Beam scanning based random access MSG 3 and MSG 4

Abstract

A method, computer-readable medium, and apparatus for wireless communication including random access between a base station and a user equipment (UE) are provided. The UE sends a first random access message to a serving cell. The UE receives a second random access message from the serving cell in response to the first random access message. The UE may send a third random access message to one or more transmission reception points of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to provisional application serial number No. 63 / 003,224, filed on March 31, 2020, and entitled “BEAM SWEEP BASED RANDOMACCESS MSG 3AND MSG 4,” and U.S. patent application No. 17 / 214,641, filed on March 26, 2021, and entitled “BEAM SWEEP BASED RANDOM ACCESS MSG 3AND MSG 4,” the entire contents of which are expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to communication systems and, more particularly, to wireless communications including random access. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city, country, region, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution released by the Third Generation Partnership (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., together with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with the following: enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvements to 5GNR technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an extensive overview of all expected aspects, and is neither intended to identify the key or important elements of all aspects, nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0007] In one aspect of the present disclosure, a method for wireless communication at a user equipment (UE) is provided. The method includes: sending a first random access message to a serving cell; receiving a second random access message from the serving cell in response to the first random access message. The method also includes: sending a third random access message to one or more transmit receive point (TRP)s of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a transmit receive point (TRP) index. The method also includes: receiving an indication of a beam set for receiving a fourth random access message; and receiving the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0008] In another aspect of the present disclosure, a device for wireless communication at a UE is provided. The device includes: a unit for sending a first random access message to a serving cell. The device includes: a unit for receiving a second random access message in response to the first random access message from the serving cell. The device includes: a unit for sending a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index. The device also includes: a unit for receiving an indication of a beam set for receiving a fourth random access message, and receiving the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0009] In another aspect of the present disclosure, a device for wireless communication at a UE is provided. The device includes: a memory; and at least one processor coupled to the memory. The memory and the at least one processor are configured to: send a first random access message to a serving cell; receive a second random access message in response to the first random access message from the serving cell; and send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index. The memory and the at least one processor may also be configured to: receive an indication of a beam set for receiving a fourth random access message; and receive the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0010] In another aspect of the present disclosure, a non-transitory computer-readable storage medium storing computer-executable code for wireless communication at a UE is provided. When executed by a processor, the code causes the processor to perform the following operations: send a first random access message to a serving cell; receive a second random access message in response to the first random access message from the serving cell; and send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index. The code may also cause the processor to perform the following operations: receive an indication of a beam set for receiving a fourth random access message; and receive the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0011] In another aspect of the present disclosure, a method for wireless communication at a base station is provided. The method includes: receiving a first random access message from a UE; and sending a second random access message to the UE in response to the first random access message. The method includes: at one or more TRPs, receiving a third random access message on at least one of a plurality of beams being monitored in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index. The method may also include: sending an indication of a beam set for a fourth random access message; and sending the fourth random access message from the one or more TRPs on the beam set.

[0012] In another aspect of the present disclosure, a device for wireless communication at a base station is provided. The device includes: a unit for receiving a first random access message from a UE; and a unit for sending a second random access message to the UE in response to the first random access message. The device also includes: a unit for receiving a third random access message on at least one of a plurality of monitored beams in a beam scanning mode at one or more TRPs using resources based on a beam pool index or at least one of a TRP index. The device may also include: a unit for sending an indication of a beam set for a fourth random access message, and sending the fourth random access message from the one or more TRPs on the beam set.

[0013] In another aspect of the present disclosure, a device for wireless communication at a base station is provided. The device includes: a memory; and at least one processor coupled to the memory. The memory and the at least one processor are configured to: receive a first random access message from a UE; send a second random access message to the UE in response to the first random access message; and at one or more TRPs, receive a third random access message on at least one of a plurality of beams being monitored in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index. The memory and the at least one processor are configured to: send an indication of a beam set for a fourth random access message; and send the fourth random access message from the one or more TRPs on the beam set.

[0014] In another aspect of the present disclosure, a non-transitory computer-readable storage medium storing computer-executable code for wireless communication at a base station is provided. The code, when executed by a processor, causes the processor to perform the following operations: receiving a first random access message from a UE; sending a second random access message to the UE in response to the first random access message; and receiving a third random access message on at least one of the monitored multiple beams in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index at one or more TRPs. The code may also cause the processor to perform the following operations: sending an indication of a beam set for a fourth random access message; and sending the fourth random access message from the one or more TRPs on the beam set.

[0015] To accomplish the foregoing and related purposes, one or more aspects include features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of only some of the various ways in which the principles of the various aspects may be employed, and this specification is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram illustrating an example of a wireless communication system and an access network.

[0017] Figure 2A , 2B , 2C and 2D are schematic diagrams showing examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0018] Figure 3 is a schematic diagram showing an example of a base station and a UE in an access network.

[0019] Figure 4 The communication flow including the RACH process between the UE and the base station is shown.

[0020] Figure 5 An example of communication for a UE to perform random access with a primary secondary cell (PSCell) is shown.

[0021] Figure 6 An example of the use of beams in conjunction with random access is shown.

[0022] Fig. 7A and 7B Example aspects of random access between a UE and a cell having a single transmit receive point (TRP) using multiple beams in accordance with aspects of the present disclosure are shown.

[0023] Figure 8 Example aspects of random access between a UE and a cell having multiple TRPs using multiple beams in accordance with various aspects of the present disclosure are shown.

[0024] Fig. 9 Example aspects of random access between a UE and a cell having a single TRP using multiple beams in accordance with various aspects of the present disclosure are shown.

[0025] Fig.10 Example aspects of random access between a UE and a cell having multiple TRPs using multiple beams in accordance with various aspects of the present disclosure are shown.

[0026] Fig.11A ,11B and 11C illustrate example aspects of random access between a UE and a cell having multiple TRPs using multiple beams in accordance with various aspects of the present disclosure.

[0027] Fig. 12A and 12B Example aspects of random access between a UE and a cell having multiple TRPs using multiple beams in accordance with various aspects of the present disclosure are shown.

[0028] Fig.13 is a flow chart of a method of wireless communication according to aspects presented herein.

[0029] Fig.14 is a schematic diagram illustrating an example of a hardware implementation for an example apparatus according to aspects presented herein.

[0030] Fig.15 is a flow chart of a method of wireless communication according to aspects presented herein.

[0031] Fig.16 is a schematic diagram illustrating an example of a hardware implementation for an example apparatus according to aspects presented herein. DETAILED DESCRIPTION

[0032] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein may be practiced. For the purpose of providing a comprehensive understanding of each concept, the detailed description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some cases, well-known structures and components are shown in the form of block diagrams in order to avoid obscuring such concepts.

[0033] Several aspects of telecommunication systems will now be presented with reference to various devices and methods. These devices and methods will be described in the detailed description below and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may 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.

[0034] By way of example, an element, or any part of an element, or any combination of elements, can 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, systems on chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functions described throughout the present disclosure. One or more processors in a processing system can execute software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other names, software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0035] Accordingly, in one or more examples, the described functions can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored or encoded on a computer-readable medium as one or more instructions or codes. Computer-readable media include computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the aforementioned types, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0036] The aspects proposed herein improve reliability and reduce latency for the RACH process between the UE and the base station by transmitting one or more random access messages based on beam scanning. For example, the UE may send multiple third random access messages (e.g., Msg 3) on multiple beams based on beam scanning so as to be received at one or more beams of the base station or one or more beams of the TRP of the base station. Therefore, if the base station or the TRP of the base station is able to receive at least one of the third random access messages (e.g., Msg 3) at one of its beams, the RACH process may be able to continue. On the other hand, the base station may send multiple fourth random access messages (e.g., Msg 4) based on beam scanning. For example, the base station or the TRP of the base station may send multiple fourth random access messages to the UE on multiple beams based on beam scanning. Therefore, if the UE is able to receive at least one of the fourth random access messages at one of its beams, the RACH process may be completed even if no other fourth random access messages are received on other beams of the UE.

[0037] Figure 1 is a schematic diagram showing an example of a wireless communication system and access network 100 including a UE 104 and base stations 102, 180. The UE 104 may include a random access message component 199, which is configured to exchange random access messages with a cell using multiple beams (e.g., beam direction 182″). The base station 102 and / or 180 may include a random access message component 198, which is configured to exchange random access messages with the UE 104 using multiple beams (e.g., beam direction 182′). The random access message component 199 of the UE may be configured to send a third random access message using multiple transmit beams, for example, based on beam scanning information provided by the base station 102 / 180 in a second random access message (e.g., uplink grant). Additionally or alternatively, the random access message component 199 may be configured to receive a fourth random access from the base station 102 / 180 using a beam scanning mode.

[0038] Although the description below may focus on 5G NR, the concepts described herein may be applicable to other similar areas such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0039] The random access message component 198 of the base station 102 / 180 may be configured to receive a third random access message using multiple transmit beams. The random access message component 198 may be configured to provide beam scanning information to the UE, for example, in a second random access message (e.g., an uplink grant). Additionally or alternatively, the random access message component 198 may be configured to send a fourth random access to the UE 104 using a beam scanning mode.

[0040] Figure 1 The wireless communication system in may be referred to as a wireless wide area network (WWAN). The wireless communication system may include a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0041] The base station 102 configured for 4G LTE (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with the EPC 160 via a first backhaul link 132 (e.g., an S1 interface). The base station 102 configured for 5G NR (collectively referred to as the Next Generation RAN (NG-RAN)) can interface with the core network 190 via a second backhaul link 184. Among other functions, the base station 102 can also perform one or more of the following functions: transmission of user data, wireless channel encryption and decryption, 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), user and device tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) over a third backhaul link 134 (eg, an X2 interface). The third backhaul link 134 may be wired or wireless.

[0042] Base station 102 can communicate wirelessly with UE 104. Each base station 102 in base station 102 can provide communication coverage for a corresponding geographic coverage area 110. There can be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, which includes spatial multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. The base station 102 / UE 104 may use a spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may be adjacent to each other or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​than for UL). The component carrier may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

[0043] 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 a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0044] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

[0045] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may improve coverage and / or increase capacity of the access network.

[0046] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified with the frequency range names FR1 (410 MHz-7.125 GHz) and FR2 (24.25 GHz-52.6 GHz). It should be understood that although a portion of FR1 is greater than 6 GHz, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band in various documents and articles. Similar naming issues sometimes arise with respect to FR2, which is often (interchangeably) referred to as the "millimeter wave" band in documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz-300 GHz) identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0047] Frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands for these mid-band frequencies as the frequency range name FR3 (7.125GHz-24.25GHz). The frequency bands falling within FR3 can inherit FR1 characteristics and / or FR2 characteristics, and therefore the features of FR1 and / or FR2 can be effectively extended to mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations to more than 52.6GHz. For example, three higher operating bands have been identified as frequency range names FR4a or FR4-1 (52.6GHz-71GHz), FR4 (52.6GHz-114.25GHz) and FR5 (114.25GHz-300GHz). Each of these higher frequency bands falls within the EHF band.

[0048] In view of the above, unless otherwise specifically stated, it should be understood that if the term "sub-6 GHz" or the like is used herein, it can broadly refer to frequencies that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise specifically stated, it should be understood that if the term "millimeter wave" or the like is used herein, it can broadly refer to frequencies that can include mid-band frequencies, can be within FR2, FR4, FR4-a or FR4-1 and / or FR5, or can be within the EHF band.

[0049] The base station 102 (whether a small cell 102' or a large cell (e.g., a macro base station)) may include and / or be referred to as an eNB, a gNodeB (gNB), or another type of base station. Some base stations 180 (such as gNBs) may operate in traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with the UE 104. When a gNB (e.g., base station 180) operates in mmW or near mmW frequencies, the gNB may be referred to as a mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 mm and 10 mm. Radio waves in this band may be referred to as millimeter waves. Near mmW may extend down to frequencies of 3 GHz, which have a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz and is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands (e.g., 3 GHz-300 GHz) have extremely high path loss and short range. A mmW base station (e.g., base station 180) can utilize beamforming 182 with UE 104 to compensate for the extremely high path loss and short range. Base station 180 and UE 104 can each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming.

[0050] The base station 180 may transmit beamformed signals in one or more transmit directions 182' to the UE 104. The UE 104 may receive beamformed signals from the base station 180 in one or more receive directions 182". The UE 104 may also transmit beamformed signals to the base station 180 in one or more transmit directions. The base station 180 may receive beamformed signals from the UE 104 in one or more receive directions. The base station 180 / UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 / UE 104. The transmit direction and receive direction for the base station 180 may be the same or may be different. The transmit direction and receive direction for the UE 104 may be the same or may be different.

[0051] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. Typically, the MME 162 provides bearer and connection management. User Internet Protocol (IP) packets are transmitted through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides IP address allocation and other functions to the UE. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0052] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management unit (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Typically, the AMF 192 provides QoS flow and session management. User Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0053] A base station may include and / or be referred to as a gNB, a Node B, an eNB, an access point, a base transceiver, a wireless base station, a wireless transceiver, a transceiver functional unit, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other appropriate term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio unit, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet computer, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, an oven, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handheld device, a user agent, a mobile client, a client, or some other suitable terminology.

[0054] Figure 2A FIG200 is a diagram showing an example of a first subframe within a 5G NR frame structure. Figure 2B FIG230 is a diagram showing an example of DL channels within a 5G NR subframe. Figure 2C FIG250 is a diagram showing an example of a second subframe within a 5G NR frame structure. Figure 2D 280 is a diagram illustrating an example of UL channels within a 5G NR subframe. The 5G NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or the 5G NR frame structure may be TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , 2CIn the example provided, it is assumed that the 5G NR frame structure is TDD, where subframe 4 is configured with slot format 28 (mainly DL), where D is DL, U is UL, and X is flexibly used between DL / UL, and subframe 3 is configured with slot format 34 (mainly UL). Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe can be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and UL, respectively. Other slot formats 2-61 include a mixture of DL, UL and flexible symbols. The UE is configured with the slot format (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling) through the received slot format indicator (SFI). It should be noted that the description below also applies to the 5G NR frame structure as TDD.

