Method, base station and storage medium for network configuration of csi-rs based radio resource management

Abstract

A base station of a network operates as a serving cell for a user equipment (UE) and configures the UE to measure channel state information reference signals (CSI-RS) from a target cell. The base station: determines whether a target cell of the network transmits synchronization signal block (SSB) information; and transmits, to the UE, a measurement configuration message indicating that the UE is to measure channel state information reference signals (CSI-RS) from the target cell, wherein the measurement configuration message does not include SSB information of the target cell, but further includes an indication of whether the target cell transmits SSBs.

Description

Background Technology

[0001] User equipment (UE) can operate on one or more types of networks. When operating on a network, the UE typically reports information back to the network. The reported information can be based on measurements performed by the UE on signals transmitted by the network's base station. Fifth-generation (5G) New Radio (NR) base stations can transmit various types of reference signals measured by UEs operating on 5G networks. An example of a reference signal transmitted by a 5G base station is the Channel State Information Reference Signal (CSI-RS). The UE can measure the CSI-RS and report information such as CSI-RS Received Power (CSI-RSRP), CSI-RS Received Signal Strength (CSI-RSSI), and CSI-RS Received Quality (CS-RSRQ) back to the base station.

[0002] The UE can measure these signals for both its currently reserved base station and neighboring base stations. The base stations and the 5G network can then use this information for various purposes such as channel estimation and mobility. However, for the UE to measure CSI-RS, the UE should know the resources (e.g., frequency and time) by which the various base stations in the network transmit CSI-RS. Summary of the Invention

[0003] Some exemplary aspects relate to a method performed by a base station of a network operating as a serving cell of a user equipment (UE). The method includes: determining whether a target cell of the network is transmitting synchronization signal block (SSB) information; and transmitting to the UE a measurement configuration message instructing the UE to measure channel state information reference signals (CSI-RS) from the target cell, wherein the measurement configuration message does not include the target cell's SSB information, but further includes an indication of whether the target cell is transmitting an SSB.

[0004] Other exemplary aspects relate to a base station of a network operating as a serving cell of a user equipment (UE). The base station has one or more processors and a transceiver. The one or more processors are configured to: determine whether a target cell of the network is transmitting Synchronization Signal Block (SSB) information; and configure a measurement configuration message instructing the UE to measure Channel State Information Reference Signal (CSI-RS) from the target cell, wherein the measurement configuration message does not include the target cell's SSB information, but further includes an indication of whether the target cell is transmitting an SSB. The transceiver transmits the measurement configuration message to the UE.

[0005] Another exemplary aspect relates to a computer-readable storage medium having instructions executable by a processor. Executing these instructions causes the processor to perform operations including: determining whether a target cell of the network is transmitting synchronization signal block (SSB) information; and transmitting to the UE a measurement configuration message instructing the UE to measure channel state information reference signals (CSI-RS) from the target cell, wherein the measurement configuration message does not include the target cell's SSB information, but further includes an indication of whether the target cell is transmitting an SSB. Attached Figure Description

[0006] Figure 1 An exemplary network arrangement based on various exemplary aspects is shown.

[0007] Figure 2 Exemplary user equipment (UE) based on various exemplary aspects is shown.

[0008] Figure 3 An exemplary network cell is shown according to various exemplary aspects.

[0009] Figure 4 It shows various exemplary aspects Figure 1 This is part of an exemplary network layout.

[0010] Figure 5 An example of information received by the UE in a Radio Resource Management (RRM) measurement configuration message is shown.

[0011] Figure 6 A first exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated synchronization signal block (SSB) in the RRM measurement configuration but the target gNB transmits an SSB, according to various exemplary aspects.

[0012] Figure 7 A second exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated SSB in the RRM measurement configuration but the target gNB transmits an SSB, according to various exemplary aspects.

[0013] Figure 8 A third exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated SSB in the RRM measurement configuration but the target gNB transmits an SSB, according to various exemplary aspects.

[0014] Figure 9 A fourth exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated SSB in the RRM measurement configuration but the target gNB transmits an SSB, according to various exemplary aspects.

[0015] Figure 10 A first exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated SSB in the RRM measurement configuration due to the target gNB not transmitting an SSB, according to various exemplary aspects.

[0016] Figure 11 A second exemplary signaling diagram is shown for UE to measure CSI-RS from the target gNB when there is no associated SSB in the RRM measurement configuration due to the target gNB not transmitting an SSB, according to various exemplary aspects. Detailed Implementation

[0017] The exemplary aspects can be further understood with reference to the following description and related figures, wherein similar elements have the same reference numerals. The exemplary aspects relate to user equipment (UE) performing additional synchronization to perform CSI-RS measurements on a target cell when an associated synchronization signal block (SSB) is absent in the measurement configuration. In some exemplary aspects, the serving cell provides the UE with additional information to assist the UE in performing additional synchronization.

