CN115699851A

CN115699851A - Optimization of CSI-RS measurements

Info

Publication number: CN115699851A
Application number: CN202080101737.6A
Authority: CN
Inventors: L·达尔斯加德; 杜蕾; 袁平; 贺敬
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2023-02-03
Also published as: WO2021243708A1

Abstract

Example embodiments of the present disclosure relate to apparatuses, methods, and computer-readable storage media for optimization of channel state indicator reference signal (CSI-RS) measurements. In an example embodiment, a terminal device determines that CSI-RS from a first cell served by a first network device is to be measured. The terminal device sends a measurement start indication to the second network device indicating that measurements of the CSI-RS from the first cell are to be initiated by the terminal device. Further, the terminal device performs a measurement of a channel state indicator reference signal from the first cell.

Description

Optimization of CSI-RS measurements

Technical Field

Example embodiments of the present disclosure relate generally to the field of communications, and, in particular, to an apparatus, method and computer-readable storage medium for optimization of channel state indicator reference signal (CSI-RS) measurements.

Background

Channel state indicator reference signal (CSI-RS) measurements have been designed for separate purposes, including, for example: 1) beam management, and 2) layer 3 (L3) mobility management. CSI-RS based L3 mobility measurements are very important in network deployment and optimization. Compared to Synchronization Signal Block (SSB) based measurements for Radio Resource Management (RRM), CSI-RS based measurements for L3 mobility are more refined and flexible in terms of resource usage, mobility enhancement and handover reliability. Layer 1 (L1) functions and RRC signaling have been introduced for the function of CSI-RS based measurements for RRM. However, corresponding User Equipment (UE) behavior and RRM requirements have not been developed.

Disclosure of Invention

In general, example embodiments of the present disclosure provide devices, methods, and computer-readable storage media for optimization of channel state indicator reference signal (CSI-RS) measurements.

In a first aspect, a terminal device is provided that includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to determine that CSI-RS from a first cell served by the first network device is to be measured. The terminal device is caused to send a measurement start indication to the second network device indicating that measurements of CSI-RS from the first cell are to be initiated by the terminal device. Further, the terminal device is caused to perform a measurement of a channel state indicator reference signal from the first cell.

In a second aspect, a second network device is provided that includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the second network device to receive a measurement start indication from the terminal device indicating that measurements of CSI-RSs from a first cell served by the first network device are to be initiated by the terminal device. The second network device is also caused to send an enablement request to the first network device to enable transmission of at least the CSI-RS in the first cell.

In a third aspect, a first network device is provided that includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the first network device to receive an enablement request from a second network device for enabling transmission of at least CSI-RS in a first cell served by the first network device. The first network device is also caused to send an acknowledgement to the second network device regarding whether transmission of the CSI-RS is enabled in the first cell.

In a fourth aspect, a method implemented at a terminal device is provided. In the method, a terminal device determines that a CSI-RS from a first cell served by a first network device is to be measured. The terminal device sends a measurement start indication to the second network device indicating that measurements of the CSI-RS from the first cell are to be initiated by the terminal device. Further, the terminal device performs a measurement of a channel state indicator reference signal from the first cell.

In a fifth aspect, a method implemented at a second network device is provided. In the method, the second network device receives a measurement start indication from the terminal device indicating that measurements of CSI-RSs from a first cell served by the first network device are to be initiated by the terminal device. The second network device also sends an enabling request to the first network device for enabling transmission of at least the CSI-RS in the first cell.

In a sixth aspect, a method implemented at a first network device is provided. In the method, a first network device receives, from a second network device, an enablement request to enable transmission of at least CSI-RS in a first cell served by the first network device. The first network device also sends an acknowledgement to the second network device regarding whether transmission of the CSI-RS is enabled in the first cell.

In a seventh aspect, there is provided an apparatus comprising means for performing the method according to the fourth, fifth or sixth aspect.

In an eighth aspect, a computer-readable storage medium comprising program instructions stored thereon is provided. The instructions, when executed by a processor of an apparatus, cause the apparatus to perform the method according to the fourth, fifth or sixth aspect.

It should be understood that the summary is not intended to identify key or essential features of the example embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

Some example embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example environment in which example embodiments of the present disclosure may be implemented;

figure 2 illustrates a signaling flow between a terminal device and two network devices, according to some example embodiments of the present disclosure;

fig. 3 illustrates an example process for initiating CSI-RS measurements and transmissions, in accordance with some example embodiments of the present disclosure;

fig. 4 illustrates an example process for stopping CSI-RS measurements and transmissions, in accordance with some example embodiments of the present disclosure;

fig. 5 shows a flow diagram of an example method according to some example embodiments of the present disclosure;

fig. 6 shows a flowchart of an example method according to some other example embodiments of the present disclosure;

fig. 7 shows a flowchart of an example method according to some other example embodiments of the present disclosure; and

fig. 8 shows a simplified block diagram of an apparatus suitable for implementing an example embodiment of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is understood that these example embodiments are described merely to illustrate and assist those of ordinary skill in the art in understanding and enabling the disclosure, and are not intended to limit the scope of the disclosure in any way. The disclosure described herein may be implemented in a variety of other ways besides those described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

As used herein, the term "terminal device" or "user equipment" (UE) refers to any terminal device capable of wireless communication with each other or a base station. Communication may involve the transmission and/or reception of wireless signals using electromagnetic signals, radio waves, infrared signals, and/or other types of signals suitable for the transmission of information over the air. In some example embodiments, the UE may be configured to transmit and/or receive information without direct human-machine interaction. For example, when triggered by an internal or external event, or in response to a request from the network side, the UE may transmit information to the base station according to a predetermined schedule.

Examples of UEs include, but are not limited to, smart phones, wireless enabled tablets, laptop embedded devices (LEEs), laptop installed devices (LMEs), wireless client devices (CPEs), sensors, metering devices, personal wearable devices such as watches, and/or vehicles capable of communication. For discussion purposes, some example embodiments will be described with reference to a UE as an example of a terminal device, and the terms "terminal device" and "user equipment" (UE) may be used interchangeably in the context of this disclosure. The UE may also correspond to a Mobile Termination (MT) portion of an Integrated Access and Backhaul (IAB) node (also referred to as a relay node).

As used herein, the term "network device" refers to a device via which services may be provided to terminal devices in a communication network. As an example, the network device may include a base station. As used herein, the term "base station" (BS) refers to a network device via which services may be provided to terminal devices in a communication network. A base station may comprise any suitable device via which a terminal device or UE may access a communication network. Examples of a base station include a relay, an Access Point (AP), a transmission point (TRP), a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), a New Radio (NR) NodeB (gNB), a remote radio module (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a low power node such as femto, pico, etc. The relay node may correspond to a Distributed Unit (DU) portion of the IAB node.

As used herein, the term "cell" refers to an area covered, served, or provided by a network device. One network device may serve one or more cells, and each cell may include one or more carriers.

As used herein, the term "serving network device" refers to a network device that serves a terminal device. The term "neighboring network device" refers to a network device that is adjacent or proximate to the serving network device. The term "serving cell" refers to a cell provided by a serving network device and serving a terminal device. The term "neighboring cell" refers to a cell that is adjacent or close to the serving cell and is provided by a neighboring network device.

