Patent ID: 12253592

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable mediums for more precise user equipment (UE) position estimation in intelligent reflecting surface (IRS) aided positioning. More specifically, aspects of the present disclosure provide techniques for precisely determining a single point in space (e.g., the IRS reflection center) used to represent the area occupied by an intelligent reflecting surface (IRS) for estimating the UE's position and time difference of arrival (TDOA) measurements. The IRS reflection center may represent the location on the IRS where a signal measured by a UE, for positioning, is projecting from.

In particular, equations used for positioning may require precise knowledge of the signal sources to accurately estimate the position of the UE. However, given the large surface area of an IRS, it may be challenging to determine the specific location of the IRS reflection center (e.g., the signal source/transmitter location on the IRS) for precisely determining the position of the UE. Further, in some cases, it may be unclear what measured delay corresponds to the determined IRS reflection center when the large surface of the IRS results in a wide delay-spread of a measured impulse response (e.g., when beam squint occurs).

Accordingly, aspects of the present disclosure provide techniques for precisely determining the IRS position used to represent the area occupied by an IRS to improve the accuracy of estimating a UE's position using, at least, the IRS. Further, in certain aspects, techniques are provided for precisely determining the impulse response corresponding to the delay of a ray that passes through the determined IRS position to the UE. Iterative methods described herein may be used to increase precision estimation for three different cases: a focused case, a defocused case, and a general case.

Introduction to Wireless Communication Networks

FIG.1depicts an example of a wireless communication network100, in which aspects described herein may be implemented.

Generally, wireless communication network100includes base stations (BSs)102, user equipments (UEs)104, one or more core networks, such as an Evolved Packet Core (EPC)160and 5G Core (5GC) network190, which interoperate to provide wireless communications services.

BSs102may provide an access point to the EPC160and/or 5GC190for a UE104, and may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, delivery of warning messages, among other functions. Base stations may include and/or be referred to as a gNB, NodeB, eNB, ng-eNB (e.g., an eNB that has been enhanced to provide connection to both EPC160and 5GC190), an access point, a base transceiver station, a radio base station, a radio transceiver, or a transceiver function, or a transmission reception point in various contexts.

A BS, such as BS102, may include components that are located at a single physical location or components located at various physical locations. In examples in which BS102includes components that are located at various physical locations, the various components may each perform various functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. As such, a BS102may equivalently refer to a standalone BS or a BS including components that are located at various physical locations or virtualized locations. In some implementations, a BS102including components that are located at various physical locations may be referred to as or may be associated with a disaggregated radio access network (RAN) architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture. In some implementations, such components of a base station may include or refer to one or more of a central unit (CU), a distributed unit (DU), or a radio unit (RU).

BSs102wirelessly communicate with UEs104via communications links120. Each of BSs102may provide communication coverage for a respective geographic coverage area110, which may overlap in some cases. For example, small cell102′ (e.g., a low-power base station) may have a coverage area110′ that overlaps the coverage area110of one or more macrocells (e.g., high-power base stations).

The communication links120between BSs102and UEs104may include uplink (UL) (also referred to as reverse link) transmissions from a UE104to a BS102and/or downlink (DL) (also referred to as forward link) transmissions from a BS102to a UE104. The communication links120may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.

In certain aspects, communication between a BS102(e.g., next generation NodeB (gNB or gNodeB)) and a UE104may be blocked by obstacles (e.g., buildings, etc.) and require assistance from an intelligent reflecting surface (IRS)106(also referred to as a “reconfigurable intelligent surface”, a “reflecting intelligent surface”, a “reconfigurable impedance surface”, an “intelligent reflection surface”, or an “intelligent reconfigurable surface”). IRS106enables communications between BS102and UE104to be received and re-radiated, thereby avoiding the obstacles. For example, IRS106may be configured with a codebook for precoding one or more elements thereon (referred to as IRS elements) to allow a beam from one of BS102or UE104(e.g., a transmitter) to be re-radiated off the IRS to reach the other one of BS102or UE104(e.g., a receiver). The direction of the re-radiation by IRS106may be controlled or reconfigured by IRS controller103of the IRS106.

IRS controller103includes a codebook132for applying a beamformer (e.g., precoding weights) according to IRS elements of IRS106. Codebook132includes values of weights to configure each IRS element (or each group of IRS elements) to modify the radio signal re-radiated by each IRS element, such as weight shifting or changing amplitudes.

In an example, when UE104is the transmitter and communicates with BS102(e.g., over a wireless Uu interface), BS102is the receiver that provides IRS controller103feedback for selecting beamformer values for the IRS elements. Similarly, when UE104establishes a sidelink (e.g., PC5 interface) with another UE104, UE104may be the transmitter and the other UE104may be the receiver that provides IRS controller103feedback. Codebook132may be generated based on specific settings of BS102and UE104, and based on different parameters specific to different situations. The feedback from the receiver to IRS controller103allows for the selection of beamformer values for reflecting communications between the transmitter and the receiver. Other configurations in wireless communication network100can be similarly setup between UEs104and BSs102.

Examples of UEs104include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player, a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or other similar devices. Some of UEs104may be internet of things (IoT) devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, or other IoT devices), always on (AON) devices, or edge processing devices. UEs104may also be referred to more generally as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, or a client.

Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g.,180inFIG.1) may utilize beamforming182with a UE104to improve path loss and range. For example, BS180and the UE104may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

In some cases, BS180may transmit a beamformed signal to UE104in one or more transmit directions182′. UE104may receive the beamformed signal from BS180in one or more receive directions182″. UE104may also transmit a beamformed signal to BS180in one or more transmit directions182″. BS180may also receive the beamformed signal from UE104in one or more receive directions182′. BS180and UE104may then perform beam training to determine the best receive and transmit directions for each of BS180and UE104. Notably, the transmit and receive directions for BS180may or may not be the same. Similarly, the transmit and receive directions for UE104may or may not be the same.

In certain aspects, wireless communication network100further includes positioning component198, which may be configured to estimate a position of the UE using signals reflected from one or more IRSs.

FIG.2depicts aspects of an example BS102and a UE104. As shown, IRS106may assist the communications, by receiving and re-radiating radio signals, between BS102and UE104, such as when such communications are impeded or blocked by obstacles (not shown, illustrated as the blockage inFIGS.4A and4B). For example, IRS106may re-radiate the transmissions from one of BS102or UE104to the other using reflection, refraction, or other passive or active mechanisms.

IRS106may be reconfigured or controlled by an IRS controller103. Each IRS element may re-radiate radio signals with certain phase or amplitude changes, such as phase shifts. IRS controller103may reconfigure the phase or amplitude changes by applying a beamformer weight to each IRS element or a group of IRS elements to enable IRS103to re-radiate an output beam at different directions given a particular input beam. An illustrative deployment example of IRS103is shown inFIG.4B.

Antennas252, processors266,258,264, and/or controller/processor280of UE104and/or antennas234, processors220,230,238, and/or controller/processor240of BS102may be used to perform the various techniques and methods described herein. Although the present disclosure uses IRS(s) as example(s) of implementing the beamformer techniques, the techniques may apply to another form of cooperative communications, such as transparent relaying or regenerative relaying implementations.

Generally, BS102includes various processors (e.g.,220,230,238, and240), antennas234a-t(collectively234), transceivers232a-t(collectively232), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source212) and wireless reception of data (e.g., data sink239). For example, BS102may send and receive data between itself and UE104.

BS102includes controller/processor240, which may be configured to implement various functions related to wireless communications.

Generally. UE104includes various processors (e.g.,258,264,266, and280), antennas252a-r(collectively252), transceivers254a-r(collectively254), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source262) and wireless reception of data (e.g., data sink260).

UE104includes controller/processor280, which may be configured to implement various functions related to wireless communications. In the depicted example, controller/processor280includes positioning component281, which may be representative of positioning component198ofFIG.1. Notably, while depicted as an aspect of controller/processor280, positioning component281may be implemented additionally or alternatively in various other aspects of UE104in other implementations.

FIGS.3A,3B,3C, and3Ddepict aspects of data structures for a wireless communication network, such as wireless communication network100ofFIG.1. In particular,FIG.3Ais a diagram300illustrating an example of a first subframe within a 5G (e.g., 5G NR) frame structure,FIG.3Bis a diagram330illustrating an example of DL channels within a 5G subframe,FIG.3Cis a diagram350illustrating an example of a second subframe within a 5G frame structure, andFIG.3Dis a diagram380illustrating an example of UL channels within a 5G subframe.

Further discussions regardingFIG.1,FIG.2, andFIGS.3A,3B,3C, and3Dare provided later in this disclosure.

Introduction to Millimeter Wave (mmWave) Wireless Communications

5G New Radio (NR) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth, millimeter wave (mmW) targeting high carrier frequency, massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC). These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QOS) requirements. In addition, these services may co-exist in the same subframe.

One of the main drivers behind 5G is the availability of massive amounts of spectrum. In particular, the electromagnetic spectrum is often subdivided into various classes, bands, channels, or other features. The subdivision is often provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. 5G networks may utilize several frequency ranges, which in some cases are defined by a standard, such as the 3GPP standards. For example, 3GPP technical standard (TS) 38.101 currently defines Frequency Range 1 (FR1) as including 600 megahertz (MHz)-6 gigahertz (GHz), though specific uplink (UL) and downlink (DL) allocations may fall outside of this general range. Thus, FR1 is often referred to (interchangeably) as a “Sub-6 GHz” band.

Similarly, TS 38.101 currently defines Frequency Range 2 (FR2) as including 26-41 GHz, though again specific UL and DL allocations may fall outside of this general range. FR2, is sometimes referred to (interchangeably) as a “millimeter wave” (“mmW” or “mmWave”) band, despite being different from the extremely high frequency (EHF) band (30 GHZ-300 GHz) that is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band because wavelengths at these frequencies are between 1 millimeter (mm) and 10 millimeters.

