Systems and methods for beam management

Abstract

The present disclosure provides a first method, a first device, and a first computer-readable medium for beam management. The first device may send one or more indications of one or more beam indices corresponding to one or more beams to a user equipment (UE) on a control channel. The first device may send one or more reference signals to the UE via the one or more beams corresponding to the one or more beam indices. The reference signal may be used by the UE to select an optimal subarray and / or receive combiner for communication with the first device.

Description

[0001] This application is a divisional application of a patent application filed on March 31, 2017, entitled “System and Method for Beam Management” and application number 201780023098.4.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 322,168, filed on April 13, 2016, entitled “TRANSMIT REQUEST FOR BEAM TRACKING,” U.S. Provisional Application Serial No. 62 / 329,180, filed on April 28, 2016, entitled “TRANSMIT REQUEST FOR BEAM TRACKING,” U.S. Provisional Application Serial No. 62 / 333,120, filed on May 6, 2016, entitled “TRANSMIT REQUEST FOR BEAM TRACKING,” U.S. Provisional Application Serial No. 62 / 337,829, filed on May 17, 2016, and U.S. Provisional Application Serial No. 62 / 338,669, filed on May 18, 2016, entitled “TRANSMIT REQUEST FOR BEAM TRACKING,” No. 62 / 338,484, filed on May 24, 2016, entitled “TRANSMIT REQUEST FOR BEAM TRACKING,” U.S. Provisional Application Serial No. 62 / 341,051, filed on May 24, 2016, entitled “SYSTEM AND METHOD FOR BEAM INDEX,” and U.S. Patent Application Serial No. 15 / 474,859, filed on March 30, 2017, entitled “SYSTEM AND METHOD FOR BEAM MANAGEMENT.” The disclosures of the above-mentioned provisional applications are expressly incorporated herein by reference in their entirety. Technical Field

[0004] The present disclosure relates generally to communication systems, and more particularly to user equipment and base stations that can communicate via one of a plurality of beams. Background Art

[0005] Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies that can support 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.

[0006] These multiple access technologies have been adopted in a variety of telecommunication standards to provide a common protocol that enables different wireless devices to communicate at local, national, regional, and even global levels. An exemplary telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard issued by the Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access by using OFDMA on the downlink, SC-FDMA on the uplink, and using multiple-input multiple-output (MIMO) antenna technology to improve spectrum efficiency, reduce costs, and improve services. However, with the continued growth of the demand for mobile broadband access, there is a need for further improvements to the LTE technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies.

[0007] Examples of improvements to LTE may include fifth generation wireless systems and mobile networks (5G). 5G is a telecommunications standard that can be extended beyond the scope of LTE and / or 4G standards. For example, 5G can provide higher capacity and, therefore, serve a greater number of users in an area. In addition, 5G can increase data consumption and data rates. Summary of the invention

[0008] The following content introduces a brief summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all expected aspects, and is not intended to identify key or important elements of all aspects, nor is it intended to describe the scope of any or all aspects. Its only purpose is to introduce some concepts of one or more aspects in a simplified form as a preface to the more detailed description introduced later.

[0009] In millimeter wave (mmW) systems, path loss may be relatively high. Transmissions may be directional to mitigate path loss. The base station may send one or more beam reference signals by scanning in all directions so that the user equipment (UE) can identify the optimal "coarse" beam. In addition, the base station may send a beam refinement request signal so that the UE can track the "fine" beam. If the "coarse" beam identified by the UE changes, the UE may need to notify the base station so that the base station can train one or more new "fine" beams for the UE.

[0010] In a first aspect, a first method, a first device, and a first computer-readable medium are provided. The first device may communicate with a UE via a first active beam. The first device may determine to perform beam tracking with the UE, including identifying a new beam for communication between the UE and the first device. The first device may perform beam tracking with the UE based on the determination to perform beam tracking. The first device may communicate with the UE via a second active beam based on the beam tracking. In one aspect, the determination to perform beam tracking for the UE includes determining a time for the UE to transition from an inactive period of discontinuous reception (DRX) to an active period of DRX, and the performing of the beam tracking is based on the determined time. In one aspect, the performing the beam tracking comprises one or more of: transmitting at least one beam reference signal (BRS); receiving a first indication of a first beam index from the UE based on the at least one BRS; transmitting at least one beam refinement reference signal (BRRS) based on the first indication of the first beam index; and receiving a second indication of a second beam index based on the at least one BRRS, the second beam index corresponding to the second active beam. In one aspect, the performing the beam tracking comprises one or more of: receiving a request for beam tracking from the UE; transmitting at least one BRRS based on the request for beam tracking; and receiving an indication of a beam index based on the at least one BRRS, the beam index corresponding to the second active beam. In one aspect, the communicating with the UE via the first active beam comprises: transmitting a reference signal to the UE to determine whether the first active beam is failing, and the determining to initiate beam tracking for the UE comprises: receiving a response from the UE based on the reference signal; and detecting a radio link failure based on the received response. In one aspect, the communication with the UE via the first active beam is performed using a first radio access technology (RAT), and the response is received via a second RAT, wherein the second RAT has a lower carrier frequency than the first RAT. In one aspect, the reference signal is one of: a channel state information reference signal (CSI-RS), a cell-specific reference signal (CRS), a secondary synchronization signal (SSS), a mobility reference signal (MRS), a demodulation reference signal (DMRS), or a beam reference signal (BRS), and the response includes at least one of: channel quality information (CQI), signal to interference plus noise ratio (SINR), signal to noise ratio (SNR), received signal strength indicator (RSSI), reference signal received power (RSRP), or reference signal received quality (RSRQ).In one aspect, performing the beam tracking with the UE includes sending a message to the UE indicating that beam tracking is to be performed, wherein the message is sent on a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH). In one aspect, the message is sent via downlink control information (DCI) in the PDCCH. In one aspect, determining that beam tracking is to be initiated for the UE includes determining that there is no communication with the UE via the first active beam. In one aspect, determining that there is no communication with the UE via the first active beam is based on the absence of data carried on a physical uplink control channel (PUCCH), the absence of data carried on a physical uplink shared channel (PUSCH), or the absence of an acknowledgement / negative acknowledgement (ACK / NACK) message from the UE.

[0011] In a second aspect, a second method, a second apparatus, and a second computer-readable medium are provided. The second apparatus may communicate with a base station via a first active beam. The second apparatus may receive a signal associated with beam tracking from the base station, the beam tracking comprising identifying a new beam for communication between the second apparatus and the base station. The second apparatus may communicate with the base station via a second active beam based on the signal associated with the beam tracking. In one aspect, the signal comprises a BRRS, and the second apparatus may send a beam index corresponding to the second active beam to the base station based on the BRRS. In one aspect, the signal comprises a BRS, and the second apparatus may send a beam index corresponding to a coarse beam to the base station. In one aspect, the second apparatus may send a request to perform beam tracking to the base station based on the signal. In one aspect, the communication with the base station via the first active beam comprises receiving a reference signal, and the second apparatus may detect a radio link failure based on the receiving of the reference signal, and send an indication to the base station based on the detected radio link failure. In one aspect, the reference signal is one of a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS, and the indication includes at least one of a CQI, a SINR, a SNR, an RSSI, an RSRP, or an RSRQ. In one aspect, the communication with the base station via the first active beam is performed using a first RAT, and the indication is sent via a second RAT, wherein the first RAT has a higher carrier frequency than the second RAT. In one aspect, the second device may perform beam tracking with the base station. In one aspect, the performing the beam tracking includes one or more of the following: receiving at least one BRS from the base station; sending a first indication of a first beam index to the base station based on the BRS; receiving at least one BRRS; and sending a second indication of a second beam index based on the at least one BRRS. In one aspect, the signal is received on a PDCCH or a PDSCH. In one aspect, the signal is received via a DCI on a PDCCH.

[0012] In a third aspect, a third method, a third device, and a third computer-readable medium are provided. The third device may communicate with a UE via an active beam. The third device may send information to the UE, the information being used to indicate a period for transmitting control information on a control channel via a control information beam. The third device may use the period to transmit the control information to the UE on the control channel via the control information beam. In one aspect, the control channel includes a PUCCH, and the transmitting the control information to the UE on the control channel includes: based on the period, receiving the control information carried on the PUCCH from the UE via the control information beam. In one aspect, the control information beam includes at least one candidate beam, the at least one candidate beam corresponding to a beam index included in a set of candidate beam indices maintained by the third device. In one aspect, the control information beam includes at least one wide beam, the at least one wide beam having an angle greater than an angle of the active beam. In one aspect, the information indicating the period is sent via radio resource control (RRC) signaling. In one aspect, the information indicating the period is sent on a PDCCH. In one aspect, the information indicating the period includes a DCI of the PDCCH. In one aspect, the third device may receive a request to change the active beam, the request indicating a beam index corresponding to a second beam; and change the active beam to the second beam corresponding to the beam index indicated by the request. In one aspect, the request indicates the beam index by at least one of a cyclic offset or an extension across symbols. In one aspect, the request indicates the beam index by at least one of a subcarrier region or a random access channel (RACH).

[0013] In a fourth aspect, a fourth method, a fourth apparatus, and a fourth computer-readable medium are provided. The fourth apparatus may communicate with a base station via an active beam. The fourth apparatus may receive information from the base station, the information indicating a periodicity at which control information is to be transmitted on a control channel via a control information beam. The fourth apparatus may transmit the control information to the base station on the control channel via the control information beam using the periodicity. In one aspect, the control channel includes a PUCCH, and the transmitting the control information on the control channel includes: based on the periodicity, sending the control information to the base station on the PUCCH via the control information beam. In one aspect, the control information beam includes at least one candidate beam, the at least one candidate beam corresponding to a beam index included in a set of candidate beam indices. In one aspect, the control information beam includes at least one wide beam, the at least one wide beam having an angle greater than an angle of the active beam. In one aspect, the information indicating the periodicity is received using RRC signaling. In one aspect, the information indicating the periodicity is received on a PDCCH. In one aspect, the information indicating the period is indicated by the DCI of the PDCCH. In one aspect, the fourth device may send a request to the base station to change the active beam, the request indicating a beam index corresponding to a second beam; and change the active beam to the second beam corresponding to the beam index indicated by the request. In one aspect, the request indicates the beam index by at least one of a cyclic offset or an extension across symbols. In one aspect, the request indicates the beam index by at least one of a subcarrier region or a RACH.

[0014] In a fifth aspect, a fifth method, a fifth apparatus, and a fifth computer-readable medium are provided. The fifth apparatus may send one or more indications of one or more beam indexes corresponding to one or more beams to a UE on a control channel. The fifth apparatus may send one or more reference signals to the UE via the one or more beams corresponding to the one or more beam indexes. In one aspect, the control channel includes a PDCCH, and the one or more indications are included in one or more bits of a DCI message. In one aspect, the sending of the one or more indications of the one or more beam indexes corresponding to the one or more beams includes sending one or more beam indexes associated with one or more BRSs, the one or more BRSs being sent during a synchronization subframe. In one aspect, the sending of the one or more indications of the one or more beam indexes corresponding to the one or more beams includes receiving one or more beam indexes corresponding to the one or more beams from the UE, and sending the one or more beam indexes corresponding to the one or more beams based on the most recently received one or more beam indexes. In one aspect, the one or more beam indexes corresponding to the one or more beams are received on a PUSCH or a PUCCH. In one aspect, when more than two symbols are used for the reference signal transmission, the one or more beam indices corresponding to the one or more beams are sent based on the one or more beam indices received via the PUSCH. In one aspect, when two or less symbols are used for the reference signal transmission, the one or more beam indices associated with one or more beams are sent based on the one or more beam indices received via the PUCCH. In one aspect, the one or more reference signals include at least one of a CSI-RS or a BRRS. In one aspect, the sending of the one or more indications of the one or more beam indices associated with the one or more beams includes sending the one or more beam indices associated with the one or more beams, wherein at least one of the CSI-RS was previously sent via the one or more beams.

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

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

[0017] Figure 2A , 2B , 2C, and 2D are diagrams of LTE examples showing a DL frame structure, a DL channel within the DL frame structure, a UL frame structure, and a UL channel within the UL frame structure, respectively.

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

[0019] Figure 4A and 4B is a diagram of a wireless communication system.

[0020] Figures 5A to 5G is a diagram of a wireless communication system.

[0021] Figure 6 is a diagram of a wireless communication system.

[0022] Figure 7 is a diagram of a wireless communication system.

[0023] Figure 8 is a diagram of a wireless communication system.

[0024] Figures 9A to 9E is a diagram of a wireless communication system.

[0025] Fig. 10A and 10B is a flow chart of a method of wireless communication.

[0026] Fig.11A and 11B is a flow chart of a method of wireless communication.

[0027] Fig.12 is a flow chart of a method of wireless communication.

[0028] Fig.13 is a flow chart of a method of wireless communication.

[0029] Fig.14 is a flow chart of a method of wireless communication.

[0030] Fig.15 is a flow chart of a method of wireless communication.

[0031] Fig.16 is a flow chart of a method of wireless communication.

[0032] Fig.17 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0033] Fig.18 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

[0034] Fig.19 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0035] Fig. 20 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

[0036] Fig.21 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0037] Fig. 22 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

[0038] Fig.23 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0039] Fig.24 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

[0040] Fig.25 is a conceptual data flow diagram illustrating the flow of data between different units / components in an exemplary apparatus.

[0041] Fig.26 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system. DETAILED DESCRIPTION

[0042] The specific embodiments described below in conjunction with the accompanying drawings are intended to be a description of various configurations, and are not intended to represent the only configuration that can implement the concepts described herein. For the purpose of providing a thorough understanding of various concepts, the specific embodiments include specific details. However, it will be apparent to those skilled in the art that these concepts can also be implemented without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid blurring such concepts.

[0043] 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 following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0044] For 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 appropriate hardware that are 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 terms, 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.

[0045] Therefore, in one or more exemplary embodiments, the functions described 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 medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media can 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 above types, or any other medium that can be used to store computer executable code that can be accessed by a computer in the form of instructions or data structures.

[0046] Figure 1 1 is a diagram showing an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, and an evolved packet core (EPC) 160. 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.

[0047] The base stations 102 (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) interface with the EPC 160 via a backhaul link 132 (e.g., an S1 interface). The base stations 102 may perform one or more of the following functions, among other functions: transfer 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 (e.g., via the EPC 160) via a backhaul link 134 (e.g., an X2 interface). The backhaul link 134 may be wired or wireless.

[0048] The base station 102 can communicate with the UE 104 wirelessly. Each base station 102 in the base station 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may 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 may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group referred to as a closed subscriber group (CSG). The communication link 120 between the base station 102 and the UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also referred to as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including space division multiplexing, beamforming and / or transmit diversity. The communication link may be through one or more carriers. The base station 102 / UE 104 may use up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) of spectrum bandwidth allocated in carrier aggregation per carrier to achieve up to a total of 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).

[0049] 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) before communicating to determine whether the channel is available.

[0050] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as the 5 GHz unlicensed spectrum 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.

[0051] The gNode B (gNB) 180 may operate in millimeter wave (mmW) frequencies and / or near mmW frequencies to communicate with the UE 182. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 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 has a wavelength between 1 mm and 10 mm. The wireless waves in this band may be referred to as millimeter waves. Near mmW may extend down to a frequency of 3 GHz with 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 the mmW / near mmW radio frequency bands have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 184 with the UE 182 to compensate for the extremely high path loss and short range.

[0052] 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. All user Internet Protocol (IP) packets are transferred through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. 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 (PSS), 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 that broadcasts specific services, and may be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0053] A base station may also be referred to as a gNB, a Node B, an evolved Node B (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), or some other appropriate term. Base station 102 provides an access point to EPC 160 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, 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, or any other device with similar functionality. UE 104 may also be referred to as a station, a mobile station, a user station, a mobile unit, a user unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile user 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 appropriate term.

[0054] Refer again Figure 1In certain aspects, the base station 180 may send one or more indications 198 of one or more beam indexes corresponding to the one or more beams to the UE 182 on a control channel. The base station 180 may send one or more reference signals to the UE 182 via the one or more beams corresponding to the one or more beam indexes. In one aspect, the control channel includes a PDCCH, and the one or more indications 198 are included in one or more bits of a DCI message. In one aspect, sending the one or more indications 198 of the one or more beam indexes corresponding to the one or more beams includes sending the one or more beam indexes associated with one or more BRSs that are sent during a synchronization subframe. In one aspect, sending the one or more indications 198 of the one or more beam indexes corresponding to the one or more beams includes receiving the one or more beam indexes corresponding to the one or more beams from the UE 182, and sending the one or more beam indexes corresponding to the one or more beams based on the most recently received one or more beam indexes. In one aspect, the one or more beam indexes corresponding to the one or more beams are received on a PUSCH or a PUCCH. In one aspect, when more than two symbols are used for reference signal transmission, one or more beam indices corresponding to one or more beams are sent based on one or more beam indices received via PUSCH. In one aspect, when two or less symbols are used for reference signal transmission, one or more beam indices associated with one or more beams are sent based on one or more beam indices received via PUCCH. In one aspect, the one or more reference signals include at least one of a CSI-RS or a BRRS. In one aspect, sending one or more indications 198 of one or more beam indices associated with one or more beams includes sending one or more beam indices associated with one or more beams, wherein at least one of the CSI-RS was previously sent via the one or more beams.

[0055] Figure 2A is a diagram 200 showing an example of a DL frame structure. Figure 2B is a diagram 230 showing an example of channels within a DL frame structure. Figure 2C is a diagram 250 showing an example of a UL frame structure. Figure 2D280 is a diagram showing an example of channels within a UL frame structure. Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 subframes of equal size. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including one or more time-concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into multiple resource elements (REs). For a conventional cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols in the time domain (for DL, OFDM symbols; for UL, SC-FDMA symbols), for a total of 84 REs. For an extended cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

[0056] like Figure 2A As shown, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include CRS (sometimes also referred to as common RS), UE-specific reference signal (UE-RS) and CSI-RS. Figure 2A CRS for antenna ports 0, 1, 2 and 3 (indicated as R0, R1, R2 and R3 respectively), UE-RS for antenna port 5 (indicated as R5) and CSI-RS for antenna port 15 (indicated as R) are shown. Figure 2B An example of various channels within a DL subframe of a frame is shown. The Physical Control Format Indicator Channel (PCFICH) is within symbol 0 of slot 0 and carries an indication of whether the PDCCH occupies 1, 2, or 3 symbols ( Figure 2B The PDCCH occupies 3 symbols) and the control format indicator (CFI) is shown. The PDCCH carries downlink control information (DCI) in one or more control channel elements (CCEs), each CCE includes nine RE groups (REGs), each REG includes four consecutive REs in one OFDM symbol. The UE can be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries the DCI. The ePDCCH can have 2, 4, or 8 RB pairs ( Figure 2BTwo RB pairs are shown, with each subset including one RB pair). A physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0 and carries a HARQ indicator (HI) that indicates HARQ ACK / NACK feedback based on the PUSCH. A primary synchronization channel (PSCH) may be within symbol 6 of slot 0 within subframes 0 and 5 of a frame. The PSCH carries a primary synchronization signal (PSS) used by the UE to determine subframe / symbol timing and a physical layer identity. A secondary synchronization channel (SSCH) may be within symbol 5 of slot 0 within subframes 0 and 5 of a frame. The SSCH carries a secondary synchronization signal (SSS) used by the UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE may determine a physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the DL-RS described above. A physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSCH and SSCH to form a synchronization signal (SS) block. The MIB provides the number of RBs in the DL system bandwidth, PHICH configuration, and system frame number (SFN).The PDSCH carries user data, broadcast system information not sent through the PBCH (such as system information blocks (SIBs)), and paging messages.

[0057] like Figure 2C As shown, some of the REs carry DMRS for channel estimation at the base station. In addition, the UE may send a sounding reference signal (SRS) in the last symbol of the subframe. The SRS may have a comb structure, and the UE may send the SRS on one of the teeth of the comb. The SRS may be used by the base station for channel quality estimation to achieve frequency-dependent scheduling on the UL. Figure 2D Examples of various channels within a UL subframe of a frame are shown. A physical random access channel (PRACH) may be within one or more subframes within a frame based on the PRACH configuration. The PRACH may include six consecutive RB pairs within a subframe. The PRACH allows a UE to perform initial system access and achieve UL synchronization. The physical uplink control channel (PUCCH) may be located at the edge of the UL system bandwidth. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (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.

[0058] Figure 33 is a block diagram of a base station 310 communicating with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to the 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 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 (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with transfer 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), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0059] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functions associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on 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 maps to a 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-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may 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 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 produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived based on reference signals and / or channel condition feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier using a corresponding spatial stream for transmission.

[0060] At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers the information modulated on 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 of the information to recover any spatial stream to and from the UE 350. If multiple spatial streams are to the UE 350, they can be merged into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols and reference signals on each subcarrier 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 channel estimates 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 the base station 310. The data and control signals are then provided to the controller / processor 359, which implements layer 3 and layer 2 functions.

[0061] 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.