As used herein, the term "circuitry" may refer to one or more or all of the following:

(a) A purely hardware circuit implementation (such as an implementation using only analog and/or digital circuitry), and

(b) A combination of hardware circuitry and software, such as (as applicable):

(i) Combinations of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Hardware processor(s) with software (including digital signal processor (s)), software and any portion of memory(s) that work together to cause a device, such as a mobile phone or server, to perform various functions, and

(c) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or a portion of microprocessor(s), that require software (e.g., firmware) for operation, but software may not be present when operation is not required.

The definition of circuitry is suitable for all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also encompasses implementations of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. For example, the term circuitry, if applicable to a particular claim element, also encompasses a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular base station, or other computing or base station.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "includes" and variations thereof should be understood as an open term meaning "including, but not limited to". The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". Other definitions (explicit and implicit) may be included below.

As used herein, the terms "first," "second," and the like may be used herein to describe various elements, which should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

For example, RRM requirements for CSI-RS based L3 measurements include the least required CSI-RS measurement bandwidth, intra-and inter-frequency definitions, intra-and inter-frequency measurement requirements, accuracy assessment and specification, and additional UE measurement capabilities, including the number of frequency layers and the number of cells. Further, in terms of assumptions regarding synchronization, for intra-frequency and inter-frequency measurements, a single Fast Fourier Transform (FFT) is assumed for multiple cell measurements per frequency layer.

For CSI-RS based L3 measurements, the defined CSI-RS measurement configuration framework allows no more than 96 CSI-RS resources per MO when all CSI-RS resources configured by a Measurement Object (MO) have been configured to have an associated SSB, while the defined CSI-RS measurement configuration framework allows no more than 64 CSI-RS resources per MO when all CSI-RS resources are configured to have no associated SSB, or when only some CSI-RS resources have been configured by the same MO to have an associated SSB. Furthermore, all CSI-RS resources in the same MO should have the same center frequency and the same subcarrier spacing (SCS).

Currently, for CSI-RS based L3 measurements, the UE may be configured with CSI-RS resources to be measured in the neighbor cells, e.g., via the message CSI-RS-ResourceConfigMobility. However, on the network side, it is challenging to control when and how to configure and indicate appropriate or correct CSI-RS resources from neighboring cells to enable UE measurements. For example, in a New Radio (NR), CSI-RS resources to be measured are configured for each UE. When the UE is performing CSI-RS based neighbor cell measurements, there may not be any CSI-RS transmitted from the neighbor cells.

In addition, the CSI-RS resources in the neighboring cells are dynamically allocated and released. The CSI-RS transmission is managed regardless of whether the CSI-RS is measured by any UE. The CSI-RS resources that the UE is measuring may suddenly disappear, causing the measurement to be interrupted or even fail. Furthermore, CSI-RS may be transmitted in a cell for measurement, but no UE performs measurements on the transmitted CSI-RS resources, which results in potentially significant reference signal overhead and resource waste.

Furthermore, bandwidth part (BWP) switching in NR allows the UE to switch its operating BWP from time to time. If the CSI-RS resources used in the neighboring cell do not fall within the active BWP of the UE, the UE is neither able to measure CSI-RS nor perform measurements on the CSI-RS resources in the neighboring cell (no measurement gaps).

It is unpredictable which and how many CSI-RS signals the UE is to measure. The network may indicate all available CSI-RS resources to the UE. However, there may be a large number of CSI-RSs transmitted in neighboring cells. For example, resource exchange of all CSI-RSs from the neighbor cell to the serving cell may result in a large signaling overhead over interface Xn. Furthermore, the indication of the resources of all CSI-RSs to the UE may result in a large signaling overhead over the air interface.

The CSI-RS transmissions from the cells are arranged at the network side without regard to UE requirements. For example, the CSI-RI resources in the neighboring cells may be configured in an operation administration and maintenance configuration. In addition, the CSI-RS resource configurations may be exchanged at the cell level. For example, the CSI-RS configuration of L3 measurements may be exchanged between two gnbs/cells during Xn setup and may be updated during next generation radio access network (NG-RAN) node configuration update in NG-RAN scenarios. Alternatively or additionally, the exchange of CSI-RS resource configurations may be triggered based on a request from the serving gNB.

However, as described above, the CSI-RS is always configured for the UE, not for the cell. It is desirable to configure appropriate CSI-RS resources for each UE for CSI-RS measurements in the neighboring cells, to enable the UE to detect the CSI-RS resources and perform associated measurements in the neighboring cells.

Example embodiments of the present disclosure provide a new scheme to enable efficient CSI-RS measurement configuration and associated CSI-RS transmission. With this scheme, if the terminal device determines that the CSI-RS is to be measured in a cell (referred to as a first cell, e.g., a neighboring cell) served by a network device (referred to as a first network device, e.g., a neighboring gNB), the terminal device sends a measurement start indication to a different network device (referred to as a second network device, e.g., a serving gNB) serving a different cell (e.g., a serving cell). Alternatively, if it cannot be detected, the terminal device transmits a measurement start indication. The measurement start indication informs the second network device that CSI-RS measurements from the first cell are to be initiated by the terminal device. The terminal device then performs CSI-RS measurements in the first cell.

On the network side, after the second network device receives the measurement start indication from the terminal device, the second network device sends an enabling request for enabling CSI-RS transmission in the first cell to the first network device. The first network device sends an acknowledgement to the second network device regarding whether CSI-RS transmission is enabled in the first cell.

This scheme allows a cell to request CSI-RS resources of neighboring cells for a served UE. It also allows a cell to manage CSI-RS resource allocation and CSI-RS transmission based on requests from neighboring cells. In this way, CSI-RS measurements may be more efficient at the UE side. Furthermore, transmission of CSI-RS for measurement may be more efficient at the network side.

FIG. 1 illustrates an example environment 100 in which example embodiments of the present disclosure may be implemented.

Environment 100, which may be part of a communication network, includes a terminal device 110 and two network devices 120 and 130 (referred to as first network device 120 and second network device 130, respectively). The number of devices shown in fig. 1 is for illustrative purposes only and does not imply any limitation. Environment 100 may include any suitable number of terminal devices and network devices.

As shown, a first network device 120 serves a cell 140 and a second network device 130 serves a cell 150. For purposes of discussion, the two

cells

140 and 150 will be referred to as a first cell 140 and a second cell 150, respectively. The number of cells provided by

network device

120 or 130 shown in fig. 1 is for illustration purposes only and does not imply any limitation. One of

network devices

120 and 130 may provide one or more carriers, each carrier including one or more cells.

Terminal device 110 may communicate with first network device 120 and/or second network device 130. The communication may follow any suitable communication standard or protocol that already exists or is developed in the future, such as Universal Mobile Telecommunications System (UMTS), long Term Evolution (LTE), LTE-advanced (LTE-a), fifth generation (5G) New Radio (NR), wireless fidelity (Wi-Fi), and Worldwide Interoperability for Microwave Access (WiMAX) standards, and employ any suitable communication technology including, for example, multiple-input multiple-output (MIMO), orthogonal Frequency Division Multiplexing (OFDM), time Division Multiplexing (TDM), frequency Division Multiplexing (FDM), code Division Multiplexing (CDM), bluetooth, zigBee, machine Type Communication (MTC), enhanced mobile broadband (eMBB), large scale Machine Type Communication (MTC), ultra-reliable low latency communication (URLLC), carrier Aggregation (CA), dual Connectivity (DC), and new radio license-free (NR-U) technologies.

