Patent Description:
With the increased demand for mobile broadband access, additional spectrum has been opened for shared communications at frequencies previously restricted for exclusive licensed, governmental, or military use. In one example of such additional spectrum, the citizens broadband radio service (CBRS) spectrum around <NUM> has been opened for shared access according to new, hierarchical access rights and procedures. This shared scheme may be referred to as Spectrum Access System (SAS) or License Shared Access (LSA). Further procedures and advancement may be directed to enhancing mobile communications using such shared spectrum. <CIT> discloses channel reservation systems and methods which schedule transmissions on a shared radio medium that is shared by a plurality of licensed network operators. Other documents disclosing the use of SRS signals in the context of unlicensed spectrum access are the following:.

In one aspect of the disclosure, a method of wireless communication includes obtaining, by a UE, a resource configuration, wherein the resource configuration identifies a plurality of sound reference signal (SRS) resources including at least a sounding set of SRS resources and a coexistence set of SRS resources, receiving, by the UE, a trigger signal from a serving base station over a shared spectrum shared between at least one or more priority license users, transmitting, by the UE in response to the trigger signal, an SRS using the coexistence set of SRS resources, and communicating, by the UE, with the serving base station.

In an additional aspect of the disclosure, a method of wireless communication includes determining, by a base station, a communication operation between the base station and one or more served UEs, monitoring, by the base station, for radio frequency (RF) energy on a communication channel at a beginning of a listen before talk (LBT) window of a current frame in a shared spectrum shared between at least one or more opportunistic general authorized users, wherein the monitoring occurs after a back-off operation executed by the base station, transmitting, by the base station, an LBT trigger signal in response to detection of no RF energy above a minimum energy threshold at the beginning of the LBT window, receiving, by the base station, an LBT trigger response signal from the one or more served UEs, wherein the RF energy on the communication channel remains above the minimum energy threshold for a remainder of the LBT window, and communicating, by the base station, with the one or more UEs during a channel occupancy time (COT) of the current frame after the LBT window.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for obtaining, by a UE, a resource configuration, wherein the resource configuration identifies a plurality of SRS resources including at least a sounding set of SRS resources and a coexistence set of SRS resources, means for receiving, by the UE, a trigger signal from a serving base station over a shared spectrum shared between at least one or more priority license users, means for transmitting, by the UE in response to the trigger signal, an SRS using the coexistence set of SRS resources, and means for communicating, by the UE, with the serving base station.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for determining, by a base station, a communication operation between the base station and one or more served UEs, means for monitoring, by the base station, for RF energy on a communication channel at a beginning of a LBT window of a current frame in a shared spectrum shared between at least one or more opportunistic general authorized users, wherein the means for monitoring occurs after a back-off operation executed by the base station, means for transmitting, by the base station, an LBT trigger signal in response to detection of no RF energy above a minimum energy threshold at the beginning of the LBT window, means for receiving, by the base station, an LBT trigger response signal from the one or more served UEs, wherein the RF energy on the communication channel remains above the minimum energy threshold for a remainder of the LBT window, and means for communicating, by the base station, with the one or more UEs during a COT of the current frame after the LBT window.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to obtain, by a UE, a resource configuration, wherein the resource configuration identifies a plurality of SRS resources including at least a sounding set of SRS resources and a coexistence set of SRS resources, code to receive, by the UE, a trigger signal from a serving base station over a shared spectrum shared between at least one or more priority license users, code to transmit, by the UE in response to the trigger signal, an SRS using the coexistence set of SRS resources, and code to communicate, by the UE, with the serving base station.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to determine, by a base station, a communication operation between the base station and one or more served UEs, code to monitor, by the base station, for RF energy on a communication channel at a beginning of a LBT window of a current frame in a shared spectrum shared between at least one or more opportunistic general authorized users, wherein the code to monitor is executed after a back-off operation executed by the base station, code to transmit, by the base station, an LBT trigger signal in response to detection of no RF energy above a minimum energy threshold at the beginning of the LBT window, code to receive, by the base station, an LBT trigger response signal from the one or more served UEs, wherein the RF energy on the communication channel remains above the minimum energy threshold for a remainder of the LBT window, and code to communicate, by the base station, with the one or more UEs during a COT of the current frame after the LBT window.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to obtain, by a UE, a resource configuration, wherein the resource configuration identifies a plurality of SRS resources including at least a sounding set of SRS resources and a coexistence set of SRS resources, to receive, by the UE, a trigger signal from a serving base station over a shared spectrum shared between at least one or more priority license users, to transmit, by the UE in response to the trigger signal, an SRS using the coexistence set of SRS resources, and to communicate, by the UE, with the serving base station.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to determine, by a base station, a communication operation between the base station and one or more served UEs, to monitor, by the base station, for RF energy on a communication channel at a beginning of a LBT window of a current frame in a shared spectrum shared between at least one or more opportunistic general authorized users, wherein the configuration to monitor is executed after a back-off operation executed by the base station, to transmit, by the base station, an LBT trigger signal in response to detection of no RF energy above a minimum energy threshold at the beginning of the LBT window, to receive, by the base station, an LBT trigger response signal from the one or more served UEs, wherein the RF energy on the communication channel remains above the minimum energy threshold for a remainder of the LBT window, and to communicate, by the base station, with the one or more UEs during a COT of the current frame after the LBT window,.

This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, <NUM>th Generation (<NUM>) or new radio (NR) networks, as well as other communications networks. As described herein, the terms "networks" and "systems" may be used interchangeably.

In particular, <NUM> networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for <NUM> NR networks. The <NUM> NR will be capable of scaling to provide coverage (<NUM>) to a massive Internet of things (IoTs) with an ultra-high density (e.g., ~<NUM> nodes/km<NUM>), ultra-low complexity (e.g., ~<NUM> of bits/sec), ultra-low energy (e.g., ~<NUM>+ years of battery life), and deep coverage with the capability to reach challenging locations; (<NUM>) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ~<NUM>% reliability), ultra-low latency (e.g., ~ <NUM>), and users with wide ranges of mobility or lack thereof; and (<NUM>) with enhanced mobile broadband including extreme high capacity (e.g., ~ <NUM> Tbps/km<NUM>), extreme data rates (e.g., multi-Gbps rate, <NUM>+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.

The <NUM> NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/ frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in <NUM> NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than <NUM> FDD/TDD implementations, subcarrier spacing may occur with <NUM>, for example over <NUM>, <NUM>, <NUM>, <NUM>, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than <NUM>, subcarrier spacing may occur with <NUM> over <NUM>/<NUM> bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the <NUM> band, the subcarrier spacing may occur with <NUM> over a <NUM> bandwidth. Finally, for various deployments transmitting with mm Wave components at a TDD of <NUM>, subcarrier spacing may occur with <NUM> over a <NUM> bandwidth.

