Beam indication during the random access channel (RACH) procedure

Abstract

Certain aspects of the present disclosure provide techniques for random access channel (RACH) communications.For example, certain aspects provide a method for providing an indication of a preferred beam for subsequent (uplink or downlink) transmissions via a first uplink transmission.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application S / N. 62 / 534,153, filed on July 18, 2017, and U.S. Patent Application No. 16 / 037,693, filed on July 17, 2018, both of which are incorporated herein by reference in their entirety.

[0003] introduction

[0004] Aspects of the present disclosure relate generally to wireless communications, and more particularly to random access channel (RACH) communications.

[0005] 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 (e.g., bandwidth, transmit power). Examples of such multiple access technologies include Long Term Evolution (LTE) systems, 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.

[0006] In some examples, a wireless multiple access communication system may include several base stations, each base station supporting communication of multiple communication devices (also referred to as user equipment (UE)) simultaneously. In an LTE or LTE-A network, a set of one or more base stations may define an evolved B node (eNB). In other examples (e.g., in a next generation or 5G network), a wireless multiple access communication system may include several distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with several central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), wherein a set of one or more distributed units in communication with the central unit may define an access node (e.g., new radio base stations (NR BSs), new radio B nodes (NR NBs), network nodes, 5G NBs, gNBs, etc.). A base station or DU may communicate with a group of UEs on a downlink channel (e.g., for transmission from a base station to a UE) and an uplink channel (e.g., for transmission from a UE to a base station or a distributed unit).

[0007] 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 of an emerging telecommunication standard is called New Radio (NR), for example, 5G radio access. It is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, improving services, utilizing new spectrum, and better integrating with other open standards using OFDMA with cyclic prefix (CP) on downlink (DL) and uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

[0008] However, as the demand for mobile broadband access continues to grow, there is a need for further improvements in NR technology. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

[0009] Brief Overview

[0010] The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed in the appended claims, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "Detailed Description," it will be understood how the features of the present disclosure provide advantages including improved communication between access points and stations in a wireless network.

[0011] Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE). The method generally includes: determining at least one preferred beam for at least one subsequent transmission based on one or more downlink signals and an expected time of the at least one subsequent transmission, and providing an indication of the preferred beam via a first uplink transmission.

[0012] Certain aspects of the present disclosure provide a method for wireless communication that may be performed by a network entity. The method generally includes: signaling configuration information indicating partitioning of different resource sets for indicating different preferred beams, receiving from a user equipment (UE) a first uplink transmission sent using one of the resource sets, and determining at least one preferred beam for at least one subsequent transmission based on the partition and the resource set used to send the first uplink transmission.

[0013] Aspects generally include methods, apparatus, systems, computer-readable media, and processing systems substantially as described herein with reference to and as illustrated by the accompanying figures.

[0014] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to understand in detail the manner in which the above-stated features of the present disclosure are used, a more particular description of the content briefly summarized above may be made with reference to various aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only certain typical aspects of the present disclosure and are not to be considered limiting of its scope, as the description may admit to other equally effective aspects.

[0017] Figure 1 is a block diagram conceptually illustrating an example telecommunications system in accordance with certain aspects of the present disclosure.

[0018] Figure 2 is a block diagram illustrating an example logical architecture of a distributed RAN in accordance with certain aspects of the present disclosure.

[0019] Figure 3 is a diagram illustrating an example physical architecture of a distributed RAN in accordance with certain aspects of the present disclosure.

[0020] Figure 4 is a block diagram conceptually illustrating a design of an example BS and user equipment (UE) in accordance with certain aspects of the present disclosure.

[0021] Figure 5 is a diagram illustrating an example for implementing a communication protocol stack in accordance with certain aspects of the present disclosure.

[0022] Figure 6 An example of a frame format for a New Radio (NR) system is illustrated in accordance with certain aspects of the present disclosure.

[0023] Figure 7 Examples of the use of different types of beams in accordance with certain aspects of the present disclosure are illustrated.

[0024] Figure 8 A call flow diagram illustrating an example four-step random access channel (RACH) procedure in accordance with certain aspects of the present disclosure.

[0025] Fig. 9 Call flow diagram illustrating an example two-step RACH procedure in accordance with certain aspects of the present disclosure.

[0026] Fig.10

[0013] Example operations for wireless communications by a user equipment (UE) are illustrated, in accordance with certain aspects of the present disclosure.

[0027] Fig.11

[0013] Example operations for wireless communications by a network entity are illustrated in accordance with certain aspects of the present disclosure.

[0028] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized in other aspects without specific recitation.

[0029] Detailed Description

[0030] Aspects of the present disclosure provide apparatus, methods, processing systems, and computer-readable media for random access channel (RACH) communications.

[0031] Certain aspects of the present disclosure may be applied to New Radio (NR) (new radio access technology or 5G technology). NR may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., more than 80 MHz), millimeter wave (mmW) targeting high carrier frequency (e.g., 60 GHz), massive MTC (mMTC) targeting non-backward compatible MTC technology, and / or mission critical services targeting ultra-reliable low latency communication (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTIs) to meet corresponding quality of service (QoS) requirements. In addition, these services can coexist in the same subframe.

[0032] The following description provides examples rather than limiting the scope, applicability or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements discussed without departing from the scope of the present disclosure. Various examples may appropriately omit, replace, or add various procedures or components. For example, the described method may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, the features described with reference to some examples may be combined in some other examples. For example, any number of aspects set forth herein may be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionality, or structures and functionality as supplements to the various aspects of the present disclosure set forth herein or in addition. It should be understood that any aspect of the present disclosure disclosed herein may be implemented by one or more elements of the claims. The wording "exemplary" is used herein to mean used as "example, instance, or explanation". Any aspect described as "exemplary" herein is not necessarily to be interpreted as being superior to or superior to other aspects.

