems.

[0044] Block 300 may comprise generating/selecting, or receiving (e.g. from another controlling entity) an already generated/selected value for the transmission beamwidth and/or transmission power. This may include control signaling from the AN 20, such as gNB. [0045] The required/intended transmission power may be determined in or for block 300 semi-statically and/or dynamically per allocated UL transmission. Already existing power control mechanisms may be applied for determining the transmission power, such as the 3GPP NR power control mechanism for UL Tx power, comprising e.g. open loop setting and the closed loop adjustment. The transmission power may be determined based on rules for maximum transmission power, maximum power spectral density, and maximum power reduction allowed for different scenarios. The transmission power may be based on the number of physical resource blocks (PRBs) transmitted. The transmission power may be based on DL path loss measured at UE for the beam. At least some of power control parameter values may be configured separately for each beam.

[0046] As an example of semi-static determination, in CG-PUSCH (or physical random access channel (PRACH)) the power control parameter values are semi-static, and there is no dynamic closed loop adjustment. However, the path loss measured at UE obviously changes dynamically, affecting also the transmission power.

[0047] The AP 20 may indicate a beam to be used for the transmission, e.g. based on sounding reference signal (SRS) measurements from candidate beams. However, the beamwidth may be determined by the UE 10 for the transmission. The AP, such as a gNB, may or may not be aware of beamwidth associated to the beam that gNB indicates for the transmission.

[0048] The AN 20 may support implementation where certain antenna panel (e.g. 16x16 antenna elements) is equipped with multiple Tx/Rx chains (e.g. 4 Tx/Rx chains per panel). Each Tx/Rx chain is associated to a separate sub-panel (e.g. 8x8 antenna elements). In this scenario, beamwidth of single sub-panel can be seen as an example of “a wide beam”. The AN can create a narrow beam by steering the beams of multiple sub-panels towards the same direction. This allows to create “a narrow beam”. For example, steering the beams of multiple sub-panels towards the same direction provides additional beamforming or beam gain (e.g. 6 dB with four sub-panels). Generally, in order to create a wide beam, the AN may use only a subset of antenna elements (or even a single one) of the antenna panel. Similar operations may be deployed by the UE 10.

[0049] The determination 310 of the threshold may comprise a plurality of reference values, on the basis of which the threshold is determined. The transmission beamwidth may be compared to the reference value(s). For example, one or more beamwidth reference threshold values or ranges may be used, and the threshold is selected or determined on the basis of the detecting the transmission beamwidth exceeds the threshold value or falls within a given range.

[0050] With reference to the method of Fig. 4, the block of determining 310 the threshold may comprise: comparing 400, 410 the transmission beamwidth to a reference value for setting a threshold for transmission power based CAM selection. A first threshold value is selected 420 in response to detecting that the transmission beamwidth is higher than the reference value. A second threshold value is selected 430 in response to detecting that the transmission beamwidth is lower than the reference value. When the first threshold value is lower than the second threshold value, first CAM is thus more likely selected for transmission with wider beamwidth. It will be appreciated that Fig.4 represents only a simple example and various number (more than two) of reference values and associated thresholds may be applied.

[0051] The beamdwidth for the transmission may be determined in block 300 in terms of angle (of a sector for the beam). For example, the beamwidth may relate to half power beamwidth, that is the angle between half power points of the beam relative to the peak power of the beam. An angle value may thus be determined in block 300 as the transmission beamwidth, and the reference value(s) may be angle value(s).

[0052] There is an inverse relation between beamwidth and beam gain. In an example embodiment, the transmission beamwidth is determined 310 based on beam(forming) gain of a transmission beam. Instead of degrees, beamwidth can be defined by means of beam gain, e.g. by means of decibels with respect to an isotropic radiator, in dBi.

[0053] The threshold may be determined 310 based on the beam gain for the transmission, and the comparison illustrated in Fig. 4 may be performed based on the beam gain. The threshold selection may thus be reversed. For example, in Fig 4, if the beam gain exceeds the reference value, a second (higher) threshold is selected, and if not, first (lower) threshold value is selected. Reference value(s) may thus be (reference) beam gain value(s).

[0054] As regards determining 300 the beamwidth or beam gain, in an example embodiment beamwidths or beam gains are predetermined for a set of beam configurations (used sub-panel configuration, antenna weights). A beamwidth or beam gain value associated to a predetermined beam configuration closest to used beam configuration may be selected in block 300. The values may be predetermined in relation to an angle between the beam and boresight of the antenna panel.

