Patent Description:
The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (<NUM>) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (<NUM>) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. Sixth Generation (<NUM>) wireless communication systems are also under development.

Radios with antenna arrays are capable of beamforming. Beamforming is a general concept where the signal is transmitted from multiple locations after being weighted with appropriate complex weights based on element location relative to a fixed position. Typically, the fixed position is set as one of the antenna element positions on which the signal is being transmitted. The coverage shape of the transmission is managed via the complex weights. This concept has found significant use in acoustics communications, radar and wireless communications. In various devices, microphone arrays are deployed to control the direction of received or emitted audio signals. In wireless communications, both access points and mobiles are equipped with multiple antennas where beamforming can be used to improve the desired signal and/or cancel undesired interference towards selected directions. RF frequency band varies significantly from HF band all the way to terra-hertz spectrum.

In order to benefit from beamforming, the transmitter needs to calculate the complex phases to create the desired beam shape. In some cases, the transceiver may have means of estimating the channels and deriving those weights. In some other cases, however, the network protocol may not have the means to estimate the channel and may fall back to common beam transmissions. For example, in 3GPP millimeter wave (mmWave) communications, during certain periods of transmissions, the synchronicity between the transmitters and receiver may be lost for a prolonged period of time at which point they need to undergo a safe mode operation where the achievable throughput performance degrades significantly. An example of when safe mode operations are triggered in 3GPP mmWave communications is when several consecutive CSI reports are missed, resulting in discontinuance of beam management. Thus, a safe mode operation has reduced performance.

When the transmitter loses access to training protocols based on which the beamforming weights are estimated, the link falls back typically to a non-multiple input multiple output (non-MIMO) transmission mode to create wider beams to reach the target receivers. Equipping the radio with a large-array and reducing the transmission to a common beam is disadvantageous in most cases, whether it is during normal operation or it is during a recovery phase.

In some other cases, the reliability of methods to determine beamforming weights may become critical in achieving the desired coverage shape. Radio frequency (RF) characteristics and design accuracies significantly change across these RF bands and proper protocols are required to determine the complex weights. The reliability of RF beamforming may also vary vastly due to the frequency dependency of the medium on electromagnetic waves. As one gets to mmWave frequencies and higher, radio waves suffer from huge propagation loss and atmospheric absorption, so that the cell coverage area shrinks significantly. Thus, at mmWave frequencies and higher, highly directional transmissions enabled by beamforming may be important. Falling back to a common beam transmission mode may result in loss of communication and restart of beam management protocols (which is a resource and time-consuming procedure). <CIT> discloses methods to determine direction of arrivals (DoAs) of arriving ambient sound signals using acoustic means and determining an area of coverage for communication based on the DoAs.

Some embodiments advantageously provide a method and system for spatial audio assisted radio frequency (RF) beamforming for millimeter wave and Tera Hertz communications in safe mode.

In order to avoid the complete lack of MIMO mode operation that occurs during safe mode operational periods in known methods, and/or during the periods where the usual beamformer estimation procedures become less reliable, some embodiments provide an emergency-mode beamforming procedure where acoustics array are employed.

Beamforming in most cases reduces to determining the desired directions and undesired directions and steering one or more beams in the desired directions while steering one or more nulls in the undesired directions. Any additional information to determine the directions contribute to more accurate beam steering and null steering. Some embodiments provide an audio-RF heterogenous beamforming architecture which includes an access point and a microphone array collocated with the RF antenna array of the access point. The access point, which hereinafter is referred to as a network node, can trigger acoustics-based direction acquisition. A beam management entity of the network node (e.g., during beam-refinement periods) can combine the information obtained from an out-of-band acoustic array and an in-band RF signal. The information from an acoustic array can be mapped to a spatial angle direction. Then, a beam-forming mode of operation may be performed during safe mode procedures or during protocol periods where the transmitter loses access to channel state measurements. In cases where limited in-band channel estimation available, some embodiments include combining acoustics-based beamforming information with beamforming information derived from the usual channel state information (CSI) estimation procedure. In some embodiments, a selective direction information combination includes determining acoustic signal quality and RF signal quality to be used for direction estimation. The use of comparison and a weighted-beam approach may be employed where the direction of an RF beam can be based on an RF signal, or acoustic signal, or may be based on a both the RF signal and the acoustic signal.

According to one aspect, a method for beamforming at a network node configured to communicate with a plurality of WDs. The network node has a microphone array. The method includes triggering a WD to transmit at least one acoustic pulse and determining a direction of arrival of the at least one acoustic pulse received from the WD via the microphone array. The method also includes determining a radio frequency, RF, beam for communication with the WD based at least in part on the determined direction of arrival, and transmitting to the WD on the determined RF beam.

