TECHNIQUES FOR PROVIDING FEEDBACK IN A PILOT SYMBOL

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration associated with transmitting acknowledgment (ACK) or negative ACK (NACK) feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal. The UE may receive a communication. The UE may transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration. Numerous other aspects are described.

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and specifically relate to techniques, apparatuses, and methods for providing feedback in a pilot symbol.

DESCRIPTION OF RELATED ART

Wireless communication systems are widely deployed to provide various services that may include carrying voice, text, messaging, video, data, and/or other traffic. The services may include unicast, multicast, and/or broadcast services, among other examples. Typical wireless communication systems may employ multiple-access radio access technologies (RATs) capable of supporting communication with multiple users by sharing available system resources (for example, time domain resources, frequency domain resources, spatial domain resources, and/or device transmit power, among other examples). Examples of such multiple-access RATs include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple-access RATs have been adopted in various telecommunication standards to provide common protocols that enable different wireless communication devices to communicate on a municipal, national, regional, or global level. An example telecommunication standard is New Radio (NR). NR, which may also be referred to as 5G, is part of a continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP). NR (and other mobile broadband evolutions beyond NR) may be designed to better support Internet of things (IoT) and reduced capability device deployments, industrial connectivity, millimeter wave (mmWave) expansion, licensed and unlicensed spectrum access, non-terrestrial network (NTN) deployment, sidelink and other device-to-device direct communication technologies (for example, cellular vehicle-to-everything (CV2X) communication), massive multiple-input multiple-output (MIMO), disaggregated network architectures and network topology expansions, multiple-subscriber implementations, high-precision positioning, and/or radio frequency (RF) sensing, among other examples. As the demand for mobile broadband access continues to increase, further improvements in NR may be implemented, and other radio access technologies such as 6G may be introduced, to further advance mobile broadband evolution.

SUMMARY

In some aspects, a method of wireless communication performed by a user equipment (UE) includes receiving a configuration associated with transmitting acknowledgment (ACK) or negative ACK (NACK) feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receiving a communication; and transmitting the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

In some aspects, a method of wireless communication performed by a network node includes transmitting a configuration associated with transmitting NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receiving a transmission including the pilot symbol; performing a first channel estimation on the transmission; identifying the ACK or NACK feedback in accordance with the first channel estimation; and performing a second channel estimation on the transmission using the ACK or NACK feedback.

In some aspects, an apparatus for wireless communication at a UE includes one or more memories; and one or more processors, coupled to the one or more memories, configured to cause the UE to: receive a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a communication; and transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

In some aspects, an apparatus for wireless communication at a network node includes one or more memories; and one or more processors, coupled to the one or more memories, configured to cause the network node to: transmit a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a transmission including the pilot symbol; perform a first channel estimation on the transmission; identify the ACK or NACK feedback in accordance with the first channel estimation; and perform a second channel estimation on the transmission using the ACK or NACK feedback.

In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to: receive a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a communication; and transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a network node, cause the network node to: transmit a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a transmission including the pilot symbol; perform a first channel estimation on the transmission; identify the ACK or NACK feedback in accordance with the first channel estimation; and perform a second channel estimation on the transmission using the ACK or NACK feedback.

In some aspects, an apparatus for wireless communication includes means for receiving a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; means for receiving a communication; and means for transmitting the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

In some aspects, an apparatus for wireless communication includes means for transmitting a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; means for receiving a transmission including the pilot symbol; means for performing a first channel estimation on the transmission; means for identifying the ACK or NACK feedback in accordance with the first channel estimation; and means for performing a second channel estimation on the transmission using the ACK or NACK feedback.

Aspects of the present disclosure may generally be implemented by or as a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, network node, network entity, wireless communication device, and/or processing system as substantially described with reference to, and as illustrated by, the specification.

The foregoing paragraphs of this section have broadly summarized some aspects of the present disclosure. These and additional aspects and associated advantages will be described hereinafter. The disclosed aspects may be used as a basis for modifying or designing other aspects for carrying out the same or similar purposes of the present disclosure. Such equivalent aspects do not depart from the scope of the appended claims. Characteristics of the aspects disclosed herein, both their organization and method of operation, together with associated advantages, will be better understood from the following description when considered in connection with the accompanying drawings.

DETAILED DESCRIPTION

Various aspects of the present disclosure are described hereinafter with reference to the accompanying drawings. However, aspects of the present disclosure may be embodied in many different forms and is not to be construed as limited to any specific aspect illustrated by or described with reference to an accompanying drawing or otherwise presented in this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. One skilled in the art may appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using various combinations or quantities of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover an apparatus having, or a method that is practiced using, other structures and/or functionalities in addition to or other than the structures and/or functionalities with which various aspects of the disclosure set forth herein may be practiced. Any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

Several aspects of telecommunication systems will now be presented with reference to various methods, operations, apparatuses, and techniques. These methods, operations, apparatuses, and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, or algorithms (collectively referred to as “elements”). These elements may be implemented using hardware, software, or a combination of hardware and software. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

A user equipment (UE) may provide acknowledgment (ACK) or negative ACK (NACK) feedback (also referred to as ACK/NACK feedback) to indicate whether a communication was received by the UE. For example, the UE may transmit the ACK/NACK feedback after attempting to decode downlink data. If the UE successfully decodes and/or demodulates the downlink data, the UE may transmit an ACK. If the UE fails to successfully decode or demodulate the downlink data, the UE may transmit a NACK. In some deployments, a UE may support separate ACK/NACK feedback for each code block group (CBG), where a CBG is a group of one or more code blocks. ACK/NACK feedback at the granularity of the CBG may provide a more precise indication of demodulation success than ACK/NACK feedback at the granularity of the entire transport block (TB). However, CBG-granularity ACK/NACK feedback may involve higher overhead than TB-granularity ACK/NACK feedback, since CBG-granularity ACK/NACK feedback may include a binary indication per CBG of a TB, and TB-granularity ACK/NACK feedback may include a binary indication for the entire TB.

A UE may transmit various reference signals, such as a demodulation reference signal (DMRS) or a sounding reference signal (SRS). These reference signals may be transmitted in pilot symbols. A pilot symbol is an orthogonal frequency division multiplexing (OFDM) symbol configured to include a reference signal. For example, a symbol configured as a pilot symbol may not include any data transmission, and may include only reference signals and/or blank (unused, empty, zero-power) resource elements.

As mentioned, increasing the granularity of ACK/NACK feedback (such as by providing ACK/NACK feedback at the CBG granularity) may improve the efficiency of network operation by increasing the precision of the feedback. However, the increased granularity may also cause increased overhead and may use physical uplink control channel (PUCCH) resources for transmission of a larger ACK/NACK indication. This impact of increasing the granularity of ACK/NACK feedback may negatively impact other uplink control information transmissions such as scheduling requests.

Various aspects relate generally to providing ACK/NACK feedback in a pilot symbol. In some aspects, a UE may transmit ACK/NACK feedback in a pilot symbol. For example, the UE may multiplex the ACK/NACK feedback with reference signal resources in the pilot symbol, such as by placing the ACK/NACK feedback in blank resource elements. As another example, the UE may replace one or more reference signal resources (which may be referred to as known data subcarriers) with the ACK/NACK feedback. Some aspects described herein provide signaling of whether the UE should provide the ACK/NACK feedback in the pilot symbol and/or a configuration for providing the ACK/NACK feedback in the pilot symbol.

Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, by providing the ACK/NACK feedback in the pilot symbol, the described techniques can be used to reduce PUCCH overhead relative to providing the ACK/NACK feedback in a PUCCH. This reduced overhead may mean that more granular ACK/NACK feedback can be provided, such as ACK/NACK at the CBG granularity. By signaling whether the UE should provide the ACK/NACK feedback in the pilot symbol, the network can activate or deactivate this feature in association with different traffic conditions, channel conditions, or the like. By signaling a configuration for providing the ACK/NACK feedback in the pilot symbol, the network can configure the ACK/NACK feedback to be provided in appropriate resources, such as blank resources or reference signal resources, thereby improving efficiency of the ACK/NACK feedback and effectiveness of the reference signal transmission.

As mentioned, ACK/NACK feedback, particularly at the CBG granularity, may involve some amount of overhead. Providing the ACK/NACK feedback in a pilot symbol for an uplink reference signal may impact the performance of the uplink reference signal, such as by reducing the number of reference signal resources available for the uplink reference signal or occupying blank resources with ACK/NACK feedback. In this case, channel estimation or demodulation performance may be negatively impacted.

Some aspects of the present disclosure provide channel estimation based at least in part on ACK/NACK feedback in a pilot symbol. For example, a network node may receive a transmission including a pilot symbol carrying ACK/NACK feedback. The network node may perform a first channel estimation using reference signal resources of the pilot symbol. The network node may demodulate the ACK/NACK feedback in accordance with the first channel estimation. The network node may then perform a second channel estimation using the ACK/NACK feedback. For example, the network node may refine channel estimation using known values of the ACK/NACK feedback as part of the reference signal. In this way, performance of channel estimation using a reference signal in a pilot symbol can be preserved or improved while also providing ACK/NACK feedback in the pilot symbol.

Multiple-access radio access technologies (RATs) have been adopted in various telecommunication standards to provide common protocols that enable wireless communication devices to communicate on a municipal, enterprise, national, regional, or global level. For example, 5G New Radio (NR) is part of a continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP). 5G NR supports various technologies and use cases including enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), massive machine-type communication (mMTC), millimeter wave (mmWave) technology, beamforming, network slicing, edge computing, Internet of Things (IoT) connectivity and management, and network function virtualization (NFV).

As the demand for broadband access increases and as technologies supported by wireless communication networks evolve, further technological improvements may be adopted in or implemented for 5G NR or future RATs, such as 6G, to further advance the evolution of wireless communication for a wide variety of existing and new use cases and applications. Such technological improvements may be associated with new frequency band expansion, licensed and unlicensed spectrum access, overlapping spectrum use, small cell deployments, non-terrestrial network (NTN) deployments, disaggregated network architectures and network topology expansion, device aggregation, advanced duplex communication, sidelink and other device-to-device direct communication, IoT (including passive or ambient IoT) networks, reduced capability (RedCap) UE functionality, industrial connectivity, multiple-subscriber implementations, high-precision positioning, radio frequency (RF) sensing, and/or artificial intelligence or machine learning (AI/ML), among other examples. These technological improvements may support use cases such as wireless backhauls, wireless data centers, extended reality (XR) and metaverse applications, meta services for supporting vehicle connectivity, holographic and mixed reality communication, autonomous and collaborative robots, vehicle platooning and cooperative maneuvering, sensing networks, gesture monitoring, human-brain interfacing, digital twin applications, asset management, and universal coverage applications using non-terrestrial and/or aerial platforms, among other examples. The methods, operations, apparatuses, and techniques described herein may enable one or more of the foregoing technologies and/or support one or more of the foregoing use cases.

FIG. 1 is a diagram illustrating an example of a wireless communication network 100 in accordance with the present disclosure. The wireless communication network 100 may be or may include elements of a 5G (or NR) network or a 6G network, among other examples. The wireless communication network 100 may include multiple network nodes 110, shown as a network node (NN) 110a, a network node 110b, a network node 110c, and a network node 110d. The network nodes 110 may support communications with multiple UEs 120, shown as a UE 120a, a UE 120b, a UE 120c, a UE 120d, and a UE 120e.

