Patent Description:
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

For example, a fifth generation (<NUM>) wireless communications technology (which can be referred to as <NUM> new radio (<NUM> NR)) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, <NUM> communications technology can include services such as: enhanced mobile broadband (eMBB) addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, further improvements in <NUM> communications technology and beyond may be desired.

In <NUM>, the availability of unpaired spectrum in high frequency band has led to selection of time division duplexing (TDD) as a prominent deployment scenario for resource utilization. Dynamic TDD, which is similar to enhanced interference mitigation and traffic adaptation (eIMTA) in LTE, can provide additional flexibility for configuring resources, but may be limited due to cross-link interference (CLI) where a device served by one base station may transmit uplink communications that interfere with downlink communications from another base station (to another device) and/or where a base station may transmit downlink communications (to a device) that interfere with uplink communications from another device to another base station. Patent application <CIT> relates to mobile communications, wherein a reference signal period during which an uplink reference signal utilized in channel estimation is transmitted is partially set in downlink frequency f1. A user equipment transmits uplink reference signal to eNB by using the downlink frequency f1 during the reference signal period. The eNB receives the uplink reference signal from the UE by using the downlink frequency f1 during the reference signal period.

As defined by claim <NUM>, the invention provides a method for configuring reference signal transmission in wireless communications, for a first access point serving a user equipment, UE, the method comprising: receiving, from a second access point, an indication of resources over which at least one of a downlink reference signal is transmitted, or downlink interference measurement resource, IMR, is configured, by the second access point; and configuring the UE to transmit an uplink reference signal over the resources.

Preferred embodiments of the method of claim <NUM> are defined by claims <NUM> to <NUM>.

As defined by claim <NUM>, the invention provides an apparatus for wireless communication as a first access point serving a user equipment, UE, the apparatus comprising: a transceiver for communicating one or more wireless signals via at least a transmitter and one or more antennas; a memory configured to store instructions; and one or more processors communicatively coupled with the transceiver and the memory, wherein the one or more processors are configured to: receive, from a second access point, an indication of resources over which a downlink reference signal is transmitted, or downlink interference measurement resource, IMR, is configured, by the second access point; and configure the UE to transmit an uplink reference signal over the resources.

Preferred embodiments of the apparatus of claim <NUM> are defined by claims <NUM> to <NUM>.

The described features generally relate to scheduling transmission of uplink and downlink reference signals over similar resources (e.g., in frequency, time, and/or space) to facilitate cross-link interference (CLI) measurement and mitigation. For example, an access point can configure resources over which a user equipment (UE) is to transmit an uplink reference signal, where the resources can be at least partially used by another access point to transmit a downlink reference signal or configured as downlink interference measurement resources (IMR) (and/or configured for another UE to transmit another uplink reference signal). For example, in a time division duplexing (TDD) configuration where access points can configure time divisions (e.g., symbols within a slot) for either uplink or downlink communications, the access point may configure the UE to transmit the uplink reference signal in the same symbol of the slot (or other time division) that is used by a base station to transmit the downlink reference signal or configured as downlink IMR (and/or configured for another UE to transmit another uplink reference signal). In an example, the access point can receive an indication of the resources used by another base station to transmit the downlink reference signal, and can accordingly configure the UE to transmit the uplink reference signal over the same resource (e.g., at least the same time resources). The access point may configure the UE to transmit the uplink reference signal orthogonally (e.g., in frequency and/or space) to the downlink reference signal within the symbol.

A served UE that receives the downlink reference signal and the uplink reference signal (e.g., based on CLI), for example, can report, to the serving access point, measurements related to the reference signals. In this example, the access point can accordingly perform interference-aware coordinated scheduling of resources for the served UE. The served UE may be unaware that the uplink reference signal is indeed an uplink signal from another UE, and may report the uplink reference signal as a downlink reference signal (e.g., using a procedure defined for reporting downlink reference signal measurements), which may include reporting the uplink reference signal as corresponding to a different antenna port of a base station. In another example, the UE may combine the uplink reference signal measurement with the downlink reference signal (e.g., when the reference signals are transmitted in the same symbol). In any case, the access point can categorize an interference measurement report received from the served UE into downlink and/or CLI uplink, and can accordingly use the reported interference in scheduling the served UE. In another example, the served UE may be capable of separating the uplink reference signal from the downlink reference signal over the resources, and may accordingly separately report interference measurements for these signals to the serving access point.

In an example, using a mechanism such as that described above may be beneficial in wireless networks that have more availability of unpaired spectrum in high frequency band where time division duplexing (TDD) can be of increased importance (e.g., such as fifth generation (<NUM>) new radio (NR). In such networks, dynamic TDD with CLI mitigation may provide a performance gain over static TDD or dynamic TDD without CLI mitigation. Fast and accurate CLI measurements can enable CLI mitigation in dynamic TDD as well. In this regard, downlink and uplink reference signals and/or measurement procedures can be jointly designed for efficient CLI measurement and reporting, as described above and further herein.

As used in this application, the terms "component," "module," "system" and the like are intended to include a computer-related entity, such as but not limited to hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components can communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets, such as data from one component interacting with another component in a local system, distributed system, and/or across a network such as the Internet with other systems by way of the signal.

Techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" may often be used interchangeably. IS-<NUM> Releases <NUM> and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-<NUM> (TIA-<NUM>) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM™, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). The techniques described herein may be used for the systems and radio technologies mentioned above as well as other systems and radio technologies, including cellular (e.g., LTE) communications over a shared radio frequency spectrum band. The description below, however, describes an LTE/LTE-A system for purposes of example, and LTE terminology is used in much of the description below, although the techniques are applicable beyond LTE/LTE-A applications (e.g., to <NUM> networks or other next generation communication systems).

<FIG> illustrates an example of a wireless communication system <NUM> in accordance with various aspects of the present disclosure. The wireless communication system <NUM> may include one or more base stations <NUM>, one or more UEs <NUM>, and a core network <NUM>. The core network <NUM> may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations <NUM> may interface with the core network <NUM> through backhaul links <NUM> (e.g., S1, etc.). The base stations <NUM> may perform radio configuration and scheduling for communication with the UEs <NUM>, or may operate under the control of a base station controller (not shown). In various examples, the base stations <NUM> may communicate, either directly or indirectly (e.g., through core network <NUM>), with one another over backhaul links <NUM> (e.g., X2, etc.), which may be wired or wireless communication links.

The base stations <NUM> may wirelessly communicate with the UEs <NUM> via one or more base station antennas. In some examples, base stations <NUM> may be referred to as a network entity, a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, or some other suitable terminology. The geographic coverage area <NUM> for a base station <NUM> may be divided into sectors making up only a portion of the coverage area (not shown). The wireless communication system <NUM> may include base stations <NUM> of different types (e.g., macro or small cell base stations). There may be overlapping geographic coverage areas <NUM> for different technologies.

In some examples, the wireless communication system <NUM> may be or include a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) network. The wireless communication system <NUM> may also be a next generation network, such as a <NUM> wireless communication network. In LTE/LTE-A networks, the term evolved node B (eNB), gNB, etc. may be generally used to describe the base stations <NUM>, while the term UE may be generally used to describe the UEs <NUM>. The wireless communication system <NUM> may be a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station <NUM> may provide communication coverage for a macro cell, a small cell, or other types of cell. The term "cell" is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs <NUM> with service subscriptions with the network provider.

A small cell may include a lower-powered base station, as compared with a macro cell, that may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macro cells. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by the UEs <NUM> with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by the UEs <NUM> having an association with the femto cell (e.g., UEs <NUM> in a closed subscriber group (CSG), UEs <NUM> for users in the home, and the like). An eNB for a macro cell may be referred to as a macro eNB, gNB, etc. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB.

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A packet data convergence protocol (PDCP) layer can provide header compression, ciphering, integrity protection, etc. of IP packets. A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use HARQ to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE <NUM> and the base stations <NUM>. The RRC protocol layer may also be used for core network <NUM> support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs <NUM> may be dispersed throughout the wireless communication system <NUM>, and each UE <NUM> may be stationary or mobile. A UE <NUM> may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE <NUM> may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, an entertainment device, a vehicular component, or the like. A UE may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

The communication links <NUM> shown in wireless communication system <NUM> may carry uplink (UL) transmissions from a UE <NUM> to a base station <NUM>, or downlink (DL) transmissions, from a base station <NUM> to a UE <NUM>. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each communication link <NUM> may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. The communication links <NUM> may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Frame structures may be defined for FDD (e.g., frame structure type <NUM>) and TDD (e.g., frame structure type <NUM>).

In aspects of the wireless communication system <NUM>, base stations <NUM> or UEs <NUM> may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between the base stations <NUM> and UEs <NUM>. Additionally or alternatively, the base stations <NUM> or UEs <NUM> may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

Wireless communication system <NUM> may support operation on multiple cells or carriers, a feature which may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may also be referred to as a component carrier (CC), a layer, a channel, etc. The terms "carrier," "component carrier," "cell," and "channel" may be used interchangeably herein. A UE <NUM> may be configured with multiple downlink CCs and one or more uplink CCs for carrier aggregation.

In an example, base station <NUM>-a and UE <NUM>-a may communicate using communication link <NUM>-a, which may be configured with TDD resources. In addition, for example, base station <NUM>-b and UE <NUM>-b may communicate using communication link <NUM>-b, which may also be configured with TDD resources, though the resource configuration for communication link <NUM>-a and <NUM>-b may be different in a given time division (e.g., in a given symbol of a slot). In an example, however, the resources for communication link <NUM>-a and <NUM>-b may generally be symbol-aligned and/or slotaligned in time, but a given symbol (or other time division) for communication link <NUM>-a may be configured for uplink communications while the same symbol (or other time division) for communication link <NUM>-b may be configured for downlink communications. Accordingly, in this example, UE <NUM>-b transmitting in resources over communication link <NUM>-b may interfere with downlink transmissions from base station <NUM>-a over communication link <NUM>-a in the symbol or other time division (e.g., as received by UE <NUM>-a). In addition, for example, base station <NUM>-a transmitting in resources over communication link <NUM>-a may interfere with uplink transmission from the UE <NUM>-b over communication link <NUM>-b in the symbol or other time division (e.g., as received by base station <NUM>-b). These two interference scenarios can be referred to as CLI.