[0033] The technology described herein can be used for various wireless communication networks, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network can implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes other variants of Wideband CDMA (WCDMA) and CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network can implement radio technologies such as Global System for Mobile Communications (GSM). An OFDMA network can implement radio technologies such as NR (e.g., 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). NR is an emerging wireless communication technology being developed in collaboration with the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and Advanced LTE (LTE-A) are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called "3rd Generation Partnership Project" (3GPP). Cdma2000 and UMB are described in documents from an organization called "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, although various aspects may be described herein using terms commonly associated with 3G and / or 4G wireless technologies, various aspects of the present disclosure may be applied in communication systems based on other generations, such as 5G and later generations, including NR technologies.

[0034] Example Wireless Communication System

[0035] Figure 1 An example wireless network 100 is illustrated in which aspects of the present disclosure may be performed. For example, the wireless network may be a new radio (NR) or 5G network. The NR wireless communication system may employ beams, where a BS and a UE communicate via an active beam. As described herein, the BS may monitor the active beam using measurements of reference signals (e.g., MRS, CSI-RS, synch) transmitted via a reference beam.

[0036] The UE 120 may be configured to perform the operations 1000 and methods described herein for detecting a mobility event based at least in part on mobility parameters associated with a beam set. The BS 110 may include a transmit reception point (TRP), a B node (NB), a 5G NB, an access point (AP), a new radio (NR) BS, etc. The BS 110 may be configured to perform the operations 900 and methods described herein for configuring beam sets and mobility parameters associated with each of the beam sets. The BS may receive an indication of a detected mobility event based on the mobility parameters and may make a decision regarding mobility management of the UE based on the event trigger.

[0037] like Figure 1 As explained in , the wireless network 100 may include several BSs 110 and other network entities. A BS may be a station that communicates with a UE. Each BS 110 may provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to the coverage area of ​​a B node and / or a B node subsystem that serves the coverage area, depending on the context in which the term is used. In the NR system, the terms "cell" and gNB, B node, 5G NB, AP, NR BS, NR BS, or TRP may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of ​​the cell may move according to the location of a mobile base station. In some examples, base stations may be interconnected to each other and / or to one or more other base stations or network nodes (not shown) in the wireless network 100 via various types of backhaul interfaces (such as direct physical connections, virtual networks, or analogs using any suitable transport networks).

[0038] In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a specific radio access technology (RAT) and may operate on one or more frequencies. RAT may also be referred to as radio technology, air interface, etc. Frequency may also be referred to as carrier, frequency channel, etc. Each frequency may support a single RAT in a given geographic area to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

[0039] A BS may provide communication coverage for macro cells, pico cells, femto cells, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions. A femto cell may cover a relatively small geographic area (e.g., a residence) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in a residence, etc.). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1 In the example shown in FIG. 1 , BSs 110a, 110b, and 110c may be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x may be a pico BS for pico cell 102x. BSs 110y and 110z may be femto BSs for femto cells 102y and 102z, respectively. A BS may support one or more (e.g., three) cells.

[0040] The wireless network 100 may also include a relay station. A relay station is a station that receives transmissions of data and / or other information from an upstream station (e.g., a BS or a UE) and sends transmissions of the data and / or other information to a downstream station (e.g., a UE or a BS). A relay station may also be a UE that relays transmissions for other UEs. Figure 1 In the example shown in , a relay station 110r may communicate with a BS 110a and a UE 120r to facilitate communication between the BS 110a and the UE 120r. A relay station may also be referred to as a relay BS, a relay, or the like.

[0041] The wireless network 100 may be a heterogeneous network including different types of BSs (e.g., macro BSs, pico BSs, femto BSs, relays, etc.). These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network 100. For example, a macro BS may have a high transmit power level (e.g., 20 watts), while a pico BS, a femto BS, and a relay may have a lower transmit power level (e.g., 1 watt).

[0042] Wireless network 100 may support synchronous or asynchronous operation. For synchronous operation, each BS may have similar frame timing, and transmissions from different BSs may be roughly aligned in time. For asynchronous operation, each BS may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

[0043] A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. Network controller 130 may communicate with BSs 110 via a backhaul. BSs 110 may also communicate with each other, directly or indirectly, for example, via a wireless or wired backhaul.

[0044] UE 120 (e.g., 120x, 120y, etc.) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer premises equipment (CPE), cellular phone, smart phone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet device, camera, gaming device, netbook, smartbook, ultrabook, medical device or medical equipment, biometric sensor / device, wearable device (such as smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart necklace, etc.)), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, global positioning system device, or any other suitable device configured to communicate via wireless or wired medium. Some UEs may be considered as evolved or machine type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., which can communicate with a BS, another device (e.g., a remote device), or some other entity. A wireless node can provide connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network), for example, via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices.

[0045] exist Figure 1 In FIG. 1 , a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on a downlink and / or uplink. A dashed line with double arrows indicates interfering transmissions between a UE and a BS.

[0046] Some wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also often referred to as frequency modulation, frequency bins, etc. Each subcarrier can be modulated with data. In general, modulation symbols are sent in the frequency domain under OFDM and in the time domain under SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the spacing of subcarriers can be 15kHz, and the minimum resource allocation (called a 'resource block') can be 12 subcarriers (or 180kHz). Therefore, for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), the nominal FFT size can be equal to 128, 256, 512, 1024, or 2048, respectively. The system bandwidth can also be divided into subbands. For example, a subband may cover 1.08 MHz (ie, 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10, or 20 MHz, respectively.

[0047] Although aspects of the examples described herein may be associated with LTE technology, aspects of the present disclosure may be applicable to other wireless communication systems, such as NR.

