Pathloss estimates for candidate cells

Abstract

A method includes receive, from a serving cell of a network node, information of layer1 / layer2 triggered mobility (LTM) configuration for one or more candidate cells; perform a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determine to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintain the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receive from the serving cell of the network node, a cell switch command for a candidate cell.

Description

PATHLOSS ESTIMATES FOR CANDIDATE CELLSTECHNICAL FIELD

[0001] This description relates to wireless communications.BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. EUTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node AP (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, or mobile stations are referred to as user equipments (UE). LTE has included a number of improvements or developments. Aspects of LTE are also continuing to improve.

[0004] 5G New Radio (NR) development is part of a continued mobile broadband evolution process to meet the requirements of 5G, similar to earlier evolution of 3G and 4G wireless networks. In addition, 5G is also targeted at the new emerging use cases in addition to mobile broadband. A goal of 5G is to provide significant improvement in wireless performance, which may include new levels of data rate, latency, reliability, and security. 5G NR may also scale to efficiently connect the massive Internet of Things (loT) and may offer new types of mission-critical services. For example, ultra-reliable and low- latency communications (URLLC) devices may require high reliability and very low latency. 6G and other networks are also being developed.SUMMARY

[0005] In some aspects, the techniques described herein relate to an apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving,by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells; determining N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates; maintaining the pathloss estimates for the N activated TCI states; and receiving a cell switch command indicating a TCI state and a candidate cell.

[0006] In some aspects, the techniques described herein relate to a method including: receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, by the user device from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells; determining by the user device, N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates; maintaining the pathloss estimates for the N activated TCI states; and receiving a cell switch command indicating a TCI state and a candidate cell.

[0007] In some aspects, the techniques described herein relate to an apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; performing, by the apparatus, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determining to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

[0008] In some aspects, the techniques described herein relate to a method including: receiving, by a user device from a serving cell of a network node, information ofIayerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; performing, by the user device, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

[0009] In some aspects, the techniques described herein relate to an apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, from the network node, information of maintaining pathloss estimates associated with M candidate cells; determining N reference signals (RSs) associated with at least one candidate cell of the M candidate cells; maintaining the pathloss estimates for the N RSs; and receiving a cell switch command for a candidate cell.

[0010] In some aspects, the techniques described herein relate to a method including: receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, by the user device from the network node, information of maintaining pathloss estimates associated with M candidate cells; determining by the user device, N reference signals (RSs) associated with at least one candidate cell of the M candidate cells; maintaining the pathloss estimates for the N RSs; and receiving a cell switch command for a candidate cell.

[0011] In some aspects, the techniques described herein relate to an apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus, information of M candidate cells; determining by the apparatus to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received; maintaining the pathloss estimates for the N RSs of the at least one candidate cell;transmitting, to a serving cell of a network node, information of the N RSs of the at least one candidate cell for which the apparatus maintained the pathloss estimates; and receiving, from the serving cell of the network node, a cell switch command for a candidate cell.

[0012] In some aspects, the techniques described herein relate to a method including: receiving, by a user device, information of M candidate cells; determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received; maintaining the pathloss estimates for the N RSs of the at least one candidate cell; transmitting, by the user device to a serving cell of a network node, information of the N RSs of the at least one candidate cell for which the user device maintained the pathloss estimates; and receiving, by the user device from the serving cell of the network node, a cell switch command for a candidate cell.

[0013] Other example embodiments are provided or described for each of the example methods, including: means for performing any of the example methods; a non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed by at least one processor, are configured to cause a computing system to perform any of the example methods; and an apparatus including 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 apparatus at least to perform any of the example methods.

[0014] The details of one or more examples of embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a block diagram of a wireless network 130.

[0016] FIG. 2 is a diagram illustrating an example procedure for LTM.

[0017] FIG. 3 is a diagram illustrating an example procedure for LTM according to an example embodiment based on TCI state activation.

[0018] FIG. 4 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment.

[0019] FIG. 5 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment.

[0020] FIG. 6 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment.

[0021] FIG. 7 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment.

[0022] FIG. 8 is a block diagram of a wireless station or node (e.g., UE, user device, AP, BS, eNB, gNB, RAN node, network node, TRP, or other node) 1300 according to an example embodiment.DETAILED DESCRIPTION

[0023] It shall be understood that although the terms “first,” “second,”. . ., etc., in front of noun(s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun(s). 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.

[0024] As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

[0025] FIG. 1 is a block diagram of a wireless network 130. In the wireless network 130 of FIG. 1, user devices 131, 132, 133 and 135, which may also be referred to as mobile stations (MSs) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB), a gNB or a network node. The terms user device and user equipment (UE) may be used interchangeably. A BS may also include or may be referred to as a RAN (radio access network) node, and may include a portion of a BS or a portion of a RAN node, such as e.g., such as a centralized unit (CU) and / or a distributed unit (DU) in the case of a split BS or split gNB. At least part of the functionalities of a BS (e.g., access point (AP), base station (BS) or (e)Node B (eNB), gNB, RAN node) may also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remoteradio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices (or UEs) 131, 132, 133 and 135. Although only four user devices (or UEs) are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a SI interface 151. This is merely one simple example of a wireless network, and others may be used.

[0026] A base station (e.g., such as BS 134) is an example of a radio access network (RAN) node within a wireless network. A BS (or a RAN node) may be or may include (or may alternatively be referred to as), e.g., an access point (AP), a gNB, an eNB, or portion thereof (such as a centralized unit (CU) and / or a distributed unit (DU) in the case of a split BS or split gNB), or other network node.

[0027] Some functionalities of the communication network may be carried out, at least partly, in a central / centralized unit, CU, (e.g., server, host or node) operationally coupled to distributed unit, DU, (e.g., a radio head / node). Thus, 5G networks architecture may be based on a so-called CU-DU split. The gNB-CU (central node) may control a plurality of spatially separated gNB-DUs, acting at least as transmit / receive (TX / RX) nodes. In some embodiments, however, the gNB-DUs (also called DU) may comprise e.g., a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the gNB-CU (also called a CU) may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layer. Other functional splits are possible too.