[0018] The exemplary aspects are described with reference to a UE. However, the reference to a UE is provided for illustrative purposes only. The exemplary aspects can be used with any electronic component that can establish a connection to a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Therefore, the UE described herein is used to represent any electronic component.

[0019] Exemplary aspects are also described with reference to CSI-RS radio resource management (RRM) signaling and measurement in 5G NR networks. However, 5G NR networks and other different networks may transmit different types of reference signals or pilot signals for various purposes. Those skilled in the art will understand how the principles described herein for 5G CSI-RS RRM can be applied to other types of reference signals and other types of networks.

[0020] Figure 1 An exemplary network arrangement 100 according to various exemplary aspects is shown. The exemplary network arrangement 100 includes a UE 110. Those skilled in the art will understand that the UE 110 can be any type of electronic component configured to communicate via a network, such as a mobile phone, tablet, desktop computer, smartphone, phablet, embedded device, wearable device, Internet of Things (IoT) device, etc. It should also be understood that a practical network arrangement can include any number of UEs used by any number of users. Therefore, for illustrative purposes, only an example with a single UE 110 is provided.

[0021] UE 110 can be configured to communicate with one or more networks. In the example of network configuration 100, the networks with which UE 110 can wirelessly communicate are 5G NR Radio Access Network (RAN) 120, LTE RAN 122, and WLAN 124. However, it should be understood that UE 110 can also communicate with other types of networks (e.g., 5G cloud RAN, traditional cellular networks, etc.), and UE 110 can also communicate with networks via wired connections. Referring to the exemplary aspect, UE 110 can establish connections with 5G NR RAN 120, LTE RAN 122, and / or WLAN 124. Therefore, UE 110 may have a 5G NR chipset for communicating with NR RAN 120, an LTE chipset for communicating with LTE-RAN 122, and an ISM chipset for communicating with WLAN 124.

[0022] 5G NR RAN 120 and LTE-RAN 122 can be portions of a cellular network that can be deployed by network operators (e.g., Verizon, AT&T, Sprint, T-Mobile, etc.). RAN 120 and 122 can include, for example, cells or base stations (NodeB, eNodeB, HeNB, eNBS, gNB, gNodeB, macrocell base stations, microcell base stations, small cell base stations, femtocell base stations, etc.) configured to send and receive traffic from UEs equipped with appropriate cellular chipsets. WLAN 124 can include any type of wireless local area network (WiFi, hotspot, IEEE 802.11x network, etc.).

[0023] In network deployment 100, 5G NR RAN 120 includes a first 5G NR cell 120A and a second 5G NR cell 120B. LTE-RAN 122 includes a first LTE cell 122A and a second LTE cell 122B. However, actual network deployments can include any number of cells, deployed by any number of RANs. Therefore, the example of two 5G NR cells 120A and 120B and two LTE cells 122A and 122B is provided merely for illustrative purposes.

[0024] The references to the standalone 5G NR-RAN 120 and LTE-RAN 122 are provided for illustrative purposes only. Actual network deployments may include radio access networks with architectures capable of providing both 5G NR RAT and LTE-RAN services. For example, a next-generation radio access network (NG-RAN) (not shown) may include a next-generation Node B (gNB) providing 5G NR services and a next-generation evolved Node B (ng-eNB) providing LTE services. The NG-RAN may be connected to at least one of the evolved packet core (EPC) or the 5G core (5GC). Therefore, the examples of 5G NR-RAN 120 and LTE-RAN 122 are provided for illustrative purposes only.

[0025] Returning to the exemplary network arrangement 100, UE 110 can connect to 5G NR-RAN 120 via at least one of cells 120A-120B. UE 110 can connect to LTE-RAN 122 via at least one of cells 122A-122B. Those skilled in the art will understand that any relevant process can be performed to connect UE 110 to 5G NR-RAN 120 or LTE-RAN 122. For example, as described above, 5G NR-RAN 120 can be associated with a specific cellular provider, where UE 110 and / or its user have protocol and credential information (e.g., stored on a SIM card). Upon detecting the presence of 5G NR-RAN 120, UE 110 can transmit the corresponding credential information to associate with 5G NR-RAN 120. More specifically, UE 110 can be associated with a specific cell (e.g., cells 120A-120B). Similarly, for access to LTE services, UE 110 can be associated with cell 122A. However, as stated above, the references to 5G NR-RAN 120 and LTE-RAN 122 are for illustrative purposes only, and any appropriate type of RAN can be used.

