CN114175524A

CN114175524A - Minimizing block error rate (BLER) associated with beam switching

Info

Publication number: CN114175524A
Application number: CN202080054215.5A
Authority: CN
Inventors: R·柏林纳; S·兰迪斯; I·古特曼; G·S·库兹
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2019-07-31
Filing date: 2020-06-26
Publication date: 2022-03-11
Also published as: EP4005106A1; WO2021021352A1; CN114175712A; WO2021021295A1; EP4005108A1

Abstract

Aspects of the present disclosure relate to minimizing a block error rate (BLER) experienced by a User Equipment (UE) at downlink beam switching at a base station. The base station may mitigate link adaptation convergence transients by modifying a Modulation and Coding Scheme (MCS) according to a Reference Signal Received Power (RSRP) difference between the old and new beams upon performing the beam switch. The base station may further adjust the MCS after the beam switch using an outer loop link adaptation procedure or Channel State Feedback (CSF) provided by the UE. Other aspects, features and embodiments are also claimed and described.

Description

Minimizing block error rate (BLER) associated with beam switching

According to 35U.S.C. § 119-

This application claims priority and benefit from U.S. non-provisional application No.16/528,451 (attorney docket No. 192282), filed on 31/7/2019, as fully set forth below and incorporated herein for all applicable purposes.

This application also claims priority and benefit from and is a continuation of co-pending U.S. application No.16/528,457(QC docket No. 192347), filed 2019, 31, 7/month, and which is incorporated herein by reference as if fully set forth below and for all applicable purposes.

Technical Field

The techniques discussed below relate generally to wireless communication networks and, more particularly, to adjusting transmit and receive characteristics associated with beam switching (e.g., after beam switching) in a beam-based communication scenario (e.g., millimeter wave beam). Some embodiments and techniques enable and provide communications devices, methods, and systems with techniques for minimizing a block error rate (sometimes abbreviated BLER) associated with performing beam switching (e.g., before, during, or after beam switching).

Introduction to the design reside in

In wireless communication systems, such as those specified under the standards for 5G New Radios (NR), base stations and User Equipment (UE) may utilize beamforming to compensate for high pathloss and short range. Beamforming is a signal processing technique used with antenna arrays for directional signal transmission and/or reception. Each antenna in an antenna array transmits a signal that is combined with other signals of other antennas in the same array in such a way that signals at a particular angle undergo constructive interference while other signals undergo destructive interference.

As the demand for mobile broadband access continues to increase, research and development continues to advance beamforming communication technologies (including, inter alia, techniques for enhanced beamforming management) in order to not only meet the increasing demand for mobile broadband access, but also to enhance and enhance the user experience with mobile communications.

Brief summary of some examples

The following presents a simplified summary of one or more aspects of the disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended to neither identify key or critical elements of all aspects of the disclosure, nor delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a form as a prelude to the more detailed description that is presented later.

Various aspects of the present disclosure relate to minimizing a block error rate (BLER) experienced by a User Equipment (UE) in a beam-based communication scenario. BLER may be minimized upon downlink beam switching at the base station. As one example, the base station may mitigate link adaptation convergence transient problems by modifying the Modulation and Coding Scheme (MCS) upon performing beam switching. The modification may be made according to differences in Reference Signal Received Power (RSRP) measurements for various beams (e.g., between an existing or old beam and a new or intended beam). MCS modification may occur shortly after beam switching to minimize BLER at the UE (e.g., in the first slot after beam switching). In some examples, the base station may further adjust the MCS with an outer loop link adaptation procedure or Channel State Feedback (CSF) provided by the UE after the beam switch. The disclosed aspects include various method, system, device, and apparatus embodiments.

In one example, a method for wireless communication at a base station in a wireless communication network is disclosed. The method can comprise the following steps: communicate with a User Equipment (UE) using a first downlink beam of a plurality of downlink beams; and switching from the first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. The switching may occur based on a difference in measured or observed power reference signal levels (e.g., a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam). The method may further comprise: modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on a difference between the first RSRP and the second RSRP.

Another example provides a base station in a wireless communication network, comprising a wireless transceiver, a memory, and a processor communicatively coupled to the wireless transceiver and the memory. The processor may be configured to: communicate with a User Equipment (UE) using a first downlink beam of a plurality of downlink beams; and switching from the first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. The switching may occur based on a difference in measured or observed power reference signal levels (e.g., a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam). The processor may be further configured to: a Modulation and Coding Scheme (MCS) for communicating with the UE is modified based on a difference between the first RSRP and the second RSRP.

Another example provides a base station in a wireless communication network. The base station may include: means for communicating with a User Equipment (UE) utilizing a first downlink beam of a plurality of downlink beams; and means for switching from a first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. The switching may occur based on a difference in measured or observed power reference signal levels (e.g., a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam). The base station may further include: means for modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on a difference between the first RSRP and the second RSRP.

Another example provides a non-transitory computer-readable medium comprising code for causing a base station to: communicate with a User Equipment (UE) using a first downlink beam of a plurality of downlink beams; and switching from the first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. The switching may occur based on a difference in measured or observed power reference signal levels (e.g., a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam). The non-transitory computer-readable medium may also include code for causing the base station to: a Modulation and Coding Scheme (MCS) for communicating with the UE is modified based on a difference between the first RSRP and the second RSRP.

Various method, system, device, and apparatus embodiments may also include additional features. For example, the first downlink beam and the second downlink beam may have the same or different widths. Further, the base station may communicate with the UE using a millimeter wave carrier frequency.

In some examples, the base station may be further configured to receive at least one beam measurement report from the UE, wherein the first RSRP and the second RSRP are each included in one of the at least one beam measurement report. The base station may be further configured to calculate a difference between the first RSRP and the second RSRP based on the beam measurement report. In another example, the base station may be further configured to estimate a difference between the first RSRP and the second RSRP based on respective signal quality measurements of a first uplink beam corresponding to the first downlink beam and a second uplink beam corresponding to the second downlink beam.

In some examples, the base station may be configured to adjust the MCS using an outer loop link adaptation procedure. For example, the base station may be configured to receive acknowledgement information from the UE; and adjusting the MCS based on the acknowledgement information. In another example, the base station may be configured to transmit a channel state information-reference signal (CSI-RS) to the UE via a second beam; receiving Channel State Feedback (CSF) from the UE; and adjusting the MCS based on the CSF.

These and other aspects will be more fully understood after a review of the following detailed description. Other aspects, features and embodiments will become apparent to those ordinarily skilled in the art upon review of the following description of specific exemplary embodiments in conjunction with the accompanying figures. While various features may be discussed below with respect to certain embodiments and figures, all embodiments can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more such features may also be used in accordance with the various embodiments discussed herein. In a similar manner, although exemplary embodiments may be discussed below as device, system, or method embodiments, such exemplary embodiments may be implemented in various devices, systems, and methods.

Brief Description of Drawings

Fig. 1 is a schematic illustration of a wireless communication system, according to some aspects.

Fig. 2 is a conceptual illustration of an example of a radio access network according to some aspects.

Fig. 3 is a diagram illustrating an example of a frame structure for use in a radio access network, in accordance with some aspects.

Fig. 4 is a block diagram illustrating a wireless communication system supporting beamforming and/or multiple-input multiple-output (MIMO) communication, in accordance with some aspects.

Fig. 5 is a diagram illustrating an example of communication between a base station and a User Equipment (UE) using beamforming, according to some aspects.

Fig. 6 is a block diagram illustrating exemplary components of a UE in accordance with some aspects.

Fig. 7 is a signaling diagram illustrating example signaling for minimizing BLER based on an expected beam switch, in accordance with some aspects.

Fig. 8 is a block diagram illustrating an example of a hardware implementation of a UE employing a processing system in accordance with some aspects.

Fig. 9 is a flow diagram of an example method for a UE to minimize BLER associated with an expected beam switch, in accordance with some aspects.

Fig. 10 is a flow diagram of another example method for a UE to minimize BLER associated with an expected beam switch, in accordance with some aspects.

Fig. 11 illustrates example signaling between a UE and a base station to minimize BLER based on beam switching, in accordance with some aspects.

Fig. 12 is a block diagram illustrating an example of a hardware implementation of a base station employing a processing system, in accordance with some aspects.

Fig. 13 is a flow diagram of an example method for a base station to minimize BLER associated with beam switching, in accordance with some aspects.

Fig. 14 is a flow diagram of another example method for a base station to minimize BLER associated with beam switching, in accordance with some aspects.

Fig. 15 is a flow diagram of another example method for a base station to minimize BLER associated with beam switching, in accordance with some aspects.

Fig. 16 is a flow diagram of another example method for a base station to minimize BLER associated with beam switching, in accordance with some aspects.

Fig. 17 is a flow diagram of another example method for a base station to minimize BLER associated with beam switching, in accordance with some aspects.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Although aspects and embodiments are described herein by way of illustration of some examples, those skilled in the art will appreciate that additional implementations and use cases may be generated in many different arrangements and scenarios. The innovations described herein may be implemented across many different platform types, devices, systems, shapes, sizes, packaging arrangements. For example, embodiments and/or uses can be generated via integrated chip embodiments and other non-module component-based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/shopping devices, medical devices, AI-enabled devices, etc.). While some examples may or may not be specific to each use case or application, broad applicability of the described innovations may occur. Implementations may range from chip-level or modular components to non-module, non-chip-level implementations, and further to aggregated, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some practical environments, a device incorporating the described aspects and features may also include additional components and features as necessary to implement and practice the various embodiments as claimed and described. For example, the transmission and reception of wireless signals must include several components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, summers/summers, etc.). The innovations described herein are intended to be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, and the like, of various sizes, shapes, and configurations.

The various concepts presented throughout this disclosure may be implemented across a wide variety of telecommunications systems, network architectures, and communication standards. Referring now to fig. 1, various aspects of the present disclosure are illustrated with reference to a wireless communication system 100, as an illustrative example and not by way of limitation. The wireless communication system 100 includes three interaction domains: a core network 102, a Radio Access Network (RAN)104, and a User Equipment (UE) 106. With the wireless communication system 100, the UE 106 may be enabled to perform data communications with an external data network 110, such as, but not limited to, the internet.

RAN 104 may implement any suitable wireless communication technology or technologies to provide radio access to UEs 106. As one example, RAN 104 may operate in accordance with the third generation partnership project (3GPP) New Radio (NR) specification, commonly referred to as 5G. As another example, RAN 104 may operate under a mix of 5G NR and evolved universal terrestrial radio access network (eUTRAN) standards, commonly referred to as LTE. The 3GPP refers to this hybrid RAN as the next generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure.

