Directional channel access awareness

Abstract

The radio station performs an omni-directional or directional channel access sensing procedure before transmission and performs a directional channel access sensing procedure in the direction of the new beam before changing the beam direction during the channel occupancy time.

Description

Technical Field

[0001] This application relates to channel access awareness, and more particularly to such awareness performed prior to directed transmission. Background Technology

[0002] Wireless communication systems, such as third-generation (3G) mobile phone standards and technologies, are well-known. These 3G standards and technologies were developed by the Third Generation Partnership Project (3GPP) (RTM). Third-generation wireless communication has been widely developed to support macro-cell mobile phone communication. Communication systems and networks have evolved towards broadband and mobile systems.

[0003] In a cellular wireless communication system, User Equipment (UE) connects to the Radio Access Network (RAN) via a radio link. The RAN comprises a set of base stations that provide radio links to UEs located in cells covered by base stations, and an interface providing overall network control to the Core Network (CN). It should be understood that the RAN and CN each perform their respective functions relevant to the overall network. For convenience, the term "cellular network" will be used to refer to the combined RAN and CN, and should be understood to refer to the corresponding systems used to perform the disclosed functions.

[0004] The 3G Partnership developed the so-called Long Term Evolution (LTE) (RTM) system, namely the Evolved Universal Mobile Telecommunication System Territorial Radio Access Network (E-UTRAN), for mobile access networks, in which one or more macro cells are supported by base stations called eNodeBs or eNBs (evolved NodeBs). More recently, LTE is further evolving towards the so-called 5G or NR (New Radio) system, in which one or more cells are supported by base stations called gNBs. NR is proposed to use the Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

[0005] The NR protocol is designed to provide the option to operate in unlicensed radio bands known as NR-U. When operating in unlicensed radio bands, the gNB and UE must compete with other devices for physical media / resource access. For example, Wi-Fi (RTM), NR-U, and LAA can use the same physical resources.

[0006] Listen-before-talk (LBT) is used as a channel access procedure type for unlicensed operation in 3GPP design, thus requiring radio transmitters to perform Clear Channel Assessment (CCA) checks before transmission. CCA involves at least a certain threshold (ED threshold) of energy detection (ED) for a duration to determine whether the channel is occupied or idle. When the channel is occupied, a random back-off within the contention window is applied to ensure a minimum channel idle time before the transmitter can transmit. This also introduces randomness among competing devices, thus avoiding collisions. To protect Wi-Fi ACK transmissions, a delay period (e.g., 43 microseconds for best-effort traffic) is applied after each busy CCA slot before resuming backoff. After gaining access to the channel, the transmitter is only permitted to transmit for a limited duration called the Maximum Channel Occupancy Time (MCOT). To differentiate channel access priorities based on the type of traffic served (e.g., VoIP, video, best-effort, or background), as described in Section 4.1.2 of TS37.213, four LBT priority categories with different Contention Window Sizes (CWS) and MCOT are defined. Parameter m p Used to calculate delay duration when a busy channel is detected, resulting in longer delay periods for lower priority categories.

[0007] Regulatory bodies have defined a single sensing slot, or CCA slot, as having a duration of 9 microseconds over 6 GHz and a duration of 5 microseconds over 60 GHz of unlicensed spectrum. Furthermore, specific durations for energy detection within the sensing slot have been specified.

[0008] Type 1 downlink channel access procedures are performed by the base station (eNB / gNB), where the duration spanned by the sensing slots that are sensed as idle before downlink transmission is randomized. Furthermore, whenever channel congestion is detected, the base station will back off with a delay duration corresponding to the access priority of the channel being used. Type 1 procedures are essentially used to initiate channel access for most data transmissions.

[0009] Type 2 downlink channel access procedures are performed by the base station (eNB / gNB), where the duration spanned by the sensed time slots sensed as idle prior to downlink transmission is deterministic. These are primarily used for data transmission when the same base station or UE a priori establishes channel access. This type of channel access is also permitted for short-duration control signaling transmissions, such as discovery bursts.

[0010] Similar to downlink type 1 and type 2 channel access, uplink type 1 and type 2 channel access procedures have been defined, in which the UE will perform channel access with random or deterministic durations, respectively.

[0011] Beam-based operation has been proposed for the NR protocol, allowing base stations to transmit up to 64 beams in different directions. Beamforming is particularly attractive when operating at higher transmission frequencies due to higher path loss. For example, there is a significant amount of unlicensed spectrum in the 60 GHz region.

[0012] The following disclosure relates to various improvements to cellular wireless communication systems. Summary of the Invention

[0013] This invention summary provides a simplified overview of a series of concepts, which will be further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0014] The present invention will now be described in detail with reference to the accompanying drawings.

[0015] A channel-aware method is provided, performed by a first radio station in a cellular communication network, the first radio station being capable of beamforming transmission. The method includes the following steps: before transmission, performing a first channel-aware process at the first radio station, wherein a successful first channel-aware process acquires a transmission channel with a channel occupancy time, the first channel-aware process being selected from omnidirectional and directional channel-aware processes; transmitting a first signal from the first radio station to a second radio station using the transmission channel; performing a directional channel-aware process at the first radio station before the channel occupancy time expires, wherein the directional channel-aware process is performed in the direction of a new beam that the first radio station intends to transmit; and after a successful directional channel-aware process, transmitting a second signal from the first radio station to the second radio station using the new beam.