[0048] NR can utilize OFDM with CP on the uplink and downlink and includes support for half-duplex operation using TDD. A single component carrier bandwidth of 100MHz can be supported. NR resource blocks can span 12 subcarriers with a subcarrier bandwidth of 75kHz over a duration of 0.1ms. Each radio frame may include 50 subframes with a length of 10ms. Therefore, each subframe may have a length of 0.2ms. Each subframe may indicate the link direction (i.e., DL or UL) used for data transmission, and the link direction for each subframe may be switched dynamically. Each subframe may include DL / UL data and DL / UL control data. The UL and DL subframes for NR may be referred to below. Figure 6 and 7 Described in more detail. Beamforming can be supported and the beam direction can be dynamically configured. MIMO transmission with precoding can also be supported. The MIMO configuration in the DL can support up to 8 transmit antennas (multi-layer DL transmission with up to 8 streams) and up to 2 streams per UE. Multi-layer transmission of up to 2 streams per UE can be supported. Up to 8 serving cells can be used to support the aggregation of multiple cells. Alternatively, in addition to being based on OFDM, NR can support different air interfaces. The NR network may include entities such as CU and / or DU.

[0049] In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication between some or all devices and equipment within its service area or cell. In the present disclosure, as further discussed below, a scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, a subordinate entity utilizes resources allocated by a scheduling entity. A base station is not the only entity that can be used as a scheduling entity. That is, in some examples, a UE may be used as a scheduling entity, thereby scheduling resources for one or more subordinate entities (e.g., one or more other UEs). In this example, the UE is acting as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication. A UE may act as a scheduling entity in a peer-to-peer (P2P) network and / or in a mesh network. In a mesh network example, UEs may optionally communicate directly with each other in addition to communicating with a scheduling entity.

[0050] Thus, in a wireless communication network having scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate using the scheduled resources.

[0051] As mentioned above, the RAN may include a CU and a DU. A NR BS (e.g., a gNB, a 5G Node B, a Node B, a Transmit Receiving Point (TRP), an Access Point (AP)) may correspond to one or more BSs. An NR cell may be configured as an access cell (ACell) or a data-only cell (DCell). For example, a RAN (e.g., a central unit or a distributed unit) may configure these cells. A DCell may be a cell used for carrier aggregation or dual connectivity but not for initial access, cell selection / reselection, or switching. In some cases, a DCell may not transmit a synchronization signal—in some cases, a DCell may transmit an SS. The NR BS may transmit a downlink signal to the UE to indicate the cell type. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine the NR BS to be considered for cell selection, access, switching, and / or measurement based on the indicated cell type.

[0052] Figure 2 An example logical architecture of a distributed radio access network (RAN) 200 is illustrated, which may be Figure 1206. The 5G access node 206 may include an access node controller (ANC) 202. The ANC may be a central unit (CU) of the distributed RAN 200. The backhaul interface to the next generation core network (NG-CN) 204 may be terminated at the ANC. The backhaul interface to the adjacent next generation access node (NG-AN) may be terminated at the ANC. The ANC may include one or more TRPs 208 (which may also be referred to as BS, NR BS, B node, 5G NB, AP or some other term). As described above, TRP may be used interchangeably with "cell".

[0053] TRP 208 may be a DU. The TRP may be connected to one ANC (ANC 202) or more than one ANC (not illustrated). For example, for RAN sharing, Radio as a Service (RaaS), and service-specific AND deployments, the TRP may be connected to more than one ANC. The TRP may include one or more antenna ports. The TRP may be configured to serve traffic to the UE individually (e.g., dynamically selected) or jointly (e.g., joint transmission).

[0054] The local architecture 200 can be used to illustrate the fronthaul definition. The architecture can be defined to support fronthaul solutions across different deployment types. For example, the architecture can be based on transport network capabilities (e.g., bandwidth, latency, and / or jitter).

[0055] The architecture may share features and / or components with LTE. According to various aspects, the next generation AN (NG-AN) 210 may support dual connectivity with NR. For LTE and NR, the NG-AN may share a common fronthaul.

[0056] The architecture may enable collaboration between and among TRPs 208. For example, collaboration may exist within a TRP and / or across TRPs via ANC 202. According to various aspects, an inter-TRP interface may not be required / existent.

[0057] According to various aspects, dynamic configuration of split logic functions may exist within architecture 200. Figure 5 Described in more detail, a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a medium access control (MAC) layer, and a physical (PHY) layer may be adaptively placed at a DU or CU (e.g., at a TRP or ANC, respectively). According to certain aspects, a BS may include a central unit (CU) (e.g., ANC 202) and / or one or more distributed units (e.g., one or more TRPs 208).

[0058] Figure 3An example physical architecture of a distributed RAN 300 according to aspects of the present disclosure is illustrated. A centralized core network unit (C-CU) 302 may host core network functions. The C-CU may be centrally deployed. C-CU functionality may be offloaded (e.g., to Advanced Wireless Services (AWS)) in an effort to handle peak capacity.

[0059] A centralized RAN unit (C-RU) 304 may host one or more ANC functions. Optionally, the C-RU may host core network functions locally. The C-RU may have a distributed deployment. The C-RU may be closer to the network edge.

[0060] The DU 306 may host one or more TRPs (edge ​​node (EN), edge unit (EU), radio head (RH), smart radio head (SRH), etc.) The DU may be located at the edge of the network with radio frequency (RF) functionality.

[0061] Figure 4 Explained Figure 1 10 and UE 120, which may be used to implement various aspects of the present disclosure. The BS may include a TRP. One or more components of the BS 110 and UE 120 may be used to practice various aspects of the present disclosure. For example, the antenna 452, Tx / Rx 454, processors 466, 458, 464 and / or controller / processor 480 of the UE 120, and / or the antenna 434, processors 420, 430, 438 and / or controller / processor 440 of the BS 110 may be used to perform the operations described herein and with reference to Figure 9-10 Explanation of the operation.