<FIG> is a block diagram illustrating <NUM> network <NUM> including various base stations and UEs configured according to aspects of the present disclosure. The <NUM> network <NUM> includes a number of base stations <NUM> and other network entities. A base station may be a station that communicates with the UEs and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each base station <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of a base station and/or a base station subsystem serving the coverage area, depending on the context in which the term is used.

A base station may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cell. A base station for a macro cell may be referred to as a macro base station. A base station for a small cell may be referred to as a small cell base station, a pico base station, a femto base station or a home base station. In the example shown in <FIG>, the base stations 105d and 105e are regular macro base stations, while base stations 105a-105c are macro base stations enabled with one of <NUM> dimension (3D), full dimension (FD), or massive MIMO. Base stations 105a-105c take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. Base station 105f is a small cell base station which may be a home node or portable access point. A base station may support one or multiple (e.g., two, three, four, and the like) cells.

The <NUM> network <NUM> may support synchronous or asynchronous operation.

The UEs <NUM> are dispersed throughout the wireless network <NUM>, and each UE may be stationary or mobile. A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE may be a device that includes a Universal Integrated Circuit Card (DICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, UEs that do not include UICCs may also be referred to as internet of everything (IoE) or internet of things (IoT) devices. UEs 115a-115d are examples of mobile smart phone-type devices accessing <NUM> network <NUM> A UE may also be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. UEs 115e-<NUM> are examples of various machines configured for communication that access <NUM> network <NUM>. A UE may be able to communicate with any type of the base stations, whether macro base station, small cell, or the like. In <FIG>, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE and a serving base station, which is a base station designated to serve the UE on the downlink and/or uplink, or desired transmission between base stations, and backhaul transmissions between base stations.

In operation at <NUM> network <NUM>, base stations 105a-105c serve UEs 115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. Macro base station 105d performs backhaul communications with base stations 105a-105c, as well as small cell, base station 105f. Macro base station 105d also transmits multicast services which are subscribed to and received by UEs 115c and 115d.

<NUM> network <NUM> also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such UE 115e, which is a drone. Redundant communication links with UE 115e include from macro base stations 105d and 105e, as well as small cell base station 105f. Other machine type devices, such as UE 115f (thermometer), UE <NUM> (smart meter), and UE <NUM> (wearable device) may communicate through <NUM> network. <NUM> either directly with base stations, such as small cell base station 105f, and macro base station 105e, or in multi-hop configurations by communicating with another user device which relays its information to the network, such as UE 115f communicating temperature measurement information to the smart meter, UE <NUM>, which is then reported to the network through small cell base station 105f. <NUM> network <NUM> may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such as in a vehicle-to-vehicle (V2V) mesh network between UEs 115i-<NUM> communicating with macro base station 105e.

<FIG> shows a block diagram of a design of a base station <NUM> and a UE <NUM>, which may be one of the base station and one of the UEs in <FIG>. At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a through 232t. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

At the UE <NUM>, the antennas 252a through 252r may receive the downlink signals from the base station <NUM> and may provide received signals to the demodulators (DEMODs) 254a through 254r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.

On the uplink, at the UE <NUM>, a transmit processor <NUM> may receive and process data (e.g., for the PUSCH) from a data source <NUM> and control information (e.g., for the PUCCH) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the modulators 254a through 254r (e.g., for SC-FDM, etc.), and transmitted to the base station <NUM>. At the base station <NUM>, the uplink signals from the UE <NUM> may be received by the antennas <NUM>, processed by the demodulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE <NUM>. The processor <NUM> may provide the decoded data to a data sink <NUM> and the decoded control information to the controller/processor <NUM>.

The controller/processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct the execution of various processes for the techniques described herein. The controllers/processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct the execution of the functional blocks illustrated in <FIG> and <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the base station <NUM> and the UE <NUM>, respectively.

In some cases, UE <NUM> and base station <NUM> of the <NUM> network <NUM> may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs <NUM> or base stations <NUM> may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE <NUM> or base station <NUM> may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available. A CCA may include an energy detection procedure to determine whether there are any other active transmissions. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In the <NUM> network <NUM>, base stations <NUM> and UEs <NUM> may be operated by the same or different network operating entities. In some examples, an individual base station <NUM> or UE <NUM> may be operated by more than one network operating entity. In other examples, each base station <NUM> and UE <NUM> may be operated by a single network operating entity. Requiring each base station <NUM> and UE <NUM> of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

<FIG> illustrates an example of a timing diagram <NUM> for coordinated resource partitioning. The timing diagram <NUM> includes a superframe <NUM>, which may represent a fixed duration of time (e.g., <NUM>). The superframe <NUM> may be repeated for a given communication session and may be used by a wireless system such as <NUM> network <NUM> described with reference to <FIG>. The superframe <NUM> may be divided into intervals such as an acquisition interval (A-INT) <NUM> and an arbitration interval <NUM>. As described in more detail below, the A-INT <NUM> and arbitration interval <NUM> may be subdivided into sub-intervals, designated for certain resource types, and allocated to different network operating entities to facilitate coordinated communications between the different network operating entities. For example, the arbitration interval <NUM> may be divided into a plurality of sub-intervals <NUM>. Also, the superframe <NUM> may be further divided into a plurality of subframes <NUM> with a fixed duration (e.g., <NUM>). While timing diagram <NUM> illustrates three different network operating entities (e.g., Operator A, Operator B, Operator C), the number of network operating entities using the superframe <NUM> for coordinated communications may be greater than or fewer than the number illustrated in timing diagram <NUM>.

The A-INT <NUM> may be a dedicated interval of the superframe <NUM> that is reserved for exclusive communications by the network operating entities. In some examples, each network operating entity may be allocated certain resources within the A-INT <NUM> for exclusive communications. For example, resources <NUM>-a may be reserved for exclusive communications by Operator A, such as through base station 105a, resources <NUM>-b may be reserved for exclusive communications by Operator B, such as through base station 105b, and resources <NUM>-c may be reserved for exclusive communications by Operator C, such as through base station 105c. Since the resources <NUM>-a are reserved for exclusive communications by Operator A, neither Operator B nor Operator C can communicate during resources <NUM>-a, even if Operator A chooses not to communicate during those resources. That is, access to exclusive resources is limited to the designated network operator. Similar restrictions apply to resources <NUM>-b for Operator B and resources <NUM>-c for Operator C. The wireless nodes of Operator A (e. g, UEs <NUM> or base stations <NUM>) may communicate any information desired during their exclusive resources <NUM>-a, such as control information or data.