The network nodes 110 and the UEs 120 of the wireless communication network 100 may communicate using the electromagnetic spectrum, which may be subdivided by frequency or wavelength into various classes, bands, carriers, or channels. For example, devices of the wireless communication network 100 may communicate using one or more operating bands. In some aspects, multiple wireless networks 100 may be deployed in a given geographic area. Each wireless communication network 100 may support a particular RAT (which may also be referred to as an air interface) and may operate on one or more carrier frequencies in one or more frequency ranges. Examples of RATs include a 4G RAT, a 5G/NR RAT, and/or a 6G RAT, among other examples. In some examples, when multiple RATs are deployed in a given geographic area, each RAT in the geographic area may operate on different frequencies to avoid interference with one another.

Various operating bands have been defined as frequency range designations FR1 (410 MHz through 7.125 GHz), FR2 (24.25 GHz through 52.6 GHZ), FR3 (7.125 GHz through 24.25 GHz), FR4a or FR4-1 (52.6 GHz through 71 GHz), FR4 (52.6 GHz through 114.25 GHz), and FR5 (114.25 GHz through 300 GHz). Although a portion of FR1 is greater than 6 GHz, FR1 is often referred to (interchangeably) as a “Sub-6 GHZ” band in some documents and articles. Similarly, FR2 is often referred to (interchangeably) as a “millimeter wave” band in some documents and articles, despite being different than the extremely high frequency (EHF) band (30 GHz through 300 GHz), which is identified by the International Telecommunications Union (ITU) as a “millimeter wave” band. The frequencies between FR1 and FR2 are often referred to as mid-band frequencies, which include FR3. Frequency bands falling within FR3 may inherit FR1 characteristics or FR2 characteristics, and thus may effectively extend features of FR1 or FR2 into mid-band frequencies. Thus, “sub-6 GHz,” if used herein, may broadly refer to frequencies that are less than 6 GHZ, that are within FR1, and/or that are included in mid-band frequencies. Similarly, the term “millimeter wave,” if used herein, may broadly refer to frequencies that are included in mid-band frequencies, that are within FR2, FR4, FR4-a or FR4-1, or FR5, and/or that are within the EHF band. Higher frequency bands may extend 5G NR operation, 6G operation, and/or other RATs beyond 52.6 GHz. For example, each of FR4a, FR4-1, FR4, and FR5 falls within the EHF band. In some examples, the wireless communication network 100 may implement dynamic spectrum sharing (DSS), in which multiple RATs (for example, 4G/LTE and 5G/NR) are implemented with dynamic bandwidth allocation (for example, based on user demand) in a single frequency band. It is contemplated that the frequencies included in these operating bands (for example, FR1, FR2, FR3, FR4, FR4-a, FR4-1, and/or FR5) may be modified, and techniques described herein may be applicable to those modified frequency ranges.

A network node 110 may include one or more devices, components, or systems that enable communication between a UE 120 and one or more devices, components, or systems of the wireless communication network 100. A network node 110 may be, may include, or may also be referred to as an NR network node, a 5G network node, a 6G network node, a Node B, an eNB, a gNB, an access point (AP), a transmission reception point (TRP), a mobility element, a core, a network entity, a network element, a network equipment, and/or another type of device, component, or system included in a radio access network (RAN).

A network node 110 may be implemented as a single physical node (for example, a single physical structure) or may be implemented as two or more physical nodes (for example, two or more distinct physical structures). For example, a network node 110 may be a device or system that implements part of a radio protocol stack, a device or system that implements a full radio protocol stack (such as a full gNB protocol stack), or a collection of devices or systems that collectively implement the full radio protocol stack. For example, and as shown, a network node 110 may be an aggregated network node (having an aggregated architecture), meaning that the network node 110 may implement a full radio protocol stack that is physically and logically integrated within a single node (for example, a single physical structure) in the wireless communication network 100. For example, an aggregated network node 110 may consist of a single standalone base station or a single TRP that uses a full radio protocol stack to enable or facilitate communication between a UE 120 and a core network of the wireless communication network 100.

Alternatively, and as also shown, a network node 110 may be a disaggregated network node (sometimes referred to as a disaggregated base station), meaning that the network node 110 may implement a radio protocol stack that is physically distributed and/or logically distributed among two or more nodes in the same geographic location or in different geographic locations. For example, a disaggregated network node may have a disaggregated architecture. In some deployments, disaggregated network nodes 110 may be used in an integrated access and backhaul (IAB) network, in an open radio access network (O-RAN) (such as a network configuration in compliance with the O-RAN Alliance), or in a virtualized radio access network (vRAN), also known as a cloud radio access network (C-RAN), to facilitate scaling by separating base station functionality into multiple units that can be individually deployed.

The network nodes 110 of the wireless communication network 100 may include one or more central units (CUs), one or more distributed units (DUs), and/or one or more radio units (RUs). A CU may host one or more higher layer control functions, such as radio resource control (RRC) functions, packet data convergence protocol (PDCP) functions, and/or service data adaptation protocol (SDAP) functions, among other examples. A DU may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and/or one or more higher physical (PHY) layers depending, at least in part, on a functional split, such as a functional split defined by the 3GPP. In some examples, a DU also may host one or more lower PHY layer functions, such as a fast Fourier transform (FFT), an inverse FFT (iFFT), beamforming, physical random access channel (PRACH) extraction and filtering, and/or scheduling of resources for one or more UEs 120, among other examples. An RU may host RF processing functions or lower PHY layer functions, such as an FFT, an iFFT, beamforming, or PRACH extraction and filtering, among other examples, according to a functional split, such as a lower layer functional split. In such an architecture, each RU can be operated to handle over the air (OTA) communication with one or more UEs 120.

In some aspects, a single network node 110 may include a combination of one or more CUs, one or more DUs, and/or one or more RUs. Additionally or alternatively, a network node 110 may include one or more Near-Real Time (Near-RT) RAN Intelligent Controllers (RICs) and/or one or more Non-Real Time (Non-RT) RICs. In some examples, a CU, a DU, and/or an RU may be implemented as a virtual unit, such as a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU), among other examples. A virtual unit may be implemented as a virtual network function, such as associated with a cloud deployment.

Some network nodes 110 (for example, a base station, an RU, or a TRP) may provide communication coverage for a particular geographic area. In the 3GPP, the term “cell” can refer to a coverage area of a network node 110 or to a network node 110 itself, depending on the context in which the term is used. A network node 110 may support one or multiple (for example, three) cells. In some examples, a network node 110 may provide communication coverage for a macro cell, a pico cell, a femto cell, or another type of cell. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs 120 with service subscriptions. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs 120 with service subscriptions. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs 120 having association with the femto cell (for example, UEs 120 in a closed subscriber group (CSG)). A network node 110 for a macro cell may be referred to as a macro network node. A network node 110 for a pico cell may be referred to as a pico network node. A network node 110 for a femto cell may be referred to as a femto network node or an in-home network node. In some examples, a cell may not necessarily be stationary. For example, the geographic area of the cell may move according to the location of an associated mobile network node 110 (for example, a train, a satellite base station, an unmanned aerial vehicle, or a NTN network node).

The wireless communication network 100 may be a heterogeneous network that includes network nodes 110 of different types, such as macro network nodes, pico network nodes, femto network nodes, relay network nodes, aggregated network nodes, and/or disaggregated network nodes, among other examples. In the example shown in FIG. 1, the network node 110a may be a macro network node for a macro cell 130a, the network node 110b may be a pico network node for a pico cell 130b, and the network node 110c may be a femto network node for a femto cell 130c. Various different types of network nodes 110 may generally transmit at different power levels, serve different coverage areas, and/or have different impacts on interference in the wireless communication network 100 than other types of network nodes 110. For example, macro network nodes may have a high transmit power level (for example, 5 to 40 watts), whereas pico network nodes, femto network nodes, and relay network nodes may have lower transmit power levels (for example, 0.1 to 2 watts).

In some examples, a network node 110 may be, may include, or may operate as an RU, a TRP, or a base station that communicates with one or more UEs 120 via a radio access link (which may be referred to as a “Uu” link). The radio access link may include a downlink and an uplink. “Downlink” (or “DL”) refers to a communication direction from a network node 110 to a UE 120, and “uplink” (or “UL”) refers to a communication direction from a UE 120 to a network node 110. Downlink channels may include one or more control channels and one or more data channels. A downlink control channel may be used to transmit downlink control information (DCI) (for example, scheduling information, reference signals, and/or configuration information) from a network node 110 to a UE 120. A downlink data channel may be used to transmit downlink data (for example, user data associated with a UE 120) from a network node 110 to a UE 120. Downlink control channels may include one or more physical downlink control channels (PDCCHs), and downlink data channels may include one or more physical downlink shared channels (PDSCHs). Uplink channels may similarly include one or more control channels and one or more data channels. An uplink control channel may be used to transmit uplink control information (UCI) (for example, reference signals and/or feedback corresponding to one or more downlink transmissions) from a UE 120 to a network node 110. An uplink data channel may be used to transmit uplink data (for example, user data associated with a UE 120) from a UE 120 to a network node 110. Uplink control channels may include one or more physical uplink control channels (PUCCHs), and uplink data channels may include one or more physical uplink shared channels (PUSCHs). The downlink and the uplink may each include a set of resources on which the network node 110 and the UE 120 may communicate.

Downlink and uplink resources may include time domain resources (frames, subframes, slots, and/or symbols), frequency domain resources (frequency bands, component carriers, subcarriers, resource blocks, and/or resource elements), and/or spatial domain resources (particular transmit directions and/or beam parameters). Frequency domain resources of some bands may be subdivided into bandwidth parts (BWPs). A BWP may be a continuous block of frequency domain resources (for example, a continuous block of resource blocks) that are allocated for one or more UEs 120. A UE 120 may be configured with both an uplink BWP and a downlink BWP (where the uplink BWP and the downlink BWP may be the same BWP or different BWPs). A BWP may be dynamically configured (for example, by a network node 110 transmitting a DCI configuration to the one or more UEs 120) and/or reconfigured, which means that a BWP can be adjusted in real-time (or near-real-time) based on changing network conditions in the wireless communication network 100 and/or based on the specific requirements of the one or more UEs 120. This enables more efficient use of the available frequency domain resources in the wireless communication network 100 because fewer frequency domain resources may be allocated to a BWP for a UE 120 (which may reduce the quantity of frequency domain resources that a UE 120 is required to monitor), leaving more frequency domain resources to be spread across multiple UEs 120. Thus, BWPs may also assist in the implementation of lower-capability UEs 120 by facilitating the configuration of smaller bandwidths for communication by such UEs 120.

As described above, in some aspects, the wireless communication network 100 may be, may include, or may be included in, an IAB network. In an IAB network, at least one network node 110 is an anchor network node that communicates with a core network. An anchor network node 110 may also be referred to as an IAB donor (or “IAB-donor”). The anchor network node 110 may connect to the core network via a wired backhaul link. For example, an Ng interface of the anchor network node 110 may terminate at the core network. Additionally or alternatively, an anchor network node 110 may connect to one or more devices of the core network that provide a core access and mobility management function (AMF). An IAB network also generally includes multiple non-anchor network nodes 110, which may also be referred to as relay network nodes or simply as IAB nodes (or “IAB-nodes”). Each non-anchor network node 110 may communicate directly with the anchor network node 110 via a wireless backhaul link to access the core network, or may communicate indirectly with the anchor network node 110 via one or more other non-anchor network nodes 110 and associated wireless backhaul links that form a backhaul path to the core network. Some anchor network node 110 or other non-anchor network node 110 may also communicate directly with one or more UEs 120 via wireless access links that carry access traffic. In some examples, network resources for wireless communication (such as time resources, frequency resources, and/or spatial resources) may be shared between access links and backhaul links.

