On flexible search spaces for random access response for efficient resourcing

Abstract

A method includes receiving, by a user equipment (UE) from a network node, a Random Access Channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam; receiving, by the UE from the network node, an indication of location information for each beam; and selecting, by the UE, a specific beam based on the location information.

Description

ON FLEXIBLE SEARCH SPACES FOR RANDOM ACCESS RESPONSE FOR EFFICIENT RESOURCING CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The following applications are related: U.S. Patent Application having attorney docket no. 336242-US-PSP (44665-588); and U.S. Patent Application U.S. Patent Application having attorney docket no. 336298-US-PSP (44665-589).FIELD

[0002] Various example embodiments relate generally to wireless networking and, more particularly, to configurations for reducing resources required to perform Random Access (RA).BACKGROUND

[0003] Wireless networking provides significant advantages for user mobility. A user’s ability to remain connected while on the move provides advantages not only for the user, but also provides greater efficiency and productivity for society as a whole. As user expectations for connection reliability, data speed, and device battery life become more demanding, technology for wireless networking must also keep pace with such expectations. Accordingly, there is continuing interest in improving wireless networking technology.SUMMARY

[0004] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.

[0005] In accordance with aspects of the disclosure, a method includes receiving, by a user equipment (UE) from a network node, a Random Access Channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam; receiving, by the UE from the network node, channel state information reference signal (CSI-RS) for each beam; measuring, by the UE, the CSI-RS; and selecting, by the UE, a specific beam based on the measured CSI-RS.

[0006] In an aspect, the method may further include selecting a random access preamble index associated to the specific beam based on the indication.

[0007] In an aspect, the RACH configuration may further include an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0008] In an aspect, the method may further include: determining, by the UE, to perform random access using the random access preamble index associated to the specific beam; and initiating, by the UE, monitoring of a random access response associated to the specific beam.

[0009] In an aspect, the association between the subset of random access preamble indexes and a beam may be performed based on a CSI-RS of the beam.

[0010] In an aspect, each CSI-RS may be uniquely associated with a beam.

[0011] In an aspect, the association may be between the subset of random access preambles and the CSI-RS or a Non-Cell-Defined SSB (NCD SSB).

[0012] In an aspect, each CSI-RS may map into a unique subset of preambles within the subset of preambles available for contention-based random access.

[0013] In an aspect, the method may further include receiving, by the UE from the network node, an indication including a threshold value to determine a CSI-RS.

[0014] In an aspect, a user equipment (UE) includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform any one of the preceding methods.

[0015] In an aspect, processor-readable medium storing instructions which, when executed by at least one processor of a UE, causes the UE at least to perform any one of the preceding methods.

[0016] In accordance with aspects of the disclosure, a method includes: transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; and transmitting, from the network node to the UE, channel state information reference signal (CSI-RS) for each beam.

[0017] In an aspect, the RACH configuration may further include an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0018] In an aspect, the method may further include receiving, by the network node from the UE, a random access preamble index (RAPID).

[0019] In an aspect, the method may further include identifying a beam selected by the UE based on the RAPID.

[0020] In an aspect, the method may further include transmitting, to the UE by the network node, a response in the identified beam.

[0021] In an aspect, a network apparatus includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, causes the network apparatus at least to perform any one of the preceding methods.

[0022] In an aspect, a processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, causes the network apparatus at least to perform any one of the preceding methods.

[0023] In accordance with aspects of the disclosure, a method includes: receiving, by a user equipment (UE) from a network node, a random access channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam; receiving, by the UE from the network node, an indication of location information for each beam; and selecting, by the UE, a specific beam based on the location information.

[0024] In an aspect, the RACH configuration may further include an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0025] In an aspect, the method may further include selecting a random access preamble index associated to the specific beam based on the indication.

[0026] In an aspect, the method may further include: determining, by the UE, to perform random access using the random access preamble index associated to a specific beam; and initiating, by the UE, monitoring of a random access response associated to the specific beam.

[0027] In an aspect, the association between the subset of random access preamble indexes and a beam may be performed based the location information.

[0028] In an aspect, a NCD SSB may include the location information, and each NCD SSB may be uniquely associated with a beam.

[0029] In an aspect, the association may be between the subset of random access preambles and a NCD SSB.

[0030] In an aspect, the location information may include at least one of a location-based reference point or a geographical coordinate.

[0031] In an aspect, a user equipment (UE), includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform any one of the preceding methods.

[0032] In an aspect, a processor-readable medium storing instructions which, when executed by at least one processor of a UE, cause the UE at least to perform any one of the preceding methods.

[0033] In accordance with aspects of the disclosure, a method includes: transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; and transmitting, from the network node to the UE, location information for each beam.

[0034] In an aspect, the RACH configuration may further include an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0035] In an aspect, the method may further include receiving, by the network node from the UE, a random access preamble index (RAPID).

[0036] In an aspect, the method may further include identifying a beam selected by the UE based on the RAPID.

[0037] In an aspect, the method may further include transmitting, to the UE by the network node, a response in the identified beam.

[0038] In an aspect, a network apparatus includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, causes the network apparatus at least to perform any of the preceding methods.

