WO2024007233A1

WO2024007233A1 - Random access channel procedure in inter-band carrier aggregation with synchronization signal block-less carrier

Info

Publication number: WO2024007233A1
Application number: PCT/CN2022/104276
Authority: WO
Inventors: Hung Dinh LY; Kexin XIAO
Original assignee: Qualcomm Incorporated
Priority date: 2022-07-07
Filing date: 2022-07-07
Publication date: 2024-01-11

Abstract

Certain aspects of the present disclosure provide a method of wireless communication by a user equipment (UE), generally including detecting a synchronization signal block (SSB) in a first carrier, determining whether a second carrier is configured to transmit SSBs, selecting, based on the determination, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure, and performing the RACH procedure on the second carrier using the selected parameters.

Description

RANDOM ACCESS CHANNEL PROCEDURE IN INTER-BAND CARRIER AGGREGATION WITH SYNCHRONIZATION SIGNAL BLOCK-LESS CARRIER

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to random access channel (RACH) procedures in carriers that lack Synchronization Signal Block (SSB) transmissions.

Description of Related Art

Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, or other similar types of services. These wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available wireless communications system resources with those users.

Although wireless communications systems have made great technological advancements over many years, challenges still exist. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and wireless receivers. Accordingly, there is a continuous desire to improve the technical performance of wireless communications systems, including, for example: improving speed and data carrying capacity of communications, improving efficiency of the use of shared communications mediums, reducing power used by transmitters and receivers while performing communications, improving reliability of wireless communications, avoiding redundant transmissions and/or receptions and related processing, improving the coverage area of wireless communications, increasing the number and types of devices that can access wireless communications systems, increasing the ability for different types of devices to intercommunicate, increasing the number and type of wireless communications mediums available for use, and the like. Consequently, there exists a need for further improvements in wireless communications systems to overcome the aforementioned technical challenges and others.

SUMMARY

One aspect provides a method of wireless communications by a user equipment (UE) . The method includes detecting a synchronization signal block (SSB) in an first carrier; determining whether a second carrier is configured to transmit SSBs; selecting, based on the determination, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure; and performing the RACH procedure on the second carrier using the selected parameters.

Another aspect provides a method of wireless communications by a network entity. The method includes transmitting information indicating a first carrier is configured for SSB transmissions; determining, based on whether a second carrier is configured to transmit SSBs, one or more parameters for transmission or reception of one or more messages of a RACH procedure; and participating in the RACH procedure with a UE on the second carrier using the parameters.

Other aspects provide: an apparatus operable, configured, or otherwise adapted to perform any one or more of the aforementioned methods and/or those described elsewhere herein; a non-transitory, computer-readable media comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform the aforementioned methods as well as those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising code for performing the aforementioned methods as well as those described elsewhere herein; and/or an apparatus comprising means for performing the aforementioned methods as well as those described elsewhere herein. By way of example, an apparatus may comprise a processing system, a device with a processing system, or processing systems cooperating over one or more networks.

The following description and the appended figures set forth certain features for purposes of illustration.

BRIEF DESCRIPTION OF DRAWINGS

The appended figures depict certain features of the various aspects described herein and are not to be considered limiting of the scope of this disclosure.

FIG. 1 depicts an example wireless communications network.

FIG. 2 depicts an example disaggregated base station architecture.

FIG. 3 depicts aspects of an example base station and an example user equipment.

FIGS. 4A, 4B, 4C, and 4D depict various example aspects of data structures for a wireless communications network.

FIG. 5 depicts a call flow diagram for a 4-step random access channel (RACH) procedure.

FIG. 6 depicts a call flow diagram for a 2-step RACH procedure.

FIG. 7 depicts a table describing potential overhead reduction achievable configuring carriers without synchronization signal block (SSB) transmissions.

FIG. 8 depicts example changes resulting from the configuration of dormant bandwidth-parts (BWPs) .

FIG. 9 depicts an example timeline for secondary cell (SCell) activation based on a temporary reference signal (RS) .

FIG. 10 and FIG. 11 depict example timelines for different options for triggering a temporary RS for SCell activation.

FIG. 12A and FIG. 12B depict example configurations of SSB-less carriers.

FIG. 13A and FIG. 13B depict example configurations of SSB-less carriers with and without temporary reference signals (RS) .

FIG. 14 depicts a method for wireless communications.

FIG. 15 depicts a method for wireless communications.

FIG. 16 depicts aspects of an example communications device.

FIG. 17 depicts aspects of an example communications device.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable mediums for random access channel (RACH) procedures in carriers that lack Synchronization Signal Block (SSB) transmissions.

In a random access channel (RACH) procedure, a user equipment (UE) sends a first message referred to as a physical RACH (PRACH) preamble to a network entity (e.g., a base station) to synchronize a cell. A UE typically selects a cell to perform a RACH procedure with based on SSB transmissions from different cells. Based on SSB detection, the UE may determine various parameters for the RACH procedure, such as time and frequency resources for a RACH occasion (RO) , spatial transmit filters, and uplink power control parameters.

Carrier aggregation (CA) may be deployed to achieve higher data rates and capacity by combining component carriers with various bandwidths. CA may allow for transmission and reception of data on multiple component carriers from two cell groups: a master cell group (MCG) via a master node and a secondary cell group (SCG) via secondary node. In certain CA deployments, SSBs may not be transmitted in a carrier. For example, to reduce power consumption in a radio access network (RAN) that utilizes CA, one or more carriers may not transmit SSBs. Such carriers may be referred to herein as SSB-less carriers. This lack of SSBs may present a challenge to a UE for determining parameters for a RACH procedure.

Aspects of the present disclosure, however, provide techniques for determining parameters to perform a RACH procedure in an SSB-less carrier. For example, a UE may detect an SSB in an first carrier and determine whether a second carrier is configured to transmit SSBs. The UE may then perform a RACH procedure on the second carrier, regardless of whether the second carrier is configured to transmit SSBs, using parameters selected based on the determination.

Utilization of techniques presented herein may provide significant advantages, especially for network power savings. For example, by supporting RACH procedures with an SSB-less carrier, resource utilization may be improved by downlink overhead reduction. Additionally, such techniques may facilitate efficient secondary cell (SCell) activation and de-activation based on actual traffic, decreasing SCell latency. Further, offloading physical RACH (PRACH) transmissions from a primary cell (PCell) to an SSB-less carrier may reduce PRACH collision and PRACH retransmissions, which provides benefits to the network and UE.

Introduction to Wireless Communications Networks

The techniques and methods described herein may be used for various wireless communications networks. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may likewise be applicable to other communications systems and standards not explicitly mentioned herein.

FIG. 1 depicts an example of a wireless communications network 100, in which aspects described herein may be implemented.

Generally, wireless communications network 100 includes various network entities (alternatively, network elements or network nodes) . A network entity is generally a communications device and/or a communications function performed by a communications device (e.g., a user equipment (UE) , a base station (BS) , a component of a BS, a server, etc. ) . For example, various functions of a network as well as various devices associated with and interacting with a network may be considered network entities. Further, wireless communications network 100 includes terrestrial aspects, such as ground-based network entities (e.g., BSs 102) , and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipments.