[0016] A channel-aware method is also provided, performed by a first radio station in a cellular communication network, the first radio station being capable of beamforming transmission, wherein the method includes the following steps: performing a first channel-aware process at the first radio station before transmission, wherein a successful first channel-aware process acquires a transmission channel with channel occupancy time, the first channel-aware process being selected from omnidirectional and directional channel-aware processes; transmitting a signal from the first radio station to a second radio station using the transmission channel; performing a directional channel-aware process at the second radio station before the channel occupancy time expires, wherein the directional channel-aware process is performed in the direction of a new beam that the second radio station intends to transmit; and transmitting the signal from the second radio station using the new beam.

[0017] The choice between omnidirectional or directional channel sensing is defined by the system configuration.

[0018] The first channel sensing process is an omnidirectional channel sensing process.

[0019] The first channel sensing process is a directional channel sensing process performed in the direction of the first beam in which the first radio station intends to transmit the first signal; the direction of the first beam is different from the direction of the new beam.

[0020] The first channel sensing process is an omnidirectional process that is performed once or multiple times to attempt to acquire the channel. The method further includes performing a further first channel sensing process if the first channel sensing process fails to acquire the transmission channel, wherein the further first channel sensing process is a directional channel sensing process.

[0021] The first and / or second channel sensing process uses random backoff.

[0022] The first and / or second channel sensing process uses a random duration.

[0023] The first and / or second channel sensing process uses a deterministic duration.

[0024] The first and / or second channel sensing process uses a deterministic duration unless, when the channel access process acquires the transmission channel, the gap between transmissions on the beam to be used exceeds a threshold, in which case a random duration is used.

[0025] The duration depends on the gap between transmissions on the beam, which will be used if the channel access process acquires the channel.

[0026] The first and / or second channel sensing process utilizes an energy detection threshold based on the maximum effective isotropic radiated power in any beam direction of the radio station performing the sensing process.

[0027] Transmissions on the new beam will end no later than the expiration of the channel occupancy time at the start of the first channel sensing process.

[0028] The first and second channel sensing processes are a process of listening before speaking.

[0029] The first radio station transmits information about the first and / or second channel sensing process.

[0030] The information indicates whether the first channel sensing process is omnidirectional or directional.

[0031] The first radio station is a base station.

[0032] The first radio station is a UE.

[0033] A base station and a UE are also provided, which are configured to perform the methods described herein. Attached Figure Description

[0034] Further details, aspects, and embodiments of the invention will be described by way of example only with reference to the accompanying drawings. Components in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. Similar reference numerals have been included in the respective drawings for ease of understanding.

[0035] Figure 1 Displays selected elements of the cellular communication network;

[0036] Figure 2 Displays a base station and UE with directional transmission; and

[0037] Figure 3 Display the base station and the UE shared by the COT. Detailed Implementation

[0038] Those skilled in the art will recognize and understand that the details of the described examples are merely illustrative of some embodiments, and that the teachings set forth herein are applicable to various alternative settings.

[0039] Figure 1 This diagram illustrates three base stations (e.g., eNB or gNB, depending on the specific cellular standard and terminology) forming a cellular network. Typically, each base station is deployed by a cellular network operator to provide geographic coverage for UEs in that area. The base stations form a Radio Area Network (RAN). Each base station provides radio coverage for UEs in its area or cell. The base stations interconnect via an X2 interface and connect to the core network via an S1 interface. It should be understood that only basic details are shown for the purpose of illustrating key characteristics of a cellular network. A PC5 interface is provided between UEs for sidelink (SL) communication. Figure 1 The related interface and component names are for illustrative purposes only; different systems operating on the same principles may use different naming conventions.

[0040] Each base station includes hardware and software to implement RAN functions, including communication with the core network and other base stations, control and data signaling between the core network and UEs, and maintaining wireless communication with the UEs associated with each base station. The core network includes hardware and software to implement network functions, such as overall network management and control, and call and data routing.

[0041] Traditional channel access procedures use omnidirectional sensing to determine whether a channel is occupied. However, as Figure 2 As shown, this can be inefficient for systems using beamforming. Base station 200 intends to transmit to UE 201 in unlicensed spectrum and therefore executes an omnidirectional channel access procedure to detect transmissions within area 202. This procedure will detect transmissions between devices 203 and 204, which may be, for example, Wi-Fi devices. These transmissions will prevent base station 200 from transmitting, even if they do not overlap with beam-based transmission 205 directed to UE 201.

[0042] This difficulty is exacerbated because even during the acquired COT period, transmitter transmissions typically experience gaps. The transmitter must perform further channel access procedures after these gaps before resuming transmission, which provides an opportunity for further transmissions blocked by other devices such as 203 and 204 that might have started transmitting after the initial channel access procedures. Even if devices 203 and 204 do not affect transmission beam 205, transmission to UE 201 is again blocked.

[0043] The following are systems designed to improve channel access in beamforming transmission systems. Three main processes used in beamforming transmissions are explained in more detail below. In the first type of process, the base station initiates channel access with an omnidirectional channel access procedure (e.g., an LBT procedure that detects all transmissions in any direction). However, if the base station subsequently wishes to change to a different beam at the COT, it performs a directional channel access procedure to check if the direction of the new beam is clear. In the second type of process, the base station performs a directional channel access procedure both when initiating channel access and when switching beams. In this second type of process, the base station's first transmission in a particular beam direction will use a random backoff duration, regardless of whether it is the start of a new COT or a change of direction within a COT. In the third type of process, the base station can choose between an omnidirectional or directional channel access procedure when initiating channel access. The choice may depend on regulations or system configuration and traffic requirements. Using a directional channel access procedure may give devices an unfair channel access advantage compared to systems that only use an omnidirectional channel access procedure (e.g., Wi-Fi), so it is best to avoid using a directional channel access procedure in each case.

