WO2022257123A1

WO2022257123A1 - Synchronization signal block invalidation for frame based equipment (fbe) mode

Info

Publication number: WO2022257123A1
Application number: PCT/CN2021/099769
Authority: WO
Inventors: Shaozhen GUO; Jing Sun; Changlong Xu; Xiaoxia Zhang; Aleksandar Damnjanovic; Hao Xu; Rajat Prakash; Luanxia YANG; Siyi Chen
Original assignee: Qualcomm Incorporated
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2022-12-15

Abstract

A method of wireless communication performed by a first wireless communication device, the method comprising: communicating, with a second wireless communication device, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period, identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and communicating, with the second wireless communication device, an SSB at a position other than the at least one invalid candidate SSB position.

Description

SYNCHRONIZATION SIGNAL BLOCK INVALIDATION FOR FRAME BASED EQUIPMENT (FBE) MODE

TECHNICAL FIELD

The present disclosure is directed to wireless communication systems and methods. Certain aspects can enable and provide techniques for invalidating candidate synchronization signal block (SSB) positions of frame-based equipment (FBE) frames. INTRODUCTION

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . A wireless multiple-access communications system may include a number of base stations (BSs) , each simultaneously supporting communications for multiple communication devices, which may be otherwise known as user equipment (UE) .

To meet the growing demands for expanded mobile broadband connectivity, wireless communication technologies are advancing from the long term evolution (LTE) technology to a next generation new radio (NR) technology, which may be referred to as 5 ^th Generation (5G) . For example, NR is designed to provide a lower latency, a higher bandwidth or a higher throughput, and a higher reliability than LTE. NR is designed to operate over a wide array of spectrum bands, for example, from low-frequency bands below about 1 gigahertz (GHz) and mid-frequency bands from about 1 GHz to about 6 GHz, to high-frequency bands such as millimeter wave (mmWave) bands. NR is also designed to operate across different spectrum types, from licensed spectrum to unlicensed and shared spectrum. Spectrum sharing enables operators to opportunistically aggregate spectrums to dynamically support high-bandwidth services. Spectrum sharing can extend the benefit of NR technologies to operating entities that may not have access to a licensed spectrum.

One approach to avoiding collisions when communicating in a shared spectrum or an unlicensed spectrum is to use a listen-before-talk (LBT) procedure to ensure that the shared channel is clear before transmitting a signal in the shared channel. The operations or deployments of NR in an unlicensed spectrum is referred to as NR-U. In NR-U, a BS may schedule a UE for an UL transmission in an unlicensed frequency band. The UE may perform an LBT procedure prior to the scheduled time. When the LBT is a success, the UE may proceed to transmit UL data according to the schedule. When the LBT fails, the UE may refrain from transmitting.

In some instances, channel access may be in an FBE configuration, where an FBE frame may include an idle period and channel occupancy time (COT) . In some instances, an FBE frame may include a COT that may start at any time within the fixed frame period (FFP) . That is, the starting time of a COT can vary from one FBE frame to another FBE frame. A COT that may start at any time within the fixed frame period (FFP) may be referred to as a floating COT. For example, an FBE frame may include an idle period at the beginning of the frame. The idle period may be followed by an LBT in which the energy in the channel is measured to determine if the channel is clear for transmission (e.g., when the measurement is below a threshold) . The COT may immediately follow the LBT when the LBT is a success. In certain aspects, a shared frequency spectrum or unlicensed spectrum may be regulated, where a regulation may impose a certain percentage of idle time (e.g., no transmission) from a wireless communication device that transmits in the frequency spectrum. That is, each FBE frame may include a certain amount of idle time that satisfies the regulation. Because the starting time of a floating COT can vary within an FBE frame, the FBE frame may have an idle period at the beginning of the frame, at the end of the frame, or may have an idle period at both the beginning and the end of the frame.

In some instances, a BS may transmit synchronization signal blocks (SSBs) in a network to facilitate access to the network by UEs. The BS may transmit the SSBs according to a certain SSB periodicity and SSB time pattern, which may include a set of SSB candidate positions. Depending on the SSB periodicity and time pattern, the duration of the FBE frame, and/or the starting time of a floating COT within the FBE frame, the floating COT may include invalid candidate SSB positions in which the BS may not transmit SSBs. Accordingly, SSB communication technique improvements in FBE configurations may also yield benefits. Accordingly, SSB communication technique improvements in FBE configurations may also yield benefits.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in summary form as a prelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure a method of wireless communication may be performed by a first wireless communication device, the method comprising communicating, with a second wireless communication device, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period, identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and communicating, with the second wireless communication device, an SSB at a position other than the at least one invalid candidate SSB position.

In an additional aspect of the disclosure, a user equipment (UE) , may include a memory, a transceiver, and at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to receive, from a base station (BS) via the transceiver, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. The at least one processor may identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames. The UE may receive, from the BS via the transceiver, an SSB at a position other than the at least one invalid candidate SSB position.

In an additional aspect of the disclosure, a base station (BS) , may include a memory, a transceiver, and at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to transmit, to a user equipment (UE) via the transceiver, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. The BS may identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and transmit, to the UE via the transceiver, an SSB at a position other than the at least one invalid candidate SSB position.

In an additional aspect of the disclosure, a user equipment (UE) may include means for receiving, from a base station (BS) , a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. The UE may include means for identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and means for receiving, from the BS, an SSB at a position other than the at least one invalid candidate SSB position.

Other aspects, features, and embodiments of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain embodiments and figures below, all embodiments of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the invention discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according to some aspects of the present disclosure.

FIG. 2 illustrates a radio frame structure according to some aspects of the present disclosure.

FIG. 3 illustrates a frame-based equipment (FBE) frame structure according to some aspects of the present disclosure.

FIGS. 4A and 4B illustrate a synchronization signal block (SSB) transmission configuration according to some aspects of the present disclosure.

FIGS. 5A and 5B illustrate example FBE frame structures according to some aspects of the present disclosure.

FIGS. 6A and 6B illustrate candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIG. 7 illustrates candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIG. 8 illustrates candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIG. 9 illustrates candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIGS. 10A and 10B illustrate candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIG. 11 is a table illustrating invalid candidate SSB positions within FBE frames according to some aspects of the present disclosure.

FIG. 12 illustrates a discovery reference signal (DRS) window for valid SSB candidate positions according to some aspects of the present disclosure.

FIG. 13 illustrates a DRS duration for valid SSB candidate positions according to some aspects of the present disclosure.

FIG. 14 illustrates invalid SSB candidate positions within a floating COT according to some aspects of the present disclosure.

FIG. 15 illustrates invalid SSB candidate positions at least partially overlapping idle periods according to some aspects of the present disclosure.

FIG. 16 is a block diagram of an exemplary user equipment (UE) according to some aspects of the present disclosure.

FIG. 17 is a block diagram of an exemplary base station (BS) according to some aspects of the present disclosure.

FIG. 18 is a flow diagram of a wireless communication method according to some aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

This disclosure relates generally to 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, Global System for Mobile Communications (GSM) networks, 5 ^th Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS) . In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP) , and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the UMTS mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G 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 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with a ultra-high density (e.g., ～1M nodes/km ²) , ultra-low complexity (e.g., ～10s of bits/sec) , ultra-low energy (e.g., ～10+ years of battery life) , and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ～99.9999%reliability) , ultra-low latency (e.g., ～ 1 ms) , and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ～ 10 Tbps/km ²) , extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates) , and deep awareness with advanced discovery and optimizations.

A 5G NR communication system may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI) . Additional features may also include 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 5G 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 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and the like bandwidth (BW) . For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz BW. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz BW. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with UL/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive UL/downlink that may be flexibly configured on a per-cell basis to dynamically switch between UL and downlink to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

In a cellular wireless communication network, a UE may request a connection setup to the network, commonly referred to as random access. The random access plays three main roles, including: (i) establishment of a radio link and uplink synchronization for initial access (ii) to re-establish a radio link after radio-link failure (iii) for handover when uplink synchronization needs to be established to the new cell. The UE may initiate a random access procedure in an uplink Random Access Channel (RACH) . The first step in the random access procedure is the transmission of a random access preamble. The main purpose of the preamble transmission is to notify the presence of a random access attempt to the BS and to allow the BS to estimate the delay between the BS and the UE. The delay estimate will be used to adjust the uplink timing.

The time frequency resources on which the random access preamble is transmitted is known as the Physical Random Access Channel (PRACH) . The network broadcast information to all the UEs which time-frequency resources (PRACH resources) are allowed for the preamble transmission on Downlink Physical Broadcast Channel (DL-PBCH) . For instance, the PRACH information may be informed to the UEs via System Information Block (SIB) 2.

In some aspects, a wireless communication network can operate over an unlicensed band. The deployment of NR over an unlicensed spectrum is referred to as NR-unlicensed (NR-U) . Channel access in unlicensed bands, such as 5 GHz and 6 GHz bands, may be regulated by authorities, such as Federal Communications Commission (FCC) . For example, FCC imposes various regulations on the maximum equivalent isotropically radiated power (EIRP) and the maximum EIRP power spectral density (PSD) that a transmitting node may transmit in a 6 GHz band. EIRP may refer to the amount of power a radio transmitter system (including transmitter and radiating antenna) may emit. EIRP PSD may refer to the amount of power per bandwidth unit a radio transmitter system may emit.

One issue of cellular network operating in unlicensed spectrum is to ensure a fair coexistence with other unlicensed system (e.g., Wi-Fi) . Fairness for NR-U device is defined as the ability that the NR-U device does not impact the other devices operating in the same band. For example, the regulation mandates the use of Listen-Before-Talk (LBT) protocols. LBT is a spectrum sharing mechanism by which a device senses the spectrum band using a Clear Channel Assessment (CCA) check before accessing to it.

An NR-U UE or BS may first sense the communications channel to find out there is no communication prior to any transmission. In some aspects, the channel sensing procedure relies on detecting energy level on multiple sub-bands of the of the frequency band. The LBT parameters (e.g., duration, CCA parameters, etc. ) are configured in the UE by the BS.

There are two types of LBT procedures, a frame based equipment (FBE) -based LBT and a load based equipment (LBE) -based LBT. In FBE-based LBT, channel sensing is performed at predetermined time instants. For instance, if the channel is busy, a transmitting node may back off for a predetermined time period and sense the channel again after this period. In LBE-based LBT, channel sensing is performed at any time instant and random back-off is used if the channel is found busy. For instance, in the FBE mode, the NR-U unlicensed devices (e.g., UE, BS) are allowed to contend for the channel beginning only at synchronized frame boundaries. The FBE NR-U device has to detect the energy level at a designated time equal to CCA period. If the energy level in the channel is below the CCA threshold, then the equipment can transmit for a duration, which may be referred to as a Channel Occupancy Time (COT) , within an FBE frame.

In some aspects, a BS may broadcast system information in a network to facilitate UEs in accessing the network. The system information may be in the form of a set of Synchronization Signal Blocks (SSBs) and/or RMSI (Remaining Minimum System Information) . In some aspects, the BS may transmit SSBs in the form of SSB burst, where an SSB burst may include a set of SSB, and may repeat the transmission of the SSB burst according to a certain SSB periodicity. In some instances, the BS may broadcast RMSI indicating an FBE transmission configuration via a downlink BCH. The FBE transmission configuration may also be referred to as a Fixed Frame Period (FFP) configuration. As described herein, the terms “FBE frames” and “FFPs” may be used interchangeably. In some instances, the RMSI may include a system information block 1 (SIB-1) carrying the FFP configuration. In some other instances, the BS may signal the FFP configuration for a UE with UE specific RRC signaling, for example, for an FBE Secondary Cell (sCell) .

As described in 3GPP Release 16 specifications, in the FBE mode of operation, the FBE mode (e.g., semi-static channel access) may be signaled in the RMSI. The fixed frame period configuration may be signaled in the SIB (e.g., SIB-1) . In some instances, the FBE frame may include a COT that may only start at the beginning of the fixed frame period (FFP) . The FFP may be a period at which the FBE frame is repeated. For example, the FFP may include a time period of 1 ms, 2 ms, 2.5 ms, 4 ms, 5 ms, 10 ms, or another time period. In some instances, the FBE frame may include a COT that may start at a random time within the fixed frame period (FFP) . A COT that may start at various time (e.g., a random time) within the fixed frame period (FFP) may be referred to as a floating COT. For example, an FBE frame may include an idle period at the beginning of the frame, at the end of the frame, or at the beginning and end of the frame. The idle period may include a time value restricted to a maximum time period. For example, the idle period may have a minimum period of 5%of the FFP or 100us, whichever is greater.