[0028] According to an illustrative example, a BS node (e.g., BS, eNB, gNB, CU / DU, . . .) or a radio access network (RAN) may be part of a mobile telecommunication system. A RAN (radio access network) may include one or more BSs or RAN nodes that implement a radio access technology, e.g., to allow one or more UEs to have access to a network or core network (CN). Thus, for example, the RAN (RAN nodes, such as BSs or gNBs) may reside between one or more user devices or UEs and a core network. According to an example embodiment, each RAN node (e.g., BS, eNB, gNB, CU / DU, . . .) or BS may provide one or more wireless communication services for one or more UEs or user devices, e.g., to allow the UEs to have wireless access to a network, via the RAN node. Each RAN node or BS may perform or provide wireless communication services, e.g., such as allowing UEs or user devices to establish a wireless connection to the RAN node, and sending data to and / or receiving data from one or more of the UEs. For example,after establishing a connection to a UE, a RAN node or network node (e.g., BS, eNB, gNB, CU / DU, . . .) may forward data to the UE that is received from a network or the core network, and / or forward data received from the UE to the network or core network. RAN nodes or network nodes (e.g., BS, eNB, gNB, CU / DU, . . .) may perform a wide variety of other wireless functions or services, e.g., such as broadcasting control information (e.g., such as system information or on-demand system information) to UEs, paging UEs when there is data to be delivered to the UE, assisting in handover of a UE between cells, scheduling of resources for uplink data transmission from the UE(s) and downlink data transmission to UE(s), sending control information to configure one or more UEs, and the like. These are a few examples of one or more functions that a RAN node or BS may perform.

[0029] A user device or user node (user terminal, user equipment (UE), mobile terminal, handheld wireless device, etc.) may refer to a portable computing device that includes wireless mobile communication devices operating either with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and / or touch screen computer, a tablet, a phablet, a game console, a notebook, a vehicle, a sensor, and a multimedia device, as examples, or any other wireless device. It should be appreciated that a user device may also be (or may include) a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. Also, a user node may include a user equipment (UE), a user device, a user terminal, a mobile terminal, a mobile station, a mobile node, a subscriber device, a subscriber node, a subscriber terminal, or other user node. For example, a user node may be used for wireless communications with one or more network nodes (e.g., gNB, eNB, BS, AP, CU, DU, CU / DU) and / or with one or more other user nodes, regardless of the technology or radio access technology (RAT). In LTE (as an illustrative example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility / handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, andother control functions or blocks. Other types of wireless networks, such as 5G (which may be referred to as New Radio (NR)) may also include a core network.

[0030] In addition, the techniques described herein may be applied to various types of user devices or data service types, or may apply to user devices that may have multiple applications running thereon that may be of different data service types. New Radio (5G) development may support a number of different applications or a number of different data service types, such as for example: machine type communications (MTC), enhanced machine type communication (eMTC), Internet of Things (loT), and / or narrowband loT user devices, enhanced mobile broadband (eMBB), and ultra-reliable and low-latency communications (URLLC). Many of these new 5G (NR) - related applications may require generally higher performance than previous wireless networks.

[0031] loT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC, or Machine to Machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without intervention of humans. Enhanced mobile broadband (eMBB) may support much higher data rates than currently available in LTE.

[0032] Ultra-reliable and low-latency communications (URLLC) is a new data service type, or new usage scenario, which may be supported for New Radio (5G) systems. This enables emerging new applications and services, such as industrial automations, autonomous driving, vehicular safety, e-health services, and so on. 3 GPP targets in providing connectivity with reliability corresponding to block error rate (BLER) of 10-5 and up to 1 ms U-Plane (user / data plane) latency, by way of illustrative example. Thus, for example, URLLC user devices / UEs may require a significantly lower block error rate than other types of user devices / UEs as well as low latency (with or without requirement for simultaneous high reliability). Thus, for example, a URLLC UE (or URLLC application on a UE) may require much shorter latency, as compared to an eMBB UE (or an eMBB application running on a UE).

[0033] The techniques described herein may be applied to a wide variety of wireless technologies or wireless networks, such as 5G (New Radio (NR)), cmWave, and / or mmWave band networks, loT, MTC, eMTC, eMBB, URLLC, 6G, etc., or any other wireless network or wireless technology. These example networks, technologies or data service types are provided only as illustrative examples.

[0034] A user device (or UE) may measure various signals and may transmit one or more measurement reports to the network. For example, a UE may measure reference signals received from one or more network nodes (e.g., gNBs or DUs), including channel state information-reference signals (CSI-RSs) and / or synchronization signal block (SSB) reference signals, demodulation references signals, and / or other reference signals. Based on received reference signals, the UE may measure various signal parameters, e.g., such as reference signal received power (RSRP), reference signal received quality (RSRQ), signal- to interference-plus-noise-ratio (SINR), received signal strength indicator (RSSI), or other signal parameter.

[0035] The PHY (physical) layer may refer to layer 1 (LI) and MAC (media access control) may refer to layer 2 (L2). RSRP, RSRQ, SINR and RSSI are signal quantities measured at layer 1 (LI). The UE may send LI measurement reports (e.g., SSB or CSLRS measurement reports, which include measurements of one or more signal parameters for one or more cells) to a gNB, source DU or serving cell. These LI measurement reports may be sent periodically, for example, or aperiodically. L1 / L2 measurement reports may include no averaging or filtering of measurement values or may include less averaging or filtering than what is performed for L3 measurement reports. LI (or L1 / L2) measurement reports may be transmitted by a UE to a serving network node or source DU and may cause the network node to trigger or initiate a L1 / L2 triggered mobility (LTM) handover of the UE to another cell. LI measurements (e.g., RSRP RSRQ, RSSI) may be provided or reported periodically to the DU (MAC / PHY).

[0036] Layer 3 (L3) measurement reports may be event-based measurement reports, e.g., which may be triggered when a cell (e.g., a neighbour cell) has a RSRP or RSSI (or other signal parameter) that meets some handover (HO) event criteria. For example, a L3 measurement report may be transmitted by a UE to a serving cell or network node if, e.g., a serving cell measured signal becomes / is worse than a threshold, a neighbour cell signal measurement is or becomes better than a first threshold and / or serving cell signalmeasurement becomes an offset threshold worse than a neighbouring cell’s signal measurement, etc. Thus, L3 measurement reports may be event-triggered measurement reports.

