Terminal receiving beam management method and device

Abstract

A user equipment, method and computer readable medium. A UE including a transceiver having multiple antenna panels is configured to determine a link quality of a serving antenna panel. If the link quality of the serving panel is below a quality threshold, resources are allocated from the serving antenna panel to another antenna panel during a scanning period to identify one or more beams of a target antenna panel to resume communication. During the scanning period, measurements of a set of beams of another antenna panel are obtained using the allocated resources. Based on the obtained measurements, it can be determined that the other antenna panel is a target antenna panel. The UE can switch from the serving antenna panel to the target antenna panel, select one or more beams based on the obtained measurements, and resume communication on the selected one or more beams.

Description

Technical Field

[0001] The present disclosure relates to pre-fifth generation (5G) or 5G communication systems, such as Long Term Evolution (LTE), provided to support higher data rates beyond fourth generation (4G) communication systems. More specifically, the present disclosure is directed to beam management in a mobile terminal having multiple antenna panels. Background Art

[0002] The communication system includes a downlink (DL) that transmits signals from a transmission point such as a base station (BS) or eNodeB to a user equipment (UE) and an uplink (UL) that transmits signals from the UE to a receiving point such as an eNodeB. The communication system may be a millimeter wave (mmWave) wireless communication system. The UE, also commonly referred to as a terminal or mobile station, may be fixed or mobile and may be a cellular phone, a personal computer device, etc. In addition, the UE may include a multi-panel antenna for communication. The eNodeB, which is typically a fixed station, may also be referred to as an access point or other equivalent terms. Summary of the invention

[0003]

Technical issues

[0004] The BS transmit power may be significantly greater than the UE transmit power, resulting in the BS received signal strength being significantly lower than the UE received signal strength. The asymmetry of the UL and DL link budgets will limit the UE's radio coverage.

[0005] Due to link blocking, link failure, channel condition changes and other design constraints, the BS or network may have to switch or change the transmission configuration indicator (TCI) state to maintain good link quality. In some cases, the switching or changing of the TCI state may result in the switching or changing of the transmit beam at the BS. Upon receiving the TCI state switching command from the network through higher layer signaling, the UE may also need to change the receive beam used.

[0006]

Problem Solution

[0007] Embodiments of the present disclosure include user equipment (UE), methods, and non-transitory computer-readable media for beam management of multiple antenna panels. One embodiment is directed to a UE, the UE including a transceiver and a processor, the transceiver including multiple antenna panels, the processor operably connected to the transceiver. The processor is configured to determine the link quality of the serving antenna panel; in response to determining that the link quality of the serving antenna panel is below a quality threshold, allocate resources from the serving antenna panel to another antenna panel of the multiple antenna panels during a scanning period to identify one or more beams of the target antenna panel to restore communication; using the allocated resources, obtain a measurement of a set of beams of another antenna panel during the scanning period; determine that the other antenna panel is a target antenna panel based on the obtained measurements; switch from the serving antenna panel to the target antenna panel; select one or more beams from the group of beams based on the obtained measurements; and restore communication on the selected one or more beams via the target antenna panel.

[0008] Another embodiment is directed to a method comprising the following steps: determining a link quality of a serving antenna panel; in response to determining that the link quality of the serving antenna panel is below a quality threshold, allocating resources from the serving antenna panel to another antenna panel among a plurality of antenna panels during a scanning period to identify one or more beams of a target antenna panel to restore communication; obtaining measurements of a set of beams of another antenna panel during the scanning period using the allocated resources; determining that the other antenna panel is a target antenna panel based on the obtained measurements; switching from the serving antenna panel to the target antenna panel; selecting one or more beams from the group of beams based on the obtained measurements; and restoring communication on the selected one or more beams via the target antenna panel.

[0009] Yet another embodiment relates to a non-transitory computer-readable medium comprising instructions which, when executed by a processor of an electronic device, are configured to cause the electronic device to: determine a link quality of a serving antenna panel; in response to determining that the link quality of the serving antenna panel is below a quality threshold, allocate resources from the serving antenna panel to another antenna panel of a plurality of antenna panels during a scanning period to identify one or more beams of a target antenna panel to restore communication; obtain measurements of a set of beams of another antenna panel during the scanning period using the allocated resources; determine that the other antenna panel is a target antenna panel based on the obtained measurements; switch from the serving antenna panel to the target antenna panel; select one or more beams from the set of beams based on the obtained measurements; and restore communication on the selected one or more beams via the target antenna panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, in which:

[0011] Figure 1 An exemplary networked computing system according to various embodiments of the present disclosure is shown;

[0012] Figure 2 An exemplary base station (BS) in a networked computing system according to various embodiments of the present disclosure is shown;

[0013] Figure 3 An exemplary user equipment (UE) in a networked computing system according to various embodiments of the present disclosure is shown;

[0014] Figure 4 An exemplary millimeter wave communication system according to various embodiments of the present disclosure is shown;

[0015] Figure 5 A beam management process between a BS and a UE according to various embodiments of the present disclosure is shown;

[0016] Figure 6 A communication module having multiple antenna panels according to various embodiments of the present disclosure is shown;

[0017] Figure 7 A flow chart for allocating resources to another antenna panel during a scan cycle of a serving antenna panel according to various embodiments of the present disclosure is shown;

[0018] Fig. 8A A timeline showing switching between a serving antenna panel and a target antenna panel is shown;

[0019] Figure 8B illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0020] Fig. 9 A flowchart of updating a beam measurement table based on a reordered beam according to various embodiments of the present disclosure is shown;

[0021] Fig. 10A A timeline showing switching between a serving antenna panel and a target antenna panel is shown;

[0022] Fig. 10B illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0023] Fig.11 A flowchart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure is shown;

[0024] Fig.12 Another flow chart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure is shown;

[0025] Fig.13 Another flow chart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure is shown;

[0026] Fig.14 A flow chart showing updating a beam management table using a narrow beam of an optimal wide beam according to various embodiments of the present disclosure is shown;

[0027] Fig.15A shows the beam structure of the antenna module;

[0028] Fig. 15B shows a hierarchical structure for updating a beam measurement table according to various embodiments of the present disclosure;

[0029] Fig.16 illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0030] Fig.17 A flowchart for updating a beam measurement table according to various embodiments of the present disclosure is shown;

[0031] Fig.18 illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0032] Fig.19 Another flow chart for updating a beam measurement table according to various embodiments of the present disclosure is shown;

[0033] Fig. 20 illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0034] Fig.21 A flow chart for switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure is shown;

[0035] Fig.22A A switching timeline between a serving antenna panel and a target antenna panel is shown;

[0036] Fig. 22B illustrates a timeline of switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure;

[0037] Fig.23 shows unknown TCI state switching according to various embodiments of the present disclosure;

[0038] Fig.24shows a comparison of a receive beam search over the entire angular space and a receive beam search over a restricted area according to various embodiments of the present disclosure;

[0039] Fig.25A A flowchart of a receive beam search for TCI state switching according to various embodiments of the present disclosure is shown;

[0040] Fig.25B Another flow chart of receive beam search for TCI state switching according to various embodiments of the present disclosure is shown;

[0041] Fig.26 A process for MAC CE-enabled TCI status indication for PDCCH according to various embodiments of the present disclosure is shown;

[0042] Fig.27A and 27B A flowchart showing beam selection and corresponding receive beams according to various embodiments of the present disclosure is shown;

[0043] Fig.28 shows examples of selected beams according to various embodiments of the present disclosure;

[0044] Fig.29 Various modes of candidate beams according to various embodiments of the present disclosure are shown;

[0045] Fig.30 A flowchart of receiving beam selection under TCI state switching according to various embodiments of the present disclosure is shown;

[0046] Fig.31 shows candidate beams in a first group and a second group according to various embodiments of the present disclosure;

[0047] Fig.32 Various types of candidate beams according to various embodiments of the present disclosure are shown;

[0048] Fig.33 A flowchart of receiving beam selection under TCI state switching according to various embodiments of the present disclosure is shown;

[0049] Fig.34 shows corresponding candidate beam selection according to various embodiments of the present disclosure;

[0050] Fig.35A and 35B A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0051] Fig.36 A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0052] Fig.37 A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0053] Fig.38 A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0054] Fig.39A and 39B A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0055] Fig.40 A flowchart of receive beam selection according to various embodiments of the present disclosure is shown;

[0056] Fig.41 A conceptual example of selecting candidate beams for a fifth group of beams and a sixth group of beams according to various embodiments of the present disclosure is shown;

[0057] Fig.42 shows the asymmetry of downlink and uplink link budget limitations of UE radio coverage according to various embodiments of the present disclosure;

[0058] Fig.43 A flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0059] Fig.44 Another flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0060] Fig.45 Another flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0061] Fig.46 A flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0062] Fig.47 A flowchart showing switching between type 1 and type 2 transmit beams based on signal strength or quality according to various embodiments of the present disclosure;

[0063] Fig.48 A flowchart showing switching between type 1 and type 2 transmit beams based on a modulation and coding scheme of a PUSCH according to various embodiments of the present disclosure is shown;

[0064] Fig.49 Another flow chart illustrating switching between type 1 and type 2 transmit beams based on signal strength or quality according to various embodiments of the present disclosure;

[0065] Fig.50 Another flow chart showing switching between type 1 and type 2 transmit beams based on a modulation and coding scheme for a PUSCH according to various embodiments of the present disclosure;

[0066] Fig.51 A flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0067] Fig.52 A flow chart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown;

[0068] Fig.53 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown; and

[0069] Fig.54 A flow chart for managing beams among multiple antenna panels according to various embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0070] The drawings and various embodiments used to describe the principles of the present disclosure are merely exemplary and should not be interpreted in any way as limiting the scope of the present disclosure. In addition, those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged wireless communication system.

[0071] The UE may include a communication module having multiple antenna panels that cover different angular spaces using directional beam groups. Each antenna panel is associated with its own L1-RSRP measurement table, which is maintained and updated at the UE. Before communicating with any beam on any antenna panel, the UE reports the L1-RSRP value to the BS for beam selection. However, the measurement values ​​in the L1-RSRP measurement table may be outdated, resulting in undesirable beam selection. Performing beam measurements at antenna panel switching boundaries can result in measurement delays, which can also result in link interruptions. Therefore, some novel aspects of the present disclosure are directed to beam management of multi-panel antennas, which improves the severity of link interruptions at antenna switching boundaries.

[0072] In a millimeter wave system based on directional beamforming, in order to optimize a certain performance metric (e.g., received signal power), the UE typically performs an exhaustive search for all candidate beam codewords in the beam codebook and selects the codeword that results in the best performance metric (e.g., highest received signal power) to receive the data packet. If the number of candidate beam codewords in the beam codebook is large, the exhaustive search may take a very long time to converge, resulting in a large delay in the UE connecting to the network. An exhaustive search may be necessary during an unknown TCI state switch. According to the definition in 3GPP TS 38.133, if (i) the UE has previously reported a measurement of the target TCI state to the network at least once, (ii) the last measurement of the target TCI state reported by the UE is no more than a predetermined amount of time, for example, X ms ago, and (iii) during the TCI state switch, the SNR of the target TCI state is higher than a predetermined threshold Th_0, for example, Th_0 = -3dB, then the UE is considered to know the TCI state. If any of the above conditions is true, the target TCI state is considered to be unknown to the UE. If the switched TCI state is unknown to the UE, the UE may have to perform a brute force search on all candidate beam codewords in the beam codebook to find the receive beam and thus re-establish the communication link. If the beam codebook size is large, the interested UE may experience significant interruption during the unknown TCI state switch. Therefore, at least some novel aspects of the present disclosure recognize the need to implement new effective and efficient receive beam selection / operation strategies at the mobile terminal to facilitate the overall receive beam selection process under unknown TCI state switching.

[0073] To communicate with the BS, the UE may search all candidate beam codewords in the beam codebook and select one or more codewords that result in the best performance metric (e.g., the highest received signal power). The beam codebook may include beams of different beam widths. For ease of description, the present disclosure only considers two types of beams in the codebook, namely, wide beams (type 1) and narrow beams (type 2). However, the novel aspects of the present disclosure may also be applied to beam codebooks with more than two types. In general, wider beams have lower beam gains, but less frequent beam updates may be required when channel conditions change; while narrower beams have higher beam gains, but more frequent beam updates may be required when channel conditions change.

[0074] The base station transmit power can be much larger than the terminal transmit power (e.g., 20 dB). As a result, the received signal strength at the base station may be significantly lower than the received signal at the terminal. Under certain conditions, such as when the UE is at or near the cell edge, although the downlink signal strength is sufficient to support the minimum downlink data rate, the uplink signal strength may not be sufficient to support the minimum uplink data rate. This asymmetry of the downlink and uplink link budgets limits the radio coverage of the UE. The novel aspects of the present disclosure recognize that the asymmetry of the downlink and uplink link budgets limits the radio coverage of the UE, and that the asymmetry of the downlink and uplink link budgets can be mitigated by having the UE use a wide Rx beam to receive downlink signals and a narrow Tx beam to send uplink signals, because the narrow Tx beam has a higher beam gain than the wide Rx beam.

[0075] Figure 1 An exemplary networked computing system is shown in accordance with various embodiments of the present disclosure. Figure 1 The embodiment of the wireless network 100 shown is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0076] like Figure 1 As shown, wireless network 100 includes gNodeB (gNB) 101, gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. gNB 101 also communicates with at least one Internet Protocol (IP) network 130, such as the Internet, a private IP network, or other data network.

[0077] gNB 102 provides wireless broadband access to network 130 for a first plurality of user equipment (UE) within coverage area 120 of gNB 102. The first plurality of UEs include: UE 111, which may be located in a small business; UE 112, which may be located in an enterprise (E); UE 113, which may be located in a WiFi hotspot (HS); UE 114, which may be located in a first residence (R); UE 115, which may be located in a second residence (R); and UE 116, which may be a mobile device (M) such as a cellular phone, a wireless laptop, a wireless PDA, etc. gNB 103 provides wireless broadband access to network 130 for a second plurality of UEs within coverage area 125 of gNB 103. The second plurality of UEs includes UE 115 and UE 116. In some embodiments, one or more gNBs 101-103 may communicate with each other and with UEs 111-116 using 5G, LTE, LTE-A, WiMAX, WiFi, or other wireless communication technologies.

[0078] Depending on the network type, the term "base station" or "BS" may refer to any component (or collection of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmission-reception point (TRP), an enhanced base station (eNodeB or eNB or gNB), a macro cell, a femto cell, a WiFi access point (AP), or other wireless-enabled device. A base station may provide wireless access according to one or more wireless communication protocols, such as 5G 3GPP New Radio Interface / Access (NR), Long Term Evolution (LTE), Advanced LTE (LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to a network infrastructure component that provides wireless access to a remote terminal. In addition, depending on the network type, the term "user equipment" or "UE" may refer to any component, such as a "mobile station", "subscriber station", "remote terminal", "wireless terminal", "reception point", or "user equipment". For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered a fixed device (such as a desktop computer or vending machine).

[0079] Dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are shown as generally circular for purposes of illustration and explanation only. It should be clearly understood that coverage areas associated with a gNB, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles.

[0080] As described in more detail below, wireless network 100 may be a 5G communication system in which a UE such as UE 116 may manage a multi-panel antenna and / or select beams for UL / DL transmissions.

[0081] although Figure 1 One example of a wireless network 100 is shown, but may be Figure 1 Various changes may be made. For example, in any suitable arrangement, wireless network 100 may include any number of gNBs and any number of UEs. In addition, gNB 101 may communicate directly with any number of UEs and provide these UEs with wireless broadband access to network 130. Similarly, each gNB 102-103 may communicate directly with network 130 and provide the UEs with direct wireless broadband access to network 130. In addition, gNBs 101, 102, and / or 103 may provide access to other or additional external networks, such as an external telephone network or other type of data network.

[0082] Figure 2 An exemplary base station (BS) according to various embodiments of the present disclosure is shown. Figure 2 The embodiment of gNB 102 shown is for illustration only. Figure 1 gNBs 101 and 103 may have the same or similar configurations. However, gNBs have various configurations, and Figure 2 There is no intent to limit the scope of this disclosure to any particular implementation of a gNB.

[0083] like Figure 2 As shown, gNB 102 includes multiple antennas 280a-280n, multiple RF transceivers 282a-282n, transmit (TX) processing circuitry 284, and receive (RX) processing circuitry 286. gNB 102 also includes a controller / processor 288, a memory 290, and a backhaul or network interface 292.

[0084] The RF transceivers 282a-282n receive incoming RF signals from antennas 280a-280n, such as signals sent by UEs in the network 100. The RF transceivers 282a-282n down-convert the incoming RF signals to produce IF or baseband signals. The IF or baseband signals are sent to the RX processing circuit 286, which generates processed baseband signals by filtering, decoding and / or digitizing the baseband or IF signals. The RX processing circuit 286 sends the processed baseband signals to the controller / processor 288 for further processing.

[0085] The TX processing circuit 284 receives analog or digital data (e.g., voice data, network data, email, or interactive video game data) from the controller / processor 288. The TX processing circuit 284 encodes, multiplexes, and / or digitizes the output baseband data to generate processed baseband or IF signals. The RF transceivers 282a-282n receive the output processed baseband or IF signals from the TX processing circuit 284 and up-convert the baseband or IF signals to RF signals that are transmitted via the antennas 280a-280n.

[0086] The controller / processor 288 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 288 may control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 282a-282n, the RX processing circuitry 286, and the TX processing circuitry 284 in accordance with well-known principles. The controller / processor 288 may also support additional functionality, such as more advanced wireless communication functionality. For example, the controller / processor 288 may support beamforming or directional routing operations, in which the output signals from the multiple antennas 280a-280n are weighted differently to effectively direct the output signals in a desired direction. The controller / processor 288 may support any of a variety of other functions in the gNB 102. In some embodiments, the controller / processor 288 includes at least one microprocessor or microcontroller.

[0087] The controller / processor 288 is also capable of executing programs and other processes, such as a basic OS, that reside in the memory 290. The controller / processor 288 can move data into or out of the memory 290 as required by the executing process.

[0088] The controller / processor 288 is also coupled to a backhaul or network interface 292. The backhaul or network interface 292 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or network. The interface 292 can support communication over any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (e.g., a communication system supporting 5G, LTE, or LTE-A), the interface 292 can allow the gNB 102 to communicate with other gNBs via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 292 can allow the gNB 102 to communicate via a wired or wireless local area network or via a wired or wireless connection to a larger network (e.g., the Internet). The interface 292 includes any suitable structure that supports communication over a wired or wireless connection, such as an Ethernet or RF transceiver.

[0089] Memory 290 is coupled to controller / processor 288. A portion of memory 290 may include RAM and another portion of memory 290 may include flash memory or other ROM.

[0090] As described in more detail below, in some embodiments, UE management of multi-panel antennas and / or beam selection for UL / downlink transmissions can be based on signals sent and received from a BS such as gNB 102 and a UE.

[0091] although Figure 2 An example of a gNB 102 is shown, but the Figure 2For example, gNB 102 may include Figure 2 As a specific example, an access point may include multiple interfaces 292, and the controller / processor 288 may support routing functionality to route data between different network addresses. As another specific example, while shown as including a single instance of TX processing circuitry 284 and a single instance of RX processing circuitry 286, the gNB 102 may include multiple instances of each (e.g., one for each RF transceiver). In addition, Figure 2 The various components in may be combined, further subdivided, or omitted, and additional components may be added according to specific needs.