In some aspects, an FBE frame may begin with an idle period followed by one or more CCA periods. A wireless communication device intending to transmit during the FBE frame may randomly select a CCA period. The wireless communication device may measure energy in the channel during the selected CCA period to determine if the channel energy is below a threshold. If the energy is below the threshold, the wireless device may transmit during the COT. The COT may immediately follow the CCA period with a CCA indicating that the channel is clear for transmission. Because of the uncertainty associated with CCA and the random selection of CCA period, the starting time of a COT may vary from FBE frame to FBE frame. Accordingly, an FBE frame may have an idle period at the beginning of the frame, at the end of the frame, or may have an idle period at both the beginning and the end of the frame.

A discovery reference signal (DRS) window may be configured to limit the range in which a UE will assume the SSBs are transmitted. The SSBs may be transmitted in bursts. During the DRS window, the UE may listen for and decode the SSBs. The SSBs may include PSS, the SSS, and the PBCH. The DRS window may be used when a BS does not configure the full range of SSB positions to be reserved. The DRS window may be configured with a time duration. For example, the DRS window may be configured as 0.5 ms, 1 ms, 2 ms, 3 ms, 4 ms, 5 ms, or more. In some instances, the DRS window may be configured by a BS. The DRS window may also be configured to a default time period (e.g., 5 ms) . If a UE does not receive a DRS window configuration, the UE may assume the default value (e.g., 5ms) . In some instances, the DRS window periodicity may be configured the same as the configuration of the SSB burst periodicity.

In some instances, the invalid candidate SSB positions may correspond to common invalid candidate SSB positions between one or more invalid candidate SSB positions when the idle period is at the beginning of the FBE frame and one or more invalid candidate SSB positions when the idle period is at the end of the FBE frame.

The BS may inform the UEs about which SSBs are being transmitted using ssb-PositionsInBurst information element within the ServingCellConfigCommon SIB. The ssb-PositionsInBurst information element may include a bitmap, where each bit in the bitmap may correspond to one SSB in an SSB burst (a set of SSBs) . SSBs in an SSB burst may be indexed from 0 to K, where K may be 8 or 64, in some examples. In some instances, a value 0 at bit position k in the bitmap may indicate that the corresponding SSB index k-1 is not transmitted while a value 1 at position k may indicate that the corresponding SSB index k-1 is transmitted. The interpretation of this field may vary depending upon the operating frequency band. For example, when the UE is operating in an unlicensed frequency band, the UE may expect that a bit at position k > Q is set to 0, where Q indicates the quasi-colocation (QCL) relationship among the SSB positions. The UE may determine the SS/PBCH block index according to (

mod

) , and/or according to (

mod

) where

is the candidate SS/PBCH block index. Therefore, the SSB index may not be greater than

where

corresponds to Q.

If the bit at position k is set to 1 (indicating an SSB will be transmitted) , the PDSCH transmissions will be rate matched around all candidate SSB positions with the same QCL as position k. As an example, a BS may transmit an SSB burst including 8 SSBs indexed from 0 to 7 and may repeat the transmission of the SSB burst at every 20 ms. When bit position 2 (e.g., k=2) in the bitmap of the ssb-PositionsInBurst information element is set to 1, the BS may transmit all SSBs with index 1 and PDSCH transmission in subframes where SSB index 1 is located will be rate matched around SSB index l.

Depending on the SSB periodicity and time pattern, the duration of the FBE frame, and/or the starting time of a floating COT within the FBE frame, the floating COT may include invalid candidate SSB positions in which the BS may not transmit SSBs. For example, certain candidate SSB positions may fall within an idle period for an FBE frame where no transmission is allowed.

The present disclosure describes mechanisms for communicating a configuration for frame-based equipment (FBE) frames between wireless communication devices (e.g. a UE and a BS) . Each of the FBE frames may include a COT period and an idle period as described above. The present disclosure describes methods of identifying valid and invalid candidate synchronization signal block (SSB) positions within the FBE frames. SSB candidate positions may refer to the time locations at which SSBs may be transmitted by a BS according to an SSB periodicity and time pattern (e.g., SSB burst pattern) . The valid and invalid SSB candidate positions may be identified such that SSBs are communicated (e.g., transmitted) at valid candidate SSB positions and SSBs are not communicated at invalid candidate SSB positions. By identifying and/or having knowledge of the invalid candidate SSB positions, a wireless communication device (e.g., a UE) may skip SSB monitoring at those invalid candidate SSB positions, and thus may conserve resources (e.g., processor execution time, battery power, memory, etc. ) that would otherwise be used for processing the SSBs. For example, a BS may transmit SSBs to a UE. The UE may also conserve the resources required to measure SSBs for radio link monitoring (RLM) and/or radio resource management (RRM) . Further, data transmission in a subframe that includes an SSB may be rate-matched around the SSB. By having knowledge that a certain subframe may include an invalid SSB, the data may be transmitted in the certain subframe without rate-match. Accordingly, resources may be utilized more efficiently.

Aspects of the present disclosure may provide a mechanism for determining invalid candidate SSB positions and valid candidate SSB positions for NR-U. Aspects of the present disclosure can provide several benefits. For example, the UE may conserve resources (e.g., processor execution time, battery power, memory, etc. ) required for processing the SSBs. When a UE does not process SSBs during invalid candidate SSB positions, the UE may conserve the resources required to rate match a PDSCH over the candidate SSB positions. The UE may also conserve the resources required to measure SSBs for radio link monitoring (RLM) and/or radio resource management (RRM) . Conservation of these resources may allow a UE to have a longer battery life and/or a processor of the UE to have reduced computing resources.

FIG. 1 illustrates a wireless communication network 100 according to some aspects of the present disclosure. The network 100 may be a 5G network. The network 100 includes a number of base stations (BSs) 105 (individually labeled as 105a, 105b, 105c, 105d, 105e, and 105f) and other network entities. A BS 105 may be a station that communicates with UEs 115 and may also be referred to as an evolved node B (eNB) , a next generation eNB (gNB) , an access point, and the like. Each BS 105 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a BS 105 and/or a BS subsystem serving the coverage area, depending on the context in which the term is used.

A BS 105 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 macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . A BS for a macro cell may be referred to as a macro BS. A BS for a small cell may be referred to as a small cell BS, a pico BS, a femto BS or a home BS. In the example shown in FIG. 1, the

BSs

105d and 105e may be regular macro BSs, while the BSs 105a-105c may be macro BSs enabled with one of three dimension (3D) , full dimension (FD) , or massive MIMO. The BSs 105a-105c may take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. The BS 105f may be a small cell BS which may be a home node or portable access point. A BS 105 may support one or multiple (e.g., two, three, four, and the like) cells.

The network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE 115 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 115 may be a device that includes a Universal Integrated Circuit Card (UICC) . In another aspect, a UE may be a device that does not include a UICC. In some aspects, the UEs 115 that do not include UICCs may also be referred to as IoT devices or internet of everything (IoE) devices. The UEs 115a-115d are examples of mobile smart phone-type devices accessing network 100. A UE 115 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. The UEs 115e-115h are examples of various machines configured for communication that access the network 100. The UEs 115i-115k are examples of vehicles equipped with wireless communication devices configured for communication that access the network 100. A UE 115 may be able to communicate with any type of the BSs, whether macro BS, small cell, or the like. In FIG. 1, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE 115 and a serving BS 105, which is a BS designated to serve the UE 115 on the downlink (DL) and/or uplink (UL) , desired transmission between BSs 105, backhaul transmissions between BSs, or sidelink transmissions between UEs 115.

In operation, the BSs 105a-105c may serve the

UEs

115a and 115b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. The macro BS 105d may perform backhaul communications with the BSs 105a-105c, as well as small cell, the BS 105f. The macro BS 105d may also transmits multicast services which are subscribed to and received by the

UEs

115c and 115d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

The BSs 105 may also communicate with a core network. The core network may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. At least some of the BSs 105 (e.g., which may be an example of a gNB or an access node controller (ANC) ) may interface with the core network through backhaul links (e.g., NG-C, NG-U, etc. ) and may perform radio configuration and scheduling for communication with the UEs 115. In various examples, the BSs 105 may communicate, either directly or indirectly (e.g., through core network) , with each other over backhaul links (e.g., X1, X2, etc. ) , which may be wired or wireless communication links.

The network 100 may also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such as the UE 115e, which may be a drone. Redundant communication links with the UE 115e may include links from the

macro BSs

105d and 105e, as well as links from the small cell BS 105f. Other machine type devices, such as the UE 115f (e.g., a thermometer) , the UE 115g (e.g., smart meter) , and UE 115h (e.g., wearable device) may communicate through the network 100 either directly with BSs, such as the small cell BS 105f, and the macro BS 105e, or in multi-step-size configurations by communicating with another user device which relays its information to the network, such as the UE 115f communicating temperature measurement information to the smart meter, the UE 115g, which is then reported to the network through the small cell BS 105f. The network 100 may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such asV2V, V2X, C-V2X communications between a

UE

115i, 115j, or 115k and other UEs 115, and/or vehicle-to-infrastructure (V2I) communications between a

UE

115i, 115j, or 115k and a BS 105.

In some implementations, the network 100 utilizes OFDM-based waveforms for communications. An OFDM-based system may partition the system BW into multiple (K) orthogonal subcarriers, which are also commonly referred to as subcarriers, tones, bins, or the like. Each subcarrier may be modulated with data. In some instances, the subcarrier spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system BW. The system BW may also be partitioned into subbands. In other instances, the subcarrier spacing and/or the duration of TTIs may be scalable.

In some aspects, the BSs 105 can assign or schedule transmission resources (e.g., in the form of time-frequency resource blocks (RB) ) for downlink (DL) and uplink (UL) transmissions in the network 100. DL refers to the transmission direction from a BS 105 to a UE 115, whereas UL refers to the transmission direction from a UE 115 to a BS 105. The communication can be in the form of radio frames. A radio frame may be divided into a plurality of subframes or slots, for example, about 10. Each slot may be further divided into transmission time intervals as will be discussed more fully below in relation to FIG. 2. In a FDD mode, simultaneous UL and DL transmissions may occur in different frequency bands. For example, each subframe includes a UL subframe in a UL frequency band and a DL subframe in a DL frequency band. In a TDD mode, UL and DL transmissions occur at different time periods using the same frequency band. For example, a subset of the subframes (e.g., DL subframes) in a radio frame may be used for DL transmissions and another subset of the subframes (e.g., UL subframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided into several regions. For example, each DL or UL subframe may have pre-defined regions for transmissions of reference signals, control information, and data. Reference signals are predetermined signals that facilitate the communications between the BSs 105 and the UEs 115. For example, a reference signal can have a particular pilot pattern or structure, where pilot tones may span across an operational BW or frequency band, each positioned at a pre-defined time and a pre-defined frequency. For example, a BS 105 may transmit cell specific reference signals (CRSs) and/or channel state information –reference signals (CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE 115 may transmit sounding reference signals (SRSs) to enable a BS 105 to estimate a UL channel. Control information may include resource assignments and protocol controls. Data may include protocol data and/or operational data. In some aspects, the BSs 105 and the UEs 115 may communicate using self-contained subframes. A self-contained subframe may include a portion for DL communication and a portion for UL communication. A self-contained subframe can be DL-centric or UL-centric. A DL-centric subframe may include a longer duration for DL communication than for UL communication. A UL-centric subframe may include a longer duration for UL communication than for UL communication.

In some aspects, the network 100 may be an NR network deployed over a licensed spectrum. The BSs 105 can transmit synchronization signals (e.g., including a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) ) in the network 100 to facilitate synchronization. The BSs 105 can broadcast system information associated with the network 100 (e.g., including a master information block (MIB) , remaining system information (RMSI) , and other system information (OSI) ) to facilitate initial network access. In some instances, the BSs 105 may broadcast the PSS, the SSS, and/or the MIB in the form of synchronization signal block (SSBs) over a physical broadcast channel (PBCH) and may broadcast the RMSI and/or the OSI over a physical downlink shared channel (PDSCH) . In some instances, the BSs 105 may broadcast the SSBs only in valid candidate SSB positions.