Communications using mmWave/near mm Wave radio frequency band (e.g., 3 GHz-300 GHz) may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, as described above with respect toFIG.1, a BS (e.g.,180) configured to communicate using mm Wave/near mm Wave radio frequency bands may utilize beamforming (e.g.,182) with a UE (e.g.,104) to improve path loss and range.

Further, in some cases, to aid in seamless communication at mmWave bands, additional cell sites are added within existing infrastructure to increase the amount of available capacity, such additions may be referred to as network densification. Network densification. In particular, cell sites placed in capacity-strained areas add more capacity where it is most needed and also help to offload traffic from surrounding sites. Network densification may involve various layers of components including gNBs, remote-radioheads (RRHs), various types of repeaters, small-cells, and femto-cells. In some cases, network densification involves the addition of one or more intelligent reflecting surfaces (IRSs) to the existing infrastructure. IRS, as used herein, may also be referred to in the art as a reconfigurable intelligent surface, a reflecting intelligent surface, a reconfigurable impedance surface, an intelligent reflection surface, an intelligent reconfigurable surface, a fixed reflecting surface, a meta-surface, etc.

Example Application(s) of Intelligent Reflecting Surface(s) (IRS(s))

Massive multiple-input-multiple-output (MIMO) configuration increases throughput. For example, MIMO can achieve high beamforming gain by using active antenna units and can operate with individual radio frequency (RF) chains for each antenna port. To further such advantages and extend coverage, IRSs may be deployed to reflect impinging waves in desired directions. In some cases, IRSs may operate without substantial power consumption when they operate passively to only reflect or refract beams from a transmitter towards a receiver. In some cases, the reflection or refraction direction may be controlled by a network entity (e.g., base station (BS), next generation NodeB (gNB or gNodeB)) or a monitoring sidelink user equipment (UE).

FIG.4Aillustrates an example400A of communication blockage between wireless communication devices, in accordance with certain aspects of the present disclosure. As shown, impeded by a blockage (e.g., blockages such as buildings, terrains, etc.), a network entity, BS102a(e.g., BS102of wireless communication network100ofFIG.1), is only able to transmit to a first UE, UE104a, as transmissions may not reach a second UE, UE104b, given the blockage prevents signals from reaching UE104b. The blockage also prevents UE104bfrom establishing sidelink communications with UE104a. As such, UE104bis prevented from communicating with BS102avia UE104a, using sidelink.

FIG.4Billustrates an example400B of using IRS106to overcome the blockage, in accordance with certain aspects of the present disclosure. As shown, an IRS106is introduced to reflect, or otherwise re-radiate, radio signals to bypass the blockage. For example, two-way communications between BS102aand UE104bare enabled by IRS106re-radiating one or more beams from BS102atoward UE104b, and vice versa. Furthermore, in some cases, IRS106is reconfigured, such as with different beamformer values, to enable UEs104aand104bto establish sidelink communications.

FIG.5illustrates an example arrangement500of IRS elements (e.g., such as elements of IRS106inFIGS.1,2, and4B), in accordance with certain aspects of the present disclosure. As illustrated inFIG.5, the surface of IRS106consists of any array of discrete elements, such as an m×n rectangular matrix of discrete elements, that can be controlled individually or on a group level. Such elements may enable IRS106to perform passive beamforming. For example, IRS106may receive signal power from a transmitter (e.g., BS102, UE104a, or UE104b) proportional to the number of IRS elements thereon. When IRS106reflects or refracts the radio signal, elements of IRS106cause phase shifts to perform conventional beamforming or beamformer. The phase shifts are controlled by beamformer weights (e.g., a multiplier or an offset of time delay) applied to the elements of IRS106. In some cases, for the array of IRS elements illustrated inFIG.5, for example, a respective beamformer weight may be generated or specified for each of the IRS elements by the IRS controller.

Example Intelligent Reflecting Surface (IRS) Aided Positioning

In general, intelligent reflecting surfaces (IRSs) enhance the coverage and capacity of wireless communication systems with low hardware cost and energy consumption. Moreover, IRSs provide additional benefits in several applications, such as for example, with respect to positioning. Because an increasing awareness of objects about their own location is an essential feature of emerging systems and services in wireless communication, e.g., autonomous systems and industrial Internet of Things (IoT), positioning is seen as an integral part of the system design of 5G mobile radio networks.

For example, IRS-based positioning methods provide an alternative to traditional positioning methods (e.g., GPS, terrestrial positioning systems, etc.) which may use transmitters positioned at several geographically separated locations. Instead of using multiple transmitters, IRS-based positioning methods may use as few as one transmitter whose signal is reflected from numerous IRSs for positioning techniques, in addition to one or more mathematical equations, to determine a UE's position.

Such mathematical equations used to determine the UE's position, however, may require precise knowledge of the signal sources, in this case, the IRS reflection center(s). The “IRS reflection center” essentially refers to a single point in space, which may vary based on UE position, used to represent the area occupied by the IRS. The IRS reflection center may represent a point on the surface area of the IRS where a signal measured by a UE (e.g., for positioning) is coming from. In other words, the IRS reflection center may be considered as the transmitter location, e.g., the location where the signal/energy is projecting from on the IRS, for positioning purposes.

FIG.6is a diagram600illustrating example UE positioning using an IRS, in accordance with certain aspects of the present disclosure. Given the typically large surface area of an IRS (as illustrated byFIG.6), determining the specific location of the IRS reflection center (e.g., the transmitter location on the IRS) for precisely determining the position of a UE may be challenging. For example, where a maximum of 10 cm of positioning error is allowed, and the IRS is 1 meter in size, depending upon the point on the IRS considered as the IRS reflection center, the estimated position of the UE may fall outside the allowed positioning error.

Further, in some cases, the large surface of the IRS may result in a wide delay-spread of a measured impulse response. For example, as shown inFIG.6, the measured impulse response (also referred to as the “observed impulse response”) by a UE may be represented as a histogram of measured delays for a plurality of rays through different points over the surface area of the IRS. In cases where beam squint occurs, the measured impulse response may look similar to the time-domain view of the measured impulse response illustrated inFIG.6where a blur effect in the frequency domain occurs and causes drooping at the band edges.

As used in the art, beam squint may refer to the phenomenon where different frequency components in a signal transmitted by a phased array are beamformed in different direction due to the “phase” at each antenna element corresponding to a different actual path length depending on the frequency. For example, if a wavelength is 10 cm, a 90° phase may correspond to a 2.5 cm path length; however, where the wavelength is increased, the same phase may correspond to a longer path length.FIG.7Aillustrates example beam squinting, in accordance with certain aspects of the present disclosure. Although beam squint typically applies to antenna arrays, beam squint may also apply to IRSs.

FIG.7Billustrates the time-domain view of beam squint for an IRS. In particular,FIG.7Billustrates the impulse response for a plurality of rays reflected from different points over the surface area of the IRS. As shown inFIG.7B, the impulse response is almost-continuous time, and may be represented by the following equation:
h(τ)=histogram({τn:gNB−UE delay thrun'thmetaatom})×ej2πfcτ

For positioning purposes, however, the impulse response may need to be represented as a single point on the histogram, which corresponds to the determined IRS reflection center. In some cases, it may be difficult to precisely determine the impulse response corresponding to the delay of a ray that passes through the IRS reflection center for precisely determining the position of the UE.

Accordingly, techniques for precisely determining the IRS reflection center, as well the impulse response corresponding to the delay of a ray that passes through the IRS reflection center, may be desired to improve the precision of UE positioning using one or more IRSs.

Aspects Related to Techniques for Intelligent Reflecting Surface (IRS) Position Determination in IRS Aided Positioning

Aspects of the present disclosure provide techniques for precisely determining a single point in space (e.g., the intelligent reflecting surface (IRS) reflection center) used to represent the area occupied by an IRS to improve the accuracy of estimating a user equipment's (UE's) position using, at least, the IRS. Further, in certain aspects, techniques are provided for precisely determining the impulse response corresponding to the delay of a ray that passes through the determined IRS reflection center to the UE. Iterative methods described herein may be used to precisely determine the IRS reflection center, and in some cases, the impulse response for the IRS reflection center, for three different cases: a focused case, a defocused case, and a general case.

FIG.8Aillustrates an example focused case800A for IRS aided positioning, in accordance with certain aspects of the present disclosure. The focused case may refer to a scenario where wireless signals, transmitted by a network entity and reflected from one or more IRSs, are focused towards a receiver device (e.g., a UE). As used herein, a network entity may refer to a wireless communication device in a radio access network (RAN), such as a BS, a remote radio head or antenna panel in communication with a BS, and/or a network controller, for example. In particular, the focusing operation may be used by an IRS for beamforming towards a UE (e.g., where the location of the UE is known), such that the wireless signals (e.g., rays) are focused towards the specific UE, rather than having the signals spread in all directions from a broadcast antenna. Focusing may be achieved by setting the surface phase of an IRS in a particular way to cause energy to be focused on the UE. As illustrated inFIG.8A, given all signals reflected from the IRS are expected to reach the UE, any point on the IRS may be used as the IRS reflection center for positioning purposes. However, the focused case may suffer from beam squint; thus, the measured impulse response may have a wide delay spread, also as illustrated inFIG.8A. Accordingly, for the focused case, aspects herein describe using iterative methods to precisely determine the impulse response corresponding to the delay of a ray that passes through the determined IRS reflection center.

