WO2021108817A2

WO2021108817A2 - Methods and apparatus for channel sensing for beamformed transmissions

Info

Publication number: WO2021108817A2
Application number: PCT/US2021/026458
Authority: WO
Inventors: Weimin Xiao; George Calcev; Qian CHENG; Jialing Liu
Original assignee: Futurewei Technologies, Inc.
Priority date: 2020-05-22
Filing date: 2021-04-08
Publication date: 2021-06-03
Also published as: WO2021108817A3

Abstract

A method implemented by a transmitting device includes sensing, by the transmitting device during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determining, by the transmitting device, a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determining, by the transmitting device, that the channel is idle in accordance with the sensing threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

Description

Methods and Apparatus for Channel Sensing for Beamformed Transmissions

This application claims the benefit of U.S. Provisional Application No. 63/029,035, filed on May 22, 2020 and entitled "Apparatus and Methods for Channel Sensing for Beamformed Transmissions," which application is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to methods and apparatus for digital communications, and, in particular embodiments, to methods and apparatus for channel sensing for beamformed transmissions.

BACKGROUND

In the license exempt spectrum, a.k.a., unlicensed spectrum or shared spectrum, in order to minimize the interference into ongoing transmissions the transmitter devices will use listen before talk (LBT) approach where they sense the channel (a commonly used technique is the clear channel assessment (CCA)) before initial transmissions. During the sensing period, the energy in the channel or received preambles are measured and compared with reference CCA thresholds. If the received energy is below the CCA threshold, the channel is deemed to be clear and the transmission can take place. Additional details regarding the CCA process may be found in European Telecommunications Standards Institute (ETSI) documents EN 301893 and EN 302567 for unlicensed access in the 5 GHz and 60 GHz spectrum bands, respectively.

After the channel is found clear (or idle) and hence available for transmission, the initiator of the transmission and the receivers could have successive transmissions for a duration up to the maximum channel occupancy time (COT).

However, existing CCA procedures do not consider beamformed transmission and reception, which introduces antenna gain that differs in different directions and communication beams. Therefore, there is a need for methods and apparatus for channel sensing in beamformed transmissions.

SUMMARY

According to a first aspect, a method implemented by a transmitting device is provided. The method comprising: sensing, by the transmitting device during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determining, by the transmitting device, a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determining, by the transmitting device, that the channel is idle in accordance with the sensing threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

In a first implementation form of the method according to the first aspect, the sensing using a receive spatial filter.

In a second implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the sensing comprising detecting an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

In a third implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the channel is determined as idle if the energy level associated with the channel is lower than the energy detection threshold.

In a fourth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the transmitting using at least one transmitting spatial filter.

In a fifth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising starting, by the transmitting device, a channel occupancy time (COT) timer associated with a COT associated with the transmitting.

In a sixth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising expiring, by the transmitting device, the COT timer at least when the COT timer reaches a maximum channel occupancy time.

In a seventh implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising completing, by the transmitting device, the transmitting prior to expiration of the COT timer.

In an eighth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising stopping, by the transmitting device, the transmitting responsive to the expiration of the COT timer. In a ninth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the channel is determined as busy if the energy level associated with the channel is higher than the energy detection threshold.

In a tenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the sensing comprising preamble detection, and the sensing threshold comprising a preamble detection threshold.

In an eleventh implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the at least one transmitting spatial filter being associated with the at least one transmit beam.

In a twelfth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

In a thirteenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between an effective isotropic radiated power (EIRP) of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

In a fourteenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

In a fifteenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising transmitting, by the transmitting device, physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

In a sixteenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising determining, by the transmitting device during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

In a seventeenth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, further comprising determining, by the transmitting device during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam.

According to a second aspect, a transmitting device is provided. The transmitting device comprising: one or more processors; and a non-transitoiy memory storage comprising instructions that, when executed by the one or more processors, cause the transmitting device to: sense, during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determine a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determine that the channel is idle in accordance with the sensing threshold, and based thereon, transmit on the channel using the at least one transmit beam.

In a first implementation form of the transmitting device according to the second aspect, the instructions causing the transmitting device to detect an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

In a second implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to start a COT timer associated with a COT associated with the transmitting.

In a third implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to expire the COT timer at least when the COT timer reaches a maximum channel occupancy time.

In a fourth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to complete the transmitting prior to expiration of the COT timer. In a fifth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to stop the transmitting responsive to the expiration of the COT timer.

In a sixth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

In a seventh implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between an EIRP of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

In an eighth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

In a ninth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to transmit physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

In a tenth implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to determine, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmit on the channel using the at least one transmit beam.

In an eleventh implementation form of the transmitting device according to the second aspect or any preceding implementation form of the second aspect, the instructions causing the transmitting device to determine, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam.

According to a third aspect, a non-transitory computer-readable media storing computer instructions is provided. When executed by one or more processors, the instructions cause the one or more processors to perform the steps of: sensing, by a transmitting device during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determining, by the transmitting device, a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determining, by the transmitting device, that the channel is idle in accordance with the sensing threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

In a first implementation form of the media according to the third aspect, the instructions causing the one or more processors to perform the step of detecting an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

In a second implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of starting a COT timer associated with a COT associated with the transmitting.

In a third implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of expiring the COT timer at least when the COT timer reaches a maximum channel occupancy time.

In a fourth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of completing the transmitting prior to expiration of the COT timer.

In a fifth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of stopping the transmitting responsive to the expiration of the COT timer. In a sixth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

In a seventh implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between an EIRP of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

In an eighth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

In a ninth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of transmitting physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

In a tenth implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of determining, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmit on the channel using the at least one transmit beam.

In an eleventh implementation form of the media according to the third aspect or any preceding implementation form of the third aspect, the instructions causing the one or more processors to perform the step of determining, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam. An advantage of a preferred embodiment is that beamforming gain is considered in setting the CCA threshold for channel sensing so that more accurate channel sensing performance is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

Figure t illustrates a first example communications system;

Figure 2 illustrates a diagram of fixed frame periods for frame-based equipment (FBE);

Figures 3A and 3B illustrate a flow diagram of a prior art technique for adaptively initiating a communicating device as specified in ETSI EN301893;

Figure 4 illustrates an example communications system, providing mathematical expressions of signals transmitted in the communications system;

Figures 5A and 5B are block diagrams of embodiments of systems for analog beamsteering plus digital beamforming;

Figure 6 illustrates a diagram of an example timing for FBE;

Figure 7 illustrates a flow diagram of example operations occurring in carrier sensing;

Figure 8 illustrates a flow diagram of example operations occurring in a general listen before talk (LBT) mechanism;

Figure 9 illustrates a diagram of the channel access procedure of WiFi compliant communication systems;

Figure 10A illustrates a diagram of a wide beam pattern;

Figure 10B illustrates a diagram of a narrow beam pattern;

Figure 11A illustrates a diagram of the clear channel assessment (CCA) threshold defining a zone or volume around a device;

Figure 11B illustrates a diagram of beam-based sensing threshold where the sensing threshold is adapted as a ratio between the beamforming gain (or equivalent isotropic radiated power (EIRP) when the same beam is used for transmission) of the sensing beam and the maximum beamforming gain (or EIRP) of the transmission beam(s);

Figure ltC illustrates a diagram of a situation when the beam used for sensing is also used for transmitting;

Figure 12 illustrates a flow diagram of operations occurring in a transmitting device making a transmission in unlicensed spectrum utilizing beamformed LBT according to example embodiments presented herein;

Figure 13A illustrates a diagram of a synchronization signal (SS) burst according to example embodiments presented herein;

Figure 13B illustrates a diagram of signals multiplexed for more than one UE according to example embodiments presented herein;

Figure 14 illustrates a diagram of non-zero power (NZP) channel state information reference signal (CSI-RS) according to example embodiments presented herein;

Figure 15 illustrates a diagram of physical downlink shared channel (PDSCH) or physical uplink control channel (PUCCH) multiplexing, as well as PUCCH, PUSCH, or demodulation reference signal (DMRS) multiplexing according to example embodiments presented herein;

Figure 16 illustrates a diagram of a set of transmission beams covering the entirety of a sensing coverage area according to example embodiments presented herein;

Figure 17 illustrates a table of a first example multiplexing of transmission beams in time and frequency during a channel occupancy time (COT) according to example embodiments presented herein;

Figure 18 illustrates a diagram of an interaction of a transmission over a transmission beam and a sensing coverage area of another device according to example embodiments presented herein;

Figure 19 illustrates a table of a second example multiplexing of transmission beams in time and frequency during a COT according to example embodiments presented herein;

Figure 20 illustrates a table of a third example multiplexing of transmission beams in time and frequency during a COT according to example embodiments presented herein; Figure 21 illustrates a table of a fourth example multiplexing of transmission beams in time and frequency during a COT according to example embodiments presented herein;

Figure 22 illustrates a flow diagram of operations occurring in a transmitting device making a transmission in unlicensed spectrum utilizing beamformed LBT with multiple transmission beams according to example embodiments presented herein;

Figure 23 illustrates a flow diagram of example operations occurring in the UE making an uplink transmission in unlicensed spectrum utilizing beamformed LBT with multiple transmission beams according to example embodiments presented herein;

Figure 24 illustrates an example communication system according to example embodiments presented herein;

Figures 25A and 25B illustrate example devices that may implement the methods and teachings according to this disclosure; and

Figure 26 is a block diagram of a computing system that may be used for implementing the devices and methods disclosed herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The structure and use of disclosed embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific structure and use of embodiments, and do not limit the scope of the disclosure.

Figure 1 illustrates a first example communications system too. Communications system too includes an access node 110, with coverage area 101, serving user equipments (UEs), such as UEs 120. Access node 110 is connected to a backhaul network 115 that provides connectivity to services and the Internet. In a first operating mode, communications to and from a UE passes through access node 110. In a second operating mode, communications to and from a UE do not pass through access node 110, however, access node 110 typically allocates resources used by the UE to communicate when specific conditions are met. Communication between a UE pair in the second operating mode occurs over sidelinks 125, comprising uni-directional communication links. Communication between a UE and access node pair also occur over uni-directional communication links, where the communication links between the UE and the access node are referred to as uplinks 130, and the communication links between the access node and UE is referred to as downlinks 135.

A cell may include one or more bandwidth parts (BWPs) for UL or DL allocated for a UE. Each BWP may have its own BWP-specific numerology and configuration. It is noted that not all BWPs need to be active at the same time for the UE. A cell may correspond to one or more carriers. Typically, one cell (a primary cell (PCell) or a secondary cell (SCell), for example) is a component carrier (a primary component carrier (PCC) or a secondary CC (SCC), for example). For some cells, each cell may include multiple carriers in UL, one carrier is referred to as an UL carrier or non-supplementary UL (non-SUL) UL carrier which has an associated DL, and other carriers are called a supplementary UL (SUL) carriers which do not have an associated DL. A cell, or a carrier, may be configured with slot or subframe formats comprised of DL and UL symbols, and that cell or carrier is seen as operating in time division duplexed (TDD) mode. In general, for unpaired spectrum, the cells or carriers are in TDD mode, and for paired spectrum, the cells or carrier are in a frequency division duplexed (FDD) mode.

Access nodes may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, base stations, access points, transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, and so on, while UEs may also be commonly referred to as mobile stations, mobiles, terminals, users, subscribers, stations, and the like. Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., the Third Generation Partnership Project (3GPP) long term evolution (LTE), LTE advanced (LTE-A), 5G, 5G LTE, 5G NR, sixth generation (6G), High Speed Packet Access (HSPA), the IEEE 802.11 family of standards, such as 802.na/b/g/n/ac/ad/ax/ay/be, etc. While it is understood that communications systems may employ multiple access nodes capable of communicating with a number of UEs, only one access node and two UEs are illustrated for simplicity.

As discussed previously, a communicating device transmitting in unlicensed spectrum will use a listen before talk (LBT) approach. In LBT, the communicating device with a transmission performs a channel sensing (e.g., perform a clear channel assessment (CCA)) prior to transmitting. In the channel sensing, the communicating device measures the energy in the channel and compares the measured energy with a reference threshold (e.g., a CCA threshold). If the measured energy is below the reference threshold, the channel is deemed to be clear (e.g., idle) and the communicating device can make the transmission. The communicating device (and a communicating device (or devices) receiving the transmission) may make successive transmissions during a duration referred to as a maximum channel occupancy time (COT).