[0037] The L3 measurement report may include or may be based on averaging and / or filtering of multiple signal samples, or averaging over a longer period of time, as compared to the LI measurement report. Also, L3 measurement reports may be transmitted to a CU, and may be event-triggered measurement reports and may trigger a network node to initiate or trigger a handover (e.g., L3 handover, which may be basic handover or conditional handover) of the UE to another cell. A L3 handover (L3 HO) may be, for example, based on a L3 measurement report. In response to receiving a L3 measurement report from a UE, a source network node (e.g., gNB, or source CU) may send a handover request to a target network node (e.g., target CU). The source network node may transmit to the UE a RRC reconfiguration message including a HO command to cause the UE to perform handover to the target cell, or a conditional handover (CHO) configuration (to configure the conditional handover conditions that will trigger or cause the UE to initiate CHO to the target cell). Because the L3 HO (either HO or CHO) is based on a L3 measurement report, e.g., which may require more time to obtain or measure (e.g., based on more signal measurement samples and / or filtering and / or averaging of the measurement samples) as compared to a LI measurement report, the L3 measurement report may be transmitted by a UE well after radio conditions with a serving cell / serving network node have already degraded. If a handover configuration is not already prepared for a HO or CHO to the target cell, then the source network node may need to send a message to the target node to request and prepare the HO configuration for the UE, which may cause significant delay, e.g., of 100ms or more, before the UE can perform a L3 HO or CHO to the target cell. This significant delay may increase the likelihood the UE will suffer a radio link failure (RLF) or loss in connectivity.

[0038] In 3GPP Release 18, additional mobility enhancements, for example layer 1 / layer 2 or Ll / L2-triggered mobility (LTM) is introduced to facilitate faster inter-cell mobility than traditional mobility mechanisms based on RRC signaling. LTM is a procedure in which a gNB may receive LI or L2 or L3 measurement report(s) from a UE, and on this basis the gNB may change a serving cell of the UE by a cell switch command that may be transmitted or signaled via a media access control (MAC) control element (CE) (e.g., MAC-CE). Thecell switch command may indicate an LTM candidate cell configuration that the gNB previously prepared and provided to the UE through RRC signaling. In an example, the LTM candidate cell configuration may be within a configuration message such as RRC and may be part of an information element (IE) such as an LTM-Config IE. In an example, based on receiving the cell switch command, the UE may switch to a target cell (or a target cell configuration) according to the cell switch command, where the target cell is one of the candidate cells in the LTM candidate cell configuration. The LTM procedure may be employed to reduce latency of a mobility procedure. When LTM is configured by the network, it may be possible to activate transmission configuration indicator (TCI) states of one or more cells (e.g., multiple cells) that are different from the current serving cell of the UE. In an example, the TCI state may correspond to one or more downlink reference signals, either synchronization signal block (SSB), configured periodic CSLRS, or configured tracking reference signals (TRS), where each reference signal is associated with a specific quasi co location (QCL) type. For example, the TCI states of the LTM candidate cells may be activated in advance before any of those cells become the serving cell. This allows the UE to be downlink (DL) synchronized with those cells, thereby facilitating a faster cell switch to one of the one or more cells when cell switch is triggered. This is because with early DL synchronization, there is no need to synchronize again to access the target cell after the cell switch is triggered.

[0039] When configured by the network, it is possible to initiate uplink (UL) timing advance (TA) acquisition (called early TA) procedure of one or more cells (or multiple cells) that are different from the current serving cell. If the cell has the same timing offset (NT A) as the current serving cell or NTA=0, early TA acquisition procedure may not be required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure may be triggered by physical downlink control channel (PDCCH) order (e.g., a mechanism by which the gNB may force the UE to transmit a physical layer random access channel (PRACH)) preamble as part of a random access (RACH) procedure, or realized through UE based TA measurement as configured by a RRC procedure (e.g., RRC or RRC message). In an example, the gNB to which the candidate cell belongs may calculate the TA value and may send it to the gNB to which the serving cell belongs. The serving cell may send the TA value in the LTM cell switch command MAC-CE when triggering LTM cell switch. In another example, the UEmay perform the TA measurement for the candidate cells after being configured by the RRC procedure. In an example, the exact time the UE performs TA measurement may be determined by the UE (e.g., may be up to the UE implementation). The UE may apply the measured TA value and may perform random access channel (RACH) less (e.g., RACH- less) LTM procedure upon receiving the cell switch command. In an example, the network may send a TA value in the LTM cell switch command MAC-CE e.g., without early TA acquisition.

[0040] In an example, depending on the availability of a valid TA value, the UE may perform either a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command, the UE may apply the TA value as instructed (e.g., indicated, configured, and / or the like) by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE may apply the TA value by itself if available. Meanwhile, the UE may perform RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE may perform RACH-based LTM cell switch (in which a random access (RACH) procedure is performed by the UE with the target cell).

[0041] In an example, regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, the UE may follow the PDCCH order, which may include performing a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. In another example, regardless of whether the UE has already performed a random access procedure towards the candidate cells, the UE may follow the UE-based measurement configuration if configured by the network.

[0042] In an example, for RACH-less LTM, the UE may access the target cell using either a configured grant or a dynamic grant. The configured grant may be provided in the LTM candidate configuration, and the UE may select the configured grant occasion associated with the beam indicated in the cell switch command. In an example, upon initiation of LTM cell switch to the target cell, the UE may start to monitor PDCCH on the target cell for dynamic scheduling. In an example, before RACH-less LTM procedure completion, the UE may not trigger random access procedure if it does not have a valid Physical Uplink Control Channel (PUCCH) resource for triggered scheduling requests (SRs).

[0043] In an example, a security key may be maintained upon an LTM cell switch. In an example, subsequent LTM procedures may be supported by the UE and / or the network. In an example, the LTM procedure may support intra-gNB-DU mobility, intra-gNB-CU mobility, and / or inter-gNB-DU mobility. LTM procedure may support intra-frequency and inter-frequency mobility, including mobility (handover or cell switch) to inter-frequency cell that is not a current serving cell. Accordingly, LTM may be supported for licensed spectrum. In another example, while the UE has stored LTM candidate configurations, the UE may also execute any L3 handover command sent by the network (e.g., the base station, gNB, eNB, NG-RAN, a cell of the base station, and / or the like).

[0044] In an example embodiment, a beam may refer to a beam index associated with a reference signal, such as, for example a beam reference signal, a reference signal beam, a reference signal, a TCI state associated with a reference signal, a reference signal associated with a beam index, a channel state information reference signal (CSLRS) signal associated with a beam, and / or the like.