In some aspects, a UE 115 attempting to access the network 100 may perform an initial cell search by detecting a PSS from a BS 105. The PSS may enable synchronization of period timing and may indicate a physical layer identity value. The UE 115 may then receive a SSS. The SSS may enable radio frame synchronization, and may provide a cell identity value, which may be combined with the physical layer identity value to identify the cell. The PSS and the SSS may be located in a central portion of a carrier or any suitable frequencies within the carrier.

After receiving the PSS and SSS, the UE 115 may receive a MIB. The MIB may include system information for initial network access and scheduling information for RMSI and/or OSI. After decoding the MIB, the UE 115 may receive RMSI and/or OSI. The RMSI and/or OSI may include radio resource control (RRC) information related to random access channel (RACH) procedures, paging, control resource set (CORESET) for physical downlink control channel (PDCCH) monitoring, physical UL control channel (PUCCH) , physical UL shared channel (PUSCH) , power control, and SRS.

After obtaining the MIB, the RMSI and/or the OSI, the UE 115 can perform a random access procedure to establish a connection with the BS 105. In some examples, the random access procedure may be a four-step random access procedure. For example, the UE 115 may transmit a random access preamble and the BS 105 may respond with a random access response. The random access response (RAR) may include a detected random access preamble identifier (ID) corresponding to the random access preamble, timing advance (TA) information, a UL grant, a temporary cell-radio network temporary identifier (C-RNTI) , and/or a backoff indicator. Upon receiving the random access response, the UE 115 may transmit a connection request to the BS 105 and the BS 105 may respond with a connection response. The connection response may indicate a contention resolution. In some examples, the random access preamble, the RAR, the connection request, and the connection response can be referred to as message 1 (MSG1) , message 2 (MSG2) , message 3 (MSG3) , and message 4 (MSG4) , respectively. In some examples, the random access procedure may be a two-step random access procedure, where the UE 115 may transmit a random access preamble and a connection request in a single transmission and the BS 105 may respond by transmitting a random access response and a connection response in a single transmission.

After establishing a connection, the UE 115 may initiate an initial network attachment procedure with the network 100. When the UE 115 has no active data communication with the BS 105 after the network attachment, the UE 115 may return to an idle state (e.g., RRC idle mode) . Alternatively, the UE 115 and the BS 105 can enter an operational state or active state, where operational data may be exchanged (e.g., RRC connected mode) . For example, the BS 105 may schedule the UE 115 for UL and/or DL communications. The BS 105 may transmit UL and/or DL scheduling grants to the UE 115 via a PDCCH. The scheduling grants may be transmitted in the form of DL control information (DCI) . The BS 105 may transmit a DL communication signal (e.g., carrying data) to the UE 115 via a PDSCH according to a DL scheduling grant. The UE 115 may transmit a UL communication signal to the BS 105 via a PUSCH and/or PUCCH according to a UL scheduling grant.

In some aspects, the BS 105 may communicate with a UE 115 using HARQ techniques to improve communication reliability, for example, to provide a URLLC service. The BS 105 may schedule a UE 115 for a PDSCH communication by transmitting a DL grant in a PDCCH. The BS 105 may transmit a DL data packet to the UE 115 according to the schedule in the PDSCH. The DL data packet may be transmitted in the form of a transport block (TB) . If the UE 115 receives the DL data packet successfully, the UE 115 may transmit a HARQ ACK to the BS 105. Conversely, if the UE 115 fails to receive the DL transmission successfully, the UE 115 may transmit a HARQ NACK to the BS 105. Upon receiving a HARQ NACK from the UE 115, the BS 105 may retransmit the DL data packet to the UE 115. The retransmission may include the same coded version of DL data as the initial transmission. Alternatively, the retransmission may include a different coded version of the DL data than the initial transmission. The UE 115 may apply soft-combining to combine the encoded data received from the initial transmission and the retransmission for decoding. The BS 105 and the UE 115 may also apply HARQ for UL communications using substantially similar mechanisms as the DL HARQ.

In some aspects, the network 100 may operate over a system BW or a component carrier (CC) BW. The network 100 may partition the system BW into multiple BWPs (e.g., portions) . A BS 105 may dynamically assign a UE 115 to operate over a certain BWP (e.g., a certain portion of the system BW) . The assigned BWP may be referred to as the active BWP. The UE 115 may monitor the active BWP for signaling information from the BS 105. The BS 105 may schedule the UE 115 for UL or DL communications in the active BWP. In some aspects, a BS 105 may assign a pair of BWPs within the CC to a UE 115 for UL and DL communications. For example, the BWP pair may include one BWP for UL communications and one BWP for DL communications.

In some aspects, the network 100 may operate over an unlicensed band, for example, a 6 GHz bands. As discussed above, FCC may regulate maximum EIRP and/or maximum EIRP PSD for transmission in a 6 GHz band. Thus, when the network operates over a 6 GHz channel, a BS 105 may communicate with a UE 115 in accordance with the FCC regulation. The BS 105 may broadcast system information indicating a FBE configuration to facilitate UEs 115 in accessing the network 100 over the unlicensed band. The FBE configuration may include information associated with durations for FFPs, candidate SSB positions, durations and/or locations of idle periods in the FFPs, DRS windows, DRS window offsets, etc. The candidate SSB positions may include information associated with valid SSB position in which a UE may receive and decode SSBs and invalid SSB positions in which a UE may refrain from receiving and decoding SSBs. For example, a UE may refrain from rate matching around the invalid candidate SSB positions, refrain from performing radio link monitoring (RLM) measurements and/or refrain from performing radio resource management (RRM) measurement at the invalid candidate SSB positions.

In some aspects, the BSs 105 and/or the UEs 115 may be 3GPP Rel. 16 NR-U compliant BSs and/or UEs, respectively, which may communicate with each other in the FBE mode. The 3GPP Rel. 16 NR-U compliant BS and/or UE may communicate a COT starting position and/or a DRS window offset. The DRS window offset may begin at the beginning of the FBE frame and the DRS window may begin at the end of the DRS window offset. In some instances, an invalid candidate SSB position may be at least partially located outside the DRS window. In some instances, an invalid candidate SSB position may be at least partially overlap the idle period.

In some aspects, the BSs 105 and/or the UEs 115 may communicate a configuration that indicates that the SSB is transmitted at an earliest opportunity within the FBE frame. In some aspects, the BSs 105 and/or the UEs 115 may determine that the invalid candidate SSB positions correspond to common invalid candidate SSB positions between invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and invalid candidate SSB positions when the idle period is at the end of the FBE frame.

In some aspects, the BSs 105 and/or the UEs 115 may determine that the invalid candidate SSB positions correspond to candidate SSB positions that partially overlap a discovery reference signal (DRS) window offset or second candidate SSB positions that partially overlap a worst-case idle period at the end of the FBE frame. Mechanisms for determining valid and invalid candidate SSB positions when operating in FBE mode are described in greater detail herein.

FIG. 2 illustrates a radio frame structure 200 according to some aspects of the present disclosure. The radio frame structure 200 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for communications. In FIG. 2, the x-axes represent time in some arbitrary units and the y-axes represent frequency in some arbitrary units. The transmission frame structure 200 includes a radio frame 201. The duration of the radio frame 201 may vary depending on the aspects. In an example, the radio frame 201 may have a duration of about ten milliseconds. The radio frame 201 includes M number of slots 202, where M may be any suitable positive integer. In an example, M may be about 10.

Each slot 202 includes a number of subcarriers 204 in frequency and a number of symbols 206 in time. The number of subcarriers 204 and/or the number of symbols 206 in a slot 202 may vary depending on the aspects, for example, based on the channel bandwidth, the subcarrier spacing (SCS) , and/or the CP mode. One subcarrier 204 in frequency and one symbol 206 in time forms one resource element (RE) 212 for transmission. A resource block (RB) 210 is formed from a number of consecutive subcarriers 204 in frequency and one or more consecutive symbols 206 in time. In NR, a RB 210 is defined as twelve consecutive subcarriers 204 in a frequency domain.

In an example, a BS (e.g., BS 105 in FIG. 1) may schedule a UE (e.g., UE 115 in FIG. 1) for UL and/or DL communications at a time-granularity of slots 202 or TTIs 208. Each slot 202 may be time-partitioned into K number of TTIs 208. Each TTI 208 may include one or more symbols 206. The TTIs 208 in a slot 202 may have variable lengths. For example, when a slot 202 includes N number of symbols 206, a TTI 208 may have a length between one symbol 206 and (N-1) symbols 206. In some aspects, a TTI 208 may have a length of about two symbols 206, about four symbols 206, or about seven symbols 206. In some examples, the BS may schedule UE at a frequency-granularity of a resource block (RB) 210 (e.g., including about 12 subcarriers 204) .

FIG. 3 illustrates an FBE frame structure 300 according to some aspects of the present disclosure. The structure 300 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for communications. In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using the structure 300. In FIG. 3, the x-axis represents time in some arbitrary units. The structure 300 may be employed in conjunction with the structure 200.

As shown, the frame structure 300 includes a plurality of FFPs 301 (e.g., in a shared radio frequency band) . Each FFP 301 includes a Channel Occupancy Time (COT) 302 and an idle period 304. The COT 302 may also be referred to as a transmission period. A BS 105 or a UE 115 may perform channel sensing or an LBT in the idle period 304 and may access the frequency during a COT 302 in a subsequent FFP 301. Although FIG. 3 illustrates the idle period 304 located at the end of the FFP 301, it should be understood that in other examples the idle period of an FFP can be located at the beginning of the FFP (e.g., a floating COT) . In some aspects, some regulations may restrict the COT 302 to be no longer than 95%of the frame length (the duration of the FFP 301) and the idle period to be no shorter than 5%of the frame length. In some aspects, some regulations may restrict the idle period to be no longer than 100 microseconds (μs) .

In some aspects, the BS 105 and/or the UE 115 may perform an LBT in an idle period 304 to gain access to COT 302 in a subsequent FFP 301. After gaining access to the COT 302, the BS 105 and/or the UE 115 may communicate multiple UL and/or DL communications in the COT 302 without another LBT. In some aspects, each FFP 301 is restricted to a duration of about 1 ms, 2 ms, 2.5 ms, 4ms, 5ms, 10 ms, or more. The starting positions of the FFPs 301 within every two radio frames (e.g., the radio frames 201) may start from an even radio frame and are given by

i*P ; i= {0, 1, …, 20/P-1} (1)

where P is a duration of an FFP 301.

In some aspects, the base station 105 notifies an FBE mode with the structure 300 to the UE 115 in RMSI. In some aspects, RMSI scheduling information may be indicated in a broadcast channel (BCH) payload carried in an SSB. In some aspects, RMSI may be carried in in System Information Block (SIB) Type 1. For instance, SIB1 may include a semi-static channel access configuration indicating an FBE mode or FFP configuration. Additionally, SIB1 may include information relevant for a UE to evaluate whether the UE is allowed to access a corresponding cell. Also, SIB1 may provide the UE 115 with the scheduling of other system information.

The frame structure 300 broadcasted by the BS 105 may be used to perform channel access by the UE 115 at fixed time instants (COT 302) . The UE 115 may perform CCA to sense if the channel is available, for example, during idle period 304. If the channel is busy, the UE 115 may back off for the COT 302 and sense the channel again in a next idle period 304 after the COT 302. In some instances, the UE 115 may measure the energy level during COT 302. If the energy level is lower than a threshold and if the UE 115 detected that the channel is idle, the UE 115 may start transmitting data immediately in the COT 302.

FIG. 4A illustrates an SSB transmission configuration 400, according to some aspects of the present disclosure. For instance, a BS 105 may transmit SSBs with a subcarrier spacing (SCS) of 15 kHz as shown by the SSB transmission configuration 400. In the illustrated example of FIG. 4A, the BS 105 may transmit an SSB burst with 8 SSBs and may repeat the SSB burst transmission at every 20 ms (e.g., corresponding to two radio frames) as shown by the SSB period 420, which may also be referred to as a DRS window. In general, an SSB period 420 may include any suitable duration. In some examples, the BS 105 may repeat SSB burst transmission at a periodicity of 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms . In the illustrated example, the SSB period 420 is partitioned into sub-periods 422 (1) ... 422 (4) of 5 ms each.. In some instances, certain sub-periods may include candidate SSB positions. For example, the BS 105 may transmit the SSB burst (8 SSBs) at the beginning 5 ms of every 20 ms SSB period 420. That is, the sub-period 422 (1) may include candidate SSB positions and the remaining sub-periods 422 (2) , 422 (3) , and 422 (4) in the SSB period 420 may not.

