Patent Description:
Wireless communication networks are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication networks may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems.

For example, fifth generation (<NUM>) New Radio (NR) communications technology is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, <NUM> communications technology includes enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with strict requirements, especially in terms of latency and reliability; and massive machine type communications for a very large number of connected devices and typically transmitting a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, there exists a need for further improvements in <NUM> communications technology and beyond.

As the number of packets being transmitted increases with <NUM>, techniques are needed to provide efficient and improved process when communicating frames during wireless communications. In certain instances, as the next generation of wireless communications come into existence, more flexible transmissions may be desired in order to ensure adequate or improved levels of wireless communications. Thus, improvements in communication during wireless communication are desired.

<NPL>) proposes a uplink common control channel, where a common channel and sequence are reserved for UEs to provide feedback on the uplink.

<CIT> discloses a method is provided for operating a base station serving multiple mobile stations within a predetermined spatial area. The base station includes an adaptive antenna array and forward link beam forming circuitry for forming simultaneous multiple forward link beams, each beam being spatially directed and adapted to serve one of the multiple mobile stations. The base station receives packets of digital traffic data and sends the packets to the mobile stations via the adaptive antenna array.

<CIT> discloses a base station apparatus which communicates in uplink with a mobile station using a random access channel is disclosed. The base station apparatus includes a preamble-sequence securing unit which secures, as preamble sequences not to be used in signal transmission, some preamble sequences of multiple preamble sequences used in the random access channel; and an interference power estimating unit which estimates interference power using the preamble sequences not to be used in the signal transmission.

Embodiments are set out in the appended dependent claims.

Various aspects and features of the disclosure are described in further detail below with reference to various examples thereof as shown in the accompanying drawings.

The features, nature, and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout, where dashed lines may indicate optional components or actions, and wherein:.

In an aspect, the term "component" as used herein may be one of the parts that make up a system, may be hardware or software, and may be divided into other components.

The present aspects generally relate to a frame structure for new radio shared spectrum. Specifically, conventional implementations may be unsuited for facilitating communication between user equipments (UEs) and network entities supporting multiple operators. For example, an operator may be or otherwise correspond to a provider of wireless service. In particular, conventional implementations may either inefficiently utilize available spectrum associated with a particular radio access technology (RAT) across multiple operators, or may be unable to utilize available spectrum in conjunction with another operator. As such, a frame structure that allows for or otherwise facilitates multiple operator communication may be desirable. For instance, the frame structure may provide shared medium access by multiple operators in a new radio shared spectrum system.

Even more, medium access in various spectrums such as, but not limited to, an unlicensed spectrum, may utilize a listen-before-talk (LBT) scheme to monitor an unlicensed or shared channel so as to prevent or mitigate interference with another RAT and/or another operator. For instance, LBT may be performed via energy detection or preamble detection, which in some aspects, may utilize random backoff. However, performing LBT in an multi-RAT environment including various operators may encounter a number of drawbacks such as high overhead associated with random backoff, chances of collision if a continuous carrier aggregation (CCA) counter of at least two network entities reaches zero at the same CCA slot, issues associated with hidden network entities and spatial reuse. Accordingly, to overcome the above drawbacks, synchronization may be provided across various network entities (e.g., eNBs). In particular, to achieve such synchronization, the present aspects provide a priority-based medium contention scheme for one or more frequency bands that may or may not have an LBT scheme. According to the invention, the scheme includes a reservation preamble associated with a particular operator that is transmitted by a network entity to notify one or more network entities (e.g., eNBs) of other operators that the network entity will occupy the medium or channel during a given transmission opportunity (e.g., during a time duration of a number of symbols). In some instances, certain network entities may have higher assigned priorities than other network entities.

Accordingly, in some aspects, the present methods and apparatuses may provide an efficient solution, as compared to conventional solutions, by utilizing reservation preambles associated with a distinct operator for announcing to other operators a reservation of at least one transmission opportunity of a given frame in a new radio shared spectrum. In other words, in the present aspects, a UE may efficiently and effectively determine whether a first reservation preamble of a first operator is received on a first time slot of multiple time slots of a downlink channel from a first network entity, and transmit a second reservation preamble of the first operator on an uplink channel to the second network entity based on a determination that the first reservation preamble of the first operator is received. Further, the present aspects provide one or more mechanisms for a first network entity to generate a first reservation preamble of a first operator based on at least one of a compressed representation in a signal space, a basis function of the signal space, or a constant amplitude zero autocorrelation waveform (CAZAC) sequences, and transmit, on a first timeslot of multiple time slots of a downlink channel, the first reservation preamble of the first operator to at least a UE.

Additional features of the present aspects are described in more detail below with respect to <FIG>.

It should be noted that the techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to <NUM> networks or other next generation communication systems).

