Beam-specific rach occasion density

Abstract

Aspects of the disclosure provide techniques for adjusting a density and / or a number of random access channel (RACH) occasions for one synchronization signal block (SSB) beam or a subset of SSB beams out of a plurality of available SSB beams. To this end, aspects of the disclosure utilize a beam-specific bit field transmitted by a base station to a user equipment (UE), which can indicate a RACH occasion density for an SSB beam or a subset of SSB beams. In some aspects, time and frequency resources for RACH occasions with a beam-specific alternative density can be identified via resources for general RACH occasions. Based on the adjusted RACH occasion density, a UE can select one of these time and frequency resources to initiate access with the base station.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 088,121, filed October 6, 2020, entitled "BEAM SPECIFIC RACH OCCASION DENSITY," and U.S. Patent Application No. 17 / 494,327, filed October 5, 2021, entitled "BEAM SPECIFIC RACH OCCASION DENSITY," both of which have been assigned to the assignee of this application and are hereby expressly incorporated herein by reference. Technical Field

[0003] This disclosure relates to wireless communication systems, and more specifically to techniques for adjusting the density and / or number of random access channels (RACH) timings for one of a plurality of available synchronization signal block (SSB) beams or a subset of SSB beams in order to accommodate overload and / or congestion.

[0004] background

[0005] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and Single Carrier Frequency Division Multiple Access (SC-FDMA) systems.

[0006] These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol enabling different wireless devices to communicate at the city, national, regional, and even global levels. For example, fifth-generation (5G) wireless communication technology (which may be referred to as New Radio (NR)) is designed to expand and support a diverse range of use cases and applications relative to current mobile network generations. In one aspect, 5G communication technologies can include: enhanced mobile broadband for human-centric use cases of accessing multimedia content, services, and data; ultra-reliable low latency communication (URLLC) with certain specifications regarding latency and reliability; and massive machine-type communication, which allows for a very large number of connected devices and the transmission of relatively small amounts of non-latency-sensitive information. However, with the continued growth in demand for mobile broadband access, further improvements to NR and ultra-NR communication technologies may be expected.

[0007] Overview

[0008] This disclosure provides techniques for adjusting the density and / or number of Random Access Channel (RACH) timings for one SSB beam or subset of SSB beams among multiple available Synchronization Signal Block (SSB) beams. To this end, features of this disclosure utilize beam-specific bit fields transmitted by the base station to the user equipment (UE), which indicate the RACH timing density for the SSB beam or subset of SSB beams. In some aspects, time and frequency resources for RACH timings with beam-specific alternative densities can be identified via resources for general RACH timings. Based on the adjusted RACH timing density, the UE can select one of these time and frequency resources to initiate access with the base station.

[0009] In one example, a method, apparatus (device), and non-transient computer-readable medium for wireless communication implemented by a base station are disclosed. The method may include configuring a first set of Synchronization Signal Block (SSB) beams at a base station to have a first Random Access Channel (RACH) timing density set, wherein the RACH timing density identifies time and frequency resources available to one or more User Equipment (UEs) to transmit an initial access request to the base station. The method may further include configuring a second set of SSB beams to have a second RACH timing density set. In some examples, the first RACH timing density set may be larger than the second RACH timing density set used for the second SSB beam set. The method may further include transmitting a system information message to one or more UEs including a beam-dependent bit field indicating the first RACH timing density set for the first SSB beam set and the second RACH timing density set for the second SSB beam set.

[0010] In one example, a method, apparatus (device), and non-transient computer-readable medium for wireless communication implemented by a UE are disclosed. The method may include receiving a system information message at the UE, including a beam-specific bit field indicating a RACH timing density for one of a plurality of SSB beams or a subset of SSB beams. The method may further include determining, in response to receiving the system information message, that a first set of SSB beams among the plurality of SSB beams is configured with a first RACH timing density set and a second set of SSB beams among the plurality of SSB beams is configured with a second RACH timing density set. In some examples, the first RACH timing density set may be larger than the second RACH timing density set used for the second SSB beam set. The method may further include selecting at least one RACH timing within the first or second SSB beam set. The method may further include transmitting an initial access message from the UE to a base station on time and frequency resources corresponding to the at least one RACH timing.

[0011] To achieve the foregoing and related objectives, these one or more aspects include the features fully described below and specifically pointed out in the claims. Certain illustrative features of these one or more aspects are set forth in detail in the following description and drawings. However, these features merely indicate a few of the various ways in which the principles of these various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. Brief description of the attached diagram

[0013] The disclosed aspects will now be described in conjunction with the accompanying drawings, which are provided for illustrative purposes and not for limiting the scope of the disclosure, wherein similar reference numerals denote similar elements, and wherein:

[0014] Figure 1 These are schematic diagrams illustrating examples of wireless communication systems according to various aspects of this disclosure;

[0015] Figure 2 This is a schematic diagram illustrating an example of RACH density or timing associated with an SSB beam or subset of SSB beams, based on various aspects of this disclosure.

[0016] Figure 3 These are schematic diagrams illustrating example implementations of various components of user equipment based on various aspects of this disclosure;

[0017] Figure 4 This is a flowchart illustrating an example of a wireless communication method implemented by a UE according to various aspects of this disclosure;

[0018] Figure 5 These are schematic diagrams illustrating example implementations of various components of a base station according to various aspects of this disclosure; and

[0019] Figure 6 This is a flowchart illustrating an example of a wireless communication method implemented by a base station according to various aspects of this disclosure.

[0020] Detailed description

[0021] One aspect of 5G NR communication technology involves the use of high-frequency bands (such as those above 24 GHz), often referred to as millimeter-wave (mmW) bands. These bands enable significant improvements in extremely high data rates and data processing capabilities. However, compared to LTE, mmW bands are susceptible to rapid channel variations and suffer from severe free-space path loss and atmospheric absorption. Furthermore, mmW bands are highly susceptible to obstruction (e.g., penetration by hands, heads, bodies, leaves, and buildings). Particularly at mmW frequencies, even minor environmental changes, such as head turns, hand movements, or passing cars, can alter the channel conditions between the base station (BS) and user equipment (UE), thus impacting communication performance.

[0022] Current mmW 5G NR systems utilize small wavelengths at higher frequencies in mmW to create highly directional beams using multiple-input multiple-output (MIMO) antenna arrays. These highly directional beams focus the transmitted radio frequency (RF) energy in an attempt to overcome propagation and path loss challenges in both uplink and downlink. Therefore, the UE can use several antenna ports associated with the antenna array (e.g., 1, 2, 4, or 8 antenna ports) to form beams in various directions using several analog weighting factors (e.g., antenna configuration). Similarly, the base station can use directional beams to transmit downlink signals.

[0023] When attempting to access the network, the UE may use beamforming technology to perform RACH transmission for Random Access Channel (RACH) messages. Such RACH procedures may include multiple RACH messages exchanged between the base station and the UE to establish a connection. Therefore, to facilitate communication between the base station and the UE, the base station may support multiple beams in different directions. For the purposes of this disclosure, the terms "Initial Access" or "RACH" procedures may refer to a series of processes between the UE and the base station to enable the UE to acquire synchronization and obtain a designated identifier (ID) for radio access communication.