[0092] Figure 3 An exemplary user equipment (UE) according to various embodiments of the present disclosure is shown. Figure 3 The embodiment of UE 116 shown is for illustration only. Figure 1 UEs 111-115 may have the same or similar configurations. However, UEs have a variety of configurations, and Figure 3 The scope of the present disclosure is not limited to any particular implementation of a UE.

[0093] like Figure 3 As shown, UE 116 includes antenna 305, radio frequency (RF) transceiver 310, transmit (TX) processing circuit 315, microphone 320 and receive (RX) processing circuit 325. UE 116 also includes speaker 330, main processor 340, input / output (I / O) interface 345, keyboard 350, display 355 and memory 360. Memory 360 includes basic operating system (OS) program 361 and one or more application programs 362.

[0094] RF transceiver 310 receives an incoming RF signal from antenna 305 transmitted by a gNB of network 100. RF transceiver 310 downconverts the incoming RF signal to produce an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to RX processing circuitry 325, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. RX processing circuitry 325 sends the processed baseband signal to speaker 330 (e.g., for voice data) or host processor 340 for further processing (e.g., for web browsing data).

[0095] The TX processing circuit 315 receives analog or digital voice data from the microphone 320, or receives other output baseband data (e.g., network data, email, or interactive video game data) from the main processor 340. The TX processing circuit 315 encodes, multiplexes, and / or digitizes the output baseband data to generate a processed baseband or IF signal. The RF transceiver 310 receives the output processed baseband or IF signal from the TX processing circuit 315 and up-converts the baseband or IF signal to an RF signal that is transmitted through the antenna 305.

[0096] The main processor 340 may include one or more processors or other processing devices and execute a basic OS program 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the main processor 340 may control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceiver 310, the RX processing circuit 325, and the TX processing circuit 315 according to well-known principles. In some embodiments, the main processor 340 includes at least one microprocessor or microcontroller.

[0097] The main processor 340 is also capable of executing other processes and programs residing in the memory 360. The main processor 340 can move data into or out of the memory 360 as needed for the executing process. In some embodiments, the main processor 340 is configured to execute applications 362 based on the OS program 361 or in response to signals received from the gNB or operator. The main processor 340 is also coupled to the I / O interface 345, which provides the UE 116 with the ability to connect to other devices such as laptops and handheld computers. The I / O interface 345 is the communication path between these accessories and the main processor 340.

[0098] Main processor 340 is also coupled to keyboard 350 and display unit 355. An operator of UE 116 may enter data into UE 116 using keyboard 350. Display 355 may be a liquid crystal display or other display capable of presenting text and / or at least limited graphics, such as from a website.

[0099] Memory 360 is coupled to main processor 340. A portion of memory 360 may include random access memory (RAM) and another portion of memory 360 may include flash memory or other read-only memory (ROM).

[0100] As described in more detail below, a UE such as UE 116 may manage a multi-panel antenna and / or select beams for UL / DL transmissions.

[0101] although Figure 3 An example of UE 116 is shown, but the Figure 3 Make various changes. For example, Figure 3 The various components in the embodiment may be combined, further subdivided, or omitted, and additional components may be added as required. As a specific example, the main processor 340 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In addition, although Figure 3 The UE 116 is shown configured as a mobile phone or smartphone, but the UE may be configured to operate as other types of mobile or stationary devices.

[0102] Figure 4 An exemplary millimeter wave communication system according to various embodiments of the present disclosure is shown. The communication system 400 may be used in a system such as Figure 2 BS 102 of the BS and / or such as Figure 3 The method is implemented in the UE 116 of the UE.

[0103] For mmWave frequencies, the number of antenna elements can be large for a given form factor. However, due to hardware limitations (e.g., the feasibility of installing a large number of ADCs / DACs at mmWave frequencies), the number of digital chains is limited, e.g. Figure 4 As shown in Figure 1. In this case, a digital chain is mapped to a large number of antenna elements, which can be controlled by a set of analog phase shifters. A digital chain can correspond to a subarray that produces a narrow analog beam through analog beamforming. By changing the phase shifter set during the transmission time interval, the analog beam can be configured to sweep over a wider angle range.

[0104] A gNB can cover the entire area of ​​a cell with one or more transmit beams. The gNB can form the transmit beams by applying appropriate gain and phase settings to the antenna arrays. The transmit gain, i.e., the amplification of the transmit signal power provided by the transmit beam, is generally inversely proportional to the width or area covered by the beam. At lower carrier frequencies, more benign propagation losses may make it possible for the gNB to provide coverage with a single transmit beam, i.e., to ensure adequate received signal quality for all UE locations within the coverage area by using a single transmit beam. In other words, at lower transmit signal carrier frequencies, the transmit power amplification provided by a transmit beam that is wide enough to cover the area may be sufficient to overcome the propagation losses to ensure adequate received signal quality for all UE locations within the coverage area. However, at higher signal carrier frequencies, the transmit beam power amplification corresponding to the same coverage area may not be sufficient to overcome the higher propagation losses, resulting in a degradation in received signal quality at UE locations within the coverage area. To overcome this degradation in received signal quality, the gNB may form multiple transmit beams, each beam providing coverage over an area narrower than the entire coverage area, but providing transmit power amplification sufficient to overcome the higher signal propagation losses resulting from the use of a higher transmit signal carrier frequency. The UE can also form a receive beam to increase the signal-to-interference-and-noise ratio (SINR) at the receiver. Similarly, in the uplink, the UE can form a transmit beam and the gNB can form a receive beam.

[0105] To help the UE determine its RX and / or TX beams, a beam scanning process is employed, which involves the gNB sending a set of transmit beams to scan the cell area, and the UE uses its receive beams to measure the signal quality on different beams. To facilitate candidate beam identification, beam measurement, and beam quality reporting, the gNB configures the UE with one or more RS resources (e.g., SS blocks, periodic / aperiodic / semi-persistent CSI-RS resources or CRI) corresponding to a set of TX beams. RS resources refer to reference signal transmissions at one or more combinations of time (OFDM symbols) / frequency (resource elements) / space (antenna ports) domain locations. For each RX beam, the UE reports the different TX beams received using that RX beam, arranged in order of signal strength (RSRP) and optionally CSI (CQI / PMI / RI). Based on the UE's measurement report feedback, the gNB indicates to the UE one or more transmission configuration indicator (TCI) states for receiving PDCCH and / or PDSCH.

[0106] Beam management for multi-panel antennas

[0107] Figure 5The beam management process between a BS and a UE according to various embodiments of the present disclosure is shown. In a TX-RX period 502, data is transmitted between the BS 102 and the UE 116. Within the TX-RX period 502 is a synchronization signal (SS) period 504, during which the UE 116 forms a receive beam, such as BM#0_4 representing module index 0 and beam index 4 in module 0, measures from all SSB beams 506, such as all 64 SSB beams, and updates the corresponding entries of the L1-RSRP measurement table. At the end of each SS period 504, the UE 116 sends a report 508 indicating the maximum L1-RSRP from the L1-RSRP measurement table to the base station 102.

[0108] Based on the L1-RSRP report 508 from the UE 116, the base station 102 determines the best transmit beam / TCI state 510 for performing data communication. The base station 102 transmits the payload data using the selected best transmit beam 510 and completes the TX-RX cycle 502. The entire process may include many TX-RX cycles.

[0109] As described above, measurement delays, especially at antenna module switching boundaries, can cause outdated / outdated L1-RSRP information in the L1-RSRP measurement table, which can lead to inaccurate beam selection and severe link outages. Various embodiments disclosed herein reduce RSRP loss at module switching boundaries.

[0110] Figure 6 A communication module with multiple antenna panels according to various embodiments of the present disclosure is shown. The communication module 600a may be implemented in a UE, for example Figure 3 UE 116 in.

[0111] The communication module 600 includes a plurality of antenna panels 602, each of which covers a specific angular space using a set of directional beams 606. In this embodiment, the set of directional beams 606 includes seven beams, with beam 3 used as the boresight. Each antenna panel 602a, 602b, and 602c is connected to a communication processor 604. In one embodiment, the communication processor 604 is configured to control one antenna panel 602 at a time to measure and / or transmit data. As used herein, the term "antenna panel" can be used interchangeably with the term "antenna module".

[0112] Multiple L1-RSRP measurement tables can be maintained and updated on the terminal side, each corresponding to a given antenna panel 602. For a given time period, because only one antenna panel 602 can be enabled as a serving antenna panel, only one L1-RSRP measurement table can be updated at a time. If the link quality of the serving antenna panel drops below a given threshold, the corresponding UE can scan other antenna panels within a scanning period to perform measurements and identify different antenna panels with better link quality. If a new antenna panel is identified as having better link quality, such as above a threshold or better than the current serving antenna panel, the UE can use the new antenna panel for data communication or measurement. Figure 6 In this example, if antenna panel 602c is the serving antenna panel and the link quality of antenna panel 602c drops below a threshold, the corresponding UE may scan antenna modules 602a and 602b to determine whether antenna panel 602a or 602b can be used as a new serving antenna panel.

[0113] Significant data channel RSRP loss is observed at module switching boundaries. In some cases, the outdated RSRP values ​​are also low, which may cause severe link outages. It may take hundreds of milliseconds to fully update the L1-RSRP measurement table if it is already outdated for the newly selected serving module. Therefore, during this time, the selected TX beam at the base station and the RX beam at the UE may not be ideal.

[0114] Figure 7 700 is a flowchart for allocating resources to another antenna panel during a scanning period of a serving antenna panel according to various embodiments of the present disclosure. The operations of flowchart 700 may be implemented in a UE, for example Figure 3 UE 116 in.

[0115] Flowchart 700 begins at operation 702, where the timing and process of the predefined beam operation design are followed. In operation 704, it is determined whether the L1-RSRP measurement table of antenna panel X has been updated within T time slots. If the L1-RSRP measurement table of antenna panel X has been updated within T time slots, flowchart 700 returns to operation 702. If the L1-RSRP measurement table of antenna panel X has not been updated within T time slots, flowchart 700 proceeds from operation 704 to operation 706, where resources are allocated to antenna panel X to update its L1-RSRP measurement table.

[0116] To implement the operation of flowchart 700, a timer, e.g., T, may be defined to indicate when the L1-RSRP measurement table for a given module should be updated. Thus, if the L1-RSRP measurement table for a given antenna module X has not been updated in T time slots since the last update, the UE may allocate the necessary resources for the given antenna module X to update its L1-RSRP measurement table. As a result, at any module switching boundary, the L1-RSRP measurement table of the target module may not be very out-of-date / out-of-date because the L1-RSRP measurement table is updated according to a predefined timer. However, fewer resources are allocated to the current serving module, which may result in a loss in average data channel RSRP.

[0117] Fig. 8A A switching timeline between a serving antenna panel and a target antenna panel is shown. Timeline 800a depicts a first time period 802 in which service module 0 operates. At module switching boundary 804, service module 2 begins operation and continues to operate throughout time period 806. At module switching boundary 804, the L1-RSRP measurement table of antenna module 2 may be out of date, and the time required to perform measurements to update the L1-RSRP table may result in a temporary link interruption.

[0118] Figure 8B Various embodiments according to the present disclosure (particularly according to Figure 7 800b depicts a first time period 808 in which service module 0 operates. At module switching boundary 814, service module 2 begins operation and continues to operate throughout time period 816. Time period 810 is a measurement time period in which resources are allocated to antenna module 2 to allow antenna module 2 to make measurements and update its L1-RSRP measurement table. As shown in flowchart 700, if the L1-RSRP measurement table of antenna module 2 has not been updated within T time slots since the last update, then resources are allocated to antenna module 2. At module switching boundary 814, the L1-RSRP measurement table of antenna module 2 may not be out of date.

[0119] In some embodiments, the severity of the link outage may be reduced by switching to the first beam in the L1-RSRP measurement table of the target antenna module that can provide a satisfactory communication link at or shortly after the module switching boundary.

[0120] Fig. 9 900 is a flowchart of updating a beam measurement table based on a reordered beam according to various embodiments of the present disclosure. The operations of flowchart 900 may be implemented in a UE, for example Figure 3 UE 116 in.

[0121] Flowchart 900 begins at operation 902 and follows the timing and process of the predefined beam operation design. In operation 904, it is determined whether the current time is within N time slots after the module switching boundary. If the current time is not within N time slots after the module switching boundary, flowchart 900 returns to operation 902. However, if the current time is within N time slots after the module switching boundary, flowchart 900 proceeds to operation 906, in which measurement beams are formed in a predetermined order to update the L1-RSRP measurement table.

[0122] At the module switching boundary, for example, within N time slots after the module switching, the measurement beams formed to update the L1-RSRP measurement table are detected by the UE in a predetermined and optimized time order. The measurement beam that "most likely" matches the current channel conditions is formed and measured first. In some embodiments, the first measurement beam that can provide a satisfactory communication link is used for data communication to reduce latency. By doing so, both the BS and the UE can quickly identify the correct TX and RX beams to use, which in turn can avoid relatively long periods of large data channel RSRP loss, thereby avoiding severe link interruptions.

[0123] Fig. 10A A timeline for switching between a serving antenna panel and a target antenna panel is shown. Timeline 1000a depicts a first time period 1002 in which service module 0 is operating. At module switching boundary 1004, service module 2 begins operation and continues to operate throughout time period 1006. At module switching boundary 1004, the L1-RSRP measurement table of antenna module 2 may be out of date, and the time required to perform measurements to update the L1-RSRP table may result in a temporary link interruption. During time period 1008 within N time slots after the module switch, beams 1010 in the L1-RSRP measurement table of service module 2 are sequentially ordered.

[0124] Fig. 10B Various embodiments according to the present disclosure (particularly according to Fig. 9 1000b depicts a first time period 1012 in which service module 0 operates. At module switching boundary 1014, service module 2 begins operation and continues to operate throughout time period 1016. During time period 1018 within N time slots after the module switch, beams 1020 in the L1-RSRP measurement table may be reordered to allow faster identification of preferred Tx and Rx beams, which may reduce the severity of link outages. In the following Fig.11 and 12 An example of reordering beams in the L1-RSRP table is discussed in.

[0125] Fig.11 1100 is a flowchart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure. The operations of flowchart 1100 may be implemented in a UE, for example Figure 3 UE 116 in.

[0126] Flowchart 1100 begins at operation 1102, where the most recent beam used by the target service module for data communication is considered as a reference beam. In operation 1104, a predefined metric is calculated between the measurement beam of the target service module and the reference beam of the target service module. Non-limiting examples of the predefined metric may include corresponding to an angular distance on a sphere, overlap in beam patterns, etc.

[0127] The measurement beams of the target service modules are ranked based on their calculated metrics in operation 1106. For example, if the metric is angular distance on a sphere, the measurement beam with the smallest metric will be ranked highest, and similarly, the measurement beam with the largest metric will be ranked lowest.

[0128] In operation 1108, a measurement beam of the target service module is formed based on the order determined in operation 1106. At the module switching boundary, the measurement beams are detected by the UE in time order, from the highest level to the lowest level, within a time period 1018. In one embodiment, the target service module may use the first measurement beam that provides the desired link quality for communication.

[0129] Fig.12 1200 is another flowchart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure. The operations of flowchart 1200 may be implemented in a UE, for example Figure 3 UE 116 in.

[0130] Flowchart 1200 begins at operation 1202, where the most recent beam used by the current serving module for data communication is considered as a reference beam. In operation 1204, a predefined metric is calculated between the measurement beam of the target serving module and the reference beam of the current serving module. Non-limiting examples of the predefined metric may include corresponding to an angular distance on a sphere, overlap in beam patterns, etc.

[0131] The measurement beams of the target service modules are ranked based on their calculated metrics in operation 1206. For example, if the metric is angular distance on a sphere, the measurement beam with the smallest metric will be ranked highest, and similarly, the measurement beam with the largest metric will be ranked lowest.

[0132] In operation 1208, a measurement beam of the target service module is formed based on the order determined in operation 1206. At the module switching boundary, within time period 1018, the measurement beams are detected by the UE in time order, from the highest level to the lowest level. In one embodiment, the target service module may use the first measurement beam that provides the desired link quality for communication. In one embodiment, the target service module may use the first measurement beam that provides the desired link quality for communication.

[0133] Fig.13 1300 is another flowchart for determining a beam order for updating a beam measurement table according to various embodiments of the present disclosure. The operations of flowchart 1300 may be implemented in a UE, for example Figure 3 UE 116 in.

[0134] Flowchart 1300 combines the operations in flowcharts 1100 and 1200, but includes a timing condition for distinguishing which reference beam to select. Thus, flowchart 1300 begins with operation 1302, determining whether the target serving module has been measured within time T_th.

[0135] If the target service module is not measured within time T_th, flowchart 1300 proceeds to operation 1304, where the latest beam used by the target service module for data communication is considered to be the reference beam. In operation 1306, a predefined metric is calculated between the measurement beam of the target service module and the reference beam of the target service module. In operation 1308, the measurement beams of the target service modules are sorted based on their calculated metrics. In one embodiment, the measurement beams are sorted from high to low. In another embodiment, the order can be reversed.

[0136] In operation 1310, a measurement beam of the target service module is formed based on the order determined in operation 1308. After the module switching boundary, for example, within N time slots after the module switching boundary, the reordered measurement beams may be measured. In one embodiment, the target service module may use the first measurement beam that provides the desired link quality for communication.

[0137] Returning to operation 1302, if the target module has been measured within time T_th, flowchart 1300 proceeds to operation 1312, where the latest beam used by the current service module for data communication is considered to be a reference beam. In operation 1314, a predefined metric is calculated between the measurement beam of the target service module and the reference beam of the current service module. In operation 1316, the measurement beams of the target service modules are sorted based on their calculated metrics. In one embodiment, the measurement beams are sorted from high to low. In another embodiment, the order can be reversed. In operation 1318, the measurement beams of the target service module are formed based on the order determined in operation 1316. After the module switching boundary, for example, within N time slots after the module switching boundary, the reordered measurement beams can be measured. In one embodiment, the target service module can use the first measurement beam that provides the desired link quality for communication.

[0138] In flow chart 1300 , if the L1-RSRP measurement table of the target module was last updated less than T_th ago, it is assumed that some previous information / knowledge of the target serving module is not completely outdated and can be utilized.

[0139] Fig.14 1400 is a flowchart of updating a beam management table using a narrow beam of an optimal wide beam according to various embodiments of the present disclosure. The operations of flowchart 1400 may be implemented in a UE, for example Figure 3 UE 116 in.

[0140] Flowchart 1400 begins at operation 1402 and follows the timing and process of the predefined beam operation design. In operation 1404, it is determined whether the current time is within N time slots after the module switching boundary. If the current time is not within N time slots after the module switching boundary, flowchart 1400 returns to operation 1402. However, if the current time is within N time slots after the module switching boundary, flowchart 1400 proceeds to operation 1406, where a sub-beam is formed from a narrow beam of the best wide beam of the target service module to update the L1-RSRP measurement table. In one embodiment, at the module switching boundary, the UE forms a narrowband sub-beam of the best wide beam of the target service module determined during the module scanning period to update the L1-RSRP measurement table.

[0141] The probability that the measurement beam formed during the module switching boundary matches the current channel conditions is high. Therefore, the corresponding selected TX beam at the base station and RX beam at the UE for data communication will result in good link quality.

