User equipment radio frequency calibration requirements

Abstract

Various aspects of the present disclosure relate to user equipment (UE) radio frequency (RF) calibration requirements. An apparatus, such as a UE, receives a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, where the first signal and the second signal having different receive gains and different receive phases. The UE reports an estimate of a receive phase offset between the first signal and the second signal. A baseband processor of a UE receives the first signal via a first antenna connector, and receives the second signal via a second antenna connector. The baseband processor compares a receive phase of the first signal to a receive phase of the second signal to determine the estimate of a receive phase offset between the first and second signals. The baseband processor reports the estimate of the receive phase offset between the first and second signals.

Description

Lenovo Ref. No. SMM920230181-WO-PCT 1 USER EQUIPMENT RADIO FREQUENCY CALIBRATION REQUIREMENTS RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application Serial No. 63 / 549,258 filed February 02, 2024 entitled “User Equipment Radio Frequency Calibration Requirements,” the disclosure of which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to wireless communications, and more specifically to calibration requirements for user equipment (UE). BACKGROUND

[0003] A wireless communications system may include one or multiple network communication devices, which may be otherwise known as network equipment (NE), supporting wireless communications for one or multiple user communication devices, which may be otherwise known as UE, or other suitable terminology. The wireless communications system may support wireless communications with one or multiple user communication devices by utilizing resources of the wireless communication system (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers, or the like)). Additionally, the wireless communications system may support wireless communications across various radio access technologies including third generation (3G) radio access technology, fourth generation (4G) radio access technology, fifth generation (5G) radio access technology, among other suitable radio access technologies beyond 5G (e.g., sixth generation (6G)).

[0004] A UE in a wireless communications system may use channel reciprocity to maximize throughput or capacity on a communication channel without feedback from a base station. Typically, a UE may receive reference symbols from the base station, and based on the reference symbols, determine how best to beamform, use a precoding matrix, etc. For time division duplex (TDD), using the same frequencies to transmit and receive, channel reciprocity may be assumed to apply, in which case the transmission links would match and a channel estimate of uplink at the UE Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 2 transmitter can be used for downlink based on link adaptation. However, due to the circuitry in the transmit path and the receive path, channel reciprocity for a UE transceiver may not be accurate. SUMMARY

[0005] An article “a” before an element is unrestricted and understood to refer to “at least one” of those elements or “one or more” of those elements. The terms “a,” “at least one,” “one or more,” and “at least one of one or more” may be interchangeable. As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” or “one or both of”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on”. Further, as used herein, including in the claims, a “set” may include one or more elements.

[0006] A UE for wireless communication is described. The UE may be configured to, capable of, or operable to perform one or more operations as described herein. For example, the UE may be configured to, capable of, or operable to receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal.

[0007] A processor (e.g., a standalone processor chipset, or a component of a UE) for wireless communication is described. The processor may be configured to, capable of, or operable to perform one or more operations as described herein. For example, the processor may be configured to, capable of, or operable to receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 3

[0008] A method performed or performable by a UE for wireless communication is described. The method may include receiving a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and reporting an estimate of a receive phase offset between the first signal and the second signal.

[0009] In some implementations of the UE, the processor, and the method described herein, the first signal and the second signal are orthogonal frequency division multiplexing (OFDM) modulated, and the second signal is a phase shifted and scaled version of the first signal. In some implementations of the UE, the processor, and the method described herein, an absolute error of the estimate of the receive phase offset is less than an accuracy threshold. In some implementations of the UE, the processor, and the method described herein, the absolute error of the estimate of the receive phase offset is an indication of a receiver calibration requirement.

[0010] In some implementations of the UE, the processor, and the method described herein, the UE, the processor, and the method may be configured to, capable of, or operable to report an additional estimate of a receive gain offset between the first signal and the second signal. In some implementations of the UE, the processor, and the method described herein, an absolute error of the estimate of the receive gain offset is less than an accuracy threshold. In some implementations of the UE, the processor, and the method described herein, the absolute error of the estimate of the receive gain offset is an indication of a receiver calibration requirement.

[0011] In some implementations of the UE, the processor, and the method described herein, the UE, the processor, and the method may be configured to, capable of, or operable to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit phases. In some implementations of the UE, the processor, and the method described herein, an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. In some implementations of the UE, the processor, and the method described herein, the absolute value difference between the transmit phase offset and the conjugate of the receive phase offset is an indication of receiver and transmitter calibration requirements.

[0012] In some implementations of the UE, the processor, and the method described herein, the UE, the processor, and the method may be configured to, capable of, or operable to transmit signals Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 4 via the two or more antenna connectors, the transmitted signals having different transmit gains. In some implementations of the UE, the processor, and the method described herein, an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. In some implementations of the UE, the processor, and the method described herein, the absolute value difference between the transmit gain offset and the receive gain offset is an indication of a receiver calibration requirement.

[0013] In some implementations of the UE, the processor, and the method described herein, the UE, the processor, and the method may be configured to, capable of, or operable to receive the first signal and the second signal from a test equipment that simulates a network equipment (NE).

[0014] A baseband processor for wireless communication is described. The baseband processor may be configured to, capable of, or operable to perform one or more operations as described herein. For example, the baseband processor may be configured to, capable of, or operable to receive a first signal via a first antenna connector of a multi-antenna receiver; receive a second signal via a second antenna connector of the multi-antenna receiver; compare a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal; and report the estimate of the receive phase offset between the first signal and the second signal.

[0015] A method performed or performable by a baseband processor for wireless communication is described. The method may include receiving a first signal via a first antenna connector of a multi-antenna receiver; receiving a second signal via a second antenna connector of the multi-antenna receiver; comparing a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal; and reporting the estimate of the receive phase offset between the first signal and the second signal.

[0016] In some implementations of the baseband processor and the method described herein, the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. In some implementations of the baseband processor and the method described herein, an absolute error of the estimate of the receive phase offset is less than an accuracy threshold. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 5

[0017] In some implementations of the baseband processor and the method described herein, the baseband processor and the method may be configured to, capable of, or operable to compare a receive gain of the first signal to a receive gain of the second signal to determine an additional estimate of a receive gain offset between the first signal and the second signal; and report the additional estimate of the receive gain offset between the first signal and the second signal. In some implementations of the baseband processor and the method described herein, an absolute error of the estimate of the receive gain offset is less than an accuracy threshold.

[0018] In some implementations of the baseband processor and the method described herein, the baseband processor and the method may be configured to, capable of, or operable to determine whether an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold.

[0019] In some implementations of the baseband processor and the method described herein, the baseband processor and the method may be configured to, capable of, or operable to determine whether an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 illustrates an example of a wireless communications system in accordance with aspects of the present disclosure.

[0021] Figure 2 illustrates an example of a baseband processor and antenna system, in accordance with aspects of the present disclosure.

[0022] Figure 3 illustrates an example of an antenna element system, in accordance with aspects of the present disclosure.

[0023] Figure 4 illustrates an example of a baseband processor and antenna system, in accordance with aspects of the present disclosure.

[0024] Figure 5 illustrates an example of a UE in accordance with aspects of the present disclosure. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 6

[0025] Figure 6 illustrates an example of a processor in accordance with aspects of the present disclosure.