In some examples, any network node 110 that relays communications may be referred to as a relay network node, a relay station, or simply as a relay. A relay may receive a transmission of a communication from an upstream station (for example, another network node 110 or a UE 120) and transmit the communication to a downstream station (for example, a UE 120 or another network node 110). In this case, the wireless communication network 100 may include or be referred to as a “multi-hop network.” In the example shown in FIG. 1, the network node 110d (for example, a relay network node) may communicate with the network node 110a (for example, a macro network node) and the UE 120d in order to facilitate communication between the network node 110a and the UE 120d. Additionally or alternatively, a UE 120 may be or may operate as a relay station that can relay transmissions to or from other UEs 120. A UE 120 that relays communications may be referred to as a UE relay or a relay UE, among other examples.

The UEs 120 may be physically dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. A UE 120 may be, may include, or may be included in an access terminal, another terminal, a mobile station, or a subscriber unit. A UE 120 may be, include, or be coupled with a cellular phone (for example, a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device, a biometric device, a wearable device (for example, a smart watch, smart clothing, smart glasses, a smart wristband, and/or smart jewelry, such as a smart ring or a smart bracelet), an entertainment device (for example, a music device, a video device, and/or a satellite radio), an XR device, a vehicular component or sensor, a smart meter or sensor, industrial manufacturing equipment, a Global Navigation Satellite System (GNSS) device (such as a Global Positioning System device or another type of positioning device), a UE function of a network node, and/or any other suitable device or function that may communicate via a wireless medium.

A UE 120 and/or a network node 110 may include one or more chips, system-on-chips (SoCs), chipsets, packages, or devices that individually or collectively constitute or comprise a processing system. The processing system includes processor (or “processing”) circuitry in the form of one or multiple processors, microprocessors, processing units (such as central processing units (CPUs), graphics processing units (GPUs), neural processing units (NPUs) and/or digital signal processors (DSPs)), processing blocks, application-specific integrated circuits (ASIC), programmable logic devices (PLDs) (such as field programmable gate arrays (FPGAs)), or other discrete gate or transistor logic or circuitry (all of which may be generally referred to herein individually as “processors” or collectively as “the processor” or “the processor circuitry”). One or more of the processors may be individually or collectively configurable or configured to perform various functions or operations described herein. A group of processors collectively configurable or configured to perform a set of functions may include a first processor configurable or configured to perform a first function of the set and a second processor configurable or configured to perform a second function of the set, or may include the group of processors all being configured or configurable to perform the set of functions.

The processing system may further include memory circuitry in the form of one or more memory devices, memory blocks, memory elements or other discrete gate or transistor logic or circuitry, each of which may include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof (all of which may be generally referred to herein individually as “memories” or collectively as “the memory” or “the memory circuitry”). One or more of the memories may be coupled (for example, operatively coupled, communicatively coupled, electronically coupled, or electrically coupled) with one or more of the processors and may individually or collectively store processor-executable code (such as software) that, when executed by one or more of the processors, may configure one or more of the processors to perform various functions or operations described herein. Additionally or alternatively, in some examples, one or more of the processors may be preconfigured to perform various functions or operations described herein without requiring configuration by software. The processing system may further include or be coupled with one or more modems (such as a Wi-Fi (for example, IEEE compliant) modem or a cellular (for example, 3GPP 4G LTE, 5G, or 6G compliant) modem). In some implementations, one or more processors of the processing system include or implement one or more of the modems. The processing system may further include or be coupled with multiple radios (collectively “the radio”), multiple RF chains, or multiple transceivers, each of which may in turn be coupled with one or more of multiple antennas. In some implementations, one or more processors of the processing system include or implement one or more of the radios, RF chains or transceivers. The UE 120 may include or may be included in a housing that houses components associated with the UE 120 including the processing system.

Some UEs 120 may be considered machine-type communication (MTC) UEs, evolved or enhanced machine-type communication (eMTC), UEs, further enhanced eMTC (feMTC) UEs, or enhanced feMTC (efeMTC) UEs, or further evolutions thereof, all of which may be simply referred to as “MTC UEs”. An MTC UE may be, may include, or may be included in or coupled with a robot, an uncrewed aerial vehicle, a remote device, a sensor, a meter, a monitor, and/or a location tag. Some UEs 120 may be considered IoT devices and/or may be implemented as NB-IoT (narrowband IoT) devices. An IoT UE or NB-IoT device may be, may include, or may be included in or coupled with an industrial machine, an appliance, a refrigerator, a doorbell camera device, a home automation device, and/or a light fixture, among other examples. Some UEs 120 may be considered Customer Premises Equipment, which may include telecommunications devices that are installed at a customer location (such as a home or office) to enable access to a service provider's network (such as included in or in communication with the wireless communication network 100).

Some UEs 120 may be classified according to different categories in association with different complexities and/or different capabilities. UEs 120 in a first category may facilitate massive IoT in the wireless communication network 100, and may offer low complexity and/or cost relative to UEs 120 in a second category. UEs 120 in a second category may include mission-critical IoT devices, legacy UEs, baseline UEs, high-tier UEs, advanced UEs, full-capability UEs, and/or premium UEs that are capable of URLLC, enhanced mobile broadband (eMBB), and/or precise positioning in the wireless communication network 100, among other examples. A third category of UEs 120 may have mid-tier complexity and/or capability (for example, a capability between UEs 120 of the first category and UEs 120 of the second capability). A UE 120 of the third category may be referred to as a reduced capacity UE (“RedCap UE”), a mid-tier UE, an NR-Light UE, and/or an NR-Lite UE, among other examples. RedCap UEs may bridge a gap between the capability and complexity of NB-IoT devices and/or eMTC UEs, and mission-critical IoT devices and/or premium UEs. RedCap UEs may include, for example, wearable devices, IoT devices, industrial sensors, and/or cameras that are associated with a limited bandwidth, power capacity, and/or transmission range, among other examples. RedCap UEs may support healthcare environments, building automation, electrical distribution, process automation, transport and logistics, and/or smart city deployments, among other examples.

In some examples, two or more UEs 120 (for example, shown as UE 120a and UE 120e) may communicate directly with one another using sidelink communications (for example, without communicating by way of a network node 110 as an intermediary). As an example, the UE 120a may directly transmit data, control information, or other signaling as a sidelink communication to the UE 120e. This is in contrast to, for example, the UE 120a first transmitting data in an UL communication to a network node 110, which then transmits the data to the UE 120e in a DL communication. In various examples, the UEs 120 may transmit and receive sidelink communications using peer-to-peer (P2P) communication protocols, device-to-device (D2D) communication protocols, vehicle-to-everything (V2X) communication protocols (which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, and/or vehicle-to-pedestrian (V2P) protocols), and/or mesh network communication protocols. In some deployments and configurations, a network node 110 may schedule and/or allocate resources for sidelink communications between UEs 120 in the wireless communication network 100. In some other deployments and configurations, a UE 120 (instead of a network node 110) may perform, or collaborate or negotiate with one or more other UEs to perform, scheduling operations, resource selection operations, and/or other operations for sidelink communications.

In various examples, some of the network nodes 110 and the UEs 120 of the wireless communication network 100 may be configured for full-duplex operation in addition to half-duplex operation. A network node 110 or a UE 120 operating in a half-duplex mode may perform only one of transmission or reception during particular time resources, such as during particular slots, symbols, or other time periods. Half-duplex operation may involve time-division duplexing (TDD), in which DL transmissions of the network node 110 and UL transmissions of the UE 120 do not occur in the same time resources (that is, the transmissions do not overlap in time). In contrast, a network node 110 or a UE 120 operating in a full-duplex mode can transmit and receive communications concurrently (for example, in the same time resources). By operating in a full-duplex mode, network nodes 110 and/or UEs 120 may generally increase the capacity of the network and the radio access link. In some examples, full-duplex operation may involve frequency-division duplexing (FDD), in which DL transmissions of the network node 110 are performed in a first frequency band or on a first component carrier and transmissions of the UE 120 are performed in a second frequency band or on a second component carrier different than the first frequency band or the first component carrier, respectively. In some examples, full-duplex operation may be enabled for a UE 120 but not for a network node 110. For example, a UE 120 may simultaneously transmit an UL transmission to a first network node 110 and receive a DL transmission from a second network node 110 in the same time resources. In some other examples, full-duplex operation may be enabled for a network node 110 but not for a UE 120. For example, a network node 110 may simultaneously transmit a DL transmission to a first UE 120 and receive an UL transmission from a second UE 120 in the same time resources. In some other examples, full-duplex operation may be enabled for both a network node 110 and a UE 120.

In some examples, the UEs 120 and the network nodes 110 may perform MIMO communication. “MIMO” generally refers to transmitting or receiving multiple signals (such as multiple layers or multiple data streams) simultaneously over the same time and frequency resources. MIMO techniques generally exploit multipath propagation. MIMO may be implemented using various spatial processing or spatial multiplexing operations. In some examples, MIMO may support simultaneous transmission to multiple receivers, referred to as multi-user MIMO (MU-MIMO). Some RATs may employ advanced MIMO techniques, such as mTRP operation (including redundant transmission or reception on multiple TRPs), reciprocity in the time domain or the frequency domain, single-frequency-network (SFN) transmission, or non-coherent joint transmission (NC-JT).

In some aspects, the UE 120 may include a communication manager 140. As described in more detail elsewhere herein, the communication manager 140 may receive a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a communication; and transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration. Additionally, or alternatively, the communication manager 140 may perform one or more other operations described herein.

In some aspects, the network node 110 may include a communication manager 150. As described in more detail elsewhere herein, the communication manager 150 may transmit a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receive a transmission including the pilot symbol; perform a first channel estimation on the transmission; identify the ACK or NACK feedback in accordance with the first channel estimation; and perform a second channel estimation on the transmission using the ACK or NACK feedback. Additionally, or alternatively, the communication manager 150 may perform one or more other operations described herein.

FIG. 2 is a diagram illustrating an example network node 110 in communication with an example UE 120 in a wireless network.

As shown in FIG. 2, the network node 110 may include a data source 212, a transmit processor 214, a transmit (TX) MIMO processor 216, a set of modems 232 (shown as 232a through 232t, where t≥1), a set of antennas 234 (shown as 234a through 234v, where v≥1), a MIMO detector 236, a receive processor 238, a data sink 239, a controller/processor 240, a memory 242, a communication unit 244, a scheduler 246, and/or a communication manager 150, among other examples. In some configurations, one or a combination of the antenna(s) 234, the modem(s) 232, the MIMO detector 236, the receive processor 238, the transmit processor 214, and/or the TX MIMO processor 216 may be included in a transceiver of the network node 110. The transceiver may be under control of and used by one or more processors, such as the controller/processor 240, and in some aspects in conjunction with processor-readable code stored in the memory 242, to perform aspects of the methods, processes, and/or operations described herein. In some aspects, the network node 110 may include one or more interfaces, communication components, and/or other components that facilitate communication with the UE 120 or another network node.

The terms “processor,” “controller,” or “controller/processor” may refer to one or more controllers and/or one or more processors. For example, reference to “a/the processor,” “a/the controller/processor,” or the like (in the singular) should be understood to refer to any one or more of the processors described in connection with FIG. 2, such as a single processor or a combination of multiple different processors. Reference to “one or more processors” should be understood to refer to any one or more of the processors described in connection with FIG. 2. For example, one or more processors of the network node 110 may include transmit processor 214, TX MIMO processor 216, MIMO detector 236, receive processor 238, and/or controller/processor 240. Similarly, one or more processors of the UE 120 may include MIMO detector 256, receive processor 258, transmit processor 264, TX MIMO processor 266, and/or controller/processor 280.