[0062] Similar to the functions described for DL ​​transmission performed in conjunction with the base station 310, the controller / processor 359 provides RRC layer functions associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functions associated with header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functions associated with transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation 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 TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0063] The TX processor 368 may select an appropriate coding and modulation scheme, and to facilitate spatial processing, using channel estimates derived by the channel estimator 358 based on a reference signal or feedback sent by the base station 310. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0064] UL transmissions are processed at the base station 310 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 on an RF carrier and provides the information to a RX processor 370.

[0065] 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.

[0066] Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and has a wavelength between 1 mm and 10 mm. The wireless waves in this band may be referred to as millimeter waves. Near mmW can extend down to a frequency of 3 GHz, with a wavelength of 100 mm (the super high frequency (SHF) band extends between 3 GHz and 30 GHz, also known as centimeter waves). Although the disclosure herein refers to mmW, it should be understood that the disclosure also applies to near mmW. In addition, although the disclosure herein refers to mmW base stations, it should be understood that the disclosure also applies to near mmW base stations.

[0067] In order to build a useful communication network in the millimeter wavelength spectrum, beamforming technology can be used to compensate for path loss. Beamforming technology focuses RF energy in a narrow direction to allow the RF beam to propagate farther in that direction. Using beamforming technology, non-line-of-sight (NLOS) RF communications in the millimeter wavelength spectrum can rely on reflection and / or diffraction of the beam to reach the UE. If the direction becomes blocked, whether due to UE movement or changes in the environment (e.g., obstacles, moisture, rain, etc.), the beam cannot reach the UE. Because, in order to ensure that the UE has continuous seamless coverage, multiple beams in as many different directions as possible may be available. In one aspect, beamforming technology may require mmW base stations and UEs to transmit and receive in directions that allow the most RF energy to be collected.

[0068] Figure 4A and 4B402a-402h. UE 404 receives a transmission 402e including PSS, SSS and PBCH. Based on the received SS blocks, UE 404 synchronizes to the NR network and camps on a cell associated with base station 402.

[0069] Reference Figure 4A , diagram 400 shows a base station 402 of a mmW system transmitting a beamforming signal 406 (e.g., BRS) in different transmission directions (e.g., directions A, B, C, and D). In one example, the base station 402 can scan through the transmission directions according to the order ABCD. In another example, the base station 402 can scan through the transmission directions according to the order BDAC. Although with respect to Figure 4A Only four transmission directions and two transmission orders are described, but any number of different transmission directions and transmission orders are contemplated.

[0070] After sending the signal, the base station 402 may switch to a receiving mode. In the receiving mode, the base station 402 may scan through different receiving directions in an order or pattern corresponding to (mapped to) the order or pattern in which the base station 402 previously sent synchronization / discovery signals in different transmitting directions. For example, if the base station 402 previously sent synchronization / discovery signals in a transmitting direction according to the order ABCD, the base station 402 may scan through the receiving direction according to the order ABCD to attempt to receive an association signal from the UE 404. In another example, if the base station 402 previously sent synchronization / discovery signals in a transmitting direction according to the order BDAC, the base station 402 may scan through the receiving direction according to the order BDAC to attempt to receive an association signal from the UE 404.

[0071] The propagation delay on each beamformed signal allows the UE 404 to perform a receive (RX) scan. A UE 404 in receive mode may scan through different receive directions in an attempt to detect a synchronization / discovery signal 406 (see Figure 4B). The UE 404 may detect one or more of the synchronization / discovery signals 406. When a strong synchronization / discovery signal 406 is detected, the UE 404 may determine an optimal transmission direction of the base station 402 and an optimal reception direction of the UE 404 corresponding to the strong synchronization / discovery signal. For example, the UE 404 may determine a preliminary antenna weight / direction for the strong synchronization / discovery signal 406, and may also determine a time and / or resource in which the base station 402 is expected to optimally receive the beamformed signal. Thereafter, the UE 404 may attempt to associate with the base station 402 via the beamformed signal.

[0072] The base station 402 may use multiple ports to scan through multiple directions in a cell-specific manner in the first symbol of the synchronization subframe. For example, the base station 402 may use four ports to scan through different transmission directions (e.g., directions A, B, C, and D) in a cell-specific manner in the first symbol of the synchronization subframe. In one aspect, these different transmission directions (e.g., directions A, B, C, and D) may be considered "coarse" beam directions. In one aspect, BRS may be transmitted in different transmission directions (e.g., directions A, B, C, and D).

[0073] In one aspect, the base station 402 may use four ports to scan four different transmit directions (eg, directions A, B, C, and D) in a cell-specific manner in the second symbol of the synchronization subframe. The synchronization beam may appear in the second symbol of the synchronization subframe.

[0074] Reference Figure 4B 420, UE 404 may listen for beamforming discovery signals in different receive directions (e.g., directions E, F, G, and H). In one example, UE 404 may scan through the receive directions in the order EFGH. In another example, UE 404 may scan through the receive directions in the order FHEJ. Figure 4B Only four receiving directions and two receiving orders are described, but any number of different receiving directions and receiving orders are contemplated.

[0075] UE 404 may attempt association by transmitting beamforming signals 426 (e.g., association signals or another indication of an optimal "coarse" beam or an optimal "fine" beam) in different transmit directions (e.g., directions E, F, G, and H). In one aspect, UE 404 may transmit association signals 426 along an optimal receive direction of UE 404 at a time / resource where base station 402 is expected to optimally receive the association signals. Base station 402 in receive mode may scan through different receive directions and detect association signals 426 from UE 404 during one or more time slots corresponding to the receive directions. When a strong association signal 426 is detected, base station 402 may determine an optimal transmit direction of UE 404 and an optimal receive direction of base station 402 corresponding to the strong association signal. For example, base station 402 may determine preliminary antenna weights / directions for the strong association signals 426 and may also determine a time and / or resource where UE 404 is expected to optimally receive the beamforming signals. The above description of the association signals 426 may be updated over time. Figure 4A and 4B Any of the processes discussed is refined or repeated so that the UE 404 and the base station 402 eventually learn the optimal transmission direction and the optimal reception direction for establishing a link with each other. Such refinement and repetition may be referred to as beam training.

[0076] In one aspect, the base station 402 may select an order or pattern for sending synchronization / discovery signals based on the number of beamforming directions. The base station 402 may then send a signal in an amount of time long enough for the UE 404 to scan through several beamforming directions in an attempt to detect a synchronization / discovery signal. For example, the BS beamforming direction may be indicated by n, where n is an integer from 0 to N, and N is the maximum number of transmit directions. Additionally, the UE beamforming direction may be indicated by k, where k is an integer from 0 to K, and K is the maximum number of receive directions. When the UE 404 detects a synchronization / discovery signal from the base station 402, the UE 404 may find that the strongest synchronization / discovery signal is received when the UE 404 beamforming direction is k=2 and the base station 402 beamforming direction is n=3. Therefore, the UE 404 may respond to the base station 402 (send a beamforming signal) using the same antenna weight / direction in the corresponding response time slot. That is, UE 404 may transmit a signal to base station 402 using UE 404 beamforming direction k=2 during a time slot in which base station 402 is expected to perform a receive scan at base station 402 beamforming direction n=3.

[0077] In mmW systems, path loss may be relatively high. Transmissions may be directional to mitigate path loss. The base station may send one or more beam reference signals by scanning in all directions so that the UE can identify the optimal "coarse" beam. In addition, the base station may send a BRRS so that the UE can track a "fine" beam. In various aspects, the CSI-RS may be used to track the fine beam, and therefore, a reference to the BRRS may include a reference to the CSI-RS. If the "coarse" beam identified by the UE changes, the UE may need to notify the base station so that the base station can train one or more new "fine" beams for the UE.

[0078] In various aspects, the UE may send an index of the best beam and a corresponding beam refinement reference signal session request to the base station in a subframe reserved for RACH. The UE may occupy one or more tones reserved for RACH. In addition, the UE may occupy tones reserved for scheduling requests but not used for RACH transmissions.

[0079] FIG. 5A to FIG. 5G is a diagram illustrating an example of transmission of beamformed signals between a base station and a UE. Base station 502 may be embodied as a base station in a mmW system (mmW base station), such as mmW base station 180. In one aspect, base station 502 may be co-located with another base station, such as an eNB, a cellular base station, or other base station (e.g., a base station configured to communicate in a sub-6 GHz frequency band). Although some beams are shown as being adjacent to each other, such an arrangement may be different in different aspects (e.g., beams transmitted during the same symbol may not be adjacent to each other). Additionally, the number of beams shown is to be considered illustrative.

[0080] The base station 502 may include hardware for performing analog and / or digital beamforming. If the base station 502 is equipped with analog beamforming, then at any time, the base station 502 may transmit or receive signals in only one direction. If the base station 502 is equipped with digital beamforming, then the base station 502 may transmit multiple signals in multiple directions simultaneously, or may receive multiple signals in multiple directions simultaneously.

[0081] In addition, for example, UE 504 may include hardware for performing analog and / or digital beamforming. If UE 504 is equipped with analog beamforming, then at any time, UE 504 may send or receive signals in only one direction. If UE 504 is equipped with digital beamforming, then UE 504 may send multiple signals in multiple directions simultaneously, or may receive multiple signals in multiple directions simultaneously.

[0082] In the mmW network, the UE may perform beam scanning with the mmW base station within a range. For example, the base station 502 may send m beams in multiple different spatial directions. The UE 504 may monitor / scan the beam transmission from the base station 502 in n different receiving spatial directions. When monitoring / scanning the beam transmission, the UE 504 may monitor / scan the beam scanning transmission from the base station 502 m times (a total of m*n scans) in each of the n different receiving spatial directions. In another aspect, in the beam scanning, the UE 504 may send n beams in multiple different spatial directions. The base station 502 monitors / scans the beam transmission from the UE 504 in m different receiving spatial directions. When monitoring / scanning the beam transmission, the base station 502 may monitor / scan the beam scanning transmission from the UE 504 n times (a total of m*n scans) in each of the m different receiving spatial directions.

[0083] Based on the beam scanning performed, the UE and / or the mmW base station can determine the channel quality associated with the beam scanning performed. For example, the UE 504 can determine the channel quality associated with the beam scanning performed. Alternatively, the base station 502 can determine the channel quality associated with the beam scanning performed. If the UE 504 determines the channel quality associated with the beam scanning performed, the UE 504 can send channel quality information (also referred to as beam scanning result information) to the base station 502. The UE 504 can send the beam scanning result information to the base station 502. If the base station 502 determines the channel quality associated with the beam scanning performed, the base station 502 can send the beam scanning result information to the UE 504. In one aspect, the channel quality can be affected by a variety of factors. These factors include the movement of the UE 504 along the path or due to rotation (for example, the user holds and / or rotates the UE 504), the movement along the path behind the obstacle, and / or the movement in a specific environmental condition (for example, obstacles, rain, humidity). The UE 504 and the base station 502 may exchange other information associated with, for example, beamforming (eg, analog or digital beamforming capabilities, beamforming type, timing information, configuration information, etc.).

[0084] Based on the received information, the base station 502 and / or the UE 504 may determine various configuration information, such as mmW network access configuration information, information for adjusting a beam scanning period, information about overlapping coverage for predicting switching to another base station, such as a mmW base station.

[0085] In one aspect, the beam set may include eight different beams. For example, Figure 5AEight beams 521, 522, 523, 524, 525, 526, 527, 528 in eight different directions are shown. In one aspect, the base station 502 may be configured to beamform transmissions of at least one of the beams 521, 522, 523, 524, 525, 526, 527, 528 to the UE 504. In one aspect, the base station 502 may use eight ports to scan / transmit directions during a subframe (e.g., a synchronization subframe).

[0086] In one aspect, a base station may transmit a signal (such as a BRS) in multiple directions, for example during a synchronization subframe. In one aspect, the transmission may be cell-specific. Figure 5B , the base station 502 may transmit a first set of beams 521, 523, 525, and 527 in four directions. For example, the base station 502 may transmit a BRS in a synchronization subframe of each of the transmission beams 521, 523, 525, and 527.

[0087] In one aspect, these beams 521, 523, 525, 527 transmitted in four directions may be odd-indexed beams 521, 523, 525, 527 in four directions out of eight possible directions of a beam set. For example, the base station 502 may be able to transmit beams 521, 523, 525, 527 in directions adjacent to other beams 522, 524, 526, 528 that the base station 502 is configured to transmit. In one aspect, this configuration in which the base station 502 transmits beams 521, 523, 525, 527 in four directions may be considered a "coarse" beam set.

[0088] The UE 504 may determine a corresponding beam index (sometimes abbreviated as "BI") corresponding to the corresponding beam. In various aspects, the beam index may indicate at least a direction (e.g., a beamforming direction) for communicating via the corresponding beam to the UE 504. For example, the beam index may be a logical beam index associated with an antenna port, an OFDM symbol index, and / or a BRS transmission period, which may be indicated by one or more bits (e.g., 9 bits). For example, the UE 504 may be configured to determine the beam index corresponding to the beam based on the time when the BRS is received, e.g., the symbol or time slot during which the BRS is received may indicate the beam index corresponding to the beam.

[0089] exist Figure 5C, UE 504 may determine or select the strongest or preferred beam index (sometimes abbreviated as "BI"). For example, UE 504 may determine that beam 525 carrying BRS is the strongest or preferred. UE 504 may select a beam by measuring a value of received power or received quality associated with each beam in the first set of beams 521, 523, 525, 527. In one aspect, the received power may be referred to as BRS received power (BRSRP).

[0090] UE 504 may compare the corresponding values ​​to each other. UE 504 may select the "optimal" beam. In one aspect, the optimal beam may be the beam corresponding to the maximum or highest value (e.g., the optimal beam may be the beam with the highest BRSRP). The selected beam may correspond to a beam index, which may be a beam index with respect to base station 502. For example, UE 504 may determine that the BRSRP corresponding to fifth beam 525 is the highest, and therefore, fifth beam 525 is the optimal beam, as determined by UE 504.

[0091] The UE 504 may send a first indication 560 of the fifth beam 525 to the base station 502. In one aspect, the first indication 560 may include a request to send a BRRS. The BRRS may be UE-specific. Those skilled in the art will recognize that the BRRS may be referenced by different terms, such as a beam refinement signal, a beam tracking signal, or another term, without departing from the present disclosure.

[0092] In one aspect, the base station 502 may trigger the transmission of the first indication 560. For example, the base station 502 may trigger the transmission of the first indication 560 via a DCI message.

[0093] The base station 502 may receive a first indication 560. In one aspect, the first indication 560 may include a beam adjustment request (BAR) (e.g., a request for beam tracking, a request for BRRS, a request for the base station to start transmitting on the indicated beam index without any further beam tracking, etc.). In one aspect, the BAR may be included in a MAC control element (CE). In one aspect, the first indication 560 may be indicated by a scheduling request.

[0094] In one aspect, the UE 504 may send a BAR once during a specific time interval (which may be defined by a timer (e.g., a "prohibit BAR timer") configured through RRC signaling). In one aspect, the UE 504 may trigger a BAR if the prohibit BAR timer is not running and at least one condition is met. In one aspect, if the UE 504 has uplink resources allocated for a new transmission for a transmission time interval (TTI), the UE 504 may generate and send a BAR MAC CE and start or restart the prohibit BAR timer. In another aspect, the UE 504 may be configured with a dedicated scheduling request for a BRRS request. In such an aspect, the UE 504 may signal a dedicated scheduling request for a BRRS request in the scheduling request region of a RACH subframe (and the UE 504 may start or restart the prohibit BAR timer). In another aspect, the UE 504 may trigger a scheduling request (eg, when a dedicated scheduling request for a BRRS request is not configured for the UE 504 and / or when the UE 504 lacks uplink resources allocated for a new transmission for that TTI).

[0095] In some aspects, the first indication 560 may include a beam state information (BSI) report. The BSI report may include a beam index and a received power. For example, the UE 504 may measure a BRSRP corresponding to a beam through which the BRS is received, and the UE 504 may include the BRSRP and the beam index corresponding to the beam with the "best" (e.g., highest) BRSRP. For example, the UE 504 may send the first indication 560 as a format of uplink control information on a PUCCH (e.g., xPUCCH) or a PUSCH (e.g., xPUSCH), wherein the BSI report includes the beam index and the BRSRP.

[0096] Based on the first indication 560, the base station 502 may determine a beam index corresponding to the fifth beam 525. Figure 5D , the base station 502 may send the second set of beams based on the first indication 560 (e.g., based on the beam index indicated by the first indication 560). For example, the UE 504 may indicate that the fifth beam 525 is the optimal beam, and in response, the base station 502 may send the second set of beams 524, 525, 526 to the UE 504 based on the indicated beam index. In one aspect, the beams 524, 525, 526 sent based on the first indication 560 may be closer (e.g., spatially and / or in direction) to the fifth beam 525 than those other beams 521, 523, 527 in the first set of beams.

[0097] In one aspect, the beams 524, 525, 526 transmitted based on the first indication 560 may be considered a "fine" beam set. In one aspect, the base station 502 may transmit a BRRS via each of the beams 524, 525, 526 in the fine beam set. In one aspect, the beams 524, 525, 526 in the fine beam set may be adjacent. In one aspect, a BRRS transmission may span 1, 2, 5, or 10 OFDM symbols and may be associated with a BRRS resource allocation, a BRRS process indication, and / or a beam refinement process configuration.

[0098] Based on the BRRS transmissions performed via beams 524, 525, 526 in the fine beam set, the UE 504 may send a second indication 565 to the base station 502 to indicate the "optimal" beam. In one aspect, the second indication 565 may use two (2) bits to indicate the selected beam. For example, the UE 504 may send a second indication 565 indicating a beam index corresponding to the selected beam 525. In one aspect, the second indication 565 may report beam refinement information (BRI). In one aspect, the second indication 565 may include a resource index (e.g., BRRS-RI) and / or a reference power (RP) associated with the reception of the BRRS as measured by the UE 504 (e.g., BRRS-RP). Subsequently, the base station 502 may communicate with the UE 504 via the selected beam 525.

[0099] Reference Figure 5E , the base station 502 may send BRS in multiple directions during the synchronization subframe. In one aspect, the base station 502 may periodically and / or continuously send BRS, for example, even after the UE 504 has transmitted the second indication 565. For example, the base station 502 may send beams 521, 523, 525, 527 (e.g., a "coarse" beam set) that each include a BRS.

[0100] Reference Fig. 5F, the quality of the selected beam 525 may deteriorate, causing the UE 504. For example, when the base station 502 and the UE 504 communicate through the selected beam 525, the selected beam 525 may become blocked or otherwise unsatisfactory, so that the base station 502 and the UE 504 may prefer to communicate through another beam. Based on the BRS (e.g., sent during the synchronization subframe), the UE 504 can determine a new beam 523 through which to communicate. For example, the UE 504 can determine that the third beam 523 through which the BRS is transmitted may be the optimal beam. The UE 504 can select a beam based on measuring the received power (e.g., BRSRP) or the value of the received quality associated with each beam in the set of beams 521, 523, 525, 527, comparing the corresponding values ​​with each other, and selecting the beam corresponding to the highest value. The selected beam can correspond to the beam index at the base station 502. The UE 504 may send a third indication 570 to the base station 502 indicating the beam index. In one aspect, the third indication 570 may include a request to send a BRRS. The BRRS may be UE-specific. In one aspect, the BAR may be used to request the base station 502 to send the BRRS. In one aspect, the third indication 570 may be triggered by the base station 502, such as by a DCI message. Similar to the first indication 560, the third indication 570 may be included in a scheduling request.

[0101] about Figure 5G , the base station 502 may receive a third indication 570 from the UE 504. The base station 502 may be configured to determine a beam index based on at least the third indication 570. The base station 502 and the UE 504 may perform a beam refinement process, such as regarding Figure 5E as shown (e.g., to select a new beam through which to communicate).

[0102] Reference Figure 6 , a diagram of a wireless communication system 600 is shown. Base station 602 can be an aspect of base station 502, base station 310, base station 102, mmW base station 180, and / or another base station. UE 604 can be an aspect of UE 504, UE 350, UE 104, UE 182, and / or another UE.

[0103] In the illustrated aspect, the base station 602 can include up to eight antenna ports for BRS transmission. In various aspects, the base station 602 can send one or more BRS 612a-h (e.g., as described with respect to Figure 5A-5G). Each BRS 612a-h may be transmitted via a corresponding beam 620a-h. For example, the base station 602 may transmit a first BRS 612a via a first beam 620a with which the first BRS 612a is associated. The UE 604 may track one or more beams 620a-h by periodically measuring the BRS 612a-h associated with a corresponding one of the beams 620a-h. In one aspect, the transmission period of the BRS may be configured by an indicator on a PBCH, such as an enhanced or evolved PBCH (ePBCH). The transmission period may be associated with a time at which the beams 620a-h through which the BRS 612a-h are transmitted are scanned.