[0044] Uplink (UL) transmissions from the UE to the base station can also utilize beamforming, and procedures for such transmissions have been disclosed. In this first type of procedure, the UE can perform directional LBT in the direction of its intended transmission beam before initiating the transmission.

[0045] The process for sharing channel occupancy from the initiating device to other devices in the network is also outlined below. When channel occupancy is shared from the base station to the UE or from the UE to the base station for COT initiated using a directed LBT, immediate transmission may not be supported even if the gap between handover transmissions is less than the regulated immediate transmission threshold, such as 16 microseconds. Therefore, there is always a directed LBT with a deterministic duration before sharing.

[0046] As will be understood from the following revelation, each type of feature can be used in combination or varied appropriately.

[0047] The first type of procedure used for downlink transmission can be called Omni-Start, Directional-Switch (OS-DS) channel access. In such a procedure, an omni-directional channel access procedure (e.g., LBT) with random duration and backoff precedes the initial channel acquisition. Within the acquired channel occupancy, the base station executes the directional channel access procedure before each beam change.

[0048] Before initiating transmission, the base station executes its omnidirectional channel access procedure, and if successful, transmission begins during COT. The omnidirectional channel access procedure for initiating COT has a random duration and backoff. While the basic parameters of the number of sensing slots, contention window, and backoff can be adjusted according to specifications on a given spectrum, this omnidirectional LBT is very similar to existing type 1 based channel access procedures. The channel access procedure uses an energy detection threshold corresponding to the maximum effective isotropically radiated power in any beam direction. That is, the energy detection threshold is selected by considering the transmit power the base station intends to transmit in a beam with combined antenna / panel gain and beamforming gain. When the transmit power or gain differs in different beam directions, the procedure aims to use the energy detection threshold corresponding to the beam with the maximum radiated power.

[0049] If the base station intends to change the beam direction from the first direction BD during its channel occupancy period i Change to second direction BD j (i≠j), then when intending to start transmitting beam BD j The directional channel access procedure is executed in the direction of the current beam. If the channel is clear, transmission will simply switch to the new beam.

[0050] Before switching BD j The parameters of the channel access procedure depend on BD j Transmission gap in the direction, not BD i End of transmission and BD j The time between the start of transmission. Because the beam is in different directions, BD i and BD j The gap between transmissions may not be a useful metric. In legacy systems, if the gap between transmissions is less than a threshold, such as 16 microseconds, transmissions can be restarted without a channel access procedure. However, this may not be suitable when changing the beam, because even if the channel is in BD... i The direction is occupied by the base station, and other devices may also be using BD. j The direction is not occupied by the base station. Therefore, transmission may not be allowed immediately after beam switching, and a channel access procedure should be required before switching to the new beam.

[0051] In summary, when the initiating device transmits its beam from a given beam direction BD during its channel occupancy period... i Switch to different directions BD jWhen (i≠j), regardless of the gap during the switching, immediate transmission is not permitted; a channel access procedure is required before transmission. Although the beam direction is referenced, the same principle applies to other relevant beam characteristics. For example, beam width or distance can also be considered a change in direction and therefore will also be considered as described in terms of direction.

[0052] Different types of channel access procedures can be performed before beam switching. In the first type (D1A), the directional channel access procedure always has a deterministic sensing duration defined by the transmission gap on the associated beam. Random duration sensing and backoff are not used. For example, types 2A or 2B from TS37.213 can be used, or another type where the sensing period is deterministic and based on the transmission gap, and there is no random backoff. Based on the fundamental principles of the omnidirectional channel access procedure used for initial channel acquisition, the deterministic duration is used for the directional channel access procedure during channel occupancy. Deterministic channel access procedure types 2A and 2B are used for gap durations of up to 25 and 16 microseconds, respectively. These gaps, representing only a few OFDM symbols of a large subcarrier spacing, may be insufficient for beam switching scenarios where the beam may typically be inactive for relatively long durations. Therefore, it may be necessary to define new, longer gap durations and associated (longer) deterministic channel access procedures for beam switching scenarios.

[0053] In the second type of directional channel access procedure, a deterministic duration or a random duration can be used for channel awareness in the direction of the intended transmit beam. If the transmission gap on the new beam is below a threshold, the directional channel access procedure is deterministic (e.g., type 2A, 2B, or other definitions with appropriate durations), but if the transmission gap exceeds the threshold, the directional channel access procedure uses random duration channel awareness prior to beam switching (e.g., type 1LBT).

[0054] Obviously, switching to a new beam does not restart the COT (Channel Access Time) that was obtained from the initial channel access obtained through a channel sensing procedure with a backoff omnidirectional random duration. Therefore, the base station will perform the directional channel access procedure as described above during the channel occupancy period prior to each beam switching event, and must leave the channel occupancy before the maximum COT duration, which corresponds to the channel access priority level, the parameters of which are part of the omnidirectional channel access procedure to initiate channel access.

