Patent Description:
The present disclosure generally relates to the field of wireless network communications, and more particularly, to deploying aperiodic channel state information reference signals in mixed numerology environments.

Prior art implementations of deploying aperiodic channel state information reference signals in mixed numerology environments are known from the document: <NPL>, relates to issues of CSI reporting for NR-MIMO.

Additional prior art implementations of deploying aperiodic channel state information reference signals in mixed numerology environments are known from the document: <NPL>, relates to issues on NR CSI reporting.

The scope of the present invention is defined by the scope of the appended claims.

The next generation mobile wireless communication system (<NUM>) or new radio (NR), supports a diverse set of use cases and a diverse set of deployment scenarios. Some deployment scenarios include deployment at both low frequencies (<NUM> of MHz), similar to LTE today, and very high frequencies (mm waves in the tens of GHz).

Similar to LTE, NR uses orthogonal frequency division multiplexing (OFDM) in the downlink (i.e., from a network node, gNB, eNB, or base station, to a user equipment (UE). In the uplink (i.e., from UE to gNB), both discrete Fourier transform spread (DFT-spread) OFDM and OFDM is supported.

The basic NR physical resource can thus be seen as a time-frequency grid as illustrated in <FIG>, where each resource element corresponds to one OFDM subcarrier during one OFDM symbol interval. Resource allocation in a slot is described in terms of resource blocks (RBs) in the frequency domain and number of OFDM symbols in the time domain. An RB corresponds to <NUM> contiguous subcarriers and a slot consists of <NUM> OFDM symbols.

Different subcarrier spacing values are supported in NR. The supported subcarrier spacing values (also referred to as numerologies) in NR are given by Δƒ = (<NUM> × <NUM>µ) kHz where µ = <NUM>,<NUM>,<NUM>,<NUM>,<NUM>. The possible subcarrier spacings are summarized in Table <NUM>.

In the time domain, downlink and uplink transmissions in NR are organized into equally-sized subframes, similar to LTE, as shown in <FIG>. A subframe is further divided into slots and the number of slots per subframe is <NUM>µ for a numerology of (<NUM> × <NUM>µ) kHz.

NR supports "slot based" transmission. In each slot, the gNB transmits downlink control information (DCI) about which UE data is to be transmitted to and what resources in the current downlink slot the data is transmitted on. The DCI is carried on the Physical Control Channel (PDCCH) and data is carried on Physical Downlink Shared Channel (PDSCH).

These figures will be better understood by reference to the following detailed description.

The PDCCH is typically transmitted in control resource sets (CORSETs) in the first few OFDM symbols in each slot. In operation, a UE may first decode PDCCH and, if a PDCCH is decoded successfully, though UE may then decode the corresponding PDSCH based on the decoded DCI in the PDCCH.

Uplink data transmissions are also dynamically scheduled using PDCCH. For example, similar to the downlink scenario, a UE first decodes an uplink grant in a DCI carried by PDCCH and then transmits data over the Physical Uplink Shared Channel (PUSCH) based the decoded control information in the uplink grant such as modulation order, coding rate, and uplink resource allocation, etc..

Each UE is assigned with a unique C-RNTI (Cell Radio Network Temporary Identifier) during network connection. The CRC (cyclic redundancy check) bits attached to a DCI for a UE may be scrambled by the UE's C-RNTI, so that a UE can recognize its own DCI by checking the CRC bits of the DCI against the assigned C-RNTI.

For UL scheduling of PUSCH, at least the following bit fields are included in a UL DCI:.

For DL scheduling of PDSCH, at least the following bit fields are included in an DL DCI.