[0045] In an example embodiment, the term “beam” herein is used synonymously with “spatial filter” or “spatial-domain filter”, as found in 3GPP specifications.

[0046] In an example embodiment, an indication of a transmission beam of a candidate cell may be in the form of a resource indicator, such as a channel state information reference signal (CSLRS) resource indicator (CRI) or synchronization signal or physical broadcast channel (SS) / PBCH block resource indicator (SSBRI).

[0047] In an example implementation, time and frequency resources that can be used by the UE to report CSI may be controlled by the gNB. The CSI may include a channel quality indicator (CQI), precoding matrix indicator (PMI), the CSLRS resource indicator (CRI), SS / PBCH block resource indicator (SSBRI), layer indicator (LI), rank indicator (RI), Ll-RSRP, and / or the like.

[0048] In an example embodiment, a transmission (or sending) from a UE to a network node (e.g., a base station) may be via a cell of the network node or the base station. In an example, a reception (or receiving) by the UE from the network node (or base station) may be via the cell of the network node (or base station). In an example, the network node may be a base station (BS), a gNB, a BS-DU, a gNB-DU, a gNB-CU, and / or the like.

[0049] FIG. 2 is a diagram illustrating an example procedure for LTM. At step 1, the UE 210 may send a measurement report message to the gNB 220. In an example, the UEmay be in RRC connected state or mode. The gNB 220 may determine or decide to configure LTM and may initiate LTM preparation. At step 2, the gNB 220 may transmit an RRC reconfiguration message to the UE 210 that may include the LTM candidate configurations. At step 3, the UE 210 may store the LTM candidate configurations and transmit an RRC reconfiguration complete message to the gNB 220. At step 4a, the UE 210 may perform DL synchronization with the candidate cell(s) before receiving the cell switch command. At step 4b, when UE-based timing advance (TA) measurement is configured, the UE 210 may acquire the TA value(s) of the candidate cell(s) by measurement. The UE 210 may perform early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command. This may be done via contention free random access (CFRA) triggered by a PDCCH order from the source cell. In order to minimize the data interruption due to CFRA during a switch from the source cell to the candidate cell(s), the UE 210 may not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell may be indicated in the cell switch command. In an example, the UE 210 may not maintain the TA timer for the candidate cell and may rely on network implementation to guarantee the TA validity. At step 5, the UE 210 may perform LI measurements on the configured candidate cell(s) and transmit LI measurement reports to the gNB 220. At step 6, the gNB 220 may determine or decide to execute cell switch to a target cell and may transmit a MAC-CE. The MAC-CE may trigger a cell switch by including (or indicating) the candidate (or candidate cell) configuration index of the target cell. Based on receiving the MAC-CE (or cell switch command), the UE 210 may typically then perform cell switch (or RRC) processing for the target candidate cell configuration in which the UE decodes and performs validity confirmation of the target candidate cell configuration identified by the MAC-CE (where the target candidate cell configuration was one of N (e.g., 8) candidate cell configurations previously received by the UE via message 2 above), and then the UE may perform a cell switch to the target cell and may apply the target candidate cell configuration indicated by candidate configuration index. At step 7, the UE 210 may perform the random access procedure towards the target cell, if UE 210 does not have a valid TA of the target cell. At step 8, the UE 210 may complete the LTM cell switch procedure by sending an RRC reconfiguration complete message to the target cell. If the UE 210 has performed a random access (RA) procedure in step 7, the UE 210 mayconsider or determine that the LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE 210 may determine or consider that the LTM cell switch execution is successfully completed when the UE 210 determines that the network has successfully received its first UL data.

[0050] In an example, to reduce the LTM cell switch delay compared to L3 -based handover delay, early DL synchronization based on candidate TCI state activation for one or more LTM candidate cells may be employed. For example, the network (or a network node) may activate one or more LTM TCI states for one or more candidate cells before the cell switch with separate MAC-CEs for each candidate cell. In an example, a joint downlink and uplink (DL / UL) TCI state (e.g., in a case of a unified TCI state type = joint) or a pair of DL and UL TCI states (in a case of unified TCI state type = separate) may be provided. In an example, for an UL TCI state, the network node may provide the UE (e.g., via radio resource control (RRC) messages) with information of pathloss reference signal information (e.g., an information element (IE) such as PathlossReferenceRS-Id) under a joint DL / UL TCI state information element CandidateTCL State or a separate UL TCI state information element CandidateTCI-UL- State IE. In an example, pathlossReferenceRS-Id may indicate a pathloss reference RS, e.g., PathlossReferenceRS IE of the candidate cell that corresponds to the CandidateTCL State IE. In an example, PathlossReferenceRS IE may refer to one of the pathloss reference RSs (e.g., PathlossReferenceRS) configured within LTM TCI information IE (e.g., LTM-TCI-Info). In an example, a SSB, or the like may be included as reference signal when PathlossReferenceRS is included within a CandidateTCLState IE.

[0051] In an example, in case of the joint TCI states, e.g., the joint DL / UL TCI states, maximum number of MAC-CE activated joint LTM TCI states per candidate cell may be one of { 1, 2, 3, 4, ....15, 16}, and maximum number of MAC-CE activated joint LTM TCI states across candidate cells and serving cells may be one of { 1, 2, 3, 4, 8, 16, 32}. The selection of the maximum values may be performed based on the UE capability indicated for these features.

[0052] In an example, in case of the separate DL and UL TCI states, e.g., TCI state type = separate, then maximum number of MAC-CE activated DL TCI states per candidate cell may be one of { 1,2, 3, 4, 5, 6, 7, 8}, and maximum number of MAC-CE activated DL TCI states across all candidate cells and serving cells may be one of { 1,2,3,8,16}, andmaximum number of MAC-CE activated UL TCI states per candidate cell may be one of { 1,2, 3, 4, 5, 6, 7, 8}, and maximum number of MAC-CE activated UL TCI states across all candidate cells and serving cells may be one of { 1,2,3,8,16}. The selection of the maximum values may be performed based on the UE capability indicated for these features.

[0053] In an example, maintaining pathloss estimates may include tracking, measuring and / or storing pathloss measurements with respect to a reference signal (RS). In an example, maintaining the pathloss estimates by the UE may be used in serving cell beam management procedures. In an example, a pathloss may be a measure of how much a signal's power attenuates as it travels through a propagation path. In an example, the pathloss may be expressed in decibels (dB) and may be calculated by subtracting a received power from a transmit power. In an example, maintaining the pathloss estimates may include frequent (or periodic, aperiodic, and / or the like) measurements of the pathloss, and storing the measurements (in memory of the UE), or a one-time measurement of the pathloss and storing the measurement for a period of time.