FIG.8Billustrates an example defocused case800B for IRS aided positioning, in accordance with certain aspects of the present disclosure. The defocused case may refer to a scenario where wireless signals, transmitted by a network entity and reflected from one or more IRSs, are not focused towards a receiver device (e.g., a UE). Instead, as illustrated inFIG.8B, the surface phase of an IRS may be set such that waves appear as if they are propagating/radiating from a virtual focal point defined to be a point at any location behind the IRS. While the focusing case is concerned with waves converging on the UE, in the defocusing case, such waves may diverge and form a wide beam. Wide beams may be better for broadcasting data on a given frequency across a wider area, as compared to spot beams which are more concentrated in power. Accordingly, wide beams may be useful in positioning where a UE's location is unknown (e.g., unlike the focusing case). Further, wide beams may suffer from little, or no, effects of beam squint given energy arrives to a UE from a narrow region. Because there is no beam squint (e.g., delay spread), in the defocused case, as illustrated inFIG.8B, the peak of the impulse response may be narrow, and thus used as the impulse response needed in determining the position of the UE. However, for the defocused case, aspects herein may use iterative methods to precisely determine the IRS reflection center.

FIG.8Cillustrates an example general case800C for IRS aided positioning, in accordance with certain aspects of the present disclosure. The general case may refer to a scenario where wireless signals, transmitted by a network entity and reflected from one or more IRSs, are focused at a focal point at any arbitrary location, other than the UE's location. In particular, the general case may apply to scenarios where wireless signals are focused at real focal points, as well as, scenarios where wireless signals are focused at infinity (e.g., reflected rays are parallel). Similar to the focused case, the general case may suffer from beam squint; thus, the measured impulse response may have a wide delay spread, as illustrated inFIG.8C. Accordingly, for the general case, aspects herein describe using iterative methods to precisely determine the (1) IRS reflection center and the (2) impulse response corresponding to the delay of a ray that passes through the determined IRS reflection center.

FIG.9is a coordinate system900illustrating example vectors used to compute a reflection coefficient for focusing transmitter signals at a receiver (e.g., at an estimated position of the UE for the focusing case), a real focal point (e.g., for the general case), or a virtual focal point (e.g., for the defocused case), in accordance with certain aspects of the present disclosure. The computed reflection coefficient may be used to set the surface phase for the IRS. In certain aspects, by properly setting the surface phase (e.g. the phases of surface elements), a network entity's beam (e.g., gNB's beam) may be reflected from the IRS, where the surface phase is set, towards a UE (in downlink (DL)).

As illustrated inFIG.9, a reflection coefficient, Γn, at surface element “n” may be computed by the following equation:

Γn=exp⁡(j⁢2⁢π⁡(dn,tx+dn,rx)λ)
where dn,tx=|pn,tx|, pn,txis the vector from surface element “n” to the transmission (tx) point, dn,rx=|pn,rx|, pn,rxis the vector from surface element “n” to the receiver (rx) point, and λ is the operating wavelength. pn,rxmay depend on whether the transmitter signals are focused at a receiver (e.g., the UE), a real focal point, or a virtual focal point. Further, as shown inFIG.9, pnis the vector from the origin to surface element “n”, μtxis the unit-vector from the origin to the tx point, and μrxis the unit-vector from the origin to the rx point. μrxmay depend on whether the transmitter signals are focused at a receiver (e.g., the UE), a real focal point, or a virtual focal point. The term virtual focal point is used to mean a point behind the IRS where electromagnetic propagation appears to originate from. In other words, the term is used to mean a virtual image of a transmitter.

Beginning with the defocused case, in certain aspects, iterative methods may be used to precisely determine IRS reflection centers for one or more IRSs (e.g., an IRS reflection center per IRS, where the IRS reflection center may be different for each IRS) to be used for estimating the position of a UE.

FIG.10is a workflow illustrating example operations1000for determining IRS reflection center(s) for UE positioning in a defocused case, in accordance with certain aspects of the present disclosure. In certain aspects, operations1000may be performed by a UE, for example, by UE104in wireless communication network100.

Operations1000may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the wireless node in operations1000may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

Operations1000may begin, at1010, by the UE identifying first IRS reflection centers for one or more IRSs as a center of each of the one or more IRSs. For example, where four IRSs are being used for positioning, the UE may identify four IRS centers, e.g., one IRS center per IRS. The center of each IRS may be used as a starting point for determining the precise location of the IRS reflection center using iterative methods, as described in the following operations ofFIG.10.

At1020, the UE estimates a first position of the UE based on, at least, the first IRS reflection centers for the one or more IRSs. In certain aspects, the UE estimates the first position of the UE using time difference of arrival (TDOA) measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. Using the previous example, the UE may use the four centers of the four different IRSs and the TDOA measurements to calculate the first position of the UE. In calculating the first position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS.

In certain aspects, operations1000further include the UE measuring an impulse response to obtain an impulse response representation. The UE may use a peak point on the impulse response representation for the different signals reflected from the one or more IRSs for the TDOA measurements used to estimate the first position of the UE at1020.

At1030, the UE identifies second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and a virtual focal point for each of the one or more IRSs. The identified second IRS reflection centers may be different for each of the one or more IRSs. For example, using the previous example, the UE may identify four second IRS reflection centers, e.g., one second IRS reflection center per IRS.

Further, as mentioned previously, the virtual focal point for each IRS may be selected, and the UE may use the selected position for each IRS to set a surface phase for each of the IRSs. In certain aspects, the UE may also use positions of one or more network entities transmitting signals reflected from each IRS to the UE and a position, an orientation, and a size of each IRS to set the surface phase for each IRS. The surface phase may be set such that defocused beams are produced, in this case.

In certain aspects, the UE identifies the second IRS reflection centers for the one or more IRSs by, (1) at1032, identifying an intersection point on a surface area of the IRS for a straight line joining the UE at the previously estimated position and the virtual focal point and, (2) at1034, using the intersection point as the second IRS reflection center. For example, the UE may (1) produce an estimate of an intersection point on a first IRS, of the one or more IRSs, for a straight line between the previously estimated position of the UE (e.g., the first position of the UE) and a virtual focal point for the first IRS and (2) use this intersection point as the second IRS reflection center for the first IRS. Further, the UE may (1) produce an estimate of an intersection point on a second IRS, of the one or more IRSs, for a straight line between the previously estimated position of the UE (e.g., the first position of the UE) and a virtual focal point for the second IRS and (2) use this intersection point as the second IRS reflection center for the first IRS. The UE may perform such steps for each IRS until a second IRS reflection center is estimated for each of the IRSs. Identifying second IRS reflection centers for the one or more IRSs is described in more detail with respect toFIGS.11A and11B.

At1040, the UE estimates the second position of the UE based on, at least, the second IRS reflection centers for the one or more IRSs (e.g., identified at1030). In certain aspects, the UE estimates the second position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. Using the previous example, the UE may use the four second IRS reflections centers identified for the four different IRSs and the TDOA measurements to calculate the second position of the UE. In calculating the second position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS.

At1050, the UE determines whether convergence has been achieved. In certain aspects, convergence is achieved where a change in position of the UE, based on the second estimated position of the UE and a previously estimated position of the UE (e.g., the first estimated position of the UE), is less than a first threshold. The first threshold may be any number greater than zero, and in some cases, may be preconfigured.

In certain other aspects, convergence is achieved where a change in location of each respective IRS reflection center for each of the one or more IRSs is less than a second threshold. For example, using the previous example, convergence may be achieved when a change in the second estimated IRS reflection center for the first IRS (e.g., of the four IRSs) is less than a threshold, a change in the second estimated IRS reflection center for the second IRS is less than a threshold, a change in the second estimated IRS reflection center for the third IRS is less than a threshold, and a change in the second estimated IRS reflection center for the fourth IRS is less than a threshold.

The second threshold may be any number greater than zero, and in some cases, may be preconfigured. In certain aspects, the first threshold may be equal to the second threshold.

Accordingly, at1050, the UE may make one or both of these determinations. Where, at1050, convergence has been achieved, operations1000may be complete. In other words, the precise location of the IRS reflection center for each IRS of the one or more IRSs has been determined, and the UE position estimated using such IRS reflection centers may be used. According to aspects descried herein, the estimated UE position should provide an accurate estimate as to the UE's position, given, in some cases, multiple iterations are necessary to determine the IRS reflection center before both a precise IRS reflection center and estimated UE position can be used.

On the other hand, where at1050, convergence has not been achieved, at operation1060the UE may update the first IRS reflection centers as the second IRS reflection centers for the one or more IRSs. Following such an update, operations1020-1050(and in some cases,1060) may be repeated. In other words, IRS reflection centers and UE positions may be iteratively determined until convergence is achieved. For example, in some cases, the number of iterations of operations1000may be minimal where the initial estimate of the IRS reflection center for each IRS was close to the precise location of the IRS reflection, thereby allowing convergence to be achieved earlier. However, in some cases, multiple iterations of operations of1000may be necessary to precisely determine the IRS reflection center for each IRS (e.g., to precisely determine the UE's position), and accordingly achieve convergence. According to aspects descried herein, the estimated UE position should provide an accurate estimate as to the UE's position, given, in some cases, multiple iterations are necessary to determine the IRS reflection center before both a precise IRS reflection center and estimated UE position can be used.

Operations1000may be understood with respect to the example provided inFIGS.11A and11B. In particular,FIGS.11A and11Bprovide an example1100A,1100B, respectively, illustrating iterative techniques for determining a precise IRS reflection center for an IRS, in accordance with certain aspects of the present disclosure.

As illustrated inFIG.11A, a virtual focal point1102may be situated behind an IRS106(e.g., such as IRS106illustrated inFIGS.1,2, and4B). A surface phase for the IRS may be set, based on the location of the virtual focal point, such that defocused beams are produced, in this example. Similar to1010inFIG.10, as a first step, a UE104(e.g., such as UE104illustrated inFIGS.1,2, and4B) may identify a first IRS reflection center as the center (e.g., origin for the X axis and Y axis) of IRS106. UE104may use the center of IRS106in calculating a first estimated position of UE104illustrated inFIG.11A.