Channel state information (CSI) feedback is used by gNB to obtain DL CSI from a UE in order to determine how to transmit DL data to a UE over plurality of antenna ports. The CSI typically includes a channel rank indicator (RI), a precoding matrix indicator(PMI), and a channel quality indicator (CQI). RI is used to indicate the number of data layers that can be transmitted simultaneously to a particular UE; PMI is used to indicate the precoding matrix over the indicated data layers; and CQI is used to indicate the modulation and coding rate that can be achieved with the indicated rank and the precoding matrix. A special type of CSI reporting is beam reporting, where the gNB transmits multiple CSI-RS resources in a plurality of beams and the UE feeds back a number of the strongest beams of the plurality of beams in the form of multiple CSI-RS resource indicators (CRIs) together with L1-RSRP (reference signal received power) for each selected resource.

In NR, in addition to periodic and aperiodic CSI reporting as in LTE, semi-persistent CSI reporting is also supported. Thus, three types of CSI reporting may be supported in NR as follows:.

First, periodic CSI (P-CSI) Reporting on PUCCH. CSI is reported periodically by a UE. Parameters such as periodicity and slot offset are configured semi-statically by higher layer RRC signaling from the gNB to the UE.

Second, aperiodic CSI (A-CSI) Reporting on PUSCH. This type of CSI reporting involves a single-shot (i.e., one time) CSI report by a UE which is dynamically triggered by the gNB using DCI. Some of the parameters related to the configuration of the aperiodic CSI report is semi-statically configured by RRC but the triggering is dynamic.

Third, semi-persistent CSI (SP-CSI) Reporting on PUSCH. Similar to periodic CSI reporting, semi-persistent CSI reporting has a periodicity and slot offset which may be semi-statically configured. However, a dynamic trigger from a gNB to a UE may be needed to allow the UE to begin semi-persistent CSI reporting. A dynamic trigger from the gNB to the UE is needed to request the UE to stop the semi-persistent CSI reporting.

Non-zero power (NZP) CSI-RS is used for measuring downlink CSI by a UE. CSI-RS is transmitted over each transmit (Tx) antenna port at the gNB and for different antenna ports, the CSI-RS are multiplexed in time, frequency, and code domains such that the channel between each Tx antenna port at the gNB and each receive antenna port at a UE can be measured by the UE. A time frequency resource used for transmitting CSI-RS may be referred to as a CSI-RS resource.

In NR, the following three types of CSI-RS transmissions are supported:.

First, periodic CSI-RS (P CSI-RS): CSI-RS is transmitted periodically in certain slots. This CSI-RS transmission is semi-statically configured using parameters such as CSI-RS resource, periodicity and slot offset.

Second, aperiodic CSI-RS (AP CSI-RS). This is a one-shot CSI-RS transmission that can happen in any slot. Here, one-shot means that CSI-RS transmission only happens once per trigger. The CSI-RS resources within a slot (i.e., the resource element locations which consist of subcarrier locations and OFDM symbol locations) for aperiodic CSI-RS are semi-statically configured. The transmission of aperiodic CSI-RS is triggered by dynamic signaling through PDCCH using the CSI request field in UL DCI. Multiple aperiodic CSI-RS resources can be included in a CSI-RS resource set and the triggering of aperiodic CSI-RS is on a resource set basis. The slot offset of the CSI-RS relative to the triggering DCI is given by the RRC parameter aperiodicTriggeringOffset which is given on an CSI-RS resource set level.

Third, semi-persistent CSI-RS (SP CSI-RS). Similar to periodic CSI-RS, resources for semi-persistent CSI-RS transmissions are semi-statically configured with parameters such as periodicity and slot offset. However, unlike periodic CSI-RS, dynamic signaling is needed to activate and deactivate the CSI-RS transmission.

In the case of aperiodic CSI-RS and/or aperiodic CSI reporting, the gNB RRC configures the UE with S_c CSI triggering states. Each triggering state contains the aperiodic CSI report setting to be triggered along with the associated aperiodic CSI-RS resource sets.

In NR, a UE can be configured with N≥<NUM> CSI reporting settings (i.e., ReportConfigs), M≥<NUM> resource settings (i.e., ResourceConfigs). At least the following configuration parameters may be signaled via RRC for CSI acquisition.

