WO2020226658A1

WO2020226658A1 - System and method for adaptive beam control

Info

Publication number: WO2020226658A1
Application number: PCT/US2019/031561
Authority: WO
Inventors: Young Hoon Kwon; Pengfei Xia; Bin Liu
Original assignee: Huawei Technologies, Inc
Priority date: 2019-05-09
Filing date: 2019-05-09
Publication date: 2020-11-12
Also published as: CN113906687B; CN113906687A; WO2020226658A8

Abstract

A method implemented by a transmitting device (TD) includes determining, by the TD, a first link quality of a first signal transmitted to one or more first receiving devices (RDs) using a first set of beams, and determining, by the TD, that the first link quality meets a first specified threshold, and based thereon, selecting, by the TD, a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and transmitting, by the TD, to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

Description

System and Method for Adaptive Beam Control

TECHNICAL FIELD

The present disclosure relates generally to a system and method for digital

communications, and, in particular embodiments, to a system and method for adaptive beam control in wireless communications systems.

BACKGROUND

One possible deployment scenario for fifth generation (5G) New Radio (NR) system architecture uses high frequency (HF) (6 gigahertz (GHz) and above, such as millimeter wavelength (mmWave)) operating frequencies to exploit greater available bandwidth and less interference then what is available at the congested lower frequencies. However, pathloss is a significant issue. Beamforming may be used to overcome the high pathloss.

Beamformed beams are typically directional in nature. The directional nature of the beams may complicate communications. As an example, communicating devices with one or more misaligned beams can suffer from temporal link quality degradation.

Therefore, there is a need for system and method for adaptive beam control.

SUMMARY

According to a first aspect, a method implemented by a transmitting device (TD) is provided. The method includes determining, by the TD, a first link quality of a first signal transmitted to one or more first receiving devices (RDs) using a first set of beams, and determining, by the TD, that the first link quality meets a first specified threshold, and based thereon, selecting, by the TD, a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and

transmitting, by the TD, to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

In a first implementation form of the method according to the first aspect as such, wherein the second set of beams further has a smaller number of beams than the first set of beams.

In a second implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the second set of beams further has a smaller periodicity than the first set of beams. In a third implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the beams of the second set of beams has a smaller beamforming gain than the beams of the first set of beams.

In a fourth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein determining the first link quality comprises estimating, by the TD, a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

In a fifth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the signal quality comprises at least one of a long term signal to noise ratio (SNR), a signal plus interference to noise ratio (SINR), or a pathloss.

In a sixth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein determining the first link quality comprises estimating, by the TD, the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a communications system including the TD, the one or more first RDs, and the one or more second RDs.

In a seventh implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein determining the first link quality comprises determining, by the TD, an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment, and setting, by the TD, the first link quality in accordance with the operating environment of the TD.

In an eighth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein determining that the first link quality meets the first specified threshold comprises monitoring, by the TD, the first link quality during a time window, and determining, by the TD, that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

In a ninth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein determining that the first link quality meets the first specified threshold includes monitoring, by the TD, the first link quality during a time window, and determining, by the TD, that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

In a tenth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, further includes determining, by the TD, a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams, and determining, by the TD, that the second link quality does not meet the first specified threshold, and based thereon, selecting, by the TD, a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmitting, by the TD, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

In an eleventh implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the third set of beams and the first set of beams are the same.

In a twelfth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, further includes determining, by the TD, a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams, selecting, by the TD, a fourth set of beams, wherein beams of the fourth set of beams have different beamwidths from the beams of the second set of beams, determining, by the TD, a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams, and determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon, selecting, by the TD, the second set of beams, and transmitting, by the TD, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.

In a thirteenth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the beams of the fourth set of beams have wider beamwidths than the beams of the second set of beams.

In a fourteenth implementation form of the method according to the first aspect as such or any preceding implementation form of the first aspect, wherein the beams of the fourth set of beams have narrower beamwidths than the beams of the second set of beams.

According to a second aspect, a TD is provided. The TD includes a non-transitory memory storage comprising instructions, and one or more processors in communication with the memory storage. The one or more processors execute the instructions to determine a first link quality of a first signal transmitted to one or more first RDs using a first set of beams, and determine that the first link quality meets a first specified threshold, and based thereon, select a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and transmit to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

In a first implementation form of the TD according to the second aspect as such, wherein the second set of beams further has a smaller number of beams than the first set of beams.

In a second implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the second set of beams further has a smaller periodicity than the first set of beams.

In a third implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the beams of the second set of beams has a smaller beamforming gain than the beams of the first set of beams.

In a fourth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to estimate a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

In a fifth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the signal quality comprises at least one of a long term SNR, a SINR, or a pathloss.

In a sixth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to estimate the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a

communications system including the TD, the one or more first RDs, and the one or more second RDs. In a seventh implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to determine an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment, and set the first link quality in accordance with the operating environment of the TD.

In an eighth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to monitor the first link quality during a time window, and determine that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

In a ninth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to determine a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams, and determine that the second link quality does not meet the first specified threshold, and based thereon, select a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmit, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

In a tenth implementation form of the TD according to the second aspect as such or any preceding implementation form of the second aspect, wherein the one or more processors further execute the instructions to determine a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams, select a fourth set of beams, wherein beams of the fourth set of beams have different beamwidths from the beams of the second set of beams, determine a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams, and determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon, select the second set of beams, and transmit, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.

According to a third aspect, a non-transitory computer-readable media storing computer instructions is provided. When the instructions are executed by one or more processors, the instructions cause one or more processors to perform the steps of determine a first link quality of a first signal transmitted to one or more first RDs using a first set of beams, and determine that the first link quality meets a first specified threshold, and based thereon, select a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and transmit to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

In a first implementation form of the non-transitoiy computer-readable media according to the third aspect as such, wherein the one or more processors further execute the instructions to estimate a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

In a second implementation form of the non-transitory computer- readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to estimate the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a communications system including the TD, the one or more first RDs, and the one or more second RDs.

In a third implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to monitor the first link quality during a time window, and determine that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

In a fourth implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to determine an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment, and set the first link quality in accordance with the operating environment of the TD.

In a fifth implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to monitor the first link quality during a time window, and determine that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

In a sixth implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to determine a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams, and determine that the second link quality does not meet the first specified threshold, and based thereon, select a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmit, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

In a seventh implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect, wherein the one or more processors further execute the instructions to determine a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams, select a fourth set of beams, wherein beams of the fourth set of beams have different beam widths from the beams of the second set of beams, determine a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams, and determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon, select the second set of beams, and transmit, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.

In an eighth implementation form of the non-transitory computer-readable media according to the third aspect as such or any preceding implementation form of the third aspect,

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

Figure t illustrates an example communications system;

Figure 2 illustrates a communications system highlighting an example channel structure between an access node and a UE; Figure 3 illustrates a wireless communications system highlighting beam failure and beam failure recovery;

Figure 4A illustrates a beam diagram of beam patterns of an access node and a UE;

Figure 4B illustrates a diagram highlighting a multi-step beam management process;

Figure 5A illustrates an example communication system highlighting temporal link quality degradation due to motion or rotation;

Figure 5B illustrates a graph of an example link quality;

Figures 6A and 6B illustrate beam sets configured for indoor and outdoor operating environments, respectively according to example embodiments presented herein;

Figures 7A and 7B illustrate beam sets configured according to a first variation of device allocated beam resources according to example embodiments presented herein;

Figures 7C and 7D illustrate beam sets configured according to a second variation of device allocated beam resources according to example embodiments presented herein;

Figures 8A and 8B illustrate a communications system highlighting communications using beam sets selected in accordance with link quality according to example embodiments presented herein;

Figure 9 illustrates an example transmitting device according to example embodiments presented herein;

Figure to illustrates a flow diagram of example operations occurring in a transmitting device transmitting signals according to example embodiments presented herein;

Figure 11 illustrates a flow diagram of example operations occurring in a transmitting device transmitting signals to a receiving device according to example embodiments presented herein;

Figure 12 illustrates an example communication system according to example embodiments presented herein;

Figures 13A and 13B illustrate example devices that may implement the methods and teachings according to this disclosure; and Figure 14 is a block diagram of a computing system that may be used for implementing the devices and methods disclosed herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the disclosed embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the embodiments, and do not limit the scope of the disclosure.