As illustrated, the RAN 104 includes a plurality of base stations 108. Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. A base station may be referred to variously by those skilled in the art as a Base Transceiver Station (BTS), a radio base station, a radio transceiver, a transceiver function, a Basic Service Set (BSS), an Extended Service Set (ESS), an Access Point (AP), a Node B (NB), an evolved node B (eNB), a gbb node (gbb), or some other suitable terminology, in different technologies, standards, or contexts.

The radio access network 104 is further illustrated as supporting wireless communication for a plurality of mobile devices. A mobile device may be referred to as a User Equipment (UE) in the 3GPP standards, but may also be referred to by those skilled in the art as a Mobile Station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless communications device, a remote device, a mobile subscriber station, an Access Terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE may be a device that provides a user with access to network services.

Within this document, a "mobile" device does not necessarily need to have mobility capabilities, and may be stationary. The term mobile device or mobile equipment generally refers to a wide variety of equipment and technologies. A UE may include several hardware structural components sized, shaped, and arranged to facilitate communication; such components may include antennas, antenna arrays, RF chains, amplifiers, one or more processors, and so forth, electrically coupled to each other. For example, some non-limiting examples of mobile devices include mobile devices, cellular (cell) phones, smart phones, Session Initiation Protocol (SIP) phones, laptops, Personal Computers (PCs), notebooks, netbooks, smartbooks, tablets, Personal Digital Assistants (PDAs), and a wide variety of embedded systems, e.g., corresponding to the "internet of things" (IoT). Additionally, the mobile device may be an automobile or other transportation vehicle, a remote sensor or actuator, a robot or robotic device, a satellite radio, a Global Positioning System (GPS) device, an object tracking device, a drone, a multi-axis aircraft, a quadcopter, a remote control device, a consumer and/or wearable device (such as glasses), a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, and so forth. The mobile device may additionally be a digital home or intelligent home appliance, such as a home audio, video and/or multimedia appliance, vending machine, intelligent lighting device, home security system, smart meter, and the like. The mobile device may additionally be a smart energy device, a security device, a solar panel or array, a municipal infrastructure device (e.g., a smart grid) that controls power, lighting, water, etc.; industrial automation and enterprise equipment; a logistics controller; agricultural equipment; military defense equipment, vehicles, airplanes, boats, weapons, and the like. Still further, the mobile device may provide networked medical or telemedicine support, i.e., remote health care. The remote healthcare devices may include remote healthcare monitoring devices and remote healthcare supervisory devices whose communications may be given priority or preferential access over other types of information, for example in the form of prioritized access to critical service data transmissions and/or associated QoS for critical service data transmissions.

Wireless communication between RAN 104 and UE 106 may be described as utilizing an air interface. Transmissions from a base station (e.g., base station 108) to one or more UEs (e.g., UE 106) over the air interface may be referred to as Downlink (DL) transmissions. In accordance with certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station 108). Another way of describing this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE 106) to a base station (e.g., base station 108) may be referred to as Uplink (UL) transmissions. According to further aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at a scheduled entity (described further below; e.g., UE 106).

In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., base station 108) allocates resources for communication among some or all of the devices and equipment within its service area or cell. Within this disclosure, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities, as discussed further below. That is, for scheduled communications, the UE 106 (which may be a scheduled entity) may utilize resources allocated by the scheduling entity 108.

Base station 108 is not the only entity that can act as a scheduling entity. That is, in some examples, a UE may serve as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). And as discussed below, the UE may communicate directly with other UEs in a peer-to-peer manner and/or in a relay configuration.

As illustrated in fig. 1, the scheduling entity 108 may broadcast downlink traffic 112 to one or more scheduled entities 106. Broadly, the scheduling entity 108 is a node or device responsible for scheduling traffic (including downlink traffic 112 and, in some examples, also uplink traffic 116 from one or more scheduled entities 106 to the scheduling entity 108) in a wireless communication network. On the other hand, the scheduled entity 106 is a node or device that receives downlink control information 114 (including but not limited to scheduling information (e.g., grants), synchronization or timing information), or other control information from another entity in the wireless communication network, such as the scheduling entity 108.

In addition, uplink and/or downlink control information and/or traffic information may be divided in time into frames, subframes, slots, and/or symbols. As used herein, a symbol may refer to a unit of time that carries one Resource Element (RE) per subcarrier in an Orthogonal Frequency Division Multiplexing (OFDM) waveform. A slot may carry 7 or 14 OFDM symbols. A subframe may refer to a duration of 1 ms. Multiple subframes or slots may be grouped together to form a single frame or radio frame. Of course, these definitions are not required, and the waveforms may be organized using any suitable scheme, and the various time divisions of the waveforms may have any suitable duration.

In general, the base station 108 may include a backhaul interface for communicating with a backhaul portion 120 of a wireless communication system. The backhaul 120 may provide a link between the base station 108 and the core network 102. Further, in some examples, a backhaul network may provide interconnection between respective base stations 108. Various types of backhaul interfaces may be employed, such as direct physical connections using any suitable transport network, virtual networks, and so forth.

The core network 102 may be part of the wireless communication system 100 and may be independent of the radio access technology used in the RAN 104. In some examples, the core network 102 may be configured according to the 5G standard (e.g., 5 GC). In other examples, the core network 102 may be configured according to a 4G Evolved Packet Core (EPC), or any other suitable standard or configuration.

Referring now to fig. 2, a schematic illustration of a RAN 200 is provided by way of example and not limitation. In some examples, RAN 200 may be the same as RAN 104 described above and illustrated in fig. 1. The geographic area covered by the RAN 200 may be divided into cellular regions (cells) that may be uniquely identified by User Equipment (UE) based on an identification broadcast from one access point or base station. Fig. 2 illustrates

macro cells

202, 204, and 206, and small cell 208, each of which may include one or more sectors (not shown). A sector is a sub-area of a cell. All sectors within a cell are served by the same base station. A radio link within a sector may be identified by a single logical identification belonging to the sector. In a cell divided into sectors, multiple sectors within a cell may be formed by groups of antennas, with each antenna responsible for communication with UEs in a portion of the cell.

Various base station arrangements may be utilized. For example, in fig. 2, two

base stations

210 and 212 are shown in

cells

202 and 204; and a third base station 214 is shown controlling a Remote Radio Head (RRH)216 in the cell 206. That is, the base station may have an integrated antenna, or may be connected to an antenna or RRH by a feeder cable. In the illustrated example,

cells

202, 204, and 126 may be referred to as macro cells because

base stations

210, 212, and 214 support cells having large sizes. Further, the base station 218 is shown in a small cell 208 (e.g., a microcell, picocell, femtocell, home base station, home node B, home enodeb, etc.), which small cell 208 may overlap with one or more macro cells. In this example, cell 208 may be referred to as a small cell because base station 218 supports cells having a relatively small size. Cell sizing may be done according to system design and component constraints.

It is to be understood that the radio access network 200 may include any number of wireless base stations and cells. Further, relay nodes may be deployed to extend the size or coverage area of a given cell. The

base stations

210, 212, 214, 218 provide wireless access points to the core network for any number of mobile devices. In some examples, the

base stations

210, 212, 214, and/or 218 may be the same as the base station/scheduling entity 108 described above and illustrated in fig. 1.

Within the RAN 200, cells may include UEs that may be in communication with one or more sectors of each cell. Further, each

base station

210, 212, 214, and 218 may be configured to provide an access point to the core network 102 (see fig. 1) for all UEs in the respective cell. For example,

UEs

222 and 224 may be in communication with base station 210;

UEs

226 and 228 may be in communication with base station 212;

UEs

230 and 232 may be in communication with base station 214 via RRH 216; and the UE 234 may be in communication with the base station 218. In some examples, the

UEs

222, 224, 226, 228, 230, 232, 234, 238, 240, and/or 242 may be the same as the UEs/scheduled entities 106 described above and illustrated in fig. 1.

In some examples, an Unmanned Aerial Vehicle (UAV)220 (which may be a drone or a quadcopter) may be a mobile network node and may be configured to function as a UE. For example, the UAV 220 may operate within the cell 202 by communicating with the base station 210.

In a further aspect of RAN 200, side-link signals may be used between UEs without having to rely on scheduling or control information from the base station. For example, two or more UEs (e.g., UEs 226 and 228) may communicate with each other using peer-to-peer (P2P) or sidelink signals 227 without relaying the communication through a base station (e.g., base station 212). In a further example, UE 238 is illustrated as communicating with

UEs

240 and 242. Here, UE 238 may serve as a scheduling entity or primary sidelink device, and

UEs

240 and 242 may each serve as a scheduled entity or non-primary (e.g., secondary) sidelink device. In yet another example, the UE may serve as a scheduling or scheduled entity in a device-to-device (D2D), peer-to-peer (P2P), or vehicle-to-vehicle (V2V) network, a car networking (V2X), and/or a mesh network. In the mesh network example,

UEs

240 and 242 may optionally communicate directly with each other in addition to communicating with scheduling entity 238. Thus, in a wireless communication system having scheduled access to time-frequency resources and having a cellular configuration, a P2P configuration, or a mesh configuration, a scheduling entity and one or more scheduled entities may communicate utilizing the scheduled resources. In some examples, the sidelink signal 227 includes sidelink traffic and sidelink control.

The air interface in the radio access network 200 may utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of the various devices. For example, the 5G NR specification utilizes Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) to provide multiple access for UL transmissions from

UEs

222 and 224 to base station 210 and multiplexing for DL transmissions from base station 210 to one or

more UEs

222 and 224. In addition, for UL transmission, the 5G NR specification provides support for discrete fourier transform spread OFDM with CP (DFT-s-OFDM), also known as single carrier FDMA (SC-FDMA). However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes and may be provided using Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Sparse Code Multiple Access (SCMA), Resource Spreading Multiple Access (RSMA), or other suitable multiple access schemes. Further, multiplexing the DL transmissions from the base station 210 to the

UEs

222 and 224 may be provided using Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Frequency Division Multiplexing (FDM), Orthogonal Frequency Division Multiplexing (OFDM), Sparse Code Multiplexing (SCM), or other suitable multiplexing schemes.

The air interface in the radio access network 200 may further utilize one or more duplexing algorithms. Duplex refers to a point-to-point communication link where two end points can communicate with each other in both directions. Full duplex means that two endpoints can communicate with each other at the same time. Half-duplex means that only one endpoint can send information to another endpoint at a time. In wireless links, a full-duplex channel typically relies on physical isolation of the transmitter and receiver, as well as appropriate interference cancellation techniques. Full duplex emulation is typically achieved for wireless links by utilizing Frequency Division Duplex (FDD) or Time Division Duplex (TDD). In FDD, transmissions in different directions operate at different carrier frequencies. In TDD, transmissions in different directions on a given channel are separated from each other using time division multiplexing. That is, at some times the channel is dedicated to transmissions in one direction, and at other times the channel is dedicated to transmissions in the other direction, where the direction may change very quickly, e.g., several times per time slot.