The two

network devices

120 and 130 may communicate with each other in a wired or wireless manner. Communication between

network devices

120 and 130 may conform to any suitable communication standard or protocol that already exists or is developed in the future.

In some example embodiments, terminal device 110 may be served by second network device 130 in second cell 150. The first network device 120 is a neighboring network device and the first cell 140 is a neighboring cell. It is also possible that the first network device 120 is a serving network device and the first cell 140 is a serving cell.

Terminal device 110 may perform CSI-RS measurements in either or both of first cell 140 and second cell 150. In various example embodiments, when the terminal device 110 is to initiate CSI-RS measurements in a first cell 140 (e.g., a neighboring cell), the terminal device 110 sends a measurement start indication to a second network device 130 (e.g., a serving network device) indicating that CSI-RS measurements are to be initiated in the first cell 140. Further, the second network device 130 sends a request to the first network device 120 to enable CSI-RS transmission in the first cell 140. Accordingly, the first network device 120 sends an acknowledgement to the second network device as to whether CSI-RS transmission is enabled in the first cell 140.

Fig. 2 illustrates a signaling flow 200 between terminal device 110 and first network device 120 and second network device 130, according to some example embodiments of the present disclosure. For purposes of discussion, signaling flow 200 will be described with reference to fig. 1.

As shown in fig. 2, terminal device 110 determines (205) that the CSI-RS from first cell 140 is to be measured. In some example embodiments, the event for triggering initiation of CSI-RS measurements may be used by terminal device 110 to make the above determination. For example, a threshold value related to the received signal strength or power level of the CSI-RS may be used to trigger CSI-RS measurements in the first cell 140. For example, in an example embodiment in which the first cell 140 is a neighboring cell and the second cell 150 is a serving cell, the terminal device 110 may determine to initiate CSI-RS measurements in the first cell 140 as a neighboring cell if a Reference Signal Received Power (RSRP) and/or a Reference Signal Received Quality (RSRQ), e.g. CSI-RS, in the second cell 150 as a serving cell is below a configured threshold.

In some example embodiments, the initiation of CSI-RS measurements may be associated with other measurements. For example, CSI-RS measurements may be triggered based on measurements of synchronization signal block (SS block or SSB) measurements. SSBs, including, for example, primary Synchronization Signals (PSS) and Secondary Synchronization Signals (SSS), may allow terminal devices to achieve initial system acquisition, including, for example, initial time synchronization (such as symbol and frame timing), initial frequency synchronization, and cell acquisition (such as a physical cell ID of a cell). The SSB may be transmitted through beam scanning to cover the entire area of the cell. Based on the SSB measurements, the terminal device may find the best or strongest beam. The CSI-RS may be transmitted via a narrower set of transmission beams than the beams of the SSB, as compared to the SSB. If the SSB measurements are not sufficient to detect a better or finer beam, the CSI-RS measurements may be triggered to find the best beam. In this example, if the metric associated with the SSB measurements in one or both of the first cell 140 and the second cell 150 is below, for example, a set threshold, the terminal device 110 may determine that CSI-RS measurements are to be performed to further optimize RRM. The metrics associated with the SSB measurements may include, for example, RSRP, RSRQ, or other metrics of the SSB.

The threshold may be used for comparison with the metric. The threshold may be static, semi-static, or dynamic. For example, the threshold may be configured to terminal device 110 through the network. In some example embodiments, terminal device 110 may obtain the threshold from second network device 130 (e.g., the serving network device) via higher layer signaling. The indication of the threshold may reuse existing signaling following the 3GPP standard. For example, a Control Element (CE) s-Measure may be used to indicate a threshold. Terminal device 110 may determine the initiation of the CSI-RS measurement if the RSRP of the SSB is below a threshold indicated by the s-Measure.

Any other measurements may also be considered to determine the initiation of the CSI-RS. For example, measurements based on a physical broadcast control channel (PBCH), demodulation reference signal (DMRS), etc., may be used to determine whether CSI measurements are to be initiated. Alternatively, one or more existing measurement events may be used.

Upon determining that the CSI-RS from the first cell 140 is to be measured, the terminal device 110 sends (210) a measurement start indication to the second network device 130, the measurement start indication indicating that CSI-RS measurements are to be initiated for the first cell 140. The measurement start indication may be triggered based on the availability or detectability of CSI-RS from the first cell 140. For example, if the terminal device 110 cannot detect an available CSI-RS from the first cell 140, the terminal device 110 may send a measurement start indication to the second network device 130. As another example, terminal device 110 may send a measurement start indication if the CSI-RS from first cell 140 disappears when terminal device 110 performs CSI-RS measurements.

In some example embodiments, the triggering of the measurement start indication may be configured by the network. For example, the network may configure terminal device 110 whether it needs to notify the network when performing CSI-RS measurements. The configuration related to the triggering of the measurement start indication may be indicated to the terminal device together with the necessary configuration of CSI-RS L3 measurements. For example, when the second network device 130 (e.g., serving network device) configures CSI-RS measurements to the terminal device 110 in the second cell 150 (e.g., serving cell), the second network device 130 may configure whether the terminal device 110 should report when performing CSI-RS measurements in the first cell 140 and/or the second cell 150. In this way, CSI-RS measurements may be more flexible and efficient at terminal device 110, and CSI-RS transmissions may be more flexible and efficient at the network side.

The sending of the measurement start indication may reuse (reuse) existing messages or signaling. For example, in example embodiments where initiation of CSI-RS measurements is triggered based on SSB measurements, the measurement start indication may be implicitly or explicitly carried in the measurement report of the SSB measurements. Other reports or messages may be used and a new report or message may be defined for the measurement start indication.

In some example embodiments, the measurement start indication may include further details related to the target cell to be measured by the terminal device 110. For example, the indication may indicate a cell Identification (ID) of the first cell 130, an index of an SSB associated with the CSI-RS (if available), CSI-RS resources in time and/or frequency domain, a CSI-RS index (if available), a bandwidth of the CSI-RS resources, and other information related to CSI-RS measurements.

Upon receiving the measurement start indication from the terminal device 110, the second network device 130 sends (215) an enabling request to the first network device 120 for enabling transmission of the one or more CSI-RSs to be measured by the terminal device in the first cell 140. The activation request may indicate (or include) information related to the CSI-RS and/or the first cell 140 to be measured.

Further, the enablement request may include information related to CSI-RSs of other cells to be measured by other terminal devices served by the second device 130. For example, the activation request may indicate a list of carriers in the at least first cell 140 for measurement of a set of CSI-RS comprising CSI-RS to be measured by the terminal device. The request may also indicate a list of cells (including the first cell 140), a list of active bandwidth parts (BWPs) in the second cell 150, etc., for measurements of the set of CSI-RSs. For CSI-RS with an associated SSB, the request may indicate an index list of the associated SSB. The network requests transmission of the CSI-RS resource associated with the SSB having the index. In this way, the second device 130 may more efficiently inform the first device 120 of the CSI-RS measurement requirements of the served terminal devices.