[0055] Other wireless communication technologies may have different frame structures and / or different channels. A frame (e.g., 10ms) may be divided into subframes of the same size (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbol on the DL may be a cyclic prefix (CP) OFDM (CP-OFDM) symbol. The symbol on the UL may be a CP-OFDM symbol (for high throughput scenarios) or a discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbol (also referred to as a single carrier frequency division multiple access (SC-FDMA) symbol) (for power-limited scenarios; limited to single-stream transmission). The number of time slots in a subframe is based on the time slot configuration and numerology. For slot configuration 0, different digital schemes μ0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different digital schemes 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Therefore, for slot configuration 0 and digital scheme μ, there are 14 symbols / slot and 2 μ time slots / subframe. The subcarrier spacing and symbol length / duration are functions of the digital scheme. The subcarrier spacing can be equal to 2 μ *15kHz, where μ is digital scheme 0 to 5. As such, digital scheme μ=0 has a subcarrier spacing of 15kHz, and digital scheme μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is inversely proportional to the subcarrier spacing. Figures 2A-2DAn example is provided for slot configuration 0 with 14 symbols per slot and a digital scheme μ = 0 with 1 slot per subframe. The subcarrier spacing is 15 kHz and the symbol duration is approximately 66.67 μs.

[0056] A resource grid may be used to represent a frame structure. Each time slot may include a resource block (RB) (also referred to as a physical RB (PRB)) that extends 12 consecutive subcarriers. A resource grid may be divided into a plurality of resource elements (REs). The number of bits carried by each RE may depend on the modulation scheme.

[0057] like Figure 2A As shown, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) for channel estimation at the UE (for a specific configuration (where 100x is the port number), which is indicated as R x , but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0058] Figure 2B Examples of various DL channels within a subframe of a frame are shown. The physical downlink control channel (PDCCH) carries DCI in one or more control channel elements (CCEs), each CCE includes nine RE groups (REGs), and each REG includes four consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) can be within symbol 2 of a specific subframe of the frame. The PSS is used by UE 104 to determine the subframe / symbol timing and the physical layer identification. The secondary synchronization signal (SSS) can be within symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identification group number and the radio frame timing. Based on the physical layer identification and the physical layer cell identification group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth and the system frame number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information not sent through the PBCH (such as System Information Blocks (SIBs)), and paging messages.

[0059] like Figure 2CAs shown, some of the REs carry DM-RS for channel estimation at the base station (for a specific configuration, which is indicated as R, but other DMRS configurations are possible). The UE can send DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS can be sent in the first one or two symbols of the PUSCH. The PUCCH DM-RS can be sent in different configurations depending on whether a short PUCCH or a long PUCCH is sent and according to the specific PUCCH format used. The UE can send a sounding reference signal (SRS). The SRS can be sent in the last symbol of the subframe. The SRS can have a comb structure, and the UE can send the SRS on one of the combs. The SRS can be used by the base station for channel quality estimation to achieve frequency-dependent scheduling on the UL.

[0060] Figure 2D Examples of various UL channels within a subframe of a frame are shown. The PUCCH may be positioned as indicated in a configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and HARQ ACK / NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0061] Figure 33 is a block diagram of a base station 310 in an access network communicating with a UE 350. In the DL, IP packets from the EPC 160 may be provided to a controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functions. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides: RRC layer functions associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with header compression / decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with transmission of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), and MAC Demultiplexing of SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling and logical channel prioritization.

[0062] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 including the physical (PHY) layer may include error detection of the transmission channel, forward error correction (FEC) encoding / decoding of the transmission channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The coded and modulated symbols can then be divided into parallel streams. Each stream can then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time domain and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. Channel estimates may be derived from reference signals and / or channel condition feedback sent by the UE 350. Each spatial stream is then provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0063] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If multiple spatial streams are destined for the UE 350, the RX processor 356 can combine them into a single OFDM symbol stream. The RX processor 356 then uses a fast Fourier transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on the channel estimate calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by base station 310. The data and control signals are then provided to controller / processor 359, which implements layer 3 and layer 2 functions.

[0064] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0065] Similar to the functions described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides: RRC layer functions, which are associated with the following: system information (e.g., MIB, SIB) acquisition, RRC connection and measurement reporting; PDCP layer functions, which are associated with the following: header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions, which are associated with the following: transmission of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, re-segmentation of RLC data PDUs and reordering of RLC data PDUs; and MAC layer functions, which are associated with the following: mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling and logical channel prioritization.

[0066] Channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via respective transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

[0067] At the base station 310, the UL transmission is processed in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0068] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0069] At least one of the TX processor 368, the RX processor 356, and the controller / processor 359 may be configured to perform operations related to Figure 1 The random access message component 199 combines various aspects.

[0070] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to perform operations related to Figure 1 The random access message component 198 combines various aspects.

[0071] The UE may use a random access channel (RACH) procedure (which may also be referred to as a "random access procedure") to initiate communication with a base station, such as requesting an RRC connection, re-establishing an RRC connection, and / or resuming an RRC connection with a base station. Figure 4 4 is a communication flow 400 illustrating example aspects of a RACH procedure between a UE 402 and a base station 404. At 410, the UE 402 may initiate a random access message exchange (e.g., a RACH procedure) by sending a first random access message 412 (e.g., Msg 1) that may include a preamble to the base station 404. Prior to sending the first random access message 412, the UE may obtain random access parameters, such as preamble format parameters, time and frequency resources, parameters for determining a root sequence and / or cyclic shift for a random access preamble, etc., such as shown at 406, for example, in system information 408 sent / broadcasted from the base station 404. The preamble may be sent with an identifier, such as a random access RNTI (RA-RNTI). The UE 402 may randomly select a random access preamble sequence, for example, from a set of preamble sequences. In some examples, the preamble sequence may be assigned to the UE 402.

[0072] At 414, the base station may respond to the first random access message 412 by sending a second random access message 416 (e.g., Msg 2), wherein the second random access message 416 may be a PDSCH and / or PDCCH including a random access response (RAR). The RAR may include, for example, an identifier of a random access preamble sent by the UE, a timing advance (TA), an uplink grant for the UE to send data, a cell radio network temporary identifier (C-RNTI) or other identifier, and / or a backoff indicator. At 418, after receiving the second random access message 416, the UE 402 may send a third random access message 420 (e.g., Msg 3) to the base station 404, such as via a PUSCH, which may include an RRC connection request, an RRC connection re-establishment request, or an RRC connection recovery request, depending on the trigger used to initiate the RACH procedure. At 422, the base station 404 may complete the RACH process by sending a fourth random access message 424 (e.g., Msg 4) to the UE 402, wherein the fourth random access message may include a PDCCH for scheduling and a PDSCH for carrying messages. For example, the fourth random access message 424 may include a random access response message, which includes timing advance information, contention resolution information, and / or RRC connection setup information. The UE 402 may monitor the PDCCH in the fourth random access message 424, such as based on the C-RNTI. If the PDCCH is successfully received and decoded, the UE 402 may also decode the PDSCH corresponding to the PDCCH. The UE 402 may send HARQ feedback for any data carried in the fourth random access message. In some examples, the fourth random access message may be referred to as a contention resolution message. The fourth random access message 424 may complete the RACH process. Thus, the UE 402 may then send uplink communications and / or receive downlink communications with the base station 404 based on the RAR (e.g., from the second random access message 416) and the fourth random access message 424. Because four random access messages may be exchanged during a RACH procedure, the RACH procedure may also be referred to as a four-step RACH procedure.

[0073] Figure 5 5 is a communication flow 500 showing an example of a UE 502 performing a RACH procedure with a secondary cell, such as a primary secondary cell (PSCell) 506 (e.g., a secondary node (SN)), based on a configuration received from a primary cell (PCell) 504 (e.g., a primary node (MN)) serving the UE 502. Figure 5As shown, PCell 504 may send configuration 501 to UE 502, wherein configuration 501 may configure UE 502 to perform layer 3 (L3) measurements (e.g., beam measurements) on another cell such as PSCell 506. PSCell 506 may belong to a secondary cell group (SCG), wherein the SCG may include PSCell 506 and one or more secondary service cells (SSCells). Although the aspects presented herein are shown for PSCell, these aspects may also be applied to SCell. In some examples, UE 502 may use configuration 501 received from PCell 504 to measure synchronization signal blocks (SSBs) / physical broadcast channels (PBCHs) sent from PSCell 506. For example, UE 502 may perform synchronization signal measurements in a corresponding SS / PBCH block (or SSB-based) measurement time configuration (SMTC) window 503. SMTC window 503 may be configured by PCell 504, for example, via configuration 501. Examples of SS / PBCH blocks may be provided by Figure 2B 230. After UE 502 performs L3 measurement on the SSB of the PSCell, UE 502 may send a beam report 507 (e.g., an L3 beam report) including one or more beam measurements for PSCell 506 to PCell 504. UE 502 may provide beam report 507 to PCell 504 in response to event trigger 505. In one example, beam report 507 may be a periodic report, and UE 502 may provide beam report 507 to PCell 504 in a periodic manner.

[0074] After the PCell 504 receives the beam report 507 from the UE 502, the PCell 504 may initiate a PSCell add request procedure 509 for the UE 502 using the beam report 507 including the beam measurement for the PSCell 506, wherein the PCell 504 may send an RRC reconfiguration to the UE 502 511 to initiate the RRC reconfiguration for the UE 502. After the UE 502 completes the RRC reconfiguration, the UE 502 may send an RRC reconfiguration complete indication 515 to the PCell 504 indicating that the RRC reconfiguration has been completed. Then, the PCell 504 may also send an RRC reconfiguration complete indication 517 to the PSCell 506 to notify the PSCell 506 that the RRC reconfiguration has been completed for the UE 502. In one example, UE 502 may identify the best downlink beam (e.g., RS beam) for PSCell 506 based on measuring a reference signal (e.g., RS 513) transmitted from PSCell 506, and UE 502 may perform / initiate a RACH procedure 519 with PSCell 506 using the identified best downlink beam. For example, UE 502 may transmit a first random access message (e.g., Msg 1 412) to PSCell 506 during a corresponding RACH opportunity. After transmission of the first random access message, PSCell 506 and UE 502 may exchange a second random access message (e.g., 416), a third random access message (e.g., 420), and / or a fourth random access message (e.g., 424) for RACH procedure 519, such as in conjunction with Figure 4 In one example, one or more random access messages (e.g., second, third, and / or fourth random access messages) of the RACH process 519 may be exchanged between the UE 502 and the PSCell 506 using the same beam pair as the first random access message, and the random access message may include a combination of Figure 4 After completing the RACH procedure 519, the UE 502 and the PSCell 506 may transition to CSI-RS based beam refinement operation 521, wherein the UE 502 may measure the CSI-RS transmitted from different beams of the PSCell 506. The UE 502 may then provide a beam measurement report to the PSCell 506 for beam selection.

[0075] A UE with beam correspondence with a base station may obtain multi-beam diversity by sending multiple Msg 1 transmissions during a random access transmission, where each Msg 1 transmission may be sent using a different beam of the UE. Beam correspondence may refer to the ability of the UE to select a suitable beam for UL transmission based on DL measurements. Figure 6 600 is a diagram illustrating an example of multiple Msg 1 transmissions that may be performed by a UE within a RAR window 603 (e.g., during a portion 602 of the RAR window 603). The RAR window 603 may correspond to a time window in which the UE receives a RAR (e.g., Msg 2). The beams (e.g., 604a, 604b, and 604c) may correspond to different SSBs and / or different CSI-RS. As shown by Figure 6 As shown, beam correspondence can be configured between one or more UE beams (e.g., beams 608a, 608b, and 608c) and one or more base station beams (e.g., reference signals associated with one or more base station beams). For example, UE beam 608a can correspond to a reference signal associated with base station beam 604a, UE beam 608b can correspond to a reference signal associated with base station beam 604b, and UE beam 608c can correspond to a reference signal associated with base station beam 604c, and so on. Thus, the UE can send Msg 1 (e.g., a first random access message) multiple times using different beams (e.g., one or more Msg1s per UE beam). In one example, using beam correspondence, an uplink transmit beam can be the same as a downlink receive beam for the UE. In another example, the UE can perform uplink beam scanning, and then the UE can select one or more uplink transmit beams for Msg 1 beam scanning based at least in part on the uplink beam scanning. In some examples, a UE with beam correspondence may have full flexibility to use any uplink transmit beam (e.g., beams 608a, 608b, 608c) to transmit multiple Msg 1 random access transmissions corresponding to different SSB / CSI-RS. In other examples, RAR windows 603 may be interleaved for different transmit beams.

[0076] In one example, the UE may use portions of the RAR window 603 to monitor Msg 2 from the base station using different receive beams (e.g., beams 608a, 608b, 608c). The UE and the base station may be synchronized so that the base station determines beams that the UE may use to monitor Msg 2 within different portions 602 of the RAR window. For example, during a particular portion 602a of the RAR window 603, the base station may determine that the UE is using receive beam 608a corresponding to a reference signal associated with transmit beam 604a of the base station. Therefore, the base station may transmit Msg 2 using beam 604a during portion 602a. The base station may transmit multiple Msg 2s including RAR using different beams of the base station during different portions 602 of the RAR window 603.

[0077] Aspects presented herein may provide coverage and / or latency improvements between a UE and a cell, such as when the UE is being handed over from one cell to another, such as by Figure 5 As shown in 523. The aspects presented herein can increase the reliability of transmission between the UE and the cell by enabling multiple transmission opportunities in the time domain and / or frequency domain for uplink transmissions or channels (such as random access transmissions or RACH processes). Multiple (or additional) transmission opportunities can improve the reliability of communications (such as communications involving unlicensed spectrum) by increasing the likelihood of success of the RACH process between the UE and the base station (e.g., a secondary cell such as a PSCell). The increased reliability can be used to enhance or support services such as URLLC services, IoT services including industrial IoT (IIoT) services, NR-based communications in unlicensed spectrum (such as FR1) in a controlled environment, and the like. Aspects of the present disclosure can also increase random access reliability and robustness by using beam scanning during the RACH process between the UE and the cell (e.g., PCell, SCell, or PSCell, etc.).

[0078] In one aspect of the present disclosure, the UE may exchange one or more random access messages (e.g., Msg 1, Msg 2, Msg 3, and / or Msg 4, etc.) with the cell based on beam scanning, which is combined with Figure 6 to 12 described. In one example, beam scanning can be based on time division multiplexing (TDM), frequency division multiplexing (FDM), space division multiplexing (SDM), or a combination thereof, so that the UE can exchange one or more random access messages with a single transmit receive point (TRP) or with multiple TRPs of a serving cell. In another example, one or more candidate beam pools can be provided for the RACH process, wherein each beam pool can be associated with a beam pool index that can be used by the UE to avoid potential beam pairing misalignment, which may occur when the UE is communicating with one or more TRPs of a cell based on beam scanning. In addition, when the UE is communicating with one or more TRPs, each TRP can be associated with a TRP index or identifier that the UE can use to distinguish the TRPs. For example, when the random access process involves multiple TRPs, the beam pool index and / or the TRP index can enable the UE to select a random access beam with a large angle of departure (AoD) from different TRPs, which can improve uplink interference diversity. In some examples, applying beam scanning to one or more random access messages can provide load balancing between multiple TRPs. For example, based on beam scanning of one or more random access messages, the UE can select a TRP with less or no urgent traffic for communication. Applying beam scanning to random access messages (e.g., joint random access beam scanning) can also improve the rate of successfully completing the RACH process. For example, as long as one path among multiple transmissions of different random access message exchanges arrives (e.g., received by the UE and / or cell), the initial access or RACH process can be successfully completed. Beam scanning during random access can help avoid blocking during the initial access process with the cell. The added transmission of beam scanning can help avoid failures due to bursts of uplink or downlink inter-cell interference. For example, random access using beam scanning for one or more random access messages can reduce random access delays and provide a faster PSCell setup process with reduced failures or retransmissions.