[0062] Figure 4 It shows that it can be Figure 1 1 and 120. For a constrained association scenario, base station 110 may be Figure 1 1. The macro BS 110c in FIG. 1 may be a macro BS 110c, and the UE 120 may be a UE 120y. The base station 110 may also be some other type of base station. The base station 110 may be equipped with antennas 434a to 434t, and the UE 120 may be equipped with antennas 452a to 452r.

[0063] At the base station 110, the transmit processor 420 may receive data from the data source 412 and control information from the controller / processor 440. The control information may be used for a physical broadcast channel (PBCH), a physical control format indicator channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH), etc. The data may be used for a physical downlink shared channel (PDSCH), etc. The processor 420 may process (e.g., encode and symbol map) the data and the control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols (e.g., for PSS, SSS, and cell-specific reference signals (CRS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, and / or reference symbols, where applicable, and may provide output symbol streams to modulators (MODs) 432a to 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 432 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 432a through 432t may be transmitted via antennas 434a through 434t, respectively.

[0064] At the UE 120, antennas 452a to 452r may receive downlink signals from the base station 110 and may provide received signals to demodulators (DEMODs) 454a to 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 454 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 456 may obtain received symbols from all demodulators 454a to 454r, perform MIMO detection on the received symbols where applicable, and provide detected symbols. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 460, and provide decoded control information to a controller / processor 480.

[0065] On the uplink, at the UE 120, a transmit processor 464 may receive and process data from a data source 462 (e.g., for a physical uplink shared channel (PUSCH)) and control information from a controller / processor 480 (e.g., for a physical uplink control channel (PUCCH)). The transmit processor 464 may also generate reference symbols for a reference signal. The symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466, if applicable, further processed by demodulators 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to the base station 110. At the BS 110, uplink signals from the UE 120 may be received by the antenna 434, processed by the modulator 432, detected by the MIMO detector 436, if applicable, and further processed by the receive processor 438 to obtain decoded data and control information sent by the UE 120. Receive processor 438 may provide decoded data to data sink 439 and decoded control information to controller / processor 440 .

[0066] Controllers / processors 440 and 480 may direct operations at base station 110 and UE 120, respectively. Processor 440 and / or other processors and modules at base station 110 may perform or direct the execution of, for example, the functional blocks illustrated in the various figures, and / or other processes for the techniques described herein. Processor 480 and / or other processors and modules at UE 120 may also perform or direct the execution of corresponding / supplementary processes for the techniques described herein and as illustrated in the various figures. Memories 442 and 482 may store data and program codes for BS 110 and UE 120, respectively. Scheduler 444 may schedule UEs for data transmission on the downlink and / or uplink.

[0067] Figure 5 A diagram 500 showing an example for implementing a communication protocol stack according to various aspects of the present disclosure is illustrated. The illustrated communication protocol stack may be implemented by a device operating in a 5G system. Diagram 500 illustrates a communication protocol stack including a radio resource control (RRC) layer 510, a packet data convergence protocol (PDCP) layer 515, a radio link control (RLC) layer 520, a media access control (MAC) layer 525, and a physical (PHY) layer 530. In various examples, these layers of the protocol stack may be implemented as separate software modules, parts of a processor or ASIC, parts of non-co-located devices connected by a communication link, or various combinations thereof. Co-located and non-co-located implementations may be used, for example, in a protocol stack for a network access device (e.g., AN, CU, and / or DU) or a UE.

[0068] The first option 505-a illustrates a split implementation of the protocol stack, where the implementation of the protocol stack is performed on a centralized network access device (e.g., Figure 2 ANC 202 in the system) and distributed network access equipment (e.g., Figure 2 In the first option 505-a, the RRC layer 510 and the PDCP layer 515 may be implemented by a central unit, while the RLC layer 520, the MAC layer 525, and the PHY layer 530 may be implemented by the DU. In various examples, the CU and the DU may be co-located or non-co-located. The first option 505-a may be useful in a macro cell, a micro cell, or a pico cell deployment.

[0069] The second option 505-b shows a unified implementation of the protocol stack, where the protocol stack is implemented in a single network access device (e.g., access node (AN), new radio base station (NR BS), new radio node B (NR NB), network node (NN), etc.). In the second option, the RRC layer 510, the PDCP layer 515, the RLC layer 520, the MAC layer 525, and the PHY layer 530 may each be implemented by the AN. The second option 505-b may be useful in femtocell deployment.

[0070] Regardless of whether the network access device implements part or all of the protocol stack, the UE may implement the entire protocol stack (eg, the RRC layer 510, the PDCP layer 515, the RLC layer 520, the MAC layer 525, and the PHY layer 530).

[0071] Figure 6 6 is a diagram showing an example of a frame format 600 for NR. The transmission timeline of each of the downlink and uplink may be divided into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be divided into 10 subframes with indices 0 to 9, each subframe being 1 ms. Each subframe may include a variable number of slots, depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols), depending on the subcarrier spacing. An index may be assigned to the symbol period in each slot. A mini slot, which may be referred to as a subslot structure, refers to a transmission time interval having a duration less than a slot (e.g., 2, 3, or 4 symbols).

[0072] Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission, and the link direction for each subframe may be switched dynamically. The link direction may be based on the slot format. Each slot may include DL / UL data and DL / UL control information.

[0073] In NR, a synchronization signal (SS) block is transmitted. The SS block includes PSS, SSS, and two-symbol PBCH. The SS block can be in a fixed time slot position (such as Figure 6 ) is transmitted in the codewords 0-3 shown in . PSS and SSS can be used by UE for cell search and acquisition. PSS can provide half-frame timing, and SS can provide CP length and frame timing. PSS and SSS can provide cell identity. PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frames, SS burst set periodicity, system frame number, etc. SS blocks can be organized into SS bursts to support beam sweeping. Further system information (such as remaining minimum system information (RMSI), system information block (SIB), other system information (OSI)) can be transmitted on the physical downlink shared channel (PDSCH) in certain subframes.