Figure 1 illustrates an example communications system too. Communications system too includes an access node 105 serving a user equipment (UE) 115. In a first operating mode, communications to and from UE 115 pass through access node 105. In a second operating mode, communications to and from UE 115 do not pass through access node 105, however, access node 105 typically allocates resources used by UE 115 to

communicate. Access nodes may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, base stations, access points, transmission points (TPs), transmission- reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, and so on, while UEs may also be commonly referred to as mobile stations, mobiles, terminals, users, subscribers, stations, and the like. Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., the Third

Generation Partnership Project (3GPP) long term evolution (LTE), LTE advanced (LTE- A), 5G, 5G LTE, NR, High Speed Packet Access (HSPA), Wi-Fi

802.na/b/g/n/ac/ad/ax/ay, etc. While it is understood that communications systems may employ multiple eNBs capable of communicating with a number of UEs, only one eNB and one UE are illustrated for simplicity.

As discussed previously, pathloss in communications systems operating at high frequency (HF) (6 gigahertz (GHz) and above, such as millimeter wavelength

(mmWave)) operating frequencies, is high, and beamforming maybe used to overcome the high pathloss. As shown in Figure 1, both access node 105 and UE 115 communicate using beamformed transmissions and receptions. As an example, access node 105 communicates using a plurality of communications beams, including beams 110 and 112, while UE 115 communicates using a plurality of communications beams, including beams 120 and 122. A beam may be a pre-defined set of beamforming weights in the context of codebook- based precoding or a dynamically defined set of beamforming weights in the context of non-codebook based precoding (e.g., Eigen -based beamforming (EBB)). A beam may also be a pre-defined set of phase shift preprocessors combining signals from the antenna array in the radio frequency (RF) domain. It should be appreciated that a UE may rely on codebook-based precoding to transmit uplink signals and receive downlink signals, while a TRP may rely on non-codebook based precoding to form certain radiation patterns to transmit downlink signals or receive uplink signals.

Figure 2 illustrates a communications system 200 highlighting an example channel structure between an access node 205 and a UE 210. In a bi-directional communications implementation, there is a downlink channel 220 and an uplink channel 230 between access node 205 and UE 210. Downlink channel 220 and uplink channel 230 may each include a plurality of unidirectional channels. As shown in Figure 2, downlink channel 220 includes a physical downlink shared channel (PDSCH) 222 and a physical downlink control channel (PDCCH) 224 among others, while uplink channel 230 includes a physical uplink control channel (PUCCH) 232, a physical uplink shared channel

(PUSCH) 234, and a physical random access channel (PRACH) 236, among others. Other channels may be present in downlink channel 220 or uplink channel 230 but are not shown in Figure 2.

Figure 3 illustrates a wireless communications system 300 highlighting beam failure and beam failure recovery. Communications system 300 includes an access node 305 serving a UE 315. As shown in Figure 3, both access node 305 and UE 315 communicate using beamformed transmissions and receptions. As an example access node 305

communicates using a plurality of communications beams, including beams 310 and 312, while UE 315 communicates using a plurality of communications beams, including beams 320 and 322.

Initially, access node 305 and UE 315 are communicating through beam pair link (BPL) 325, which comprises beams 310 and 322. However, due to blockage or UE mobility, BPL 325 fails. UE 315 detects a candidate beam 312 from access node 305 to replace failed beam 310, for example. UE 315 initiates beam failure recovery by sending a beam failure recovery request (BFRQ) to access node 305. Upon completion of the beam failure recovery, BPL 330 is established (comprising beams 312 and 320).

When two or more reference signals, data signals, or resources are related in such a way that the two or more reference signals, data signals, or resources may be viewed as possessing similar characteristics, they are said to possess a quasi collocated (QCL) relationship or that they are QCL'ed. QCL relationships may refer to time, frequency, code, or spatial relationships between two or more reference signals, data signals, or resources, while spatial QCL refers to only spatial relationships between two or more reference signals, data signals, or resources. The spatial QCL information may include associations between signals and resources, such as channel status information-reference signal (CSI-RS) resources and wideband reference signals (WBRS), or associations between individual WBRSs, or associations between CSI-RS resources and beamformed random access channels (BRACHs). As an example, in a one to one association, each CSI- RS signal is associated with one WBRS such that the transmit precoder for the CSI-RS signal is the same as a transmit precoder for the WBRS. As another example, each CSI- RS signal is associated with one WBRS such that the transmit precoder for the CSI-RS signal is the same as a transmit precoder for the WBRS. As another example, a first WBRS is associated with a second WBRS such that the transmit precoder for the second WBRS is the same as that for the first WBRS. It is possible that multiple CSI-RS signals are associated with a single WBRS, and vice versa. The spatial QCL information may be stored in tabular form or in a memory of a device. The spatial QCL information includes associations between CSI-RS and WBRSs. The spatial QCL information may be used by the UE to determine CSI-RS beam indices from WBRS beam indices, and vice versa, for example. As an example, in a one to one association, each CSI-RS signal is associated with one WBRS. It is possible that multiple CSI-RS signals are associated with a single WBRS, and vice versa.

It is noted that as used in the discussion presented herein, the term QCL may generally refer to both QCL and spatial QCL. In circumstances where such usage would lead to confusion, spatial QCL will be used as needed.

Beam management is a process in which beams between a pair of communicating device are selected and then refined. Beam management may be a multi-step process. As an example, in a first step, one or more beams or beam groups are selected, then in one or more steps, beam refinement results in the selection of beams from the one or more beams or beam groups to optimize performance. The multi-step process may be performed in successive steps with or without interruption, wherein interruption may involve the communication of data or control information.

Figure 4A illustrates a beam diagram 400 of beam patterns of an access node 405 and a UE 407. As shown in Figure 4A, access node 405 has four wide beams: wide beam A 410, wide beam B 412, wide beam C 414, and wide beam D 416, while UE 407 has two wide beams: wide beam a 420 and wide beam b 422. In addition to wide beams, each communicating device has narrow beams, with each narrow beam having a fraction of the beam width of a wide beam. As an example, wide beam A 410 may be spanned by beams At, A2, and A3, while wide beam a 420 may be spanned by beams at and cc2. Hence, narrow beams At, A2, and A3 may span about the same beamwidth footprint as wide beam A 410 when they are used in combination. Although the discussion focusses on devices with two and four wide beams and two and three narrow beams, the example embodiments are operable with devices with any number of wide beams and narrow beams. Additionally, the beams illustrated in Figure 4A have equal beamwidths, where the wide or narrow beams of a single device have equal beamwidth. However, the example embodiments presented herein are operable of beams with consistent or inconsistent beamwidth. Therefore, the discussion of a specific number of wide or narrow beams, or the beams having the same beamwidth should not be construed as being limiting to either the scope or spirit of the example embodiments.

Although access node 405 has four wide beams and UE 407 has two wide beams, the achievable performance using different beams may differ significantly. As an example, considering communications between access node 405 and UE 407, communicating using wide beams B 412 and a 420 are more likely to result in better performance (e.g., higher data rate, better signal plus interference to noise ratio (SINR), better error rates, etc.) than if wide beams D 416 and b 422 were used. Similarly, the narrower beamwidths of the narrow beams may offer additional refinement to optimize performance. As an example, communicating using narrow beams B3 and at may result in better

performance than communicating with wide beams B 412 and a 420, while the combination of narrow beams B2 and cc2 may result in worse performance.