Figure 2 illustrates a diagram 200 of fixed frame periods for frame-based equipment (FBE). Diagram 200 illustrates a sequence fixed frame periods for FBE as specified in European Telecommunications Standards Institute (ETSI) documents EN 301893, including frame 202. Channel sensing during gaps in the COT (e.g., idle periods) is necessary to preempt transmission collisions (interference) with other transmissions occurring in the same general area.

Frame 202 includes a COT 204 and an idle period 206. During COT 204, a communicating device that determined the channel to be idle can transmit. Typically, a CCA performed before the start of a particular frame. If the channel is idle, the communicating device may start a COT by transmitting at the beginning of the frame. As an example, CCA 208 of idle period 206 is associated with frame 212. Similarly, a communicating device performing CCA 214 can obtain access to the channel for COT 204 in frame 202. The period around the end of a frame is referred to as an idle period and the communicating device is prohibited from transmitting during the idle period.

The LBT procedure specified in ETSI EN301893 includes a fixed sensing period based on traffic priority (a prioritization period), and if the measured energy is below the CCA threshold, the communicating device continues with an extended CCA period that consists of a random CCA duration limited by a contention window (CW) length.

Figures 3A and 3B illustrate a flow diagram of a prior art technique 300 for adaptively initiating a communicating device as specified in ETSI EN301893. Technique 300 includes a prioritization period 302 performs channel sensing based on the priority of the traffic the communicating device has to transmit. As an example, the priority determines a maximum backoff window, where a larger backoff window means that the communicating device must check if the channel is idle for a longer duration (which makes the likelihood of the channel being deemed idle less likely. Hence, the higher priorities correspond to a shorter backoff window (corresponding to a higher probability that the channel is deemed idle). Therefore, the communicating device has increased chance to obtain access to the channel. Furthermore, the COT is typically shorter for the communicating devices with higher priority, meaning that such communicating devices can more readily access the channel, but can keep it for shorter durations. Technique 300 also includes a backoff procedure 304. In backoff procedure 304, the communicating device, upon determining that the channel is busy, waits a random amount of time before attempting to repeat the channel sensing. Furthermore, the communicating device is permitted to decrement the backoff counter only if the channel is deemed idle for the sensing time. If the channel is not idle, the communicating device waits for a random duration.

Once channel access is obtained, the associated COT can be shared between the initiating device (the communicating device with the transmission) and the responding device (the communicating device receiving the transmission). During COT transmission gaps (e.g., idle periods), no transmission periods are allowed. The gaps are also limited in duration. As an example, in the 5 GHz spectrum, only transmission gaps of up to 25 microseconds are allowed. If the transmissions gaps are very short, the LBT is not necessary, and a participant in a COT can transmit without having to sense the channel. For various gap lengths, the communicating devices may be required to use different LBT schemes. For instance, the Third Generation Partnership Project (3GPP) TS 37.213 technical standard specifies, for New Radio unlicensed (NR-U) devices operating in the 5-6 GHz spectrum, that for transmission gaps shorter than 16 microseconds, the LBT (channel sensing) is not required. However, for gaps longer than 16 microseconds the transmitter needs to sense the channel for 16 microseconds (i.e., during the gap), and for gaps of 25 microseconds, the transmitter needs to sense the channel for 25 microseconds.

In general, pathloss increases with frequency. For instance, at 60GHz there is an additional 2tdB (20 log₁₀(f_c60/f_c5)) with respect to 5GHz pathloss (according to 3GPP TR38.901- channel models). In addition, there other factors like oxygen and water absorption that reduce the signal strength. Fortunately, at higher frequencies the antenna dimensions can be substantially reduced (proportionally with the wavelength) and higher antenna gains can be achieved when using highly directional antennas (uniform planar array (UPA) antennas, uniform linear array (ULA) antennas, etc). Using directional antennas increases the antenna gain, and makes possible to improved spatial reuse, thus allowing several transmissions to take place in the same space.

When directional antennas are used to transmit and receive signals, the channel sensing, which is required for space and spectrum sharing, could be limited to the space where the transmissions take place via directional sensing. Directional channel sensing limits, to a smaller space volume, the sensing of interferers, and therefore, has a higher probability in detecting that the channel is clear (and hence allowing transmissions), while limiting the exposed node area. Another advantage of directional channel sensing is the farther transmission collision protection, which is achieved from higher directional antenna gain used for sensing

Under directional channel sensing and transmissions, the COT has a constrained spatial dimension. Therefore, it makes sense to make COT definition more flexible in order to consider the variable number of interferers in the variable space volume. The regulatory or standard setting bodies, such as FCC or ETSI, do not have a clear definition and policy for COT, or allowable gaps during a COT in 6o GHz unlicensed channel.

Figure 4 illustrates an example communications system 400, providing mathematical expressions of signals transmitted in the communications system. Communications system 400 includes an access node 405 communicating with a UE 410. As shown in Figure 4, access node 405 is using a transmit filter v and UE 410 is using a receive filter w. Both access node 405 and UE 410 use linear precoding or combining. Assuming H is N_ra x N_tx matrix of a multiple-input multiple-output (MIMO) system, i.e., there are N_¾ transmit antennas and N_rx receive antennas. The transmit filter v of dimension N_tx x Ns enables the transmitter to precode or beamform the transmitted signal, where Ns is the number of layers, ports, streams, symbols, pilots, messages, data, or known sequences transmitted. The receive filter w of multi-antenna systems is of dimension N_rx x Ns and represents the combining matrix, which is usually applied on the received signal y according to w"y. The above description is for a transmission from access node 405 to UE 410, i.e., a downlink (DL) transmission. The transmission may also occur at the reverse direction (an uplink (UL) transmission), for which the channel matrix becomes H" in the case of TDD (where H" is the Hermitian of channel model H), and w may be seen as the transmit filter and v as the receiver filter. The w for transmission and the w for reception may or may not be the same, and likewise for v.

A DL (or forward) channel 415 between access node 405 and UE 410 has channel model or response H, while an UL (or backward, or reverse) channel 420 between UE 410 and access node 405 has channel model or response H". Another convention is that the UL channel is denoted as H^T, which is the transposition of channel model H. Although Figure 4 depicts only one access node and one UE, communication system 400 is not limited to this case. Multiple UEs may be served by the access node, on different time- frequency resources (such as in frequency division multiplexed-time division multiplexed (FDM-TDM) communication systems, as in typical cellular systems) or on the same time- frequency resources (such as in multi-user MIMO (MU-MIMO) communication systems, wherein multiple UEs are paired together and transmissions to each UE are individually precoded). Among the paired UEs, there is intra-cell interference.

Also multiple access nodes may exist in the network, some of which may be cooperatively serving UE 410 in a joint transmission fashion (such as in coherent joint transmission, non-coherent joint transmission, coordinated multipoint transmission, etc.), a dynamic point switching fashion, and so on. Some other access nodes may not serve UE 410 and their transmissions to their own UEs cause inter-cell interference to UE 410. The scenario of multiple access nodes and multiple UEs, with access node cooperation to serve a UE and with MU-MIMO, is a scenario considered herein.

One way to increase the network resources is to utilize more and more usable spectrum resources, which include not only the licensed spectrum resources of the same type as the macro, but also the licensed spectrum resources of a different type from the macro (e.g., the macro is a FDD cell but a small cell may use both FDD and TDD carriers), as well as unlicensed spectrum resources and shared-licensed spectrums; some of the spectrum resources lie in high-frequency bands, such as 6 GHz to 60 GHz. The unlicensed spectrums can be used by generally any user, subject to regulation requirements. The shared-licensed spectrums are also not exclusive for an operator to use. Traditionally the unlicensed spectrums are not used by cellular networks as it is generally difficult to ensure quality of service (QoS) requirements. Operating on the unlicensed spectrums mainly include wireless local area networks (WLAN), e.g., the Wi-Fi networks. Due to the fact that the licensed spectrum is generally scarce and expensive, utilizing the unlicensed spectrum by the cellular operator may be considered. On high-frequency bands and unlicensed/shared-licensed bands, typically TDD is used, and hence, the channel reciprocity can be exploited for the communications.

In unlicensed spectrum, generally, there is no pre-coordination among multiple nodes operating on the same frequency resources. Thus, a contention-based protocol (CBP) may be used. According to Section 90.7 of Part 90 (paragraph 58) of the United States Federal Communication Commission (FCC), CBP is defined as: CBP — "A protocol that allows multiple users to share the same spectrum by defining the events that must occur when two or more transmitters attempt to simultaneously access the same channel and establishing rules by which a transmitter provides reasonable opportunities for other transmitters to operate. Such a protocol may consist of procedures for initiating new transmissions, procedures for determining the state of the channel (available or unavailable), and procedures for managing retransmissions in the event of a busy channel." The state of a channel being busy may also be referred to as channel being unavailable, channel not clear, channel being occupied, etc., and the state of a channel being idle may also be referred to as channel being available, channel being clear, channel not occupied, etc.

The LBT procedure of IEEE 802.11 (WiFi) is one of the most used CBPs (the LBT procedure of IEEE 802.11 can be found described in, "Wireless LAN medium access control (MAC) and physical layer (PHY) specifications," IEEE Std 802.11-2007 (Revision of IEEE Std 802.11-1999), which is hereby incorporated herein by reference). It is also referred to as the carrier sense multiple access with collision avoidance (CSMA/CA) protocol. Carrier sensing is performed before any transmission attempt, and the transmission is performed only if the carrier is sensed to be idle, otherwise a random backoff time for the next sensing is applied. The sensing is generally done through a CCA procedure to determine if the in -channel power is below a given threshold.

In ETSI EN 301893 V1.7.1, which is hereby incorporated herein by reference, Clause 4.9.2 describes 2 types of Adaptive equipment: Frame Based Equipment and Load Based Equipment. To quote the specification,

"Frame Based Equipment shall comply with the following requirements:

1) Before starting transmissions on an Operating Channel, the equipment shall perform a Clear Channel Assessment (CCA) check using "energy detect". The equipment shall observe the Operating Channel(s) for the duration of the CCA observation time which shall be not less than 20 ps. The CCA observation time used by the equipment shall be declared by the manufacturer. The Operating Channel shall be considered occupied if the energy level in the channel exceeds the threshold corresponding to the power level given in point 5 below. If the equipment finds the Operating Channel(s) to be clear, it may transmit immediately (see point 3 below).

2) If the equipment finds an Operating Channel occupied, it shall not transmit on that channel during the next Fixed Frame Period.

NOTE 1: The equipment is allowed to continue Short Control Signalling Transmissions on this channel providing it complies with the requirements in clause 4-9-2.3-

NOTE 2: For equipment having simultaneous transmissions on multiple (adjacent or non-adjacent) Operating Channels, the equipment is allowed to continue transmissions on other Operating Channels providing the CCA check did not detect any signals on those channels. 3) The total time during which an equipment has transmissions on a given channel without re-evaluating the availability of that channel, is defined as the Channel Occupancy Time. The Channel Occupancy Time shall be in the range 1 ms to to ms and the minimum Idle Period shall be at least 5 % of the Channel Occupancy Time used by the equipment for the current Fixed Frame Period. Towards the end of the Idle Period, the equipment shall perform a new CCA as described in point 1 above.

4) The equipment, upon correct reception of a packet which was intended for this equipment, can skip CCA and immediately (see note 3) proceed with the transmission of management and control frames (e.g. ACK and Block ACK frames). A consecutive sequence of such transmissions by the equipment, without it performing a new CCA, shall not exceed the Maximum Channel Occupancy Time as defined in point 3 above.

NOTE 3: For the purpose of multi-cast, the ACK transmissions (associated with the same data packet) of the individual devices are allowed to take place in a sequence.