Referring to <FIG>, in accordance with various aspects of the present disclosure, an example wireless communication network <NUM> includes at least one UE <NUM> with a modem <NUM> having a preamble relay component <NUM> that may be configured to facilitate reception of a reservation preamble according to a new radio shared spectrum frame structure on one or more downlink communication channels from a network entity such as base station <NUM> in a wireless communication network <NUM>. Further, the at least one base station <NUM> includes a modem <NUM> having a reservation preamble transmission component <NUM> that transmit, via communication channel <NUM>, a reservation preamble of a particular operator based on an indication that the particular operator will transmit data on at least one transmission opportunity of a frame <NUM>. For example, the preamble relay component <NUM> may receive, on a downlink channel from a first network entity (e.g., base station <NUM>), a first reservation preamble <NUM> of a first operator <NUM>, and transmit, on an uplink channel (e.g., communication channel <NUM>), the second reservation preamble <NUM> of the first operator <NUM> to the second network entity (e.g. base station <NUM>). Further, the reservation preamble transmission component <NUM> may generate a first reservation preamble <NUM> of a first operator <NUM> based on at least one of a compressed representation in a signal space, a basis function of the signal space, or a constant amplitude zero autocorrelation waveform (CAZAC) sequences.

In an aspect, the UE <NUM> may include the preamble relay component <NUM>, which may be configured to facilitate reception of a reservation preamble according to a new radio shared spectrum frame structure on one or more downlink communication channels from a network entity such as base station <NUM>. For example, with reference to <FIG>, a reservation preamble associated with a particular operator (e.g., first operator <NUM>) may inform or otherwise indicate to one or more network entities (e.g., base station <NUM>) associated with different operators that the base station <NUM> will transmit data on a transmission opportunity (e.g., formed of a number of subframes of a consistent time duration). However, in some cases, network entities (e.g., base station <NUM>) may be hidden from or remain undetected by the transmitting network entity, i.e. base station <NUM>, and as such, the reservation preamble may not be received by the potentially interfering network entity (e.g., base station <NUM>). As such, UE <NUM> may transmit the reservation preamble to the one or more network entities (e.g., base station <NUM>) that may potentially interfere with the transmission of the transmission opportunity associated with the reservation preamble by the network entity. In some aspects, UE <NUM> may transmit one or more transmission opportunities within a frame <NUM> in accordance with a frame structure that facilities transmission on subframes or symbols associated with multiple or different operators, as illustrated in <FIG>.

Specifically, to facilitate network synchronization, preamble relay component <NUM> may be configured to determine whether a first reservation preamble <NUM> of a first operator <NUM> is received on a first time slot of multiple time slots of a downlink channel <NUM> from a first base station <NUM> (e.g., which may be a serving eNB). For example, determination component <NUM> may determine whether a first reservation preamble <NUM> of a first operator <NUM> is received by partitioning a receiver timeframe into multiple segments each with a maximum time duration, accumulating one or more of the multiple segments corresponding to a portion of the first reservation preamble <NUM>, applying a non-coherent cross-correlation operation to each of the accumulated one or more segments, and combining each output of the non-coherent cross-correlation operations to trigger detection of the first reservation preamble <NUM>. In some aspects, the non-coherent cross-correlation operation corresponds to at least one of a time-domain non-coherent cross-correlation operation or a frequency-domain non-coherent cross-correlation operation.

In some aspects, UE <NUM> and/or preamble relay component <NUM> may be configured to determine a ratio of a time duration of the second reservation preamble <NUM> and a time duration of a switching gap. In some examples, the second reservation preamble <NUM> is aligned with a slot boundary of the first time slot. In an example, a sequence of the second reservation preamble <NUM> corresponds to at least one of a punctured or a phase rotated waveform of the first reservation preamble <NUM>.

In an aspect, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit a second reservation preamble <NUM> of the first operator <NUM> on an uplink channel <NUM> to the second base station <NUM> based on a determination that the first reservation preamble <NUM> of the first operator <NUM> is received. In an example, transceiver <NUM> may transmit the second reservation preamble <NUM> at a transmission time corresponding to a time of completion of the determination that the first reservation preamble <NUM> of the first operator <NUM> is received. In some examples, an end time of the second reservation preamble <NUM> corresponds to an end time of the first reservation preamble <NUM>, the end time of the second reservation preamble <NUM> and the end time of the first reservation preamble <NUM> being aligned with a slot boundary of the first time slot.

In some aspects, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit the second reservation preamble <NUM> as a single frequency network (SFN) transmission based on the UE <NUM> and the first base station <NUM> both corresponding to the first operator <NUM>.

In some aspects, the UE <NUM> includes a plurality of transmit antennas <NUM>-a to <NUM>-b. Further, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit, on the plurality of transmit antennas <NUM>-a to <NUM>-b, the second reservation preamble <NUM> by reusing an OFDM frame. Additionally, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit the second reservation preamble <NUM> based on a configurable transmit diversity scheme. For example, the configurable transmit diversity scheme includes at least one of a tone interleaving in a frequency domain, sub-band interleaving in the frequency domain, or a cyclic shift diversity in a time domain.