[0079] Fig. 7A 7 is a diagram 700 illustrating an example of a RACH procedure between a UE 702 and one of the TRPs (eg, the first TRP 704) of a PSCell 706 according to aspects of the present disclosure. Optional aspects are shown with dashed lines. The RACH procedure may correspond to a combination of Figure 5 The RACH process described in 519 may also include the following: Figure 4The exchange of one or more random access messages described herein. In one example, the PSCell 706 can transmit a reference signal, such as a channel state information reference signal (CSI-RS), from the first TRP 704 based on beam scanning. For example, the first TRP 704 can use a different transmission beam to transmit each CSI-RS within a CSI-RS resource set, for example, the first TRP 704 can use a first beam to transmit a first CSI-RS resource (e.g., resource #1), use a second beam to transmit a second CSI-RS resource (e.g., resource #2), use a third beam to transmit a third CSI-RS resource (e.g., resource #3), and use an Nth beam to transmit an Nth CSI-RS resource (e.g., resource #N), etc. For example, as described by Fig. 7A As shown in schematic diagram 700, the first TRP 704 may use different beams (e.g., sixty-six beams corresponding to sixty-six CRI-RS resources) to send CSI-RS using CSI-RS resources one (1) to sixty-six (66). Based on the CSI-RS sent from different beams of the first TRP 704, the UE 702 may send multiple Msg 1s (e.g., corresponding to a first random access message of 412 including a preamble) to one or more beams (e.g., a receive beam) of the first TRP 704. For example, the UE 702 may use a number X of selected reference signals (e.g., CSI-RS) received from the first TRP 704 on X allocated random access opportunities, where the allocated random access opportunities may correspond to the X reference signals of the first TRP 704.

[0080] In some examples, UE 702 may send multiple Msg 1s based on TDM, FDM, SDM, or a combination thereof. Fig. 7A As shown in the schematic diagram 700 of FIG. 7 , UE 702 may send multiple Msg 1s based on TDM, wherein UE 702 may send multiple Msg 1s at different time periods and optionally using different beams. For example, UE 702 may send Msg 1 (e.g., 711) at a first time period (e.g., time period 1) using beam n, and send another Msg 1 (e.g., 713) at a second time period (e.g., time period 2) using beam m, and so on. As shown by Figure 7B As shown in the schematic diagram 750, UE 702 can send multiple Msg 1 based on FDM, wherein UE 702 can use the same time resources but different frequency resources to send multiple Msg 1. For example, the first Msg1 transmission 715 and the second Msg1 transmission 717 can overlap in time, but use different frequency resources (for example, use different frequency bands) to send.

[0081] although Fig. 7A The examples of the reference signal are shown as CSI-RS, but the aspects presented herein can be applied to other types of reference signals, such as synchronization signals (e.g., SSB) transmitted from a base station using different beams. In addition, although the reference signal can be sent from a single TRP and the Msg 1 transmission from the UE can be received at a single TRP, the aspects presented herein can also be applied to multiple TRPs. In addition, although Fig. 7A The aspects of the schematic diagram 700 of FIG. 700 are described in conjunction with the PSCell 706, but the UE 702 can similarly perform a random access procedure with the PCell 707 or SCell based on beam scanning. Figure 5 As described, PCell 707 may provide random access configuration to UE 702 .

[0082] In some examples, the UE may use the selected beam pair to send each of the multiple Msg 1s. For example, referring back to Fig. 7A , UE 702 may use a selected beam pair (e.g., the selected beam pair may include a transmit beam of the UE and a receive beam of the base station) to send Msg 1 (e.g., 711), and UE 702 may use a different beam pair to send another Msg 1 (e.g., 713). In other words, the UE may use a transmit beam corresponding to CSI-RS beam n to send a first Msg 1 (e.g., 711), and the UE may also use CSI-RS beam m to send a second Msg 1 (e.g., 713), and so on.

[0083] Figure 8 8 is a diagram 800 illustrating an example of a RACH procedure involving multiple TRPs in accordance with aspects of the present disclosure. Optional aspects are illustrated with dashed lines. The PSCell may include a first TRP 806 (e.g., TRP i) and a second TRP 808 (e.g., TRP j). The RACH procedure involving multiple TRPs may correspond to a combination of Figure 5 The RACH process 519 described above and the RACH process may include the following: Figure 4 The RACH process involving multiple TRPs may include the combination of Fig. 7A and 7B Similar aspects are described for the RACH process involving a single TRP. However, for the RACH process involving multiple TRPs, the PSCell (e.g., 804) can send multiple reference signals (e.g., CSI-RS) to the UE through multiple TRPs, and the UE can send multiple Msg 1s to different TRPs of the PSCell.

[0084] For example, as shown by diagram 800, the first TRP 806 may transmit multiple CSI-RSs from different transmit beams of the first TRP 806 using different CSI-RS resources (e.g., resources #51-54 and #63-66), for example, the first TRP 806 may transmit a first CSI-RS from a first beam of the first TRP 806 using a first CSI-RS resource (e.g., resource #51), transmit a second CSI-RS from a second beam of the first TRP 806 using a second CSI-RS resource (e.g., resource #52), transmit a third CSI-RS from a third beam of the first TRP 806 using a third CSI-RS resource (e.g., resource #53), and so on. In one example, the beam used to transmit the CSI-RS may be selected from a beam pool associated with the first TRP 806 (e.g., RACH candidate beam pool i). Similarly, the second TRP 808 may also transmit multiple CSI-RSs from different transmit beams of the second TRP using different CSI-RS resources (e.g., resources #1-4 and #13-16), for example, the second TRP 808 may transmit a first CSI-RS from a first beam of the second TRP 808 using a first CSI-RS resource (e.g., resource #1), transmit a second CSI-RS from a second beam of the second TRP 808 using a second CSI-RS resource (e.g., resource #2), transmit a third CSI-RS from a third beam of the second TRP 808 using a third CSI-RS resource (e.g., resource #3), and so on. Similarly, the beam used to transmit the CSI-RS may be selected from a beam pool (e.g., RACH candidate beam pool j) associated with the second TRP 808. In some examples, a beam pool associated with one TRP of a PSCell may not overlap with a beam pool associated with another TRP of the PSCell. For example, beams within RACH candidate beam pool i associated with the first TRP 806 of PSCell 804 may be configured to not overlap with beams within RACH candidate beam pool j associated with the second TRP 808 of PSCell 804.

[0085] Based on the CSI-RS transmitted from one or more beams of the first TRP 806 and the CSI-RS transmitted from one or more beams of the second TRP 808, the UE 802 may transmit multiple Msg 1s (e.g., corresponding to the first random access message 412 that may include a preamble) to one or more beams (e.g., receiving beams) of the first TRP 806 and one or more beams of the second TRP 808. For example, the UE 802 may transmit a first Msg 1 (e.g., 811) to the first TRP 806, and the UE 802 may transmit a second Msg 1 (e.g., 813) to the second TRP 808.

[0086] In some examples, the receive beam of the PSCell may be from different random access resource candidate beam pools of the serving cell that may correspond to FDM or TDM random access resources. For example, since the second TRP 808 may be associated with random access candidate beam pool j, the second TRP 808 may use the receive beam selected from the random access candidate beam pool j for random access. Similarly, since the first TRP 806 may be associated with random access candidate beam pool i, the first TRP 806 may use the receive beam selected from the random access candidate beam pool i for the random access process. In other examples, a single TRP may be associated with multiple beam pools, where different beam pools may be used for different random access resources. An index (e.g., a beam index) associated with a reference signal sent from a cell or a TRP of the cell may be provided to the UE. In addition, each TRP may be associated with a TRP index. Thus, when the UE receives a reference signal from a cell or TRP during a RACH process, the UE may determine the beam of the cell or TRP corresponding to the received reference signal and / or the beam pool associated with the cell or TRP corresponding to the received reference signal based on the beam pool index and / or the TRP index. In some examples, the TRP may have up to sixty-four (64) beams, which may be separated / grouped into different beam pools for random access. For example, the first eight (8) beams of a TRP (e.g., TRP index = 0) may be associated with a first beam pool index (e.g., pool index #1), the next eight beams of the TRP may be associated with a second beam pool index (e.g., pool index #2), and so on, where the last eight beams of the TRP are associated with an eighth beam pool index (e.g., pool index #8). In such an example, the UE may select a beam within the beam pool index to send Msg 1. By configuring / assigning beam pool indices for beams of a single TRP or multiple TRPs, beam pairing misalignment between UE and TRP can be avoided.

[0087] Fig. 9 9 is a diagram illustrating an example of beam pair misalignment that may occur during a RACH procedure involving beam scanning. The RACH procedure may include combining Fig. 7A , 7Band 8. In one example, after PSCell 906 transmits multiple CSI-RS from multiple beams of PSCell 906, UE 902 may transmit multiple Msg 1 to one or more beams of PSCell 906 based at least in part on the CSI-RS. For example, UE 902 may use a first UE beam 905 to transmit a first Msg 1 (e.g., 911) to beam 903 of PSCell 906, and UE 902 may use a second UE beam 909 to transmit a second Msg 1 (e.g., 913) to beam 905 of PSCell 906. However, PSCell 906 may receive the second Msg 1 (e.g., 913) at beam 907, but may not receive the first Msg 1 (e.g., 911) at beam 903. Since the PSCell 906 may not have received the first Msg 1 (e.g., 911), the PSCell 906 may transmit the Msg 2 PDCCH 915 during the RACH process using a beam or beam pair (e.g., beam 907) corresponding to the reception of the second Msg 1 (e.g., 913). However, as shown at 920, the UE 902 may monitor the Msg 2 PDCCH (e.g., for the first Msg 1) using beam 905 (i.e., the beam used to transmit the first Msg 1). This may result in misaligned beam pairing because the UE 902 may be expecting to receive the Msg 2 PDCCH 915 from beam 903 of the PSCell 906, but the PSCell is transmitting the Msg 2 PDCCH 915 using beam 907. Then, at 922, UE 902 may be monitoring Msg 2 PDCCH (e.g., for the second Msg 1) using beam 909 (i.e., the beam used to transmit the second Msg 1). However, when PSCell 906 receives one Msg 1 (e.g., 913) from UE 902, PSCell 906 may transmit one Msg 2 PDCCH at 920 and may not transmit another Msg 2 PDCCH at 922. Therefore, UE 902 may not receive another Msg 2 PDCCH at 922. Therefore, the unsuccessful transmission of the first Msg 1 (e.g., 911) may result in a misalignment between the beam used by PSCell 906 to transmit Msg 2 PDCCH and the beam used by UE 902 to receive Msg 2 PDCCH 915.

[0088] Fig.101000 is a diagram illustrating an example of using beam pool indexes to avoid beam pairing misalignment according to various aspects of the present disclosure. Optional aspects are illustrated with dashed lines. UE 1002 may initiate a RACH procedure via a first TRP 1006 and a second TRP 1008 of PSCell 1004, wherein the first TRP 1006 may be associated with a first RACH candidate beam pool (e.g., beam pool i) and a first TRP index (e.g., TRP index=0), and the second TRP 1006 may be associated with a second RACH candidate beam pool (e.g., beam pool j) and a second TRP index (e.g., TRP index=1). The RACH procedure may include incorporating Figure 7A-9 In one example, UE 1002 may send a first Msg 1 (e.g., 1011) to a first TRP 1006, and a second Msg 1 (e.g., 1013) to a second TRP 1008. The first Msg 1 from UE 1002 may not be received by the first TRP 1006, while the second Msg 1 may be received by the second TRP 1008. Since the first Msg 1 is not received by the first TRP 1006, the PSCell 1004 may not send a Msg 2 PDCCH in response to the first Msg 1. However, as shown at 1020, random access resources (e.g., resources selected from the first RACH candidate beam pool (e.g., beam pool i)) may be reserved by the PSCell 1004 for sending the Msg 2PDCCH 1017 from the first TRP 1006 to the UE 1002 in response to the first message 1 (e.g., 1011). Therefore, the PSCell 1004 may skip sending the Msg 2PDCCH 1017 from the first TRP 1006 when the random access resources are reserved. Then, as shown at 1022, the PSCell 1004 may transmit a Msg 2 PDCCH 1015 from the second TRP 1008 using a beam selected from the second RACH candidate beam pool (e.g., beam pool j) in response to the second Msg 1 (e.g., 1013), wherein the UE 1002 may monitor the Msg 2 PDCCH 1015 using the beam that transmits the second Msg 1. Therefore, the beam pair used by the UE 1002 to receive the Msg 2 PDCCH 1015 may be aligned with the beam pair used by the UE to transmit the second Msg 1, so that the UE 1002 may receive the Msg 2 PDCCH 1015 using the beam that transmits the second Msg 1.

[0089] Aspects presented herein may enable a UE to send multiple Msg 3s using beam scanning and / or enable a cell or a TRP of a cell to send multiple Msg 4s using beam scanning to improve the reliability and robustness of random access communications. For example, a UE may send multiple Msg 3 RRC connection requests to a cell or one or more TRPs of a cell using beam scanning and based on TDM, SDM, FDM, or a combination thereof. The UE may use the uplink resources granted by the cell in Msg 2 to send multiple Msg 3s, such as in combination with Figure 9-1 1. In some examples, the cell may include information related to beam scanning in each of the transmitted Msg 2, such as the beam used by the cell and / or each TRP to send the random access message. Thus, as long as one of the Msg 2 is successfully received by the UE, the UE may apply beam scanning to multiple Msg 3 transmissions based at least in part on the received beam scanning information. Similarly, the cell may send multiple Msg 4 based on beam scanning in response to the Msg 3 received from the UE.

[0090] Depend on Fig.11A , Fig. 11B and Fig. 11C FIG. 11 is a diagram 1100 showing an example of a RACH process involving sending multiple Msg3 (e.g., from a UE) and multiple Msg4 (multiple TRPs from a cell) according to various aspects of the present disclosure. The RACH process described herein may include combining Figure 7A-10 Aspects of any of the examples described in the examples and may include joint random access message transmission that may improve reliability and robustness of random access communications.