[0024] Different beams in different directions may need to accommodate different network needs (e.g., better coverage for enhanced cell shape). Each beam in different directions may also indicate a different number of UEs. For example, a first beam in a first direction may communicate with a single UE, while a second beam may provide coverage for more than ten UEs. Therefore, the load balancing regarding the number of UEs supported by each beam may not be similar across multiple beams. This is especially true for scenarios where the base station supports one or more RedCap devices. Specifically, in some scenarios, several RedCap and / or Internet of Things (IoT) devices may also connect to the network. RedCap and / or IoT devices can be used in several scenarios, including wearable devices, industrial wireless sensors, and video surveillance. Some of these scenarios may involve stationary devices, and there may be a relatively large number of such devices located within a cell.

[0025] RedCap and IoT devices require a small form factor compared to traditional smartphones. For the purposes of this disclosure and unless explicitly specified, the terms "RedCap device" or "IoT device" may be used interchangeably with "UE". For stationary RedCap devices, the distribution of UEs within the base station coverage area can also result in some beams having significantly more UEs than other beams, leading to overload of one or more beams in certain directions.

[0026] Furthermore, multiple RedCap or IoT devices can connect to the same cell or beam, and therefore may need to access the network simultaneously (using RACH protocols), leading to RACH overload and congestion. For example, bike-sharing sets (e.g., services where bikes are available for short-term sharing by individuals and are “rented” or “lent” from docks throughout the city and returned to another dock belonging to the same system) can be implemented using RedCap or IoT devices. Thus, in scenarios where a large number of bikes parked in the same location (e.g., on a service file) are unlocked within a short period (e.g., during peak hours), each IoT device associated with each bike may need to send information to the network for accounting or tracking within that short period. Similarly, in other IoT applications that may include multiple co-located cameras or industrial sensors, each camera or sensor may be scheduled to upload data to the network at specific times, potentially overloading certain beams in the network.

[0027] However, in NR systems, the base station can identify the beam the UE is using to communicate with the base station by associating a Synchronization Signal Block (SSB) with a Physical Random Access Channel (RACH) timing beam. The term "RACH timing" can refer to resources in the time and / or frequency domains available for transmission of the PRACH preamble from the UE. In some respects, a single SSB beam can be associated with multiple RACH timings, or alternatively, multiple SSBs can be associated with a single RACH timing. By detecting the RACH timing selected by the UE for PRACH preamble transmission, the network can further identify the SSB beam the UE has selected for communication.

[0028] However, in current NR systems, the number of RACH opportunities (or alternatively, RACH density) for each beam is generally fixed for all beams in each direction. In other words, if a base station uses five beams in five different directions, each of those five beams can include the same number of RACH opportunities (e.g., three RACH opportunities), regardless of the number of UEs that can utilize one or more beams. Therefore, in instances where multiple RedCap or IoT devices need to simultaneously access the network (using RACH protocols) on a single beam or subset of beams, the limited number of RACH opportunities serving a large number of UEs in one direction can lead to RACH overload and / or congestion.

[0029] Various aspects of this disclosure address the aforementioned identification problem by implementing techniques for adjusting the density and / or number of RACH timings for one SSB beam or subset of SSB beams among multiple available SSB beams. To this end, features of this disclosure utilize beam-specific bit fields transmitted by the base station to the UE in the Residual Minimum System Information (RMSI), which can indicate the RACH timing density for an SSB beam or subset of SSB beams. In some aspects, time and frequency resources for RACH timings with beam-specific alternative densities can be identified via resources for general RACH timings.

[0030] Therefore, in cases where the base station detects overload of a beam or subset of beams, the base station can increase the number (or RACH density) of RACH opportunities for the potentially overloaded beams to allow more UEs to initiate RACH procedures without the risk of conflict or overload. However, for beams that are unlikely to be overloaded (e.g., beams serving a lower number of UEs), the number of RACH opportunities can remain the same as the original network settings. Thus, according to various aspects of this disclosure, the RACH opportunities associated with one or more SSB beams can be dynamically adjusted based on usage and the number of UEs served.

[0031] In some respects, the PRACH format and / or transmission type utilized by the UE (e.g., using repetition) may depend on the associated beam-specific RACH density configured by the network. For example, a UE that may use an SSB beam associated with a higher RACH timing density may use a shorter PRACH format compared to the conventional PRACH format. In other examples, a UE that may use an SSB beam associated with a higher RACH timing density may have the option of PRACH repetition on multiple RACH timings (e.g., using this option when the SSB-based RSRP is below a certain threshold). In some respects, the beam-specific PRACH format and / or transmission type may be indicated by the base station in the beam-specific portion of the RMSI along with the RACH timing density. The beam-specific PRACH format and / or transmission type may also be linked to the beam-specific RACH timing density (and / or the ratio of the beam-specific RACH timing density to the general RACH timing density) based on predefined standard specifications. It should be understood that various aspects of this disclosure may also be applicable depending on the frequency range, subcarrier spacing, and / or the number of SSB beams.

[0032] Now refer to Figure 1-5The various aspects are described in more detail below. Numerous specific details are set forth for illustrative purposes to provide a thorough understanding of one or more aspects. However, it is obvious that such aspects can be practiced without these specific details. Furthermore, as used herein, the term "component" can refer to one of the parts that make up a system, can be hardware, firmware, and / or software stored on a computer-readable medium, and can be divided into other components.

[0033] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the elements discussed without departing from the scope of this disclosure. Various procedures or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to some examples may be combined in other examples.

[0034] Figure 1 This is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also known as a wireless wide area network (WWAN)) may include base station 102, UE 104, evolved packet core (EPC) 160, and / or 5G core (5GC) 190. Base station 102 may include macrocells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macrocells may include base stations. Small cells may include femtocells, picocells, and microcells. In one example, base station 102 may also include gNB 180, as further described herein.

[0035] In one example, base station 102 may have modem 514 and communication management module 550 (see [link]). Figure 5 These features are used to adjust the density and / or number of RACH timings for one of the multiple available SSB beams or a subset of SSB beams. To this end, the features of this disclosure utilize beam-specific bit fields transmitted from the base station to the UE, which indicate the RACH timing density for the SSB beam or subset of SSB beams. In some aspects, time and frequency resources for RACH timings with beam-specific alternative densities can be identified via resources for general RACH timings. Based on the adjusted RACH timing density, the UE can select one of these time and frequency resources to initiate access with the base station.

[0036] In some respects, UE 104 may have modem 314 and initial access module 350 (see...) Figure 4These are used to receive RMSIs with beam-specific bit fields transmitted by the base station to identify the RACH timing density for the SSB beam or subset of the SSB beam. Furthermore, UE 104 can select one or more RACH timings to initiate a RACH procedure with base station 102.

[0037] Base station 102 can also be configured for 4G LTE (which may be collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)), and can interface with EPC 160 via backhaul link 132 (e.g., using the S1 interface). Base station 102 configured for 5G NR (which may be collectively referred to as Next Generation RAN (NG-RAN)) can interface with 5GC 190 via backhaul link 184. Among other functions, base station 102 can also perform one or more of the following functions: user data delivery, radio channel cryptography and cryptography decoding, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of Non-Access Stratum (NAS) messages, NAS node selection, synchronization, Radio Access Network (RAN) sharing, Multimedia Broadcast Multicast Service (MBMS), subscriber and equipment tracking, RAN Information Management (RIM), paging, location, and delivery of alarm messages. Base stations 102 can communicate directly or indirectly (e.g., via EPC 160 or 5GC 190) on backhaul link 134 (e.g., using an X2 interface). Backhaul link 134 can be wired or wireless.