Further, the UE <NUM>, and in particular preamble relay component <NUM> may configure the frame structure of frame <NUM> based on frame configuration information received from the base station <NUM>. For example, preamble relay component <NUM> may be configured to receive an indication including a number of operators from the base station <NUM>, and determine a transmission opportunity structure including at least one uplink timeslot based on the number of operators from the base station <NUM>. Accordingly, preamble relay component <NUM> may be configured to transmit the second reservation preamble <NUM> of the first operator <NUM> to the second network entity during the at least one uplink listen-before-talk timeslot. Further, UE <NUM>, and in particular preamble relay component <NUM> may be configured to receive at least one of a duration or a priority of one or more transmission opportunities, and forgo monitoring of one or more timeslots.

In an aspect, the base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit, on a first timeslot of multiple time slots of a downlink channel <NUM>, the first reservation preamble <NUM> of the first operator to at least a UE <NUM>. For example, transceiver <NUM> may transmit a plurality of uniformly spaced pilot tones corresponding to the first reservation preamble <NUM>. For example, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit the first reservation preamble <NUM> as a single frequency network (SFN) transmission based on the UE <NUM> and the first base station <NUM> both corresponding to the first operator <NUM>. In another example, transceiver <NUM> may transmit data associated with the first operator <NUM> within a portion of a transmission opportunity on the downlink channel <NUM> in response to transmitting the first reservation preamble <NUM> of the first operator <NUM>. In some examples, the first reservation preamble <NUM> of the first operator <NUM> notifies the UEs served by the first base station <NUM> and at least one of a second base station <NUM> that the first base station <NUM> will access a channel <NUM> during the portion of the transmission opportunity. In other examples, the reservation preamble <NUM> may restrict access of one or more network entities including at least one of a second base station <NUM> to the portion of the transmission opportunity based on a determination that the first reservation preamble <NUM> of the first operator <NUM> has been transmitted by at least the first base station <NUM>.

In some aspects, the first network entity includes a plurality of transmit antennas <NUM>. Further, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit, on the plurality of transmit antennas <NUM>, the first reservation preamble <NUM> by reusing an OFDM frame. Additionally, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit the first reservation preamble <NUM> based on a configurable transmit diversity scheme. In an example, the configurable transmit diversity scheme includes at least one of a tone interleaving in a frequency domain, a sub-band interleaving in the frequency domain, or a cyclic shift diversity in a time domain.

In an aspect, the base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to receive, on the first timeslot of an uplink channel from the UE <NUM>, a second reservation preamble <NUM> of the first operator <NUM> in addition to receiving , on the first timeslot of the downlink channel <NUM>, the first reservation preamble <NUM> of the first operator <NUM> to at least the UE <NUM>. For example, a sequence of the second reservation preamble <NUM> corresponds to at least one of a punctured or a phase rotated waveform of the first reservation preamble <NUM>.

In an aspect, the base station <NUM> may include the reservation preamble transmission component <NUM>, which may be configured to transmit a reservation preamble of a particular operator based on an indication that the particular operator will transmit data on at least one transmission opportunity of a frame <NUM>. That is, reservation preamble transmission component <NUM> may notify or inform other network entities (e.g., second base station <NUM>) supporting various operators that may potentially interfere with transmission of transmission opportunities by the first base station <NUM>. In some aspects, the first reservation preamble <NUM> and the second operator reservation preamble <NUM> may notify one or more network entities including the base station <NUM> (e.g., non-serving eNB) that the base station <NUM> will transmit data on a channel during the portion of the transmission opportunity for a given operator.

Specifically, the reservation preamble transmission component <NUM> may be configured to control operator access to one or more transmission opportunities by determining whether a highest priority operator has elected not to transmit a corresponding reservation preamble. For example, in some aspects, the first operator <NUM> may have a highest priority level such that access to at least one transmission opportunity may be made without contention with other operators. If the first operator <NUM> elects to transmit data on the at least one transmission opportunity, reservation preamble transmission component <NUM> may be configured to notify or inform other network entities (e.g., base station <NUM>) supporting different operators that base station <NUM> plans on or will transmit data of the first operator <NUM> at the at least one transmission opportunity (e.g., so as to avoid or mitigate interference with the other network entities transmitting on the same frequencies).

In the event the first operator <NUM> foregoes the opportunity to transmit on the at least one transmission opportunity of the frame <NUM>, reservation preamble transmission component <NUM>, and more specifically determination component <NUM>, may be configured to determine whether a second operator <NUM> has elected to transmit data on the at least one transmission opportunity upon determining that the first operator <NUM> has not transmitted the first operator reservation preamble <NUM>. As such, reservation preamble transmission component <NUM> may be configured to transmit a second operator reservation preamble <NUM> to a distinct network entity of at least the first operator <NUM>, for example, based on a determination that the reservation preamble of the first operator <NUM> has not been transmitted to at least the second base station <NUM>.

Further, where first base station <NUM> supports a third operator, reservation preamble transmission component <NUM> may make a similar determination to determine whether the third operator may transmit an associated reservation preamble for access to the transmission opportunity. That is, when both the first operator <NUM> and the second operator <NUM> have determined or elected not to utilize the transmission opportunity, and correspondingly where the third operator does not detect transmission of neither first operator reservation preamble <NUM> nor second operator reservation preamble <NUM>, the third operator may or may not transmit an associated reservation preamble via reservation preamble transmission component <NUM>.