[0074] The UE may operate in various radio resource configurations, including a configuration associated with transmitting a pilot using a dedicated resource set (e.g., a radio resource control (RRC) dedicated state, etc.), or a configuration associated with transmitting a pilot using a shared resource set (e.g., an RRC shared state, etc.). When operating in the RRC dedicated state, the UE may select a dedicated resource set for transmitting a pilot signal to the network. When operating in the RRC shared state, the UE may select a shared resource set for transmitting a pilot signal to the network. In either case, the pilot signal transmitted by the UE may be received by one or more network access devices (such as an AN, or a DU, or parts thereof). Each receiving network access device may be configured to receive and measure a pilot signal transmitted on a shared resource set, and also receive and measure a pilot signal transmitted on a dedicated resource set allocated to the UE, wherein the network access device is a member of a monitoring network access device set for the UE. One or more receiving network access devices or a CU to which (s) receiving network access devices transmit pilot signal measurements may use these measurements to identify a serving cell of the UE or initiate a change in a serving cell for one or more UEs.

[0075] Example mmWave System

[0076] As used herein, the term millimeter wave generally refers to a band of spectrum in very high frequencies, such as 28 GHz. Such frequencies can provide very large bandwidths capable of delivering multi-Gbps data rates, as well as opportunities for extremely dense spatial reuse for increased capacity. Traditionally, these higher frequencies have not been robust enough for indoor / outdoor mobile broadband applications due to high propagation losses and susceptibility to obstruction (e.g., from buildings, humans, etc.).

[0077] Despite these challenges, at the higher frequencies where mmWave operates, the small wavelength enables the use of a large number of antenna elements in a relatively small form factor. This characteristic of mmWave can be exploited to form narrow directional beams that can send and receive more energy, which can help overcome propagation / path loss challenges.

[0078] These narrow directional beams can also be used for spatial reuse. This is one of the key drivers for using mmWave for mobile broadband services. In addition, non-line-of-sight (NLOS) paths (e.g., reflections from nearby buildings) can have very large energy, providing an alternative path when the line-of-sight (LOS) path is blocked. Aspects of the present disclosure can take advantage of such directional beams, for example, by using them for RACH communications.

[0079] Figure 7 700 according to various aspects of the present disclosure. A BS and a UE may communicate using an active beam set. An active beam may refer to a BS and a UE beam pair that is used to transmit data and control channels. A data beam may be used to transmit data, while a control beam may be used to transmit control information. Figure 7 As illustrated in , the data beam BS-A1 may be used to transmit DL data, while the control beam BS-A2 may be used to transmit DL control information.

[0080] The BS may monitor the beam using beam measurements and feedback from the UE. For example, the BS may monitor the active beam using a DL reference signal. The BS may transmit a DL RS, such as a measurement reference signal (MRS), a channel state information reference signal (CSI-RS), or a synchronization (synch) signal. The UE may report to the BS the reference signal received power (RSRP) associated with the received reference signal. In this way, the BS may monitor the active beam.

[0081] Example Random Access Channel (RACH) Procedure

[0082] A random access channel (RACH) is a channel that can be shared by multiple UEs and can be used by these UEs to access a network for communication. For example, RACH can be used for call setup and access to a network for data transmission. In some cases, RACH can be used for initial access to a network when a UE switches from a radio resource control (RRC) connected idle mode to an active mode, or when switching in an RRC connected mode. In addition, RACH can be used for downlink (DL) and / or uplink (UL) data arrival when the UE is in RRC idle or RRC inactive mode, and when reestablishing a connection with the network. Certain aspects of the present disclosure provide multiple RACH procedures and techniques for selecting a RACH procedure for communication.

[0083] Figure 8 8 is a timing diagram (or "call flow diagram") 800 illustrating an example four-step RACH procedure in accordance with certain aspects of the present disclosure. A first message (MSG1) may be sent from UE 120 to eNB 110a and eNB 110b on a physical random access channel (PRACH). In this case, MSG1 may include only a RACH preamble. At least one of eNB 110a or eNB 110b may respond with a random access response (RAR) message (MSG2), which may include an identifier (ID) of the RACH preamble, a timing advance (TA), an uplink grant, a cell radio network temporary identifier (C-RNTI), and a backoff indicator. As illustrated, MSG2 may include a PDCCH communication that includes control information regarding subsequent communications on a PDSCH. In response to MSG2, MSG3 is transmitted from UE 120 to eNB 110a on a PUSCH. MSG2 may include an RRC connection request, a tracking area update, and a scheduling request. The eNB 110a then responds with MSG4, which may include a contention resolution message.

[0084] Fig. 9 9 is a timing diagram 900 illustrating an example two-step RACH procedure in accordance with certain aspects of the present disclosure. A first enhanced message (eMSG1) may be sent from UE 120 to eNB 110a and eNB 110b on an enhanced physical random access channel (ePRACH). In this case, eMSG1 may include a RACH preamble for random access and a demodulation reference signal (RS) for RACH payload demodulation. eMSG1 may also include a RACH message including a UE-ID and other signaling information, such as a buffer status report (BSR) or a scheduling request (SR). At least one eNB 110a or eNB 110b may respond with a random access response (RAR) message (eMSG2), which may include an ID of the RACH preamble, a timing advance (TA), a backoff indicator, a contention resolution message, an UL / DL grant, and a transmit power control (TPC) command.

[0085] Example beam indication during RACH procedure

[0086] Certain aspects of the present disclosure generally relate to beam selection and indicating one or more preferred beams to be used for subsequent (uplink and / or downlink) messages (eg, subsequent transmissions or retransmissions), for example, via an uplink transmission of a RACH procedure.