A-CSI reporting over PUSCH is triggered by a DCI for scheduling PUSCH, i.e., an UL DCI. A special CSI request bit field in the DCI is defined for the purpose. Each value of the CSI request bit field defines a codepoint and each codepoint can be associated with a higher layer configured CSI report trigger state. The first codepoint with all "<NUM>"s corresponds to a no CSI request. For A-CSI reporting, each of the SC triggering states comprise indication of one or more A-CSI reports to be triggered. Optionally, each triggered A-CSI report may also trigger aperiodic NZP CSI-RS resource sets for channel measurements, aperiodic CSI-IM and/or aperiodic NZP CSI-RS for interference measurements. Thus, each CSI report trigger state defines at least the following information:.

The bit width, Lc, of the CSI request field is configurable from <NUM> to <NUM> bits. When the number of CSI triggering states, Sc, is larger than the number of codepoints, i.e., Sc > <NUM>Lc - <NUM> , MAC (Medium Access Control) CE (control element) is used to select a subset of <NUM>Lc - <NUM> triggering states from the Sc triggering states so that there is a one-to-one mapping between each codepoint and a CSI triggering state. Some of these aspects may be seen in the illustration of aperiodic CSI reporting in <FIG>.

There currently exist certain challenges. The current aperiodic CSI-RS triggering procedure in NR is not well-defined for the case where the DCI triggering the aperiodic CSI-RS and the aperiodic CSI-RS itself are transmitted on carriers or bandwidth parts which use different numerologies. For instance, it is not clear how to derive in which slot the aperiodic CSI-RS resource is transmitted due to the different numerologies resulting in different slot lengths and, therefore, different slot indexing. Another issue is that the aperiodic CSI-RS could be transmitted non-causally in case the CSI-RS subcarrier spacing (SCS) is larger than the PDCCH SCS, which would require a UE implementation to buffer OFDM symbols for several slots in the carrier with larger SCS in anticipation of potential aperiodic CSI-RS triggers in the carrier with the smaller SCS, which increases UE implementation complexity and memory consumption.

Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges, decreasing UE implementation complexity and memory consumption. In this disclosure, a predefined rule is introduced to map the PDCCH reception slot in the numerology of the triggering PDCCH to a reference slot in the numerology of the CSI-RS such that the reference slot is the latest slot overlapping in time with PDCCH reception slot. The triggering offset of the aperiodic CSI-RS is then applied relative to the reference slot in the CSI-RS numerology.

Additionally, a restriction of aperiodic CSI-RS slot offset may be applied in the case where the PDCCH SCS is smaller than the aperiodic CSI-RS SCS, such that PDCCH decoding can be assured to be completed earlier in time than the occurrence of the aperiodic CSI-RS.

There are, proposed herein, various embodiments which address one or more of the issues disclosed herein. For example, <FIG> illustrates a method <NUM> according to some embodiments the present disclosure, performed by a wireless device, for receiving an aperiodic CSI-RS on a first carrier that uses a first OFDM numerology may include several operations. Such operations may include receiving a DCI message carried by a PDCCH) on a second carrier that uses a second OFDM numerology (operation <NUM>), obtaining an aperiodic CSI-RS slot offset from the DCI message (operation <NUM>), determining, on the first carrier, a reference slot in the first numerology (operation <NUM>), determining the slot of the aperiodic CSI-RS based on the reference slot and the aperiodic CSI-RS slot offset (operation <NUM>), and receiving the aperiodic CSI-RS in the determined slot of the aperiodic CSI-RS (operation <NUM>). Additional embodiments of the method <NUM> may include additional operations beyond those enumerated in <FIG>. For example, embodiments of the method <NUM> may include additional operations before, after, in between, or as part of the enumerated operations. Some embodiments of the method <NUM> include a set of instructions stored on a computer readable medium that can be executed by a processor to perform associated operations.