According to this aspect, in some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a weighted average of beam steering vectors. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a largest eigenvector of a weighted singular value decomposition, SVD, matrix. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a beam synthesis process to determine an RF beam in a direction toward the WD. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a channel state information, CSI, is not available. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD is not received within an expected time slot, the P2 report indicating which of a plurality of RF beams is associated with the WD. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD is deemed to be unreliable, the P2 report indicating which of a plurality of RF beams is associated with the WD. In some embodiments, the P2 report is based at least in part on a downlink control information, DCI, format DCI_0_1. In some embodiments, the method also includes adjusting a margin of a link adaptation process based at least in part on a reliability or noise level of a beam index estimation module. In some embodiments, the method further includes switching an outer loop link adaptation process to conservative mode, where in the conservative mode, a signal to noise ratio, SNR, is not increased in response to receipt of a non-acknowledgment, NACK, from the WD. In some embodiments, the triggering is prior to entering a safe mode of operation.

According to another aspect, a network node is configured to communicate with a plurality of WDs. The network node includes a microphone array configured to receive an acoustic pulse from a WD. The network node also includes processing circuitry configured to trigger the WD to transmit at least one acoustic pulse, and determine a direction of arrival of the at least one acoustic pulse received from the WD via the microphone array. The processing circuitry is also configured to determine a radio frequency, RF, beam for communication with the WD based at least in part on the determined direction of arrival. The network node also includes a radio interface configured transmit to the WD on the determined RF beam.

According to this aspect, in some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a weighted average of beam steering vectors. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a largest eigenvector of a weighted singular value decomposition, SVD, matrix. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a beam synthesis process to determine an RF beam in a direction toward the WD. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a channel state information, CSI, is not available. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD is not received within an expected time slot, the P2 report indicating which of a plurality of RF beams is associated with the WD. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD is deemed to be unreliable, the P2 report indicating which of a plurality of RF beams is associated with the WD. In some embodiments, the P2 report is based at least in part on a downlink control information, DCI, format DCI_0_1. In some embodiments, the processing circuitry is further configured to adjust a margin of a link adaptation process based at least in part on reliability or noise level of a beam index estimation module. In some embodiments, the processing circuitry is further configured to switch an outer loop link adaptation process to conservative mode, where in the conservative mode, a signal to noise ratio, SNR, is not increased in response to receipt of a non-acknowledgment, NACK, from the WD. In some embodiments, the triggering is prior to entering a safe mode of operation.

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to spatial audio assisted radio frequency (RF) beamforming for millimeter wave and Tera Hertz communications in safe mode. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

The term "network node" used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term "radio node" used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell/multicast Coordination Entity (MCE), relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

The heterogenous beamforming architecture described herein may have any one or more features:.

Referring to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in <FIG> a schematic diagram of a communication system <NUM>, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (<NUM>), which comprises an access network <NUM>, such as a radio access network, and a core network <NUM>. The access network <NUM> comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes <NUM>), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas <NUM>). Each network node 16a, 16b, 16c is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices <NUM>) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node <NUM>. Note that although only two WDs <NUM> and three network nodes <NUM> are shown for convenience, the communication system may include many more WDs <NUM> and network nodes <NUM>.

A network node <NUM> (eNB or gNB) is configured to include a beamformer controller <NUM> configured to determine a direction of arrival of the at least one acoustic pulse received from a WD via a microphone array. A wireless device <NUM> is configured to include an audio unit <NUM> which is configured to transmit an audio signal.

Example implementations, in accordance with an embodiment, of the WD <NUM> and network node <NUM> discussed in the preceding paragraphs will now be described with reference to <FIG>.

The communication system <NUM> includes a network node <NUM> provided in a communication system <NUM> and including hardware <NUM> enabling it to communicate with the WD <NUM>. The hardware <NUM> may include a radio interface <NUM> for setting up and maintaining at least a wireless connection <NUM> with a WD <NUM> located in a coverage area <NUM> served by the network node <NUM>. The radio interface <NUM> includes an array of antennas <NUM> to radiate and receive signal(s) carrying electromagnetic waves. In addition to the radio interface <NUM>, the network node <NUM> also includes a microphone array <NUM> configured to receive acoustic signals. The radio interface <NUM> communicates over the air on a wireless connection <NUM>, e.g., an RF link. The microphone array <NUM> senses audio frequency signals communicated over the air by wireless devices <NUM>, shown in <FIG> as audio link <NUM>.

Thus, the network node <NUM> further has software <NUM> stored internally in, for example, memory <NUM>, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node <NUM> via an external connection. The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node <NUM>. Processor <NUM> corresponds to one or more processors <NUM> for performing network node <NUM> functions described herein. The memory <NUM> is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to network node <NUM>. For example, processing circuitry <NUM> of the network node <NUM> may include a beamformer controller <NUM> configured to determine a direction of arrival of the at least one acoustic pulse received from a WD via a microphone array.