[0055] The combination of omnidirectional and directional channel access procedures provides good coexistence with other systems that may not use directional access procedures by initiating omnidirectional-aware channel access, while using directional procedures before beam-switching events avoids interference with devices that become active in the new beam direction after the initial channel access procedure. Directional channel access procedures aim to provide better channel utilization by enabling transmission in a new direction where no other devices are active but devices are present in other directions. Using purely deterministic durations makes base station transmissions more deterministic, while using random duration awareness promises to improve coexistence.

[0056] The second type of procedure used for downlink transmission can be called Directional-Start, Directional-Switch (DS-DS) channel access. In this type of procedure, although the parameters and characteristics may differ, the base station executes a directional channel access procedure to initiate channel access and before switching beams during the acquired channel occupancy period. The channel access procedure for initiating channel access uses a random duration with backoff, after which the base station can begin transmission on the beam on which the channel access procedure was performed. During subsequent COT periods, when the base station needs to switch beams, a directional channel access procedure is executed for the direction of the new beam before transmission to that beam.

[0057] A successful channel access procedure for a given beam direction initiates the COT for the maximum duration MCOT, with parameters defined according to the channel access priority category for this directional channel access procedure. For the initial channel access procedure, the base station uses a random duration channel access procedure with backoff. A set of example parameters for delay duration, sensed duration, and backoff can be similar to Type 1 (3GPP TS 37.213) for omnidirectional channel access procedures in reserved systems. Different parameters or channel categories can be defined to appropriately serve new service types and other system-related parameters in beam-based transmissions, especially at higher frequencies.

[0058] As mentioned above, in BD i To BD j Before beam switching during COT, the base station in the intended beam direction BD j The directional channel access procedure is executed. In the DS-DS channel access procedure, during the acquired COT, three types of directional channel access procedures for use prior to beam switching are discussed below. Specific options can be selected based on the relative importance of performance and coexistence with other devices / technologies. Selection can be defined by standards or based on system configuration and parameters.

[0059] In the first option, the directional channel access procedure prior to beam switching always has a deterministic duration (e.g., type 2A, 2B, or another type), where the perceived duration is a function of the time gap between the new beam and the time gap before transmission. Existing types 2A and 2B are used for gap durations of up to 25 and 16 microseconds, respectively. These gaps, representing only a few OFDM symbols of a large sub-carrier spacing, may be insufficient for beam switching scenarios where the beam may typically be inactive for relatively long periods. Therefore, it may be necessary to define new, longer gap durations and associated (longer) deterministic channel access procedures for beam switching systems.

[0060] In the second option, the directional channel access option prior to beam switching can use deterministic or random duration for channel awareness in the intended beam direction. In this option, directional channel access with random duration and backoff (e.g., type 1 LBT) precedes the first transmission in any beam direction, even if the first transmission occurs in the middle of acquiring channel occupancy. When switching to a beam direction for which a random duration backoff LBT procedure has already been performed in the current COT (i.e., the base station returns to the previous beam), the base station executes a deterministic duration channel access procedure (type 2A, 2B, or similar other types), regardless of the transmission gap duration in that beam direction.

[0061] In the third option, a directional channel access procedure of deterministic or random duration can be employed prior to beam switching for channel awareness in the intended beam direction. This directional channel access procedure for a given beam direction can be deterministic (type 2A, 2B, or some other new length) as a function of the time gap during which the base station does not transmit in a given beam direction, and should have a random duration and backoff (e.g., type 1LBT) if the transmission gap exceeds a given threshold time. Therefore, a random duration directional channel access procedure is used before the first beam is used in the COT, or if the beam's transmission gap is greater than the threshold.

[0062] Under the DS-DS option, the base station can use the random duration channel access procedure (LBT) at any time to use any beam direction. Since this procedure is also used to initiate COT, it's possible to consider starting a new COT with each new beam direction added after the LBT. This could result in a new beam direction being added after transmission has started in the first set of beam directions, and the base station switching transmission to that first set. With each beam direction switch, the COT timer can be restarted repeatedly. However, beam directions between adjacent beams are not truly orthogonal, and energy spillover may occur in spatially adjacent beams. Therefore, if channel occupancy is allowed to restart with a new beam added in a previous channel occupancy, other devices in the transmission area may be penalized.

[0063] To avoid this problem, COT can begin with the first transmission in any beam direction and must end after the relevant CAPC parameters used in the channel access procedure of the first transmission. That is, COT will not restart due to beam switching events within the channel occupancy acquired on the same frequency.

[0064] Using directional channel access procedures to initiate channel occupancy is expected to improve base station performance, while this technique prior to beam switching is anticipated to improve coexistence. The use of deterministic procedures makes base station transmissions more deterministic and allows for better scheduling of their transmissions; in particular, random-duration channel access procedures can improve coexistence with other devices that may belong to different radio access technologies.

[0065] The third type of channel access procedure used for downlink transmission can be called Configurable Start-Directional Switch (CS-DS) channel access. In this type of procedure, the base station initiates access to the channel using an omnidirectional or directional channel access procedure with a random duration. For example, the base station can initially use an omnidirectional procedure, and if access is successful, it can begin transmission and use the first type of procedure (OS-DS) discussed above for transmission and beam switching.

[0066] If the omnidirectional channel access procedure fails more than a threshold number of times, or if the base station determines that channel access cannot be secured through the omnidirectional process due to some active devices in a certain direction, the base station may switch to the directional channel access procedure for its preferred beam direction. If channel access is successful, the base station may continue using the second option (DS-DS) discussed above to continue transmission and beam switching.