For downlink communication from the network node 110 to the UE 120, the transmit processor 214 may receive data (“downlink data”) intended for the UE 120 (or a set of UEs that includes the UE 120) from the data source 212 (such as a data pipeline or a data queue). In some examples, the transmit processor 214 may select one or more MCSs for the UE 120 in accordance with one or more channel quality indicators (CQIs) received from the UE 120. The network node 110 may process the data (for example, including encoding the data) for transmission to the UE 120 on a downlink in accordance with the MCS(s) selected for the UE 120 to generate data symbols. The transmit processor 214 may process system information (for example, semi-static resource partitioning information (SRPI)) and/or control information (for example, CQI requests, grants, and/or upper layer signaling) and provide overhead symbols and/or control symbols. The transmit processor 214 may generate reference symbols for reference signals (for example, a cell-specific reference signal (CRS), a demodulation reference signal (DMRS), or a channel state information (CSI) reference signal (CSI-RS)) and/or synchronization signals (for example, a primary synchronization signal (PSS) or a secondary synchronization signals (SSS)).

The TX MIMO processor 216 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide a set of output symbol streams (for example, T output symbol streams) to the set of modems 232. For example, each output symbol stream may be provided to a respective modulator component (shown as MOD) of a modem 232. Each modem 232 may use the respective modulator component to process (for example, to modulate) a respective output symbol stream (for example, for orthogonal frequency division multiplexing (OFDM)) to obtain an output sample stream. Each modem 232 may further use the respective modulator component to process (for example, convert to analog, amplify, filter, and/or upconvert) the output sample stream to obtain a time domain downlink signal. The modems 232a through 232t may together transmit a set of downlink signals (for example, T downlink signals) via the corresponding set of antennas 234.

A downlink signal may include a DCI communication, a MAC control element (MAC-CE) communication, an RRC communication, a downlink reference signal, or another type of downlink communication. Downlink signals may be transmitted on a PDCCH, a PDSCH, and/or on another downlink channel. A downlink signal may carry one or more transport blocks (TBs) of data. A TB may be a unit of data that is transmitted over an air interface in the wireless communication network 100. A data stream (for example, from the data source 212) may be encoded into multiple TBs for transmission over the air interface. The quantity of TBs used to carry the data associated with a particular data stream may be associated with a TB size common to the multiple TBs. The TB size may be based on or otherwise associated with radio channel conditions of the air interface, the MCS used for encoding the data, the downlink resources allocated for transmitting the data, and/or another parameter. In general, the larger the TB size, the greater the amount of data that can be transmitted in a single transmission, which reduces signaling overhead. However, larger TB sizes may be more prone to transmission and/or reception errors than smaller TB sizes, but such errors may be mitigated by more robust error correction techniques.

For uplink communication from the UE 120 to the network node 110, uplink signals from the UE 120 may be received by an antenna 234, may be processed by a modem 232 (for example, a demodulator component, shown as DEMOD, of a modem 232), may be detected by the MIMO detector 236 (for example, a receive (Rx) MIMO processor) if applicable, and/or may be further processed by the receive processor 238 to obtain decoded data and/or control information. The receive processor 238 may provide the decoded data to a data sink 239 (which may be a data pipeline, a data queue, and/or another type of data sink) and provide the decoded control information to a processor, such as the controller/processor 240.

The network node 110 may use the scheduler 246 to schedule one or more UEs 120 for downlink or uplink communications. In some aspects, the scheduler 246 may use DCI to dynamically schedule DL transmissions to the UE 120 and/or UL transmissions from the UE 120. In some examples, the scheduler 246 may allocate recurring time domain resources and/or frequency domain resources that the UE 120 may use to transmit and/or receive communications using an RRC configuration (for example, a semi-static configuration), for example, to perform semi-persistent scheduling (SPS) or to configure a configured grant (CG) for the UE 120.

One or more of the transmit processor 214, the TX MIMO processor 216, the modem 232, the antenna 234, the MIMO detector 236, the receive processor 238, and/or the controller/processor 240 may be included in an RF chain of the network node 110. An RF chain may include one or more filters, mixers, oscillators, amplifiers, analog-to-digital converters (ADCs), and/or other devices that convert between an analog signal (such as for transmission or reception via an air interface) and a digital signal (such as for processing by one or more processors of the network node 110). In some aspects, the RF chain may be or may be included in a transceiver of the network node 110.

In some examples, the network node 110 may use the communication unit 244 to communicate with a core network and/or with other network nodes. The communication unit 244 may support wired and/or wireless communication protocols and/or connections, such as Ethernet, optical fiber, common public radio interface (CPRI), and/or a wired or wireless backhaul, among other examples. The network node 110 may use the communication unit 244 to transmit and/or receive data associated with the UE 120 or to perform network control signaling, among other examples. The communication unit 244 may include a transceiver and/or an interface, such as a network interface.

The UE 120 may include a set of antennas 252 (shown as antennas 252a through 252r, where r≥1), a set of modems 254 (shown as modems 254a through 254u, where u≥1), a MIMO detector 256, a receive processor 258, a data sink 260, a data source 262, a transmit processor 264, a TX MIMO processor 266, a controller/processor 280, a memory 282, and/or a communication manager 140, among other examples. One or more of the components of the UE 120 may be included in a housing 284. In some aspects, one or a combination of the antenna(s) 252, the modem(s) 254, the MIMO detector 256, the receive processor 258, the transmit processor 264, or the TX MIMO processor 266 may be included in a transceiver that is included in the UE 120. The transceiver may be under control of and used by one or more processors, such as the controller/processor 280, and in some aspects in conjunction with processor-readable code stored in the memory 282, to perform aspects of the methods, processes, or operations described herein. In some aspects, the UE 120 may include another interface, another communication component, and/or another component that facilitates communication with the network node 110 and/or another UE 120.

For downlink communication from the network node 110 to the UE 120, the set of antennas 252 may receive the downlink communications or signals from the network node 110 and may provide a set of received downlink signals (for example, R received signals) to the set of modems 254. For example, each received signal may be provided to a respective demodulator component (shown as DEMOD) of a modem 254. Each modem 254 may use the respective demodulator component to condition (for example, filter, amplify, downconvert, and/or digitize) a received signal to obtain input samples. Each modem 254 may use the respective demodulator component to further demodulate or process the input samples (for example, for OFDM) to obtain received symbols. The MIMO detector 256 may obtain received symbols from the set of modems 254, may perform MIMO detection on the received symbols if applicable, and may provide detected symbols. The receive processor 258 may process (for example, decode) the detected symbols, may provide decoded data for the UE 120 to the data sink 260 (which may include a data pipeline, a data queue, and/or an application executed on the UE 120), and may provide decoded control information and system information to the controller/processor 280.

For uplink communication from the UE 120 to the network node 110, the transmit processor 264 may receive and process data (“uplink data”) from a data source 262 (such as a data pipeline, a data queue, and/or an application executed on the UE 120) and control information from the controller/processor 280. The control information may include one or more parameters, feedback, one or more signal measurements, and/or other types of control information. In some aspects, the receive processor 258 and/or the controller/processor 280 may determine, for a received signal (such as received from the network node 110 or another UE), one or more parameters relating to transmission of the uplink communication. The one or more parameters may include a reference signal received power (RSRP) parameter, a received signal strength indicator (RSSI) parameter, a reference signal received quality (RSRQ) parameter, a CQI parameter, or a transmit power control (TPC) parameter, among other examples. The control information may include an indication of the RSRP parameter, the RSSI parameter, the RSRQ parameter, the CQI parameter, the TPC parameter, and/or another parameter. The control information may facilitate parameter selection and/or scheduling for the UE 120 by the network node 110.

The transmit processor 264 may generate reference symbols for one or more reference signals, such as an uplink DMRS, an uplink sounding reference signal (SRS), and/or another type of reference signal. The symbols from the transmit processor 264 may be precoded by the TX MIMO processor 266, if applicable, and further processed by the set of modems 254 (for example, for DFT-s-OFDM or CP-OFDM). The TX MIMO processor 266 may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide a set of output symbol streams (for example, U output symbol streams) to the set of modems 254. For example, each output symbol stream may be provided to a respective modulator component (shown as MOD) of a modem 254. Each modem 254 may use the respective modulator component to process (for example, to modulate) a respective output symbol stream (for example, for OFDM) to obtain an output sample stream. Each modem 254 may further use the respective modulator component to process (for example, convert to analog, amplify, filter, and/or upconvert) the output sample stream to obtain an uplink signal.

The modems 254a through 254u may transmit a set of uplink signals (for example, R uplink signals or U uplink symbols) via the corresponding set of antennas 252. An uplink signal may include a UCI communication, a MAC-CE communication, an RRC communication, or another type of uplink communication. Uplink signals may be transmitted on a PUSCH, a PUCCH, and/or another type of uplink channel. An uplink signal may carry one or more TBs of data. Sidelink data and control transmissions (that is, transmissions directly between two or more UEs 120) may generally use similar techniques as were described for uplink data and control transmission, and may use sidelink-specific channels such as a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), and/or a physical sidelink feedback channel (PSFCH).

One or more antennas of the set of antennas 252 or the set of antennas 234 may include, or may be included within, one or more antenna panels, one or more antenna groups, one or more sets of antenna elements, or one or more antenna arrays, among other examples. An antenna panel, an antenna group, a set of antenna elements, or an antenna array may include one or more antenna elements (within a single housing or multiple housings), a set of coplanar antenna elements, a set of non-coplanar antenna elements, or one or more antenna elements coupled with one or more transmission or reception components, such as one or more components of FIG. 2. As used herein, “antenna” can refer to one or more antennas, one or more antenna panels, one or more antenna groups, one or more sets of antenna elements, or one or more antenna arrays. “Antenna panel” can refer to a group of antennas (such as antenna elements) arranged in an array or panel, which may facilitate beamforming by manipulating parameters of the group of antennas. “Antenna module” may refer to circuitry including one or more antennas, which may also include one or more other components (such as filters, amplifiers, or processors) associated with integrating the antenna module into a wireless communication device.

In some examples, each of the antenna elements of an antenna 234 or an antenna 252 may include one or more sub-elements for radiating or receiving radio frequency signals. For example, a single antenna element may include a first sub-element cross-polarized with a second sub-element that can be used to independently transmit cross-polarized signals. The antenna elements may include patch antennas, dipole antennas, and/or other types of antennas arranged in a linear pattern, a two-dimensional pattern, or another pattern. A spacing between antenna elements may be such that signals with a desired wavelength transmitted separately by the antenna elements may interact or interfere constructively and destructively along various directions (such as to form a desired beam). For example, given an expected range of wavelengths or frequencies, the spacing may provide a quarter wavelength, a half wavelength, or another fraction of a wavelength of spacing between neighboring antenna elements to allow for the desired constructive and destructive interference patterns of signals transmitted by the separate antenna elements within that expected range.