5) The energy detection threshold for the CCA shall be proportional to the maximum transmit power (P_H) of the transmitter: for a 23 dBm e.i.r.p. (or EIRP) transmitter the CCA threshold level (TL) shall be equal or lower than -73 dBm/MHz at the input to the receiver (assuming a o dBi receive antenna). For other transmit power levels, the CCA threshold level TL shall be calculated using the formula: TL = -73 dBm/MHz + 23 - PH (assuming a o dBi receive antenna and PH specified in dBm e.i.r.p.)."

"Load based Equipment may implement an LBT based spectrum sharing mechanism based on the Clear Channel Assessment (CCA) mode using "energy detect", as described in IEEE 802.II™-2007 [9], clauses 9 and 17, in IEEE 802.itn™-2009 [to], clauses 9, 11 and 20 providing they comply with the conformance requirements referred to in clause 4.9.3 (see note 1) (all of which are hereby incorporated herein by reference.

NOTE 1: It is intended also to allow a mechanism based on the Clear Channel Assessment (CCA) mode using "energy detect" as described in IEEE 8o2.itac™ [1.2], clauses 8, 9, to and 22 (which are hereby incorporated herein by reference), when this becomes available.

Load Based Equipment not using any of the mechanisms referenced above shall comply with the following minimum set of requirements:

1) Before a transmission or a burst of transmissions on an Operating Channel, the equipment shall perform a Clear Channel Assessment (CCA) check using "energy detect". The equipment shall observe the Operating Channel(s) for the duration of the CCA observation time which shall be not less than 20 ps. The CCA observation time used by the equipment shall be declared by the manufacturer. The Operating Channel shall be considered occupied if the energy level in the channel exceeds the threshold corresponding to the power level given in point 5 below. If the equipment finds the channel to be clear, it may transmit immediately (see point 3 below).

2) If the equipment finds an Operating Channel occupied, it shall not transmit in that channel. The equipment shall perform an Extended CCA check in which the Operating Channel is observed for the duration of a random factor N multiplied by the CCA observation time. N defines the number of clear idle slots resulting in a total Idle Period that need to be observed before initiation of the transmission. The value of N shall be randomly selected in the range i..q every time an Extended CCA is required and the value stored in a counter. The value of q is selected by the manufacturer in the range

4..32. This selected value shall be declared by the manufacturer (see clause 5.3.1 q)). The counter is decremented every time a CCA slot is considered to be "unoccupied". When the counter reaches zero, the equipment may transmit.

NOTE 2: The equipment is allowed to continue Short Control Signalling Transmissions on this channel providing it complies with the requirements in clause 4-9-2.3-

NOTE 3: For equipment having simultaneous transmissions on multiple (adjacent or non-adjacent) operating channels, the equipment is allowed to continue transmissions on other Operating Channels providing the CCA check did not detect any signals on those channels.

3) The total time that an equipment makes use of an Operating Channel is the Maximum Channel Occupancy Time which shall be less than (13/32) x q ms, with q as defined in point 2 above, after which the device shall perform the Extended CCA described in point 2 above.

4) The equipment, upon correct reception of a packet which was intended for this equipment, can skip CCA and immediately (see note 4) proceed with the transmission of management and control frames (e.g. ACK and Block ACK frames). A consecutive sequence of transmissions by the equipment, without it performing a new CCA, shall not exceed the Maximum Channel Occupancy Time as defined in point 3 above.

NOTE 4: For the purpose of multi-cast, the ACK transmissions (associated with the same data packet) of the individual devices are allowed to take place in a sequence.

5) The energy detection threshold for the CCA shall be proportional to the maximum transmit power (P_H) of the transmitter: for a 23 dBm e.i.r.p. transmitter the CCA threshold level (TL) shall be equal or lower than -73 dBm/MHz at the input to the receiver (assuming a o dBi receive antenna). For other transmit power levels, the CCA threshold level TL shall be calculated using the formula: TL = -73 dBm/MHz + 23 - P_H (assuming a o dBi receive antenna and PH specified in dBm e.i.r.p.)."

Figures 5A and 5B are block diagrams of embodiments of systems 500 and 550 for analog beamsteering plus digital beamforming. System 500 in Figure 5A includes a baseband component 502 for digital processing, a plurality of RF chain components 504, a plurality of phase shifters 506, a plurality of combiners 308, and a plurality of antennas 510. The diagram may be used for transmission or receiving. For simplicity, the diagram is described for transmission; receiving may be understood similarly.

Each RF chain 504 receives a weighting factor (or weight, p , ..., p_mas shown in Figure 5A) from the baseband component 502. The collection of the weighting factors form the digital precoding vector, precoding matrix, beamforming vector, or beamforming matrix for the transmission. For example, a precoding vector may be [ p , ..., p_m ] - When multiple layers/streams are transmitted, a precoding matrix may be used by the baseband unit to generate the weighting factors, which each column (or row) of the matrix is applied to a layer/stream of the transmission. Each RF chain 504 is coupled to a plurality of phase shifters 506. The phase shifters may, theoretically, apply any phase shift values, but generally in practice, only a few possible phase shift values, e.g., 16 or 32 values. Each RF chain 504 generates a narrow beam 512 oriented in a direction determined by the settings on the phase shifters 506 and combiners 508. If the phase shifters can apply any phase shift values, the beam may point to any direction, but if only a few phase shift values can be used, the beam may be one of few possibilities (e.g., in the figure, the solid narrow beam is selected by setting a specific phase shift value in the RF chain, and the beam is among all the possible narrow beams shown as solid and dotted beams corresponding to all the possible phase shift values).

Each RF chain selects such a narrow beam, and all such narrow beams selected by all the RF chains will be further superposed. How the superposition is done is based on the digital weighting factors. The factor can make a beam from a RF chain stronger or weaker, and therefore, a different set of the factors can generate different superpositions in the spatial domain; in the figure, a particular beam 514 is illustrated. In other words, by selecting different digital weighting factors, different beam 514 can be generated. The digital operations may generally refer to as (digital) beamforming or precoding, and the analog operations as (analog) beamsteering or phase shifting, but sometimes there is no clear distinctions. System 550 in Figure 5B is similar to system 500 in Figure 5A except that corresponding combiners 508 in each RF chain 502 are connected to one another.

Figure 6 illustrates a diagram 600 of an example timing for FBE. A first trace 602 represents CCA intervals performed by a communicating device, and a second trace 604 represents transmission intervals performed by the communicating device. The communicating device performs a CCA during CCA interval 606, where CCA interval may be greater than or equal to 20 microseconds in duration with a CCA threshold of -73 dBm/MHz + (23-maxEIRP), where maxEIRP is the maximum equivalent isotropic radiated power (a measure of transmitted power). If, during CCA interval 606, communicating device determines that the channel is idle, the communicating device makes a transmission during a COT (with a duration ranging from 1 to to milliseconds). The COT occurs during a portion 608 of the frame period. A remainder of the frame period, referred to as idle period 610, is greater than or equal to 5 percent of portion 608 and 50 microseconds. During idle period 610, communicating devices can perform channel sensing in CCA interval 612.

Figure 7 illustrates a flow diagram of example operations 700 occurring in carrier sensing. Operations 700 may occur in a communicating device performing carrier sensing to obtain access to the channel.

Operations 700 begin with a communication controller receiving a waveform signal from a UE (block 702). The communication system processes the signal and generates a decision variable X (block 704). The signal processing here, in general, is performed in the digital domain which is normally performed in the baseband, and may include: sampling, analog-to-digital (A/D) conversion, receiver's digital combining with precoding weighting, etc. The decision variable, X, is used to determine whether the channel is idle or busy. The communication controller determines whether the decision variable X is less than a threshold, T (block 706). The threshold T may be a standardized value, or derived from a standard or some regulation, which may be device type specific, spatial specific, etc. The threshold T may also be allowed to change within a specified range according to the traffic loads, interference conditions, etc. If the communication controller determines that the value of the decision variable, X, is less than the threshold, T, operations 700 proceed to block 708 where the communication controller determines that the carrier channel is idle, after which, operations 700 end. If, at block 506, the communication controller determines that the value of the decision variable, X, is not less than the threshold, T, then operations 700 proceed to block 710 where the communication controller determines that the carrier channel is busy, after which, operations 700 end.

Figure 8 illustrates a flow diagram of example operations 800 occurring in a general LBT mechanism. Operations 800 may occur in a communicating device performing LBT.

Operations 800 begin with the communication controller assembling a frame (block 802). The communication controller performs carrier sensing, such as described above with reference to Figure 7, to determine if the channel is idle (block 804). If, at block 804, the communication controller determines that the channel is not idle, but is busy, then operations 800 proceed to block 806 where the communication controller refrains from transmitting the frame and waits for a random backoff timer to expire, after which, operations 800 return to block 804 to continue performing carrier sensing. If, at block 804, the communication controller determines that the channel is idle, then operations 800 proceed to block 808 where the communication controller transmits the frame, after which, operations 800 end.

WiFi is a widely present example of the application of the LBT mechanism. WiFi uses IEEE 802.11 standards technologies such as the air interface (including physical and MAC layer). In IEEE 802.11, the communication channel is shared by stations under a mechanism called distributed channel access with a function referred to as a distributed coordination function (DCF), which uses CSMA/CA. The DCF uses both physical and virtual carrier sense functions to determine the state of the medium. The physical carrier sense resides in the PHY and uses energy detection and preamble detection with frame length deferral to determine when the medium is busy. The virtual carrier sense resides in the media access control (MAC) layer and uses reservation information carried in the Duration field of MAC headers to announce the impeding use of the wireless channel.

The virtual carrier sense mechanism is referred to as the network allocation vector (NAV). The wireless channel is determined to be idle only when both the physical and virtual carrier sense mechanisms indicate it to be idle.

Figure 9 illustrates a diagram 900 of the channel access procedure of WiFi compliant communication systems. A station with a data frame for transmission first performs a CCA by sensing the wireless channel for a fixed duration, i.e., the DCF inter-frame space (DIFS). As an example, STA 1 senses the wireless channel for DIFS 902. If the wireless channel is busy, the station waits until the channel becomes idle, defers for another DIFS 904, and then waits for a further random backoff period 906 (by setting the backoff timer with an integer number of slots). The backoff timer decreases by one for every idle slot and freezes when the channel is sensed busy 908. When the backoff timer reaches zero, the station starts data transmission 910.

To meet the regulatory requirements of operating in the unlicensed spectrum and to co exist with other radio access technologies (RATs) such as Wi-Fi, the transmissions on the unlicensed spectrum cannot be continuous or persistent in time. Rather, on/off, or opportunistic transmissions and measurements on demand may be adopted.

In addition, for operations in high-frequency bands, especially in the bands from 28GHz to 60GHz (commonly referred to as belonging to the mmWave regime), there are significantly different propagation characteristics from microwave bands (generally below 6GHz). For example, mmWaves experiences higher pathloss over distance than microwaves do. Therefore, high-frequency bands are more suitable for small cell operations than macro cell operations, and they generally rely on beamforming with a large number of antennas (e.g. >16, and sometimes maybe even a few hundred or more) for effective transmissions.

At high operating frequencies, the wavelengths, antenna sizes, and antenna spacing can all be smaller than those at low operating frequency, thus making it feasible to equip a node with a large number of antennas. As a result, the beams formed by the large number of antennas can be very narrow, for example, with beamwidth of to degrees or even less. In sharp contrast, in traditional wireless communications, beamwidth is generally much wider, such as on the order tens of degrees. Figure 10A illustrates a diagram 1000 of a wide beam pattern 1002. Wide beam pattern 1002 may be achieved with a small number of antennas in a low operating frequency. Figure 10B illustrates a diagram 1050 of a narrow beam pattern 1052. Narrow beam pattern 1052 maybe achieved with a large number of antennas in high operating frequency.

In general, it is regarded that narrow beams are a major new feature of mmWaves. As a general rule of thumb, the beamforming gain achievable by massive MIMO can be roughly estimated by N x K, where N is the number of transmit antennas and K the receive antennas. This is because the 2-norm of the channel matrix H scales roughly according to ( N x K)^1/2, and therefore if the precoding vector by the transmitting node isp, and the combining vector by the receiving node is w, then the composite channel is w’Hp, and by properly selecting w andp, the composite channel gain in energy can attain NxK, much higher than the case with fewer antennas being used.