[0054] Therefore, maintaining pathloss estimates, pathloss measurements or determinations of pathloss estimates may be important when determining or calculating an uplink power of transmissions by the UE. In an example, uplink power control in a UE may determine a power (or transmit power) for a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), a sounding reference signal (SRS), and PRACH transmissions.

[0055] In an example embodiment, for a cell switch (or the LTM cell switch) purpose in LTM, up to 32 joint DL / UL TCI states or 16 UL TCI states (in case of separate TCI states) may be activated or pre-activated, e.g., before receiving a cell switch command from a network node, if the UE indicates such support. For example, a total number of LTM TCI states may be across candidate cells and serving cells, e.g., the total may include the number of activated TCI states of candidate cells and the number of activated TCI states of the serving cells.

[0056] In an example, a UE may be able to simultaneously maintain up to four pathloss estimates per serving cell for all PUSCH / PUCCH / SRS transmissions.

[0057] In existing technologies, a UE may be able to simultaneously maintain up to four pathloss estimates per serving cell for all PUSCH / PUCCH / SRS transmissions. In anexample, the capability of the UE may also be limited to a number of pathloss estimates (that can be maintained) for candidate cells, and therefore, the UE may not maintain pathloss estimates for all activated TCI states for all configured candidate cells. Therefore, during a cell switch procedure or LTM cell switch, the UE may receive a cell switch command indicating a candidate TCI state and / or a candidate cell for which the UE has not maintained the pathloss estimate. In an example, when a pathloss estimate is not maintained for candidate TCI state (that may be an indicated joint / UL TCI state in the cell switch command) and / or candidate cell (that maybe a target cell), the cell switch or the LTM cell switch delay may be increased. When the cell switch delay is increased, system performance degradation may occur as longer cell switch delay may cause a handover failure or even a radio link failure.

[0058] Example embodiments are directed to enhancements of UE behaviour and improvement of signaling between the UE and a network node (e.g., a base station, an eNB, a gNB, a serving cell of the gNB, and / or the like). Example embodiments enable the UE to determine or select candidate TCI states (e.g., TCI states associated with at least one candidate cell) and / or candidate cells (according to the UE capability on a maximum number of pathloss estimates that can be maintained by the UE) for which maintaining the pathloss estimate should be performed. In an example, measurement of pathloss (that may also include or followed by processing, estimation, and other computations) for maintaining the pathloss estimate may take additional time (e.g., tens of milliseconds or more) and may cause additional delay during a cell switch or a LTM cell switch. Thus, it is beneficial to perform the pathloss measurements or pathloss estimates corresponding to the candidate TCI states or TCI states associated with at least one candidate cell (that may be indicated as potential joint or UL TCI state in the cell switch command) and / or candidate cells (that may be potential target cells) before execution of the LTM cell switch, so that the LTM cell switch phase of the procedure can be performed with a lower delay.

[0059] As a result, when example embodiments are implemented, the UE may have performed the pathloss measurements and maintained the pathloss estimates before receiving a cell switch command from the network node or the serving cell of the network node. Therefore, example embodiments may result in the cell switch to be performed with less delay. If example embodiments are not implemented, the UE may maintain pathloss estimates for candidate TCI states (e.g., TCI states associated with at least one candidatecell) and / or candidate cells that may be unlikely to be indicated as potential joint or UL TCI state and / or target cell. Therefore, maintaining the pathloss estimates that are not useful during the LTM cell switch phase may cause inefficient use of resources and additional delays during the LTM cell switch phase of the LTM procedure.

[0060] Example embodiments may improve the performance of a communication system by enhanced decision making on the UE side on selection of candidate cells for which the pathloss estimates are to be maintained. For example, it may be advantageous if the UE maintains pathloss estimates for candidate cells that are more likely to be a target cell during a cell switch phase of the LTM procedure. The determining or selecting a proper set of candidate cells (for which the pathloss estimate maintenance may be performed) may be subject to a UE capability constraint for a maximum number of candidate cells (reference signals (RSs), activated TCI states, or TCI states) for which a pathloss estimate may be maintained. For example, the UE capability may be related to a number of pathloss estimates that can be maintained for multiple (N) candidate cells. In an example embodiment, the UE may be capable of maintaining pathloss estimates for up to N candidate cells where N may be an integer value such as 2, 4, 5, 6, and / or the like. In an example embodiment, the UE may be capable of maintaining pathloss estimates for up to N TCI states of at least one candidate cell where N may be an integer value such as 2, 4, 5, 6, and / or the like. In another example, the UE may be capable of maintaining pathloss estimates for up to N RSs of at least one candidate cell for which a TCI state was activated where N may be an integer value such as 2, 4, 5, 6, and / or the like. In addition, according to an example embodiment, the network node may become aware of the pathloss estimates maintained by the UE. For example, the network node may leverage information about pathloss estimates on the UE side to estimate the cell switch or a handover interruption delay. For example, if the pathloss estimates are not maintained, for a TCI state indicated in the cell switch command, a larger cell switch or handover delay should be expected by the network node. According to an alternative example, information about pathloss estimates that are maintained by the UE may assist the network node to select an appropriate TCI state (for indication to the UE) such that the cell switch or handover interruption can be reduced or minimized.

[0061] Thus, according to an example embodiment, a UE (that is capable of maintaining N pathloss estimates) may receive from a serving cell of a network node,information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells. The UE may receive from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells. The UE may determine N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates. In an example, the UE may maintain the pathloss estimates for the N activated TCI states. In an example, the UE may receive a cell switch command indicating a TCI state and a candidate cell. For example, the cell switch command may indicate one of the N activated TCI states then the UE may perform a cell switch to the candidate cell for which the cell switch command was received. In an example, the UE may be capable of maintaining N pathloss estimates associated with the configured one or more candidate cells. As a result, when the example embodiment is implemented, the UE may have performed the pathloss measurements and maintained the pathloss estimates before receiving the cell switch command from the serving cell. Therefore, the cell switch may be performed with less delay. On the contrary, if the example embodiment is not implemented, the UE does not know for which candidate cells the pathloss estimates should be maintained. Therefore, the UE may maintain pathloss estimates for candidate cells that may be unlikely to be potential target cells or the UE may maintain pathloss estimates for candidate TCI states (e.g., TCI states associated with at least one candidate cell) that may be unlikely to be potential indicated joint or UL TCI state in the cell switch command. Therefore, maintaining pathloss estimates that are not useful during the LTM cell switch phase may cause inefficient use of resources and additional delays during the LTM cell switch phase of the LTM procedure.