Similar to1030inFIG.10, as a next step, UE104may identify a second IRS reflection center of IRS106. In certain aspects, to identify the second IRS reflection center, a straight line may be drawn between virtual focal point1102and the previously estimated position of UE104(e.g., in this case, the first estimated position of UE104). The second IRS reflection center may be the point on IRS106where the line intersects IRS106. This intersection point on IRS106may be used as the second IRS reflection center.

In certain aspects (e.g., not illustrated inFIG.11A), to identify the second IRS reflection center, UE104may identify an intersection point on IRS106for a straight line joining UE104at the previously estimated position and virtual focal point1102. UE104may then calculate the second IRS reflection center for IRS106as a weighted average of a position of the intersection point on the IRS and one or more previous intersection points.

In certain aspects (e.g., not illustrated inFIG.11A), UE104may determine the straight line joining UE104at the previously estimated position for UE104and virtual focal point1102does not intersect a surface area of IRS106. For example, no intersection point exists on IRS106for the line drawn. Accordingly, in certain aspects, UE104may manipulate the previously estimated position of UE104to be an adjusted position of UE104and redraw the straight line (e.g., draw a second straight line) connecting virtual focal point1102to the adjusted position of UE104to find the new intersection point on IRS106. In certain other aspects, UE104may manipulate the first IRS reflection center (e.g., as not the center of IRS106, given this is the first iteration) and calculate a new first estimated position of UE104, such that the new first estimated position of UE104is an adjusted position of UE104. UE104may then redraw the straight line (e.g., draw a second straight line) connecting virtual focal point1102to the adjusted position of UE104to find the new intersection point on IRS106. The new intersection point on IRS106may be used as the second IRS reflection center.

Similar to1040inFIG.10, as a next step, UE104may estimate a second position of UE104based on, at least, the second IRS reflection center for IRS106. The second estimated position of UE104, using the second IRS reflection center for IRS106, is illustrated inFIG.11B.

Subsequently, UE104may determine whether convergence has been achieved (e.g., similar to100inFIG.10). As mentioned, in certain aspects, convergence is achieved where a change in position of the UE, based on the second estimated position of the UE and a previously estimated position of the UE (e.g., the first estimated position of the UE), is less than a first threshold. Accordingly, as illustrated inFIG.11B, where the delta between the first estimated position of the UE and the second estimated position of the UE is less than the first threshold, the second IRS reflection center is determined to be the precise point in space to use in estimating the position of UE104. Accordingly, the second estimated position of the UE estimated using the second IRS reflection center may be determined to be the precise location of UE104. On the other hand, where the delta is greater than the first threshold, UE104may determine third IRS reflection centers, estimate a third position of the UE using the third IRS reflection centers, and again determine whether convergence is achieved. UE104may continue performing these iterative steps until convergence is achieved.

Although not illustrated inFIG.11B, in certain aspects, convergence may also be achieved where a change in location between the first IRS reflection center and the second IRS reflection center for IRS106is less than a second threshold.

As an alternative to the defocused case, in certain aspects, wireless signals, transmitted by a network entity and reflected from one or more IRSs, may be focused towards a receiver device (e.g., a UE) (referred to herein as the focused case). For the focused case, iterative methods may be used to precisely estimate the impulse response corresponding to the delay of a ray that is reflected at an IRS reflection center.

FIGS.12A and12Bare a workflow illustrating example operations1200for determining IRS reflection center(s) for UE positioning in a focused case, in accordance with certain aspects of the present disclosure. In certain aspects, operations1200may be performed by a UE, for example, by UE104in wireless communication network100.

Operations1200may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the wireless node in operations1200may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

As mentioned herein, in a focused case, to be able to set the surface phase of each IRS of one or more IRSs reflecting signals to a UE, such that the signals are focused towards the specific UE, a position of the UE may have been previously estimated. Accordingly, operations1200may begin, at operation1210, by the UE setting the surface phase of each IRS such that each IRS is focused on top of the estimated position of the UE.

At1215, the UE computes, for each IRS, a first expected impulse response to obtain a first expected impulse response representation. The UE may use the estimated position of the UE to compute the first expected impulse response. The first expected impulse response representation may be a first histogram of expected delays for a plurality of rays through different points over a surface area of the corresponding IRS. An example of a first expected impulse representation is illustrated inFIG.13at1305. In particular,FIG.13is a diagram1300illustrating an example method for aligning an expected impulse response representation with a measured impulse response representation, in accordance with certain aspects of the present disclosure. The UE may compute the first expected impulse response, to obtain the first expected impulse response representation, using known network entity position(s), known IRS size, position, and orientation, as well as, the current estimated position of the UE. On this impulse response representation, the UE may identify a point, or more specifically a delay value, corresponding a ray reflected from the IRS reflection center (indicated by a triangle inFIG.13at1305). This point, or the delay value, can be referred to as the expected impulse response of the IRS reflection center.

At1220, the UE measures, for each IRS, a first impulse response from the IRS using one or more first transmissions from a network entity that are reflected to the UE using the IRS, to obtain a first measured impulse response representation. The first measured impulse response representation may be a first histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS. An example of a first measured impulse representation is illustrated inFIG.13at1310.

At1225, the UE adjusts, for each IRS, by a first delay adjustment, a delay of the first expected impulse response representation to align in time with the first measured impulse response representation. In particular, at1225, the UE may adjust the gain and delay of the expected impulse response to match the measured impulse response, for example in a least-squares sense. Alignment of the first measured impulse response representation with the first expected impulse response representation is illustrated inFIG.13at1315. The point on the adjusted expected impulse response corresponding to a ray that is reflected from the IRS reflection center is indicated by a triangle. This point, or the associated delay value, may be referred to as the impulse response of the IRS reflection center.

At1230, the UE determines, for each IRS, a first impulse response for a first ray reflected from the first IRS reflection center over the surface area of the IRS. This first point may be used as a reflection center for the focused case, and will remain fixed throughout the iterative process. As mentioned, the measured impulse response representation provides a graphical display of measured delays mapped to different rays through different points over a surface area of the corresponding IRS. For example, a center point on the histogram might represent a measured impulse response for a center point on a corresponding IRS, while edge points on the histogram might represent measured impulse responses for points along the edges of the IRS. Thus, at1230, the UE may determine a first impulse response for a first point (e.g., the selected reflection center) on the IRS using the histogram.

Subsequently, at1235, the UE estimates a first position of the UE based on, at least, the first impulse response each of the one or more IRSs. In certain aspects, the UE estimates the first position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. In calculating the first position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS. In setting up the positioning equations for the UE, the UE may use TDOA corresponding to the reflection center and the associated first impulse response for each IRS

At1240, the UE determines whether convergence has been achieved. In certain aspects, convergence is achieved where a change in position of the UE, based on the first estimated position of the UE and the previously estimated position of the UE (e.g., the estimated position of the UE known by the UE prior to operations1200), is less than a first threshold. The first threshold may be any number greater than zero, and in some cases, may be preconfigured.

Where, at1240, convergence has been achieved, operations1200may be complete. In other words, the (TDOA of) the first impulse response on the expected impulse responses has been precisely determined. The UE position estimated using such IRS reflection centers, and such impulse responses, may be used.

On the other hand, where at1240, convergence has not been achieved, at1250(e.g., illustrated inFIG.12B), the UE computes, for each IRS, a second expected impulse response to obtain a second expected impulse response representation. The second expected impulse response representation may be a second histogram of expected delays for the plurality of rays through the different points over the surface area of the IRS. The UE may compute the second expected impulse response using known network entity position(s), known IRS size, position, and orientation, as well as, the previously estimated (e.g., the most recently estimated) position of the UE (e.g., at this point in the workflow, the first position of the UE estimated at1235).

At1255, the UE measures, for each IRS, a second impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a second measured impulse response representation. The second measured impulse response representation may be a second histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS.

At1260, the UE adjusts, for each IRS, by a second delay adjustment, a delay of the second expected impulse response representation to align in time with the second measured impulse response representation. In particular, at1260, the UE may adjust the gain and delay of the expected impulse response to match the measured impulse response, for example in a least-squares sense.

At1265, the UE determines, for each IRS, a second impulse response for the first ray reflected from the first IRS reflection center over the surface area of the IRS. Subsequently, at1270, the UE estimates the second position of the UE is based on, at least, the second impulse response for each of the one or more IRSs. In certain aspects, the UE estimates the second position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. In calculating the second position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS.

At1275, the UE determines whether convergence has been achieved. In certain aspects, convergence is achieved where a change in position of the UE, based on the second estimated position of the UE (e.g., estimated at1270) and the previously estimated position of the UE (e.g., the first estimated position of the UE estimated at1235), is less than the first threshold.

Where, at1275, convergence has been achieved, operations1200may be complete. In other words, the precise expected impulse response, and hence the TDOA of the second impulse response of a ray reflected from the reflection center has been determined, and the UE position previously estimated may be used.

On the other hand, where at1275, convergence has not been achieved, operations1250-1275may be repeated to (1) compute a new expected impulse response, using a previously estimated position of the UE, to obtain a new expected impulse response representation, (2) measure a new impulse response from the IRS to obtain a new measured impulse response representation, (3) align the new expected impulse response and the new measured impulse response to determine a new second impulse response for a first ray reflected from the IRS reflection center for each IRS, (4) use the TDOA corresponding to the new second impulse response for each IRS to calculate a new estimated position of the UE, and determine whether convergence has been achieved. Operations245-1275may be iteratively performed until convergence is achieved.