[0091] As shown at 1112, UE 1102 may initiate a RACH procedure with a first TRP 1106 and a second TRP 1108 of PSCell 1104, wherein the first TRP 1106 may be associated with a first RACH candidate beam pool 1007 (e.g., beam pool i) and a first TRP index (e.g., TRP index=0), and the second TRP 1108 may be associated with a second RACH candidate beam pool 1009 (e.g., beam pool j) and a second TRP index (e.g., TRP index=1). The RACH procedure may include incorporating Figure 7A-10 Any aspect of the example description in the examples.

[0092] As combined Figure 8As described, each TRP may transmit one or more reference signals from one or more beams of the TRP, wherein one reference signal may correspond to one beam of the TRP. For example, as shown at 1112, the first TRP 1106 may transmit multiple CSI-RS from one or more beams 1116 of the first TRP 1106 using different CSI-RS resources (e.g., resources #51-54 and #63-66), wherein the one or more beams 1116 may be selected from the first RACH candidate beam pool 1007. Similarly, the second TRP 1108 may transmit multiple CSI-RS from one or more beams 1114 of the second TRP 1108 using different CSI-RS resources (e.g., resources #1-4 and #13-16), wherein the one or more beams 1114 may be selected from the second RACH candidate beam pool 1009. In some examples, the candidate beams in the first RACH candidate beam pool 1007 may be configured to not overlap with the candidate beams in the second RACH candidate beam pool 1009 .

[0093] At 1118, after UE 1102 receives one or more CSI-RS transmitted from the first TRP 1106 and / or the second TRP 1108, the UE may transmit a plurality of Msg1s to the first TRP 1106 and / or the second TRP 1108 based on beam scanning, such as in combination with Figures 8 to 10Described. UE 1102 can determine which beam(s) is used by the TRP to send CSI-RS and / or which TRP sends CSI-RS based on the pool index and / or TRP index associated with the TRP. In one example, UE 1102 can use a first UE beam to send a first Msg 1 to beam n of a first TRP 1106, and UE 1102 can use a second UE beam to send a second Msg 1 to beam m of a second TRP 1108, and so on. Each Msg 1 in Msg 1 may include information related to the beam (e.g., a first UE beam and a second UE beam) used by UE 1102 to send Msg 1. Therefore, as long as one Msg 1 is successfully received by PSCell 1104 or one of the TRPs of PSCell 1104, PSCell 1104 can know the beam pair used by UE 1102 to send Msg1 (for example, the first UE beam pair with beam n of the first TRP, the second UE beam pair with beam m of the second TRP, and so on). For example, if the first Msg 1 from UE 1102 is not received by the first TRP 1106, but the second Msg 1 is received by the second TRP 1108, PSCell 1104 can still know the beam pair used by UE 1102, and PSCell 1104 can send multiple Msg2PDCCH / PDSCH to UE 1102 based on the beam pair to avoid beam pair misalignment. Although Fig.11A The example in FIG. 1 shows that UE 1102 sends Msg 1 to one beam of each TRP, but UE 1102 can also use different UE beams to send multiple Msg 1 to multiple receive beams of a TRP, such as in combination with Fig. 7A as described.

[0094] After PSCell 1104 receives Msg 1 from UE 1102 (such as at beam m of second TRP 1108), PSCell 1104 may respond to UE 1102 with multiple Msg 2 based on beam scanning. Fig.11A As shown at 1120 of , PSCell 1104 can send Msg 2PDCCH 1111 and Msg 2PDSCH 1115 from beam n of first TRP 1106 to first UE beam, and PSCell 1104 can send Msg 2PDCCH 1113 and Msg 2PDSCH 1117 from beam m of second TRP 1108 to second UE beam. In some examples, PSCell 1104 can use a single TRP to communicate with UE 1102 (e.g., as shown in FIG. 1120 ). Fig. 7A and 9), or PSCell 1104 may use multiple TRPs to communicate with the UE (as shown in Fig.10 and 11). Although Figure 9-1 1 shows beam scanning and / or transmission of a random access message based on TDM, but beam scanning of a random access message may be performed using TDM, SDM, FDM, or a combination thereof. In addition, a Msg 2PDSCH (e.g., 1115, 1117) may be transmitted using a beam corresponding to an Msg 2PDCCH that schedules a PDSCH. For example, a beam used by the first TRP 1106 to transmit an Msg 2PDSCH 1115 may be the same as a beam used by the first TRP to transmit an Msg 2PDCCH 1111 that schedules an Msg 2PDSCH 1115 (e.g., both use beam n). In another example, an Msg 2PDSCH may be transmitted using a beam different from that of an Msg 2PDSCH that schedules an Msg 2PDSCH.

[0095] Msg 2PDCCH may carry resource allocation information and / or beam scanning related information for multiple Msg 2PDSCHs. Therefore, if one of the Msg 2PDCCHs is not received, the UE may still receive the Msg 2PDSCH because the UE 1102 may be able to determine the corresponding resources from different Msg 2PDCCHs. For example, return to reference Fig.11A , if Msg 2PDCCH 1111 from the first TRP 1106 is not received by UE 1102 and Msg 2PDCCH 1113 from the second TRP 1108 is received by UE 1102, UE 1102 may still be able to receive both Msg 2PDSCH 1113 and Msg 2PDSCH 1117 from the first TRP 1106 and the second TRP 1108, respectively, because resource allocation information for multiple Msg 2PDSCHs 1115 and 1117 may be included in each of Msg 2PDCCH 1111 and 1113. Therefore, as long as one Msg 2PDCCH (e.g., Msg 2PDCCH 1113) is received by UE 1002, UE 1002 can successfully receive complete resource allocation information for the scheduled PDSCH.

[0096] In another aspect of the present disclosure, a Msg 2 such as a Msg 2 PDSCH (e.g., 1113 and 1117) sent to a UE may carry an uplink grant, the uplink grant including beam-related information such as a beam scanning mode and / or a beam configuration, and the beam-related information may be used by the UE to send multiple Msg 3s based on beam scanning. Thus, after the UE receives at least one Msg 2 PDSCH from a TRP or a cell, the UE may use the uplink resources granted in the Msg 2 to send multiple Msg 3s using beam scanning based at least in part on the beam-related information received in the uplink grant.

[0097] For example, returning a reference Fig.11A , UE 1102 may receive Msg 2PDSCH 1115 from first TRP 1106, but may not receive Msg 2PDSCH 1117 sent from second TRP 1108. Then, as described by Fig. 11B As shown, based on the received Msg 2PDSCH 1115, UE 1102 can utilize beam scanning to send multiple Msg 3PUSCHs (such as PUSCH 1119, 1121, 1123, 1125) to the first TRP 1106 and the second TRP 1108, because Msg 2PDSCH 1115 may include uplink resources and complete beam scanning information (for example, beams used by TRPs to send / receive RACH messages) in which UE 1102 can use to send multiple Msg 3PUSCHs. Therefore, as long as the UE 1102 receives one of the multiple Msg2PDSCHs from the TRP (e.g., 1106, 1108), the UE 1102 can know the beam and / or beam pair used by the cell or the TRP of the cell to send / receive the RACH message, and the UE 1102 can use beam scanning to send multiple Msg 3 to the beam and / or beam pair used by the cell or the TRP of the cell. The UE 1102 can send multiple Msg 3 to the first TRP 1006 and / or the second TRP 1008 based on TDM, SDM, FDM and / or a combination thereof. For example, as in Fig. 11BAs shown at 1122 of , UE 1102 can use the first UE beam to send the first Msg 3PUSCH 1119 and the second Msg 3PUSCH 1121 to the beam n of the first TRP 1106, and then UE 1102 can use the second UE beam to send the third Msg 3PUSCH 1123 and the fourth Msg 3PUSCH 1125 to the beam m of the second TRP 1108, wherein the beam scanning transmission of the Msg 3PUSCH is based on TDM (for example, each Msg 3 can be sent at a different time). In some examples, UE 1102 can select resources for sending Msg 3 based on at least one of the beam pool index or the TRP index, such as in combination with Fig.10 and 11A The RACH candidate beam pool described in .

[0098] In one example, if the UE sends multiple Msg 1s based on beam scanning, the UE may use the same beam scanning mode to send Msg 3 PUSCH, or it may use a different beam scanning mode / set based on the beam scanning information received by the UE in the uplink grant of Msg 2. Fig.11A As shown at 1118 of , if UE 1102 uses a first UE beam to send a first Msg 1 to beam n of a first TRP 1106, and uses a second UE beam to send a second Msg 2 to beam m of a second TRP 1108, UE 1102 may use the same beam pair and / or transmit beam (e.g., a first UE beam and a second UE beam) to send multiple Msg 3PUSCHs, such as in Fig. 11B As shown at 1122.

[0099] In some examples, the base station (e.g., cell 1104) may include in the beam scanning information (e.g., in Msg2PDSCH) an indication for indicating / notifying the UE whether to apply the same beam scanning configuration or to apply a different beam scanning configuration to improve wireless transmission. For example, if the base station (e.g., 706, 806, 808, 906) or TRP (e.g., 1006, 1008, 1106, 1108) determines that the received signal strength is low or below the threshold for Msg 1, the base station may enable beam repetition for the UE in the uplink grant of Msg 2 to improve the transmission reliability for Msg 3. For example, return to reference Fig.11A 1118, if the second TRP 1108 determines that the received signal strength of Msg 1 transmitted from the second UE beam is below the threshold, the PSCell 1104 may instruct the UE 1102 to apply beam repetition to the Msg 3 PUSCH transmission. Then, as described by Fig. 11BAs shown, for one or more transmit beams of the UE, UE 1102 can send multiple Msg 3PUSCHs (e.g., 1119 and 1121) from a first UE beam, send multiple Msg 3PUSCHs (e.g., 1123 and 1125) from a second UE beam, and so on, at least in part based on beam scanning information, wherein Msg 3PUSCH 1121 can be a repetition of Msg 3PUSCH 1119, and Msg 3PUSCH 1125 can be a repetition of Msg 3PUSCH 1123, and so on.

[0100] In another example, because the environment or channel conditions between the UE and the base station may change over time, if the base station (e.g., SCell 706, 806, 808, 906) or TRP (e.g., 1006, 1008, 1106, 1108) receives a newer beam measurement report (such as layer 1 (L1) and / or layer 3 (L3) measurement report) indicating one or more beams with better beam measurements than those beams used by the UE (e.g., 702, 802, 902, 1002, 1102) to send Msg 1, the base station can indicate to the UE (e.g., via beam scanning information in an uplink grant of Msg 2PDSCH) to change one or more scanning (e.g., transmission) beams used to send Msg 3PUSCH. For example, returning to reference Fig.11A and 11B , if PSCell 1004 receives a beam measurement report indicating that the third UE beam and the fourth UE beam of UE 1002 have better beam measurements than the first UE beam and the second UE beam of UE 1002, PSCell 1004 may indicate to UE 1002 to use the third UE beam and the fourth UE beam instead to send Msg 3PUSCH. In some examples, the base station may also select a new beam with better L1 and / or L3 measurements, or it may select a beam that is above a threshold in L1 and / or L3 measurements.

[0101] In another example, if the base station (e.g., SCell 706, 806, 808, 906) or TRP (e.g., 1006, 1008, 1106, 1108) determines that the received signal strength of one or more beams for the UE is low or below a threshold (e.g., based on measuring the received Msg 1), the base station may indicate to the UE in an uplink grant (e.g., Msg 2PDSCH) to add beams for sending Msg 3PUSCH and / or to replace one or more beams for sending Msg 1 with other beams for sending Msg 3PUSCH to improve transmission reliability. For example, if a UE (e.g., UE 1102) uses a first UE beam and a second UE beam to send Msg 1, and a serving base station (e.g., PSCell 1104) determines that the signal strength for the first UE beam is below a threshold, the base station may instruct the UE to use an additional beam to send Msg 3PUSCH (such as using the first UE beam, the second UE beam, the third UE beam, and the fourth UE beam to send Msg 3PUSCH), or the base station may instruct the UE to use the third UE beam to replace the first UE beam to send Msg 3PUSCH, so that the UE can use the second UE beam and the third UE beam to send Msg3PUSCH.

[0102] As described above, a wireless device (e.g., a base station, a TRP, a UE, etc.) may send a random access message using beam scanning based on TDM, SDM, FDM, or a combination thereof. In one example, the base station may use an uplink grant to indicate to the UE which multiplexing scheme the UE may use to send Msg 3 PUSCH, and the base station may optionally indicate the number of repetitions used for transmission based on the indication of the multiplexing scheme. For example, the UE may be configured by the base station in the uplink grant to have a scheme selection indicator set to one of "FDM scheme", "TDM scheme", "SDM scheme", and / or the number of repetitions used for transmission in each scheme may also be indicated to the UE (e.g., two repetitions, four repetitions, etc.). For example, when two repetitions are indicated in the uplink grant and the UE is configured to apply the FDM scheme, the base station may monitor two PUSCH transmission opportunities with non-overlapping frequency domain resource allocations. Therefore, the UE may send Msg 3 in two PUSCH transmission opportunities with non-overlapping frequency resources. Similarly, when two repetitions are indicated in the uplink grant and the UE is using the TDM scheme, the base station may monitor two PUSCH transmission opportunities with non-overlapping time domain resource allocations. Therefore, the UE may send Msg 3 in two PUSCH transmission opportunities with non-overlapping time resources. In another example, when two repetitions are indicated in the uplink grant and the UE is using the SDM scheme, the base station may monitor two PUSCH transmission opportunities with two spatially separated beam resource allocations (e.g., two downlink reference signal IDs). Therefore, the UE may send Msg 3 in two different beams. In addition, the UE may also be configured by the base station to use more than one multiplexing scheme or a combination of schemes. For example, the UE may use SDM in combination with an FDM scheme and / or a TDM scheme.

[0103] Combination Figure 4 to 1 The RACH setup procedure (e.g., random access message exchange) between a PSCell (e.g., 706, 806, 808, 906) and a UE (e.g., 702, 802, 902, 1002) described in 1 may be contention-free, such as when the PSCell is in non-standalone (NSA) mode in certain network settings. For example, referring back to Figure 5, since the PCell 504 can be connected to the UE 502, the PCell 504 can allocate reference signal resources (e.g., 513), RACH resources (e.g., 511), etc. for the PSCell 506, and the PCell 504 can also pass the UE information (e.g., UE ID) to the PSCell 506. Therefore, the PSCell 506 can skip performing the contention resolution process because the PSCell 506 can have information about the UE 502 (e.g., UE ID). In this way, if the contention resolution process can be skipped, the PSCell 506 can continue or complete the RACH setup process with the UE 502 without sending a contention resolution message (e.g., Msg 4) to the UE 502.