In 3GPP NR, beam management consists of beam measurement and beam indication. An access node transmits downlink reference signal with downlink beam sweeping toward various spatial directions and configures a UE to perform measurements on these transmitted beams. The UE performs Layer t reference signal received power (Lt-RSRP) or Li signal to interference plus noise ratio (Lt-SINR) measurements on each of the transmit beam and reports the one or several downlink reference signal resource indicators corresponding to the highest Lt-RSRP or Lt-SINR values. The UE also stores the receive spatial parameters which are utilized to form receive beam used in receiving the corresponding beamformed downlink reference signal.

The access node transmits downlink control and data signals, e.g. physical downlink control channel (PDCCH) or physical downlink shared channel (PDSCH), to the UE, either through radio resource control (RRC) static configuration, media access control (MAC) control element (CE) semi-static configure, or downlink control information (DCI) dynamic signaling. The access node indicates to the UE to receive the intended downlink transmission with the receive beam which is used in receiving the downlink reference signal in the beam measurement. The reference signal of the downlink transmission is said to be quasi-collocated (QCLed) in type D (i.e., in a spatial receive filter) to the downlink reference signal for measurement such that they have the same receive spatial parameters.

The access node schedules the UE for uplink physical uplink control channel (PUCCH) transmission, either through RRC static configuration or MAC CE semi-static configuration. The access node indicates to the UE to transmit the scheduled uplink transmission with the transmit beam which is in spatial relation to the downlink reference signal in the measurement. The transmit beam is the correspondence beam of the receive beam used in receiving the indicated downlink reference signal in the measurement.

The access node schedules the UE for uplink physical uplink shared channel (PUSCH) transmission, either through RRC static configuration or MAC CE semi-static configuration. The access node indicates to UE to transmit the scheduled uplink transmission with the transmit beam which is used in the uplink sounding reference signal (SRS) sweeping.

As stated above, directional transmissions are used for high frequency bands (e.g. Frequency Range 2 (FR2) in 3GPP) in order to improve coverage of the signals or channels. Therefore, directional sensing (i.e., sensing with spatial receiver filter or received beamformer or combiner) can be used in place of omni-sensing (non-directional sensing). Though this is conceptually straightforward, a few problems need to be solved. In a cellular system, for example 3GPP NR, a transmit-receive point (TRP) or access node (e.g., gNB, eNB, etc.) generally communicates with multiple UEs or devices with different locations within its coverage area. This demands the transmissions from (to) the TRP to (from) these UEs use different transmission or reception beamforming (or precoding, spatial transmission or reception filter). The transmissions beamforming may differ in terms of beamwidth, beamforming gain, transmission power, spatial direction, or combination of them. Even for channels or signals to (from) the same UE, different transmission or reception beamforming may be used considering the different performance targets, for example, reliability, coverage, broadcast versus unicast versus groupcast, etc.

In addition, the COT of a channel of a TRP is relatively long compared to that of a slot or transmission time of a channel or a signal. In addition, the bandwidth of shared spectrum channel can be quite large, for example, a few hundred MHz or even over 1 GHz, where a transmission to a single UE may not be able (or need) to fully utilize the bandwidth. Therefore, the multiplexing of multiple transmissions (of channels and signals) for one or multiple UEs in time, frequency, spatial domain, or a combination thereof, are needed within a COT after the TRP successfully obtains the channel after channel sensing or CCA.

Hence the issues are as follows:

As multiple channels or signals to and from one or more UEs are multiplexed within the channel bandwidth and the COT, multiple transmission or reception beams are utilized. On the other hand, the TRP senses the channel occupancy over its whole coverage area which means a single beam with wide(r) -beamwidth may be used for channel sensing. Therefore, the channel sensing beam is not the same as the beam(s) used for transmission of channels and signals within the COT after the channel sensing. The angular spread (including the spatial direction and the spread of the beam) of the channel sensing beam should generally cover the angular spread of all the transmission beams used for transmission within the COT after the channel sensing. However, as the shape of a beam is usually irregular, the exact angular spread of a beam and angular spread relationship between the beams may be difficult to define and quantize.

In the case that the same beam is used for sensing and transmission, the threshold for sensing, for example, energy sensing or preamble/signal sensing, can be defined independent of the actual beamwidth (or beamforming gain or EIRP). In the case where sensing beam are different from that of the beam(s) for transmissions, what should be the sensing threshold?

Furthermore, multiple transmission beams are used within a COT after the TRP obtains access to the channel in both frequency domain as well as spatial/angular domain. These transmission beams will be multiplexed within the channel bandwidth and the COT in FDM, TDM, and/or SDM, as a result of channel and signal multiplexing. For channel bandwidth occupancy, regulation requires that the transmissions at any time instance occupy a sufficiently large portion (for example, 8o%) of the channel bandwidth. Over the COT, the time gap between transmissions may be allowed if the duration of the gap is sufficiently small, for example, less than 5 microseconds. In term of spatial domain, how should the transmission beam(s) occupy the angular spread of the sensing beam throughout the channel bandwidth and COT?

In addition, with directional sensing at the TRP that obtains a channel access with certain spatial direction and/or angular spread, when the TRP shares the channel COT with a device/UE, the UE may transmit beamformed channels and signals to the TRP. The UE’s beamformed transmission should generally fall within the TRP sensing direction/ angular spread. However, as the TRP and the UE(s) are not collocated, and the transmit beam of TRP and the transmit beam of the UE(s) are oriented towards each other (i.e., in opposite direction) instead of aligned, UE behavior needs to be specified.

When directional sensing and transmission is performed using beamforming, the CCA threshold is adapted with a difference between the sensing beamform and the transmit beamform. In ETSI EN 302567V020200, the CCA energy detection (ED) threshold adapts based on the EIRP at the transmitter as follows:

ED = -80 dBm + iolog _o(Operating channel BW (in MHz) + iolog _o(Pmax/Pout), where Pout is the RF output power (EIRP) and Pmax is the RF output power limit.

However, if the transmit power is smaller the ED increases correspondingly.

Figure 11A illustrates a diagram 1100 of the CCA threshold defining a zone or volume around a device. As shown in Figure 1100, the CCA threshold used during the sensing phase defines a zone (or volume) 1104 or 1106 around transmitting device 1102 as transmitting device 1102 performs sensing (e.g., executes LBT), where there are no transmitters with the received power at the transmitting device 1102 above the CCA threshold. The zone 1104 (which is free of transmitters) corresponds to the sensing range (or sensing area). At the same time, zone 1104 may represent a protected zone from transmitting device 1102 transmission in the sense that transmitting device 1102 will not transmit if a transmitting device 1108 makes a transmission within zone 1104 and transmitting device 1102 would not transmit to prevent interference to transmitting device 1108 or other receiving devices in the protected zone. In general, a larger CCA threshold would result in a smaller protected zone. As shown in Figure tiA, zone 1104 corresponds to a larger CCA threshold than zone 1106.

A decrease in Pout, i.e., the increase in the ED threshold, permits transmissions in the presence of stronger interferers, which means a more aggressive channel access. Resulting in the protected range of other ongoing transmissions being reduced. In other words, the less potential impact on the ongoing transmissions the more increased ED, i.e., the more aggressive channel access. A different interpretation is that a decrease in transmit power Pout corresponds to an decrease in sensing (protected) range, equivalent to an increased ED threshold.

For instance, if an interferer (I) 1108 uses a max power of 40 dBm at the border of the sensing range there is at least 87 dB in pathloss from the interferer to the transmitting device (TX) 1102 necessary to sense the channel empty. Reciprocally, if the transmitting device 1102 uses 4odBm the received power at interferer 1108 is less than -47 dBm so both can proceed and transmit. If transmitting device 1102 uses only 2odBm, the ED is - 27dBm, which translates in 67dB pathloss separation from interferer 1108 that uses 40dBm, and that is a reduced sensing range. The received power from transmitting device 1102 at interferer 1108 will be -47dBm. In other words, the ED CCA threshold adapts in such way that maintain the same interference (-47dBm) at the interferer that uses max transmit power (4odBm).

In the example embodiments, it is assumed that the transmit antenna beam (pattern) is a spatial subset of the sensing antenna beam (pattern). This means that the transmit antenna beam covers at least a portion of the sensing antenna beam. The above equation and analysis, however, does not depend on the directionality of CCA. If a directional antenna is used for channel sensing, the received power at the antenna port is increased due to antenna gain with respect to an isotropic antenna. For instance, an antenna of 45 degrees beamwidth directionality corresponds to 9 dB increase in antenna gain with respect to an isotropic (omni) antenna of 360 degrees. Under the assumption that the interferer 1108 uses a 4odBm omni antenna, the pathloss tolerated to interferer 1108 is again -87dB for transmitting device 1102 using max 4odBm EIRP to generate -47dBm at interferer 1108. However, when sensing at transmitting device 1102, the received power that corresponds to 87dB pathloss, 4odBm from interferer 1108, and 9dB antenna gain at transmitter 1102, is be -37dBm. This simple link budged indicates that the CCA ED threshold level needs to increase with antenna gain used for channel sensing. This may be expressed as:

EDt = EDo + (Ant_sens_gaint - Ant_sens_gaino), where EDo is the CCA threshold corresponds to Ant_sens_gaino (for instance, an isotropic antenna (odBi)), while EDt corresponds to a directional sensing antenna gain Ant_sens_gaint. On the other hand, with directional sensing antenna gain, and assuming the same directional antenna is used for transmission, the sensing range to prevent interfering the other device needs to increase accordingly. Therefore, the sensing threshold (EDt) remains unchanged despite the sensing antenna gain.

In general, the sensing (or energy detection) threshold ED is adapted according to the difference between the antenna beam used for sensing and one or more antenna beams used for transmission. This may be expressed as:

EDt = EDo - F(sensing antenna beam, transmission antenna beam(s)), where F(sensing antenna beam, transmission antenna beam(s)) is a function of the sensing antenna beam and the transmission antenna beam(s) at the TRP or the transmitting device.

In an embodiment, the sensing threshold ED is adapted according to the difference between the radiated powers of the antenna beam used for sensing and one or more antenna beams used for transmission. This may be expressed as:

EDt = EDo - (EIRP_max_TX - EIRP_sense_2TX).

Where EIRP_max_TX correspond to the max EIRP used for transmission, and EIRP_sense_2TX correspond to an equivalent EIRP for the case when the sensing antenna is used for transmission with the same maximum power at the antenna port. Therefore, this formula allows to adapt the ED when the sensing antenna gain (directionality) and transmit antenna gain (directionality) are different.

For discussion purposes, the following terms are defined:

Equivalent isotropic sensitivity (EIS): sensitivity for an isotropic directivity device equivalent to the sensitivity of the discussed device exposed to an incoming wave from a defined angle of arrival (AoA).

Receive beam peak direction: direction where the maximum total component of incoming wave RSRP and thus best total component of EIS is found.

The reference sensitivity CCA power level CCA REFSENS is defined as the EIS level at the center of the quiet zone in the receive beam peak direction, assuming a o dBi reference antenna located at the center of the quiet zone (as defined in 3GPP TS 38.101-2).

With the above definitions defining an ED CCA threshold, including adaptation with antenna gain, is equivalent with defining a fixed value for the reference sensitivity CCA power level. Therefore, LBT and channel access can be reformulated in terms of CCA REFSENS.

As an example,

CCA REFSENS=-47dBm.

This reformulation will make unnecessary any ED adaptation with beam gain (antenna directionality). In the above analysis, a tacit assumption made was that the transmit power is the maximum EIRP power. If this is not the case, i.e., a smaller EIRP power for transmission is used, the following CCA REFSENS adaptation is necessary:

CCA REFSENSt= CCA REFSENSo + (Pmax [EIRP] -Pout [EIRP]).

Another possible way to express the change of the ED CCA threshold with antenna directivity is presented below.

Figure tiB illustrates a diagram 1150 of beam-based sensing threshold where the sensing threshold is adapted as a ratio between the beamforming gain (or EIRP when the same beam is used for transmission) of the sensing beam and the maximum beamforming gain (or EIRP) of the transmission beam(s). Region 1152 represents the directional sensing coverage area with the assumption of the beam used for sensing is also used for transmission. Region 1154 represents the directional sensing coverage area with an adapted threshold. Region 1156 represents the transmission beam with EIRPi and region 1158 represents the transmission beam with EIRP2.