When communicating over an exclusive resource, a network operating entity does not need to perform any medium sensing procedures (e.g., listen-before-talk (LBT) or clear channel assessment (CCA)) because the network operating entity knows that the resources are reserved. Because only the designated network operating entity may communicate over exclusive resources, there may be a reduced likelihood of interfering communications as compared to relying on medium sensing techniques alone (e.g., no hidden node problem). In some examples, the A-INT <NUM> is used to transmit control information, such as synchronization signals (e.g., SYNC signals), system information (e.g., system information blocks (SIBs)), paging information (e.g., physical broadcast channel (PBCH) messages), or random access information (e.g., random access channel (RACH) signals). In some examples, all of the wireless nodes associated with a network operating entity may transmit at the same time during their exclusive resources.

In some examples, resources may be classified as prioritized for certain network operating entities. Resources that are assigned with priority for a certain network operating entity may be referred to as a guaranteed interval (G-INT) for that network operating entity. The interval of resources used by the network operating entity during the G-INT may be referred to as a prioritized sub-interval. For example, resources <NUM>-a may be prioritized for use by Operator A and may therefore be referred to as a G-INT for Operator A (e.g., G-INT-OpA). Similarly, resources <NUM>-b may be prioritized for Operator B (e.g., G-fNT-OpB), resources <NUM>-c may be prioritized for Operator C (e.g., G-IN-OpC), resources <NUM>-d may be prioritized for Operator A, resources <NUM>-e may be prioritized for Operator B, and resources <NUM>-f may be prioritized for Operator C.

The various G-INT resources illustrated in <FIG> appear to be staggered to illustrate their association with their respective network operating entities, but these resources may all be on the same frequency bandwidth. Thus, if viewed along a time-frequency grid, the G-INT resources may appear as a contiguous line within the superframe <NUM>. This partitioning of data may be an example of time division multiplexing (TDM). Also, when resources appear in the same sub-interval (e.g., resources <NUM>-a and resources <NUM>-b), these resources represent the same time resources with respect to the superframe <NUM> (e.g., the resources occupy the same sub-interval <NUM>), but the resources are separately designated to illustrate that the same time resources can be classified differently for different operators.

When resources are assigned with priority for a certain network operating entity (e.g., a G-INT), that network operating entity may communicate using those resources without having to wait or perform any medium sensing procedures (e.g., LBT or CCA). For example, the wireless nodes of Operator A are free to communicate any data or control information during resources <NUM>-a without interference from the wireless nodes of Operator B or Operator C.

A network operating entity may additionally signal to another operator that it intends to use a particular G-INT. For example, referring to resources <NUM>-a, Operator A may signal to Operator B and Operator C that it intends to use resources <NUM>-a. Such signaling may be referred to as an activity indication. Moreover, since Operator A has priority over resources <NUM>-a, Operator A may be considered as a higher priority operator than both Operator B and Operator C. However, as discussed above, Operator A does not have to send signaling to the other network operating entities to ensure interference-free transmission during resources <NUM>-a because the resources <NUM>-a are assigned with priority to Operator A.

Similarly, a network operating entity may signal to another network operating entity that it intends not to use a particular G-INT. This signaling may also be referred to as an activity indication. For example, referring to resources <NUM>-b, Operator B may signal to Operator A and Operator C that it intends not to use the resources <NUM>-b for communication, even though the resources are assigned with priority to Operator B. With reference to resources <NUM>-b, Operator B may be considered a higher priority network operating entity than Operator A and Operator C. In such cases, Operators A and C may attempt to use resources of sub-interval <NUM> on an opportunistic basis. Thus, from the perspective of Operator A, the sub-interval <NUM> that contains resources <NUM>-b may be considered an opportunistic interval (O-INT) for Operator A (e.g., O-INT-OpA). For illustrative purposes, resources <NUM>-a may represent the O-INT for Operator A. Also, from the perspective of Operator C, the same sub-interval <NUM> may represent an O-INT for Operator C with corresponding resources <NUM>-b. Resources <NUM>-a, <NUM>-b, and <NUM>-b all represent the same time resources (e.g., a particular sub-interval <NUM>), but are identified separately to signify that the same resources may be considered as a G-INT for some network operating entities and yet as an O-INT for others.

To utilize resources on an opportunistic basis, Operator A and Operator C may perform medium-sensing procedures to check for communications on a particular channel before transmitting data. For example, if Operator B decides not to use resources <NUM>-b (e.g., G-INT-OpB), then Operator A may use those same resources (e.g., represented by resources <NUM>-a) by first checking the channel for interference (e.g., LBT) and then transmitting data if the channel was determined to be clear. Similarly, if Operator C wanted to access resources on an opportunistic basis during sub-interval <NUM> (e.g., use an O-INT represented by resources <NUM>-b) in response to an indication that Operator B was not going to use its G-INT (e.g., resources <NUM>-b), Operator C may perform a medium sensing procedure and access the resources if available. In some cases, two operators (e.g., Operator A and Operator C) may attempt to access the same resources, in which case the operators may employ contention-based procedures to avoid interfering communications. The operators may also have sub-priorities assigned to them designed to determine which operator may gain access to resources if more than operator is attempting access simultaneously. For example, Operator A may have priority over Operator C during sub-interval <NUM> when Operator B is not using resources <NUM>-b (e.g., G-INT-OpB). It is noted that in another sub-interval (not shown) Operator C may have priority over Operator A when Operator B is not using its G-INT.

In some examples, a network operating entity may intend not to use a particular G-INT assigned to it, but may not send out an activity indication that conveys the intent not to use the resources. In such cases, for a particular sub-interval <NUM>, lower priority operating entities may be configured to monitor the channel to determine whether a higher priority operating entity is using the resources. If a lower priority operating entity determines through LBT or similar method that a higher priority operating entity is not going to use its G-INT resources, then the lower priority operating entities may attempt to access the resources on an opportunistic basis as described above.

In some examples, access to a G-INT or O-INT may be preceded by a reservation signal (e.g., request-to-send (RTS),"clear-to-send (CTS)), and the contention window (CW) may be randomly chosen between one and the total number of operating entities.

In some examples, an operating entity may employ or be compatible with coordinated multipoint (CoMP) communications. For example an operating entity may employ CoMP and dynamic time division duplex (TDD) in a G-INT and opportunistic CoMP in an O-INT as needed.

In the example illustrated in <FIG>, each sub-interval <NUM> includes a G-INT for one of Operator A, B, or C. However, in some cases, one or more sub-intervals <NUM> may include resources that are neither reserved for exclusive use nor reserved for prioritized use (e.g., unassigned resources). Such unassigned resources may be considered an O-INT for any network operating entity, and may be accessed on an opportunistic basis as described above.