[0026] Figure 7 illustrates an example of a test equipment in accordance with aspects of the present disclosure.

[0027] Figure 8 illustrates a flowchart of a method performed by a UE in accordance with aspects of the present disclosure.

[0028] Figure 9 illustrates a flowchart of a method performed by a baseband processor of a UE in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0029] A wireless communications system may include one or multiple communication devices, such as UEs, which support wireless communications. The wireless communications system may support wireless communications by a UE that is calibrated. A communication device, such as a UE that is calibrated, can support features such as beamforming using channel reciprocity for TDD channels and receive communication signals, such as for an estimation of angle of arrival (AoA). Accordingly, the requirements for calibration should be defined and tested to verify that a communication device properly performs, otherwise the user experience and the system performance may be significantly degraded, or inoperable. For some applications, calibration verification of only the receiver of a UE may be needed, such as when determining the AoA of a received signal. Alternatively, calibration verification of both the transmitter and receiver may be needed so that the UE can maximize coverage and throughput using channel reciprocity.

[0030] A UE in a wireless communications system may use channel reciprocity to maximize throughput or capacity on a communication channel without feedback from a base station. Typically, for TDD, channel reciprocity may be assumed to apply, in which case the transmission links for receive and transmit would match, and a channel estimate of downlink at a UE receiver can be used for uplink transmission. However, due to the circuitry in the transmit path and the receive path, channel reciprocity for a UE transceiver may not be accurate. The signal paths between the individual antennas of a device, such as a UE, and a baseband processor of the device include switches, filters, amplifiers, matching circuits, and signal traces of unequal lengths with unequal losses. As a result, the phases and gains of the signal paths from the antennas to the Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 7 baseband can be different for each antenna. Furthermore, the phases and gains between the baseband processor and the antennas of a device can be different for the transmit signal paths and the receive signal paths.

[0031] Typically for TDD channels, calibration of the transmit and receive paths allows a UE to determine the uplink channel as the transpose of the downlink channel. For 3GPP Frequency Range 2 (FR2), channel reciprocity is exploited using beam reciprocity in which the best downlink beam is assumed to be the best uplink beam. However, the use of beam reciprocity requires that the UE signal paths are calibrated. Typically, hybrid or analog beamforming is used in which an equal phase progression is applied across the antennas of the device with the assumption that the antennas are equally spaced. However, the antennas of 3GPP Frequency Range 1 (FR1) devices may not be evenly spaced, but rather, are positioned at different locations around a UE device. In implementations, there may not be a regular spacing or pattern of the antenna elements of a device, and the antenna elements may not be identical. Therefore, device calibration verification cannot assume the use of hybrid or analog beamforming.

[0032] Aspects of this disclosure are directed to calibration verification of a communication device, such as a UE, in a wireless communications system. In implementations, the described techniques support calibration verification of a UE receiver. In other implementations, the described techniques support calibration verification of both the transmitter and receiver of a UE. By utilizing the described techniques, the calibration of a UE can be verified for operation in a wireless communications system. Reference is made herein to communicating data or information, such as signaling communications that are transmitted or received between devices. It is to be appreciated that other terms may be used interchangeably with communicating, such as signaling, transmitting, receiving, outputting, forwarding, retrieving, obtaining, and so forth.

[0033] Aspects of the present disclosure are described in the context of a wireless communications system.

[0034] Figure 1 illustrates an example of a wireless communications system 100 in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more NE 102, one or more UE 104, and a core network (CN) 106. The wireless communications system 100 may support various radio access technologies. In some implementations, the wireless Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 8 communications system 100 may be a 4G network, such as an LTE network or an LTE-Advanced (LTE-A) network. In some other implementations, the wireless communications system 100 may be a NR network, such as a 5G network, a 5G-Advanced (5G-A) network, or a 5G ultrawideband (5G-UWB) network. In other implementations, the wireless communications system 100 may be a combination of a 4G network and a 5G network, or other suitable radio access technology including Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20. The wireless communications system 100 may support radio access technologies beyond 5G, for example, 6G. Additionally, the wireless communications system 100 may support technologies, such as time division multiple access (TDMA), frequency division multiple access (FDMA), or code division multiple access (CDMA), etc.

[0035] The one or more NE 102 may be dispersed throughout a geographic region to form the wireless communications system 100. One or more of the NE 102 described herein may be or include or may be referred to as a network node, a base station, a network element, a network function, a network entity, a radio access network (RAN), a NodeB, an eNodeB (eNB), a next- generation NodeB (gNB), or other suitable terminology. An NE 102 and a UE 104 may communicate via a communication link, which may be a wireless or wired connection. For example, an NE 102 and a UE 104 may perform wireless communication (e.g., receive signaling, transmit signaling) over a Uu interface.

[0036] An NE 102 may provide a geographic coverage area for which the NE 102 may support services for one or more UEs 104 within the geographic coverage area. For example, an NE 102 and a UE 104 may support wireless communication of signals related to services (e.g., voice, video, packet data, messaging, broadcast, etc.) according to one or multiple radio access technologies. In some implementations, an NE 102 may be moveable, for example, a satellite associated with a non-terrestrial network (NTN). In some implementations, different geographic coverage areas associated with the same or different radio access technologies may overlap, but the different geographic coverage areas may be associated with different NE 102.

[0037] The one or more UEs 104 may be dispersed throughout a geographic region of the wireless communications system 100. A UE 104 may include or may be referred to as a remote unit, a mobile device, a wireless device, a remote device, a subscriber device, a transmitter device, a receiver device, or some other suitable terminology. In some implementations, the UE 104 may be Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 9 referred to as a unit, a station, a terminal, or a client, among other examples. Additionally, or alternatively, the UE 104 may be referred to as an Internet-of-Things (IoT) device, an Internet-of- Everything (IoE) device, or machine-type communication (MTC) device, among other examples.

[0038] A UE 104 may be able to support wireless communication directly with other UEs 104 over a communication link. For example, a UE 104 may support wireless communication directly with another UE 104 over a device-to-device (D2D) communication link. In some implementations, such as vehicle-to-vehicle (V2V) deployments, vehicle-to-everything (V2X) deployments, or cellular-V2X deployments, the communication link may be referred to as a sidelink. For example, a UE 104 may support wireless communication directly with another UE 104 over a PC5 interface.

[0039] An NE 102 may support communications with the CN 106, or with another NE 102, or both. For example, an NE 102 may interface with other NE 102 or the CN 106 through one or more backhaul links (e.g., S1, N2, N6, or other network interface). In some implementations, the NE 102 may communicate with each other directly. In some other implementations, the NE 102 may communicate with each other indirectly (e.g., via the CN 106). In some implementations, one or more NE 102 may include subcomponents, such as an access network entity, which may be an example of an access node controller (ANC). An ANC may communicate with the one or more UEs 104 through one or more other access network transmission entities, which may be referred to as a radio heads, smart radio heads, or transmission-reception points (TRPs).