[0039] In an aspect, a processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, causes the network apparatus at least to perform any of the preceding methods.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Some example embodiments will now be described with reference to the accompanying drawings.

[0041] FIG. 1 is a diagram of an example embodiment of wireless networking between a network system and a user equipment (UE), according to one illustrated aspect of the disclosure;

[0042] FIG. 2 is a diagram of example components of a network system, according to one illustrated aspect of the disclosure;

[0043] FIG. 3 is a diagram of an example embodiment of a satellite performing a Random Access (RA) procedure to broadcast New Radio (NR) cells at different points in time, according to one illustrated aspect of the disclosure;

[0044] FIG. 4 is a diagram of an example embodiment of a satellite performing a RA procedure to broadcast NR cells through a wide satellite beam footprint, according to one illustrated aspect of the disclosure;

[0045] FIG. 5 is a diagram of an example embodiment of signals and operations among a UE and a network node such as gNodeB (gNB), according to one illustrated aspect of the disclosure;

[0046] FIG. 6 is a diagram of an example block diagram of a wireless station or node (e.g., network node (such as gNB, user node or UE, relay node, or other node), according to one illustrated aspect of the disclosure.DETAILED DESCRIPTION

[0047] In the following description, certain specific details are set forth in order to provide a thorough understanding of the disclosed aspects. However, one skilled in the relevant art will recognize that aspects may be practiced without one or more of these specific details or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the aspects.

[0048] Reference throughout this specification to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearances of the phrases “in one aspect” or “in an aspect” in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

[0049] Embodiments described in the present disclosure may be implemented in wireless networking apparatuses, such as, without limitation, apparatuses utilizing Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-codedivision multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LIE- Advanced, enhanced LTE (eLTE), 5G New Radio (5G NR), 5G Advance, 6G (and beyond) and 802.1 lax (Wi-Fi 6), among other wireless networking systems. The term ‘eLTE’ here denotes the LTE evolution that connects to a 5G core. LTE is also known as evolved UMTS terrestrial radio access (EUTRA) or as evolved UMTS terrestrial radio access network (EUTRAN).

[0050] The present disclosure may use the term “serving network device” to refer to a network node or network device (or a portion thereof) that services a UE. As used herein, the terms “transmit to,” “receive from,” and “cooperate with,” (and their variations) include communications that may or may not involve communications through one or more intermediate devices or nodes. The term “acquire” (and its variations) includes acquiring in the first instance or reacquiring after the first instance. The term “connection” may mean a physical connection or a logical connection.

[0051] The present disclosure uses 5G NR as an example of a wireless network and may use smartphones and / or extended reality headsets as an example of user equipments (UEs). It is intended and shall be understood that such examples are merely illustrative, and the present disclosure is applicable to other wireless networks and user equipment.

[0052] FIG. 1 is a diagram depicting an example of wireless networking between a network system 100 and a user equipment (UE) 150. The network system 100 may include one or more network nodes 120, one or more servers 110, and / or one or more network equipment 130 (e.g., test equipment). The network nodes 120 will be described in more detail below. As used herein, the term “network apparatus” may refer to any component of the network system 100, such as the server 110, the network node 120, the network equipment 130, any component(s) of the foregoing, and / or any other component(s) of the network system 100. Examples of network apparatuses include, without limitation, apparatuses implementing aspects of 5G NR, among others. The present disclosure describes embodiments related to 5GNR and embodiments that involve aspects defined by 3rd Generation Partnership Project (3GPP). However, it is contemplated that embodiments relating to other wireless networking technologies are encompassed within the scope of the present disclosure.

[0053] The following description provides further details of examples of network nodes. In a 5G NR network, a gNodeB (also known as gNB) may include, e.g., a node that provides new radio (NR) user plane and control plane protocol terminations towards the UE and that is connected viaa NG interface to the 5G core (5GC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 3.2, which is hereby incorporated by reference herein.

[0054] A gNB supports various protocol layers, e.g., Layer 1 (LI) - physical layer, Layer 2 (L2), and Layer 3 (L3).

[0055] The layer 2 (L2) of NR is split into the following sublayers: Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP), where, e.g.:o The physical layer offers to the MAC sublayer transport channels;o The MAC sublayer offers to the RLC sublayer logical channels;o The RLC sublayer offers to the PDCP sublayer RLC channels;o The PDCP sublayer offers to the SDAP sublayer radio bearers;o The SDAP sublayer offers to 5GC quality of service (QoS) flows;o Control channels include broadcast control channel (BCCH) and physical control channel (PCCH).

[0056] Layer 3 (L3) includes, e.g., radio resource control (RRC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 6, which is hereby incorporated by reference herein.

[0057] A gNB central unit (gNB-CU) includes, e.g., a logical node hosting, e.g., radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocols of the gNB or RRC and PDCP protocols of the en-gNB, that controls the operation of one or more gNB distributed units (gNB-DUs). The gNB-CU terminates the Fl interface connected with the gNB-DU. A gNB-CU may also be referred to herein as a CU, a central unit, a centralized unit, or a control unit.