[0104] In other examples, the RACH setup procedure (e.g., random access message exchange) between the PSCell (e.g., 706, 806, 808, 906) and the UE (e.g., 702, 802, 902, 1002, 1102) may not be contention-free, such as when the PSCell is in a standalone (SA) mode in certain network settings. In such a case, the PSCell may perform contention resolution by sending a contention resolution message (e.g., Msg 4) to the UE to complete the RACH setup procedure.

[0105] In another aspect of the present disclosure, a cell or one or more TRPs of a cell may be configured to send multiple Msg 4PDCCH / PDSCH to a UE based on beam scanning, wherein the transmission of the multiple Msg 4PDCCH / PDSCH may be based on TDM, FDM, SDM, or a combination thereof. Similarly, the beams used by the cell or one or more TRPs to send the multiple Msg 4PDCCH / PDSCH may be selected from one or more beam pool indices, such as in combination with Figure 9-1 1. Therefore, as long as the UE receives a Msg 4, the RACH setting process between the UE and the cell can be completed.

[0106] For example, by Fig. 11C As shown, PSCell 1004 can configure multiple Msg 4 PDCCH / PDSCH to be sent to UE 1102 from one or more beams of the first TRP 1006 and one or more beams of the second TRP 1008 based on TDM. Fig. 11CThe example in applies TDM to multiple Msg 4 transmissions, but the transmission of multiple Msg 4 PDCCH / PDSCH can also be based on FDM TDM, SDM or a combination thereof. One or more beams used by the first TRP 1106 and / or the second TRP can be selected from their corresponding beam pools, such as beam pool 1007 and beam pool 1109, respectively.

[0107] In one example, the first TRP 1106 and / or the second TRP 1108 may apply the same beam scanning mode (e.g., beam size, number of beam scanning / repetitions, etc.) and / or configuration for transmitting Msg 2 PDCCH / PDSCH (e.g., 1111, 1113, 1115, 1117). Fig.11A As shown at 1120 of , the first TRP 1106 may use beam n to send Msg 2PDCCH 1111 and Msg 2PDSCH 1115 to the first UE beam of UE 1002, and the second TRP 1108 may use beam m to send Msg 2PDCCH 1113 and Msg 2PDSCH 1117 to the second UE beam of UE 1002. Then, as shown in Fig. 11C As shown in 1124, PSCell 1004 may also configure Msg 4PDCCH 1127, Msg 4PDSCH 1131, Msg4PDSCH repetition 1133 (e.g., repetition of Msg 4PDSCH 1131) to be sent from beam n of the first TRP 1106 to the first UE beam of UE1102, and PSCell 1004 may configure Msg 4PDCCH 1129, Msg 4PDSCH 1135, Msg4PDSCH repetition 1137 (e.g., repetition of Msg 4PDSCH 1135) to be sent from beam m of the second TRP 1108 to the second UE beam of UE1102.

[0108] In another example, the first TRP 1106 and / or the second TRP 1108 may apply a beam scanning mode (e.g., a narrower beam or a different number of beam scanning / repetitions) and / or a beam configuration different from the beam scanning mode and / or beam configuration used to send Msg2PDCCH / PDSCH (e.g., 1111, 1113, 1115, 1117), and the PSCell 1004 may indicate a beam scanning mode and / or beam configuration in which the UE 1002 may receive Msg 4 via Msg 2PDCCH and / or Msg 4PDCCH. Alternatively, the TRP 1106 and / or the TRP 1108 may be configured (e.g., via the Msg 2PDCCH or the Msg4PDCCH) to use a different beam, beam pattern (e.g., a narrower beam) and / or beam configuration (e.g., a different number of beam scanning / repetitions).

[0109] If UE 1102 receives at least one of Msg 4 PDCCH / PDSCH from at least one of the TRPs (e.g., 1106, 1108) and contention resolution is successful, the temporary cell radio network temporary identifier (TC-RNTI) associated with UE 1102 can become the allocated C-RNTI. For example, the TC-RNTI can be used during a RACH process, where the MAC layer of the base station can generate a RAR as a response to a random access preamble sent by the UE. The MAC RAR can contain the TC-RNTI. During a contention-based RACH process, the UE can store the received TC-RNTI (e.g., received in the RAR) and use the TC-RNTI (e.g., as an identifier) ​​during the RACH process. The UE can use the TC-RNTI to scramble msg3 (corresponding to the PUSCH granted by the RAR) and its retransmissions. During a contention-based RACH process, the UE can also monitor the PDCCH scrambled with the temporary C-RNTI. For a UE that detects that random access is successful and does not have a C-RNTI, the TC-RNTI may be promoted to a C-RNTI.

[0110] After UE 1102 receives at least one of the Msg 4PDCCH / PDSCH, UE 1102 may send HARQ feedback (e.g., ACK / NACK) to PSCell 1004 (such as via PUCCH) to complete the RACH process. Similarly, the transmission of the HARQ feedback may be based on beam scanning using TDM, FDM, SDM, or a combination thereof. UE 1102 may be configured by PSCell 1004 via Msg 2PDCCH / PDSCH and / or Msg 4PDCCH regarding how to perform beam scanning for HARQ-ACK feedback transmission. For example, UE 1102 may be configured by PSCell 1004 to send HARQ feedback using a specific beam, beam pattern, and / or one or more beam configurations. For example, the PSCell may indicate to UE 1102 to send HARQ feedback using the same beam and / or beam pattern used to send Msg 3PUSCH. As in Fig. 11C As shown at 1126 of , UE 1102 may send a first HARQ feedback 1139 from a first UE beam to beam n of a first TRP 1106, and UE 1102 may send a second HARQ feedback 1141 from a second UE beam to beam m of a second TRP 1108, etc. Therefore, as long as PSCell 1104 receives one of the HARQ feedbacks sent by UE 1102, the RACH process may be completed.

[0111] By sending one or more random access messages of the RACH process between the UE and the base station based on beam scanning (such as described in conjunction with Figures 7 to 11), as long as one of each random access message (e.g., Msg 1, Msg 2, Msg 3, Msg 4, etc.) is successfully received by the UE or the base station (e.g., depending on the random access message), the RACH setup process can be completed between the base station and the UE even if the beam subset fails. In this way, the robustness and reliability of network transmission can be improved. For example, if the random access message sent / received in one beam is unsuccessful, the UE or cell can continue the RACH process because the random access message can be successfully sent / received in a different beam. Therefore, applying beam scanning for random access Msg 3 and / or Msg4 can improve the latency for transmission, especially in low-quality channel conditions.

[0112] Fig. 12A and 12B 1200 is a diagram illustrating an example of a beam scanning based RACH procedure between a UE and multiple TRPs of a base station according to aspects of the present disclosure. The RACH procedure described herein may include combining Figure 4 and 7AAspects of any of the example descriptions in Examples 1 to 11.

[0113] If through Fig. 12A As shown, UE 1202 may initiate a RACH process with base station 1204 through a first TRP 1206, a second TRP 1208, and a third TRP 1210 of base station 1204, wherein the first TRP 1206 may be associated with a first beam pool 1207 and a first TRP index (e.g., TRP index = 0), the second TRP 1208 may be associated with a second beam pool 1209 and a second TRP index (e.g., TRP index = 1), the third TRP 1210 may be associated with a third beam pool 1211 and a third TRP index (e.g., TRP index = 2), etc. Each TRP may transmit one or more reference signals from one or more beams of the TRP, wherein one reference signal may correspond to one beam of the TRP. For example, as shown at 1250, the first TRP 1206 may send multiple CSI-RS from one or more beams of the first TRP 1206 using different CSI-RS resources (e.g., resources #1-20), wherein the one or more beams of the first TRP 1206 may be selected from the beam pool 1007; the second TRP 1208 may send multiple CSI-RS from one or more beams of the second TRP 1208 using different CSI-RS resources (e.g., resources #41-60), wherein the one or more beams of the second TRP 1208 may be selected from the beam pool 1009; and the third TRP 1210 may send multiple CSI-RS from one or more beams of the third TRP 1210 using different CSI-RS resources (e.g., resources #21-40), wherein the one or more beams of the third TRP 1210 may be selected from the beam pool 1007. In some examples, beams in one beam pool may be configured to not overlap with beams in another beam pool.

[0114] After UE 1202 receives one or more CSI-RS transmitted from the first TRP 1206, the second TRP 1208, and the third TRP 1210, the UE may transmit multiple Msg 1s to the first TRP 1206, the second TRP 1208, and the third TRP 1210 based on beam scanning, such as in combination with Figure 8 to 1 1. For example, as described in Fig. 12AAs shown at 1252, UE 1202 may use a first UE beam 1224 to send a first Msg 1 to beam 1212 of a first TRP 1206, use a second UE beam 1226 to send a second Msg 1 to beam 1214 of the first TRP 1206, use a third UE beam 1228 to send a third Msg 1 to beam 1216 of the second TRP 1208, use a fourth UE beam 1230 to send a fourth Msg 1 to beam 1218 of the second TRP 1208, use a fifth UE beam 1232 to send a fifth Msg 1 to beam 1220 of the second TRP 1208, and use a sixth UE beam 1234 to send a sixth Msg 1 to beam 1222 of the third TRP 1210. Each Msg 1 in the Msg 1 may include information related to the beam used by UE 1202. Therefore, as long as one Msg 1 is successfully received by base station 1204 or one of the TRPs of base station 1204, base station 1204 can know the beam pair used by UE 1202 to send Msg 1. The transmission of Msg 1 can be based on TDM, FDM, SDM or a combination thereof.

[0115] After the base station 1204 receives at least one Msg 1 from one of the beams of the UE 1202, the base station 1204 may respond to the UE 1202 with multiple Msg 2 based on the beam scanning. Fig. 12BAs shown in 1254, the base station 1204 can send a first Msg 2 from the beam 1212 of the first TRP 1206 to the first UE beam 1224, send a second Msg 2 from the beam 1214 of the first TRP 1206 to the second UE beam 1226, send a third Msg 2 from the beam 1216 of the second TRP 1208 to the third UE beam 1228, send a fourth Msg 2 from the beam 1218 of the second TRP 1208 to the fourth UE beam 1230, send a fifth Msg 2 from the beam 1220 of the second TRP 1208 to the fifth UE beam 1232, and send a sixth Msg 2 from the beam 1222 of the third TRP 1210 to the sixth UE beam 1234, and so on. Msg 2 may include PDCCH and PDSCH, and the beams used to send PDCCH and PDSCH may be the same, or they may be different. The transmission of Msg 2 may be based on TDM, FDM, SDM, or a combination thereof. Msg 2 (e.g., PDCCH) may carry resource allocation information and / or beam scanning related information for multiple Msg 2PDSCHs. Therefore, if one of the Msg 2PDCCHs is received but the others are not, the UE is still able to receive the Msg 2PDSCH. Msg 2PDSCH may carry an uplink grant, which includes beam related information (such as beam scanning mode and / or beam configuration) that the UE may use to send multiple Msg 3s based on beam scanning. Therefore, after the UE receives at least one Msg 2 PDSCH from a TRP or cell, the UE may use the uplink resources granted in Msg 2 to send multiple Msg 3s using beam scanning based at least in part on beam-related information received in the uplink grant.

[0116] Based on at least one of the Msg 2s received from the base station 1204, the UE 1202 may send multiple Msg 3s to the base station 1204 based on beam scanning. For example, the UE 1202 may send Msg 3 using the beam pair used to send Msg 1, wherein the UE 1202 may send the first Msg 3 to the beam 1212 of the first TRP 1206 using the first UE beam 1224, send the second Msg 1 to the beam 1214 of the first TRP 1206 using the second UE beam 1226, and so on. The UE 1202 may send multiple Msg 3s to the first TRP 1006, the second TRP 1008, and / or the third TRP 1210 based on TDM, SDM, FDM, and / or a combination thereof. In some examples, the UE 1202 may select a resource for sending Msg 3 based on at least one of a beam pool index or a TRP index, such as in combination with Fig.10 and the RACH candidate beam pool described in 11.

[0117] In some examples, the base station 1204 may include in the beam scanning information (e.g., in Msg 2) an indication for indicating to the UE 1202 whether to apply the same beam scanning configuration or to apply a different beam scanning configuration to improve wireless transmission. For example, if the base station 1204 determines that the received signal strength for one or more beams is lower than the threshold for Msg 1, the base station may enable beam repetition for the UE in the uplink grant of Msg 2 to improve transmission reliability for Msg 3. In another example, because the environment or channel conditions between the UE and the base station may change over time, if the base station 1204 receives a newer beam measurement report indicating one or more beams with better beam measurements than those beams used by the UE 1202 to send Msg 1, the base station 1204 may indicate to the UE to change one or more scanning (e.g., transmission) beams used to send Msg 3 PUSCH. In another example, if base station 1204 determines that the received signal strength of one or more beams for UE 1202 is below a threshold, the base station may indicate to the UE in an uplink grant to add a beam for sending Msg 3 and / or to replace one or more beams for sending Msg 1 with other beams for sending Msg 3.

[0118] Based on receiving at least one of the Msg 3 from the UE 1202, the base station 1204 may send multiple Msg 4 PDCCH / PDSCH to the UE 1202 based on beam scanning, wherein the transmission of the multiple Msg 4 PDCCH / PDSCH may be based on TDM, FDM, SDM or a combination thereof. Fig. 12B As shown at 1254, the base station 1204 can send a first Msg 4 from the beam 1212 of the first TRP 1206 to the first UE beam 1224, send a second Msg 4 from the beam 1214 of the first TRP 1206 to the second UE beam 1226, send a third Msg 4 from the beam 1216 of the second TRP 1208 to the third UE beam 1228, and so on. In one example, the first TRP 1206, the second TRP 1208, and / or the third TRP 1210 can apply the same beam scanning mode (e.g., beam size, number of beam scanning / repetitions, etc.) and / or configuration for sending Msg 2.

[0119] If UE 1202 receives at least one of the Msg4s from at least one of the TRPs (e.g., 1206, 1208, 1210) of base station 1204 and contention resolution is successful, the TC-RNTI associated with UE 1202 may become the allocated C-RNTI. UE 1202 may then send HARQ feedback (e.g., ACK / NACK) to PSCell 1004, such as via PUCCH, to complete the RACH process. Similarly, the transmission of HARQ feedback may be based on beam scanning using TDM, FDM, SDM, or a combination thereof. UE 1202 may be configured by base station 1204 via Msg 2PDCCH / PDSCH and / or Msg 4PDCCH regarding how to perform beam scanning for HARQ-ACK feedback transmission. Thus, as long as base station 1204 receives one of the HARQ feedbacks sent by UE 1202, the RACH process may be completed.