[0040] The CN 106 may support user authentication, access authorization, tracking, connectivity, and other access, routing, or mobility functions. The CN 106 may be an evolved packet core (EPC), or a 5G core (5GC), which may include a control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management functions (AMF)) and a user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)). In some implementations, the control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management (e.g., data bearers, signal bearers, etc.) for the one or more UEs 104 served by the one or more NE 102 associated with the CN 106. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 10

[0041] The CN 106 may communicate with a packet data network over one or more backhaul links (e.g., via an S1, N2, N6, or other network interface). The packet data network may include an application server. In some implementations, one or more UEs 104 may communicate with the application server. A UE 104 may establish a session (e.g., a protocol data unit (PDU) session, or the like) with the CN 106 via an NE 102. The CN 106 may route traffic (e.g., control information, data, and the like) between the UE 104 and the application server using the established session (e.g., the established PDU session). The PDU session may be an example of a logical connection between the UE 104 and the CN 106 (e.g., one or more network functions of the CN 106).

[0042] In the wireless communications system 100, the NEs 102 and the UEs 104 may use resources of the wireless communications system 100 (e.g., time resources (e.g., symbols, slots, subframes, frames, or the like) or frequency resources (e.g., subcarriers, carriers)) to perform various operations (e.g., wireless communications). In some implementations, the NEs 102 and the UEs 104 may support different resource structures. For example, the NEs 102 and the UEs 104 may support different frame structures. In some implementations, such as in 4G, the NEs 102 and the UEs 104 may support a single frame structure. In some other implementations, such as in 5G and among other suitable radio access technologies, the NEs 102 and the UEs 104 may support various frame structures (i.e., multiple frame structures). The NEs 102 and the UEs 104 may support various frame structures based on one or more numerologies.

[0043] One or more numerologies may be supported in the wireless communications system 100, and a numerology may include a subcarrier spacing and a cyclic prefix. A first numerology (e.g., ^=0) may be associated with a first subcarrier spacing (e.g., 15 kHz) and a normal cyclic prefix. In some implementations, the first numerology (e.g., ^=0) associated with the first subcarrier spacing (e.g., 15 kHz) may utilize one slot per subframe. A second numerology (e.g., ^=1) may be associated with a second subcarrier spacing (e.g., 30 kHz) and a normal cyclic prefix. A third numerology (e.g., ^=2) may be associated with a third subcarrier spacing (e.g., 60 kHz) and a normal cyclic prefix or an extended cyclic prefix. A fourth numerology (e.g., ^=3) may be associated with a fourth subcarrier spacing (e.g., 120 kHz) and a normal cyclic prefix. A fifth numerology (e.g., ^=4) may be associated with a fifth subcarrier spacing (e.g., 240 kHz) and a normal cyclic prefix. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 11

[0044] A time interval of a resource (e.g., a communication resource) may be organized according to frames (also referred to as radio frames). Each frame may have a duration, for example, a 10 millisecond (ms) duration. In some implementations, each frame may include multiple subframes. For example, each frame may include 10 subframes, and each subframe may have a duration, for example, a 1 ms duration. In some implementations, each frame may have the same duration. In some implementations, each subframe of a frame may have the same duration.

[0045] Additionally or alternatively, a time interval of a resource (e.g., a communication resource) may be organized according to slots. For example, a subframe may include a number (e.g., quantity) of slots. The number of slots in each subframe may also depend on the one or more numerologies supported in the wireless communications system 100. For instance, the first, second, third, fourth, and fifth numerologies (i.e., ^=0, ^=1, ^=2, ^=3, ^=4) associated with respective subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz may utilize a single slot per subframe, two slots per subframe, four slots per subframe, eight slots per subframe, and 16 slots per subframe, respectively. Each slot may include a number (e.g., quantity) of symbols (e.g., OFDM symbols). In some implementations, the number (e.g., quantity) of slots for a subframe may depend on a numerology. For a normal cyclic prefix, a slot may include 14 symbols. For an extended cyclic prefix (e.g., applicable for 60 kHz subcarrier spacing), a slot may include 12 symbols. The relationship between the number of symbols per slot, the number of slots per subframe, and the number of slots per frame for a normal cyclic prefix and an extended cyclic prefix may depend on a numerology. It should be understood that reference to a first numerology (e.g., ^=0) associated with a first subcarrier spacing (e.g., 15 kHz) may be used interchangeably between subframes and slots.

[0046] In the wireless communications system 100, an electromagnetic (EM) spectrum may be split, based on frequency or wavelength, into various classes, frequency bands, frequency channels, etc. By way of example, the wireless communications system 100 may support one or multiple operating frequency bands, such as frequency range designations FR1 (410 MHz – 7.125 GHz), FR2 (24.25 GHz – 52.6 GHz), FR3 (7.125 GHz – 24.25 GHz), FR4 (52.6 GHz – 114.25 GHz), FR4a or FR4-1 (52.6 GHz – 71 GHz), and FR5 (114.25 GHz – 300 GHz). In some implementations, the NEs 102 and the UEs 104 may perform wireless communications over one or more of the operating frequency bands. In some implementations, FR1 may be used by the NEs 102 and the UEs 104, among other equipment or devices for cellular communications traffic (e.g., Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 12 control information, data). In some implementations, FR2 may be used by the NEs 102 and the UEs 104, among other equipment or devices for short-range, high data rate capabilities.

[0047] FR1 may be associated with one or multiple numerologies (e.g., at least three numerologies). For example, FR1 may be associated with a first numerology (e.g., ^=0), which includes 15 kHz subcarrier spacing; a second numerology (e.g., ^=1), which includes 30 kHz subcarrier spacing; and a third numerology (e.g., ^=2), which includes 60 kHz subcarrier spacing. FR2 may be associated with one or multiple numerologies (e.g., at least 2 numerologies). For example, FR2 may be associated with a third numerology (e.g., ^=2), which includes 60 kHz subcarrier spacing; and a fourth numerology (e.g., ^=3), which includes 120 kHz subcarrier spacing.

[0048] According to implementations, a UE 104 is operable to implement various aspects of the techniques described with reference to the present disclosure. For example, a UE 104 receives a first signal and a second signal from a test equipment that simulates an NE 102. The UE 104 receives the first and second signals at two or more antenna connectors of a multi-antenna receiver of the UE. The first signal and the second signal have different receive gains and different receive phases, where the first and second signals are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. The UE 104 can determine and report an estimate of a receive phase offset between the first signal and the second signal, where an absolute error of the estimate of the receive phase offset is less than an accuracy threshold, and the absolute error of the estimate of the receive phase offset is an indication of a receiver calibration requirement. The UE 104 can also determine and report an additional estimate of a receive gain offset between the first signal and the second signal, where an absolute error of the estimate of the receive gain offset is less than an accuracy threshold, and the absolute error of the estimate of the receive gain offset is an indication of a receiver calibration requirement.

[0049] Additionally, the UE 104 can transmit signals via the two or more antenna connectors, where the transmitted signals have different transmit phases. An absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold, and the absolute value difference between the transmit phase offset and the conjugate of the receive phase offset is an indication of receiver and transmitter calibration requirements. The UE 104 can also transmit signals via the two or more antenna connectors, where the transmitted signals have Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 13 different transmit gains. An absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold, and the absolute value difference between the transmit gain offset and the receive gain offset is an indication of a receiver calibration requirement.