In the depicted example, wireless communications network 100 includes BSs 102, UEs 104, and one or more core networks, such as an Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190, which interoperate to provide communications services over various communications links, including wired and wireless links.

FIG. 1 depicts various example UEs 104, which may more generally include: a cellular phone, smart phone, session initiation protocol (SIP) phone, laptop, personal digital assistant (PDA) , satellite radio, global positioning system, multimedia device, video device, digital audio player, camera, game console, tablet, smart device, wearable device, vehicle, electric meter, gas pump, large or small kitchen appliance, healthcare device, implant, sensor/actuator, display, internet of things (IoT) devices, always on (AON) devices, edge processing devices, or other similar devices. UEs 104 may also be referred to more generally as a mobile device, a wireless device, a wireless communications device, a station, a mobile station, a subscriber station, a mobile subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a remote device, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, and others.

BSs 102 wirelessly communicate with (e.g., transmit signals to or receive signals from) UEs 104 via communications links 120. The communications links 120 between BSs 102 and UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a BS 102 and/or downlink (DL) (also referred to as forward link) transmissions from a BS 102 to a UE 104. The communications links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.

BSs 102 may generally include: a NodeB, enhanced NodeB (eNB) , next generation enhanced NodeB (ng-eNB) , next generation NodeB (gNB or gNodeB) , access point, base transceiver station, radio base station, radio transceiver, transceiver function, transmission reception point, and/or others. Each of BSs 102 may provide communications coverage for a respective geographic coverage area 110, which may sometimes be referred to as a cell, and which may overlap in some cases (e.g., small cell 102’ may have a coverage area 110’ that overlaps the coverage area 110 of a macro cell) . A BS may, for example, provide communications coverage for a macro cell (covering relatively large geographic area) , a pico cell (covering relatively smaller geographic area, such as a sports stadium) , a femto cell (relatively smaller geographic area (e.g., a home) ) , and/or other types of cells.

While BSs 102 are depicted in various aspects as unitary communications devices, BSs 102 may be implemented in various configurations. For example, one or more components of a base station may be disaggregated, including a central unit (CU) , one or more distributed units (DUs) , one or more radio units (RUs) , a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) , or a Non-Real Time (Non-RT) RIC, to name a few examples. In another example, various aspects of a base station may be virtualized. More generally, a base station (e.g., BS 102) may include components that are located at a single physical location or components located at various physical locations. In examples in which a base station includes components that are located at various physical locations, the various components may each perform functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. In some aspects, a base station including components that are located at various physical locations may be referred to as a disaggregated radio access network architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture. FIG. 2 depicts and describes an example disaggregated base station architecture.

Different BSs 102 within wireless communications network 100 may also be configured to support different radio access technologies, such as 3G, 4G, and/or 5G. For example, BSs 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through first backhaul links 132 (e.g., an S1 interface) . BSs 102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN) ) may interface with 5GC 190 through second backhaul links 184. BSs 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over third backhaul links 134 (e.g., X2 interface) , which may be wired or wireless.

Wireless communications network 100 may subdivide the electromagnetic spectrum into various classes, bands, channels, or other features. In some aspects, the subdivision is provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. For example, 3GPP currently defines Frequency Range 1 (FR1) as including 410 MHz –7125 MHz, which is often referred to (interchangeably) as “Sub-6 GHz” . Similarly, 3GPP currently defines Frequency Range 2 (FR2) as including 24, 250 MHz –52, 600 MHz, which is sometimes referred to (interchangeably) as a “millimeter wave” ( “mmW” or “mmWave” ) . A base station configured to communicate using mmWave/near mmWave radio frequency bands (e.g., a mmWave base station such as BS 180) may utilize beamforming (e.g., 182) with a UE (e.g., 104) to improve path loss and range.

The communications links 120 between BSs 102 and, for example, UEs 104, may be through one or more carriers, which may have different bandwidths (e.g., 5, 10, 15, 20, 100, 400, and/or other MHz) , and which may be aggregated in various aspects. Carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL) .

Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g., 180 in FIG. 1) may utilize beamforming 182 with a UE 104 to improve path loss and range. For example, BS 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming. In some cases, BS 180 may transmit a beamformed signal to UE 104 in one or more transmit directions 182’. UE 104 may receive the beamformed signal from the BS 180 in one or more receive directions 182”. UE 104 may also transmit a beamformed signal to the BS 180 in one or more transmit directions 182”. BS 180 may also receive the beamformed signal from UE 104 in one or more receive directions 182’. BS 180 and UE 104 may then perform beam training to determine the best receive and transmit directions for each of BS 180 and UE 104. Notably, the transmit and receive directions for BS 180 may or may not be the same. Similarly, the transmit and receive directions for UE 104 may or may not be the same.

Wireless communications network 100 further includes a Wi-Fi AP 150 in communication with Wi-Fi stations (STAs) 152 via communications links 154 in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum.

Certain UEs 104 may communicate with each other using device-to-device (D2D) communications link 158. D2D communications link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , a physical sidelink control channel (PSCCH) , and/or a physical sidelink feedback channel (PSFCH) .

EPC 160 may include various functional components, including: a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and/or a Packet Data Network (PDN) Gateway 172, such as in the depicted example. MME 162 may be in communication with a Home Subscriber Server (HSS) 174. MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation as well as other functions. PDN Gateway 172 and the BM-SC 170 are connected to IP Services 176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a Packet Switched (PS) streaming service, and/or other IP services.

BM-SC 170 may provide functions for MBMS user service provisioning and delivery. BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and/or may be used to schedule MBMS transmissions. MBMS Gateway 168 may be used to distribute MBMS traffic to the BSs 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and/or may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

5GC 190 may include various functional components, including: an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. AMF 192 may be in communication with Unified Data Management (UDM) 196.

AMF 192 is a control node that processes signaling between UEs 104 and 5GC 190. AMF 192 provides, for example, quality of service (QoS) flow and session management.

Internet protocol (IP) packets are transferred through UPF 195, which is connected to the IP Services 197, and which provides UE IP address allocation as well as other functions for 5GC 190. IP Services 197 may include, for example, the Internet, an intranet, an IMS, a PS streaming service, and/or other IP services.

In various aspects, a network entity or network node can be implemented as an aggregated base station, as a disaggregated base station, a component of a base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, to name a few examples.

FIG. 2 depicts an example disaggregated base station 200 architecture. The disaggregated base station 200 architecture may include one or more central units (CUs) 210 that can communicate directly with a core network 220 via a backhaul link, or indirectly with the core network 220 through one or more disaggregated base station units (such as a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC) 225 via an E2 link, or a Non-Real Time (Non-RT) RIC 215 associated with a Service Management and Orchestration (SMO) Framework 205, or both) . A CU 210 may communicate with one or more distributed units (DUs) 230 via respective midhaul links, such as an F1 interface. The DUs 230 may communicate with one or more radio units (RUs) 240 via respective fronthaul links. The RUs 240 may communicate with respective UEs 104 via one or more radio frequency (RF) access links. In some implementations, the UE 104 may be simultaneously served by multiple RUs 240.

Each of the units, e.g., the CUs 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communications interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally or alternatively, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver) , configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.