Figure 4B illustrates a diagram 450 highlighting a multi-step beam management process. A top sequence 455 of beams represents transmissions by an access node using the respective beams, and a bottom sequence 457 of beams represents transmissions by a UE using the respective beams. Pi 460 represents a first step of the multi-step beam management process, which may be referred to as beam selection. Pi 460 may be used to enable UE measurement of different access node transmit beams and support the selection of transmit beams of the access node, as well as receive beams of the UE.

During Pi 460, the access node transmits a signal (such as a reference signal or any other signal that is known by the UE) using its wide beams, and the access node cycles through its wide beams. Furthermore, the access node repeats the cycling of the wide beams for a specified number of times. As an example, the access node transmits using wide beam A, followed by wide beam B, wide beam C, and wide beam D, (shown collectively as first cycle 461) and then the access node repeats the transmissions with the wide beams A, B, C, and D, (shown collectively as second cycle 463) the specified number of times. While the access node is transmitting on its wide beams, the UE is receiving with its wide beams. However, the UE continues to receive using a single wide beam for the entirety of the time that it takes for the access node to cycle through its own wide beams one time.

As an example, the UE receives using its wide beam a (shown collectively as beams 465) as the access node completes its cycle of transmissions with wide beams A, B, C, and D. The UE repeats for each of its remaining wide beams, for example wide beam b (shown collectively as beams 467). The cycling of the transmit beams or the receive beams may be referred to as beam sweeping.

The UE makes measurements of the signals transmitted by the wide beams of the access node received using the wide beams of the UE, and selects a best wide beam of the access node, as well as a best wide beam of the UE. The UE sends a report to the access node (event 470). The report includes an indication of the best wide beam of the access node, for example. The indication may be an index corresponding to a coding sequence or spreading sequence associated with the best wide beam of the access node, for example. The report may also include an indication of the best wide beam of the UE. The indication may be an index corresponding to the best wide beam of the UE or an index corresponding to a coding sequence or spreading sequence associated with the best wide beam of the UE, for example.

After Pi 460, the UE and the access node may communicate using the best wide beam of the access node (as reported by the UE) and the best wide beam of the UE, for example. Immediately after Pi 460, after a specified amount of time, or after an occurrence of an event, the UE and the access node perform P2 475 of the multi-step beam management process. P2 475 may be used to enable the UE to measure different access node transmit beams to possibly change the inter or intra access node transmit beams. P2 475 may be performed by the access node and the UE to help refine the beam used by the access node when communicating with the UE. Examples of events that may trigger P2 475 include, but are not limited to, a receipt of an instruction to perform P2 475, a receipt of an instruction to continue with the multi-step beam management process, an error rate (such as bit error rate, frame error rate, block error rate, etc.) meeting a specified threshold, a mobility event, and so on. P2 475 may be a special case of Pi 460.

During P2 475, the access node transmits a signal (such as a reference signal or any other signal that is known by the UE) using its narrow beams, where the narrow beams used by the access node correspond to the best wide beam as reported by the UE in event 470. Hence, instead of transmitting using all of its narrow beams, the access node uses only the narrow beams that span about the same beamwidth footprint as the best wide beam reported by the UE. As an example, in event 470, the UE reported that wide beam B (i.e., wide beam B 412 from Figure 4 A) was the best wide beam for the access node. Therefore, in P2 475, the access node uses the narrow beams Bi, B2, and B3 (shown collectively as cycle 477) to transmit the signal to the UE. During P2 475, the UE receives the signal transmitted by the access node using its wide beam a (shown collectively as beams 479). The UE makes measurements of the signals transmitted by the narrow beams (e.g., the narrow beams Bi, B2, and B3) of the access node received using the wide beam a of the UE, and selects a best narrow beam of the access node. The UE sends a report to the access node (event 481). The report includes an indication of the best narrow beam of the access node, for example. The indication may be an index corresponding to a coding sequence or spreading sequence associated with the best narrow beam of the access node, for example.

After P2 475, the UE and the access node may communicate using the best narrow beam of the access node (as reported by the UE) and the best wide beam of the UE, for example. Immediately after P2 475, after a specified amount of time, or after an occurrence of an event, the UE and the access node perform P3 485 of the multi-step beam management process. P3 485 may be used to enable the UE to make

measurements of the same transmit beam of the access node to change the receive beam of the UE in a situation where the UE uses beamforming. P3 485 may be performed by the access node and the UE to help refine the beam used by the UE when communicating with the access node. Examples of events that may trigger P3485 include, but are not limited to, a receipt of an instruction to perform P3 485, a receipt of an instruction to continue with the multi-step beam management process, an error rate (such as bit error rate, frame error rate, block error rate, etc.) meeting a specified threshold, a mobility event, and so on.

During P3 485, the access node transmits a signal (such as a reference signal or any other signal that is known by the UE) using its best narrow beam (shown as beams 487), as reported by the UE in event 481. During P3 485, the UE receives the signal transmitted by the access node using its narrow beams, where the narrow beams used by the UE correspond to the best wide beam of the UE. Hence, instead of receiving using all of its narrow beams, the UE uses only the narrow beams that span about the same beamwidth footprint as the best wide beam determined during Pi 460 (shown collectively as cycle 489). The UE makes measurements of the signals transmitted by the best narrow beam of the access node received by the narrow beams of the UE having the same bandwidth footprint of the best wide beam a of the UE. The UE sends a report to the access node (event 491). The report includes an indication of the best narrow beam of the access node, for example. The indication may be an index corresponding to a coding sequence or spreading sequence associated with the best narrow beam of the access node, for example. The report may include an indication of the best narrow beam of the UE, for example. The indication may be an index corresponding to the best narrow beam of the UE or an index corresponding to a coding sequence or spreading sequence associated with the best narrow beam of the UE, for example.

It is possible the actual sequence of steps performed by a particular access node and UE pair may differ from the sequence described herein. As an example, after performing Pi 460 and P2 475, the access node and UE pair may go back to perform Pi 460 instead of performing P3485. The different sequence of steps may be the result of a performance decrease that meets a specified threshold, a receipt of an instruction to perform Pi 460, etc., for example.

As discussed previously, communications systems operating at mmWave operating frequencies and above use beamforming at both the transmitting device and the receiving device to compensate for the high pathloss in the high frequency channels. The highly beamformed signals are directional. Therefore, communications with a highly beamformed signal may experience temporal link quality degradation, even if sophisticated beam management mechanisms are used. As an example, temporal link quality degradation may be the result of motion of the UE or rotation of the UE.

Figure 5A illustrates an example communication system 500 highlighting temporal link quality degradation due to motion or rotation. Communications system 500 includes an access node 505 and a UE 507. Access node 505 is transmitting to UE 507 using beam 510, and UE 507 is receiving using beam 512. Beams 510 and 512 may be selected for access node 505 and UE 507, respectively, as a result of a multi-step beam management procedure, such as one described in Figures 4A and 4B and associated discussion. If UE 507 is in rotation, then the link quality of the communication between access node 505 and UE 507 is at a maximum while beams 510 and 512 are directly (or substantially) aligned. Then, as UE 507 continues rotating, the link quality drops as beams 510 and 512 become more misaligned.

Figure 5B illustrates a graph 550 of an example link quality 555. Link quality 555 corresponds to a link quality between an access node and a UE, where the UE is rotating. As shown in Figure 5B, link quality 555 experiences a drop as the UE rotates and the beams used by the access node and the UE become misaligned. Once the link quality drops below a specified threshold (e.g., beam management thresholds 557), beam management events 559 may be triggered. The triggering of a beam management event may result in the initiation of a multi-step beam management procedure, for example. The result of a beam management event may be the substantial increase in the link quality shown in Figure 5B. However, if the UE continues to rotate or move, the link quality may continue to drop after completion of a beam management event.