The wireless communication network <NUM> may include one or more base stations <NUM>, one or more UEs <NUM>, and a core network <NUM>. The core network <NUM> may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations <NUM> may interface with the core network <NUM> through backhaul links <NUM> (e.g., S1, etc.). The base stations <NUM> may perform radio configuration and scheduling for communication with the UEs <NUM>, or may operate under the control of a base station controller (not shown). In various examples, the base stations <NUM> may communicate, either directly or indirectly (e.g., through core network <NUM>), with one another over backhaul links <NUM> (e.g., X1, etc.), which may be wired or wireless communication links.

The base stations <NUM>/<NUM> may wirelessly communicate with the UEs <NUM> via one or more base station antennas. Each of the base stations <NUM>/<NUM> may provide communication coverage for a respective geographic coverage area <NUM>. In some examples, base stations <NUM>/<NUM> may be referred to as a base transceiver station, a radio base station, an access point, an access node, a radio transceiver, a NodeB, eNodeB (eNB), gNodeB (gNB), Home NodeB, a Home eNodeB, a relay, or some other suitable terminology. The geographic coverage area <NUM> for a base station <NUM>/<NUM> may be divided into sectors or cells making up only a portion of the coverage area (not shown). The wireless communication network <NUM> may include base stations <NUM>/<NUM> of different types (e.g., macro base stations or small cell base stations, described below). Additionally, the plurality of base stations <NUM>/<NUM> may operate according to different ones of a plurality of communication technologies (e.g., <NUM> (New Radio or "NR"), fourth generation (<NUM>)/LTE, <NUM>, Wi-Fi, Bluetooth, etc.), and thus there may be overlapping geographic coverage areas <NUM> for different communication technologies.

In some examples, the wireless communication network <NUM> may be or include one or any combination of communication technologies, including a new radio (NR) or <NUM> technology, a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) or MuLTEfire technology, a Wi-Fi technology, a Bluetooth technology, or any other long or short range wireless communication technology. In LTE/LTE-A/MuLTEfire networks, the term evolved node B (eNB) may be generally used to describe the base stations <NUM>/<NUM>, while the term UE may be generally used to describe the UEs <NUM>. The wireless communication network <NUM> may be a heterogeneous technology network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station <NUM>/<NUM> may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs <NUM> with service subscriptions with the network provider.

A small cell may include a relative lower transmit-powered base station, as compared with a macro cell, that may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by the UEs <NUM> with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access and/or unrestricted access by the UEs <NUM> having an association with the femto cell (e.g., in the restricted access case, the UEs <NUM> in a closed subscriber group (CSG) of the base station <NUM>, which may include the UEs <NUM> for users in the home, and the like). A micro cell may cover a geographic area larger than a pico cell and a femto cell, but smaller than a macro cell.

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A user plane protocol stack (e.g., packet data convergence protocol (PDCP), radio link control (RLC), MAC, etc.), may perform packet segmentation and reassembly to communicate over logical channels. For example, a MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat/request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and the base station <NUM>. The RRC protocol layer may also be used for core network <NUM> support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs <NUM> may be dispersed throughout the wireless communication network <NUM>, and each UE <NUM> may be stationary or mobile. A UE <NUM> may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may be a cellular phone, a smart 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 smart watch, a wireless local loop (WLL) station, an entertainment device, a vehicular component, a customer premises equipment (CPE), or any device capable of communicating in wireless communication network <NUM>. Additionally, a UE <NUM> may be Internet of Things (IoT) and/or machine-to-machine (M2M) type of device, e.g., a low power, low data rate (relative to a wireless phone, for example) type of device, that may in some aspects communicate infrequently with wireless communication network <NUM> or other LTEs. A UE <NUM> may be able to communicate with various types of base stations <NUM> and network equipment including macro eNBs, small cell eNBs, macro gNBs, small cell gNBs, relay base stations, and the like.

UE <NUM> may be configured to establish one or more wireless communication links <NUM> with one or more base stations <NUM>. The wireless communication links for channel reservation <NUM> shown in wireless communication network <NUM> may carry uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each wireless communication link <NUM> may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. In an aspect, the wireless communication links <NUM> may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type <NUM>) and TDD (e.g., frame structure type <NUM>). Moreover, in some aspects, the wireless communication links <NUM> may represent one or more broadcast channels.

Similarly, in an aspect, UE <NUM> may be configured to establish one or more wireless communication links <NUM> with one or more base stations <NUM>. The wireless communication links for channel reservation <NUM> shown in wireless communication network <NUM> may carry UL transmissions from a UE <NUM> to a base station <NUM>, or DL transmissions from a base station <NUM> to a UE <NUM>. For example, these UL transmissions may correspond to a communication link from UEs <NUM> served by the first network entity (e.g. the base station <NUM>) to the potential aggressor of the second network entity (e.g. the base station <NUM>).