The amplitudes and/or phases of signals transmitted via antenna elements and/or sub-elements may be modulated and shifted relative to each other (such as by manipulating phase shift, phase offset, and/or amplitude) to generate one or more beams, which is referred to as beamforming. The term “beam” may refer to a directional transmission of a wireless signal toward a receiving device or otherwise in a desired direction. “Beam” may also generally refer to a direction associated with such a directional signal transmission, a set of directional resources associated with the signal transmission (for example, an angle of arrival, a horizontal direction, and/or a vertical direction), and/or a set of parameters that indicate one or more aspects of a directional signal, a direction associated with the signal, and/or a set of directional resources associated with the signal. In some implementations, antenna elements may be individually selected or deselected for directional transmission of a signal (or signals) by controlling amplitudes of one or more corresponding amplifiers and/or phases of the signal(s) to form one or more beams. The shape of a beam (such as the amplitude, width, and/or presence of side lobes) and/or the direction of a beam (such as an angle of the beam relative to a surface of an antenna array) can be dynamically controlled by modifying the phase shifts, phase offsets, and/or amplitudes of the multiple signals relative to each other.

Different UEs 120 or network nodes 110 may include different numbers of antenna elements. For example, a UE 120 may include a single antenna element, two antenna elements, four antenna elements, eight antenna elements, or a different number of antenna elements. As another example, a network node 110 may include eight antenna elements, 24 antenna elements, 64 antenna elements, 128 antenna elements, or a different number of antenna elements. Generally, a larger number of antenna elements may provide increased control over parameters for beam generation relative to a smaller number of antenna elements, whereas a smaller number of antenna elements may be less complex to implement and may use less power than a larger number of antenna elements. Multiple antenna elements may support multiple-layer transmission, in which a first layer of a communication (which may include a first data stream) and a second layer of a communication (which may include a second data stream) are transmitted using the same time and frequency resources with spatial multiplexing.

In some aspects, the controller/processor 280 may be a component of a processing system. A processing system may generally be a system or a series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, the UE 120). For example, a processing system of the UE 120 may be a system that includes the various other components or subcomponents of the UE 120.

The processing system of the UE 120 may interface with one or more other components of the UE 120, may process information received from one or more other components (such as inputs or signals), or may output information to one or more other components. For example, a chip or modem of the UE 120 may include a processing system, a first interface to receive or obtain information, and a second interface to output, transmit, or provide information. In some examples, the first interface may be an interface between the processing system of the chip or modem and a receiver, such that the UE 120 may receive information or signal inputs, and the information may be passed to the processing system. In some examples, the second interface may be an interface between the processing system of the chip or modem and a transmitter, such that the UE 120 may transmit information output from the chip or modem. A person having ordinary skill in the art will readily recognize that the second interface also may obtain or receive information or signal inputs, and the first interface also may output, transmit, or provide information.

In some aspects, the controller/processor 240 may be a component of a processing system. A processing system may generally be a system or a series of machines or components that receives inputs and processes the inputs to produce a set of outputs (which may be passed to other systems or components of, for example, the network node 110). For example, a processing system of the network node 110 may be a system that includes the various other components or subcomponents of the network node 110.

The processing system of the network node 110 may interface with one or more other components of the network node 110, may process information received from one or more other components (such as inputs or signals), or may output information to one or more other components. For example, a chip or modem of the network node 110 may include a processing system, a first interface to receive or obtain information, and a second interface to output, transmit, or provide information. In some examples, the first interface may be an interface between the processing system of the chip or modem and a receiver, such that the network node 110 may receive information or signal inputs, and the information may be passed to the processing system. In some examples, the second interface may be an interface between the processing system of the chip or modem and a transmitter, such that the network node 110 may transmit information output from the chip or modem. A person having ordinary skill in the art will readily recognize that the second interface also may obtain or receive information or signal inputs, and the first interface also may output, transmit, or provide information.

FIG. 3 is a diagram illustrating an example disaggregated base station architecture 300 in accordance with the present disclosure. One or more components of the example disaggregated base station architecture 300 may be, may include, or may be included in one or more network nodes (such one or more network nodes 110). The disaggregated base station architecture 300 may include a CU 310 that can communicate directly with a core network 320 via a backhaul link, or that can communicate indirectly with the core network 320 via one or more disaggregated control units, such as a Non-RT RIC 350 associated with a Service Management and Orchestration (SMO) Framework 360 and/or a Near-RT RIC 370 (for example, via an E2 link). The CU 310 may communicate with one or more DUs 330 via respective midhaul links, such as via F1 interfaces. Each of the DUs 330 may communicate with one or more RUs 340 via respective fronthaul links. Each of the RUs 340 may communicate with one or more UEs 120 via respective RF access links. In some deployments, a UE 120 may be simultaneously served by multiple RUs 340.

Each of the components of the disaggregated base station architecture 300, including the CUs 310, the DUs 330, the RUs 340, the Near-RT RICs 370, the Non-RT RICs 350, and the SMO Framework 360, may include one or more interfaces or may be coupled with one or more interfaces for receiving or transmitting signals, such as data or information, via a wired or wireless transmission medium.

In some aspects, the CU 310 may be logically split into one or more CU user plane (CU-UP) units and one or more CU control plane (CU-CP) units. A CU-UP unit may communicate bidirectionally with a CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 310 may be deployed to communicate with one or more DUs 330, as necessary, for network control and signaling. Each DU 330 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 340. For example, a DU 330 may host various layers, such as an RLC layer, a MAC layer, or one or more PHY layers, such as one or more high PHY layers or one or more low PHY layers. Each layer (which also may be referred to as a module) may be implemented with an interface for communicating signals with other layers (and modules) hosted by the DU 330, or for communicating signals with the control functions hosted by the CU 310. Each RU 340 may implement lower layer functionality. In some aspects, real-time and non-real-time aspects of control and user plane communication with the RU(s) 340 may be controlled by the corresponding DU 330.

The SMO Framework 360 may support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 360 may support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operations and maintenance interface, such as an O1 interface. For virtualized network elements, the SMO Framework 360 may interact with a cloud computing platform (such as an open cloud (O-Cloud) platform 390) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface, such as an O2 interface. A virtualized network element may include, but is not limited to, a CU 310, a DU 330, an RU 340, a non-RT RIC 350, and/or a Near-RT RIC 370. In some aspects, the SMO Framework 360 may communicate with a hardware aspect of a 4G RAN, a 5G NR RAN, and/or a 6G RAN, such as an open eNB (O-eNB) 380, via an O1 interface. Additionally or alternatively, the SMO Framework 360 may communicate directly with each of one or more RUs 340 via a respective O1 interface. In some deployments, this configuration can enable each DU 330 and the CU 310 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The Non-RT RIC 350 may include or may implement a logical function that enables non-real-time control and optimization of RAN elements and resources, AI/ML workflows including model training and updates, and/or policy-based guidance of applications and/or features in the Near-RT RIC 370. The Non-RT RIC 350 may be coupled to or may communicate with (such as via an A1 interface) the Near-RT RIC 370. The Near-RT RIC 370 may include or may implement a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions via an interface (such as via an E2 interface) connecting one or more CUs 310, one or more DUs 330, and/or an O-eNB with the Near-RT RIC 370.

In some aspects, to generate AI/ML models to be deployed in the Near-RT RIC 370, the Non-RT RIC 350 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 370 and may be received at the SMO Framework 360 or the Non-RT RIC 350 from non-network data sources or from network functions. In some examples, the Non-RT RIC 350 or the Near-RT RIC 370 may tune RAN behavior or performance. For example, the Non-RT RIC 350 may monitor long-term trends and patterns for performance and may employ AI/ML models to perform corrective actions via the SMO Framework 360 (such as reconfiguration via an O1 interface) or via creation of RAN management policies (such as A1 interface policies).

The network node 110, the controller/processor 240 of the network node 110, the UE 120, the controller/processor 280 of the UE 120, the CU 310, the DU 330, the RU 340, or any other component(s) of FIG. 1, 2, or 3 may implement one or more techniques or perform one or more operations associated with ACK/NACK feedback in a pilot symbol, as described in more detail elsewhere herein. For example, the controller/processor 240 of the network node 110, the controller/processor 280 of the UE 120, any other component(s) (or combinations of components) of FIG. 2, the CU 310, the DU 330, or the RU 340 may perform or direct operations of, for example, process 800 of FIG. 8, process 900 of FIG. 9, or other processes as described herein (alone or in conjunction with one or more other processors). The memory 242 may store data and program codes for the network node 110, the network node 110, the CU 310, the DU 330, or the RU 340. The memory 282 may store data and program codes for the UE 120. In some examples, the memory 242 or the memory 282 may include a non-transitory computer-readable medium storing a set of instructions (for example, code or program code) for wireless communication. The memory 242 may include one or more memories, such as a single memory or multiple different memories (of the same type or of different types). The memory 282 may include one or more memories, such as a single memory or multiple different memories (of the same type or of different types). For example, the set of instructions, when executed (for example, directly, or after compiling, converting, or interpreting) by one or more processors of the network node 110, the UE 120, the CU 310, the DU 330, or the RU 340, may cause the one or more processors to perform process 800 of FIG. 8, process 900 of FIG. 9, or other processes as described herein. In some examples, executing instructions may include running the instructions, converting the instructions, compiling the instructions, and/or interpreting the instructions, among other examples.

In some aspects, the UE 120 includes means for receiving a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; means for receiving a communication; and/or means for transmitting the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration. The means for the UE 120 to perform operations described herein may include, for example, one or more of communication manager 140, antenna 252, modem 254, MIMO detector 256, receive processor 258, transmit processor 264, TX MIMO processor 266, controller/processor 280, or memory 282.

In some aspects, the network node 110 includes means for transmitting a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; means for receiving a transmission including the pilot symbol; means for performing a first channel estimation on the transmission; means for identifying the ACK or NACK feedback in accordance with the first channel estimation; and/or means for performing a second channel estimation on the transmission using the ACK or NACK feedback. The means for the network node 110 to perform operations described herein may include, for example, one or more of communication manager 150, transmit processor 214, TX MIMO processor 216, modem 232, antenna 234, MIMO detector 236, receive processor 238, controller/processor 240, memory 242, or scheduler 246.

FIGS. 4A, 4B, 4C, and 4D depict aspects of data structures for a wireless communications network, such as wireless communications network 100 of FIG. 1, in accordance with the present disclosure. FIG. 4A is a diagram 400 illustrating an example of a first subframe within a frame structure (such as for 5G communication), FIG. 4B is a diagram 430 illustrating an example of DL channels within a subframe, FIG. 4C is a diagram 450 illustrating an example of a second subframe within a frame structure, and FIG. 4D is a diagram 480 illustrating an example of UL channels within a subframe.

A wireless communications frame structure may be frequency division duplex, in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either downlink (DL) or uplink (UL). Wireless communications frame structures may also be time division duplex (TDD), in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.

As depicted in FIGS. 4A, 4B, 4C, and 4D, 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 across, for example, 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs), where a resource element comprises a subcarrier and an OFDM symbol. The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry reference (pilot) signals (RSs) for a UE (e.g., UE 120). The RSs may include DMRSs and/or CSI-RSs for channel estimation at the UE. The RSs may also include beam measurement RSs (BRSs), beam refinement RSs (BRRSs), and/or phase tracking RSs (PT-RSs). An RE carrying an RS may be referred to as a reference signal resource.

FIG. 4B illustrates an example of various DL channels within a subframe of a frame. The PDCCH carries DCI within one or more control channel elements (CCEs), each CCE including, for example, nine RE groups (REGs), each REG including, for example, four consecutive REs in an OFDM symbol.

A PSS may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., UE 120) to determine subframe/symbol timing and a physical layer identity.