In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC) , packet data convergence protocol (PDCP) , service data adaptation protocol (SDAP) , or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (e.g., Central Unit –User Plane (CU-UP) ) , control plane functionality (e.g., Central Unit –Control Plane (CU-CP) ) , or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.

The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3 ^rd Generation Partnership Project (3GPP) . In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.

Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like) , or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU (s) 240 can be implemented to handle over the air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communications with the RU (s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU (s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface) . For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface) . Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a Non-RT RIC 215 configured to support functionality of the SMO Framework 205.

The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.

In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the Non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies) .

FIG. 3 depicts aspects of an example BS 102 and a UE 104.

Generally, BS 102 includes various processors (e.g., 320, 330, 338, and 340) , antennas 334a-t (collectively 334) , transceivers 332a-t (collectively 332) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source 312) and wireless reception of data (e.g., data sink 339) . For example, BS 102 may send and receive data between BS 102 and UE 104. BS 102 includes controller/processor 340, which may be configured to implement various functions described herein related to wireless communications.

Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380) , antennas 352a-r (collectively 352) , transceivers 354a-r (collectively 354) , which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., retrieved from data source 362) and wireless reception of data (e.g., provided to data sink 360) . UE 104 includes controller/processor 380, which may be configured to implement various functions described herein related to wireless communications.

In regards to an example downlink transmission, BS 102 includes a transmit processor 320 that may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical HARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , and/or others. The data may be for the physical downlink shared channel (PDSCH) , in some examples.

Transmit processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor 320 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , PBCH demodulation reference signal (DMRS) , and channel state information reference signal (CSI-RS) .

Transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t may process a respective output symbol stream to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers 332a-332t may be transmitted via the antennas 334a-334t, respectively.

In order to receive the downlink transmission, UE 104 includes antennas 352a-352r that may receive the downlink signals from the BS 102 and may provide received signals to the demodulators (DEMODs) in transceivers 354a-354r, respectively. Each demodulator in transceivers 354a-354r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples to obtain received symbols.

MIMO detector 356 may obtain received symbols from all the demodulators in transceivers 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to a data sink 360, and provide decoded control information to a controller/processor 380.

In regards to an example uplink transmission, UE 104 further includes a transmit processor 364 that may receive and process data (e.g., for the PUSCH) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH) ) from the controller/processor 380. Transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the modulators in transceivers 354a-354r (e.g., for SC-FDM) , and transmitted to BS 102.

At BS 102, the uplink signals from UE 104 may be received by antennas 334a-t, processed by the demodulators in transceivers 332a-332t, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by UE 104. Receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.

Memories

342 and 382 may store data and program codes for BS 102 and UE 104, respectively.

Scheduler 344 may schedule UEs for data transmission on the downlink and/or uplink.

In various aspects, BS 102 may be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 312, scheduler 344, memory 342, transmit processor 320, controller/processor 340, TX MIMO processor 330, transceivers 332a-t, antenna 334a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 334a-t, transceivers 332a-t, RX MIMO detector 336, controller/processor 340, receive processor 338, scheduler 344, memory 342, and/or other aspects described herein.

In various aspects, UE 104 may likewise be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 362, memory 382, transmit processor 364, controller/processor 380, TX MIMO processor 366, transceivers 354a-t, antenna 352a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 352a-t, transceivers 354a-t, RX MIMO detector 356, controller/processor 380, receive processor 358, memory 382, and/or other aspects described herein.

In some aspects, a processor may be configured to perform various operations, such as those associated with the methods described herein, and transmit (output) to or receive (obtain) data from another interface that is configured to transmit or receive, respectively, the data.

FIGS. 4A, 4B, 4C, and 4D depict aspects of data structures for a wireless communications network, such as wireless communications network 100 of FIG. 1.

In particular, FIG. 4A is a diagram 400 illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure, FIG. 4B is a diagram 430 illustrating an example of DL channels within a 5G subframe, FIG. 4C is a diagram 450 illustrating an example of a second subframe within a 5G frame structure, and FIG. 4D is a diagram 480 illustrating an example of UL channels within a 5G subframe.

Wireless communications systems may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. Such systems may also support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth (e.g., as depicted in FIGS. 4B and 4D) into multiple orthogonal subcarriers. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and/or in the time domain with SC-FDM.

A wireless communications frame structure may be frequency division duplex (FDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either DL or UL. Wireless communications frame structures may also be time division duplex (TDD) , in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.

In FIG. 4A and 4C, the wireless communications frame structure is TDD where D is DL, U is UL, and X is flexible for use between DL/UL. UEs may be configured with a slot format through a received slot format indicator (SFI) (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) . In the depicted examples, a 10 ms frame is divided into 10 equally sized 1 ms subframes. Each subframe may include one or more time slots. In some examples, each slot may include 7 or 14 symbols, depending on the slot format. Subframes may also include mini-slots, which generally have fewer symbols than an entire slot. Other wireless communications technologies may have a different frame structure and/or different channels.

In certain aspects, the number of slots within a subframe is based on a slot configuration and a numerology. For example, for slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2 ^μ × 15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGS. 4A, 4B, 4C, and 4D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

As depicted in FIGS. 4A, 4B, 4C, and 4D, a resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs) ) that extends, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs) . The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry reference (pilot) signals (RS) for a UE (e.g., UE 104 of FIGS. 1 and 3) . The RS may include demodulation RS (DMRS) and/or channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and/or phase tracking RS (PT-RS) .

FIG. 4B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) , each CCE including, for example, nine RE groups (REGs) , each REG including, for example, four consecutive REs in an OFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., 104 of FIGS. 1 and 3) to determine subframe/symbol timing and a physical layer identity.

A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI) . Based on the PCI, the UE can determine the locations of the aforementioned DMRS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and/or paging messages.

As illustrated in FIG. 4C, some of the REs carry DMRS (indicated as R for one particular configuration, but other DMRS configurations are possible) for channel estimation at the base station. The UE may transmit DMRS for the PUCCH and DMRS for the PUSCH. The PUSCH DMRS may be transmitted, for example, in the first one or two symbols of the PUSCH. The PUCCH DMRS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. UE 104 may transmit sounding reference signals (SRS) . The SRS may be transmitted, for example, in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 4D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR) , a power headroom report (PHR) , and/or UCI.

Example RACH Procedures

A random-access channel (RACH) is so named because it refers to a wireless channel (medium) that may be shared by multiple UEs and used by the UEs to (randomly) access the network for communications. For example, the RACH may be used for call setup and to access the network for data transmissions. In some cases, RACH may be used for initial access to a network when the UE switches from a radio resource control (RRC) connected idle mode to active mode, or when handing over in RRC connected mode. Moreover, RACH may be used for downlink (DL) and/or uplink (UL) data arrival when the UE is in RRC idle or RRC inactive modes, and when reestablishing a connection with the network.