In some aspects of the wireless communication network <NUM>, base stations <NUM>/<NUM> or UEs <NUM> may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations <NUM> and UEs <NUM>. Additionally or alternatively, base stations <NUM>/<NUM> or UEs <NUM> may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication network <NUM> may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation. The base stations <NUM> and UEs <NUM> may use spectrum up to Y MHz (e.g., Y = <NUM>, <NUM>, <NUM>, or <NUM>) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x = number of component carriers) used for transmission in each direction. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The wireless communications network <NUM> may further include base stations <NUM>/<NUM> operating according to Wi-Fi technology, e.g., Wi-Fi access points, in communication with UEs <NUM> operating according to Wi-Fi technology, e.g., Wi-Fi stations (STAs) via communication links in an unlicensed frequency spectrum (e.g., <NUM>). When communicating in an unlicensed frequency spectrum, the STAs and AP may perform a clear channel assessment (CCA) or listen before talk (LBT) procedure prior to communicating in order to determine whether the channel is available.

Additionally, one or more of base stations <NUM> and/or UEs <NUM> may operate according to a NR or <NUM> technology referred to as millimeter wave (mmW or mmwave) technology. For example, mmW technology includes transmissions in mmW frequencies and/or near mmW frequencies. Extremely high frequency (EHF) is part of the radio frequency (RF) in the electromagnetic spectrum. For example, the super high frequency (SHF) band extends between <NUM> and <NUM>, and may also be referred to as centimeter wave. Communications using the mmW and/or near mmW radio frequency band has extremely high path loss and a short range. As such, base stations <NUM> and/or UEs <NUM> operating according to the mmW technology may utilize beamforming in their transmissions to compensate for the extremely high path loss and short range.

<FIG> is a flow diagram illustrating examples of a method <NUM> related to detection of at least one reservation preamble in accordance with various aspects of the present disclosure. Although the operations described below are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Also, although the preamble relay component <NUM> is illustrated as having a number of subcomponents, it should be understood that one or more of the illustrated subcomponents may be separate from, but in communication with, the preamble relay component <NUM>, and/or each other. Moreover, it should be understood that any of actions or components described below with respect to the preamble relay component <NUM> and/or its subcomponents may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component specially configured for performing the described actions or components. The dashed lines surrounding one or more blocks may represent optional steps.

In an aspect, at block <NUM>, the method <NUM> may determine whether a first reservation preamble of a first operator is received on a first time slot of multiple time slots of a downlink channel from a first network entity. In an aspect, for example, the UE <NUM> and/or preamble relay component <NUM> may execute the determination component <NUM> to determine whether a first reservation preamble <NUM> of a first operator <NUM> is received on a first time slot of multiple time slots of a downlink channel <NUM> from a first base station <NUM>.

In some aspects, determination component <NUM> may determine whether a first reservation preamble <NUM> of a first operator <NUM> is received by partitioning a receiver timeframe into multiple segments each with a maximum time duration, accumulating one or more of the multiple segments corresponding to a portion of the first reservation preamble <NUM>, applying a non-coherent cross-correlation operation to each of the accumulated one or more segments, and combining each output of the non-coherent cross-correlation operations to trigger detection of the first reservation preamble <NUM>.

In some aspects, the non-coherent cross-correlation operation corresponds to at least one of a time-domain non-coherent cross-correlation operation or a frequency-domain non-coherent cross-correlation operation.

At block <NUM>, the method <NUM> may transmit a second reservation preamble of the first operator on an uplink channel to a second network entity based on a determination that the first reservation preamble of the first operator is received. In an aspect, for example, the UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit a second reservation preamble <NUM> of the first operator <NUM> on an uplink channel to a second base station <NUM> based on a determination that the first reservation preamble <NUM> of the first operator <NUM> is received.

In some aspects, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> (<FIG>) to transmit the second reservation preamble <NUM> at a transmission time corresponding to a time of completion of the determination that the first reservation preamble <NUM> of the first operator <NUM> is received.

In some aspects, an end time of the second reservation preamble <NUM> corresponds to an end time of the first reservation preamble <NUM>, the end time of the second reservation preamble <NUM> and the end time of the first reservation preamble <NUM> being aligned with a slot boundary of the first time slot.

In some aspects, although not shown, method <NUM> may include determining a ratio of a time duration of the second reservation preamble <NUM> and a time duration of a switching gap, wherein the second reservation preamble <NUM> is aligned with a slot boundary of the first time slot.

In some aspects, a sequence of the second reservation preamble <NUM> corresponds to at least one of a punctured or a phase rotated waveform of the first reservation preamble <NUM>.

In some aspects, the UE <NUM> includes a plurality of transmit antennas <NUM>. Further, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit, on the plurality of transmit antennas <NUM>, the second reservation preamble <NUM> by reusing an OFDM frame.

In some aspects, UE <NUM> and/or preamble relay component <NUM> may execute transceiver <NUM> to transmit the second reservation preamble <NUM> based on a configurable transmit diversity scheme.