In some example embodiments, the second network device 130 may first check whether there are available resources for CSI-RS measurements before sending the enabling request. For example, the second network device 130 may check whether the relevant CSI-RS resources are stored locally. If the relevant CSI-RS resource is not stored, the second network device 130 may send an enablement request to the first network device 120 to cause the first network device 120 to allocate the CSI-RS resource.

In some example embodiments, the CSI-RS resources may be previously allocated by the first network device 120 and exchanged between the first network device 120 and the second network device 130. For example, in an example embodiment where both the first network device 120 and the second network device 130 are implemented by a gNB, CSI-RS resources may be exchanged between the two

network devices

120 and 130 during an Xn setup procedure. If the CSI resources are not allocated during the Xn setup procedure, the relevant CSI-RS resources may not be locally detectable. Accordingly, the second network device 130 may send an enable request via an Xn interface with the first network device 120 to cause the first network device 120 to allocate CSI-RS resources. The second device 130 may send an enabling request to cause the first network device 120 to transmit CSI-RS in the first cell 140 if CSI-RS resources have been reserved or allocated during the Xn setup procedure.

After receiving the enablement request from the second network device 130, the first network device 120 sends (220) an acknowledgement to the second network device 130 regarding whether the CSI-RS transmission is enabled in the first cell 140. For example, in the case where the CSI-RS resources are not pre-allocated, the first network device 120 may allocate the CSI-RS resources and transmit the CSI-RS on the resources. Alternatively, the first network device 120 may refuse to allocate CSI-RS resources, or may release the allocated CSI-RS resources due to limited resources in its own cell(s).

The acknowledgement may indicate any suitable information related to the decision of first network device 120. For example, the acknowledgement may indicate a resource list of a set of CSI-RS on one or more carriers in at least the first cell 140, the set of CSI-RS including the CSI-RS requested by the second network device 130. The acknowledgement may also indicate an enabled or disabled status list of resources for the set of CSI-RS, and an index list of SSBs associated with the set of CSI-RS (if available). Thus, the second network device 130 may store all received CSI-RS resources and corresponding states. When needed, the second network device 130 may configure the CSI-RS resource to the terminal device, e.g., via the message CSI-RS-ResourceConfigMobility.

In some example embodiments, the acknowledgement may indicate at least a validity duration of one of the resources for the set of CSI-RS. Based on the validity duration, the second device 130 may determine the validity of the corresponding CSI resource. For example, the second network device 150 may run a validity timer for the corresponding CSI-RS resource. When the validity timer for the CSI-RS resource expires, the second device 130 may determine that the CSI-RS resource is invalid. If there are still ongoing CSI-RS measurements of the terminal device on the CSI-RS resource, the second network device 130 may send a request to the first network device 120 to maintain the CSI-RS transmission, requesting maintenance of the "enabled state" of the CSI-RS resource. If CSI-RS measurements are required to be configured to a further terminal device and the corresponding CSI-RS resource is still valid (e.g. the validity timer has not expired), the second network device 130 may configure the corresponding CSI/RS resource to the further terminal device, e.g. via the message CSI-RS-ResourceConfigMobility.

In this example, the first network device 120 acknowledges enabling CSI-RS transmission. As shown in fig. 2, after sending (220) the acknowledgement, the first network device 120 may transmit (225) the CSI-RS in the first cell 140. At the terminal device 110, the CSI-RS measurements are performed (230) in the first cell 140 after the measurement start indication is sent (210) to the second network device 130. Since CSI-RS transmission in the first cell 140 is enabled based on the needs of the terminal device 110, measurement of CSI-RS may be more efficient at the terminal device 110.

In addition to the measurement start indication that the terminal device 110 starts performing CSI-RS measurements, the terminal device 110 may also send (235) a measurement stop indication to the second network device 130 indicating that CSI-RS measurements are to be stopped in the first cell 140. For example, when the CSI-RS measurement is completed or other suitable event occurs, terminal device 110 may determine that the CSI-RS measurement is to be stopped and send a measurement stop indication.

Accordingly, the second network device 130 may send (240) a disable request to the first network device 120 to disable CSI-RS transmissions. In some example embodiments, the second network device 130 may first check whether CSI-RS measurements in the first cell 140 are still needed by other terminal devices before sending the disabling request. If not, second network device 130 may send a disable request to first network device 120.

In response to the disabling request, the first network device 120 may determine (245) whether to cease CSI-RS transmission in the first cell 140. For example, the first network device 120 may locally check whether other network devices still request CSI-RS transmissions. If not, first network device 120 may disable CSI-RS transmission. The first network device 120 may reply to the second network device 130 with an acknowledgement that CSI-RS transmission is to be disabled. In this way, multiple requests by one or more network devices for different terminal devices are not required, a single request may ensure that CSI-RS resources are used for all terminal devices configured with CSI-RS L3 measurements.

Fig. 3 illustrates an example process 300 for initiating CSI-RS measurements and transmissions, in accordance with some example embodiments of the present disclosure.

In process 300, terminal device 110 communicates with second network device 130, e.g., in a connected mode (305). The second network device 130 sends (310) a measurement configuration comprising a CSI-RS configuration to the terminal device 110. In this example, as shown, the CSI-RS configuration includes s-Measure indicating a threshold value related to SSB measurement. The terminal device 110 performs (315) SSB measurements in the first cell 140 and the second cell 150.

Terminal device 110 detects (320) that the received signal level of the SSB in second cell 150 is below the level indicated by s-Measure. The terminal device 110 triggers (325) the initiation of the CSI-RS measurements in the first cell 140. The terminal device 110 sends (330) a measurement report to the second network device 130, the measurement report comprising a measurement start indication indicating that CSI-RS measurements are to be initiated by the terminal device 110 for the first cell 140. Terminal device 110 may then immediately begin (435) CSI-RS measurements, as shown in fig. 3. Terminal device 110 may also initiate CSI-RS measurements after receiving a resource indication of CSI-RS measurements from second network device 130.

After receiving the measurement start indication, the second network device 130 sends (340) an enabling request to the first network device 120 for enabling CSI-RS transmission in the first cell 140. The first network device 120 sends (345) an acknowledgement to the second network device 130 as to whether CSI-RS transmission is enabled in the first cell 140. In this example, the acknowledgement, i.e., CSI-RS transmission, is enabled by the first network device 120 in the first cell 140. The CSI-RS is then transmitted (350) by the first network device 120 and the second network device 130. Terminal device 110 performs (355) the SSB and CSI-RS measurements.

Fig. 4 illustrates an example process 400 for stopping CSI-RS measurements and transmissions, according to some example embodiments of the present disclosure.

In process 400, terminal device 110 performs (405) SSB and CSI-RS measurements. The terminal device 110 detects (410) that the received signal level of the SSB or CSI-RS in the second cell 150 is above the level indicated by s-Measure. The terminal device 110 sends (415) a measurement report to the second network device 130, the measurement report comprising a measurement stop indication indicating that CSI-RS measurements are to be stopped by the terminal device 110 in the first cell 140. Terminal device 110 may then immediately stop (420) CSI-RS measurements.