[0142] Fig.14 The embodiments described in Fig. 9The embodiment described in the embodiment differs in that no a priori information of the target service module or the current service module (e.g., the selection of the reference beam) is utilized. However, the scanning order of the sub-beams of the selected WB can be as follows: Fig. 9 The strategy proposed in is further optimized.

[0143] Fig.15A The beam structure of antenna module X 1500a includes wide beams 1502, 1504, and 1506, which operate independently of narrow beams 1508, 1510, 1512, 1514, 1516, 1518, and 1520.

[0144] Fig. 15B Various embodiments (particularly Fig.14 1500b). The hierarchical beam structure of module X 1500b includes wide beams 1522, 1524, and 1526 in a hierarchical relationship with one or more narrow beams. For example, wide beam 1522 is associated with narrow beams 1528, 1530, and 1532; wide beam 1524 is associated with narrow beams 1532, 1534, and 1536; and wide beam 1526 is associated with narrow beams 1536, 1538, and 1540. As previously described, after a module switching boundary, the hierarchical relationship can be used to select one or more narrow beams.

[0145] Fig.16 Various embodiments (particularly Fig.14 The timeline for switching between the serving antenna panel and the target antenna panel is as follows: Fig. 10A , and for the sake of brevity will not be reproduced.

[0146] Timeline 1600 depicts a first time period 1612 of service module 0 operation. At module switch boundary 1614, service module 2 begins operation and continues to operate throughout time period 1616. During time period 1618 within N time slots after the module switch, the beams 1620 measured and updated in the L1-RSRP measurement table may be limited to the sub-beams of the best wideband module for antenna module 2 determined during an earlier scan cycle. Fig.16 In this example, sub-beams 1532, 1534, and 1536 of wide beam 1524 are identified for measurement.

[0147] Fig.17 1700 is a flowchart for updating a beam measurement table according to various embodiments of the present disclosure. The operations of flowchart 1700 may be implemented in a UE, for example: Figure 3 UE 116 in.

[0148] Flowchart 1700 begins at operation 1702 and follows the timing and process of the predefined beam operation design. In operation 1704, it is determined whether the L1-RSRP measurement table of antenna module X has been updated within T time slots. If the L1-RSRP measurement table of antenna module X has been updated within T time slots, flowchart 1700 proceeds to operation 1706, in which another determination is made as to whether the current time is within N time slots after the antenna module is switched. If the current time is within N time slots after the antenna module is switched, flowchart 1700 proceeds to operation 1708 to form a measurement beam in a predetermined order to update the L1-RSRP measurement table. However, if the current time is not within N time slots after the antenna module is switched, flowchart 1700 returns to operation 1702.

[0149] Returning to operation 1704 , if it is determined that the L1-RSRP measurement table of antenna module X has not been updated within T time slots, flowchart 1700 proceeds to operation 1710 , where resources are allocated to module X to update its L1-RSRP measurement table before returning to operation 1706 .

[0150] Fig.18 Various embodiments (particularly Fig.17 The timeline for switching between the serving antenna panel and the target antenna panel is as follows: Fig. 10A , and for the sake of brevity will not be reproduced.

[0151] Timeline 1800 depicts a first time period 1802 of service module 0 operation. At module switch boundary 1808, service module 2 begins operation and continues to operate throughout time period 1820. Time period 1804 is a measurement time period in which resources are allocated to antenna module 2 to allow antenna module 2 to make measurements and update its L1-RSRP measurement table. As shown in flowchart 1700, if the L1-RSRP measurement table of antenna module 2 has not been updated within T time slots since the last update, then resources are allocated to antenna module 2. During time period 1818 within N time slots after the module switch, beams 1822 in the L1-RSRP measurement table may be reordered based on the measurements made during measurement time period 1804. In some embodiments, the severity of the link outage may be reduced by switching to the first beam in the L1-RSRP measurement table of the target antenna module that can provide a satisfactory communication link at or shortly after the module switch boundary.

[0152] Fig.191900 is a flowchart for updating a beam measurement table according to various embodiments of the present disclosure. The operations of flowchart 1900 may be implemented in a UE, for example Figure 3 UE 116 in.

[0153] Flowchart 1900 begins at operation 1902 and follows the timing and process of the predefined beam operation design. In operation 1904, it is determined whether the L1-RSRP measurement table of antenna module X has been updated within T time slots. If the L1-RSRP measurement table of antenna module X has been updated within T time slots, flowchart 1900 proceeds to operation 1906, in which another determination is made as to whether the current time is within N time slots after the antenna module is switched. If the current time is within N time slots after the antenna module is switched, flowchart 1900 proceeds to operation 1908 to form a measurement beam from a sub-narrow beam of the best wide beam of the target service module, thereby updating the L1-RSRP measurement table. However, if the current time is not within N time slots after the antenna module is switched, flowchart 1900 returns to operation 1902.

[0154] Returning to operation 1904 , if it is determined that the L1-RSRP measurement table of antenna module X has not been updated within T time slots, flowchart 1900 proceeds to operation 1910 , where resources are allocated to module X to update its L1-RSRP measurement table before returning to operation 1906 .

[0155] Fig. 20 Various embodiments (particularly Fig.19 A timeline for switching between a serving antenna panel and a target antenna panel in accordance with an embodiment described in the accompanying drawings.

[0156] The timeline for switching between the service antenna panel and the target antenna panel is Fig. 10A , and for the sake of brevity will not be reproduced.

[0157] Timeline 2000 depicts a first time period 2002 of service module 0 operation. At module switch boundary 2008, service module 2 begins operation and continues to operate throughout time period 2020. Time period 2004 is a measurement period in which resources are allocated to antenna module 2 to allow antenna module 2 to make measurements and update its L1-RSRP measurement table. As shown in flowchart 1900, if the L1-RSRP measurement table of antenna module 2 has not been updated within T time slots since the last update, then resources are allocated to antenna module 2. During time period 2018 within N time slots after the module switch, the beams 2022 measured and updated in the L1-RSRP measurement table can be limited to the sub-beams of the best wideband module of antenna module 2 determined during measurement time period 2004. In some embodiments, the severity of the link outage can be reduced by switching to the first beam in the L1-RSRP measurement table of the target antenna module that can provide a satisfactory communication link at or shortly after the module switch boundary.

[0158] Fig.21 21 shows a flow chart for switching between a serving antenna panel and a target antenna panel according to various embodiments of the present disclosure. The operations of flow chart 2100 may be implemented in a UE, for example Figure 3 UE 116 in.

[0159] Flowchart 2100 begins at operation 2102 and follows the timing and process of the predefined beam operation design. In operation 2104, it is determined whether the current time is within N time slots after the antenna module is switched. If the current time is not within N time slots after the antenna module is switched, flowchart 2100 returns to operation 2102. However, if the current time is within N time slots after the antenna module is switched, flowchart 2100 proceeds to operation 2106 to form a measurement beam selected from the target service module, thereby updating the L1-RSRP measurement table. In operation 2108, a receive beam for data communication is selected from the service module used before the antenna module is switched.

[0160] By using the receive beam from the previous service module for data communication, severe link interruption due to outdated measurement information of the target service module can be avoided as long as the receive beam from the previous service module can still provide reasonable link performance. After the measurement information of the target service module is fully updated, the receive beam from the target service module can be used for data communication.

[0161] Fig.22AA switching timeline between a serving antenna panel and a target antenna panel is shown. Timeline 2200a depicts a first time period 2202 of operation of serving antenna module 0. At module switching boundary 2204, serving antenna module 2 begins operation and continues to operate throughout time period 2206. During time period 2208 within N time slots after the module switching, beam 2210 of serving module 2 is used for measurement and data communication. In particular, measurement beam 2210a from serving antenna module 2 is used to update the L1-RSRP measurement table of serving antenna module 2. Receive beam 2210b from serving antenna module 2 is used for data communication.

[0162] Fig. 22B Various embodiments (particularly Fig.21 2200a). Timeline 2200b depicts a first time period 2212 of operation of serving antenna module 0. At module switch boundary 2214, serving antenna module 2 begins operation and continues to operate throughout time period 2216. During time period 2218 within N time slots after the module switch, beam 2210 is used for measurement and data communication. However, measurement beam 2220a from serving antenna module 2 is used to update the L1-RSRP measurement table of antenna module 2, and receive beam 2220b from the previous antenna serving module 0 is used for data communication.

[0163] Receive beam management for mobile terminals

[0164] As previously mentioned, TCI state switching can result in unwanted communication interruption at the UE. Therefore, various embodiments of the present disclosure describe several fast and efficient receive beam selection / operation strategies for unknown TCI state switching. In addition to the strict known conditions defined in 3GPP TS 38.133 for a given TCI state, several other practical conditions that can better characterize the target TCI state are implemented at the UE together with their corresponding receive beam selection / operation strategies.

[0165] For example, by definition, if the last measurement of the TCI state is more than X ms ago (e.g., more than 1280 ms ago) or the SNR of the target TCI state is lower than a given threshold Th_0, the UE may not be able to directly determine the receive beam for the target / switched TCI state, but must perform an exhaustive search on a certain number of beam codewords in the beam codebook to identify the receive beam of the TCI state of interest. In one aspect of the present disclosure, the UE may first decompose the unknown condition of a given TCI state into several sub-conditions or one or more combinations thereof. The UE may then use different types of beams (e.g., different beam widths, radiation patterns, beam patterns, etc.) and different receive beam selection strategies for different sub-conditions or one or more combinations thereof. For example, if the SNR of the target / switched TCI state is lower than Th_0, by definition, the TCI state of interest is unknown to the UE. In this case, the UE may have performed the last measurement of the target TCI state, either more than X ms ago, or less than X ms ago. If the last measurement of the target TCI state is less than Xms ago, the UE may use the receive beams corresponding to the target TCI state or their steering directions as reference receive beams or reference directions. Accordingly, when receiving data packets from the target TCI (e.g., TCIx) during the past measurement period, the reference receive beam may result in the highest, second highest, third highest, or fourth highest (may be up to the eighth highest) received signal power.

[0166] Fig.23 Unknown TCI state switching according to various embodiments of the present disclosure is shown. In communication system 2300a, UE 116 communicates with BS 102 in a known TCI state. In communication system 2300b, BS 102 switches the TCI state, but UE 116 is unaware of the TCI state. When UE 116 is unaware of the TCI state, a search for a corresponding receive beam of the TCI state of interest is performed, which may result in communication interruption.

[0167] Fig.24 A comparison of receive beam search over the entire angular space and receive beam search over a restricted area according to various embodiments of the present disclosure is shown. In particular, angular search space 2400a is a full-angle search space that can be searched by UE 116 when determining a receive beam for a target TCI state. Angular search space 2400b is a restricted search space around a reference receive beam / direction or across an angular range. By selecting / forming a relatively small number of beams with relatively small beamwidths around a reference receive beam (or reference direction), or covering a restricted angular range, search complexity and latency can be reduced.

[0168] In another embodiment of the present disclosure, the UE may also adaptively configure the conditions of the unknown TCI state based on channel conditions and / or other system information. This technique may be useful in a dynamic environment, such that propagation channel conditions may change rapidly due to various mobility settings. For example, the channel may be highly correlated during a certain amount of time, for example, with a large channel coherence time, but independent during another time period. In these cases, using a fixed cutoff threshold to characterize the obsolescence state (X ms) or detectability (Th_0 of SNR) of the target TCI state may not be a viable solution to achieve promising performance. Therefore, on the other hand, the UE may adjust the known / unknown conditions used to characterize the TCI state based on past measurements, channel conditions, and other necessary system information, and optimize the receive beam selection / operation strategy accordingly. For example, the UE may first define a set of potential time windows, such as {X ms}. 0 , X 1 , …, X T-1}ms to describe the last measurement of the TCI state, rather than using a fixed time window; in addition, the UE can also define a set of potential SNR thresholds, such as {Th 0 , Th 1 ,…,Th M-1} to classify the actual SNR of the target TCI state instead of using a fixed threshold. For a channel condition, the UE can set the known TCI state condition as: the last measurement at X 2 ms, and the SNR of the target TCI state exceeds Th 2 For another channel condition, the UE may set the known condition for a given TCI state to be: the last measurement at X 0 ms, and the actual SNR of the TCI state is greater than Th M-1 It is expected that by adaptively configuring known / unknown conditions based on channel conditions and / or other system information, the overall receive beam search complexity and latency at the terminal can be reduced.

[0169] Millimeter wave (mmWave) frequency bands are expected to provide high data rates in wireless LANs and fifth generation (5G) cellular networks. The small carrier wavelengths at mmWave frequencies enable the synthesis of compact antenna arrays, providing large beamforming gains for good received signal power. Grid of beams (GoB) based beam search is the de facto method for configuring transmit and receive beams; a variant is used in IEEE 802.11ad systems and 5G. Specifically, for a given channel condition, the BS and UE search all candidate beam codewords in their own beam codebooks and select the best combination of transmit and receive beams to optimize a given performance metric. However, such an exhaustive search on a large beam codebook may bring significantly high power consumption, implementation complexity, and large access delay to the user terminal, not to mention that receive beam search on the UE side appears in many basic deployment scenarios in 5G, such as directional initial access, beamforming-based inter-cell measurements, TCI state switching, and many mobility-related configurations. To reduce access delay, the UE can perform beam search using a small beam codebook with a wide beamwidth. However, in this case, the corresponding link quality may deteriorate and the link budget may not be met, especially when the receive SNR / SINR is a key design factor.

[0170] In the present disclosure, several receive beam selection / operation strategies on the UE side are described, assuming that the BS triggers a TCI state switch due to link blocking, link failure and / or other design factors. The BS may send a TCI state switch command to the UE via RRC, MAC CE, DCI or other types of signaling or one or more combinations thereof. Upon receiving the TCI state switch command, the UE checks whether the switch or target TCI state is known to the UE. Explicit conditions for a known TCI state are specified in 3GPP TS38.133. In some embodiments, if the TCI state has been measured by the UE at least once before, the last measurement of the target TCI state is no more than X ms ago, and the SNR of the target TCI state exceeds a given threshold, such as Th_0, then the UE knows the TCI state. In some embodiments, if any of the above conditions is not met, the TCI state is unknown to the UE.

[0171] Different receive beam operation strategies can be applied to known TCI state switching and unknown TCI state switching. For known TCI state switching, the UE can directly apply the receive beam corresponding to the switched TCI state to receive data packets. For unknown TCI state switching, the UE may have to perform a beam search on a given set of candidate beams, and therefore perform a beam search on a certain angle space to identify the receive beam for the switching / target TCI state. In order to reduce access delay, power consumption and implementation complexity, an efficient and effective receive beam selection strategy needs to be implemented on the UE, and their corresponding trigger events / conditions also need to be specified.

[0172] In one embodiment, the UE further checks the obsolete state of the target / switched TCI state, although it is unknown to the UE by definition. That is, assuming that the SNR of the target TCI state is less than Th_0 (the trigger condition for the unknown state of the target TCI state), the last measurement of the target TCI state can be X ms ago, or less than X ms ago. The UE can apply different receive beam operation strategies based on the obsolete state of the switched TCI state. For example, if the last measurement of the switched / target TCI state is greater than X ms ago, the UE will perform a full beam search over the entire angular range or a given beam codebook to identify the receive beam of the target TCI state. Otherwise, the UE will perform a beam search over a limited angular range or a subset of the beam codebook to select the receive beam of the target TCI state. In this example, the candidate beams to be searched and / or the beam selection strategy do not depend on the exact SNR value of the target TCI state.

[0173] exist Fig.25A and 25B In the present invention, an algorithm is given to illustrate the receive beam operation at the UE for unknown TCI state switching under various outdated conditions. The proposed receive beam operation algorithm does not depend on the SNR of the target TCI state, although it may be the only factor that causes the target TCI state to be unknown. That is, assuming a given beam width, radiation pattern, or beam pattern of a candidate beam, the UE optimizes the number of candidate beams to search or the angular range to scan based on the outdated state of the target TCI state. In several other embodiments of the present disclosure, in addition to optimizing the angular space to be scanned based on the outdated state of the TCI state, the UE can also optimize the beam width, radiation pattern, or beam pattern of the candidate beam based on the SNR of the target TCI state.

[0174] Fig.25A 2500a is a flowchart of receiving beam search for TCI state switching according to various embodiments of the present disclosure. The operation of flowchart 2500a can be implemented in a UE, for example Figure 3 UE 116 in.

[0175] Flowchart 2500a starts from operation 2502, receiving an indication of switching the TCI state to TCI state x (TCIx). TCI state switching can be triggered by various factors, such as link blocking and link failure. The BS or network can send a corresponding TCI state switching command to the UE via RRC, MAC CE of PDCCH, and DCI of PDSCH. Fig.26 An example of a MACCE-based TCI status indication process is described in more detail in.

[0176] In operation 2504, it is determined whether TCIx is known. This determination may be made based on a set of predefined conditions, which may include: (i) the TCI state of interest has been measured by the UE before (at least once), (ii) the last measurement of the TCI state of interest is less than X ms ago, and (iii) the SNR of the switched / target TCI state is greater than a given threshold Th_0. If any of the conditions (i), (ii) and (iii) are not met, the switched TCI state is considered to be unknown to the UE, and the UE may optimize the corresponding receive beam selection strategy, as shown in flowchart 2500.

[0177] If TCIx is known, flow chart 2500a proceeds from operation 2504 to operation 2506, where a receive beam corresponding to TCIx is selected. Therefore, the UE knows the receive beam for the switched TCI state. This correspondence between the receive beam and the known TCI state can be established during the last measurement. Therefore, when the target / switched TCI state takes effect, the UE can directly apply the receive beam corresponding to the target / switched TCI state.

[0178] If TCIx is unknown, flow chart 2500a proceeds from operation 2504 to operation 2508, where it is determined whether TCIx has been measured before. For example, the UE may determine whether it has previously sent at least one measurement report for a handover / target TCI state.

[0179] If TCIx has not been measured before, flowchart 2500a proceeds from operation 2508 to operation 2510, in which a beam search is performed on the first set of beams and a receive beam is determined for TCIx. The candidate beams in the first set of beams may cover a relatively large angular range. For example, the first set of candidate beams to be searched may correspond to a DFT beam codebook, or a DFT beam codebook with an oversampling factor greater than 1. The angular range of interest may be 120 degrees around the UE azimuth boresight, and 90 degrees around the UE elevation boresight. In order to find a receive beam for TCIx, the UE may exhaustively search all candidate beams and select the beam that produces the best performance metric. The performance metric may be based on received signal power, RSRP, RSRQ, SNR, and / or SINR. As another example, the UE may perform a search / measurement on a subset of beams from all candidate beams. The UE may then interpolate the search / measurement results from the subset of beams and select a receive beam from the candidate beams. The selected receive beam may or may not belong to a subset of beams among all candidate beams in the first group. The measurement of the subset of beams among all candidate beams in the first group may be based on received signal power, RSRP, RSRQ, SNR and / or SINR.

[0180] Returning to operation 2508, if TCIx was previously measured, flowchart 2500a proceeds to operation 2512, where it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). This condition characterizes how outdated the switch / target TCI state is for the UE for a given channel condition. If the last measurement of TCIx is within the X ms time window, the UE can conclude that the switched TCI state is unknown because the corresponding SNR of TCIx is less than Th_0. That is, the target TCI state is not completely outdated / expired with respect to the last measurement time, although it is still considered unknown to the UE due to the low SNR. In this case, flowchart 2500 proceeds to operation 2514.