As illustrated in FIG. 4C, some of the REs carry DMRSs (indicated as “R” for one particular configuration, but other DMRS configurations are possible) for channel estimation at the base station. The UE may transmit DMRSs for the PUCCH and DMRSs for the PUSCH. The PUSCH DMRSs may be transmitted, for example, in the first one or two symbols of the PUSCH. The PUCCH DMRSs may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. UE 120 may transmit SRSs. The SRSs may be transmitted, for example, in the last symbol of a subframe. The SRSs may have a comb structure, and a UE may transmit SRSs on one of the combs. Unused REs of the last symbol of the subframe may carry no data and may be referred to herein as blank resources. The SRSs may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL. In some aspects, a DMRS may be transmitted with one or more blank resources.

As indicated above, FIGS. 4A-4D are provided as examples. Other examples may differ from what is described with regard to FIGS. 4A-4D.

FIG. 5 is a diagram illustrating an example 500 of signaling for data-aided ACK/NACK feedback in a pilot symbol, in accordance with the present disclosure. Example 500 includes a UE 120 and a network node 110.

As shown, the network node 110 may transmit, and the UE 120 may receive, a configuration 510 associated with transmitting ACK/NACK feedback in a pilot symbol. The pilot symbol may be configured for transmission of an RS, such as a DMRS, an SRS, a PT-RS, or another form of RS, such as an RS described with regard to FIGS. 4A-4D. The configuration 510 may be associated with transmitting the ACK/NACK feedback in that the configuration 510 may indicate whether to transmit the ACK/NACK feedback (such as whether the ACK/NACK feedback should be provided in the pilot symbol or via a PUCCH). Additionally, or alternatively, the configuration 510 may be associated with transmitting the ACK/NACK feedback in that the configuration 510 may indicate one or more parameters for transmitting the ACK/NACK feedback, as described below. In some aspects, the network node 110 may transmit the configuration 510 via radio resource control signaling, a physical downlink control channel (PDCCH), or another form of signaling.

In some aspects, the configuration 510 may indicate whether to transmit the ACK/NACK feedback (such as whether the ACK/NACK feedback should be provided in the pilot symbol or via a PUCCH). For example, the network node 110 may determine whether the UE 120 is to transmit the ACK/NACK feedback in the pilot symbol or via the PUCCH. In some aspects, the network node 110 may perform this determination based on a channel metric, such as a channel condition (e.g., an uplink signal to noise ratio (SNR)) or a quality metric (e.g., a mutual information parameter). For example, the network node 110 may determine whether the channel metric satisfies a threshold (for example, a threshold indicating satisfactory uplink channel conditions). If the channel metric satisfies the threshold, the configuration 510 may indicate to transmit the ACK/NACK feedback in the pilot symbol. If the channel metric does not satisfy the threshold, the configuration 510 may indicate to transmit the ACK/NACK feedback via the PUCCH. In some examples, the threshold may be based on a type of modulation used for the ACK/NACK feedback. In some aspects, the threshold may be approximately 6 dB uplink SNR, such as for a quadrature phase shift keying (QPSK) modulation scheme. In some aspects, the network node 110 may select the threshold, such as according to a requirement of the network node 110 for demodulation of the ACK/NACK feedback. In some aspects, the channel metric may include, for example, a mutual information capacity of a bandwidth allocated for the pilot symbol in which the ACK/NACK feedback may be provided. In some aspects, the configuration 510 may indicate that a first set of ACK/NACK feedback is to be provided in the pilot symbol and a second set of ACK/NACK feedback is to be provided in the PUCCH. For example, the network node 110 may determine to provide part of the ACK/NACK feedback in the pilot symbol and part of the ACK/NACK feedback via the PUCCH.

In some aspects, the configuration 510 may indicate one or more parameters for transmitting the ACK/NACK feedback. For example, the configuration 510 may indicate a set of resources for the ACK/NACK feedback. For example, the configuration 510 may indicate that the UE 120 is to transmit the ACK/NACK feedback in one or more blank resources of the pilot symbol, such that the ACK/NACK feedback is multiplexed with RS resources of the pilot symbol, as illustrated in FIG. 6. As another example, the configuration 510 may indicate that the UE 120 is to transmit the ACK/NACK feedback on one or more data subcarriers of the pilot symbol, such as by replacing an RS in one or more RS resources with the ACK/NACK feedback, as also illustrated in FIG. 6. As another example, the configuration 510 may indicate one or more particular subcarriers on which to transmit the ACK/NACK feedback. For example, the one or more particular subcarriers may be associated with a channel condition metric (such as an SNR or another channel condition) that satisfies a threshold. As another example, the configuration 510 may indicate a particular pilot symbol or a particular type of reference signal to carry the ACK/NACK feedback. As another example, the configuration 510 may indicate a modulation order for the ACK/NACK feedback, such as a modulation and coding scheme (MCS). Thus, the configuration may be associated with a channel condition or a quality metric of the network node 110.

In some aspects, the configuration 510 may include an identifier that indicates the one or more parameters and/or whether the UE 120 is to provide the ACK/NACK feedback in the pilot symbol. For example, the UE 120 and/or the network node 110 may be configured with a codebook. The codebook may indicate a plurality of configurations 510. Each configuration 510 may be associated with an identifier, such as an index. The network node 110 may transmit, to the UE 120, an indication of a selected identifier corresponding to a configuration 510 of the plurality of configurations 510. The UE 120 may use the indicated configuration 510 to transmit ACK/NACK feedback.

In some aspects, the configuration 510 may be an initial configuration 510, such as associated with activating a feature for the ACK/NACK feedback in the pilot symbol. In some aspects, the configuration 510 may update one or more aspects of the ACK/NACK feedback, such as whether to provide the ACK/NACK feedback in the pilot symbol or via the PUCCH, or the one or more parameters described above. For example, the network node 110 may transmit a configuration 510 each time the one or more parameters, or whether to provide the ACK/NACK feedback via the PUCCH or in the pilot symbol, changes.

As shown, the network node 110 may transmit, and the UE 120 may receive, a communication 520. The communication 520 may include any form of downlink communication. The network node 110 may transmit the communication 520 in a slot. The UE 120 may demodulate the communication 520 (e.g., the downlink slot) and may decode data of the communication 520. For example, the UE 120 may decode one or more code blocks or CBGs of the communication 520.

The UE 120 may generate ACK/NACK feedback regarding the communication 520. For example, the UE 120 may generate (e.g., configure) a number of ACK/NACK indications of the ACK/NACK feedback. In some aspects, each ACK/NACK indication of the number of ACK/NACK indications may correspond to a different CBG of the communication 520. In some aspects, the ACK/NACK feedback may include a single ACK/NACK indication for the communication 520, such as a TB of the communication 520.

As shown, the UE 120 may transmit, and the network node 110 may receive, ACK/NACK feedback 530. For example, the UE 120 may transmit a transmission that includes an RS in the pilot symbol, as well as the ACK/NACK feedback 530 in the pilot symbol. The ACK/NACK feedback 530 may include a number of ACK/NACK indications, such as an ACK/NACK indication per CBG of the communication 520 or an ACK/NACK indication for the communication 520. In example 500, the UE 120 may transmit the ACK/NACK feedback 530 in a pilot symbol indicated by the configuration 510 and/or using the one or more parameters indicated by the configuration 510. In some other examples, the UE 120 may transmit the ACK/NACK feedback 530 via a PUCCH.

In some aspects, the UE 120 may modulate the ACK/NACK feedback 530. For example, the UE 120 may modulate the ACK/NACK feedback 530 using a modulation order indicated by the configuration 510. The modulation order may include, for example, QPSK, 16 quadrature amplitude modulation (16QAM), or another form of modulation order. In some aspects, the modulation order may be selected to provide a threshold robustness for the ACK/NACK feedback 530. For example, QPSK or 16QAM may be considered more robust or reliable than higher-order modulation schemes such as 64QAM or 256QAM, and providing the ACK/NACK feedback 530 using QPSK or 16QAM may improve reliability of demodulating the ACK/NACK feedback 530. This may be particularly beneficial where RSs are transmitted in poor channel conditions, which may be sometimes be expected because RSs can be triggered to determine channel conditions.

As an example of modulating the ACK/NACK feedback 530 using QPSK, the UE 120 may fail to receive a third CBG and an eighth CBG of a ten-CBG communication 520. In this example, the ACK/NACK feedback 530 may be represented as a vector of binary ACK/NACK indications [1 1 0 1 1 1 1 0 1 1], where “1” represents a successfully-received CBG and “0” represents an unsuccessfully received CBG (such as due to a decoding failure). A QPSK constellation may include four symbols, each corresponding to a two-digit binary value. The UE 120 may identify five symbols corresponding to two-digit binary values [11], [01], [11], [10], and [11], and may modulate the five symbols into the pilot symbol. Thus, reliability of the ACK/NACK feedback 530 is improved while reducing overhead of the ACK/NACK feedback 530.

In some aspects, the UE 120 may encode the ACK/NACK feedback 530. For example, the UE 120 may add a protecting code to the ACK/NACK feedback 530, which may increase robustness of the ACK/NACK feedback 530 and/or provide error protection for the ACK/NACK feedback 530.

The UE 120 may transmit the ACK/NACK feedback 530 in a pilot symbol. Examples of resources on which the ACK/NACK feedback 530 may be modulated and/or transmitted are provided in connection with FIG. 6.

As shown, the network node 110 may receive the ACK/NACK feedback 530. As shown, the network node 110 may perform channel estimation 540 (such as a first channel estimation and a second channel estimation) on a transmission that includes the ACK/NACK feedback 530. The channel estimation 540 is described in more detail in connection with FIG. 7.

FIG. 6 is a diagram illustrating examples 600, 605, and 610 of resources of a pilot symbol 615, 620, or 625, in accordance with the present disclosure. In examples 600, 605, and 610, data subcarriers 630 may be subcarriers on which a UE 120 transmits an RS, which may be referred to as a known pilot. Blank subcarriers 635 may be subcarriers on which a UE 120 transmits no communication, such as an empty subcarrier or a non-allocated subcarrier. Feedback subcarriers 640 may be subcarriers on which a UE 120 transmits ACK/NACK feedback, such as ACK/NACK feedback 530. Pilot symbols 615/620/625 may each include an OFDM symbol or multiple OFDM symbols.

In example 600, no ACK/NACK feedback is transmitted in the pilot symbol 615. For example, the pilot symbol 615 may include a number of data subcarriers 630 and blank subcarriers 635 multiplexed with one another in frequency.

In example 605, a set of feedback subcarriers 640 are multiplexed with a set of data subcarriers 630 in the pilot symbol 620. For example, in example 605, the UE 120 may provide ACK/NACK feedback in subcarriers that were configured, in example 600, as blank subcarriers 635. Multiplexing the set of feedback subcarriers 640 with the set of data subcarriers 630 may provide ACK/NACK indication without degrading spectral efficiency or channel estimation quality. Furthermore, multiplexing the set of feedback subcarriers 640 with the set of data subcarriers 630 may improve channel estimation accuracy when implemented in conjunction with data-aided channel estimation, as described in connection with FIG. 7.

In example 610, a set of feedback subcarriers 640 are multiplexed with a set of data subcarriers 630 and a set of blank subcarriers 635 in the pilot symbol 625. For example, the set of feedback subcarriers 640 may replace one or more data subcarriers 630 from example 600. This approach may provide for ACK/NACK feedback transmission in the pilot symbol 625 in a situation where one or more subcarriers are used as blank subcarriers, such as to prevent collision with other uplink transmissions.

A configuration (such as the configuration 510) may indicate whether to provide the ACK/NACK feedback in accordance with example 605 or example 610. Additionally, or alternatively, the configuration may indicate particular subcarriers on which to transmit the ACK/NACK feedback.

The resource allocations of examples 600, 605, and 610 are provided as examples. Other examples may differ from what is described with regard to examples 600, 605, or 610. For example, the set of feedback subcarriers 640 of example 610 may be provided on different subcarriers than those illustrated in example 610.