[0050] With reference to channel reciprocity and TDD, both uplink and downlink transmissions share the same frequency band, but not at the same time. The uplink and downlink transmissions are divided into specific time slots. Typically, reference symbols can be used by a UE to demodulate a downlink signal to determine the downlink channel, and can also be used to estimate the uplink channel for a calibrated transmitter and receiver of the device. In order to use channel reciprocity for TDD channels, a UE must be calibrated from the antennas of the device to the baseband processor of the device for both the transmit and receive signal paths.

[0051] Figure 2 illustrates an example of a baseband processor and antenna system 200, in accordance with aspects of the present disclosure. A UE can include the baseband processor 202 and an array of antennas 204. For TDD channels, calibration of the receive signal paths (a) 206 and the transmit signal paths (b) 208 provides for a UE to determine the uplink channel as the transpose of the downlink channel. In the described techniques, M will denote the number of base station (e.g., gNB) antennas and N will denote the number of antennas 204. Further, for the channel from the base station to the UE, ^ denotes the M x N channel, where the i,j-th element denotes the propagation channel from i-th gNB antenna to the j-th UE antenna. For a TDD channel, reciprocity holds so that the channel from the UE antennas to the base station antennas is given by the transpose ^^of the downlink channel.

[0052] The signal paths (i.e., the receive signal paths (a) 206 and the transmit signal paths (b) 208) between the individual antennas 204 and the baseband processor 202 include switches, filters, amplifiers, matching circuits, and signal traces of unequal lengths with unequal losses. As a result, the phases and gains of the signal paths from the antennas 204 to the baseband processor 202 can be different for each antenna. Furthermore, the phases and gains between the baseband processor 202 and the antennas 204 (e.g., of a UE device) can be different for the transmit signal paths (b) 208 and the receive signal paths (a) 206, where, for example, a1206 and b1208 are not necessarily equal, and the gains and phases are unknown. In this example, a receive signal (y) 210 is received at an antenna 204, and the signal (^^) (“y-prime”) 212 is an input to the baseband processor 202 after down conversion, filtering, and routing in the receive signal path. For example, in between receive Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 14 signal (y1) 210 and (^^^) 212, there is a gain (a1) (e.g., a real value greater than zero) and a phase between zero and 2^ that changes the signal between the output of the antenna 204 and the input to the baseband processor 202.

[0053] In Figure 2, the gain and phase of the receive signal path from the i-th antenna 204 to thebaseband receiver is given by ^^^^^^ at 206, where ^^ is real-valued with ^^ > 0, and ^^ is real-valued in the interval 0 ≤ ^^ < 2^. If the M x 1 vector ^ denotes the signal transmitted by a basestation (e.g., gNB), then N x 1 vector ^ signal received by the UE is given by equation(1):^= ^^^.

[0054] In this example, ^ denotes the diagonal matrix of complex gains between the antennas 204 and a baseband receiver so that by equation(2): ^= ^^^^^^ ^^^^ ^ , ^ ^^^! , … , ^ ^^#^ $%and ^^denotes the signalby equation(3): ^^ = ^ ^'^ + )*where the N x 1 complex vector )^and is assumed to be a complex Gaussian random vector with covariance given by +^,#-#. By transmitting reference symbols from each of the M antennas (e.g., at the base station, gNB) using different resources elements, the UE can measure the product of the channel and the receiver impairments given by ^ ^^. However, neither the channel ^^nor the impairment matrix ^ can be determined separately from the measurement of the product ^ ^^. The baseband processor 202 sees the channel ^^multiplied by the diagonal matrix ^, which in general is unknown, and additive noise. Typically, the base station transmits reference signals and the UE can measure the product of ^ ^^, but cannot measure ^ and ^^individually.

[0055] A transmit signal (x) 214 is the output of the baseband processor 202, and is the input signal (.^) (“x-prime”) 216 to an antenna 204. The transmit signal (x) 214 is seen as a product of the signal and the diagonal matrix B through the channel H. As shown and described in this example, the gain and phase of the transmit path from the baseband transmitter to the i-th antenna is given by / ^^^0^, where / ^ is real-valued with / ^ > 0, and 1^ is real-valued and in the interval 0 ≤ 1^ < 2^.Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 15 If the M x 1 vector . denotes a baseband transmit signal, then the transmit signal .^216 at an antenna 204 is given by equation(4): .^ = 2 . ,where 2 is the diagonal matrix in equation(5): 2= ^^^^^ / ^^^0^ , / ^^0! , … , / ^0#^ $% .

[0056] In this example, base station (e.g., gNB) asgiven by equation(6): 3= ^ .^ + )4 = ^ 2 . + )4

[0057] where the M x 1 complex vector ) represents receiver noise and is assumed to be a complex Gaussian random vector with covariance given by + ,5-5. By sending reference symbols from each of the N UE antennas 204 using different resources elements, the UE can measure the product of the channel and the receiver impairments given by ^ 2. However, neither the channel ^ nor the impairment matrix 2 can be determined separately from the measurement of the product ^ 2.

[0058] A UE in a wireless communications system may use channel reciprocity to maximize throughput or capacity on the uplink channel if the channel matrix ^ is known by the UE. Specifically, it is the transpose of ^ which applies when the UE transmits to the base station. If the UE receiver and transmitter are calibrated, channel reciprocity can be used to optimize an uplink transmission based on the channel that is measured on the downlink. Typically, the maximum capacity of the channel, the Shannon capacity, can be achieved by using water-pouring power allocation with the right singular vectors of the channel matrix ^. These right singular vectors are orthonormal and can be considered to be precoding vectors, each of which is used to transmit a stream of data symbols.

[0059] A problem with maximizing uplink coverage is similar to that of maximizing capacity, except that when maximizing uplink coverage (e.g., to maximize the signal range), the signal-to- noise ratio (SNR) can be assumed to be sufficiently low so that water-pouring power allocation only results in the use of the right singular vector corresponding to the largest singular value. In the Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 16 special case in which a gNB has a single transmit antenna, the channel matrix ^ reduces to a 1 x N vector 6 and the optimal precoder (the only singular vector) is given by 67.

[0060] Figure 3 illustrates an example of an antenna element system 300, in accordance with aspects of the present disclosure. A UE can include two antenna elements 302, and in this example, a received signal 304 arrives with an angle 89306 relative to perpendicular of a distance (d) 308between the two antenna elements 302, and there is a phase progression ^ sin 89 310. While channelreciprocity technically only applies to TDD bands, channel characteristics such as AoA information, should be independent of frequency even though the phase progression seen across the receiveantennas (e.g., the two antenna elements 302) depends on frequency. The phase progression ^ sin 89310 of the received signal 304, which is arriving from the same direction, across the two antenna elements 302 can be mapped to the angle of arrival (e.g., angle 89306) relative to the perpendicular line connecting the two antenna elements so long as the distance (d) 308 between the two antenna elements 302 is known and is less than one-half of the wavelength of the received signal 304. For the special case above in which the gNB has a single transmit antenna, the 1 x 2 vector 6 to measure the received channel can be represented as equation(7): 6= =ℎ^, ℎ ? = =|ℎ^| ^AB=C ^D^=ℎ^?? , |ℎ | ^AB=C ^D^=ℎ ???= exp=C arg=ℎ^?? ^|ℎ^|, |ℎ | exp^C=arg=ℎ ? − arg=ℎ^??%%