[0026] In addition to networks 120-124, network deployment 100 also includes a cellular core network 130, an Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network service backbone 160. The cellular core network 130 can be viewed as an interconnected set of components that manage the operation and traffic of the cellular network. The cellular core network 130 also manages the traffic flowing between the cellular network and the Internet 140. The IMS 150 can generally be described as an architecture for delivering multimedia services to the UE 110 using IP protocols. The IMS 150 can communicate with the cellular core network 130 and the Internet 140 to provide multimedia services to the UE 110. The network service backbone 160 communicates directly or indirectly with the Internet 140 and the cellular core network 130. The network service backbone 160 can generally be described as a set of components (e.g., servers, network storage deployments, etc.) that implement a set of services that can be used to extend the functionality of the UE 110 to communicate with various networks.

[0027] Figure 2 An exemplary UE 110 is shown according to various exemplary aspects. Reference will be made to... Figure 1 The network layout 100 is used to describe UE 110. UE 110 can represent any electronic device and may include processor 205, memory layout 210, display device 215, input / output (I / O) device 220, transceiver 225, and other components 230. Other components 230 may include, for example, audio input devices, audio output devices, batteries providing a limited power source, data acquisition devices, ports for electrically connecting UE 110 to other electronic devices, etc.

[0028] Processor 205 may be configured to execute multiple engines of UE 110. For example, an engine may include CSI-RS measurement engine 235. If no associated SSB is present in the measurement configuration received by the UE, CSI-RS measurement engine 235 may perform operations associated with the UE performing additional synchronization when CSI-RS measurements are performed on the target cell.

[0029] The engine described above, as an application (e.g., a program) executed by processor 205, is merely exemplary. The functionality associated with the engine may also be represented as a separate integrated component of UE 110, or as a modular component coupled to UE 110, such as an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry for receiving signals and processing circuitry for processing signals and other information. The engine may also be embodied as a single application or multiple separate applications. Furthermore, in some UEs, the functionality described for processor 205 is distributed among two or more processors, such as a baseband processor and an application processor. Exemplary aspects may be implemented according to any of these or other configurations of the UE.

[0030] Memory 210 may be a hardware component configured to store data related to operations performed by UE 110. Display device 215 may be a hardware component configured to display data to a user, while I / O device 220 may be a hardware component enabling user input. Display device 215 and I / O device 220 may be separate components or may be integrated together (such as a touchscreen). Transceiver 225 may be a hardware component configured to establish connections with 5G NR-RAN 120, LTE-RAN 122, WLAN 124, etc. Therefore, transceiver 225 may operate on multiple different frequencies or channels (e.g., a continuous set of frequencies).

[0031] Figure 3 An exemplary network cell is shown according to various exemplary aspects. In this example, the network cell can be considered as... Figure 1 gNB 120A. Figure 3 The network cell shown can also represent any other gNB of gNB 120B or 5G NR-RAN 120. gNB 120A can represent the serving cell of UE 110. gNB 120A can represent any access node belonging to the 5G NR network that UE 110 can use to establish connections and manage network operations.

[0032] The gNB 120A may include a processor 305, a memory arrangement 310, input / output (I / O) devices 320, a transceiver 325, and other components 330. Other components 330 may include, for example, audio input devices, audio output devices, a battery, data acquisition devices, and ports for electrically connecting the gNB 120A to other electronic devices.

[0033] Processor 305 can be configured to execute multiple engines for gNB 120A. For example, when gNB 120A is the serving cell of the UE, the engines may include CSI-RS RRM configuration engine 335 for providing UE 110 with configuration information for performing CSI-RS measurements, including CSI-RS measurements of the target cell (e.g., gNB 120B).

[0034] The engines described above, each acting as an application (e.g., a program) executed by processor 305, are merely exemplary. The functionality associated with the engines may also be represented as a separate integrated component of gNB 120A, or as a modular component coupled to gNB 120A, such as an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry for receiving signals and processing circuitry for processing signals and other information. Furthermore, in some gNBs, the functionality described for processor 305 is split among multiple processors (e.g., a baseband processor, an application processor, etc.). Exemplary aspects may be implemented according to any configuration of these or other configurations of the gNB.

[0035] Memory 310 may be a hardware component configured to store data related to operations performed by UEs 110 and 112. I / O device 320 may be a hardware component or port enabling a user to interact with gNB 120A. Transceiver 325 may be a hardware component configured to exchange data with UEs 110, 112, and any other UE in system 100, for example, when gNB 120A is used as a PCell or SCell for either or both of UEs 110 and 112. Transceiver 325 may operate on a variety of different frequencies or channels (e.g., a set of consecutive frequencies). Therefore, transceiver 325 may include one or more components (e.g., radio components) to enable data exchange with various networks and UEs.