[0087] In NR deployments, the RACH procedure may require beam association between the beam used by the UE for UL transmission and the beam used for DL ​​synchronization channel transmission. The SS signal (such as Figure 6 ) (e.g., sending downlink signals via sweeping across multiple beams). Generally speaking, the UE will transmit Msg1 using a beam selected based on the SS beam (e.g., one swept beam of the corresponding SS with the best reception quality among the swept beams).

[0088] In some cases, all messages after Msg1 (e.g., Msg2, Msg3, and Msg4 for 4-step RACH, and ACK for Msg4) may be based on the same beam. This may not be ideal, especially in situations where channel conditions change significantly in the time period between the transmission of these messages (e.g., high mobility scenarios such as high-speed trains). Including a training beam in Msg2 (whose strength may be reported in Msg3) may help improve Msg4 beam selection. Similarly, Msg3 may include a training beam, based on which Msg4 may configure the beam for future transmissions.

[0089] Unfortunately, in some scenarios (such as high-speed trains or situations with asymmetry between uplink and downlink), the turnaround time to react to beam training can be a limitation. Aspects of the present disclosure allow the UE to report not only the current preferred beam that the UE has selected based on the current location or channel conditions, but also to indicate the beam that is expected to be preferred on subsequent transmissions (e.g., based on mobility and the expected time of subsequent transmissions).

[0090] Aspects of the present disclosure provide techniques for providing an indication of beams for subsequent transmissions that may help address such scenarios. For example, in some cases, the first transmission of a RACH procedure (e.g., Msg1) may indicate the preferred beam(s) for subsequent transmissions (e.g., Msg2, other RACH messages, or even post-RACH messages after the RACH procedure is completed). The preferred beam(s) may be determined based on the swept downlink transmission and the expected time of the subsequent transmission(s).

[0091] Fig.10 Illustrated are example operations 1000 for wireless communications in accordance with certain aspects of the present disclosure. In certain aspects, operations 1000 may be performed by a UE, such as UE 120.

[0092] Operations 1000 begin by determining at least one preferred beam for at least one subsequent transmission based on one or more downlink signals and an expected time of the at least one subsequent transmission, at block 1002. At block 1004, the UE provides an indication of the preferred beam via a first uplink transmission.

[0093] Fig.11 Illustrated are example operations 1100 for wireless communications in accordance with certain aspects of the present disclosure. In certain aspects, operations 1100 may be performed by an eNB, such as eNB 110a (or gNB) engaging in a RACH procedure with a UE performing operations 1000 described above.

[0094] Operations 1100 begin at block 1102 by signaling configuration information indicating partitioning of different resource sets for indicating different preferred beams. At block 1104, the eNB receives a first uplink transmission sent using one of the resource sets from a user equipment (UE). At block 1106, the eNB determines at least one preferred beam for at least one subsequent transmission based on the partitioning and the resource set used to send the first uplink transmission.

[0095] As indicated above, in some cases, Msg1 may be used to (directly or indirectly) indicate a preferred beam direction for a subsequent transmission (such as Msg2). In some cases, the indication may simply be a default for Msg2 to use the same beam as Msg1 (e.g., the corresponding beam in a beam pair).

[0096] In a 4-step RACH scenario (eg, as described above with reference to Figure 8 ), Msg1 includes a sequence and can be used to carry information via PRACH resource space partitioning. Such partitioning can indicate different resource sets to signal different beams. Each resource set can be, for example, a combination of a preamble sequence, time, and / or frequency position. In this way, the resources selected for PRACH transmission can indicate a preferred beam or a combination of preferred beams.

[0097] As an example, a first resource set may be assigned to indicate a “default” beam (e.g., using the same beam as Msg1), while a different resource set is assigned to indicate using the next SS beam (e.g., if msg1 used SS beam index i, then the preferred beam for msg2 may correspond to SS beam index (i+1) modulo (the total number of SS beams) or some other beam index offset relative to the default beam index. Similarly, when multiple preferred beams are indicated (e.g., for multiple subsequent transmissions), partitioning may be performed so that different resource sets correspond to different combinations of preferred beams.

[0098] In some cases, such partitioning information may be signaled (carried) in a master information block (MIB) or residual minimum system information (RMSI) that the UE reads before starting the RACH procedure. In some cases, the RMSI may be carried in SIB1 (the terms "SIB1" and "RMSI" may even be used interchangeably). The remaining information in the RMSI generally refers to system information that the UE needs to acquire before being able to transmit PRACH.

[0099] In a two-step RACH scenario (such as the one referenced above) Fig. 9 As described above, Msg1 includes a payload. Thus, the preferred beam direction may be indicated in the payload or its DMRS (it may be noted that the Msg1 PRACH sequence may be part of the DMRS).

[0100] In some cases, the UE may apply a receive (Rx) beam corresponding to the indicated beam direction to receive Msg2.

[0101] For scenarios where a "non-default" indication is to be provided, various options exist. For example, in a high-speed train scenario (where speed is known and position can be accurately predicted for a given route), mobility may cause the optimal beam to change in a predictable manner in the time interval between Msg1 and the gNB response Msg2. The techniques presented herein may also be used in cases where the Maximum Permitted Radiation (MPE) or some other source of UL / DL asymmetry may cause the optimal beams for Msg1 and Msg2 to be different.

[0102] As mentioned above, the time period between messages (such as Msg1 to Msg2) may be considered when selecting the preferred beam. In some cases, Msg2 may arrive anywhere in the random access response (RAR) time window starting at a fixed offset from the Msg1 transmission time. In some cases (such as MPE scenarios with low mobility), the optimal beam may be the same for all times in this window.

[0103] However, in high-speed train scenarios, this may not hold and the same beam may not be optimal for the entire window. Therefore, the preferred beam(s) may be selected based on the duration of the RAR window. In some cases, a narrower RAR window or a different RAR window size may be used. Based on the preconfigured PRACH resource space partitioning, the RAR window size may itself be dependent on the PRACH resources used.