Various aspects of the present disclosure will be described with reference to OFDM waveforms schematically illustrated in fig. 3. It will be appreciated by one of ordinary skill in the art that various aspects of the disclosure may be applied to SC-FDMA waveforms in substantially the same manner as described below. That is, while some examples of the disclosure may focus on OFDM links for clarity, it should be understood that the same principles may also be applied to SC-FDMA waveforms.

Referring now to fig. 3, an expanded view of an exemplary DL subframe 302 is illustrated showing an OFDM resource grid. However, as those skilled in the art will readily appreciate, the PHY transmission structure for any particular application may differ from the examples described herein depending on any number of factors. Here, time is in the horizontal direction in units of OFDM symbols; and the frequency is in the vertical direction in units of subcarriers.

The resource grid 304 may be used to schematically represent time-frequency resources for a given antenna port. That is, in a multiple-input multiple-output (MIMO) implementation where multiple antenna ports are available, there may be a corresponding multiple number of resource grids 304 available for communication. Resource grid 304 is divided into a plurality of Resource Elements (REs) 306. The RE (which is 1 subcarrier x 1 symbol) is the smallest discrete part of the time-frequency grid and contains a single complex value representing the data from the physical channel or signal. Each RE may represent one or more information bits, depending on the modulation utilized in a particular implementation. In some examples, a RE block may be referred to as a Physical Resource Block (PRB) or Resource Block (RB)308, which includes any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers, the number being independent of the set of parameters used. In some examples, an RB may include any suitable number of consecutive OFDM symbols in the time domain, depending on the parameter set. Within this disclosure, it is assumed that a single RB, such as RB 308, corresponds entirely to a single direction of communication (transmission or reception for a given device).

Scheduling a UE (e.g., a scheduled entity) for downlink or uplink transmission typically involves scheduling one or more resource elements 306 within one or more subbands. Thus, the UE generally utilizes only a subset of the resource grid 304. In some examples, an RB may be the smallest unit of resource that may be allocated to a UE. Thus, the more RBs scheduled for a UE and the higher the modulation scheme selected for the air interface, the higher the data rate for that UE.

In this illustration, RB 308 is shown occupying less than the entire bandwidth of subframe 302, with some subcarriers above and below RB 308 illustrated. In a given implementation, subframe 302 may have a bandwidth corresponding to any number of one or more RBs 308. Further, in this illustration, RB 308 is shown to occupy less than the entire duration of subframe 302, but this is just one possible example.

Each 1ms subframe 302 may include one or more adjacent slots. As an illustrative example, in the example shown in fig. 3, one subframe 302 includes four slots 310. In some examples, a slot may be defined according to a specified number of OFDM symbols with a given Cyclic Prefix (CP) length. For example, a slot may include 7 or 14 OFDM symbols with a nominal CP. Additional examples may include mini-slots (sometimes referred to as shortened Transmission Time Intervals (TTIs)) having shorter durations, such as one to three OFDM symbols. In some cases, these mini-slots or shortened Transmission Time Intervals (TTIs) may be transmitted occupying resources scheduled for ongoing slot transmissions for the same or different UEs. Any number of resource blocks may be utilized within a subframe or slot.

An expanded view of one slot 310 illustrates the slot 310 including a control region 312 and a data region 314. Generally, control region 312 can carry control channels and data region 314 can carry data channels. Of course, a slot may contain full DL, full UL, or at least one DL portion and at least one UL portion. The structure illustrated in fig. 3 is merely exemplary in nature and different slot structures may be utilized and one or more may be included for each of the control region and the data region.

Although not illustrated in fig. 3, individual REs 306 within an RB 308 may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, and so on. Other REs 306 within RB 308 may also carry pilots or reference signals including, but not limited to, demodulation reference signals (DMRS), Control Reference Signals (CRS), or Sounding Reference Signals (SRS). These pilot or reference signals may be used by a receiving device to perform channel estimation for the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within the RB 308.

In a DL transmission, a transmitting device (e.g., scheduling entity 108) may allocate one or more REs 306 (e.g., within control region 312) to carry DL control information to one or more scheduled entities, the DL control information including one or more DL control channels, such as PBCH; PSS; SSS; physical Control Format Indicator Channel (PCFICH); a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH); and/or a Physical Downlink Control Channel (PDCCH), etc. The PCFICH provides information to assist the receiving device in receiving and decoding the PDCCH. The PDCCH carries Downlink Control Information (DCI) including, but not limited to, power control commands, scheduling information, grants, and/or assignments of REs for DL and UL transmissions. The PHICH carries HARQ feedback transmissions, such as an Acknowledgement (ACK) or Negative Acknowledgement (NACK). HARQ is a technique well known to those of ordinary skill in the art, wherein the integrity of a packet transmission may be checked at the receiving side, for accuracy, for example, using any suitable integrity checking mechanism, such as a checksum (checksum) or a Cyclic Redundancy Check (CRC). An ACK may be transmitted if the integrity of the transmission is confirmed and a NACK may be transmitted if not confirmed. In response to the NACK, the transmitting device may send a HARQ retransmission, which may implement chase combining, incremental redundancy, and so on.

In UL transmissions, a transmitting device (e.g., scheduled entity 106) may utilize one or more REs 306 to carry UL control information to a scheduling entity, which includes one or more UL control channels, such as a Physical Uplink Control Channel (PUCCH). The UL control information may include various packet types and categories, including pilots, reference signals, and information configured to enable or assist in decoding uplink data transmissions. In some examples, the control information may include a Scheduling Request (SR), i.e., a request for a scheduling entity to schedule an uplink transmission. Here, in response to the SR transmitted on the control channel, the scheduling entity may transmit downlink control information, which may schedule resources for uplink packet transmission. The UL control information may also include HARQ feedback, Channel State Feedback (CSF), or any other suitable UL control information.

In addition to control information, one or more REs 306 (e.g., within data region 314) may also be allocated for user data traffic. Such traffic may be carried on one or more traffic channels, such as for DL transmissions, may be carried on a Physical Downlink Shared Channel (PDSCH); or may be carried on the Physical Uplink Shared Channel (PUSCH) for UL transmissions. In some examples, one or more REs 306 within data region 314 may be configured to carry System Information Blocks (SIBs) that carry information that may enable access to a given cell.

These physical channels are typically multiplexed and mapped to transport channels for handling by the Medium Access Control (MAC) layer. The transport channels carry blocks of information, called Transport Blocks (TBs). The Transport Block Size (TBS), which may correspond to the number of information bits, may be a controlled parameter based on the Modulation Coding Scheme (MCS) and the number of RBs in a given transmission.

The channels or carriers described above in connection with fig. 1-3 are not necessarily all channels or carriers available between the scheduling entity and the scheduled entity, and one of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels.

In some aspects of the disclosure, the scheduling entity and/or scheduled entity may be configured for beamforming and/or multiple-input multiple-output (MIMO) techniques. Fig. 4 illustrates an example of a wireless communication system 400 that supports beamforming and/or MIMO. In a MIMO system, the transmitter 402 includes multiple transmit antennas 404 (e.g., N transmit antennas) and the receiver 406 includes multiple receive antennas 408 (e.g., M receive antennas). Thus, there are N × M signal paths 410 from the transmit antenna 404 to the receive antenna 408. Each of the transmitter 402 and the receiver 406 may be implemented, for example, in a scheduling entity, a scheduled entity, or any other suitable wireless communication device.

The use of such multiple antenna techniques enables wireless communication systems to utilize the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different data streams (also referred to as layers) simultaneously on the same time-frequency resource. These data streams may be transmitted to a single UE to increase the data rate or to multiple UEs to increase the overall system capacity, the latter being referred to as multi-user MIMO (MU-MIMO). This is achieved by spatially precoding each data stream (i.e., multiplying the data streams with different weights and phase shifts) and then transmitting each spatially precoded stream over multiple transmit antennas on the downlink. The spatially precoded data streams arrive at the UE(s) with different spatial signatures that enable each UE to recover one or more data streams intended for that UE. On the uplink, each UE transmits a spatially precoded data stream, which enables the base station to identify the source of each spatially precoded data stream.

The number of data streams or layers corresponds to the rank of the transmission. In general, the rank of the MIMO system 400 is limited to the lower of the number of transmit or receive

antennas

404 or 408. Additionally, channel conditions at the UE and other considerations (such as available resources at the base station) may also affect the transmission rank. For example, the rank (and thus, the number of data streams) assigned to a particular UE on the downlink may be determined based on a Rank Indicator (RI) transmitted from the UE to the base station. The RI may be determined based on the antenna configuration (e.g., the number of transmit and receive antennas) and the measured signal-to-interference-and-noise ratio (SINR) on each receive antenna. The RI may indicate, for example, the number of layers that may be supported under the current channel conditions. The base station may use the RI along with resource information (e.g., available resources and the amount of data to be scheduled for the UE) to assign a transmission rank to the UE.

In one example, as shown in fig. 4, rank 2 spatial multiplexing transmission over a 2x2 MIMO antenna configuration would transmit one data stream from each transmit antenna 404. Each data stream follows a different signal path 410 to each receive antenna 408. Receiver 406 may then reconstruct the data streams using the signals received from each receive antenna 408.

Beamforming is a signal processing technique that may be used at the transmitter 402 or the receiver 406 to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitter 402 and the receiver 406. Beamforming may be achieved by combining signals communicated via antennas 404 or 408 (e.g., antenna elements of an antenna array module) such that some of the signals undergo constructive interference while others undergo destructive interference. To create the desired constructive/destructive interference, the transmitter 402 or receiver 406 may apply an amplitude and/or phase offset to signals transmitted or received from each of the

antennas

404 or 408 associated with the transmitter 402 or receiver 406.

A base station (e.g., a gNB) is typically able to communicate with UEs using beams of different beamwidths. For example, a base station may be configured to utilize a wider beam when communicating with a UE in motion; while utilizing narrower beams when communicating with a stationary UE. In some examples, to select a particular beam for communicating with the UE, the base station may transmit a reference signal, such as a Synchronization Signal Block (SSB) or a channel state information reference signal (CSI-RS), on each of the multiple beams in a beam sweeping manner. The UE may measure Reference Signal Received Power (RSRP) on each beam and transmit a beam measurement report to the base station indicating the RSRP for each measured beam. The base station may then select a particular beam for communicating with the UE based on the beam measurement report. In other examples, when the channel is reciprocal, the base station may derive a particular beam for communicating with the UE based on uplink measurements of one or more uplink reference signals, such as Sounding Reference Signals (SRS).