Each of the 5ms sub-periods 422 (1) ... 422 (4) may be divided into slots. The number of slots may be based upon the sub-carrier spacing (SCS) used for transmissions. For example, FIG 4A shows an SCS of 15kHz in which each of sub-periods 422 (1) ... 422 (4) may be divided into five subframes of 1 ms each. For 15 kHz SCS, each subframe may include one slot 424 (shown as 424 (1) …424 (5) ) similar to slot 202 of FIG. 2 and include a number of subcarriers (e.g., subcarriers 204) in frequency and a number of OFDM symbols (e.g., symbols 206 of FIG. 2) in time. For example, each of the slots 424 (1) ... 424 (5) may be divided into fourteen OFDM symbols 426 (0) ... 426 (13) . Each of the slots 424 (1) ... 424 (5) may carry SSBs. Each of the SSBs may include the SSS, the PSS and the PBCH within 4 symbols 426. Since each of the five slots 424 (1) ... 424 (5) may carry two SSBs there may be 10 candidate SSB positions within sub-periods 422 (1) . In some examples, 8 consecutive SSBs may be selected for transmission out of the 10 candidate SSB positions within sub-period 422 (1) . SSBs may be transmitted in 4 OFDM symbols. For example, within slot 424 (1) , a first SSB may be transmitted in OFDM symbols 426 (2) to 426 (5) and a second SSB may transmitted in OFDM symbols 426 (8) to 426 (11) .

FIG. 4B illustrates candidate SSB positions within subframes of a fixed frame period, according to some aspects of the present disclosure. FIG. 4B is substantially similar to FIG. 4A with the exception of the SCS. FIG. 4A shows an example embodiment at an SCS of 15 kHz, while FIG. 4B show an example embodiment at 30kHz. As shown in FIG. 4B, SSB period 420 may include 422 (1) ... 422 (4) . The FFP may have any length of time period. For example, the SSB period 420 may have a time period of 1 ms, 2 ms, 2.5 ms, 4 ms, 5 ms, 10 ms, or more. In the example of FIG. 4B, SSB period 420 may include 2 radio frames of 10 ms each and sub-periods 422 (1) ... 422 (4) may each have a period of 5 ms. In some instances, certain periods may include candidate SSB positions. For example, the first periods (e.g., sub-period 422 (1) ) in the SSB periodicity (e.g., 2 radio frames repeated at 20ms intervals) may include the candidate SSB positions. In some instances, the first periods 422 (1) of the FFP may be configured to carry the SSBs. The SSBs may be repeated with a periodicity of two radio frames. In some other SSB configurations, the SSB configuration period (periodicity) may be 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms.

Each of periods 422 (1) ... 422 (4) may be divided into slots. The number of slots may be based upon the sub-carrier spacing (SCS) used during transmission of the FFP. For example, FIG 4B shows an SCS of 30kHz, each of subframes 422 (1) ... 422 (4) may be divided into two slots of 0.5 ms each (e.g., shown as 425 (1) ... 425 (10) of 0.5 ms each) . Each of the slots 425 (1) ... 425 (10) may carry SSBs. Each of slots 425 (1) ... 425 (10) may be TTI 208 of FIG. 2 and include a number of subcarriers (e.g., subcarriers 204) in frequency (e.g., 15 kHz, 30 kHz, 60 kHz, or 120 kHz) and a number of OFDM symbols (e.g., symbols 206 of FIG. 2) in time. For example, each of the slots 425 (1) ... 425 (10) may be divided into fourteen OFDM symbols 426 (0) ... 426 (13) . For NR-U configured at an SCS of 30kHz, 8 consecutive SSBs may be selected from 20 candidate locations in slots 425 (1) ... 425 (10) , where each slot carries 2 SSBs. Each of the SSBs may include the SSS, the PSS and the PBCH within four consecutive symbols 426. In some instances, SSBs may be transmitted consecutively in OFDM symbols 426 (4) to 426 (7) and 426 (8) to 426 (11) . In some instances, SSBs may be transmitted in OFDM symbols 426 (2) to 426 (5) and 426 (8) to 426 (11) in which the SSBs are separated by OFDM symbols 426 (6) and 426 (7) . In some instances, only the OFDM symbols 426 (2) to 426 (5) and 426 (8) to 426 (11) are used to transmit the SSBs for NR-U.

FIG. 5A illustrates an example FBE frame structure 500 according to some aspects of the present disclosure. The frame structure 500 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using the structure 500. In FIG. 5A, the x-axis represents time in some arbitrary units. Frame structure 500 may be similar to frame structure 300 of FIG. 3. The frame structure 500 may be employed in conjunction with the structure 200. The frame structure 500 may include a plurality of FFPs 301 (e.g., in a shared radio frequency band) . Each FFP 301 may include a COT 302 and an idle period 304. The COT 302 may also be referred to as a transmission period. FIG. 5A further illustrates a CCA period 508 (e.g., having a duration of about 9 μs) . For example, a BS 105 or a UE 115 may perform channel sensing via a clear channel assessment (e.g., CCA) or an LBT in the idle period 304 at the end of the FFP 301 and may access the channel during a COT 302 in a next FFP 301. Although FIG. 5A illustrates the idle period 304 located at the end of the FFP 301, it should be understood that in other examples (e.g., example of FIG. 5B) the idle period 304 of an FFP 301 can be located at the beginning of the FFP 301. In some aspects, some regulations may restrict the COT 302 to be no longer than 95%of the frame length (the duration of the FFP 301) and the idle period 304 to be no shorter than 5%of the frame length. In some aspects, some regulations may restrict the idle period 304 to be no longer than 100 microseconds (μs) .

FIG. 5B illustrates an example FBE frame structure 550 according to some aspects of the present disclosure. The frame structure 550 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using the frame structure 550. In FIG. 5B, the x-axis represents time in some arbitrary units. Frame structure 550 may be similar to the frame structure 500 of FIG. 5A with the exception that the CCA 508 may begin after a CCA random time period 512. The CCA random time period 512 may start at the beginning of the FFP 301. The CCA random time period 512 and therefore the CCA 508 starting position may be selected by the BS. In some instances, the BS may randomly select the CCA 508 starting position. For example, the BS may draw a random number and back off for a certain duration of time or a certain number of CCA periods based on the drawn random number. In some instances, the BS may communicate the CCA random time period 512 and/or the CCA 508 starting position to the UE directly or indirectly. For example, the BS may successfully gain access (e.g., a COT 302) to a channel based on a CCA indicating the channel is clear for transmission, and may transmit an indicator indicating timing information related to the COT 302. Because of the uncertainty associated with CCA, the starting of a COT 302 may vary from one FFP 301 to another FFP 301. That is, each FFP 301 may include a different CCA random time period 512. The CCA random time period 512 may be an idle period. The combined CCA random time period 512 at the beginning of FFP 301 and the remaining idle period 514 at the end of the FFP 301 may not exceed the maximum idle period of 100us or 5%of the FFP 301.

In FIG. 5B, the COT 302 may begin after a successful CCA (performed by the BS) in the CCA 508. Since the CCA 508 may begin at a random time period based on the CCA random period 512, the COT 302 may be considered a floating COT 302. The time at which the COT begins may float within the FFP 301 based on the CCA random period 512. The floating COT 302 may support prioritization of access to the channel by certain BSs. For example, a first BS having a shorter CCA random period 512 may access the channel before a second BS having a longer CCA random period 512 due to the first BS having the CCA at an earlier time than the second BS. When the second BS performs the CCA, the channel may be busy (e.g., energy detected above a threshold) due to the first BS transmitting during the floating COT 302. That is, in some instances, a BS having a high priority may utilize an earlier CCA period or a shorter CCA period than a lower-priority BS.

FIG. 6A illustrates candidate SSB positions 600 within FBE frames 601, according to some aspects of the present disclosure. The candidate SSB positions 600 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using candidate SSB positions 600. In FIG. 6A, the x-axis represents time in some arbitrary units.

The candidate SSB positions 600 may include 10 candidate SSB positions 630 (0) ... 630 (9) operating at a 15kHz SCS. The candidate SSB positions 630 (0) ... 630 (9) may correspond to 2 SSBs in each of the slots 424 (1) ... 424 (5) . Candidate SSB positions 600 may represent the condition in which the idle period is located at the end of the FFP 601. FIGS. 6A and 6B illustrate an SSB periodicity of 5 ms or 10 ms. In this case, if a CCA is successful at the beginning of the FFP, the BS may transmit SSBs in the COT immediately after the CCA in candidate SSB position 630 (0) . The BS may transmit in the first 8 candidate SSB positions 630 (0) ... 630 (7) starting from the CCA. It may be desirable to transmit the SSBs at the earliest opportunity (e.g., first 8 candidate SSB positions) in valid SSB candidate positions to enable synchronization, rate matching, and measurements at the earliest opportunity. Since the first 8 candidate SSB positions 630 (0) ... 630 (7) are considered valid, the SSB candidate positions 630 (8) and 630 (9) are considered invalid candidate SSB positions 632.

Referring to candidate SSB positions 602, the candidate SSB positions 602 may include 10 candidate SSB positions 630 (0) ... 630 (9) . The candidate SSB positions 630 (0) ... 630 (9) may correspond to 2 SSBs in each of the slots 424 (1) ... 424 (5) . In contrast to candidate SSB positions 600, candidate SSB positions 602 may represent the condition in which the idle period is located at the beginning of the FFP 601 (e.g., floating COT configuration) . In this case, if a CCA is successful after the beginning idle period of the FFP, the BS may transmit SSBs in the COT immediately after the CCA. However, in this case since the idle period may at least partially overlap candidate SSB position 630 (0) , the BS may transmit in the first 8 candidate SSB positions 630 (1) ... 630 (8) starting from the CCA and after candidate SSB position 630 (0) . Since the first candidate SSB position 630 (0) is considered invalid due to at least partially overlapping the idle period the subsequent 8 candidate SSB positions 630 (1) ... 630 (8) are considered valid. The last SSB candidate position 630 (9) is considered invalid candidate SSB positions 632.

FIG. 6B illustrates candidate SSB positions 610 within FBE frames 601, according to some aspects of the present disclosure. The candidate SSB positions 610 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using candidate SSB positions 610. In FIG. 6B, the x-axis represents time in some arbitrary units.

The candidate SSB positions 610 may include 20 candidate SSB positions 630 (0) ... 630 (19) operating at a 30kHz SCS. Each of the candidate SSB positions 630 (0) ... 630 (19) may correspond to 2 SSBs in each of the slots 425 (1) ... 425 (10) . Candidate SSB positions 610 may represent the condition in which the idle period is located at the end of the FFP 601. In this case, if a CCA is successful at the beginning of the FFP, the BS may transmit SSBs in the COT immediately after the CCA. The BS may transmit in the first 8 candidate SSB positions 630 (0) ... 630 (7) starting from the CCA. It may be desirable to transmit the SSBs at the earliest opportunity (e.g., the first 8 candidate SSB positions) in valid SSB candidate positions 630 (0) ... 630 (7) to enable synchronization, rate matching and measurements at the earliest opportunity. Since the first 8 candidate SSB positions 630 (0) ... 630 (7) are considered valid, the SSB candidate positions 630 (8) and 630 (19) are considered invalid candidate SSB positions 632.

Referring to candidate SSB positions 612, the candidate SSB positions 612 may include 20 candidate SSB positions 630 (0) ... 630 (19) . The candidate SSB positions 630 (0) ... 630 (19) may correspond to 2 SSBs in each of the slots 424 (1) ... 424 (10) . In contrast to candidate SSB positions 610, candidate SSB positions 612 may represent the condition in which the idle period is located at the beginning of the FFP (e.g., floating COT configuration) . In this case, if a CCA is successful after the idle period of the beginning of the FFP, the BS may transmit SSBs in the COT immediately after the CCA. However, in this case since the idle period may at least partially overlap candidate SSB position 630 (0) , the BS may transmit SSBs in the first 8 valid candidate SSB positions 630 (1) ... 630 (8) starting from the CCA and after candidate SSB position 630 (0) . Since the first candidate SSB position 630 (0) is considered an invalid candidate position 632 due to at least partially overlapping the idle period, the subsequent 8 candidate SSB positions 630 (1) ... 630 (8) are considered valid. The last SSB candidate positions 630 (9) ... 630 (19) are also considered invalid candidate SSB positions 632.