As example, assume the ED threshold for sensing is X_i (dBm) when the sensing beam is substantially the same as the transmission beam. The ED threshold for sensing when sensing beam is different from those for transmissions is expressible as X_2 = X_i - (EIRP_max_tx - EIRP_sense_2tx), where EIRP_sense_2tx is the EIRP when the TRP transmits using the sensing receive beam with a certain transmission power level (for example, its maximum transmission power), and EIRP_max_tx is the maximum (used or allowed or intended) EIRP of the TRP transmission(s).

A justification is that when transmission beamforming gain can be larger than that of the sensing beam, the coverage of the transmission goes beyond that of what is achievable when the sensing beam is used for transmission, and the difference is (EIRP_max_tx - EIRP_sense_2tx) dB. Therefore, the sensing threshold needs to be reduced (i.e., more sensitive) accordingly to sense potential usage of the channel in the extended coverage area. Here the sensing (or energy detection) is performed after receive beamforming. The sensing (or energy detection) threshold is adapted according to a difference between the sensing beam and one or more transmission beam(s) which, in general, can be express as

X_2 = X_i - F(sensing beam, transmission beam(s)), where F(sensing beam, transmission beam(s)) is a function of the sensing beam and the transmission beam(s) at the TRP or a device.

The difference between the sensing beam and the one or more transmission beam(s) may be measured by difference of their EIRPs. Because the sensing beam is a receive beam, the EIRP of a sensing beam is the EIRP of transmission using the sensing beam and certain transmission power level. Then the sensing (or energy detection) threshold decreases as (EIRP_tx -EIRP_sense_2tx) increases. Consequently, when the transmission beam EIRP increases, the sensing threshold decreases, and hence becomes more sensitive so that the sensing range/ area extends. As multiple transmission beams may be used during a COT after sensing/ CCA, instead of measuring the difference between the EIRP of the sensing beam and the EIRP of a specific transmission beam, the difference between the EIRP of the sensing beam and the maximum EIRP of the beams that may be used for transmission during the COT. Therefore,

X_2 = X_i - (EIRP_max_tx - EIRP_sense_2tx).

Alternatively, the difference between the sensing beam and one or more transmission beam(s) may be measured by the difference of their beamwidths. In a radio antenna pattern, the half power beamwidth is the angle between the half-power (-3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe.

The narrower the beam-width, the farther reaching the beam and the higher beamforming gain. Then the sensing (or energy detection) threshold decreases as io*logio(Beamwidth_sense/Beamwidth_tx) increases. Consequently, when the transmission beamwidth decreases, the sensing threshold decreases, and hence becomes more sensitive such that the sensing range/area extends. As multiple transmission beams may be used during a COT after sensing/ CCA, instead of measure the difference between the beamwidth of the sensing beam and the beamwidth of a specific transmission beam, the difference between the beamwidth of the sensing beam and the minimum beamwidth of the beams (denoted as Beamwidth_min_tx) that may be used for transmission during the COT. Therefore,

X_2 = X_i - io*logio(Beamwidth_sense/Beamwidth_min_tx).

Yet another alternative is that the difference between the sensing beam and one or more transmission beam(s) may be measured by the difference of their beamforming gains. In a radio antenna pattern, the half power beamwidth is the angle between the half-power (- 3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe. The narrower the beamwidth, the farther reaching the beam and the higher beamforming gain. And then the sensing (or energy detection) threshold decreases as (Gain_BF _tx - Gain_BF_sense) increases. Consequently, when the transmission beamforming gain increases, the sensing threshold decreases, and hence becomes more sensitive such that the sensing range/area extends. As multiple transmission beams may be used during a COT after sensing/ CCA, instead of measure the difference between the beamforming gain of the sensing beam and the beamforming gain of a specific transmission beam, the difference between the beamforming gain of the sensing beam and the maximum beamforming gain of the beams (denoted as G_BF_max_tx) that may be used for transmission during the COT. Therefore,

X_2 = X_i - (G_BF_max_tx (dB) - G_BF_sense (dB)).

The sensing threshold does not necessarily depend on (or vary with) the actual EIRP/beamforming gain /beamwidth for sensing beam if the transmission is using the same beam as for sensing. Figure ltC illustrates a diagram 1170 of a situation when the beam used for sensing is also used for transmitting. Region 1172 represents the coverage area of omni-sensing, and region 1174 represents the coverage area of directional sensing.

For discussion purposes, assume that the energy detection threshold for omni-directional sensing is X_o (dBm). When directional sensing is used, the sensing range (or distance) increases at the same time the sensing angular spread (or beamwidth) reduces. If the TRP transmits using the same beam (omni- or directional-) as the one for sensing, to avoid interference to and from another device (of the same or different RAT), the sensitivity of the sensing can remain the same. Directional sensing may have other effects to the actual coverage area of the TRP, chance of inference, hidden nodes, exposed nodes, etc. which may render the need to adjust sensing and LBT parameters.

As related to receive or sensing beam and transmit multi-beam correspondence, the following are defined in 3GPP TS 38.101-2, which is hereby incorporated herein by reference:

- Beam correspondence is the ability of the UE to select a suitable beam for UL transmission based on DL measurements with or without relying on UL beam sweeping.

- Beam correspondence tolerance DEI RPBC = EIRP2 - EIRPi, where: EIRPi = measured total EIRP based on the beam the UE chooses autonomously (corresponding beam) to transmit in the direction of the incoming DL signal, which is based on beam correspondence without relying on UL beam sweeping, and EIRP2= measured total EIRP based on the beam yielding highest EIRP in a given direction, which is based on beam correspondence with relying on UL beam sweeping.

- Link angles (LA) are the ones corresponding to the top Nth percentile of the EIRP2 measurement over the whole sphere, where the value of N is according to the test point of EIRP spherical coverage requirement for power class 3, i.e. N = 50.

In the NR-U 60GHz operation, directional LBT and directional transmission is expected as a way to cope with high pathloss. Sensing during directional LBT, transmit and receive operation will possible use multiple beams of different beamwidth and directionality. It is very important that the sensing for instance prior to COT to cover the transmit receive directions and ranges in order to avoid interference to and from other RAT communications (such WiFi). The beam correspondence defined above is for a UE with single beam.

According to an example embodiment, an extension of beam correspondence for multiple beams as well as for sensing to transmit sets of beams for both access node and UE is provided. The basic idea is that the sensing space should be as close as possible to transmit/ receive space, for instance, expressed in terms of spherical coverage as discussed below. The beam correspondence tolerance definition uses two EIRPs for two possible selection of uplink beams, without and with uplink beam sweeping. Where the beam selected without uplink beam sweeping is selected based on downlink incoming signal direction, for example.

A receive-to-transmit (RX2TX) beam spherical coverage (SC) is defined as the spherical coverage obtained when a set of receive (RX) beams is used as a set of transmit (TX) beams. For instance, in directional sensing, the set of all beams used for sensing will generate a RX2TX SC when the sensing beams are used as transmit beams (referred to herein as Sense RX2TX SC). Similarly, when the set of the receive beams are used as transmit beams another RX2TX SC is obtained (referred to herein as Receive RX2TX SC). The goal of sensing is that Sense RX2TX SC >= Receive RX2TX SC = TX SC, where TX SC represent the spherical coverage of transmit beams set.

Using the definitions provided herein, it is possible to define RX2TX beam set correspondence tolerance as DEI RPBC = EIRP2 - EIRPi, where EIRPi and EIRP2 represent the EIRP corresponding to RX2TX SCt and RX2TX SC2. With such a RX2TX beam set correspondence tolerance, it is possible to quantify and measure the discrepancies between the sensing, receiving, and respectively, transmitting during a COT. For instance, a requirement to have a larger sensing coverage than transmit coverage is expressed as the correspondence tolerance between Sense RX2TX SC and TX SC to be positive, i.e.,

EIRP Sense RX2TX SC - EIRP TX SC > o.

Using the LA defined above, which is related to the top N percentile of EIRP measured on the whole sphere, it is possible to impose additional constraints between the sense LA and the transmit LA to insure that the transmit directions belong to the sensing directions. For instance,

-d < LA Sense RX2TX SC - LA TX SC < +d, where LA Sense RX2TX SC represents the LA of Sense RX2TX SC and LA TX SC is the link angle of transmit SC.

Figure 12 illustrates a flow diagram of operations 1200 occurring in a transmitting device making a transmission in unlicensed spectrum utilizing beamformed LBT.

Operations 1200 begin the transmitting device preparing to perform a transmission in a channel (block 1202). Preparing to perform a transmission may include encoding the data bits, performing rate matching, and so forth. The transmitting device determines possible transmit beam(s) (block 1204). The transmitting device may determine the possible transmit beam(s) in accordance with the location of the receiving device. The transmitting device may determine the possible transmit beam(s) in accordance with an angle of arrival (AoA) of a transmission received from the receiving device, an angle of departure (AoD) of a transmission previously sent to the receiving device, and so forth. The transmitting device determines a sensing beam and a sensing spatial filter (block 1206). The sensing beam and the sensing spatial filter may be determined in accordance with the location of the receiving device. The transmitting device may determine the sensing beam and the sensing spatial filter in accordance with the AoA of a transmission received from the receiving device, the AoD of a transmission previously sent to the receiving device, and so forth. More than one sensing beam and sensing spatial filters may be determined by the transmitting device.

The transmitting device performs sensing (block 1208). The channel sensing performed by the transmitting device may occur during a sensing slot using the sensing beam and the sensing spatial filter determined by the transmitting device. The sensing results in a sensing measurement. The transmitting device determines a sensing threshold (block 1210). The sensing threshold may be determined in accordance with the sensing beam and the transmit beam(s). The determination of the sensing threshold may be in accordance with the example embodiments presented herein.

The transmitting device compares the sensing measurement with the sensing threshold (block 1212). The transmitting device checks to determine if the sensing measurement meets the sensing threshold, for example. If the sensing measurement is greater than or equal to (or greater than) the sensing threshold, the transmitting device determines that the channel is busy and does not make a transmission (block 1214). The transmitting device does not make a transmission using the transmission beam(s) in the channel for a specified nonzero time duration, for example. The nonzero time duration may be specified by a technical standard or an operator of the communication system. Alternatively, the transmitting device and the receiving device may collaborate to specify the nonzero time duration.

If the sensing measurement is less than (or less than and equal to) the sensing threshold, the transmitting device determines that the channel is clear (block 1216). The transmitting device makes the transmission (block 1218). The transmitting device makes the transmission using the transmission beam(s). The transmitting device also starts a COT and a COT timer. The transmitting device completes the transmission within the COT (before the COT timer expires) or stops the transmission when the COT timer expires (block 1220). The transmitting device also ends the COT at the expiration of the COT timer. During the COT, the transmitting device may also make additional transmissions to the receiving device or receive transmissions from the receiving device.

Furthermore, multiple transmission beams are used within a COT after the TRP obtains access to the channel in both frequency domain as well as spatial or angular domains. These transmission beams will be multiplexed within the channel bandwidth and the COT in frequency domain (using frequency division multiplexing (FDM)), time domain (using time domain multiplexing (TDM)), and/or spatial domain (using spatial domain multiplexing (SDM)) because of channel and signal multiplexing. The COT can be in the range of a few milliseconds (ms), for example up to 9 or to ms. In the case of high frequency range, for example, 60 GHz carrier frequency, a few milliseconds COT consists of tens or even over one hundred transmission slots since larger subcarrier spacing (SCS) will be used to support channel bandwidth and mitigate severe phase noise. Each sensing or LBT channel can be of a bandwidth on the order of a few hundred MHz to even over one GHz. It is then clear that multiplexing of multiple physical layer channels and signals for one or more UEs is needed over the COT and within the LBT channel. These physical layer channels and signals include primary synchronization signal (PSS), secondary synchronization signal (SSS), physical broadcast channel (PBCH) and its associated demodulation reference signal (DMRS) (Figure 13A illustrates a diagram 1300 of a synchronization signal (SS) burst. As shown in Figure 13A, a SS (e.g., PSS 1302 and SSS 1304) is multiplexed with PDSCH around it), PDSCH and its associated DMRS and phase tracking reference signal (PT-RS), PDCCH and its associated DMRS (Figure 13B illustrates a diagram 1350 of signals multiplexed for more than one UE. As shown in Figure 13B, PDCCH 1352 is multiplexed with data for UEi (box 1354) and data for UE2 (box 1356)), and channel state information reference signal (CSI-RS) that further includes signals used for CSI acquisition, beam management, and tracking reference signal (TRS) (Figure 14 illustrates a diagram 1400 of non-zero power (NZP) CSI-RS. The NZP CSI-RS may be used for channel estimation, interference management, and so on. The NZP CSI-RS may be multiplexed with a PDSCH for one or more UEs.