[0038] Base station 102 can wirelessly communicate with one or more UEs 104. Each base station 102 can provide communication coverage for its respective geographical coverage area 110. Overlapping geographical coverage areas 110 may exist. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a Home Evolved B Node (eNB) (HeNB), which can provide services to a restricted group (which may be referred to as a Closed Subscriber Group (CSG)). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmission from base station 102 to UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technologies, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may use one or more carriers. For each carrier allocated in a total of up to Yx MHz (e.g., for x component carriers) used for transmission in the DL and / or UL directions, base station 102 / UE 104 may use a spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.). These carriers may or may not be adjacent to each other. Carrier allocation may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). Component carriers may include primary component carriers and one or more secondary component carriers. The primary component carrier may be referred to as the primary cell (PCell), and the secondary component carriers may be referred to as secondary cells (SCells).

[0039] In another example, some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as the Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Control Channel (PSCCH). D2D communication can be achieved through a wide variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0040] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communication to determine whether the channel is available.

[0041] Small cell 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, small cell 102' can employ NR and use the same 5 GHz unlicensed spectrum as that used by Wi-Fi AP 150. Small cell 102' employing NR in unlicensed spectrum can enhance access network coverage and / or increase access network capacity.

[0042] Whether it's a small cell 102' or a large cell (e.g., a macro base station), base station 102 can include an eNB, a gB node (gNB), or other types of base stations. Some base stations (such as gNB 180) can operate one or more frequency bands within the electromagnetic spectrum. The electromagnetic spectrum is typically subdivided into various classes, bands, channels, etc., based on frequency / wavelength. In 5G NR, two initial operating frequency bands have been identified as frequency range designations FR1 (410MHz–7.125GHz) and FR2 (24.25GHz–52.6GHz). The frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Although a portion of FR1 is greater than 6GHz, in various documents and articles, FR1 is often (interchangeably) referred to as the "sub-6GHz band." Similar naming issues sometimes arise regarding FR2. Although it differs from the Very High Frequency (EHF) band (30 GHz–300 GHz) which is designated as the “millimeter wave” (mmW) band by the International Telecommunication Union (ITU), FR2 is generally (interchangeably) referred to as the millimeter wave band in various documents and articles.

[0043] Considering the above aspects, unless otherwise stated, it should be understood that, as used herein, the term "sub-6GHz" and the like can broadly refer to frequencies less than 6GHz, within FR1, or including intermediate frequency band frequencies. Furthermore, unless otherwise stated, it should be understood that, as used herein, the term "millimeter wave" and the like can broadly refer to frequencies including intermediate frequency band frequencies, within FR2, or within the EHF band. However, communication using the mmW radio frequency band has extremely high path loss and short range. The mmW base station 180 can utilize beamforming 182 with the UE 104 to compensate for the high path loss and short range.

[0044] EPC 160 may include Mobility Management Entity (MME) 162, other MMEs 164, Serving Gateway 166, Multimedia Broadcast Multicast Service (MBMS) Gateway 168, Broadcast Multicast Service Center (BM-SC) 170, and Packet Data Network (PDN) Gateway 172. MME 162 may communicate with Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Service 176. IP Service 176 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services. The BM-SC 170 provides functionality for MBMS user service provisioning and delivery. The BM-SC 170 can serve as an entry point for content provider MBMS transmissions, authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and schedule MBMS transmissions. The MBMS gateway 168 can be used to distribute MBMS traffic to base station 102 within a Broadcast-Specific Service Single Frequency Network (MBSFN) area, and can be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0045] 5GC 190 may include Access and Mobility Management Functions (AMF) 192, other AMFs 193, Session Management Functions (SMF) 194, and User Plane Functions (UPF) 195. AMF 192 may communicate with Unified Data Management (UDM) 196. AMF 192 may be a control node handling signaling between UE 104 and 5GC 190. Generally, AMF 192 provides QoS streaming and session management. User Internet Protocol (IP) packets (e.g., from one or more UEs 104) may be transmitted via UPF 195. UPF 195 provides UE IP address allocation for one or more UEs, as well as other functions. UPF 195 connects to IP service 197. IP service 197 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services.

[0046] The base station may also be referred to as a gNB, B-node, evolved B-node (eNB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit / receive point (TRP), or any other suitable term. Base station 102 provides UE 104 with access to EPC 160 or 5GC 190. Examples of UE 104 include cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptop devices, personal digital assistants (PDAs), satellite radios, GPS devices, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet devices, smart devices, wearable devices, vehicles, electricity meters, gas pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other similar functional devices. Some UE 104 devices may be referred to as IoT devices (e.g., parking timers, oil pumps, ovens, vehicles, heart monitors, etc.). IoT UEs may include Machine Type Communication (MTC) / Enhanced MTC (eMTC, also known as Category (CAT)-M, Cat M1) UEs, NB-IoT (also known as CAT NB1) UEs, and other types of UEs. In this disclosure, eMTC and NB-IoT may refer to technologies that may evolve from or be based on these technologies. For example, eMTC may include FeMTC (Further eMTC), eFeMTC (Further Enhanced eMTC), mMTC (Massively Multi-Level MTC), etc., while NB-IoT may include eNB-IoT (Enhanced NB-IoT), FeNB-IoT (Further Enhanced NB-IoT), etc. UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, radio unit, remote unit, mobile device, radio device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, radio terminal, remote terminal, handheld device, user agent, mobile client, client, or some other suitable term.

[0047] Figure 2 This is a schematic diagram 200 illustrating an example of adjusting the RACH density or timing associated with an SSB beam or subset of SSB beams. Specifically, in some examples, the base station... As mentioned above, when attempting to access the network, the UE can use beamforming techniques to initiate access to the base station. Such RACH procedures may include multiple RACH messages exchanged between base station 102 and UE 104 to establish a connection. Thus, to facilitate communication between base station 102 and one or more UEs 104, base station 102 may support multiple beams in different directions (e.g., first beam 205 and second beam 210).

[0048] It may be necessary for each of the different beams (205, 210) in different directions to accommodate a different number of UEs. For example, the first beam 205 in the first direction may communicate with a single UE 104-a, while the second beam 210 may provide coverage for a second UE 104-b, a third UE 104-c, and a fourth UE 104-d. Therefore, the load balancing of the number of UEs 104 supported by each beam may not be similar across the multiple beams.

[0049] In some respects, a single SSB beam may be associated with multiple RACH timings, or alternatively, multiple SSBs may be associated with a single RACH timing. By detecting the RACH timing selected by UE 104 for PRACH preamble transmission, the network can then identify the SSB beam that the UE has selected for communication. However, in current NR systems, the number of RACH timings (or alternatively referred to as RACH density) for each beam is generally fixed for all beams in each direction. In other words, in the illustrated example, both the first beam 205 and the second beam 210 may include the same number of RACH timings (e.g., 2 RACH timings), regardless of the number of UEs that can utilize one or more beams. Therefore, in instances where multiple UEs 104 need to simultaneously access the network (using RACH protocols) on a single beam or subset of beams, a limited number of RACH timings serving a large number of UEs in one direction may lead to RACH overload and / or congestion.