In some examples, each sub frame <NUM> may contain <NUM> symbols (e.g., <NUM>-µs for <NUM> tone spacing). These subframes <NUM> may be standalone, self-contained Interval-Cs (ITCs) or the subframes <NUM> may be a part of a long ITC. An ITC may be a self-contained transmission starting with a downlink transmission and ending with an uplink transmission. In some embodiments, an ITC may contain one or more subframes <NUM> operating contiguously upon medium occupation. In some cases, there may be a maximum of eight network operators in an A-INT <NUM> (e.g., with duration of <NUM>) assuming a <NUM>-µs transmission opportunity.

Although three operators are illustrated in <FIG>, it should be understood that fewer or more network operating entities may be configured to operate in a coordinated manner as described above. In some cases, the location of the G-INT, O-INT, or A-INT within the superframe <NUM> for each operator is determined autonomously based on the number of network operating entities active in a system. For example, if there is only one network operating entity, each sub-interval <NUM> may be occupied by a G-INT for that single network operating entity, or the sub-intervals <NUM> may alternate between G-INTs for that network operating entity and O-INTs to allow other network operating entities to enter. If there are two network operating entities, the sub-intervals <NUM> may alternate between G-INTs for the first network operating entity and G-INTs for the second network operating entity. If there are three network operating entities, the G-INT and O-INTs for each network operating entity may be designed as illustrated in <FIG>. If there are four network operating entities, the first four sub-intervals <NUM> may include consecutive G-INTs for the four network operating entities and the remaining two sub-intervals <NUM> may contain O-INTs. Similarly, if there are five network operating entities, the first five sub-intervals <NUM> may contain consecutive G-INTs for the five network operating entities and the remaining sub-interval <NUM> may contain an O-INT. If there are six network operating entities, all six sub-intervals <NUM> may include consecutive G-INTs for each network operating entity. It should be understood that these examples are for illustrative purposes only and that other autonomously determined interval allocations may be used.

It should be understood that the coordination framework described with reference to <FIG> is for illustration purposes only. For example, the duration of superframe <NUM> may be more or less than <NUM>. Also, the number, duration, and location of sub-intervals <NUM> and subframes <NUM> may differ from the configuration illustrated. Also, the types of resource designations (e.g., exclusive, prioritized, unassigned) may differ or include more or less sub-designations.

Within the spectrum sharing of the CBRS or <NUM> spectrum, there may be three levels of priority defined for accessing the spectrum. Ultimate priority for accessing the spectrum lies with the incumbent users, such as governmental entities, U. naval radar systems, Department of Defense, fixed satellite systems (FSS), radio location services (e.g., aeronautical radio navigation systems (ARNS), etc.), site-specific protections for registered sites, and the like. When opening this spectrum to shared use, a portion of the spectrum was designated for sharing with the incumbent users. After incumbent users, priority access licenses (PALs) users, which typically pay a fee to reserve a portion of the spectrum in a particular geographic location and for a limited period of time have a next highest priority. The lowest priority users are referred to as general authorized access (GAA) users, which operate on opportunistic access principles. Thus, if neither incumbent nor PAL users are occupying available spectrum, GAA users may attempt access of the shared spectrum.

Within the segment of PAL users, the principles of spectrum sharing provide for both exclusive or guaranteed resources and shared resources. The exclusive or guaranteed resources are reserved for critical overhead signals and channels. Allocation of such exclusive resources may be coordinated through spectrum allocation servers, which manage access rights to the CBRS or <NUM> spectrum. PAL users may use such guaranteed resources for transmission of synchronization signal blocks (SSBs), system information (SI), paging signals, random access resources (physical random access channel (PRACH)) and the like. Because there may usually be a small number of operators sharing the spectrum band at any given geographical location, a relatively small overhead may be needed to manage sharing the spectrum.

Allocation and access to the guaranteed resources may be coordinated in both the time and frequency domains. The guaranteed resources may also be used as a part of different modes of operation due to flexible configurations for these resources in NR. Such guaranteed resources could also be used for critical quality of service (QoS) applications. For example, each licensee may be assigned resources that are not shared and that can be used for critical QoS services, such as ultra-reliable, low latency communications (URLLC), as well as hybrid automatic repeat request (HARQ) and channel state information (CSI) feedback.

In addition to the guaranteed resources, each PAL user may also access shared resources of the spectrum. Each such PAL user may be assigned priority access in different slots or frames of the shared resources. Thus, in the context of sharing between PAL users, for each slot or frame, there may be assigned priority PAL users and non-assigned priority PAL users. The shared resources can be used by the non-assigned priority PAL user when the assigned priority PAL user does not access the resource during its priority slot/frame. The determination of access to the shared resources occurs through a reservation procedure. The non-assigned priority users may create interference to the assigned priority users if the reservation procedure fails. In fact, the non-assigned priority users may block the medium from the assigned priority users until the channel occupancy time (COT) boundary.

<FIG> is a block diagram illustrating shared communications over CBRS spectrum between PAL users, base stations 105a-105c and UEs 115a-115c. The illustration of communication streams <NUM>-<NUM> visually depict the streams as separate resources. However, this visual depiction is for clarity. Each of communication streams <NUM>-<NUM> is the communication stream as seen by each of the communication pairs of the same frequency resources. Thus, communication stream <NUM> represents the shared frequency resources as seen by base station 105a and UE 115a, communication stream <NUM> represents the same shared frequency resources as seen by base station 105b and UE 115b, and communication stream <NUM> represents the same shared frequency resources as seen by base station 105b and UE 115b. Each of the base stations 105a-105c provide communications for different operators.

In a frame based equipment (FBE)-like procedure, the shared resources are organized into a synchronized slotted structure. The shared access server will assign each operator exclusive resources <NUM> in time. A channel reservation slot <NUM> is provided in each slot or frame. Base stations 105a-105b transmit a reservation signal according to a medium reservation order within channel reservation slot <NUM> (e.g., base station 105a transmits reservation signal <NUM>, base station 105b transmits reservation signal <NUM>, and base station 105c transmits reservation signal <NUM>). The medium reservation order within channel reservation slot <NUM> determines priority access. For example, in slot <NUM>, operator <NUM> has priority access. Therefore, base station 105a may use exclusive resources <NUM> for control or data signals and has assigned priority to the shared spectrum of slot <NUM> for communications with UE 115a. Similarly, operator <NUM> (base station 105b) has priority access to slot <NUM> and may use exclusive resources <NUM> of slot <NUM> and has assigned priority to the shared spectrum of slot <NUM> for communications with UE 115b. Operator <NUM> (base station 105c) has priority access to slot <NUM> and may use exclusive resources <NUM> of slot <NUM> and has assigned priority to the shared spectrum of slot <NUM> for communications with UE 115c.