Certain embodiments may provide one or more of the following technical advantage. Aperiodic triggering of CSI-RS may be seamlessly supported irrespective of the numerology of the PDCCH and CSI-RS. Existing RRC configurations of aperiodic CSI-RS triggering offset can be reused for the mixed numerology aperiodic CSI-RS triggering case. By mapping the PDCCH reception slot to a reference slot in the CSI-RS numerology which is the latest overlapping slot, the number of OFDM symbols of the CIS-RS numerology the UE needs to buffer in anticipation of potential aperiodic CSI-RS triggering is minimized, which minimizes UE memory consumption and complexity.

The herein presented technology discloses a method for aperiodic CSI-RS triggering where the PDCCH carrying the triggering DCI is transmitted on a different carrier or bandwidth part than the triggered aperiodic CSI-RS, where additionally the carrier or bandwidth part of the PDCCH uses a different numerology than the carrier or bandwidth part whereon the aperiodic CSI-RS is transmitted. Here, numerology is equated to subcarrier spacing (SCS) and the SCSs may be represented with µCSIRS and µPDCCH respectively (corresponding to a SCS of Δƒ = (<NUM> × <NUM>µ) kHz). The presented technology may provide a general solution applicable to all of the possible relationships between with µCSIRS and µPDCCH, i.e., µCSIRS > µPDCCH, µCSIRS < µPDCCH, and µCSIRS = µPDCCH.

In prior art solutions, only aperiodic CSI-RS triggering where the CSI-RS and triggering PDCCH have the same numerology have been considered. In such cases, it is relatively simple to determine the slot of the aperiodic CSI-RS as the slot X slots after the slot wherein the PDCCH is received. For example, if the PDCCH is received in slot n, the CSI-RS is transmitted in slot n+X, where X is the RRC configured aperiodic CSI-Rs slot offset. However, for the mixed numerology triggering case, it is ambiguous how to interpret such a slot offset.

The solutions presented in the present disclosure may rely on defining a predefined mapping between the PDCCH reception slot in the numerology of the PDCCH to a reference slot n' in the numerology of the CSI-RS. The indicated slot offset X in is then mapped to a slot a n'+X in the numerology of the CSI-RS.

In some embodiments, the reference slot n' is a slot overlapping in time with the slot of the PDCCH. For instance, the latest slot in the numerology of the CSI-RS overlapping in time with the slot of the PDCCH is determined as the reference slot. Alternatively, the first slot in the numerology of the CSI-RS overlapping in time with the slot of the PDCCH is determined as the reference slot (or more generally, a pre-determined slot).

In another embodiment, a slot not overlapping in time is selected as the reference slot, such as the first slot in the CSI-RS numerology not overlapping in time with the reference slot. The term "overlapping slot" includes two concepts. In one embodiment the slot timing of the two carriers/bandwidth parts as received by the UE is used to determine if slots are overlapping. In another embodiment, the UE compensates for any potential receive timing difference before determining the reference slot, i.e., first slot in a subframe of both numerologies have same start time. The two carriers could be transmitted by non co-located base stations or transmission points and, thus, the propagation delays are different resulting in different receive times.

In some embodiments, the UE may implicitly determine the reference slot as part of the procedure for determining the slot of the aperiodic CSI-RS, i.e., it may use the reference slot as an intermediate calculation in the process of determining the aperiodic CSI-RS slot and may not determiner the reference slot explicitly.

In one example, the reference slot may be determined as <MAT>, where n is the slot of the triggering PDCCH. The slot counters n and n' are typically re-started at every subframe boundary. This would map the reference slot as:.

An illustration of the above example is given in <FIG>.

In one embodiment, a restriction on the slot offset X is imposed when µCSIRS > µPDCCH, such that the aperiodic slot offset must be larger than some value, for instance zero. Enforcing a non-zero slot offset assures that the aperiodic CSI-RS is always transmitted after PDCCH reception is complete, which removes the need for the UE to buffer OFDM symbols on the CSI-RS carrier in anticipation of a potential aperiodic CSI-RS trigger on the PDCCH carrier.

In another embodiment the slot offset X is scaled based on the numerology ratio, i.e., CSI-RS is transmitted in slot <MAT>, with n the reference slot as determined above and X the indicated slot offset. Using the scaled X instead of X directly could be limited to case µCSIRS > µPDCCH. Slots with higher µ values are shorter, so the scaling compensates for that and guarantees the UE has sufficient time.