[0058] A gNB Distributed Unit (gNB-DU) includes, e.g., a logical node hosting, e.g., radio link control (RLC), media access control (MAC), and physical (PHY) layers of the gNB or en-gNB, and its operation is partly controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the Fl interface connected with the gNB-CU. A gNB-DU may also be referred to herein as DU or a distributed unit.

[0059] As used herein, the term “network node” may refer to any of a gNB, a gNB-CU, or a gNB-DU, or any combination of them. A RAN (radio access network) node or network node such as, e.g., a gNB, gNB-CU, or gNB-DU, or parts thereof, may be implemented using, e.g., anapparatus with at least one processor and / or at least one memory with processor-readable instructions (“program”) configured to support and / or provision and / or process CU and / or DU related functionality and / or features, and / or at least one protocol (sub-)layer of a RAN (radio access network), e.g., layer 2 and / or layer 3. Different functional splits between the central and distributed units are possible. An example of such an apparatus and components will be described in connection with FIG. 6 below.

[0060] The gNB-CU and gNB-DU parts may, e.g., be co-located or physically separated. The gNB-DU may even be split further, e.g., into two parts, e.g., one including processing equipment and one including an antenna. A central unit (CU) may also be called baseband unit / radio equipment controller / cloud-RAN / virtual-RAN (BBU / REC / C-RAN / V-RAN), open-RAN (O-RAN), or part thereof. A distributed unit (DU) may also be called remote radio head / remote radio unit / radio equipment / radio unit (RRH / RRU / RE / RU), or part thereof. Hereinafter, in various example embodiments of the present disclosure, a network node, which supports at least one of central unit functionality or a layer 3 protocol of a radio access network, may be, e.g., a gNB-CU. Similarly, a network node, which supports at least one of distributed unit functionality or a layer 2 protocol of the radio access network, may be, e.g., a gNB-DU.

[0061] A gNB-CU may support one or multiple gNB-DUs. A gNB-DU may support one or multiple cells and, thus, could support a serving cell for a user equipment (UE) or support a candidate cell for handover, dual connectivity, and / or carrier aggregation, among other procedures.

[0062] The user equipment (UE) 150 may be or include a wireless or mobile device, an apparatus with a radio interface to interact with a RAN (radio access network), a smartphone, an in-vehicle apparatus, an loT device, or a machine-to-machine (M2M) device, among other types of user equipment. Such UE 150 may include: at least one processor; and at least one memory including program code; where the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform certain operations, such as, e.g., RRC connection to the RAN. An example of components of a UE will be described in connection with FIG. 5. In embodiments, the UE 150 may be configured to generate a message (e.g., including a cell ID) to be transmitted via radio towards a RAN (e.g., to reach and communicate with a serving cell). In embodiments, the UE 150 may generate and transmit and receive RRC messages containing one or more RRC PDUs (packet data units). Persons skilled in the art will understand RRC protocol as well as other procedures a UE may perform.

[0063] With continuing reference to FIG. 1, in the example of a 5G NR network, the network system 100 provides one or more cells, which define a coverage area of the network system 100. As described above, the network system 100 may include a gNB of a 5G NR network or may include any other apparatus configured to control radio communication and manage radio resources within a cell. As used herein, the term “resource” may refer to radio resources, such as a resource block (RB), a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, etc. In embodiments, the network node 120 may be called a base station.

[0064] FIG. 1 provides an example and is merely illustrative of a network system 100 and a UE 150. Persons skilled in the art will understand that the network system 100 includes components not illustrated in FIG. 1 and will understand that other user equipment may be in communication with the network system 100.

[0065] FIG. 2 is a block diagram of example components of the network system 100 of FIG.1. A 5G NR network may be described as an example of the network system 100, and it is intended that aspects of the following description shall be applicable to other types of network systems, as well. The network system may operate in accordance with the signals and connections shown in FIG. 1 such that the UE 150 is in communication with the network system 100 through the radio access network 225. Additionally, the network system may be divided into user plane components and functions and control plane components and functions, as shown and described herein. Unless indicated otherwise, the terms “component,” “function,” and “service” may be used interchangeably herein, and they may refer to and be implemented by instructions executed by one or more processors.

[0066] Example functions of the components are described below. The example functions are merely illustrative, and it shall be understood that additional operations and functions may be performed by the components described herein. Additionally, the connections between components may be virtual connections over service-based interfaces such that any component may communicate with any other component. In this manner, any component may act as a service “producer,” for any other component that is a service “consumer,” to provide services for network functions.

[0067] For example, a core network 210 is described in the control plane of the network system. The core network 210 may include an authentication server function (AUSF) 211, anaccess and mobility function (AMF) 212, and a session management function (SMF) 213. The core network 210 may also include a network slice selection function (NSSF) 214, a network exposure function (NEF) 215, a network repository function (NRF) 216, and a unified data management function (UDM) 217, which may include a uniform data repository (UDR) 224.

[0068] Additional components and functions of the core network 210 may include an application function 218, policy control function (PCF) 219, network data analytics function (NWDAF) 220, analytics data repository function (ADRF) 221, management data analytics function (MDAF) 222, and operations and management function (0AM) 223.