FIG. 5 is a timing (or "call-flow" ) diagram 500 illustrating an example four-step RACH procedure, in accordance with certain aspects of the present disclosure. A first message (MSG1) may be sent from the UE to a network entity (e.g., a BS such as a gNB) on the physical random access channel (PRACH) . In this case, MSG1 may only include a RACH preamble. The network entity may respond with a random access response (RAR) message (MSG2) which may include the identifier (ID) of the RACH preamble, a timing advance (TA) , an uplink grant, cell radio network temporary identifier (C-RNTI) , and a back off indicator. MSG2 may include a PDCCH communication including control information for a following communication on the PDSCH, as illustrated. In response to MSG2, MSG3 is transmitted from the UE to the network entity on the PUSCH. MSG3 may include one or more of a RRC connection request, a tracking area update request, a system information request, a positioning fix or positioning signal request, or a scheduling request. The network entity then responds with MSG 4 which may include a contention resolution message.

In some cases, to speed access, a two-step RACH procedure may be supported. As the name implies, the two-step RACH procedure may effectively "collapse" the four messages of the four-step RACH procedure into two messages.

FIG. 6 is a call flow diagram 600 illustrating an example two-step RACH procedure, in accordance with certain aspects of the present disclosure. As illustrated, the UE may be configured with parameters, via system information (SI) and/or RRC signaling, for SSB monitoring and RACH procedure.

For the 2-step RACH procedure, a first enhanced message (msgA) may be sent from the UE to the network entity. In certain aspects, msgA includes some or all the information from MSG1 and MSG3 from the four-step RACH procedure, effectively combining MSG1 and MSG3. For example, msgA may include MSG1 and MSG3 multiplexed together such as using one of time-division multiplexing or frequency-division multiplexing. In certain aspects, msgA includes a RACH preamble for random access and a payload. The msgA payload, for example, may include the UE-ID and other signaling information (e.g., buffer status report (BSR) ) or scheduling request (SR) . BS 102 may respond with a random access response (RAR) message (msgB) which may effectively combine MSG2 and MSG4 described above. For example, msgB may include the ID of the RACH preamble, a timing advance (TA) , a back off indicator, a contention resolution message, UL/DL grant, and transmit power control (TPC) commands.

In a two-step RACH procedure, the msgA may include a RACH preamble and a payload. In some cases, the RACH preamble and payload may be sent in a msgA transmission occasion.

The random access message (msgA) transmission occasion generally includes a msgA preamble occasion (for transmitting a preamble signal) and a msgA payload occasion for transmitting a PUSCH. The msgA preamble transmission generally involves:

(1) selection of a preamble sequence; and

(2) selection of a preamble occasion in time/frequency domain (for transmitting the selected preamble sequence) .

The msgA payload transmission generally involves:

(1) construction of the random access message payload (DMRS/PUSCH) ; and

(2) selection of one or multiple PUSCH resource units (PRUs) in time/frequency domain to transmit this message (payload) .

In some cases, a UE monitors SSB transmissions which are sent (by a gNB using different beams) and are associated with a finite set of time/frequency resources defining RACH occasions (ROs) and PRUs. Upon detecting an SSB, the UE may select an RO and one or more PRUs associated with that SSB for a MSG1/msgA transmission.

There are several benefits to a two-step RACH procedure, such as speed of access and the ability to send a relatively small amount of data without the overhead of a full four-step RACH procedure to establish a connection (when the four-step RACH messages may be larger than the payload) .

The two-step RACH procedure can operate in any RRC state and any supported cell size. Networks that uses two-step RACH procedures can typically support contention-based random access (CBRA) transmission of messages (e.g., msgA) within a finite range of payload sizes and with a finite number of MCS levels.

After a UE has selected an SSB (beam) , for that SS block there is a predefined one or more ROs with certain time and frequency offset and direction (e.g., specific to the selected SSB) .

This SSB to RO association is used for the gNB to know what beam the UE has acquired/is using (generally referred to as beam establishment) . One SSB may be associated with one or more ROs or more than one SSB may be associated with one RO. Association is typically performed in the frequency domain first, then in the time domain within a RACH slot, then in the time domain across RACH slots (e.g., beginning with lower SSB indexes) . An association period is typically defined as a minimum number of RACH configuration periods, such that all (configured) SSB beams are mapped into ROs.

Overview of Network Power Consumption

One of the significant costs for operating a cellular network is due to energy consumption (e.g., 23%total expense) . Most of that cost comes from the radio access network (RAN) (e.g., around 50%in 5G) . Therefore, network energy savings features are important to limit overall costs and to promote adoption and expansion of cellular networks. This may be particularly important in more complex systems that tend to be power hungry, such as massive multiple input multiple output (MIMO) systems that utilize large arrays of antennas.

In some cases, a framework may be adapted for power consumption modelling and evaluation on the network (e.g., base station) side. This may include modeling and evaluating relative energy consumption for DL and UL, for example, considering factors such as power amplifier (PA) efficiency, a number of transmitter receiver units (TxRUs) , base station load, sleep states and the associated transition times, as well as various reference parameters/configurations.

The evaluation methodology may target evaluating system-level network energy consumption and energy savings gains, as well as assessing/balancing impact to network and user performance. (e.g., spectral efficiency, capacity, latency, handover performance, call drop rate, initial access performance, SLA assurance related key performance indicators (KPIs) ) , energy efficiency, and UE power consumption and complexity. The evaluation methodology may consider a variety of different KPIs and may reuse existing KPIs and new KPIs may be developed, as appropriate.

In some cases, techniques may be identified on the gNB and UE side to improve network energy savings in terms of both BS transmission and reception. Such techniques may include techniques designed to achieve more efficient operation dynamically and/or semi-statically and finer granularity adaptation of transmissions and/or receptions in one or more of network energy saving techniques in time, frequency, spatial, and power domains, with potential support/feedback from UE, and potential UE assistance information, with possible information exchange/coordination over network interfaces.

Power consumption in various network loading scenarios may be considered, such as idle/empty and low/medium load scenarios, and different loads among carriers and neighbor cells may be allowed. The following example scenarios including single-carrier and multi-carrier deployments may be considered: urban micro in FR1, including TDD massive MIMO, FR2 beam-based scenarios, Urban/Rural macro in FR1 with/without DSS, and EN-DC/NR-DC macro with FDD PCell and TDD/Massive MIMO on higher FR1/FR2 frequency. Energy savings techniques may be designed such that so called legacy UEs are still able to continue accessing a network implementing the network energy savings techniques (e.g., with the possible exception of techniques developed specifically for a new deployment where a network did not previously exist, a so-called greenfield deployment) .

Overview of Inter-Band CA with SSB-less Carriers

As noted above, in some case, inter-band carrier aggregation (CA) with synchronization signal block (SSB) -less carriers may be one part of a network energy savings strategy. The potential energy savings may be appreciated when considering the percentage of active symbols in a radio frame that may be occupied by SSB transmissions. As illustrated in the table shown in FIG. 7, SSB transmissions may occupy from 6.5%(FR1) to 14.8% (for FR2) of active symbols.

When utilizing SSB-less carriers, SSBs in one carrier may provide timing and frequency (T/F) synchronization for an SSB-less carrier. In some cases, it may be assumed that no legacy UEs operate on SSB-less carriers (e.g., greenfield deployments) . In some cases, SSB-less carriers may involve FR1 fragmented bands in which the bands are neighboring (e.g., 700MHz/800MHz/900MHz, 1.8GHz/2.1GHz, 1.9GHz/2GHz/2.3GHz) .