Using the specification language of TS <NUM>, the herein presented method may be implemented as follows:.

When aperiodic CSI-RS is used with aperiodic reporting, the CSI-RS offset X is configured per resource set by the higher layer parameter aperiodicTriggeringOffset. The CSI-RS triggering offset has the range of <NUM> to <NUM> slots. The UE shall transmit a CSI report or receive the CSI-RS in slot <MAT>, where n is the slot with the triggering DCI in the numerology of the PDCCH, X is the CSI-RS triggering offset in the numerology of CSI-RS according to the higher layer parameter aperiodicTriggeringOffset, and µCSIRS and µPDCCH are the subcarrier spacing configurations for CSI-RS and PDCCH, respectively. If all the associated trigger states do not have the higher layer parameter qcl-Type set to 'QCL-TypeD' in the corresponding TCI states, the CSI-RS triggering offset is fixed to zero. If the PDCCH SCS is smaller than the CSI-RS SCS, the CSI-RS triggering offset is larger than zero. The aperiodic triggering offset of the CSI-IM follows offset of the associated NZP CSI-RS for channel measurement.

For CSI-RS resource sets associated with Resource Settings configured with the higher layer parameter resourceType set to 'aperiodic', 'periodic', or 'semi-persistent', trigger states for Reporting Setting(s) (configured with the higher layer parameter reportConfigType set to 'aperiodic') and/or Resource Setting for channel and/or interference measurement on one or more component carriers are configured using the higher layer parameter CSI-AperiodicTriggerStateList. For aperiodic CSI report triggering, a single set of CSI triggering states are higher layer configured, wherein the CSI triggering states can be associated with any candidate DL BWP. A UE is not expected to receive more than one DCI with non-zero CSI request per slot. A UE is not expected to be configured with different TCI-Stateld's for the same aperiodic CSI-RS resource ID configured in multiple aperiodic CSI-RS resource sets with the same triggering offset in the same aperiodic trigger state. A UE is not expected to receive more than one aperiodic CSI report request for transmission in a given slot. A UE is not expected to be triggered with a CSI report for a non-active DL BWP. A trigger state is initiated using the CSI request field in DCI.

When all the bits of CSI request field in DCI are set to zero, no CSI is requested.

When the number of configured CSI triggering states in CSI-AperiodicTriggerStateList is greater than <NUM>NTS -<NUM>, where NTS is the number of bits in the DCI CSI request field, the UE receives a selection command [<NUM>, TS <NUM>] used to map up to <NUM>NTS -<NUM> trigger states to the codepoints of the CSI request field in DCI. NTS is configured by the higher layer parameter reportTriggerSize where NTS ∈ {<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>}. When the HARQ/ACK corresponding to the PDSCH carrying the selection command is transmitted in the slot n, the corresponding action in [<NUM>, TS <NUM>] and UE assumption on the mapping of the selected CSI trigger state(s) to the codepoint(s) of DCI CSI request field shall be applied starting from slot <MAT>.

When the number of CSI triggering states in CSI-AperiodicTriggerStateList is less than or equal to <NUM>NTS -<NUM>, the CSI request field in DCI directly indicates the triggering state.

For each aperiodic CSI-RS resource in a CSI-RS resource set associated with each CSI triggering state, the UE is indicated the quasi co-location configuration of quasi co-location RS source(s) and quasi co-location type(s), as described in Subclause <NUM>. <NUM>, through higher layer signaling of qcl-info which contains a list of references to TCI-State's for the aperiodic CSI-RS resources associated with the CSI triggering state. If a State referred to in the list is configured with a reference to an RS associated with 'QCL-TypeD', that RS may be an SS/PBCH block located in the same or different CC/DL BWP or a CSI-RS resource configured as periodic or semi-persistent located in the same or different CC/DL BWP.