[0061] For a TDD system, in order to transmit a signal back in the direction from which the signal was received, the transmit phase vector should be the conjugate of the received phase vector. Additionally, to maximize the SNR at the receiver subject to a transmit power constraint, the relative magnitudes of the transmit weights should be the same as for the receive channel, so that the optimal transmit weights are given by equation(8): 1= ^AB=C P? ^AB^C=^D^=ℎ^? − ^D^=ℎ ??%%where the multiplicative phase term exp=C P? can be chosen arbitrarily. This is the weighting vector used to transmit if the equation(7) for vector 6 above is the receive vector. This would maximize the SNR or maximize the range for a single rank transmission. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 17

[0062] For a frequency division duplex (FDD) channel, the transmitter frequency is different than the receive frequency. In this example, Q^and Q denote the wavelength of the receiver and thetransmitter frequencies, respectively. The phase difference arg=ℎ ? − arg=ℎ^? (in radians) betweenthe phases of the signals 304 received on first and second antenna elements 302 depends on the angle of arrival 306 of the received signal relative to the line perpendicular between the two antennas so that by equation(9): 2^ ^ R^S 8^D^=ℎ ? − ^D^=ℎ^? = 9Q .^

[0063] Thus, the phasewavelength is equation(10): 2^ ^ R^S 89= =^D^=ℎ ? − ^D^=ℎ^??Q^

[0064] Thus, for angiven by equation(11): 1Q^ =^D^=ℎ ? − ^D^=ℎ ??L = ^AB= ? | | | | ^M C P T ℎ^ , ℎ ^AB TC UU .

[0065] and the receiver is needed in order for a UE to maximize coverage and throughput using channel reciprocity (e.g., to maximize capacity). The UE must obtain or determine the diagonal impairment matrix ^ so that it can extract the channel ^ from the measurement ^ ^^. Similarly, the UE must obtain or determine the impairment matrix 2 so that it can pre-compensate the transmit precoder for this impairment by multiplying by the inverse of 2.

[0066] For some applications, calibration verification of only the receiver of a UE may be needed (e.g., know the matrix ^), such as when determining the AoA of a received signal. In this case, the UE needs to have the receiver impairment matrix ^ in order to estimate the AoA of the received signal. Similarly, for other applications, calibration verification of only the transmitter of a UE may be needed.

[0067] In aspects of this disclosure, consideration is given as to whether these requirements should be specified as radiated or conductive (e.g., radiated being measuring the far-field antenna Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 18 patterns of a UE). For reasons including test time and cost, almost all 3GPP RAN4, 3GPP RAN5 and Global Certification Forum (GCF) tests are conductive rather than radiated for Frequency Range 1 (FR1), using connections to antenna connection points. However, there are also radiated tests defined to measure total radiated power (TRP) and total radiated sensitivity (TRS). Table(1) below indicates definitions of frequency ranges: Frequency range Corresponding frequency range designation FR1 410 MHz – 7125 MHz FR2 FR2-1 24250 MHz – 52600 MHz FR2-2 52600 MHz – 71000 MHz

[0068] For Frequency Range 2 (FR2), there are no antenna connection points which can be used for conductive testing, and so all FR2 testing is radiated. For FR2, analog beam forming is used to select the best beam, as described above, such as based on the phase progression across an array of device antennas, assuming an equally-spaced array.

[0069] Figure 4 illustrates an example of a baseband processor and antenna system 400, in accordance with aspects of the present disclosure. A UE can include the baseband processor 402 and an array of antennas 404, each having a respective antenna connector 406. Due to the time, cost, and complexity of radiated testing, the conductive testing requirements for FR1 devices using the antenna connectors 406 are considered in this example. It should be noted that there can be some further phase and gain impairments between the antenna connectors 406 and the antennas 404. However, these impairments can be minimized with proper impedance matching. Alternatively, the UE can characterize the impairments between the antenna connectors 406 and the antennas 404 separately. In this latter case, the UE would not account for the impairments between the antenna connectors 406 and the antennas 404 for conductive testing, but would account for these impairments during radiated testing.

[0070] For a UE in a wireless communications system to use channel reciprocity and maximize uplink performance for TDD channels, both the receiver impairment matrix ^ and the transmitter impairment matrix 2 must be known by the UE. However, the simpler case of phase-only calibration is first considered, because for single layer transmission, most of the performance Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 19 benefit is obtained by transmitting the signal in the direction of the base station. For this purpose and in this example, ^Vand 2Vdenote the phase only portion of the receiver impairment matrix ^ and the transmitter impairment matrix 2, respectively so that in equation(12): ^^^W = ^^^^^^ ^ , ^^^! , … , ^^^$%

[0071] and in equation(13):2W = ^^^^^^^0^ , ^^0! , … , ^^0$% .

[0072] For the receiverof the receiver, such as for AoA), the conducted phase calibration can be characterized as the following requirement: If test signals R=X?^^Yand R=X?^^=YZ[?are simultaneously applied to antenna connectors ^ and C where P and \ are report an estimate \] of the phase difference \ within an accuracyof ^ radians, which is as in equation(13): |_ − _̀| ≤ a .

[0073] The test signal R=X? can be an OFDM modulated signal with a number of resource blocks (RBs) less than or equal to the maximum number of RBs for the carrier bandwidth.

[0074] For the receiver, conducted gain and phase calibration can be characterized as the following requirement: If test signals b R=X?^^Yand b c R=X?^^=YZ[?are simultaneously applied to antenna connectors ^ and C where P,c are real-valued and b and c are real-valued withb, c > 0, the UE must report estimates \] and cd of the phase difference \ in radians and theamplitude difference c in dB with an accuracy of ^ and e, which is as in equation(14): |_ − _̀| ≤ a

[0075] and as in equation(15): fg − ghf ≤ i .

[0076] The test signal R=X? can be an signal with a number of RBs less than or equal to the maximum number of RBs for the carrier bandwidth. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 20

[0077] For the combination of the receiver and the transmitter, conducted phase calibration can be characterized as the following requirement: If the same test signals R=X?^^Yand R=X?^^=Yj[?are simultaneously applied to antenna connectors ^ and C, where P and \ =transmits signals k=X?^^Yand k=X?^^ YZ[̀?, where in (16):|_ − _̀| ≤ a .

[0078] The test signal R=X? can be an OFDM modulated signal with a number of RBs less than or equal to the maximum number of RBs for the carrier bandwidth. The transmitted signal k=X? can be a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) signal or an OFDM signal.

[0079] For the combination of the receiver and the transmitter, conducted gain and phase calibration can be characterized as the following requirement: If test signals b R=X?^^Yand b c R=X?^^=Yj[?are simultaneously applied to antenna connectors ^ and C,and c areb and c are real-valued with b, c > 0, the UE must transmit signals k=X?^^Y andcdk=X?^^=YZ[̀?, where in equation(17): |_ − _̀| ≤ a

[0080] and in equation(18): |l − l̀| ≤ i .