[0104] In some aspects, the UE 604 may receive a set of BRS 612a-h through a set of beams 620a-h. Each BRS 612 in the set of BRS 612a-h may be associated with a beam index corresponding to the beam 620a-h through which the BRS 612 is transmitted. The UE 604 may measure the signal quality of the BRS 612a-h, and each measured signal quality may correspond to the beam 620a-h in the beam set. For example, the UE 604 may measure the signal quality of the third BRS 612c, the fourth BRS 612d, the fifth BRS 612e, and the sixth BRS 612f (which correspond to the third beam 620c, the fourth beam 620d, the fifth beam 620e, and the sixth beam 620f, respectively). In some aspects, the UE 604 may not receive each of the BRS 612a-h.

[0105] In one aspect, the UE 604 may measure signal quality as received power. In one aspect, signal quality may correspond to BRSRP. For example, the UE 604 may measure BRSRP in decibels (dB) and / or decibel milliwatts (dBm). In other aspects, the UE 604 may measure signal quality as another value such as received quality (RQ), signal-to-interference ratio (SIR), SINR, SNR, RSRP, RSRQ, RSSI, or another metric.

[0106] UE 604 may send a first indication (e.g., first indication 560) to base station 602, the first indication being used to indicate a beam index corresponding to a beam having a "best" (e.g., highest) measured signal quality (e.g., BRSRP). The first indication may be a BSI report, which may include a beam index and a BRSRP corresponding to a beam in a set of beams 620a-h. For example, UE 604 may measure the best BRSRP of the fifth beam 620e. UE 604 may generate a BSI report including a BRSRP and a beam index corresponding to the fifth beam 620e. UE 604 may send the BSI report as a first indication to base station 602.

[0107] The base station 602 may transmit the BRRS 614. In some aspects, the BRRS 614c-f may not be transmitted on each beam 620a-h. For example, the base station 602 may transmit the BRRS 614c-f on a subset of beams 620c-f in the set of beams 620a-h. For example, the base station 602 may transmit the BRRS 614c-f on a subset of beams 620c-f that are close to or proximate to the beam 620e indicated by the first indication. In one aspect, the base station 602 may transmit the beams 620c-f as a fine beam set for beam refinement with the UE 604.

[0108] The UE 604 may select a beam in the subset of beams 620c-f. For example, the UE 604 may measure the signal quality (e.g., received power) of each BRRS 614c-f in the set of BRRS 614c-f transmitted through the subset of beams 620c-f. The UE 604 may determine the optimal (e.g., highest) channel quality (e.g., received power) of a BRRS (e.g., the fifth BRRS 614e) in the set of BRRS 614c-f. The UE 604 may send a second indication (e.g., the second indication 565) to the base station 602, which may include a beam index corresponding to the selected beam (e.g., the beam index corresponding to the fifth beam 620e).

[0109] Subsequently, the UE 604 and the base station 602 may communicate 640 via the selected beam corresponding to the beam index indicated by the UE 604 in the second indication. The communication 640 may be uplink and / or downlink communication. For example, the base station 602 and the UE 604 may communicate via the same or different beams for uplink communication and downlink communication.

[0110] In one aspect, at least one of the base station 602 and / or the UE 604 may maintain a beam index set 630. The beam index set 630 may include beam indices corresponding to beams from the base station 602 and / or another transmission point (e.g., another eNB or base station), which may allow dynamic point selection and / or joint transmission from multiple transmission points to the UE 604.

[0111] Although UE 604 is shown as maintaining a set of beam indices 630, base station 602 may maintain a similar set of beam indices. Base station 602 may maintain the set of beam indices based on information from UE 604, such as one or more BSI reports.

[0112] The UE 604 may maintain a beam index set 630 as an active set. In such an aspect, the UE 604 may synchronize with the base station 602 based on the beams in the beam index set 630 (e.g., soft switching from one beam in the beams 620a-h to another beam in the beams 620a-h). The beams corresponding to the beam indices included in the beam index set 630 may be used for PDCCH (e.g., xPDCCH (such as enhanced PDCCH (ePDCCH))), PDSCH (e.g., xPDSCH (such as enhanced PDSCH (ePDSCH))), PUCCH (e.g., xPUCCH (such as enhanced PUCCH (ePUCCH))), and / or PUSCH (e.g., xPUSCH (such as enhanced PUSCH (ePUSCH))) communications. The base station 602 and / or the UE 604 may periodically and / or continuously update the beam index set 630, for example based on the measurement results of the BRS 612 and / or the BRRS 614 (e.g., a comparison result of the signal quality with a threshold or relative to the signal quality corresponding to the beams included in the beam index set 630).

[0113] In one aspect, the base station 602 and / or the UE 604 may maintain the beam index set 630 as a candidate set. The base station 602 and / or the UE 604 may maintain the active beam index set and the candidate beam index set at the same time. For the candidate beam index set, the beams corresponding to the beam indices included in the beam index set 630 may be maintained to be included in the active beam index set. Similar to the active beam index set, the base station 602 and / or the UE 604 may periodically update the candidate beam index set, for example, based on the measurement results of the BRS 612 or the BRRS 614 (e.g., the comparison results of the signal quality with the threshold or relative to the signal quality corresponding to the beams included in the candidate beam index set). However, the period for updating the active beam index set may be different from the period for updating the candidate beam index set.

[0114] The base station 602 and / or the UE 604 may update the beam index set 630, for example, by adding a beam index to the beam index set 630 or removing a beam index from the beam index set 630. Additionally, the base station 602 and / or the UE 604 may move a beam index between an active beam index set and a candidate beam index set. The criteria for updating the beam index set 630 may be based on a signal quality measurement result, such as a received power of the BRS 612 or the BRRS 614. For example, the signal quality may be compared to a threshold or another signal quality corresponding to a beam index currently included in the beam index set.

[0115] In various aspects, the base station 602 can communicate 640 with the UE 604 through the fifth beam 620e (which can be a currently active beam or a currently serving beam). The communication 640 can be performed using a first RAT such as a mmW RAT, a 5G RAT (e.g., based on one or more technical standards released by 3GPP), etc. The communication 640 can be uplink communication, downlink communication, or both uplink and downlink communication.

[0116] In various aspects, the base station 602 can determine to perform beam tracking with the UE 604. Beam tracking can include one or more operations for selecting or identifying a beam in a set of beams 620a-h for communication 640 (e.g., uplink and / or downlink communication) between the base station 602 and the UE 604. For example, the base station 602 can determine that communication through the fifth beam 620e is degraded (e.g., radio link failure) and / or another beam can provide better quality than the fifth beam 620e. Therefore, the base station 602 can determine that a new serving beam in the beams 620a-h can be used for communication 640 with the UE 604.

[0117] Based on determining to perform beam tracking, base station 602 may perform beam tracking with UE 604. In various aspects, beam tracking may include one or more operations associated with identifying or selecting a new active beam or a new serving beam for communication between base station 602 and UE 604.

[0118] According to one aspect of beam tracking, the base station 602 may transmit at least one of the BRSs 612a-h. The UE 604 may receive one or more of the BRSs 612a-h, each of which may correspond to a corresponding beam in the beams 620a-h. The UE 604 may select or identify at least one beam index corresponding to one of the beams 620a-h based on the reception of the one or more BRSs 612a-h (e.g., the UE 604 may identify one or more BRSs 612a-h with the highest signal quality). The UE 604 may transmit to the base station 602 a first indication of one or more beam indices corresponding to one or more of the beams 620a-h having the best (e.g., highest) signal quality measured for the corresponding received BRSs in the BRSs 612a-h (e.g., a beam index corresponding to the sixth beam 620f). Based on the first indication of the one or more beam indices, the base station 602 may transmit one or more BRRSs 614c-f. For example, the base station 602 may transmit the BRRS 614c-f by being close to or adjacent to the corresponding beam 620c-f of the one or more beams corresponding to the one or more beam indices indicated by the first indication. The UE 604 may receive one or more of the BRRS 614c-f, each of which may correspond to a corresponding beam in the beams 620c-f. The UE 604 may select or identify at least one beam index corresponding to one of the beams 620c-f based on the reception of the one or more BRRS 614c-f (e.g., the UE 604 may identify the one or more BRRS 614c-f with the highest signal quality). The UE 604 may send a second indication to the base station 602 of one or more beam indices corresponding to one or more of the beams 620c-f having the best (e.g., highest) signal quality measured for the corresponding received BRRS in the BRRS 614c-f (e.g., the beam index corresponding to the sixth beam 620f). The base station 602 and the UE 604 may communicate via the new active beam (which may correspond to the beam index indicated by the second indication, such as the sixth beam 620f).

[0119] According to one aspect of beam tracking, the UE 604 may send a request 648 (e.g., a BAR) for beam tracking. The request 648 for beam tracking may request the base station 602 to send the BRRS 614c-f. Based on the request 648 for beam tracking, the base station 602 may send one or more BRRS 614c-f. For example, the base station 602 may send the BRRS 614c-f through a corresponding beam 620c-f that is close to or adjacent to the first active beam (e.g., the fifth beam 620e). The UE 604 may receive one or more of the BRRS 614c-f, each of which may correspond to a corresponding beam in the beams 620c-f. The UE 604 may select or identify at least one beam index corresponding to one of the beams 620c-f based on the reception of the one or more BRRS 614c-f (e.g., the UE 604 may identify one or more BRRS 614c-f with the highest signal quality). The UE 604 may send an indication of one or more beam indices corresponding to one or more of the beams 620c-f having the best (e.g., highest) signal quality measured for the corresponding received BRRSs in the BRRSs 614c-f (e.g., a beam index corresponding to the sixth beam 620f) to the base station 602. The base station 602 and the UE 604 may communicate via the new active beam (which may correspond to the beam index indicated by the indication, such as the sixth beam 620f).

[0120] In one aspect, the base station 602 may determine to perform beam tracking with the UE 604 based on the communication 640 with the UE 604. For example, the base station 602 may send a message 642 to the UE 604 indicating that beam tracking is to be performed (e.g., based on determining that beam tracking is to be performed). In one aspect, the base station 602 may send the message 642 on a PDCCH (e.g., xPDCCH) or a PDSCH (e.g., xPDSCH). In one aspect, the base station 602 may send the message 642 as a DCI on the PDCCH. For example, one or more bits associated with the DCI may be reserved for indicating the message 642, and the base station 602 may use one or more reserved bits of the DCI to indicate the message that beam tracking is to be performed. The reserved bits may vary according to the DCI format.

[0121] In one aspect, the base station 602 may send the message via the fifth beam 620e (which may be the current active beam or the current serving beam). In other words, the base station 602 may send the message 642 to the UE 604 using the first RAT (e.g., mmW RAT). In another aspect, the base station 602 may send the message 642 to the UE via the second RAT 610 (which may have a lower carrier frequency (e.g., sub-6 GHz or LTE RAT) compared to the first RAT).

[0122] In one aspect, the UE 604 may acknowledge the message 642, such as by sending an ACK message. The UE 604 may send the acknowledgement message via the first RAT or the second RAT 610. Subsequently, the base station 602 and the UE 604 may perform beam tracking using the first RAT. In one aspect, when no acknowledgement is received in response to the message 642 (e.g., within a predetermined time period), the base station 602 may perform beam tracking (such as sending BRS 612a-h).

[0123] In one aspect, the base station 602 may communicate with the UE 604 using the currently active beam (e.g., the fifth beam 620e) by sending a reference signal 644 to the UE 604. For example, the base station 602 may send the reference signal 644 to determine whether the currently active beam (e.g., the fifth beam 620e) is failing. According to various aspects, the reference signal 644 may be a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS (e.g., the BRS 612e).

[0124] In one aspect, if the base station 602 does not receive a response to the reference signal 644, the base station 602 may determine that the currently active beam (e.g., the fifth beam 620e) is failing. In another aspect, the UE 604 may send a response 646, for example, based on the reference signal 644. The base station 602 may detect a radio link failure (e.g., determine that the currently active beam is failing) based on the response 646. For example, the base station 602 may detect a radio link failure by determining a value based on the response 646 and comparing the value to a predetermined threshold.

[0125] In one aspect, the UE 604 may send the response 646 via a second RAT 610 (e.g., a sub-6 GHz or LTE RAT). For example, the UE 604 may measure values ​​(e.g., SINR, SNR, RSSI, RSRP, RSRQ, etc.) and determine that the current active beam is failing, and therefore, send the response 646 using the second RAT 610 to increase the probability that the base station 602 receives the response 646. In another aspect, the UE 604 may send the response 646 via a first RAT (e.g., a mmW RAT). The response 646 may include at least one of CQI, SINR, SNR, RSSI, RSRP, RSRQ, etc.

[0126] In one aspect, base station 602 may select and send a reference signal for radio link failure for a specific transmission point such that the reference signal is limited to the specific transmission point. For example, the transmission point may be a different sector of the same base station and / or a coordinated multi-point transmission from a different base station, such as where a controller indicates the transmission attributes to the base station. The transmission point may also be an antenna port of a base station. For example, base station 602 may select a reference signal (similar to reference signal 644) to be sent in a sector including UE 604. Base station 602 may allow separate radio link failure procedures for separate transmission ports.

[0127] The UE 604 may receive at least a first reference signal 644 and may monitor the first reference signal 644 to determine whether an event exists, which may be a Qin event or a Qout event. For a Qin event, the UE 604 may measure one or more metrics associated with the first reference signal 644 (e.g., signal quality, received power, RSSI, SNR, etc.) to determine whether the one or more metrics are greater than or equal to a threshold. For a Qout event, the UE 604 may measure one or more metrics associated with the first reference signal 644 (e.g., signal quality, received power, RSSI, SNR, etc.) to determine whether the one or more metrics are less than or equal to a threshold, which may indicate a wireless link failure. In one aspect, the one or more metrics may include at least an SNR or an SINR.

[0128] In one aspect, the UE 604 may detect a radio link failure using the first reference signal 644. In another aspect, the UE 604 may detect a radio link failure using multiple reference signals (including the reference signal 644). For example, the UE 604 may use the best SNR estimate or another metric among all reference signals (including the reference signal 644) associated with multiple beams (e.g., the fourth beam 620d, the fifth beam 620e, the sixth beam 620f). In another example, the UE 604 may combine one or more metrics measured from the reference signals (including the reference signal 644) to detect a radio link failure.

[0129] In one aspect, for different receive beams or subarrays, the UE 604 may maintain separate radio link failure procedures, for example, using reference signals associated with different receive beams or subarrays. For example, the UE 604 may maintain a procedure for a currently active beam (e.g., the fifth beam 620e), which may be based on monitoring the first reference signal 644. In addition, the UE 604 may maintain another procedure for a first candidate beam (e.g., the sixth beam 620f), which may be based on monitoring a second reference signal (e.g., the sixth BRS 612f) associated with the first candidate beam (e.g., the sixth beam 620f).

[0130] In one aspect, when the UE 604 detects a radio link failure, the UE 604 and the base station 602 may perform beam tracking. In one aspect, when the radio link failure is detected, the UE 604 may request a beam tracking process with the base station 602. For example, the UE 604 may send a BAR. In one aspect, for example, the UE 604 may send an indication of the detected radio link failure so that the base station 602 may determine to perform beam tracking with the UE 604.

[0131] In one aspect, the base station 602 may determine to perform beam tracking with the UE 604 based on the absence of communication 640. For example, when the base station 602 expects the UE 604 to send one or more messages to the base station 602, but the one or more messages are not present (e.g., within a predetermined time period), the base station 602 may determine to perform beam tracking with the UE 604. For example, the base station 602 may schedule communication 640 with the UE 604 on the PUCCH and / or PUSCH. If the base station 602 determines that there is no communication 640 on the PUCCH and / or PUSCH (e.g., when the UE 604 is scheduled), the base station 602 may determine to perform beam tracking with the UE 604. Similarly, for example, if the base station 602 expects an ACK / NACK message (e.g., for the message 642, for the reference signal 644, etc.), but the ACK / NACK message is not present (e.g., within a predetermined time period), the base station 602 may determine to perform beam tracking with the UE 604. Similarly, if the base station 602 receives multiple NACK messages (eg, a threshold number of NACK messages are received before an ACK message is received), the base station 602 may determine that beam tracking is to be performed with the UE 604 .

[0132] In one aspect, the UE 604 may operate in accordance with DRX and, therefore, may alternate between a continuous reception period (e.g., during which the UE 604 is active and receiving) and a DRX period (e.g., during which the UE 604 is inactive and not receiving). DRX may affect the currently active beam (e.g., the fifth beam 620e), such as when the UE 604 moves during the DRX period. Thus, when the UE 604 transitions from DRX to a continuous reception period, the UE 604 may use a synchronization subframe or a tracking subframe to discover the beam. In one aspect, the base station 602 may send a signal (e.g., a BRS 612 in a synchronization subframe or a BRRS 614 in a tracking subframe). In one aspect, the tracking signal may serve many UEs sharing the same DRX cycle. The UE 604 may monitor a subset of tracking signals in a synchronization subframe based on one or more active beam indices from a previous DRX cycle. In another aspect, the base station 602 may use the active beam of the previous continuous reception cycle of the UE 604 to determine the beam index that the base station 602 should send during the beam tracking session.

[0133] In one aspect, the base station 602 may consider semi-persistent scheduling as a type of trigger for beam tracking, which may be based on the DRX duration (e.g., one PDCCH triggers multiple tracking signal transmissions on multiple subframes). That is, the base station 602 may determine to perform beam tracking based on the DRX duration. In one aspect, the base station 602 may determine to perform beam tracking with the UE 604 by determining the time when the UE 604 is to transition from an inactive period of DRX to an active period of DRX. For example, when the UE 604 is in an inactive DRX period, the currently active beam (e.g., the fifth beam 620e) may fail. The base station 602 may know the DRX period for the UE 604 and may determine to perform beam tracking corresponding to the time when the UE 604 is to transition from an inactive period and into an active period for reception.

[0134] In one aspect, the base station 602 may perform beam tracking based on the first active beam. For example, when the current active beam (e.g., the fifth beam 620e) is being used, the UE 604 may transition to an inactive DRX cycle. The UE 604 may not drift too far during the inactive DRX cycle, and thus when the UE 604 performs beam tracking after the inactive DRX cycle, the base station 602 may use a beam close to the current active beam (e.g., the fifth beam 620e). The base station 602 may, for example, send a message 642 indicating that beam tracking is to be performed based on the time at which the UE 604 is to transition from the inactive DRX cycle to the active DRX cycle.

[0135] Reference Figure 7 , a diagram of a wireless communication system 700 is shown. Base station 702 can be an aspect of base station 602, base station 502, base station 310, base station 102, mmW base station 180, and / or another base station. UE 704 can be an aspect of UE 604, UE 504, UE 350, UE 104, UE 182, and / or another UE.

[0136] In various aspects, the base station 702 and the UE 704 can communicate via a first active beam, such as the fifth beam 720e. In some aspects, the UE 704 may need to indicate a beam from the beams 720a-h to the base station 702, for example, when communication via the fifth beam 720e deteriorates, when the UE 704 transitions from an inactive DRX cycle to an active DRX cycle, etc. However, the base station 702 may detect a transmission from the UE 704 in the direction of the fifth beam 720e.

[0137] According to various aspects, UE 704 may send a request 750 to change an active beam to base station 702. Request 750 may indicate a beam index corresponding to a new beam. In one aspect, UE 704 may use a Zadoff-Chu sequence to indicate a beam change request.

[0138] In some aspects, the UE 704 and the base station 702 may communicate via the fifth beam 720e (which may be the current active beam). The UE 704 may identify or select a new beam (such as the sixth beam 720f) for communication with the base station 702. For example, the UE 704 may determine that communication via the fifth beam 720e is deteriorating or unsatisfactory. The UE 704 may select or identify the sixth beam 720f as the new beam, for example, based on measuring the signal quality of the BRS and / or BRRS transmitted via the sixth beam 720f. The UE 704 may generate a request 750 to change the active beam from the fifth beam 720e to the sixth beam 720f. The UE 704 may generate a request 750 indicating a beam index corresponding to the sixth beam 720f. The UE 704 may send the request 750 to the base station 702.

[0139] In one aspect, the UE 704 may generate a request 750 indicating a beam index corresponding to a new beam (e.g., the sixth beam 720f) based on the cyclic offset. For example, the UE 704 and / or the base station 702 may maintain a mapping of one or more cyclic offsets to one or more corresponding beam indices. In a further example, one or more bits of the request 750 may correspond to the beam index of the new beam. The UE 704 may identify the cyclic offset corresponding to the sixth beam 720f and may send the request 750 with the identified cyclic offset corresponding to the sixth beam 720f. Thus, the base station 702 may receive the request 750 with the cyclic offset and identify the beam index associated with the cyclic offset to determine the sixth beam 720f corresponding to the beam index.

[0140] In one aspect, the UE 704 may generate a request 750 indicating a beam index corresponding to a new beam (e.g., the sixth beam 720f) based on the spreading across symbols. For example, the UE 704 and / or the base station 702 may maintain a mapping of one or more spreading across symbols to one or more corresponding beam indices. The UE 704 may identify the spreading across symbols corresponding to the sixth beam 720f and may send the request 750 with the identified spreading across symbols corresponding to the sixth beam 720f. Thus, the base station 702 may receive the request 750 with the spreading across symbols and identify the beam index associated with the spreading across symbols to determine the sixth beam 720f corresponding to the beam index.