In an attempt to address CLI, a base station <NUM> may include a scheduling component <NUM> for scheduling resources to one or more UEs for transmitting an uplink reference signal, determining reported interference (e.g., from a different UE) based at least in part on uplink reference signals, determining interference from downlink reference signals transmitted by other base stations, and/or the like. In another example, a UE <NUM> can include a communicating component <NUM> configured to transmit an uplink reference signal over resources configured by the access point, report channel state information (CSI) based on a downlink reference signal, report interference from an uplink reference signal, and/or the like.

Turning now to <FIG>, aspects are depicted with reference to one or more components and one or more methods that may perform the actions or operations described herein, where aspects in dashed line may be optional. Although the operations described below in <FIG> are presented in a particular order and/or as being performed by an example component, it should be understood that the ordering of the actions and the components performing the actions may be varied, depending on the implementation. Moreover, it should be understood that the following actions, functions, and/or described components may be performed by a specially-programmed processor, a processor executing specially-programmed software or computer-readable media, or by any other combination of a hardware component and/or a software component capable of performing the described actions or functions.

Referring to <FIG>, a block diagram <NUM> is shown that includes a portion of a wireless communications system having multiple UEs <NUM> in communication with a base station <NUM> via communication links <NUM>, where the base station <NUM> is also communicatively coupled with a network <NUM>. The UEs <NUM> may be examples of the UEs described in the present disclosure that are configured to receive RS configurations and/or resources over which to communicate with a base station. Moreover the base station <NUM> may be an example of the base stations described in the present disclosure (e.g., eNB, gNB, etc.) that are configured to transmit RS configurations and/or schedule UEs for communicating with the base station.

In an aspect, the base station in <FIG> may include one or more processors <NUM> and/or memory <NUM> that may operate in combination with a scheduling component <NUM> to perform the functions, methodologies (e.g., method <NUM> of <FIG>, method <NUM> of <FIG>), or other methods presented in the present disclosure, which may include scheduling communication resources for one or more UEs <NUM>. In accordance with the present disclosure, the scheduling component <NUM> may include a downlink (DL) reference signal (RS) determining component <NUM> for determining resources over which a DL RS is transmitted, and/or an uplink (UL) RS assigning component <NUM> for assigning resources over which a UE is to transmit a UL RS.

The one or more processors <NUM> may include a modem <NUM> that uses one or more modem processors. The various functions related to the scheduling component <NUM>, and/or sub-components thereof, may be included in modem <NUM> and/or processor <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a transceiver processor associated with transceiver <NUM>, or a system-on-chip (SoC). In particular, the one or more processors <NUM> may execute functions and components included in the scheduling component <NUM>.

In some examples, the scheduling component <NUM> and each of the sub-components may comprise hardware, firmware, and/or software and may be configured to execute code or perform instructions stored in a memory (e.g., a computer-readable storage medium, such as memory <NUM> discussed below). Moreover, in an aspect, the base station <NUM> in <FIG> may include a radio frequency (RF) front end <NUM> and transceiver <NUM> for receiving and transmitting radio transmissions to, for example, UEs <NUM>. The transceiver <NUM> may coordinate with the modem <NUM> to receive signals for, or transmit signals generated by, the scheduling component <NUM> to the UEs <NUM>. The RF front end <NUM> may be communicatively coupled with one or more antennas <NUM> and can include one or more switches <NUM>, one or more amplifiers (e.g., power amplifiers (PAs) <NUM> and/or low-noise amplifiers <NUM>), and one or more filters <NUM> for transmitting and receiving RF signals on uplink channels and downlink channels. In an aspect, the components of the RF front end <NUM> can be communicatively coupled with transceiver <NUM>. The transceiver <NUM> may be communicatively coupled with the one or more of modem <NUM> and processors <NUM>.

The transceiver <NUM> may be configured to transmit (e.g., via transmitter (TX) radio <NUM>) and receive (e.g., via receiver (RX) radio <NUM>) wireless signals through antennas <NUM> via the RF front end <NUM>. In an aspect, the transceiver <NUM> may be tuned to operate at specified frequencies such that the base station <NUM> can communicate with, for example, UEs <NUM>. In an aspect, for example, the modem <NUM> can configure the transceiver <NUM> to operate at a specified frequency and power level based on the configuration of the base station <NUM> and communication protocol used by the modem <NUM>.

The base station <NUM> in <FIG> may further include a memory <NUM>, such as for storing data used herein and/or local versions of applications or scheduling component <NUM> and/or one or more of its sub-components being executed by processor <NUM>. Memory <NUM> can include any type of computer-readable medium usable by a computer or processor <NUM>, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory <NUM> may be a computer-readable storage medium that stores one or more computer-executable codes defining scheduling component <NUM> and/or one or more of its sub-components. Additionally or alternatively, the base station <NUM> may include a bus <NUM> for communicatively coupling one or more of the RF front end <NUM>, the transceiver <NUM>, the memory <NUM>, or the processor <NUM>, and to exchange signaling information between each of the components and/or sub-components of the base station <NUM>.

In an aspect, the UE <NUM> in <FIG> may include one or more processors <NUM> and/or memory <NUM> that may operate in combination with a communicating component <NUM> to perform the functions, methodologies (e.g., method <NUM> of <FIG>, method <NUM> of <FIG>), or other methods presented in the present disclosure. In accordance with the present disclosure, the communicating component <NUM> may include a RS measuring component <NUM> for measuring at least a DL RS transmitted by an access point and/or interference from one or more UL RSs transmitted over at least a portion of the same resources as the DL RS, and/or an interference reporting component <NUM> for reporting the measured DL RS and/or associated interference from UL RS.