The second network device 130 sends (425) a disable request to the first network device 120 for disabling CSI-RS transmission. The first network device 120 sends (430) an acknowledgement to the second network device 130 as to whether the CSI-RS transmission is to be ceased. In this example, the acknowledgement indicates that the CSI-RS transmission will not be ceased. The CSI-RS signal is still transmitted by the first network device 120 and the second network device 130 (435).

Fig. 5 illustrates a flow chart of an example method 500, according to some example embodiments of the present disclosure. Method 500 may be implemented at terminal device 110 as shown in fig. 1. For discussion purposes, the method 500 will be described with reference to fig. 1.

At block 505, the terminal device 110 determines that CSI-RS from the first cell 140 served by the first network device 120 is to be measured. At block 510, the terminal device 110 sends a measurement start indication to the second network device 130 indicating that measurements of CSI-RS from the first cell 140 are to be initiated by the terminal device 110. At block 515, the terminal device 110 performs measurements of the CSI-RS from the first cell 140.

Fig. 5 illustrates a flow diagram of an example method 500, according to some example embodiments of the present disclosure. Method 500 may be implemented at terminal device 110 as shown in fig. 1. For discussion purposes, the method 500 will be described with reference to fig. 1.

At block 505, the terminal device 110 determines that CSI-RS from the first cell 140 served by the first network device 120 is to be measured. At block 510, the terminal device 110 sends a measurement start indication to the second network device 130 indicating that measurements of CSI-RS from the first cell 140 are to be initiated by the terminal device 110. At block 515, terminal device 110 performs measurements of CSI-RS from first cell 140.

Fig. 6 illustrates a flow chart of an example method 600, according to some example embodiments of the present disclosure. The method 600 may be implemented at the second network device 130 as shown in fig. 1. For discussion purposes, the method 600 will be described with reference to fig. 1.

At block 605, the second network device 130 receives a measurement start indication from the terminal device 110 indicating that measurements of CSI-RSs from the first cell 140 served by the first network device 120 are to be initiated by the terminal device 110. At block 610, the second network device 130 sends an enablement request to the first network device 120 for enabling transmission of at least the CSI-RS in the first cell 140.

Fig. 7 illustrates a flow chart of an example method 700, according to some example embodiments of the present disclosure. Method 700 may be implemented at first network device 120 as shown in fig. 1. For discussion purposes, the method 700 will be described with reference to fig. 1.

At block 705, the first network device 120 receives an enablement request from the second network device 130 for enabling transmission of at least CSI-RS in a first cell 140 served by the first network device 120. At block 710, the first network device 120 sends an acknowledgement to the second network device 130 regarding whether transmission of the CSI-RS is enabled in the first cell 140.

All of the operations and features described above with reference to fig. 1-4 are equally applicable to

methods

500, 600, and 700 and have similar effects. Details will be omitted for simplicity.

Fig. 8 is a simplified block diagram of a device 800 suitable for implementing an example embodiment of the present disclosure. Device 800 may be implemented at or as part of terminal device 110, first network device 120, or second network device 130 as shown in fig. 1.

As shown, the device 800 includes a processor 810, a memory 820 coupled to the processor 810, a communication module 830 coupled to the processor 810, and a communication interface (not shown) coupled to the communication module 830. The memory 820 stores at least a program 840. The communication module 830 is used for bi-directional communication, e.g., via multiple antennas or via a cable. The communication interface may represent any interface required for communication.

The program 840 is assumed to include program instructions that, when executed by the associated processor 810, enable the device 800 to operate in accordance with example embodiments of the present disclosure, as discussed herein with reference to fig. 1-7. The example embodiments herein may be implemented by computer software executable by the processor 810 of the device 800, or by hardware, or by a combination of software and hardware. The processor 810 may be configured to implement various example embodiments of the present disclosure.

The memory 820 may be of any type suitable to the local technology network and may be implemented using any suitable data storage technology, such as non-transitory computer readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 820 is shown in device 800, there may be several physically distinct memory modules in device 800. The processor 810 may be of any type suitable to the local technology network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. Device 800 may have multiple processors, such as application specific integrated circuit chips that are time-dependent from a clock synchronized to the main processor.

When device 800 is acting as terminal device 110, processor 810 may implement the operations or actions of terminal device 110 described above with reference to fig. 1-5. When the device 800 is acting as the second network device 130, the processor 810 may implement the operations or actions of the second network device 130 described above with reference to fig. 1-4 and 6. When device 800 is acting as first network device 120, processor 810 may implement the operations or actions of first network device 120 described above with reference to fig. 1-4 and 7. All of the operations and features described above with reference to fig. 1-7 are equally applicable to the device 800 and have similar effects. Details will be omitted for simplicity.

In general, the various example embodiments of this disclosure may be implemented using hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the example embodiments of this disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product comprises computer executable instructions, such as instructions comprised in program modules, that are executed in a device on a target real or virtual processor to perform the operations and actions as described above with reference to fig. 1 to 7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. Machine-executable instructions of program modules may be executed within local or distributed devices. In a distributed arrangement, program modules may be located in both local and remote memory storage media.

Program code for performing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are described in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Also, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular example embodiments. Certain features that are described in the context of separate example embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple example embodiments separately or in any suitable subcombination.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Various example embodiments of the technology have been described. In addition to or in place of the foregoing, the following embodiments are described. Features described in any of the examples below may be used with any of the other examples described herein.

In some aspects, a terminal device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the terminal device to: determining that a channel state indicator reference signal from a first cell served by a first network device is to be measured; sending a measurement start indication to a second network device, the measurement start indication indicating that measurements of the channel state indicator reference signals from the first cell are to be initiated by the terminal device; and performing the measurement of the channel state indicator reference signal from the first cell.

In some example embodiments, the terminal device is caused to transmit the measurement start indication by: transmitting the measurement start indication to the second network device based on a measurement configuration from the second network device indicating that the measurement start indication is to be transmitted by the terminal device.

In some example embodiments, the terminal device is caused to determine that the channel state indicator reference signal from the first cell is to be measured by: in accordance with a determination that a metric associated with a measurement of a synchronization signal block in at least one of a second cell served by the second network device and the first cell is below a threshold, determining that the channel state indicator reference signal from the first cell is to be measured.

In some example embodiments, the terminal device is caused to transmit the measurement start indication by: in accordance with a determination that a channel state indicator reference signal from the first cell is undetectable, sending the measurement start indication to the second network device.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured; a resource for the channel state indicator reference signal to be measured; or an index of the channel state indicator reference signal.

In some example embodiments, the terminal device is further caused to: sending a measurement stop indication to the second network device, the measurement stop indication indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device.

In some example embodiments, the terminal device is caused to perform the measurement of the channel state indicator reference signal from the first cell by: receiving, from the second network device, a resource indication for resources of the channel state indicator reference signal; and performing the measurement of the channel state indicator reference signal on the resource.

In some aspects, a second network device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the second network device to: receiving a measurement start indication from a terminal device, the measurement start indication indicating that measurements of channel state indicator reference signals from a first cell served by a first network device are to be initiated by the terminal device; and sending an enabling request to the first network device, the enabling request for enabling transmission of at least the channel state indicator reference signal in the first cell.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured by the terminal device; a resource for the channel state indicator reference signal; or an index of the channel state indicator reference signal.