Within channel reservation slot <NUM> of each of slots <NUM>-<NUM>, the medium reservation order will determine which operator has priority access to the shared resources of the slot. Therefore, within channel reservation slot <NUM> of slot <NUM>, base station 105a transmits reservation signal <NUM> in the first position. Base stations 105b and 105c (of operators <NUM> and <NUM>, respectively) are listening for reservation signal <NUM> to identify whether the assigned priority user will be accessing the shared resources. If undetected, base station 105b would transmit reservation signal <NUM> to reserve the shared resources. Base station 105c, which is assigned the last position of the medium reservation order, further listens for reservation signal <NUM>. If undetected, base station 105c will transmit reservation signal <NUM>. During the assigned priority slot of one operator, the other operators may have opportunistic access to the shared resources if the assigned priority user does not reserve access to the slot.

Existing NR signals and channels may be leveraged for use in the reservation procedure. For example, a base station transmission of a downlink control information (DCI) with either configured demodulation reference signal (DMRS) or channel state information reference signal (CSI-RS) can be used to reserve the shared resources for the protection of the receiver. UE transmission of sounding reference signals (SRS), triggered by the base station, can additionally be used to provide protection of the UEs to be scheduled. In one example aspect, the base stations would monitor for the reservation signals from other operators. In such aspects, the secondary (non-assigned) priority operators would be allowed to use the shared resources for downlink traffic.

In various aspects of the present disclosure, neighboring base stations that belong to different operators would monitor for each other's broadcast medium reservation signal (e.g., DMRS, CSI-RS, etc.). Where the medium reservation signal takes the form of a broadcast DMRS, the DMRS sequences and resources would be agreed upon for designation of medium reservation. DMRS is typically transmitted in symbol <NUM>, which may provide more time for processing and scheduling for the secondary operator(s). Alternatively, where CSI-RS is used for the medium reservation signal, less time may be available for processing at the receiving base stations. However, CSI-RS based measurement configuration can be reused, in which the measurements may be performed by neighboring base stations instead of UEs. When operating in the <NUM> spectrum, the measurement configuration may be exchanged through a CBRS shared access server, instead of over the air signaling when the base station configures the UE. Moreover, while there may be no filtering, the presence and strength of the signal may be determined in a single short detection operation,.

On the UE signaling, a base station may monitor for the SRS from the UEs served by base stations of other operators. SRS configurations may be exchanged among the different operators through a CBRS shared access server. According to aspects of the present disclosure, multiple SRS resources can be configured, such that at a first, UE-specific SRS resource set may be configured for regular sounding operation, and, at least, a second SRS resource set may be configured for coexistence signaling. Additionally, each SRS resource set can be separately power controlled and configured using separate power control reference signaling. SRS can be transmitted at full power or may be power controlled to specifically target a neighboring base station. SRS transmitted according to the various aspects herein may be triggered in advance, such that SRS from UEs belonging to an assigned priority operator that require protection can be transmitted within the reservation slot. Thus, according to the aspects of the present disclosure, a sharing technique is provided for sharing of spectrum between multiple networks in which certain networks have priority over others.

It should be noted that, while some example aspects may be discussed with respect to the <NUM> spectrum, the various aspects of the present disclosure are not limited to a single use case. The general sharing techniques provided herein may be applicable to any spectrum sharing scenario where one network has a higher priority than another.

<FIG> is a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to UE <NUM> as illustrated in <FIG> is a block diagram illustrating UE <NUM> configured according to one aspect of the present disclosure. UE <NUM> includes the structure, hardware, and components as illustrated for UE <NUM> of <FIG>. For example, UE <NUM> includes controller/processor <NUM>, which operates to execute logic or computer instructions stored in memory <NUM>, as well as controlling the components of UE <NUM> that provide the features and functionality of UE <NUM>. UE <NUM>, under control of controller/processor <NUM>, transmits and receives signals via wireless radios 1200a-r and antennas 252a-r. Wireless radios 1200a-r includes various components and hardware, as illustrated in <FIG> for UE <NUM>, including modulator/demodulators 254a-r, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, and TX MIMO processor <NUM>.

At block <NUM>, a UE obtains a resource configuration, wherein the resource configuration identifies a plurality of SRS resources including at least a sounding set of SRS resources and a coexistence set of SRS resources. According to aspects of the present disclosure, the different SRS resource sets are associated with the function they serve. Thus, the resources assigned to the coexistence set may be known to other nodes as being associated with a channel reservation signal. For example, a UE, such as UE <NUM>, obtains a resource configuration, which may be obtained via a transmission received from a serving base station over antennas 252a-r and wireless radios 1200a-r and stored, in memory <NUM>, at SRS resource configurations <NUM>, or pre-existing at SRS resource configurations <NUM> from the manufacturer. The different configurations within SRS resource configurations <NUM> may identify many different types of SRS and their associated resources, such as normal sounding signal SRS or coexistence SRS for reserving access to a shared communication channel.

At block <NUM>, the UE receives a trigger signal from a serving base station in communication with the UE over a shared spectrum shared between at least one or more priority license users. For example, UE <NUM>, may receive the trigger signal via antennas 252a-r and wireless radios 1200a-r. The trigger signal identifies to UE <NUM>, under control of controller/processor <NUM>, to initiate actions to compete for the shared spectrum. UE <NUM> may therefore execute shared access logic <NUM>, stored in memory <NUM>. The execution environment of shared access logic <NUM> provides for UE <NUM> to begin reservation of the shared channel. In one example implementation, the trigger signal may be a communication grant, such as a downlink grant for downlink transmissions or an uplink grant to schedule and allocate resources for uplink transmissions, or both. The trigger signal may also be implemented as a dedicated signal for triggering the coexistence operation.

At block <NUM>, the UE transmits, in response to the trigger signal, an SRS signal using the coexistence set of SRS resources. The trigger signal triggers UE <NUM> to begin coexistence operations, such as by transmitting a channel reservation signal. Thus, within the execution environment of shared access logic <NUM>, UE <NUM> executes SRS generator <NUM>, in memory <NUM>, in response to the trigger signal. Because the trigger signal triggers the shared access operations, UE <NUM>, under control of controller/processor <NUM>, uses the configured resources in SRS configuration resources <NUM> to generate a coexistence SRS as a channel reservation signal. The channel reservation signal according to the aspects of the present disclosure are implemented using the SRS signaling with the coexistence set of SRS resources. UE <NUM> may then transmit the coexistence SRS generated by SRS generator <NUM> via wireless radios 1200a-r and antennas 252a-r.

At block <NUM>, the UE communicates with the serving base station. After transmitting the channel reservation SRS signals using the coexistence set of SRS resources, communications may proceed, whether granted through the trigger signal or granted in a separate transmission grant for either uplink communication, downlink communication, or both in the COT portion of the current frame. UE <NUM> may then communicate with the serving base station either through uplink or downlink transmissions via wireless radios 1200a-r and antennas 252a-r.