[0055] One or more reference values, to which the transmission beamwidth is compared in block 310, may be selected on the basis of channel or signal selected or controlled for the transmission. It will be appreciated that there is a wide variety of implementation options for determining or computing the threshold value. In some cases, a specification (or even regulation) may define inputs, such as reference or threshold value(s) for different beamwidths or beam gain values for block 310. In an example, a standard specification or regulation defines a single reference value for certain beamwidth (e.g. omnidirectional beam). Further reference or threshold values for different beamwidths may thus be derived in a predefined way from the given reference value. For example, the reference value may be scaled according to the beam gain.

[0056] The threshold may thus be configured or biased separately for different channels and signals. For example, a specific threshold may be used for control channel or for specific signals, such as a scheduling request orPRACH. The threshold for these example signals may be lower than for other signals.

[0057] At least one of the threshold, the reference value(s) for the threshold determination 310, the first channel access mechanism, and the second channel access mechanism may be based at least partly on configuration information received from an access node. For example, the UE 10 may receive a configuration from the AN 20 providing at least some of the required parameters for the CAM selection. Some examples include an indication of a set of CAMs available to select from, beamwidth reference values and associated/mapped (power/PSD) threshold values, (power/PSD) threshold value(s) or range(s) and associated CAM(s), etc.

[0058] The first CAM may comprise an LBT procedure, such as one of the LBT types already mentioned. For example, such LBT procedure(s), may comprise at least one of a) LBT without random back-off, b) LBT with random back-off with contention window of fixed size, and c) LBT with random back-off with contention window of variable size.

[0059] The second CAM may comprise a procedure other than an LBT procedure. The second CAM may be without a channel sensing or measurement prior to the transmission. An example of such non-LBT procedures, in case of shared COT, comprises immediate transmission after a (short) switching gap from reception to transmission. In case of non-shared COT, such as CG-PUSCH, PRACH, or scheduling request (SR), there may be no such preceding DL, and the second CAM may comprise immediate transmission without channel sensing.

[0060] The first and/or second CAM may be selected from among a set of at least two methods, such as the LBT and/or non-LBT methods illustrated above.

[0061] The selecting of the first or second CAM may be further based on comparing a (transmit) power spectral density (PSD) for the transmission to a second value indicated by the threshold or a further threshold for power spectral density. The use of both transmission power and PSD provides further characterization on the upcoming interference (and distribution thereof), and enables to select the CAM based on total interference power and local interference effect. As an example, values of 10 dBm and 13 dBm / MHz from CEPT frequency band nl may be used for thresholds for the transmission power and/or PSD thresholds.

[0062] The device performing the method of Fig. 3, such as the UE 10, may receive an indication for CAM selection from a network node, such as the gNB. The CAM selection of Fig. 3 may be entered in response to the indication, and/or the CAM may be selected on the basis of the indication. For example, if the transmission power and/or PSD, is above a preconfigured or the dynamically defined (310) threshold, the UE 10 may select to perform LBT according to the indication received from gNB.

[0063] Reference is made to Fig. 5 illustrating an example method performed by a UE, such as the UE 10. In this example, the UE receives 500 an UL resource allocation grant for transmission indicative of conditional LBT, i.e. the UE may itself determine the need for performing LBT. The UE may determine 510 the need for LBT based on at least one of transmission power and transmission beamwidth. This may comprise at least some of the above features, such as performing the method of Fig. 3. In case LBT is needed, selected LBT is performed 520. If outcome 530 of the LBT procedure is not positive, i.e. the medium is occupied, the transmission may be dropped 540 (and retry performed later, if applicable). If the LBT is positive, UL signal transmission 550 may be performed according to the received UL resource allocation grant. The transmission block 550 may be directly entered in case LBT is not needed. For example, LBT is not needed if the transmission power is below the set threshold set dynamically based on the beamwidth intended for the UL transmission.

[0064] In an example embodiment, the UE 10 is configured to start the transmission (e.g. in block 550) at a given transmission time instance determined for the transmission, regardless on the CAM selection, provided that channel access is acquired with the selected CAM. This may be possible for at least some of the CAMs and the UE may thus be configured to start the transmission at the transmission time instance indicated by the AN 20 regardless of whether the UE actually performed the LBT. Hence, the transmission time may be set to enable LBT procedure to be performed, and the AN does not have to be aware of the selected CAM.