[0062] In an example, maintaining the pathloss estimates for the N activated TCI states may include maintaining the pathloss estimates for reference signals (RSs) associated with the activated TCI states.

[0063] In an example, maintaining the pathloss estimate of a TCI state, an activated TCI state, a candidate cell or a RS of the candidate cell may include estimating a pathloss at least once for the RS associated with the TCI state or the activated TCI state of the candidate cell. When a TCI state includes a pathloss RS information, then maintaining the pathloss estimate of a TCI state may include estimating a pathloss at least once for thepathloss RS associated with the TCI state. In an example, the estimate of the pathloss may include a measure of a loss in signal strength of the RS through free space.

[0064] In an example, when the UE is capable of maintaining up to N pathloss estimates, the UE may determine N candidate cells and / or TCI states that are more likely to be target cell and / or indicated joint or UL TCI state. Therefore, in an example implementation, the UE may select N TCI states for which TCI state activations were received recently (e.g., most recently). For example, the activated TCI states may be associated with the at least one candidate cell of the one or more candidate cells.Therefore, the UE may determine to maintain the pathloss estimates for the N TCI states for which TCI state activation was received recently.

[0065] In another example implementation, the UE may choose the N activated TCI states based on a signal strength of RSs. In other words, the N activated TCI states for maintaining the pathloss estimates may be based on the N TCI states associated with RSs with strongest received signals. In an example, RSs associated with a TCI state may include pathloss RS or RS given as in quasi co-location (QCL) information associated with the TCI state. In an example embodiment, the UE may stop maintaining pathloss estimates for TCI states that are deactivated. In another example, when more recent activated TCI states exist, then the UE may stop maintaining the pathloss estimates for the less recent activated TCI states and replace them with the most recent activated TCI states such that the total number of the activated TCI states for which the pathloss estimates are maintained by the UE does not exceed N.

[0066] In an example embodiment, the UE may receive one TCI activation command for k TCI states of the at least one candidate cell, wherein k>N. For example, the k TCI states may be listed in the TCI activation command based on an order. Then the UE may select the N TCI states out of the k TCI states based on the ordered list of the k TCI states listed in the TCI activation command or based on RSs associated with TCI states with strongest received signals. In an example, the order may be based on the order that the items (e.g., the TCI states) in the list are received (e.g., in the ascending or descending order of the listed TCI states) and / or decoded by the UE (e.g., in the ascending or descending order of the decoded TCI states). Alternatively, the order may be based on an index associated with the k listed TCI states.

[0067] In an example embodiment, maintaining the pathloss estimates may include maintaining pathloss estimates simultaneously. For example, the pathloss estimates may be maintained simultaneously for N TCI states or N activated TCI states per candidate cell. In an example, the pathloss estimates may be maintained simultaneously for N TCI states or N activated TCI states of the at least one candidate cell. In an example, the pathloss estimates may be maintained simultaneously for N TCI states or N activated TCI states across all candidate cells. In an example, the pathloss estimates may be maintained simultaneously for the N TCI states or N activated TCI states of the N candidate cells, wherein each TCI state or each activated TCI state may be associated with one of the N candidate cells. In an example, up to L pathloss estimates may be maintained for up to S candidate cells, wherein S may be less than or equal to a number of the one or more candidate cells. In an example, the pathloss estimates may be maintained for N RSs per candidate cell. In another example, the pathloss estimates may be maintained for the N RSs of the N candidate cells, wherein each RS may be associated with one of the N candidate cells.

[0068] In an example, the UE may determine that a number of RSs for pathloss maintenance for which the TCI state is activated is less than N. In an example implementation the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated. For example, the UE may select among the remaining set of RSs, based on a most recent measurement of strongest received RSs (of the remaining set of RSs). For example, the RSs may be associated with at least one candidate cell. In an example, the determination of the strongest received RSs may be based on at least one of: a layer 1 reference signal received power (RSRP), a layer 3 RSRP, and / or the like. In an alternative implementation, when the number of RSs for which the TCI state is activated is less than N, the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, for which at least a condition for event triggered (LI or L3) measurement reporting is fulfilled or for which an event triggered (LI or L3) measurement report has been sent. In an alternative implementation when the number of RSs for which the TCI state is activated is less than N, the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, for which at least a timing advance (TA) acquisition procedure was performed once recently. For example, the TA acquisitionprocedure may be based on at least one of: a physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) transmission, or a UE based (or UE initiated) TA acquisition. The UE based TA acquisition may be based on the information of the LTM configuration.

[0069] In an example, the TA acquisition may be performed as follows. The UE may receive from the network node, a network triggered physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) procedure indicating a request to perform the PRACH procedure with a candidate cell of the at least one candidate cell using a RS. Then, the UE may transmit the candidate cell, a random access request message. In another example, the TA acquisition may be performed as follows. The UE may receive from the network node, a radio resource control (RRC) message indicating a candidate cell for which the user device can perform UE based TA acquisition procedure. Then the UE may perform measurements to estimate a received downlink timing difference between the serving cell and the candidate cell. The UE may then estimate the TA for the candidate cell using the received downlink timing difference between the serving cell and the candidate cell and the TA of the serving cell.