[0104] In some cases (e.g., for relatively long RAR windows where the best beam may change), the UE may signal multiple best beams corresponding to different times within the RAR window. In such cases, the temporal quantization of the RAR window may depend on the window length, parameters indicated by the PRACH resource space partitioning, or other parameters (e.g., indicated in the MIB or RMSI). Indicating multiple beams (for different times within the RAR window) may be particularly suitable for two-step RACH designs where Msg1 can carry more information.

[0105] As mentioned above, in some cases, the preferred beam may be indicated for subsequent transmissions after Msg1 and Msg2. For example, for a 4-step RACH procedure in a high-speed train scenario, the optimal beam for msg3 may also be different from the optimal beam for msg2. Thus, depending on the delay between Msg2 and Msg3, a different preferred beam may be selected and indicated (e.g., using the techniques described herein in Msg1).

[0106] Since Msg1 has a low payload capacity for 4-step RACH (e.g., limited by the number of possible PRACH resource space partitions), a very coarse quantization of the "non-default" indication may be used. This approach may be extended to beam indications for later messages such as Msg4 and Msg5 (e.g., an acknowledgement "ACK" for Msg4). In some cases, an indication of the preferred beam for these subsequent messages may be carried in Msg3, which has a higher payload capacity than Msg1. In other words, this approach may be applied to Msg1, Msg3, or both.

[0107] For the two-step RACH procedure, the response to Msg2 from the UE serves as an ACK to complete the RACH procedure.Thus, using the techniques described herein, the beam for Msg2 and the beam for the UE response to Msg2 may also be conveyed in Msg1.

[0108] In any of the above scenarios (e.g., 4-step or 2-step RACH), the preferred beam to be used after the connection is established (e.g., after the RACH procedure) may also be communicated. For example, such beam information may be used to configure the CSI RS for subsequent training, or to preconfigure subsequent beam switching based on known (or expected) mobility events.

[0109] The methods disclosed herein include one or more steps or actions for implementing the described methods. These method steps and / or actions may be interchangeable with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be changed without departing from the scope of the claims.

[0110] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple of the same elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0111] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database, or another data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. "Determining" may also include resolving, selecting, choosing, establishing, and the like.

[0112] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the universal principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the various aspects shown herein, but should be granted the full scope consistent with the language of the claims, wherein the singular reference to the element is not intended to mean "there is and only one" (unless specifically stated) but "one or more". Unless specifically stated otherwise, the term "some" refers to one or more. The elements of the various aspects described throughout this disclosure are all structurally and functionally equivalent schemes currently or hereafter known to those of ordinary skill in the art and are expressly incorporated herein by reference, and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be contributed to the public, regardless of whether such disclosure is explicitly stated in the claims. Any element of a claim should not be interpreted under the provisions of 35 USC § 112, paragraph 6, unless the element is explicitly stated using the wording "device for..." or in the case of a method claim, the element is stated using the wording "step for...".

[0113] The various operations of the methods described above may be performed by any suitable device capable of performing the corresponding functions. These devices may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Generally, where there are operations illustrated in the accompanying drawings, these operations may have corresponding paired device-plus-function components with similar numbers.

[0114] The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0115] If implemented in hardware, an example hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus may include any number of interconnecting buses and bridges. The bus may link together various circuits including a processor, a machine-readable medium, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the user terminal 120 (see Figure 1 ), a user interface (e.g., a keypad, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and will not be described further. The processor may be implemented with one or more general and / or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuit systems capable of executing software. Those skilled in the art will recognize how to best implement the functionality described with respect to the processing system, depending on the specific application and the overall design constraints imposed on the overall system.

[0116] If implemented in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or other. Computer-readable media include both computer storage media and communication media, which include any media that facilitate the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a machine-readable storage medium. A computer-readable storage medium may be coupled to a processor so that the processor can read and write information from / to the storage medium. Alternatively, a storage medium may be integrated into a processor. As an example, a machine-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium having instructions stored thereon that is separated from a wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or in addition, a machine-readable medium or any part thereof may be integrated into a processor, such as a cache and / or a general register file, which may be the case. As an example, examples of machine-readable storage media may include RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. Machine-readable media may be implemented in a computer program product.

[0117] A software module may include a single instruction, or many instructions, and may be distributed over several different code segments, between different programs, and across multiple storage media. A computer-readable medium may include several software modules. These software modules include instructions that cause a processing system to perform various functions when executed by a device (such as a processor). These software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or may be distributed across multiple storage devices. As an example, when a triggering event occurs, a software module may be loaded into a RAM from a hard drive. During the execution of the software module, the processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When describing the functionality of a software module as described below, it will be understood that such functionality is implemented by the processor when the processor executes instructions from the software module.

[0118] Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology (such as infrared (IR), radio, and microwave), then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Disks, where disks often reproduce data magnetically, and discs reproduce data optically with lasers. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). The above combinations should also be included within the scope of computer-readable media.

[0119] Thus, some aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and / or encoded) thereon, which instructions can be executed by one or more processors to perform the operations described herein.

[0120] In addition, it should be appreciated that modules and / or other appropriate means for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by a user terminal and / or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk, etc.) so that once the storage device is coupled to or provided to a user terminal and / or base station, the device can obtain the various methods. In addition, any other suitable technology suitable for providing the methods and techniques described herein to a device may be utilized.

[0121] It will be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. A method for wireless communication by a user equipment (UE), comprising: receiving configuration information indicating that different resource sets are divided for indicating different preferred beams; determining at least a first preferred beam and a second preferred beam for at least the subsequent downlink transmission and the subsequent uplink transmission, respectively, based on one or more downlink signals and respective expected times of the subsequent downlink transmission and the subsequent uplink transmission of a random access channel (RACH) procedure; as well as An indication of the first preferred beam and the second preferred beam is provided via a first uplink transmission based on the configuration information.