<FIG> is a block diagram illustrating shared communication between network entities of two PAL operators, the network entities, base stations 105a-105b and UEs 115a-115b, configured according to one aspect of the present disclosure. Communication streams <NUM>-62a represent communications over the same shared frequency band between base stations 105a-105b and UEs 115a-115b, respectively. Base station 105a and UE 115a communicate via a first operator (Operator <NUM>), which is assigned priority access to the shared frequency band during frame <NUM>. Base station 105b and UE 115b communicate via a second operator (Operator <NUM>), which is the non-assigned priority operator for the shared frequency band in frame <NUM>. Communication stream <NUM> is the communication as transmitted from base station 105a, while communication stream <NUM> is the communication as transmitted from UE 115a. Communication streams <NUM> is the communication as transmitted from base station 105b, while communication stream 62a is an alternative communication as transmitted from base station 105b.

Access to the shared frequency band is governed by priority-based access between Operators <NUM> and <NUM>, with Operator <NUM> having priority during frame <NUM>. When there is data to communicate between base station 105a and UE 115a, whether downlink data, uplink data, or both, base station 105a transmits a reservation signal (e.g., DCI of either DMRS or CSI-RS, etc.) during reservation slot <NUM>. UE 115a may respond with its reservation signal SRS using the coexistence SRS resources set. Base station 105b, of Operator <NUM>, monitors the shared frequency band during reservation slot <NUM> for any reservation signals from Operator <NUM> entities. If base station 105b detects either the reservation signal DCI from base station 105a or the coexistence SRS transmitted by UE 115a, it will refrain from transmission during COT <NUM> of frame <NUM>, as illustrated in communication stream <NUM>. Otherwise, if base station 105b does not detect either the reservation signal DCI from base station 105a or the coexistence SRS transmitted by UE 115a, it may transmit downlink data after transmitting its own DCI during COT <NUM> of frame <NUM>, as illustrated in alternative communication stream 62a.

In order to guarantee no interference to Operator <NUM>, any HARQ/CSI feedback from UE 115b can be delayed and transmitted on guaranteed resources, such as exclusive resources <NUM> (<FIG>). UE 115b may delay HARQ feedback though receipt of DCI signaling of different kl values. The transmitted k1 values may provide for all HARQ feedback to be transmitted in the last slot. Alternatively, the HARQ feedback may also be delayed to the next reservation slot, since DMRS or CSI-RS and SRS are utilized for coexistence in the reservation slots.

<FIG> is a block diagram illustrating time division multiplex (TDM) sharing of shared frequency band <NUM> by base stations 105a-105b and UEs 115a-115b, operated by two different operators, respectively, and each configured according to one aspect of the present disclosure. Shared frequency band <NUM> includes multiple frames each having guaranteed resources, such as reservation slots <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and shared resources, such as COTs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, using an NR licensed configuration according to one aspect of the present disclosure. A network shared access server, SAS <NUM>, coordinates the resources by allocating both the resources and assigning priority to each frame. For example, SAS <NUM> assigns priority to Operator <NUM> in the frames including reservations slots <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and COTs <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and assigns priority to Operator <NUM> in the frames including reservation slots <NUM>, <NUM>, <NUM>, and <NUM> and COTs <NUM>, <NUM>, <NUM>, and <NUM>. In addition to coordination of resources for transmission of SSB, SI, paging, RACH procedure, it is beneficial also to coordinate the use of SRS and DCI resources (e.g., DMRS and/or CSI-RS ports).

In one example of operation, base station 105a transmit the reservation trigger signal via DCI during reservation slot <NUM>. UE 115a responds with a reservation response signal, SRS, using the coexistence set of SRS resources. As discussed above, UE 115a may be configured for at least two different sets of SRS resources: a sounding set, which may be used for regular sounding reference signals (SRS), and a coexistence set to be used for reservation signals. UE 115a may further be signaled separately to use different transmission powers for either regular SRS or reservation signal SRS. For example, UE <NUM> (<FIG>) may execute transmit power control logic <NUM>, stored in memory <NUM>, to separately control the transmit power of the SRS triggered for transmission, either regular SRS or reservation signal SRS. Base station 105b knows to monitor shared frequency band <NUM> for the DCI from base station 105a. It also knows which set of SRS resources are the coexistence set and, therefore, may monitor the coexistence set of SRS resources for the reservation signal SRS transmitted by UE 115a.

In NR Release <NUM>, the HARQ timing may be set to K1 ≤ <NUM>. This implies a maximum COT, n, of <NUM> or <NUM> slots for the assigned priority user. Because the non-assigned priority user may monitor for priority transmissions in the first slot, overhead for such non-assigned priority users may be l/n slots. Moreover, where two or more operators time division share access to a shared channel, such as shared frequency band <NUM>, HARQ timing for acknowledgements may not support K1 of <NUM>. For example, acknowledgement for transmissions in COT <NUM> by base station 105a may not be located in the next slot because base station 105a, as communicating through Operator <NUM>, has opportunistic access in the next slot. Instead, the minimum K1 value would place the acknowledgement of transmissions in COT <NUM> to the next slot for which Operator <NUM> has priority, such as the slot containing reservation slot <NUM> and COT <NUM>. The acknowledgement may either be transmitted in an available slot of COT <NUM> or may be transmitted in the guaranteed resources of reservation slot <NUM>. Similarly, triggering of SRS may also not support a timing of K2 = <NUM>, if a different operator has priority in the following slot. As such, SRS triggering may provide the K2 timing for transmission in the next slot for which the operator of the SRS scheduled UE has assigned priority access. In certain instances, while a slot is assigned to the assigned priority user (Operator <NUM>), no communication may occur (e.g., slots <NUM> and <NUM>), where no data and no control signals are transmitted. Further in such idle slots (slots <NUM> and <NUM>), the non-assigned priority user (Operator <NUM>) may opportunistically attempt access if data is available for communication.

<FIG> is a block diagram illustrating shared communication between network entities of two PAL operators, the network entities, base stations 105a-105b and UEs 115a-115b, configured according to one aspect of the present disclosure. Each of communication streams <NUM>-<NUM> is the communication stream as seen by each of the communication pairs of the same frequency resources. According to the illustrated aspect, in order to enable UE 115b, of Operator <NUM>, to transmit on the shared resources, UE 115b may monitor for reservation signals from the other operator(s). Thus, both base station 105b and UE 115b monitor reservation slot <NUM> for any reservation signals at <NUM> and <NUM> in communication streams <NUM> and <NUM>, respectively, from either of base station 105a and UE 115a, of Operator <NUM>. The configured UEs, such as UE <NUM>5b with data for uplink transmission, would monitor reservation signals transmitted in reservation slot <NUM> from base station 105a or UE 115a. UE 115b monitors for the reservation signals to ensure that its transmission on the shared resources will not negatively impact communications channels of either base station 105a or UE 115a. UE 115b monitors the configured coexistence SRS resource set at <NUM> if allowed to transmit on the shared resources. In addition, UE 115b would monitor for reservation signals at <NUM> from base station 105a (e.g., CSI-RS or DMRS from base station 105a).