FIG. 7 is a diagram illustrating an example 700 of data-aided channel estimation using ACK/NACK feedback, in accordance with the present disclosure. Example 700 illustrates a number of modules of a network node 110, such as the network node 110 of FIG. 5. For example, the operations of example 700 may be performed by the network node 110. As shown, example 700 includes a Fast Fourier Transform (FFT) module 705, a channel estimation (CHEST) module 710, a CHEST interpolation module 715, an ACK/NACK data demodulation module 720, and a hard slicer module 725.

The network node 110 may receive a transmission including a pilot symbol (such as the pilot symbol 620 or 625). As shown by reference number 730, the network node 110 may extract the pilot symbol (shown as “TD pilot”, meaning time-domain pilot) from the transmission. The FFT module 705 may perform an FFT on the pilot symbol.

As shown by reference number 735, the network node 110 may provide the transformed pilot symbol to the CHEST module 710. The CHEST module 710 may perform a first channel estimation on the transformed pilot symbol. For example, the CHEST module 710 may receive, as input, the transformed pilot symbol. The CHEST module 710 may compare the transformed pilot symbol (referred to as an observed pilot) and known data of the pilot symbol (such as a configuration of data subcarriers 630 in the pilot symbol, which may be configured by the network node 110 prior to receiving the pilot symbol) to estimate an uplink channel. The CHEST module 710 may use any channel estimation algorithm to perform channel estimation, such as a pilot-based estimation, a least squares estimation, a linear interpolation, a minimum mean square error (MMSE) estimation, a combination thereof, or another form of channel estimation.

As shown, the CHEST interpolation module 715 may perform CHEST interpolation. CHEST interpolation may include evaluating the channel at feedback subcarriers (e.g., feedback subcarrier 640) of the pilot symbol and/or at blank subcarriers (e.g., blank subcarriers 635) of the pilot symbol. In CHEST interpolation, the network node 110 may use channel estimation values determined for the data subcarriers of the pilot symbol to interpolate channel estimation values for the feedback subcarriers and/or blank subcarriers. The network node 110 may use any suitable interpolation technique at the CHEST interpolation module 715.

As shown by reference number 740, in some aspects, the CHEST interpolation module 715 may provide the result of the first channel estimation to the ACK/NACK data demodulation module 720. The ACK/NACK data demodulation module 720 may demodulate ACK/NACK feedback from feedback subcarriers (e.g., feedback subcarriers 640) of the pilot symbol. For example, the ACK/NACK data demodulation module 720 may use the result of the first channel estimation (including interpolated channel estimation values corresponding to the feedback subcarriers) to identify or estimate constellation points received in the pilot symbol, which is referred to as demodulating the ACK/NACK feedback. As mentioned elsewhere herein, the ACK/NACK feedback may be modulated according to a modulation scheme, which may be configured by the network node 110 prior to receiving the pilot symbol. The network node 110 may demodulate the ACK/NACK feedback according to the modulation scheme. In some aspects, the network node 110 may decode the ACK/NACK feedback, such as according to a protecting code used to encode the ACK/NACK feedback.

As shown, the ACK/NACK data demodulation module 720 may provide the demodulated ACK/NACK feedback to the hard slicer module 725. The hard slicer module 725 may perform slicing of the demodulated ACK/NACK feedback. For example, the hard slicer module 725 may perform hard slicing. Hard slicing may include reconstructing a perfect transmitted constellation point of the ACK/NACK feedback. For example, the ACK/NACK data demodulation module 720 may provide an estimate of a constellation point, and the hard slicer module 725 may identify a transmitted constellation point corresponding to the estimate of the constellation point. The usage of the hard slicer module 725 may be facilitated by usage of a lower-order modulation constellation for the ACK/NACK feedback, as described elsewhere herein. In some aspects, a hard slicer may be referred to as a hard-decision demodulator or a hard demodulator.

As shown by reference number 745, the hard slicer module 725 may provide the ACK/NACK feedback, such as an indication of transmitted constellation points of the ACK/NACK feedback, to the CHEST module 710. The CHEST module 710 may perform a second channel estimation using the ACK/NACK feedback. For example, the CHEST module 710 may perform the second channel estimation using both the ACK/NACK feedback (such as the transmitted constellation point(s) of the ACK/NACK feedback) and the received RS of the pilot symbol as the known data of the pilot symbol. Thus, in the second channel estimation, the network node 110 has additional information regarding received information of the pilot symbol relative to the first channel estimation. This leads to a refined channel estimation value relative to performing only the first channel estimation.

As shown by reference number 750, in some aspects, the CHEST module 710, the CHEST interpolation module 715, the ACK/NACK data demodulation module 720, the hard slicer module 725, or a combination thereof, may iteratively perform channel estimation. For example, the CHEST module 710 may repeatedly perform channel estimation using the ACK/NACK feedback and the known data of the pilot symbol. In some aspects, the CHEST module 710 may perform a fixed number of iterations of the channel estimation. In some other aspects, the CHEST module 710 may perform a number of iterations in accordance with a threshold. For example, the CHEST module 710 may iteratively perform channel estimation until an error associated with the channel estimation is lower than a threshold. For example, the error may be defined as error=E{yk−Ĥkxk}, where E{⋅} is the expectation operator, k is the frequency domain index, and y, Ĥ, and x are the received signal, the estimated CHEST, and the transmitted signal, respectively.

As shown by reference number 755, the network node 110 may identify the ACK/NACK feedback. As shown by reference number 760, the network node 110 may identify a channel estimation value output by the CHEST module 710. For example, the network node 110 may determine the ACK/NACK feedback at the hard slicer module 725, and may demodulate constellation points of the ACK/NACK feedback to obtain a set of ACK/NACK indications of the ACK/NACK feedback. The network node 110 may also determine the channel estimation value. For example, the channel estimation value may include a last (final) output of the CHEST module 710, such as after performing the second channel estimation or performing a number of iterations of channel estimation. The network node 110 may communicate using the ACK/NACK feedback. For example, the network node 110 may retransmit one or more CBGs or a TB indicated as missed by an ACK/NACK indication of the ACK/NACK feedback.

As indicated above, FIG. 7 is provided as an example. Other examples may differ from what was described with regard to FIG. 7.

FIG. 8 is a diagram illustrating an example process 800 performed, for example, at a UE or an apparatus of a UE, in accordance with the present disclosure. Example process 800 is an example where the apparatus or the UE (e.g., UE 120) performs operations associated with techniques for providing feedback in a pilot symbol.

As shown in FIG. 8, in some aspects, process 800 may include receiving a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal (block 810). For example, the UE (e.g., using reception component 1002 and/or communication manager 1006, depicted in FIG. 10) may receive a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal, as described above.

As further shown in FIG. 8, in some aspects, process 800 may include receiving a communication (block 820). For example, the UE (e.g., using reception component 1002 and/or communication manager 1006, depicted in FIG. 10) may receive a communication, as described above.

As further shown in FIG. 8, in some aspects, process 800 may include transmitting the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration (block 830). For example, the UE (e.g., using transmission component 1004 and/or communication manager 1006, depicted in FIG. 10) may transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration, as described above.

In a first aspect, the ACK or NACK feedback includes feedback relating to multiple code block groups.

In a second aspect, alone or in combination with the first aspect, transmitting the ACK or NACK feedback regarding the communication further comprises transmitting the ACK or NACK feedback in accordance with a set of constellation symbols, wherein the set of constellation symbols are associated with the ACK or NACK feedback relating to the multiple code block groups.

In a third aspect, alone or in combination with one or more of the first and second aspects, the ACK or NACK feedback is multiplexed with data subcarriers in the pilot symbol.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, transmitting the ACK or NACK feedback further comprises transmitting the ACK or NACK feedback on one or more data subcarriers in the pilot symbol.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the configuration indicates a set of subcarriers on which the ACK or NACK feedback is to be transmitted.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the configuration indicates whether the ACK or NACK feedback should be provided in the pilot symbol or via a control channel.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the pilot symbol comprises at least one of a demodulation reference signal symbol or a sounding reference signal symbol.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the ACK or NACK feedback comprises a set of bits and a code.

Although FIG. 8 shows example blocks of process 800, in some aspects, process 800 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 8. Additionally, or alternatively, two or more of the blocks of process 800 may be performed in parallel.

FIG. 9 is a diagram illustrating an example process 900 performed, for example, at a network node or an apparatus of a network node, in accordance with the present disclosure. Example process 900 is an example where the apparatus or the network node (e.g., network node 110) performs operations associated with techniques for providing feedback in a pilot symbol.

As shown in FIG. 9, in some aspects, process 900 may include transmitting a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal (block 910). For example, the network node (e.g., using transmission component 1104 and/or communication manager 1106, depicted in FIG. 11) may transmit a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal, as described above.

As further shown in FIG. 9, in some aspects, process 900 may include receiving a transmission including the pilot symbol (block 920). For example, the network node (e.g., using reception component 1102 and/or communication manager 1106, depicted in FIG. 11) may receive a transmission including the pilot symbol, as described above.

As further shown in FIG. 9, in some aspects, process 900 may include performing a first channel estimation on the transmission (block 930). For example, the network node (e.g., using communication manager 1106, depicted in FIG. 11) may perform a first channel estimation on the transmission, as described above.

As further shown in FIG. 9, in some aspects, process 900 may include identifying the ACK or NACK feedback in accordance with the first channel estimation (block 940). For example, the network node (e.g., using communication manager 1106, depicted in FIG. 11) may identify the ACK or NACK feedback in accordance with the first channel estimation, as described above.

As further shown in FIG. 9, in some aspects, process 900 may include performing a second channel estimation on the transmission using the ACK or NACK feedback (block 950). For example, the network node (e.g., using communication manager 1106, depicted in FIG. 11) may perform a second channel estimation on the transmission using the ACK or NACK feedback, as described above.

Process 900 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the configuration indicates at least one of whether the ACK or NACK feedback should be transmitted on a data subcarrier or a blank subcarrier of the pilot symbol, a resource of the pilot symbol, a set of subcarriers on which the ACK or NACK feedback is to be transmitted, a modulation order of the feedback, or whether the feedback should be provided in the pilot symbol or via a control channel.

In a second aspect, alone or in combination with the first aspect, the set of subcarriers are associated with a channel condition that satisfies a threshold.

In a third aspect, alone or in combination with one or more of the first and second aspects, the configuration is associated with a channel condition or a quality metric of the network node.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the configuration indicates a codebook entry that indicates the configuration.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the configuration indicates a modulation order, and the ACK or NACK feedback corresponds to a set of constellation points associated with the modulation order.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the ACK or NACK feedback includes multiple ACK or NACK indications relating to multiple code block groups, and the multiple ACK or NACK indications are mapped to the set of constellation points.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, identifying the ACK or NACK feedback comprises demodulating the ACK or NACK feedback using an output of the first channel estimation.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, performing the second channel estimation on the transmission using the ACK or NACK feedback comprises providing the ACK or NACK feedback as a known input in the second channel estimation.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, performing the second channel estimation on the transmission using the ACK or NACK feedback further comprises iteratively performing the second channel estimation.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, iteratively performing the second channel estimation comprises iteratively performing the second channel estimation until a threshold is satisfied.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, iteratively performing the second channel estimation comprises iteratively performing the second channel estimation for a number of iterations.

Although FIG. 9 shows example blocks of process 900, in some aspects, process 900 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in FIG. 9. Additionally, or alternatively, two or more of the blocks of process 900 may be performed in parallel.