Inter-band CA with SSB-less carriers may have several benefits. For example, SSB-less carriers may help improve Secondary cell (Scell) activation latency, facilitate efficient Scell activation/de-activation according to the actual traffic (which may result in network power savings) , and may improve resource utilization by downlink overhead reduction.

A RACH procedure in SSB-less carriers may allow for offloading of PRACH transmission from a Pcell to an SSB-less carrier. This may help reduce PRACH collision, which is beneficial both to the UE and to the network by reducing PRACH retransmission.

Overview of SCell activation

A significant portion of UE power consumption may also be used for monitoring control channels, such as PDCCHs. When SCell dormancy techniques are implemented, a network may dynamically enable or disable PDCCH monitoring on a Secondary Cell (SCell) . For example, an SCell may be transitioned to a dormant state when it has little or no traffic and transitioned back to a non-dormant state when it has a higher traffic load.

FIG. 8 illustrates how the use of a dormant BWP and may help reduce latency for SCell activation. As illustrated, the time to switch from a dormant BWP to an active BWP (via a dormancy DCI) may be significantly less than the latency when switching via MAC-CE based SCell activation.

In some cases, fast SCell activation may be enabled by triggering “temporary RS”at earlier timing than SSB. Temporary RS (Temp RS) may be applicable to both intra-band CA and inter-band CA. Temporary RS may be, for example, an aperiodic tracking reference signal (A-TRS) that is used for AGC and T/F tracking. In some cases, periodic TRS (P-TRS) in the to-be-activated Scell may be the quasi co-location (QCL) source for the temporary RS.

SCell activation with a Temp RS may be understood with reference to the example timeline 900 of FIG. 9. As shown, after a UE receives an activation command (sent in the PCell) to activate an SCell, the SCell is not considered active until 3ms after the UE sends an acknowledgment (ACK) . In addition, there is additional delay to allow the UE to monitor for reference signals that the UE will use to adjust its time and frequency tracking before sending a channel state information (CSI) report. The sum of this delay is labeled in FIG. 9 and referred to as T _{axtivation time}.

As noted above, if the UE were to rely on SSBs for initial CSI measurements in the SCell, due to a relatively long period between SSBs, this delay may be substantial. The use of Temp RS may substantially reduce SCell activation time by allowing the UE to send a valid CSI report much sooner than if it had to wait on a subsequent SSB.

According to certain aspects of the present disclosure, a UE may be RRC configured for temporary RS utilizing similar RRC signaling for aperiodic CSI-RS and temporary RS, with trigger states defined using a “per-carrier” structure. Temp RS may be triggered (and details of the temp RS indicated to the UE) by indicating one of the trigger states.

There are various options for triggering a temporary RS after SCell activation. For example, as illustrated in FIG. 10, a physical downlink shared channel (PDSCH) may carry a MAC CE that activates the Scell and also triggers the Temp RS. In the illustrated example, the UE receives and acknowledges (via a hybrid automatic repeat request acknowledgment HARQ-ACK) the MAC CE in the PCell. 3ms after the HARQ-ACK, the SCell may be considered activated and a Temp RS may be sent.

In this example, the MAC CE may indicate (e.g., via a bit field/codepoint) at least one trigger state, from a per-carrier aperiodic state list for the SCell carrier. The UE may then monitor for the Temp RS on the SCell based on an RS configuration associated with the at least one trigger state indicated in the MAC CE.

As illustrated in FIG. 11, according to another option, a MAC CE may trigger SCell activation, while a DCI may trigger the Temp RS. In this case, the DCI may indicate (e.g., via a bit field/codepoint) at least one trigger state, from the per-carrier aperiodic state list for the SCell carrier. The UE may then monitor for the Temp RS on the SCell based on an RS configuration associated with the at least one trigger state indicated in the DCI.

As described herein, dormant BWP may allow for fast SCell activation. In some cases, (NR Rel. 17) Scell activation with assistance of Temp RS may reduce Scell activation latency (relative to Rel. 15) . In such cases, the activation latency may be a function of Temp RS availability time instead of SSB availability time.

Aspects Related to Random Access Channel (RACH) in inter-band Carrier Aggregation (CA) with Synchronization Signal Block (SSB) -less carrier.

In some cases, inter-band CA with SSB-less carriers may improve SCell activation, by avoiding temporary RS for a known SCell. The latency could be just the SCell activation MAC-CE procedure latency (3ms) . Inter-band CA with SSB-less carriers may also reduce broadcast signaling overhead for the known cells. As described with reference to FIG. 7, for a Sub-6, 30kHz, 8 SSBs, TDD with a slot configuration 7D: 1S: 2U and the S slot (10D: 2F: 2U) , a 20ms SSB may have a 6.5%overhead in time. A 160ms SSB may have a 0.8%overhead in time.

As noted above, performing a RACH procedure in SSB-less carriers may allow for offloading of PRACH transmission from a Pcell to an SSB-less carrier. This may help reduce PRACH collision, which is beneficial both to the UE and to the network by reducing PRACH retransmission.

A RACH procedure can be performed in a normal uplink NUL (Pcell) and supplemental uplink (SUL) cell if configured. When RACH is performed on SUL, Msg1/Msg3 (4-step) or MsgA (2-step) may be transmitted on SUL, while Msg2/Msg4 (4-step) or MsgB (2-step) may be transmitted on NUL. This may provide RACH coverage when using SUL carrier.

As noted above, a lack of SSBs in a carrier may present a challenge to a UE for determining parameters for a RACH procedure. Aspects of the present disclosure, however, provide techniques for determining parameters to perform a RACH procedure in an SSB-less carrier. For example, a UE may detect an SSB in an first carrier and determine whether a second carrier is configured to transmit SSBs. The UE may then select one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure, based on the determination, and perform the RACH procedure on the second carrier using the selected parameters.

As illustrated in FIG. 12A and FIG. 12B, the first carrier may be an anchor carrier that is used for timing and frequency (T/F) synchronization and the second carrier may be a non-anchor carrier. The example in FIG. 12A assumes a time division duplexed (TDD) configuration, where each non-anchor is SSB-less and lacks Temp RS. The example in FIG. 12B assumes a frequency division duplexed (FDD) configuration, such that one non-anchor carrier (Carrier 1) may be DL and the other non-anchor carrier (Carrier 2) may be UL.

The UE may perform a RACH procedure on the non-anchor carrier. As illustrated, the UE may treat the anchor carrier (w/SSB and SI transmissions) and one or more non-anchor carriers (SSB-less) as a single cell. The (anchor and non-anchor) carriers may be in the same band or in different bands.

Aspects of the present disclosure allow the UE to perform a RACH procedure on a non-anchor carrier, which may help reduce collisions for physical random access channel (PRACH) transmissions. In some cases, potentially all RACH messages could be sent on a non-anchor carrier.

Using the techniques presented herein, the UE may determine one or more parameters for the RACH procedure. The parameters may allow for carrier selection, time and frequency resources for RACH occasion (RO) determination, spatial transmit filter, quasi colocation (QCL) source, and UL power control.