[0141] In one aspect, the UE 704 may generate a request 750 indicating a beam index corresponding to a new beam (e.g., the sixth beam 720f) based on the one or more subcarriers carrying the request 750. For example, the UE 704 and / or the base station 702 may maintain a mapping of the one or more subcarriers to the one or more corresponding beam indices. The UE 704 may identify the one or more subcarriers corresponding to the sixth beam 720f and may send the request 750 on the identified one or more subcarriers corresponding to the sixth beam 720f. Thus, the base station 702 may receive the request 750 on the one or more subcarriers and identify the beam index associated with the one or more subcarriers to determine the sixth beam 720f corresponding to the beam index.

[0142] Based on the beam index indicated by the request 750, the base station 702 may change the active beam from the fifth beam 720e to the sixth beam 720f. Subsequently, the base station 702 and the UE 704 may communicate via the sixth beam 720f. The communication may be uplink and / or downlink communication.

[0143] In one aspect, the UE 704 may use a subframe 740 to indicate a new beam (e.g., because beamforming may not be required for a RACH in a cell provided by the base station 702). In some aspects, the subframe 740 may be a RACH subframe. The subframe 740 may include a plurality of resources, for example, 10 time resources (e.g., time slots) and 12 frequency resources (e.g., carriers). The subframe 740 may include resources 742 (e.g., SR sets or regions) for scheduling requests (SRs) and resources 744 (e.g., RACH sets or regions) for RACHs. Each resource may include six physical resource blocks (PRBs), and each PRB may include twelve tones.

[0144] In one aspect, at least one of the base station 702 and / or the UE 704 may maintain a mapping between beams (e.g., beams 720a-h) associated with a synchronization (e.g., BRS) session and / or a RACH session. That is, the UE 704 may be configured to indicate a beam index using one or more resources of the subframe 740, such as by sending a request 750 on at least one resource corresponding to the beam index selected by the UE 704.

[0145] In one aspect, the subframe 740 may include SR resources 742 (e.g., SR sets). The UE 704 may indicate a selected beam on resources not included in the SR resources 742. The UE 704 may be configured to select a beam from among the beams 720a-h, and each of the beams 720a-h may correspond to a beam index. The UE 704 may select a beam from among the beams 720a-h, for example, based on measuring a signal quality of one or more BRSs or BRRSs received through one or more of the beams 720a-h. For example, the UE 704 may select a new beam (e.g., the second beam 720b), and the UE 704 may be configured to send the request 750 as a RACH sequence in symbol 0 and / or 1 of a resource not included in the SR resources 742 if the selected beam index corresponding to the new beam (e.g., the second beam 720b) ​​corresponds to one of the beams 720a-d. Similarly, UE 704 may be configured to send request 750 as a RACH sequence in symbols 2 and / or 3 of resources not included in SR resources 742 if the selected beam index corresponds to one of beams 720e-h.

[0146] In one aspect, the UE 704 may use at least one subcarrier to indicate a particular beam within the range. For example, the UE 704 may indicate a beam within the range of beams 720a-d by using at least one of the subcarrier pairs 770, 772, 774, 776. Similarly, the UE 704 may indicate a beam within the range of beams 720e-h by using at least one of the subcarrier pairs 770, 772, 774, 776. For example, subcarrier 770 may indicate a first beam of the range, and thus, when the UE 704 sends a RACH sequence on symbols 0 and 1 and subcarrier 770 (corresponding to the first beam within the range of beams), the UE 704 is indicating the selected first beam 720a. As another example, the UE 704 may indicate the selected seventh beam 720g by sending a RACH sequence on subcarrier 774 (corresponding to the third beam in the range of beams) on symbols 2 and 3 (corresponding to the range of beams 720e-h). As another example, the UE 704 may indicate the selected sixth beam 720f by sending a RACH sequence on subcarrier 772 (corresponding to the second beam in the range of beams) on symbols 2 and 3 (corresponding to the range of beams 720e-h). Therefore, the base station 702 may determine the selected beam index based on at least the resource on which the RACH sequence is sent (which is a resource not included in the SR resources 742).

[0147] In another aspect, the UE 704 may indicate the selected beam using resources not included in the RACH resources 744. In one aspect, the BAR procedure may be configured in the UE 704. For example, if a dedicated SR for BRRS request is configured for the UE 704, the PHY layer of the UE 704 may signal the dedicated SR for BRRS request in resources not included in the RACH resources 744.

[0148] In one aspect, when the UE 704 is timing aligned with the base station 702, the UE 704 may transmit only on resources not included in the RACH resources 744 (which include the SR resources 742). The number of available cyclic offsets associated with resources not included in the RACH resources 744 may be higher than those available cyclic offsets in the RACH resources 744. Thus, there may be higher degrees of freedom (e.g., 192 degrees of freedom) associated with resources not included in the RACH resources 744 compared to the RACH resources 744 (e.g., 48 degrees of freedom). For example, multiple UEs may be able to send requests (e.g., requests for beam tracking and / or BRRS, BAR, etc.) on resources not included in the RACH resources 744. That is, different cyclic offsets and / or different extensions across symbols may be used to distinguish between different UEs at the base station 702. For example, the UE 704 may send a Zadoff-Chu sequence in two symbols, while another UE may multiply the sequence by [+1, -1] and send the product.

[0149] In one aspect, the UE 704 may select a transmission time for the SR based on the symbol index of the strongest beam (e.g., the beam in which the strongest BRS is received during the synchronization subframe). In one aspect, if directed by higher layers, the UE 704 may send the SR during subframe 740. For example, a plurality of parameters may be provided to the PHY layer of the UE 704, including the frequency band number N. SR , cyclic offset v, root u, parameter f′, system frame number (SFN), BRS transmission period N BRS , the number of symbols N during subframe 740 RACH (Base station 702 may apply different beams (e.g., different receive beams) for subframe 740), the number of subframes M in each frame (e.g., the number of RACH subframes), the index m of the current subframe (e.g., the current RACH subframe), the symbol with the strongest synchronization beam The root u may be cell specific. The UE 704 may be based on SFN, N BRS 、N RACH , M, m, and to compute the symbol index l. For example,

[0150]

[0151] Where N rep The number of symbols dedicated to a single RACH transmission may be indicated (eg, N rep =2).

[0152] In one aspect, at least one of the base station 702 and / or the UE 704 maintains a mapping between beams (e.g., beams 720a-h) associated with the synchronization (or BRS) session and resources not included in the RACH resources 744. That is, the UE 704 may be configured to indicate a beam index using one or more resources of the subframe 740, such as by sending a request 750 on at least one resource corresponding to the beam index selected by the UE 704.

[0153] For example, the UE 704 may be configured to send the request 750 in symbols 0 and 1 of the subframe 740 if the selected beam index (e.g., the second beam 720b) ​​corresponds to one of the beams 720a-d. Similarly, the UE 704 may be configured to send the request 750 in symbols 2 and 3 of the subframe 740 if the selected beam index corresponds to one of the beams 720e-h.

[0154] In one aspect, the UE 704 may use at least one subcarrier to indicate a particular beam within the range. For example, the UE 704 may indicate a beam within the range of beams 720a-d by using at least one of the subcarrier pairs 760, 762, 764, 766. Similarly, the UE 704 may indicate a beam within the range of beams 720e-h by using at least one of the subcarrier pairs 760, 762, 764, 766. For example, subcarrier 760 may indicate a first beam of the range, and thus, when the UE 704 sends the request 750 on symbols 0 and 1 and subcarrier 760, the UE 704 is indicating the selected first beam 720a. As another example, the UE 704 may indicate a selected seventh beam 720g by sending a request on subcarrier 764 (corresponding to the third beam within the range) on symbols 2 and 3 (corresponding to the range of beams 720e-h). Thus, the base station 702 may determine the selected beam index based on the at least one resource on which the request is sent.

[0155] Reference Figure 8, a diagram of a wireless communication system 800 is shown. Base station 802 can be an aspect of base station 702, base station 602, base station 502, base station 310, base station 102, mmW base station 180, and / or another base station. UE 804 can be an aspect of UE 704, UE 604, UE 504, UE 350, UE 104, UE 182, and / or another UE.

[0156] exist Figure 8 In the example, UE 804 may use active beam 820e (e.g., active beam 820e may be Figure 7 804 can communicate with the base station 802 via a set of beams 840d-e at the UE 804. In one aspect, the active beam 802e can be paired with the first beam 840d at the UE 804, and they can form an active beam pair. Similarly, the control information beam 820f can be paired with the second beam at the UE 804, and they can form a control information beam pair. The UE 804 can identify a beam pair for communication (e.g., uplink and / or downlink communication) with the base station 802. In one aspect, the UE 804 can be configured to monitor a control channel (e.g., PDCCH, ePDCCH, new radio (NR) PDCCH, etc.) on one or more beam pair links at the same time and / or the UE 804 can monitor a control channel on different beam pair links in different OFDM symbols.

[0157] Each of the UE 804 and / or the base station 802 may maintain a candidate beam index set 830. In one aspect, the candidate beam index set 830 includes at least a beam index corresponding to the control information beam 820f (eg, the control information beam 820f may be Figure 7 The candidate beam index set 830 may include additional beams 720d, 720g, 720h (e.g., as described with respect to Figure 7 804). The base station 802 and / or the UE 804 may maintain a set of candidate beam indices 830 to include additional beams 720d, 720g, 720h that are not currently used for communication with the UE 804 (e.g., the base station 802 may generate one or more of the additional beams 720d, 720g, 720h based on the request 750 to change the active beam). In one aspect, the set of candidate beam indices 830 may include a set of beam pairs, such as beam pairs 820f, 840e.

[0158] Each of the UE 804 and / or the base station 802 may maintain an active beam index set, which may be similar to the candidate beam index set 830. The active beam index set may include one or more beam indices (including the active beam 820e) to be used for communication between the base station 802 and the UE 804. The base station 802 and / or the UE 804 may maintain the active beam index set to include additional beams (e.g., another one of the beams 720a-h) that may be used for uplink or downlink communication between the base station 802 and the UE 804. In one aspect, the active beam index set may include a set of beam pairs, such as beam pairs 820e, 840d.

[0159] The base station 802 and the UE 804 may maintain two beam sets: an active set and a candidate set. The active set may include an active beam 820e. The candidate set may include at least one beam that may be a candidate for communication between the base station 802 and the UE 804 (e.g., if the active beam 820e fails). In one aspect, the candidate beam set may include a control information beam 820f.

[0160] In one aspect, the UE 804 sends control information on the control channel so that it is received at the base station 802 using the active beam 820e. In one aspect, the control channel can be a PUCCH. However, the base station 802 can periodically receive the control information 844 carried on the control channel via a second beam. For example, the UE 804 can send the control information 844 to the base station 802 using the control information beam 820f. In one aspect, the control information beam 820f can correspond to the second beam 840e at the UE 802. Therefore, the UE 804 can identify or select the second beam 840e through which to send the control information 844 based on the use of the control information beam 820f instead of the active beam 820e.

[0161] In one aspect, the UE 804 and the base station 802 may also be configured to communicate using a wide beam 822. For example, the base station 802 and the UE 804 may communicate using a mmW RAT or a near mmW RAT, wherein the beamforming weights of the active beam 820e and the control information beam 820f may have a first beam weight, and the wide beam 822 may have a second beam weight that is greater than the first beam weight. In one aspect, the base station 802 may sample the antenna weights of the base station 802 so that a wider area of ​​a sector associated with the base station 802 is covered. In one aspect, the wide beam 822 may have an angle that is larger than an angle of at least one of the active beam 820e and / or the control information beam 820f. For example, the active beam 820e and / or the control information beam 820f may have an angle of approximately five or six degrees, and the wide beam 822 may have an angle of approximately twenty or thirty degrees.

[0162] In one aspect, the wide beam 822 may be directed to at least one beam at the UE 804. For example, the wide beam 822 may be directed to the second beam 840e at the UE 804, and thus, when the UE 804 monitors the antenna port or subarray associated with the second beam 840e, the UE 804 may receive information transmitted by the base station 802 through the wide beam 822.

[0163] In one aspect, the UE 804 may periodically send information 844 (e.g., control information) to the base station 802 via the wide beam 822. The UE 804 may measure signal quality or channel estimates associated with communications with the base station 802. For example, the UE 804 may measure signal quality (e.g., SNR, SINR, received power, received quality, etc.) of a signal (e.g., BRS, CSI-RS, reference signal, etc.), and the UE 804 may send the signal quality or channel estimate to the base station 802. In various aspects, the information may include UCI, CQI, SR, and / or other control information. For example, if the active beam 820e and / or the control information beam 820f fails and / or becomes unsatisfactorily degraded, the base station 802 may receive the signal quality or channel estimate via the wide beam 822.

[0164] In one aspect, the UE 804 may transmit information (e.g., control information 844 on a control channel such as a PUCCH) via the wide beam 822 without explicit signaling from the base station 802. For example, the UE 804 may determine that the UE 804 will transmit information via the wide beam 822 after there is no signaling from the base station 802 on the active beam 820e and / or the control information beam 820f.

[0165] Thus, the base station 802 may receive information (e.g., control information 844) from the UE 804 via the wide beam 822. In one aspect, the base station 802 may determine, based on receiving the information via the wide beam 822, that at least one of the active beam 820e and / or the control information beam 820f has failed and / or become unsatisfactorily degraded.

[0166] In one aspect, the UE 804 may periodically send control information 844 on a control channel via the control information beam 820f. The base station 802 may estimate the uplink channel quality of the control information beam 820f based on the periodic reception of the control information 844 from the UE 804. In one aspect, the UE 804 may measure the quality (e.g., channel quality) associated with the active beam 820e and may generate the control information 844 to include an indication of the quality associated with the active beam 820e.

[0167] The base station 802 receives the information 844. Based on the information 844, the base station 802 can determine whether the active beam 820e is failing and / or is unsatisfactory (eg, the quality does not meet a threshold).

[0168] Although Figure 8 Transmission of information 844 via control information beam 820f is shown, but wide beam 822 may serve as a control information beam, as described above. For example, UE 804 may transmit information 844 via a beam corresponding to a beam index included in the candidate beam set and / or UE 804 may transmit information 844 via wide beam 822.

[0169] The UE 804 and the base station 802 may switch to a beam corresponding to a beam index included in the candidate beam index set for communication based on the control information 844. For example, the UE 804 and the base station 802 may switch to the control information beam 820f for communication (in this case, the control information beam 820f may become an active beam and may carry alternative control information 844 or other data in addition to the control information 844).

[0170] In one aspect, the UE 804 and the base station 802 may change the active beam to the control information beam 820f without explicit signaling (eg, the UE 804 does not need to send via RACH or SR to indicate the beam index, such as Figure 7 For example, UE 804 may determine to change the active beam based on information 844 (e.g., based on the signal quality included in information 844). Similarly, base station 802 may determine to change the active beam based on information 844.

[0171] In one aspect, the base station 802 may send information 842 to the UE 804 indicating a periodicity with which control information is to be sent from the UE 804 to the base station 802 on a control channel. In one aspect, the base station 802 may send the information 842 via the active beam 820e. In one aspect, the base station 802 may send the information 842 to the UE 804 using RRC signaling. In another aspect, the base station 802 may send the information 842 to the UE 804 on the PDCCH. For example, the base station 802 information 842 may indicate the periodicity to the UE 804 using one or more bits of the DCI (e.g., one or more bits of the information 842 reserved for indicating the periodicity) and / or via a DCI format.

[0172] The UE 804 may receive the information 842 and may determine a period based on the information 842. The UE 804 may periodically send the control information 844 to the base station 802 using the determined period.

[0173] Fig. 9A , 9B , 9C, 9D, and 9E illustrate an exemplary wireless communication environment including at least a base station 902 and a UE 904. Base station 902 may be an aspect of base station 802, base station 702, base station 602, base station 502, base station 310, base station 102, mmW base station 180, and / or another base station. UE 904 may be an aspect of UE 804, UE 704, UE 604, UE 504, UE 350, UE 104, UE 182, and / or another UE.

[0174] The UE 904 may include one or more antenna arrays and / or one or more subarrays. The UE 904 may receive one or more reference signals (e.g., PSS / SSS, discrete long sphere sequence (DPSS), CSI-RS, BRRS, etc.) from the base station 902 through one or more beams, wherein the one or more beams may be received at multiple antennas of the UE 904 according to multiple reception angle ranges, and the multiple reception angle ranges may be detected at a reception combiner at the UE 904. Data communication between the base station 902 and the UE 904 may require a combination of one or more of the following: an optimal beam (corresponding to a beam index) at the base station 902, an optimal subarray at the UE 904 (e.g., a subarray at which the highest reception power of the one or more reference signals is detected), and / or an optimal reception combiner at an optimal array or subarray at the UE 904 (e.g., a reception combiner at which the highest reception power of the one or more reference signals is detected).

[0175] In one example, base station 902 may scan through the transmission direction according to the order ABCD to transmit one or more reference signals (e.g., reference signal 950). In another example, base station 902 may scan through the transmission direction according to the order BDAC. Fig. 9A Only four transmission directions and two transmission orders are described, but any number of different transmission directions and transmission orders are contemplated.

[0176] In some aspects, the base station 902 may send out a reference signal (e.g., reference signal 950) over multiple consecutive symbols (albeit in different directions ABCD). The base station 902 may scan across the entire sector.

[0177] Reference Fig. 9B , the UE 904 may listen or detect for reference signals in different reception directions (e.g., directions E, F, G, and H). In one example, the UE 904 may scan through the reception directions according to the order EFGH. In another example, the UE 904 may scan through the reception directions according to the order FHEJ. Although only four reception directions and two reception orders are described, any number of different reception directions and reception orders are contemplated.

[0178] In some aspects, the UE 904 may try different receive subarrays in different time periods (such as four reference signal periods). The UE 904 may find the optimal subarray after the reference signal period. For example, the UE 904 may measure the signal quality of each reference signal received at the corresponding subarray during the corresponding time period.

[0179] UE 904 may determine the optimal subarray to be the subarray with the highest signal quality measured for the reference signal, the subarray with the highest average signal quality of the set of reference signals received during the period in which the subarray is used, or another method of selecting the optimal subarray.

[0180] Fig. 9C Aspects of a reference signal 950 are shown. The reference signal 950 may be repeated in consecutive subframes, slots, or subslots. Fourteen symbols may be reserved for the reference signal 950; however, the reference signal 950 may not be sent during every symbol. For example, the reference signal 950 may be sent via a first beam on one of the fourteen symbols, and another reference signal may be sent via a second beam on a different symbol in the fourteen symbols. The reference signal may be one or more of a PSS, SSS, BRS, BRRS, CSI-RS, DPSS, etc.

[0181] Fig.9DA wireless communication system 960 is shown in which a time slot 962 includes fourteen symbols. One or more of the fourteen symbols may be used for a reference signal, such as reference signal 950. In the illustrated aspect, the base station 902 may transmit three beams 970, 972, 974 (e.g., a set of fine beams). The base station 902 may transmit the reference signal via the set of beams 970, 972, 974 in the last three symbols 964, 966, 968 of the time slot 962.

[0182] The base station 902 may cause the reference signal to occupy one of every fourth tone in each of the three symbols 964, 966, 968. The base station 902 may repeat the reference signal four times in each of the three symbols 964, 966, 968.

[0183] In some aspects, the UE 904 may try different receive combiners in different time periods (such as four reference signal periods for each of the three symbols 964, 966, 968). The UE 904 may find the optimal receive combiner after the reference signal period. For example, the UE 904 may measure the signal quality of each reference signal received at the corresponding receive combiner during the corresponding period. The UE 904 may determine the optimal receive combiner by determining the receive combiner at which the highest signal quality is measured for the reference signal, the receive combiner at which the highest average signal quality is measured for the reference signal set (the reference signal set is received during the period in which the receive combiner is used), or another method of selecting the optimal receive combiner.

[0184] Additionally, the UE 904 may select an optimal beam corresponding to a beam index at the base station 902 based on the reference signal received during the three symbols 964, 966, 968. For example, the UE 904 may determine the highest signal quality corresponding to the reference signal received during one of the three symbols 964, 966, 968. For example, since each symbol set of the three symbols 964, 966, 968 may correspond to a different beam, the UE 904 may determine the beam index corresponding to the beam at the base station 902. The UE 904 may communicate with the base station 902 through the optimal beam corresponding to the beam index (e.g., the UE 904 may send information indicating the beam index to the base station 902).

[0185] Fig.9EAn exemplary wireless communication environment 980 is shown that includes at least a base station 902 and a UE 904. In some aspects, the base station 902 may need to transmit one or more beam indices to the UE 904, for example, to initiate reference signal transmission. In one aspect, the reference signal may include one or more of an MRS, a BRRS, a BRS, a CSI-RS, a PSS, a SSS, a DPSS, etc. Based on the reference signal transmission, the UE 904 may determine an optimal subarray and / or a receive combiner at the UE 904.

[0186] The base station 902 may determine one or more indexes associated with one or more beams 972, 974, 976. According to one aspect, the base station 902 may receive one or more beam indices, such as BSIs, corresponding to the one or more beams 972, 974, 976. The base station 902 may determine to send one or more reference signals via one or more beams corresponding to the one or more beam indices most recently indicated to the base station 902 by the UE 904.