The performance loss due to the link quality degradation may be minimized if the beam management period is sufficiently short. However, if the period is too short, additional communications system overhead is incurred due to the increased number of beam management procedures, which will reduce the overall performance of the

communications system.

In modern communications systems, such as 3GPP LTE, NR, NR Device to Device (D2D), NR vehicle to everything (V2X), etc., a transmitting device may need to transmit synchronization signals multiple times, each time with a different beam. The specific synchronization signal format may differ depending on the technical standard, however, the number of times the synchronization signal will be sent, as well as which beam will be used for each time the synchronization signal is sent are implementation issues. If the transmit beam used for the synchronization signal is too narrow, the synchronization signal will need to be repeated many times, resulting in increased communications system overhead. However, if the transmit beam used for the synchronization signal is too broad, the coverage of the synchronization signal is too small to reach potential receiving devices.

In a D2D, V2X, or similar communications system, transmitting device and receiving device communications may occur between two (or more) UEs, with both devices potentially being mobile. In such a situation, both the transmitting device and the receiving device are UEs. The discussion presented herein focuses on such a situation. However, the example embodiments presented in this discussion are also operable in a cellular deployment where one of the two devices is an access node (the access node may be the transmitting device or the receiving device, with a UE usually being the other device), which is generally immobile. Therefore, the discussion of UE to UE

communications should not be construed as being limiting to the scope or spirit of the example embodiments.

It is observed that, even with communications occurring at high frequencies (e.g., mmWave operating frequencies), if the distance between the transmitting device and the receiving device is small (e.g., an indoor operating environment scenario) then sufficient link budget may be maintained even with low beamforming gain so that the maximum modulation and coding scheme (MCS) level is achievable. Low beamforming gain is achieved through the use of a wider beam, for example. In a short range situation, even though the wireless channel may change due to the movement or rotation of the receiving device, the use of a beam with low beamforming gain (and hence, a wider beam) enables the instantaneous link quality to fluctuate slowly enough so that the temporal link quality degradation is avoidable. However, if the distance between the transmitting device and the receiving device is large or the quality of the wireless channel becomes worse, high beamforming gain may be used to overcome the low signal quality. In a long range situation, the narrow beams (as a result of the high beamforming gain) leads to increased temporal link quality degradation sensitivity due to receiving device mobility or rotation.

According to an example embodiment, the configuration of the beams is determined based on an estimated link quality of the wireless channel between the transmitting device and the receiving device. The estimated link quality may be a measure of the distance between the transmitting device and the receiving device. As an example, if the estimated link quality is high, then the transmitting device and the receiving device are close together. As another example, if the estimated link quality is low, then the transmitting device and the receiving device are far apart. The estimated link quality may then be used to determine the configuration of the beams. As an example, if the estimated link quality is high (e.g., the devices are close together) then wider beams are used. As an example, if the estimated link quality is low (e.g., the devices are far apart) then narrower beams are used.

According to an example embodiment, a configuration of a beam or beam set includes a periodicity of the beam, a dwell time of the beam, a number of beams in the beam set, a beamforming gain of the beam, a beam bandwidth of the beam, and so on. The configuration of a beam or beam set specifies the beam or the beams of the beam set. The beams of a beam set may be configured based on an individual characteristic of the beam, such as its beamwidth, beamforming gain, and so on. The beams of the beam set may be configured based on a group characteristic of the beam set, such as the number of beams in the beam set, a dwell time of each beam, the period of the beams, and so forth.

According to an example embodiment, in a scenario where a transmitting device transmits signals to one or more potential receiving devices, the transmitting device determines a link quality of channels to the one or more potential receiving devices and configures a beam set according to the link quality of the channels. In such a scenario, the transmitting device may not have a designated receiving device. Hence, the transmitting device may tend to use an omni-directional beam to maximize coverage. An example of such a scenario is when the transmitting device is transmitting

synchronization signals (or some other reference signal) to the one or more potential receiving devices, without having actual knowledge of the location of the one or more potential receiving devices or the channels between the transmitting device and the one or more potential receiving devices.

In an embodiment, the transmitting device estimates the link quality or the environment of channels between the transmitting device to the one or more potential receiving devices. As an example, the link quality or the environment of channels between the transmitting device to the one or more potential receiving devices are estimated based on historical information. Examples of historical information include known link qualities of previously connected receiving devices, data exchange information, etc. As an example, the link quality or the environment of channels between the transmitting device to the one or more potential receiving devices are set by an operator of the communications system or users of the communications system. As an example, the link quality or the environment of channels between the transmitting device to the one or more potential receiving devices are set to a specified value when the operating environment of the transmitting device is indoor.

In an embodiment, the link quality of channels are compared a threshold, and the configuration of a beam set is set in accordance with the comparison. As an illustrative example, the transmitting device estimates the link quality of channels to the one or more potential receiving devices and compares the link quality to the threshold. If the link quality meets the threshold, the transmitting device configures the beam set to a first configuration, while if the link quality does not meet the threshold, the transmitting device configures the beam set to a second configuration, wherein the first configuration is more conservative than the second configuration. As used in this discussion, the first configuration is said to be more conservative than the second configuration when the first configuration specifies a smaller periodicity, a smaller number of beams, a larger beamwidth, or a smaller beamforming gain than the second configuration. The threshold may be specified by a technical standard, set based on performance information (such as error rate, data rate, etc.), set based on operating environment of the communications system (e.g., indoor, outdoor, or a combination of indoor and outdoor), or through collaboration with other transmitting and receiving devices. In an embodiment, the configuration of the beam set is set in accordance with the environment of the communications system. As an illustrative example, if the transmitting device estimates the operating environment of the communications system as indoor, the transmitting device configures the beam set to a first configuration, while if the operating environment of the communications system is estimated as outdoor, the transmitting device configures the beam set to a second configuration, wherein the first configuration is said to be less conservative than the second configuration.

In an embodiment, a device determines the number of beams in a beam set used for synchronization channel transmission based on the environment of the communications system. As an illustrative example, if the device determines that the operating environment of the communications system is indoor, the device configures a beam set with a first number of beams. As another illustrative example, if the device determines that the operating environment of the communications system is outdoor, the device configures a beam set with a second number of beams. In general, the communications needs of an indoor operating environment may be serviced by a beam set that is more conservative than a beam set that services an outdoor operating environment while providing sufficient performance. In other words, the beam set used in the indoor operating environment may have a smaller periodicity, a smaller number of beams, a larger beamwidth, or a smaller beamforming gain, than the beam set used in the outdoor operating environment but still meet performance requirements. In the example indoor and outdoor operating environment examples presented above, the first number of beams is smaller than the second number of beams. The number of beams in the beam set may be specified by a technical standard, an operator of the communications system, or determined by the device through processing of historical information. In an embodiment, the device determines the number of beams in a beam set used for synchronization channel transmission based on the link quality of channels between the device and one or more potential receiving devices.

Figures 6A and 6B illustrate beam sets configured for indoor and outdoor operating environment, respectively. Figure 6A illustrates a beam set 6oo configured for indoor operating environment. Beam set 6oo has period 605 and includes three beams 610, 612, and 614. Figure 6B illustrates a beam set 650 configured for outdoor operating environment. Beam set 650 has period 655 and includes five beams 660, 662, 664, 666, and 668. The beams of beam set 600 have wider beamwidths than the beams of beam set 650. Beam set 600 has a smaller number of beams, with each beam being wider, than beam set 650. Therefore, beam set 600 may be said to be more conservative than beam set 650. In an embodiment, a device determines the number of beams in a beam set used for synchronization channel transmission. Examples of the device that determines the number of beams include a network entity that is tasked with determining the number of beams (such as an access node), a transmitting device, or a receiving device. The device determining the number of beams may be specified in a technical standard. If the device allocates N resources for synchronization channel transmissions (N resources is equal to N beams), then several variations are possible for adaptive beam control:

t) The transmitting device may transmit signals in Nt resources with non zero power using Nt beams in its beam set, where Nt for an indoor operating environment is smaller than Nt for an outdoor operating environment, and where Nt is less than or equal to N;

2) The transmitting device transmits signals in N resources, where a beamwidth for an indoor operating environment is larger than a beamwidth for an outdoor operating environment; or

3) A combination of t) and 2).