In certain aspects, the iterative steps illustrated inFIG.10(e.g., used in determining IRS reflection center(s) for UE positioning in defocused cases) may be performed in combination with the iterative steps illustrated inFIGS.12A and12B(e.g., used in determining IRS reflection center(s) for UE positioning in defocused cases). In particular, the iterative steps illustrated inFIG.10may be performed prior to the iterative steps illustrated inFIGS.12A and12B. The iterative steps for the defocused case may be initially used to determine an estimated position of the UE. This estimated position of the UE may allow for focusing of signals on the estimated position of the UE, such that iterative steps for the focused case may be performed, given the focused case requires an initial estimate/knowledge of the UE's position. In certain aspects, performing iterative steps for the focused case after performing iterative steps for the defocused case may provide improved results, in terms of IRS position and UE position estimation precision, due to the higher energy gain of focused signals as compared to defocused signals.

Alternatively, in certain aspects, after performing iterative steps for the defocused case, the UE may assume an intermediate position of the UE as the second position of the UE determined by the iterative steps illustrated inFIG.10. The UE may focus the one or more IRSs on top of the second position of the UE, measure an impulse response of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities, and estimate a third position of the UE using TDOA measurements using third IRS reflection centers for the one or more IRSs, wherein the third IRS reflections centers for the one or more IRSs are at a center of each of the one or more IRS and a peak point on the impulse response. This may be one case where the IRS position is further refined using focusing techniques; however, in this case, beam-squint mitigating techniques may be used when estimating the third position of the UE using TDOA measurements such that a peak point on the impulse response may be used for determining the UE's position.

As an alternative to the defocused case, the focused case, and the combination of the defocused case with the focused case, in certain aspects, wireless signals, transmitted by a network entity and reflected from one or more IRSs, may be focused at a focal point at any arbitrary location (e.g., a real focal point), other than the UE's location (referred to herein as the general case). For the general case, iterative methods may be used to precisely determine IRS reflection centers for one or more IRSs (e.g., an IRS reflection center per IRS, where the IRS reflection center may be different for each IRS) to be used for estimating the position of a UE. Further, iterative methods may be used to determine the impulse response corresponding to the delay of a ray that passes through the determined IRS reflection center.

In the general case, an estimated position of the UE may not be known and the surface phase of each IRS of one or more IRSs reflecting signals to a UE is set such that the signals are focused towards the focal point. In certain aspects, the focal point may be a real focal point. In certain aspects, the focal point may be a virtual focal point.

FIGS.14A and14Bare a workflow illustrating example operations1400for determining IRS reflection center(s) for UE positioning in a general case, in accordance with certain aspects of the present disclosure. In certain aspects, operations1400may be performed by a UE, for example, by UE104in wireless communication network100.

Operations1400may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the wireless node in operations1400may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

Operations1400may begin, at1405, by the UE identifying first IRS reflection centers for one or more IRSs as a center of each of the one or more IRSs. For example, where four IRSs are being used for positioning, the UE may identify four IRS centers, e.g., one IRS center per IRS. The center of each IRS may be used as a starting point for determining the precise location of the IRS reflection center using iterative methods, as described in the following operations ofFIG.14.

At operation1410, the UE measures an initial impulse response from each of the one or more IRSs, to obtain an initial impulse response representation for each of the one or more IRSs. At operation1415, the UE estimates a first position of the UE based on, at least: the first IRS reflection centers for the one or more IRSs and a peak point on the initial impulse response representation for each of the one or more IRSs. In certain aspects, the UE estimates the first position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. In calculating the first position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS.

At operation1420, the UE identifies second IRS reflection centers for the one or more IRSs using a previously estimated position of the UE and a focal point for each of the one or more IRSs. The identified second IRS reflection centers may be different or the same for each of the one or more IRSs. For example, using the previous example, the UE may identify four second IRS reflection centers, e.g., one second IRS reflection center per IRS, where each second IRS reflection center is different or the same as a second IRS reflection of one or more of the four IRSs.

In certain aspects, the UE identifies the second IRS reflection centers for the one or more IRSs by, (1) at1422, identifying an intersection point on a surface area of the IRS for an (infinitely) straight line passing through the UE at the previously estimated position and the focal point and, (2) at1424, using the intersection point as the second IRS reflection center. For example, the UE may (1) produce an estimate of an intersection point on a first IRS, of the one or more IRSs, for a straight line passing through the previously estimated position of the UE (e.g., the first position of the UE) and the focal point and (2) use this intersection point as the second IRS reflection center for the first IRS. Further, the UE may (1) produce an estimate of an intersection point on a second IRS, of the one or more IRSs, for a straight line passing through the previously estimated position of the UE (e.g., the first position of the UE) and focal point for the second IRS and (2) use this intersection point as the second IRS reflection center for the first IRS. The UE may perform such steps for each IRS until a second IRS reflection center is estimated for each of the IRSs.

In certain aspects (e.g., not illustrated inFIG.14A), to identify the second IRS reflection center, UE104may identify an intersection point on the IRS for a straight line passing through the UE at the previously estimated position and the focal point. The UE may then calculate the second IRS reflection center for the IRS as a weighted average of a position of the intersection point on the IRS and one or more previously estimated positions of the intersection points.

In certain aspects (e.g., not illustrated inFIG.14A), the UE may determine the straight line passing through the UE at the previously estimated position for UE and the focal point does not intersect a surface area of IRS. For example, no intersection point exists on the IRS for the line drawn. Accordingly, in certain aspects, the UE may manipulate the previously estimated position of UE to be an adjusted position of the UE and redraw the straight line (e.g., draw a second straight line) connecting focal point to the adjusted position of UE to find the new intersection point on the IRS. In certain other aspects, the UE may manipulate the first IRS reflection center and calculate a new first estimated position of the UE, such that the new first estimated position of the UE is an adjusted position of the UE. The UE may then redraw the straight line (e.g., draw a second straight line) connecting the focal point to the adjusted position of the UE to find the new intersection point on the IRS. The new intersection point on the IRS may be used as the second IRS reflection center.

At1430, the UE computes, for each IRS, an expected impulse response to obtain an expected impulse response representation. The expected impulse response representation may be a histogram of expected delays for the plurality of rays through the different points over the surface area of the IRS. The UE may compute the expected impulse response using known network entity position(s), known IRS size, position, and orientation, as well as, the previously estimated (e.g., the most recently estimated) position of the UE (e.g., at this point in the workflow, the first position of the UE estimated at1415).

At1435, the UE measures, for each IRS, a measured impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a measured impulse response representation. The measured impulse response representation may be a histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS.

At1440, the UE adjusts, for each IRS, by a delay adjustment, a delay of the expected impulse response representation to align in time with the measured impulse response representation. In particular, at1440, the UE may adjust the gain and delay of the expected impulse response to match the measured impulse response, for example in a least-squares sense.

At1445, the UE determines, for each IRS, a first impulse response for a first ray of the plurality of rays reflected from a first point (e.g., the estimated reflection center) of the different points over the surface area of the IRS. Subsequently, at1450, the UE estimates a second position of the UE based on, at least, the second IRS reflection centers for each of the one or more IRSs and the second impulse response for each of the one or more IRSs. In certain aspects, the UE estimates the second position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities. In calculating the second position of the UE, the UE may have knowledge of (1) a position of each of the one or more network entities transmitting signals reflected from each IRS to the UE and (2) a position, an orientation, and a size of each IRS.

At1455, the UE determines whether convergence has been achieved. In certain aspects, convergence is achieved where a change in position of the UE, based on the second estimated position of the UE and the previously estimated position of the UE (e.g., the first estimated position of the UE estimated at1415), is less than a first threshold.

Where, at1455, convergence has been achieved, operations14000may be complete. In other words, the precise location of the IRS reflection center for each IRS of the one or more IRSs has been determined, and the UE position estimated using such IRS reflection centers may be used.

On the other hand, where at1455, convergence has not been achieved, operations1420-1455may be repeated to (1) identify new IRS reflection centers using the previously estimated position of the UE (e.g., previously estimated at1450), (2) compute a new expected impulse response, using the previously estimated position of the UE, to obtain a new expected impulse response representation, (3) measure a new impulse response from the IRS to obtain a new measured impulse response representation, (4) align the new expected impulse response and the new measured impulse response to determine a new point for each IRS, (5) use the new point for each IRS to calculate a new estimated position of the UE, and determine whether convergence has been achieved. Operations1420-1455may be iteratively performed until convergence is achieved.

FIG.15is a flow diagram illustrating example operations1500for wireless communication by a UE, in accordance with certain aspects of the present disclosure. In certain aspects, operations1500may be performed by a UE, for example, by UE104in wireless communication network100.

Operations1500may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor280ofFIG.2). Further, the transmission and reception of signals by the wireless node in operations1400may be enabled, for example, by one or more antennas (e.g., antennas252ofFIG.2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor280) obtaining and/or outputting signals.

Operations1500may begin, at1505, by the UE setting a surface phase for each IRS of one or more IRSs based on a real focal point or a virtual focal point.

At1510, the UE identifies, for each IRS of the one or more IRSs, a first IRS reflection center. At1515, the UE measures, for each IRS of the one or more IRSs, a first impulse response from the IRS using one or more first transmissions from a network entity that are reflected to the UE using the IRS, to obtain a first measured impulse response representation, wherein the first measured impulse response representation comprises a first histogram of measured delays for a plurality of rays through different points over a surface area of the IRS.

At1520, the UE determines, for each IRS of the one or more IRSs, a first impulse response for a first ray reflected from the first IRS reflection center of the IRS. At1525, the UE estimates a first position of the UE based on, at least, the first IRS reflection centers for each of the one or more IRSs and the first impulse responses for each of the one or more IRSs.

At1530, the UE estimates a second position of the UE in an iterative manner until one or more conditions are satisfied. In certain aspects, estimating the second position of the UE includes: for each IRS of the one or more IRSs, identifying a second IRS reflection center, measuring a second impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a second measured impulse response representation, wherein the second measured impulse response representation comprises a second histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS, determining a second impulse response for a second ray reflected from the second IRS reflection center of the IRS, and estimating the second position of the UE based on, at least, the second IRS reflection centers for each of the one or more IRSs and the second impulse responses for each of the one or more IRSs.