In some instances, a processor of a base station (e.g., such as the BSs 105) may transmit a configuration to a UE (e.g., such as the UEs 115) indicating the invalid candidate SSB positions 632. Additionally or alternatively, a processor of a UE may execute code to determine the invalid candidate SSB positions 632 and/or the valid candidate positions. The UE may be configured to refrain from processing SSBs during invalid candidate SSB positions 632. The UE may conserve resources (e.g., processor execution time, battery power, memory, etc. ) required to process the SSBs by refraining from processing SSBs during invalid candidate SSB positions 632. For example, the UE may conserve the resources required to rate match a PDSCH. The UE may also conserve the resources required to measure SSBs for radio link monitoring (RLM) and/or radio resource management (RRM) .

FIG. 7 illustrates candidate SSB positions 700, 702 within FFP 301, according to some aspects of the present disclosure. The candidate SSB positions 700, 702 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using candidate SSB positions 700, 702. In FIG. 7, the x-axis represents time in some arbitrary units.

The candidate SSB positions 700 may include 10 candidate SSB positions 630 (0) ... 630 (9) within a first 2.5 ms FFP 301 operating at a 30kHz SCS followed by 10 candidate SSB positions 630 (10) ... 630 (19) within a second 2.5 ms FFP 301 operating at a 30kHz SCS. Candidate SSB positions 700 may represent the condition in which the idle period is located at the end of each of the first and second 2.5 ms FFPs 301. In this case, if a CCA is successful at the beginning of the FFP 301, the BS may transmit SSBs in the COT immediately after the CCA. The BS may transmit in the first 8 candidate SSB positions 630 (0) ... 630 (7) starting from the CCA in the first 2.5 ms FFP 301. The BS may also transmit in the first 8 candidate SSB positions 630 (10) ... 630 (17) starting from the CCA in the second 2.5 ms FFP 301. It may be desirable to transmit the SSBs at the earliest opportunity (e.g., first 8 candidate SSB positions) in valid SSB candidate positions 630 (0) ... 630 (7) and 630 (10) ... 630 (17) to enable synchronization, rate matching and measurements at the earliest opportunity. Since the first 8 candidate SSB positions 630 (0) ... 630 (7) in the first 2.5 ms FFP 301 and the first 8 candidate SSB positions 630 (10) ... 630 (17) in the second 2.5 ms FFP 301 are considered valid, the SSB candidate positions 630 (8) , 630 (9) , 630 (18) , and 630 (19) are considered invalid candidate SSB positions 632.

Referring to candidate SSB positions 702, the candidate SSB positions 702 may include 10 candidate SSB positions 630 (0) ... 630 (9) within a first 2.5 ms FFP 301 operating at a 30kHz SCS followed by 10 candidate SSB positions 630 (10) ... 630 (19) within a second 2.5 ms FFP 301 operating at a 30kHz SCS. In contrast to candidate SSB positions 700, candidate SSB positions 702 may represent the condition in which the idle period is located at the beginning of the FFP 301 (e.g., a floating COT configuration) . In this case, if a CCA is successful after the idle period of the beginning of the FFP, the BS may transmit SSBs in the COT immediately after the CCA. However, in this case since the idle period may at least partially overlap candidate SSB positions 630 (0) and 630 (10) , the BS may transmit SSBs in the first 8 valid candidate SSB positions 630 (1) ... 630 (8) of the first 2.5 ms FFP 301 and 630 (11) ... 630 (18) of the second 2.5 ms FFP 301 starting from the CCA and after candidate SSB positions 630 (0) and 630 (10) respectively. Since the first candidate SSB position 630 (0) in the first 2.5 ms FFP 301 is considered an invalid candidate position 632 due to at least partially overlapping the idle period, the subsequent 8 candidate SSB positions 630 (1) ... 630 (8) are considered valid. The last SSB candidate position 630 (9) in the first 2.5 ms FFP 301 is also considered an invalid candidate SSB position 632. Since the first candidate SSB position 630 (10) in the second 2.5 ms FFP 301 is considered an invalid candidate position 632 due to at least partially overlapping the idle period, the subsequent 8 candidate SSB positions 630 (11) ... 630 (18) are considered valid. The last SSB candidate position 630 (19) in the second 2.5 ms FFP 301 is also considered an invalid candidate SSB position 632.

The UE may be configured to refrain from processing SSBs during invalid candidate SSB positions 632. The UE may conserve resources (e.g., processor execution time, battery power, memory, etc. ) required to process the SSBs by refraining from processing SSBs during invalid candidate SSB positions 632. For example, the UE may conserve the resources required to rate match a PDSCH. The UE may also conserve the resources required to measure SSBs for radio link monitoring (RLM) and/or radio resource management (RRM) .

In some aspects, the duration of an FBE frame (e.g., the FFPs 301, 601) may not be an integer factor of the SSB period. FIGS. 8 and 9 illustrate various exemplary SSB position configuration scenarios with 30 kHz SCS and when an FBE frame has a duration of 4 ms while an SSB configuration has an SSB burst periodicity of 20 ms and 8 SSBs within an SSB burst.

FIG. 8 illustrates candidate SSB positions 800, 802, 804, and 806 within FBE slots, according to some aspects of the present disclosure. The candidate SSB positions 800, 802, 804, and 806 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using candidate SSB positions 800, 802, 804, and 806. In FIG. 8, the x-axis represents time in some arbitrary units.

In FIG. 8, candidate SSB positions 800, 802, 804, and 806 may represent the condition in which the SSB burst periodicity may be 20 ms and the FFP 0, FFP1, FFP2, FFP3, and FFP 4 each have a period of 4 ms operating at a 30kHz SCS. Although candidate SSB positions 800, 802, 804, and 806 are shown in FIG. 8 on separate lines. Candidate SSB positions 800, 802, 804, and 806 may be contiguous (e.g., consecutive) in time. Candidate SSB positions 800, 802, 804, and 806 may represent the condition in which the idle period is located at the end of FFP 0, FFP1, FFP2, FFP3, and FFP 4.

FIG. 8 shows valid and invalid SSB candidate positions 632. However, SSBs may not be transmitted in every valid SSB candidate position as the periodicity (e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms) of the SSBs will determine whether SSBs are transmitted in the valid candidate SSB positions. With a 4ms FFP, if the LBT fails for one frame, the first 16 SSB positions will be unused. However, certain candidate SSB positions in between will not be transmitted within a given DRS window. In this case, these candidate SSB positions in between should not be considered valid for UE rate matching or RLM/RRM measurement. At 30 kHz SCS, the candidate SSB positions 800 may include 20 candidate SSB positions 630 (0) ... 630 (19) within a 4 ms FFP 0 and the first 1 ms of FFP 1. In this case, if a CCA is successful at the beginning of the FFP 0, the BS may transmit SSBs in the COT immediately after the CCA. The BS may transmit in the first 8 candidate SSB positions 630 (0) ... 630 (7) starting from the CCA in the FFP 0. Since the first 8 candidate SSB positions 630 (0) ... 630 (7) in the FFP 0 are considered valid, the SSB candidate positions 630 (8) ... 630 (15) are considered invalid candidate SSB positions 632. SSB positions 800 may further include valid candidate positions 630 (16) ... 630 (19) which may be part of FFP 1. Candidate SSB positions 802 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 3 ms of FFP 1 and the first 2 ms of FFP 2 in which the SSB candidate positions 630 (8) ... 630 (11) are considered invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (7) and 630 (12) ... 630 (19) are valid candidate SSB positions. Similarly, candidate SSB positions 804 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 2 ms of FFP 2 and the first 3 ms of FFP 3 in which the SSB candidate positions 630 (16) ... 630 (19) are considered invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (15) are valid candidate SSB positions. Lastly, candidate SSB positions 806 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 1 ms of FFP 3 and the full 4 ms of FFP 4 in which the SSB candidate positions 630 (12) ... 630 (19) are considered invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (11) are valid candidate SSB positions.

FIG. 9 illustrates candidate SSB positions 900, 902, 904, and 906 within FBE slots, according to some aspects of the present disclosure. The candidate SSB positions 900, 902, 904, and 906 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using candidate SSB positions 900, 902, 904, and 906. In FIG. 9, the x-axis represents time in some arbitrary units.

In FIG. 9, candidate SSB positions 900, 902, 904, and 906 may represent the condition in which the SSB burst periodicity may be 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms and the FFP 0, FFP1, FFP2, FFP3, and FFP 4 each have a period of 4 ms operating at a 30kHz SCS. Although candidate SSB positions 900, 902, 904, and 906 are shown in FIG. 9 on separate lines. Candidate SSB positions 900, 902, 904, and 906 may be contiguous (e.g., consecutive) in time. In contrast to the embodiment described above with reference to FIG. 8, candidate SSB positions 900, 902, 904, and 906 may represent the condition in which the idle period is located at the beginning of FFP 0, FFP1, FFP2, FFP3, and FFP 4 (e.g., a floating COT configuration) .

FIG. 9 shows the valid and invalid SSB candidate positions. However, SSBs may not be transmitted in every valid SSB candidate position as the periodicity (e.g. 5 ms, 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms) of the SSBs will determine whether SSBs are transmitted in the valid candidate SSB positions.

The candidate SSB positions 900 may include 20 candidate SSB positions 630 (0) ... 630 (19) within a 4 ms FFP 0 and the first 1 ms of FFP 1. In contrast to FIG. 8, candidate SSB position 630 (0) may at least partially overlap the idle period at the beginning of FFP 0 and therefore candidate SSB position 630 (0) is considered an invalid candidate SSB position 632. In this case, if a CCA is successful at the end of the idle period at the beginning of the FFP 0, the BS may transmit SSBs in the COT immediately after the CCA. The BS may transmit in the first 8 candidate SSB positions 630 (1) ... 630 (8) starting from the CCA and after the idle period in the FFP 0. Since the first 8 candidate SSB positions 630 (1) ... 630 (8) after the idle period in the FFP 0 are considered valid, the SSB candidate positions 630 (9) ... 630 (15) are considered invalid candidate SSB positions 632. SSB positions 900 may further include invalid SSB candidate position 630 (16) which at least partially overlaps the idle period at the beginning of FFP 1 and valid candidate positions 630 (17) ... 630 (19) which may follow the idle period. Similarly, each of the first candidate SSB positions in FFP 1, FFP 2, FFP 3, and FFP 4 may be considered invalid candidates SSB positions 632 due to their at least partially overlap with the idle period at the beginning of the FFP. Candidate SSB positions 902 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 3 ms of FFP 1 and the first 2 ms of FFP 2 in which the SSB candidate positions 630 (8) ... 630 (12) are invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (7) and 630 (13) ... 630 (19) are valid candidate SSB positions. Similarly, candidate SSB positions 904 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 2 ms of FFP 2 and the first 3 ms of FFP 3 in which the SSB candidate positions 630 (8) and 630 (17) ... 630 (19) are considered invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (7) and 630 (9) ... 630 (16) are valid candidate SSB positions. Lastly, candidate SSB positions 906 may also include 20 candidate SSB positions 630 (0) ... 630 (19) comprising the last 1 ms of FFP 3 and the full 4 ms of FFP 4 in which the SSB candidate positions 630 (4) and 630 (13) ... 630 (19) are considered invalid candidate SSB positions 632 and the other candidate SSB positions 630 (0) ... 630 (3) and 630 (5) ... 630 (12) are valid candidate SSB positions.

As explained above, an FBE frame with a floating COT may include an idle period at the beginning of the FBE frame and/or an idle period at the end of the FBE frame. In some aspects, null or invalid candidate SSB positions are defined to be those candidate SSB positions in which a BS may not transmit an SSB. In this regard, null or invalid candidate SSB positions may correspond to the intersection between the candidate SSB positions in which the BS may not transmit an SSB when the entire idle period is located at the end of the FBE frame (or FFP) and candidate SSB positions in which the BS may not transmit an SSB when the entire idle period is located at the beginning of the FBE frame as shown in FIGS. 10A and 10B.

FIG. 10A illustrates

candidates SSB positions

1000, 1002 within an FBE frames 1001, according to some aspects of the present disclosure. The

candidate SSB positions

1000, 1002 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using

candidate SSB positions

1000, 1002. In FIG. 10A, the x-axis represents time in some arbitrary units.