[0067] The switching from omnidirectional channel access procedures can be defined by standards or configuration and depends on any relevant parameters. For example, the number of attempts before a change can be defined, or channel occupancy can be specified. When both directional and omnidirectional procedures are permitted, the base station can also select the appropriate procedure for active service / transmission requirements.

[0068] A similar principle can be applied to uplink transmissions utilizing beamforming. If a UE needs to transmit uplink data in the Physical Uplink Shared Channel (PUSCH) as part of dynamic grant or configured grant-based scheduling, or needs to transmit on the Physical Uplink Control Channel (PUCCH) carrying HARQ feedback or other control information, the UE may need to initiate channel occupancy. If granted access to the channel, the UE can perform a directional channel access procedure with a random duration and backoff for the beam direction it intends to transmit in. Using a directional awareness procedure to obtain channel access may be more suitable for uplink transmissions because each UE transmits to the base station only in a given direction, whereas in the downlink, the base station may transmit to different UEs in multiple directions. Therefore, to initiate channel access for uplink transmissions on unlicensed spectrum, the UE will perform a channel access procedure with a random duration and a backoff in the direction it intends to transmit in. This is similar to uplink type 1 channel access, although it is directional in nature. Using a directional channel access procedure increases the probability of a UE obtaining channel access because it maintains awareness in the direction of intended transmission. Transmissions in other areas / directions are not considered in this sensing procedure, which could otherwise prevent omnidirectional channel access from the same UE.

[0069] The UE can change / refine its uplink transmission beam during COT. This can result in gaps on the unlicensed channel if the base station sends downlink indications on the same unlicensed channel. It can also result in gapless changes to the UE's transmission beam on the unlicensed carrier if the base station is using a licensed downlink carrier or a different carrier. Whenever the UE switches / refines its transmission beam during COT, a channel access procedure should be performed for the beam it switches to. The channel access procedure prior to beam switching within the acquired channel occupancy has a deterministic duration. For example, a fixed-duration LBT of 25 microseconds can be used before the UE updates / refines its transmission beam.

[0070] The UE may determine the beam characteristics of the transmission to the base station from the beam used for transmission in the opposite direction from the base station to the UE (called beam correspondence). However, channel access procedures should be performed for the transmission direction, so even if the beam details are derived from the downlink transmission beam, they should be performed for the uplink transmission.

[0071] Obviously, directional channel access procedures are only beneficial to UEs capable of directional transmission, while UEs capable only of omnidirectional transmission can perform omnidirectional channel access procedures. Furthermore, UEs capable of beamforming transmission may not always use this technology and may perform omnidirectional transmission, for example, when they do not have sufficient information to define the beam direction.

[0072] The channel occupancy of the first device may be shared with its responding device. If a gap exists in this sharing, a deterministic duration channel access procedure is applied, but if the gap is less than a threshold (e.g., 16 microseconds ETSI EN 301.8935GHz RLAN; the Harmonized Standard covers the basic requirements of Article 3.2 of Directive 2014 / 53 / EU), immediate transmission can be performed without any channel access procedure.

[0073] like Figure 3 As shown, this principle may increase the difficulty of directional transmission and channel access procedures. Figure 3 In (A), base station 300 uses a directional channel access procedure to obtain channel occupancy in order to perform directional transmission to UE 301. Transmission beam 302 does not overlap with devices 303 and 304, therefore the base station can continue its transmission. However, if UE 301 shares the COT with base station 300 for uplink transmission to the base station, such as... Figure 3 As shown in (B), the transmission beam 305 may extend beyond the base station 300 and interfere with the transmission between devices 303 and 304.

[0074] To avoid such interference, when sharing a COT, even if the transmission gap is below a threshold, the responding device should not be allowed to transmit without having performed a channel access procedure for the expected transmission. In other words, if a directional channel access procedure has been performed to acquire a channel or before a beam-switching event, the responding device is not allowed to transmit immediately during a shared COT.

[0075] Regarding the above options, if the base station has already obtained channel access using the OS-DS method, then if the transmission gap is less than a threshold, such as 16 microseconds, the UE can be allowed to immediately transmit to share the COT, and the UE shares the COT after the base station transmits in the first beam direction before any beam switching. In the OS-DS method, if the UE shares the base station-initiated COT in the beam before the base station performs directional channel access, then the UE is not allowed to transmit immediately. If access has already been obtained using the DS-DS method, then the UE is not allowed to transmit immediately regardless of the transmission gap.

[0076] To allow the enforcement of these rules, the device initiating channel occupancy can indicate the type of channel access procedure used to obtain access. Specifically, it can indicate whether an omnidirectional or directional channel access procedure was used. This information can be selectively provided to other devices that may share the channel occupancy of the initiating device.