In some example embodiments, the enabling request indicates at least one of: a carrier list in at least the first cell for measurements of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising the channel state indicator reference signals to be measured by the terminal device; a list of cells for the measurements of the set of channel state indicator reference signals, the cells including the first cell; a list of active bandwidth parts in a second cell served by the second network device; or an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals.

In some example embodiments, the second network device is further caused to: receiving an acknowledgement from the first network device as to whether the transmission of at least the channel state indicator reference signal in the first cell is enabled by the first network device.

In some example embodiments, the acknowledgement indicates at least one of: a resource list for a set of channel state indicator reference signals on one or more carriers in at least the first cell, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device; an enabled or disabled status list of the resources for the set of channel state indicator reference signals; an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals; or at least a validity duration of one of the resources for the set of channel state indicator reference signals.

In some example embodiments, the acknowledgement indicates a validity duration of resources for the channel state indicator reference signal requested by the second network device, and the second network device is further caused to: determining that the measurement of the channel state indicator reference signal is to continue after the validity duration expires; and sending a request to the first network device to maintain the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the second network device is further caused to: receiving a measurement start indication from a further terminal device, the measurement start indication indicating that the channel state indicator reference signal from the first cell is to be measured by the further terminal device; and in accordance with a determination that the validity duration has not expired, sending a resource indication of the resources for the channel state indicator reference signal to the further terminal device.

In some example embodiments, the second network device is further caused to: receiving a measurement stop indication from the terminal device indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device; and transmitting a disabling request to the first network device, the disabling request to disable the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the second network device is caused to send the disable request by: determining, after the reception of the measurement stop indication, that the measurement of the channel state indicator reference signal from the first cell is not requested by a further terminal device; and sending the disable request to the first network device.

In some aspects, a first network device, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the first network device to: receiving an enabling request from a second network device, the enabling request for enabling transmission of at least a channel state indicator reference signal in a first cell served by the first network device; and sending an acknowledgement to the second network device as to whether the transmission of the channel state indicator reference signal is enabled in the first cell.

In some example embodiments, the enabling request indicates at least one of: a carrier list in at least the first cell for measurements of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device; a cell list for the measurements of the set of channel state indicator reference signals, including the first cell; a list of active bandwidth parts in a second cell served by the second network device; or an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals.

In some example embodiments, the acknowledgement indicates at least one of: a resource list for a set of channel state indicator reference signals on one or more carriers in at least the first cell, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device; a list of enabled or disabled states of the resources of the set of channel state indicator reference signals; an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals; or at least a validity duration of one of the resources for the set of channel state indicator reference signals.

In some example embodiments, the first network device is further caused to: receiving a disabling request from the second network device for disabling the transmission of the channel state indicator reference signals in the first cell; and ceasing the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the first network device is caused to: determining, subsequent to the receipt of the disable request, that the transmission of the channel state indicator reference signal is not requested by another network device; and ceasing the transmission of the channel state indicator reference signal in the first cell.

In some aspects, a method implemented at a terminal device, comprising: determining that a channel state indicator reference signal from a first cell served by a first network device is to be measured; sending a measurement start indication to a second network device, the measurement start indication indicating that measurements of the channel state indicator reference signals from the first cell are to be initiated by the terminal device; and performing the measurement of the channel state indicator reference signal from the first cell.

In some example embodiments, sending the measurement start indication comprises: transmitting the measurement start indication to the second network device based on a measurement configuration from the second network device indicating that the measurement start indication is to be transmitted by the terminal device.

In some example embodiments, determining that the channel state indicator reference signal from the first cell is to be measured comprises: in accordance with a determination that a metric associated with a measurement of a synchronization signal block in at least one of a second cell served by the second network device and the first cell is below a threshold, determining that the channel state indicator reference signal from the first cell is to be measured.

In some example embodiments, sending the measurement start indication comprises: in accordance with a determination that a channel state indicator reference signal from the first cell is undetectable, sending the measurement start indication to the second network device.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured; resources for the channel state indicator reference signal; or an index of the csi-rs reference signal.

In some example embodiments, the method further comprises: sending a measurement stop indication to the second network device, the measurement stop indication indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device.

In some example embodiments, performing the measurement of the channel state indicator reference signal from the first cell comprises: receiving, from the second network device, a resource indication for the resources of the channel state indicator reference signal; and performing the measurement of the channel state indicator reference signal on the resource.

In some aspects, a method implemented at a second network device, comprising: receiving a measurement start indication from a terminal device, the measurement start indication indicating that measurements of channel state indicator reference signals from a first cell served by a first network device are to be initiated by the terminal device; and sending an enabling request to the first network device, the enabling request enabling transmission of at least the channel state indicator reference signal in the first cell.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured by the terminal device; resources for the channel state indicator reference signal; or an index of the csi-rs reference signal.

In some example embodiments, the method further comprises: receiving an acknowledgement from the first network device as to whether the transmission of at least the channel state indicator reference signal in the first cell is enabled by the first network device.

In some example embodiments, the acknowledgement indicates a validity duration of resources of the channel state indicator reference signal requested by the second network device, and the method further comprises: determining that the measurement of the channel state indicator reference signal is to continue after the validity duration expires; and sending a request to the first network device to maintain the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the method further comprises: receiving a measurement start indication from a further terminal device, the measurement start indication indicating that the channel state indicator reference signal from the first cell is to be measured by the further terminal device; and in accordance with a determination that the validity duration has not expired, transmitting a resource indication for the resources of the channel state indicator reference signal to the further terminal device.

In some example embodiments, the method further comprises: receiving a measurement stop indication from the terminal device indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device; and transmitting a disabling request to the first network device, the disabling request to disable the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, sending the disable request comprises: determining, after the reception of the measurement stop indication, that the measurement of the channel state indicator reference signal in the first cell is not requested by a further terminal device; and sending the disable request to the first network device.

In some aspects, a method implemented at a first network device, comprising: receiving an enabling request from a second network device for enabling transmission of at least a channel state indicator reference signal in a first cell served by the first network device; and sending an acknowledgement to the second network device as to whether the transmission of the channel state indicator reference signal is enabled in the first cell.

In some example embodiments, the enablement request indicates at least one of: a list of carriers in at least the first cell for measurement of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising: the channel state indicator reference signal requested by the second network device; a cell list for the measurements of the set of channel state indicator reference signals, including the first cell; a list of active bandwidth parts in a second cell served by the second network device; or an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals.

In some example embodiments, the acknowledgement indicates at least one of: a resource list for a set of channel state indicator reference signals on one or more carriers in at least the first cell, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device; a list of enabled or disabled states of the resources of the set of channel state indicator reference signals; an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals; or at least a validity duration of one of the resources of the set of channel state indicator reference signals.

In some example embodiments, the method further comprises: receiving a disabling request from the second network device, the disabling request to disable the transmission of the channel state indicator reference signal in the first cell; and ceasing the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, ceasing the transmission of the channel state indicator reference signal comprises: determining, subsequent to the receiving of the disabling request, that the transmission of the channel state indicator reference signal is not requested by a further network device; and ceasing the transmission of the channel state indicator reference signal in the first cell.