The one or more processors <NUM> may include a modem <NUM> that uses one or more modem processors. The various functions related to the communicating component <NUM>, and/or its sub-components, may be included in modem <NUM> and/or processor <NUM> and, in an aspect, can be executed by a single processor, while in other aspects, different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors <NUM> may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a transceiver processor associated with transceiver <NUM>, or a system-on-chip (SoC). In particular, the one or more processors <NUM> may execute functions and components included in the communicating component <NUM>.

In some examples, the communicating component <NUM> and each of the sub-components may comprise hardware, firmware, and/or software and may be configured to execute code or perform instructions stored in a memory (e.g., a computer-readable storage medium, such as memory <NUM> discussed below). Moreover, in an aspect, the UE <NUM> in <FIG> may include an RF front end <NUM> and transceiver <NUM> for receiving and transmitting radio transmissions to, for example, base stations <NUM>. The transceiver <NUM> may coordinate with the modem <NUM> to receive signals that include the packets as received by the communicating component <NUM>. The RF front end <NUM> may be communicatively coupled with one or more antennas <NUM> and can include one or more switches <NUM>, one or more amplifiers (e.g., PAs <NUM> and/or LNAs <NUM>), and one or more filters <NUM> for transmitting and receiving RF signals on uplink channels and downlink channels. In an aspect, the components of the RF front end <NUM> can be communicatively coupled with transceiver <NUM>. The transceiver <NUM> may be communicatively coupled with one or more of modem <NUM> and processors <NUM>.

The transceiver <NUM> may be configured to transmit (e.g., via transmitter (TX) radio <NUM>) and receive (e.g., via receiver (RX) radio <NUM>) wireless signals through antennas <NUM> via the RF front end <NUM>. In an aspect, the transceiver <NUM> may be tuned to operate at specified frequencies such that the UE <NUM> can communicate with, for example, base stations <NUM>. In an aspect, for example, the modem <NUM> can configure the transceiver <NUM> to operate at a specified frequency and power level based on the configuration of the UE <NUM> and communication protocol used by the modem <NUM>.

The UE <NUM> in <FIG> may further include a memory <NUM>, such as for storing data used herein and/or local versions of applications or communicating component <NUM> and/or one or more of its sub-components being executed by processor <NUM>. Memory <NUM> can include any type of computer-readable medium usable by a computer or processor <NUM>, such as RAM, ROM, tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory <NUM> may be a computer-readable storage medium that stores one or more computer-executable codes defining communicating component <NUM> and/or one or more of its sub-components. Additionally or alternatively, the UE <NUM> may include a bus <NUM> for communicatively coupling one or more of the RF front end <NUM>, the transceiver <NUM>, the memory <NUM>, or the processor <NUM>, and to exchange signaling information between each of the components and/or sub-components of the UE <NUM>.

In examples described herein, the downlink and uplink reference signals can be jointly designed for efficient CLI measurement and reporting (e.g. to provide fast and accurate CLI measurement to facilitate CLI mitigation in a dynamic time division duplexing (TDD) configuration). In an example, cells of base stations <NUM> may be aligned in time, such as symbol-aligned and/or slot aligned, where a symbol can be an orthogonal frequency division multiplexing (OFDM) symbol, single carrier frequency division multiplexing (SC-FDM) symbol, or other division of time, and a slot may include a number of symbols (e.g., <NUM> or <NUM> symbols per slot in <NUM>). The DL and UL RSs can be a new type of RS used for CLI measurement or an existing RS (e.g., CSI-RS, sounding RS (SRS), etc.). In an example, a base station <NUM> can measure base station-to-base station interference based on DL RSs from other base stations, and/or UE <NUM> can measure UE-to-UE interference based on UL RSs from other UEs, which the UE <NUM> can report to its serving base station <NUM>. Based on the reported interference measurement, for example, the base station can perform interference-aware coordinated scheduling for a served UE <NUM>. In an example, this can be in conjunction with other interference management/mitigation schemes (e.g., beam coordination, power control, etc.).

<FIG> illustrates a flow chart of an example of a method <NUM> for configuring (e.g., by an access point or base station (e.g., base station <NUM>-b), such as an eNB, gNB, etc.) one or more UEs to transmit a reference signal in resources over which another access point transmits a reference signal. In method <NUM>, blocks indicated as dashed boxes may represent optional steps.