[0081] The test signal R=X?can be an OFDM modulated signal with a number of RBs less than or equal to the maximum number of RBs for the carrier bandwidth. The transmitted signal k=X?can be a DFT-s-OFDM signal or an OFDM signal. The signal s(t) (e.g., a same signal) is provided to a first antenna connector, and the signal is then phase shifted and scaled, and provided to a second antenna connector.

[0082] Figure 5 illustrates an example of a UE 500 in accordance with aspects of the present disclosure. The UE 500 may include a processor 502, a memory 504, a controller 506, a transceiver 508, and a baseband processor 514. The processor 502, the memory 504, the controller 506, the transceiver 508, or the baseband processor 514, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 21 disclosure as described herein. These components may be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces.

[0083] The processor 502, the memory 504, the controller 506, the transceiver 508, or the baseband processor 514, or various combinations or components thereof may be implemented in hardware (e.g., circuitry). The hardware may include a processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure.

[0084] The processor 502 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination thereof). In some implementations, the processor 502 may be configured to operate the memory 504. In some other implementations, the memory 504 may be integrated into the processor 502. The processor 502 may be configured to execute computer-readable instructions stored in the memory 504 to cause the UE 500 to perform various functions of the present disclosure.

[0085] The memory 504 may include volatile or non-volatile memory. The memory 504 may store computer-readable, computer-executable code including instructions when executed by the processor 502 cause the UE 500 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as the memory 504 or another type of memory. Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer.

[0086] In some implementations, the processor 502 and the memory 504 coupled with the processor 502 may be configured to cause the UE 500 to perform one or more of the functions described herein (e.g., executing, by the processor 502, instructions stored in the memory 504). For example, the processor 502 may support wireless communication at the UE 500 in accordance with examples as disclosed herein. The UE 500 may be configured to or operable to support a means for receiving a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 22 phases; and reporting an estimate of a receive phase offset between the first signal and the second signal.

[0087] Additionally, the UE 500 may be configured to support any one or combination of the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. An absolute error of the estimate of the receive phase offset is less than an accuracy threshold. The absolute error of the estimate of the receive phase offset is an indication of a receiver calibration requirement. The method further comprising reporting an additional estimate of a receive gain offset between the first signal and the second signal. An absolute error of the estimate of the receive gain offset is less than an accuracy threshold. The absolute error of the estimate of the receive gain offset is an indication of a receiver calibration requirement. The method further comprising transmitting signals via the two or more antenna connectors, the transmitted signals having different transmit phases. An absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. The absolute value difference between the transmit phase offset and the conjugate of the receive phase offset is an indication of receiver and transmitter calibration requirements. The method further comprising transmitting signals via the two or more antenna connectors, the transmitted signals having different transmit gains. An absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. The absolute value difference between the transmit gain offset and the receive gain offset is an indication of a receiver calibration requirement. The method further comprising receiving the first signal and the second signal from a test equipment that simulates a NE.

[0088] Additionally, or alternatively, the UE 500 may support at least one memory (e.g., the memory 504) and at least one processor (e.g., the processor 502) coupled with the at least one memory and configured to cause the UE to receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal.

[0089] Additionally, the UE 500 may be configured to support any one or combination of the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. An absolute error of the estimate of the receive phase offset is less Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 23 than an accuracy threshold. The absolute error of the estimate of the receive phase offset is an indication of a receiver calibration requirement. The at least one processor is configured to cause the UE to report an additional estimate of a receive gain offset between the first signal and the second signal. An absolute error of the estimate of the receive gain offset is less than an accuracy threshold. The absolute error of the estimate of the receive gain offset is an indication of a receiver calibration requirement. The at least one processor is configured to cause the UE to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit phases. An absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. The absolute value difference between the transmit phase offset and the conjugate of the receive phase offset is an indication of receiver and transmitter calibration requirements. The at least one processor is configured to cause the UE to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit gains. An absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. The absolute value difference between the transmit gain offset and the receive gain offset is an indication of a receiver calibration requirement. The at least one processor is configured to cause the UE to receive the first signal and the second signal from a test equipment that simulates a NE.

[0090] In some implementations, the baseband processor 514 and the memory 504 coupled with the baseband processor 514 may be configured to cause the UE 500 to perform one or more of the functions described herein (e.g., executing, by the processor 502, instructions stored in the memory 504). For example, the baseband processor 514 may support wireless communication at the UE 500 in accordance with examples as disclosed herein. The baseband processor 514 may be configured to or operable to support a means for receiving a first signal via a first antenna connector of a multi- antenna receiver; receiving a second signal via a second antenna connector of the multi-antenna receiver; comparing a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal; and reporting the estimate of the receive phase offset between the first signal and the second signal.

[0091] Additionally, the baseband processor 514 may be configured to support any one or combination of the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. An absolute error of the estimate of the receive Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 24 phase offset is less than an accuracy threshold. The method further comprising comparing a receive gain of the first signal to a receive gain of the second signal to determine an additional estimate of a receive gain offset between the first signal and the second signal; and reporting the additional estimate of the receive gain offset between the first signal and the second signal. An absolute error of the estimate of the receive gain offset is less than an accuracy threshold. The method further comprising determining whether an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. The method further comprising determining whether an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold.

[0092] Additionally, or alternatively, the baseband processor 514 may be configured to or operable to support at least one controller (e.g., the controller 506) coupled with at least one memory (e.g., the memory 504) and configured to cause the baseband processor to receive a first signal via a first antenna connector of a multi-antenna receiver; receive a second signal via a second antenna connector of the multi-antenna receiver; compare a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal; and report the estimate of the receive phase offset between the first signal and the second signal.

[0093] Additionally, the baseband processor 514 may be configured to support any one or combination of the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. An absolute error of the estimate of the receive phase offset is less than an accuracy threshold. The at least one controller is configured to cause the baseband processor to compare a receive gain of the first signal to a receive gain of the second signal to determine an additional estimate of a receive gain offset between the first signal and the second signal; and report the additional estimate of the receive gain offset between the first signal and the second signal. An absolute error of the estimate of the receive gain offset is less than an accuracy threshold. The at least one controller is configured to cause the baseband processor to determine whether an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. The at least one controller is configured to cause the baseband processor to determine whether an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 25

[0094] The controller 506 may manage input and output signals for the UE 500. The controller 506 may also manage peripherals not integrated into the UE 500. In some implementations, the controller 506 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some implementations, the controller 506 may be implemented as part of the processor 502.

[0095] In some implementations, the UE 500 may include at least one transceiver 508. In some other implementations, the UE 500 may have more than one transceiver 508. The transceiver 508 may represent a wireless transceiver. The transceiver 508 may include one or more receiver chains 510, one or more transmitter chains 512, or a combination thereof. In some implementations, the transceiver 508 may include the baseband processor 514.

[0096] A receiver chain 510 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receiver chain 510 may include one or more antennas to receive a signal over the air or wireless medium. The receiver chain 510 may include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. The receiver chain 510 may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receiver chain 510 may include at least one decoder for decoding the demodulated signal to receive the transmitted data.