Figures 7A and 7B illustrate beam sets configured according to a first variation of device allocated beam resources. In the first variation of device allocated beam resources, the device allocates N beam resources and the transmitting device uses Nt beams, where Nt is less than or equal to N, and N is equal to five in Figures 7A and 7B. In the situation when Nt is less than N, the synchronization signals are transmitted in the Nt resources and for the remaining N - Nt resources, no synchronization signals are transmitted. The Nt resources where the synchronization signals are transmitted to not need to be sequential or consecutive. As shown in Figure 7A, a beam set 700 is configured for an indoor operating environment with Nt = 3 and N = 5, and includes beams 705, 707, and 709. While Figure 7B illustrates a beam set 720 that is configured for an outdoor operating environment with Nt = 5 and N = 5, and includes beams 725, 727, 729, 731, and 733. The beams of beam set 700 are wider than those of beam set 720. Because beam set 700 is used in an indoor operating environment and beam set 720 is used in an outdoor operating environment, beam set 700 may be more conservative than beam set 720, hence the number of beams (Nt) in beam set 700 is smaller than the number of beams (Nt) in beam set 720.

Figures 7C and 7D illustrate beam sets configured according to a second variation of device allocated beam resources. In the second variation of device allocated beam resources, the device allocates N beam resources and the transmitting device uses Nt beams, where Nt is equal to N, and N is equal to five in Figures 7C and 7D. As shown in Figure 7C, a beam set 740 is configured for an indoor operating environment and includes five beams 745, 747, 749, 751, and 753. While Figure 7D illustrates a beam set 760 that is configured for an outdoor operating environment and includes five beams 765, 767, 769, 771, and 773. The beams of beam set 740 are wider than those of beam set 760. Because beam set 740 is used in an indoor operating environment and beam set 760 is used in an outdoor operating environment, beam set 740 may be more conservative than beam set 760, hence the beamwidth of beams in beam set 740 is greater than the beam width of beams in beam set 760. Similarly, the beamforming gain of beams in beam set 740 is smaller than the beamforming gain of beams in beam set 760.

According to an example embodiment, in a scenario where a transmitting device transmits signals to one or more known receiving devices, the transmitting device determines a link quality of channels to the one or more potential receiving devices and configures a beam set according to the link quality of the channels. In such a scenario, the transmitting device has one or more designated receiving devices. Hence, the transmitting device has knowledge of the location or approximate location of the one or more receiving devices, and may use a beam (or beams) with an orientation that is directed towards the one or more receiving devices. Furthermore, the transmitting device is capable of measuring the channels between the transmitting device and the one or more receiving devices (or is able to obtain measurements of the channels) and is able to obtain the link quality of the channels. An example of such a scenario is when the transmitting device is transmitting data or control information to the one or more receiving devices and has actual knowledge of the location of the one or more receiving devices or the channels between the transmitting device and the one or more receiving devices.

In an embodiment, the transmitting device has multiple beam sets, where each beam set comprises multiple beams with different directions and a combined beam may span the entire targeting direction. The beamwidth of the beams in the different beam sets may be different. Additionally, the beams of a single beam set may have different beamwidths. In general, each beam within a beam set may have a somewhat different beamwidth.

However, an average beamwidth of beams of different beam sets may be different. As an example, there are two beam sets, and the beamwidth of beams in a first beam set is wider than the beamwidths of beams in a second beam set.

In an embodiment, the transmitting device estimates the link quality of channels to the one or more receiving devices. Because the one or more receiving devices are known to the transmitting device, the transmitting device is able to make measurements of the channels (measuring signals from the one or more receiving devices) or obtain measurements of the channels (obtaining reports of measurements of signals transmitted by the transmitting device). The link quality may be determined when the transmitting device discovers the receiving device, for example. The link quality may be long term signal to noise ratio (SNR) values, signal plus interference to noise ratio (SINR) values, estimated path loss values, and so on.

In an embodiment, the transmitting device selects which beam set to use for

communication with the one or more receiving devices based on the link quality of the channels. The transmitting device selects a beam set based on one or more individual characteristic of a beam or one or more group characteristic of a beam set. As an example, the transmitting device selects a beam set with a beamwidth that is linked with the link quality of the channels. The transmitting device selects a first beam set if the link quality meets a specified threshold, and a second beam set if the link quality does not meet the specified threshold, where the beams of the first beam set have wider beamwidths than the beams of the second beam set. The transmitting device may also select a beam set based on beamforming gain, number of beams in a beam set, dwell time of beams in a beam set, period of beams in a beam set, and so on. The transmitting device may select a beam set based on more than one individual characteristic or group characteristic.

In an embodiment, the transmitting device selects which beam set to use for

communication with the one or more receiving devices based on the environment of the communications system. The transmitting device selects a first beam set if the operating environment of the communications system is indoor, or a second beam set if the operating environment of the communications system is outdoor, for example. The first beam set may be characterized as being more conservative than the second beam set, with wider beamwidth, less beamforming gain, etc.

Figures 8A and 8B illustrate a communications system 8oo highlighting communications using beam sets selected in accordance with link quality. Communications system 8oo includes a first UE 805 serving a second UE 807. In a first scenario shown in Figure 8A, first UE 805 and second UE 807 are far apart, hence the link quality of the channel between first UE 805 and second UE 807 is low (i.e., below a threshold). First UE 805 selects a first beam set that includes 12 beams, such as beam Ao 810, At 812, and An 814, for communicating with second UE 807 in this scenario. The selection of the first beam set is in accordance with the link quality of the channel between first UE 805 and second UE 807, which is below the threshold. The beams of the first beam set have narrow beamwidths, and therefore, have high beamforming gain. In a second scenario shown in Figure 8B, first UE 805 and second UE 807 are close together, hence the link quality of the channel between first UE 805 and second UE 807 is high (i.e., above the threshold). First UE 805 selects a second beam set that includes 8 beams, such as beam Bo 820, Bt 822, and B7824, for communicating with second UE 807 in this scenario.

The selection of the second beam set is in accordance with the link quality of the channel between first UE 805 and second UE 807, which is above the threshold.

According to an example embodiment, the transmitting device is able to override its current beam set or beam set configuration to meet current link quality or environmental conditions. The transmitting device is then capable of changing its beam set or beam set configuration to adaptively meet the dynamic nature of channels and operating environment. As an illustrative example, a transmitting device that is currently using a first beam set with a first bandwidth to communicate and determines that the link quality meets a threshold, the transmitting device switches to a second beam set with a second bandwidth, where the second bandwidth is wider than the first bandwidth. The transmitting device adaptively changed to a more conservative beam set because the channel condition is sufficiently good to continue operating adequately with less beamforming gain. As an illustrative example, a transmitting device that is currently using a first beam set with a first bandwidth to communicate and determines that the link quality does not meet a threshold, the transmitting device switches to a second beam set with a second bandwidth, where the second bandwidth is narrower than the first bandwidth. The transmitting device adaptively changed to a less conservative beam set because the channel condition is not good enough to continue operating at an adequate level without additional beamforming gain.