[0077] When a base station acquires a channel and schedules a UE for transmission after a channel access procedure, the base station can instruct the UE to use a specific channel access procedure before the scheduled transmission. Therefore, even if the scheduled UE can begin its transmission without a transmission gap on the channel (or with a gap less than the threshold for immediate transmission, e.g., 16 microseconds), the base station must instruct a channel access procedure with a deterministic duration. This may increase the gap between transmissions on the channel. The base station can send a COT sharing indication to UEs in the cell using DCI format 2_0 (section 7.3.1.3.1 in 3GPP TS38.212). In reserved systems, UEs that must send a PUCCH containing HARQ feedback or other control information, and UEs with periodic configuration authorization, can use the COT sharing indication for immediate transmission without knowing that the UE's base station has a channel access procedure for channel occupancy. To share channel occupancy in a meaningful manner with the proposed directional approach, the base station can include in the COT sharing indication whether an omnidirectional or directional channel access procedure is used to acquire channel access. This information can be included in the COT sharing indication, which can be contained in DCI format 2_0. Based on these instructions, a UE intending to share a base station COT can decide whether it can accept immediate transmission or whether it should perform a channel access procedure with a deterministic duration. The type and duration of the access procedure performed by the UE can be defined through specifications or configuration.

[0078] The same principle applies when a UE obtains channel access and the base station intends to share that channel occupancy. The UE can indicate to the base station the type of channel access procedure (omnidirectional or directional) performed to obtain channel access. The UE can transmit this information in uplink control information transmissions, such as PUSCH or PUCCH transmissions performed by the UE. The base station can use this information to determine whether immediate transmission using COT is possible.

[0079] Before transmitting control information or other UE data within the cell using the COT acquired by the UE, the base station selects the appropriate channel access procedure to be performed based on an indication of the type of procedure executed by the UE. If the UE acquires the channel via a directional procedure, the base station takes this into account before transmission within the COT. This depends on the strategy used by the base station when initiating channel access. If the base station uses OS-DS as discussed above, transmission is not possible in directions other than those of the UE that acquired the channel without executing an omnidirectional channel access procedure. If the base station uses DS-DS, the COT can be extended to other beam directions based on a DS-DS configuration that performs channel access in the beam direction of the intended transmission.

[0080] Generally, the UE will follow the channel access procedure indicated to it as part of the Dynamic Grant (DG) downlink control information. If, by chance, the UE receives a COT sharing indication from the base station after the DG, where the DG resources fall within the COT indicated by the base station, the UE may need to update the type of channel access procedure to be performed before transmission. If the base station has already performed an omnidirectional channel access procedure, the UE can perform immediate transmission if the transmission gap is less than 16 microseconds (or other appropriate threshold). If the base station uses a directional channel access procedure to initiate the COT (e.g., if the base station is using the DS-DS scheme discussed above), immediate transmission on the COT independent of the gap duration is not supported, and the UE will perform a channel access procedure of deterministic duration, the parameters of which may be part of a previous configuration.

[0081] For CG-based transmissions, the UE can be configured to initiate COT using a random duration channel access procedure. If the UE receives a valid COT sharing indication from the base station for the CG resources on which the UE intends to transmit, this implies that the UE transmission will effectively share the base station's COT. In this case, the UE will perform a deterministic duration channel access procedure in the direction of the transmit beam it intends to transmit on the CG resources. If the UE can determine that there is an omnidirectional LBT before the last transmission from the base station before the UE shares the COT, the UE can transmit immediately without being aware of the gap duration (currently 16 microseconds).

[0082] The selection of the energy detection threshold is crucial for channel-aware procedures. The energy detection threshold needs to be updated for direction-aware and omnidirectional (or isotropic) or dipole-based sensing. When a device, whether a base station or a UE, employs direction-aware sensing, it needs to consider the effective isotropically radiated power it intends to transmit on the acquired channel to update the energy detection threshold. This means that in addition to transmit power, all beamforming, antenna, or antenna panel gain will be included to obtain a suitable energy detection threshold.

[0083] The energy detection threshold can be updated based on the angular spread of the beam the device intends to transmit after channel acquisition. In this approach, isotropic energy thresholds defined by standards and regulatory bodies may be updated based on the expected beamwidth. For example, if the device intends to transmit in an area covering only 120 degrees, it could divide the energy detection threshold by a factor of 360 / 120 = 3, where 360 ​​represents isotropic (omnidirectional) propagation. This can be problematic if the device emits a very narrow beam to gain an advantage over other devices. To avoid this problem, different factors can be defined for different angular ranges.

[0084] Therefore, various methods and procedures have been defined to allow efficient transmission resource sharing in unlicensed spectrum using directional channel access procedures.

[0085] Obviously, the channel access procedure discussed in this paper can be performed in any suitable manner, but it is usually a Listen-Before-Speak (LBT) process, in which the UE must listen for transmissions for a period of time to perform a clear-channel assessment before transmission.

[0086] Although not shown in detail, any apparatus or device forming part of a network may include at least a processor, a storage unit, and a communication interface, wherein the processor unit, storage unit, and communication interface are configured to perform the methods of any aspect of the present invention. Further options and choices are described below.

[0087] The signal processing functions of this invention, particularly for gNB and UE, can be implemented using computing systems or architectures known to those skilled in the art. For a given application or environment, using a computing system, such as a desktop, laptop, handheld computing device (PDA, mobile phone, PDA, etc.), mainframe, server, client, or any other type of dedicated or general-purpose computing device, is ideal or appropriate. The computing system may include one or more processors, which can be implemented using general-purpose or dedicated processing engines such as microprocessors, microcontrollers, or other control modules.

[0088] The computing system may also include main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions executed by the processor. Such main memory can also be used to store temporary variables or other intermediate information during the execution of instructions by the processor. The computing system may also include read-only memory (ROM) or other static storage devices for storing static information and instructions of the processor.