[0097] A transmitter chain 512 may be configured to generate and transmit signals (e.g., control information, data, packets). The transmitter chain 512 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM). The transmitter chain 512 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmitter chain 512 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0098] Figure 6 illustrates an example of a processor 600 in accordance with aspects of the present disclosure. The processor 600 may be an example of a processor configured to perform Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 26 various operations in accordance with examples as described herein. The processor 600 may include a controller 602 configured to perform various operations in accordance with examples as described herein. The processor 600 may optionally include at least one memory 604, which may be, for example, an L1 / L2 / L3 cache. Additionally, or alternatively, the processor 600 may optionally include one or more arithmetic-logic units (ALUs) 606. One or more of these components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces (e.g., buses).

[0099] The processor 600 may be a processor chipset and include a protocol stack (e.g., a software stack) executed by the processor chipset to perform various operations (e.g., receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) in accordance with examples as described herein. The processor chipset may include one or more cores, one or more caches (e.g., memory local to or included in the processor chipset (e.g., the processor 600) or other memory (e.g., random access memory (RAM), read-only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), static RAM (SRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase change memory (PCM), and others).

[0100] The controller 602 may be configured to manage and coordinate various operations (e.g., signaling, receiving, obtaining, retrieving, transmitting, outputting, forwarding, storing, determining, identifying, accessing, writing, reading) of the processor 600 to cause the processor 600 to support various operations in accordance with examples as described herein. For example, the controller 602 may operate as a control unit of the processor 600, generating control signals that manage the operation of various components of the processor 600. These control signals include enabling or disabling functional units, selecting data paths, initiating memory access, and coordinating timing of operations.

[0101] The controller 602 may be configured to fetch (e.g., obtain, retrieve, receive) instructions from the memory 604 and determine subsequent instruction(s) to be executed to cause the processor 600 to support various operations in accordance with examples as described herein. The controller 602 may be configured to track memory addresses of instructions associated with the memory 604. The controller 602 may be configured to decode instructions to determine the operation to be performed and the operands involved. For example, the controller 602 may be configured to Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 27 interpret the instruction and determine control signals to be output to other components of the processor 600 to cause the processor 600 to support various operations in accordance with examples as described herein. Additionally, or alternatively, the controller 602 may be configured to manage flow of data within the processor 600. The controller 602 may be configured to control transfer of data between registers, ALUs 606, and other functional units of the processor 600.

[0102] The memory 604 may include one or more caches (e.g., memory local to or included in the processor 600 or other memory, such as RAM, ROM, DRAM, SDRAM, SRAM, MRAM, flash memory, etc. In some implementations, the memory 604 may reside within or on a processor chipset (e.g., local to the processor 600). In some other implementations, the memory 604 may reside external to the processor chipset (e.g., remote to the processor 600).

[0103] The memory 604 may store computer-readable, computer-executable code including instructions that, when executed by the processor 600, cause the processor 600 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. The controller 602 and / or the processor 600 may be configured to execute computer-readable instructions stored in the memory 604 to cause the processor 600 to perform various functions. For example, the processor 600 and / or the controller 602 may be coupled with or to the memory 604, the processor 600, and the controller 602, and may be configured to perform various functions described herein. In some examples, the processor 600 may include multiple processors and the memory 604 may include multiple memories. One or more of the multiple processors may be coupled with one or more of the multiple memories, which may, individually or collectively, be configured to perform various functions herein.

[0104] The one or more ALUs 606 may be configured to support various operations in accordance with examples as described herein. In some implementations, the one or more ALUs 606 may reside within or on a processor chipset (e.g., the processor 600). In some other implementations, the one or more ALUs 606 may reside external to the processor chipset (e.g., the processor 600). One or more ALUs 606 may perform one or more computations such as addition, subtraction, multiplication, and division on data. For example, one or more ALUs 606 may receive input operands and an operation code, which determines an operation to be executed. One or more ALUs 606 may be configured with a variety of logical and arithmetic circuits, including adders, subtractors, shifters, and logic gates, to process and manipulate the data according to the operation. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 28 Additionally, or alternatively, the one or more ALUs 606 may support logical operations such as AND, OR, exclusive-OR (XOR), not-OR (NOR), and not-AND (NAND), enabling the one or more ALUs 606 to handle conditional operations, comparisons, and bitwise operations.

[0105] The processor 600 may support wireless communication in accordance with examples as disclosed herein. The processor 600 may be configured to or operable to support at least one controller (e.g., the controller 602) coupled with at least one memory (e.g., the memory 604) and configured to cause the processor to receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal.

[0106] Additionally, the processor 600 may be configured to or operable to support any one or combination of the first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal. An absolute error of the estimate of the receive phase offset is less than an accuracy threshold. The absolute error of the estimate of the receive phase offset is an indication of a receiver calibration requirement. The at least one controller is configured to cause the processor to report an additional estimate of a receive gain offset between the first signal and the second signal. An absolute error of the estimate of the receive gain offset is less than an accuracy threshold. The absolute error of the estimate of the receive gain offset is an indication of a receiver calibration requirement. The at least one controller is configured to cause the processor to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit phases. An absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. The absolute value difference between the transmit phase offset and the conjugate of the receive phase offset is an indication of receiver and transmitter calibration requirements. The at least one controller is configured to cause the processor to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit gains. An absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold. The absolute value difference between the transmit gain offset and the receive gain offset is an indication of a receiver calibration requirement. The at least one controller is configured to cause the processor to receive the first signal and the second signal from a test equipment that simulates a NE. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 29

[0107] Figure 7 illustrates an example of a test equipment 700 in accordance with aspects of the present disclosure. In some implementations, the test equipment 700 simulates a NE 102. The test equipment 700 may include a processor 702, a memory 704, a controller 706, and a transceiver 708. The processor 702, the memory 704, the controller 706, or the transceiver 708, or various combinations thereof or various components thereof may be examples of means for performing various aspects of the present disclosure as described herein. These components may be coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more interfaces.

[0108] The processor 702, the memory 704, the controller 706, or the transceiver 708, or various combinations or components thereof may be implemented in hardware (e.g., circuitry). The hardware may include a processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), or other programmable logic device, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure.

[0109] The processor 702 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination thereof). In some implementations, the processor 702 may be configured to operate the memory 704. In some other implementations, the memory 704 may be integrated into the processor 702. The processor 702 may be configured to execute computer-readable instructions stored in the memory 704 to cause the test equipment 700 to perform various functions of the present disclosure.

[0110] The memory 704 may include volatile or non-volatile memory. The memory 704 may store computer-readable, computer-executable code including instructions when executed by the processor 702 cause the test equipment 700 to perform various functions described herein. The code may be stored in a non-transitory computer-readable medium such as the memory 704 or another type of memory. Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 30

[0111] In some implementations, the processor 702 and the memory 704 coupled with the processor 702 may be configured to cause the test equipment 700 to perform one or more of the functions described herein (e.g., executing, by the processor 702, instructions stored in the memory 704). For example, the processor 702 may support wireless communication at the test equipment 700 in accordance with examples as disclosed herein. The test equipment 700 may be configured to or operable to support a means for transmitting a first signal and a second signal to a UE, where the first and second signals have different receive gains and different receive phases; and receiving an estimate of a receive phase offset between the first and second signals. The first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal.