In 5G New Radio (NR) systems, especially for above 6GHz or mmWave systems, beamformed signals may be used for most downlink channels, including the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH). In addition, broadcast control information, such as a primary system information block (MSIB), a Slot Format Indicator (SFI), and paging information, may be transmitted in a beam sweeping manner to enable all scheduled entities (UEs) in a coverage area transmitting a reception point (TRP) (e.g., a gNB) to receive the broadcast control information. In addition, for UEs configured with a beamforming antenna array, beamformed signals may also be used for uplink channels, including Physical Uplink Control Channel (PUCCH) and Physical Uplink Shared Channel (PUSCH). However, it should be understood that beamformed signals may also be used by an enhanced mobile broadband (eMBB) gNB for sub-6 GHz systems.

Fig. 5 is a diagram illustrating communication between a Base Station (BS)504, such as a gNB, and a UE 502 using downlink beamformed signals, according to some aspects of the present disclosure. The base station 504 may be any of the base stations or scheduling entities illustrated in fig. 1 and 2, and the UE 502 may be any of the UEs or scheduled entities illustrated in fig. 1 and 2. It should be noted that although some beams are illustrated as being adjacent to one another, such arrangements may be different in different aspects. In some examples, the beams transmitted during the same symbol may not be adjacent to each other. In some examples, the BS 504 may transmit more or fewer beams distributed in all directions (e.g., 360 degrees).

In the example shown in fig. 5, the beam set contains eight

different beams

521, 522, 523, 524, 525, 526, 527, 528, each associated with a different beam direction. In some examples, the BS 504 may be configured to sweep or transmit each of the

beams

521, 522, 523, 524, 525, 526, 527, 528 during the synchronization time slots. For example, BS 504 may transmit a reference signal (such as an SSB or CSI-RS) on each beam in a different beam direction during the synchronization slot. The transmission of the beam reference signal may occur periodically (e.g., as configured by the gNB via Radio Resource Control (RRC) signaling), semi-persistently (e.g., as configured by the gNB via RRC signaling and activated/deactivated via medium access control-control element (MAC-CE) signaling), or aperiodically (e.g., as triggered by the gNB via Downlink Control Information (DCI)).

The UE 502 identifies beams with received beam reference signals and performs received power measurements (e.g., RSRP) on the beam reference signals. The UE 502 may then transmit a beam measurement report 560 including the respective beam index and RSRP for each beam 521-. BS 504 may then determine the downlink beam (e.g., beam 524) from beam measurement report 560 by which to transmit unicast downlink control information and/or user data traffic with the highest gain to UE 502. Transmission of beam measurement report 560 may occur periodically (e.g., as configured by the gNB via RRC signaling), semi-persistently (e.g., as configured by the gNB via RRC signaling and activated/deactivated by MAC-CE signaling), or aperiodically (e.g., triggered by the gNB via DCI).

In other examples, BS 504 may derive the downlink beam when the channel is reciprocal (e.g., downlink and uplink channel quality are the same). The derivation can be based on uplink measurements by the UE 502, such as by measuring received power, quality, or other variables of a Sounding Reference Signal (SRS) or other uplink reference signal. In some examples, the UE may not transmit the beam measurement report 560 to the BS 504. In some examples, the BS 504 may select a beam pair (e.g., a downlink transmit beam associated with the BS 504 and a downlink receive beam associated with the UE 502) as a Beam Pair Link (BPL) based on the received beam measurement report 560 and/or the uplink measurements.

When the BS 504 switches from one downlink beam to another downlink beam, the BS 504 may perform link adaptation. Link adaptation may adjust the Modulation and Coding Scheme (MCS). An adjustment may occur with respect to a link budget associated with the new downlink beam. In some examples, the BS 504 may utilize an outer loop link adaptation process, where the MCS may be modified based on HARQ feedback (e.g., ACKs and NACKs) from the UE 502. In other examples, the BS 504 may dynamically schedule transmission of CSI-RS to the UE 502 on the new downlink beam. According to the CSI-RS, the UE 502 may measure channel quality and provide Channel State Feedback (CSF) to the BS 504. The CSF may include, for example, a Channel Quality Indicator (CQI) by which the BS 504 may select/adjust the MCS for unicast transmission to the UE 502 on the new downlink beam. In selecting/adjusting the MCS, the BS 504 may then further utilize the outer loop link adaptation process to further modify the MCS as needed until another CSI-RS is transmitted to the UE 502.

Although dynamic transmission of CSI-RS to UE 502 may result in a faster MCS adjustment than the outer loop link adaptation process, in either case, the beam switching is followed by a link adaptation convergence period during which it may suffer from a block error rate (BLER) burst when the link moves to a beam with lower spectral efficiency or a lower throughput when the link moves to a beam with higher spectral efficiency.

Further, when the beams are quasi co-located (or QCL), the BS 504 may not signal to the UE 502 that the BS 504 is switching beams. This may cause the UE 502 to experience a sudden increase in received signal strength, which may increase the BLER at the UE 502. For example, when the BS 504 switches from a wide beam to a narrow beam, the antenna gain difference between the wide beam and the narrow beam may be significant, resulting in large jumps in received signal strength at the UE 502.

In various aspects of the present disclosure, to minimize BLER after performing downlink beam switching from a current downlink beam to a new downlink beam, BS 504 may mitigate a link adaptation convergence period. Mitigation may occur by adjusting the MCS according to the difference in RSRP between the current beam and the new beam. In some examples, the difference in RSRP may be discerned from a beam measurement report 560 sent from the UE 502 to the BS 504. In other examples, channel reciprocity may be utilized, where the BS 504 may derive a difference in RSRP from uplink measurements on corresponding uplink beams associated with the BS 504. For example, the BS 504 may compare the uplink channel quality (e.g., received power) measured on a previous uplink beam corresponding to a previous downlink beam at the BS 504 prior to the beam switch with the uplink channel quality (e.g., received power) measured on a new uplink beam corresponding to a new downlink beam at the BS 504 after the beam switch.

By adjusting the MCS based on the difference of RSRP, an initial change in MCS may be applied in the first slot after beam switching, which reduces the convergence time of outer loop link adaptation. Furthermore, the BLER during the convergence period may be reduced when moving to beams with lower RSRP. In examples where CSFs are used for link adaptation, performing an initial adjustment to the MCS based on the difference in RSRP optimizes link adaptation until UE 502 reports the first CSF.

In other aspects of the disclosure, to minimize BLER at the UE 502 upon downlink beam switching, the UE 502 may modify an Automatic Gain Control (AGC) state of the UE. The modification may be based on a difference in RSRP between the current downlink beam and the expected downlink beam. In some examples, the intended downlink beam may be a beam that is intended to be selected by the BS 504 for a subsequent downlink transmission (e.g., a unicast transmission) to the UE 502. The UE 502 may identify an intended downlink beam based on RSRP measurements made by the UE 502 during the synchronization time slot (e.g., during a beam sweep). In some examples, the expected downlink beam may have the highest RSRP of all measured RSRPs of different downlink beams. In other examples, the expected downlink beams may have a lower RSRP or be grouped to within a range of desired RSRP levels. The desired downlink beam may be selected based on various criteria (e.g., power, timing, signal quality, channel conditions, beam type, polarization, operating conditions, etc.). In the case where the BS 504 does not switch beams, the UE 502 may further apply a slow decay to the AGC state to converge back to the nominal value of the current downlink beam.

By modifying the AGC state prior to beam switching based on the expected downlink beam, the AGC step response latency can be reduced to near zero and the AGC can be in an optimal state in the first time slot after beam switching. As a result, the BLER experienced by the UE when switching from a wide beam to a narrow beam, or more generally from a beam with a lower RSRP to a beam with a higher RSRP, may be minimized.

Fig. 6 illustrates an example of a UE 600 configured to modify AGC states of one or more receiver gain stages within the UE. UE 600 includes an antenna 602, a Low Noise Amplifier (LNA)604, a down conversion module 606, a local oscillator 608, an optional variable gain amplifier 610, an analog-to-digital converter (ADC)612, and a processor 614. The antenna 602 may be a single antenna shared by the transmit and receive paths (half-duplex) or may include separate antennas for the transmit and receive paths (full-duplex). The antennas may further include multiple transmit and/or receive antennas to support MIMO and/or beamforming techniques.

LNA 604 is configured to receive a Radio Frequency (RF) signal from antenna 602 and amplify the RF signal to generate an amplified RF signal. The down-conversion module 606 is configured to receive the amplified RF signal from the LNA 604 and convert the amplified RF signal to a low Intermediate Frequency (IF) signal or a baseband signal based on a local oscillation provided by the local oscillator 608. Optional VGA 610 is configured to receive the low IF or baseband signal from the down conversion module and adjust the gain of the low IF or baseband signal before providing it to ADC 612. ADC 612 converts the low IF or baseband signals from the analog domain to the digital domain to produce digital signals that can be processed by processor 614. For example, processor 614 may demodulate, demap, descramble, and/or decode the digital signals to generate information (e.g., control information and/or user data traffic).

The UE 600 further includes an additional ADC 616 and an Automatic Gain Control (AGC) module 618. The additional ADC 616 is configured to receive the low IF signal or baseband signal from the down conversion module and convert the low IF signal or baseband signal from the analog domain to the digital domain to produce an additional digital signal for input to the AGC module 618. The AGC module 618 is configured to continuously monitor the received power (or received signal strength) of the additional digital signal and adjust one or more receiver gain stages of the UE based on the received power (or received signal strength) to ensure that the received signal strength at the input of the ADC 612 is sufficient for correct decoding. The one or more gain stages may include, for example, LNA 604 and VGA 610.

For example, if the received strength is low, the AGC module 618 may boost one or more receiver gain levels. This may be done to minimize noise at the input of the ADC 612 and to achieve an acceptable signal-to-noise ratio (SNR) for the signal level (e.g., within the dynamic range of the ADC 612). As another example, if the received signal strength is high, the AGC module 618 may attenuate one or more receiver gain stages to avoid signal clipping and non-linear degradation and to achieve an acceptable SNR for the signal level at the input of the ADC 612. In general, the AGC module 618 may be configured to increase or decrease the gain of one or more gain stages in particular steps based on a comparison between the received signal strength and one or more thresholds, each of which may be associated with a different gain step. For example, the gain step size for each threshold may be defined in a look-up table (not shown).

In various aspects of the disclosure, the processor 614 may be further configured to instruct the AGC module 618 to modify the AGC state of one or more receiver gain stages (e.g., the LNA 604 and/or the VGA 610). The modification may be based on a difference between an RSRP of a current downlink beam currently used by the base station to communicate with UE 600 and an RSRP of an expected downlink beam that the base station expects to use for subsequent downlink transmissions to UE 600. In some examples, processor 614 may instruct AGC module 618 to modify the AGC state by an amount equal to the difference between the RSRP of the current beam and the RSRP of the intended beam.