These downlink channels and signals are transmitted using beamforming for high frequency bands. The beams used for these channels and signals can be semi-statically configured, such as for the PDCCH per CORESET via type-D QCL (i.e., quasi-collocation in term of spatial receiver filter) in a transmission configuration indication (TCI) state, or dynamically indicated via TCI in downlink control information (DCI) such as in the case of the PDSCH. Beam sweeping may be employed to sweep a set of narrower beams over a wider angular direction for beam management as in the case of SS or PBCH blocks or beam management CSI-RS resources. It is clear then that multiple beams of various spatial directions, beamforming gains, and beam-widths or shapes will be multiplexed within the COT and the LBT channel after the TRP obtains access to the channel.

If the TRP shares its COT with served UEs in a TDM manner, uplink channels and signals will also be multiplexed which include PUSCH and its associated DMRS and PT- RS, PUCCH and its associated DMRS, PRACH signal, and SRS. Figure 15 illustrates a diagram 1500 of PDSCH or PUCCH multiplexing, as well as PUCCH, PUSCH, or DMRS multiplexing. Sub-diagram 1502 illustrates the multiplexing of PDSCH 1504 and PUCCH 1506 in a situation with short PUCCH (either 1 or 2 symbols). Sub-diagram 1510 illustrates the multiplexing of PUSCH 1512 and DMRS 1514 in long duration PUCCH (e.g., 12 symbol PUCCH).

For channel bandwidth occupancy, regulation requires that the transmissions at any time instance occupy at least 70% of the channel bandwidth. Over the COT, a time gap between transmissions may be allowed if the duration of the gap is sufficiently small, for example, less than a few microseconds. In the spatial domain, the transmission beam(s) should also sufficiently occupy the sensing area (in terms of both angular spread and distance range of the sensing beam) throughout the channel bandwidth and COT, for example.

Figure 16 illustrates a diagram 1600 of a set of transmission beams covering the entirety of a sensing coverage area. Diagram 1600 displays a sensing coverage area 1602 and three transmission beams (beam 1 (Bt) 1608, beam 2 (B2) 1606, and beam 3 (B3) 1608)). The three transmission beams cover the entirety of sensing coverage area 1602.

Figure 17 illustrates a table 1700 of a first example multiplexing of transmission beams in time and frequency during a COT. The multiplexing occurs within the LBT channel bandwidth. In Figure 17, Ft, F2, ..., and F_N each denotes a subset of frequency resources, such as REs, PRBs, subbands, resource block groups (RBGs), etc., of the whole LBE channel bandwidth, while Ti, T2, ..., and T_L denotes a set of time resources, such as OFDM symbols, slots, mini-slots, subframe, or any equal or non-equal durations that are non-overlapping within the COT while filling up the COT. For each time and frequency resource pair, for example, {Ti, Ft} which can be a set of PRBs over several slots (or OFDM symbols), a beam is used to transmit a channel or signal.

As shown in table 1700, transmission beams are time multiplexed where, at each time, a beam (or a subset of beams) is used while multiple beams are used for transmission across the COT and these multiple beams together may cover the whole sensing area. As an example, a single beam, for example, Bi, is used for transmissions throughout the LBT channel bandwidth and during part of COT (or even during the whole COT). However, Bt has narrower beam-width than that of the sensing beam and hence does not cover the whole sensing area. In such as case, the TRP only utilizes a part of the channel that it has obtained in term of spatial domain. This can be problematic. On the one hand, obtaining a wider spatial channel than what the TRP actually uses reduces its chance to successfully access the channel.

Figure 18 illustrates a diagram 1800 of an interaction of a transmission over a transmission beam and a sensing coverage area of another device. As shown in Figure 18, during a time (e.g., time T2), only transmission beam Bt 1804 is used for transmissions while another device senses the channel with its sensing coverage area 1806 that overlaps with sensing coverage area 1802 of the TRP, but not overlaps with transmission beam Bt 1804. This other device will sense the channel as being idle and start transmitting. If the TRP later, for example in T3, transmits using another beam, for example B2 (e.g., transmission beam B21606 of Figure 16), there will be collision and interference between the TRP and the other device. Therefore, in this case, after the TRP has not transmitted in certain beam direction and angular spread (for example that of transmission beam B2) for a period of time longer than a certain time duration, the TRP needs to sense the channel at (or including) the beam direction and angular spread (for example that of transmission beam B2) before transmit at the beam direction and within the angular spread.

In general, this situation can occur, if during a time interval that is long enough to perform a type of LBT / sensing, the set of beams used for transmission(s) by the TRP do not jointly cover the whole sensing area of the sensing beam (and its associated sensing threshold). To prevent this from happening, the time duration (or a gap) should be sufficiently short in cases when the beams used for transmission(s) do not jointly cover sufficiently large portion of the sensing protected area.

Figure 19 illustrates a table 1900 of a second example multiplexing of transmission beams in time and frequency during a COT. In the second example, the transmission beams are multiplexed in frequency domain where at each frequency resource a beam (or a subset of beams) is used while multiple beams are used for transmissions across the LBT channel bandwidth, and these multiple beams together may cover the whole sensing area at each time interval Ti. Unlike in the case of TDM of transmission beams, because a device always senses the channel usage or availability over the whole LBT channel bandwidth, the device whose sensing coverage overlaps with the sensing range of the TRP will be able to detect that the channel as being occupied as long as some part of the LBT channel uses a beam that overlaps with the device’s sensing coverage. Therefore, there is no (or very short) gap in the COT during which the beams used for transmission(s) do not jointly cover sufficiently large portion of the sensing area.

Figure 20 illustrates a table 2000 of a third example multiplexing of transmission beams in time and frequency during a COT. In the third example, the transmission beams are multiplexed in frequency and time domains where at each time and frequency resource a beam (or a subset of beams) is used while multiple beams are used for transmissions across the LBT channel bandwidth, and during the COT. Together, these multiple beams may cover the whole sensing area at the same time. Unlike in the case of TDM of beams, because a device always senses the channel usage or availability over the whole LBT channel bandwidth, the device whose sensing coverage overlaps with the sensing range of the TRP may be able to detect that the channel is occupied if some part of the LBT channel uses a beam that overlaps with the device’s sensing coverage during the channel sensing duration. Therefore, there is no (or very short) gap in the COT during which the beams used for transmission(s) do not jointly cover sufficiently large portion of the sensing area. Figure 21 illustrates a table 2100 of a fourth example multiplexing of transmission beams in time and frequency during a COT. In the fourth example, the transmission beams are frequency and time multiplexed where at each time and frequency resource a beam (or a subset of beams) is used while multiple beams are used for transmissions across the LBT channel bandwidth and during the COT and these multiple beams together partially cover the whole sensing area at the same time. Unlike previous examples, at some times, at least one beam direction is not covered by the transmission beams, for example, at Tt no Bt is covered in any frequency resource, at T2 no B2 is covered in any frequency resource, at T3 no B3 is covered in any frequency resource, etc. However, although Bt is missing in Ti, it appears in T2, T3, and so on. In other words, there is a brief time gap for T2, a brief time gap for B2, a brief time gap for B3 in T3, etc. These brief gaps are made short enough, e.g., shorter than 16 microseconds, and therefore, a device always sensing the channel usage or availability over the whole LBT channel bandwidth will not see sufficiently long time gap within the entire sensing coverage area and sense that the channel is idle and will not make a transmission, that may cause a collision. This strategy may also be applied to that the second example shown in Figure 18 if the beams are cycled sufficiently fast enough so that no beam has a time gap longer than, e.g., 16 microseconds, which overcomes the potential collision problem described above, if the number of beams are not too large.

The above examples can be extended to more complex situations, for example, there may be a wider beamwidth beam that covers beams Bt 1604 and B21606 at the same time. A wide beam equal to the sensing beam may also be one of the beams time-multiplexed together. There may be some beams that are partially overlapped in spatial domain. There may be a narrow spatial gap not fully covered by the beams, but if the spatial gap is small (as is the case shown in Figure 16), then a device falling in that spatial gap and having data to transmit in a direction with a potential collision is very unlikely and the spatial gap may be safely disregarded.

According to an example embodiment, methods and apparatus for transmit beam multiplexing within the coverage of a sensing beam are provided. Overall, frequency and time multiplexing of different beams may be used by the TRP during the COT and within the LBT channel bandwidth. These beams shall be within the coverage of the sensing beam (and its associated sensing threshold). During the COT, the time interval (or a gap) of when the beams used for transmission(s) do not provide a combined coverage (referred to as joint coverage) that covers a sufficiently large portion of the sensing area should be sufficiently short. When such a gap is longer than a time duration threshold, after the TRP has not transmitted in a certain beam direction and angular spread (for example that of beam B21606) for a period of time longer than a certain time duration, the TRP needs to sense the channel at (or including) the beam direction and angular spread (for example that of beam B21606) before transmitting at the beam direction and with angular spread again.

For example, during a COT of 9 milliseconds, each constituent beam needs to be transmitted at least once per every 16 microseconds. Using 5G NR with numerology 4 (SCS = 240 kHz) as an example, this means that each constituent beam needs to be transmitted at least once every 3 or 4 OFDM symbols; if each OFDM symbol transmits on one constituent non-overlapping beam only, then at most 3 or 4 such beams can be multiplexed in the COT; if each OFDM symbol transmits two (e.g., in a MU, SDM, or FDM fashion) constituent non-overlapping beams only, then at most 6 to 8 such beams can be multiplexed in the COT; and so on. If the symbol duration becomes smaller and with larger SCS of 480 KHz or even 960 KHz, then more beams can be multiplexed in the COT. A few rules may be developed to simplify the transmission strategy, as described in detail below.

Assume that the longest time gap without requiring additional LBT within a COT is g, the OFDM symbol duration is t, and that there are n constituent non-overlapping beams. An embodiment strategy is to follow a fixed time pattern: Each \g/t\ symbols for a pattern that is repeated in time. In each symbol, [n/fg/tl] beams are multiplexed as SDM or FDM, where f.1 is the ceiling operator. The time pattern may need to be indicated to the UEs using DCI so that the UE can rate match or disregard some OFDM symbols pointing to a different direction. As an example, the DCI may have a new field for the UE to know the OFDM symbols it should use for its time domain resource assignment (TDRA). Within each OFDM symbol, as long as the [n/lg/tl] beams are transmitted, how they are multiplexed, such as SDM or FDM, or which form of FDM, or FDMed in a same or different way as other OFDM symbol(s) can be determined by the access node. However, to save resource allocation field overhead in DCI, it may be possible that the SDM or FDM also follow a pre-determined pattern over time, such as simple repetition. This strategy may be seen as the access node “juggling” among n beams and only tending a beam right before that beam space may be taken by others. If larger SCS is supported, then the time pattern may become a half-slot or a full slot. This may help simplify the access node scheduling and resource allocation. A multi-slot scheduling can be adopted and a UE will retrieve its data from the m-th OFDM symbols of all the slots within a COT.

The above example embodiment put strong restriction on access node scheduling and resource allocation. In another embodiment, assume the longest time gap without requiring additional LBT within a COT is g, and a slot can fit within g. The access node transmits a wide beam corresponding to the sensing beam at least once in each slot. The wide beam may carry a DCI which is intended for multiple UEs or non-high spectrum efficiency purposes.