While Operator <NUM> has assigned priority to the shared resources, when no reservation signals are detected in reservation slot <NUM>, base station 105b, of Operator <NUM>, can transmit a DCI in a subsequent mini slot, mini slot <NUM> of slot <NUM>. The DCI at mini slot <NUM> provides reservation and grant of downlink transmission (DL Tx) of communication stream <NUM> to UE 115b. Transmission of the DCI by base station 105b at mini slot <NUM> may also trigger UE 115b, if ready with uplink data, to transmit coexistence SRS in slot <NUM> of communication link <NUM>. Base station 105b may schedule UE 115b for uplink transmissions in COT <NUM> with an uplink grant DCI at mini slot <NUM>. For both non-assigned priority network entities to monitor for reservation signals of the assigned priority network entities, the overhead would be <NUM>/n slots for non-assigned priority user uplink transmissions.

The lowest priority users (e.g.,GAA users) may also share spectrum resources in the CBRS/<NUM> band with PAL users. Such non-exclusive license holders may also be assigned exclusive or guaranteed resources for critical overhead signals and channels. In one example aspect, when operating within the <NUM> spectrum, the CBRS shared access servers may coordinate such guaranteed resources for SSBs, SI, paging signals, PRACH resources, and the like, for the GAA users. Relatively small overhead may be used when smaller numbers of operators share the frequency band at any given geographical location. GAA users may provide for possible modes of operation due to flexible configurations for these resources in NR, with coordination of GAA users possible in both the time and frequency domains.

Sharing of resources by each GAA user may be implemented using listen before talk (LBT) NR shared spectrum (SS) procedures. The method of sharing may be similar to the sharing mechanism between PAL, users, but the use of LBT techniques allows for more aggressive reuse of resources. GAA users vying for the same shared resources may use pre-coded SRS for interference alignment when possible and/or receiver based messaging or energy-only LBT procedures or synchronization and FBE-like sensing. GAA users from different operators may cause residual interference to each other after the LBT NR SS procedure is performed due to access frequency assignment, timing, and the like. However, when operating within CBRS/<NUM>, the potential residual interference may be more effectively minimized by assigning orthogonal resources to the nearby nodes.

<FIG> is a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to base station <NUM> as illustrated in <FIG> is a block diagram illustrating base station <NUM> configured according to one aspect of the present disclosure. Base station <NUM> includes the structure, hardware, and components as illustrated for base station <NUM> of <FIG>. For example, base station <NUM> includes controller/processor <NUM>, which operates to execute logic or computer instructions stored in memory <NUM>, as well as controlling the components of base station <NUM> that provide the features and functionality of base station <NUM>. Base station <NUM>, under control of controller/processor <NUM>, transmits and receives signals via wireless radios 1300a-t and antennas 234a-t. Wireless radios 1300a-t includes various components and hardware, as illustrated in <FIG> for base station <NUM>, including modulator/demodulators 232a-t, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, and TX MIMO processor <NUM>.

At block <NUM>, a base station determines a communication operation between the base station and one or more served UEs. The communication operation may be uplink communication as requested by the UE or downlink communications triggered by receive of data for downlink. For example, a base station, such as base station <NUM>, may determine a communication operation via uplink/downlink communication <NUM>, in memory <NUM>. Uplink/downlink communication <NUM> may include a downlink buffer that indicates downlink data for transmission to one of the served UEs, or may include scheduling logic for response to a scheduling request from a served UE to schedule and grant uplink communication. Base station <NUM>, under control of controller/processor <NUM>, executes shared access logic <NUM>, in memory <NUM>. The execution environment of shared access logic <NUM> provides for base station <NUM> to compete for access to the shared communication channel.

At block <NUM>, the base station monitors for radio frequency (RF) energy on a communication channel at a beginning of an LBT window of a current frame in a shared spectrum shared between at least one or more opportunistic general authorized users, wherein the monitoring occurs after a back-off operation executed by the base station. In an energy-based LBT procedure according to the aspects of the present disclosure, base station <NUM> monitors the shared resources for RF energy above a minimum threshold value. If such energy is detected above the threshold, base station <NUM> would conclude that the channel is occupied and begin the LBT procedure again. To monitor for RF energy, within the execution environment of shared access logic <NUM>, base station <NUM> receives RF energy via antennas 234a-t and wireless radios <NUM>. Base station <NUM> may execute energy detection logic <NUM>, stored in memory <NUM>. The execution environment of energy detection logic <NUM> provides measurement parameters for determining the threshold level of energy between where the shared channel is considered occupied and the channel is considered available.

At block <NUM>, the base station transmits an LBT trigger signal in response to detection of no RF energy above a minimum energy threshold at the beginning of the LBT window. When no RF energy is detected above the minimum threshold as identified within the execution environment of energy detection logic <NUM>, base station <NUM>, executes, under control of controller/processor <NUM>, LBT procedure <NUM>, in memory <NUM>. The execution environment of LBT procedure <NUM> provides for managing access to the shared channel using LBT. For example, base station <NUM>, within the execution environment of LBT procedure <NUM>, transmits an LBT trigger signal via wireless radios 1300a-t and antennas 234a-t, to a served UE, not only to trigger the served UE to send a channel reservation response signal, but to indicate to competing neighbors that the channel is intended to be occupied.

At block <NUM>, the base station receives an LBT trigger response signal from the one or more served UEs, wherein the RF energy on the communication channel remains above the minimum energy threshold for a remainder of the LBT window. After base station <NUM> transmits the trigger signal, the served UE responds with a trigger response signal which also acts as a channel reservation signal on the shared resources. Base station <NUM> receive the trigger response signal via antennas 234a-t and wireless radios 1300a-t. RF blocking energy may be transmitted onto the shared resources through blocking signals transmitted either by base station <NUM>, within the execution environment of LBT procedure <NUM>, the served UE, or both, until the end of the LBT window. The blocking signals would be detected by most other competing neighbor nodes attempting access to the channel during their respective LBT procedures and preserves reservation of the shared channel to base station <NUM> and its served UEs.