In an example, processor 614 may perform and/or implement a number of specialized acts or functions. For example, processor 614 may be configured to receive a respective reference signal on each of a plurality of downlink beams. The reception of the reference signal may be during a beam sweep performed by the base station (e.g., via antenna 602, LNA 604, down-conversion module 606, VGA 610, and ADC 612). As another example, processor 614 may measure RSRP of respective reference signals corresponding to each of the plurality of downlink beams. Processor 614 may be further configured to compare the measured RSRP of each downlink beam to identify an expected downlink beam that is expected to be used by the base station for a subsequent downlink transmission. In some examples, the expected downlink beams have the highest measured RSRP of the measured RSRPs of all of the downlink beams. Processor 614 may further identify a measured RSRP for the current downlink beam and calculate a difference between the measured RSRP for the current downlink beam and the measured RSRP for the expected downlink beam. Based on the RSRP difference, the processor 614 may then instruct the AGC module 618 to modify the AGC state by an amount corresponding to the difference in RSRP.

Fig. 7 illustrates exemplary signaling between a UE 702 and a base station 704 that minimizes BLER based on an expected beam switch. The UE 702 may correspond to any of the UEs shown in fig. 1, 2, 5, and/or 6. Further, the base station 704 may correspond to any of the base stations shown in fig. 1, 2, 5, and/or 6.

At 706, the base station 704 may perform a beam sweep to transmit a reference signal (e.g., an SSB or CSI-RS) to the UE 702 on each of a plurality of downlink beams. At 708, the UE 702 may measure RSRP on each of the plurality of downlink beams. At 710, UE 702 may generate and transmit a beam measurement report comprising the measured RSRP for each of a plurality of downlink beams.

Based on the measured RSRP for each of the plurality of downlink beams, at 712, UE 702 may adjust the AGC state of the UE further based on an expected beam of the plurality of beams that is expected to be selected by base station 704 for a subsequent unicast downlink transmission to UE 702. For example, the UE 702 may adjust the AGC state of one or more receiver gain stages (e.g., an LNA and/or a VGA in a receiver chain). In some examples, UE 702 may modify the AGC state by an amount equal to a difference between the RSRP of the current downlink beam and the RSRP of the intended downlink beam. For example, when the UE 702 expects the base station 704 to switch from the current wide beam to the expected narrow beam, the UE 702 may attenuate the one or more receiver gain stages due to an expected increase in RSRP between the current wide beam and the expected narrow beam.

At 714, the UE 702 may receive a unicast downlink transmission from the base station 704 via the intended downlink beam. By modifying the AGC state prior to receiving the unicast downlink transmission, UE 702 may minimize the BLER of the unicast downlink transmission.

Fig. 8 is a conceptual diagram illustrating an example of a hardware implementation of an exemplary User Equipment (UE) employing processing system 814. For example, the UE 800 may be a UE as illustrated in any one or more of fig. 1, 2, and/or 5-7.

The UE 800 may be implemented with a processing system 814 that includes one or more processors 804. Examples of processor 804 include microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionalities described throughout this disclosure. In various examples, UE 800 may be configured to perform any one or more of the functions described herein. That is, the processor 804 as utilized in the UE 800 may be utilized to implement any one or more of the processes described below. In some examples, processor 804 may be implemented via a baseband or modem chip, while in other implementations, processor 804 itself may comprise a number of devices distinct and different from the baseband or modem chip (e.g., may work in conjunction in such scenarios to achieve the embodiments discussed herein). And as mentioned above, various hardware arrangements and components other than baseband modem processors may be used in implementations, including RF chains, power amplifiers, modulators, buffers, interleavers, summers/summers, etc.

In this example, the processing system 814 may be implemented with a bus architecture, represented generally by the bus 802. The bus 802 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 814 and the overall design constraints. The bus 802 communicatively couples various circuits including one or more processors (represented generally by processor 804), memory 805, and computer-readable media (represented generally by computer-readable media 806). The bus 802 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface 808 provides an interface between the bus 802 and a transceiver 810. The transceiver 810 provides a means for communicating with various other apparatus over a transmission medium, such as an air interface. A user interface 812 (e.g., keypad, display, speaker, microphone, joystick) may also be provided.

The processor 804 is responsible for managing the bus 802 and general processing, including the execution of software stored on the computer-readable medium 806. The software, when executed by the processor 804, causes the processing system 814 to perform the various functions described below for any particular apparatus. The computer-readable medium 806 and the memory 805 may also be used for storing data that is manipulated by the processor 804 when executing software.

One or more processors 804 in the processing system may execute software. Software should be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subprograms, software modules, applications, software applications, packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to in software, firmware, middleware, microcode, hardware description language, or other terminology. The software may reside on computer-readable medium 806.

The computer-readable medium 806 may be a non-transitory computer-readable medium. By way of example, non-transitory computer-readable media include magnetic storage devices (e.g., hard disks, floppy disks, magnetic tape), optical disks (e.g., Compact Disks (CDs) or Digital Versatile Disks (DVDs)), smart cards, flash memory devices (e.g., cards, sticks, or key drives), Random Access Memory (RAM), Read Only Memory (ROM), programmable ROM (prom), erasable prom (eprom), electrically erasable prom (eeprom), registers, removable disks, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. By way of example, computer-readable media may also include carrier waves, transmission lines, and any other suitable media for conveying software and/or instructions that are accessible and readable by a computer. The computer-readable medium 806 may reside in the processor system 814, external to the processing system 814, or distributed across multiple entities including the processing system 814. The computer-readable medium 806 may be embodied in a computer program product. In some examples, computer-readable medium 806 may be a portion of memory 805. By way of example, a computer program product may include a computer-readable medium in packaging material. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure, depending on the particular application and the overall design constraints imposed on the overall system.

In some aspects of the disclosure, the processor 804 may include circuitry configured for various functions. For example, the processor 804 may include communication and processing circuitry 842 configured to communicate with a base station. In some examples, the communication and processing circuitry 842 may include one or more hardware components that provide a physical structure for performing processes related to wireless communication (e.g., signal reception and/or signal transmission) and signal processing (e.g., processing received signals and/or processing signals for transmission).

In some examples, the communications and processing circuitry 842 may be configured to generate and transmit the uplink beamformed signal at the millimeter wave frequency or the sub-6 GHz frequency via the transceiver 810 and the antenna array 820. For example, communications and processing circuitry 842 may be configured to transmit beam measurement report 815 to a base station. Further, the communications and processing circuitry 842 may be configured to receive and process the downlink beamformed signals at millimeter wave frequencies or sub-6 GHz frequencies via the antenna array module 820 and the transceiver 810. For example, the communication and processing circuitry 842 may be configured to receive, from a base station, a respective reference signal on each of a plurality of downlink beams during a beam sweep. The communication and processing circuitry 842 may be further configured to receive unicast downlink control information and/or user data traffic from the base station on the selected downlink beam.

The communications and processing circuitry 842 may be further configured to receive the CSI-RS on the current downlink beam from the base station and transmit Channel State Feedback (CSF) to the base station in response to the CSI-RS. The CSF may include, for example, a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), and a Rank Indicator (RI). Further, the communication and processing circuitry 842 may be configured to implement a HARQ-based feedback mechanism to transmit ACK/NACKs to base stations. The communication and processing circuitry 842 may be further configured to execute the communication and processing software 852 stored in the computer-readable medium 806 to implement one or more functions described herein.

The processor 804 may further include beam management circuitry 844 configured to: a respective RSRP on each of a plurality of downlink beams is measured during a downlink beam sweep by the base station, and a beam measurement report 815 including the measured RSRP of each of the plurality of downlink beams is generated for transmission to the base station. Beam measurement report 815 may be further stored in memory 805 for further processing. Further, beam management circuitry 844 may be configured to identify an intended downlink beam intended for subsequent downlink transmissions by the base station based on the respective RSRP measured for each of the plurality of downlink beams. In some examples, the expected downlink beam corresponds to the downlink beam with the highest measured RSRP.

The beam management circuitry 844 may be further configured to generate and transmit various signals. The generation and transmission may be accomplished in conjunction with communication and processing circuitry 842. The reference signal may comprise an uplink reference signal on each of a plurality of uplink beams in different beam directions. Each uplink reference signal may comprise, for example, a contention-based RACH (random access channel) message or a Sounding Reference Signal (SRS). The transmission of the contention-based RACH message may occur during initial access and/or failure recovery using RACH resources covering all directions that are periodically allocated by the base station and shared by all UEs in the cell. The transmission of the SRS may occur during the connected mode and may be triggered aperiodically by the base station, scheduled periodically by the base station, or semi-persistently scheduled by the base station. The base station may perform received beam quality measurements on the uplink beam reference signals to identify an uplink beam on which the UE should transmit control information and/or user data traffic to the base station. Examples of beam quality measurements may include, but are not limited to, received power or signal-to-noise ratio (SNR). In some examples, beam management circuitry 844, along with communication and processing circuitry 842, may receive an uplink beam selection signal from a base station indicating a selected serving uplink beam. The beam management circuitry 844 may be further configured to execute beam management software 854 stored in the computer readable medium 806 to implement one or more of the functions described herein.

The processor 804 may further include Antenna Gain Control (AGC) circuitry 846 and Received Signal Strength Indicator (RSSI) measurement circuitry 848. AGC circuitry 846 may be configured to modify an AGC state of UE 800 based on an intended downlink beam identified by beam management circuitry 844. For example, AGC circuitry 846 may be configured to determine a first RSRP of a current downlink beam measured by beam management circuitry 844 and a second RSRP of an intended downlink beam measured by beam management circuitry 844. AGC circuitry 846 may be further configured to modify an AGC state of UE 800 by an amount equal to a difference between the first RSRP and the second RSRP. In some examples, the AGC circuitry 846 may be configured to attenuate one or more receiver gain stages (e.g., within the transceiver 810) by an amount equal to a difference between the first and second RSRPs. In some examples, the AGC circuitry 846 may correspond to the AGC module 618 and processor 614 shown in fig. 6 and may be configured to modify the AGC state of the LNA and/or VGA as described above in connection with fig. 6.