[0120] Fig.13 1300 is a flow chart of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., UE 104, 350, 402, 502, 702, 802, 902, 1002, 1102, 1202; apparatus 1402; a processing system, which may include a memory 360 and may be the entire UE 350 or a component of the UE 350, such as a TX processor 368, an RX processor 356, and / or a controller / processor 359). Optional aspects are shown with dashed lines. The method may improve random access between a UE and a base station by providing multiple transmission opportunities and applying beam scanning to random access transmissions. Aspects of the method may improve the reliability of random access and reduce latency for random access.

[0121] At 1302, the UE may send a first random access message to the serving cell, such as in conjunction with Figure 4 and 7-12. The serving cell may include a PCell, an SCell and / or a PSCell, such as a combination of Figure 5 and 7-12. For example, as described in Fig.11A As shown at 1118 of UE 1102, UE 1102 may send a first random access message (e.g., Msg 1) to PSCell 1104 through first TRP 1106 and second TRP 1108 of PSCell 1104. For example, the transmission of the first random access message may be performed by Fig.14 The Msg 1 processing component 1440 and / or the sending component 1434 of the device 1402 are executed.

[0122] At 1304, the UE may receive a second random access message in response to the first random access message from the serving cell, such as in conjunction with Figure 9-1 2. For example, as described in Fig.11A As shown at 1120 of , UE 1102 may receive a second random access message (e.g., Msg 2PDCCH 1113, Msg 2PDSCH 1117, etc.) from a second TRP 1108 of PSCell 1104. The second random access message received by the UE may include a grant for a third random access message, and may also indicate to the UE that the third random access message is sent on multiple beams using at least one of TDM, FDM, or SDM. In some examples, the second random access message may also include beam scanning information for the third random access message. In other examples, the third random access message may also indicate a number of repetitions for the third random access message, such as in conjunction with Fig.11A and 11B The reception of the second random access message may be performed by, for example, Fig.14 The Msg 2 receiving component 1442 and / or the receiving component 1430 of the device 1402 is executed.

[0123] At 1308, the UE may send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for reception (e.g., reception of the random access message) on multiple beams of the UE, and use resources based on at least one of the beam pool index or the TRP index, such as in combination with Fig.11A , 11B and 12A. For example, as described in Fig. 11B As shown at 1122 of , UE 1102 may send multiple Msg 3s to the first TRP 1106 and the second TRP 1108 of PSCell 1104 in a beam scanning mode for reception on multiple beams, and UE 1102 may use resources (e.g., beams) selected from beam pools 1107 and 1109 associated with the first TRP 1106 and the second TRP 1108, respectively, and each TRP may be associated with a TRP index. In other words, the UE may send multiple Msg 3s to multiple TRPs based on a beam scanning mode (e.g., beam scanning using multiple beams), and then in response, the UE may receive multiple Msg 4s from the multiple TRPs or at least one of the multiple TRPs. Transmission of the third random access message may be, for example, by Fig.14 The Msg 3 process component 1444 and / or the sending component 1434 of the device 1402 is executed.

[0124] In one example, a third random access message may be sent using resources granted in the second random access message for reception on multiple beams. For example, at 1306, the UE may receive beam scanning related information (e.g., resources and patterns, etc.) for TDM, FDM, and / or SDM beam scanning for the third random access message in the second random access message (e.g., in the PDSCH portion of the second random access message). In some examples, the first random access message and the third random access message may be sent using the same pattern of multiple beams. In other examples, the first random access message may be sent using a first beam pattern of multiple beams, and the third random access message may be sent using a second different beam pattern of the multiple beams. For example, at 1310, the UE may send a third random access message on multiple beams using at least one of TDM, FDM, or SDM, such as in combination with Fig.11A , 11B and as described in 12A.

[0125] At 1312, the UE may receive an indication of a beam set for receiving a fourth random access message, such as in conjunction with Fig. 11B , 11C and 12A. The receipt of the indication may be, for example, by Fig.14 The receiving component 1430 of the device 1402 is executed.

[0126] In some examples, the UE may receive the indication in the second random access message (such as the PDCCH of the second random access message), wherein the UE may use the beam set indicated by the indication to receive the PDCCH or PDSCH of the fourth random access message. In other examples, the UE may receive the indication in the PDCCH of the fourth random access message, and the UE may use the beam set indicated in the PDCCH to receive the PDSCH of the fourth random access message, such as in combination with Fig. 11B , 11C and as described in 12B.

[0127] At 1314, the UE may receive a fourth random access message from one or more TRPs of the serving cell on the beam set, such as in conjunction with Fig. 11B , 11C and 12B. The reception of the fourth random access message may be performed, for example, by Fig.14The Msg 4 receiving component 1446 and / or the receiving component 1430 of the device 1402 in the embodiment of the present invention may be performed. The fourth random access message may be sent by the base station based on one or more of TDM, FDM or SDM on the beam set. The resources used for the fourth random access message may be associated with at least one of the beam pool index or the TRP index. In some examples, the UE may use the same beam set to receive the second random access message and the fourth random access message. In other examples, the beam set used to receive the fourth random access message may have a different beam configuration from the beam used to receive the second random access message.

[0128] At 1318, the UE may send HARQ-ACK feedback (e.g., 1139, 1141) in the PUCCH using TDM, FDM, or SDM beam scanning, such as in conjunction with Fig. 11C As shown at 1306, the UE may receive beam scanning related information (e.g., resources and modes, etc.) for TDM, FDM, and / or SDM beam scanning for HARQ feedback in at least one of the second random access message or the control portion of the fourth random access message.

[0129] Fig.1414 is a schematic diagram 1400 showing an example of a hardware implementation for an apparatus 1402. The apparatus 1402 is a UE and includes a cellular baseband processor 1404 (also referred to as a modem) coupled to a cellular RF transceiver 1422 and one or more subscriber identity modules (SIM) cards 1420, an application processor 1406 coupled to a secure digital (SD) card 1408 and a screen 1410, a Bluetooth module 1412, a wireless local area network (WLAN) module 1414, a global positioning system (GPS) module 1416, and a power supply 1418. The cellular baseband processor 1404 communicates with the UE 104 and / or the BS 102 / 180 through the cellular RF transceiver 1422. The cellular baseband processor 1404 may include a computer-readable medium / memory. The computer-readable medium / memory may be non-transitory. The cellular baseband processor 1404 is responsible for general processing, including executing software stored on the computer-readable medium / memory. When executed by the cellular baseband processor 1404, the software causes the cellular baseband processor 1404 to perform the various functions described above. The computer-readable medium / memory may also be used to store data manipulated by the cellular baseband processor 1404 when executing the software. The cellular baseband processor 1404 also includes a receiving component 1430, a communication manager 1432, and a transmitting component 1434. The communication manager 1432 includes one or more of the components shown. The components within the communication manager 1432 may be stored in a computer-readable medium / memory and / or configured as hardware within the cellular baseband processor 1404. The cellular baseband processor 1404 may be a component of the UE 350 and may include at least one of the TX processor 368, the RX processor 356, and the controller / processor 359 and / or the memory 360. In one configuration, the device 1402 may be a modem chip and include only the baseband processor 1404, and in another configuration, the device 1402 may be the entire UE (e.g., see Figure 3 350) and includes the additional modules discussed previously of device 1402.

[0130] The communication manager 1432 includes a Msg 1 processing component 1440, which is configured to send a first random access message to the serving cell, for example, as combined with Fig.13 The communication manager 1432 also includes a Msg 2 receiving component 1442, which is configured to receive a second random access message in response to the first random access message from the serving cell, for example, as described in conjunction with Fig.13The communication manager 1432 also includes a Msg 3 processing component 1444, which is configured to send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving (e.g., Msg 4) on multiple beams (e.g., multiple receive beams of the UE) and using resources based on at least one of the beam pool index or the TRP index, for example, as combined Fig.13 The communication manager 1432 also includes a Msg 4 receiving component 1446, which is configured to receive a fourth random access message from one or more TRPs of the serving cell on the beam set, for example, as combined with Fig.13 1314 described.

[0131] The device may include executing the aforementioned Fig.13 Each block in the flowchart of the algorithm has an additional component. Fig.13 Each block in the flowchart of can be performed by a component, and the apparatus may include one or more of those components. The component may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium to be implemented by a processor, or some combination thereof.

[0132] In one configuration, the apparatus 1402 (and specifically, the cellular baseband processor 1404) includes: a unit for sending a first random access message to a serving cell (e.g., a Msg 1 processing component 1440 and / or a sending component 1430). The apparatus 1402 includes: a unit for receiving a second random access message in response to the first random access message from the serving cell (e.g., a Msg 2 receiving component 1442 and / or a receiving component 1430). The apparatus 1402 includes: a unit for sending a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams of the UE and using resources based on at least one of a beam pool index or a TRP index (e.g., a Msg 3 processing component 1444 and / or a sending component 1434).

[0133] The aforementioned means may be one or more of the components of the apparatus 1402 configured to perform the functions recited by the aforementioned means. As described above, the apparatus 1402 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Therefore, in one configuration, the aforementioned means may be a TX processor 368, an RX processor 356, and a controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0134] Fig.151500 is a flowchart of a method of wireless communication. The method may be performed by a base station or a component of a base station (e.g., base station 102, 180, 310, 404; cell 504, 506, 706, 906, 1004, 1104, 1204; TRP 704, 806, 808, 1006, 1008, 1106, 1108, 1206, 1208; device 1602; processing system, which may include memory 376 and may be the entire base station 310 or a component of the base station 310, such as TX processor 316, RX processor 370 and / or controller / processor 375). The method may be performed, for example, by a PCell, SCell, or PSCell for a UE. Optional aspects are shown with dashed lines. The method may improve random access between a base station and a UE by providing multiple transmission opportunities and applying beam scanning to random access transmissions. Aspects of the method may improve the reliability of random access and reduce latency for random access.

[0135] At 1502, a base station may receive a first random access message from a UE, such as in conjunction with Figure 4 and 7-12. The base station can serve the UE as a PCell, SCell or PSCell, such as in combination Figure 5 and 7-9. For example, in Fig.11A At 1118 of , PSCell 1104 may receive Msg 1 from UE 1102 from the first TRP 1106 and the second TRP 1108 of PSCell 1104. Reception of the first random access message may be performed, for example, by Fig.16 The Msg 1 receiving component 1640 and / or the receiving component 1630 of the device 1602 is executed.

[0136] At 1504, the base station sends a second random access message to the UE in response to the first random access message, such as in conjunction with Figure 9-1 2. For example, in Fig.11A At 1120, PSCell 1104 may send Msg 2 from first TRP 1106 and second TRP 1108 to UE 1102. In one example, the second random access message may include beam scanning information for the third random access message. The sending of the second random access message may be performed, for example, by Fig.16 The Msg 2 processing component 1642 and / or the sending component 1634 of the device 1602 are executed.

[0137] At 1508, the base station may receive a third random access message on at least one of a plurality of beams monitored by the base station or one or more TRPs of the base station (e.g., a plurality of receive beams of one or more TRPs) in a beam scanning mode using resources based on at least one of the beam pool index or the TRP index at one or more TRPs, such as in combination with Fig.11A , 11B and 12A. For example, in Fig. 11B At 1122 of , PSCell 1104 may receive multiple Msg 3s at a first TRP 1106 and a second TRP 1108 of PSCell 1104, wherein the first TRP 1106 may be associated with a beam pool 1107 and a first TRP index, and the second TRP 1108 may be associated with a beam pool 1109 and a second TRP index. In other words, the base station may use multiple beams (e.g., multiple beams from multiple TRPs and / or TRPs) to send multiple Msg 2s to the UE, and in response, the base station may receive one or more Msg 3s from the UE via at least one of the multiple beams of the multiple TRPs. Reception of the third random access message may be, for example, by Fig.16 The Msg 3 receiving component 1644 and / or the receiving component 1630 of the device 1602 is executed.

[0138] In some examples, the base station may use the resources granted to the UE in the second random access message to monitor the third random access message, such as in conjunction with Fig.11A , 11B and 12A. For example, the base station may use the same pattern of multiple beams to receive the first random access message and the third random access message. In another example, the base station may use a first beam pattern of multiple beams to receive the first random access message, and the base station may use a second different beam pattern of multiple beams to monitor the third random access message.

[0139] The third random access message may be sent based on TDM, FDM or SDM on multiple beams.

[0140] At 1506, the base station may indicate a second different beam pattern to the UE in a second random access message in response to determining that the signal strength of one or more beams for the first random access message is below a threshold amount or receiving a report from the UE indicating a better beam than the beam used for the first random access message. In some examples, the second random access message may include a grant for a third random access message and indicate to the UE that the third random access message is to be sent using at least one of TDM, FDM, or SDM on multiple beams. In other examples, the grant for the third random access message may also indicate a number of repetitions for the third random access message, such as in conjunction with Fig.11A and 11B as described.

[0141] At 1510, the base station may send an indication of a beam set for a fourth random access message, such as in conjunction with Fig. 11B and 11C The sending of the indication may be performed, for example, by Fig.16 The base station may transmit the indication in the second random access message. In such an example, the base station may transmit the indication in the PDCCH of the second random access message, and the base station may use the beam set indicated by the indication to transmit the PDCCH or PDSCH of the fourth random access message. In another example, the base station may transmit the indication in the PDCCH of the fourth random access message, and the base station may use the beam set indicated in the PDCCH to transmit the PDSCH of the fourth random access message, such as in combination with Fig. 11B and 11C as described.

[0142] At 1512, the base station may send a fourth random access message from one or more TRPs on the beam set, such as in conjunction with Fig. 11B , 11C and 12B. For example, Fig. 11C At 1124 of , PSCell 1104 may send multiple Msg 4 PDCCH / PDSCH from the first TRP 1106 and the second TRP 1108 of PSCell 1104 on the beam set. The sending of the fourth random access message may be, for example, by Fig.16 The Msg 4 processing component 1646 and / or the sending component 1634 of the device 1602 in 1514 are executed. In one example, at 1514, the base station may use one or more of TDM, FDM, or SDM to send a fourth random access message on a beam set. In some examples, the resources used for the fourth random access message may be based on at least one of a beam pool index or a TRP index. In other examples, the base station may use the same beam set to send the second random access message and the fourth random access message. In other examples, the beam set used to send the fourth random access message may have a different beam configuration than the beam used to send the second random access message.

[0143] At 1518, the base station may receive HARQ-ACK feedback in a PUCCH (e.g., 1159, 1141) from the UE using TDM, FDM, or SDM beam scanning. Reception of HARQ-ACK feedback may be performed, for example, by Fig.16 The receiving component 1630 of the device 1602 is executed.

[0144] In some examples, the base station may send information for TDM, FDM, and / or SDM beam scanning in the second random access message, as shown at 1507. For example, the base station may send the TDM, FDM, and / or SDM beam scanning information in the PDSCH portion of the second random access message. Alternatively, the base station may send information for TDM, FDM, and / or SDM beam scanning in the fourth random access message.