In method <NUM>, at Block <NUM>, an indication of resources over which a DL reference signal is transmitted, or DL interference measurement resources (IMR) is configured, by an access point, can be received from the access point. In an aspect, DL RS determining component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM> and/or scheduling component <NUM>, can receive, from the access point (e.g., another base station <NUM>-a where base station <NUM>-b performs method <NUM>), the indication of resources over which the DL reference signal is transmitted, or the DL IMR is configured, by the access point. For example, base station <NUM>-b may transmit a DL reference signal over certain resources (e.g., in a symbol within a slot), and/or may configure certain resources as DL IMR to allow other base stations to transmit DL reference signal without interference (or at least to mitigate interference) from base station <NUM>. In one example, the resources related to transmitting DL reference signals can be referred to as non-zero-power (NZP) reference signals, and the resource related to DL IMR can be referred to as zero-power (ZP) reference signals, as the base station <NUM> does not transmit (e.g., uses zero power) over the ZP reference signal resources. In any case, for example, base station <NUM>-a may transmit an indication of the certain resources to base station <NUM>-b and/or other base stations to facilitate CLI mitigation. For example, DL RS determining component <NUM> may receive the indication from base station <NUM>-b over a backhaul link <NUM>, <NUM> or other communicative coupling between the base stations <NUM>-a, <NUM>-b. The resources can be indicated as time resources (e.g., symbol(s)), frequency resources (e.g., resource block(s)), spatial resources (e.g., beam(s)), etc. Though CSI-RSs are mainly described herein, in some examples the DL reference signals (whether NZP or ZP) may include SRSs or other reference signals.

In method <NUM>, at Block <NUM>, a UE can be configured to transmit a UL reference signal based on the indication of the resources. In an aspect, UL RS assigning component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM> and/or scheduling component <NUM>, can configure the UE to transmit the UL reference signal based on the indication of the resources. For example, UL RS assigning component <NUM> may configure the UE <NUM>-b to transmit the UL reference signal based on receiving the indication of the DL reference signal and/or DL IMR from the base station <NUM>-a. Moreover, in an example, UL RS assigning component <NUM> may configure the UE <NUM>-b to transmit the UL reference signal based at least in part on another indication that the UE <NUM>-b is causing interference to one or more UEs served by base station <NUM>-a. In any case, for example, UL RS assigning component <NUM> can configure the UE <NUM>-b by transmitting one or more parameters in a configuration thereto, where the configuration can indicate one or more symbols corresponding to the resources. In another example, UL RS assigning component <NUM> can determine and/or transmit one or more parameters for orthgonalizing the UL RS with respect to the DL reference signal and/or DL IMR. Such parameters may include, for example, a time division (e.g., symbol in a slot) to use in transmitting the RS, frequency division (e.g., one or more resource blocks or resource elements) to use in transmitting the RS, code division (e.g., one or more orthogonal cover codes) to use in transmitting the RS, etc., which can be different that the parameters for the DL CSI-RS/IMR (e.g., as indicated by the base station <NUM>-a). Thus, in one example, the UE <NUM>-b can transmit UL reference signal using resources orthogonal to those scheduled for DL reference signal and/or DL IMR. Though CSI-RSs are mainly described herein, in some examples the UL reference signals may include SRSs or other reference signals.

For example, UL RS assigning component <NUM> may assign a symbol of the resources as indicated for DL IMR to allow the UE <NUM>-b to transmit UL CSI-RS without interference from other RSs. In another example, UL RS assigning component <NUM> may assign the same symbol of the resource as indicated for DL CSI-RS transmission by the base station <NUM>-a, but can assign or apply a different orthogonal cover code for the UL CSI-RS of UE <NUM>-a than that used by base station <NUM>-b in transmitting the DL CSI-RS in the same symbol. Also, for example, UL RS assigning component <NUM> can transmit the one or more parameters in a radio resource control (RRC) layer message, layer <NUM> (physical or PHY layer) or layer <NUM> (media access control or MAC layer) message, dedicated control signaling, broadcast signaling (e.g., system information broadcast (SIB), etc.).

Moreover, in an example, UL RS assigning component <NUM> may configure the UE <NUM>-b to transmit a SRS over the resources, where the configuration may allow for specifying additional parameters for the SRS, such as a flexible symbol location within the slot (e.g., to place the SRS in the cross-interference region). In any case, for example, the configuration provided to the UE can include an indication of the resources (or at least a portion thereof). The indication may specify time resources (e.g., symbol), frequency resources (e.g., resource block(s)), spatial resources (e.g., beam), etc. In any case, the UE <NUM> can receive the one or more parameters, and can generate and transmit the UL CSI-RS, SRS, or other RS, based on the one or more parameters, as described further herein.

Examples of resource allocations and associated RS configurations are illustrated in <FIG>, at resource allocations <NUM> and <NUM>. For example, in <FIG>, resource allocation <NUM> illustrates a plurality of symbols (e.g., OFDM, SC-FDM, etc. symbols, represented horizontally). Resource allocation <NUM> corresponds to a first cell (e.g., provided by a first base station, such as base station <NUM>-a serving a UE <NUM>-a), and resource allocation <NUM> corresponds to a second cell (e.g., provided by a second base station, such as base station <NUM>-b serving UE <NUM>-b). In Slot <NUM>, resource allocation <NUM> includes a plurality of symbols in a downlink control and data region, followed by three symbols for DL IMR, followed by a blank symbol (e.g., to allow switching to uplink in TDD), followed by an uplink control and data region. In Slot <NUM>, resource allocation <NUM> also includes a plurality of symbols in a shorter downlink control and data region, followed by an uplink control and data region that overlaps (in time) with the downlink region of resource allocation <NUM>. The second cell can allocate the symbols aligning to the DL IMR symbols (e.g., DL ZP CSI-RS symbols) of resource allocation <NUM> as UL CSI-RS symbols to allow UE <NUM>-a to receive and measure UL CSI-RS from UE <NUM>-b without interference from downlink communications of base station <NUM>-a. For example, UL RS assigning component <NUM> of base station <NUM>-b can assign these resources to UE <NUM>-b to facilitate transmitting the UL CSI-RS. In addition, in an example, UL RS assigning component <NUM> may notify additional neighboring base stations of the assignment of resources to cause the other base stations not to transmit DL CSI-RS over the resources.