[0181] If TCIx was measured more than X ms ago, flowchart 2500a proceeds to operation 2510. In particular, if the last measurement of the target TCI state was performed by the UE more than X ms ago, the target TCI state is unknown and is outdated / expired regardless of the SNR. However, if TCIx was not measured more than X ms ago, flowchart 2500a proceeds to operation 2514, in which a beam search is performed on the second set of beams to determine the receive beam of TCIx. The candidate beams in the second set of beams may cover a smaller angular range than the candidate beams in the first set of beams searched in operation 2510. In operation 2514, the unknown TCI state (TCIx) is not completely outdated / expired. Therefore, the UE can determine (or narrow) the angular range to be searched using the receive beams (and / or their steering directions) corresponding to the target TCI state. This correspondence between the receive beams and the TCI state can be established during the last measurement.

[0182] For example, the UE may consider the receive beam corresponding to the target TCI state as a reference beam and / or its steering direction as a reference direction, and generate a set of beams around the reference receive beam and / or reference direction. Using the reference receive beam and / or reference direction, a smaller number of candidate beams to be searched and / or a smaller angular range to be scanned can be established compared to those beams in the first group of beams. This in turn can reduce search complexity and access delay. In order to find a receive beam for TCIx, the UE can exhaustively search all candidate beams in the second group and select the one that results in the best performance metric. The performance metric can be based on received signal power, RSRP, RSRQ, SNR and / or SINR.

[0183] As another example, the UE may perform a search / measurement on a subset of beams among all candidate beams in the second group. The UE may then interpolate the search / measurement results from the subset of beams among all candidate beams in the second group and select a receive beam from the candidate beams. The selected receive beam may or may not belong to the subset of beams among all candidate beams in the second group. The measurement of the subset of beams among all candidate beams in the second group may be based on received signal power, RSRP, RSRQ, SNR, and / or SINR.

[0184] exist Fig.25AIn this embodiment, operation 2510 and operation 2514 differ in two key points. First, a reference receive beam or reference direction is defined in operation 2514 to limit the angular space to be scanned, because the target TCI state is not (completely) out-of-date / outdated in operation 2514, even if it is unknown. The reference receive beam or reference direction corresponding to the target TCI state can help the UE narrow down the potential angular range to be scanned and / or the potential candidate beams to be searched. Second, the size of the first set of beams in operation 2510 may be different from the size of the second set of beams in operation 2514, because the angular range scanned in operation 2514 may be smaller than the angular range in operation 2510 due to the introduction of the reference beam / direction. Note that in Fig.25A In this embodiment, the candidate beams in the first group and the second group may have the same beam width, radiation pattern, beam pattern, etc.

[0185] Fig.25B Another flowchart of receive beam search for TCI state switching according to various embodiments of the present disclosure is shown. The operations of flowchart 2500b can be implemented in a UE, for example Figure 3 UE 116 in.

[0186] Flowchart 2500b begins at operation 2520, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 2522, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 2500b proceeds from operation 2522 to operation 2524, where a receive beam corresponding to TCIx is selected.

[0187] If TCIx is unknown, the flowchart 2500b proceeds from operation 2522 to operation 2526, where it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). If TCIx was measured more than X ms ago, the flowchart 2500b proceeds to operation 2528, where a beam search is performed on the first set of beams to determine a receive beam for TCIx. However, if TCIx was not measured more than X ms ago, the flowchart 2500b proceeds to operation 2530, where a beam search is performed on the second set of beams to determine a receive beam for TCIx.

[0188] Therefore, if the target TCI state is unknown and the last measurement was greater than X ms ago, the UE may perform a full scan of all candidate beams (the first set of beams) to update the corresponding L1-RSRP measurement table and select the best RX beam for the target TCI state. In this case, no a priori information of the target TCI state is or can be utilized by the UE.

[0189] If the target TCI state is "unknown", but it was last measured less than X ms ago, the reference beam previously used for the target TCI state may be first determined, and then a second set of beams around the reference beam may be determined (determined by a predetermined metric, such as angular distance on a unit sphere, beam pattern overlap, etc.). The UE may scan on the second set of beams to update the corresponding entry in the L1-RSRP measurement table and select the best RX beam for the target TCI state. By scanning only a limited set of beams, access delay may be reduced.

[0190] Fig.26 The process of TCI status indication enabled by MAC CE for PDCCH according to various embodiments of the present disclosure is shown. The operation of process 2600 can be implemented in a BS, for example Figure 2 BS 102 in.

[0191] In operation 2602, the BS or network first configures M through the RRC parameter PDSCH-config. 0 In operation 2604, for a given control resource set (CORESET), the network or BS obtains the TCI state from the M via the RRC parameter ControlResourceSet. 0 Configure a group of M in the TCI status list 1 (e.g., 64) candidate TCI states. Finally, at operation 2606, the network or BS sends an indication of the selected TCI state to the UE via a MAC CE. In addition, the network or BS may indicate the selected TCI state from the MAC CE to the corresponding CORESET of the UE. 1 Configure a new TCI state in the TCI state list.

[0192] In some embodiments, the UE may not monitor all M 1 Therefore, the switched TCI state may be unknown to the UE. For the DCI of PDSCH to enable TCI state indication / switching, the network or BS first configures M through the RRC parameter PDSCH-config 0( For example, a list of 128) TCI states. Then, through the UE-specific PDSCH MAC CE, the total number M 0Eight out of the TCI states are active. The network or the BS notifies the UE of the target / handoff TCI state (one of the eight active TCI states) via DCI. The UE is capable of monitoring the eight active TCI states, and in this case, the target / handoff TCI state can be considered to be always known to the UE. If the UE is only capable of monitoring some of the eight active TCI states and the handoff / target TCI state indicated by the BS is outside the monitored set of active TCI states, then the target / handoff TCI state can be considered unknown to the UE.

[0193] Fig.27A A flowchart of beam selection according to various embodiments of the present disclosure is shown. The operations of flowchart 2700a can be implemented in a UE, such as Figure 3 UE 116 in. In addition, the operations of flowchart 2700a can be implemented as steps for receiving beam search for TCI state handoff in another flowchart. For example, the operations of flowchart 2700a can be implemented in operation 2514 of flowchart 2500. The operations of flowchart 2700 will be described in conjunction with Fig.27B the illustration in. Fig.27B depicts a corresponding received beam based on Fig.27A the operations in.

[0194] Flowchart 2700a starts with operation 2702 to determine a reference received beam 2722 and / or a reference angular direction 2720. In operation 2704, a set of candidate beams 2724 is formed based on the reference received beam 2722 and / or the reference angular direction 2720. The size of the second set of beams (or the number of candidate beams), the exact candidate beam codewords in the beam codebook, etc. may vary according to the exact time of the last measurement / report of the target TCI state (<X ms), channel conditions, and other design factors. For example, if the last measurement of the target TCI state was several time slots (e.g., less than 10 ms) ago, the second set of candidate beams may include only those beams that are closely around the reference beam / direction (e.g., the adjacent 4 beams in the azimuth and elevation domains).

[0195] In operation 2706, a received beam 2726 is selected based on the measurements of the candidate beams 2724. The selection of the received beam is described in Fig.25A operation 2514 in, and for the sake of brevity, it will not be repeated here.

[0196] Fig.28 Examples of selected beams according to various embodiments of the present disclosure (particularly Fig.25A , Fig.25B , Fig.27A and Fig.27B the embodiments described in) are shown. Fig.282800a, 2800b, and 2800c of the beam codebook. In each group of beams, the circles represent the various beams in the beam codebook. The shaded circle 2802 represents a candidate beam in the second group of beams from operation 2514 of flowchart 2500. The shaded circle 2804 with a triangle in the center represents the reference receive beam / direction. The shaded circle 2808 with a diamond in the middle represents the selected receive beam. The unshaded circle 2806 represents other beams in the beam codebook. Beam groups 2800a, 2800b, and 2800c show that even for the same reference receive beam and / or reference direction, the candidate beams for selection can be different. For example, in beam group 2800c, a total of four beams (two in the azimuth domain and two in the elevation domain) are formed around the reference receive beam. Therefore, there are a total of five candidate beams in the second group including the reference receive beam. In contrast, beam set 2800b includes only two beams formed in the elevation domain, resulting in a total of three candidate beams.

[0197] As previously mentioned, the second set of candidate beams may vary even with the same reference beam and / or reference steering direction. The selection of the second set of candidate beams may depend on the exact time of the last measurement of the target TCI state, channel conditions, and / or other information collected by the UE (e.g., the UE's direction, moving speed, and forward direction collected by an accelerometer and a magnetometer). For example, for a given direction of the UE, the UE may prefer to select certain beams as candidate beams to cover a specific angular space around the reference beam / direction rather than other beams covering other angular ranges around the reference beam / direction.

[0198] Based on the above information, a lookup table can be implemented at the UE, which maps one or more combinations / patterns of candidate beams to the exact time of the last measurement of the target TCI state, as well as a set of information including but not limited to the direction of the UE, the moving speed and the forward direction. Table 1 is an example of such a lookup table characterizing candidate beam patterns. For example, if the last measurement time t of the target TCI state satisfies t∞(X1,X]ms, and their information set can be best characterized by {Ψ}, then the second set of beams is formed by the UE using the mode B candidate beams, e.g. Fig.25A Note that the first set of beams (e.g. Fig.25A The first group of beams in operation 2510 in the embodiment of the present invention may be constructed by the UE using Pattern-X candidate beams, that is, Fig.29 The beam pattern 2906 in , which can correspond to all beam codewords in the beam codebook, covers the entire angular range of interest.

[0199] Table 1

[0200]

[0201] Fig.29 Various modes of candidate beams according to various embodiments of the present disclosure are shown. In each mode 2906, 2908, 2910, 2912, 2914, and 2916, the shaded circle 2902 represents a candidate beam in the beam codebook, and the shaded circle 2904 with a triangle in the middle represents a receive beam / direction. Obviously, different modes can have the same number of candidate beams (e.g., mode 2908 and mode 2910). In general, a smaller t can correspond to a smaller number of candidate beams in the candidate beam mode.

[0202] In some embodiments, if the target TCI state is "unknown" and its SNR is lower than a given threshold Th_0, the UE may perform a full scan of all candidate beams in the second group of beams to update the corresponding L1-RSRP measurement table and select the best RX beam for the target TCI state. In these embodiments, since the SNR condition is not promising, a narrow beam in the second group is used. In some embodiments, if the target TCI state is "unknown", but its SNR exceeds a given threshold Th_0, the UE may perform a full scan of all candidate beams (i.e., the first group of beams) to update the corresponding L1-RSRP measurement table and select the best RX beam for the target TCI state. In these embodiments, a wide beam with lower array gain in the first group is used to reduce beam search delay because the SNR condition is promising. These embodiments are described below. Fig.30 A more detailed description is given in .

[0203] Fig.30 FIG. 4 is a flowchart of receiving beam selection under TCI state switching according to various embodiments of the present disclosure. Fig.30 In this example, the target / switching TCI state SNR is the trigger condition for various types of receive beam selection strategies. This is different from Fig.25A The operation of flowchart 3000 may be implemented in a UE, for example, Figure 3 UE 116 in.

[0204] Flowchart 3000 begins at operation 3002, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3004, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 3000 proceeds from operation 3004 to operation 3006, where a receive beam corresponding to TCIx is selected.

[0205] If TCIx is unknown, then flow diagram 3000 proceeds from operation 3004 to operation 3008 where it is determined whether the SNR of TCIx is below a threshold. Operation 3008 characterizes the detectability of the switching / target TCI state during the switching period.

[0206] If the SNR of TCIx is not below the threshold, flowchart 3000 proceeds to operation 3010, where a beam search is performed on the first set of beams to determine a receive beam for TCIx. If the SNR of the target / switching TCI state exceeds Th_0, it means that the target / switching TCI state is detectable during the switching period.

[0207] However, if the SNR of TCIx is below the threshold, the flowchart 3000 proceeds from operation 3008 to operation 3012, where a beam search is performed on the second set of beams to determine a receive beam for TCIx. If the SNR of TCIx is below a given threshold Th_0, the target TCI state may become undetectable during the switching period.

[0208] exist Fig.30 In this example, the selection of the first and second sets of candidate beams does not depend on the staleness of the target TCI state, or even on whether the UE has previously measured the target / switched TCI state.

[0209] In operation 3010, the UE performs a receive beam search on a first group of candidate beams in a switching / target TCI state. In operation 3012, the UE performs a receive beam search on a second group of candidate beams in a switching / target TCI state. In this example, the first group of candidate beams and the second group of candidate beams may cover the same angular range of interest. For example, the angular range of interest may be 120 degrees around the UE azimuth boresight and 90 degrees around the UE elevation boresight. The first group of candidate beams may correspond to a DFT beam codebook, or a DFT beam codebook with an oversampling factor greater than 1. The second group of candidate beams may correspond to another DFT beam codebook, or another DFT beam codebook with an oversampling factor greater than 1. The design principles of the first and second groups of beams in operations 3010 and 3012 are different. Fig.25A The design principles of the first and second groups of beams in operations 2510 and 2514 of FIG. 25. In the former case, the two groups of beams can cover the same angular space, but have different one or more beam-specific parameters, such as beam width, radiation pattern, and beam pattern. In the latter, the two groups of beams can cover different areas using different numbers of beams, but their beam width, radiation pattern, beam pattern, etc. are the same.

[0210] The following process is common to operations 3010 and 3012, i.e., searching the first set of candidate beams and the second set of candidate beams. In order to find the receiving beam for TCIx, the UE may perform an exhaustive search of all candidate beams and select the beam that produces the best performance metric. The performance metric may be based on received signal power, RSRP, RSRQ, SNR and / or SINR. As another example, the UE may perform a search / measurement on a subset of beams among all candidate beams. The UE may then interpolate the search / measurement results from the beam subset and select a receiving beam from the candidate beams. The selected receiving beam may or may not belong to the beam subset. The measurements on the beam subset may be based on received signal power, RSRP, RSRQ, SNR and / or SINR.

[0211] Fig.31 Candidate beams in the first group and the second group according to various embodiments of the present disclosure are shown. One of the main differences between the first group of candidate beams 3100a and the second group of candidate beams 3100b is their beamwidth. In this example, the beamwidth, for example the 3dB beamwidth of the candidate beams in the first group 3100a can be greater than the 3dB beamwidth of the candidate beams in the second group 3100b. The bird's-eye view of the first group of candidate beams 3100a and the second group of candidate beams 3100b shows that the first group of candidate beams 3100a and the second group of candidate beams 3100b have different beamwidths, and therefore, different numbers of candidate beams in the group cover the same angular range of interest. One of the motivations for using different beam groups with different beamwidths is that they can be applied to various SNR conditions / constraints. For example, an SNR greater than Th_0 for the switching / target TCI state means that the link quality is good enough to allow the use of relatively wide beams (the first group 3100a in this example) with relatively small beamforming / array gain. If the SNR of the switching / target TCI state is below a given threshold Th_0, relatively narrow candidate measurement beams (in this example, the second group 3100b) may be needed to ensure a certain link quality and link budget. Compared with wide beams, more narrow beams are needed to cover the same angular space. If an exhaustive search is performed on the candidate measurement beams, this in turn leads to high computational complexity and access delay. Fig.31 In the example shown, the UE searches all 16 beams in the second group 3100b (in the azimuth and elevation domains) to find a receive beam for the target TCI state, while the UE only searches 4 beams in the first group of candidate beams 3100a.

[0212] The beamwidths of the candidate beams, as well as the total number of candidate beams in a given set, may vary depending on the exact value of the SNR for the target TCI state. For example, assume that the second group 3100b contains a total of 16 candidate measurement beams, covering an angular range A. If the SNR for the target / switching TCI state exceeds Th_0 by more than 3 dB, it may be preferred that the beamwidths of the beams in the first group are approximately twice that of the beams in the second group, so that the number of candidate beams in the first group is half that of the beams in the second group (i.e., 8 in this example), to cover the same angular range A. If the SNR for the target / switching TCI state exceeds Th_0 by more than 6 dB, it may be preferred that the beamwidths of the beams in the first group are approximately four times that of the beamwidths in the second group 3100b, so that the number of candidate beams in the first group is one-fourth that of the beamwidths in the second group (i.e., 4 in this example), to cover the same angular range A. The mapping between the SNR for the target / switching TCI state and the desired beamwidth may be implemented on the UE in the form of a lookup table.

[0213] In Table 2, an example of such a lookup table is given, where each row maps the SNR of the target / switching TCI state to the desired beamwidth and candidate beam type. It can be observed from Table 2 that, for example, if the SNR of the target TCI state satisfies Th_0<γ≤Th_1, then the UE can select θ 1 As another example, if the SNR of the target TCI state satisfies Th_2<γ≤Th_3, the UE can select θ 3 As the desired beamwidth is used to generate another set of candidate beam codewords, it is possible to cover the same angular space as in the previous example. From Table 2, it is clear that the candidate beam types may correspond one-to-one with the desired beamwidth, and therefore, the exact SNR of the target TCI state.

[0214] Table 2

[0215]

[0216] Fig.32Various types of candidate beams according to various embodiments of the present disclosure are shown. It can be seen that different candidate beam types may correspond to different beam widths, and in this example, starting from type-I to type-IV, the beam width of the candidate beams becomes larger and larger (i.e., from narrow beams to wider and wider beams). Note that an alternative to directly generating candidate beams of desired beam widths is to map the existing beam codebook to the desired beam width, which can reduce implementation complexity. For example, the beam codebook implemented at the UE may have a hierarchical structure, including multiple layers of beam codewords, each layer corresponding to a different beam width. The beam width of a beam codeword selected from a lower layer (e.g., the first layer) may be greater than the beam width of a beam codeword selected from a higher layer (e.g., the third layer). According to Table 2, the third layer beam codeword may therefore be mapped to Θ 0 (Type-I candidate beam), the second layer beam codeword can be mapped to θ 1 (Type-II candidate beams), and the first layer beam codeword can be mapped to θ 2 (Type-III candidate beam).

[0217] In the previous embodiments, both outdated and detectable conditions were considered for establishing an "unknown" TCI state, and the outdated / detectable condition was characterized by a single threshold. In some embodiments, it may be desirable to jointly consider the outdated and detectable conditions for the "unknown" TCI state, and apply different thresholds (or even adaptive thresholds) to better characterize the outdated and detectable conditions. These embodiments are discussed in more detail in the subsequent figures.

[0218] Fig.33 3300 is a flowchart of receiving beam selection under TCI state switching according to various embodiments of the present disclosure. The operation of flowchart 3300 can be implemented in a UE, for example Figure 2 UE 316 in , which combines the accurate SNR of the outdated state and the target / handover TCI state.

[0219] Flowchart 3300 begins at operation 3302, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3304, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 3300 proceeds from operation 3304 to operation 3306, where a receive beam corresponding to TCIx is selected.

[0220] If TCIx is unknown, the flowchart 3300 proceeds from operation 3304 to operation 3308, where it is determined whether TCIx has been measured before. If TCIx has not been measured before, the flowchart 3300 proceeds from operation 3308 to operation 3310, where a beam search is performed on the first set of beams to determine a receive beam for TCIx.

[0221] Returning to operation 3308, if it is determined that TCIx was previously measured, the flowchart 3300 proceeds to operation 3312, where it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). If TCIx was not measured more than X ms ago, the flowchart 3300 proceeds to operation 3314, where a beam search is performed on the second set of beams to determine a receive beam for TCIx. Note that in this operation, since the target TCI state is unknown to the UE, the SNR of TCIx should be lower than the threshold Th_0.