[0145] Fig.16 1600 is a schematic diagram showing an example of a hardware implementation for an apparatus 1602. The apparatus 1602 is a BS and includes a baseband unit 1604. The baseband unit 1604 can communicate with the UE 104 via a cellular RF transceiver. The baseband unit 1604 may include a computer-readable medium / memory. The baseband unit 1604 is responsible for general processing, including executing software stored on the computer-readable medium / memory. When executed by the baseband unit 1604, the software causes the baseband unit 1604 to perform the various functions described above. The computer-readable medium / memory can also be used to store data manipulated by the baseband unit 1604 when executing the software. The baseband unit 1604 also includes a receiving component 1630, a communication manager 1632, and a sending component 1634. The communication manager 1632 includes one or more of the components shown. The components within the communication manager 1632 may be stored in a computer-readable medium / memory and / or configured as hardware within the baseband unit 1604. The baseband unit 1604 may be a component of the base station 310 and may include the memory 376 and / or at least one of the TX processor 316 , the RX processor 370 , and the controller / processor 375 .

[0146] The communication manager 1632 includes a Msg 1 receiving component 1640, which is configured to receive a first random access message from the UE, for example, as combined with Fig.15 The communication manager 1632 also includes a Msg 2 processing component 1642, which is configured to send a second random access message to the UE in response to the first random access message, for example, as combined with Fig.15 The communication manager 1632 also includes a Msg 1 receiving component 1644, which is configured to receive a third random access message on at least one beam of a plurality of beams (e.g., receiving beams) monitored by one or more TRPs in a beam scanning mode using resources based on at least one of the beam pool index or the TRP index at one or more TRPs, for example, as combined Fig.15 The communication manager 1632 also includes a Msg 4 processing component 1646, which is configured to send a fourth random access message from one or more TRPs on the beam set, for example, as combined with Fig.15 1512 described.

[0147] The device may include executing the aforementioned Fig.15 The additional components of each block of the algorithm in the flowchart. Fig.15 Each block in the flowchart of can be performed by a component, and the apparatus may include one or more of these components. The component may be one or more hardware components specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium for processor implementation, or some combination thereof.

[0148] In one configuration, the apparatus 1602 (and specifically, the baseband unit 1604) includes: a unit for receiving a first random access message from a UE (e.g., a Msg 1 receiving component 1640 and / or a receiving component 1630). The apparatus 1602 includes: a unit for sending a second random access message to the UE in response to the first random access message (e.g., a Msg 2 processing component 1642 and / or a sending component 1634). The apparatus 1602 includes: a unit for receiving a third random access message on at least one of a plurality of receiving beams monitored by one or more TRPs in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index at one or more TRPs (e.g., a Msg 3 receiving component 1644 and / or a receiving component 1630). The apparatus 1602 includes: a unit for sending a fourth random access message from one or more TRPs on a beam set (e.g., a Msg 4 processing component 1646 and / or a sending component 1634).

[0149] The aforementioned means may be one or more components of the components of the apparatus 1602 configured to perform the functions recited by the aforementioned means. As described above, the apparatus 1602 may include a TX processor 316, an RX processor 370, and a controller / processor 375. Therefore, in one configuration, the aforementioned means may be a TX processor 316, an RX processor 370, and a controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0150] The following examples set forth additional aspects and are merely illustrative, and aspects thereof may be combined with aspects of other examples or teachings described herein without limitation.

[0151] Aspect 1 is a method for performing wireless communication at a UE, comprising: sending a first random access message to a serving cell; receiving a second random access message from the serving cell in response to the first random access message; and sending a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index.

[0152] In aspect 2, the method according to aspect 1 further includes: the serving cell includes a PCell, a SCell or a PSCell.

[0153] In aspect 3, the method according to aspect 1 or aspect 2 further includes: the third random access message is sent using resources granted in the second random access message for reception on multiple beams.

[0154] In aspect 4, the method according to any one of aspects 1-3 further includes: the second random access message includes beam scanning information for the third random access message.

[0155] In aspect 5, the method according to any one of aspects 1-4 further includes: the first random access message and the third random access message are sent using the same pattern of the multiple beams.

[0156] In aspect 6, the method according to any one of aspects 1-5 also includes: the first random access message is sent using a first beam pattern of multiple beams, and the third random access message is sent using a second different beam pattern of multiple beams.

[0157] In aspect 7, the method according to any one of aspects 1-6 further comprises: using at least one of TDM, FDM or SDM to send the third random access message on the plurality of beams.

[0158] In aspect 8, the method according to any one of aspects 1-7 also includes: the second random access message includes a permission for the third random access message, and instructs the UE to use at least one of TDM, FDM or SDM to send the third random access message on the multiple beams.

[0159] In aspect 9, the method according to any one of aspects 1-8 further comprises: the grant for the third random access message further indicating a number of repetitions for the third random access message.

[0160] In aspect 10, the method according to any one of aspects 1-9 also includes: receiving an indication of a beam set for receiving a fourth random access message; and receiving the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0161] In aspect 11, the method according to any one of aspects 1-10 further includes: the fourth random access message is one or more of TDM, FDM or SDM performed on the beam set.

[0162] In aspect 12, the method according to any one of aspects 1-11 further includes: resources used for the fourth random access message are based on at least one of a beam pool index or a TRP index.

[0163] In aspect 13, the method according to any one of aspects 1-12 further includes: the UE using the same beam set to receive the second random access message and the fourth random access message.

[0164] In aspect 14, the method according to any one of aspects 1-13 further comprises: the indication is received in the second random access message.

[0165] In aspect 15, the method according to any one of aspects 1-14 further comprises: the set of beams used for receiving the fourth random access message has a beam configuration different from the beam used for receiving the second random access message.

[0166] In aspect 16, the method according to any one of aspects 1-15 also includes: the indication is received in the PDCCH of the second random access message, and wherein the UE uses the beam set indicated by the indication to receive the PDCCH or physical downlink shared channel of the fourth random access message.

[0167] In aspect 17, the method according to any one of aspects 1-16 also includes: the indication is received in the PDCCH of the fourth random access message, and the UE uses the beam set indicated in the PDCCH to receive the PDSCH of the fourth random access message.

[0168] In aspect 18, the method according to any one of aspects 1-17 further comprises: sending HARQ-ACK feedback in PUCCH using TDM or FDM or SDM beam scanning.

[0169] In aspect 19, the method according to any one of aspects 1-18 further comprises: receiving information for the TDM or FDM or SDM beam scanning in at least one of the control part of the second random access message or the fourth random access message.

[0170] Aspect 20 is a device for wireless communication, comprising: a unit for sending a first random access message to one or more TRPs of a serving cell; a unit for receiving a second random access message from the serving cell in response to the first random access message; and a unit for sending a third random access message to the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index.

[0171] In aspect 21, the apparatus according to aspect 20 further comprises: a unit for performing the method according to any one of claims 2-19.

[0172] Aspect 22 is a device for wireless communication, comprising: a memory; and at least one processor coupled to the memory, the memory and the at least one processor being configured to: send a first random access message to a serving cell; receive a second random access message from the serving cell in response to the first random access message; and send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources based on at least one of a beam pool index or a TRP index.

[0173] In aspect 23, the apparatus according to aspect 22 further comprises: the memory and the at least one processor are further configured to perform the method according to any one of claims 2-19.

[0174] Aspect 24 is a non-transitory computer-readable storage medium storing computer-executable code for wireless communication, which, when executed by a processor, causes the processor to perform the method according to any one of claims 1-19.

[0175] Aspect 25 is a method for performing wireless communications at a base station, comprising: receiving a first random access message from a UE; sending a second random access message from the one or more TRPs to the UE in response to the first random access message; and at one or more TRPs, receiving a third random access message on at least one of the monitored multiple beams in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index.

[0176] In aspect 26, the method according to aspect 25 further comprises: the UE is served by the base station as a PCell, SCell or PSCell.

[0177] In aspect 27, the method according to aspect 25 or aspect 26 further includes: the base station monitoring the third random access message using resources granted to the UE in the second random access message.

[0178] In aspect 28, the method according to any one of aspects 25-27 further comprises: the second random access message comprising beam scanning information for the third random access message.

[0179] In aspect 29, the method according to any one of aspects 25-28 further includes: the base station receiving the first random access message and the third random access message using the same pattern of the multiple beams.

[0180] In aspect 30, the method according to any one of aspects 25-29 also includes: the first random access message is received using a first beam pattern of multiple beams, and the base station monitors the third random access message using a second different beam pattern of multiple beams.

[0181] In aspect 31, the method according to any one of aspects 25-30 also includes: in response to determining that the signal strength of one or more beams for the first random access message is lower than a threshold amount or receiving a report from the UE indicating a better beam than the beam used for the first random access message, indicating the second different beam mode to the UE in the second random access message.

[0182] In aspect 32, the method according to any one of aspects 25-31 further includes: the third random access message is one or more of TDM, FDM or SDM on multiple beams.

[0183] In aspect 33, the method according to any one of aspects 25-32 also includes: the second random access message includes a grant for the third random access message, and instructs the UE to use at least one of TDM, FDM or SDM to send the third random access message on the multiple beams.

[0184] In aspect 34, the method according to any one of aspects 25-33 further comprises: the grant for the third random access message further indicating a number of repetitions for the third random access message.

[0185] In aspect 35, the method according to any one of aspects 25-34 also includes: sending an indication of a beam set for a fourth random access message; and sending the fourth random access message from the one or more TRPs on the beam set.

[0186] In aspect 36, the method according to any one of aspects 25-35 further comprises: sending the fourth random access message on the set of beams using one or more of TDM, FDM or SDM.

[0187] In aspect 37, the method according to any one of aspects 25-36 further comprises: resources used for the fourth random access message are based on at least one of a beam pool index or a TRP index.

[0188] In aspect 38, the method according to any one of aspects 25-37 further includes: the base station sending the second random access message and the fourth random access message using the same beam set.

[0189] In aspect 39, the method according to any one of aspects 25-38 further comprises: the indication is sent in the second random access message.

[0190] In aspect 40, the method according to any one of aspects 25-39 further comprises: the set of beams used for sending the fourth random access message has a different beam configuration from the beams used for sending the second random access message.

[0191] In aspect 41, the method according to any one of aspects 25-40 also includes: the base station sends the indication in the PDCCH of the second random access message, and wherein the base station uses the beam set indicated by the indication to send the PDCCH or physical downlink shared channel of the fourth random access message.

[0192] In aspect 42, the method according to any one of aspects 25-41 further includes: the base station sends the indication in the PDCCH of the fourth random access message, and wherein the base station uses the beam set indicated in the PDCCH to send the PDSCH of the fourth random access message.

[0193] In aspect 43, the method according to any one of aspects 25-42 further comprises: receiving HARQ-ACK feedback in the PUCCH from the UE using TDM, FDM or SDM beam scanning.

[0194] In aspect 44, the method according to any one of aspects 25-43 further comprises: sending information for the TDM or FDM or SDM beam scanning in at least one of the control part of the second random access message or the fourth random access message.

[0195] Aspect 45 is a device for wireless communication, comprising: a unit for receiving a first random access message from a UE; a unit for sending a second random access message to the UE in response to the first random access message; and a unit for receiving a third random access message on at least one of a plurality of monitored beams in a beam scanning mode at one or more TRPs using resources based on a beam pool index or at least one of a TRP index.

[0196] In aspect 46, the apparatus according to aspect 45 further comprises means for performing the method according to any one of claims 26-44.

[0197] Aspect 47 is a device for wireless communication, comprising: a memory; at least one processor coupled to the memory, the memory and the at least one processor being configured to: receive a first random access message from a UE; send a second random access message to the UE in response to the first random access message; and at one or more TRPs, receive a third random access message on at least one of a plurality of monitored beams in a beam scanning mode using resources based on a beam pool index or at least one of a TRP index.

[0198] In aspect 48, the apparatus according to aspect 47 further comprises: the memory and the at least one processor are further configured to perform the method according to any one of claims 26-44.

[0199] Aspect 49 is a non-transitory computer-readable storage medium storing computer-executable code for wireless communication at a base station, which, when executed by a processor, causes the processor to perform a method according to any one of claims 25-44.

[0200] Aspect 51 is a method for performing wireless communications at a UE, comprising: sending a first random access message to a serving cell; receiving a second random access message from the serving cell in response to the first random access message; and sending a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving a fourth random access message on multiple beams (e.g., multiple receive beams) of the UE and using resources based on at least one of a beam pool index or a TRP index.

[0201] In aspect 52, the method according to aspect 51 further comprises: the serving cell comprises a PCell, a SCell or a PSCell.

[0202] In aspect 53, the method according to aspect 51 or aspect 52 further comprises: the third random access message is sent using resources granted in the second random access message for reception on multiple beams.

[0203] In aspect 54, the method according to any one of aspects 51-53 further comprises: the second random access message comprising beam scanning information for the third random access message.

[0204] In aspect 55, the method according to any one of aspects 51-54 further comprises: the first random access message and the third random access message are sent using the same pattern of the multiple beams.

[0205] In aspect 56, the method according to any one of aspects 51-55 also includes: the first random access message is sent using a first beam pattern of multiple beams, and the third random access message is sent using a second different beam pattern of multiple beams.

[0206] In aspect 57, the method according to any one of aspects 51-56 further comprises: transmitting the third random access message on the plurality of beams using at least one of TDM, FDM or SDM.

[0207] In aspect 58, the method according to any one of aspects 51-57 also includes: the second random access message includes a permission for the third random access message, and instructs the UE to use at least one of TDM, FDM or SDM to send the third random access message on the multiple beams.

[0208] In aspect 59, the method according to any one of aspects 51-58 further comprises: the grant for the third random access message further indicating a number of repetitions for the third random access message.

[0209] In aspect 60, the method according to any one of aspects 51-59 also includes: receiving an indication of a beam set for receiving a fourth random access message; and receiving the fourth random access message from the one or more TRPs of the serving cell on the beam set.

[0210] In aspect 61, the method according to any one of aspects 51-60 further includes: the fourth random access message is one or more of TDM, FDM or SDM performed on the beam set.

[0211] In aspect 62, the method according to any one of aspects 51-61 further comprises: resources used for the fourth random access message are based on at least one of a beam pool index or a TRP index.

[0212] In aspect 63, the method according to any one of aspects 51-62 further includes: the UE receiving the second random access message and the fourth random access message using the same beam set.

[0213] In aspect 64, the method according to any one of aspects 51-63 further comprises: the indication being received in the second random access message.

[0214] In aspect 65, the method according to any one of aspects 51-64 further comprises: the set of beams used for receiving the fourth random access message has a different beam configuration than the beams used for receiving the second random access message.