If the scheduling offset, in the numerology of the aperiodic CSI-RS, between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources in a NZP-CSI-RS-ResourceSet configured without higher layer parameter trs-Info and without the higher layer parameter repetition is smaller than the UE reported threshold beamSwitchTiming, as defined in [<NUM>, TS <NUM>], when the reported value is one of the values of {<NUM>, <NUM>, <NUM>}, if there is any other DL signal with an indicated TCI state in the same symbols as the CSI-RS, the UE applies the QCL assumption of the other DL signal also when receiving the aperiodic CSI-RS. The other DL signal refers to PDSCH scheduled with offset larger than or equal to the threshold timeDurationForQCL, as defined in [<NUM>, TS <NUM>], aperiodic CSI-RS scheduled with offset larger than or equal to the UE reported threshold beamSwitchTiming when the reported values is one of the values {<NUM>,<NUM>,<NUM>}, periodic CSI-RS, semi-persistent CSI-RS.

If the scheduling offset, in the numerology of the aperiodic CSI-RS, between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is equal to or greater than the UE reported threshold beamSwitchTiming when the reported value is one of the values of {<NUM>,<NUM>,<NUM>}, the UE is expected to apply the QCL assumptions in the indicated TCI states for the aperiodic CSI-RS resources in the CSI triggering state indicated by the CSI trigger field in DCI.

A non-zero codepoint of the CSI request field in the DCI is mapped to a CSI triggering state according to the order of the associated positions of the up to <NUM>NTS - <NUM> trigger states in CSI-AperiodicTriggerStateList with codepoint '<NUM>' mapped to the triggering state in the first position.

For a UE configured with the higher layer parameter CSI-AperiodicTriggerStateList, if a Resource Setting linked to a CSI-ReportConfig has multiple aperiodic resource sets, only one of the aperiodic CSI-RS resource sets from the Resource Setting is associated with the trigger state, and the UE is higher layer configured per trigger state per Resource Setting to select the one CSI-IM/NZP CSI-RS resource set from the Resource Setting.

When aperiodic CSI-RS is used with aperiodic reporting, the CSI-RS offset X is configured per resource set by the higher layer parameter aperiodicTriggeringOffset. The CSI-RS triggering offset has the range of <NUM> to <NUM> slots. The UE shall transmit the CSI-RS in slot <MAT>, where n is the slot with the triggering DCI in the numerology of the PDCCH, X is the CSI-RS triggering offset in the numerology of CSI-RS according to the higher layer parameter aperiodicTriggeringOffset, and µCSIRS and µPDCCH are the subcarrier spacing configurations for CSI-RS and PDCCH, respectively. If all the associated trigger states do not have the higher layer parameter qcl-Type set to 'QCL-TypeD' in the corresponding TCI states, the CSI-RS triggering offset is fixed to zero. If the PDCCH SCS is smaller than the CSI-RS SCS, the CSI-RS triggering offset is larger than zero. The aperiodic triggering offset of the CSI-IM follows offset of the associated NZP CSI-RS for channel measurement.

The UE does not expect that aperiodic CSI-RS is transmitted before the OFDM symbol(s) carrying its triggering DCI. If interference measurement is performed on aperiodic NZP CSI-RS, a UE is not expected to be configured with a different aperiodic triggering offset of the NZP CSI-RS for interference measurement from the associated NZP CSI-RS for channel measurement. If the UE is configured with a single carrier for uplink, the UE is not expected to transmit more than one aperiodic CSI report triggered by different DCIs on overlapping OFDM symbols.

Although the subject matter described herein may be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a wireless network, such as the example wireless network illustrated in <FIG>. For simplicity, the wireless network of <FIG> only depicts network <NUM>, network nodes <NUM> and 660b, and WDs <NUM>, 610b, and 610c. In practice, a wireless network may further include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or end device. Of the illustrated components, network node <NUM> and wireless device (WD) <NUM> are depicted with additional detail. The wireless network may provide communication and other types of services to one or more wireless devices to facilitate the wireless devices' access to and/or use of the services provided by, or via, the wireless network.