[0065] Fig. 6 illustrates a timing example for 3GPP based transmission, in which the considered transmission is PUSCH. The gNB generally reserves the LBT gap for UE based on the indicated LBT type. The indication may be done via physical downlink control channel (PDCCH) message from the gNB to the UE, preceding physical downlink shared channel (PDSCH) transmissions from the gNB to the UE. However, when applying embodiments illustrated above, there may be cases where gNB may not know whether UE need to perform LBT or not (gNB may not be aware of the exact UE Tx power). The gNB may reserve the LBT gap also for such cases for the UE. The allowed starting time for PUSCH transmission from the UE to the gNB may thus be the same regardless of the UE CAM determination.

[0066] Fig. 7 illustrates three examples, a to c, of UE transmit beams and interfered areas. In a), the UE 10 uses a wide beam. High transmission power is needed for sufficient effective isotropic radiated power (EIRP) to reach the AP 20, in the present example gNB, with sufficient signal to interference and noise ratio (SINR) for scheduled modulation and coding schemes (MCS). Even higher transmission power is needed when resource allocation comprises large allocation of PRBs and/or MCS is set high. The interfered area is significant and UE should select CAM with LBT.

[0067] In b), the UE 10 uses a narrow beam. Lower transmission power (than in case a)) is needed for sufficient EIRP to reach gNB with sufficient SINR. The interfered area may be sufficiently small, so as the UE may select CAM without LBT. [0068] In c), the UE 10 uses a wide beam. However, the UE is closer to gNB than in a) (or path loss is otherwise smaller due to better propagation condition, e.g. due to line-of- sight condition). Lower transmission power is needed than in case a). The transmission power may be lowered also due to resource allocation consisting of only few PRBs and/or MCS is set low. The interfered area may be sufficiently small, so as the UE may select CAM without LBT.

[0069] Two or more beamdwidth classes may be pre-configured in the UE or configured by the AN 20 and a beamwidth indication is applied for the threshold determination 310 or CAM selection. For example, beamwidth classes similar to as illustrated below could be used (only one dimension being considered for simplicity):

- Class A: narrow beamwidth, e.g. below 13° per dimension (azimuth and elevation)

- Class B: medium beamwidth, e.g. between 13° and 52°

- Class C: wide beamwidth, e.g. above 52°

[0070] In some embodiments, a signal or energy detection threshold is adapted for determining whether the wireless medium is occupied on the basis of the selected method. Thus, different CAMs (e.g. LBT types illustrated above) may be associated with different detection thresholds, and the detection threshold may vary on the basis to the transmission power/PSD and/or beamwidth determined for the transmission. For example, the detection threshold may be lower for smaller beamwidth than for larger beamwidth.

[0071] In some embodiments, as already illustrated, presently disclosed features are applied for accessing unlicensed wireless medium by 3GPP 5G system. Current NR Release 16 defines operation for frequencies up to 52.6 GHz. Unlicensed band access beyond 52.6 GHz, around 60 GHz is also being studied. At least some of 3GPP 5G channel access schemes for LBT types or categories may be applied as CAMs, as such or as modified. Such access schemes may include one or more of category 1 immediate transmission and two or more further LBT categories, which may be defined in channel access schemes of 3 GPP TR 38.889.

[0072] It is to be noted that the device applying the method of Fig. 3 may perform two (or even more) LBT methods or events in consecutive manner. For example, one LBT may be with omni-pattern or a wide beam and another LBT may be beam-based. The methods may be of different LBT/CA types. The methods may have different energy detection thresholds.

[0073] In some embodiments, the UE 10 comprises a wireless local area network (WLAN) transceiver, which may be configured to operate as a station (STA) in an IEEE 802.11-based WLAN. Thus, the STA may be associated with a basic service set (BSS) which is a basic building block of IEEE 802.11-based WLANs. The most common BSS type is an infrastructure BSS that includes a single access point (AP) together with all STAs associated with the AP. The device 10, 20 may be configured to operate as an AP or a non-AP STA. The AP may be a fixed AP or a mobile AP.