AGC circuitry 846 may be further configured to adjust the AGC state over a period of time to converge back to the initial AGC state (e.g., a nominal value associated with the current downlink beam prior to modifying the AGC state of the intended downlink beam) when the base station does not select the intended downlink beam for a subsequent unicast downlink transmission to UE 800. For example, the AGC circuitry 846 may apply a slow attenuation to the AGC state to substantially maintain the AGC state during a transition of the base station from a current downlink beam to a desired downlink beam. In some examples, the expected transition time interval for transitioning from the current downlink beam to the expected downlink beam may include a number of time slots. The AGC circuitry 846 may further apply a slow attenuation to the AGC state over additional time intervals that extend beyond the expected transition time interval to converge the AGC state back to the initial AGC state. Accordingly, the time period during which the AGC circuitry 846 may adjust (e.g., slowly decay) the AGC state may include a transition time interval and an additional time interval. The AGC circuitry 846 may be further configured to execute AGC software 856 stored on the computer-readable medium 806 to implement one or more of the functions described herein.

The RSSI measurement circuitry 848 may be configured to measure a respective RSSI for each of a plurality of received signals received from the base station over a period of time. RSSI measurement circuitry 848 may be further configured to provide RSSI measured over a period of time to AGC circuitry 846. When the measured RSSI substantially corresponds to the first RSRP for the current downlink beam (or similarly, the measured RSSI does not substantially correspond to the second RSRP for the intended downlink beam), the AGC circuitry 846 may adjust (e.g., slowly attenuate) the AGC state, thereby indicating that the base station has not switched to the intended downlink beam. The RSSI measurement circuitry 848 may be further configured to execute RSSI measurement software 858 stored in the computer-readable medium 806 to implement one or more of the functions described herein.

Fig. 9 is a flow diagram 900 of a method for minimizing BLER associated with beam switching for a UE. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the UE 800 as described above and illustrated in fig. 8, by a processor or processing system, or by any suitable means for performing the described functions.

At block 902, the UE may receive a plurality of downlink beams from a base station. For example, the base station may transmit a reference signal to the UE on each of a plurality of downlink beams during a beam sweep. For example, the communication and processing circuitry 842 shown and described above in connection with fig. 8 may receive multiple downlink beams.

At block 904, the UE may measure a respective RSRP for each of a plurality of downlink beams. For example, the beam management circuitry 844 shown and described above in connection with fig. 8 may measure RSRP for each downlink beam.

At block 906, the UE may identify an expected downlink beam of the plurality of downlink beams that is expected to be used by the base station for a subsequent downlink transmission based on the measured RSRP of each of the plurality of downlink beams. In some examples, the expected downlink beam has the highest measured RSRP of all downlink beams. For example, the beam management circuitry 844 illustrated and described above in connection with fig. 8 may identify a desired downlink beam.

At block 908, the UE may modify an AGC state of the UE based on the expected downlink beam before receiving the subsequent downlink transmission. In some examples, the UE may determine a first RSRP of a current downlink beam currently used by the base station for downlink transmissions and a second RSRP of an expected downlink beam expected by the base station for future downlink transmissions. The UE may then modify the AGC state by an amount equal to a difference between the first RSRP and the second RSRP. In some examples, the UE may be configured to attenuate the one or more receiver gain stages by an amount equal to a difference between the first and second RSRPs. For example, the AGC circuitry 846 shown and described above in connection with fig. 8 may modify the AGC state of the UE.

Fig. 10 is a flow diagram 1900 of a method for a UE to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the UE 800 as described above and illustrated in fig. 8, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1002, the UE may receive a plurality of downlink beams from a base station. For example, the base station may transmit a reference signal to the UE on each of a plurality of downlink beams during a beam sweep. For example, the communication and processing circuitry 842 shown and described above in connection with fig. 8 may receive multiple downlink beams.

At block 1004, the UE may measure a respective RSRP for each of a plurality of downlink beams. For example, the beam management circuitry 844 shown and described above in connection with fig. 8 may measure RSRP for each downlink beam.

At block 1006, the UE may identify an expected downlink beam of the plurality of downlink beams that is expected to be used by the base station for a subsequent downlink transmission based on the measured RSRP of each of the plurality of downlink beams. In some examples, the expected downlink beam has the highest measured RSRP of all downlink beams. For example, the beam management circuitry 844 illustrated and described above in connection with fig. 8 may identify a desired downlink beam.

At block 1008, the UE may modify an AGC state of the UE based on the expected downlink beam before receiving the subsequent downlink transmission. In some examples, the UE may determine a first RSRP of a current downlink beam currently used by the base station for downlink transmissions and a second RSRP of an expected downlink beam expected by the base station for future downlink transmissions. The UE may then modify the AGC state by an amount equal to a difference between the first RSRP and the second RSRP. In some examples, the UE may be configured to attenuate the one or more receiver gain stages by an amount equal to a difference between the first and second RSRPs. For example, the AGC circuitry 846 shown and described above in connection with fig. 8 may modify the AGC state of the UE.

At block 1010, the UE may measure a received signal strength (e.g., RSSI) of a signal received from a base station. For example, the RSSI measurement circuitry 848 shown and described above in connection with fig. 8 may measure the RSSI of the received signal.

At block 1012, the UE may determine whether the measured RSSI is equal to the RSRP of the current downlink beam (e.g., as determined at block 1004). If the measured RSSI is equal to the RSRP of the current downlink beam, the UE may adjust the AGC state to converge back to the initial AGC state (e.g., modify the nominal value before the AGC state for the intended downlink beam) at block 1014. In some examples, the UE may apply a slow decay to the AGC state to substantially maintain the modified AGC state during an expected transition time interval from the current downlink beam to the expected downlink beam. For example, the AGC circuitry 846 shown and described above in connection with fig. 8 may compare the measured RSSI to the measured RSRP of the current downlink beam and adjust the AGC state when the RSSI equals the RSRP of the current downlink beam.

At block 1016, the UE may determine whether the AGC state has converged back to the initial AGC state. If the AGC state is different from the initial AGC state, the process may return to block 1010, where the UE may measure the RSSI of the received signal and further adjust the AGC state at

blocks

1012 and 1014. For example, the AGC circuitry 846 shown and described above in connection with fig. 8 may determine whether the AGC has converged back to the initial AGC state.

Fig. 11 illustrates exemplary signaling between a UE 1102 and a base station 1104 to minimize BLER based on beam switching. The UE 1102 may correspond to any of the UEs shown in fig. 1, 2, and/or 5-8. Further, base station 1104 can correspond to any of the base stations shown in fig. 1, 2, and/or 5-7.

At 1106, the base station 1104 can perform a beam sweep to transmit a reference signal (e.g., an SSB or CSI-RS) to the UE 1102 on each of a plurality of downlink beams. At 1108, the UE 1102 may measure RSRP on each of the plurality of downlink beams. At 1110, UE 1102 may generate and transmit a beam measurement report including the measured RSRP for each of a plurality of downlink beams to base station 1104.

At 1112, the base station 1104 can switch beams. An example switch may include switching from a first beam of a plurality of beams currently used for unicast downlink transmissions to UE 1102 to a second beam of the plurality of beams for subsequent (future) unicast downlink transmissions to UE 1102 based on the measured RSRPs of the first and second beams. For example, the second beam may have a higher RSRP than the first beam. In some examples, the second beam may have the highest RSRP of all beams.

At 1114, the base station 1104 may modify a Modulation and Coding Scheme (MCS) based on an RSRP difference between the first and second beams. More specifically, base station 1104 may modify the MCS of the second beam based on the current MCS for the first beam and the RSRP difference between the first and second beams. Typically, higher order modulation (e.g., 64QAM) may be used on beams with higher RSRP. Furthermore, for a given modulation scheme, an appropriate code rate may be selected based on channel (beam) quality. For example, higher code rates may be used on beams with better quality (e.g., higher RSRP). At 1116, the base station 1104 may generate a unicast downlink transmission toward the UE 1102 using the second beam and the modified (new) MCS.

Fig. 12 is a conceptual diagram illustrating an example of a hardware implementation of an example base station 1200 employing a processing system 1214. For example, the base station 1200 may be the base station illustrated in any one or more of fig. 1, 2, 5-7, and/or 11.

The processing system 1214 may be substantially the same as the processing system 814 illustrated in fig. 8. The system 1214 may include a bus interface 1208, a bus 1202, a memory 1205, a processor 1204, and a computer-readable medium 1206. Further, the base station 1200 may include an optional user interface 1212 and transceiver 1210 substantially similar to those described above in fig. 8. Moreover, the UE may further include one or more antenna array modules 1220. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system 1204 that includes one or more processors 1214. That is, the processor 1200 as utilized in the base station 1204 may be utilized to implement any one or more of the processes described below.

In some aspects of the disclosure, the processor 1204 may include circuitry configured for various functions. For example, processor 1204 may include resource assignment and scheduling circuitry 1242 configured to: resource assignments or grants for time-frequency resources (e.g., a set comprising one or more resource elements) are generated, scheduled, and modified. For example, resource assignment and scheduling circuitry 1242 may schedule time-frequency resources within multiple Time Division Duplex (TDD) and/or Frequency Division Duplex (FDD) subframes, time slots, and/or mini-slots to carry user data traffic and/or control information to and/or from multiple UEs.

In some examples, resource assignment and scheduling circuitry 1242 may be configured to allocate/schedule downlink resources (e.g., millimeter wave or sub-6 GHz resources) for transmission of downlink beam reference signals to UEs during a downlink beam sweep. Resource assignment and scheduling circuitry 1242 may be further configured to allocate/schedule uplink resources for transmission of beam measurement reports from the UEs to base station 1200. In other examples, resource assignment and scheduling circuitry 1242 may be configured to allocate/schedule uplink resources for transmission of uplink beam reference signals from UEs to base station 1200 during downlink beam sweeps. The resource assignment and scheduling circuitry 1242 may be further configured to execute resource assignment and scheduling software 1252 stored in the computer-readable medium 1206 to implement one or more of the functions described herein.

The processor 1204 may further include communication and processing circuitry 1244 configured to communicate with UEs. In some examples, communication and processing circuitry 1244 may include one or more hardware components that provide a physical structure for performing processes related to wireless communication (e.g., signal reception and/or signal transmission) and signal processing (e.g., processing a received signal and/or processing a signal for transmission). In some examples, the communication and processing circuitry 1244 may be configured to generate and transmit downlink signals at millimeter wave frequencies or sub-6 GHz frequencies via the transceiver 1210 and the antenna array module(s) 1220. Further, the communication and processing circuitry 1244 may be configured to receive and process uplink signals at millimeter wave frequencies or sub-6 GHz frequencies via the antenna array module(s) 1220 and transceiver 1210.

For example, the communication and processing circuitry 1244 may be configured to generate and transmit a respective reference signal (e.g., an SSB or CSI-RS) to the UE on each of a plurality of downlink beams during a beam sweep. Additionally, the communication and processing circuitry 1244 may be configured to receive beam measurement reports from the UEs that include RSRPs measured on each of the plurality of downlink beams. The communication and processing circuitry 1244 may be further configured to receive a respective uplink reference signal (e.g., RACH message or SRS) on each of a plurality of uplink beams from the UE.