[0222] However, if TCIx was measured more than X ms ago, the flowchart 3300 proceeds from operation 3312 to operation 3316, where it is determined whether the SNR of TCIx is below a threshold. Note that in this operation, the SNR of the target / switched TCI state may exceed or fall below a predetermined threshold because the target TCI state is completely outdated / expired, which may result in an unknown state of the target TCI state for the UE.

[0223] If the SNR of TCIx is below the threshold, the flowchart 3300 proceeds to operation 3318, where a beam search is performed on the third set of beams to determine the receive beam of TCIx. However, if the SNR of TCIx is not below the threshold, the flowchart 3300 proceeds from operation 3316 to operation 3320, where a beam search is performed on the fourth set of beams to determine the receive beam of TCIx.

[0224] exist Fig.33 In the example shown, different candidate beam combinations in operations 3310, 3314, 3318, and 3320 may have different candidate beam patterns and / or candidate beam types. This is different from the algorithm developed in the previous embodiment, in which different candidate beam groups have different candidate beam patterns (e.g., Fig.25A 2510 and 2514 in ) or candidate beam types (e.g., Fig.30 Operations 3010 and 3012) in the example are different, but not both are different.

[0225] In operation 3310, a first set of candidate beams can be generated by the UE without relying on the outdated state of the target TCI state and / or SNR conditions. Thus, the candidate beams in the first set can cover the entire angle range of interest with a medium beam width to balance the complexity and accuracy of beam search. For example, the first set of candidate beams can have a beam pattern of pattern-X, i.e., Fig.29 the beam pattern 2906 in Fig.32 to cover the entire angle space of interest, and the candidate beams in the first set can have a type corresponding to type-III in

[0226] In Fig.33 operation 3314, a second set of candidate beams can be generated by the UE using the condition that the target TCI state TCIx is not (fully) outdated / expired and the SNR of TCIx is lower than Th_0. In this case, the UE can perform beam selection on a restricted angle space around the reference beam (direction) corresponding to TCIx. That is, the second set of candidate beams can include a relatively small number of candidate beams with a relatively small beam width to improve the link quality because the SNR of the target TCI state is low (<Th_0). For example, the second set of candidate beams can be generated by the UE using candidate beam pattern-C, i.e., Fig.29 the beam pattern 2912 in Fig.32 and the candidate beams of type-I in

[0227] In Fig.33 operation 3318, a third set of candidate beams can be generated by the UE based on the condition that the target TCI state TCIx is (fully) outdated / expired and the SNR of TCIx is lower than Th_0. In this case, the candidate beams in the third set can cover the entire angle range of interest and have a relatively small beam width to ensure the link quality. For example, the third set of candidate beams can be generated by the UE using candidate beam pattern-X, i.e., Fig.29 the beam pattern 2906 in Fig.32 and the candidate beams of type-I in

[0228] In Fig.33 operation 3320, a fourth set of candidate beams can be generated by the UE using candidate beam pattern-X, i.e., Fig.29 the beam pattern 2906 in Fig.32 to cover the entire angle space of interest and the candidate beams of type-II in

[0229] Fig.34 Fig.32 In one embodiment, the third set of beams and the fourth set of beams differ only in beam width, depending on the exact value of the SNR of the target TCI state and how it is compared with Th_0.

[0229] Fig.34Various embodiments according to the present disclosure are shown, in particular, Fig.33 The candidate beam selection of the embodiment described in . Beam group 3408 corresponds to the beams from Fig.33 The first set of candidate beams in operation 3310 in FIG. 3410 is a type-III candidate beam in mode-X. Beam set 3410 corresponds to the beams from Fig.33 The second set of candidate beams in operation 3314 in mode-C corresponds to the type-I candidate beams in mode-C. Beam group 3412 corresponds to the third set of candidate beams 3318, that is, the type-II candidate beams in mode-X. Beam group 3414 corresponds to the Fig.33 The fourth set of candidate beams in operation 3320, namely, type-II candidate beams in mode-X.

[0230] As before, the shaded circles 3402 in each group of beams 3408, 3410, 3412, and 3414 represent candidate beams. The shaded circles 3404 with triangles in the center represent reference receive beams / directions. The unshaded circles 3406 represent any remaining beams in the beam codebook.

[0231] Fig.35A and 35B 3500 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operations of flowchart 3500 may be implemented in a UE, for example Figure 3 UE 116 in.

[0232] Flowchart 3500 differs from flowchart 3300 based on the order in which the staleness state of the target TCI state and the SNR condition are considered. In flowchart 3300, the staleness state of the target TCI state is checked first, and then the SNR condition is checked. In flowchart 3500, the SNR of the target TCI is checked first, and then the staleness state is checked. It can be seen that this difference may result in different receive beam operation / selection strategies and / or different beam sets.

[0233] Flowchart 3500 begins at operation 3502, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3504, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 3500 proceeds from operation 3504 to operation 3506, where a receive beam corresponding to TCIx is selected.

[0234] If TCIx is unknown, then the flowchart 3500 proceeds from operation 3504 to operation 3508, where it is determined whether the SNR of TCIx is below a threshold. Operation 3508 serves as a global trigger event / condition in FIG. 35, such that if the SNR of TCIx is below Th_0, then a first beam type (e.g., Fig.32, and if the SNR of TCIx is higher than Th_0, a second beam type (e.g., Fig.32 Type-III wide beam in ).

[0235] If the SNR of TCIx is not below the threshold, the flowchart 3500 proceeds from operation 3508 to operation 3510, where another determination is made as to whether TCIx has been measured before. If TCIx has not been measured before, the flowchart 3500 proceeds from operation 3510 to operation 3512, where a beam search is performed on the fourth set of beams to determine a receive beam for TCIx.

[0236] Returning to operation 3510, if it is determined that TCIx was previously measured, the flowchart 3500 proceeds to operation 3514, where it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). If TCIx was not measured more than X ms ago, the flowchart 3500 proceeds to operation 3516, where a beam search is performed on the fifth set of beams to determine a receive beam for TCIx. However, if TCIx was measured more than X ms ago, the flowchart 3500 proceeds from operation 3514 to operation 3518, where a beam search is performed on the sixth set of beams to determine a receive beam for TCIx.

[0237] Returning to operation 3508, if it is determined that the SNR of TCIx is lower than the threshold Th_0, the flowchart 3500 proceeds to Fig.35B In operation 3520, it is determined in operation 3520 whether TCIx has been measured before. If TCIx has not been measured before, flowchart 3500 proceeds from operation 3520 to operation 3522, in which a beam search is performed on the first set of beams to determine the receive beam of TCIx. In operation 3522, the first set of candidate beams should cover the entire angular space of interest (e.g., 120 degrees in the azimuth domain of the UE and 90 degrees in the elevation domain of the UE). In this example, the candidate beams in the first set can correspond to mode-X and type-I candidate beams.

[0238] Returning to operation 3520, if it is determined that TCIx was measured before, the flowchart 3500 proceeds to operation 3524, in which it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). If TCIx was not measured more than X ms ago, the flowchart 3500 proceeds to operation 3526, in which a beam search is performed on the second set of beams to determine the receive beam of TCIx. In operation 3526, it is implied that the target TCI state is not (completely) outdated / expired, and the receive beam corresponding to the target TCI state can be used as a reference receive beam (direction) to narrow the angle range to be scanned. Therefore, in operation 3526, the UE searches on the second set of candidate beams to determine the receive beam of TCIx. The candidate beams in the second set can correspond to mode C obtained from Table 1, and a type-I beam given a reference receive beam (reference steering direction).

[0239] However, if TCIx was measured more than X ms ago, flowchart 3500 proceeds from operation 3524 to operation 3528, in which a beam search is performed on the third set of beams to determine the receive beam for TCIx. If the last measurement of the target / switched TCI state was performed by the UE more than X ms ago, the receive beam corresponding to the target TCI state may no longer be valid, so the UE will not use it as a reference receive beam and / or reference direction to narrow the angular space to be scanned. In operation 3528, a search is performed on the third set of candidate beams to identify the receive beam for TCIx, and in this non-limiting embodiment, the candidate beams in the third set may correspond to mode-X and type-I candidate beams. In this example, the first set of candidate beams and the third set of candidate beams may be the same because they are constructed under the same trigger event / condition. Note that they may include different candidate beams (different candidate beam modes and / or types) according to actual needs.

[0240] Operations 3510-3518 are similar to operations 3520-3528. Therefore, the design principles of the fourth, fifth, and sixth groups of candidate beams in operations 3512, 3516, and 3518 are similar to the design principles of the first, second, and third groups of candidate beams in operations 3522, 3526, and 3528, respectively. However, because the triggering conditions of operations 3510-3518 are different from the triggering conditions of operations 3520-3528, the candidate beams generated in operations 3512, 3516, and 3518 may have a larger beamwidth than the beams generated in operations 3522, 3526, and 3528. For example, in operation 3518, a search is performed on the sixth group of candidate beams to find a receive beam of the target TCI state TCIx, and the corresponding candidate beams may correspond to a mode-X (covering the entire angular space of interest) and a type-III candidate beam.

[0241] Typically, in flowchart 3500, in order to find a receive beam for TCIx, the UE may perform an exhaustive search of all candidate beams and select the one that results in the best performance metric. The performance metric may be based on received signal power, RSRP, RSRQ, SNR, and / or SINR. As another example, the UE may perform a search / measurement on a subset of beams among all candidate beams. The UE may then interpolate the search / measurement results from the subset of beams and select a receive beam from the candidate beams. The selected receive beam may or may not belong to the subset of beams. The measurements on the subset of beams may be based on received signal power, RSRP, RSRQ, SNR, and / or SINR.

[0242] In the aforementioned embodiments, various receive beam selection strategies are proposed for (unknown) TCI state switching, assuming fixed thresholds or criteria to characterize the detectability and obsolete status of a given TCI state. For example, in order to determine whether the target / switched TCI state is detectable during a switching period, the UE may compare the SNR of the target TCI state with a predefined threshold Th_0, which may be set to a fixed value, such as -3dB, throughout the process. As another example, assuming that the target TCI state has been measured by the UE at least once before, the UE may compare the last measurement of the target TCI state with a predefined time window X ms to determine their obsolete status. Here, X ms may correspond to a fixed value, such as 80ms. However, in practice, using a fixed threshold Th_0 and / or a fixed time window X ms to characterize the target TCI state may not achieve promising receive beam selection performance, especially when channel conditions vary. For example, in a certain time period, the channel may be highly correlated in time with a large channel coherence time, while in another time period, the channel may be independent. In this case, for a given channel realization, the target TCI state may be (completely) out-of-date / out-of-date, but for a different channel realization, the target TCI state is not (completely) out-of-date / out-of-date and may be used to determine the reference receive beam / direction, although the last measurement of the target TCI state was made by the UE a fixed X ms ago. Therefore, it may be necessary to adaptively configure the thresholds or criteria characterizing the detectability and out-of-date status of a given TCI state depending on various system settings such as propagation channel conditions. These embodiments are discussed in more detail in the subsequent figures.

[0243] Fig.36 3600 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operations of flowchart 3600 may be implemented in a UE, for example Figure 3 UE 116 in.

[0244] The receive beam selection strategy described in flowchart 3600 is based on the outdated state of the target TCI state and is similar to Fig.25A However, flowchart 3600 differs from flowchart 2500A in that it incorporates an adjustable time window for determining the obsolescence state of the target TCI state. That is, Fig.36 In this example, the UE is able to flexibly configure the obsolete state of a given TCI state to generate corresponding candidate measurement beams and find a receiving beam suitable for the target TCI state TCIx.

[0245] Flowchart 3600 begins at operation 3602, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3604, a determination is made as to whether TCIx is known. If TCIx is known, then flowchart 3600 proceeds from operation 3604 to operation 3606, where a receive beam corresponding to TCIx is selected. If TCIx is unknown, then flowchart 3600 proceeds from operation 3604 to operation 3608, where a determination is made as to whether TCIx has been previously measured.

[0246] If TCIx has not been measured before, the flowchart 3600 proceeds from operation 3608 to operation 3610, where a beam search is performed on the first set of beams and a receive beam is determined for TCIx.

[0247] If TCIx has been measured before, the flowchart 3600 proceeds from operation 3608 to operation 3612, where the time offset Δt is determined. In this embodiment of the present disclosure, the time offset parameter Δt may be a positive or negative number. For example, the time offset Δt may be implemented on the UE using a set of V discrete values, for example, Δt={Δt 0 , △t 1 ,…,△t V-1}. Table 3 gives a set of exemplary potential time offset values ​​(other values ​​are also possible depending on the actual implementation). For a given time slot (cycle) and / or channel implementation, the UE can select a time offset value from Table 3 and apply it in a subsequent operation 3614 to update the time window to characterize the outdated state of the target TCI state. For example, the UE can select a time offset value from Table 3 based on their mobility rate. If the UE moves quickly with a high absolute / angular velocity, the propagation channel will also change quickly, resulting in, for example, a relatively small channel coherence time. In this case, a relatively small time window may be required to characterize the outdated state of the target TCI state to ensure good link quality, although the overall beam search complexity may also increase. Therefore, the UE can select Δt from Table 3 1 = -35 as the time offset value to adjust / update the baseline X ms time window.

[0248] Table 3

[0249] <![CDATA[Δt 0 ]]> <![CDATA[Δt 1 ]]> … <![CDATA[Δt V-2 ]]> <![CDATA[Δt V-1 ]]> -40 -35 … 35 40

[0250] After determining the time offset, the flowchart 3600 proceeds to operation 3614, in which it is determined whether TCIx was measured more than X+Δt ms ago. In this operation, the UE applies the time offset value Δt to adjust / update the baseline Xms time window. The new time window then becomes X+Δt ms to characterize the outdated state of the given TCI state. If Δt=0, the UE will continue to use the X ms time window to characterize the outdated state of the given TCI state.

[0251] If TCIx is measured before greater than X+Δt ms, the target TCI state is considered to be (completely) out-of-date / out-of-date, causing the flowchart 3600 to proceed from operation 3614 to operation 3610. However, if TCIx is not measured before greater than X+Δt ms, the target TCI state is not considered to be (completely) out-of-date / out-of-date, causing the flowchart 3600 to proceed to operation 3616, where a beam search is performed on the second set of beams to determine a receive beam for TCIx.

[0252] The first and second sets of candidate beams in operations 3610 and 3616, respectively, may be selected by the UE similar to Fig.25A The candidate beams in the first and second groups in operations 3610 and 3616 are generated / constructed by those in operations 2510 and 2514 in . Since in this example, the UE only checks the outdated state without considering the SNR of the target TCI state, the candidate beams in the first and second groups in operations 3610 and 3616 are mainly different in terms of candidate beam patterns, which can be selected from a lookup table predetermined at the terminal. Table 4 gives an exemplary lookup table. The lookup table maps the candidate beam pattern to the last measurement time of the target TCI state and a specific information set that captures the necessary sensing information collected at the UE. Table 4 differs from Table 1 in that a time offset value is included in Table 4 to adjust the corresponding time windows of all rows. For example, if the last measurement of the target / switched TCI state was made by the UE at a time greater than X 3 +Δt ms but less than X 2 +Δt ms ago, and the UE's information set can be best represented by {Ψ 4}, then the second set of candidate beams can correspond to Fig.29 A mode-E candidate beam is formed around a reference receive beam corresponding to the target TCI state.

[0253] Table 4

[0254]

[0255] Fig.37 3700 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operations of flowchart 3700 may be implemented in a UE, for example Figure 3 UE 116 in.

[0256] The receive beam selection strategy described in flowchart 3700 is based on the SNR condition of the target / switching TCI state and is similar to Fig.30 However, flowchart 3700 differs from flowchart 3000 in that it incorporates an SNR offset value △γ to adaptively adjust / update the SNR threshold and thus flexibly configure the detectability of a given TCI state to generate corresponding candidate measurement beams, thereby finding a receiving beam suitable for the target TCI state TCIx.

[0257] Flowchart 3700 begins at operation 3702, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3704, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 3700 proceeds from operation 3704 to operation 3706, where a receive beam is selected corresponding to TCIx.

[0258] If TCIx is unknown, then flow chart 3700 proceeds from operation 3704 to operation 3708, where an SNR offset Δγ is determined. In one embodiment, the SNR offset Δγ may be positive or negative. For example, the SNR offset Δγ may be implemented at the UE using a set of U discrete values, e.g., Δγ = {Δγ 0 , △γ 1 ,…,△γ U-1}. In Table 5, a set of potential SNR offset values ​​are given (other values ​​are also possible depending on the actual implementation). For a given time slot (cycle) and / or channel implementation, in operation 3710, the UE may select an SNR offset value from Table 5 and apply it to update the SNR threshold to characterize the detectability of the target TCI state. For example, the UE may select an SNR offset value from Table 5 based on certain past measurements. Past measurements may correspond to one or more SNRs of the target TCI state measured in the past, for example, during the last few measurements and / or in the first few time slots. The sum, average and / or other forms of previously measured SNRs of the target TCI state may also be considered as past SNR measurements. For example, past SNR measurements of the target TCI state may be much higher than the baseline threshold Th0. In this case, a relatively large SNR threshold may better characterize the detectability of the target TCI state to reduce the overall beam search complexity. Therefore, the UE may select ΔYU-2=20 from Table 5 as the SNR offset value to adjust / update the baseline SNR threshold Th 0.

[0259] Table 5

[0260] <![CDATA[Δγ 0 ]]> <![CDATA[Δγ 1 ]]> … <![CDATA[Δγ U-2 ]]> <![CDATA[Δγ U-1 ]]> -25 -20 … 20 25

[0261] Flowchart 3700 proceeds from operation 3708 to operation 3710, where it is determined whether the SNR of TCIx is lower than Th0+Δγ. The SNR offset value is applied to adjust / update the baseline SNR threshold Th_0. The new SNR threshold may become Th_0+Δγ to characterize the detectability of a given TCI state. If Δγ=0, the UE will continue to use the baseline SNR threshold Th_0 to characterize the detectability of a given TCI state.

[0262] If the SNR of TCIx is not lower than Th_0+Δγ, the flowchart 3700 proceeds from operation 3710 to operation 3712, where a beam search is performed on the first set of beams to determine a receive beam of TCIx. However, if the SNR of TCIx is lower than Th_0+Δγ, the flowchart 3700 proceeds from operation 3710 to operation 3714, where a beam search is performed on the second set of beams to determine a receive beam of TCIx.

[0263] The first and second groups of candidate beams in operations 3712 and 3714 may be selected by the UE similar to Fig.30 . Since in this example, the UE only checks the SNR condition and does not further check the outdated state, the candidate beams in the first and second groups of candidate beams in operations 3712 and 3714 differ mainly in the candidate beam type, which can be selected from a lookup table implemented at the terminal. An exemplary lookup table is provided in Table 6, which maps the candidate beam type and / or the desired beam width to the exact SNR of the target TCI state. Table 6 differs from Table 2 in that an SNR offset value is included in Table 6 for adjusting the corresponding SNR thresholds of all rows. For example, if the SNR of the target TCI state exceeds Th_1+Δγ but is less than Th_2+Δγ, the desired beam width of the candidate beam can be θ from Table 6. 2 , and the candidate beams in the second group can correspond to Fig.32 In this case, the UE uses Mode-X and Type-III candidate beams in the second group to cover the entire angular range of interest.