The candidate SSB positions 1000 may include 10 candidate SSB positions 630 (0) ... 630 (9) operating at a 15kHz SCS when the FFP 1001 includes an idle period at the end of the FFP 1001. As described in detail above with reference to FIG. 6A, the first 8 candidate SSB positions 630 (0) ... 630 (7) are considered valid while the SSB candidate positions 630 (8) and 630 (9) at least partially overlap the idle period and are considered invalid candidate SSB positions 632. The candidate SSB positions 1002 may also include 10 candidate SSB positions 630 (0) ... 630 (9) operating at a 15kHz SCS when the FFP 1001 includes an idle period at the beginning of the FFP 1001 (in contrast to candidate SSB positions 1000 in which the idle period is at the end of the FFP) . As described in detail above with reference to FIG. 6A, the 8 candidate SSB positions 630 (1) ... 630 (8) are considered valid while the SSB candidate positions 630 (0) and 630 (9) are considered invalid candidate SSB positions 632. SSB candidate positions 630 (0) is considered invalid as it at least partially overlaps the idle period at the beginning of the FFP 1001.

In some instances, certain candidate SSB positions may be considered invalid based on whether the idle period is at the beginning or the end of the FFP 1001. As can be seen in

SSB positions

1000 and 1002, SSB candidate position 630 (9) is considered an invalid candidate position 632 whether the idle period is at the beginning (as shown in candidate SSB positions 1000) or the end of the FFP (as shown in candidate SSB positions 1002) . In some instances, an invalid candidate SSB position may correspond to common invalid candidate SSB positions 1018 (grouped with dashed rectangle and labeled as1018) between invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and invalid candidate SSB positions when the idle period is at an end of the FBE frame.

FIG. 10B illustrates

candidates SSB positions

1010, 1012 within an FFP 1011, according to some aspects of the present disclosure. The

candidate SSB positions

1010, 1012 may be employed by BSs such as the BSs 105 and UEs such as the UEs 115 in a network such as the network 100 for wireless communications (e.g., NR-U) . In particular, the BS may communicate with the UE in an FBE mode, for example, over a shared radio frequency band in an unlicensed spectrum or shared spectrum, using

candidate SSB positions

1010, 1012. In FIG. 10B, the x-axis represents time in some arbitrary units.

The candidate SSB positions 1010 may include 20 candidate SSB positions 630 (0) ... 630 (19) operating at a 30kHz SCS when the FFP 1011 includes an idle period located at the end of the FFP. As described in detail above with reference to FIG. 6B, the first 9 candidate SSB positions 630 (0) ... 630 (8) are considered valid while the SSB candidate positions 630 (9) ... 630 (19) are considered invalid candidate SSB positions.

The candidate SSB positions 1012 may include 20 candidate SSB positions 630 (0) ... 630 (19) operating at a 30kHz SCS when the FFP 1011 includes an idle period located at the beginning of the FFP 1011. As described in detail above with reference to FIG. 6B, the 8 candidate SSB positions 630 (1) ... 630 (8) are considered valid while the SSB candidate positions 630 (0) and 630 (9) ... 630 (19) are considered invalid candidate SSB positions 632. SSB candidate positions 630 (0) is considered invalid as it at least partially overlaps the idle period at the beginning of the FFP 1011.

In some instances, certain candidate SSB positions may be considered invalid whether the idle period is located at the beginning or the end of the FFP 1011. As can be seen in

SSB positions

1010 and 1012, SSB candidate positions 630 (9) ... 630 (19) are considered invalid candidate positions 632 whether the idle period is located at the beginning or the end of the FFP 1011. In some instances, an invalid candidate SSB position may corresponds to a common invalid candidate SSB positions 1018 (grouped with dashed rectangle and labeled as 1018) between invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and invalid candidate SSB positions when the idle period is at an end of the FBE frame.

FIG. 11 is a table illustrating invalid candidate SSB positions within FBE frames, according to some aspects of the present disclosure. The table 1100 shows invalid candidate SSB positions within consecutive FBE frames for 30 kHz SCS and 15 kHz SCS for different fixed frame periods. As described above with reference to FIGS. 10A-10B, certain candidate SSB positions may be invalid based on whether the idle period is located at the beginning or the end of the FFP. These invalid SSB positions are the candidate SSB positions that corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame. For example, when the FFP is 1 ms or 2 ms, there are no common invalid SSB position for 15 kHz SCS or 30 kHz SCS. For a 2.5 ms FFP and 30 kHz SCS, the invalid SSB candidate positions may include SSB candidate positions 630 (9) and 630 (19) as described above with reference to FIG. 7. For a 4 ms FFP and 30 kHz SCS, the invalid SSB candidate positions may include SSB candidate positions 630 (9) -630 (15) , 630 (8) -630 (11) , 630 (17) -630 (19) , or 630 (13) -630 (19) based on the common invalid candidate SSB positions between the invalid SSB candidate positions of FIG. 8 (idle period located at the end of the FFP) and the invalid SSB candidate positions of FIG. 9 (idle period located at the beginning of the FFP) . As another example, when the FFP is 5 ms or 10 ms and 30 kHz SCS, the common invalid SSB candidate positions may include SSB candidate positions 630 (9) and 630 (19) as described above with reference to FIG. 10B. As another example, when the FFP is 5 ms or 10 ms and 15 kHz SCS, the common invalid SSB candidate positions may include SSB candidate position 630 (9) as described above with reference to FIG. 10A.

If SSBs are not transmitted (e.g., transmitted by a BS) at invalid SSB positions, the UE may conserve the resources (e.g., processor execution time, battery power, memory, etc. ) required for processing the SSBs. For example, the UE may conserve the resources required to rate match a PDSCH over the invalid candidate SSB positions as indicated in Table 1100. The UE may also conserve the resources required to measure SSBs for radio link monitoring (RLM) and/or radio resource management (RRM) by refraining from performing RLM/RRM processing during invalid candidate SSB positions as indicated in Table 1100.

FIG. 12 illustrates a DRS window for valid SSB candidate positions according to some aspects of the present disclosure. In some instances, a DRS window 1245 may define a time window (e.g., time period) in which valid SSB candidates may be transmitted to a UE for FBE scenarios that use a floating COT. The DRS window 1245 length may be configured by an RRC message (e.g., an information element indicating the DRS window 1245 length) . When the FFP is 5ms or 10ms, if the DRS window 1245 length is not configured, the DRS window 1245 length may be limited to 2ms for 30kHz SCS and 4ms for 15kHz SCS. As another example, when the FFP is 2.5ms, if the DRS window 1245 length is not configured, the DRS window 1245 length may be limited to 2ms for 30kHz SCS. The DRS window may be configured with a DRS window offset 1250. The DRS window offset 1250 may be the time from the beginning of the FFP to the beginning of the DRS window 1245

In the example of FIG. 12, the FFP is configured as 5 ms, the DRS window 1245 length is configured as 4 ms, and the DRS window offset is configured as 0.5 ms. In some instances, SSB candidate positions that fall within the DRS window may be considered valid and SSB candidate positions that fall within the DRS window offset may be considered invalid. For example, slot 424 (1) may include DRS window offset 1250 that occurs during OFDM symbols 426 (0) -426 (6) . OFDM symbols 426 (0) -426 (6) may not include valid SSB candidate positions because they occur during the DRS window offset 1250. However, OFDM symbols 426 (7) -426 (13) may occur after the DRS window offset 1250 and during the DRS window 1245 (e.g., partial overlap with DRS window 1245) . The OFDM symbols 426 (7) -426 (13) may be considered valid SSB candidate positions and an SSB may be transmitted in four consecutive OFDM symbols 426 (8) -426 (11) . Slots 424 (2) , 424 (3) , 424 (4) may at least partially overlap (e.g., completely overlap or completely within) the DRS window 1245 and therefore may include valid SSB candidate positions. For example, OFDM symbols 426 (2) -426 (5) and 426 (8) -426 (11) may be considered valid SSB candidate positions within slots 424 (2) , 424 (3) , 424 (4) .

Similar to slot 424 (1) , slot 424 (5) may partially overlap the DRS window 1245 and therefore the at least partially overlapping portion (e.g., first 0.5 ms including OFDM symbols 426 (1) –426 (7) ) may include valid candidate SSB positions. However, the last 0.5 ms including OFDM symbols 426 (8) –426 (14) ) may include invalid candidate SSB positions.

FIG. 13 illustrates a DRS duration 1326 for valid SSB candidate positions according to some aspects of the present disclosure. FIG. 13 illustrates a similar embodiment to FIG. 12 in which a DRS window is defined which includes valid SSB candidate positions. The difference between FIG. 12 and FIG. 13 is that in FIG. 12 the DRS window 1245 starts after the DRS window offset. Whereas, in FIG. 13, the DRS duration 1326 begins at the start of the FFP.

In some instances, a DRS duration 1326 may define a time period that repeats at the periodicity of the FFP (e.g., 20 ms) . FIG. 13 further shows a DRS duration starting offset 1325. The DRS duration starting offset 1325 may define a time period at the beginning of the DRS duration 1326 which includes invalid SSB candidate positions. The time period in the DRS duration 1326 after the DRS duration starting offset 1325 may be a time period in which valid SSB candidates may be transmitted to a UE for FBE scenarios that use a floating COT.

The DRS duration 1326 length may be configured by an RRC message (e.g., an information element indicating the DRS duration 1326 length) . For example, when the FFP is 5ms or 10ms, if the DRS duration 1326 length is not configured, the DRS duration 1326 length may be limited to 2.25 ms/2.5 ms for 30kHz SCS and 4.5 ms for 15kHz SCS. As another example, when the FFP is 2.5ms, if the DRS duration 1326 length is not configured, the DRS duration 1326 length may be limited to 2.25 ms/2.5 ms for 30kHz SCS. The DRS duration 1326 may be configured with a DRS window starting offset 1325. The DRS window starting offset 1325 may be the time from the beginning of the FFP to the beginning of a time period within the DRS duration 1326 that includes valid SSB candidate positions. Although FIG. 13 shows a DRS duration 1326 of 4.5 ms, since the DRS window starting offset 1325 is 0.5 ms, the time period in which candidates SSB positions are valid is equal to 4 ms creating an effective DRS window of 4 ms.

In the example of FIG. 13, the FFP is configured as 5 ms, the DRS duration 1326 is configured as 4.5 ms, and the DRS window starting offset 1325 is configured as 0.5 ms. In some instances, the SSB candidate positions that fall within the effective DRS window of 4 ms may be considered valid and SSB candidate positions that fall within the DRS window starting offset 1325 may be considered invalid. For example, slot 424 (1) may include DRS window starting offset 1325 that occurs during OFDM symbols 426 (0) -426 (6) . OFDM symbols 426 (0) -426 (6) may not include valid SSB candidate positions because they occur during the DRS window starting offset 1325. However, OFDM symbols 426 (7) -426 (13) may occur after the DRS window starting offset 1325 and during the DRS duration 1326. The OFDM symbols 426 (7) -426 (13) may be considered valid SSB candidate positions and an SSB may be transmitted in four consecutive OFDM symbols, for example, OFDM symbols 426 (8) -426 (11) . Similarly, slots 424 (2) , 424 (3) , and 424 (4) may at least partially overlap (e.g., completely overlap) the DRS duration 1326 and therefore may include valid SSB candidate positions. For example, OFDM symbols 426 (2) -426 (5) and 426 (8) -426 (11) in slots 424 (2) , 424 (3) , and 424 (4) may be considered valid SSB candidate positions.

Similar to slot 424 (1) , slot 424 (5) may partially overlap the DRS duration 1326 and therefore the at least partially overlapping portion (e.g., first 0.5 ms including OFDM symbols 426 (1) –426 (7) ) may include valid candidate SSB positions. However, the last 0.5 ms including OFDM symbols 426 (8) –426 (14) ) of slot 424 (5) may include invalid candidate SSB positions.

FIG. 14 illustrates invalid SSB candidate positions within a floating COT according to some aspects of the present disclosure. As described above with reference to FIGS. 5A and 5B, an FFP may include an idle period at the start of the FFP or at the end of the FFP. In some instances, a first portion of the idle period may be at the beginning of the FFP and a second portion of the idle period may be at the end of the FFP. For example, as shown in FIG. 14, in FFP 301 the idle period 304 is at the beginning of the FFP 301. In contrast, the idle period 306 is at the end of the FFP 303. In some instances, the

idle period

304, 306 may dynamically switch between the beginning and the end of the FFP for each FFP due to variable starting time for floating COTs described above. Further, the idle period may be of variable length with a minimum period required for each FFP. In order to cover the worst-case scenario in which the idle period 304 is at the beginning of the FFP 301 and the worst-case scenario in which the idle period 306 is located at the end of the FFP 303, invalid candidate SSB positions may be designated to cover both scenarios. FIGS. 12 and 13 showed examples of invalid candidate SSB positions when the idle period is at the start of the FFP. However, the example of FIG. 14 handles both cases of when the idle period 304 is at the beginning of the FFP 301 or when the idle period 306 is at the end of the FFP 303.