[0036] Figure 4 It shows various exemplary aspects Figure 1 This is part of an exemplary network layout 100. Figure 4 UE 110, gNB 120A, and gNB 120B are illustrated. In this example, gNB 120A can be considered the serving cell of UE 110, and gNB 120B is the neighboring cell. As described above, UE 110 can perform CSI-RS RRM measurements on the CSI-RS transmitted by the serving gNB 120A and the neighboring cell gNB 120B. For the purpose of CSI-RS RRM, gNB 120B can also be referred to as the "target cell".

[0037] To perform these measurements, UE 110 receives the RRM measurement configuration from the serving gNB 120A via RRC signaling. The RRM measurement configuration may include information such as CSI-RS resource information, cell ID, and associated SSB indication. Figure 5 An example of information 500 received by UE110 in the RRM measurement configuration message is shown. Figure 5The example illustrates information 500 as specified in 3GPP Technical Specification (TS) 38.331. The following description will refer to this information by way of example when describing various exemplary aspects. However, as stated above, the use of the CSI-RS RRM is merely an example, and measurements of other reference signals can be configured in different ways.

[0038] exist Figure 5 In this context, information 500 includes CSI-RS-ResourceConfigMobility information elements (IE) 510, CSI-RS-CellMobility IE 520, CSI-RS-Resource-Mobility IE 530, and associatedSSB IE 540. Figure 5 This illustrates the relationship between IE 510-540 and the various pieces of information included in each of IE 510-540. However, although Figure 5 The diagram shows information 500 that UE 110 can receive in the RRM measurement configuration message, but UE 110 may not actually receive all information 500. When UE 110 does not receive all information 500, it needs to determine the operation of CSI-RS RRM.

[0039] The following provides various exemplary scenarios of UE 110's operation based on information 500 received in the RRM measurement configuration. For example, if associated SSB IE 540 is present, UE 110 may enable the timing of the CSI-RS resources indicated in CSI-RS-Resource-Mobility IE 530 to be based on the timing of the cell indicated by the cellId in CSI-RS-CellMobility IE 520. In this case, if UE 110 cannot detect the synchronization signal (SS) and physical broadcast channel (PBCH) SS / PBCH blocks indicated by the associated SSB IE 540 and cellId, then UE 110 does not need to monitor CSI-RS resources. If associatedSSB IE 540 is not present, UE 110 may enable the timing of the CSI-RS resource indicated in CSI-RS-Resource-Mobility IE 530 to be based on the timing of service gNB 120A indicated by refServCellIndex in CSI-RS-ResourceConfigMobility IE 510. In this case, UE 110 can measure the CSI-RS resource even if no SS / PBCH block with cellId in CSI-RS-CellMobility IE 520 is detected.

[0040] In other scenarios, if UE 110 is configured with higher-layer parameters for CSI-RS-Resource-Mobility and the higher-layer parameters for associated SSB are not configured, UE 110 will perform measurements based on CSI-RS-Resource-Mobility IE 530, and UE 110 can make the timing of CSI-RS resources based on the timing of the serving gNB 120A.

[0041] In another scenario, if UE 110 is configured with higher-layer parameters for CSI-RS-Resource-Mobility and associated SSB, UE 110 can make the timing of CSI-RS resources based on the cell timing given by the cellId configured for the CSI-RS resources (e.g., neighboring gNB 120B). Additionally, for a given CSI-RS resource, if the associated SS / PBCH block is configured but not detected by UE 110, UE 110 does not need to monitor the corresponding CSI-RS resource.

[0042] Therefore, in the above scenario, there exists a situation where UE 110 will use the timing of serving gNB 120A, indicated by refServCellIndex, for the purpose of measuring the CSI-RS of neighboring cell gNB 120B. However, due to factors such as cell phase synchronization errors and UE location, there may be timing misregistration between serving gNB 120A and neighboring cell 120B. Therefore, even if the network may instruct UE 110 to use the timing of serving gNB 120A, UE 110 may still need to perform additional synchronization to obtain sufficient timing / frequency information to measure the CSI-RS of neighboring gNB 120B. An example of UE 110 performing such additional synchronization will be described below.

[0043] Two scenarios are used to describe exemplary aspects. In both scenarios, UE 110 may be configured to measure CSI-RS of target gNB 120B, but no associated SSB exists in the RRM measurement configuration. In the first scenario, target gNB 120B may actually be performing an SSB transmission. In the second scenario, target gNB 120B may not be performing an SSB transmission. In both scenarios, serving gNB 120A may indicate to UE 110 whether target gNB 120B is performing an SSB transmission. UE 110 can use this information (e.g., whether target gNB 120B is performing an SSB transmission) to determine the operation regarding CSI-RS measurement on target gNB 120B. As will be described in more detail for these two scenarios below, in some cases, the network (e.g., the serving gNB 120A) will provide additional information beyond an indication of whether the target gNB 120B is performing an SSB transmission to help the UE 110 determine the action to be taken regarding the CSI-RS measurement on the target gNB 120B.