As another illustrative example, a transmitting device that is currently using a first beam set with a first bandwidth to communicate and determines that the link quality is fluctuating faster than a threshold, the transmitting device switches to a second beam set with a second bandwidth, where the second bandwidth is wider than the first bandwidth. As an example, the transmitting device monitors the link quality within a time window, and if the link quality fluctuates by more than a fluctuation threshold within the time window, the transmitting device determines that the link quality is fluctuating faster than the threshold and switches to the second beam set. As another example, the transmitting device monitors the link quality within a time window, and if a difference between the monitored link quality at different times within the time window is greater than a fluctuation threshold, the transmitting device determines that the link quality is fluctuating faster than the threshold and switches to the second beam set. The transmitting device adaptively changed to a more conservative beam set because the current beam set with its narrower beamwidth may not be able to keep track of the receiving device, leading to excessive channel variation. As another illustrative example, a transmitting device that is currently using a first beam set with a first bandwidth to communicate and determines that the link quality is fluctuating slower than a threshold, the transmitting device switches to a second beam set with a second bandwidth, where the second bandwidth is narrower than the first bandwidth. The transmitting device adaptively changed to a less conservative beam set because the current beam set with its wider beamwidth is wider than necessary.

According to an example embodiment, a closed loop adaptive beam set control mechanism is provided. The transmitting device determines the link quality of channels after changing a beam set configuration and adaptively adjusts the beam set

configuration if needed. As an illustrative example, consider a situation where the transmitting device has at least two beam sets configured and is using a first one of the configured beam sets to communicate. On occasion (such as randomly, at a specified times, at a specified time after the last beam set switch, upon receipt of an instruction, upon a threshold being met (e.g., a number of transmission made, a number of beam set switches, an error rate meeting a threshold, etc.), and so on), the transmitting device switches from the first configured beam set to a second configured beam set and determines the link quality of the channels. The transmitting device compares the link quality with a threshold and if the link quality meets the threshold, the transmitting device continues operating with the second configured beam set, while if the link quality does not meet the threshold, the transmitting device switches back to the first configured beam set or to a third configured beam set.

In an embodiment, the beamwidth of the first configured beam set is wider than the beamwidth of the second configured beam set. In an embodiment, the beamwidth of the first configured beam set is narrower than the beamwidth of the second configured beam set. In another embodiment, the transmitting device switches from the first configured beam set to the second figured beam set if the link quality associated with the first configured beam set does not meet a specified threshold.

Although the discussion focusses on configured beam sets and switching between configured beam sets, the example embodiments presented herein are operable with situations where one or more characteristics of a beam set are changed. As an example, the beamwidth of a beam set is changed, the beamforming gain of the beam set is changed, a dwell time of beams of the beam set is changed, a periodicity of the beam set is changed, and so on. Figure 9 illustrates an example transmitting device 900. Transmitting device 900 is capable of adaptively configuring beams or beam sets in accordance with link quality or environmental conditions as described herein. Transmitting device 900 includes one or more antenna panels 905 that may implement transmit and receive beamforming through the application of coefficients of phase shifters of a phase shifter bank 910 coupled to antenna panel 905. An intermediate frequency (IF) / radio frequency (RF) unit 915 coupled to phase shifter bank 910 provides IF and RF signal processing for signals being transmitted or received. A baseband unit 920 coupled to IF/RF unit 915 provides baseband signal processing, including link quality estimation, phase shifter coefficient determination, and so on. A memory 925 coupled to baseband unit 920 provides storage for historical information, such as known link qualities of previously connected receiving devices, data exchange information, etc., which may be used to determine link quality.

A link quality estimator unit 930 of baseband unit 920 is configured to determine link quality of channels between transmitting device 900 and receiving devices. Link quality estimator unit 930 may use measurements of signals received by transmitting device 900 to determine the link quality. Alternatively, link quality estimator unit 930 uses measurements reported by other devices to determine the link quality. Alternatively, link quality estimator unit 930 uses historical information stored in memory 925 to determine the link quality. Baseband unit 920 may also store historical information in memory 925 to be used at a later time in determining the link quality. A beamwidth controller 932 is configured to determine the coefficients of the phase shifters of phase shifter bank 910 to generate beams of a configured beamwidth, where the beamwidth is based on the link quality provided by link quality estimator 930.

Figure to illustrates a flow diagram of example operations 1000 occurring in a transmitting device transmitting signals. Operations 1000 may be indicative of operations occurring in a transmitting device as the transmitting device transmits signals, such as synchronization signals or other signals, where the transmitting device does not have actual knowledge of the location of potential receiving devices or channels between the transmitting device and the potential receiving devices.

Operations 1000 begin with the transmitting device transmitting signals using a first beam set (block 1005). The first beam set comprises a plurality of beams configured in accordance with beam characteristics. The beams of the beam set may be configured based on an individual characteristic of the beam, such as its beamwidth, beamforming gain, and so on. The beams of the beam set may be configured based on a group characteristic of the beam set, such as the number of beams in the beam set, a dwell time of each beam, the period of the beams, and so forth. The transmitting device determines link quality of channels between the transmitting device and the potential receiving devices (block 1007). As an example, the link quality of channels between the transmitting device to the potential receiving devices are estimated based on historical information. As an example, the link quality of channels between the transmitting device to the potential receiving devices are set by an operator of the communications system or users of the communications system. As an example, the link quality of channels between the transmitting device to the potential receiving devices are set to a specified value when the operating environment of the transmitting device is indoor.

The transmitting device determines a second beam set in accordance with the link quality (block 1009). As an example, the transmitting device may compare the link quality with a threshold and select the second beam set in accordance with the results of the comparison. If the link quality meets the threshold, a more conservative beam set (as compared to the first beam set) may be selected, for example. If the link quality does not meet the threshold, a less conservative beam set may be selected, for example.

Alternatively, instead of selecting a different beam set, the transmitting device may adjust one or more characteristics of the beams of the first beam set in accordance with the link quality. As an example, the transmitting device may compare the link quality with a threshold and adjust one or more characteristics of the beams in accordance with the results of the comparison. If the link quality meets the threshold, a characteristic (such as beamwidth, beamforming gain, beam number, beam periodicity, etc.) may be adjusted to produce a more conservative beam set (as compared to the first beam set) may be selected, for example. If the link quality does not meet the threshold, a characteristic may be adjusted to produce a less conservative beam set may be selected, for example.

The beams of the transmitting device are reconfigured (block ton). The beams of the transmitting device may be reconfigured in accordance with the second beam set, for example. As another example, the beams of the transmitting device may be reconfigured in accordance with the one or more adjusted characteristics of the beams. The reconfiguration may involve changing coefficients of a phase shifter bank of the transmitting device are changed to produce the beamforming of the beams of the beam set, for example. The transmitting device may determine the link quality and may determine if the link quality has improved (block 1013). The transmitting device may perform this to determine if the beam set change or the configuration change has resulted in improved performance. If the change has improved performance, the transmitting device returns to continue transmitting signals (block 1005). If the change has not improved performance, the transmitting device may change the beam set back to the first beam set or the configuration of the beam set back to the configuration of the first beam set (block 1015) and return to transmitting signals (block 1005).

On occasion, such as randomly, periodically, expiration of a timer, expiration of a counter, receipt of an instruction, an error rate meeting a threshold, etc., and independent of the beam set currently being used and independent of the link quality, the transmitting device switches to a more conservative beam set or a less conservative beam set (as compared to the beam set currently being used). The nature of the beam set (e.g., more conservative or less conservative) may be selected in accordance with the operating environment of the deployment, current link quality, historical information regarding prior beam set changes, beam set availability, and so on. After switching beam set, the transmitting device may perform a check to determine if link quality has improved (e.g., block 1013) and if the link quality has not improved, changed back to the previous beam set or change to a different beam set (e.g., block 1015). If the link quality has improved, the transmitting device continues using the beam set. This process may be referred to as closed-loop operation.

In an embodiment, it is possible to determine the beam set for the transmitting device prior to the transmitting device transmits signals. An example of such a situation is when an end user of the transmitting device or an operator of the communications system specifies the beam set for the transmitting device. In such a situation, block 1005 (transmitting signals using the first beam set) may occur after block 1015 (changing beam set). Furthermore, in such a situation, blocks 1009 and ton (beam set reconfiguration) may not take place.