Example Wireless Communication Devices

FIG.16depicts an example communications device1600that includes various components operable, configured, or adapted to perform operations for the techniques disclosed herein, such as the operations depicted and described with respect toFIGS.10,12A,12B,14A,14B, and15. In some examples, communication device1600may be a UE104as described, for example with respect toFIGS.1and2.

Communications device1600includes a processing system1602coupled to a transceiver1608(e.g., a transmitter and/or a receiver). Transceiver1608is configured to transmit (or send) and receive signals for the communications device1600via an antenna1610, such as the various signals as described herein. Processing system1602may be configured to perform processing functions for communications device1600, including processing signals received and/or to be transmitted by communications device1600.

Processing system1602includes one or more processors1620coupled to a computer-readable medium/memory1640via a bus1606. In certain aspects, computer-readable medium/memory1640is configured to store instructions (e.g., computer-executable code) that when executed by the one or more processors1520, cause the one or more processors1620to perform the operations illustrated inFIGS.10,12A,12B,14A.14B, and15, or other operations for performing the various techniques discussed herein for IRS aided UE positioning.

In the depicted example, computer-readable medium/memory1640stores code1641for identifying, code1642for using, code1643for determining, code1644for manipulating, code1645for computing/calculating, code1646for measuring, code1647for assuming, code1648for focusing, code1649for aligning, code1650for estimating, and code1651for setting.

In the depicted example, the one or more processors1620include circuitry configured to implement the code stored in the computer-readable medium/memory1640, including circuitry1621for identifying, circuitry1622for using, circuitry1623for determining, circuitry1624for manipulating, circuitry1625for computing/calculating, circuitry1626for measuring, circuitry1627for assuming, circuitry1628for focusing, circuitry1629for aligning, circuitry1630for estimating, and circuitry1631for setting.

Various components of communications device1600may provide means for performing the methods described herein, including with respect toFIGS.10,12A,12B,14A.14B, and15.

In some examples, means for transmitting or sending (or means for outputting for transmission) may include the transceivers254and/or antenna(s)252of the UE104illustrated inFIG.2and/or transceiver1608and antenna1610of the communication device1600inFIG.16.

In some examples, means for receiving (or means for obtaining) may include the transceivers254and/or antenna(s)252of UE104illustrated inFIG.2and/or transceiver1608and antenna1610of the communication device1600inFIG.16.

In some cases, rather than actually transmitting, for example, signals and/or data, a device may have an interface to output signals and/or data for transmission (a means for outputting). For example, a processor may output signals and/or data, via a bus interface, to a radio frequency (RF) front end for transmission. Similarly, rather than actually receiving signals and/or data, a device may have an interface to obtain the signals and/or data received from another device (a means for obtaining). For example, a processor may obtain (or receive) the signals and/or data, via a bus interface, from an RF front end for reception. In various aspects, an RF front end may include various components, including transmit and receive processors, transmit and receive MIMO processors, modulators, demodulators, and the like, such as depicted in the examples inFIG.2.

In some examples, means for identifying, means for using, means for determining, means for manipulating, means for computing/calculating, means for measuring, means for assuming, means for focusing, means for aligning, means for estimating, and means for setting may include various processing system components, such as: the one or more processors1620inFIG.16, or aspects of UE104depicted inFIG.2, including receive processor258, transmit processor264, TX MIMO processor266, and/or controller/processor280(including positioning component241).

Notably,FIG.16is an example, and many other examples and configurations of communication device1600are possible.

EXAMPLE CLAUSES

Implementation examples are described in the following numbered clauses:

Clause 1: A method for wireless communication by a user equipment (UE), comprising: setting a surface phase for each intelligent reflecting surface (IRS) of one or more IRSs based on a real focal point or a virtual focal point; for each IRS of the one or more IRSs: identifying a first IRS reflection center; measuring a first impulse response from the IRS using one or more first transmissions from a network entity that are reflected to the UE using the IRS, to obtain a first measured impulse response representation, wherein the first measured impulse response representation comprises a first histogram of measured delays for a plurality of rays through different points over a surface area of the IRS; determining a first impulse response for a first ray reflected from the first IRS reflection center of the IRS; estimating a first position of the UE based on, at least, the first IRS reflection centers for each of the one or more IRSs and the first impulse responses for each of the one or more IRSs; and estimating a second position of the UE in an iterative manner until one or more conditions are satisfied.

Clause 2: The method of Clause 1, wherein estimating the second position of the UE comprises: for each IRS of the one or more IRSs: identifying a second IRS reflection center; measuring a second impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a second measured impulse response representation, wherein the second measured impulse response representation comprises a second histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; determining a second impulse response for a second ray reflected from the second IRS reflection center of the IRS; and estimating the second position of the UE based on, at least, the second IRS reflection centers for each of the one or more IRSs and the second impulse responses for each of the one or more IRSs.

Clause 3: The method of any one of Clauses 1 or 2, wherein the one or more conditions comprise, at least one of: a change in position of the UE based on the second position of the UE and a previously estimated position of the UE is less than a first threshold, or a maximum number of iterations have been performed.

Clause 4: The method of any one of Clauses 1-3, wherein the one or more conditions further comprise: a change in location of each respective IRS reflection center for each IRS of the one or more IRSs is less than a second threshold.

Clause 5: The method of any one of Clauses 1-4, wherein: the first IRS reflection center identified for each IRS is identified as a center point of each IRS; the first impulse response determined for each IRS comprises a maximum impulse response represented as a peak impulse response in the first measured impulse response representation; and the first position of the UE position is estimated based on, at least, the center point of each IRS of the one or more IRSs and the maximum impulse response for each IRS of the one or more IRSs.

Clause 6: The method of any one of Clauses 2-5, wherein identifying the second IRS reflection center for each IRS comprises: identifying an intersection point on the surface area of the IRS for a straight line passing through the UE at: a previously estimated position of the UE and the focal point; or the previously estimated position of the UE and the virtual focal point; and using the intersection point as the second IRS reflection center.

Clause 7: The method of any one of Clauses 2-6, wherein identifying the second IRS reflection center for each IRS comprises: determining a first straight line passing through the UE at: a previously estimated position of the UE and the focal point; or the previously estimated position of the UE and the virtual focal point does not intersect the surface area of the IRS; manipulating the first IRS reflection center to estimate an adjusted position of the UE such that a second straight line passing through the UE at: the adjusted position of the UE and the focal point; or the adjusted position of the UE and the virtual focal point does intersect the surface area of the IRS at an intersection point; identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 8: The method of any one of Clauses 2-7, wherein identifying the second IRS reflection center for each IRS comprises: determining a first straight line passing through the UE at: a previously estimated position of the UE and the focal point; or the previously estimated position of the UE and the virtual focal point does not intersect a surface area of the IRS; manipulating the previously estimated position of the UE to be an adjusted position of the UE such that a second straight line passing through the UE at: the adjusted position of the UE and the focal point; or the adjusted position of the UE and the virtual focal point does intersect the surface area of the IRS at an intersection point; identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 9: The method of any one of Clauses 2-8, wherein identifying the second IRS reflection centers for the one or more IRSs using a previously estimated positon of the UE and the virtual focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: determining a first straight line passing through the UE at the previously estimated position and the virtual focal point does not intersect the surface area of the IRS; manipulating the previously estimated position of the UE to be an adjusted position of the UE such that a second straight line passing through the UE at the adjusted position of the UE and the virtual focal point does intersect the surface area of the IRS at an intersection point; identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 10: The method of any one of Clauses 2-9, wherein when the surface phase for each IRS of the one or more IRSs is set based on the real focal point, the second IRS reflection center identified for each IRS is identified as a center point of the surface area of each IRS.

Clause 11: The method of any one of Clauses 2-10, when the surface phase for each IRS of the one or more IRSs is set based on the real focal point, wherein the real focal point comprises a previously estimated position of the UE, the second IRS reflection center identified for each IRS is identified as a center point of the surface area of each IRS.

Clause 12: The method of any one of Clauses 2-11, wherein for each IRS: the second impulse response determined comprises a maximum impulse response represented as a peak impulse response in the second measured impulse response representation when beam-squint mitigating techniques are used for the IRS.

Clause 13: The method of any one of Clauses 2-12, wherein when the surface phase for each IRS of the one or more IRSs is set based on the virtual focal point, the second impulse response determined comprises a maximum impulse response represented as a peak impulse response in the second measured impulse response representation.

Clause 14: The method of any one of Clauses 2-13, wherein determining, for each IRS of the one or more IRSs, the second impulse response for the second ray reflected from the second IRS reflection center of the IRS comprises: computing an expected impulse response for the plurality of the rays through the different points over the surface area of the IRS, using a previously estimated position of the UE, to obtain an expected impulse response representation, wherein the expected impulse response representation comprises a histogram of expected delays for the plurality of the rays through the different points over the surface area of the IRS; identifying an expected impulse response, using the expected impulse response representation, as a delay value corresponding to a ray that is reflected at the second IRS reflection center; and adjusting, by a delay adjustment, a delay of the expected impulse response representation to align in time with the second measured impulse response representation, wherein the second impulse response is determined using the delay adjustment and the expected impulse response.

Clause 15: The method of any one of Clauses 1-14, wherein the UE estimates the first position of the UE using time difference of arrival (TDOA) measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 16: The method of any one of Clauses 2-15, wherein the UE estimates the first position and the second position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 17: The method of any one of Clauses 1-16, wherein the UE has knowledge of: a position for each network entity of one or more network entities transmitting signals reflected from the one or more IRSs to the UE; and a position, an orientation, and a size of each of the one or more IRSs.