[0069] The user plane includes the UE 150, a radio access network (RAN) 225, a user plane function (UPF) 226, and a data network (DN) 227. The RAN 225 may include one or more components described in connection with FIG. 1, such as one or more network nodes. However, the RAN 225 may not be limited to such components. The UPF 226 provides connection for data being transmitted over the RAN 225. The DN 226 identifies services from service providers, Internet access, and third-party services, for example.

[0070] The AMF 212 processes connection and mobility tasks. The AUSF 211 receives authentication requests from the AMF 212 and interacts with UDM 217 to authenticate and validate network responses to determine successful authentication. The SMF 213 conducts packet data unit (PDU) session management and manages session context with the UPF 226.

[0071] The NSSF 214 may select a network slicing instance (NSI) and determine the allowed network slice selection assistance information (NSSAI). This selection and determination are utilized to set the AMF 212 to provide service to the UE 150. The NEF 215 secures access to network services for third parties to create specialized network services. The NRF 216 acts as a repository to store network functions to allow the functions to register with and discover each other.

[0072] The UDM 217 generates authentication vectors for use by the AUSF 211 and ADM 212 and provides user identification handling. The UDM 217 may be connected to the UDR 224 which stores data associated with authentication, applications, or the like. The AF 218 provides application services to a user (e.g., streaming services, etc.). The PCF 219 provides policy control functionality. For example, the PCF 219 may assist in network slicing and mobility management, as well as provide quality of service (QoS) and charging functionality.

[0073] The NWDAF 220 collects data (e.g., from the UE 150 and the network system) to perform network analytics and provide insight to functions that utilize the analytics in the providing of services. The ADRF 221 allows the storage, retrieval, and removal of data and analytics by consumers. The MDAF 222 provides additional data analytics services for network functions. The 0AM 223 provides provisioning and management processing functions to manage elements in or connected to the network (e.g., UE 150, network nodes, etc.).

[0074] FIG. 2 is merely an example of components of a network system, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the network system may include other components not illustrated in FIG. 2. In embodiments, the network system may not include every component illustrated in FIG. 2. In embodiments, the components and connections may be implemented with different connections than those illustrated in FIG. 2. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0075] Due to power constraints at the network node side (for example, the gNodeB (gNB) side), the mechanism of “extended SSB periodicity” is adopted with a combination of Cell inactive periods (Cell DTX). During the inactive periods, the Cell does not convey any payload, control or signaling information, including Master Information Blocks (MIB), System Information Blocks (SIB), and Channel State Information Reference Signals (CSI-RS). The periods between active times may be up to 160 milliseconds (ms) with different length for the active periods, though other time periods may be contemplated. Referring to FIGS. 3 and 4, considerations in how to implement “switch off’ of cell / beams are described. Beams may include a satellite beam footprint, which is a radio beam transmitted by the satellite and might correspond to a full cell, a part of a cell, or a beam as described in the context of Third Generation Partnership Project (3GPP) New Radio (NR) Systems.

[0076] FIG. 3 shows an example satellite performing a Random Access (RA) procedure to broadcast four different NR cells at different points in time. As shown in FIG. 3, a 160 ms periodicity is used and each of the four cells are broadcasted at distinguished points in time. The blank block in the graph represents a gap where none of the cells are transmitted, though a gap in the transmission of cells may not be present.

[0077] FIG. 4 shows another example satellite performing an RA procedure to broadcast NR cells through a wide satellite beam footprint with a large coverage area. The wide (main) beam carries MIB / SIB / RS and other necessary information for the UE to perform search and(re)selection to the cell, and to acquire the necessary information. UEs in connected mode are moved to resources covered by one or more narrow satellite beam footprints. The narrow satellite beam footprints do not necessarily correspond to beams as described in the context of 3 GPP NR Systems as the “switching” time is expected to be slower in this case. In some aspects, each of the narrow satellite beam footprints may be identified by different CSI-RS configuration, and a Random Access Occasion (RO) to CSI mapping may be created. The full RA procedure may be performed in the narrow beams.

[0078] A problem with the RA procedures of FIGS. 3 and 4 is the need to have Random Access Channel (RACH) resources available in each of the cells (FIG. 3) or satellite beam footprints (FIG.4), which places further constraints on uplink (UL) capacity in the cells, in addition to other limiting factors such as poor link budgeting and the introduction of “OFF” periods due to power constraints at the satellite end.

[0079] To remedy some of the problems of the RA procedure of FIG. 4, the RA attempt may be performed by the UE on the large cell, and the UE may be moved to the narrow satellite beam footprints after this operation is completed. The embodiment of FIG. 5 further enhances this RA procedure by having a network node such as gNB provide CSI-to-preamble mapping to one or more UEs, where each RO can accommodate RA attempts by UE in every satellite beam footprint. The UEs perform RA attempts in the wide satellite beam footprint, and the gNB identifies a narrow satellite beam footprint selected by each UE depending on the preamble selected by the UE. By the gNB configuration, the UE knows a starting point of Random Access Response (RAR) for a defined time window (ra-ResponseWindow) associated to its satellite beam footprints. The gNB provides a UE response in the narrow satellite beam footprint.