In method <NUM>, optionally at Block <NUM>, a second UE can be configured to transmit a second UL reference signal based on the indication of the resources. In an aspect, UL RS assigning component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM> and/or scheduling component <NUM>, can configure the second UE to transmit the second UL reference signal based on the indication of the resources. For example, UL RS assigning component <NUM> can configure the second UE to transmit the second UL reference signal over the same resources (e.g., the same symbol and/or frequency division) as the UE <NUM>-a transmits its UL reference signal) and/or using a different orthogonal cover code. Thus, UE <NUM>-b may be able to detect the two (or more) UL reference signals from the two (or more) UEs, and can accordingly report the interference of one or both of the UEs to the base station <NUM>-b, as described further herein.

In method <NUM>, optionally at Block <NUM>, the UE can be configured to transmit the uplink reference signal over second resources and a ZP reference signal over third resources, and the second UE can be configured to transmit the second reference signal over the third resources and a ZP reference signal over the second resources. In an aspect, UL RS assigning component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, transceiver <NUM> and/or scheduling component <NUM>, can configure the UE <NUM>-a to transmit the uplink reference signal over second resources and a ZP reference signal over third resources, and the second UE to transmit the second reference signal over the third resources and a ZP reference signal over the second resources. For example, in reference to <FIG>, given three DL IMR symbols indicated in resource allocation <NUM>, UL RS assigning component <NUM> can configure (e.g., in resource allocation <NUM>) both UEs to transmit UL reference signal over the first symbol, one UE to transmit UL reference signal over the second symbol (and a ZP reference signal in the third symbol) and the other UE to transmit UL reference signal in the third symbol (and a ZP reference signal in the second symbol). This can allow UE <NUM>-b to determine interference caused by both UEs based on the corresponding UL reference signals in a multiple interferer situation. Thus, in this regard, multiple UEs and base stations can be jointly configured to generate different cross-cell/inter-cell interference patterns on different reference signal resources.

<FIG> illustrates a flow chart of an example of a method <NUM> for receiving (e.g., by an access point or base station (e.g., base station <NUM>-a), such as an eNB, gNB, etc.) measurements associated with one or more reference signals transmitted by a base station or UE. In method <NUM>, blocks indicated as dashed boxes may represent optional steps.

In method <NUM>, at Block <NUM>, a DL reference signal can be transmitted or DL IMR can be configured over resources. In an aspect, scheduling component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can transmit the DL reference signal or configure the DL IMR over the resources. For example, the resources may include a frequency division over a time division (e.g., one or more symbols of a slot). In one example, configuring the DL IMR and/or the DL reference signal may include and/or may be based on transmitting an indication of the resources over which the DL reference signal is transmitted and/or which resources are considered DL IMR (e.g., as ZP reference signal that other base stations may use for transmitting DL reference signal). Scheduling component <NUM> can transmit such configurations using RRC or other higher layer signaling, dedicated control signaling to a UE, etc., and/or may transmit reference signals over a control channel using the frequency division over the time division (e.g., one or more resource blocks of an OFDM or SC-FDM symbol in a slot of multiple symbols). For example, the DL reference signal may include CSI-RS, SRS, or other reference signals, as described. Resource allocation <NUM> in <FIG> shows examples of symbols used for DL CSI-RS and DL IMR.

For example, one or more UEs <NUM>-a may receive the DL CSI-RS and/or the configuration indicating DL IMR (and/or DL CSI-RS resources), and may measure CSI-RSs over the resources. In one example, the UE <NUM>-a may be agnostic to the fact that the CSI-RSs transmitted over the resources may actually include UL CSI-RSs (as opposed to DL CSI-RSs), as described herein, and may thus measure and report any UL CSI-RSs received in DL IMR as DL CSI-RSs. In one example, such UEs may report the UL CSI-RSs as related to a different antenna port of the base station <NUM>-a. Base station <NUM>-a, however, may be able to distinguish reported interference measurements based on information from base station <NUM>-b on resources over which it instructed one or more UEs (e.g., UE <NUM>-b) to transmit UL CSI-RS. For example, the information can be shared among the base stations <NUM>-a, <NUM>-b over a backhaul link, as described.

In method <NUM>, at Block <NUM>, an interference measurement report can be received from a served UE including measurement of at least one or more UL reference signals transmitted over the resources. In an aspect, scheduling component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can receive the interference measurement report from the served UE, where the report includes measurement of at least one or more UL reference signals transmitted over the resources. As described, for example, another base station (e.g., base station <NUM>-b) can instruct a UE to transmit UL reference signals on the resources indicated as being used by the base station <NUM>-a for DL reference signal or DL IMR. Thus, the served UE <NUM>-a may measure the UL reference signals received over the resources (though it may not distinguish the reference signals as being UL or DL). In one example, where the UE <NUM>-a is capable of distinguishing UL and DL reference signals, the measurement report may indicate whether the measurement corresponds to an UL or DL reference signal. In other examples, the report may not distinguish between measurements for UL and DL reference signal, and/or the base station <NUM> may do so based in part on known information regarding scheduled resources.