[0050] This disclosure provides techniques for adjusting the density and / or number of RACH timings for one SSB beam or subset of SSB beams among multiple available SSB beams. To this end, features of this disclosure utilize beam-specific bit fields transmitted by base station 102 to UE 104 in the RMSI, which can indicate the RACH timing density for an SSB beam or subset of SSB beams. In some aspects, time and frequency resources for RACH timings with beam-specific alternative densities can be identified via resources for general RACH timings.

[0051] For example, in cases where base station 102 can detect overload of a beam or subset of beams (e.g., second beam 210), base station 102 can increase the number (or RACH density) of RACH opportunities for second beam 210 to allow more UEs (e.g., second UE 104-b, third UE 104-c, and fourth UE 104-d) to initiate RACH procedures without the risk of conflict or overload. However, for beams that may not be overloaded (e.g., first beam 205), the number of RACH opportunities can remain the same as the original network settings. Thus, according to various aspects of this disclosure, the RACH opportunities associated with one or more SSB beams can be dynamically adjusted based on usage and the number of UEs served.

[0052] In some aspects, the PRACH format and / or transmission type utilized by the UE (e.g., repetition) may depend on the associated beam-specific RACH density configured by the network. For example, UE 104 (e.g., second UE 104-b, third UE 104-c, and fourth UE 104-d) that can use an SSB beam associated with a higher RACH timing density can use a shorter PRACH format compared to a conventional PRACH format. In other examples, UE 104 (e.g., second UE 104-b, third UE 104-c, and fourth UE 104-d) that can use an SSB beam associated with a higher RACH timing density may have the option of PRACH repetition on multiple RACH timings (e.g., using this option when the SSB-based RSRP is below a certain threshold). In some aspects, the beam-specific PRACH format and / or transmission type may be indicated along with the RACH timing density in the beam-specific portion of the base station's RMSI. Beam-specific PRACH formats and / or transmission types can also be linked to beam-specific RACH timing densities (and / or the ratio of beam-specific RACH timing density to general RACH timing density) based on predefined standard specifications. It should be understood that aspects of this disclosure may also be applicable depending on the frequency range, subcarrier spacing, and / or the number of SSB beams.

[0053] Figure 3Hardware components and sub-components of an apparatus (which may be UE 104) for implementing one or more methods (e.g., method 400) described herein, according to various aspects of this disclosure, are explained. For example, an example implementation of UE 104 may include a wide variety of components, some of which have already been described above, but also components such as one or more processors 312, memory 316, and transceiver 302 communicating via one or more buses 344, which may operate in conjunction with the initial access module 350 to perform the functions described herein related to one or more methods (e.g., 400) including this disclosure. Specifically, the initial access module 350 may receive an RMSI with beam-specific bit fields transmitted by a base station to identify the RACH timing density for an SSB beam or subset of SSB beams. Furthermore, the initial access module 350 may select one or more RACH timings to initiate a RACH procedure with the base station 102.

[0054] One or more processors 312, modem 314, memory 316, transceiver 302, RF front end 388, and one or more antennas 365 may be configured to support voice and / or data calls (simultaneously or asynchronously) in one or more radio access technologies. In one aspect, the one or more processors 312 may include modem 314 using one or more modem processors. Various functions associated with the initial access module 350 may be included in modem 314 and / or processor 312, and in one aspect may be performed by a single processor, while in other aspects, different functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 312 may include any one or any combination of: a modem processor, or a baseband processor, or a digital signal processor, or a transmitter processor, or a receiver processor, or a transceiver processor associated with transceiver 302. In other aspects, some features of the one or more processors 312 and / or modem 314 associated with the initial access module 350 may be performed by transceiver 302.

[0055] Memory 316 may be configured to store data used herein and / or a local version of applications 375, or one or more of the initial access module 350 and / or its sub-components executed by at least one processor 312. Memory 316 may include any type of computer-readable medium that can be used by a computer or at least one processor 412, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In one aspect, for example, while UE 104 is operating at least one processor 312 to execute the initial access module 350 and / or one or more of its sub-components, memory 316 may be a non-transient computer-readable storage medium storing one or more computer-executable codes defining the initial access module 350 and / or one or more of its sub-components and / or data associated therewith.

[0056] Transceiver 402 may include at least one receiver 306 and at least one transmitter 308. Receiver 306 may include hardware, firmware, and / or processor-executable software code for receiving data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Receiver 306 may be, for example, a radio frequency (RF) receiver. In one aspect, receiver 306 may receive signals transmitted by at least one UE 104. Additionally, receiver 306 may process such received signals and may also obtain measurements of the signals, such as, but not limited to, Ec / Io, SNR, RSRP, RSSI, etc. Transmitter 308 may include hardware, firmware, and / or processor-executable software code for transmitting data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Suitable examples of transmitter 308 may include, but are not limited to, RF transmitters.

[0057] Furthermore, in one aspect, the transmitting device may include an RF front-end 388, which is communicatively operable with one or more antennas 365 and a transceiver 302 for receiving and transmitting radio transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by a UE 104. The RF front-end 388 may be connected to one or more antennas 365 and may include one or more low-noise amplifiers (LNAs) 390, one or more switches 392, one or more power amplifiers (PAs) 398, and one or more filters 396 for transmitting and receiving RF signals.

[0058] On one hand, the LNA 390 can amplify the received signal to a desired output level. On another hand, each LNA 390 can have specified minimum and maximum gain values. On yet another hand, the RF front end 388 can use one or more switches 392 to select a particular LNA 390 and its specified gain value based on the desired gain value for a particular application.

[0059] Furthermore, for example, one or more PAs 398 may be used by the RF front end 388 to amplify signals to obtain an RF output with a desired output power level. In one aspect, each PA 398 may have specified minimum and maximum gain values. In another aspect, the RF front end 388 may use one or more switches 392 to select a particular PA 398 and its specified gain value based on the desired gain value for a particular application.

[0060] Furthermore, for example, one or more filters 396 may be used by the RF front end 388 to filter the received signal to obtain the input RF signal. Similarly, in one aspect, for example, a corresponding filter 396 may be used to filter the output from a corresponding PA 398 to produce an output signal for transmission. In one aspect, each filter 396 may be connected to a specific LNA 390 and / or PA 398. In one aspect, the RF front end 388 may use one or more switches 392 to select the transmit or receive path using a specified filter 396, LNA 390, and / or PA 398 based on a configuration as specified by the transceiver 302 and / or processor 312.

[0061] Thus, transceiver 302 can be configured to transmit and receive wireless signals via RF front end 388 through one or more antennas 365. In one aspect, transceiver 302 can be tuned to operate at a specified frequency so that the transmitting device can, for example, communicate with one or more base stations 102 or one or more cells associated with one or more base stations 102 or other UE 104. In another aspect, for example, modem 314 can configure transceiver 302 to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by modem 314.

[0062] In one aspect, modem 314 may be a multi-band, multi-mode modem capable of processing digital data and communicating with transceiver 302 to enable the use of transceiver 302 to transmit and receive digital data. In another aspect, modem 314 may be multi-band and configured to support multiple frequency bands for a specific communication protocol. In another aspect, modem 314 may be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, modem 314 may control one or more components of the transmitting device (e.g., RF front-end 388, transceiver 302) to enable signal transmission and / or reception with the network based on a specified modem configuration. In one aspect, the modem configuration may be based on the mode and frequency band used by modem 314. In another aspect, the modem configuration may be based on UE configuration information associated with the transmitting device, such as information provided by the network during cell selection and / or cell reselection.