[0089] The computing system may also include an information storage system, which may include, for example, media drives and removable storage interfaces. Media drives may include drives or other mechanisms that support fixed or removable storage media, such as hard disk drives, floppy disk drives, magnetic tape drives, optical disc drives, compact disc (CD) or digital video drives (DVD) (RTM), read or write drives (R or RW), or other removable or fixed media drives. Storage media may include, for example, hard disks, floppy disks, magnetic tapes, optical discs, CDs, or DVDs, or other fixed or removable media that can be read and written by media drives. Storage media may include computer-readable storage media in which specific computer software or data is stored.

[0090] In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, removable storage units and interfaces, such as program boxes and box interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, as well as other removable storage units and interfaces that allow software and data to be transferred from the removable storage units to the computing system.

[0091] The computing system may also include a communication interface. Such a communication interface can be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (such as Ethernet or other NIC cards), communication ports (such as Universal Serial Bus (USB) ports), PCMCIA slots and cards, etc. Software and data transmitted via the communication interface are in the form of signals, which may be electronic, electromagnetic, optical, or other signals that can be received by the communication interface medium.

[0092] In this document, the terms "computer program product," "computer-readable medium," etc., are generally used to refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. Such instructions, commonly referred to as "computer program code" (which may be grouped as computer programs or other groups), when executed, enable a computing system to perform the functions of embodiments of the present invention. Note that code may directly cause a processor to perform specified operations, be compiled to perform such operations, and / or be combined with other software, hardware, and / or firmware elements (e.g., libraries for performing standard functions) to perform such operations.

[0093] Non-transitory computer-readable media may include at least one from the group consisting of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memories, programmable read-only memories, erasable programmable read-only memories, EPROMs, electrically erasable programmable read-only memories, and flash memory. In embodiments using software-implemented components, the software may be stored in a computer-readable medium and loaded into a computing system using, for example, a removable storage drive. When executed by a processor in a computer system, a control module (in this example, software instructions or executable computer program code) causes the processor to perform the functions of the invention as described herein.

[0094] Furthermore, the concepts of this invention can be applied to any circuit used to perform signal processing functions within network components. It is further envisioned that, for example, semiconductor manufacturers can incorporate the concepts of this invention into the design of stand-alone devices, such as microcontrollers for digital signal processors (DSPs), or application-specific integrated circuits (ASICs), and / or any other subsystem elements.

[0095] It should be understood that, for clarity, the above description has referred to embodiments of the invention with reference to a single processing logic. However, the inventive concept can also be implemented by a number of different functional units and processors to provide signal processing functionality. Therefore, references to specific functional units are to be regarded only as references to suitable means for providing said functionality, and not as indications of a strict logical or physical structure or organization.

[0096] Various aspects of the present invention can be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. The present invention can optionally be implemented, at least in part, as computer software running on one or more data processors and / or digital signal processors or configurable module components such as FPGA devices.

[0097] Therefore, the components and elements of the embodiments of the present invention can be implemented physically, functionally, and logically in any suitable manner. In fact, functionality can be implemented in a single unit, in multiple units, or as part of other functional units. Although the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features may appear to be described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined according to the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

[0098] Furthermore, although listed separately, multiple means, components, or method steps can be implemented by, for example, a single unit or processor. Moreover, while individual features may be included in different claims, these can be advantageously combined, and inclusion in different claims does not imply that the combination of features is infeasible and / or unadvantageous. Furthermore, including a feature in one class of claims does not imply a limitation on that class, but rather indicates that the feature is equally applicable to other claim classes, as appropriate.

[0099] Furthermore, the order of features in the claims does not imply any particular order in which these features must be performed; in particular, the order of steps in a method claim does not imply that these steps must be performed in this order. On the contrary, these steps can be performed in any suitable order. Moreover, singular references do not exclude plural forms. Therefore, references to “a,” “an,” “first,” “second,” etc., do not exclude plural forms.

[0100] Although the invention has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the scope of the invention is limited only by the appended claims. Furthermore, although features may appear to be described in conjunction with specific embodiments, those skilled in the art will recognize that various features of the described embodiments can be combined according to the invention. In the claims, the terms "comprising" or "including" do not exclude the presence of other elements.

Claims

1. A channel sensing method performed by a first radio station in a cellular communication network, the first radio station being capable of beamforming transmission, characterized in that, The method includes the following steps: Before transmission, a first channel sensing process is performed at the first radio station, wherein a successful first channel sensing process acquires the transmission channel with channel occupancy time, and the first channel sensing process is selected from omnidirectional and directional channel sensing processes; The first signal is transmitted from the first radio station to the second radio station using the transmission channel; Before the channel occupancy time expires, a directional second channel sensing process is performed at the first radio station, wherein the directional second channel sensing process is performed in the direction of the new beam that the first radio station intends to transmit; and Following the successful orientation of the second channel sensing process, the second signal is transmitted from the first radio station to the second radio station using the new beam. When the transmission gap on the new beam is below a threshold, the directional channel access process uses a deterministic duration; when the transmission gap exceeds the threshold, the directional channel access process uses a random duration.

2. The method according to claim 1, characterized in that, The choice between omnidirectional or directional channel sensing is defined by the system configuration.

3. The method according to claim 1, characterized in that, The first channel sensing process is an omnidirectional channel sensing process.

4. The method according to claim 1, characterized in that, The first channel sensing process is a directional channel sensing process performed in the direction of the first beam in which the first radio station intends to transmit the first signal; the direction of the first beam is different from the direction of the new beam.