[0080] FIG. 5 is a diagram of an example embodiment of signals and operations among a user equipment (UE) and a network node such as gNB, according to one illustrated aspect of the disclosure. In various embodiments, FIG. 5 shows an example method of performing a RA procedure between the UE and gNB, according to one illustrated aspect of the disclosure. In various embodiments, the components depicted in FIG. 5 may correspond to similar components described above in FIGS. 1 and 2. It will be understood that a described signal may have associated operations, and a described operation may have associated signals.

[0081] At operation 501, the gNB transmits a modified RACH configuration to the UE. The UE receives the modified RACH configuration from the gNB. The gNB provides the RACHconfiguration through system information with the following modifications: an association between a subset of RA preambles and a narrow beam; and a configuration that enables the UE to identify a starting point of an ra-ResponseWindow for each of the subset of preambles. The narrow beam may be a narrow satellite beam footprint.

[0082] Regarding the association between the subset of RA preambles and a narrow beam, in some aspects, the association is between a group of preambles and a CSI-RS or a Non Cell Defining System Synchronization Block (NCD-SSB), where each CSI-RS or NCD-SSB is uniquely associated to a narrow beam. In aspects, each CSI-RS may map into a unique subset of preambles from the entire set of configured random access preambles available for contention based random access. In aspects, the gNB may configure selection threshold values that allow the UE to select the strongest of the observed CSI-RS from the configured set of CSI-RS to monitor. For example, the strongest of the observed CSI-RS may include a CSI-RS having the highest power level. In aspects, the gNB may configure the UE to select randomly between any CSI-RS that meets a certain detection threshold. For example, the UE selecting randomly between any CSI-RS that meets a certain detection threshold may result in larger diversity across cells if coverage is sufficiently good for a given UE that observes two or more cells as being within coverage. In aspects, a configuration may enable the UE to identify the starting point of the ra-responseWindow for each of the subset of preambles.

[0083] At operation 502, the gNB transmits reference symbols for each narrow beam to the UE. The UE receives the reference symbols for each narrow beam from the gNB. At operation 503, the UE measures the reference symbols (e.g., the reference signal).

[0084] At operation 504, the UE selects a narrow beam, for example, a narrow satellite beam footprint. The satellite beam footprint may be selected based on a ranking of received power of the CSI-RS or NCD-SSB for each of the satellite beam footprints. The satellite beam footprint may be selected based on location information, such as a reference point, a geographical coordinate, or the like. The location information may be transmitted by the NCD-SSB.

[0085] At operation 505, the UE selects a preamble index based on the beam selection to perform a RA attempt, with the preamble index being associated to the selected satellite beam footprint.

[0086] At operation 506, the UE transmits a RA attempt with a selected RA preamble index (RAPID) to the gNB. The gNB receives the RA attempt with the RAPID from the UE.

[0087] At operation 507, the UE configures a ra-ResponseWindow according to the RAPID, where the RAR is associated with the selected satellite beam footprint. For example, based on the received RAPID, the gNB provides a RAR in the associated resource transmitted in the respective satellite beam footprint.

[0088] By the operations of FIG. 5, RA occasions may be limited in the cell, as UEs from the different Satellite beam footprints might reuse the same occasion for access with different preambles. Further, in sparse deployments, the NW may limit the power consumption on each of the narrow Satellite beam footprints to the reference signals (CSI-RS or Non-Cell Defining SSBs). Therefore, there may be no need to turn UL on in all beams until a connected mode UE is associated to one of the narrow satellite beam footprints. RARs, for example, Msg2, Msg3 and Msg4 in the RA procedure, which are not as robust as reference signals or the preamble transmission by the UE, may benefit from the enhanced link budget in the narrower beams. Furthermore, if the ra-responseWindow for each beam is properly configured, the proportion of allocated resources for each of the narrow Satellite beam footprints may be dynamically changed according to demand. This is less flexible when RA occasions are firmly configured for each of the satellite beam footprints.

[0089] The operations of FIG. 5 are merely illustrative, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the operations may include other operations not illustrated in FIG. 5. In embodiments, the operations may not include every operation illustrated in FIG. 5. In embodiments, the operations may be implemented in a different order than that illustrated in FIG. 5. Such and other embodiments are contemplated to be within the scope of the present disclosure. Persons of skill in the art will appreciate that, although various example components are described as performing various functions, other components may perform those functions described in FIG. 5.

[0090] The following describes operations from the perspective of a network node. From such a perspective, a method may include: receiving, by a user equipment (UE) from a network node, a Random Access Channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam (e.g., FIG. 5, operation 501); receiving, by the UE from the network node, channel state information reference signal (CSI-RS) for each beam (e.g., FIG. 5, operation 502); measuring, by the UE, the CSI-RS (e.g., FIG. 5, operation 503);and selecting, by the UE, a specific beam based on the measured CSI-RS (e.g., FIG. 5, operation 504).

[0091] FIG. 6 is a block diagram of a wireless station or node (e.g., UE, user device, AP, BS, eNB, gNB, RAN node, network node, TRP, or other node) 600, according to one illustrated aspect of the present disclosure. The wireless station 600 may include, for example, one or more (e.g., two as shown in FIG. 6) RF (radio frequency) or wireless transceivers 602A, 602B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit / entity (controller) 608 to execute instructions or software and control transmission and receptions of signals, and a memory 606 to store data and / or instructions.