Figure 11 illustrates a flow diagram of example operations 1100 occurring in a transmitting device transmitting signals to a receiving device. Operations 1100 may be indicative of operations occurring in a transmitting device as the transmitting device transmits signals, such as data or control signals, to a receiving device.

Operations 1100 begin with the transmitting device transmitting signals to the receiving device using beams of the first beam set (block 1105). The first beam set comprises a plurality of beams configured in accordance with beam characteristics. The beams of the first beam set may be configured based on an individual characteristic of the beam, such as its beamwidth, beamforming gain, and so on. The beams of the first beam set may be configured based on channel measurements made by the transmitting device or channel measurements made by the receiving device and reported to the transmitting device, for example. The transmitting device determines a link quality of a channel between the transmitting device and the receiving device (block 1107). The link quality may be long term SNR values, SINR values, estimated path loss values, and so on. As an example, the transmitting device receives reports of measurements made of transmissions made by the transmitting device and determines the link quality from the reports. As another example, the transmitting device receives signals and determines the link quality from measurements of the signals. The transmitting device determines a configuration of a beam set in accordance with the link quality (block 1109). As an example, the transmitting device may adjust one or more characteristics of the beams of the beam set in accordance with the link quality. As an example, the transmitting device may compare the link quality with a threshold and adjust one or more characteristics of the beams in accordance with the results of the comparison. If the link quality meets the threshold, a characteristic (such as beamwidth, beamforming gain, beam number, beam periodicity, etc.) may be adjusted to produce a more conservative beam set (as compared to the first beam set) may be selected, for example. If the link quality does not meet the threshold, a characteristic may be adjusted to produce a less conservative beam set may be selected, for example. Alternatively, the transmitting device may have a plurality of configured beam sets and will select one of the configured beam sets in accordance with the results of the comparison.

The beams of the transmitting device are reconfigured (block 1111). The beams of the beam set may be reconfigured in accordance with the second beam set, for example. As another example, the beams of the transmitting device may be reconfigured in accordance with the one or more adjusted characteristics of the beams. The

reconfiguration may involve changing coefficients of a phase shifter bank of the transmitting device are changed to produce the beamforming of the beams of the beam set, for example. The transmitting device may determine the link quality and may determine if the link quality has improved (block 1113). The transmitting device may perform this to determine if the beam set change or the configuration change has resulted in improved performance. If the change has improved performance, the transmitting device returns to continue transmitting signals (block 1105). If the change has not improved performance, the transmitting device may change the configuration of the beam set back to the configuration of the beam set prior to the change in the configuration or the beam set back to the beam set used prior to changing the beam set (block 1115) and return to transmitting signals (block 1105). On occasion, such as periodically, expiration of a timer, receipt of an instruction, etc., and independent of the beam set currently being used and independent of the link quality, the transmitting device switches to a more conservative beam set or a less conservative beam set (as compared to the currently used beam set). The nature of the beam set (e.g., more conservative or less conservative) may be selected in accordance with the operating environment of the deployment, current link quality, historical information regarding prior beam set changes, beam set availability, and so on. After switching beam set, the transmitting device may perform a check to determine if link quality has improved (e.g., block 1113) and if the link quality has not improved, changed back to the previous beam set or change to a different beam set (e.g., block 1115). If the link quality has improved, the transmitting device continues using the beam set.

Figure 12 illustrates an example communication system 1200. In general, the system 1200 enables multiple wireless or wired users to transmit and receive data and other content. The system 1200 may implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).

In this example, the communication system 1200 includes electronic devices (ED) 1210a- 1210c, radio access networks (RANs) i22oa-t22ob, a core network 1230, a public switched telephone network (PSTN) 1240, the Internet 1250, and other networks 1260. While certain numbers of these components or elements are shown in Figure 12, any number of these components or elements may be included in the system 1200.

The EDs i2ioa-i2toc are configured to operate or communicate in the system 1200. For example, the EDs i2ioa-i2toc are configured to transmit or receive via wireless or wired communication channels. Each ED i2ioa-i2toc represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, or consumer electronics device.

The RANs i22oa-t22ob here include base stations I270a-t270b, respectively. Each base station I270a-t270b is configured to wirelessly interface with one or more of the EDs i2ioa-t2iocto enable access to the core network 1230, the PSTN 1240, the Internet 1250, or the other networks 1260. For example, the base stations I270a-t270b may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNodeB), a Next Generation (NG) NodeB (gNB), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs i2ioa-i2ioc are configured to interface and communicate with the Internet 1250 and may access the core network 1230, the PSTN 1240, or the other networks 1260.

In the embodiment shown in Figure 12, the base station 1270a forms part of the RAN 1220a, which may include other base stations, elements, or devices. Also, the base station 1270b forms part of the RAN 1220b, which may include other base stations, elements, or devices. Each base station I270a-t270b operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a“cell.” In some embodiments, multiple-input multiple-output (MIMO) technology maybe employed having multiple transceivers for each cell.

The base stations I270a-t270b communicate with one or more of the EDs i2ioa-i2toc over one or more air interfaces 1290 using wireless communication links. The air interfaces 1290 may utilize any suitable radio access technology.

It is contemplated that the system 1200 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

The RANs I220a-t220b are in communication with the core network 1230 to provide the EDs i2ioa-i2toc with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs i22oa-t22ob or the core network 1230 may be in direct or indirect communication with one or more other RANs (not shown). The core network 1230 may also serve as a gateway access for other networks (such as the PSTN 1240, the Internet 1250, and the other networks 1260). In addition, some or all of the EDs i2ioa-i2toc may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 1250.

Although Figure 12 illustrates one example of a communication system, various changes may be made to Figure 12. For example, the communication system 1200 could include any number of EDs, base stations, networks, or other components in any suitable configuration. Figures 13A and 13B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, Figure 13A illustrates an example ED 1310, and Figure 13B illustrates an example base station 1370. These components could be used in the system 1200 or in any other suitable system.

As shown in Figure 13A, the ED 1310 includes at least one processing unit 1300. The processing unit 1300 implements various processing operations of the ED 1310. For example, the processing unit 1300 could perform signal coding, data processing, power control, input/output processing, or any other functionality enabling the ED 1310 to operate in the system 1200. The processing unit 1300 also supports the methods and teachings described in more detail above. Each processing unit 1300 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1300 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

The ED 1310 also includes at least one transceiver 1302. The transceiver 1302 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 1304. The transceiver 1302 is also configured to demodulate data or other content received by the at least one antenna 1304. Each transceiver 1302 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 1304 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 1302 could be used in the ED 1310, and one or multiple antennas 1304 could be used in the ED 1310. Although shown as a single functional unit, a transceiver 1302 could also be implemented using at least one transmitter and at least one separate receiver.

The ED 1310 further includes one or more input/output devices 1306 or interfaces (such as a wired interface to the Internet 1250). The input/output devices 1306 facilitate interaction with a user or other devices (network communications) in the network. Each input/output device 1306 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

In addition, the ED 1310 includes at least one memory 1308. The memory 1308 stores instructions and data used, generated, or collected by the ED 1310. For example, the memory 1308 could store software or firmware instructions executed by the processing unit(s) 1300 and data used to reduce or eliminate interference in incoming signals. Each memory 1308 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.

As shown in Figure 13B, the base station 1370 includes at least one processing unit 1350, at least one transceiver 1352, which includes functionality for a transmitter and a receiver, one or more antennas 1356, at least one memory 1358, and one or more input/output devices or interfaces 1366. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 1350. The scheduler could be included within or operated separately from the base station 1370. The processing unit 1350 implements various processing operations of the base station 1370, such as signal coding, data processing, power control, input/output processing, or any other functionality. The processing unit 1350 can also support the methods and teachings described in more detail above. Each processing unit 1350 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1350 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

Each transceiver 1352 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1352 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 1352, a transmitter and a receiver could be separate components. Each antenna 1356 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 1356 is shown here as being coupled to the transceiver 1352, one or more antennas 1356 could be coupled to the transceiver(s) 1352, allowing separate antennas 1356 to be coupled to the transmitter and the receiver if equipped as separate components. Each memory 1358 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input/output device 1366 facilitates interaction with a user or other devices (network communications) in the network. Each input/output device 1366 includes any suitable structure for providing information to or receiving/providing information from a user, including network interface communications.