[0063] Reference Figure 4 Example method 400 for wireless communication according to various aspects of this disclosure can be found by reference. Figure 1 and 2 One or more UEs 104 are discussed for implementation. Although method 400 is described below with respect to the various elements of UE 104, other components may also be used to implement one or more of the steps described herein.

[0064] At block 405, method 400 may include receiving a system information message at the UE, which includes a beam-specific bit field indicating the RACH timing density of one SSB beam or subset of SSB beams among a plurality of SSB beams. In some examples, the system information message may be an RMSI message. The system information message may also include information relating to the format of a PRACH preamble message to be used by one or more UEs for initial access to a base station. In some examples, one or more UEs utilizing resources in a first RACH timing density set associated with a first SSB beam set may be configured to use a shorter format of the PRACH preamble message compared to one or more UEs utilizing resources in a second RACH timing density set associated with a second SSB beam set. In some aspects, one or more UEs utilizing resources in the first RACH timing density set associated with a first SSB beam set may be configured to repeatedly transmit the PRACH preamble message on multiple RACH timings. Aspects of block 405 may be derived from, as referenced Figure 3 The transceiver 302 and initial access component 350 described herein shall perform this action. Thus, the initial access component 350, transceiver 302, one or more antennas 365, modem 314, processor 312 and / or UE 104 or one of its sub-components may define means for receiving system information messages at the UE, the system information messages including beam-specific bit fields for indicating the RACH timing density of one of a plurality of SSB beams or a subset of SSB beams.

[0065] In block 410, method 400 may include determining, in response to receiving a system information message, that a first SSB beam set of a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set of the plurality of SSB beams is configured with a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set. Aspects of block 410 may be derived from, as referenced... Figure 3The initial access component 350 described herein shall be used to perform this action. Therefore, the initial access component 350, modem 314, processor 312, and / or UE 104 or any of its sub-components may be defined as means for determining, in response to receiving a system information message, that a first SSB beam set among a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set among the plurality of SSB beams is configured with a second RACH timing density set.

[0066] In block 415, method 400 may include selecting at least one RACH timing within a first SSB beamset or a second SSB beamset. Aspects of block 415 may be derived from, as referenced... Figure 3 The initial access component 350 described herein performs this action. Therefore, the initial access component 350, modem 314, processor 312, and / or UE 104 or any of its sub-components may define means for selecting at least one RACH timing within a first SSB beamset or a second SSB beamset.

[0067] In block 420, method 400 may include transmitting an initial access message from the UE to the base station on time and frequency resources corresponding to the at least one RACH timing. Aspects of block 420 may be derived as shown in reference to... Figure 3 The transceiver 302 and initial access component 350 described herein shall be used to perform this action. Thus, the initial access component 350, transceiver 302, one or more antennas 365, modem 314, processor 312 and / or UE 104 or one of its sub-components may be defined as means for transmitting an initial access message from the UE to the base station on time and frequency resources corresponding to the at least one RACH timing.

[0068] Figure 5The hardware components and sub-components of an apparatus (which may be base station 102) for implementing one or more methods (e.g., method 600) described herein, according to various aspects of this disclosure, are explained. For example, an example implementation of base station 102 may include a wide variety of components, some of which have already been described above, but also components such as one or more processors 512, memory 516, and transceiver 502 communicating via one or more buses 544, which may operate in conjunction with communication management component 550 to implement the functions described herein related to one or more methods (e.g., 600) including this disclosure. Specifically, communication management component 550 may adjust the density and / or number of RACH timings for one of a plurality of available SSB beams or a subset of SSB beams. To this end, communication management component 550 may utilize beam-specific bit fields transmitted from the base station to the UE, which may indicate the RACH timing density for the SSB beam or subset of SSB beams. In some respects, time and frequency resources for RACH timings with beam-dependent replacement densities can be identified via resources used for general RACH timings. Based on the adjusted RACH timing density, UE 104 can select one of these time and frequency resources to initiate access with the base station.

[0069] One or more processors 512, modem 514, memory 516, transceiver 502, RF front end 588, and one or more antennas 565 may be configured to support voice and / or data calls (simultaneously or not simultaneously) in one or more radio access technologies. In one aspect, the one or more processors 512 may include modem 514 using one or more modem processors. Various functions related to the communication management component 550 may be included in modem 514 and / or processor 512, and in one aspect may be performed by a single processor, while in other aspects, different functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 512 may include any one or any combination of: a modem processor, or a baseband processor, or a digital signal processor, or a transmitter processor, or a receiver processor, or a transceiver processor associated with transceiver 502. In other aspects, some features of the one or more processors 512 and / or modem 514 associated with the initial access module 350 may be performed by transceiver 502.

[0070] Memory 516 may be configured to store data used herein and / or a local version of applications 575, or one or more of a communication management component 550 and / or its sub-components executed by at least one processor 512. Memory 516 may include any type of computer-readable medium that can be used by a computer or at least one processor 512, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In one aspect, for example, when base station 102 is operating at least one processor 512 to execute communication management component 550 and / or one or more of its sub-components, memory 516 may be a non-transient computer-readable storage medium storing one or more computer-executable codes defining communication management component 550 and / or one or more of its sub-components and / or associated data.

[0071] Transceiver 502 may include at least one receiver 506 and at least one transmitter 508. Receiver 506 may include hardware, firmware, and / or processor-executable software code for receiving data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Receiver 506 may be, for example, a radio frequency (RF) receiver. In one aspect, receiver 506 may receive signals transmitted by at least one UE 104. Additionally, receiver 506 may process such received signals and may also obtain measurements of the signals, such as, but not limited to, Ec / Io, SNR, RSRP, RSSI, etc. Transmitter 508 may include hardware, firmware, and / or processor-executable software code for transmitting data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Suitable examples of transmitter 508 may include, but are not limited to, RF transmitters.

[0072] Furthermore, in one aspect, the transmitting device may include an RF front-end 588, which is communicatively operable with one or more antennas 565 and a transceiver 502 for receiving and transmitting radio transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by a UE 104. The RF front-end 588 may be connected to one or more antennas 365 and may include one or more low-noise amplifiers (LNAs) 590, one or more switches 592, one or more power amplifiers (PAs) 598, and one or more filters 596 for transmitting and receiving RF signals.

[0073] On one hand, the LNA 590 can amplify the received signal to a desired output level. On another hand, each LNA 590 can have specified minimum and maximum gain values. On yet another hand, the RF front end 588 can use one or more switches 592 to select a particular LNA 590 and its specified gain value based on the desired gain value for a particular application.

[0074] Furthermore, for example, one or more PAs 598 may be used by the RF front end 588 to amplify signals to obtain an RF output with a desired output power level. In one aspect, each PA 598 may have specified minimum and maximum gain values. In another aspect, the RF front end 588 may use one or more switches 592 to select a particular PA 598 and its specified gain value based on the desired gain value for a particular application.