[0044] The following describes various exemplary aspects related to the first scenario, in which the UE is configured to perform CSI-RS measurements against a target gNB 120B, but even if the target gNB 120B transmits an SSB, there is no associated SSB in the RRM measurement configuration.

[0045] Figure 6 A first exemplary signaling diagram 600 is shown for UE 110 to measure CSI-RS from target gNB 120B when there is no associated SSB in the RRM measurement configuration but the target gNB 120B transmits an SSB, according to various exemplary aspects. As will be described in more detail below, in this exemplary aspect, UE 110 will synchronize with the SSB of the target gNB 120B to obtain accurate timing and frequency information of the target gNB 120B.

[0046] In step 605, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. Various information that can be included in the CSI-RS RRM measurement configuration message has been described above. The CSI-RS RRM measurement configuration message instructs the UE 110 to measure the CSI-RS of the target gNB 120B. However, in this example, it can be assumed that the CSI-RS RRM measurement configuration message does not include the associated SSB of the target gNB 120B.

[0047] In 610, the serving gNB 120A may also send a message indicating that the target gNB 120B is transmitting an SSB. It should be understood that the information in message 610 may also be sent as part of the RRM measurement configuration message 605. Additionally, it should be understood that the serving gNB 120A and the target gNB 120B may exchange information allowing the serving gNB 120A to know that the target gNB 120B is transmitting an SSB. In other exemplary aspects, the serving gNB 120A may know that the target gNB 120B is transmitting an SSB based on information received from the core network 130. It should be understood that throughout this specification describing any type of information exchanged between the serving gNB 120A and the target gNB 120B, this exchange may be performed via direct communication between gNBs (e.g., via an X2 interface) or indirect communication via the core network 130.

[0048] In step 615, UE 110 determines a search window to search for SSB transmissions of target gNB 120B. Since in step 610, serving gNB 120A notifies UE 110 that target gNB 120B is transmitting an SSB, UE 110 can subsequently attempt to receive the target gNB 120B SSB transmission. UE 110 can determine the search window based on the timing of serving gNB 120A. For example, because serving gNB 120A and target gNB 120B are adjacent, the 5G network should configure SSB transmissions of gNB 120A and gNB 120B relative to each other. UE 110 can learn about this relationship between SSB transmissions of adjacent cells and select a search window that should include the SSB of target gNB 120B.

[0049] In this example, UE 110 can be assumed to receive the target gNB 120B SSB transmission 620 in search window 615. UE 110 will now have accurate timing and frequency information to perform CSI-RS measurements on the target gNB 120B. For example, the target gNB 120B may transmit CSI-RS transmission 625, and because UE 110 obtains the timing and frequency information based on receiving the target gNB 120B SSB transmission 620, UE 110 can perform CSI-RS measurements on the target gNB 120B's CSI-RS transmission 625.

[0050] Figure 7 A second exemplary signaling diagram 700 is shown for UE 110 to measure CSI-RS from target gNB 120B when there is no associated SSB in the RRM measurement configuration but the target gNB 120B transmits an SSB, according to various exemplary aspects. In this exemplary aspect, UE 110 receives information from the target gNB 120B from the serving gNB 120A.

[0051] In step 705, the serving gNB 120A and the target gNB 120B can exchange various information, including timing / frequency information of the target gNB 120B. In step 710, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. Again, in this example, the CSI-RS RRM measurement configuration message 710 can be considered not to include the associated SSB of the target gNB 120B. However, the CSI-RS RRM measurement configuration message 710 may include the timing / frequency information of the target gNB 120B. It should be understood that the timing / frequency information of the target gNB 120B may also be transmitted from the serving gNB 120A to the UE 110 in a separate message from the CSI-RS RRM measurement configuration message 710.

[0052] In some exemplary aspects, the actual timing / frequency information of the target gNB 120B may be provided to the UE 110. In other exemplary aspects, the timing / frequency information of the target gNB 120B may be indicated as an offset from the timing / frequency of the serving gNB 120A; for example, the UE 110 may derive the timing / frequency of the target gNB 120B based on the offset from the timing of the serving gNB 120A. In some exemplary aspects, if the offset = 0, the serving gNB 120A may indicate a single bit to the UE 110 to indicate perfect timing registration between the serving gNB 120A and the target gNB 120B.