[0264] Table 6

[0265]

[0266] In the subsequent Fig.38In 39, two additional algorithms supporting fast receive beam selection / operation strategies are developed for TCI state switching. In both algorithms, the UE checks the staleness and SNR conditions of the target TCI state to facilitate the receive beam search process under unknown TCI state switching. The thresholds and criteria for characterizing the staleness and detectability of the target TCI state can be flexibly configured by the UE based on past measurements, channel conditions, etc.

[0267] Fig.38 3800 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operations of flowchart 3800 may be implemented in a UE, for example Figure 3 UE 116 in.

[0268] Flowchart 3800 begins at operation 3802, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3804, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 3800 proceeds from operation 3804 to operation 3806, where a receive beam corresponding to TCIx is selected.

[0269] If TCIx is unknown, the flowchart 3800 proceeds from operation 3804 to operation 3808, where it is determined whether TCIx has been measured before. If TCIx has not been measured before, the flowchart 3800 proceeds from operation 3808 to operation 3810, where a beam search is performed on the first set of beams to determine a receive beam for TCIx.

[0270] Returning to operation 3808, if it is determined that TCIx was previously measured, the flowchart 3800 proceeds to operation 3812, where the time offset Δt is determined. In operation 3814, it is determined whether TCIx was measured more than X+Δt ms ago. If TCIx was not measured more than X+Δt ms ago, the flowchart 3800 proceeds from operation 3814 to operation 3816, where a beam search is performed on the second set of beams to determine a receive beam for TCIx.

[0271] Returning to operation 3814, if TCIx was measured more than X+Δt ms ago, the flowchart 3800 proceeds to operation 3818 and determines the SNR offset Δγ. In operation 3820, it is determined whether the SNR of TCIx is lower than Th_0+Δγ. If the SNR of TCIx is lower than Th_0+Δγ, the flowchart 3800 proceeds from operation 3820 to operation 3822, in which a beam search is performed on the third set of beams to determine the receive beam of TCIx. However, if the SNR of TCIx is not lower than Th_0+Δγ, the flowchart 3800 proceeds from operation 3820 to operation 3824, in which a beam search is performed on the fourth set of beams to determine the receive beam of TCIx.

[0272] The construction of the candidate beams in the first, second, third and fourth groups in operations 3810, 3816, 3822 and 3824, respectively, and their corresponding receive beam search processes are similar to Fig.33 3310, 3314, 3318, and 3320 in . However, flowchart 3800 differs from flowchart 3300 in that flowchart 3800 combines the time offset value Δt and the SNR offset value Δγ. The calculation of the time offset Δt and the SNR offset Δγ follows Fig.36 and 37 Those described in .

[0273] In operation 3814 of flowchart 3800, a time offset is applied to adjust / update a time window for characterizing an outdated state of a target TCI state. In operation 3820 of flowchart 3800, an SNR offset is applied to adjust / update an SNR threshold to characterize the detectability of a target TCI state. Operations 3814 and 3820 in flowchart 3800 are similar to operations 3614 in flowchart 3600 and operation 3710 in flowchart 3700, respectively.

[0274] Fig.39A and 39B 3900 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operation of flowchart 3900 can be implemented in a UE, for example Figure 3 UE 116 in.

[0275] Flowchart 3900 begins at operation 3902, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 3904, it is determined whether TCIx is known. If TCIx is known, flowchart 3900 proceeds from operation 3904 to operation 3906, where a receive beam corresponding to TCIx is selected. If TCIx is unknown, flowchart 3900 proceeds to operation 3908, where an SNR offset Δγ and a time offset Δt are determined.

[0276] In operation 3910, it is determined whether the SNR of TCIx is lower than Th_0+Δγ. If the SNR of TCIx is not lower than Th_0+Δγ, the flowchart 3900 proceeds to operation 3912 to determine whether TCIx has been measured before. If TCIx has not been measured before, the flowchart 3900 proceeds from operation 3912 to operation 3914, in which a beam search is performed on the fourth group of beams to determine a receive beam of TCIx. If TCIx has been measured before, the flowchart 3900 proceeds from operation 3912 to operation 3916, in which it is determined whether TCIx was measured before greater than X+Δt ms. If TCIx has not been measured before greater than X+Δt ms, the flowchart 3900 proceeds from operation 3916 to operation 3918, in which a beam search is performed on the fifth group of beams to determine a receive beam of TCIx. However, if TCIx was measured more than X+Δt ms ago, the flowchart 3900 proceeds from operation 3916 to operation 3920, where a beam search is performed on the sixth set of beams to determine a receive beam for TCIx.

[0277] Returning to operation 3910, if the SNR of TCIx is lower than Th_0+Δγ, the flowchart 3900 proceeds from operation 3910 to Fig.39BIn operation 3922, it is determined whether TCIx has been measured before. If TCIx has not been measured before, the flowchart 3900 proceeds to operation 3924, in which a beam search is performed on the first set of beams to determine a receive beam for TCIx. If TCIx has been measured before, the flowchart 3900 proceeds from operation 3922 to operation 3926, in which it is determined whether TCIx was measured more than X+Δt ms ago. If TCIx has not been measured more than X+Δt ms ago, the flowchart 3900 proceeds from operation 3926 to operation 3928, in which a beam search is performed on the second set of beams to determine a receive beam for TCIx. If TCIx was measured more than X+Δt ms ago, the flowchart 3900 proceeds from operation 3926 to operation 3930, where a beam search is performed on the third set of beams to determine a receive beam for TCIx.

[0278] In operations 3924, 3928, 3930, 3914, 3918, and 3920 of FIG. 39, the construction of the candidate beams in the first group, the second group, the third group, the fourth group, the fifth group, and the sixth group and their corresponding receive beam search processes correspond to Fig.35A and Fig.35B The construction and search of the first, second, third, fourth, fifth and sixth groups in operations 3522, 3526, 3528, 3512 and 3518 of Flowchart 3900 are as follows. The difference between Flowchart 3900 and Flowchart 3500 is that Flowchart 3900 combines the time offset value △t and the SNR offset value △γ. The calculation of the time offset △t and the SNR offset △γ follows Fig.36 and 37 Those described in .

[0279] In operation 3910 of flowchart 3900, an SNR offset is applied to adjust / update an SNR threshold to characterize the detectability of a target TCI state. In operations 3916 and 3926 of flowchart 3900, a time offset is applied to adjust / update a time window for an outdated state characterizing a target TCI state. Operation 3910 in flowchart 3900 is similar to operation 3710 in flowchart 3700, and operations 3916 and 3926 are similar to operation 3614 in flowchart 3600.

[0280] In some previous embodiments of the present disclosure, for a given instant in time, time period, time slot, or channel implementation, a receive beam selection is performed by the UE assuming an SNR threshold (e.g., Th_0) to characterize the detectability of a given TCI state, and / or a receive beam selection is performed by the UE assuming a time window (e.g., X ms) to characterize the obsolescence of a given TCI state, although in some cases the SNR threshold and time window may be adjusted / updated based on channel changes and / or past measurements. However, in some deployment scenarios, for a given instant in time, time period, time slot, or channel implementation, multiple (more than one) SNR thresholds (e.g., two thresholds Th_0 and Th_1) and / or multiple (more than one) time windows (e.g., two time windows X and Y ms) may be required to characterize the detectability and obsolescence of a given TCI state, respectively.

[0281] In the next embodiment, an algorithm flow chart explaining several receive beam selection strategies is given, assuming that the outdated state of the target TCI state is checked through two time windows, in this example, the two time windows are Yms and X ms satisfying Y>X. In this example, X ms can be considered as a baseline time window, and Y ms is an additional time window.

[0282] Fig.40 4000 is a flowchart of receiving beam selection according to various embodiments of the present disclosure. The operation of flowchart 4000 can be implemented in a UE, for example Figure 3 UE 116 in.

[0283] Flowchart 4000 begins at operation 4002, where an indication of a TCI state switch to TCI state x (TCIx) is received. At operation 4004, a determination is made as to whether TCIx is known. If TCIx is known, flowchart 4000 proceeds from operation 4004 to operation 4006, where a receive beam corresponding to TCIx is selected.

[0284] If TCIx is unknown, the flowchart 4000 proceeds from operation 4004 to operation 4008, where it is determined whether TCIx has been previously measured. If TCIx has not been previously measured, the flowchart 4000 proceeds from operation 4008 to operation 4010, where a beam search is performed on the first set of beams to determine a receive beam for TCIx.

[0285] Returning to operation 4008, if it is determined that TCIx was previously measured, flowchart 4000 proceeds to operation 4012, where it is determined whether TCIx was measured more than X ms ago (i.e., more than a predetermined amount of time ago). If TCIx was not measured more than X ms ago, flowchart 4000 proceeds to operation 4014, where a beam search is performed on the second set of beams to determine a receive beam for TCIx.

[0286] However, if TCIx was measured more than X ms ago, the flowchart 4000 proceeds from operation 4012 to operation 4016, where it is determined whether TCIx was measured more than Y ms ago (i.e., more than a predetermined amount of time ago in the case of Y>X). If TCIx was not measured more than Y ms ago, the flowchart 4000 proceeds to operation 4018, where it is determined whether the SNR of TCIx is below a threshold value Th_0.

[0287] If the SNR of TCIx is lower than the threshold, the flowchart 4000 proceeds to operation 4022, in which a beam search is performed on the fifth group of beams to determine the receive beam of TCIx. However, if the SNR of TCIx is not lower than the threshold, the flowchart 4000 proceeds from operation 4018 to operation 4020, in which a beam search is performed on the sixth group of beams to determine the receive beam of TCIx.

[0288] Returning to operation 4016, if it is determined that TCIx is measured before more than Y ms, the flowchart 4000 proceeds to operation 4024, where it is determined whether the SNR of TCIx is lower than the second threshold Th_1. If the SNR of TCIx is lower than the second threshold, the flowchart 4000 proceeds to operation 4028, where a beam search is performed on the third group of beams to determine the receive beam of TCIx. However, if the SNR of TCIx is not lower than the second threshold, the flowchart 4000 proceeds from operation 4024 to operation 4026, where a beam search is performed on the fourth group of beams to determine the receive beam of TCIx.

[0289] The construction of the candidate beams in the first, second, third, fourth, fifth, and sixth groups in flowchart 4000 is similar to the construction of the candidate beams in the first, second, third, fourth, fifth, and sixth groups in flowchart 4000, respectively. The beam search procedure is also similar.

[0290] In flow chart 4000, in operation 4016, the UE further checks whether the last measurement of the target TCI state was performed by the UE more than Y ms ago, where Y>X. If the last measurement of the target TCI state was performed by the UE more than X ms ago but less than Y ms ago, the target TCI state is still considered not to be (completely) out-of-date / out-of-date, so that the receive beam corresponding to the target TCI state can still be used as a reference beam (direction) to limit the angular range of interest to be scanned.

[0291] Note that in addition to the baseline X ms time window, a second time window Y ms, or multiple time windows (more than two) can be applied to the algorithms in flowcharts 2500a, 3300, 3500, 3600, 3700, 3800, 3900, and 4000, for the UE to further check the outdated state of the target TCI state and perform corresponding receive beam operations. In addition to the baseline SNR threshold Th_0, a second SNR threshold, such as Th_1, or multiple SNR thresholds (more than two) can also be applied to the algorithms in flowcharts 3000, 3300, 3500, 3600, 3700, 3800, 3900, and 4000, for the UE to further check the detectability of the target TCI state and perform corresponding receive beam selection strategies.

[0292] Fig.41 Various embodiments according to the present disclosure (particularly according to Fig.40 A conceptual example of selecting a candidate beam for the fifth group of beams and the sixth group of beams according to the embodiment described in FIG. 4A . Beam group 4108 corresponds to the candidate beams from Fig.40 The fifth set of candidate beams in operation 4022 in FIG. 41 is a type-I candidate beam in mode-A. Beam group 4110 corresponds to the candidate beams from Fig.40 The sixth set of candidate beams of operation 4020, for example, type-II candidate beams in mode-A.

[0293] As before, the shaded circles 4102 in each set of beams 4108 and 4110 represent candidate beams. The shaded circles 4104 with a triangle in the center represent reference receive beams / directions. The unshaded circles 4106 represent any remaining beams in the beam codebook.

[0294] Although the detailed design process is explicitly discussed for unknown TCI state switching, the receive beam selection strategy described here can still be applied to various application scenarios. For example, based on SNR, reference beams (directions) are used to narrow the angular search space and adjust beam-specific parameters such as beam width, beam shape, etc. It can also be used for initial access procedures and inter-cell measurements based on beamforming. Several related use cases are introduced and discussed below.

[0295] Use case 1: Fast receive beam selection under unknown TCI state switching. Due to sudden link failure, congestion, etc., the BS or network can change the TCI state and send a corresponding command to the UE to inform the UE about the switched TCI state. If the switched TCI state is unknown to the UE, so that the UE has never measured the switched TCI state before, or the last measurement is completely outdated, the UE may have to perform a full receive beam scan to find the receive beam of the switched TCI state. The proposed receive beam operation / selection strategy can be applied here to reduce the search complexity, access delay and interruption rate.

[0296] Use case 2: Fast receive beam selection during initial access. In the third phase of the initial access procedure, the UE refines the receive beam by scanning / searching the receive beam over a given angle space. By implementing the proposed receive beam manipulation / selection strategy at the UE, the receive beam refinement in p-3 can be greatly facilitated and the corresponding initial access delay can be significantly reduced.

[0297] Use case 3: Inter-cell measurements based on directional beamforming. To perform inter-cell measurements, the UE may need to form narrow measurement beams to ensure sufficient link quality. A relatively large number of narrow measurement beams may be required to cover the entire angular range. Scanning all narrow measurement beams may be time-consuming and power-intensive and may introduce additional delays. Obviously, the proposed receive beam manipulation / selection strategy can also be applied here to facilitate the inter-cell measurement process.

[0298] Use Case 4: Beam Search in Several Mobility Scenarios such as Handover, RRC Reconnection and RRC Re-establishment. In many mobility configurations, such as handover and RRC reconnection / re-establishment, receive beam search is often performed at the UE to find the best cell / beam to connect to or camp on. If the target cell or target frequency is unknown to the UE such that the UE has never measured the target cell or target frequency before the last measurement is completely out of date, a full receive beam search may be required to correctly handle various mobility conditions.

[0299] Transmit beam management for mobile terminals

[0300] As mentioned earlier, the asymmetry of the downlink and uplink link budgets limits the radio coverage of the UE. To alleviate the asymmetry of the downlink and uplink link budgets, the UE can use a wide Rx beam to receive downlink signals and a narrow Tx beam to send uplink signals, because the narrow Tx beam has a higher beam gain than the wide Rx beam. The wide Rx beam is beneficial for supporting robust mobility and reducing the time required for beam search. Since the uplink is the bottleneck of cell coverage, the narrow Tx beam can be used to extend the uplink coverage and effectively increase the cell coverage.

[0301] Fig.42 The asymmetry of downlink and uplink link budget constraints of UE radio coverage according to various embodiments of the present disclosure is shown. In 4200a, a UE receiving signals in the downlink using a wide Rx beam has sufficient downlink coverage, represented by an area containing the BS and the UE. In 4200b, a UE transmitting signals in the uplink using a wide Tx beam has insufficient uplink coverage, represented by an area containing only the UE. In 4200c, a UE transmitting signals in the uplink using a narrow Tx beam has sufficient uplink coverage, represented by an area containing the BS and the UE.

[0302] The UE may need to switch between a wide Tx beam (beam type 1) and a narrow Tx beam (beam type 2) depending on channel conditions. Some subsequent embodiments describe methods that enable the UE to detect conditions for switching from one Tx beam type to another Tx beam type. The beam type is used to indicate beam gain and beam width characteristics. Although two beam types are assumed in the embodiments of the present disclosure, these embodiments may also be applied to beamforming systems with more than two beam types.

[0303] Fig.43 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 4300 may be implemented in a UE, for example Figure 3 UE 116 in.

[0304] Flowchart 4300 begins with operation 4302, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive a master information block (MIB) to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0305] In operation 4304, a physical random access channel (PRACH) is transmitted with Tx beam type 1. The transmit beam may be the same spatial filter as the spatial filter used for the receive beam to receive SSB or CSI-RS. In some embodiments, operation 4304 occurs after receiving other system information, such as SIB1 using the same receive beam in operation 4302.

[0306] In operation 4306, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4300 proceeds to operation 4308, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Examples of subsequent transmissions include physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), and PRACH transmissions. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0307] In operation 4306, if a RAR corresponding to the transmitted PRACH is not received, then flowchart 4300 proceeds to operation 4310, where it is determined whether the maximum transmit power has been reached. If the maximum transmit power has not been reached, flowchart 4300 proceeds to operation 4312, where the transmit power for the PRACH is increased before returning to operation 4304.

[0308] Returning to operation 4310, if it is determined that the maximum power is reached, flowchart 4300 proceeds to operation 4314, and PRACH is transmitted with a transmit beam of type 2. In some embodiments, PRACH may be transmitted with the maximum power or the most recently used transmit power. In some embodiments, the transmit beam of type 2 has similar spatial parameters to the current receive beam for SSB or CSI-RS reception (i.e., quasi-co-location of type D as defined in TS 38.214). In addition, a suitable transmit beam or optimal Tx beam of type 2 may be determined by first determining a suitable or optimal receive beam of type 2 via reciprocity or beam correspondence, for example, by performing receive beam scanning / measurement using a type 2 beam. In operation 4302, receive beam type 2 measurements may be performed using SSB or CSI-RS signals received using a receive beam of type 1. Measurement and determination of the receive beam of type 2 may also be performed before the conditions for using a transmit beam of type 2 are met to reduce waiting time. The candidate reception beams of type 2 are generally a subset of all reception beams of type 2, for example, a sub-beam of a reception beam of type 1 for receiving SSB or CSI-RS in operation 4302, i.e., a hierarchical codebook having reception beams of type 1 in the first layer and reception beams of type 2 in the second layer. In operation 4302, the candidate reception beams of type 2 may be considered to be quasi-co-located with a reception beam of type D having a reception beam of type 1 for receiving SSB or CSI-RS.

[0309] At operation 4316, it is determined whether a RAR corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4300 proceeds to operation 4308, at which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0310] If, in operation 4316, it is determined that a RAR corresponding to the transmitted PRACH has not been received, then flowchart 4300 proceeds to operation 4318, in which it is determined whether the maximum number of attempts has been reached. If the maximum number of attempts has not been reached, flowchart 4300 returns to operation 4314. However, if the maximum number of attempts has been reached in operation 4318, flowchart 4300 continues to operation 4320, in which other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed. Thus, PRACH transmissions using the same TX beam of type 2 are repeated until the random access procedure is successful, or until the maximum number of PRACH transmissions configured by the network is reached.

[0311] If the SSB or CSI-RS is received using a type 2 receive beam (ie, a narrow receive beam) in operation 4302 , a type 2 transmit beam is used for PRACH transmission in operation 4304 , ie, a type 1 transmit beam is not used.

[0312] Fig.44 Another flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 4400 may be implemented in a UE, for example Figure 3 UE116 in.

[0313] Flowchart 4400 begins with operation 4402, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive a master information block (MIB) to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0314] In operation 4404, a physical random access channel (PRACH) is transmitted with Tx beam type 1. The transmit beam may be the same spatial filter as the spatial filter used for the receive beam to receive SSB or CSI-RS. In some embodiments, operation 4404 occurs after receiving other system information, such as SIB1 using the same receive beam in operation 4402.