5. The method according to claim 1, characterized in that, The first channel sensing process is an omnidirectional process that is performed once or multiple times to attempt to acquire the channel. The method further includes performing a further first channel sensing process if the first channel sensing process fails to acquire the transmission channel, wherein the further first channel sensing process is a directional channel sensing process.

6. The method according to any one of claims 1 to 5, characterized in that, The first and / or second channel sensing process uses random backoff.

7. The method according to any one of claims 1 to 6, characterized in that, The first and / or second channel sensing process uses a random duration.

8. The method according to any one of claims 1 to 6, characterized in that, The first and / or second channel sensing process uses a deterministic duration.

9. The method according to any one of claims 1 to 6, characterized in that, The first and / or second channel sensing process uses a deterministic duration unless, when the channel access process acquires the transmission channel, the gap between transmissions on the beam to be used exceeds a threshold, in which case a random duration is used.

10. The method according to claim 8 or 9, characterized in that, The duration depends on the gap between transmissions on the beam, which will be used if the channel access process acquires the channel.

11. The method according to any one of claims 1 to 10, characterized in that, The first and / or second channel sensing process utilizes an energy detection threshold based on the maximum effective isotropic radiated power in any beam direction of the radio station performing the sensing process.

12. The method according to any one of claims 1 to 11, characterized in that, Transmissions on the new beam will end no later than the expiration of the channel occupancy time at the start of the first channel sensing process.

13. The method according to any one of claims 1 to 12, characterized in that, The first and second channel sensing processes are listening-before-speaking processes.

14. The method according to any one of claims 1 to 13, characterized in that, The first radio station transmits information about the first and / or second channel sensing process.

15. The method according to claim 14, characterized in that, The information indicates whether the first channel sensing process is omnidirectional or directional.

16. The method according to any one of the preceding claims, characterized in that, The first radio station is a base station.

17. The method according to any one of claims 1 to 15, characterized in that, The first radio station is a UE.

18. A channel sensing method performed by a first radio station in a cellular communication network, the first radio station being capable of beamforming transmission, characterized in that, The method includes the following steps: Before transmission, a first channel sensing process is performed at the first radio station, wherein a successful first channel sensing process acquires the transmission channel with channel occupancy time, and the first channel sensing process is selected from omnidirectional and directional channel sensing processes; The transmission channel is used to transmit signals from the first radio station to the second radio station; Before the channel occupancy time expires, a directional second channel sensing process is performed at the second radio station, wherein the directional second channel sensing process is performed in the direction of the new beam that the second radio station intends to transmit; and The signal is transmitted from the second radio station using the new beam. When the transmission gap on the new beam is below a threshold, the directional channel access process uses a deterministic duration; when the transmission gap exceeds the threshold, the directional channel access process uses a random duration.

19. The method according to claim 18, characterized in that, The choice between omnidirectional or directional channel sensing is defined by the system configuration.

20. The method according to claim 18, characterized in that, The first channel sensing process is an omnidirectional channel sensing process.

21. The method according to claim 18, characterized in that, The first channel sensing process is a directional channel sensing process performed in the direction of the first beam in which the first radio station intends to transmit the first signal; the direction of the first beam is different from the direction of the new beam.

22. The method according to claim 18, characterized in that, The first channel sensing process is an omnidirectional process that is performed once or multiple times to attempt to acquire the channel. The method further includes performing a further first channel sensing process if the first channel sensing process fails to acquire the transmission channel, wherein the further first channel sensing process is a directional channel sensing process.

23. The method according to any one of claims 18 to 22, characterized in that, The first and / or second channel sensing process uses random backoff.

24. The method according to any one of claims 18 to 23, characterized in that, The first and / or second channel sensing process uses a random duration.

25. The method according to any one of claims 18 to 23, characterized in that, The first and / or second channel sensing process uses a deterministic duration.

26. The method according to any one of claims 18 to 23, characterized in that, The first and / or second channel sensing process uses a deterministic duration unless, when the channel access process acquires the transmission channel, the gap between transmissions on the beam to be used exceeds a threshold, in which case a random duration is used.

27. The method according to claim 25 or 26, characterized in that, The duration depends on the gap between transmissions on the beam, which will be used if the channel access process acquires the channel.

28. The method according to any one of claims 18 to 27, characterized in that, The first and / or second channel sensing process utilizes an energy detection threshold based on the maximum effective isotropic radiated power in any beam direction of the radio station performing the sensing process.

29. The method according to any one of claims 18 to 28, characterized in that, Transmissions on the new beam will end no later than the expiration of the channel occupancy time at the start of the first channel sensing process.

30. The method according to any one of claims 18 to 29, characterized in that, The first and second channel sensing processes are listening-before-speaking processes.

31. The method according to any one of claims 18 to 30, characterized in that, The first radio station transmits information about the first and / or second channel sensing process.

32. The method according to claim 31, characterized in that, The information indicates whether the first channel sensing process is omnidirectional or directional.

33. The method according to any one of claims 18 to 32, characterized in that, The first radio station is a base station.

34. The method according to any one of claims 18 to 32, characterized in that, The first radio station is a UE.

35. A base station, characterized in that, It is configured to perform the method of any one of claims 1 to 17 and 18 to 32.

36. A UE, characterized in that, It is configured to perform the method of any one of claims 1 to 17 and 18 to 32.

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