In some aspects, the configurable transmit diversity scheme includes at least one of a tone interleaving in a frequency domain, sub-band interleaving in the frequency domain, or a cyclic shift diversity in a time domain.

In some aspects, although not shown, method <NUM> may include receiving an indication including a number of operators from the first base station <NUM>, and determining a transmission opportunity structure including the first timeslot based on the number of operators from the first base station <NUM>, wherein the number of operators includes a second base station <NUM> with a priority level less than the first base station <NUM>.

<FIG> is a flow diagram illustrating examples of a method <NUM> related to transmission of at least one reservation preamble, in accordance with the invention. Although the operations described below are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Also, although the reservation preamble transmission component <NUM> is illustrated as having a number of subcomponents, it should be understood that one or more of the illustrated subcomponents may be separate from, but in communication with, the reservation preamble transmission component <NUM>, and/or each other. Moreover, it should be understood that any of actions or components described below with respect to the reservation preamble transmission component <NUM> and/or its subcomponents may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component specially configured for performing the described actions or components. The dashed lines surrounding one or more blocks may represent optional steps.

At block <NUM>, the method <NUM> is configured to generate a first reservation preamble of a first operator based on at least one of a compressed representation in a signal space, a basis function of the signal space, or a CAZAC sequences. Correspondingly, the base station <NUM> and/or reservation preamble transmission component <NUM> is configured to execute the determination component <NUM> to generate a first reservation preamble <NUM> of a first operator <NUM> based on at least one of a compressed representation in a signal space, a basis function of the signal space, or a CAZAC sequences.

At block <NUM>, the method <NUM> is configured to transmit, on a first timeslot of multiple time slots of a downlink channel, the first reservation preamble of the first operator to at least a UE. Correspondingly, the base station <NUM> and/or reservation preamble transmission component <NUM> is configured to execute transceiver <NUM> to transmit, on a first timeslot of multiple time slots of a downlink channel <NUM>, the first reservation preamble <NUM> of the first operator to at least a UE <NUM>.

In some aspects, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit a plurality of uniformly spaced pilot tones corresponding to the first reservation preamble <NUM>.

In some aspects, the first network entity includes a plurality of transmit antennas <NUM>. Further, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit, on the plurality of transmit antennas <NUM>, the first reservation preamble <NUM> by reusing an OFDM frame.

In some aspects, network entity includes a plurality of transmit antennas. Further, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit the first reservation preamble <NUM> based on a configurable transmit diversity scheme.

In some aspects, the configurable transmit diversity scheme includes at least one of a tone interleaving in a frequency domain, a sub-band interleaving in the frequency domain, or a cyclic shift diversity in a time domain.

In some aspects, although not shown, method <NUM> may include transmitting , on the first timeslot of an uplink channel from the UE <NUM>, a second reservation preamble <NUM> of the first operator <NUM> in response to receiving , on the first timeslot of the downlink channel <NUM>, the first reservation preamble <NUM> of the first operator <NUM> to at least the UE <NUM>.

In some aspects, a sequence of the second reservation preamble <NUM> corresponds to a sequence of the first reservation preamble <NUM>.

In some aspects, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit the first reservation preamble <NUM> as a single frequency transmission based on the UE <NUM> and the first base station <NUM> both corresponding to the first operator <NUM>.

In some aspects, base station <NUM> and/or reservation preamble transmission component <NUM> may execute transceiver <NUM> to transmit data associated with the first operator <NUM> within a portion of a transmission opportunity on the downlink channel <NUM> in response to transmitting the first reservation preamble <NUM> of the first operator <NUM>.

In some aspects, the first reservation preamble <NUM> of the first operator <NUM> notifies the first base station <NUM> and at least one of a second base station <NUM> that the first base station <NUM> will access a channel <NUM> during the portion of the transmission opportunity.

In some aspects, although not shown, method <NUM> may include restricting access of one or more network entities including at least one of a second base station <NUM> to the portion of the transmission opportunity based on a determination that the first reservation preamble <NUM> of the first operator <NUM> has been transmitted by at least the first base station <NUM>.

<FIG> is a conceptual diagram of a transmission opportunity <NUM> including a reservation preamble structure during downlink communications from a network entity, such as base station <NUM>, to a UE, such as UE <NUM>, in accordance with one or more aspects. For example, transmission opportunity <NUM> including a reservation preamble structure may be part of frame <NUM> in an communication system supporting at least three operators (e.g., OP1, OP2, and OP3). According to the invention, transmission opportunity <NUM> is configured to include one or more LBT slots allowing for or facilitating transmission of a reservation preamble of a particular operator assigned to an LBT slot based on a priority level. For example, the first operator <NUM> may have the highest priority and as such, may determine or elect to transmit data on the transmission opportunity <NUM> without contention from other operators. The second operator <NUM> may transmit on the transmission opportunity if the first operator <NUM> elects not to transmit the assigned or allocated reservation preamble to the other network entities. Likewise, a third operator may transmit utilize the transmission opportunity <NUM> and transmit the assigned or allocated reservation preamble when the first operator <NUM> and second operator <NUM> forego transmission of their respective reservation preambles.