[0053] In step 715, the target gNB 120B can transmit CSI-RS transmissions, and because UE 110 is aware of the timing and frequency information (e.g., based on receive offset information), UE 110 can perform CSI-RS measurements on the target gNB 120B's CSI-RS transmissions. Because UE 110 receives the timing / frequency information of the target gNB 120B from the serving gNB 120A, UE 110 can skip synchronization with the target gNB 120B to receive SSB transmissions, as per [reference to...]. Figure 6 The signaling diagram 600 executes.

[0054] Figure 8 A third exemplary signaling diagram 800 is shown for UE 110 to measure CSI-RS from target gNB 120B when there is no associated SSB in the RRM measurement configuration but the target gNB 120B transmits an SSB, according to various exemplary aspects. In this exemplary aspect, UE 110 will be configured to perform system frame number (SFN) and frame time difference (SFTD) measurements between the serving gNB 120A and the target gNB 120B.

[0055] In step 805, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. This message again includes information instructing the UE 110 to measure the CSI-RS of the target gNB 120B, but does not include the associated SSB of the target gNB 120B. In this exemplary aspect, the CSI-RS RRM measurement configuration message may also include configuration information instructing the UE 110 to perform additional SFTD measurements between the serving gNB 120A and the target gNB 120B.

[0056] In 810, the serving gNB 120A transmits one or more SFN transmissions, and in 815, the destination gNB 120B transmits one or more SFN transmissions. SFN transmissions 810 and 815 do not refer to any specific type of transmission, but simply to frame transmissions of gNBs 120A-B with system frame numbers. SFN stands for System Frame Number, a 10-bit identifier for frames numbered consecutively from 0 to 1023 in a 5G network.

[0057] In 820, UE 110 performs SFTD measurements based on SFN transmissions 810 and 820. SFTD measurements allow UE 110 to measure the timing difference between the SFN and frame boundaries between the serving gNB 120A and the target gNB 120B. UE 110 can then use this timing difference with the timing of the serving gNB 120A, indicated by, for example, refServCellIndex, to determine the timing of the CSI-RS of the target gNB 120B.

[0058] In step 825, the target gNB 120B can transmit CSI-RS transmissions, and because the UE 110 obtains the timing information of the target gNB 120B from the SFTD measurement and the timing of the serving gNB 120A, the UE 110 can perform CSI-RS measurements on the CSI-RS transmissions of the target gNB 120B in step 825. In other exemplary aspects, similar to the signaling diagram 600 above, the UE 110 can use the timing information from the SFTD measurement and the timing of the serving gNB 120A to locate and synchronize with the SSB of the target gNB 120B to determine the exact timing of the CSI-RS transmissions of the target gNB 120B in step 825.

[0059] Figure 9 A fourth exemplary signaling diagram 900 is shown for UE 110 to measure CSI-RS from target gNB 120B when no associated SSB is present in the RRM measurement configuration but the target gNB 120B transmits an SSB, according to various exemplary aspects. As will be described in more detail below, in this exemplary aspect, UE 110 can determine a search window for CSI-RS transmissions from target gNB 120B.

[0060] In 905, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. This message again includes information instructing the UE 110 to measure the CSI-RS of the target gNB 120B, but does not include the associated SSB of the target gNB 120B.

[0061] In 910, UE 110 can determine the search window for CSI-RS transmission of target gNB 120B based on the timing of serving gNB 120A. As described above, the CSI-RS RRM measurement configuration message will include the timing of serving gNB 120A. This timing can be used to locate the CSI-RS of target gNB 120B. The search window 910 range will take into account the cell phase synchronization error and possible propagation delay difference between serving gNB 120A and target gNB 120B.

[0062] Cell phase synchronization error can be a value related to the minimum requirements for this parameter in relevant standards (e.g., 3GPP specifications). This can be added to the possible propagation delay difference between the serving gNB 120A and the target gNB 120B. UE 110 knows its own location and the location of gNB 120A-B, and can, for example, estimate the possible propagation delay difference. It has been shown that, by using this technique, the search window 910 will be approximately ±min (2 SSB symbols, 1 Physical Downlink Shared Channel (PDSCH) symbol).

[0063] In this example, it can be assumed that UE 110 has selected the appropriate search window 910 and received CSI-RS transmission 915 from the target gNB 120B. UE 110 can perform CSI-RS measurements on the CSI-RS transmission 915 of the target gNB 120B.

[0064] The following describes various exemplary aspects related to the second scenario, in which the UE is configured to perform CSI-RS measurements against a target gNB 120B, but because the target gNB 120B does not transmit SSBs, there is no associated SSB in the RRM measurement configuration.