Clause 18: A method for wireless communication by a user equipment (UE), comprising: identifying first intelligent reflecting surface (IRS) reflection centers for one or more IRSs as a center of each of the one or more IRSs; estimating a first position of the UE based on, at least, the first IRS reflection centers for the one or more IRSs; and estimating a second position of the UE in an iterative manner until at least one of: a change in position of the UE based on the second position of the UE and a previously estimated position of the UE is less than a first threshold, or a change in location of each respective IRS reflection center for each of the one or more IRSs is less than a second threshold, wherein estimating the second position of the UE in the iterative manner comprises: identifying second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and a virtual focal point for each of the one or more IRSs; and estimating the second position of the UE based on, at least, the second IRS reflection centers for the one or more IRSs.

Clause 19: The method of Clause 18, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and the virtual focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: identifying an intersection point on a surface area of the IRS for a straight line joining the UE at the previously estimated position and the virtual focal point; and using the intersection point as the second IRS reflection center.

Clause 20: The method of any one of Clauses 18 or 19, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and the virtual focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: determining a first straight line joining the UE at the previously estimated position and the virtual focal point does not intersect a surface area of the IRS; manipulating the first IRS reflection center to estimate an adjusted position of the UE such that a second straight line joining the UE at the adjusted position of the UE and the virtual focal point does intersect the surface area of the IRS at an intersection point; identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 21: The method of any one of Clauses 18-20, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and the virtual focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: determining a first straight line joining the UE at the previously estimated position and the virtual focal point does not intersect a surface area of the IRS; manipulating the previously estimated position of the UE to be an adjusted position of the UE such that a second straight line joining the UE at the adjusted position of the UE and the virtual focal point does intersect the surface area of the IRS at an intersection point; identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 22: The method of any one of Clauses 18-21, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated position of the UE and the virtual focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: identifying an intersection point on the IRS for a straight line joining the UE at the previously estimated position and the virtual focal point; and calculating the second IRS reflection center as a weighted average of a position of the intersection point on the IRS corresponding to one or more previously estimated positions of the UE.

Clause 23: The method of any one of Clauses 18-22, wherein the UE estimates the first position of the UE and the second position of the UE using time difference of arrival (TDOA) measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 24: The method of Clause 23, further comprising: measuring an impulse response to obtain an impulse response representation, wherein the UE uses a peak point on the impulse response representation for the different signals reflected from the one or more IRSs for the TDOA measurements.

Clause 25: The method of any one of Clauses 18-24, wherein the UE has knowledge of: a position for each network entity of one or more network entities transmitting signals reflected from the one or more IRSs to the UE; and a position, an orientation, and a size of each of the one or more IRSs.

Clause 26: The method of any one of Clauses 18-25, wherein a surface phase for each of the one or more IRSs is set based, at least in part, on a position of the virtual focal point.

Clause 27: The method of any one of Clauses 18-26, wherein immediately prior to estimating the first position of the UE, the UE is unaware of a position of the UE.

Clause 28: The method of any one of Clauses 18-27, further comprising: assuming an intermediate position of the UE as the second position; focusing the one or more IRSs on top of the second position of the UE; measuring an impulse response of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities; and estimating a third position of the UE using TDOA measurements using: third IRS reflection centers for the one or more IRSs, wherein the third IRS reflections centers for the one or more IRSs are at a center of each of the one or more IRSs; and a peak point on the impulse response.

Clause 29: The method of Clause 28, wherein beam-squint mitigating techniques are used when estimating the third position of the UE using TDOA measurements.

Clause 30: The method of any one of Clauses 18-29, further comprising: assuming an intermediate position of the UE as the second position; focusing the one or more IRSs on top of the second position of the UE; for each IRS of the one or more IRSs: computing a first expected impulse response, using the second position of the UE, to obtain a first expected impulse response representation, wherein the first expected impulse response representation comprises a first histogram of expected delays for a plurality of rays through different points over a surface area of the IRS; measuring a first impulse response from the IRS using one or more first transmissions from a network entity that are reflected to the UE using the IRS, to obtain a first measured impulse response representation, wherein the first measured impulse response representation comprises a first histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; adjusting, by a first delay adjustment, a delay of the first expected impulse response representation to align in time with the first measured impulse response representation; and determining a first impulse response for a first ray reflected from the first reflection center over the surface area of the IRS; estimating a third position of the UE based on, at least, the first IRS reflection centers for each of the one or more IRSs and the first impulse responses for each of the one or more IRSs; determining a change in position of the UE based on the third position of the UE and the second position of the UE is greater than a third threshold; and estimating a fourth position of the UE in an iterative manner until the change in position of the UE based on the fourth position of the UE and a previously estimated position of the UE is less than the third threshold.

Clause 31: The method of Clause 30, wherein estimating the fourth position of the UE in the iterative manner comprises, for each of the one or more IRSs: computing a second expected impulse response using the previously estimated position of the UE, to obtain a second expected impulse response representation, wherein the second expected impulse response representation comprises a second histogram of expected delays for the plurality of rays through the different points over the surface area of the IRS; measuring a second impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a second measured impulse response representation, wherein the second measured impulse response representation comprises a second histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; adjusting, by a second delay adjustment, a delay of the second expected impulse response representation to align in time with the second measured impulse response representation; and determining a second impulse response for the first ray reflected from the first IRS reflection center over the surface area of the IRS, wherein estimating the fourth position of the UE based on, at least, the first IRS reflection centers for each of the one or more IRSs and the second impulse responses for each of the one or more IRSs.

Clause 32: The method of any one of Clauses 30 or 31, wherein the UE estimates the third position of the UE and the fourth position of the UE using TDOA measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 33: A method for wireless communication by a user equipment (UE), comprising: for each intelligent reflecting surface (IRS) of one or more IRSs focused on top of an estimated position of the UE and from which the UE receives reflected signals: computing a first expected impulse response, using the estimated position of the UE, to obtain a first expected impulse response representation, wherein the first expected impulse response representation comprises a first histogram of expected delays for a plurality of rays through different points over a surface area of the IRS; measuring a first impulse response from the IRS using one or more first transmissions from a network entity that are reflected to the UE using the IRS, to obtain a first measured impulse response representation, wherein the first measured impulse response representation comprises a first histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; adjusting, by a first delay adjustment, a delay of the first expected impulse response representation to align in time with the first measured impulse response representation; and determining a first impulse response for a first ray reflected from the first IRS reflection center over the surface area of the IRS; estimating a first position of the UE based on, at least, the first impulse response for each of the one or more IRSs; determining a change in position of the UE based on the first position of the UE and the estimated position of the UE is greater than a threshold; and estimating a second position of the UE in an iterative manner until the change in position of the UE based on the second position of the UE and a previously estimated position of the UE is less than the threshold.

Clause 34: The method of Clause 33, wherein estimating the second position of the UE in the iterative manner comprises, for each of the one or more IRSs: computing a second expected impulse response using the previously estimated position of the UE, to obtain a second expected impulse response representation, wherein the second expected impulse response representation comprises a second histogram of expected delays for the plurality of rays through the different points over the surface area of the IRS; measuring a second impulse response from the IRS using one or more second transmissions from the network entity that are reflected to the UE using the IRS, to obtain a second measured impulse response representation, wherein the second measured impulse response representation comprises a second histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; adjusting, by a second delay adjustment, a delay of the second expected impulse response representation to align in time with the second measured impulse response representation; and determining a second impulse response for the first ray reflected from the first IRS reflection center over the surface area of the IRS, wherein estimating the second position of the UE is based on, at least, the second impulse response for each of the one or more IRSs.

Clause 35: The method of any one of Clauses 33 or 34, wherein the UE estimates the first position of the UE and the second position of the UE using time difference of arrival (TDOA) measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 36: The method of any one of Clauses 33-35, wherein the UE has knowledge of: a position for each network entity of one or more network entities transmitting signals reflected from the one or more IRSs to the UE; and a position, an orientation, and a size of each of the one or more IRSs.

Clause 37: A method for wireless communication by a user equipment (UE), comprising: identifying first intelligent reflecting surface (IRS) reflection centers for one or more IRSs as a center of each of the one or more IRSs; measuring an initial impulse response from each of the one or more IRSs, to obtain an initial impulse response representation for each of the one or more IRSs; estimating a first position of the UE based on, at least: the first IRS reflection centers for the one or more IRSs and a peak point on the initial impulse response representation for each of the one or more IRSs; and estimating a second position of the UE in an iterative manner until a change in position of the UE based on the second position of the UE and a previously estimated position of the UE is less than a threshold, wherein estimating the second position of the UE in the iterative manner comprises: identifying second IRS reflection centers for the one or more IRSs using a previously estimated position of the UE and a focal point for each of the one or more IRSs; for each IRS of the one or more IRSs: computing an expected impulse response, using the previously estimated position of the UE, to obtain an expected impulse response representation, wherein the expected impulse response representation comprises a histogram of expected delays for a plurality of rays through different points over a surface area of the IRS; measuring a measured impulse response from the IRS using one or more transmissions from a network entity that are reflected to the UE using the IRS, to obtain a measured impulse response, wherein the measured impulse response representation comprises a histogram of measured delays for the plurality of rays through the different points over the surface area of the IRS; adjusting, by a delay adjustment, a delay of the expected impulse response representation to align in time with the measured impulse response representation; and determining a first impulse response for a first ray of the plurality of rays reflected from a first point of the different points over the surface area of the IRS; and estimating the second position of the UE based on, at least, the second IRS reflection centers for each of the one or more IRSs and the first impulse response for each of the one or more IRSs.

Clause 38: The method of Clause 37, wherein the focal point comprises a real focal point or a virtual focal point.