In some aspects, an apparatus implemented at a terminal device, comprising: means for determining that a channel state indicator reference signal from a first cell served by a first network device is to be measured; means for sending a measurement start indication to a second network device, the measurement start indication indicating that measurements of the channel state indicator reference signals from the first cell are to be initiated by the terminal device; and means for performing the measurement of the channel state indicator reference signal from the first cell.

In some example embodiments, the means for sending the measurement start indication comprises: means for sending the measurement start indication to the second network device based on a measurement configuration from the second network device indicating that the measurement start indication is to be sent by the terminal device.

In some example embodiments, the means for determining that the channel state indicator reference signal from the first cell is to be measured comprises: means for determining that the channel state indicator reference signal from the first cell is to be measured in accordance with a determination that a metric associated with a measurement of a synchronization signal block in at least one of a second cell served by the second network device and the first cell is below a threshold.

In some example embodiments, the means for sending the measurement start indication comprises: means for transmitting the measurement start indication to the second network device in accordance with a determination that a channel state indicator reference signal from the first cell is undetectable.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured; resources for the channel state indicator reference signal; or an index of the channel state indicator reference signal.

In some example embodiments, the apparatus further comprises: means for sending a measurement stop indication to the second network device, the measurement stop indication indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device.

In some example embodiments, the means for performing the measurement of the channel state indicator reference signal from the first cell comprises: means for receiving a resource indication for resources of the channel state indicator reference signal from the second network device; and means for performing the measurement of the channel state indicator reference signal on the resource.

In some aspects, an apparatus implemented at a second network device comprises: means for receiving a measurement start indication from a terminal device, the measurement start indication indicating that measurements of channel state indicator reference signals from a first cell served by a first network device are to be initiated by the terminal device; and means for sending an enablement request to the first network device for enabling transmission of at least the channel state indicator reference signal in the first cell.

In some example embodiments, the measurement start indication indicates at least one of: a cell identity of the first cell; an index of a synchronization signal block associated with the channel state indicator reference signal to be measured by the terminal device; resources for the channel state indicator reference signal; or an index of the channel state indicator reference signal.

In some example embodiments, the apparatus further comprises: means for receiving an acknowledgement from the first network device as to whether the transmission of at least the channel state indicator reference signal in the first cell is enabled by the first network device.

In some example embodiments, the acknowledgement indicates a validity duration of the resource of the channel state indicator reference signal requested by the second network device, and the apparatus further comprises: means for determining that the measurement of the channel state indicator reference signal is continued when the validity duration expires; and means for sending a request to the first network device to maintain the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the apparatus further comprises: means for receiving a measurement start indication from a further terminal device, the measurement start indication indicating that the channel state indicator reference signal from the first cell is to be measured by the further terminal device; and means for transmitting a resource indication of resources for the channel state indicator reference signal to the further terminal device in dependence on determining that the validity duration has not expired.

In some example embodiments, the apparatus further comprises: means for receiving a measurement stop indication from the terminal device indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device; and means for sending a disable request to the first network device, the disable request to disable the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the method further comprises determining that the measurement of the channel state indicator reference signal from the first cell was not requested by a further terminal device after the reception of the measurement stop indication; and means for sending the disable request to the first network device.

In some aspects, an apparatus implemented at a first network device comprises: means for receiving an enablement request from a second network device for enabling transmission of at least a channel state indicator reference signal in a first cell served by the first network device; and means for sending an acknowledgement to the second network device as to whether the transmission of the channel state indicator reference signal is enabled in the first cell.

In some example embodiments, the apparatus further comprises: means for receiving a disable request from the second network device, the disable request to disable the transmission of the channel state indicator reference signal in the first cell; and means for ceasing the transmission of the channel state indicator reference signal in the first cell.

In some example embodiments, the means for ceasing the transmission of the channel state indicator reference signal comprises: means for determining, subsequent to the receiving of the disabling request, that the transmission of the channel state indicator reference signal is not requested by a further network device; and means for ceasing the transmission of the channel state indicator reference signal in the first cell.

In some aspects, a computer-readable storage medium includes program instructions stored thereon that, when executed by a processor of a device, cause the device to perform a method according to some example embodiments of the present disclosure.

Claims

1. A terminal device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the terminal device to:

determining that a channel state indicator reference signal from a first cell served by a first network device is to be measured;

sending a measurement start indication to a second network device, the measurement start indication indicating that measurements of the channel state indicator reference signals from the first cell are to be initiated by the terminal device; and

performing the measurement of the channel state indicator reference signal from the first cell.

2. A terminal device according to claim 1, wherein the terminal device is caused to transmit the measurement start indication by:

transmitting the measurement start indication to the second network device based on a measurement configuration from the second network device indicating that the measurement start indication is to be transmitted by the terminal device.

3. The terminal device of claim 1, wherein the terminal device is caused to determine that the channel state indicator reference signal from the first cell is to be measured by:

in accordance with a determination that a metric associated with a measurement of a synchronization signal block in at least one of a second cell served by the second network device or the first cell is below a threshold, determining that the channel state indicator reference signal from the first cell is to be measured.

4. A terminal device according to claim 1, wherein the terminal device is caused to transmit the measurement start indication by:

in accordance with a determination that a channel state indicator reference signal from the first cell is undetectable, sending the measurement start indication to the second network device.

5. The terminal device of claim 1, wherein the measurement start indication indicates at least one of:

a cell identity of the first cell;

an index of a synchronization signal block associated with the channel state indicator reference signal to be measured;

a resource for the channel state indicator reference signal to be measured; or

An index of the channel state indicator reference signal.

6. The terminal device of claim 1, wherein the terminal device is further caused to:

sending a measurement stop indication to the second network device, the measurement stop indication indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device.

7. The terminal device of claim 1, wherein the terminal device is caused to perform the measurement of the channel state indicator reference signal from the first cell by:

receiving, from the second network device, a resource indication for resources of the channel state indicator reference signal; and

performing the measurement of the channel state indicator reference signal on the resource.

8. A second network device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the second network device to:

receiving a measurement start indication from a terminal device, the measurement start indication indicating that measurements of channel state indicator reference signals from a first cell served by a first network device are to be initiated by the terminal device; and

sending an enabling request to the first network device, the enabling request to enable transmission of at least the channel state indicator reference signal in the first cell.

9. The second network device of claim 8, wherein the measurement start indication indicates at least one of:

a cell identity of the first cell;

an index of a synchronization signal block associated with the channel state indicator reference signal to be measured by the terminal device;

resources for the channel state indicator reference signal; or

An index of the channel state indicator reference signal.

10. The second network device of claim 8, wherein the enablement request indicates at least one of:

a carrier list in at least the first cell for measurements of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising the channel state indicator reference signals to be measured by the terminal device;

a list of cells for the measurements of the set of channel state indicator reference signals, the cells including the first cell;

a list of active bandwidth parts in a second cell served by the second network device; or

An index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals.

11. The second network device of claim 8, wherein the second network device is further caused to:

receiving, from the first network device, an acknowledgement as to whether the transmission of at least the channel state indicator reference signal in the first cell is enabled by the first network device.