FIG. 10 is a diagram of an example apparatus 1000 for wireless communication, in accordance with the present disclosure. The apparatus 1000 may be a UE, or a UE may include the apparatus 1000. In some aspects, the apparatus 1000 includes a reception component 1002, a transmission component 1004, and/or a communication manager 1006, which may be in communication with one another (for example, via one or more buses and/or one or more other components). In some aspects, the communication manager 1006 is the communication manager 140 described in connection with FIG. 1. As shown, the apparatus 1000 may communicate with another apparatus 1008, such as a UE or a network node (such as a CU, a DU, an RU, or a base station), using the reception component 1002 and the transmission component 1004.

In some aspects, the apparatus 1000 may be configured to perform one or more operations described herein in connection with FIGS. 4-7. Additionally, or alternatively, the apparatus 1000 may be configured to perform one or more processes described herein, such as process 800 of FIG. 8, or a combination thereof. In some aspects, the apparatus 1000 and/or one or more components shown in FIG. 10 may include one or more components of the UE described in connection with FIG. 2. Additionally, or alternatively, one or more components shown in FIG. 10 may be implemented within one or more components described in connection with FIG. 2. Additionally, or alternatively, one or more components of the set of components may be implemented at least in part as software stored in one or more memories. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by one or more controllers or one or more processors to perform the functions or operations of the component.

The transmission component 1004 may transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1008. In some aspects, one or more other components of the apparatus 1000 may generate communications and may provide the generated communications to the transmission component 1004 for transmission to the apparatus 1008. In some aspects, the transmission component 1004 may perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and may transmit the processed signals to the apparatus 1008. In some aspects, the transmission component 1004 may include one or more antennas, one or more modems, one or more modulators, one or more transmit MIMO processors, one or more transmit processors, one or more controllers/processors, one or more memories, or a combination thereof, of the UE described in connection with FIG. 2. In some aspects, the transmission component 1004 may be co-located with the reception component 1002 in one or more transceivers.

The communication manager 1006 may support operations of the reception component 1002 and/or the transmission component 1004. For example, the communication manager 1006 may receive information associated with configuring reception of communications by the reception component 1002 and/or transmission of communications by the transmission component 1004. Additionally, or alternatively, the communication manager 1006 may generate and/or provide control information to the reception component 1002 and/or the transmission component 1004 to control reception and/or transmission of communications.

The reception component 1002 may receive a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal. The reception component 1002 may receive a communication. The transmission component 1004 may transmit the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

The number and arrangement of components shown in FIG. 10 are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 10. Furthermore, two or more components shown in FIG. 10 may be implemented within a single component, or a single component shown in FIG. 10 may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown in FIG. 10 may perform one or more functions described as being performed by another set of components shown in FIG. 10.

FIG. 11 is a diagram of an example apparatus 1100 for wireless communication, in accordance with the present disclosure. The apparatus 1100 may be a network node, or a network node may include the apparatus 1100. In some aspects, the apparatus 1100 includes a reception component 1102, a transmission component 1104, and/or a communication manager 1106, which may be in communication with one another (for example, via one or more buses and/or one or more other components). In some aspects, the communication manager 1106 is the communication manager 150 described in connection with FIG. 1. As shown, the apparatus 1100 may communicate with another apparatus 1108, such as a UE or a network node (such as a CU, a DU, an RU, or a base station), using the reception component 1102 and the transmission component 1104.

In some aspects, the apparatus 1100 may be configured to perform one or more operations described herein in connection with FIGS. 4-7. Additionally, or alternatively, the apparatus 1100 may be configured to perform one or more processes described herein, such as process 900 of FIG. 9, or a combination thereof. In some aspects, the apparatus 1100 and/or one or more components shown in FIG. 11 may include one or more components of the network node described in connection with FIG. 2. Additionally, or alternatively, one or more components shown in FIG. 11 may be implemented within one or more components described in connection with FIG. 2. Additionally, or alternatively, one or more components of the set of components may be implemented at least in part as software stored in one or more memories. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by one or more controllers or one or more processors to perform the functions or operations of the component.

The reception component 1102 may receive communications, such as reference signals, control information, data communications, or a combination thereof, from the apparatus 1108. The reception component 1102 may provide received communications to one or more other components of the apparatus 1100. In some aspects, the reception component 1102 may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components of the apparatus 1100. In some aspects, the reception component 1102 may include one or more antennas, one or more modems, one or more demodulators, one or more MIMO detectors, one or more receive processors, one or more controllers/processors, one or more memories, or a combination thereof, of the network node described in connection with FIG. 2. In some aspects, the reception component 1102 and/or the transmission component 1104 may include or may be included in a network interface. The network interface may be configured to obtain and/or output signals for the apparatus 1100 via one or more communications links, such as a backhaul link, a midhaul link, and/or a fronthaul link.

The transmission component 1104 may transmit communications, such as reference signals, control information, data communications, or a combination thereof, to the apparatus 1108. In some aspects, one or more other components of the apparatus 1100 may generate communications and may provide the generated communications to the transmission component 1104 for transmission to the apparatus 1108. In some aspects, the transmission component 1104 may perform signal processing on the generated communications (such as filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, among other examples), and may transmit the processed signals to the apparatus 1108. In some aspects, the transmission component 1104 may include one or more antennas, one or more modems, one or more modulators, one or more transmit MIMO processors, one or more transmit processors, one or more controllers/processors, one or more memories, or a combination thereof, of the network node described in connection with FIG. 2. In some aspects, the transmission component 1104 may be co-located with the reception component 1102 in one or more transceivers.

The communication manager 1106 may support operations of the reception component 1102 and/or the transmission component 1104. For example, the communication manager 1106 may receive information associated with configuring reception of communications by the reception component 1102 and/or transmission of communications by the transmission component 1104. Additionally, or alternatively, the communication manager 1106 may generate and/or provide control information to the reception component 1102 and/or the transmission component 1104 to control reception and/or transmission of communications.

The transmission component 1104 may transmit a configuration associated with transmitting ACK or NACK feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal. The reception component 1102 may receive a transmission including the pilot symbol. The communication manager 1106 may perform a first channel estimation on the transmission. The communication manager 1106 may identify the ACK or NACK feedback in accordance with the first channel estimation. The communication manager 1106 may perform a second channel estimation on the transmission using the ACK or NACK feedback.

The number and arrangement of components shown in FIG. 11 are provided as an example. In practice, there may be additional components, fewer components, different components, or differently arranged components than those shown in FIG. 11. Furthermore, two or more components shown in FIG. 11 may be implemented within a single component, or a single component shown in FIG. 11 may be implemented as multiple, distributed components. Additionally, or alternatively, a set of (one or more) components shown in FIG. 11 may perform one or more functions described as being performed by another set of components shown in FIG. 11.

Aspect 1: A method of wireless communication performed by a user equipment (UE), comprising: receiving a configuration associated with transmitting acknowledgment (ACK) or negative ACK (NACK) feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receiving a communication; and transmitting the ACK or NACK feedback regarding the communication in the pilot symbol in accordance with the configuration.

Aspect 2: The method of Aspect 1, wherein the ACK or NACK feedback includes feedback relating to multiple code block groups.

Aspect 3: The method of Aspect 2, wherein transmitting the ACK or NACK feedback regarding the communication further comprises transmitting the ACK or NACK feedback in accordance with a set of constellation symbols, wherein the set of constellation symbols are associated with the ACK or NACK feedback relating to the multiple code block groups.

Aspect 4: The method of any of Aspects 1-3, wherein the ACK or NACK feedback is multiplexed with data subcarriers in the pilot symbol.

Aspect 5: The method of any of Aspects 1-4, wherein transmitting the ACK or NACK feedback further comprises transmitting the ACK or NACK feedback on one or more data subcarriers in the pilot symbol.

Aspect 6: The method of any of Aspects 1-5, wherein the configuration indicates a set of subcarriers on which the ACK or NACK feedback is to be transmitted.

Aspect 7: The method of any of Aspects 1-6, wherein the configuration indicates whether the ACK or NACK feedback should be provided in the pilot symbol or via a control channel.

Aspect 8: The method of any of Aspects 1-7, wherein the pilot symbol comprises at least one of a demodulation reference signal symbol or a sounding reference signal symbol.

Aspect 9: The method of any of Aspects 1-8, wherein the ACK or NACK feedback comprises a set of bits and a code.

Aspect 10: A method of wireless communication performed by a network node, comprising: transmitting a configuration associated with transmitting acknowledgment (ACK) or negative ACK (NACK) feedback in a pilot symbol, wherein the pilot symbol is associated with an uplink reference signal; receiving a transmission including the pilot symbol; performing a first channel estimation on the transmission; identifying the ACK or NACK feedback in accordance with the first channel estimation; and performing a second channel estimation on the transmission using the ACK or NACK feedback.

Aspect 11: The method of Aspect 10, wherein the configuration indicates at least one of: whether the ACK or NACK feedback should be transmitted on a data subcarrier or a blank subcarrier of the pilot symbol, a resource of the pilot symbol, a set of subcarriers on which the ACK or NACK feedback is to be transmitted, a modulation order of the feedback, or whether the feedback should be provided in the pilot symbol or via a control channel.

Aspect 12: The method of Aspect 11, wherein the set of subcarriers are associated with a channel condition that satisfies a threshold.

Aspect 13: The method of any of Aspects 10-12, wherein the configuration is associated with a channel condition or a quality metric of the network node.

Aspect 14: The method of any of Aspects 10-13, wherein the configuration indicates a codebook entry that indicates the configuration.

Aspect 15: The method of any of Aspects 10-14, wherein the configuration indicates a modulation order, and wherein the ACK or NACK feedback corresponds to a set of constellation points associated with the modulation order.

Aspect 16: The method of Aspect 15, wherein the ACK or NACK feedback includes multiple ACK or NACK indications relating to multiple code block groups, and wherein the multiple ACK or NACK indications are mapped to the set of constellation points.

Aspect 17: The method of any of Aspects 10-16, wherein identifying the ACK or NACK feedback comprises demodulating the ACK or NACK feedback using an output of the first channel estimation.

Aspect 18: The method of Aspect 17, wherein performing the second channel estimation on the transmission using the ACK or NACK feedback comprises providing the ACK or NACK feedback as a known input in the second channel estimation.

Aspect 19: The method of Aspect 17, wherein performing the second channel estimation on the transmission using the ACK or NACK feedback further comprises iteratively performing the second channel estimation.

Aspect 20: The method of Aspect 19, wherein iteratively performing the second channel estimation comprises iteratively performing the second channel estimation until a threshold is satisfied.

Aspect 21: The method of Aspect 19, wherein iteratively performing the second channel estimation comprises iteratively performing the second channel estimation for a number of iterations.

Aspect 24: An apparatus for wireless communication, the apparatus comprising at least one means for performing the method of one or more of Aspects 1-21.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software. As used herein, the phrase “based on” is intended to be broadly construed to mean “based at least in part on.” As used herein, “satisfying a threshold” may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or not equal to the threshold, among other examples. 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.

Also, as used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (for example, related items, unrelated items, or a combination of related and unrelated items), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” and similar terms are intended to be open-ended terms that do not limit an element that they modify (for example, an element “having” A also may have B). Further, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or,” unless explicitly stated otherwise (for example, if used in combination with “either” or “only one of”).

In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Aspects of the subject matter described in this specification also can be implemented as one or more computer programs (such as one or more modules of computer program instructions) encoded on a computer storage media for execution by, or to control the operation of, a data processing apparatus.

Various modifications to the aspects described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.