[0187] For example, during reference signal transmission, the base station 902 may transmit different types of beams. In one aspect, the base station 902 may transmit a BRS beam (e.g., a coarse beam). The base station 902 may need to transmit one or more indexes associated with one or more BRS beams to the UE 904. In such an aspect, if the BRS duration period is four time slots or subframes, nine bits may be required, for example, in the case of eight antenna ports, the number of symbols per subframe is fourteen. The UE 904 may send information to the base station 902 indicating one or more beam indices corresponding to one or more beams 972, 974, 976 through which one or more BRS are received.

[0188] According to another aspect, the base station 902 can determine one or more indexes associated with one or more beams 972, 974, 976 based on beams previously reported from the UE 904. For example, the base station 902 can send the most recent beam that the UE 904 may have reported. For example, the UE 904 can report one or more beam indexes based on one or more BRS received through one or more beams (e.g., beams 972, 974, 976), which can be sent by the base station 902 during a synchronization time slot or subframe.

[0189] In some aspects, the UE 904 may send information (e.g., BSI) indicating a beam index to the base station 902 via the PUCCH or PUSCH (e.g., the UE 904 may send more information via the PUSCH than via the PUCCH). The beam set used to train the UE 904 receive beam may be implicitly derived based on the most recently reported information and / or channel type used to transmit the information.

[0190] In one aspect, if the base station 902 schedules the reference signal in one or two symbols, the base station 902 may reuse the beam information received by the base station on the PUCCH from the UE 904. In another aspect, if the base station 902 schedules the reference signal in more than two symbols, the base station 902 may reuse the beam information received by the base station 902 during the PUSCH from the UE 904. The base station 902 may use a few bits (e.g., less than nine bits) to send one or more beam indexes to the UE 904 indicating one or more previously reported beams.

[0191] In another aspect, the base station 902 may determine one or more beam indexes based on finer beams 972, 974, 974 previously sent to the UE 904. The finer beams 972, 974, 974 may have been previously used for transmission of one or more reference signals (e.g., MRS, CSI-RS, and / or BRRS). The base station 902 may only need to send a few bits (e.g., less than nine) to send information 990 indicating the fine beams 972, 974, 974 to the UE 904.

[0192] Based on the determined one or more beam indices, the base station 902 may send information 990 indicating the one or more beam indices to the UE 904. The base station 902 may send the information 990 on a control channel. In one aspect, the control channel may include a PDCCH. For example, the information 990 may be included in one or more bits of a DCI message of the PDCCH.

[0193] Based on the information 990, the UE 904 may determine one or more beam indices for the reference signal indicated by the information 990. Thereafter, the base station 902 may send one or more reference signals to the UE 904 through one or more beams 972, 974, 976 corresponding to the one or more beam indices.

[0194] The UE 904 may use an optimal subarray and / or receive combiner to detect the reference signal transmission. For example, the UE 904 may determine an optimal subarray and / or receive combiner for a symbol in which the reference signal is scheduled to be transmitted. Subsequently, the UE 904 may use the determined subarray and / or receive combiner to detect the reference signal.

[0195] Fig. 10A and 10B 1 is a flow chart of a method 1000, 1020 of wireless communication. The method 1000, 1020 may be performed by a base station (e.g., base station 602). In one aspect, the method 1000, 1020 may be performed by an apparatus. It will be understood by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0196] by Fig. 10A Initially, at operation 1002, the base station may transmit at least one BRS. For example, the base station may generate a BRS set, and the base station may transmit the BRS set through a beam set to be used for communication with a UE. Figure 6 In the context of , the base station 602 can transmit the set of BRSs 612a-h via the set of beams 620a-h, and each of the BRSs 612a-h can correspond to a beam in the beams 620a-h.

[0197] At operation 1004, the base station may receive an indication of a first beam index from the UE based on the BRS. The first beam index may be a coarse beam index to be used for beam refinement. Figure 6 In the context of , the base station 602 may receive an indication of a beam index corresponding to a coarse beam (such as the sixth beam 620f) from the UE 604. The indication may be a first indication 560, such as Figure 5A-5G Described in .

[0198] At operation 1006, the base station may transmit at least one BRRS based on the first indication of the first beam index. Figure 6 In the context of, the first indication may indicate a beam index corresponding to the sixth beam 620f, and the base station may send a fine beam set, such as by sending BRRS 614c-f on beams 620c-f that are close to the beam indicated by the coarse beam index.

[0199] At operation 1008, the base station may receive a second indication of a second beam index corresponding to the second beam based on the at least one BRRS. Figure 6 In the context of , the base station 602 may receive an indication of a beam index corresponding to a fine beam (such as the sixth beam 620f) from the UE 604. The indication may be a second indication 565, such as Figure 5A-5G Described in .

[0200] The base station may communicate with the UE via the beam corresponding to the index indicated in the second indication. The communication may be uplink communication and / or downlink communication.

[0201] Steering Fig. 10B , another method 1020 is shown for a base station for performing beam tracking. At operation 1022, the base station may receive a request for beam tracking from a UE. For example, the base station may receive a BAR. Figure 6 In the context of, base station 602 may receive a request for beam tracking from UE 604.

[0202] At operation 1024, the base station may transmit at least one BRRS based on the request for beam tracking. Figure 6 In the context of , the base station may transmit a refined beam set, such as by transmitting BRRS 614c-f on beams 620c-f that are close to the beams through which the base station 602 and the UE 604 previously communicated (eg, the fifth beam 620e).

[0203] At operation 1026, the base station may receive a second indication of a second beam index corresponding to the second beam based on the at least one BRRS. Figure 6 In the context of , the base station 602 may receive an indication of a beam index corresponding to a fine beam (such as the sixth beam 620f) from the UE 604. The indication may be a second indication 565, such as Figure 5A-5G Described in .

[0204] The base station may communicate with the UE via the beam corresponding to the index indicated in the second indication. The communication may be uplink communication and / or downlink communication.

[0205] Fig.11A and 11B 1 is a flow chart of a method 1100, 1120 of wireless communication. The method 1100, 1120 may be performed by a UE (eg, UE 604). In one aspect, the method 1100, 1120 may be performed by an apparatus. It will be appreciated by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0206] by Fig.11A Initially, at operation 1102, the UE may receive at least one BRS from a base station. Figure 6In the context of , UE 604 can receive a set of BRSs 612a-h from base station 602 via a set of beams 620a-h, and each of BRSs 612a-h can correspond to a beam in beams 620a-h.

[0207] At operation 1104, the UE may send an indication of a first beam index to the base station based on the BRS. The first beam index may be a coarse beam index to be used for beam refinement. For example, the UE may measure the signal quality or power of one or more received BRSs and select a beam index corresponding to a beam through which a BRS having an optimal or highest value is received. Figure 6 In the context of , UE 604 may send an indication of a beam index corresponding to a coarse beam (such as the sixth beam 620f) to base station 602. The indication may be a first indication 560, such as Figure 5A-5G Described in .

[0208] At operation 1106, the UE may receive at least one BRRS from the base station (e.g., based on the first indication of the first beam index). Figure 6 In the context of , UE 604 may receive a fine beam set, such as by receiving BRRS 614c-f on beams 620c-f that are close to the beam indicated by the coarse beam index.

[0209] At operation 1108, the UE may send a second indication of a second beam index corresponding to the second beam based on at least one BRRS. The second beam index may be a refined beam index to be used for communication. For example, the UE may measure the signal quality or power of one or more received BRRSs and select a beam index corresponding to a beam through which a BRRS having an optimal or highest value is received. Figure 6 In the context of , UE 604 may send an indication of a beam index corresponding to a fine beam (such as the sixth beam 620f) to base station 602. The indication may be a second indication 565, such as Figure 5A-5G Described in .

[0210] The UE may communicate with the UE via the beam corresponding to the index indicated in the second indication. The communication may be uplink communication and / or downlink communication.

[0211] Steering Fig. 11B , another method 1120 is shown for a base station for performing beam tracking. At operation 1122, the UE may send a request for beam tracking to the base station. For example, the UE may send a BAR. Figure 6 In the context of , UE 604 may send a request 648 (eg, BAR) for beam tracking to base station 602 .

[0212] At operation 1124, the UE may receive at least one BRRS from the base station based on the request for beam tracking. Figure 6 In the context of , the UE 604 may receive a refined set of beams, such as by receiving BRRS 614c-f on beams 620c-f that are close to a beam through which the base station 602 and the UE 604 previously communicated (eg, the fifth beam 620e).

[0213] At operation 1126, the UE may send an indication of a beam index corresponding to the beam to the base station based on at least one BRRS. For example, the UE may measure the signal quality or power of one or more received BRRSs and select a beam index corresponding to the beam through which the BRRS with the best or highest value is received. Figure 6 In the context of , UE 604 may send an indication of a beam index corresponding to a fine beam (such as the sixth beam 620f) to base station 602. The indication may be a second indication 565, such as Figure 5A-5G Described in .

[0214] The base station may communicate with the UE via the beam corresponding to the index indicated in the indication. The communication may be uplink communication and / or downlink communication.

[0215] Fig.12 1 is a flow chart of a method 1200 of wireless communication. The method 1200 may be performed by a base station (eg, base station 602). In one aspect, the method 1200 may be performed by an apparatus. It will be appreciated by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0216] Beginning with operation 1202, a base station may communicate with a UE via a first active beam. In one aspect, the communication may be a downlink communication. For example, the base station may determine data to be sent to the UE, and then the base station may send the determined data via the first active beam. In one aspect, the communication may be an uplink communication. For example, the base station may determine a time (e.g., a time slot) at which the UE is scheduled to send data to the base station, and then the base station may receive the data via the first active beam at the scheduled time. Figure 6 In the context of, the base station 602 can communicate with the UE 604 via a first active beam (such as the fifth beam 620e).

[0217] In one aspect, operation 1202 may include operation 1220. At operation 1220, the base station may send a reference signal to the UE to determine whether the first active beam is failing. In one aspect, the reference signal may be a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS. Figure 6 In the context of, the base station 602 may send a reference signal 644 via a first active beam (eg, the fifth beam 620e).

[0218] At operation 1204, the base station may determine to perform beam tracking with the UE. For example, the base station may determine that the first active beam is failing, and then the base station may initiate beam tracking to select a new active beam. Figure 6 In the context of, base station 602 can determine to perform beam tracking with UE 604.

[0219] In one aspect, operation 1204 may include operation 1222 and operation 1224. At operation 1222, the base station may receive a response from the UE based on a reference signal sent to the UE (e.g., the reference signal described at operation 1220). In one aspect, the response may include at least one of CQI, SINR, SNR, RSSI, RSRP, or RSRQ. Figure 6 In the context of , the base station 602 can receive a response 646 from the UE 604.

[0220] At operation 1224, the base station may detect a radio link failure based on the received response. For example, the base station may determine that a value (e.g., CQI, SINR, SNR, RSRP, RSRQ, etc.) may be below a threshold, and the base station may determine that the value below the threshold indicates a radio link failure. In another example, the base station may determine that the response indicates a NACK or an absence of a response, and the base station may determine that a radio link failure has occurred based on the NACK or the absence of a response. Figure 6 In the context of , the base station 602 can detect the radio link failure through the first active beam (e.g., the fifth beam 620e) based on the response 646 or based on the absence of the response 646.

[0221] In another aspect, operation 1204 may include operation 1226. At operation 1226, the base station may determine when the UE is to transition from an inactive period of DRX to an active period of DRX. Since the base station and the UE may not communicate when the UE is in an inactive DRX period, the base station may determine to perform beam tracking with the UE when the UE transitions to an active period of DRX (e.g., because the UE has drifted during the inactive DRX period). Figure 6In the context of, base station 602 can determine the DRX cycle of UE 604 (for example, base station 602 can configure the DRX cycle of UE 604), and when UE 604 is to transition from an inactive DRX cycle to an active DRX cycle, base station 602 can determine to perform beam tracking with UE 604.

[0222] In another aspect, operation 1204 may include operation 1228. At operation 1228, the base station may determine that there is no communication with the UE using the first active beam. For example, the base station may determine that the base station did not receive data from the UE when the UE was scheduled to communicate with the base station. In another example, the base station may receive one or more NACK messages indicating that there is no communication with the UE. Figure 6 In the context of , the base station 602 can determine that there is no communication 640 with the UE 604 using the first active beam (e.g., the fifth beam 620e).

[0223] At operation 1206, the base station may perform beam tracking with the UE based on the determination to perform beam tracking. For example, the base station may perform Fig. 10A and / or one or more operations described in 10B. Figure 6 In the context of, base station 602 can perform beam tracking with UE 604.

[0224] In one aspect, operation 1206 includes operation 1230. At operation 1230, the base station may send a message to the UE indicating that beam tracking is to be performed. The base station may send the message on the PDCCH or the PDSCH. Figure 6 In the context of , the base station 602 may send a message 642 to the UE 604 indicating that beam tracking is to be performed. Subsequently, the base station 602 may perform Fig. 10A and / or one or more operations described in 10B.

[0225] At operation 1208, the base station may communicate with the UE via the second active beam based on beam tracking. For example, the base station may receive from the UE an indication of a beam index corresponding to a beam at the base station. The base station may select a beam corresponding to the indicated beam index for at least one of uplink or downlink communications with the UE. Figure 6 In the context of, the base station 602 can communicate with the UE 604 via a second active beam (e.g., the sixth beam 620f).

[0226] Fig.131 is a flow chart of a method 1300 of wireless communication. The method 1300 may be performed by a UE (eg, UE 604). In one aspect, the method 1300 may be performed by an apparatus. It will be appreciated by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0227] Beginning with operation 1302, a UE may communicate with a base station via a first active beam. In one aspect, the communication may be a downlink communication. For example, the UE may receive data from the base station. In one aspect, the communication may be an uplink communication. For example, the UE may determine a time (e.g., a time slot) at which the UE is scheduled to send data to the base station, and then the UE may send the data via the first active beam at the scheduled time. Figure 6 In the context of, UE 604 can communicate with base station 602 via a first active beam (such as the fifth beam 620e).

[0228] In one aspect, operation 1302 may include operation 1320. At operation 1320, the UE may receive a reference signal from a base station. In one aspect, the reference signal may be a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS. Figure 6 In the context of, the UE 604 can receive the reference signal 644 from the base station 602 through the first active beam (e.g., the fifth beam 620e).

[0229] At operation 1304, the UE may receive a signal associated with beam tracking from the base station. In one aspect, the signal may be a reference signal. In another aspect, the signal may be a BRS. In another aspect, the signal may be a BRRS. In another aspect, the signal may be a message indicating that beam tracking is to be performed between the UE and the base station. Figure 6 In the context of , UE 604 may receive a signal associated with beam tracking from base station 602. The signal may be a BRS in BRS 612a-h, a BRRS in BRRS 614c-f, a message 642, a reference signal 644, or another signal.

[0230] In one aspect, operation 1304 may include operation 1322 and operation 1324. At operation 1322, the UE may detect a radio link failure based on reception of a reference signal (as described at operation 1320). For example, the UE may measure a signal quality (e.g., SINR, SNR, BRSRP, RSRP, RSRQ, or another signal quality) and compare the measured signal quality with a threshold. Based on the comparison result, the UE may determine that communication through the first active beam is failing or degraded. Figure 6In the context of , the UE 604 can detect a radio link failure associated with a first active beam (e.g., the fifth beam 620e) based on reception of the reference signal 644.

[0231] At operation 1324, the UE may send an indication of the detected radio link failure to the base station based on the detected radio link failure. For example, the UE may send a measured signal quality (e.g., SINR, SNR, BRSRP, RSRP, RSRQ, etc.) associated with a reference signal, a CQI, or a BAR, or another indication of the detected radio link failure to the base station. Figure 6 In the context of , UE 604 can send a response 646 to base station 602.

[0232] In one aspect, operation 1304 may include operation 1326. At operation 1326, the UE may send a beam index to the base station based on the BRS. For example, the UE may measure the signal quality of multiple BRSs and may determine the optimal (e.g., highest) signal quality corresponding to the optimal BRS. The UE may determine the beam index corresponding to the beam through which the optimal BRS is received, and may send the determined beam index to the base station. In one aspect, the beam index may be a coarse beam index. In Figure 6 In the context of , the UE 604 may send to the base station 602 a beam index corresponding to a beam in the beams 620a-h through which the best BRS in the BRS 612a-h is received. For example, the UE 604 may send a first indication 560 such as Figure 5A-5G Described in .

[0233] In one aspect, operation 1304 may include operation 1328. At operation 1328, the UE may send a beam index to the base station based on the BRRS. For example, the UE may measure the signal qualities of multiple BRRSs and may determine an optimal (e.g., highest) signal quality corresponding to an optimal BRRS. The UE may determine a beam index corresponding to the beam through which the optimal BRRS is received, and may send the determined beam index to the base station. In one aspect, the beam index may be a refined beam index. Figure 6 In the context of , UE 604 may send to base station 602 a beam index corresponding to a beam in beams 620c-f through which the best BRRS in BRRS 614c-f is received. For example, UE 604 may send a second indication 565 such as Figure 5A-5G Described in .

[0234] At operation 1306, the UE may perform beam tracking with the base station, for example, based on a signal associated with beam tracking. Fig.11AFor example, UE 604 may send a request 648 for beam tracking. Based on the beam tracking, the UE may determine a second beam corresponding to a second beam index for communication with the base station. Figure 6 In the context of, UE 604 can perform beam tracking with base station 602.

[0235] At operation 1308, the UE may communicate with the base station via the second active beam based on beam tracking. For example, the UE may send an indication of a beam index corresponding to the beam at the base station to the base station. The UE may select the second active beam for at least one of uplink or downlink communications with the UE. Figure 6 In the context of, UE 604 can communicate with base station 602 via a second active beam (e.g., the sixth beam 620f).

[0236] Fig.14 1400 is a flow chart of a method 1400 of wireless communication. The method 1400 may be performed by a base station (e.g., base station 702 and / or base station 802). In one aspect, the method 1400 may be performed by an apparatus. It will be appreciated by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0237] Beginning with operation 1402, a base station may communicate with a UE via a first active beam. In one aspect, the communication may be a downlink communication. For example, the base station may determine data to be sent to the UE, and then the base station may send the determined data via the first active beam. In one aspect, the communication may be an uplink communication. For example, the base station may determine a time (e.g., a time slot) at which the UE is scheduled to send data to the base station, and then the base station may receive the data via the first active beam at the scheduled time. Figure 7 In the context of , the base station 702 can communicate with the UE 704 via a first active beam (such as the fifth beam 720e). Figure 8 In the context of, base station 802 can communicate with UE 804 via active beam 820e.

[0238] At operation 1404, the base station may send information to the UE indicating a periodicity at which control information is to be transmitted on a control channel via a control information beam. For example, the base station may determine a periodicity at which the UE is to transmit control information to the base station (e.g., based on one or more standards released by 3GPP). The base station may generate a message indicating the periodicity and send the generated message to the UE, for example, via an active beam. Figure 7In the context of , the base station 702 may send information indicating the period to the UE 704 through the currently active beam (such as the fifth beam 720e). Figure 8 In the context of, the base station 802 can send information 842 indicating the period to the UE 804 via the active beam 820e.

[0239] In one aspect, the base station may send information indicating the period to the UE via RRC signaling. In another aspect, the base station may send information indicating the period to the UE on the PDCCH. For example, the base station may indicate the information in a DCI of the PDCCH (such as one or more bits of one or more DCI formats reserved for information indicating the period).

[0240] At operation 1406, the base station may adopt the period to transmit control information to the UE on the control channel via the control information beam. For example, the base station may receive (e.g., attempt to receive, detect, monitor, etc.) control information in each time period corresponding to the indicated period. The control information may include UCI, CQI, etc. The base station may determine the quality (e.g., channel quality) associated with the active beam based on the control information. Therefore, the base station may determine whether the active beam is satisfactory based on the control information. Alternatively, the base station may determine that the active beam is failing and / or unsatisfactory based on the control information, and the base station may determine to change the active beam. Figure 7 In the context of , when the fifth beam 720e is an active beam for communication between the base station 702 and the UE 704, the base station 702 can transmit control information with the UE 704 on the control channel through a beam among the beams 720a-h (such as the sixth beam 720f). Figure 8 In the context of , the base station 802 can transmit information 844 with the UE 804 on a control channel.

[0241] In one aspect, the base station may receive the control information via a control information beam, wherein the control information beam may be a beam corresponding to a beam index included in the set of candidate beam indices. Figure 8 In the context of, the base station 802 can transmit information 844 with the UE 804 on the control channel through the control information beam 820f, and the beam index corresponding to the control information beam 820f can be included in the candidate beam index set 830.

[0242] In another aspect, the base station may receive the control information via a control information beam, wherein the control information beam may be a wide beam having an angle greater than that of the active beam. Figure 8In the context of , base station 802 can transmit information 844 with UE 804 on a control channel via wide beam 822 (eg, wide beam 822 can serve as a control information beam).