[0092] Processor 604 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 604, which may be a baseband processor, for example, may generate messages, packets, frames, or other signals for transmission via wireless transceiver 602 (602A or 602B). Processor 604 may control transmission of signals or messages over a wireless network and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 602, for example). Processor 604 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 604 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and / or any combination of these. Using other terminology, processor 604 and transceiver 602 together may be considered as a wireless transmitter / receiver system, for example.

[0093] In addition, referring to FIG. 6, a controller (or processor) 608 may execute software and instructions, and may provide overall control for the station 600, and may provide control for other systems not shown in FIG. 6, such as controlling input / output devices (e.g., display, keypad), and / or may execute software for one or more applications that may be provided on wireless station 600, such as, for example, an email program, audio / video applications, a word processor, a Voice over IP application, or other application or software.

[0094] In addition, a storage medium may be provided that includes stored instructions, whichwhen executed by a controller or processor may result in the processor 604, or other controller or processor, performing one or more of the functions or tasks described above.

[0095] According to another example embodiment, RF or wireless transceiver(s) 602A / 602B may receive signals or data and / or transmit or send signals or data. Processor 604 (and possibly transceivers 602A / 602B) may control the RF or wireless transceiver 602A or 602B to receive, send, broadcast or transmit signals or data.

[0096] Example embodiments are provided or described for each of the example methods, including: An apparatus (e.g., 600, FIG. 6) including means (e.g., processor 604, RF transceivers 602A and / or 602B, and / or memory 606, in FIG. 6) for carrying out any of the methods; a non-transitory computer-readable storage medium (e.g., memory 606, FIG. 6) comprising instructions stored thereon that, when executed by at least one processor (processor 604, FIG. 6), are configured to cause a computing system (e.g., 600, FIG. 6) to perform any of the example methods; and an apparatus (e.g., 600, FIG. 6) including at least one processor (e.g., processor 604, FIG. 6), and at least one memory (e.g., memory 606, FIG. 6) including computer program code, the at least one memory (606) and the computer program code configured to, with the at least one processor (604), cause the apparatus (e.g., 600) at least to perform any of the example methods.

[0097] Further embodiments of the present disclosure include the following examples.

[0098] Example 1.1. An apparatus in a user equipment (UE), comprising:means for receiving, by the UE from a network node, a Random Access Channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam;means for receiving, by the UE from the network node, channel state information reference signal (CSI-RS) for each beam;means for measuring, by the UE, the CSI-RS; andmeans for selecting, by the UE, a specific beam based on the measured CSI-RS.

[0099] Example 1.2. The apparatus of Example 1.1, further comprising:means for selecting a random access preamble index associated to the specific beam based on the indication

[0100] Example 1.3. The apparatus of Example 1.2, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0101] Example 1.4. The apparatus of Example 1.3, further comprising:means for determining, by the UE, to perform random access using the random access preamble index associated to the specific beam; andmeans for initiating, by the UE, monitoring of a random access response associated to the specific beam.

[0102] Example 1.5. The apparatus of any one of Examples 1.1 through 1.4, wherein the association between the subset of random access preamble indexes and a beam is performed based on a CSI-RS of the beam.

[0103] Example 1.6. The apparatus of Example 1.5, wherein each CSI-RS is uniquely associated with a beam.

[0104] Example 1.7. The apparatus of Example 1.4, wherein the association is between the subset of random access preambles and the CSI-RS or a Non-Cell-Defined SSB (NCD SSB).

[0105] Example 1.8. The apparatus of any one of Examples 1.1 through 1.7, wherein each CSI-RS maps into a unique subset of preambles within the subset of preambles available for contention-based random access.

[0106] Example 1.9. The apparatus of any one of Examples 1.1 through 1.8, further comprising:means for receiving, by the UE from the network node, an indication including a threshold value to determine a CSI-RS.

[0107] Example 1.12. An apparatus in a network node, comprising:means for transmitting, by the network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; andmeans for transmitting, from the network node to the UE, channel state information reference signal (CSI-RS) for each beam.

[0108] Example 1.13. The apparatus of Example 1.12, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0109] Example 1.14. The apparatus of Example 1.12 or 1.13, further comprising:means for receiving, by the network node from the UE, a random access preamble index(RAPID).

[0110] Example 1.15. The apparatus of Example 1.14, further comprising:means for identifying a beam selected by the UE based on the RAPID.

[0111] Example 1.16. The apparatus of Example 1.15, further comprising:means for transmitting, to the UE by the network node, a response in the identified beam.

[0112] Example 2.1. A method, comprising:receiving, by a user equipment (UE) from a network node, a Random Access Channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam;receiving, by the UE from the network node, channel state information reference signal (CSI-RS) for each beam;measuring, by the UE, the CSI-RS; andselecting, by the UE, a specific beam based on the measured CSI-RS.

[0113] Example 2.2. The method of Example. 2.1, further comprising:selecting a random access preamble index associated to the specific beam based on the indication.