The radio interface <NUM> includes an array of antennas <NUM> to radiate and receive signal(s) carrying electromagnetic waves.

The client application <NUM> may be operable to provide a service to a human or non-human user via the WD <NUM>.

The processing circuitry <NUM> may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD <NUM>. The processor <NUM> corresponds to one or more processors <NUM> for performing WD <NUM> functions described herein. The WD <NUM> includes memory <NUM> that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software <NUM> and/or the client application <NUM> may include instructions that, when executed by the processor <NUM> and/or processing circuitry <NUM>, causes the processor <NUM> and/or processing circuitry <NUM> to perform the processes described herein with respect to WD <NUM>. For example, the processing circuitry <NUM> of the wireless device <NUM> may include an audio unit <NUM> which is configured to transmit an audio signal.

In some embodiments, the inner workings of the network node <NUM> and WD <NUM> may be as shown in <FIG> and independently, the surrounding network topology may be that of <FIG>.

More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc. In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve.

Although <FIG> and <FIG> show various "units" such as beamformer controller <NUM> and audio unit <NUM> as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

<FIG> illustrates a block diagram for an audio-RF beamforming protocol which includes operations of the beamformer controller <NUM>. The beamformer controller <NUM> may include a beam manager module <NUM> configured to perform initial beamforming or beam refinement and/or tracking. The beamformer controller <NUM> may also include an acoustic based beam index generation module <NUM> configured to determine a beam index based on acoustic signal direction. The beamformer controller <NUM> may also include other beam index generation modules <NUM>, for example, video based beam index generation modules. The beam manager module <NUM>, acoustic based beam index generation module <NUM>, and any other optional beam index generation modules <NUM> may produce beam indices which may be input to a beam index combiner <NUM>. The beamformer controller <NUM> may operate in a safe mode <NUM>. Safe mode operation <NUM> may generate an activation signal to cause activation of alternative beam index generation <NUM>. In safe mode operation <NUM>, there may be performed, link adaptation <NUM> which may include selection of a modulation and coding scheme. Safe mode operation <NUM> may also include outer loop adaptation <NUM> and/or data transmission <NUM> which received input from the beam index combiner <NUM>.

<FIG> is a flowchart of an example process in a network node <NUM> for spatial audio assisted radio frequency (RF) beamforming for millimeter wave and Tera Hertz communications in safe mode. One or more blocks described herein may be performed by one or more elements of network node <NUM> such as by one or more of processing circuitry <NUM> (including the beamformer controller <NUM>), processor <NUM>, and/or radio interface <NUM>. Network node <NUM> such as via processing circuitry <NUM> and/or processor <NUM> and/or radio interface <NUM> is configured to trigger the WD to transmit at least one acoustic pulse, the triggering being prior to entering a safe mode of operation (Block S <NUM>). The process also includes determining a direction of arrival of the at least one acoustic pulse received from the WD via a microphone array (Block S <NUM>). The process also includes determining a radio frequency, RF, beam for communication with the WD based at least in part on the determined direction of arrival (Block S <NUM>). The process further includes transmitting to the WD on the determined RF beam (Block S106).

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for spatial audio assisted radio frequency (RF) beamforming for millimeter wave and Tera Hertz communications in safe mode.

An acoustics-based approach for mmWave (or higher frequency) safe mode operations to continue regular uplink/downlink (UL/DL) transmissions using directional transmissions is provided. The approach described herein may be utilized in normal operation modes where a channel state information (CSI) report is not available due to UL bottle neck or lack of in-band temporal resources to collect the usual beam-refinement related reports. Some embodiments are implemented in a network node <NUM>, which may be, for example, a gNB operating as a pico-cell or femto-cell in an indoor environment. A microphone array <NUM> may have a range of <NUM> meters, for example, and may operate at one or more audio frequencies that are greater than an audio frequency that can be heard by a human being. By supplementing beam forming in the safe mode, latencies can be reduced.

In a safe mode of operation, the network node <NUM> may not increase a signal to noise ratio when a hybrid automatic repeat request (HARQ) non-acknowledgement (NACK) is received.

Upon switching to safe mode operation <NUM> or upon detecting deterioration in a normal beam-refinement process, the network node <NUM> (e.g., a gNB), via processing circuitry <NUM> and/or radio interface <NUM>, may send a transmission mode modification message to the radio interface <NUM> of the WD <NUM> via the user control plane (UPC). The network node <NUM> and may continue the communication as follows:.