[0074] Clear channel assessment (CCA) is applied for determining if WLAN medium is idle or not. The CCA includes carrier sense and energy detection functions, wherein carrier sense refers generally to ability of the receiver to detect and decode WLAN signal preamble. Network allocation vector (NAV) is a virtual carrier-sensing mechanism used in wireless network protocols, such as IEEE 802.11 based systems, and is a logical abstraction that limits the need for physical carrier-sensing at the air interface to save power. The MAC layer frame headers contain a duration field that specifies the transmission time required for the communication. In addition, the PLCP header also carries information relevant for determining the duration of the frame being transmitted. Wireless devices listening to the wireless medium read this information and back off accordingly.

[0075] Fig. 8 illustrates a simplified example of an embodiment for a WLAN based system. The AP may, upon detecting based on channel or carrier sensing 801 using a CAM which may be selected by applying the method of Fig. 3, that the wireless medium is not occupied, send 802.11 frame 802, such as a request-to-send (RTS) frame or a data frame. The STA may be configured to perform the method of Fig. 3 and select, based on determined transmission power and the beamwidth based threshold, the CAM to be used for channel sensing 803. Upon detecting the wireless medium to be unoccupied on the basis of the selected CAM, the STA may send an 802.11 frame 804.

[0076] There may be coexisting wireless communication networks, which may be of different RATs. For example, there may be a wireless local area network (WLAN) and a cellular network, such as a 5G NR Unlicensed (NR-U) network, coexisting in the same unlicensed band. Various scenarios of coexistence are facilitated, for example, wherein a gNB is neighbour to a Wi-Fi AP. The methods enable benefits also for relay-type network nodes. For example, 3GPP integrated access backhaul (IAB) relays, and Wi-Fi relays/bridges may be configured to apply at least some of the above-illustrated embodiments.

[0077] For example, the AN 20 is (or is configured to operate as) a gNB comprising an NR-U transceiver, i.e. a communications unit configured to operate in unlicensed spectrum on the basis of 3GPP NR based access, and a Wi-Fi AP. In a further example embodiment, the devices 10, 20 are configured to support 802.1 lax based WLAN. Examples of millimetre-wave 802.11 based systems, in which at least some of the above illustrated features may be applied, include WiGiG (also known as 60 GHz Wi-Fi) based on IEEE 802.1 lad and/or 802.1 lay standards.

[0078] While some embodiments have been described in the context of 5GNR-U and WLAN / IEEE 802.11 based systems, it should be appreciated that these or other embodiments of the invention may be applicable in connection with other technologies configured to operate on licensed or non-licensed band, such as with wireless devices operating according to other local -connectivity technologies, other existing or future versions of the IEEE 802.11, 6G cellular systems, or other existing or future technologies facilitating spatial reuse. Further, although LBT has been referred in above illustrated embodiments, also other methods for coexistence and channel access may be used. For example, the duty cycle based coexistence method may be applied, wherein allowed duty cycle for the first device and/or the second device may be dependent on the applied beamwidth and/or transmission power.

[0079] An electronic device comprising electronic circuitries may be an apparatus for realizing at least some embodiments of the present invention. The apparatus may be or may be comprised in a computer, a laptop, a tablet computer, a cellular phone, a machine to machine (M2M) device (e.g. an loT sensor device), a base station, an access point or node device or any other apparatus provided with radio communication capability. In another embodiment, the apparatus carrying out the above-described functionalities is comprised in such a device, e.g. the apparatus may comprise a circuitry, such as a chip, a chipset, a microcontroller, or a combination of such circuitries in any one of the above-described devices. [0080] The apparatus may comprise a communication circuitry providing the apparatus with capability of communicating in at least one wireless network. The communication circuitry may employ a radio interface providing the apparatus with radio communication capability. The radio interface may comprise a radio modem RF circuitries providing at least a part of the physical layer(s) of the wireless device. The radio interface may be comprised in the apparatus in the embodiments where the apparatus is the wireless device. In other embodiments where the apparatus is a chipset for the wireless device, the radio interface may be external to the apparatus.

[0081] The radio interface may support transmission and reception according to the principles described above. The RF circuitries may comprise radio frequency converters and components such as an amplifier, filter, and one or more antennas. The radio modem may comprise baseband signal processing circuitries such as (de)modulator and encoder/decoder circuitries. The communication circuitry may carry out at least some of the features described above. In embodiments where the apparatus employs multiple physical layer entities, the radio modem and the RF circuitries may employ a separate transmitter and receiver branch for each of the multiple links supported by the apparatus. The radio modem and the RF circuitries may include a dedicated circuitry for the physical layer and another dedicated circuitry for the physical layer, although the dedicated circuitries may employ partially the same physical components in the transmission and/or reception.