The techniques presented herein may be used for a UE configured to transmit physical random access channel (PRACH) /physical uplink shared channel (PUSCH) on non-anchor carrier supporting time division duplexing (TDD) operation and the non-anchor carrier does not transmit synchronization signal block (SSB) (i.e., SSB-less carrier) , as in the examples illustrated in FIG. 13A and FIG. 13B.

For example, the UE may use an SSB in the (anchor) carrier providing the T/F synchronization for the non-anchor carrier, in order to determine the parameters for PRACH/PUSCH transmission. For example, from the SSB, the UE may determine the RO resource (e.g., for PRACH only) , spatial transmit filter, and power control (e.g., path loss measurement) . If the non-anchor carrier transmits temporary RS, as in the example shown in FIG. 13B, the UE may determine the spatial transmit filter and/or power control parameters based on the temporary RS. In this context, the PUSCH transmission may be a Msg3 PUSCH (for a 4-step RACH) or a MsgA PUSCH (for a 2-step RACH) .

In some cases, when a UE is configured to transmit PRACH/PUSCH on a non-anchor carrier supporting TDD operation and the non-anchor carrier does transmit SSB, the UE may use one of various options to determine the parameters for PRACH/PUSCH transmission (in the non-anchor carrier) .

According to a first option, the UE may use the SSB in the anchor carrier to determine the parameters for PRACH/PUSCH transmission. According to a second option, the UE may use an SSB in the non-anchor carrier to determine the parameters for PRACH/PUSCH transmission. In some cases, the NW may configure the UE with which option to use, for example, via system information (SI) .

In some cases, a UE may configured to receive PDCCH/PDSCH on a non-anchor carrier and the non-anchor carrier does not transmit SSB (i.e., is an SSB-less carrier) . In such cases, the UE may use an SSB in the carrier providing the T/F synchronization for the non-anchor carrier as a QCL source for PDCCH/PDSCH reception.

In some cases, a UE may be configured to receive PDCCH/PDSCH on a non-anchor carrier and the non-anchor carrier may transmit SSB. In some cases, the UE may use the SSB in the anchor carrier as the QCL source for PDCCH/PDSCH reception. In other cases, the UE may use an SSB in the non-anchor carrier as the QCL source for PDCCH/PDSCH reception. In some cases, the NW may configure the UE with which option to use, for example, via SI or via DCI for PDSCH reception.

Example Operations of a User Equipment

FIG. 14 shows an example of a method 1400 for wireless communications by a UE, such as UE 104 of FIGS. 1 and 3.

Method 1400 begins at step 1405 with detecting a SSB in an first carrier. In some cases, the operations of this step refer to, or may be performed by, circuitry for detecting and/or code for detecting as described with reference to FIG. 16.

Method 1400 then proceeds to step 1410 with determining whether a second carrier is configured to transmit SSBs. In some cases, the operations of this step refer to, or may be performed by, circuitry for determining and/or code for determining as described with reference to FIG. 16.

Method 1400 then proceeds to step 1415 with selecting, based on the determination, one or more parameters for transmission or reception of one or more messages of a RACH procedure. In some cases, the operations of this step refer to, or may be performed by, circuitry for selecting and/or code for selecting as described with reference to FIG. 16.

Method 1400 then proceeds to step 1420 with performing the RACH procedure on the second carrier using the selected parameters. In some cases, the operations of this step refer to, or may be performed by, circuitry for performing and/or code for performing as described with reference to FIG. 16.

In some aspects, the one or more parameters comprise a RO resource, a spatial transmit filter, and a power control parameter.

In some aspects, the second carrier supports TDD.

In some aspects, the one or more messages comprise at least one of a PRACH preamble or PUSCH.

In some aspects, the second carrier is not configured to transmit SSBs; and the selecting comprises selecting the one or more parameters based on an SSB transmitted in the first carrier.

In some aspects, the one or more parameters comprise a RO resource; the second carrier is configured to transmit a temporary RS.

In some aspects, the method 1400 further includes determining at least one of a spatial transmit filter or power control parameter, based on the temporary RS. In some cases, the operations of this step refer to, or may be performed by, circuitry for determining and/or code for determining as described with reference to FIG. 16.

In some aspects, the second carrier is configured to transmit SSBs; and the selecting comprises selecting the one or more parameters based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.

In some aspects, the method 1400 further includes receiving signaling indicating whether the UE is to select the one or more parameters based on the SSB transmitted in the second carrier or the SSB transmitted in the first carrier. In some cases, the operations of this step refer to, or may be performed by, circuitry for receiving and/or code for receiving as described with reference to FIG. 16.

In some aspects, the one or more messages comprise at least one of a PDCCH or a PDSCH; and the one or more parameters comprises a QCL source for reception of the PDCCH or PDSCH.

In some aspects, the second carrier is not configured to transmit SSBs; and the selecting comprises selecting an SSB transmitted in the first carrier as the QCL source for reception of the PDCCH or PDSCH.

In some aspects, the second carrier is configured to transmit SSBs; and the selecting comprises selecting, as the QCL source for reception of the PDCCH or PDSCH, an SSB transmitted in the first carrier or an SSB transmitted in the second carrier.

In some aspects, the method 1400 further includes receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier. In some cases, the operations of this step refer to, or may be performed by, circuitry for receiving and/or code for receiving as described with reference to FIG. 16.

In one aspect, method 1400, or any aspect related to it, may be performed by an apparatus, such as communications device 1600 of FIG. 16, which includes various components operable, configured, or adapted to perform the method 1400. Communications device 1600 is described below in further detail.

Note that FIG. 14 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Operations of a Network Entity

FIG. 15 shows an example of a method 1500 for wireless communications by a network entity, such as BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

Method 1500 begins at step 1505 with transmitting information indicating a first carrier is configured for SSB transmissions. In some cases, the operations of this step refer to, or may be performed by, circuitry for transmitting and/or code for transmitting as described with reference to FIG. 17.

Method 1500 then proceeds to step 1510 with determining, based on whether a second carrier is configured to transmit SSBs, one or more parameters for transmission or reception of one or more messages of a RACH procedure. In some cases, the operations of this step refer to, or may be performed by, circuitry for determining and/or code for determining as described with reference to FIG. 17.

Method 1500 then proceeds to step 1515 with participating in the RACH procedure with a UE on the second carrier using the parameters. In some cases, the operations of this step refer to, or may be performed by, circuitry for participating and/or code for participating as described with reference to FIG. 17.

In some aspects, the second carrier supports TDD.

In some aspects, the second carrier is not configured to transmit SSBs; and the one or more parameters are determined based on an SSB transmitted in the first carrier.

In some aspects, the second carrier is configured to transmit SSBs; and the one or more parameters are determined based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.

In some aspects, the method 1500 further includes transmitting signaling indicating whether the UE is to select one or more parameters for the RACH procedure based on the SSB transmitted in the second carrier or the SSB transmitted in the first carrier. In some cases, the operations of this step refer to, or may be performed by, circuitry for transmitting and/or code for transmitting as described with reference to FIG. 17.

In some aspects, the method 1500 further includes receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier. In some cases, the operations of this step refer to, or may be performed by, circuitry for receiving and/or code for receiving as described with reference to FIG. 17.