[0075] Furthermore, for example, one or more filters 596 may be used by the RF front end 588 to filter the received signal to obtain the input RF signal. Similarly, in one aspect, for example, a corresponding filter 596 may be used to filter the output from a corresponding PA 598 to produce an output signal for transmission. In one aspect, each filter 596 may be connected to a specific LNA 590 and / or PA 598. In one aspect, the RF front end 588 may use one or more switches 592 to select the transmit or receive path using a specified filter 596, LNA 590, and / or PA 598 based on a configuration as specified by the transceiver 502 and / or processor 512.

[0076] Thus, transceiver 502 can be configured to transmit and receive wireless signals via RF front end 588 through one or more antennas 565. In one aspect, transceiver 502 can be tuned to operate at a specified frequency so that the transmitting device can, for example, communicate with one or more UEs 104. In another aspect, for example, modem 514 can configure transceiver 502 to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by modem 514.

[0077] In one aspect, modem 514 may be a multi-band, multi-mode modem capable of processing digital data and communicating with transceiver 502 to enable the use of transceiver 502 for transmitting and receiving digital data. In another aspect, modem 514 may be multi-band and configured to support multiple frequency bands for a specific communication protocol. In another aspect, modem 514 may be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, modem 514 may control one or more components of the transmitting device (e.g., RF front-end 588, transceiver 502) to enable signal transmission and / or reception with the network based on a specified modem configuration. In one aspect, the modem configuration may be based on the mode and frequency band used by modem 514. In another aspect, the modem configuration may be based on UE configuration information associated with the transmitting device, such as information provided by the network during cell selection and / or cell reselection.

[0078] Reference Figure 6Example method 600 for wireless communication according to various aspects of this disclosure can be found by reference. Figure 1 and 2 One or more base stations 102 are discussed for implementation. Although method 600 is described below with respect to the various elements of base station 102, other components may also be used to implement one or more of the steps described herein.

[0079] In block 605, method 600 may include configuring a first set of SSB beams among a plurality of SSB beams at a base station to have a first RACH timing density set, wherein the RACH timing density identifies time and frequency resources available for one or more UEs to transmit an initial access request to the base station. Aspects of block 605 may be derived from, as referenced Figure 5 The described communication management component 550 performs this function. Therefore, the communication management component 550, modem 514, processor 512, and / or base station or its sub-components may be defined as means for configuring a first SSB beam set of a plurality of SSB beams at the base station to have a first RACH timing density set.

[0080] In block 610, method 600 may include configuring a second SSB beam set among the plurality of SSB beams to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set. Aspects of block 610 may also be derived from, as referenced... Figure 5 The communication management component 550 described herein performs this function. Therefore, the communication management component 550, modem 514, processor 512, and / or base station or any of its sub-components may be defined as means for configuring a second SSB beam set among the plurality of SSB beams to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set.

[0081] In block 615, method 600 may include transmitting to one or more UEs a system information message including a beam-dependent bit field indicating a first RACH timing density set for a first SSB beam set and a second RACH timing density set for a second SSB beam set.

[0082] In some examples, the system information message further includes information regarding the format of the Physical Random Access Channel (PRACH) preamble message to be used by one or more UEs for initial access to the base station. In some examples, one or more UEs utilizing resources in a first RACH timing density set associated with a first SSB beam set may be configured to use a shorter format of the PRACH preamble message compared to one or more UEs utilizing resources in a second RACH timing density set associated with a second SSB beam set. In some aspects, one or more UEs utilizing resources in the first RACH timing density set associated with a first SSB beam set may be configured to repeatedly transmit the PRACH preamble message on multiple RACH timings. Aspects of block 615 may be derived from, as referenced... Figure 5 The transceiver 502, one or more antennas 565, and communication management component 550 described herein shall perform this function. Thus, the communication management component 550, transceiver 502, one or more antennas 565, modem 514, processor 512, and / or base station or one of its sub-components may define means for transmitting system information messages to one or more UEs, including beam-dependent bit fields indicating a first RACH timing density set for a first SSB beam set and a second RACH timing density set for a second SSB beam set.

[0083] In some examples, method 600 may further include receiving a PRACH preamble message from at least one UE on a RACH timing selected from a first RACH timing density set for a first SSB beam set or a second RACH timing density set for a second SSB beam set. The method may further include identifying the SSB beam utilized by the UE for PRACH preamble message transmission based on time and frequency resources associated with the selected RACH timing. The method may further include establishing communication with the UE on that SSB beam.

[0084] Some additional example terms

[0085] Examples of implementations are described in the following numbered clauses:

[0086] 1. A method for wireless communication, comprising:

[0087] At the base station, the first SSB beam set among multiple synchronization signal block (SSB) beams is configured to have a first random access channel (RACH) timing density set, wherein the RACH timing density identifies the time and frequency resources available for one or more user equipment (UE) to transmit an initial access request to the base station.

[0088] The second SSB beam set among the plurality of SSB beams is configured to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set; and

[0089] A system information message including a beam-dependent bit field is transmitted to one or more UEs, the beam-dependent bit field indicating a first RACH timing density set for a first SSB beam set and a second RACH timing density set for a second SSB beam set.

[0090] 2. The method as described in Clause 1 further includes:

[0091] Physical random access channel (PRACH) preamble messages are received from at least one UE on time and frequency resources selected from either a first RACH timing density set for a first SSB beam set or a second RACH timing density set for a second SSB beam set.

[0092] The SSB beam used by the UE for PRACH preamble message transmission is identified based on the time and frequency resources on which the PRACH preamble is received; and

[0093] Establish communication with the UE on this SSB beam.

[0094] 3. The method of Clause 1 or 2, wherein the system information message further includes information relating to the format of a Physical Random Access Channel (PRACH) preamble message to be used by one or more UEs for initial access to the base station.

[0095] 4. The method of any of the preceding clauses 1-3, wherein one or more UEs utilizing resources of the first RACH timing density set associated with the first SSB beam set are configured to utilize a shorter format PRACH preamble message compared to one or more UEs utilizing resources of the second RACH timing density set associated with the second SSB beam set.

[0096] 5. The method of any of the preceding clauses 1-4, wherein one or more UEs utilizing resources in the first RACH timing density set associated with the first SSB beam set are configured to repeatedly transmit PRACH preamble messages on multiple RACH timings.

[0097] 6. The method of any of the preceding clauses 1-5, wherein the system information message is the Residual Minimal System Information (RMSI).

[0098] 7. An apparatus for wireless communication, comprising:

[0099] At least one processor;

[0100] and a memory coupled to the at least one processor, the memory including instructions executable by the at least one processor to cause the device to:

[0101] At the base station, the first SSB beam set among multiple synchronization signal block (SSB) beams is configured to have a first random access channel (RACH) timing density set, wherein the RACH timing density identifies the time and frequency resources available for one or more user equipment (UE) to transmit an initial access request to the base station.

[0102] The second SSB beam set among the plurality of SSB beams is configured to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set; and

[0103] A system information message including a beam-dependent bit field is transmitted to one or more UEs, the beam-dependent bit field indicating a first RACH timing density set for a first SSB beam set and a second RACH timing density set for a second SSB beam set.

[0104] 8. The apparatus of clause 7, wherein these instructions are further executable by the at least one processor to cause the apparatus to:

[0105] Physical random access channel (PRACH) preamble messages are received from at least one UE on time and frequency resources selected from either a first RACH timing density set for a first SSB beam set or a second RACH timing density set for a second SSB beam set.