[0070] In an example, the UE may maintain up to N pathloss estimates across candidate cells and a serving cell (or serving cells). In other words, the UE capability of maintaining pathloss estimates for one or more RSs may be shared between the current serving cell and the LTM candidate cells. In order to maintain a pathloss estimate for an RS associated with a candidate cell, the UE may need to stop maintaining pathloss estimate for an RS associated with the serving cell, and vice versa. For example, the N pathloss estimates may include X pathloss estimates for X activated TCI states of the serving cell and Y pathloss estimates for Y activated TCI states of the at least one candidate cell. In other words, a total number of pathloss estimates X+Y may not exceed N. When the total number of pathloss estimates across candidate cells and serving cell pathloss estimates exceeds N, the UE may then stop maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0071] In an example embodiment, the determination of maintaining the N pathloss estimates may be based on a timing advance (TA) acquisition status of the candidate cells. For example, the UE may receive from a serving cell of a network node, information of LTM configuration for one or more candidate cells. In an example, the UE may perform atiming advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells. In an example, the UE may determine to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed. In an example, the UE may maintain the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed. The UE may receive from the serving cell of the network node, a cell switch command for a candidate cell. For example, the cell switch command may be associated with one of the N RSs. In other words, the indicated joint / UL TCI state in cell switch command may be associated with one of the N RSs. Then based on the cell switch command, the UE may perform a cell switch to the candidate cell for which the cell switch command was received. In an example, the UE may be capable of maintaining N pathloss estimates associated with configured one or more candidate cells. As a result, when the example embodiment is implemented, the UE may have performed the pathloss measurements and maintained the pathloss estimates based on the TA information before receiving the cell switch command from the serving cell. Therefore, the cell switch may be performed with less delay. On the contrary, if the example embodiment is not implemented, the UE does not know for which candidate cells or RSs the pathloss estimates should be maintained. Therefore, the UE may maintain pathloss estimates for candidate cells that may be unlikely to be potential target cells and / or the UE may maintain pathloss estimates for RSs that may be unlikely to be associated with joint or UL TCI state indicated in the cell switch command. Therefore, maintaining pathloss estimates that are not useful during the LTM cell switch phase may cause inefficient use of resources and additional delays during the LTM cell switch phase of the LTM procedure.

[0072] In an example embodiment, the pathloss estimates may be maintained for N RSs per candidate cell. In an example, the pathloss estimates may be maintained for the N RSs, wherein each RS is associated with one candidate cell.

[0073] In an example, when the UE is capable of maintaining up to N pathloss estimates, the UE may determine N candidate cells that are more likely to be target cells. Therefore, in an example implementation, the UE may maintain the pathloss estimates for the N RSs associated with the at least one candidate cell. For example, the UE may select N most recent RSs for which the TA acquisition procedure was performed. In an example, the UE may also stop maintaining of the pathloss estimates for RSs for which the TAacquisition procedure was performed before the TA acquisition procedure of the N RSs was performed. In other words, the UE may replace the RSs that have older TA acquisition information with the most recent N RSs for which the TA acquisition procedure was performed.

[0074] In an example, when the UE determines to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell the UE may maintain the pathloss estimates based on the N RSs with strongest received signal. For example, the strongest received signal may be determined based on a measurement of at least one of layer 1 reference signal received power (RSRP), e.g., Ll-RSRP of the RSs, or layer 1 signal to interference plus noise ratio (SINR), e.g., Ll-SINR of the RSs.

[0075] In an example, the UE may determine that a number of RSs for which the TA acquisition procedure was performed is less than N. Then, the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, based on a most recent measurement of strongest received RSs of the remaining set of RSs. For example, the strongest received RSs may be determined based on at least one of a layer 1 reference signal received power (RSRP), or a layer 3 RSRP. In another example, when the number of RSs for which the TA acquisition procedure was performed is less than N, the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which at least a condition for event triggered (LI or L3) measurement reporting is fulfilled or for which an event triggered (LI or L3) measurement report has been sent. In another example, when the number of RSs for which the TA acquisition procedure was performed is less than N, the UE may maintain the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which a most recent transmission configuration indicator (TCI) state activation was received.

[0076] In another example, the user device may maintain up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell. In an example, a total number of pathloss estimates X+Y may not exceed N. In an example, the UE may then stop maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N. In other words, the UE capability of maintaining pathloss estimates for oneor more RSs may be shared between the current serving cell and the LTM candidate cells. In order to maintain pathloss estimates for an RS associated with a candidate cell, the UE may need to stop maintaining pathloss for an RS associated with the serving cell, and vice versa.

[0077] An example embodiment may be based on receiving information (such as assistance information, configuration, and / or the like) from a network node that may include information of maintaining pathloss estimates. For example, the UE may receive from a serving cell of a network node, information of LTM configuration for one or more candidate cells. The UE may then receive from the network node, information of maintaining pathloss estimates associated with M candidate cells e.g., via a RRC message, MAC-CE, DCI, or a lower layer message in ASN.1 format. The UE may determine N reference signals (RSs) associated with at least one candidate cell of the M candidate cells, wherein N<=M. The UE may then maintain the pathloss estimates for the N RSs. In an example, the UE may receive a cell switch command for a candidate cell. For example, the cell switch command may be associated with one of the N RSs (e.g., indicated joint or UL TCI state in the cell switch command is associated with one of the N RSs). Then based on the cell switch command, the UE may perform a cell switch to a candidate cell associated with one of the N RSs for which the cell switch command was received. In an example, N may be less than or equal to M. In an example, the UE may be capable of maintaining N pathloss estimates associated with configured one or more candidate cells. As a result, when the example embodiment is implemented, the UE may have performed the pathloss measurements and maintained the pathloss estimates based on the set of M candidate cells before receiving the cell switch command from the serving cell. Therefore, the cell switch may be performed with less delay. On the contrary, if the example embodiment is not implemented, the UE does not know for which candidate cells the pathloss estimates should be maintained. Therefore, the UE may maintain pathloss estimates for candidate cells that may be unlikely to be potential target cells. Therefore, maintaining pathloss estimates that are not useful during the LTM cell switch phase may cause inefficient use of resources and additional delays during the LTM cell switch phase of the LTM procedure.

[0078] In an example embodiment, the information of maintaining the pathloss estimates associated with the M candidate cells may include a set of M candidate cells listed in a sequential order of candidate cells for maintaining the pathloss estimates. Forexample, the order may indicate priority information wherein based on the priority information, some candidate cells may have higher priority over others for maintaining the pathloss estimates. Then the UE may select the N RSs associated with the at least one candidate cell. For example, the at least one candidate cell may be selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates. In other words, maintaining the pathloss estimates may include maintaining the pathloss estimates for the selected N RSs of the selected at least one candidate cell. In another example, the N candidate cells may be selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates. Then, the UE may maintain the pathloss estimates for RSs of the selected N candidate cells.

[0079] In an example, the UE may start maintaining the pathloss estimates upon receiving a configuration information of measurement reporting of a candidate cell, or upon receiving an activation of the configuration information of the measurement reporting. For example, the configuration information of the measurement reporting may include indication of at least one of: an identifier of the candidate cell, periodic measurement reporting, aperiodic measurement reporting, and / or the like.