Figure 14 is a block diagram of a computing system 1400 that may be used for implementing the devices and methods disclosed herein. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 1400 includes a processing unit 1402. The processing unit includes a central processing unit (CPU) 1414, memory 1408, and may further include a mass storage device 1404, a video adapter 1410, and an I/O interface 1412 connected to a bus 1420.

The bus 1420 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 1414 may comprise any type of electronic data processor. The memory 1408 may comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 1408 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

The mass storage 1404 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1420. The mass storage 1404 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

The video adapter 1410 and the I/O interface 1412 provide interfaces to couple external input and output devices to the processing unit 1402. As illustrated, examples of input and output devices include a display 1418 coupled to the video adapter 1410 and a mouse, keyboard, or printer 1416 coupled to the I/O interface 1412. Other devices may be coupled to the processing unit 1402, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

The processing unit 1402 also includes one or more network interfaces 1406, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1406 allow the processing unit 1402 to communicate with remote units via the networks. For example, the network interfaces 1406 may provide wireless communication via one or more transmitters/transmit antennas and one or more receivers/ receive antennas. In an embodiment, the processing unit 1402 is coupled to a local-area network 1422 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

It should be appreciated that one or more steps of the embodiment methods provided herein may be performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a determining unit or module, a selecting unit or module, or a monitoring unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method implemented by a transmitting device (TD), the method comprising: determining, by the TD, a first link quality of a first signal transmitted to one or more first receiving devices (RDs) using a first set of beams; and

determining, by the TD, that the first link quality meets a first specified threshold, and based thereon,

selecting, by the TD, a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and

2. The method of claim t, wherein the second set of beams further has a smaller number of beams than the first set of beams.

3. The method of any one of claims t-2, wherein the second set of beams further has a smaller periodicity than the first set of beams.

4. The method of any one of claims t-2, wherein the beams of the second set of beams has a smaller beamforming gain than the beams of the first set of beams.

5. The method of any one of claims 1-4, wherein determining the first link quality comprises estimating, by the TD, a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

6. The method of claim 5, wherein the signal quality comprises at least one of a long term signal to noise ratio (SNR), a signal plus interference to noise ratio (SINR), or a pathloss.

7. The method of any one of claims 1-4, wherein determining the first link quality comprises estimating, by the TD, the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a communications system including the TD, the one or more first RDs, and the one or more second RDs.

8. The method of any one of claims 1-4, wherein determining the first link quality comprises:

determining, by the TD, an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment; and

setting, by the TD, the first link quality in accordance with the operating environment of the TD.

9. The method of any one of claims 1-4, wherein determining that the first link quality meets the first specified threshold comprises:

monitoring, by the TD, the first link quality during a time window; and determining, by the TD, that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window. to. The method of claim 1, further comprising:

determining, by the TD, a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams; and

determining, by the TD, that the second link quality does not meet the first specified threshold, and based thereon,

selecting, by the TD, a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmitting, by the TD, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

11. The method of claim to, wherein the third set of beams and the first set of beams are the same.

12. The method of claim 1, further comprising:

determining, by the TD, a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams;

selecting, by the TD, a fourth set of beams, wherein beams of the fourth set of beams have different beam widths from the beams of the second set of beams;

determining, by the TD, a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams; and

determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon,

selecting, by the TD, the second set of beams, and

transmitting, by the TD, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.

13. The method of claim 12, wherein the beams of the fourth set of beams have wider beam widths than the beams of the second set of beams.

14. The method of claim 14, wherein the beams of the fourth set of beams have narrower beamwidths than the beams of the second set of beams.

15. A transmitting device (TD) comprising:

a non-transitory memory storage comprising instructions; and

one or more processors in communication with the memory storage, wherein the one or more processors execute the instructions to:

determine a first link quality of a first signal transmitted to one or more first receiving devices (RDs) using a first set of beams, and

determine that the first link quality meets a first specified threshold, and based thereon,

select a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and

transmit to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

16. The TD of claim 15, wherein the second set of beams further has a smaller number of beams than the first set of beams.

17. The TD of any one of claims 15-16, wherein the second set of beams further has a smaller periodicity than the first set of beams.

18. The TD of any one of claims 15-16, wherein the beams of the second set of beams has a smaller beamforming gain than the beams of the first set of beams.

19. The TD of any one of claims 15-18, wherein the one or more processors further execute the instructions to estimate a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

20. The TD of claim 19, wherein the signal quality comprises at least one of a long term signal to noise ratio (SNR), a signal plus interference to noise ratio (SINR), or a pathloss.

21. The TD of any one of claims 15-18, wherein the one or more processors further execute the instructions to estimate the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a communications system including the TD, the one or more first RDs, and the one or more second RDs.

22. The TD of any one of claims 15-18, wherein the one or more processors further execute the instructions to determine an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment, and set the first link quality in accordance with the operating environment of the TD.

23. The TD of any one of claims 15-18, wherein the one or more processors further execute the instructions to monitor the first link quality during a time window, and determine that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

24. The TD of claim 15, wherein the one or more processors further execute the instructions to determine a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams, and determine that the second link quality does not meet the first specified threshold, and based thereon, select a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmit, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

25. The TD of claim 15, wherein the one or more processors further execute the instructions to determine a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams, select a fourth set of beams, wherein beams of the fourth set of beams have different beamwidths from the beams of the second set of beams, determine a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams, and determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon, select the second set of beams, and transmit, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.

26. A non-transitoiy computer-readable media storing computer instructions, that when executed by one or more processors, cause the one or more processors to perform the steps of:

select a second set of beams, wherein beams of the second set of beams have wider beamwidth than beams of the first set of beams, and transmit to the one or more first RDs, a second signal beamformed in accordance with the second set of beams.

27. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to estimate a signal quality of a channel between the TD and the one or more first RDs, wherein the first signal is transmitted on the channel.

28. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to estimate the first link quality in accordance with at least one of link qualities of one or more second RDs connected to the TD, historical data transfer information associated with the one or more second RDs connected to the TD, or environmental parameters set by an operator of a

communications system including the TD, the one or more first RDs, and the one or more second RDs.

29. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to determine an operating environment of the TD, wherein the operating environment comprises one of an indoor environment or an outdoor environment, and set the first link quality in accordance with the operating environment of the TD.

30. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to monitor the first link quality during a time window, and determine that the first link quality meets the first specified threshold when the first link quality fluctuates by more than a second specified threshold during the time window.

31. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to determine a second link quality of the second signal transmitted to the one or more first RDs using the second set of beams, and determine that the second link quality does not meet the first specified threshold, and based thereon, select a third set of beams, wherein beams of the third set of beams have bandwidth equal to or narrower than beams of the first set of beams, and transmit, to the one or more first RDs, a third signal beamformed in accordance with the third set of beams.

32. The non-transitory computer-readable media of claim 26, wherein the one or more processors further execute the instructions to determine a third link quality of the second signal transmitted to the one or more first RDs using the second set of beams, select a fourth set of beams, wherein beams of the fourth set of beams have different beamwidths from the beams of the second set of beams, determine a fourth link quality of a fourth signal transmitted to the one or more first RDs using the fourth set of beams, and determining, by the TD, that the fourth link quality is worse than the third link quality, and based thereon, select the second set of beams, and transmit, to the one or more first RDs, a fifth signal beamformed in accordance with the second set of beams.