[0243] In one aspect, operation 1406 may include operation 1420. In such an aspect, the control channel may be a PUCCH. At operation 1420, the base station may receive control information carried on the PUCCH from the UE via a control information beam. Figure 7 In the context of , when the fifth beam 720e is an active beam for communication between the base station 702 and the UE 704, the base station 702 can receive control information from the UE 704 on the PUCCH through a beam among the beams 720a-h (such as the sixth beam 720f). Figure 8 In the context of , the base station 802 can receive information 844 from the UE 804 on the PUCCH, for example, by controlling the information beam 820f and / or the wide beam 822.

[0244] At operation 1408, the base station may receive a request to change the active beam. The request may indicate a beam index corresponding to the second beam. In one aspect, the request may indicate the beam index by at least one of a cyclic offset and / or an extension across symbols. In one aspect, the request may indicate the beam index by at least one of a subcarrier region (e.g., an SR resource (e.g., a region) of a subframe) and / or a RACH (e.g., a RACH resource (e.g., a region) of a subframe).

[0245] exist Figure 7 In the context of , base station 702 may receive request 750 from UE 704, which may indicate a beam index corresponding to a beam in beams 720a-h. Figure 8 In the context of, the base station 802 may receive a request from the UE 804, which request may indicate a beam index corresponding to another beam different from the currently active beam 820e, for example, the request may indicate a beam index corresponding to the control information beam 820f, where the control information beam 820f may be a candidate beam corresponding to a beam index included in a candidate beam index set (e.g., the candidate beam index set 830).

[0246] At operation 1410, the base station may change the active beam to a second beam corresponding to the beam index indicated by the request. The base station may then communicate with the UE via the second beam (which may be the new active beam). Figure 7 In the context of , base station 702 may change the active beam to the beam in beams 720a-h that corresponds to the beam index indicated by the request. Figure 8In the context of, the base station 802 can change the active beam from the current active beam 820e to a second beam corresponding to the beam index indicated by the request, for example, the base station 802 can change the active beam to the control information beam 820f, where the control information beam 820f can be a candidate beam corresponding to a beam index included in a candidate beam index set (e.g., candidate beam index set 830).

[0247] Fig.15 1 is a flow chart of a method 1500 of wireless communication. The method 1500 may be performed by a UE (eg, UE 704 and / or UE 804). In one aspect, the method 1500 may be performed by an apparatus. It will be appreciated by those skilled in the art that one or more operations may be omitted, swapped, and / or performed simultaneously.

[0248] Beginning with operation 1502, a UE may communicate with a base station via a first active beam. In one aspect, the communication may be a downlink communication. For example, the UE may receive data from the base station. In one aspect, the communication may be an uplink communication. For example, the UE may determine a time (e.g., a time slot) at which the UE is scheduled to send data to the base station, and then the UE may send the data via the first active beam at the scheduled time. Figure 7 In the context of , UE 704 can communicate with base station 702 via a first active beam (such as fifth beam 720e). Figure 8 In the context of, UE 804 can communicate with base station 802 via active beam 820e.

[0249] At operation 1504, the UE may receive information from the base station indicating a period for transmitting control information on the control channel through a control information beam. For example, the UE may receive information from the base station indicating a period through an active beam. Figure 7 In the context of , UE 704 can obtain information indicating the period from base station 702 through the currently active beam (such as the fifth beam 720e). Figure 8 In the context of, the base station 802 can send information 842 indicating the period to the UE 804 via the active beam 820e.

[0250] In one aspect, the UE may receive information indicating the period to the UE via RRC signaling. In another aspect, the UE may receive information indicating the period on the PDCCH. For example, the information may be indicated via a DCI of the PDCCH (such as one or more bits of one or more DCI formats reserved for information indicating the period). Thus, the UE may determine the information based on the DCI of the PDCCH.

[0251] At operation 1506, the UE may adopt the period to transmit control information with the base station on the control channel via the control information beam. For example, the UE may send control information in each time period corresponding to the indicated period. In various aspects, the UE may measure signal quality or channel estimation associated with communication with the base station, for example, via an active beam. For example, the UE may measure the signal quality (e.g., SNR, SINR, received power, received quality, etc.) of a signal (e.g., BRS, CSI-RS, reference signal, etc.). The UE may generate a message for indicating the signal quality or channel estimation to the base station, and the UE may send the message to the base station. In various aspects, the information may include UCI, CQI, SR and / or other control information. In Figure 7 In the context of , when the fifth beam 720e is an active beam for communication between the base station 702 and the UE 704, the UE 704 can transmit control information on the control channel with the base station 702 through a beam among the beams 720a-h (such as the sixth beam 720f). Figure 8 In the context of , the base station 802 can transmit information 844 with the UE 804 on a control channel.

[0252] In one aspect, the UE may send control information via a control information beam, where the control information beam may be a beam corresponding to a beam index included in the set of candidate beam indices. Figure 8 In the context of, UE 804 may send information 844 to base station 802 on a control channel via a control information beam 820f, as well as a beam index corresponding to the control information beam 820f.

[0253] In another aspect, the UE may transmit control information via a control information beam, wherein the control information beam may be a wide beam having an angle greater than that of the active beam. Figure 8 In the context of , UE 804 can send information 844 to base station 802 on a control channel via wide beam 822 (eg, wide beam 822 can serve as a control information beam).

[0254] In one aspect, operation 1506 may include operation 1520. In such an aspect, the control channel may be a PUCCH. At operation 1520, the UE may send control information to the base station on the PUCCH via a control information beam. Figure 7 In the context of , when the fifth beam 720e is an active beam for communication between the base station 702 and the UE 704, the UE 704 can send control information to the base station 702 on the PUCCH through a beam among the beams 720a-h (such as the sixth beam 720f). Figure 8In the context of , the UE 804 can send information 844 to the base station 802 on the PUCCH, for example, by controlling the information beam 820f and / or the wide beam 822.

[0255] At operation 1508, the UE may send a request to the base station to change the active beam. The request may indicate a beam index corresponding to the second beam. For example, the UE may determine that the active beam is failing and / or unsatisfactory based on the measured signal quality (e.g., based on a comparison of the measured signal quality with a threshold). Therefore, the UE may request the base station to change the active beam because the current active beam is failing and / or unsatisfactory. In one aspect, the request indicates the beam index by at least one of a cyclic offset and / or an extension across symbols. In one aspect, the request indicates the beam index by at least one of a subcarrier region (e.g., an SR resource (e.g., region) of a subframe) and / or a RACH (e.g., a RACH resource (e.g., region) of a subframe).

[0256] exist Figure 7 In the context of , UE 704 may send a request 750 to base station 702, which may indicate a beam index corresponding to a beam in beams 720a-h. Figure 8 In the context of, UE 804 may send a request to base station 802, which may indicate a beam index corresponding to another beam different from the currently active beam 820e, for example, the request may indicate a beam index corresponding to control information beam 820f, where control information beam 820f may be a candidate beam corresponding to a beam index included in a candidate beam index set (e.g., candidate beam index set 830).

[0257] At operation 1510, the UE may change the active beam to a second beam corresponding to the beam index indicated by the request. The UE may then communicate with the base station via the second beam (which may be the new active beam). Figure 7 In the context of , UE 704 may change the active beam to a beam among beams 720a-h that corresponds to the beam index indicated by the request. Figure 8 In the context of, UE 804 can change the active beam from the current active beam 820e to a second beam corresponding to the beam index indicated by the request, for example, UE 804 can change the active beam to a control information beam 820f, where the control information beam 820f can be a candidate beam corresponding to a beam index included in a candidate beam index set (e.g., candidate beam index set 830).

[0258] Fig.161600 is a flow chart of a method of wireless communication. The method may be performed by a base station (eg, base station 902) communicating with a UE (eg, UE 904). Those skilled in the art will appreciate that one or more operations may be omitted, swapped, or performed simultaneously.

[0259] At operation 1602, the base station may determine one or more indexes associated with one or more beams. For example, the base station may receive a BSI from a UE, the BSI including one or more beam indexes corresponding to one or more beams of the base station. The base station may then identify a refined beam set based on the BSI received from the UE. Fig. 9A -E context, the base station 902 can determine one or more indexes corresponding to one or more beams 970, 972, 974.

[0260] At operation 1604, the base station may send one or more indications of one or more beam indices to the UE. In various aspects, the one or more indications may be carried on a control channel such as a PDCCH. For example, the one or more indications may be indicated via a DCI message of the PDCCH. Fig. 9A -E context, the base station 902 can send information 990 to the UE 904.

[0261] In one aspect, operation 1604 includes operations 1620 and 1622. At operation 1620, the base station may receive information from the UE indicating one or more indexes corresponding to the one or more beams. In one aspect, the one or more indexes may be received from the UE via a PUSCH or a PUCCH. In one aspect, the information indicating the one or more beam indexes may be one or more BSI reports. Fig. 9A -E context, the base station 902 may receive one or more indexes associated with one or more beams from the UE 904.

[0262] At operation 1622, the base station may send one or more indices based on one or more indices most recently received from the UE. In one aspect, when more than two symbols are reserved for reference signal transmission, the base station may send one or more indices based on one or more indices received from the UE via the PUSCH. In another aspect, if one or two symbols are reserved for reference signal transmission, the base station may send one or more indices based on one or more indices received from the UE via the PUCCH. Fig. 9A -E context, the base station 902 may send information 990 indicating one or more indexes to the UE 904 based on one or more indexes most recently received from the UE 904.

[0263] In one aspect, operation 1604 may include operation 1624. At operation 1624, the base station may transmit one or more indices associated with one or more beam reference signals (e.g., one or more BRSs). The one or more beam reference signals may be transmitted during a synchronization subframe. Fig. 9A -E context, the base station 902 may send one or more indexes associated with one or more beam reference signals, where the one or more beam reference signals may be used for coarse beam training with the UE 904.

[0264] In one aspect, operation 1604 may include operation 1628. At operation 1628, the base station may transmit one or more indices corresponding to one or more beams transmitted during a previous reference signal transmission (e.g., CSI-RS or BRRS transmission). Fig. 9A -E context, the base station 902 may send information 990 to the UE 904 indicating one or more beam indices associated with one or more beams sent during a previous reference signal transmission.

[0265] At operation 1606, the base station may send a reference signal to the UE based on one or more indices associated with the one or more beams (e.g., as determined at operation 1602). In various aspects, the reference signal may be a CSI-RS, a BRRS, an MRS, or another reference signal described herein. Fig. 9A In the context of -E, the base station 902 can send one or more reference signals to the UE 904 based on one or more indexes associated with one or more beams.

[0266] Fig.17 1700 is a conceptual data flow diagram 1700 illustrating data flows between different units / components in an exemplary apparatus 1702. The apparatus may be a base station (e.g., base station 602). The data flows illustrated in diagram 1700 are to be considered illustrative. Thus, according to various aspects, one or more additional units / components may be present, and one or more of the illustrated units / components may not be present. Furthermore, various data flows between units / components may occur in addition to and / or in lieu of the illustrated data flows.

[0267] Apparatus 1702 may include a receiving component 1704 configured to receive a signal from a UE (eg, UE 1750, mmW UE, etc.) Apparatus 1702 may also include a transmitting component 1710 configured to transmit a signal to a UE (eg, UE 1750, mmW UE, etc.).

[0268] The apparatus 1702 may include a communication component 1708. The communication component 1708 may be configured to determine a beam corresponding to a beam index. The communication component 1708 may provide an indication of the beam index to the receiving component 1704 so that the receiving component 1704 can receive data from the UE 1750 through the beam corresponding to the beam index. The communication component 1708 may provide an indication of the beam index to the transmitting component 1710 so that the transmitting component 1710 can transmit data to the UE 1750 through the beam corresponding to the beam index. The beam through which the apparatus 1702 communicates with the UE 1750 may be an active beam.

[0269] In one aspect, communication component 1708 may generate a reference signal. The reference signal may be a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS. Communication component 1708 may cause transmission component 1710 to transmit the reference signal to UE 1750 via a first active beam. In one aspect, communication component 1708 may cause the reference signal to be transmitted via a first RAT (e.g., a 5G RAT, a mmW RAT, and / or a near mmW RAT) having a first carrier frequency.

[0270] The apparatus 1702 may include a determining component 1712. The determining component 1712 may be configured to determine that beam tracking is to be performed with the UE 1750. Beam tracking may include selecting or identifying an active beam through which the apparatus 1702 is to communicate with the UE 1750. The determining component 1712 may provide an indication that beam tracking is to be performed to the beam tracking component 1706 so as to perform beam tracking.

[0271] In one aspect, determining component 1712 can be configured to determine a time for UE 1750 to transition from an inactive period of DRX to an active period of DRX. When UE 1750 transitions to an active period of DRX, determining component 1712 can determine to perform beam tracking. Determining component 1712 can indicate to beam tracking component 1706 that beam tracking is to be performed with UE 1750 at the time when UE 1750 transitions from an inactive period of DRX to an active period of DRX.

[0272] In one aspect, the determining component 1712 may be configured to determine to perform beam tracking with the UE 1750 based on a response to a reference signal received from the UE 1750. In one aspect, the response may be received via a second RAT, wherein the second RAT has a different carrier frequency than the first RAT, for example, the second RAT may have a lower carrier frequency than the first RAT, and the second RAT may be a sub-6 GHz RAT and / or an LTE RAT. In one aspect, the response may include at least one of a CQI, a SINR, a SNR, a RSSI, a BRSRP, a RSRP, or a RSRQ. Thus, the response may indicate the signal quality to the determining component 1712. The determining component 1712 may compare the signal quality with a threshold, and determine to perform beam tracking based on the comparison of the signal quality with the threshold.

[0273] In one aspect, determining component 1712 can detect radio link failure, for example, based on a response, an absence of a response, or at least one NACK message.Determining component 1712 can determine to perform beam tracking based on the detected radio link failure.

[0274] In one aspect, determining component 1712 can determine that there is no communication with UE 1750 via the currently active beam. Determining component 1712 can determine to perform beam tracking based on the absence of communication. For example, determining component 1712 can determine that there is no communication using the currently active beam based on the absence of data carried on PUCCH (e.g., when UE 1750 is scheduled to transmit uplink data on PUCCH), the absence of data carried on PUSCH (e.g., when UE 1750 is scheduled to transmit uplink data on PUSCH), and / or the absence of ACK / NACK messages from UE 1750 (e.g., in response to downlink data transmitted to UE 1750).

[0275] In one aspect, the beam tracking component 1706 can perform beam tracking with the UE 1750. Beam tracking allows the device 1702 to select or identify an active beam (e.g., a new beam) for communication with the UE 1750. In one aspect, the beam tracking component 1706 can cause the sending component 1710 to send one or more BRSs (e.g., a coarse beam set). The beam tracking component 1706 can receive a first indication of a first beam index through the receiving component 1704 based on one or more of the BRSs. The first beam index can be a coarse beam index. Based on the first beam index, the beam tracking component 1706 can select or identify a fine beam set through which to send one or more BRRSs, for example, for beam refinement. The beam tracking component 1706 can select or identify the fine beam set as one or more beams adjacent or close to the beam corresponding to the first beam index. Subsequently, the beam tracking component 1706 can send one or more BRRSs through the fine beam set. The beam tracking component 1706 can receive, via the receiving component 1704, a second indication of a second beam index based on one or more of the BRRS. The second beam index can be a fine beam index. Based on the second beam index, the beam tracking component 1706 can select or identify a fine beam through which the communication component 1708 is to communicate with the UE 1750. The beam tracking component 1706 can indicate the second beam index to the communication component 1708, where the second beam index can be a new active beam for communication (e.g., uplink and / or downlink communication) with the UE 1750.

[0276] In one aspect, beam tracking component 1706 may receive, via receiving component 1704, a request to perform beam tracking (e.g., a BAR) from UE 1750. Based on the request to perform beam tracking, beam tracking component 1706 may select or identify a set of fine beams through which to transmit one or more BRRS, e.g., for beam refinement. Beam tracking component 1706 may select or identify the set of fine beams as one or more beams that are adjacent or proximate to a beam used for communication with UE 1750 (e.g., the closest beam through which device 1702 communicates with UE 1750). Subsequently, beam tracking component 1706 may transmit one or more BRRS through the set of fine beams. Beam tracking component 1706 may receive, via receiving component 1704, an indication of a beam index based on one or more of the BRRS. The beam index may be a fine beam index. Based on the beam index, beam tracking component 1706 can select or identify a fine beam through which communication component 1708 is to communicate with UE 1750. Beam tracking component 1706 can indicate the beam index to communication component 1708, where the beam index can be a new active beam for communication with UE 1750 (e.g., uplink and / or downlink communication).

[0277] In one aspect, beam tracking component 1706 can indicate to UE 1750 that beam tracking is to be performed by generating a transmission of a message. For example, beam tracking component 1706 can generate a transmission of a message indicating that beam tracking is to be performed, and the message can be carried on a PDCCH or a PDSCH. In one aspect, the message can be sent via a DCI in a PDCCH.

[0278] The device 1702 may include executing the above Fig. 10A , 10B and / or each of the blocks of the algorithm in the flowchart of 12. In this way, the above-mentioned components can be performed by the components. Fig. 10A , 10B The process / algorithm and / or each block in the flowchart of 12, and the device 1702 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 for implementation by a processor, or some combination thereof.

[0279] Fig.181800 is a diagram illustrating an example of a hardware implementation of an apparatus 1702' employing a processing system 1814. The processing system 1814 may be implemented using a bus architecture, generally represented by a bus 1824. The bus 1824 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 1814. The bus 1824 links together various circuits including one or more processors and / or hardware components (represented by the processor 1804), components 1704, 1706, 1708, 1710, 1712, and computer readable media / memory 1806. The bus 1824 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are circuits well known in the art and will not be described further.

[0280] The processing system 1814 can be coupled to the transceiver 1810. The transceiver 1810 is coupled to one or more antennas 1820. The transceiver 1810 provides a unit for communicating with various other devices through a transmission medium. The transceiver 1810 receives signals from one or more antennas 1820, extracts information from the received signals, and provides the extracted information to the processing system 1814 (specifically the receiving component 1704). In addition, the transceiver 1810 receives information from the processing system 1814 (specifically the transmitting component 1710) and generates signals to be applied to one or more antennas 1820 based on the received information. The processing system 1814 includes a processor 1804 coupled to a computer-readable medium / memory 1806. The processor 1804 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 1806. When the processor 1804 executes the software, the software causes the processing system 1814 to perform the various functions described above for any particular device. The computer-readable medium / memory 1806 may also be used to store data that is manipulated by the processor 1804 when executing software. The processing system 1814 also includes at least one of the components 1704, 1706, 1708, 1710, 1712. The component may be a software component running in the processor 1804, resident / stored in the computer-readable medium / memory 1806, one or more hardware components coupled to the processor 1804, or some combination thereof. The processing system 1814 may be a component of the base station 310 and may include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375 and / or the memory 376.

[0281] In one configuration, the apparatus 1702 / 1702' for wireless communication includes: a unit for communicating with a UE via a first active beam. The apparatus 1702 / 1702' may also include: a unit for determining to perform beam tracking with the UE, wherein the beam tracking includes identifying a new beam for communication between the UE and the base station. The apparatus 1702 / 1702' may also include: a unit for performing beam tracking with the UE based on the determination to perform beam tracking. The apparatus 1702 / 1702' may also include: a unit for communicating with the UE via a second active beam based on the beam tracking.

[0282] In one aspect, the unit for determining to perform beam tracking for the UE is configured to: determine the time when the UE transitions from an inactive period of DRX to an active period of DRX, and the unit for performing beam tracking is configured to: perform beam tracking based on the determined time.

[0283] In one aspect, a unit for performing beam tracking is configured for one or more of: sending at least one beam reference signal; receiving a first indication of a first beam index from a UE based on the beam reference signal; sending at least one beam refinement reference signal based on the first indication of the first beam index; and receiving a second indication of a second beam index based on the at least one beam refinement reference signal, wherein the second beam index corresponds to a second active beam.

[0284] In one aspect, a unit for performing beam tracking is configured for one or more of: receiving a request for beam tracking from a UE; sending at least one beam refinement reference signal based on the request for beam tracking; and receiving an indication of a beam index based on the at least one beam refinement reference signal, wherein the beam index corresponds to a second active beam.

[0285] In one aspect, a unit for communicating with a UE via a first active beam is configured to: send a reference signal to the UE to determine whether the first active beam is failing, and a unit for determining to initiate beam tracking for the UE is configured to: receive a response from the UE based on the reference signal; and detect wireless link failure based on the received response.

[0286] In one aspect, communication with the UE via the first active beam is performed using a first RAT, and a response is received via a second RAT, wherein the second RAT has a lower carrier frequency than the first RAT. In one aspect, the reference signal is one of a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS, and the response includes at least one of a CQI, a SINR, a SNR, an RSSI, an RSRP, or an RSRQ.

[0287] In one aspect, the unit for performing beam tracking with the UE is configured to: send a message to the UE indicating that beam tracking is to be performed, and the message is sent on the PDCCH or PDSCH. In one aspect, the message is sent via DCI in the PDCCH.