Clause 39: The method of any one of Clauses 37 or 38, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated positon of the UE and the focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: identifying an intersection point on a surface area of the IRS for a straight line passing through the UE at the previously estimated position and the focal point; and using the intersection point as the second IRS reflection center.

Clause 40: The method of any one of Clauses 37-39, wherein the UE estimates the first position and the second position of the UE using time difference of arrival (TDOA) measurements of different signals reflected from the one or more IRSs, the signals being transmitted by one or more network entities.

Clause 41: The method of any one of Clauses 37-40, wherein the UE has knowledge of: a position for each network entity of one or more network entities transmitting signals reflected from the one or more IRSs to the UE; and a position, an orientation, and a size of the one or more IRSs.

Clause 42: The method of any one of Clauses 37-41, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated positon of the UE and the focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: determining a first straight line passing through the UE at the previously estimated position and the focal point does not intersect a surface area of the IRS; manipulating the previously estimated position of the UE to be an adjusted position of the UE such that a second straight line passing through the UE at the adjusted position of the UE and the focal point does intersect the surface area of the IRS at an intersection point; and identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 43: The method of any one of Clauses 37-42, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated positon of the UE and the focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: determining a first straight line passing through the UE at the previously estimated position and the focal point does not intersect a surface area of the IRS; manipulating the first IRS reflection center to estimate an adjusted position of the UE such that a second straight line passing through the UE at the adjusted position of the UE and the focal point does intersect the surface area of the IRS at an intersection point; and identifying the intersection point on the surface area of the IRS; and using the intersection point as the second IRS reflection center.

Clause 44: The method of any one of Clauses 37-43, wherein identifying the second IRS reflection centers for the one or more IRSs using the previously estimated positon of the UE and the focal point for each of the one or more IRSs comprises, for each of the one or more IRSs: identifying an intersection point on the IRS for a straight line passing through the UE at the previously estimated position and the focal point; and calculating the second IRS reflection center as a weighted average of a position of the intersection point on the IRS and one or more previously estimated positions of the UE.

Clause 45: An apparatus, comprising: a memory comprising executable instructions; and one or more processors configured to execute the executable instructions and cause the apparatus to perform a method in accordance with any one of Clauses 1-44.

Clause 46: An apparatus, comprising means for performing a method in accordance with any one of Clauses 1-44.

Clause 47: A non-transitory computer-readable medium comprising executable instructions that, when executed by one or more processors of an apparatus, cause the apparatus to perform a method in accordance with any one of Clauses 1-44.

Clause 48: A computer program product embodied on a computer-readable storage medium comprising code for performing a method in accordance with any one of Clauses 1-44.

Additional Wireless Communication Network Considerations

The techniques and methods described herein may be used for various wireless communications networks (or wireless wide area network (WWAN)) and radio access technologies (RATs). While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G (e.g., 5G new radio (NR)) wireless technologies, aspects of the present disclosure may likewise be applicable to other communication systems and standards not explicitly mentioned herein.

5G wireless communication networks may support various advanced wireless communication services, such as enhanced mobile broadband (eMBB), millimeter wave (mmWave), machine type communications (MTC), and/or mission critical targeting ultra-reliable, low-latency communications (URLLC). These services, and others, may include latency and reliability requirements.

Returning toFIG.1, various aspects of the present disclosure may be performed within the example wireless communication network100.

In 3GPP, the term “cell” can refer to a coverage area of a NodeB and/or a narrowband subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and BS, next generation NodeB (gNB or gNodeB), access point (AP), distributed unit (DU), carrier, or transmission reception point may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area (e.g., a sports stadium) and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) and UEs for users in the home). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS, home BS, or a home NodeB.

BSs102configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC160through first backhaul links (e.g., an S1 interface). BSs102configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) may interface with 5GC190through second backhaul links184. BSs102may communicate directly or indirectly (e.g., through the EPC160or 5GC190) with each other over third backhaul links134(e.g., X2 interface). Third backhaul links134may generally be wired or wireless.

Small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP150. Small cell102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

Some base stations, such as BS180(e.g., gNB) may operate in a traditional sub-6 GHz spectrum, in millimeter wave (mmWave) frequencies, and/or near mmWave frequencies in communication with the UE104. When the BS180operates in mmWave or near mmWave frequencies, the BS180may be referred to as an mmWave base station.

The communication links120between BSs102and, for example, UEs104, may be through one or more carriers. For example, BSs102and UEs104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, and other MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).

Wireless communication network100further includes a Wi-Fi access point (AP)150in communication with Wi-Fi stations (STAs)152via communication links154in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs152/AP150may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

Certain UEs104may communicate with each other using device-to-device (D2D) communication link158. The D2D communication link158may use the DL/UL WWAN spectrum. The D2D communication link158may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ. WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, 4G (e.g., LTE), or 5G (e.g., NR), to name a few options.

EPC160may include a Mobility Management Entity (MME)162, other MMEs164, a Serving Gateway166, a Multimedia Broadcast Multicast Service (MBMS) Gateway168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway172. MME162may be in communication with a Home Subscriber Server (HSS)174. MME162is the control node that processes the signaling between the UEs104and the EPC160. Generally, MME162provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred through Serving Gateway166, which itself is connected to PDN Gateway172. PDN Gateway172provides UE IP address allocation as well as other functions. PDN Gateway172and the BM-SC170are connected to the IP Services176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services.

BM-SC170may provide functions for MBMS user service provisioning and delivery. BM-SC170may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. MBMS Gateway168may be used to distribute MBMS traffic to the BSs102belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

5GC190may include an Access and Mobility Management Function (AMF)192, other AMFs193, a Session Management Function (SMF)194, and a User Plane Function (UPF)195. AMF192may be in communication with a Unified Data Management (UDM)196.

AMF192is generally the control node that processes the signaling between UEs104and 5GC190. Generally, AMF192provides QoS flow and session management.

All user Internet protocol (IP) packets are transferred through UPF195, which is connected to the IP Services197, and which provides UE IP address allocation as well as other functions for 5GC190. IP Services197may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services.

Returning toFIG.2, various example components of BS102and UE104(e.g., the wireless communication network100ofFIG.1) are depicted, which may be used to implement aspects of the present disclosure.

At BS102, a transmit processor220may receive data from a data source212and control information from a controller/processor240. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), and others. The data may be for the physical downlink shared channel (PDSCH), in some examples.

A medium access control (MAC)-control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

Transmit processor220may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor220may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).

Transmit (TX) multiple-input multiple-output (MIMO) processor230may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers232a-232t. Each modulator in transceivers232a-232tmay process a respective output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers232a-232tmay be transmitted via the antennas234a-234t, respectively.

At UE104, antennas252a-252rmay receive the downlink signals from the BS102and may provide received signals to the demodulators (DEMODs) in transceivers254a-254r, respectively. Each demodulator in transceivers254a-254rmay condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM) to obtain received symbols.

MIMO detector256may obtain received symbols from all the demodulators in transceivers254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor258may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE104to a data sink260, and provide decoded control information to a controller/processor280.

On the uplink, at UE104, transmit processor264may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source262and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor280. Transmit processor264may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor264may be precoded by a TX MIMO processor266if applicable, further processed by the modulators in transceivers254a-254r(e.g., for SC-FDM), and transmitted to BS102.

At BS102, the uplink signals from UE104may be received by antennas234a-t, processed by the demodulators in transceivers232a-232t, detected by a MIMO detector236if applicable, and further processed by a receive processor238to obtain decoded data and control information sent by UE104. Receive processor238may provide the decoded data to a data sink239and the decoded control information to the controller/processor240.

Memories242and282may store data and program codes for BS102and UE104, respectively.

Scheduler244may schedule UEs for data transmission on the downlink and/or uplink.

5G may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. 5G may also support half-duplex operation using time division duplexing (TDD). OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones and bins. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may be dependent on the system bandwidth. The minimum resource allocation, called a resource block (RB), may be 12 consecutive subcarriers in some examples. The system bandwidth may also be partitioned into subbands. For example, a subband may cover multiple RBs. NR may support a base subcarrier spacing (SCS) of 15 KHz and other SCS may be defined with respect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, and others).

As above,FIGS.3A,3B,3C, and3Ddepict various example aspects of data structures for a wireless communication network, such as wireless communication network100ofFIG.1.

In various aspects, the 5G frame structure may be frequency division duplex (FDD), in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for either DL or UL. 5G frame structures may also be time division duplex (TDD), in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided byFIGS.3A and3C, the 5G frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL), where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL). While subframes 3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI), or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI). Note that the description below applies also to a 5G frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. In some examples, each slot may include 7 or 14 symbols, depending on the slot configuration.

For example, for slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission).

The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2μ×15 kHz, where u is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing.FIGS.3A,3B,3C, and3Dprovide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

As illustrated inFIG.3A, some of the REs carry reference (pilot) signals (RS) for a UE (e.g., UE104ofFIGS.1and2). The RS may include demodulation RS (DM-RS) (indicated as Rx for one particular configuration, where 100× is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS), beam refinement RS (BRRS), and phase tracking RS (PT-RS).

FIG.3Billustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g.,104ofFIGS.1and2) to determine subframe/symbol timing and a physical layer identity.

A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

As illustrated inFIG.3C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS). The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG.3Dillustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

ADDITIONAL CONSIDERATIONS

The preceding description provides examples of intelligent reflecting surface (IRS) aided user equipment (UE) positioning. The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

The techniques described herein may be used for various wireless communication technologies, such as 5G (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), cdma2000, and others. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement a radio technology such as NR (e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, and others. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). NR is an emerging wireless communications technology under development.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a DSP, an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC), or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the physical (PHY) layer. In the case of a user equipment (as in the example UE104ofFIG.1), a user interface (e.g., keypad, display, mouse, joystick, touchscreen, biometric sensor, proximity sensor, light emitting element, and others) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.