The communications and processing circuitry 1244 may be further configured to transmit a CSI-RS to the UE and receive Channel State Feedback (CSF)1218 from the UE in response to the CSI-RS. The CSF may include, for example, a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), and a Rank Indicator (RI). In some examples, communication and processing circuitry 1244 may store CSF 1218 in memory 1205 for further processing. Additionally, the communication and processing circuitry 1244 may be configured to implement a HARQ feedback mechanism to receive ACK/NACKs from the UEs. The communication and processing circuitry 1244 may be further configured to execute communication and processing software 1254 stored on the computer-readable medium 1206 to implement one or more functions described herein.

Processor 1204 may further include beam management circuitry 1246 configured to communicate with the UE (e.g., in conjunction with communication and processing circuitry 1244). The communication may utilize a first downlink beam of the plurality of downlink beams. Beam management circuitry 1246 may be further configured to process beam measurement reports 1215 received from the UEs (e.g., via communications and processing circuitry 1244). A Beam Measurement Report (BMR)1215 may include the measured RSRP for each of a plurality of downlink beams. In addition, the BMR 1215 may be further stored in the memory 1205 for further processing. The beam management circuitry 1246 may be configured to switch from a first downlink beam to a second downlink beam of the plurality of downlink beams for communicating with the UE based on the respective RSRP measured for each of the plurality of downlink beams. For example, the second downlink beam may have a higher RSRP than the first downlink beam. In some examples, the second downlink beam corresponds to the downlink beam with the highest measured RSRP. The beam management circuitry 1246 may be further configured to calculate a difference between a first measured RSRP associated with the first downlink beam and a second measured RSRP associated with the second downlink beam from the beam measurement report 1215.

The beam management circuitry 1246 may be further configured to receive (e.g., in conjunction with the communication and processing circuitry 1244) a respective uplink reference signal on each of a plurality of uplink beams from the UE. Beam management circuitry 1246 may be further configured to perform signal quality measurements on the uplink beam reference signals to identify uplink beams on which the UE should transmit control information and/or user data traffic to base station 1200. Examples of signal quality measurements may include, but are not limited to, received power or signal-to-noise ratio (SNR). In the example of channel reciprocity, beam management circuitry 1246 may switch from a first downlink beam to a second downlink beam based on a signal quality measurement of a corresponding uplink beam. In this example, beam management circuitry 1246 may estimate a difference between a first RSRP for the first downlink beam and a second RSRP for the second downlink beam based on respective signal quality measurements for the first uplink beam corresponding to the first downlink beam and the second uplink beam corresponding to the second downlink beam. Beam management circuitry 1246 may be further configured to execute beam management software 1256 stored in computer-readable medium 1206 to implement one or more functions described herein.

Processor 1204 may further include MCS selection circuitry 1248 configured to select an MCS for a unicast downlink transmission to the UE. In some examples, MCS selection circuitry 1248 may select an MCS for downlink transmission to the UE with the first beam and then modify the MCS for downlink transmission to the UE with the second beam based on a difference between the first RSRP (associated with the first beam) and the second RSRP (associated with the second beam) determined by beam management circuitry 1246. MCS selection circuitry 1248 may modify the MCS used for the downlink transmission to the UE on the second beam before transmitting unicast downlink control information and/or user data traffic to the UE on the second beam. In some examples, different MCSs may be used for control information and user data communications. MCS selection circuitry 1248 may be further configured to execute MCS selection software 1258 stored in computer-readable medium 1206 to implement one or more functions described herein.

The processor 1204 may further include link adaptation circuitry 1250 configured to further adjust the MCS after selecting the MCS for the second beam based on an RSRP difference between the first and second beams. In some examples, the link adaptation circuitry 1250 may utilize an outer loop link adaptation process to adjust the MCS. For example, link adaptation circuitry 1250 may be configured to adjust the MCS based on acknowledgement information (e.g., ACKs and NACKs) received from the UE. In other examples, the link adaptation circuitry 1250 may adjust the MCS using the CSF 1218 received from the UE in response to the CSI-RS transmitted by the base station 1200 on the second beam. For example, link adaptation circuitry 1250 may adjust the MCS based on the CQI in CSF 1218. In adjusting the MCS based on the CQI, the link adaptation circuitry 1250 may further utilize an outer loop link adaptation process to further adjust the MCS as needed until another CSI-RS is transmitted to the UE on the second beam. The link adaptation circuitry 1250 may be further configured to execute link adaptation software 1260 stored on the computer-readable medium 1206 to implement one or more of the functions described herein.

Fig. 13 is a flow diagram 1300 of a method for a base station to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the base station 1200 as described above and illustrated in fig. 12, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1302, a base station may communicate with a UE using a first downlink beam of a plurality of downlink beams. The downlink beam may be, for example, a millimeter wave or sub-6 GHz beam. For example, the communication and processing circuitry 1244 and beam management circuitry 1246 shown and described above in connection with fig. 12 may communicate with the UE using the first downlink beam.

At block 1304, the base station may switch from a first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. In some examples, the base station may switch to the second downlink beam based on a difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. For example, the base station may calculate an RSRP difference based on a beam measurement report including a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. As another example, the base station may estimate an RSRP difference between the first and second downlink beams based on uplink signal quality measurements of the corresponding first and second uplink beams. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may determine an RSRP difference between the first and second downlink beams and switch to the second downlink beam based on the RSRP difference.

At block 1306, the base station may modify an MCS for communicating with the UE based on a difference between the first RSRP and the second RSRP. The modified MCS may be used to communicate with the UE on the second beam immediately after the switch from the first beam to the second beam (e.g., in the first slot after the switch). For example, MCS selection circuitry 1248 shown and described above in connection with fig. 12 may modify the MCS.

Fig. 14 is a flow diagram 1400 of a method for a base station to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the base station 1200 as described above and illustrated in fig. 12, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1402, a base station may communicate with a UE using a first downlink beam of a plurality of downlink beams. The downlink beam may be, for example, a millimeter wave or sub-6 GHz beam. For example, the communication and processing circuitry 1244 and beam management circuitry 1246 shown and described above in connection with fig. 12 may communicate with the UE using the first downlink beam.

At block 1404, the base station may receive a beam measurement report from the UE. The beam measurement report may include a respective RSRP measured on each of a plurality of downlink beams during a beam sweep performed by the base station. In particular, the beam measurement report may comprise a first RSRP of the first beam and a second RSRP of the second beam, wherein the second RSRP may be higher than the first RSRP. In some examples, the second RSRP may be the highest RSRP of all downlink beams. For example, beam management circuitry 1246 and communication and processing circuitry 1244 shown and described above in connection with fig. 12 may receive beam measurement reports.

At block 1406, the base station may switch from the first downlink beam to a second downlink beam to communicate with the UE based on a difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam of the plurality of downlink beams. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may determine an RSRP difference between the first and second downlink beams and switch to the second downlink beam based on the RSRP difference.

At block 1408, the base station may modify an MCS for communicating with the UE based on a difference between the first RSRP and the second RSRP. The modified MCS may be used to communicate with the UE on the second beam immediately after the switch from the first beam to the second beam (e.g., in the first slot after the switch). For example, MCS selection circuitry 1248 shown and described above in connection with fig. 12 may modify the MCS.

Fig. 15 is a flow diagram 1500 of a method for a base station to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the base station 1200 as described above and illustrated in fig. 12, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1502, a base station may communicate with a UE using a first downlink beam of a plurality of downlink beams. The downlink beam may be, for example, a millimeter wave or sub-6 GHz beam. For example, the communication and processing circuitry 1244 and beam management circuitry 1246 shown and described above in connection with fig. 12 may communicate with the UE using the first downlink beam.

At block 1504, when the channel is reciprocal, the base station may estimate a difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam based on respective uplink signal quality measurements of a first uplink beam corresponding to the first downlink beam and a second uplink beam corresponding to the second downlink beam of the plurality of downlink beams. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may estimate the RSRP difference.

At block 1506, the base station may switch from the first downlink beam to a second downlink beam of the plurality of downlink beams. The handover may enable the BS to communicate with the UE based on an estimated difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may switch to a second downlink beam based on the RSRP difference.

At block 1508, the base station may modify an MCS used to communicate with the UE based on a difference between the first RSRP and the second RSRP. The modified MCS may be used to communicate with the UE on the second beam immediately after the switch from the first beam to the second beam (e.g., in the first slot after the switch). For example, MCS selection circuitry 1248 shown and described above in connection with fig. 12 may modify the MCS.

Fig. 16 is a flow diagram 1600 of a method for a base station to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the base station 1200 as described above and illustrated in fig. 12, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1602, the base station may communicate with the UE using a first downlink beam of the plurality of downlink beams. The downlink beam may be, for example, a millimeter wave or sub-6 GHz beam. For example, the communication and processing circuitry 1244 and beam management circuitry 1246 shown and described above in connection with fig. 12 may communicate with the UE using the first downlink beam.

At block 1604, the base station may switch from the first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. In some examples, the base station may switch to the second downlink beam based on a difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. For example, the base station may calculate an RSRP difference based on a beam measurement report including a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. As another example, the base station may estimate an RSRP difference between the first and second downlink beams based on uplink signal quality measurements of the corresponding first and second uplink beams. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may determine an RSRP difference between the first and second downlink beams and switch to the second downlink beam based on the RSRP difference.

At block 1606, the base station may modify an MCS for communicating with the UE based on a difference between the first RSRP and the second RSRP. The modified MCS may be used to communicate with the UE on the second beam immediately after the switch from the first beam to the second beam (e.g., in the first slot after the switch). For example, MCS selection circuitry 1248 shown and described above in connection with fig. 12 may modify the MCS.

At block 1608, the base station may further adjust the MCS using an outer loop link adaptation procedure. For example, the base station may be configured to adjust the MCS based on HARQ feedback (e.g., ACKs and NACKs) received from the UE. For example, the link adaptation circuitry 1250 shown and described above in connection with fig. 12 may further adjust the MCS after modifying the MCS based on the RSRP difference value.

Fig. 17 is a flow diagram 1700 of a method for a base station to minimize BLER associated with beam switching. As described below, some or all of the illustrated features may be omitted in particular implementations within the scope of the present disclosure, and some of the illustrated features may not be required to implement all embodiments. In some examples, the method may be performed by the base station 1200 as described above and illustrated in fig. 12, by a processor or processing system, or by any suitable means for performing the described functions.