The radio interfaces <NUM> and <NUM> may exchange control messages to agree on triggering the acoustics beam acquisition procedure as an auxiliary method to be employed during safe mode operations <NUM>.

In some embodiments, the acoustics protocol enables the transmission of spatial acoustic pulses from the receiver to the transmitter. Angle-of-arrival techniques are used to estimate the angle(s) of arrival(s) and this information may be mapped to a beam-index within the usual beam-management procedure. This acoustic protocol (process) may be triggered by an application layer application program interface (API) or built-in beam management protocol. The generation of an acoustic-assisted beam index may be performed as follows:.

According to one aspect, a method for beamforming at a network node <NUM> configured to communicate with a plurality of WDs. The network node <NUM> has a microphone array <NUM>. The method includes triggering a WD <NUM> to transmit at least one acoustic pulse and determining a direction of arrival of the at least one acoustic pulse received from the WD <NUM> via the microphone array <NUM>. The method also includes determining a radio frequency, RF, beam for communication with the WD <NUM> based at least in part on the determined direction of arrival, and transmitting to the WD <NUM> on the determined RF beam.

According to this aspect, in some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a weighted average of beam steering vectors. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a largest eigenvector of a weighted singular value decomposition, SVD, matrix. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a beam synthesis process to determine an RF beam in a direction toward the WD <NUM>. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a channel state information, CSI, is not available. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD <NUM> is not received within an expected time slot, the P2 report indicating which of a plurality of RF beams is associated with the WD <NUM>. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD <NUM> is deemed to be unreliable, the P2 report indicating which of a plurality of RF beams is associated with the WD <NUM>. In some embodiments, the P2 report is based at least in part on a downlink control information, DCI, format DCI_0_1. In some embodiments, the method also includes adjusting a margin of a link adaptation process based at least in part on a reliability or noise level of a beam index estimation module. In some embodiments, the method further includes switching an outer loop link adaptation process to conservative mode, where in the conservative mode, a signal to noise ratio, SNR, is not increased in response to receipt of a non-acknowledgment, NACK, from the WD <NUM>. In some embodiments, the triggering is prior to entering a safe mode of operation.

According to another aspect, a network node <NUM> is configured to communicate with a plurality of WDs. The network node <NUM> includes a microphone array <NUM> configured to receive an acoustic pulse from a WD <NUM>. The network node <NUM> also includes processing circuitry <NUM> configured to trigger the WD <NUM> to transmit at least one acoustic pulse, and determine a direction of arrival of the at least one acoustic pulse received from the WD <NUM> via the microphone array <NUM>. The processing circuitry <NUM> is also configured to determine a radio frequency, RF, beam for communication with the WD <NUM> based at least in part on the determined direction of arrival. The network node <NUM> also includes a radio interface <NUM> configured transmit to the WD <NUM> on the determined RF beam.

According to this aspect, in some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a weighted average of beam steering vectors. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a largest eigenvector of a weighted singular value decomposition, SVD, matrix. In some embodiments, the determined RF beam is based at least in part on a beam index corresponding to the determined direction of arrival, the beam index being based at least in part on a beam synthesis process to determine an RF beam in a direction toward the WD <NUM>. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a channel state information, CSI, is not available. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD <NUM> is not received within an expected time slot, the P2 report indicating which of a plurality of RF beams is associated with the WD <NUM>. In some embodiments, determining an RF beam based at least in part on the determined direction of arrival is performed when a P2 report from the WD <NUM> is deemed to be unreliable, the P2 report indicating which of a plurality of RF beams is associated with the WD <NUM>. In some embodiments, the P2 report is based at least in part on a downlink control information, DCI, format DCI_0_1. In some embodiments, the processing circuitry <NUM> is further configured to adjust a margin of a link adaptation process based at least in part on reliability or noise level of a beam index estimation module. In some embodiments, the processing circuitry <NUM> is further configured to switch an outer loop link adaptation process to conservative mode, where in the conservative mode, a signal to noise ratio, SNR, is not increased in response to receipt of a non-acknowledgment, NACK, from the WD <NUM>. In some embodiments, the triggering is prior to entering a safe mode of operation.

Claim 1:
A method for beamforming at a network node (<NUM>) configured to communicate with a plurality of wireless device, WDs, the network node (<NUM>) having a microphone array (<NUM>), the method comprising:
triggering (S100) a WD (<NUM>) to transmit at least one acoustic pulse;
determining (S102) a direction of arrival of the at least one acoustic pulse received from the WD (<NUM>) via the microphone array (<NUM>);
determining (S104) a radio frequency, RF, beam for communication with the WD (<NUM>) based at least in part on the determined direction of arrival; and
transmitting (S106) to the WD (<NUM>) on the determined RF beam.