12. The second network device of claim 11, wherein the acknowledgement indicates at least one of:

a list of resources for a set of channel state indicator reference signals on one or more carriers in at least the first cell, the set of channel state indicator reference signals comprising: the channel state indicator reference signal requested by the second network device;

an enabled or disabled status list of the resources for the set of channel state indicator reference signals;

an index list of a set of synchronization signal blocks associated with the set of channel state indicator reference signals; or

At least a validity duration of one of the resources for the set of channel state indicator reference signals.

13. The second network device of claim 11, wherein the acknowledgement indicates a validity duration of resources for the channel state indicator reference signal requested by the second network device, and the second network device is further caused to:

determining that the measurement of the channel state indicator reference signal is to continue after the validity duration expires; and

sending a request to the first network device to maintain the transmission of the channel state indicator reference signal in the first cell.

14. The second network device of claim 11, wherein the second network device is further caused to:

receiving a measurement start indication from a further terminal device, the measurement start indication specifying that the channel state indicator reference signal is to be measured in the first cell by the further terminal device; and

in accordance with a determination that the validity duration has not expired, transmitting a resource indication of resources for the channel state indicator reference signal to the further terminal device.

15. The second network device of claim 8, wherein the second network device is further caused to:

receiving a measurement stop indication from the terminal device indicating that the measurement of the channel state indicator reference signal from the first cell is to be stopped by the terminal device; and

sending a disabling request to the first network device, the disabling request to disable the transmission of the channel state indicator reference signal in the first cell.

16. The second network device of claim 15, wherein the second network device is caused to send the disable request by:

determining, after the reception of the measurement stop indication, that the measurement of the channel state indicator reference signal from the first cell is not requested by a further terminal device; and

sending the disable request to the first network device.

17. A first network device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the first network device to:

receiving an enabling request from a second network device for enabling transmission of at least a channel state indicator reference signal in a first cell served by the first network device; and

sending an acknowledgement to the second network device as to whether the transmission of the channel state indicator reference signal is enabled in the first cell.

18. The first network device of claim 17, wherein the enablement request indicates at least one of:

a carrier list in at least the first cell for measurements of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device;

a cell list for the measurements of the set of channel state indicator reference signals, including the first cell;

19. The first network device of claim 17, wherein the acknowledgement indicates at least one of:

a resource list for a set of channel state indicator reference signals on one or more carriers in at least the first cell, the set of channel state indicator reference signals comprising the channel state indicator reference signals requested by the second network device;

a list of enabled or disabled states of the resources of the set of channel state indicator reference signals;

20. The first network device of claim 17, wherein the first network device is further caused to:

receiving a disabling request from the second network device, the disabling request to disable the transmission of the channel state indicator reference signal in the first cell; and

ceasing the transmission of the CSI reference signal in the first cell.

21. The first network device of claim 20, wherein the first network device is caused to:

determining, subsequent to the receiving of the disabling request, that the transmission of the channel state indicator reference signal is not requested by a further network device; and

ceasing the transmission of the channel state indicator reference signal in the first cell.

22. A method implemented at a terminal device, comprising:

23. The method of claim 22, wherein sending the measurement start indication comprises:

24. The method of claim 22, wherein determining that the channel state indicator reference signal from the first cell is to be measured comprises:

in accordance with a determination that a metric associated with a measurement of a synchronization signal block in at least one of a second cell served by the second network device and the first cell is below a threshold, determining that the channel state indicator reference signal from the first cell is to be measured.

25. The method of claim 22, wherein sending the measurement start indication comprises:

26. The method of claim 22, wherein the measurement start indication indicates at least one of:

a cell identity of the first cell;

resources for the channel state indicator reference signal; or alternatively

An index of the channel state indicator reference signal.

27. The method of claim 22, further comprising:

28. The method of claim 22, wherein performing the measurement of the channel state indicator reference signal from the first cell comprises:

receiving, from the second network device, a resource indication for the resources of the channel state indicator reference signal; and

29. A method implemented at a second network device, comprising:

30. The method of claim 29, wherein the measurement start indication indicates at least one of:

a cell identity of the first cell;

resources for the channel state indicator reference signal; or alternatively

An index of the channel state indicator reference signal.

31. The method of claim 29, wherein the enabling request indicates at least one of:

32. The method of claim 29, further comprising:

receiving an acknowledgement from the first network device as to whether the transmission of at least the channel state indicator reference signal in the first cell is enabled by the first network device.

33. The method of claim 32, wherein the acknowledgement indicates at least one of:

34. The method of claim 32, wherein the acknowledgement indicates a validity duration of resources for the channel state indicator reference signal requested by the second network device, and the method further comprises:

35. The method of claim 32, further comprising:

receiving a measurement start indication from a further terminal device, the measurement start indication indicating that the channel state indicator reference signal from the first cell is to be measured by the further terminal device; and

36. The method of claim 29, further comprising:

37. The method of claim 36, wherein sending the disable request comprises:

determining, after the reception of the measurement stop indication, that the measurement of the channel state indicator reference signal in the first cell is not requested by a further terminal device; and

sending the disable request to the first network device.

38. A method implemented at a first network device, comprising:

39. The method of claim 38, wherein the enabling request indicates at least one of:

a list of carriers in at least the first cell for measurement of a set of channel state indicator reference signals, the set of channel state indicator reference signals comprising: the channel state indicator reference signal requested by the second network device;

40. The method of claim 38, wherein the acknowledgement indicates at least one of:

At least a validity duration of one of the resources of the set of channel state indicator reference signals.

41. The method of claim 38, further comprising:

receiving a disabling request from the second network device for disabling the transmission of the channel state indicator reference signals in the first cell; and

42. The method of claim 41, wherein ceasing the transmission of the channel state indicator reference signals comprises:

determining, subsequent to the receipt of the disable request, that the transmission of the channel state indicator reference signal is not requested by another network device; and

43. An apparatus implemented at a terminal device, comprising:

means for determining that a channel state indicator reference signal from a first cell served by a first network device is to be measured;

means for sending a measurement start indication to a second network device, the measurement start indication indicating that measurements of the channel state indicator reference signals from the first cell are to be initiated by the terminal device; and

means for performing the measurement of the channel state indicator reference signal from the first cell.

44. An apparatus implemented at a second network device, comprising:

means for receiving a measurement start indication from a terminal device, the measurement start indication indicating that measurements of channel state indicator reference signals from a first cell served by a first network device are to be initiated by the terminal device; and

means for transmitting an activation request to the first network device, the activation request to activate transmission of at least the channel state indicator reference signal in the first cell.

45. An apparatus implemented at a first network device, comprising:

means for receiving an enablement request from a second network device for enabling transmission of at least a channel state indicator reference signal in a first cell served by the first network device; and

means for transmitting an acknowledgement to the second network device regarding whether the transmission of the channel state indicator reference signal is enabled in the first cell.

46. A computer readable storage medium comprising program instructions stored thereon which, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 22 to 28.

47. A computer readable storage medium comprising program instructions stored thereon which, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 29 to 37.

48. A computer readable storage medium comprising program instructions stored thereon which, when executed by a processor of an apparatus, cause the apparatus to perform the method of any of claims 38 to 42.