Subframe 422 (1) may be configured (e.g., configured via RRC signaling) to have an idle period 304 at the beginning of the sub-period 422 (1) . As described in detail above with reference to FIG. 13, DRS duration 1326 may be 4.5 ms. The DRS duration 1326 may begin at the beginning of sub-period 422 (1) and a DRS window starting offset 1325 of 0.5 ms may define an effective DRS window of 4 ms. SSB candidate positions after the DRS window starting offset 1325, but within the DRS duration 1326, may be considered valid. SSB candidate positions that fall within the DRS window starting offset 1325 may be considered invalid. Further, SSB candidate positions that fall outside the DRS duration 1326 may be considered invalid.

For example, DRS window starting offset 1325 may occurs during OFDM symbols 426 (0) -426 (6) of sub-period 422 (1) . OFDM symbols 426 (0) -426 (6) of sub-period 422 (1) may include invalid SSB candidate positions because they occur during the DRS window starting offset 1325. However, OFDM symbols 426 (7) -426 (13) of sub-period 422 (1) may occur after the DRS window starting offset 1325 and during the DRS duration 1326. The OFDM symbols 426 (7) -426 (13) of sub-period 422 (1) may be considered valid SSB candidate positions and an SSB may be transmitted in four consecutive OFDM symbols, for example, OFDM symbols 426 (8) -426 (11) .

Idle period 306 may partially overlap sub-period 422 (4) . Since SSBs cannot be transmitted during idle periods, OFMD symbols that at least partially overlap idle periods may be considered invalid. For example, OFDM symbols 426 (7) -426 (13) of sub-period 422 (4) may at least partially overlap idle period 306 and be considered invalid. However, OFDM symbols 426 (0) -426 (6) of sub-period 422 (4) may be within the DRS duration 1326 and may not partially overlap the idle period 306, therefore OFDM symbols 426 (0) -426 (6) of sub-period 422 (4) may be considered valid SSB candidate positions.

FIG. 15 illustrates invalid SSB candidate positions at least partially overlapping idle periods according to some aspects of the present disclosure. FIG. 15 illustrates a 5 ms FFP frame 301 which includes a beginning idle period 1540 at the beginning of the slot 424 (1) and an ending idle period 1542 at the end of the slot 424 (1) . As shown in FIG. 15, beginning idle period 1540 at least partially overlaps the SSB candidate position 630 (0) (e.g., the period covering OFDM symbols 426 (0) –426 (6) ) . Considering that an SSB may not be transmitted during an idle period as described above with reference to FIG. 14, the SSB candidate position 630 (0) may be considered an invalid candidate SSB position 632. However, the adjacent candidate SSB candidate position 630 (1) (e.g., the period covering OFDM symbols 426 (7) –426 (13) ) may be considered valid since ending idle period 1542 does not at least partially overlap with SSB candidate position 630 (1) .

As discussed above with reference to FIGS. 10A and 10B, an invalid candidate SSB position 632 may correspond to common invalid candidate SSB positions between invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and invalid candidate SSB positions when the idle period is at an end of the FBE frame. In the example of FIG. 15, when the SCS is configured at 15kHz, candidate SSB position 630 (9) is invalid as it is a common invalid candidate SSB position between invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and invalid candidate SSB positions when the idle period is at an end of the FBE frame.

The invalid candidate SSB positions 630 (0) and 630 (9) correspond to a combined approach of invalidating candidate SSB positions when the candidate SSB positions at least partially overlap an idle period or when the candidate SSB positions are common to an idle period at a beginning of an FBE frame and an idle period at an end of an FBE frame.

FIG. 16 is a block diagram of an exemplary UE 1600 according to some aspects of the present disclosure. The UE 1600 may be a UE 115 in the network 100 as discussed above in FIG. 1. As shown, the UE 1600 may include a processor 1602, a memory 1604, a SSB position invalidation module 1608, a transceiver 1610 including a modem subsystem 1612 and a RF unit 1614, and one or more antennas 1616. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 1602 may have various features as a specific-type processor. For example, these may include a CPU, a DSP, an ASIC, a controller, a FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1602 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.

The memory 1604 may include a cache memory (e.g., a cache memory of the processor 1102) , RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard disk drives, memristor-based arrays, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some aspects, the memory 1604 may include a non-transitory computer-readable medium. The memory 1604 may store instructions 1606. The instructions 1606 may include instructions that, when executed by the processor 1602, cause the processor 1602 to perform operations described herein, for example, aspects of FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. Instructions 1606 may also be referred to as program code. The program code may be for causing a wireless communication device to perform these operations, for example by causing one or more processors (such as processor 1102) to control or command the wireless communication device to do so. The terms “instructions” and “code” should be interpreted broadly to include any type of computer-readable statement (s) . For example, the terms “instructions” and “code” may refer to one or more programs, routines, sub-routines, functions, procedures, etc. “Instructions” and “code” may include a single computer-readable statement or many computer-readable statements.

The SSB position invalidation module 1608 may be implemented via hardware, software, or combinations thereof. For example, the SSB position invalidation module 1608 may be implemented as a processor, circuit, and/or instructions 1606 stored in the memory 1604 and executed by the processor 1602. In some instances, the SSB position invalidation module 1608 can be integrated within the modem subsystem 1612. For example, the SSB position invalidation module 1608 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1612.

The SSB position invalidation module 1608 may communicate with various components of the UE 1600 to implement various aspects of the present disclosure, for example, aspects of FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. In some aspects, the SSB position invalidation module 1608 is configured to cause the UE 1600 to receive from a BS (e.g., the BSs 105, 1700) , a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. The SSB position invalidation module 1608 is configured to cause the UE 1600 to identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and receive from a BS (e.g., the BSs 105, 1700) , an SSB at a position other than the at least one invalid candidate SSB position. In this regard, the SSB position invalidation module 1608 may be configured to receive from a BS (e.g., the BSs 105, 1700) , a COT starting position and a DRS window offset.

In some instances, the DRS window offset begins at a beginning of the FBE frame, a DRS window begins at an end of the DRS window offset, and the at least one invalid candidate SSB position is at least partially located outside the DRS window. In some instances, the invalid candidate SSB position at least partially overlaps the idle period. In some instances, the configuration received by the UE 1600 indicates that the SSB is communicated at an earliest opportunity within the FBE frame. The configuration may include a fixed frame period. In some instance, the invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset, or a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.

The UE 1600 may be configured to refrain from rate matching around the invalid candidate SSB positions. The UE 1600 may also be configured to refrain from performing radio link monitoring (RLM) measurements or radio resource management (RRM) measurements at the invalid candidate SSB positions. By refraining from rate matching and performing measurements during the invalid candidate SSB positions, the UE 1600 may conserve computing resources, memory, and power consumption.

As shown, the transceiver 1610 may include the modem subsystem 1612 and the RF unit 1614. The transceiver 1610 can be configured to communicate bi-directionally with other devices, such as the BSs 105 and/or another core network element. The modem subsystem 1612 may be configured to modulate and/or encode data according to a MCS, e.g., a LDPC coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 1614 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., RRC configuration, PRACH configurations, PDCCH signals, SSB, PDSCH signals, UL data) from the modem subsystem 1612 (on outbound transmissions) or of transmissions originating from another source such as a BS 105. The RF unit 1614 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 1610, the modem subsystem 1612 and/or the RF unit 1614 may be separate devices that are coupled together at the UE 115 to enable the UE 115 to communicate with other devices.

The RF unit 1614 may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may contain one or more data packets and other information) , to the antennas 1616 for transmission to one or more other devices. This may include, for example, transmission of information to complete attachment to a network and communication with a BS 105 according to some aspects of the present disclosure. The antennas 1616 may further receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver 1610. The transceiver 1610 may provide the demodulated and decoded data (e.g., PUSCH signals, PUCCH signals, SSB, PRACH, BCH) to the SSB position invalidation module 1608 for processing. The antennas 1116 may include multiple antennas of similar or different designs in order to sustain multiple transmission links.

In an aspect, the UE 1600 can include multiple transceivers 1610 implementing different RATs (e.g., NR and LTE) . In an aspect, the UE 1600 can include a single transceiver 1610 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 1610 can include various components, where different combinations of components can implement different RATs.

FIG. 17 is a block diagram of an exemplary BS 1700 according to some aspects of the present disclosure. The BS 1700 may be a BS 105 as discussed above with respect to FIG. 1. As shown, the BS 1700 may include a processor 1702, a memory 1704, a SSB position invalidation module 1708, a transceiver 1710 including a modem subsystem 1712 and a radio frequency (RF) unit 1714, and one or more antennas 1716. These elements may be in direct or indirect communication with each other, for example via one or more buses.

The processor 1702 may include a central processing unit (CPU) , a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. The processor 1702 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.

The memory 1704 may include a cache memory (e.g., a cache memory of the processor 1202) , random access memory (RAM) , magnetoresistive RAM (MRAM) , read-only memory (ROM) , programmable read-only memory (PROM) , erasable programmable read only memory (EPROM) , electrically erasable programmable read only memory (EEPROM) , flash memory, solid state memory device, hard disk drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an aspect, the memory 1704 includes a non-transitory computer-readable medium. The memory 1704 may store, or have recorded thereon, instructions 1706. The instructions 1706 may include instructions that, when executed by the processor 1702, cause the processor 1702 to perform the operations described herein with reference to the BSs 105 in connection with aspects of the present disclosure, for example, aspects of FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. Instructions 1706 may also be referred to as program code, which may be interpreted broadly to include any type of computer-readable statement (s) as discussed above with respect to FIG. 16.

The SSB position invalidation module 1708 may be implemented via hardware, software, or combinations thereof. For example, the SSB position invalidation module 1708 may be implemented as a processor, circuit, and/or instructions 1706 stored in the memory 1704 and executed by the processor 1702. In some instances, the SSB position invalidation module 1708 can be integrated within the modem subsystem 1712. For example, the SSB position invalidation module 1708 can be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the modem subsystem 1712.

The SSB position invalidation module 1708 may communicate with various components of the BS 1700 to implement various aspects of the present disclosure, for example, aspects of FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. In some aspects, the SSB position invalidation module 1708 is configured to cause the BS 1700 to transmit to a UE (e.g., the UEs 115, 1600) , a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. The SSB position invalidation module 1708 is configured to cause the BS 1700 to identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and transmit to a UE (e.g., the UEs 115, 1600) , an SSB at a position other than the at least one invalid candidate SSB position.

In this regard, the SSB position invalidation module 1708 may be configured to transmit to a UE (e.g., the UEs 115, 1600) , a COT starting position and a DRS window offset. In some instances, the DRS window offset begins at a beginning of the FBE frame, a DRS window begins at an end of the DRS window offset, and the at least one invalid candidate SSB position is at least partially located outside the DRS window. In some instances, the invalid candidate SSB position at least partially overlaps the idle period. In some instances, the configuration transmitted to a UE (e.g., the UEs 115, 1600) , indicates that the SSB is communicated at an earliest opportunity within the FBE frame. The configuration may include a fixed frame period. In some instances, the invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset, or a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.

The BS 1700 may be configured to command a UE (e.g., the UEs 115, 1600) to refrain from rate matching around the invalid candidate SSB positions. The BS 1700 may also be configured to command a UE to refrain from performing radio link monitoring (RLM) measurements or radio resource management (RRM) measurements at the invalid candidate SSB positions. By refraining from rate matching and performing measurements during the invalid candidate SSB positions, the UE 1600 may conserve computing resources, memory, and power consumption.