In any case, in method <NUM>, at Block <NUM>, the interference measurement report can be categorized as interference caused by one or more UL reference signals and/or DL reference signals. In an aspect, scheduling component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can categorize the interference measurement report as interference caused by one or more reference signals and/or DL reference signals. For example, scheduling component <NUM> can determine the categorization based on the measurement report specifying whether measurements are related to UL or DL reference signals. In another example, scheduling component <NUM> can determine resources used for UL reference signals based on determining resources indicated by another base station (e.g., base station <NUM>-b) as being used for DL reference signal or DL IMR. Where measurements correspond to resources indicated as used for DL reference signal, scheduling component <NUM> may attempt to separate the UL and DL reference signal measurements based on known orthogonality parameters. For example, scheduling component <NUM> may receive an indication of resources from the other base station (e.g., base station <NUM>-b) as to a symbol over which UL reference signal is configured for one or more UEs, a portion of frequency resources over which UL reference signal is configured for the one or more UEs, orthogonal cover code(s) used by the one or more UEs in transmitting the UL reference signals, and/or the like, and the scheduling component <NUM> may accordingly categorize received interference measurements based on associated symbol.

In another example, the UE <NUM>-a may report the interference measurements as related to different antenna ports of the base station (e.g., base station <NUM>-a) based on determining that the reference signals are transmitted in different frequency resources, symbols, using different orthogonal cover codes, etc. In this regard, scheduling component <NUM> may categorize the measured interference based on an indication of antenna port specified by the UE <NUM>-a.

In method <NUM>, optionally at Block <NUM>, a second DL reference signal transmitted by another access point can be measured. In an aspect, scheduling component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can measure the second downlink reference signal transmitted by another access point (e.g., base station <NUM>-b). For example, scheduling component <NUM> can determine resources associated with the DL reference signal of other base stations, as described above, and may accordingly declare related resources as UL IMR for measuring the DL reference signal of other base stations without UL interference from other UEs. Thus, during the uplink for base station <NUM>-a, CLI from base station <NUM>-b and the uplink channel from UE <NUM>-a can be measured.

In method <NUM>, at Block <NUM>, resources can be scheduled for the UE based at least in part on the categorized interference and/or measurement of the second DL reference signal. In an aspect, scheduling component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can schedule resources for the UE (e.g., UE <NUM>-a) based at least in part on the categorized interference and/or measurement of the second DL reference signal. For example, scheduling component <NUM> can avoid scheduling downlink resources to the UE <NUM>-a that may be interfered by UE <NUM>-b on the uplink and/or uplink resources that may be interfered by base station <NUM>-b on the downlink, etc. Accordingly, CLI can be taken into consideration in scheduling the resources, as the UE <NUM>-a measurements of UL reference signals can be used in scheduling the resources for the UE <NUM>-a.

<FIG> illustrates a flow chart of an example of a method <NUM> for transmitting (e.g., by UE) a UL reference signal. In method <NUM>, blocks indicated as dashed boxes may represent optional steps.

In method <NUM>, at Block <NUM>, an indication of resources over which to transmit a UL reference signal can be received from an access point. In an aspect, communicating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can receive, from the access point, an indication of resources over which to transmit a UL reference signal. As described, for example, the resources indicated by the access point may include resources used by the access point or another access point for transmitting DL reference signal, configuring DL IMR, etc. Moreover, for example, the resources may be orthogonal to DL reference signal resources in time, frequency, or space, and associated parameters may be received from the access point (e.g., a symbol index, resource block, orthogonal cover code, etc. to use in transmitting the UL reference signal). The resources can be indicated as time resources (e.g., symbol), frequency resources (e.g., resource block(s)), spatial resources (e.g., beam), etc. Additionally, as described, communicating component <NUM> can receive the resources (e.g., or an indication of the resources or parameters for determining the resources) in layer <NUM> signaling, layer <NUM> signaling, higher layer signaling (e.g., RRC), broadcast or dedicated signaling, in a control channel, and/or the like, from the access point. Moreover, as described, the reference signal may include one or more of an UL CSI-RS, UL SRS, or other UL reference signal.

In method <NUM>, at Block <NUM>, the UL reference signal can be transmitted over the resources. In an aspect, communicating component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, and/or transceiver <NUM>, can transmit the UL reference signal over the resources. For example, communicating component <NUM> may transmit the UL reference signal over the indicated symbol, resource block, etc., using the specified orthogonal cover code, and/or the like to facilitate transmitting UL reference signal for CLI mitigation, as described herein. For example, this may include communicating component <NUM> transmitting the UL reference signal over similar resources as DL reference signal or DL IMR resources (e.g., in a similar symbol but over different frequency resources or using a different orthogonal cover code, etc.).

<FIG> illustrates a flow chart of an example of a method <NUM> for transmitting (e.g., by UE) an interference measurement report to an access point. In method <NUM>, blocks indicated as dashed boxes may represent optional steps.