<FIG> is a conceptual diagram of a transmission opportunity <NUM> including a reservation preamble structure during downlink communications from a network entity, such as base station <NUM>, to a UE, such as UE <NUM>, in accordance with one or more aspects. For example, transmission opportunity <NUM> including a reservation preamble structure may be part of frame <NUM> in an communication system supporting at least two operators (e.g., OP1 and OP2). In some aspects, transmission opportunity <NUM> may include one or more LBT slots allowing for or facilitating transmission of a reservation preamble of a particular operator assigned to an LBT slot based on a priority level. For example, transmission opportunity <NUM> permits the downlink and uplink reservation preamble relaying scheme according to frequency division duplexing. In particular, a node, such as a UE, may detect a reservation preamble in LBT slot <NUM>. Through the process of early detection (e.g., low latency) of the reservation preamble, the node may transmit a corresponding reservation preamble on the uplink before the end of the LBT slot <NUM>. As such, OP1 may reserve the channel for uplink and downlink communications.

<FIG> is a conceptual diagram of an example of a reservation preamble <NUM> with a configurable switching gap in accordance with one or more aspects. For instance, the reservation preamble transmission of the first operator <NUM> may be part of frame <NUM> in an communication system supporting at least three operators. The reservation preamble <NUM> may include a system bandwidth of at least one of <NUM>, <NUM>, or <NUM>. Further, the time duration of the reservation preamble <NUM> may be the summation of TU and TG, where TU corresponds to the waveform samples of a multi-tone transmission, and TG corresponds to the switching gap without active transmissions. In some instances, for the same operator, the downlink and uplink reservation preambles use the same sequence to achieve the single frequency network effect, which would enhance the reliability of channel reservations at the operator-level. Additionally, the ratio of the switching gap to the multi-tone transmission (e.g., N<NUM>/N<NUM>) may be adaptive to different coverage requirements of the downlink and uplink channel reservations.

<FIG> is a conceptual diagram of an example of a scenario <NUM> of frequency mapping of reservation preamble tones in accordance with one or more aspects. For example, a network entity, such as base station <NUM>, may generate a reservation preamble that enables early detection (e.g., low latency) by using less than N<NUM> samples at a sample rate Fs with L tones of the reservation preamble needing to be allocated to L bins of a reduced-sized fast Fourier transform (FFT) of size <NUM>M-Q. As a result, once the reservation preamble is transmitted on the downlink, a node, such as a UE <NUM>, may perform early detection of the reservation preamble based on the frequency mapping of the preamble tones.

<FIG> is a conceptual diagram of an example of a transmission scheme scenario <NUM> for a reservation preamble in accordance with one or more aspects. For instance, the reservation preamble transmission of the first operator <NUM> may be part of frame <NUM> in an communication system supporting tone interleaving. In some aspects, the reservation preamble <NUM> may be transmitted using a plurality of antennas. For example, the reservation preamble <NUM> may be generated using a base sequence and zero filling with a size-N inverse FFT (IFFT). After generation, the reservation preamble <NUM> may be transmitted by transmit antenna <NUM>. Additionally, a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a frequency shift of size U, and a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a frequency shift of 2U.

<FIG> is a conceptual diagram of an example of a transmission scheme scenario <NUM> for a reservation preamble in accordance with one or more aspects. For example, the reservation preamble transmission of the first operator <NUM> may be part of frame <NUM> in an communication system supporting sub-band interleaving. Similar to <FIG>, the reservation preamble <NUM> may be transmitted using a plurality of antennas. For example, the reservation preamble <NUM> may be generated using a base sequence and zero filling with a size-N IFFT. After generation, the reservation preamble <NUM> may be transmitted by transmit antenna <NUM>. Additionally, a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a frequency shift of size L, and a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a frequency shift of <NUM>.

<FIG> is a conceptual diagram of an example of a transmission scheme scenario <NUM> for a reservation preamble in accordance with one or more aspects. For example, the reservation preamble transmission of the first operator <NUM> may be part of frame <NUM> in an communication system supporting cyclic shift diversity. Similar to <FIG>, the reservation preamble <NUM> may be transmitted using a plurality of antennas. For example, the reservation preamble <NUM> may be generated using a base sequence and zero filling with a size-N IFFT. After generation, the reservation preamble <NUM> may be transmitted by transmit antenna <NUM>. Additionally, a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a cyclic shift (e.g., tone-wise phase ramping), and a modified reservation preamble <NUM> may be transmitted by transmit antenna <NUM> with a cyclic shift.

Referring to <FIG>, one example of an implementation of an UE <NUM> may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM> and memory <NUM> and transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and preamble relay component <NUM> to enable one or more of the functions described herein related to performing measurements during a connected mode in a wireless communication system. Further, the one or more processors <NUM>, modem <NUM>, memory <NUM>, transceiver <NUM>, radio frequency (RF) front end <NUM> and one or more antennas <NUM>, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies. In some aspects, the modem <NUM> may be the same as or similar to the modem <NUM> (<FIG>).