Figure 22 illustrates a flow diagram of operations 2200 occurring in a transmitting device making a transmission in unlicensed spectrum utilizing beamformed LBT with multiple transmission beams.

Operations 2200 begin the transmitting device sensing the channel (block 2202). The transmitting device senses the channel with a sensing beam. The sensing beam corresponds to a set of transmit beams, the set of transmit beams providing coverage of the sensing beam. The coverage of the set of transmit beams may be about equal to the coverage of the sensing beam or the coverage of the set of transmit beams may be greater than that of the sensing beam. The transmitting device determines that the channel is clear (block 2204). The transmitting device determines that the channel is clear (or idle) based on measurements made while the transmitting device senses the channel. As an example, the transmitting device makes measurements of the channel using the sensing beam.

The transmitting device starts a COT and starts a COT timer (block 2206). The COT started by the transmitting device is associated with the sensing beam. The transmitting device performs a transmission with a first subset of the set of transmit beams (block 2208). The first subset of the set of transmit beams may include one or more transmit beams from the set of transmit beams, for example. As an example, referring back to Figure 16, the first subset of the set of transmit beams may include beam Bt 1604. The transmitting device determines a first angular area outside of the first subset of the set of transmit beams (block 2210). The first angular area outside of the first subset of the set of transmit beams may include areas that are inside the coverage of the sensing beam but outside the coverage of the subset of the set of transmit beams.

The transmitting device starts a gap timer (block 2212). The gap timer is associated with the first angular area and corresponds to when the transmit beams do not jointly cover a portion of the coverage of the sensing beam. In other words, the gap timer is associated with the first angular area that corresponds to when the combined coverage of the transmit beams do not cover a portion of the coverage of the sensing beam. The gap timer corresponds to the time when the sensing beam is not being covered (at least in part) by the set of transmit beams. The transmitting device performs a check to determine if the gap timer has expired (block 2214). The gap timer may expire when it reaches a specified value or zero, for example. The specified value corresponds to the time when the sensing beam is not being covered. If the gap timer has expired, the transmitting device ends the COT and the COT timer (block 2216). The ending of the COT results in the transmitting device having to repeat the LBT process (i.e., sensing the channel, etc.) before it transmits.

If the gap timer has not expired, the transmitting device determines a second subset of the set of transmit beams (block 2218). The second subset of the set of transmit beams cover the first angular area. In other words, the second subset of the set of transmit beams provides coverage for the first angular area, which was not covered by the first subset of the set of transmit beams. The transmission device performs a transmission with the second subset of the set of transmit beams (block 2220). The transmitting device continues transmissions, along with the coverage of gaps that may present in the coverage of the sensing beam in the transmit beams used in the transmissions. As an example, the transmitting device may, after transmitting over the second subset of the set of transmit beams, transmit over the first subset of the set of transmit beams, transmit over the second subset of the set of transmit beams, and so on, until the COT ends.

In 3GPP, spherical coverage is an over the air (OTA) metric has been specified. Spherical coverage is the range of solid angles that a UE can cover. Spherical coverage can be quantified by the coverage efficiency which is defined as the ratio between the total covered solid angles and the whole surrounding sphere. 3GPP evaluated this parameter with the cumulative distribution function (CDF) of the EIRP.

In an embodiment, COT spherical coverage is defined as the range of solid angles that a UE can cover during a specific COT, and COT transmission coverage efficiency is the ratio between the total covered solid angles during any single transmission and the whole COT spherical coverage. Furthermore, the requirement of spatial coverage is a requirement that the average COT transmission coverage threshold is above a specified threshold, where the threshold may be specified in a technical standard or the operator of the communication system. The requirement of spatial coverage is expressible in terms of minimum time gap to transmit to the same solid angles. Additionally, the directional sensing duration required before a directional transmission is related to the transmission spherical coverage, and the time gap to the next transmission that covers the same spherical coverage.

A larger spherical coverage will typically require a longer channel sensing. For example, a larger time gap of transmitting toward the same direction range will require a longer channel sensing time. The dependence between time gap, spherical coverage of a transmission, and sensing duration can be expressed in many ways. The examples provided herein are only a simple example of such dependence.

As an illustrative example, let ATi be defined as the time from the last transmission using transmit beam Bi. If ATi is short (e.g., shorter than a specified threshold), then there is no LBT. If DTΐ is larger than the specified threshold, then the LBT duration TLBT before transmission depends on DTΐ as well as the EIRP of transmit beam Bi. As an example:

TLBT = ihίh{(DTί - Threshold)/Ts * (Bi[EIRP] - min{Bk[EIRP]}), max_LBT} where Ts is the sensing slot duration (e.g., 5 microseconds), min{Bk[EIRP]} is the minimum EIRP of all beams transmitting in the same COT, Threshold is the specified threshold related to DTΐ, and max_LBT is the maximum LBT duration.

With directional sensing, the TRP obtains access to a channel with certain spatial direction and angular spread. When the TRP shares the channel COT with a UE, the UE may transmit beamformed channels and signals. The UE’s beamformed transmission should also generally fall within the TRP's sensing direction/angular spread. However, as the TRP and the UE(s) are not collocated, and the TX beam of TRP and the TX beam of the UE(s) are generally oriented towards each other (i.e., in opposite directions) instead.

According to an example embodiment, the UE can also perform sensing prior to making an uplink transmission. In general, the UE may perform a LBT process to determine if the channel is idle prior to making an uplink transmission. However, the UE is provided a transmission opportunity associated with the uplink transmission, so the LBT process needs to occur prior to the transmission opportunity. As an example, the LBT process for the UE may occur during a COT, so that the UE may measure the channel before the transmission opportunity. If the transmission opportunity is part of a persistent allocation, the UE may have wider leeway when it comes to performing the LBT process.

In an embodiment, if a UE has selected a receive beam and that beam correspondence for the uplink and the downlink is satisfied, then the UE uses the downlink receive beam as the uplink transmit beam.

In an embodiment, if the access node has selected a transmit beam for the UE prior to the UE performing beam sweeping, if the UE has multiple different downlink receptions using different receive beams, the uplink transmit beam is indicated by the access node. The access node may use the TCI in the DCI, for example.

In an embodiment, the UE senses the channel using its downlink receive beam (and hence, the uplink transmit beam due to beam correspondence) if the UE has not use the receive beam to receive a downlink transmission for a specified amount of time and if it was instructed by the access node to use a specific LBT before transmitting.

In an embodiment, the sensing threshold of the UE is scaled by the TRP sensing threshold by a difference of the maximum EIRP of the TRP and the UE, i.e., Xu = X2 - (EIRPmax_ue - EIRPmax_tx) = Xt - (EIRPmax_UE - EIRPsense).

In an embodiment, the UE receives, from a TRP (or an access node), a control message with spatial information for its transmission of uplink channel or signal or for its reception of downlink channel or signal. The UE also receives a control message with information regarding a channel access procedure. The UE senses the availability of a channel according to the spatial information for transmission (or reception), as well as the information for channel access procedure. After the UE obtains access to the channel, the UE transmits physical layer channel or signal according to the spatial information for the transmission. The spatial information for the UE’s transmission of uplink channel or signal or for the UE’s reception of downlink channel or signal may be received via upper layer signaling such as RRC, MAC CE, or via physical layer signaling such as DCI . The spatial information may include TCI, QCL TypeD information, or SRS resource indication (SRI). The UE performs reception using downlink spatial receive filter according to TCI or QCL TypeD information. The UE performance transmission using uplink spatial beamforming according to TCI, QCL TypeD information, or SRI. The information for channel access procedure may include the LBT type, sensing during, gap duration, sensing threshold, etc. The information for channel access procedure may be received via RRC, MAC CE, or DCI. The UE preforms sensing the channel availability according to the information for channel access procedure. The UE performs sensing of the channel availability using receive beam according to the spatial information for its downlink reception, such as TCI or QCL TypeD. As an alternative, the UE performs sensing the channel availability using receive beam according to the spatial information for its uplink transmission, such as TCI, QCL TypeD, or SRI.

Figure 23 illustrates a flow diagram of example operations 2300 occurring in the UE making an uplink transmission in unlicensed spectrum utilizing beamformed LBT with multiple transmission beams.

Operations 2300 begin with the UE performing transmit beam sweeping (block 2302). Transmit beam sweeping may involve the UE transmitting a signal over a set of transmit beams. As an example, the UE transmits the signal in each transmit beam of the set of transmit beams for a specified amount of time, where the UE may be able to continuously transmit over all transmit beams of the set of transmit beams or transmit over some of the transmit beams, pause to perform other activities, and resume transmitting over additional transmit beams. The UE receives a TCI in a DCI (block 2304). The DCI is received from the access node, for example. The TCI may specify a receive beam for the UE. However, due to beam correspondence, the transmit beam is indirectly specified.

The UE receives a downlink transmission (block 2306). The UE receives the downlink transmission utilizing the receive beam specified in the TCI, for example. Block 2306 maybe an optional operation. The UE receives an instruction to perform a LBT process (block 2308). The instruction to perform the LBT process may be received in a separate message or in a combined message, such as with the downlink transmission, for example. As an alternative, the UE initiates the LBT process on its own when a timer started after the downlink transmission exceeds a threshold. The threshold may be specified by a technical standard or set by the operator of the communication system.

The UE performs the LBT process (block 2310). The LBT process may be as described herein. If the channel is clear, the UE transmits in the uplink (block 2312). The UE transmits in the uplink using the transmit beam corresponding to the receive beam indicated by the TCI, for example.

According to an example embodiment, the access node transmits downlink reference signals, e.g. SSB, or NZP CSI-RS, to the UE to perform receive spatial parameter derivation. The UE forms a receive beam according to the derived receive spatial parameters.

According to an example embodiment, the access node indicates to the UE the uplink transmission with the transmit beam being defined with spatial relation to certain downlink reference signals indicators, e.g., synchronization signal block resource indicator (SSBRI) or CSI-RS resource indicator (CRI). The UE forms the receive beam by applying the receive spatial parameters corresponding to the indicated downlink signal. The UE performs LBT using the receive beam. The UE performs uplink transmission with the transmit beam which is the correspondence beam of the receive beam used in the LBT process.

According to an example embodiment, the access node indicates to the UE the uplink transmission with the transmit beam defined with spatial relation to certain uplink reference signals indicators, e.g., SRI. The UE forms the same transmit beam which is used in transmitting the indicated uplink reference signal, e.g., SRS. The UE also performs LBT by applying the receive beam which is the correspondence beam of the formed transmit beam.

According to an example embodiment, the access node indicates to the UE the uplink transmission with the transmit beam with TCI. The TCI indicates the transmit beam with QCL to certain uplink reference signal indicators, e.g., SRI. The UE also forms the same transmit beam which is used in transmitting the indicated uplink reference signal, e.g., SRS, and the UE performs LBT by applying the receive beam which is the correspondence beam of the formed transmit beam.

According to an example embodiment, in uplink transmission power control, the UE may reduce its uplink transmission power to prevent the near-far problem. In such a situation, the uplink transmission coverage area may be reduced. In applying LBT for the reduced transmit power, the power reduction should be taken into consideration while deriving the LBT threshold. For example, if the uplink transmission power is reduced with x dB, the LBT threshold should be increased by xdB.

According to an example embodiment, in uplink transmission maximum permitted exposure (MPE), the UE may back off its uplink transmission power to meet MPE requirements. In this case, the uplink transmission coverage area maybe reduced. In applying LBT for the reduced transmit power, the power back off should be taken into account in deriving the LBT threshold. For example, if the uplink transmission power is reduced by x dB, the LBT threshold should be increased by x dB.

According to an example embodiment, in the case that the UE transmit beamwidth is narrower than the downlink LBT beamwidth, several UEs may be indicated to transmit simultaneously. Each UE performs LBT with a receive beam which is the correspondence beam of the indicated uplink transmit beam. The union of the UE LBT receive beams should cover the downlink LBT beam coverage.

According to an example embodiment, in the case that the UE performs uplink beam sweeping, the UE performs LBT with an effectively wider beam which should cover a union of the coverage of the sweeping beams. The beamforming gain difference between the LBT beam and sweeping beams should be taken into account into the derivation of the LBT threshold. The derivation of the LBT threshold should follow from the derivation of downlink LBT threshold within the COT.