As shown, the transceiver 1710 may include the modem subsystem 1712 and the RF unit 1714. The transceiver 1710 can be configured to communicate bi-directionally with other devices, such as the UEs 115, 1600. The modem subsystem 1712 may be configured to modulate and/or encode the data from the memory 1704 and/or the SSB position invalidation module 1708 according to a modulation and coding scheme (MCS) , e.g., a low-density parity check (LDPC) coding scheme, a turbo coding scheme, a convolutional coding scheme, a digital beamforming scheme, etc. The RF unit 1714 may be configured to process (e.g., perform analog to digital conversion or digital to analog conversion, etc. ) modulated/encoded data (e.g., the invalid candidate SSB positions, PUSCH signals, PUCCH signals) from the modem subsystem 1712 (on outbound transmissions) or of transmissions originating from another source such as a UE 115 or a BS 105. The RF unit 1714 may be further configured to perform analog beamforming in conjunction with the digital beamforming. Although shown as integrated together in transceiver 1710, the modem subsystem 1712 and the RF unit 1714 may be separate devices that are coupled together at the BS 105 or 1700 to enable the UE 115 or 1600 to communicate with other devices.

The RF unit 1714 may provide the modulated and/or processed data, e.g. data packets (or, more generally, data messages that may include one or more data packets and other information) , to the antennas 1716 for transmission to one or more other devices. The antennas 1716 may further receive data messages transmitted from other devices. The antennas 1716 may provide the received data messages for processing and/or demodulation at the transceiver 1710. The transceiver 1710 may provide the demodulated and decoded data (e.g., RRC configuration, PRACH configurations, PDCCH signals, SIB, PDSCH signals, BCH Signals, DL data) to the SSB position invalidation module 1708 for processing. The antennas 1716 may include multiple antennas of similar or different designs in order to sustain multiple transmission links. The RF unit 1714 may configure the antennas 1716.

In some aspects, the transceiver 1710 is configured to communicate with other components of the BS 1700 to receive, from a UE, a PRACH preamble from a sequence of random preambles in the set of frequency interlaces being in a different component carrier of a set of component carriers. The transceiver 1710 is further configured to communicate with other components of the BS 1700 to receive, from the UE in the set of frequency interlaces, an uplink RACH signal comprising SSB, and communicate, with the UE based on the PRACH, a communication signal in one or more component carriers of the set of component carriers.

In an aspect, the BS 1700 can include multiple transceivers 1710 implementing different RATs (e.g., NR and LTE) . In an aspect, the BS 1700 can include a single transceiver 1710 implementing multiple RATs (e.g., NR and LTE) . In an aspect, the transceiver 1710 can include various components, where different combinations of components can implement different RATs.

FIG. 18 is a flow diagram of a wireless communication method 1800 according to some aspects of the present disclosure. Aspects of the method 1800 can be executed by a computing device (e.g., a processor, processing circuit, and/or other suitable component) of a wireless communication device or other suitable means for performing the steps. For example, a wireless communication device, such as a UE 115 or the UE 1600, may utilize one or more components, such as the processor 1602, the memory 1604, the SSB position invalidation module 1608, the transceiver 1610, the modem 1612, and the one or more antennas 1616, to execute the steps of method 1800. As another example, a wireless communication device, such as a BS 105 or the BS 1700, may utilize one or more components, such as the processor 1702, the memory 1704, the SSB position invalidation module 1708, the transceiver 1710, the modem 1712, and the one or more antennas 1716, to execute the steps of method 1800.

The method 1800 may employ similar mechanisms as described above with reference to FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. As illustrated, the method 1800 includes a number of enumerated steps, but aspects of the method 1800 may include additional steps before, after, and in between the enumerated steps. In some aspects, one or more of the enumerated steps may be omitted or performed in a different order.

At block 1810, a first wireless communication device (e.g., the BS 105, the BS 1700, the UE 115 or the UE 1600) transmits a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period. In some instances, the COT may be a floating COT in which the idle period may be configured at the beginning of the COT. Additionally or alternatively, the COT may be a floating COT in which the idle period may be configured at the end of the COT. In some instances, a first portion of the idle period may be configured at the beginning of the COT and a second portion of the idle period may be configured at the end of the COT. The configuration for a plurality of frame-based equipment (FBE) frames may be transmitted by the first wireless communication device to a second wireless communication device (e.g., the BS 105, the BS 1700, the UE 115 or the UE 1600) in an RRC message. The FBE frames may be similar to the FFPs 301 of FIG. 3.

At block 1820, the first wireless communication device identifies at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames. The first wireless communication device may identify at least one invalid candidate SSB position according to the methods described above with reference to FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. For example, the first wireless communication device may identify the at least one invalid candidate SSB position corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame. As another example, the first wireless communication device may identify the at least one invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset, or a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.

At block 1830, the first wireless communication device may communicate, with the second wireless communication device, an SSB at a position other than the at least one invalid candidate SSB position. For example, the first wireless communication device may transmit an SSB to the second wireless communication device at a valid SSB candidate position as described above with reference to FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15. Further, the first wireless communication device may refrain from transmitting an SSB in the invalid SSB candidate positions as described above with reference to FIGS. 2, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7, 8, 9, 10A, 10B, 11, 12, 13, 14, and 15.

By way of non-limiting examples, the following aspects are included in the present disclosure.

Aspect 1 includes a method of wireless communication performed by a first wireless communication device, the method comprising communicating, with a second wireless communication device, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period, identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames, and communicating, with the second wireless communication device, an SSB at a position other than the at least one invalid candidate SSB position.

Aspect 2 includes the method of aspect 1, wherein the communicating the configuration comprises communicating, with the second wireless communication device, a COT starting position.

Aspect 3 includes the method of any of aspects 1-2, wherein the communicating the configuration comprises communicating, with the second wireless communication device, a discovery reference signal (DRS) window offset.

Aspect 4 includes the method of any of aspects 1-3, wherein the DRS window offset begins at a beginning of the FBE frame, a DRS window begins at an end of the DRS window offset, and

the at least one invalid candidate SSB position is at least partially located outside the DRS window.

Aspect 5 includes the method of any of aspects 1-4, wherein a DRS duration begins at the beginning of the FBE frame, and an end of the DRS window is based on the DRS duration.

Aspect 6 includes the method of any of aspects 1-5, wherein the at least one invalid candidate SSB position at least partially overlaps the idle period.

Aspect 7 includes the method of any of aspects 1-6, wherein the configuration indicates that the SSB is communicated at an earliest opportunity within the FBE frame.

Aspect 8 includes the method of any of aspects 1-7, wherein the at least one invalid candidate SSB position corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame.

Aspect 9 includes the method of any of aspects 1-8, wherein the configuration includes a fixed frame period configuration.

Aspect 10 includes the method of any of aspects 1-9, wherein the at least one invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset, or a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.

Aspect 11 includes the method of any of aspects 1-10, wherein the worst-case idle period comprises a period associated with a fixed frame period.

Aspect 12 includes the method of any of aspects 1-11, further comprising refraining, by the first wireless communication device, from communicating the SSB at the at least one invalid candidate SSB position.

Aspect 13 includes the method of any of aspects 1-12, further comprising refraining from rate matching around the at least one invalid candidate SSB position.

Aspect 14 includes the method of any of aspects 1-13, further comprising refraining from performing at least one of a radio link monitoring (RLM) measurement or a radio resource management (RRM) measurement at the at least one invalid candidate SSB position.

Aspect 15 includes the method of any of aspects 1-14, wherein the first wireless communication device is a user equipment (UE) and the second wireless communication device is a base station (BS) .

Aspect 16 includes a user equipment (UE) , comprising a memory, a transceiver, and at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to perform any one of aspects 1-15.

Aspect 16 includes a base station (BS) , comprising a memory, a transceiver, and at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to perform any one of aspects 1-15.

Aspect 18 includes a user equipment (UE) comprising means for performing any one of aspects 1-15.

Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of [at least one of A, B, or C] means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) .

As those of some skill in this art will by now appreciate and depending on the particular application at hand, many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of use of the devices of the present disclosure without departing from the spirit and scope thereof. In light of this, the scope of the present disclosure should not be limited to that of the particular embodiments illustrated and described herein, as they are merely by way of some examples thereof, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.

Claims

A method of wireless communication performed by a first wireless communication device, the method comprising:

communicating, with a second wireless communication device, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period;

identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames; and

communicating, with the second wireless communication device, an SSB at a position other than the at least one invalid candidate SSB position.
The method of claim 1, wherein the communicating the configuration comprises:

communicating, with the second wireless communication device, a COT starting position.
The method of claim 1, wherein the communicating the configuration comprises:

communicating, with the second wireless communication device, a discovery reference signal (DRS) window offset.
The method of claim 3, wherein:

the DRS window offset begins at a beginning of the FBE frame;

a DRS window begins at an end of the DRS window offset; and

the at least one invalid candidate SSB position is at least partially located outside the DRS window.
The method of claim 4, wherein:

a DRS duration begins at the beginning of the FBE frame; and

an end of the DRS window is based on the DRS duration.
The method of claim 1, wherein the at least one invalid candidate SSB position at least partially overlaps the idle period.
The method of claim 1, wherein the configuration indicates that the SSB is communicated at an earliest opportunity within the FBE frame.
The method of claim 1, wherein the at least one invalid candidate SSB position corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame.
The method of claim 1, wherein the configuration includes a fixed frame period configuration.
The method of claim 1, wherein:

the at least one invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset; or

a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.
The method of claim 10, wherein the worst-case idle period comprises a period associated with a fixed frame period.
The method of claim 1, further comprising:

refraining, by the first wireless communication device, from communicating the SSB at the at least one invalid candidate SSB position.
The method of claim 1, further comprising:

refraining from rate matching around the at least one invalid candidate SSB position.
The method of claim 1, further comprising:

refraining from performing at least one of a radio link monitoring (RLM) measurement or a radio resource management (RRM) measurement at the at least one invalid candidate SSB position.
The method of claim 1, wherein the first wireless communication device is a user equipment (UE) and the second wireless communication device is a base station (BS) .
A user equipment (UE) , comprising:

a memory;

a transceiver; and

at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to:

receive, from a base station (BS) via the transceiver, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period;

identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames; and

receive, from the BS via the transceiver, an SSB at a position other than the at least one invalid candidate SSB position.
The UE of claim 16, wherein the configuration comprises a COT starting position.
The UE of claim 16, wherein the configuration comprises a discovery reference signal (DRS) window offset.
The UE of claim 18, wherein:

the DRS window offset begins at a beginning of the FBE frame;

a DRS window begins at an end of the DRS window offset; and

the at least one invalid candidate SSB position is at least partially located outside the DRS window.
The UE of claim 19, wherein:

a DRS duration begins at the beginning of the FBE frame; and

an end of the DRS window is based on the DRS duration.
The UE of claim 16, wherein the at least one invalid candidate SSB position at least partially overlaps the idle period.
The UE of claim 16, wherein the configuration indicates that the SSB is communicated at an earliest opportunity within the FBE frame.
The UE of claim 16, wherein the at least one invalid candidate SSB position corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame.
The UE of claim 16, wherein:

the at least one invalid candidate SSB position corresponds to at least one of a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset; or

a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.
The UE of claim 24, wherein the worst-case idle period comprises a period associated with a fixed frame period.
A base station (BS) , comprising:

a memory;

a transceiver; and

at least one processor coupled to the memory and the transceiver, wherein the at least one processor is configured to:

transmit, to a user equipment (UE) via the transceiver, a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period;

identify at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames; and

transmit, to the UE via the transceiver, an SSB at a position other than the at least one invalid candidate SSB position.
The BS of claim 26, wherein the at least one processor is further configured to:

transmit, to the UE via the transceiver, a discovery reference signal (DRS) window offset, wherein:

the DRS window offset begins at a beginning of the FBE frame;

a DRS window begins at an end of the DRS window offset; and

the at least one invalid candidate SSB position is at least partially located outside the DRS window.
The BS of claim 26, wherein the at least one invalid candidate SSB position corresponds to a common invalid candidate SSB position between one or more first invalid candidate SSB positions when the idle period is at a beginning of the FBE frame and one or more second invalid candidate SSB positions when the idle period is at an end of the FBE frame.
The BS of claim 26, wherein:

the at least one invalid candidate SSB position corresponds to at least one of:

a first candidate SSB position that partially overlaps a discovery reference signal (DRS) window offset; or

a second candidate SSB position that partially overlaps a worst-case idle period at an end of the FBE frame.
A user equipment (UE) comprising:

means for receiving, from a base station (BS) , a configuration for a plurality of frame-based equipment (FBE) frames, each FBE frame of the plurality of FBE frames including a channel occupancy time (COT) period and an idle period;

means for identifying at least one invalid candidate synchronization signal block (SSB) position within an FBE frame of the plurality of FBE frames; and

means for receiving, from the BS, an SSB at a position other than the at least one invalid candidate SSB position.