In one aspect, method 1500, or any aspect related to it, may be performed by an apparatus, such as communications device 1700 of FIG. 17, which includes various components operable, configured, or adapted to perform the method 1500. Communications device 1700 is described below in further detail.

Note that FIG. 15 is just one example of a method, and other methods including fewer, additional, or alternative steps are possible consistent with this disclosure.

Example Communications Devices

FIG. 16 depicts aspects of an example communications device 1600. In some aspects, communications device 1600 is a user equipment, such as UE 104 described above with respect to FIGS. 1 and 3.

The communications device 1600 includes a processing system 1605 coupled to the transceiver 1675 (e.g., a transmitter and/or a receiver) . The transceiver 1675 is configured to transmit and receive signals for the communications device 1600 via the antenna 1680, such as the various signals as described herein. The processing system 1605 may be configured to perform processing functions for the communications device 1600, including processing signals received and/or to be transmitted by the communications device 1600.

The processing system 1605 includes one or more processors 1610. In various aspects, the one or more processors 1610 may be representative of one or more of receive processor 358, transmit processor 364, TX MIMO processor 366, and/or controller/processor 380, as described with respect to FIG. 3. The one or more processors 1610 are coupled to a computer-readable medium/memory 1640 via a bus 1670. In certain aspects, the computer-readable medium/memory 1640 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1610, cause the one or more processors 1610 to perform the method 1400 described with respect to FIG. 14, or any aspect related to it. Note that reference to a processor performing a function of communications device 1600 may include one or more processors 1610 performing that function of communications device 1600.

In the depicted example, computer-readable medium/memory 1640 stores code (e.g., executable instructions) , such as code for detecting 1645, code for determining 1650, code for selecting 1655, code for performing 1660, and code for receiving 1665. Processing of the code for detecting 1645, code for determining 1650, code for selecting 1655, code for performing 1660, and code for receiving 1665 may cause the communications device 1600 to perform the method 1400 described with respect to FIG. 14, or any aspect related to it.

The one or more processors 1610 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1640, including circuitry such as circuitry for detecting 1615, circuitry for determining 1620, circuitry for selecting 1625, circuitry for performing 1630, and circuitry for receiving 1635. Processing with circuitry for detecting 1615, circuitry for determining 1620, circuitry for selecting 1625, circuitry for performing 1630, and circuitry for receiving 1635 may cause the communications device 1600 to perform the method 1400 described with respect to FIG. 14, or any aspect related to it.

Various components of the communications device 1600 may provide means for performing the method 1400 described with respect to FIG. 14, or any aspect related to it. For example, means for transmitting, sending or outputting for transmission may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1675 and the antenna 1680 of the communications device 1600 in FIG. 16. Means for receiving or obtaining may include transceivers 354 and/or antenna (s) 352 of the UE 104 illustrated in FIG. 3 and/or the transceiver 1675 and the antenna 1680 of the communications device 1600 in FIG. 16.

FIG. 17 depicts aspects of an example communications device 1700. In some aspects, communications device 1700 is a network entity, such as BS 102 of FIGS. 1 and 3, or a disaggregated base station as discussed with respect to FIG. 2.

The communications device 1700 includes a processing system 1705 coupled to the transceiver 1765 (e.g., a transmitter and/or a receiver) and/or a network interface 1775. The transceiver 1765 is configured to transmit and receive signals for the communications device 1700 via the antenna 1770, such as the various signals as described herein. The network interface 1775 is configured to obtain and send signals for the communications device 1700 via communication link (s) , such as a backhaul link, midhaul link, and/or fronthaul link as described herein, such as with respect to FIG. 2. The processing system 1705 may be configured to perform processing functions for the communications device 1700, including processing signals received and/or to be transmitted by the communications device 1700.

The processing system 1705 includes one or more processors 1710. In various aspects, one or more processors 1710 may be representative of one or more of receive processor 338, transmit processor 320, TX MIMO processor 330, and/or controller/processor 340, as described with respect to FIG. 3. The one or more processors 1710 are coupled to a computer-readable medium/memory 1735 via a bus 1760. In certain aspects, the computer-readable medium/memory 1735 is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors 1710, cause the one or more processors 1710 to perform the method 1500 described with respect to FIG. 15, or any aspect related to it. Note that reference to a processor of communications device 1700 performing a function may include one or more processors 1710 of communications device 1700 performing that function.

In the depicted example, the computer-readable medium/memory 1735 stores code (e.g., executable instructions) , such as code for transmitting 1740, code for determining 1745, code for participating 1750, and code for receiving 1755. Processing of the code for transmitting 1740, code for determining 1745, code for participating 1750, and code for receiving 1755 may cause the communications device 1700 to perform the method 1500 described with respect to FIG. 15, or any aspect related to it.

The one or more processors 1710 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1735, including circuitry such as circuitry for transmitting 1715, circuitry for determining 1720, circuitry for participating 1725, and circuitry for receiving 1730. Processing with circuitry for transmitting 1715, circuitry for determining 1720, circuitry for participating 1725, and circuitry for receiving 1730 may cause the communications device 1700 to perform the method 1500 as described with respect to FIG. 15, or any aspect related to it.

Various components of the communications device 1700 may provide means for performing the method 1500 as described with respect to FIG. 15, or any aspect related to it. Means for transmitting, sending or outputting for transmission may include transceivers 332 and/or antenna (s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1765 and the antenna 1770 of the communications device 1700 in FIG. 17. Means for receiving or obtaining may include transceivers 332 and/or antenna (s) 334 of the BS 102 illustrated in FIG. 3 and/or the transceiver 1765 and the antenna 1770 of the communications device 1700 in FIG. 17.

Example Clauses

Implementation examples are described in the following numbered clauses:

Clause 1: A method of wireless communication by a UE, comprising: detecting a SSB in an first carrier; determining whether a second carrier is configured to transmit SSBs; selecting, based on the determination, one or more parameters for transmission or reception of one or more messages of a RACH procedure; and performing the RACH procedure on the second carrier using the selected parameters.

Clause 2: The method of Clause 1, wherein the one or more parameters comprise a RO resource, a spatial transmit filter, and a power control parameter.

Clause 3: The method of any one of

Clauses

1 and 2, wherein the second carrier supports TDD.

Clause 4: The method of any one of Clauses 1-3, wherein the one or more messages comprise at least one of a PRACH preamble or PUSCH.

Clause 5: The method of Clause 4, wherein: the second carrier is not configured to transmit SSBs; and the selecting comprises selecting the one or more parameters based on an SSB transmitted in the first carrier.

Clause 6: The method of Clause 5, wherein: the one or more parameters comprise a RO resource; the second carrier is configured to transmit a temporary RS; and the method further comprises determining at least one of a spatial transmit filter or power control parameter, based on the temporary RS.

Clause 7: The method of Clause 4, wherein: the second carrier is configured to transmit SSBs; and the selecting comprises selecting the one or more parameters based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.

Clause 8: The method of Clause 7, further comprising: receiving signaling indicating whether the UE is to select the one or more parameters based on the SSB transmitted in the second carrier or the S SB transmitted in the first carrier.

Clause 9: The method of any one of Clauses 1-8, wherein: the one or more messages comprise at least one of a PDCCH or a PDSCH; and the one or more parameters comprises a QCL source for reception of the PDCCH or PDSCH.