[0315] In operation 4406, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4400 proceeds to operation 4408, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 4406 to operation 4408, the same transmit beam used in operation 4404 is used in operation 4408. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0316] In operation 4406, if a RAR corresponding to the transmitted PRACH is not received, then flowchart 4400 proceeds to operation 4410, where it is determined whether the maximum transmit power has been reached. If the maximum transmit power has not been reached, flowchart 4400 proceeds to operation 4412, where the transmit power for the PRACH is increased before returning to operation 4404.

[0317] Returning to operation 4410, if it is determined that the maximum power is reached, the flowchart 4400 proceeds to operation 4414 and the PRACH is transmitted with a transmit beam of type 2. In some embodiments, the PRACH may be transmitted with the maximum power or the most recently used transmit power. In some embodiments, the transmit beam of type 2 has similar spatial parameters as the current receive beam for SSB or CSI-RS reception (i.e., quasi-co-location of type D as defined in TS 38.214).

[0318] At operation 4416, it is determined whether a RAR corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4400 proceeds to operation 4408, where it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 4416 to operation 4408, the same transmit beam used in operation 4414 is used in operation 4408. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0319] If, in operation 4416, it is determined that a RAR corresponding to the transmitted PRACH has not been received, then flowchart 4400 proceeds to operation 4418, where it is determined whether the maximum number of attempts has been reached. If the maximum number of attempts has not been reached, flowchart 4400 proceeds to operation 4419 and switches to another type 2 transmit beam before returning to operation 4414. However, if the maximum number of attempts has been reached in operation 4418, flowchart 4400 continues to operation 4420, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed. Thus, the transmit beam switching between type 2 beams may be repeated until the random access procedure is successful, or until the maximum number of PRACH transmissions configured by the network is reached.

[0320] If the SSB or CSI-RS is received using a type 2 receive beam (ie, a narrow receive beam) in operation 4402 , a type 2 transmit beam is used for PRACH transmission in operation 4404 , ie, a type 1 transmit beam is not used.

[0321] Fig.45 Another flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 4500 may be implemented in a UE, for example Figure 3 UE116 in.

[0322] Flowchart 4500 begins with operation 4502, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive a master information block (MIB) to obtain information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0323] In operation 4504, a physical random access channel (PRACH) is transmitted with Tx beam type 1. The transmit beam may be the same spatial filter as the spatial filter used for the receive beam to receive SSB or CSI-RS. In some embodiments, operation 4504 occurs after receiving other system information, such as SIB1 using the same receive beam in operation 4502.

[0324] In operation 4506, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4500 proceeds to operation 4508, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 4506 to operation 4508, the same transmit beam used in operation 4504 is used in operation 4508. Examples of subsequent transmissions include physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), and PRACH transmissions. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0325] In operation 4506, if the RAR corresponding to the transmitted PRACH is not received, the flowchart 4500 proceeds to operation 4510, in which the PRACH is transmitted with a transmit beam of type 2. In some embodiments, the PRACH may be transmitted with the most recently used transmit power. In some embodiments, the transmit beam of type 2 has similar spatial parameters as the current receive beam for SSB or CSI-RS reception (i.e., quasi-co-location of type D as defined in TS 38.214). In addition, a suitable transmit beam or optimal Tx beam of type 2 may be determined by first determining a suitable or optimal receive beam of type 2 via reciprocity or beam correspondence, for example, by performing receive beam scanning / measurement using a type 2 beam. In operation 4502, receive beam type 2 measurements may be performed using SSB or CSI-RS signals received using a receive beam of type 1. Measurement and determination of the receive beam of type 2 may also be performed before the conditions for using a transmit beam of type 2 are met to reduce waiting time. The candidate reception beams of type 2 are generally a subset of all reception beams of type 2, for example, a sub-beam of a reception beam of type 1 for receiving SSB or CSI-RS in operation 4502, i.e., a hierarchical codebook having reception beams of type 1 in the first layer and reception beams of type 2 in the second layer. In operation 4502, the candidate reception beams of type 2 may be considered to be quasi-co-located with a reception beam of type D having a reception beam of type 1 for receiving SSB or CSI-RS.

[0326] Flowchart 4500 proceeds from operation 4510 to operation 4512, where it is determined whether a RAR corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, flowchart 4500 proceeds to operation 4508, where it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 4512 to operation 4508, the same transmit beam used in operation 4510 is used in operation 4508. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0327] If, in operation 4512, it is determined that a RAR corresponding to the transmitted PRACH has not been received, then the flowchart 4500 proceeds to operation 4514, where it is determined whether a maximum number of attempts has been reached. If, in operation 4514, the maximum number of attempts has been reached, then the flowchart 4500 continues to operation 4516, where other actions may be performed (e.g., searching for an alternative SSB, cell, or network). If, in operation 4514, the maximum number of attempts has not been reached, then the flowchart 4500 proceeds to operation 4518, where it is determined whether a maximum power has been reached. If the maximum power has been reached, then the flowchart 4500 returns to operation 4510. If the maximum power has not been reached, then the flowchart 4500 proceeds to operation 4520, where the power for the PRACH is increased before returning to operation 4510. Therefore, PRACH transmissions using the same TX beam of type 2 are repeated until the random access procedure succeeds, or until the maximum number of PRACH transmissions configured by the network is reached.

[0328] If the SSB or CSI-RS is received using a type 2 receive beam (ie, a narrow receive beam) in operation 4502, a type 2 transmit beam is used for PRACH transmission in operation 4504, ie, a type 1 transmit beam is not used.

[0329] Fig.46 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 4600 may be implemented in a UE, for example Figure 3 UE 116 in.

[0330] Flowchart 4600 begins with operation 4602, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive the MIB to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0331] At operation 4604, a physical random access channel (PRACH) is transmitted with Tx beam type 1. The transmit beam may be the same spatial filter as that used for the receive beam to receive SSB or CSI-RS. In some embodiments, operation 4604 occurs after receiving other system information, such as SIB1 using the same receive beam in operation 4602.

[0332] In operation 4606, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4600 proceeds to operation 4608, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 4606 to operation 4608, the same TX beam used in operation 4604 is used in operation 4608. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0333] In operation 4606, if a RAR corresponding to the transmitted PRACH is not received, flowchart 4600 proceeds to operation 4610, where the PRACH is transmitted with a transmit beam of type 2. In some embodiments, the PRACH may be transmitted with a most recently used transmit power. In some embodiments, the transmit beam of type 2 has similar spatial parameters as the current receive beam for SSB or CSI-RS reception (i.e., quasi-co-location of type D as defined in TS 38.214).

[0334] In operation 4612, it is determined whether a RAR corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 4600 proceeds to operation 4608, and in operation 4608, it is determined that the transmission beam in the subsequent transmission is the same type as the transmission beam used for the last PRACH transmission. Therefore, when proceeding from operation 4612 to operation 4608, the same transmission beam used in operation 4610 is used in operation 4608.

[0335] In operation 4612, if a RAR corresponding to the transmitted PRACH is not received, the flowchart 4600 proceeds to operation 4614, where it is determined whether the maximum number of attempts has been reached. If the maximum number of attempts has been reached, the flowchart 4600 proceeds to operation 4616, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed. However, if the maximum number of attempts has not been reached in operation 4614, the flowchart 4600 proceeds to operation 4618, where it is determined whether any type 2 candidate transmit beams remain. If a type 2 transmit beam remains, the flowchart 4600 switches to another type 2 transmit beam in operation 4620 before returning to operation 4610.

[0336] If it is determined at operation 4618 that no candidate transmit beams of type 2 remain, flowchart 4600 proceeds to operation 4622, where it is determined whether the maximum power has been reached. If the maximum power has been reached, flowchart 4600 proceeds to operation 4624, where the candidate transmit beams of type 2 are reset before proceeding to operation 4620. If the maximum power has not been reached at operation 4622, flowchart 4600 proceeds to operation 4626, where the transmit power for PRACH is increased before continuing to operation 4610.

[0337] Therefore, if the UE does not receive the corresponding RAR in operation 4612, the UE may switch to another transmit beam of type 2 in operation 4620, and transmit PRACH with the same Tx power in operation 4610. Transmit beam switching between type 2 beams may be repeated until one of the following conditions is met.

[0338] Condition 1: The random access procedure is successful. The UE uses the same type 2 TX beam as used for subsequent PRACH transmissions (until new configuration or indicated by the network).

[0339] Condition 2: The maximum number of PRACH transmissions configured by the network is reached.

[0340] Condition 3: All candidate transmit beams of type 2 that are QCLed in type D have been used for PRACH transmission relative to the current receive beam used for SSB or CSI-RS reception. For example, if the remaining transmit beams are considered to have a low probability of success, it is also possible to beam scan only a subset of all such type 2 transmit beams.

[0341] If, in operation 4612, the UE does not receive the corresponding RAR and condition (3) is satisfied, but condition (2) has not been satisfied, the UE repeats the transmission beam scanning with beam type 2 for PRACH transmission with power increased. If the random access procedure is successful using PRACH transmission with power increased, the UE uses the same type 2 transmission beam as used for PRACH transmission for subsequent transmissions (until new configuration or indicated by the network).

[0342] If the UE receives an SSB or CSI-RS with Rx beam type 2 (narrow Rx beam), the UE uses Tx beam type 2 for PRACH transmission, that is, does not use Tx beam type 1.

[0343] According to an embodiment of the present disclosure, after the UE has determined to use a type 2 Tx beam and a type 1 Rx beam, the UE also identifies a condition for switching from a type 2 Tx beam to a type 1 Tx beam, because channel conditions may change over time. The condition for switching may be based on signal strength or quality, as discussed in some embodiments below.

[0344] Fig.47 4700 is a flowchart showing switching between type 1 and type 2 transmit beams based on signal strength or quality according to various embodiments of the present disclosure. The operations of flowchart 4700 may be implemented in a UE, for example Figure 3 UE 116 in.

[0345] Flowchart 4700 begins with operation 4702, where wireless communications are performed using a receive beam of type 1 and a transmit beam of type 2. In operation 4704, it is determined whether the signal strength or quality of the receive beam is higher than a threshold. Examples of signal strength or quality may include RSRP, SNR, or SINR of a received signal based on a current receive beam. If it is determined in operation 4704 that the signal strength or quality of the receive beam is higher than the threshold, flowchart 4700 proceeds to operation 4706, where the transmit beam is switched from a transmit beam of type 2 to a transmit beam of type 1. However, if it is determined in operation 4704 that the signal strength or quality of the receive beam is not higher than the threshold, flowchart 4700 proceeds to operation 4708, where the transmit beam of type 2 is still used.

[0346] Signal strength or quality may be a condition because a type 2 transmit beam is needed to improve the signal strength or quality. When the condition is met, the type 1 transmit beam to be switched to should have similar spatial parameters as the type 2 transmit beam (i.e., quasi-co-location of type D as defined in TS 38.214). In the case of implementing a hierarchical codebook, the type 1 transmit beam is the parent beam of the type 2 transmit beam.

[0347] Fig.48 4800 is a flowchart showing switching between type 1 and type 2 transmission beams based on the modulation and coding scheme of the PUSCH according to various embodiments of the present disclosure. The operations of flowchart 4800 may be implemented in a UE, for example Figure 3 UE116 in.

[0348] Flowchart 4800 begins with operation 4802, wireless communication is performed using a receive beam of type 1 and a transmit beam of type 2. In operation 4804, it is determined whether the MCS for PUSCH is higher than a threshold. If the MCS for PUSCH is higher than the threshold, flowchart 4800 proceeds to operation 4806, in which the transmit beam may be switched from the transmit beam of type 2 to the transmit beam of type 1. However, if it is determined in operation 4804 that the MCS for PUSCH is not higher than the threshold, flowchart 4800 proceeds to operation 4808, in which the transmit beam of type 2 is still used.

[0349] MCS can be a condition because a higher MCS scheduled by the base station means that the received signal at the base station is high enough that switching to a type 1 transmit beam will not harm the uplink connection.

[0350] Assuming that according to the embodiments of the present disclosure, the UE has determined to use a transmit beam of type 1 together with a receive beam of type 1, the UE also needs to identify a condition for switching from a transmit beam of type 1 to a transmit beam of type 2, because channel conditions may change over time. Similar principles as shown in the previous two flowcharts may also be applied to enable conditional determination to switch from a transmit beam of type 1 to a transmit beam of type 2, as shown below Fig.49 and 50 shown.

[0351] In addition, when the conditions are met, the type 2 transmit beam to be switched to should have similar spatial parameters as the type 1 transmit beam (i.e., quasi-co-location of type D defined in TS 38.214). In the case of implementing a hierarchical codebook, the type 2 transmit beam is a sub-beam of the type 1 transmit beam. As in the previous embodiment, a suitable or optimal transmit beam of type 2 can be determined by determining a suitable or optimal receive beam of type 2 (reciprocity or beam correspondence). The measurement and determination of the type 2 receive beam can also be performed before the conditions for using the type 2 transmit beam are met to reduce waiting time.

[0352] Fig.49 Another flowchart for switching between type 1 and type 2 transmit beams based on signal strength or quality according to various embodiments of the present disclosure is shown. The operations of flowchart 4900 may be implemented in a UE, for example Figure 3 UE116 in.

[0353] Flowchart 4900 begins with operation 4902, where wireless communications are performed using a receive beam of type 1 and a transmit beam of type 1. In operation 4904, it is determined whether the signal strength or quality of the receive beam is below a threshold. Examples of signal strength or quality may include RSRP, SNR, or SINR of a received signal based on a current receive beam. If it is determined in operation 4904 that the signal strength or quality of the receive beam is below the threshold, flowchart 4900 proceeds to operation 4906, where the transmit beam is switched from a transmit beam of type 1 to a transmit beam of type 2. However, if it is determined in operation 4904 that the signal strength or quality of the receive beam is not below the threshold, flowchart 4900 proceeds to operation 4908, where the transmit beam of type 1 is still used.

[0354] Fig.50 Another flowchart of switching between type 1 and type 2 transmit beams based on the modulation and coding scheme of the PUSCH according to various embodiments of the present disclosure is shown. The operations of flowchart 5000 may be implemented in a UE, for example Figure 3 UE 116 in.

[0355] Flowchart 5000 starts with operation 5002, wireless communication is performed using a type 1 receive beam and a type 1 transmit beam. In operation 5004, it is determined whether the MCS for the PUSCH is lower than a threshold. If the MCS for the PUSCH is lower than the threshold, flowchart 5000 proceeds to operation 5006, in which the transmit beam may be switched from the type 1 transmit beam to the type 2 transmit beam. However, if it is determined in operation 5004 that the MCS for the PUSCH is not lower than the threshold, flowchart 5000 proceeds to operation 5008, in which the type 1 transmit beam is still used.

[0356] The RRC message IE PUCCH-SpatialRelationInfo (TS 38.331) is used to configure the spatial setting of PUCCH transmission and the parameters of PUCCH power control. With respect to the Rx beam used by the UE to receive the configured reference signal, the RRC configuration parameter referenceSignal in PUCCH-SpatialRelationInfo (TS 38.331 & TS 38.214) indicates the spatial setting reference for PUCCH transmission. Table 7 summarizes how the UE determines the Tx beam type for PUCCH transmission based on the Rx beam type used to receive the configured reference signal and the embodiments in the present disclosure. In particular, if Rx beam type 1 is used to receive the RS corresponding to referenceSignal in PUCCH-SpatialRelationInfo, then according to Figure 44-50 In the described embodiment, the UE determines the Tx beam type for PUCCH transmission. If Rx beam type 2 is used to receive the RS corresponding to referenceSignal in PUCCH-SpatialRelationInfo, the UE uses Tx beam type 2 for PUCCH transmission.

[0357] Table 7

[0358]

[0359] The same method for determining the Tx beam type for PUCCH transmission can also be applied to SRS transmission, as shown in Table 8. RRC message IE SRS-SpatialRelationInfo is used to indicate the configuration of the spatial relationship between the reference RS and the target SRS. The reference RS can be SSB / CSI-RS / SRS (TS 38.331). If Rx beam type 1 is used to receive the RS corresponding to the referenceSignal in SRS-SpatialRelationInfo, then according to Figure 44-50 In the described embodiment, the UE determines the Tx beam type for SRS transmission. If Rx beam type 2 is used to receive the RS corresponding to referenceSignal in SRS-SpatialRelationInfo, the UE uses Tx beam type 2 for SRS transmission.

[0360] Table 8

[0361]

[0362] According to the DCI format (TS 38.214, TS 38.212), the Tx beam used for PUSCH transmission is determined by the TX beam used for PUSCH transmission or SRS transmission. Therefore, the embodiments described in Table 7 and Table 8 can be used to determine the Tx beam used for PUSCH transmission.

[0363] Fig.51 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 5100 may be implemented in a UE, for example Figure 3 UE 116 in.

[0364] Flowchart 5100 begins with operation 5102, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive the MIB to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0365] At operation 5104, a physical random access channel (PRACH) is transmitted with Tx beam type 1. The transmit beam may be the same spatial filter as the spatial filter used for the receive beam to receive SSB or CSI-RS. In some embodiments, operation 5104 occurs after receiving other system information, such as SIB1 using the same receive beam in operation 5102.

[0366] In operation 5106, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 5100 proceeds to operation 5108, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5106 to operation 5108, the same TX beam used in operation 5104 is used in operation 5108. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0367] In operation 5106, if a RAR corresponding to the transmitted PRACH is not received, the flowchart 5100 proceeds to operation 5110, in which it is determined whether a predetermined number of transmission attempts has been reached. If the predetermined number of transmission attempts has been reached, the flowchart 5100 proceeds to operation 5112, in which a transmission power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmission power as before is used, and the flowchart 5100 returns to operation 5104 to transmit the PRACH with a transmission beam of type 1 using the power selected in operation 5112.

[0368] In operation 5110, if it is determined that the predetermined number of transmission attempts has not been reached, the flowchart 5100 proceeds to operation 5114, in which the PRACH is transmitted using a transmission beam of type 2. In some embodiments, the transmission beam of type 2 should have similar spatial parameters as the current reception beam for SSB or CSI-RS reception (i.e., quasi-co-location of type D as defined in TS 38.214).

[0369] The flowchart 5100 then proceeds to operation 5116, where it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 5100 proceeds to operation 5108, where it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5116 to operation 5108, the same TX beam used in operation 5114 is used in operation 5108. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0370] In operation 5116, if a RAR corresponding to the transmitted PRACH is not received, the flowchart 5100 proceeds to operation 5118, where it is determined whether the maximum number of transmission attempts has been reached. If the maximum number of transmission attempts has been reached, the flowchart 5100 proceeds to operation 5120, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed.

[0371] In operation 5118, if it is determined that the maximum number of transmit attempts has not been reached, the flowchart 5100 proceeds to operation 5122, where it is determined whether any type 2 candidate transmit beams remain. If type 2 transmit beams remain, the flowchart 5100 switches to another type 2 transmit beam in operation 5124 before returning to operation 5114.

[0372] In operation 5122, if it is determined that there are no candidate transmit beams of type 2 remaining, then the flowchart 5100 proceeds to operation 5126, where a transmit power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmit power as before is used, and the flowchart 5100 returns to operation 5114.