[0288] In one aspect, the unit for determining to initiate beam tracking for the UE is configured to: determine that there is no communication with the UE via the first active beam. In one aspect, determining that there is no communication with the UE via the first active beam is based on the absence of data carried on the PUCCH, the absence of data carried on the PUSCH, or the absence of an ACK / NACK message from the UE.

[0289] The aforementioned means may be one or more of the aforementioned components of the apparatus 1702 and / or the processing system 1814 of the apparatus 1702' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1814 may include the TX processor 316, the RX processor 370, and the controller / processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0290] Fig.19 1 is a conceptual data flow diagram 1900 illustrating data flows between different units / components in an exemplary apparatus 1902. The apparatus may be a UE (e.g., UE 604). The data flows illustrated in diagram 1900 are to be considered illustrative. Thus, according to various aspects, one or more additional units / components may be present, and one or more of the illustrated units / components may not be present. Furthermore, in addition to the illustrated data flows, various data flows between units / components may occur.

[0291] Apparatus 1902 may include a receiving component 1904 configured to receive a signal from a base station (e.g., base station 1950, mmW base station, eNB, etc.) Apparatus 1902 may also include a transmitting component 1910 configured to transmit a signal to a base station (e.g., base station 1950, mmW base station, eNB, etc.).

[0292] In one aspect, the apparatus 1902 may include a communication component 1908. The communication component 1908 may be configured to determine beams corresponding to beam indices, which may be beams at the base station 1950 and corresponding beam indices. The communication component 1908 may provide an indication of the beam index to the receiving component 1904 so that the receiving component 1904 may receive data from the base station 1950 via the beam corresponding to the beam index. The communication component 1908 may provide an indication of the beam index to the transmitting component 1910 so that the transmitting component 1910 may transmit data to the base station 1950 via the beam corresponding to the beam index. The beams through which the apparatus 1902 communicates with the base station 1950 may be active beams.

[0293] In one aspect, the beam tracking component 1906 can perform beam tracking with the base station 1950. Beam tracking can allow the device 1902 to select or identify an active beam (e.g., a new beam) for communication with the base station 1950. In one aspect, the beam tracking component 1906 can receive one or more BRSs (e.g., a coarse beam set) through the receiving component 1904. The beam tracking component 1906 can measure the corresponding signal quality of the one or more received BRSs, and can select an optimal beam corresponding to the best (e.g., highest) signal quality of the received BRSs. The beam tracking component 1906 can send a first indication of a first beam index corresponding to the selected optimal beam through the sending component 1910. The first beam index can be a coarse beam index. Based on the first beam index, the beam tracking component 1906 can receive one or more BRRSs, for example, through the fine beam set. The beam tracking component 1906 can select a fine beam based on the one or more BRRSs (e.g., the beam tracking component can select the optimal beam based on the best or highest signal quality of the BRRS). Beam tracking component 1906 can transmit a second indication of a second beam index via transmitting component 1910, wherein the second beam index corresponds to the BRRS having the best or highest signal quality. The second beam index can be a refined beam index. Beam tracking component 1906 can indicate the second beam index to communicating component 1908, wherein the second beam index can be a new active beam for communications (e.g., uplink and / or downlink communications) with base station 1950.

[0294] In one aspect, beam tracking component 1906 may transmit a request to perform beam tracking (e.g., a BAR) via transmitting component 1910. Based on the request for beam tracking, beam tracking component 1906 may receive one or more BRRS, for example, via a fine beam set. Beam tracking component 1906 may select a fine beam based on one or more BRRS (e.g., beam tracking component may select an optimal beam based on an optimal or highest signal quality of the BRRS). Beam tracking component 1906 may transmit an indication of a beam index via transmitting component 1910, wherein the beam index corresponds to a BRRS with an optimal or highest signal quality. The beam index may be a fine beam index. Beam tracking component 1906 may indicate a second beam index to communication component 1908, wherein the second beam index may be a new active beam for communication (e.g., uplink and / or downlink communication) with base station 1950.

[0295] In one aspect, beam tracking component 1906 may receive a message (e.g., a signal) from base station 1950 indicating that beam tracking is to be performed. For example, beam tracking component 1906 may receive a message indicating that beam tracking is to be performed via receiving component 1904, and the message may be carried on a PDCCH or a PDSCH. In one aspect, the message may be received via a DCI in a PDCCH.

[0296] The apparatus 1902 may include a determining component 1912. The determining component 1912 may be configured to determine that beam tracking is to be performed with the base station 1950. Beam tracking may include selecting or identifying an active beam through which the apparatus 1902 is to communicate with the base station 1950. The determining component 1912 may provide an indication to the beam tracking component 1906 that beam tracking is to be performed so as to perform beam tracking.

[0297] In one aspect, determining component 1912 may be configured to receive, via receiving component 1904, a signal associated with beam tracking. In one aspect, the signal may be a BRS or a BRRS. In another aspect, the signal may be a reference signal. The reference signal may be one of a CSI-RS, a CRS, a SSS, an MRS, a DMRS, and the like.

[0298] In one aspect, determining component 1912 may be configured to cause transmitting component 1910 to transmit a response to a reference signal. In various aspects, the response may include one of CQI, SINR, SNR, RSSI, BRSRP, RSRP, or RSRQ. For example, determining component 1912 may measure signal quality (e.g., SINR, SNR, RSSI, BRSRP, RSRP, RSRQ, etc.) based on the reference signal. Determining component 1912 may generate a response including the measured signal quality.

[0299] In one aspect, determining component 1912 can receive the signal via a first RAT (e.g., a 5G RAT, mmW RAT, near mmWRAT, etc.) However, determining component 1912 can cause the response to be sent via a second RAT, wherein the second RAT has a different carrier frequency than the first RAT, e.g., the second RAT can have a lower carrier frequency than the first RAT, and the second RAT can be a Sub-6 GHz RAT and / or an LTE RAT.

[0300] In one aspect, determining component 1912 may detect a radio link failure based on a signal (e.g., a reference signal). For example, determining component 1912 may measure a signal quality of a reference signal. Determining component 1912 may compare the signal quality with a threshold and detect a radio link failure based on a comparison of the measured signal quality with the threshold. Determining component 1912 may determine to perform beam tracking based on the detected radio link failure. Determining component 1912 may cause transmitting component 1910 to transmit an indication of the detected radio link failure to base station 1950 and / or determining component 1912 may indicate to beam tracking component 1906 that beam tracking is to be performed, e.g., to recover an active beam for communication.

[0301] The device 1902 may include executing the above Fig.11A , 11B and / or each of the blocks of the algorithm in the flowchart of 13. In this way, the above-mentioned components can be performed by the components. Fig.11A , 11B Each block in the flowchart of 1 and / or 13, and the device 1902 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 for implementation by a processor, or some combination thereof.

[0302] Fig. 202000 is a diagram illustrating an example of a hardware implementation of an apparatus 1902' employing a processing system 2014. The processing system 2014 may be implemented using a bus architecture, generally represented by a bus 2024. The bus 2024 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 2014. The bus 2024 links together various circuits including one or more processors and / or hardware components (represented by the processor 2004), components 1904, 1906, 1908, 1910, 1912, and computer readable media / memory 2006. The bus 2024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are circuits well known in the art and will not be described further.

[0303] The processing system 2014 can be coupled to the transceiver 2010. The transceiver 2010 is coupled to one or more antennas 2020. The transceiver 2010 provides a unit for communicating with various other devices through a transmission medium. The transceiver 2010 receives signals from the one or more antennas 2020, extracts information from the received signals, and provides the extracted information to the processing system 2014 (specifically the receiving component 1904). In addition, the transceiver 2010 receives information from the processing system 2014 (specifically the transmitting component 1910), and generates signals to be applied to the one or more antennas 2020 based on the received information. The processing system 2014 includes a processor 2004 coupled to a computer-readable medium / memory 2006. The processor 2004 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 2006. When the processor 2004 executes the software, the software causes the processing system 2014 to perform various functions described above for any particular device. The computer-readable medium / memory 2006 may also be used to store data that is manipulated by the processor 2004 when executing software. The processing system 2014 also includes at least one of the components 1904, 1906, 1908, 1910, 1912. The component may be a software component running in the processor 2004, resident / stored in the computer-readable medium / memory 2006, one or more hardware components coupled to the processor 2004, or some combination thereof. The processing system 2014 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.

[0304] In one configuration, the apparatus 1902 / 1902' for wireless communication includes: means for communicating with a base station via a first active beam. The apparatus 1902 / 1902' may also include: means for receiving a signal associated with beam tracking from the base station, wherein the beam tracking includes identifying a new beam for communication between the apparatus 1902 / 1902' and the base station. The apparatus 1902 / 1902' may also include: means for communicating with the base station via a second active beam based on the signal associated with the beam tracking.

[0305] In one aspect, the signal includes a BRRS, and the apparatus 1902 / 1902' further includes: a unit for sending a beam index corresponding to a second active beam to a base station based on the BRRS. In one aspect, the signal includes a BRS, and the apparatus 1902 / 1902' further includes: a unit for sending a beam index corresponding to a coarse beam to a base station. In one aspect, the apparatus 1902 / 1902' may also include: a unit for sending a request to perform beam tracking to a base station based on the signal.

[0306] In one aspect, the means for communicating with the base station via the first active beam is configured to receive a reference signal, and the apparatus 1902 / 1902' further comprises: a means for detecting a radio link failure based on the received reference signal, and a means for sending an indication to the base station based on the detected radio link failure. In one aspect, the reference signal is one of a CSI-RS, a CRS, a SSS, an MRS, a DMRS, or a BRS, and the indication comprises at least one of a CQI, a SINR, a SNR, an RSSI, an RSRP, or an RSRQ. In one aspect, the means for communicating with the base station via the first active beam is performed using a first RAT, and the means for sending the indication is configured to send the indication via a second RAT, wherein the first RAT has a higher carrier frequency than the second RAT.

[0307] In one aspect, the apparatus 1902 / 1902' further comprises: a unit for performing beam tracking with a base station. In one aspect, the unit for performing beam tracking is configured for one or more of: receiving at least one BRS from the base station; sending a first indication of a first beam index to the base station based on the BRS; receiving at least one BRRS; and sending a second indication of a second beam index based on the at least one BRRS.

[0308] In one aspect, the signal is received on a PDCCH or a PDSCH. In one aspect, the signal is received via a DCI on a PDCCH.

[0309] The aforementioned means may be one or more of the aforementioned components of the apparatus 1902 and / or the processing system 2014 of the apparatus 1902' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2014 may include the TX processor 368, the RX processor 356, and the controller / processor 359. As such, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0310] Fig.21 21 is a conceptual data flow diagram 2100 illustrating data flows between different units / components in an exemplary apparatus 2102. The apparatus may be a base station (e.g., base station 702, base station 802, etc.). The data flows illustrated in diagram 2100 are to be considered illustrative. Thus, according to various aspects, one or more additional units / components may be present, and one or more of the illustrated units / components may not be present. Furthermore, various data flows between units / components may occur in addition to and / or in lieu of the illustrated data flows.

[0311] Apparatus 2102 may include a receiving component 2104 configured to receive a signal from a UE (eg, UE 2150, mmW UE, etc.) Apparatus 2102 may also include a transmitting component 2110 configured to transmit a signal to a UE (eg, UE 2150, mmW UE, etc.).

[0312] The apparatus 2102 may include a communication component 2108. The communication component 2108 may be configured to determine a beam corresponding to a beam index. The communication component 2108 may provide an indication of the beam index to the receiving component 2104 so that the receiving component 2104 can receive data from the UE 2150 through the beam corresponding to the beam index. The communication component 2108 may provide an indication of the beam index to the transmitting component 2110 so that the transmitting component 2110 can transmit data to the UE 2150 through the beam corresponding to the beam index. The beam through which the apparatus 2102 communicates with the UE 2150 may be an active beam.

[0313] In one aspect, the apparatus 2102 may include a control component 2112. The control component 2112 may be configured to determine a periodicity for transmitting control information on a control channel via a control information beam. In one aspect, the control component 2112 may cause the transmission component to send information indicating the periodicity to the UE. In one aspect, the control component 2112 may cause the information indicating the periodicity to be sent via RRC signaling. In another aspect, the control component 2112 may cause the information indicating the periodicity to be sent on a PDDCH. For example, the control component 2112 may cause the information indicating the periodicity to be sent as a DCI of the PDCCH.

[0314] In one aspect, the control component 2112 may employ the period to transmit control information with the UE on the control channel via a control information beam. The control information beam may be different from the active beam. In one aspect, the control information beam includes at least one candidate beam corresponding to a beam index included in the set of candidate beam indices. In one aspect, the control information beam includes at least one wide beam, which may have an angle greater than an angle of the active beam.

[0315] In one aspect, the control channel may include a PUCCH. The control component 2112 may be configured to receive, via the receiving component, control information carried on the PUCCH via a control information beam based on the period.

[0316] The apparatus 2102 may include a beam switching component 2106 for switching or changing an active beam. The beam switching component 2106 may receive a request to change the active beam through the receiving component 2104. The request may indicate a beam index corresponding to the second beam. For example, the request may indicate the beam index through at least one of a cyclic offset or an extension across symbols. In another example, the request may indicate the beam index through at least one of a subcarrier region or a RACH. The beam switching component 2106 may determine the second beam based on the request and provide the beam index to the communication component 2108 for communication through the new active beam.

[0317] The device may include performing the above Fig.14 Each block in the flowchart of the algorithm is an additional component. As such, the above can be performed by the component Fig.14 Each block in the flowchart of the process / algorithm may be included in the apparatus, 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 for implementation by a processor, or some combination thereof.

[0318] Fig. 22 2200 is a diagram illustrating an example of a hardware implementation of an apparatus 2102' employing a processing system 2214. The processing system 2214 may be implemented using a bus architecture, generally represented by a bus 2224. The bus 2224 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 2214. The bus 2224 links together various circuits including one or more processors and / or hardware components (represented by the processor 2204), components 2104, 2106, 2108, 2110, 2112, and computer readable media / memory 2206. The bus 2224 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are circuits well known in the art and will not be described further.

[0319] The processing system 2214 can be coupled to the transceiver 2210. The transceiver 2210 is coupled to one or more antennas 2220. The transceiver 2210 provides a unit for communicating with various other devices through a transmission medium. The transceiver 2210 receives signals from one or more antennas 2220, extracts information from the received signals, and provides the extracted information to the processing system 2214 (specifically the receiving component 2104). In addition, the transceiver 2210 receives information from the processing system 2214 (specifically the transmitting component 2110) and generates a signal to be applied to one or more antennas 2220 based on the received information. The processing system 2214 includes a processor 2204 coupled to a computer-readable medium / memory 2206. The processor 2204 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 2206. When the processor 2204 executes the software, the software causes the processing system 2214 to perform various functions described above for any particular device. The computer-readable medium / memory 2206 may also be used to store data that is manipulated by the processor 2204 when executing software. The processing system 2214 also includes at least one of the components 2104, 2106, 2108, 2110, 2112. The components may be software components running in the processor 2204, resident / stored in the computer-readable medium / memory 2206, one or more hardware components coupled to the processor 2204, or some combination thereof. The processing system 2214 may be a component of the base station 310 and may include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375 and / or the memory 376.

[0320] In one configuration, the apparatus 2102 / 2102' for wireless communication includes: a unit for communicating with a UE via an active beam. The apparatus 2102 / 2102' also includes: a unit for sending information to the UE, the information indicating a period for transmitting control information on a control channel via a control information beam. The apparatus 2102 / 2102' also includes: a unit for transmitting control information to the UE on the control channel via the control information beam using the period.

[0321] In one aspect, the control channel comprises a PUCCH, and the means for communicating control information with the UE on the control channel is configured to: based on the period, receive control information carried on the PUCCH from the UE via a control information beam.

[0322] In one aspect, the control information beam comprises at least one candidate beam corresponding to a beam index included in a set of candidate beam indices maintained by the base station. In one aspect, the control information beam comprises at least one wide beam having an angle greater than that of the active beam.

[0323] In one aspect, the information indicating the period is sent via RRC signaling. In one aspect, the information indicating the period is sent on a PDCCH. In one aspect, the information indicating the period includes a DCI of the PDCCH.

[0324] In one aspect, the apparatus 2102 / 2102' may further include: a unit for receiving a request to change the active beam, the request indicating a beam index corresponding to the second beam. In one aspect, the apparatus 2102 / 2102' may further include: a unit for changing the active beam to the second beam corresponding to the beam index indicated by the request. In one aspect, the request indicates the beam index by at least one of a cyclic offset or an extension across symbols. In one aspect, the request indicates the beam index by at least one of a subcarrier region or a RACH.

[0325] The aforementioned means may be one or more of the aforementioned components of the apparatus 2102 and / or the processing system 2214 of the apparatus 2102' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2214 may include the TX processor 316, the RX processor 370, and the controller / processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0326] Fig.232300 is a conceptual data flow diagram illustrating data flows between different units / components in an exemplary apparatus 2302. The apparatus may be a UE (e.g., UE 704, UE 804, etc.). The data flows illustrated in diagram 2300 are to be considered illustrative. Thus, according to various aspects, one or more additional units / components may be present, and one or more of the illustrated units / components may not be present. Furthermore, in addition to the illustrated data flows, various data flows between units / components may occur.

[0327] The apparatus 2302 may include a receiving component 2304 configured to receive a signal from a base station (e.g., base station 2350, mmW base station, eNB, etc.) The apparatus 2302 may also include a transmitting component 2310 configured to transmit a signal to a base station (e.g., base station 2350, mmW base station, eNB, etc.).

[0328] In one aspect, the apparatus 2302 may include a communication component 2308. The communication component 2308 may be configured to determine beams corresponding to beam indices, which may be beams at the base station 2350 and corresponding beam indices. The communication component 2308 may provide an indication of the beam index to the receiving component 2304 so that the receiving component 2304 may receive data from the base station 2350 via the beam corresponding to the beam index. The communication component 2308 may provide an indication of the beam index to the transmitting component 2310 so that the transmitting component 2310 may transmit data to the base station 2350 via the beam corresponding to the beam index. The beams through which the apparatus 2302 communicates with the base station 2350 may be active beams.

[0329] In one aspect, the apparatus 2302 may include a control component 2312. The control component 2312 may be configured to determine a period for transmitting control information on a control channel via a control information beam. In one aspect, the control component 2312 may receive information indicating a period from the base station 2350 sent by the sending component via the receiving component 2304. The control component 2312 may determine the period based on the information indicating the period. In one aspect, the control component 2312 may receive information indicating the period via RRC signaling. In another aspect, the control component 2312 may receive information indicating the period on a PDDCH. For example, the control component 2312 may receive information indicating the period as a DCI of a PDCCH.

[0330] In one aspect, the control component 2312 can use the period to transmit control information with the base station 2350 on the control channel via a control information beam. The control information beam can be different from the active beam. In one aspect, the control information beam includes at least one candidate beam corresponding to a beam index included in the set of candidate beam indices. In one aspect, the control information beam includes at least one wide beam, which can have an angle larger than that of the active beam.

[0331] In one aspect, the control channel may include a PUCCH.Control component 2312 may be configured to transmit control information to base station 2350 via a control information beam based on the period.

[0332] The apparatus 2302 may include a beam switching component 2306 for switching or changing an active beam. The beam switching component 2306 may send a request to change the active beam through the sending component 2310. The request may indicate a beam index corresponding to the second beam. For example, the request may indicate the beam index through at least one of a cyclic offset or an extension across symbols. In another example, the request may indicate the beam index through at least one of a subcarrier region or a RACH. The beam switching component 2306 may provide the beam index to the communication component 2308 for communication through the new active beam, wherein after sending the request, the new active beam may match the active beam at the base station 2350.

[0333] The device may include performing the above Fig.15 Each block in the flowchart of the algorithm is an additional component. As such, the above can be performed by the component Fig.15 Each block in the flowchart of the process / algorithm may be included in the apparatus, 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 for implementation by a processor, or some combination thereof.

[0334] Fig.242400 is a diagram illustrating an example of a hardware implementation of an apparatus 2302' employing a processing system 2414. The processing system 2414 may be implemented using a bus architecture, generally represented by a bus 2424. The bus 2424 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 2414. The bus 2424 links together various circuits including one or more processors and / or hardware components (represented by the processor 2404), components 2304, 2306, 2308, 2310, 2312, and computer readable media / memory 2406. The bus 2424 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are circuits well known in the art and will not be described further.

[0335] The processing system 2414 can be coupled to the transceiver 2410. The transceiver 2410 is coupled to one or more antennas 2420. The transceiver 2410 provides a unit for communicating with various other devices through a transmission medium. The transceiver 2410 receives signals from one or more antennas 2420, extracts information from the received signals, and provides the extracted information to the processing system 2414 (specifically the receiving component 2304). In addition, the transceiver 2410 receives information from the processing system 2414 (specifically the transmitting component 2310) and generates signals to be applied to one or more antennas 2420 based on the received information. The processing system 2414 includes a processor 2404 coupled to a computer-readable medium / memory 2406. The processor 2404 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 2406. When the processor 2404 executes the software, the software causes the processing system 2414 to perform various functions described above for any particular device. The computer-readable medium / memory 2406 may also be used to store data that is manipulated by the processor 2404 when executing software. The processing system 2414 also includes at least one of the components 2304, 2306, 2308, 2310, 2312. The component may be a software component running in the processor 2404, resident / stored in the computer-readable medium / memory 2406, one or more hardware components coupled to the processor 2404, or some combination thereof. The processing system 2414 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.