[0065] Figure 10 A first exemplary signaling diagram 1000 is shown for UE 110 to measure CSI-RS from target gNB 120B when there is no associated SSB in the RRM measurement configuration because target gNB 120B does not transmit an SSB, according to various exemplary aspects. In this exemplary aspect, UE 110 receives information from serving gNB 120A about target gNB 120B. Signaling diagram 1000 is substantially similar to... Figure 7Signaling diagram 700.

[0066] In step 1005, the serving gNB 120A and the target gNB 120B can exchange various information, including timing / frequency information of the target gNB 120B. In step 1010, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. The CSI-RS RRM measurement configuration message 1010 may include timing / frequency information of the target gNB 120B. It should be understood that the timing / frequency information of the target gNB 120B can also be transmitted from the serving gNB 120A to the UE 110 in a separate message from the CSI-RS RRM measurement configuration message 1010.

[0067] In some exemplary aspects, the actual timing / frequency information of the target gNB 120B may be provided to the UE 110. In other exemplary aspects, the timing / frequency information of the target gNB 120B may be indicated as an offset from the timing / frequency of the serving gNB 120A; for example, the UE 110 may derive the timing / frequency of the target gNB 120B based on the offset from the timing of the serving gNB 120A. In some exemplary aspects, if the offset = 0, the serving gNB 120A may indicate a single bit to the UE 110 to indicate perfect timing registration between the serving gNB 120A and the target gNB 120B.

[0068] In 1015, the target gNB 120B can transmit CSI-RS transmissions, and because the UE 110 is aware of timing and frequency information (e.g., based on receive offset information), the UE 110 can perform CSI-RS measurements on the target gNB 120B's CSI-RS transmissions 1015.

[0069] Figure 11 A second exemplary signaling diagram 1100 is shown for UE 110 to measure CSI-RS from target gNB 120B when there is no associated SSB in the RRM measurement configuration because the target gNB 120B does not transmit an SSB, according to various exemplary aspects. In this exemplary aspect, UE 110 can determine a search window for CSI-RS transmissions from target gNB 120B. Signaling diagram 1100 is substantially similar to... Figure 9 Signaling diagram 900.

[0070] In 1105, the serving gNB 120A transmits a CSI-RS RRM measurement configuration message to the UE 110. This message again includes information instructing the UE 110 to measure the CSI-RS of the target gNB 120B, but does not include the associated SSB of the target gNB 120B, because the target gNB 120B does not transmit SSBs.

[0071] In 1110, UE 110 can determine the search window for CSI-RS transmission of target gNB 120B based on the timing of serving gNB 120A. As described above, the CSI-RS RRM measurement configuration message will include the timing of serving gNB 120A. This timing can be used to locate the CSI-RS of target gNB 120B. The search window 1110 range will take into account the cell phase synchronization error and possible propagation delay difference between serving gNB 120A and target gNB 120B.

[0072] The cell phase synchronization error can be a value related to the minimum requirement for this parameter in relevant standards (e.g., 3GPP specifications). This can be added to the possible propagation delay difference between the serving gNB 120A and the target gNB 120B. The UE 110 knows its own location and the location of gNB 120A-B, and can, for example, estimate the possible propagation delay difference. It has been shown that, by using this technique, the search window 1110 will be approximately ±1 PDSCH symbol. The difference between signaling diagram 1100 and signaling diagram 900 is that, in signaling diagram 900, the search window can be ±2 SBB symbols. However, as mentioned above, in this scenario, the target gNB 120B does not transmit SSBs, so the search window cannot be described by referring to SSB symbols.

[0073] In this example, it can be assumed that UE 110 has selected the appropriate search window 1110 and received CSI-RS transmission 1115 from the target gNB 120B. UE 110 can perform CSI-RS measurements on the CSI-RS transmission 1115 of the target gNB 120B.

[0074] Those skilled in the art will understand that the exemplary aspects described above can be implemented with any suitable software or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary aspects may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, and mobile devices with operating systems such as iOS, Android, etc. Exemplary aspects of the methods described above may be embodied as programs comprising lines of code stored on a non-transitory computer-readable storage medium, which, at compile time, can be executed on a processor or microprocessor.

[0075] Although this patent application describes various combinations of aspects, each with different features, those skilled in the art will understand that any feature of one aspect can be combined with features of other aspects or features that are not functionally or logically inconsistent with the operation or function of the device of the aspect disclosed in this invention in any manner not disclosed to be denied.

[0076] As is widely recognized, the use of personally identifiable information should comply with privacy policies and practices that are generally accepted to meet or exceed industry or governmental requirements for protecting user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0077] It will be apparent to those skilled in the art that various modifications can be made to this disclosure without departing from its spirit or scope. Therefore, this disclosure is intended to cover all modifications and variations thereof, provided that such modifications and variations are within the scope of the appended claims and their equivalents.