As used herein, wireless device (WD) refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other wireless devices. Unless otherwise noted, the term WD may be used interchangeably herein with user equipment (UE). Communicating wirelessly may involve transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information through air. In some embodiments, a WD may be configured to transmit and/or receive information without direct human interaction. For instance, a WD may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the network. Examples of a WD include, but are not limited to, a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless cameras, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer-premise equipment (CPE). a vehicle-mounted wireless terminal device, etc.. A WD may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-everything (V2X) and may in this case be referred to as a D2D communication device. As yet another specific example, in an Internet of Things (IoT) scenario, a WD may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another WD and/or a network node. The WD may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the WD may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances (e.g. refrigerators, televisions, etc.) personal wearables (e.g., watches, fitness trackers, etc.). In other scenarios, a WD may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation. A WD as described above may represent the endpoint of a wireless connection, in which case the device may be referred to as a wireless terminal. Furthermore, a WD as described above may be mobile, in which case it may also be referred to as a mobile device or a mobile terminal.

<FIG> illustrates one embodiment of a UE <NUM> in accordance with various aspects described herein. For example, the UE <NUM> may perform embodiments of the method <NUM> and provide other features as described herein.

Network connection interface <NUM> may be configured to provide a communication interface to network 743a. Network 743a may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 743a may comprise a Wi-Fi network.

Storage medium <NUM> may allow UE <NUM> to access computer-executable instructions, application programs or the like, stored on transitory or non-transitory memory media, to offload data, or to upload data.

In <FIG>, processing circuitry <NUM> may be configured to communicate with network 743b using communication subsystem <NUM>. Network 743a and network 743b may be the same network or networks or different network or networks. Communication subsystem <NUM> may be configured to include one or more transceivers used to communicate with network 743b.

Network 743b may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 743b may be a cellular network, a Wi-Fi network, and/or a near-field network.

Access network <NUM> comprises a plurality of base stations 912a, 912b, 912c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 913a, 913b, 913c. Each base station 912a, 912b, 912c is connectable to core network <NUM> over a wired or wireless connection <NUM>. A first UE <NUM> located in coverage area 913c is configured to wirelessly connect to, or be paged by, the corresponding base station 912c. A second UE <NUM> in coverage area 913a is wirelessly connectable to the corresponding base station 912a.

It is noted that host computer <NUM>, base station <NUM> and UE <NUM> illustrated in <FIG> may be similar or identical to host computer <NUM>, one of base stations 912a, 912b, 912c and one of UEs <NUM>, <NUM> of <FIG>, respectively.

Wireless connection <NUM> between UE <NUM> and base station <NUM> is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to UE <NUM> using OTT connection <NUM>, in which wireless connection <NUM> forms the last segment. More precisely, the teachings of these embodiments may improve the operation and performance of a UE using the OTT connection <NUM> to access OTT services.

The measurements may be implemented in that software <NUM> and <NUM> causes messages to be transmitted, in particular empty or 'dummy' messages, using OTT connection <NUM> while it monitors propagation times, errors, etc..

Claim 1:
A method, performed by a user equipment, UE, for receiving an aperiodic channel state information reference signal, CSI-RS, on a
first carrier, wherein the first carrier uses a first orthogonal frequency division multiplexing, OFDM, numerology, the method comprising,
receiving, from a base station, BS, a downlink control information, DCI, message carried by a Physical Downlink Control Channel, PDCCH, on a second carrier, wherein the second carrier uses a second OFDM numerology;
obtaining an aperiodic CSI-RS slot offset from the DCI message;
determining a reference slot in the first OFDM numerology used by the first carrier;
determining the slot of the aperiodic CSI-RS based on the determined reference slot and the aperiodic CSI-RS slot offset; and
receiving, from the BS on the first carrier, the aperiodic CSI-RS in the determined slot and
transmitting, to the BS, a channel state information, CSI, report associated with the CSI-RS, in the determined slot of the aperiodic CSI-RS on the first carrier.