[0082] As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile user device, to perform various functions) and (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 the software may not be present when it is not needed for operation. 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 of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0083] Fig. 9 illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is a device 900, which may comprise a wireless communications device, which may be configured to operate as the UE 10, for example. The device may include one or more controllers configured to carry out operations in accordance with at least some of the embodiments illustrated above, such as some or more of the features illustrated above in connection with Figures 2 to 8. The device may be configured to operate as the apparatus configured to carry out the method of Figure 3 or 4, for example.

[0084] Comprised in the device 900 is a processor 902, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. The processor 902 may comprise more than one processor. The processor may comprise at least one application-specific integrated circuit, ASIC. The processor may comprise at least one field-programmable gate array, FPGA. The processor may be means for performing method steps in the device. The processor may be configured, at least in part by computer instructions, to perform actions.

[0085] The device 900 may comprise memory 904. The memory may comprise random-access memory and/or permanent memory. The memory may comprise at least one RAM chip. The memory may comprise solid-state, magnetic, optical and/or holographic memory, for example. The memory may be at least in part accessible to the processor 902. The memory may be at least in part comprised in the processor 902. The memory 904 may be means for storing information. The memory may 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 in overall is configured to run under the direction of the processor using computer instructions from the memory, the processor and/or its at least one processing core may be considered to be configured to perform said certain actions. The memory may be at least in part comprised in the processor. The memory may be at least in part external to the device 900 but accessible to the device. For example, control parameters affecting operations related to the CAM selection may be stored in one or more portions of the memory and used to control operation of the apparatus. Further, the memory may comprise device-specific cryptographic information, such as secret and public key of the device 900.

[0086] The device 900 may comprise a 1st transceiver 906 of the 1st RAT. The device may comprise a 2nd transceiver 908 of the 2nd RAT. The transceiver 906, 908 may be configured to operate in accordance with a wireless, cellular or non-cellular standard, such as wideband code division multiple access, WCDMA, long term evolution, LTE, 5G, 6G, or other cellular communications systems, and/or a WLAN standard, for example. The device 900 may comprise a near-field communication, NFC, transceiver 910. The NFC transceiver may support at least one NFC technology, such as NFC, Bluetooth, Wibree or similar technologies.

[0087] The device 900 may comprise user interface, UI, 912. The UI may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing the device to vibrate, a speaker and a microphone. A user may be able to operate the device via the UI, for example to configure or control the device.

[0088] The device 900 may comprise or be arranged to accept a user identity module or other type of memory module 914. The user identity module may comprise, for example, a subscriber identity module, SIM, and/or a personal identification IC card installable in the device 900. The user identity module 914 may comprise information identifying a subscription of a user of device 900. The user identity module 914 may comprise cryptographic information usable to verify the identity of a user of device 900 and/or to facilitate encryption and decryption of communication effected via the device 900.

[0089] The processor 902 may be furnished with a transmitter arranged to output information from the processor, via electrical leads internal to the device 900, to other devices comprised in the device. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 904 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise the processor may comprise a receiver arranged to receive information in the processor, via electrical leads internal to the device 900, from other devices comprised in the device 900. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from the transceiver 906, 908 for processing in the processor. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

[0090] The device 900 may comprise further devices not illustrated in Fig. 9. For example, the device may comprise at least one digital camera. Some devices may comprise a back-facing camera and a front-facing camera. The device may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of the device. In some embodiments, the device lacks at least one device described above. For example, some devices may lack the NFC transceiver 910 and/or the user identity module 914.

[0091] The processor 902, the memory 904, the transceiver 906, 908, the NFC transceiver 910, the UI 912 and/or the user identity module 914 may be interconnected by electrical leads internal to the device 900 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to the device, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0092] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0093] 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 invention. 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. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0094] As used herein, a plurality of items, structural elements, compositional elements, and/or functional features may 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 their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof.

[0095] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention 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 invention.

The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", that is, a singular form, throughout this document does not exclude a plurality.

Claims

23

CLAIMS:

1. An apparatus, comprising: means for determining a transmission beamwidth and a transmission power for a transmission, means for determining a threshold based at least partly on the transmission beam width, means for selecting a first channel access mechanism for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold, and means for selecting a second channel access mechanism for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold.