[0114] Example 2.3. The method of Example 2.2, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0115] Example 2.4. The method of Example 2.3, further comprising:determining, by the UE, to perform random access using the random access preamble index associated to the specific beam; andinitiating, by the UE, monitoring of a random access response associated to the specific beam.

[0116] Example 2.5. The method of any one of Examples 2.1 through 2.4, wherein the association between the subset of random access preamble indexes and a beam is performed based on a CSI-RS of the beam.

[0117] Example 2.6. The method of Example 2.5, wherein each CSI-RS is uniquely associated with a beam.

[0118] Example 2.7. The method of Example 2.4, wherein the association is betweenthe subset of random access preambles and the CSI-RS or a Non-Cell-Defined SSB (NCD SSB).

[0119] Example 2.8. The method of any one of Examples 2.1 through 2.7, wherein each CSI-RS maps into a unique subset of preambles within the subset of preambles available for contention-based random access.

[0120] Example 2.9. The method of any one of Examples 2.1 through 2.8, further comprising:receiving, by the UE from the network node, an indication including a threshold value to determine a CSI-RS.

[0121] Example 2.10. A user equipment (UE), comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform a method as in any one of Examples 2.1 to 2.9.

[0122] Example 2.11. A processor-readable medium storing instructions which, when executed by at least one processor of a UE, cause the UE at least to perform a method as in any one of Examples 2.1 to 2.9.

[0123] Example 2.12. A method, comprising:transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; andtransmitting, from the network node to the UE, channel state information reference signal (CSI-RS) for each beam.

[0124] Example 2.13. The method of Example 2.12, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of the subset of random access preambles.

[0125] Example 2.14. The method of Example 2.12 or 2.13, further comprising:receiving, by the network node from the UE, a random access preamble index (RAPID).

[0126] Example 2.15. The method of Example 2.14, further comprising:identifying a beam selected by the UE based on the RAPID.

[0127] Example 2.16. The method of Example 2.15, further comprising:transmitting, to the UE by the network node, a response in the identified beam.

[0128] Example 2.17. A network apparatus, comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, causes the network apparatus at least to perform a method as in any one of Examples 2.12 to 2.16.

[0129] Example 2.18. A processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, cause the network apparatus at least to perform a method as in any one of Examples 2.12 to 2.16.

[0130] Example 3.1. An apparatus in a user equipment (UE), comprising:means for receiving, by a user equipment (UE) from a network node, a random access channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam;means for receiving, by the UE from the network node, an indication of location information for each beam; andmeans for selecting, by the UE, a specific beam based on the location information.

[0131] Example 3.2. The apparatus of Example 3.1, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0132] Example 3.3. The apparatus of Example 3.1 or 3.2, further comprising:means for selecting a random access preamble index associated to the specific beam based on the indication.

[0133] Example 3.4. The apparatus of Example 3.3, further comprising:means for determining, by the UE, to perform random access using the random access preamble index associated to a specific beam; andmeans for initiating, by the UE, monitoring of a random access response associated to the specific beam.

[0134] Example 3.5. The apparatus of any one of Examples 3.1 through 3.4, wherein the association between the subset of random access preamble indexes and a beam is performed based the location information.

[0135] Example 3.6. The apparatus of Example 3.5, wherein a NCD SSB includes the location information, and wherein each NCD SSB is uniquely associated with a beam.

[0136] Example 3.7. The apparatus of Example 3.4, wherein the association is between the subset of random access preambles and a NCD SSB.

[0137] Example 3.8. The apparatus of any one of Examples 3.1 through 3.7, wherein the location information includes at least one of a location-based reference point or a geographical coordinate.

[0138] Example 3.11. An apparatus in a network node, comprising:means for transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; andmeans for transmitting, from the network node to the UE, location information for each beam.

[0139] Example 3.12. The apparatus of Example 3.11, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0140] Example 3.13. The apparatus of Example 3.11 or 3.12, further comprising: means for receiving, by the network node from the UE, a random access preamble index (RAPID).

[0141] Example 3.14. The apparatus of Example 3.13, further comprising:means for identifying a beam selected by the UE based on the RAPID.

[0142] Example 3.15. The apparatus of Example 3.14, further comprising:means for transmitting, to the UE by the network node, a response in the identified beam

[0143] Example 4.1. A method, comprising:receiving, by a user equipment (UE) from a network node, a random access channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam;receiving, by the UE from the network node, an indication of location information for each beam; andselecting, by the UE, a specific beam based on the location information

[0144] Example 4.2. The method of Example 4.1, wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0145] Example 4.3. The method of Example 4.1 or 4.2, further comprising: selecting a random access preamble index associated to the specific beam based on the indication.

[0146] Example 4.4. The method of Example 4.3, further comprising:determining, by the UE, to perform random access using the random access preamble index associated to a specific beam; andinitiating, by the UE, monitoring of a random access response associated to the specific beam.

[0147] Example 4.5. The method of any one of Examples 4.1 through 4.5, wherein the association between the subset of random access preamble indexes and a beam is performed based the location information.

[0148] Example 4.6. The method of Example 4.5, wherein a NCD SSB includes the location information, and wherein each NCD SSB is uniquely associated with a beam.