According to an example embodiment, in the case that the UE is scheduled to transmit to multiple TRPs with different transmit beams, the UE performs LBT with receive beams which are the union of the correspondence beams of the scheduled uplink transmit beams. The beamforming gain difference between the LBT beam and transmit beams should be taken into account into the derivation of the LBT threshold. The derivation of the LBT threshold should follow similarly the derivation of downlink LBT threshold within the COT.

Figure 24 illustrates an example communication system 2400. In general, the system 2400 enables multiple wireless or wired users to transmit and receive data and other content. The system 2400 may implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).

In this example, the communication system 2400 includes electronic devices (ED) 24ioa-24toc, radio access networks (RANs) 242oa-242ob, a core network 2430, a public switched telephone network (PSTN) 2440, the Internet 2450, and other networks 2460. While certain numbers of these components or elements are shown in Figure 24, any number of these components or elements may be included in the system 2400.

The EDs 24ioa-24toc are configured to operate or communicate in the system 2400. For example, the EDs 24103-24100 are configured to transmit or receive via wireless or wired communication channels. Each ED 24108-24100 represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, or consumer electronics device.

The RANs 242oa-242ob here include base stations 2470a-2470b, respectively. Each base station 2470a-2470b is configured to wirelessly interface with one or more of the EDs 24ioa-24toc to enable access to the core network 2430, the PSTN 2440, the Internet 2450, or the other networks 2460. For example, the base stations 2470a-2470b may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNodeB), a Next Generation (NG) NodeB (gNB), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 24108-24100 are configured to interface and communicate with the Internet 2450 and may access the core network 2430, the PSTN 2440, or the other networks 2460. In the embodiment shown in Figure 24, the base station 2470a forms part of the RAN 2420a, which may include other base stations, elements, or devices. Also, the base station 2470b forms part of the RAN 2420b, which may include other base stations, elements, or devices. Each base station 2470a-2470b operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multiple-input multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

The base stations 2470a-2470b communicate with one or more of the EDs 24103-24100 over one or more air interfaces 2490 using wireless communication links. The air interfaces 2490 may utilize any suitable radio access technology.

It is contemplated that the system 2400 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

The RANs 2420a-2420b are in communication with the core network 2430 to provide the EDs 24ioa-24toc with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs 2420a-2420b or the core network 2430 may be in direct or indirect communication with one or more other RANs (not shown). The core network 2430 may also serve as a gateway access for other networks (such as the PSTN 2440, the Internet 2450, and the other networks 2460). In addition, some or all of the EDs 24ioa-24toc may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 2450.

Although Figure 24 illustrates one example of a communication system, various changes may be made to Figure 24. For example, the communication system 2400 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

Figures 25A and 25B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, Figure 25A illustrates an example ED 2510, and Figure 25B illustrates an example base station 2570. These components could be used in the system 2400 or in any other suitable system. As shown in Figure 25A, the ED 2510 includes at least one processing unit 2500. The processing unit 2500 implements various processing operations of the ED 2510. For example, the processing unit 2500 could perform signal coding, data processing, power control, input/output processing, or any other functionality enabling the ED 2510 to operate in the system 2400. The processing unit 2500 also supports the methods and teachings described in more detail above. Each processing unit 2500 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 2500 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

The ED 2510 also includes at least one transceiver 2502. The transceiver 2502 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 2504. The transceiver 2502 is also configured to demodulate data or other content received by the at least one antenna 2504. Each transceiver 2502 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 2504 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 2502 could be used in the ED 2510, and one or multiple antennas 2504 could be used in the ED 2510. Although shown as a single functional unit, a transceiver 2502 could also be implemented using at least one transmitter and at least one separate receiver.

The ED 2510 further includes one or more input/output devices 2506 or interfaces (such as a wired interface to the Internet 2450). The input/output devices 2506 facilitate interaction with a user or other devices (network communications) in the network. Each input/output device 2506 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

In addition, the ED 2510 includes at least one memory 2508. The memory 2508 stores instructions and data used, generated, or collected by the ED 2510. For example, the memory 2508 could store software or firmware instructions executed by the processing unit(s) 2500 and data used to reduce or eliminate interference in incoming signals. Each memory 2508 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like. As shown in Figure 25B, the base station 2570 includes at least one processing unit 2550, at least one transceiver 2552, which includes functionality for a transmitter and a receiver, one or more antennas 2556, at least one memory 2558, and one or more input/output devices or interfaces 2566. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 2550. The scheduler could be included within or operated separately from the base station 2570. The processing unit 2550 implements various processing operations of the base station 2570, such as signal coding, data processing, power control, input/output processing, or any other functionality. The processing unit 2550 can also support the methods and teachings described in more detail above. Each processing unit 2550 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 2550 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

Each transceiver 2552 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 2552 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 2552, a transmitter and a receiver could be separate components. Each antenna 2556 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 2556 is shown here as being coupled to the transceiver 2552, one or more antennas 2556 could be coupled to the transceiver(s) 2552, allowing separate antennas 2556 to be coupled to the transmitter and the receiver if equipped as separate components. Each memory 2558 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input/output device 2566 facilitates interaction with a user or other devices (network communications) in the network. Each input/output device 2566 includes any suitable structure for providing information to or receiving/providing information from a user, including network interface communications.

Figure 26 is a block diagram of a computing system 2600 that may be used for implementing the devices and methods disclosed herein. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 2600 includes a processing unit 2602. The processing unit includes a central processing unit (CPU) 2614, memory 2608, and may further include a mass storage device 2604, a video adapter 2610, and an I/O interface 2612 connected to a bus 2620.

The bus 2620 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 2614 may comprise any type of electronic data processor. The memory 2608 may comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 2608 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

The mass storage 2604 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 2620. The mass storage 2604 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

The video adapter 2610 and the I/O interface 2612 provide interfaces to couple external input and output devices to the processing unit 2602. As illustrated, examples of input and output devices include a display 2618 coupled to the video adapter 2610 and a mouse, keyboard, or printer 2616 coupled to the I/O interface 2612. Other devices may be coupled to the processing unit 2602, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

The processing unit 2602 also includes one or more network interfaces 2606, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 2606 allow the processing unit 2602 to communicate with remote units via the networks. For example, the network interfaces 2606 may provide wireless communication via one or more transmitters/transmit antennas and one or more receivers/ receive antennas. In an embodiment, the processing unit 2602 is coupled to a local-area network 2622 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

It should be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a sensing unit or module, a determining unit or module, a starting unit or module, an expiring unit or module, a stopping unit or module, an adapting unit or module, or a completing unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs). Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the disclosure as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method implemented by a transmitting device, the method comprising: sensing, by the transmitting device during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determining, by the transmitting device, a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determining, by the transmitting device, that the channel is idle in accordance with the sensing threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

2. The method of claim t, the sensing using a receive spatial filter.

3. The method of any one of claims t-2, the sensing comprising detecting an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

4. The method of claim 3, the channel is determined as idle if the energy level associated with the channel is lower than the energy detection threshold.

5. The method of any one of claim 1-4, the transmitting using at least one transmitting spatial filter.

6. The method of claim 1, further comprising starting, by the transmitting device, a channel occupancy time (COT) timer associated with a COT associated with the transmitting.

7. The method of claim 6, further comprising expiring, by the transmitting device, the COT timer at least when the COT timer reaches a maximum channel occupancy time.

8. The method of claim 7, further comprising completing, by the transmitting device, the transmitting prior to expiration of the COT timer.

9. The method of claim 7, further comprising stopping, by the transmitting device, the transmitting responsive to the expiration of the COT timer. to. The method of claim 3, the channel is determined as busy if the energy level associated with the channel is higher than the energy detection threshold.

11. The method of any one of claims l-io, the sensing comprising preamble detection, and the sensing threshold comprising a preamble detection threshold.

12. The method of claim 5, the at least one transmitting spatial filter being associated with the at least one transmit beam.

13. The method of any one of claims 1-12, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

14. The method of claim 13, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between an effective isotropic radiated power (EIRP) of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

15. The method of claim 13, further comprising adapting, by the transmitting device, the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

16. The method of any one of claims 6-9, further comprising transmitting, by the transmitting device, physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

17. The method of claim 16, further comprising determining, by the transmitting device during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

18. The method of claim 16, further comprising determining, by the transmitting device during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam.

19. A transmitting device comprising : one or more processors; and a non-transitory memory storage comprising instructions that, when executed by the one or more processors, cause the transmitting device to: sense, during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determine a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determine that the channel is idle in accordance with the sensing threshold, and based thereon, transmit on the channel using the at least one transmit beam.

20. The transmitting device of claim 19, the instructions causing the transmitting device to detect an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

21. The transmitting device of any one of claims 19-20, the instructions causing the transmitting device to start a channel occupancy time (COT) timer associated with a COT associated with the transmitting.

22. The transmitting device of claim 21, the instructions causing the transmitting device to expire the COT timer at least when the COT timer reaches a maximum channel occupancy time.

23. The transmitting device of claim 22, the instructions causing the transmitting device to complete the transmitting prior to expiration of the COT timer.

24. The transmitting device of claim 22, the instructions causing the transmitting device to stop the transmitting responsive to the expiration of the COT timer.

25. The transmitting device of any one of claims 19-24, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

26. The transmitting device of claim 25, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between an effective isotropic radiated power (EIRP) of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

27. The transmitting device of claim 25, the instructions causing the transmitting device to adapt the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

28. The transmitting device of any one of claims 21-24, the instructions causing the transmitting device to transmit physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

29. The transmitting device of claim 28, the instructions causing the transmitting device to determine, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmit on the channel using the at least one transmit beam.

30. The transmitting device of claim 28, the instructions causing the transmitting device to determine, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam.

31. A non-transitoiy computer-readable media storing computer instructions, that when executed by one or more processors, cause the one or more processors to perform the steps of: sensing, by a transmitting device during a sensing slot using a sensing beam, an availability of a channel for performing at least one transmission using at least one transmit beam; determining, by the transmitting device, a sensing threshold in accordance with the sensing beam and the at least one transmit beam; and determining, by the transmitting device, that the channel is idle in accordance with the sensing threshold, and based thereon, transmitting, by the transmitting device, on the channel using the at least one transmit beam.

32. The media of claim 31, the instructions causing the one or more processors to perform the step of detecting an energy level associated with the channel, and the sensing threshold comprising an energy detection threshold.

33. The media of any one of claims 30-31, the instructions causing the one or more processors to perform the step of starting a channel occupancy time (COT) timer associated with a COT associated with the transmitting.

34. The media of claim 33, the instructions causing the one or more processors to perform the step of expiring the COT timer at least when the COT timer reaches a maximum channel occupancy time.

35. The media of claim 34, the instructions causing the one or more processors to perform the step of completing the transmitting prior to expiration of the COT timer.

36. The media of claim 34, the instructions causing the one or more processors to perform the step of stopping the transmitting responsive to the expiration of the COT timer.

37. The media of any one of claims 31-36, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between the sensing beam and the at least one transmit beam.

38. The media of claim 37, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between an effective isotropic radiated power (EIRP) of the of the sensing beam when it is used for transmitting and a maximum EIRP of the at least one transmit beam.

39. The media of claim 37, the instructions causing the one or more processors to perform the step of adapting the sensing threshold in accordance with a difference between a beamforming gain of the sensing beam and a maximum beamforming gain of the at least one transmit beam.

40. The media of any one of claims 33-36, the instructions causing the one or more processors to perform the step of transmitting physical layer channels or signals during the COT using one or more transmit beams with an EIRP smaller than a maximum EIRP value.

41. The media of claim 40, the instructions causing the one or more processors to perform the step of determining, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is shorter than a time threshold, and based thereon, transmit on the channel using the at least one transmit beam.

42. The media of claim 40, the instructions causing the one or more processors to perform the step of determining, during the COT, that a time interval associated with a coverage gap between a coverage of the sensing beam and a combined coverage of the at least one transmit beam is longer than a time threshold, and based thereon, sensing, by the transmitting device, the availability of the channel for performing at least one transmission using the at least one transmit beam.