2. The method of claim 1, wherein: The one or more downlink signals are transmitted via sweeping across a plurality of beams; as well as At least the first preferred beam and the second preferred beam are determined based on received signal qualities of the plurality of beams.

3. The method of claim 1, wherein the first uplink transmission is sent as part of the RACH procedure.

4. The method of claim 1, wherein: The first uplink transmission comprises a transmission or a retransmission of a first message sent during the RACH procedure; as well as At least the first preferred beam and the second preferred beam are determined based at least in part on a duration of a random access response (RAR) window.

5. The method of claim 4, wherein a plurality of different beams are indicated for use at different times within the RAR window.

6. The method of claim 1, wherein: The first uplink transmission includes a RACH preamble transmission.

7. The method of claim 1, wherein an indication of at least one preferred beam for use after completion of the RACH procedure is provided.

8. The method of claim 1, wherein the indication is provided as a payload of the first uplink transmission.

9. The method of claim 1, further comprising: The subsequent downlink transmission of the RACH procedure is processed using a receive beam corresponding to the indicated first preferred beam.

10. The method of claim 1, further comprising: The indication of the first preferred beam and the second preferred beam is provided based on resources selected for the first uplink transmission based on the partitioning.

11. The method of claim 1, wherein: The first combination of preferred beams is indicated by selecting resources from a first set of resources from the different sets of resources for the first uplink transmission; or The second combination of preferred beams is indicated by selecting resources from a second set of resources in the different sets of resources for the first uplink transmission.

12. The method of claim 1, wherein: Using resources from a first set of resources for the first uplink transmission indicates that the first preferred beam has a first beam index offset relative to a beam index used for the first uplink transmission; as well as Using resources from a second set of resources for the first uplink transmission indicates that the second preferred beam has a second beam index offset relative to a beam index used for the first uplink transmission.

13. The method of claim 1, wherein the configuration information is received via at least one of a master information block (MIB) or remaining minimum system information (RMSI).

14. The method of claim 1, wherein: Each resource set includes at least a combination of a sequence index, a time position, and a frequency position.

15. A method for wireless communication by a network entity, comprising: Signaling configuration information indicating that different resource sets are divided for indicating different preferred beams; receiving, from a user equipment (UE), a first uplink transmission sent using one of the resource sets; as well as At least a first preferred beam and a second preferred beam for at least a subsequent downlink transmission and a subsequent uplink transmission of a random access channel (RACH) procedure, respectively, are determined based on the division and the resource set used to send the first uplink transmission, wherein the at least the first preferred beam and the second preferred beam for at least the subsequent downlink transmission and the subsequent uplink transmission of the RACH procedure, respectively, are determined at the UE based on one or more downlink signals and corresponding expected times of the subsequent downlink transmission and the subsequent uplink transmission.

16. The method of claim 15, wherein the determining comprises: determining, if the first uplink transmission is received using a first set of resources in the set of resources, that a first combination of preferred beams for at least two subsequent transmissions is indicated; or Determining a second combination of preferred beams for the at least two subsequent transmissions if the first uplink transmission is received using a second set of resources in the sets of resources is indicated.

17. The method of claim 15, wherein the first uplink transmission is sent as part of the RACH procedure.

18. The method of claim 15, wherein: The first uplink transmission comprises a transmission or a retransmission of a first message sent during the RACH procedure; and Multiple different beams are indicated for use at different times within a random access response (RAR) window.

19. The method of claim 15, wherein: The first uplink transmission includes a RACH preamble transmission.

20. The method of claim 15, wherein an indication of at least one preferred beam for use after completion of the RACH procedure is provided.

21. The method of claim 15, wherein the indication is provided as a payload of the first uplink transmission.

22. The method of claim 15, further comprising: The subsequent downlink transmission of the RACH procedure is processed using a receive beam corresponding to the indicated first preferred beam.

23. The method of claim 15, wherein: a first set of resources for the first uplink transmission indicating that the first preferred beam has a first beam index offset relative to a beam index used for the first uplink transmission; as well as The second set of resources used for the first uplink transmission indicates that the second preferred beam has a second beam index offset relative to the beam index used for the first uplink transmission.

24. The method of claim 15, wherein the configuration information is signaled via at least one of a master information block (MIB) or remaining minimum system information (RMSI).

25. The method of claim 15, wherein: Each resource set includes at least a combination of a sequence index, a time position, and a frequency position.

26. An apparatus for wireless communication by a user equipment (UE), comprising: means for receiving configuration information indicating partitioning of different resource sets for indicating different preferred beams; means for determining at least a first preferred beam and a second preferred beam for at least the subsequent downlink transmission and the subsequent uplink transmission, respectively, based on one or more downlink signals and respective expected times of the subsequent downlink transmission and the subsequent uplink transmission of a random access channel (RACH) procedure; as well as means for providing an indication of the first preferred beam and the second preferred beam via a first uplink transmission based on the configuration information.

27. An apparatus for wireless communication by a network entity, comprising: means for signaling configuration information indicating partitioning of different resource sets for indicating different preferred beams; means for receiving, from a user equipment (UE), a first uplink transmission sent using one of the resource sets; as well as A device for determining at least a first preferred beam and a second preferred beam for at least a subsequent downlink transmission and a subsequent uplink transmission of a random access channel (RACH) procedure, respectively, based on the partition and the resource set used to send the first uplink transmission, wherein the at least first preferred beam and the second preferred beam for at least the subsequent downlink transmission and the subsequent uplink transmission of the RACH procedure, respectively, are determined at the UE based on one or more downlink signals and the corresponding expected times of the subsequent downlink transmission and the subsequent uplink transmission.

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