[0215] In aspect 66, the method according to any one of aspects 51-65 also includes: the indication is received in the PDCCH of the second random access message, and wherein the UE uses the beam set indicated by the indication to receive the PDCCH or physical downlink shared channel of the fourth random access message.

[0216] In aspect 67, the method according to any one of aspects 51-66 also includes: the indication is received in a PDCCH of the fourth random access message, and the UE receives the PDSCH of the fourth random access message using the beam set indicated in the PDCCH.

[0217] In aspect 68, the method according to any one of aspects 51-67 further comprises sending the HARQ-ACK feedback in the PUCCH using TDM or FDM or SDM beam scanning.

[0218] In aspect 69, the method according to any one of aspects 51-68 further comprises: receiving information for the TDM or FDM or SDM beam scanning in at least one of the control part of the second random access message or the fourth random access message.

[0219] Aspect 70 is an apparatus for wireless communication, comprising: a unit for sending a first random access message to one or more TRPs of a serving cell; a unit for receiving a second random access message from the serving cell in response to the first random access message; and a unit for sending a third random access message to the serving cell in a beam scanning mode for receiving a fourth random access message on multiple beams of the UE and using resources based on at least one of a beam pool index or a TRP index.

[0220] In aspect 71, the apparatus according to aspect 70 further comprises means for performing the method according to any one of claims 52-69.

[0221] Aspect 72 is a device for wireless communication, comprising: a memory; and at least one processor coupled to the memory, the memory and the at least one processor being configured to: send a first random access message to a serving cell; receive a second random access message from the serving cell in response to the first random access message; and send a third random access message to one or more TRPs of the serving cell in a beam scanning mode for receiving a fourth random access message on multiple beams of the UE and using resources based on at least one of a beam pool index or a TRP index.

[0222] In aspect 73, the apparatus according to aspect 72 further comprises: the memory and the at least one processor are further configured to perform the method according to any one of claims 52-69.

[0223] Aspect 74 is a non-transitory computer-readable storage medium storing computer-executable code for wireless communication, which, when executed by a processor, causes the processor to perform a method according to any one of claims 51-69.

[0224] Aspect 75 is a method for performing wireless communications at a base station, comprising: receiving a first random access message from a UE; sending a second random access message from the one or more TRPs to the UE in response to the first random access message; and receiving a third random access message at one or more TRPs in a beam scanning mode on at least one of a plurality of beams (e.g., a plurality of receiving beams) of the one or more TRPs monitored by the base station or the one or more TRPs of the base station using resources based on a beam pool index or at least one of the TRP indexes.

[0225] In aspect 76, the method according to aspect 75 further comprises: the UE is served by the base station as a PCell, SCell or PSCell.

[0226] In aspect 77, the method according to aspect 75 or aspect 76 further includes: the base station monitoring the third random access message using resources granted to the UE in the second random access message.

[0227] In aspect 78, the method according to any one of aspects 75-77 further comprises: the second random access message comprising beam scanning information for the third random access message.

[0228] In aspect 79, the method according to any one of aspects 75-78 further includes: the base station receives the first random access message and the third random access message using the same pattern of the multiple beams.

[0229] In aspect 80, the method according to any one of aspects 75-79 also includes: the first random access message is received using a first beam pattern of multiple beams, and the base station monitors the third random access message using a second different beam pattern of multiple beams.

[0230] In aspect 81, the method according to any one of aspects 75-80 also includes: in response to determining that the signal strength of one or more beams for the first random access message is lower than a threshold amount or receiving a report from the UE indicating a better beam than the beam used for the first random access message, indicating the second different beam mode to the UE in the second random access message.

[0231] In aspect 82, the method according to any one of aspects 75-81 also includes: the third random access message is one or more of TDM, FDM or SDM on multiple beams.

[0232] In aspect 83, the method according to any one of aspects 75-82 also includes: the second random access message includes a grant for the third random access message, and instructs the UE to use at least one of TDM, FDM or SDM to send the third random access message on the multiple beams.

[0233] In aspect 84, the method according to any one of aspects 75-83 further comprises: the grant for the third random access message further indicating a number of repetitions for the third random access message.

[0234] In aspect 85, the method according to any one of aspects 75-84 also includes: sending an indication of a beam set for a fourth random access message; and sending the fourth random access message from the one or more TRPs on the beam set.

[0235] In aspect 86, the method according to any one of aspects 75-85 further comprises sending the fourth random access message on the set of beams using one or more of TDM, FDM or SDM.

[0236] In aspect 87, the method according to any one of aspects 75-86 further comprises: resources used for the fourth random access message are based on at least one of a beam pool index or a TRP index.

[0237] In aspect 88, the method according to any one of aspects 75-87 further includes: the base station sending the second random access message and the fourth random access message using the same beam set.

[0238] In aspect 89, the method according to any one of aspects 75-88 further comprises: the indication is sent in the second random access message.

[0239] In aspect 90, the method according to any one of aspects 75-89 further comprises: the set of beams used for sending the fourth random access message has a different beam configuration than the beams used for sending the second random access message.

[0240] In aspect 91, the method according to any one of aspects 75-90 also includes: the base station sends the indication in the PDCCH of the second random access message, and wherein the base station uses the beam set indicated by the indication to send the PDCCH or physical downlink shared channel of the fourth random access message.

[0241] In aspect 92, the method according to any one of aspects 75-91 further includes: the base station sends the indication in the PDCCH of the fourth random access message, and wherein the base station uses the beam set indicated in the PDCCH to send the PDSCH of the fourth random access message.

[0242] In aspect 93, the method according to any one of aspects 75-92 further comprises: receiving HARQ-ACK feedback in the PUCCH from the UE using TDM, FDM or SDM beam scanning.

[0243] In aspect 94, the method according to any one of aspects 75-93 further comprises: sending information for the TDM or FDM or SDM beam scanning in at least one of the control parts of the second random access message or the fourth random access message.

[0244] Aspect 95 is a device for wireless communication, comprising: a unit for receiving a first random access message from a UE; a unit for sending a second random access message to the UE in response to the first random access message; and a unit for receiving a third random access message at one or more TRPs in a beam scanning mode on at least one of a plurality of beams monitored by the base station or the one or more TRPs of the base station using resources based on a beam pool index or at least one of the TRP indexes.

[0245] In aspect 96, the apparatus according to aspect 95 further comprises means for performing the method according to any one of claims 76-94.

[0246] Aspect 97 is a device for wireless communication, comprising: a memory; at least one processor coupled to the memory, the memory and the at least one processor being configured to: receive a first random access message from a UE; send a second random access message to the UE in response to the first random access message; and at one or more TRPs, receive a third random access message on at least one of a plurality of beams of the one or more TRPs monitored by the base station or the one or more TRPs of the base station in a beam scanning mode using resources based on at least one of a beam pool index or a TRP index.

[0247] In aspect 98, the apparatus according to aspect 97 further comprises: the memory and the at least one processor are further configured to perform the method according to any one of claims 76-94.

[0248] Aspect 99 is a non-transitory computer-readable storage medium storing computer-executable code for wireless communication at a base station, which, when executed by a processor, causes the processor to perform a method according to any one of claims 75-94.

[0249] It is to be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is an illustration of an exemplary method. It is to be understood that the specific order or hierarchy of the blocks in the process / flowchart may be rearranged based on design preferences. In addition, some blocks may be combined or omitted. The attached method claims provide the elements of the various blocks in an exemplary order and are not intended to be limited to the specific order or hierarchy provided.

[0250] Provide the previous description so that any person skilled in the art can practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the various aspects shown herein, but to be given the full scope consistent with the textual claims, wherein, unless explicitly stated so, the reference to the singular element is not intended to mean "one and only one", but "one or more". The word "exemplary" is used herein to mean "used as an example, instance or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred to other aspects or having advantages over other aspects. Unless otherwise explicitly stated, the term "some" refers to one or more. Combinations such as "at least one of A, B or C", "one or more of A, B or C", "at least one of A, B and C", "one or more of A, B and C", and "A, B, C or any combination thereof" include any combination of A, B and / or C, and may include multiples of A, multiples of B or multiples of C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B and C," "one or more of A, B and C," and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in the present disclosure that are known or later known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. In addition, the content disclosed herein is not intended to be dedicated to the public, regardless of whether such disclosure is explicitly recorded in the claims. The words "module," "mechanism," "element," "device," and the like may not be substitutes for the word "unit." Therefore, no claim element is to be interpreted as a functional unit unless the element is explicitly recorded using the phrase "unit for..."

Claims

1. A method for wireless communication at a user equipment (UE), comprising: Sending a first random access message to a serving cell; receiving, from the serving cell, a second random access message in response to the first random access message; as well as The third random access message is sent to one or more TRPs of the serving cell in a beam scanning mode for receiving on multiple beams and using resources of the beam scanning mode for the third random access message based on at least one of a beam pool index or a transmit receive point (TRP) index.

2. The method according to claim 1, wherein: The serving cell includes a primary cell (PCell), a secondary cell (SCell) or a primary secondary cell (PSCell).

3. The method according to claim 1, wherein: The UE sends the first random access message using a first beam pattern of multiple beams, and sends the third random access message using a second different beam pattern of multiple beams.

4. The method according to claim 1, further comprising: The third random access message is sent on the plurality of beams using at least one of time division multiplexing (TDM), frequency division multiplexing (FDM), or space division multiplexing (SDM).

5. The method according to claim 4, wherein: The second random access message includes a grant for the third random access message and indicates to the UE to use the at least one of TDM, FDM, or SDM to send the third random access message on the multiple beams.

6. The method according to claim 5, wherein: The grant for the third random access message further indicates a number of repetitions for the third random access message.

7. The method according to claim 1, further comprising: The first random access message and the third random access message are transmitted using the same pattern of the multiple beams.

8. The method according to claim 1, further comprising: receiving an indication of a beam set for receiving a fourth random access message; as well as The fourth random access message is received from the one or more TRPs of the serving cell on the beam set.

9. The method according to claim 8, further comprising: One or more of time division multiplexing (TDM), frequency division multiplexing (FDM), or space division multiplexing (SDM) are performed to receive the fourth random access message on the beam set.

10. The method according to claim 8, wherein: The resources used for the fourth random access message are based on at least one of the beam pool index or the TRP index.

11. The method according to claim 8, further comprising: The second random access message and the fourth random access message are received using the same beam set.

12. The method according to claim 8, wherein: The indication is received in the second random access message, wherein the set of beams used to receive the fourth random access message includes a different beam configuration than a beam used to receive the second random access message.

13. The method according to claim 8, wherein: The UE receives the indication in a physical downlink control channel (PDCCH) of the second random access message, and wherein the UE uses the beam set indicated by the indication to receive the PDCCH or physical downlink shared channel (PDSCH) of the fourth random access message.

14. The method according to claim 8, wherein: The UE receives the indication in a physical downlink control channel (PDCCH) of the fourth random access message, and the UE receives a physical downlink shared channel (PDSCH) of the fourth random access message using the beam set indicated in the PDCCH.

15. The method according to claim 8, further comprising: Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) feedback is sent in the Physical Uplink Control Channel (PUCCH) using Time Division Multiplexing (TDM), Frequency Division Multiplexing (FDM), or Space Division Multiplexing (SDM) beam scanning.

16. The method according to claim 15, further comprising: Information for the TDM, FDM or SDM beam scanning is received in at least one of a control part in the second random access message or the fourth random access message.

17. An apparatus for wireless communication at a user equipment (UE), comprising: means for sending a first random access message to one or more transmit reception points (TRPs) of a serving cell; means for receiving, from the serving cell, a second random access message in response to the first random access message; as well as A unit for sending the third random access message to the serving cell in a beam scanning mode for receiving on multiple beams and using resources of the beam scanning mode for the third random access message based on at least one of a beam pool index or a TRP index.

18. A method for wireless communication at a base station, comprising: receiving a first random access message from a user equipment (UE); sending a second random access message to the UE in response to the first random access message; as well as At one or more transmit receive points (TRPs), the third random access message is received in a beam scanning mode on at least one of the monitored multiple beams using resources in a beam scanning mode for a third random access message based on at least one of a beam pool index or a TRP index.

19. The method according to claim 18, further comprising: The UE is served as a primary cell (PCell), a secondary cell (SCell) or a primary secondary cell (PSCell).

20. The method according to claim 18, wherein: The base station receives the first random access message using a first beam pattern of multiple beams, and the base station monitors the third random access message using a second different beam pattern of multiple beams.

21. The method according to claim 20, further comprising: In response to determining that the signal strength of one or more beams for the first random access message is below a threshold or receiving a report from the UE indicating a better beam than the beam used for the first random access message, indicating the second different beam pattern to the UE in the second random access message.

22. The method according to claim 18, wherein: The third random access message is one or more of time division multiplexing (TDM), frequency division multiplexing (FDM) or space division multiplexing (SDM) on the multiple beams, wherein the second random access message includes a grant for the third random access message and indicates to the UE to use at least one of TDM, FDM or SDM to send the third random access message on the multiple beams.

23. The method of claim 18, further comprising: sending an indication of a beam set for a fourth random access message; as well as The fourth random access message is sent from the one or more TRPs on the beam set.

24. The method according to claim 23, further comprising: The fourth random access message is sent on the set of beams using one or more of time division multiplexing (TDM), frequency division multiplexing (FDM), or space division multiplexing (SDM).

25. The method according to claim 23, wherein: The resources used for the fourth random access message are based on at least one of the beam pool index or the TRP index.

26. The method of claim 23, further comprising: The second random access message and the fourth random access message are sent using the same beam set.

27. The method according to claim 23, wherein: The base station sends the indication in the second random access message, wherein the beam set used to send the fourth random access message includes a beam configuration different from a beam used to send the second random access message.

28. The method of claim 23, wherein: The base station sends the indication in a physical downlink control channel (PDCCH) of the second random access message, and uses the beam set indicated by the indication to send the PDCCH or physical downlink shared channel (PDSCH) of the fourth random access message, or wherein the base station sends the indication in the PDCCH of the fourth random access message and uses the beam set indicated in the PDCCH of the fourth random access message to send the PDSCH of the fourth random access message.

29. The method of claim 23, further comprising: receiving a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback in a physical uplink control channel (PUCCH) from the UE using time division multiplexing (TDM), frequency division multiplexing (FDM), or spatial division multiplexing (SDM) beam scanning; as well as Information for the TDM, FDM or SDM beam scanning is transmitted in at least one of the second random access message or the control part of the fourth random access message.

30. An apparatus for wireless communication at a base station, comprising: means for receiving a first random access message from a user equipment (UE); means for sending a second random access message to the UE in response to the first random access message; as well as A unit for receiving the third random access message on at least one of a plurality of monitored beams in a beam scanning mode using resources for the third random access message in a beam scanning mode based on at least one of a beam pool index or a TRP index at one or more transmit receive points (TRPs).

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