[0336] In one configuration, the apparatus 2302 / 2302' for wireless communication includes: a unit for communicating with a base station via an active beam. In one aspect, the apparatus 2302 / 2302' also includes: a unit for receiving information from the base station, the information indicating a periodicity for transmitting control information on a control channel via a control information beam. In one aspect, the apparatus 2302 / 2302' also includes: a unit for transmitting control information on a control channel with the base station via the control information beam using the periodicity.

[0337] In one aspect, the control channel comprises a PUCCH, and the means for transmitting the control information on the control channel is configured to send the control information on the PUCCH to the base station via a control information beam based on the period.

[0338] In one aspect, the control information beam includes at least one candidate beam, the at least one candidate beam corresponding to a beam index included in the set of candidate beam indices. In one aspect, the control information beam includes at least one wide beam, the at least one wide beam having an angle greater than an angle of an active beam. In one aspect, the information indicating the period is received using RRC signaling. In one aspect, the information indicating the period is received on a PDCCH. In one aspect, the information indicating the period is indicated by a DCI of the PDCCH.

[0339] In one aspect, the apparatus 2302 / 2302' further comprises: means for sending a request to the base station to change the active beam, the request indicating a beam index corresponding to the second beam. In one aspect, the apparatus 2302 / 2302' further comprises: means for changing the active beam to the second beam corresponding to the beam index indicated by the request. In one aspect, the request indicates the beam index by at least one of a cyclic offset or an extension across symbols. In one aspect, the request indicates the beam index by at least one of a subcarrier region or a RACH.

[0340] The aforementioned means may be one or more of the aforementioned components of the apparatus 2302 and / or the processing system 2414 of the apparatus 2302' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2414 may include the TX processor 368, the RX processor 356, and the controller / processor 359. As such, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0341] Fig.252500 is a conceptual data flow diagram illustrating data flows between different units / components in an exemplary apparatus 2502. The apparatus may be a base station (e.g., base station 902, etc.). The data flows illustrated in diagram 2500 are to be considered illustrative. Thus, according to various aspects, one or more additional units / components may be present, and one or more of the illustrated units / components may not be present. Furthermore, various data flows between units / components may occur in addition to and / or in lieu of the illustrated data flows.

[0342] Apparatus 2502 may include a receiving component 2504 configured to receive a signal from a UE (eg, UE 2550, mmW UE, etc.) Apparatus 2502 may also include a transmitting component 2510 configured to transmit a signal to a UE (eg, UE 2550, mmW UE, etc.).

[0343] In some aspects, the apparatus 2502 may include a determining component 2512. The determining component 2512 may be configured to determine one or more beam indices corresponding to one or more beams of the apparatus 2502 through which to transmit one or more reference signals. For example, the determining component 2512 may receive the one or more beam indices from the UE 2550 via the receiving component 2504. The beam index may be based on one or more reference signals previously transmitted by the apparatus 2502, such as one or more BRS, BRRS, CSI-RS, or another reference signal.

[0344] In one aspect, one or more beam indices are received from UE 2550 in one or more BSI reports. In one aspect, one or more beam indices corresponding to one or more beams are received on PUSCH or PUCCH. When more than two symbols are reserved for reference signal transmission, one or more beam indices corresponding to one or more beams may be received on PUSCH. When two or fewer symbols are reserved for reference signal transmission, one or more beam indices corresponding to one or more beams may be received on PUCCH.

[0345] In one aspect, determining component 2512 may determine one or more beam indices based on one or more beam indices most recently received from UE 2550. In one aspect, determining component 2512 may determine one or more beam indices based on transmitting one or more BRSs during a synchronization subframe. Determining component 2512 may reuse a beam on which one or more BRSs are transmitted, e.g., based on feedback from UE 2550 indicating an optimal beam index corresponding to an optimal beam (e.g., a beam through which an associated BRS is transmitted and the BRS has the highest measured signal quality).

[0346] The determining component 2512 may provide an indication of one or more beam indices corresponding to the one or more beams to the indicating component 2506. The indicating component 2506 may be configured to generate one or more indications of one or more beam indices corresponding to the one or more beams. Subsequently, the indicating component 2506 may cause the sending component 2510 to send the one or more indications to the UE 2550. In one aspect, the one or more indications may be carried on the PDCCH. For example, the one or more indications may be included in one or more bits of a DCI message of the PDCCH.

[0347] The determining component 2512 may provide an indication of one or more beam indexes corresponding to the one or more beams to the reference signal component 2508. The reference signal component 2508 may be configured to generate one or more reference signals. The generated reference signal may be at least one of a BRRS or a CSI-RS. Subsequently, the reference signal component 2508 may cause the transmitting component 2510 to transmit the one or more reference signals via one or more beams corresponding to the one or more beam indexes, wherein the one or more beam indexes are transmitted to the UE 2550 by the indicating component 2506.

[0348] The device may include performing the above Fig.16 Each block in the flowchart of the algorithm is an additional component. As such, the above can be performed by the component Fig.16 Each block in the flowchart of the process / algorithm may be included in the apparatus, 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 for implementation by a processor, or some combination thereof.

[0349] Fig.26 2600 is a diagram illustrating an example of a hardware implementation of an apparatus 2502' employing a processing system 2614. The processing system 2614 may be implemented using a bus architecture, generally represented by a bus 2624. The bus 2624 may include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the processing system 2614. The bus 2624 links together various circuits including one or more processors and / or hardware components (represented by the processor 2604), components 2504, 2506, 2508, 2510, 2512, and computer readable media / memory 2606. The bus 2624 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are circuits well known in the art and will not be described further.

[0350] The processing system 2614 can be coupled to the transceiver 2610. The transceiver 2610 is coupled to one or more antennas 2620. The transceiver 2610 provides a unit for communicating with various other devices through a transmission medium. The transceiver 2610 receives signals from one or more antennas 2620, extracts information from the received signals, and provides the extracted information to the processing system 2614 (specifically the receiving component 2504). In addition, the transceiver 2610 receives information from the processing system 2614 (specifically the transmitting component 2510) and generates signals to be applied to one or more antennas 2620 based on the received information. The processing system 2614 includes a processor 2604 coupled to a computer-readable medium / memory 2606. The processor 2604 is responsible for general processing, including the execution of software stored on the computer-readable medium / memory 2606. When the processor 2604 executes the software, the software causes the processing system 2614 to perform various functions described above for any particular device. The computer-readable medium / memory 2606 may also be used to store data that is manipulated by the processor 2604 when executing software. The processing system 2614 also includes at least one of the components 2504, 2506, 2508, 2510, 2512. The component may be a software component running in the processor 2604, resident / stored in the computer-readable medium / memory 2606, one or more hardware components coupled to the processor 2604, or some combination thereof. The processing system 2614 may be a component of the base station 310 and may include at least one of the TX processor 316, the RX processor 370, and the controller / processor 375 and / or the memory 376.

[0351] In one configuration, the apparatus 2502 / 2502' for wireless communication includes: a unit for sending one or more indications of one or more beam indices corresponding to one or more beams to the UE on a control channel. The apparatus 2502 / 2502' may also include: a unit for sending one or more reference signals to the UE via one or more beams corresponding to the one or more beam indices. In one aspect, the control channel includes a PDCCH, and the one or more indications are included in one or more bits of a DCI message.

[0352] In one aspect, the means for transmitting one or more indications of one or more beam indices corresponding to one or more beams is configured to transmit the one or more beams associated with one or more BRSs transmitted during a synchronization subframe.

[0353] In one aspect, a unit for sending one or more indications of one or more beam indices corresponding to one or more beams is configured to: receive one or more beam indices corresponding to one or more beams from a UE; and send one or more beam indices corresponding to one or more beams based on the most recently received one or more beam indices.

[0354] In one aspect, one or more beam indices corresponding to one or more beams are received on a PUSCH or PUCCH. In one aspect, when more than two symbols are used for reference signal transmission, one or more beam indices corresponding to one or more beams are sent based on one or more beam indices received via a PUSCH. In one aspect, when two or fewer symbols are used for reference signal transmission, one or more beam indices associated with one or more beams are sent based on one or more beam indices received via a PUCCH.

[0355] In one aspect, the one or more reference signals include at least one of a CSI-RS or a BRRS. In one aspect, the means for transmitting one or more indications of one or more beam indices associated with one or more beams is configured to: transmit the one or more beam indices associated with the one or more beams, wherein at least one of the CSI-RS was previously transmitted via the one or more beams.

[0356] The aforementioned means may be one or more of the aforementioned components of the apparatus 2502 and / or the processing system 2614 of the apparatus 2502' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2614 may include the TX processor 316, the RX processor 370, and the controller / processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0357] It should be understood that the specific order or hierarchy of the frames in the disclosed process / flowchart is only an explanation of the exemplary method. It should be understood that the specific order or hierarchy of the frames in the process / flowchart can be rearranged based on design preferences. In addition, some frames can be merged or omitted. The attached method claims provide the elements of each frame in a sample order, but are not meant to be limited to the specific order or hierarchy provided.

[0358] The foregoing description is provided so that any person skilled in the art can implement 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 aspects shown herein, but to conform to the full range consistent with the content expressed by the claims, wherein, unless explicitly stated so, the elements mentioned in the singular form are not intended to mean "one and only one", but "one or more". The word "exemplary" used herein means "as an example, instance or illustration". Any aspect described as "exemplary" herein need not be 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 or several members of A, B, or C. All structural and functional equivalents of the elements throughout the various aspects described in the present disclosure, which are known or later become known to a person of ordinary skill in the art, are expressly incorporated herein by reference and are intended to be included by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The words "module," "mechanism," "element," "device," and the like may not be substitutes for the word "unit." Thus, no claim element is to be interpreted as a functional unit unless the element is explicitly stated using the phrase "unit for..."

Claims

1. A method for wireless communication of a user equipment (UE), the method comprising: sending a request to a base station in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the base station to determine a communication beam, wherein the performing the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

2. The method according to claim 1, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

3. The method according to claim 1, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

4. The method according to claim 1, wherein: The request indicates a beam index associated with the at least one first beam.

5. The method according to claim 4, wherein: The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

6. The method according to claim 1, wherein: At least one second reference signal of the plurality of reference signals is received on at least one second beam of the plurality of beams based on a first indication of the at least one first beam index.

7. The method according to claim 1, further comprising: detecting, in the second carrier frequency, a radio link failure associated with communications with the base station on a serving beam, Wherein, sending the request is based on the failure of the wireless link.

8. The method according to claim 7, wherein: The detecting the wireless link failure comprises: measuring a value associated with the serving beam, wherein the value comprises at least one of: a signal-to-noise ratio (SNR), a signal-to-interference-plus-noise ratio (SINR), a received signal strength indicator (RSSI), a reference signal received quality, or a reference signal received power (RSRP); comparing the value to a threshold; and The radio link failure is detected based on comparing the value to the threshold.

9. A method for wireless communication of a base station, the method comprising: receiving a request from a user equipment (UE) in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the UE to determine a communication beam, wherein the performing the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicate with the UE on the communication beam in the second carrier frequency.

10. The method according to claim 9, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

11. The method according to claim 9, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

12. The method according to claim 9, wherein: The request indicates a beam index associated with the at least one first beam.

13. The method according to claim 12, wherein: The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

14. The method according to claim 9, wherein: At least one second reference signal among the plurality of reference signals is sent on at least one second beam among the plurality of beams based on a first indication of the at least one first beam index.

15. The method according to claim 9, wherein: The request is based on a failure of a radio link between the base station and the UE on a serving beam.

16. A method for wireless communication of a user equipment (UE), the method comprising: receiving a message from a base station in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instruction, performing the beam tracking with the base station to determine the communication beam, wherein the performing the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

17. The method according to claim 16, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

18. The method according to claim 16, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

19. The method according to claim 16, wherein: At least one second reference signal of the plurality of reference signals is received on at least one second beam of the plurality of beams based on a first indication of the at least one first beam index.

20. A method for wireless communication of a base station, the method comprising: sending a message to a user equipment (UE) in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instruction, performing the beam tracking with the UE to determine a communication beam, wherein the performing the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicate with the UE on the communication beam in the second carrier frequency.

21. The method according to claim 20, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

22. The method according to claim 20, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

23. The method according to claim 20, wherein: At least one second reference signal among the plurality of reference signals is sent on at least one second beam among the plurality of beams based on a first indication of the at least one first beam index.

24. An apparatus for wireless communication included in a user equipment (UE), the apparatus comprising: means for sending a request to a base station in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; and means for performing the beam tracking with the base station to determine a communication beam based on the request, wherein the means for performing the beam tracking is configured to: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Means for communicating with the base station on the communication beam in the second carrier frequency based on the beam tracking.

25. The device according to claim 24, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

26. The device according to claim 24, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

27. The device according to claim 24, wherein: The request indicates a beam index associated with the at least one first beam.

28. The device according to claim 27, wherein The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

29. The device according to claim 24, wherein: At least one second reference signal of the plurality of reference signals is received on at least one second beam of the plurality of beams based on a first indication of the at least one first beam index.

30. The apparatus of claim 24, further comprising: means for detecting, in the second carrier frequency, a radio link failure associated with communications with the base station on a serving beam, The unit for sending the request is configured to send the request based on the failure of the radio link.

31. The device according to claim 30, wherein The unit for detecting the failure of the radio link is configured to: measuring a value associated with the serving beam, wherein the value comprises at least one of: a signal-to-noise ratio (SNR), a signal-to-interference-plus-noise ratio (SINR), a received signal strength indicator (RSSI), a reference signal received quality, or a reference signal received power (RSRP); comparing the value to a threshold; and The radio link failure is detected based on comparing the value to the threshold.

32. An apparatus for wireless communication included in a base station, the apparatus comprising: means for receiving a request from a user equipment (UE) in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; and means for performing the beam tracking with the UE to determine a communication beam based on the request, wherein the means for performing the beam tracking is configured to: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Unit for communicating with the UE on the communication beam in the second carrier frequency based on the beam tracking.

33. The device according to claim 32, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

34. The device according to claim 32, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

35. The device according to claim 32, wherein: The request indicates a beam index associated with the at least one first beam.

36. The device according to claim 35, wherein The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

37. The device according to claim 32, wherein: At least one second reference signal among the plurality of reference signals is sent on at least one second beam among the plurality of beams based on a first indication of the at least one first beam index.

38. The apparatus of claim 32, wherein: The request is based on a failure of a radio link between the base station and the UE on a serving beam.

39. An apparatus for wireless communication included in a user equipment (UE), the apparatus comprising: means for receiving a message from a base station in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; and means for performing the beam tracking with the base station to determine a communication beam based on the instructions, wherein the means for performing the beam tracking is configured to: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Means for communicating with the base station on the communication beam in the second carrier frequency based on the beam tracking.

40. The device according to claim 39, wherein The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

41. The apparatus of claim 39, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

42. The apparatus of claim 39, wherein: At least one second reference signal of the plurality of reference signals is received on at least one second beam of the plurality of beams based on a first indication of the at least one first beam index.

43. An apparatus for wireless communication included in a base station, the apparatus comprising: means for sending a message to a user equipment (UE) in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; and means for performing the beam tracking with the UE to determine a communication beam based on the instruction, wherein the means for performing the beam tracking is configured to: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Unit for communicating with the UE on the communication beam in the second carrier frequency based on the beam tracking.

44. The device according to claim 43, wherein The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

45. The apparatus of claim 43, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

46. ​​The apparatus of claim 43, wherein: At least one second reference signal among the plurality of reference signals is sent on at least one second beam among the plurality of beams based on a first indication of the at least one first beam index.

47. An apparatus for wireless communication included in a user equipment (UE), the apparatus comprising: Memory; as well as at least one processor coupled to the memory and configured to: sending a request to a base station in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the base station to determine a communication beam, wherein the performing the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on multiple measurements associated with receiving the multiple reference signals, in the second carrier frequency, information indicating at least one first beam index corresponding to at least one first beam among the multiple beams is sent to the base station, wherein each of the multiple measurements is associated with a corresponding beam among the multiple beams; and based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

48. The apparatus of claim 47, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

49. The apparatus of claim 47, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

50. The apparatus of claim 47, wherein: The request indicates a beam index associated with the at least one first beam.

51. The apparatus of claim 50, wherein: The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

52. The apparatus of claim 47, wherein: The at least one processor is further configured to: detecting, in the second carrier frequency, a radio link failure associated with communications with the base station on a serving beam, The request is sent based on the failure of the wireless link.

53. The apparatus of claim 52, wherein: The detecting the wireless link failure comprises: measuring a value associated with the serving beam, wherein the value comprises at least one of: a signal-to-noise ratio (SNR), a signal-to-interference-plus-noise ratio (SINR), a received signal strength indicator (RSSI), a reference signal received quality, or a reference signal received power (RSRP); comparing the value to a threshold; and The radio link failure is detected based on comparing the value to the threshold.

54. An apparatus for wireless communication included in a base station, the apparatus comprising: Memory; as well as at least one processor coupled to the memory and configured to: receiving a request from a user equipment (UE) in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the UE to determine a communication beam, wherein the performing the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and Based on multiple measurements associated with receiving the multiple reference signals by the UE, in the second carrier frequency, information indicating at least one first beam index corresponding to at least one first beam among the multiple beams is received from the UE, wherein each of the multiple measurements is associated with a corresponding beam among the multiple beams; and based on the beam tracking, communicating with the UE on the communication beam in the second carrier frequency.

55. The apparatus of claim 54, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

56. The apparatus of claim 54, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

57. The apparatus of claim 54, wherein: The request indicates a beam index associated with the at least one first beam.

58. The apparatus of claim 57, wherein: The request indicates the beam index associated with the at least one first beam based on one or more resources associated with a random access channel (RACH).

59. The apparatus of claim 54, wherein: The request is based on a failure of a radio link between the base station and the UE on a serving beam.

60. An apparatus for wireless communication included in a user equipment (UE), the apparatus comprising: Memory; as well as at least one processor coupled to the memory and configured to: receiving a message from a base station in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instruction, performing the beam tracking with the base station to determine the communication beam, wherein the performing the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

61. The apparatus of claim 60, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

62. The apparatus of claim 60, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

63. An apparatus for wireless communication included in a base station, the apparatus comprising: Memory; as well as at least one processor coupled to the memory and configured to: sending a message to a user equipment (UE) in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instruction, performing the beam tracking with the UE to determine a communication beam, wherein the performing the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicate with the UE on the communication beam in the second carrier frequency.

64. The apparatus of claim 63, wherein: The first carrier frequency comprises a sub-6 gigahertz (GHz) frequency band, and the second carrier frequency comprises a millimeter wave (mmW) frequency band.

65. The apparatus of claim 63, wherein: The first carrier frequency is associated with a first radio access technology (RAT), and the second carrier frequency is associated with a second RAT different from the first RAT.

66. A non-transitory computer-readable medium storing computer-executable code for wireless communication by a user equipment (UE), comprising code for: sending a request to a base station in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the base station to determine a communication beam, wherein, The performing of the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

67. A non-transitory computer-readable medium storing computer-executable code for wireless communication by a base station, comprising code for: receiving a request from a user equipment (UE) in a first carrier frequency, the request associated with performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the request, performing the beam tracking with the UE to determine a communication beam, wherein: The performing of the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicate with the UE on the communication beam in the second carrier frequency.

68. A non-transitory computer-readable medium storing computer-executable code for wireless communication by a user equipment (UE), comprising code for: receiving a message from a base station in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instructions, the beam tracking is performed with the base station to determine a communication beam, wherein, The performing of the beam tracking comprises: receiving a plurality of reference signals from the base station, wherein each reference signal of the plurality of reference signals is received via a corresponding beam of a plurality of beams, and Based on a plurality of measurements associated with receiving the plurality of reference signals, transmitting, in the second carrier frequency, to the base station information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicating with the base station on the communication beam in the second carrier frequency.

69. A non-transitory computer-readable medium storing computer-executable code for wireless communication by a base station, comprising code for: sending a message to a user equipment (UE) in a first carrier frequency, the message indicating instructions for performing beam tracking between the base station and the UE in a second carrier frequency different from the first carrier frequency; Based on the instruction, the beam tracking is performed with the UE to determine a communication beam, wherein: The performing of the beam tracking comprises: transmitting a plurality of reference signals, wherein each reference signal of the plurality of reference signals is transmitted via a corresponding beam of a plurality of beams, and receiving, in the second carrier frequency, from the UE information indicating at least one first beam index corresponding to at least one first beam of the plurality of beams based on a plurality of measurements associated with receiving the plurality of reference signals by the UE, wherein each measurement of the plurality of measurements is associated with a corresponding beam of the plurality of beams; and Based on the beam tracking, communicate with the UE on the communication beam in the second carrier frequency.

Images