Clause 10: The method of Clause 9, wherein: the second carrier is not configured to transmit SSBs; and the selecting comprises selecting an SSB transmitted in the first carrier as the QCL source for reception of the PDCCH or PDSCH.

Clause 11: The method of Clause 9, wherein: the second carrier is configured to transmit SSBs; and the selecting comprises selecting, as the QCL source for reception of the PDCCH or PDSCH, an SSB transmitted in the first carrier or an SSB transmitted in the second carrier.

Clause 12: The method of Clause 11, further comprising: receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier.

Clause 13: A method of wireless communication by a network entity, comprising: transmitting information indicating a first carrier is configured for SSB transmissions; determining, based on whether a second carrier is configured to transmit SSBs, one or more parameters for transmission or reception of one or more messages of a RACH procedure; and participating in the RACH procedure with a UE on the second carrier using the parameters.

Clause 14: The method of Clause 13, wherein the one or more parameters comprise a RO resource, a spatial transmit filter, and a power control parameter.

Clause 15: The method of any one of Clauses 13 and 14, wherein the second carrier supports TDD.

Clause 16: The method of any one of Clauses 13-15, wherein the one or more messages comprise at least one of a PRACH preamble or PUSCH.

Clause 17: The method of Clause 16, wherein: the second carrier is not configured to transmit SSBs; and the one or more parameters are determined based on an SSB transmitted in the first carrier.

Clause 18: The method of Clause 16, wherein: the second carrier is configured to transmit SSBs; and the one or more parameters are determined based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.

Clause 19: The method of Clause 18, further comprising: transmitting signaling indicating whether the UE is to select one or more parameters for the RACH procedure based on the SSB transmitted in the second carrier or the SSB transmitted in the first carrier.

Clause 20: The method of any one of Clauses 13-19, wherein: the one or more messages comprise at least one of a PDCCH or a PDSCH; and the one or more parameters comprises a QCL source for reception of the PDCCH or PDSCH.

Clause 21: The method of Clause 20, further comprising: receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier.

Clause 22: An apparatus, comprising: a memory comprising executable instructions; and a processor configured to execute the executable instructions and cause the apparatus to perform a method in accordance with any one of Clauses 1-21.

Clause 23: An apparatus, comprising means for performing a method in accordance with any one of Clauses 1-21.

Clause 24: A non-transitory computer-readable medium comprising executable instructions that, when executed by a processor of an apparatus, cause the apparatus to perform a method in accordance with any one of Clauses 1-21.

Clause 25: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-21.

Additional Considerations

The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various actions may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD) , 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 commercially available 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, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC) , or any other such configuration.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The methods disclosed herein comprise one or more actions for achieving the methods. The method actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor.

The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” . All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

A method of wireless communication by a user equipment (UE) , comprising:

detecting a synchronization signal block (SSB) in a first carrier;

determining whether a second carrier is configured to transmit SSBs;

selecting, based on the determination, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure; and

performing the RACH procedure on the second carrier using the selected parameters.
The method of claim 1, wherein the one or more parameters comprise a RACH occasion (RO) resource, a spatial transmit filter, and a power control parameter.
The method of claim 1, wherein the second carrier supports time division duplexing (TDD) .
The method of claim 1, wherein the one or more messages comprise at least one of a physical RACH (PRACH) preamble or physical uplink shared channel (PUSCH) .
The method of claim 4, wherein:

the second carrier is not configured to transmit SSBs; and

the selecting comprises selecting the one or more parameters based on an SSB transmitted in the first carrier.
The method of claim 5, wherein:

the one or more parameters comprise a RACH occasion (RO) resource;

the second carrier is configured to transmit a temporary reference signal (RS) ; and

the method further comprises determining at least one of a spatial transmit filter or power control parameter, based on the temporary RS.
The method of claim 4, wherein:

the second carrier is configured to transmit SSBs; and

the selecting comprises selecting the one or more parameters based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.
The method of claim 7, further comprising receiving signaling indicating whether the UE is to select the one or more parameters based on the SSB transmitted in the second carrier or the SSB transmitted in the first carrier.
The method of claim 1, wherein:

the one or more messages comprise at least one of a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH) ; and

the one or more parameters comprises a quasi-colocation (QCL) source for reception of the PDCCH or PDSCH.
The method of claim 9, wherein:

the second carrier is not configured to transmit SSBs; and

the selecting comprises selecting an SSB transmitted in the first carrier as the QCL source for reception of the PDCCH or PDSCH.
The method of claim 9, wherein:

the second carrier is configured to transmit SSBs; and

the selecting comprises selecting, as the QCL source for reception of the PDCCH or PDSCH, an SSB transmitted in the first carrier or an SSB transmitted in the second carrier.
The method of claim 11, further comprising receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier.
A method of wireless communication by a network entity, comprising:

transmitting information indicating a first carrier is configured for synchronization signal block (SSB) transmissions;

determining, based on whether a second carrier is configured to transmit SSBs, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure; and

participating in the RACH procedure with a user equipment (UE) on the second carrier using the parameters.
The method of claim 13, wherein the one or more parameters comprise a RACH occasion (RO) resource, a spatial transmit filter, and a power control parameter.
The method of claim 13, wherein the second carrier supports time division duplexing (TDD) .
The method of claim 13, wherein the one or more messages comprise at least one of a physical RACH (PRACH) preamble or physical uplink shared channel (PUSCH) .
The method of claim 16, wherein:

the second carrier is not configured to transmit SSBs; and

the one or more parameters are determined based on an SSB transmitted in the first carrier.
The method of claim 16, wherein:

the second carrier is configured to transmit SSBs; and

the one or more parameters are determined based on an SSB transmitted in the second carrier or an SSB transmitted in the first carrier.
The method of claim 18, further comprising transmitting signaling indicating whether the UE is to select one or more parameters for the RACH procedure based on the SSB transmitted in the second carrier or the SSB transmitted in the first carrier.
The method of claim 13, wherein:

the one or more messages comprise at least one of a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH) ; and

the one or more parameters comprises a quasi-colocation (QCL) source for reception of the PDCCH or PDSCH.
The method of claim 20, further comprising receiving signaling indicating whether the UE is to select, as the QCL source for reception of the PDCCH or PDSCH, the SSB transmitted in the first carrier or the SSB transmitted in the second carrier.
An apparatus for wireless communications by a user equipment (UE) , comprising:

a memory comprising executable instructions; and

one or more processors configured to execute the executable instructions and cause the reader device to:

detect a synchronization signal block (SSB) in a first carrier;

determine whether a second carrier is configured to transmit SSBs;

select, based on the determination, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure; and

perform the RACH procedure on the second carrier using the selected parameters.
An apparatus for wireless communications by a network entity, comprising:

a memory comprising executable instructions; and

one or more processors configured to execute the executable instructions and cause the reader device to:

transmit information indicating a first carrier is configured for synchronization signal block (SSB) transmissions;

determine, based on whether a second carrier is configured to transmit SSBs, one or more parameters for transmission or reception of one or more messages of a random access channel (RACH) procedure; and

participate in the RACH procedure with a user equipment (UE) on the second carrier using the parameters.