In an aspect, the one or more processors <NUM> can include a modem <NUM> that uses one or more modem processors. The various functions related to preamble relay component <NUM> may be included in modem <NUM> and/or processors <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a receiver processor, or a transceiver processor associated with the transceiver <NUM>. In other aspects, some of the features of the one or more processors <NUM> and/or modem <NUM> associated with preamble relay component <NUM> may be performed by transceiver <NUM>.

Also, memory <NUM> may be configured to store data used herein and/or local versions of applications <NUM> or preamble relay component <NUM> and/or one or more of its subcomponents being executed by at least one processor <NUM>. Memory <NUM> can include any type of computer-readable medium usable by a computer or at least one processor <NUM>, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory <NUM> may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining preamble relay component <NUM> and/or one or more of its subcomponents, and/or data associated therewith, when UE <NUM> is operating at least one processor <NUM> to execute preamble relay component <NUM> and/or one or more of its subcomponents.

The transceiver <NUM> may include at least one receiver <NUM> and at least one transmitter <NUM>. The receiver <NUM> may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). The receiver <NUM> may be, for example, a RF receiver. In an aspect, the receiver <NUM> may receive signals transmitted by at least one base station <NUM>. Additionally, the receiver <NUM> may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. The transmitter <NUM> may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of the transmitter <NUM> may include , but is not limited to, an RF transmitter.

Moreover, in an aspect, the UE <NUM> may include an RF front end <NUM>, which may operate in communication with one or more antennas <NUM> and transceiver <NUM> for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one base station <NUM>, wireless transmissions received from neighbor UEs <NUM> and/or <NUM>, or wireless transmissions transmitted by the UE <NUM>. The RF front end <NUM> may be connected to one or more antennas <NUM> and can include one or more low-noise amplifiers (LNAs) <NUM>, one or more switches <NUM>, one or more power amplifiers (PAs) <NUM>, and one or more filters <NUM> for transmitting and receiving RF signals.

In an aspect, the LNA <NUM> can amplify a received signal at a desired output level.

Further, for example, one or more PA(s) <NUM> may be used by the RF front end <NUM> to amplify a signal for an RF output at a desired output power level. In an aspect, the RF front end <NUM> may use one or more switches <NUM> to select a particular PA <NUM> and a corresponding specified gain value based on a desired gain value for a particular application.

Also, for example, one or more filters <NUM> can be used by the RF front end <NUM> to filter a received signal to obtain an input RF signal. In an aspect, the RF front end <NUM> can use one or more switches <NUM> to select a transmit or receive path using a specified filter <NUM>, LNA <NUM>, and/or PA <NUM>, based on a configuration as specified by transceiver <NUM> and/or processor <NUM>.

As such, the transceiver <NUM> may be configured to transmit and receive wireless signals through one or more antennas <NUM> via RF front end <NUM>. In an aspect, the transceiver <NUM> may be tuned to operate at specified frequencies such that the UE <NUM> can communicate with, for example, one or more base stations <NUM> or one or more cells associated with one or more base stations <NUM>. In an aspect, for example, the modem <NUM> can configure the transceiver <NUM> to operate at a specified frequency and power level based on the UE configuration of the UE <NUM> and the communication protocol used by the modem <NUM>.

In an aspect, modem <NUM> can be a multiband-multimode modem, which can process digital data and communicate with the transceiver <NUM> such that the digital data is sent and received using the transceiver <NUM>. In an aspect, the modem <NUM> can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, the modem <NUM> can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, the modem <NUM> can control one or more components of the UE <NUM> (e.g., RF front end <NUM>, transceiver <NUM>) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In another aspect, the modem configuration can be based on UE configuration information associated with the UE <NUM> as provided by the network during cell selection and/or cell reselection.

Referring to <FIG>, one example of an implementation of base station <NUM> may include a variety of components, some of which have already been described above, but including components such as one or more processors <NUM>, a memory <NUM>, and a transceiver <NUM> in communication via one or more buses <NUM>, which may operate in conjunction with modem <NUM> and the reservation preamble transmission component <NUM>.

Claim 1:
A method (<NUM>) of wireless communication performed by a first base station of a first operator in a spectrum shared with other base stations of other operators, the method comprising:
assigning a first priority level to a first reservation preamble associated with the first operator;
generating (<NUM>) the first reservation preamble using a base sequence that is based on at least one of a compressed representation in a signal space, a basis function of the signal space, or a constant amplitude zero autocorrelation waveform, CAZAC, sequences; and
transmitting (<NUM>), on a first timeslot of multiple time slots of a downlink channel, the first reservation preamble to at least a user equipment, UE,
wherein the first reservation preamble is associated with a priority-based medium access scheme that enables the first base station to synchronize with the other base stations to reserve the shared spectrum for use by the first base station; and
wherein in the priority-based medium access scheme, reservation preambles associated with the other operators of the other base stations are assigned with respective priority levels, and are configured to be of lower priority than the first priority level assigned to the first reservation preamble.