2. The apparatus of claim 1, wherein said determining the threshold comprises: selecting a first threshold value in response to detecting that the transmission beamwidth is higher than a reference value; and selecting a second threshold value in response to detecting that the transmission beamwidth is lower than the reference value.

3. The apparatus of any preceding claim 1 or 2, wherein said determining the threshold comprises plurality of reference values to which the transmission beamwidth is compared.

4. The apparatus of claim 2 or 3, wherein the apparatus is configured to select one or more reference values, to which the transmission beamwidth is compared, on the basis of channel or signal for the transmission.

5. The apparatus of claim 1, wherein said determining the threshold comprises: selecting a first threshold value in response to detecting that a transmission beam gain based on the transmission beamwidth, is lower than a reference value; and selecting a second threshold value in response to detecting that transmission beam gain is higher than the reference value. The apparatus of any preceding claim, wherein at least one of the threshold, the reference value, the first channel access mechanism, and the second channel access mechanism is based at least partly on configuration information received from an access node. The apparatus of any preceding claim, wherein the first channel access mechanism comprises a listen-before-talk procedure. The apparatus of any preceding claim, wherein the second channel access mechanism comprises a procedure without a channel sensing or measurement prior to the transmission. The apparatus of any preceding claims, wherein the selecting the first or second channel access mechanism is further based on comparing power spectral density for the transmission to a second value indicated by the threshold or a further threshold for power spectral density. The apparatus of any preceding claim, wherein the apparatus comprises means for performing the transmission at a given transmission time instance regardless of whether the first channel access method or the second channel access method is selected, provided that channel access is acquired with the selected channel access mechanism. The apparatus of any preceding claim, wherein the apparatus is a user equipment and/or a terminal. The apparatus of any preceding claim, wherein the apparatus comprises at least one of a new radio unlicensed transceiver configured to operate on the wireless medium and a wireless local area network transceiver configured to operate on the wireless medium. A method for an apparatus, comprising: - determining a transmission beamwidth and a transmission power for a transmission,

- determining a threshold based at least partly on the transmission beamwidth, and

- selecting a first channel access mechanism for the transmission at least partly in response to detecting that the transmission power exceeds a value indicated by the threshold, or

- selecting a second channel access mechanism for the transmission at least partly in response to detecting that the transmission power is below the value indicated by the threshold.

14. The method of claim 13, wherein said determining the threshold comprises: selecting a first threshold value in response to detecting that the transmission beamwidth is higher than a reference value; and selecting a second threshold value in response to detecting that the transmission beamwidth is lower than the reference value.

15. The method of claim 13 or 14, wherein said determining the threshold comprises plurality of reference values to which the transmission beamwidth is compared.

16. The method of claim 14 or 15, comprising selecting one or more reference values, to which the transmission beamwidth is compared, on the basis of channel or signal for the transmission.

17. The method of claim 13, wherein said determining the threshold comprises: selecting a first threshold value in response to detecting that a transmission beam gain based on the transmission beamwidth, is lower than a reference value; and selecting a second threshold value in response to detecting that transmission beam gain is higher than the reference value.

18. The method of any preceding claim, wherein at least one of the threshold, the reference value, the first channel access mechanism, and the second channel access mechanism is based at least partly on configuration information received from an access node. 26

19. The method of any preceding claim, wherein the first channel access mechanism comprises a listen-before-talk procedure.

20. The method of any preceding claim, wherein the second channel access mechanism comprises a procedure without a channel sensing or measurement prior to the transmission.

21. The method of any preceding claim, wherein the selecting the first or second channel access mechanism is further based on comparing power spectral density for the transmission to a second value indicated by the threshold or a further threshold for power spectral density.

22. The method of any preceding claim, wherein the transmission is performed at a given transmission time instance regardless of whether the first channel access method or the second channel access method is selected, provided that channel access is acquired with the selected channel access mechanism.

23. The method of any preceding claim, wherein the apparatus is a user equipment and/or a terminal.

24. The method of any preceding claim, wherein the apparatus comprises at least one of a new radio unlicensed transceiver configured to operate on the wireless medium and a wireless local area network transceiver configured to operate on the wireless medium.

25. A computer program comprising code for, when executed in a data processing apparatus, causing a method in accordance with at least one of claims 13 to 24 to be performed.

26. A non-transitory computer-readable medium, comprising code for, when executed in a data processing apparatus, causing a method in accordance with at least one of claims 13 to 24 to be performed.