At block <NUM>, the base station participates in communication with the one or more UEs during a channel occupancy time (COT) of the current frame after the LBT window. After winning the channel in the LBT window, communications between base station <NUM> and the served UE, whether uplink, downlink, or both, may begin in the COT portion of the current frame.

<FIG> is a block diagram illustrating GAA users, including base station 105a and UE 115a, of Operator <NUM>, and base station 105b and UE 115b, of Operator <NUM>, each configured according to one aspect of the present disclosure and sharing access to a <NUM> band communication network. Each of base stations <NUM>05a and <NUM>05b compete for access to the shared frequency band, frequency <NUM>. At LBT slot <NUM> base station 105a executes a pseudo random back off <NUM>, which can be coordinated among operators though the CBRS shared access server or may be completely random and generated at base station 105a. After pseudo random back off <NUM>, base station 105a transmits a trigger signal <NUM><NUM> in communication stream <NUM>. UE 115a responds with a channel reservation response signal, blocking, in communication stream <NUM>. The trigger response delay may be minimized in order to minimize the likelihood of collisions.

According to aspects of the present disclosure, the LBT procedure used by GAA users competing for access to the shared resources is an energy-based LBT. Thus, during pseudo random back off <NUM>, base station 105a monitors for RF energy on frequency <NUM>. If RF energy is detected above a minimum threshold value, base station 105a would not transmit trigger signal <NUM>, and, instead, would execute another pseudo random back off (not shown). However, as illustrated, base station 105a does not detect RF energy above the minimum threshold value during pseudo random back off <NUM>.

In order to prevent other GAA users from gaining access to the shared frequency band, channel blocking may be used by either base station 105a, UE 115a, or both. Base station 105a and/or UE 115a may block the channel of frequency <NUM> by continuously transmitting a signal (e.g., blocking signal, channel reservation response signal, etc.) until the end of LBT slot <NUM>. The transmitter (base station 105a) can block the medium after detecting the response, blocking, from the receiver (UE 115a) in order to protect reception of the acknowledgement. Thus, if base station 105b would attempt access to frequency <NUM> during LBT slot <NUM>, it would listen and measure the RF energy of the blocking signals transmitted by either or both of base station 105a or UE 115a. After securing the channel in LBT slot <NUM>, base station 105a may make any downlink transmissions in communication stream <NUM> during COT <NUM> on frequency <NUM> and UE 115a may make any uplink transmissions in communication stream <NUM> during COT <NUM> on frequency <NUM>.

Energy-based LBT allows channel blocking of two nodes using different frequency resources as there may be leakage of energy into an adjacent band. However, receiver blocking may be technology specific and optional, depending on whether overhead minimization is of primary concern.

At LBT slot <NUM>, base station 105b, of Operator <NUM>, may attempt to access the shared frequency band, frequency <NUM>, after executing pseudo random back off <NUM>. Base station 105b transmits trigger signal <NUM> in communication stream <NUM>, while UE 115b responds with channel reservation response signal, blocking, in communication stream <NUM>. Either one or both of transmitter or receiver blocking signals by either or both of base station 105b or UE 115b secure the channel of frequency <NUM> with RF energy above the minirnum threshold value for the duration of LBT slot <NUM>. Once the channel is secured in LBT slot <NUM>, base station 105b and UE 115b can participate in communications (e.g., downlink and/or uplink transmissions) during COT <NUM>.

It should be noted that inter-technology coexistence may be facilitated; however, such coexistence would be possible by synchronizing the LBT windows of each technology node.

Access outside the synchronized contention (LBT) windows can be allowed if the LBT window of the transmitting node was synchronized prior to access and the transmitting node finds the COT empty. Referring back to <FIG>, when new data arrives at base station 105a in the middle of COT <NUM>, where all transmissions by either of base station 105b or UE 115b have ended in COT <NUM>, base station 105a performs the energy-based LBT procedure beginning with pseudo random back off <NUM>, followed by trigger signal <NUM>. UE 115a responds by transmitting channel reservation response signal <NUM>, after which base station 105a may begin its downlink transmission <NUM>. However, regardless of the amount of data that base station 105a has to transmit, the opportunistic downlink transmission <NUM> would stop at the end of COT <NUM>. Base station 105a may begin a new energy-based contention procedure at the next synchronized LBT window.

It should be noted that, when the nodes from different operators competing for the same shared frequency spectrum are not synchronized, receiver protection through blocking signals may not be enabled.

<FIG> is a block diagram illustrating a sharing scheme for sharing frequency spectrum between multiple PAL users, base stations 105a-105b and UEs 115a-115b, and multiple GAA users, base stations 105c, <NUM>, 105e, and UEs 115c, 115d, and <NUM> each configured according to aspects of the present disclosure. According to the illustrated aspect of the present disclosure the assigned bandwidth for sharing may be divided into two bandwidth partitions, frequency <NUM> and frequency <NUM>. Each of frequency <NUM> and <NUM> may employ time division multiplex (TDM), frequency division multiplex (FDM), a combination of TDM and FDM, and the like. The PAL users, base stations 105a-105b and UEs 115a-115b, use the listen-based sharing mechanisms, as illustrated and described with respect to <FIG> in order to manage access to frequency <NUM>, while GAA users, base stations 105c, <NUM>, 105e, and UEs 115c, 115d, and <NUM>, use the energy-based LBT NR SS sharing mechanism, as illustrated and described with respect to <FIG> in order to manage access to frequency <NUM>. As illustrated, frequency <NUM> provides TDM access, while frequency <NUM> provides a combination of TDM and FDM. Because the shared frequency resources have been divided into two different bandwidth parts, there is sufficient frequency separately for both sets of users to compete and access the shared resources, while protecting critical signaling, such as SSB, SI, paging, and PRACH resources, with guaranteed resource allocations for both PAL and GAA users.

The functional blocks and modules in <FIG> and <FIG> may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration,.

By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor, Also, a connection may be properly termed a computer-readable medium.

Claim 1:
A method of wireless communication for authorized shared access, comprising:
obtaining (<NUM>), by a user equipment, UE (<NUM>), a resource configuration (<NUM>), wherein the resource configuration identifies a plurality of sound reference signal, SRS resources including at least a sounding set of SRS resources and a coexistence set of SRS resources, for reserving access to a shared communication channel, the coexistence set of SRS resources being associated with a channel reservation signal;
receiving (<NUM>), by the UE, a listen-before-talk, LBT, trigger signal from a serving base station over a shared spectrum shared between at least one or more priority access license, PAL, users, the LBT trigger signal causing the UE (<NUM>) to initiate actions to contend for the shared spectrum;
transmitting (<NUM>), by the UE in response to the LBT trigger signal, an SRS using the coexistence set of SRS resources; and
communicating (<NUM>), by the UE, with the serving base station on the shared communication channel.