In method <NUM>, at Block <NUM>, a DL reference signal can be received from an access point, and/or one or more UL reference signals can be received from one or more UEs over a set of resources. In an aspect, RS measuring component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, communicating component <NUM>, and/or transceiver <NUM>, can receive, over a set of resources, a DL reference signal from an access point and/or one or more UL reference signals from one or more UEs. For example, RS measuring component <NUM> may receive DL reference signals and UL reference signals orthogonally to one another (e.g., in time, frequency, space, etc.). For instance, RS measuring component <NUM> may receive DL reference signal in a symbol of a slot and may receive UL reference signal in a symbol of another slot. In another example, RS measuring component <NUM> may receive DL reference signal and UL reference signal in different frequency divisions, using different orthogonal cover codes, etc., in the same symbol or otherwise. Moreover, as described, RS measuring component <NUM> may receive (and measure) multiple reference signals received from multiple UEs over the set of resources (e.g., based on different orthogonal cover codes, different utilized frequency resources, etc.). Moreover, as described, the downlink reference signal and/or uplink reference signal may include CSI-RS, SRS, other reference signals.

In method <NUM>, at Block <NUM>, the downlink reference signal and interference caused by the one or more UL reference signals can be measured. In an aspect, RS measuring component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, communicating component <NUM>, and/or transceiver <NUM>, can measure the DL reference signal and interference caused by the one or more UL reference signals. As described, for example, RS measuring component <NUM> can distinguish between the DL reference signal and UL reference signal in one example (e.g., based on resources over which the reference signals are transmitted, an indication in the reference signals, etc.). In an example, measuring the interference may include measuring one or more properties of the signal received in the set of resources (e.g., a received signal strength indicator (RSSI), reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-noise ratio (SNR), etc.).

In method <NUM>, at Block <NUM>, an interference measurement report can be transmitted, to a serving access point, indicating the interference caused by the one or more UL reference signals. In an aspect, interference reporting component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, communicating component <NUM>, and/or transceiver <NUM>, can transmit, to the serving access point, an interference measurement report indicating at least the interference caused by the one or more UL reference signals. For example, interference reporting component <NUM> can report the interference by indicating whether and/or which UL reference signal to which the interference relates. For example, interference reporting component <NUM> may indicate a symbol, frequency resources, orthogonal cover code, etc. related to the received UL reference signal, and may indicate the interference or associated signal parameter measurement. Interference reporting component <NUM> may transmit the interference measurement report in dedicated resources to the serving access point, in one example.

In method <NUM>, optionally at Block <NUM>, an indication of CSI based on the DL reference signal can be transmitted to the serving access point. In an aspect, interference reporting component <NUM>, e.g., in conjunction with processor(s) <NUM>, memory <NUM>, communicating component <NUM>, and/or transceiver <NUM>, can transmit, to the serving access point, an indication of CSI based on the DL reference signal. Thus, interference reporting component <NUM> can not only report the interference from UL reference signal, but can also determine and report CSI related to the received reference signal for use by the serving access point in scheduling resources to the UE. As described, in one example, the UE may not distinguish between UL and DL reference signals, and interference reporting component <NUM> may report both (e.g., as DL reference signal) to the serving access point.

<FIG> is a block diagram of a MIMO communication system <NUM> including a base station <NUM> and a UE <NUM>. The MIMO communication system <NUM> may illustrate aspects of the wireless communication system <NUM> described with reference to <FIG>. The base station <NUM> may be an example of aspects of the base station <NUM> described with reference to <FIG>. The base station <NUM> may be equipped with antennas <NUM> and <NUM>, and the UE <NUM> may be equipped with antennas <NUM> and <NUM>. In the MIMO communication system <NUM>, the base station <NUM> may be able to send data over multiple communication links at the same time. Each communication link may be called a "layer" and the "rank" of the communication link may indicate the number of layers used for communication. For example, in a 2x2 MIMO communication system where base station <NUM> transmits two "layers," the rank of the communication link between the base station <NUM> and the UE <NUM> is two.

The UE <NUM> may be an example of aspects of the UEs <NUM> described with reference to <FIG>. At the UE <NUM>, the UE antennas <NUM> and <NUM> may receive the DL signals from the base station <NUM> and may provide the received signals to the modulator/demodulators <NUM> and <NUM>, respectively. Each modulator/demodulator <NUM> through <NUM> may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator <NUM> through <NUM> may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector <NUM> may obtain received symbols from the modulator/demodulators <NUM> and <NUM>, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive (Rx) processor <NUM> may process (e.g., demodulate, deinterleave, and decode) the detected symbols, providing decoded data for the UE <NUM> to a data output, and provide decoded control information to a processor <NUM>, or memory <NUM>.

The processor <NUM> may in some cases execute stored instructions to instantiate a communicating component <NUM> (see e.g., <FIG> and <FIG>).

The processor <NUM> may in some cases execute stored instructions to instantiate a scheduling component <NUM> (see e.g., <FIG> and <FIG>).

Due to the nature of software, functions described above can be implemented using software executed by a specially programmed processor, hardware, firmware, hardwiring, or combinations of any of these.

Claim 1:
A method for configuring reference signal transmission in wireless communications, for a first access point (<NUM>) serving a user equipment, UE (<NUM>), the method comprising:
receiving (<NUM>), from a second access point, an indication of resources over which at least one of a downlink reference signal is transmitted, or downlink interference measurement resource, IMR, is configured, by the second access point; and
configuring (<NUM>) the UE to transmit an uplink reference signal over the resources.