At block 1702, a base station may communicate with a UE using a first downlink beam of a plurality of downlink beams. The downlink beam may be, for example, a millimeter wave or sub-6 GHz beam. For example, the communication and processing circuitry 1244 and beam management circuitry 1246 shown and described above in connection with fig. 12 may communicate with the UE using the first downlink beam.

At block 1704, the base station may switch from a first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE. In some examples, the base station may switch to the second downlink beam based on a difference between a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. For example, the base station may calculate an RSRP difference based on a beam measurement report including a first RSRP associated with the first downlink beam and a second RSRP associated with the second downlink beam. As another example, the base station may estimate an RSRP difference between the first and second downlink beams based on uplink signal quality measurements of the corresponding first and second uplink beams. For example, beam management circuitry 1246 shown and described above in connection with fig. 12 may determine an RSRP difference between the first and second downlink beams and switch to the second downlink beam based on the RSRP difference.

At block 1706, the base station may modify an MCS used to communicate with the UE based on a difference between the first RSRP and the second RSRP. The modified MCS may be used to communicate with the UE on the second beam immediately after the switch from the first beam to the second beam (e.g., in the first slot after the switch). For example, MCS selection circuitry 1248 shown and described above in connection with fig. 12 may modify the MCS.

At block 1708, the base station may transmit CSI-RS to the UE via the second downlink beam. For example, the communication and processing circuitry 1244 shown and described above in connection with fig. 12, along with the transceiver 1210, may transmit CSI-RS to the UE on the second beam.

At block 1710, the base station may receive a CSF from the UE based on the CSI-RS. For example, the communication and processing circuitry 1244 shown and described above in connection with fig. 12, along with the transceiver 1210, may receive CSF.

At block 1712, the base station may further adjust the MCS based on the CSF. For example, the base station may be configured to adjust the MCS based on the CQI included in the CSF. For example, the link adaptation circuitry 1250 shown and described above in connection with fig. 12 may further adjust the MCS after modifying the MCS based on the RSRP difference value.

In one configuration, a base station includes means for communicating with a User Equipment (UE) utilizing a first downlink beam of a plurality of downlink beams; means for switching from a first downlink beam of the plurality of downlink beams to a second downlink beam of the plurality of downlink beams to communicate with the UE based on a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam; and means for modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on the difference between the first RSRP and the second RSRP.

In one aspect, the aforementioned means for communicating with a User Equipment (UE) utilizing a first downlink beam of a plurality of downlink beams, means for switching from a first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE based on a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam, means for modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on the difference between the first RSRP and the second RSRP may be the processor 1204 shown in fig. 12 configured to perform the functions recited by the aforementioned means. For example, the aforementioned means for communicating with a User Equipment (UE) utilizing a first downlink beam of the plurality of downlink beams may comprise the communication and processing circuitry 1244, beam management circuitry 1246, transceiver 1210, and antenna array 1220 shown in fig. 12. As another example, the aforementioned means for switching from a first downlink beam to a second downlink beam of the plurality of downlink beams to communicate with the UE based on a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam may comprise beam management circuitry 1246 shown in fig. 12. In another example, the aforementioned means for modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on a difference between the first RSRP and the second RSRP may comprise MCS selection circuitry 1248 and link adaptation circuitry 1250 shown in fig. 12. In another aspect, the aforementioned means may be circuitry or any device configured to perform the functions recited by the aforementioned means.

Several aspects of a wireless communication network have been presented with reference to exemplary implementations. As those skilled in the art will readily appreciate, the various aspects described throughout this disclosure may be extended to other telecommunications systems, network architectures, and communication standards.

By way of example, the various aspects may be implemented within other systems defined by 3GPP, such as Long Term Evolution (LTE), Evolved Packet System (EPS), Universal Mobile Telecommunications System (UMTS), and/or Global System for Mobile (GSM). Various aspects may also be extended to systems defined by third generation partnership project 2(3GPP2), such as CDMA2000 and/or evolution-data optimized (EV-DO). Other examples may be implemented within systems employing IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Ultra Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunications standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

Within this disclosure, the word "exemplary" is used to mean "serving as an example, instance, or illustration. Any implementation or aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term "aspect" does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term "coupled" is used herein to refer to a direct or indirect coupling between two objects. For example, if object a physically contacts object B, and object B contacts object C, objects a and C may still be considered to be coupled to each other even though they are not in direct physical contact with each other. For example, a first object may be coupled to a second object even though the first object is never in direct physical contact with the second object. The terms "circuitry" and "circuitry" are used broadly and are intended to include both hardware implementations of electronic devices and conductors that when connected and configured enable the functions described in this disclosure to be performed, without limitation as to the type of electronic circuitry, and software implementations of information and instructions that when executed by a processor enable the functions described in this disclosure to be performed.

One or more of the components, steps, features and/or functions illustrated in fig. 1-17 may be rearranged and/or combined into a single component, step, feature or function or implemented in several components, steps or functions. Additional elements, components, steps, and/or functions may also be added without departing from the novel features disclosed herein. The apparatuses, devices, and/or components illustrated in fig. 1, 2, 4-8, 11, and 12 may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited herein.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. The term "some" or "an" refers to one or more, unless specifically stated otherwise. A phrase referring to "at least one of a list of items" refers to any combination of these items, including a single member. By way of example, "at least one of a, b, or c" is intended to encompass: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

1. A method for wireless communications at a base station in a wireless communications network, the method comprising:

communicate with a User Equipment (UE) using a first downlink beam of a plurality of downlink beams;

switching from a first downlink beam of the plurality of downlink beams to a second downlink beam of the plurality of downlink beams to communicate with the UE based on a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam; and

modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on the difference between the first RSRP and the second RSRP.

2. The method of claim 1, further comprising:

receiving at least one beam measurement report from the UE, wherein the first RSRP and the second RSRP are each included in one of the at least one beam measurement report; and

calculating the difference between the first RSRP and the second RSRP based on the at least one beam measurement report.

3. The method of claim 1, further comprising:

estimating the difference between the first RSRP and the second RSRP based on respective signal quality measurements of a first uplink beam corresponding to the first downlink beam and a second uplink beam corresponding to the second downlink beam.

4. The method of claim 1, wherein modifying the MCS further comprises:

adjusting the MCS using an outer loop link adaptation procedure.

5. The method of claim 4, further comprising:

receiving acknowledgement information from the UE; and

adjusting the MCS based on the acknowledgement information.

6. The method of claim 1, wherein modifying the MCS further comprises:

transmitting a channel state information-reference signal (CSI-RS) to the UE via the second beam;

receiving channel state information feedback (CSF) from the UE; and

adjusting the MCS based on the CSF.

7. The method of claim 1, wherein the first downlink beam comprises a first beam width and the second downlink beam comprises a second beam width, wherein the second beam width is different from the first beam width.

8. The method of claim 1, wherein communicating with the UE further comprises:

communicating with the UE using a millimeter wave carrier frequency.

9. A base station in a wireless communication network, comprising:

a wireless transceiver;

a memory; and

a processor communicatively coupled to the wireless transceiver and the memory, wherein the processor is configured to:

communicate with a User Equipment (UE) with a first downlink beam of a plurality of downlink beams via the wireless transceiver;

10. The base station of claim 9, wherein the processor is further configured to:

receiving, via the wireless transceiver, at least one beam measurement report from the UE, wherein the first RSRP and the second RSRP are each included in one of the at least one beam measurement report; and

11. The base station of claim 9, wherein the processor is further configured to:

12. The base station of claim 9, wherein the processor is further configured to:

adjusting the MCS using an outer loop link adaptation procedure.

13. The base station of claim 12, wherein the processor is further configured to:

receiving acknowledgement information from the UE; and

adjusting the MCS based on the acknowledgement information.

14. The base station of claim 9, wherein the processor is further configured to:

receiving channel state information feedback (CSF) from the UE; and

adjusting the MCS based on the CSF.

15. The base station of claim 9, wherein the first downlink beam comprises a first beam width and the second downlink beam comprises a second beam width, wherein the second beam width is different from the first beam width.

16. The base station of claim 9, wherein the processor is further configured to:

communicating with the UE via the wireless transceiver using a millimeter wave carrier frequency.

17. A base station in a wireless communication network, comprising:

means for communicating with a User Equipment (UE) utilizing a first downlink beam of a plurality of downlink beams;

means for switching from a first downlink beam of the plurality of downlink beams to a second downlink beam of the plurality of downlink beams to communicate with the UE based on a difference between a first Reference Signal Received Power (RSRP) associated with the first downlink beam and a second RSRP associated with the second downlink beam; and

means for modifying a Modulation and Coding Scheme (MCS) for communicating with the UE based on the difference between the first RSRP and the second RSRP.

18. The base station of claim 17, further comprising:

means for receiving at least one beam measurement report from the UE, wherein the first RSRP and the second RSRP are each included in one of the at least one beam measurement report; and

means for calculating the difference between the first RSRP and the second RSRP based on the at least one beam measurement report.

19. The base station of claim 17, further comprising:

means for estimating the difference between the first RSRP and the second RSRP based on respective signal quality measurements of a first uplink beam corresponding to the first downlink beam and a second uplink beam corresponding to the second downlink beam.

20. The base station of claim 17, wherein means for modifying the MCS further comprises:

means for adjusting the MCS using an outer loop link adaptation procedure.

21. The base station of claim 20, wherein means for modifying the MCS further comprises:

means for receiving acknowledgement information from the UE; and

means for adjusting the MCS based on the acknowledgement information.

22. The base station of claim 17, wherein means for modifying the MCS further comprises:

means for transmitting a channel state information-reference signal (CSI-RS) to the UE via the second beam;

means for receiving channel state information feedback (CSF) from the UE; and

means for adjusting the MCS based on the CSF.

23. The base station of claim 17, wherein the first downlink beam comprises a first beam width and the second downlink beam comprises a second beam width, wherein the second beam width is different from the first beam width.

24. The base station of claim 17, wherein means for communicating with the UE further comprises:

means for communicating with the UE using a millimeter wave carrier frequency.

25. A non-transitory computer-readable medium storing computer-executable code, comprising code for causing a base station to:

26. The non-transitory computer-readable medium of claim 25, further comprising code for causing the base station to:

27. The non-transitory computer-readable medium of claim 25, further comprising code for causing the base station to:

28. The non-transitory computer-readable medium of claim 26, further comprising code for causing the base station to:

adjusting the MCS using an outer loop link adaptation procedure.

29. The non-transitory computer-readable medium of claim 28, further comprising code for causing the base station to:

receiving acknowledgement information from the UE; and

adjusting the MCS based on the acknowledgement information.

30. The non-transitory computer-readable medium of claim 25, further comprising code for causing the base station to:

receiving channel state information feedback (CSF) from the UE; and

adjusting the MCS based on the CSF.