Claims

1. A method for wireless communication, comprising: At the base station of the network operating as the serving cell of the user equipment (UE): Determine whether the target cell of the network is transmitting Synchronization Signal Block (SSB) information; as well as A measurement configuration message is transmitted to the UE instructing the UE to measure the Channel State Information Reference Signal (CSI-RS) from the target cell, wherein the measurement configuration message does not include the SSB information of the target cell but includes an indication of whether the target cell transmits the SSB information, wherein the search window used by the UE for the measurement of the CSI-RS is based at least on the timing of the serving cell, and the range of the search window is based on the propagation delay difference and cell phase synchronization error between the serving cell and the target cell.

2. The method according to claim 1, wherein the measurement configuration message instructs the target cell to transmit the SSB information.

3. The method according to claim 1, wherein the measurement configuration message instructs the target cell not to transmit the SSB information.

4. The method according to claim 2 or 3, further comprising: Exchange timing information with the target cell; as well as Determine the offset between the timing of the serving cell and the timing of the target cell, wherein the measurement configuration message includes the timing of the serving cell and the offset.

5. The method according to claim 4, wherein, In response to the offset value being equal to 0, the offset value is indicated by a single bit in the measurement configuration message.

6. The method according to claim 1, wherein the measurement configuration message further includes the timing of the serving cell.

7. The method of claim 2, wherein the measurement configuration message further includes configuration information instructing the UE to perform system frame number (SFN) and frame time difference (SFTD) measurements between the serving cell and the target cell.

8. A base station of a network operating as a serving cell of a user equipment (UE), comprising: One or more processors, said one or more processors being configured to: Determine whether the target cell of the network is transmitting Synchronization Signal Block (SSB) information; as well as The configuration includes a measurement configuration message instructing the UE to measure the Channel State Information Reference Signal (CSI-RS) from the target cell, wherein the measurement configuration message does not include the SSB information of the target cell but includes an indication of whether the target cell transmits the SSB information, wherein the search window used by the UE for the CSI-RS measurement is based at least on the timing of the serving cell, and the range of the search window is based on the propagation delay difference and cell phase synchronization error between the serving cell and the target cell; and A transceiver for transmitting the measurement configuration message to the UE.

9. The base station according to claim 8, wherein the measurement configuration message instructs the target cell to transmit the SSB information.

10. The base station according to claim 8, wherein the measurement configuration message indicates that the target cell does not transmit the SSB information.

11. The base station according to claim 9 or 10, wherein the one or more processors are further configured to: Exchange timing information with the target cell; and Determine the offset between the timing of the serving cell and the timing of the target cell, wherein the measurement configuration message includes the timing of the serving cell and the offset.

12. The base station according to claim 11, wherein, In response to the offset value being equal to 0, the offset value is indicated by a single bit in the measurement configuration message.

13. The base station according to claim 8, wherein the measurement configuration message further includes the timing of the serving cell.

14. The base station according to claim 8, wherein the measurement configuration message further includes configuration information instructing the UE to perform system frame number (SFN) and frame time difference (SFTD) measurements between the serving cell and the target cell.

15. A computer-readable storage medium storing instructions that, when executed by a processor of a base station of a network operating as a user equipment (UE), perform operations including: Determine whether the target cell of the network is transmitting Synchronization Signal Block (SSB) information; as well as A measurement configuration message is transmitted to the UE instructing the UE to measure the Channel State Information Reference Signal (CSI-RS) from the target cell, wherein the measurement configuration message does not include the SSB information of the target cell but includes an indication of whether the target cell transmits the SSB information, wherein the search window used by the UE for the measurement of the CSI-RS is based at least on the timing of the serving cell, and the range of the search window is based on the propagation delay difference and cell phase synchronization error between the serving cell and the target cell.

16. The computer-readable storage medium of claim 15, wherein the measurement configuration message instructs the target cell to transmit the SSB information.

17. The computer-readable storage medium of claim 15, wherein the measurement configuration message indicates that the target cell does not transmit the SSB information.

18. The computer-readable storage medium of claim 16 or 17, wherein the operation further comprises: Exchange timing information with the target cell; as well as Determine the offset between the timing of the serving cell and the timing of the target cell, wherein the measurement configuration message includes the timing of the serving cell and the offset.

19. The computer-readable storage medium according to claim 18, wherein, In response to the offset value being equal to 0, the offset value is indicated by a single bit in the measurement configuration message.

20. The computer-readable storage medium of claim 15, wherein the measurement configuration message further includes the timing of the serving cell.

21. The computer-readable storage medium of claim 16, wherein the measurement configuration message further includes configuration information instructing the UE to perform system frame number (SFN) and frame time difference (SFTD) measurements between the serving cell and the target cell.

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