[0373] Therefore, the transmit beam switching between type 2 beams may be repeated until the random access procedure is successful, or until the maximum number of PRACH transmissions configured by the network is reached, or if all candidate Tx beams of type 2 that are QCL in type D relative to the current Rx beam used for SSB or CSI-RS reception have been used for PRACH transmission. For example, if the remaining transmit beams are considered to have a low probability of success, it is also possible to beam scan only a subset of all such type 2 transmit beams. If, after completing the Tx beam type 2 scan, the UE does not receive a corresponding RAR, the UE may increase the transmit power for PRACH transmission (if the maximum power has not been reached) and repeat the transmit beam scan with beam type 2 with the increased power. If the random access procedure is successful in the PRACH transmission with increased power, the UE uses the same type 2 transmit beam as for the PRACH transmission for subsequent transmissions (until new configuration, or indicated by the network).

[0374] Instead of performing switching on a type-2 transmit beam, the UE may also only use a type-2 transmit beam that is determined from measurements of a type-2 receive beam using reciprocity or beam correspondence as described in the previous embodiments.

[0375] If the UE receives an SSB or CSI-RS with reception beam type 2 (narrow Rx beam), the UE uses transmission beam type 2 for PRACH transmission, i.e., does not use transmission beam type 1.

[0376] Fig.52 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 5200 may be implemented in a UE, for example Figure 3 UE 116 in.

[0377] Flowchart 5200 begins with operation 5202, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive the MIB to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0378] In operation 5204, it is determined whether the signal strength or quality of the received SSB or CSI-RS is above a threshold. In some embodiments, the signal strength or quality is determined by RSRP, SNR, SINR. The determination in operation 5204 determines whether a type 1 or type 2 transmit beam is used for PRACH transmission. If the received signal strength or quality is greater than the threshold, the flowchart 5200 proceeds to operation 5206, and the PRACH is transmitted with a type 1 transmit beam.

[0379] In operation 5208, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 5200 proceeds to operation 5210, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5208 to operation 5210, the same TX beam used in operation 5206 is used in operation 5210. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0380] In operation 5208, if the RAR corresponding to the transmitted PRACH is not received, the flowchart 5200 proceeds to operation 5212, in which it is determined whether the maximum number of attempts (or a predetermined number of times) has been reached. If the maximum number of attempts has not been reached in operation 5212, the flowchart 5200 proceeds to operation 5214, in which a transmit power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmit power as before is used, and the flowchart 5200 returns to operation 5206 to transmit the PRACH using a transmit beam of type 1 and the power selected in operation 5214.

[0381] In operation 5212, if it is determined that the maximum number of attempts has been reached, flowchart 5200 proceeds to operation 5216, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed.

[0382] Returning to operation 5204, if it is determined that the signal strength or quality of the received SSB or CSI-RS is not higher than the threshold, the flowchart 5200 proceeds to operation 5218, and the PRACH is transmitted with a transmit beam of type 2. Thereafter, it is determined in operation 5220 whether a random access response (RAR) corresponding to the transmitted PRACH is received. If the RAR corresponding to the transmitted PRACH is received, the flowchart 5200 proceeds to operation 5210, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5220 to operation 5210, the same TX beam used in operation 5218 is used in operation 5210. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0383] In operation 5220, if a RAR corresponding to the transmitted PRACH is not received, the flowchart 5200 proceeds to operation 5222, where it is determined whether the maximum number of attempts has been reached. If the maximum number of attempts has been reached, the flowchart 5200 proceeds to operation 5216, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed. However, if the maximum number of attempts has not been reached in operation 5222, the flowchart 5200 proceeds to operation 5224, where it is determined whether there are any type 2 candidate transmit beams remaining. If a type 2 transmit beam remains, the flowchart 5200 switches to another type 2 transmit beam in operation 5226 before returning to operation 5218.

[0384] Returning to operation 5224, if it is determined that no candidate transmit beams of type 2 remain, the flowchart 5200 proceeds to operation 5228, where a transmit power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmit power as before is used, and the flowchart 5200 proceeds to operation 5230, where the candidate transmit beams of type 2 are reset before returning to operation 5218 to transmit the PRACH using the transmit beams of type 2.

[0385] Fig.53 A flowchart for determining a transmit beam from a random access procedure according to various embodiments of the present disclosure is shown. The random access procedure may be contention-based or non-contention-based. An example of a contention-based random access procedure is a random access performed for initial cell access. An example of a non-contention-based random access procedure is a random access performed for beam failure recovery. The operations of flowchart 5300 may be implemented in a UE, for example Figure 3UE 116 in.

[0386] Flowchart 5300 begins with operation 5302, where a synchronization signal block (SSB) is received on a type 1 Rx beam, i.e., a wide Rx beam. For initial access, the SSB is the SSB that the UE has selected to receive the MIB to obtain the information required to access the cell. For beam failure recovery, in one embodiment, the SSB can be a reference signal for new candidate beam identification; however, in another embodiment, CSI-RS can also be used.

[0387] In operation 5304, it is determined whether the signal strength or quality of the received SSB or CSI-RS is above a threshold. In some embodiments, the signal strength or quality is determined by RSRP, SNR, SINR. The determination in operation 5304 determines whether a type 1 or type 2 transmit beam is used for PRACH transmission. If the received signal strength or quality is greater than the threshold, the flowchart 5300 proceeds to operation 5306, and the PRACH is transmitted with a type 1 transmit beam.

[0388] In operation 5308, it is determined whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 5300 proceeds to operation 5310, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5308 to operation 5310, the same TX beam used in operation 5306 is used in operation 5310. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0389] In operation 5308, if the RAR corresponding to the transmitted PRACH is not received, the flowchart 5300 proceeds to operation 5312, in which it is determined whether the maximum number of attempts (or a predetermined number of attempts) has been reached. If the maximum number of attempts has not been reached in operation 5312, the flowchart 5300 proceeds to operation 5314, in which a transmit power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmit power as before is used, and the flowchart 5300 returns to operation 5306 to transmit the PRACH with the power selected in operation 5314 and a transmit beam of type 1.

[0390] Returning to operation 5304, if it is determined that the signal strength or quality of the received SSB or CSI-RS is not higher than the threshold, the flowchart 5300 proceeds to operation 5316, and the PRACH is transmitted with a transmit beam of type 2. Thereafter, it is determined in operation 5318 whether a random access response (RAR) corresponding to the transmitted PRACH is received. If a RAR corresponding to the transmitted PRACH is received, the flowchart 5300 proceeds to operation 5310, in which it is determined that the transmit beam in the subsequent transmission is the same type as the transmit beam used for the last PRACH transmission. Therefore, when proceeding from operation 5318 to operation 5310, the same transmit beam used in operation 5316 is used in operation 5310. In some embodiments, the same transmit beam is used until a new configuration is received or indicated by the network.

[0391] In operation 5318, if a RAR corresponding to the transmitted PRACH is not received, the flowchart 5300 proceeds to operation 5320, where it is determined whether the maximum number of attempts has been reached. If the maximum number of attempts has been reached, the flowchart 5300 proceeds to operation 5322, where other actions (e.g., searching for alternative SSBs, cells, or networks) may be performed. However, if the maximum number of attempts has not been reached in operation 5320, the flowchart 5300 proceeds to operation 5324, where it is determined whether any type 2 candidate transmit beams remain. If a type 2 transmit beam remains, the flowchart 5300 switches to another type 2 transmit beam in operation 5326 before returning to operation 5316.

[0392] Returning to operation 5324, if it is determined that no candidate transmit beams of type 2 remain, the flowchart 5300 proceeds to operation 5328, where a transmit power is selected for the PRACH. In particular, if the maximum power has not been reached, the power is increased. If the maximum power has been reached, the same transmit power as before is used, and the flowchart 5300 proceeds to operation 5330, where the candidate transmit beams of type 2 are reset before returning to operation 5316 to transmit the PRACH with a transmit beam of type 2.

[0393] Returning to operation 5312, if the number of attempts has been reached, flowchart 5300 proceeds to operation 5316, in which PRACH is transmitted using a type 2 transmit beam.

[0394] Fig.54 5400 is a flowchart of beam management between multiple antenna panels according to various embodiments of the present disclosure. The operations of flowchart 5400 may be implemented in a UE, for example Figure 3UE 116 in.

[0395] Flowchart 5400 begins at operation 5402 by determining a link quality of a serving antenna panel.

[0396] In operation 5402, if the link quality of the serving antenna panel is below a threshold, resources are allocated from the serving antenna panel to another antenna panel of the plurality of antenna panels during a scanning period to identify one or more beams of a target antenna panel to resume communication.

[0397] In some embodiments, in response to determining that the link quality measurement table of another antenna panel has not been updated within a predetermined amount of time, resources are allocated from the serving antenna panel to another antenna panel. The link quality measurement table can be updated with measurements obtained during the scan. The link quality measurement table can be updated based on the updated beam scanning order, or the link quality measurement table can be updated based on the narrow beam of the best wide beam identified during the scanning period. In one embodiment, in order to update the link quality measurement table based on the updated beam scanning order, the updated beam scanning order is identified based on the obtained measurements. Based on the updated beam scanning order, a beam group can be formed and then measured. Thereafter, the link quality measurement table can be updated based on the updated beam scanning order. In another embodiment, in order to update the link quality measurement table based on one or more narrow beams of the best wide beam, a narrow beam of the best wide beam is identified based on the obtained measurements, and a group of beams can be formed and measured based on one or more narrow beams of the best wide beam. Thereafter, the link quality measurement table can be updated based on the one or more narrow beams.

[0398] In operation 5406, measurements of a set of beams of another antenna panel are obtained using the allocated resources during the scan period. In some embodiments, obtaining measurements using the allocated resources includes identifying a best wide beam of another antenna panel, thereby selecting the selected beam from a set of narrow beams of the best wide beam.

[0399] In operation 5408, another antenna panel is determined as a target antenna panel based on the obtained measurements. In operation 5410, the serving antenna panel is switched to the target antenna panel. In operation 5412, one or more beams are selected from the set of beams based on the obtained measurements. In operation 5414, communication is resumed on the selected one or more beams via the target antenna panel.

[0400] exist Fig.54In one embodiment, obtaining a measurement of a beam group of another antenna panel includes: identifying a reference beam from another antenna panel or a serving antenna panel, wherein the reference beam may be a most recent beam used by another antenna panel or a most recent beam used by a serving antenna panel; and calculating a predefined metric between the beam group to be measured and the reference beam. In addition, selecting a beam includes determining a beam scanning order for the beam group to be measured based on the calculated metric, thereby selecting a beam for the measurement occasion based on the determined beam scanning order. In this embodiment, the selection of the beam for the measurement occasion is completed within a short predetermined time period within an antenna module switching boundary, such as within N time slots after the module switching boundary.

[0401] exist Fig.54 In another embodiment, obtaining a measurement of a beam group of another antenna panel includes determining whether the other antenna panel has been measured within a predetermined time period. In addition, selecting a beam includes: in response to determining that the other antenna panel has been measured within the predetermined time period, determining a beam scanning order for the beam group to be measured based on a calculated metric between the beam group to be measured and a reference beam of the other antenna panel, and in response to determining that the other antenna panel has not been measured within the predetermined time period, determining a beam scanning order for the beam group to be measured based on a calculated metric between the beam group to be measured and a reference beam of the serving antenna panel. In this embodiment, the beam for the measurement occasion is selected based on the determined beam scanning order. In this embodiment, the selection of the beam for the measurement occasion is completed within a short predetermined time period within the antenna module switching boundary, such as within N time slots after the module switching boundary.

[0402] Flowchart 5400 may also include the step of obtaining measurements of any remaining beams in the beam set of the target antenna panel during operation of the target antenna panel. In one embodiment, the measurements are obtained at an antenna module switching boundary, for example, within N time slots after the antenna module switching boundary and after the beam has been selected for communication by the target antenna module. Thereafter, a switch may be made to one of the remaining beams based on one of the remaining beams having a better link quality.

[0403] Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

[0404] Other technical features will be apparent to those skilled in the art from the following drawings, descriptions and claims.

[0405] It may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document. The term "coupling" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not these elements are in physical contact with each other. The terms "send", "receive" and "communication" and their derivatives include direct and indirect communication. The terms "include" and "comprise" and their derivatives refer to including but not limited to this. The term "or" is inclusive, meaning and / or. The phrase "associated" and its derivatives refer to including, being included, interconnected, containing, being contained, being connected to or with ... connected, coupled to or with ... coupled, communicable, cooperative, interlaced, juxtaposed, close, bound to or with ... bound, having, having attributes, having a relationship with or having a relationship, etc. The term "controller" refers to any device, system or part thereof that controls at least one operation. Such a controller can be implemented with hardware or a combination of hardware and software and / or firmware. The functions associated with any particular controller can be centralized or distributed, whether local or remote. When used with a list of items, the phrase "at least one of" means that different combinations of one or more of the listed items may be used, and only one item may be needed from the list. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. Similarly, the term "set" means one or more. Thus, a set of items can be a single item or a collection of two or more items.

[0406] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or parts thereof suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and rewrite it later, such as rewritable optical discs or erasable storage devices.

[0407] Definitions for other specific words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior and future uses of such defined words and phrases.

Claims

1. A user equipment (UE), comprising: a transceiver including a plurality of antenna panels; and a processor operably connected to the transceiver, the processor configured to: determining that a link quality measurement table for another antenna panel has not been updated within a predetermined amount of time, In response to determining that the link quality measurement table of the another antenna panel has not been updated within a predetermined amount of time, allocating resources from the serving antenna panel to the another antenna panel during a scanning period to identify one or more beams of the target antenna panel to resume communications, wherein The link quality measurement table is updated with the measurements obtained during the scanning period, determining whether the another antenna panel has been measured within a predetermined time period; obtaining, during a scan period, measurements of a beam set of another antenna panel using the allocated resources based on determining that the another antenna panel has been measured; determining that another antenna panel is a target antenna panel based on the obtained measurements, Switching from the service antenna panel to the target antenna panel, selecting one or more beams from the set of beams based on the obtained measurements, and Communications are restored on the selected beam or beams via the targeted antenna panel.

2. The UE according to claim 1, wherein: The processor is also configured to: identifying one or more narrow beams or an updated beam scanning sequence of the best wide beam based on the obtained measurements; forming a beam group based on one or more narrow beams or an updated beam scanning sequence; Measuring beam groups based on one or more narrow beams or an updated beam scanning sequence; and The link quality measurement table is updated based on the one or more narrow beams or the updated beam scanning order.

3. The UE according to claim 1, wherein: To obtain a measurement of a beam set of another antenna panel, the processor is configured to: identifying a reference beam from the other antenna panel or the serving antenna panel, wherein the reference beam is a most recent beam used by the other antenna panel or a most recent beam used by the serving antenna panel, and calculating a predetermined metric between the set of beams to be measured and a reference beam; and To select one or more beams, the processor is configured to: A beam scanning order of the group of beams to be measured is determined based on the calculated metric, wherein one or more beams are selected for a measurement occasion based on the determined beam scanning order.

4. The UE according to claim 1, wherein: To select one or more beams, the processor is further configured to: In response to determining that the another antenna panel has been measured within the predetermined time period, determining a beam scanning order for the group of beams to be measured based on a calculated metric between the group of beams to be measured and a reference beam of the another antenna panel, and In response to determining that another antenna panel is not measured within a predetermined time period, determining a beam scanning order of the group of beams to be measured based on a calculated metric between the group of beams to be measured and a reference beam of the serving antenna panel, One or more beams for use in a measurement instance are selected based on the determined beam scanning order.

5. The UE according to claim 1, wherein: To obtain a measurement of the beam set of the another antenna panel, the processor is further configured to: Identify the best wide beam for another antenna panel, The one or more beams are selected from a group of narrow beams that are optimal wide beams.

6. The UE according to claim 1, wherein: The processor is also configured to: obtaining measurements of any remaining beams in the beam group of the target antenna panel; and Switching to one of the remaining beams based on one of the remaining beams having a better link quality.

7. A beam management method for multiple antenna panels, the method comprising: determining that a link quality measurement table of another antenna panel has not been updated within a predetermined amount of time; In response to determining that the link quality measurement table of the another antenna panel has not been updated within a predetermined amount of time, allocating resources from the serving antenna panel to the another antenna panel during a scanning period to identify one or more beams of the target antenna panel to resume communications, wherein The link quality measurement table is updated with measurements obtained during the scanning period; determining whether the another antenna panel has been measured within a predetermined time period; based on determining that the another antenna panel has been measured, obtaining measurements of a set of beams of the another antenna panel during a scanning period using the allocated resources; determining, based on the obtained measurements, that the another antenna panel is a target antenna panel; Switching from the service antenna panel to the target antenna panel; selecting one or more beams from the set of beams based on the obtained measurements; and Communications are restored on the selected beam or beams via the targeted antenna panel.

8. The method according to claim 7, further comprising: identifying one or more narrow beams or an updated beam scanning sequence of the best wide beam based on the obtained measurements; forming a beam group based on one or more narrow beams or an updated beam scanning sequence; measuring the beam set based on one or more narrow beams or an updated beam scanning sequence; and The link quality measurement table is updated based on the one or more narrow beams or the updated beam scanning order.

9. The method according to claim 7, wherein: The measurements to obtain the beamset of another antenna panel include: identifying a reference beam from the other antenna panel or the serving antenna panel, wherein the reference beam is a most recent beam used by the other antenna panel or a most recent beam used by the serving antenna panel, and calculating a predetermined metric between the set of beams to be measured and a reference beam; and Select one or more beams including: A beam scanning order of the group of beams to be measured is determined based on the calculated metric, wherein one or more beams are selected for a measurement occasion based on the determined beam scanning order.

10. The method according to claim 7, wherein: Select one or more beams including: In response to determining that the another antenna panel has been measured within the predetermined time period, determining a beam scanning order for the group of beams to be measured based on a calculated metric between the group of beams to be measured and a reference beam of the another antenna panel, and In response to determining that another antenna panel is not measured within a predetermined time period, determining a beam scanning order of the group of beams to be measured based on a calculated metric between the group of beams to be measured and a reference beam of the serving antenna panel, One or more beams for use in a measurement instance are selected based on the determined beam scanning order.

11. The method of claim 7, wherein obtaining a measurement of a beam set of the another antenna panel comprises: Identify the best wide beam for another antenna panel, The one or more beams are selected from a group of narrow beams that are optimal wide beams.

12. The method according to claim 7, further comprising: obtaining measurements of any remaining beams in the beam group of the target antenna panel; and Switching to one of the remaining beams based on one of the remaining beams having a better link quality.

13. A non-transitory computer-readable medium comprising instructions that, when executed by a processor of an electronic device, are configured to cause the electronic device to: determining that a link quality measurement table of another antenna panel has not been updated within a predetermined amount of time; In response to determining that the link quality measurement table of the another antenna panel has not been updated within a predetermined amount of time, allocating resources from the serving antenna panel to another antenna panel of the plurality of antenna panels during a scanning period to identify one or more beams of the target antenna panel to resume communications, wherein The link quality measurement table is updated with measurements obtained during the scanning period; obtaining, during a scan period, measurements of a beam set of another antenna panel using the allocated resources, including determining whether the another antenna panel has been measured within a predetermined time period; determining, based on the obtained measurements, that another antenna panel is a target antenna panel; Switching from the service antenna panel to the target antenna panel; selecting one or more beams from the set of beams based on the obtained measurements; and Communications are restored on the selected beam or beams via the targeted antenna panel.

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