[0106] The SSB beam used by the UE for PRACH preamble message transmission is identified based on the time and frequency resources on which the PRACH preamble is received; and

[0107] Establish communication with the UE on this SSB beam.

[0108] 9. The apparatus of Clause 7 or 8, wherein the system information message further includes information relating to the format of a Physical Random Access Channel (PRACH) preamble message to be used by one or more UEs for initial access to a base station.

[0109] 10. An apparatus as described in any of the preceding clauses 7-9, wherein one or more UEs utilizing resources in a first RACH timing density set associated with a first SSB beam set are configured to utilize a shorter format PRACH preamble message compared to one or more UEs utilizing resources in a second RACH timing density set associated with a second SSB beam set.

[0110] 11. An apparatus as described in any of the preceding clauses 7-10, wherein one or more UEs utilizing resources in a first RACH timing density set associated with a first SSB beam set are configured to repeatedly transmit PRACH preamble messages on multiple RACH timings.

[0111] 12. The apparatus of any of the preceding clauses 7-11, wherein the system information message is the Residual Minimal System Information (RMSI).

[0112] 13. A method for wireless communication, comprising:

[0113] The system information message received at the user equipment (UE) includes a beam-specific bit field indicating the random access channel (RACH) timing density of one of the multiple synchronization signal block (SSB) beams or a subset of SSB beams.

[0114] In response to receiving a system information message, it is determined that a first SSB beam set among a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set among the plurality of SSB beams is configured with a second RACH timing density set, wherein the first RACH timing density set is greater than the second RACH timing density set used for the second SSB beam set.

[0115] Select at least one RACH timing within the first SSB beamset or the second SSB beamset; and

[0116] The UE transmits the initial access message to the base station on the time and frequency resources corresponding to the at least one RACH timing.

[0117] 14. The method of Clause 13, wherein the system information message further includes information relating to the format of a Physical Random Access Channel (PRACH) preamble message to be used by one or more UEs for initial access to a base station.

[0118] 15. The method of Clause 13 or 14, wherein transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing comprises:

[0119] Determine that the UE will transmit on resources in the first RACH timing density set associated with the first SSB beam set; and

[0120] A PRACH preamble message is generated, which has a shorter format than if the UE selects at least one RACH timing from the second RACH timing density set associated with the second SSB beam set.

[0121] 16. The method of any of the preceding clauses 13-15, wherein transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing comprises:

[0122] The PRACH preamble message is repeatedly transmitted on multiple RACH times within the first RACH time density set associated with the first SSB beam set.

[0123] 17. The method of any of the preceding clauses 13-17, wherein the system information message is the Residual Minimal System Information (RMSI).

[0124] 18. An apparatus for wireless communication, comprising:

[0125] At least one processor;

[0126] and a memory coupled to the at least one processor, the memory including instructions executable by the at least one processor to cause the device to:

[0127] The system information message received at the user equipment (UE) includes a beam-specific bit field indicating the random access channel (RACH) timing density of one of the multiple synchronization signal block (SSB) beams or a subset of SSB beams.

[0128] In response to receiving a system information message, it is determined that a first SSB beam set among a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set among the plurality of SSB beams is configured with a second RACH timing density set, wherein the first RACH timing density set is greater than the second RACH timing density set used for the second SSB beam set.

[0129] Select at least one RACH timing within the first SSB beamset or the second SSB beamset; and

[0130] The UE transmits the initial access message to the base station on the time and frequency resources corresponding to the at least one RACH timing.

[0131] 19. The apparatus of Clause 18, wherein the system information message further includes information relating to the format of a Physical Random Access Channel (PRACH) preamble message to be used by one or more UEs for initial access to a base station.

[0132] 20. The apparatus of clause 18 or 19, wherein the instructions for transmitting the initial access message on time and frequency resources corresponding to the at least one RACH timing can be further executed by the at least one processor to:

[0133] Determine that the UE will transmit on resources in the first RACH timing density set associated with the first SSB beam set; and

[0134] A PRACH preamble message is generated, which has a shorter format than if the UE selects at least one RACH timing from the second RACH timing density set associated with the second SSB beam set.

[0135] The detailed description above, in conjunction with the accompanying drawings, describes examples and does not represent only examples that can be implemented or fall within the scope of the claims. The term "example" as used in this description means "serving as an example, instance, or illustration," and not "superior to" or "better than other examples." This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0136] Information and signals can be represented using any of a wide variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which may be referred to throughout the above description, can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof.

[0137] The various explanatory frames and components described herein can be implemented or executed using specially programmed devices, such as, but not limited to, processors, digital signal processors (DSPs), ASICs, FPGAs, or other programmable logic devices designed to perform the functions described herein, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A specially programmed processor may be a microprocessor, but in alternatives, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially programmed processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0138] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a non-transient computer-readable medium. Other examples and implementations fall within the scope and spirit of this disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software, hardware, firmware, hardwired, or any combination thereof executed by a specially programmed processor. Features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented at different physical locations. Moreover, as used herein (including in the claims), the "or" used in a list of items followed by "at least one of" indicates a disjunctive enumeration, such that an enumeration such as "at least one of A, B, or C" represents A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0139] Computer-readable media includes both computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer. By way of example and not limitation, computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible to a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Similarly, any connection is also legitimately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then that coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used in this article, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs. Disks often magnetically reproduce data, while discs optically reproduce data using lasers. Combinations of these media are also included within the scope of computer-readable media.

[0140] The detailed description above, taken in conjunction with the accompanying drawings, is intended to describe various configurations and is not intended to represent the only configuration in which the concepts described herein can be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0141] Various apparatuses and methods are also described with reference to several aspects of the telecommunications system. These apparatuses and methods are described in detail and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0142] As an example, an element, or any part of an element, or any combination of elements, may be implemented as a "processing system" including one or more processors. Examples of processors include: microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system-on-a-chip (SoCs), baseband processors, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionalities described throughout this disclosure. One or more processors in a processing system can execute software. Software should be broadly interpreted as instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description languages, or other terms.

[0143] It should be noted that the techniques described herein can be used in various wireless communication networks, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. CDMA systems can implement radio technologies such as CDMA2000 and Universal Terrestrial Radio Access (UTRA). CDMA2000 encompasses the IS-2000, IS-95, and IS-856 standards. IS-2000 versions 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA systems can implement technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 902.11 (Wi-Fi), IEEE 902.16 (WiMAX), IEEE 902.20, and Flash-OFDM. TMRadio technologies such as UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-A Advanced (LTE-A) are new UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the Third Generation Partnership Project (3GPP). CDMA2000 and UMB are described in documents from an organization called the Third Generation Partnership Project 2 (3GPP2). The technologies described herein can be used with the systems and radio technologies mentioned above, as well as with other systems and radio technologies, including cellular (e.g., LTE) communications sharing a RF band. However, the following description describes LTE / LTE-A and / or 5G New Radio (NR) systems for illustrative purposes, and the terms LTE or 5G NR are used in most of the following description, but these technologies can also be applied beyond LTE / LTE-A and 5G NR applications (e.g., to other next-generation communication systems).