[0112] Additionally, or alternatively, the test equipment 700 may support at least one memory (e.g., the memory 704) and at least one processor (e.g., the processor 702) coupled with the at least one memory and configured to cause the test equipment to transmit a first signal and a second signal to a UE, where the first and second signals have different receive gains and different receive phases; and receive an estimate of a receive phase offset between the first and second signals. The first signal and the second signal are OFDM modulated, and the second signal is a phase shifted and scaled version of the first signal.

[0113] The controller 706 may manage input and output signals for the test equipment 700. The controller 706 may also manage peripherals not integrated into the test equipment 700. In some implementations, the controller 706 may utilize an operating system such as iOS®, ANDROID®, WINDOWS®, or other operating systems. In some implementations, the controller 706 may be implemented as part of the processor 702.

[0114] In some implementations, the test equipment 700 may include at least one transceiver 708. In some other implementations, the test equipment 700 may have more than one transceiver 708. The transceiver 708 may represent a wireless transceiver. The transceiver 708 may include one or more receiver chains 710, one or more transmitter chains 712, or a combination thereof.

[0115] A receiver chain 710 may be configured to receive signals (e.g., control information, data, packets) over a wireless medium. For example, the receiver chain 710 may include one or more antennas to receive a signal over the air or wireless medium. The receiver chain 710 may Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 31 include at least one amplifier (e.g., a low-noise amplifier (LNA)) configured to amplify the received signal. The receiver chain 710 may include at least one demodulator configured to demodulate the receive signal and obtain the transmitted data by reversing the modulation technique applied during transmission of the signal. The receiver chain 710 may include at least one decoder for decoding the demodulated signal to receive the transmitted data.

[0116] A transmitter chain 712 may be configured to generate and transmit signals (e.g., control information, data, packets). The transmitter chain 712 may include at least one modulator for modulating data onto a carrier signal, preparing the signal for transmission over a wireless medium. The at least one modulator may be configured to support one or more techniques such as amplitude modulation (AM), frequency modulation (FM), or digital modulation schemes like phase-shift keying (PSK) or quadrature amplitude modulation (QAM). The transmitter chain 712 may also include at least one power amplifier configured to amplify the modulated signal to an appropriate power level suitable for transmission over the wireless medium. The transmitter chain 712 may also include one or more antennas for transmitting the amplified signal into the air or wireless medium.

[0117] Figure 8 illustrates a flowchart of a method 800 in accordance with aspects of the present disclosure. The operations of the method may be implemented by a UE as described herein. In some implementations, the UE may execute a set of instructions to control the function elements of the UE to perform the described functions. It should be noted that the method described herein describes a possible implementation, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible.

[0118] At 802, the method may include receiving a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases. The operations of 802 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 802 may be performed by a UE as described with reference to Figure 5.

[0119] At 804, the method may include reporting an estimate of a receive phase offset between the first signal and the second signal. The operations of 804 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 804 may be performed by a UE as described with reference to Figure 5. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 32

[0120] Figure 9 illustrates a flowchart of a method 900 in accordance with aspects of the present disclosure. The operations of the method may be implemented by a baseband processor of a UE as described herein. In some implementations, the NE may execute a set of instructions to control the function elements of the NE to perform the described functions. It should be noted that the method described herein describes a possible implementation, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible.

[0121] At 902, the method may include receiving a first signal via a first antenna connector of a multi-antenna receiver. The operations of 902 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 902 may be performed by a baseband processor of a UE as described with reference to Figure 5.

[0122] At 904, the method may include receiving a second signal via a second antenna connector of the multi-antenna receiver. The operations of 904 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 904 may be performed by a baseband processor of a UE as described with reference to Figure 5.

[0123] At 906, the method may include comparing a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal. The operations of 906 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 906 may be performed a baseband processor of a UE as described with reference to Figure 5.

[0124] At 908, the method may include reporting the estimate of the receive phase offset between the first signal and the second signal. The operations of 908 may be performed in accordance with examples as described herein. In some implementations, aspects of the operations of 908 may be performed a baseband processor of a UE as described with reference to Figure 5.

[0125] The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein. Attorney Ref. No. SMM920230181-WO-PCT

Claims

Lenovo Ref. No. SMM920230181-WO-PCT 33 CLAIMS What is claimed is:

1. A user equipment (UE) for wireless communication, comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the UE to: receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal.

2. The UE of claim 1, wherein the first signal and the second signal are orthogonal frequency division multiplexing (OFDM) modulated, and the second signal is a phase shifted and scaled version of the first signal.

3. The UE of claim 1, wherein an absolute error of the estimate of the receive phase offset is less than an accuracy threshold.

4. The UE of claim 1, wherein the at least one processor is configured to cause the UE to report an additional estimate of a receive gain offset between the first signal and the second signal.

5. The UE of claim 4, wherein an absolute error of the estimate of the receive gain offset is less than an accuracy threshold.

6. The UE of claim 1, wherein the at least one processor is configured to cause the UE to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit phases.

7. The UE of claim 6, wherein an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 34 8. The UE of claim 1, wherein the at least one processor is configured to cause the UE to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit gains.

9. The UE of claim 8, wherein an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold.

10. A processor for wireless communication, comprising: at least one controller coupled with at least one memory and configured to cause the processor to: receive a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and report an estimate of a receive phase offset between the first signal and the second signal.

11. The processor of claim 10, wherein the first signal and the second signal are orthogonal frequency division multiplexing (OFDM) modulated, and the second signal is a phase shifted and scaled version of the first signal.

12. The processor of claim 10, wherein an absolute error of the estimate of the receive phase offset is less than an accuracy threshold.

13. The processor of claim 10, wherein the at least one controller is configured to cause the processor to report an additional estimate of a receive gain offset between the first signal and the second signal.

14. The processor of claim 13, wherein an absolute error of the estimate of the receive gain offset is less than an accuracy threshold.

15. The processor of claim 10, wherein the at least one controller is configured to cause the processor to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit phases. Attorney Ref. No. SMM920230181-WO-PCTLenovo Ref. No. SMM920230181-WO-PCT 35 16. The processor of claim 15, wherein an absolute value difference between a transmit phase offset and a conjugate of the receive phase offset is less than an accuracy threshold.

17. The processor of claim 10, wherein the at least one controller is configured to cause the processor to transmit signals via the two or more antenna connectors, the transmitted signals having different transmit gains.

18. The processor of claim 17, wherein an absolute value difference between a transmit gain offset and a receive gain offset is less than an accuracy threshold.

19. A method performed by a user equipment (UE), the method comprising: receiving a first signal and a second signal at two or more antenna connectors of a multi-antenna receiver, the first signal and the second signal having different receive gains and different receive phases; and reporting an estimate of a receive phase offset between the first signal and the second signal.

20. A baseband processor for wireless communication, comprising: at least one controller coupled with at least one memory and configured to cause the baseband processor to: receive a first signal via a first antenna connector of a multi-antenna receiver; receive a second signal via a second antenna connector of the multi-antenna receiver; compare a receive phase of the first signal to a receive phase of the second signal to determine an estimate of a receive phase offset between the first signal and the second signal; and report the estimate of the receive phase offset between the first signal and the second signal. Attorney Ref. No. SMM920230181-WO-PCT

Images