[0149] Example 4.7. The method of Example 4.4, wherein the association is between the subset of random access preambles and a NCD SSB.

[0150] Example 4.8. The method of any one of Examples 4.1 through 4.7, wherein the location information includes at least one of a location-based reference point or a geographical coordinate.

[0151] Example 4.9. A user equipment (UE), comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform a method as in any one of Examples 4.1 to 4.8.

[0152] Example 4.10. A processor-readable medium storing instructions which, when executed by at least one processor of a UE, cause the UE at least to perform a method as in any one of Examples 4.1 to 4.8.

[0153] Example 4.11. A method, comprising:transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; andtransmitting, from the network node to the UE, location information for each beam.

[0154] Example 4.12. The method of Example 4.11, wherein the RACH configuration1further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

[0155] Example 4.13. The method of Example 4.11 or 4.12, further comprising:receiving, by the network node from the UE, a random access preamble index (RAPID).

[0156] Example 4.14. The method of Example 4.13, further comprising:identifying a beam selected by the UE based on the RAPID.

[0157] Example 4.15. The method of Example 4.14, further comprising:transmitting, to the UE by the network node, a response in the identified beam.

[0158] Example 4.16. A network apparatus, comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, causes the network apparatus at least to perform a method as in any one of Examples 4.11 to 4.15.

[0159] Example 4.17. A processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, cause the network apparatus at least to perform a method as in any one of Examples 4.11 to 4.15.

[0160] The embodiments and aspects disclosed herein are examples of the present disclosure and may be embodied in various forms. For instance, although certain embodiments herein are described as separate embodiments, each of the embodiments herein may be combined with one or more of the other embodiments herein. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[0161] The phrases “in an aspect,” “in aspects,” “in various aspects,” “in some aspects,” or “in other aspects” may each refer to one or more of the same or different aspects in accordance with this present disclosure. The phrase “a plurality of’ may refer to two or more.

[0162] In various embodiments, the terms “first message” and “second message,” as well as any subsequent messages may refer to any messages that are transmitted or received in an order and are not necessarily limited to any particular message.

[0163] The phrases “in an embodiment,” “in embodiments,” “in various embodiments,” “in some embodiments,” or “in other embodiments” may each refer to one or more of the same or different embodiments in accordance with the present disclosure. A phrase in the form “A or B” means “(A), (B), or (A and B).” A phrase in the form “at least one of A, B, or C” means “(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C) ”

[0164] Any of the herein described methods, programs, algorithms or codes may be converted to, or expressed in, a programming language or computer program. The terms “programming language” and “computer program,” as used herein, each include any language used to specify instructions to a computer, and include (but is not limited to) the following languages and their derivatives: Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, Python, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, fifth, or further generation computer languages. Also included are database and other data schemas, and any other meta- languages. No distinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. Thus, reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all such states. Reference to a program may encompass the actual instructions and / or the intent of those instructions.

[0165] While aspects of the present disclosure have been shown in the drawings, it is not intended that the present disclosure be limited thereto, as it is intended that the present disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular aspects. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1. A method, comprising:receiving, by a user equipment (UE) from a network node, a random access channel (RACH) configuration including an indication of an association between a subset of random access preamble indexes and a beam;receiving, by the UE from the network node, an indication of location information for each beam; andselecting, by the UE, a specific beam based on the location information.

2. The method of claim 1 , wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

3. The method of claim 1 or 2, further comprising:selecting a random access preamble index associated to the specific beam based on the indication.

4. The method of claim 3, further comprising:determining, by the UE, to perform random access using the random access preamble index associated to a specific beam; andinitiating, by the UE, monitoring of a random access response associated to the specific beam.

5. The method of any one of claims 1 to 4, wherein the association between the subset of random access preamble indexes and a beam is performed based the location information.

6. The method of claim 5, wherein a NCD SSB includes the location information, and wherein each NCD SSB is uniquely associated with a beam.

257. The method of claim 4, wherein the association is between the subset of random access preambles and a NCD SSB.

8. The method of any one of claims 1 to 7, wherein the location information includes at least one of a location-based reference point or a geographical coordinate.

9. A user equipment (UE), comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform a method as in any one of claims 1 to 8.

10. A processor-readable medium storing instructions which, when executed by at least one processor of a UE, cause the UE at least to perform a method as in any one of claims 1 to 8.

11. A method, comprising:transmitting, by a network node providing a source cell to a user equipment (UE), a RACH configuration including an indication of an association between a subset of random access preamble indexes and a beam; andtransmitting, from the network node to the UE, location information for each beam.

12. The method of claim 11 , wherein the RACH configuration further includes an indication of a configuration to identify a start of random access response window for each of a subset of random access preambles.

13. The method of claim 11 or 12, further comprising:receiving, by the network node from the UE, a random access preamble index (RAPID).

14. The method of claim 13, further comprising:identifying a beam selected by the UE based on the RAPID.

15. The method of claim 14, further comprising:transmitting, to the UE by the network node, a response in the identified beam.

16. A network apparatus, comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, causes the network apparatus at least to perform a method as in any one of claims 11 to 15.

17. A processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, cause the network apparatus at least to perform a method as in any one of claims 11 to 15.

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