[0144] The prior description of this disclosure is provided to enable those skilled in the art to make or use it. Various modifications to this disclosure will readily be apparent to those skilled in the art, and the common principles defined herein can be applied to other variations without departing from the spirit or scope of this disclosure. Furthermore, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is also contemplated unless explicitly stated to be limited to the singular. Additionally, all or part of any aspect and / or embodiment may be used in conjunction with all or part of any other aspect and / or embodiment unless otherwise stated. Thus, this disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication, comprising: At the base station, the first SSB beam set of a plurality of synchronization signal block (SSB) beams is configured to have a first random access channel (RACH) timing density set, wherein the RACH timing density identifies the time and frequency resources that one or more user equipment (UE) can utilize to transmit an initial access request to the base station; The second SSB beam set among the plurality of SSB beams is configured to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set; as well as A system information message including beam-dependent bit fields is transmitted to the one or more UEs, the beam-dependent bit fields indicating the first RACH timing density set for the first SSB beam set and the second RACH timing density set for the second SSB beam set.

2. The method of claim 1, further comprising: Physical random access channel (PRACH) preamble messages are received from at least one UE on time and frequency resources selected from either the first RACH timing density set for the first SSB beam set or the second RACH timing density set for the second SSB beam set. The SSB beam used by the at least one UE to transmit the PRACH preamble is identified based on the time and frequency resources on which the PRACH preamble is received. as well as Communication is established with the UE on the SSB beam.

3. The method of claim 1, wherein the system information message further includes information relating to the format of the Physical Random Access Channel (PRACH) preamble message to be used by the one or more UEs for initial access to the base station.

4. The method of claim 3, wherein the one or more UEs utilizing resources of the first RACH timing density set associated with the first SSB beam set are configured to utilize a shorter format PRACH preamble message compared to the one or more UEs utilizing resources of the second RACH timing density set associated with the second SSB beam set.

5. The method of claim 3, wherein the one or more UEs utilizing resources in the first RACH timing density set associated with the first SSB beam set are configured to repeatedly transmit the PRACH preamble message on multiple RACH timings.

6. The method of claim 1, wherein the system information message is Residual Minimal System Information (RMSI).

7. An apparatus for wireless communication, comprising: One or more processors; and one or more memories coupled to the one or more processors, the one or more memories including, individually or in combination, instructions executable by the one or more processors to be configured such that the device: The first SSB beam set among multiple synchronization signal block (SSB) beams is configured to have a first random access channel (RACH) timing density set, wherein the RACH timing density identifies the time and frequency resources that one or more user equipment (UE) can utilize to transmit an initial access request to the base station; The second SSB beam set among the plurality of SSB beams is configured to have a second RACH timing density set, wherein the first RACH timing density set is larger than the second RACH timing density set used for the second SSB beam set; as well as A system information message including beam-dependent bit fields is transmitted to the one or more UEs, the beam-dependent bit fields indicating the first RACH timing density set for the first SSB beam set and the second RACH timing density set for the second SSB beam set.

8. The apparatus of claim 7, wherein the instructions are further executable by the one or more processors individually or in combination to be configured such that the apparatus: Physical random access channel (PRACH) preamble messages are received from at least one UE on time and frequency resources selected from either the first RACH timing density set for the first SSB beam set or the second RACH timing density set for the second SSB beam set. The SSB beam used by the UE to transmit the PRACH preamble is identified based on the time and frequency resources on which the PRACH preamble is received. as well as Communication is established with the UE on the SSB beam.

9. The apparatus of claim 7, wherein the system information message further includes information relating to the format of a Physical Random Access Channel (PRACH) preamble message to be used by the one or more UEs for initial access to the base station.

10. The apparatus of claim 9, wherein the one or more UEs utilizing resources of the first RACH timing density set associated with the first SSB beam set are configured to utilize a shorter format PRACH preamble message compared to the one or more UEs utilizing resources of the second RACH timing density set associated with the second SSB beam set.

11. The apparatus of claim 9, wherein the one or more UEs utilizing resources in the first RACH timing density set associated with the first SSB beam set are configured to repeatedly transmit the PRACH preamble message on multiple RACH timings.

12. The apparatus of claim 7, wherein the system information message is Residual Minimal System Information (RMSI).

13. A method for wireless communication, comprising: The system information message received at the user equipment (UE) includes a beam-specific bit field indicating the random access channel (RACH) timing density of one of the multiple synchronization signal block (SSB) beams or a subset of SSB beams. In response to receiving the system information message, it is determined that a first SSB beam set among a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set among the plurality of SSB beams is configured with a second RACH timing density set, wherein the first RACH timing density set is greater than the second RACH timing density set used for the second SSB beam set. Select at least one RACH timing within the first SSB beam set or the second SSB beam set; as well as The UE transmits an initial access message to the base station on time and frequency resources corresponding to the at least one RACH timing.

14. The method of claim 13, wherein the system information message further includes information relating to the format of the Physical Random Access Channel (PRACH) preamble message used by the UE for initial access to the base station.

15. The method of claim 13, wherein transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing comprises: It is determined that the UE will transmit on resources in the first RACH timing density set associated with the first SSB beam set; as well as A PRACH preamble message is generated, the format of which is shorter than that if the UE selects the at least one RACH timing from the second RACH timing density set associated with the second SSB beam set.

16. The method of claim 14, wherein transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing comprises: The PRACH preamble message is repeatedly transmitted on multiple RACH timings within the first RACH timing density set associated with the first SSB beam set.

17. The method of claim 13, wherein the system information message is Residual Minimal System Information (RMSI).

18. An apparatus for wireless communication, comprising: One or more processors; and one or more memories coupled to the one or more processors, the one or more memories including, individually or in combination, instructions executable by the one or more processors to be configured such that the device: Receive system information messages, the system information messages including beam-specific bit fields for indicating the random access channel (RACH) timing density of one SSB beam or subset of SSB beams among a plurality of synchronization signal block (SSB) beams; In response to receiving the system information message, it is determined that a first SSB beam set among a plurality of SSB beams is configured with a first RACH timing density set and a second SSB beam set among the plurality of SSB beams is configured with a second RACH timing density set, wherein the first RACH timing density set is greater than the second RACH timing density set used for the second SSB beam set. Select at least one RACH timing within the first SSB beam set or the second SSB beam set; as well as The initial access message is transmitted from the user equipment (UE) to the base station on the time and frequency resources corresponding to the at least one RACH timing.

19. The apparatus of claim 18, wherein the system information message further includes information relating to the format of the Physical Random Access Channel (PRACH) preamble message used by the UE for initial access to the base station.

20. The apparatus of claim 18, wherein the instructions for transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing can be further executed individually or in combination by the one or more processors to: It is determined that the UE will transmit on resources in the first RACH timing density set associated with the first SSB beam set; and A PRACH preamble message is generated, the format of which is shorter than that if the UE selects the at least one RACH timing from the second RACH timing density set associated with the second SSB beam set.

21. The apparatus of claim 19, wherein the instructions for transmitting the initial access message on the time and frequency resources corresponding to the at least one RACH timing can be further executed individually or in combination by the one or more processors to: The PRACH preamble message is repeatedly transmitted on multiple RACH timings within the first RACH timing density set associated with the first SSB beam set.

22. The apparatus of claim 18, wherein the system information message is Residual Minimal System Information (RMSI).

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