[0080] In an example, the UE may select the N RSs associated with the at least one candidate cell, based on at least one of a best received signal strength or a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates. For example, the best received signal strength may be determined based on at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the N RSs, or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the N RSs. For example, maintaining the pathloss estimates may include maintaining the pathloss estimates for the N RSs with the best received signal strength.

[0081] In an example, the information of maintaining the pathloss estimates may include at least one of: instructions indicating criteria for selecting the N RSs associated with the at least one candidate cell for which the pathloss estimates to be maintained, information of the N RSs for which the pathloss estimates to be maintained, instructions indicating criteria for selecting N candidate cells for which the pathloss estimates to be maintained, information of the N candidate cells for which the pathloss estimates to be maintained, and / or the like. For example, the criteria for selecting the N candidate cellsmay include at least one of: selecting N most recent candidate cells for which a timing advance (TA) acquisition procedure was performed by the user device, selecting N candidate cells with a strongest received reference signal (RS), selecting N most recent candidate cells for which a TCI activation procedure was performed, selecting N most recent candidate cells for which a condition for an event triggered (LI or L3) measurement reporting is fulfilled, or for which an event triggered (LI or L3) measurement report has been sent, and / or the like. In an example, the criteria for selecting the N RSs may include selecting the N RSs with a strongest received reference signal (RS). For example, the strongest received RS may be determined based on a measurement of at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the RS, or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the RS. For example, the information of the N RSs may include identifiers of the N RSs. In another example, the information of the N candidate cells may include identifiers of the N candidate cells e.g., cell ID.

[0082] In an example, the network node may determine to update the information of maintaining the pathloss estimates associated with the M candidate cells. Then the UE may receive from the network node, an update of the information of maintaining the pathloss estimates associated with the M candidate cells. For example, the update may be received by the UE from the network, via at least one of: a medium access control (MAC) control element (MAC-CE) command, a downlink control information (DCI), lower layer or layer 1 message in an abstract syntax notation one (ASN.l) format, and / or the like. The UE may then select the N RSs associated with at least one of the updated M candidate cells or the at least one candidate cell of the updated M candidate cells.

[0083] In an example embodiment, the UE may maintain up to N pathloss estimates that may include X RSs of the serving cell and Y RSs of the at least one candidate cell. In an example, a total number of pathloss estimates X+Y may not exceed N based on the UE capability. Then the UE may stop maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0084] Another example embodiment may be based on providing information of pathloss estimate maintenance from the UE to the network node. For example, the UE may indicate to the network node, information of RSs of at least one candidate cell for which the UE maintained pathloss estimates. Therefore, in an example, the UE may receive information of M candidate cells from a network node. In an example, the UE maydetermine to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received. In an example, the UE may maintain the pathloss estimates for the N RSs of the at least one candidate cell. In an example, the UE may transmit to a serving cell of a network node, information of the N RSs (e.g., identifiers of the N RSs, or identifiers of the at least one candidate cell associated with the N RSs) of the at least one candidate cell for which the user device maintained the pathloss estimates. The UE may receive from the serving cell of the network node, a cell switch command for a candidate cell. For example, the cell switch command may be associated with the candidate cell associated with one of the N RSs (e.g., indicated joint or UL TCI state in the cell switch command is associated with one of the N RSs). Then, the UE may perform a cell switch to the candidate cell associated with one of the N RSs for which the cell switch command was received. In an example, N may be less than or equal to M. In an example, the UE may be capable of maintaining N pathloss estimates associated with the M candidate cells. As a result, when the example embodiment is implemented, the UE may have performed the pathloss measurements and maintained the pathloss estimates before receiving the cell switch command from the serving cell. In addition, since the UE indicated to the network node, the RSs for which the pathloss estimates are maintained, the network may take such information into account. Therefore, the cell switch may be performed with less delay when the cell switch command indicates a target cell for which the pathloss estimate was maintained by the UE. On the contrary, if the example embodiment is not implemented, the UE does not know for which candidate cells the pathloss estimates should be maintained. Therefore, the UE may maintain pathloss estimates for candidate cells that may be unlikely to be potential target cells. Therefore, maintaining pathloss estimates that are not useful during the LTM cell switch phase may cause inefficient use of resources and additional delays during the LTM cell switch phase of the LTM procedure.

[0085] In an example, the information of the M candidate cells may include at least one of: LTM configuration of the M candidate cells, TCI state activation for the M candidate cells, information to perform TA acquisition with the M candidate cells, and / or the like.

[0086] In an example, the information of the N RSs of the at least one candidate cell may include measurement information of signal strength (e.g., Ll-RSRP, L3-RSRP, and / orthe like) of the N RSs for which the pathloss estimates were maintained. For example, the information of the N RSs of the at least one candidate cell may include a single bit flag indication for each of (or corresponding to) the N RSs indicating whether a pathloss estimate is maintained for each of the N RSs. For example, when the single bit flag indication is 1, it may indicate that the pathloss estimate for a corresponding RS is maintained, and when the single bit flag indication is 0, it may indicate that the pathloss estimate for the corresponding RS is not maintained. In an example, the UE may maintain the pathloss estimates for the N RSs of the at least one candidate cell for which a condition for event triggered LI and / or L3 measurement reporting is fulfilled or for which an event triggered LI or L3 measurement is sent. The measurement based on the event may indicate to the network or network node about the RSs for which the pathloss estimate is maintained by the UE. In this option, the UE may estimate and maintain the pathloss estimates from the point in time the condition becomes fulfilled or from the point in time when the UE sends the event-triggered report.

[0087] In an example, the UE may maintain up to N pathloss estimates based on the UE capability. For example, the N pathloss estimates may be for X RSs of the serving cell and Y RSs of the at least one candidate cell such that a total number of pathloss estimates X+Y does not exceed N. Then, the UE may stop maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0088] FIG. 3 is a diagram illustrating an example procedure for LTM according to an example embodiment based on TCI state activation. In an example, prior to step 1, the UE may be in RRC connected state. At step 1, the UE 210 may send a measurement report message to the gNB 220. In an example, the UE may be in RRC connected state or mode. The gNB 220 may determine or decide to configure LTM and may initiate LTM preparation. At step 2, the gNB 220 may transmit an RRC reconfiguration message to the UE 210 that may include the LTM candidate configurations, e.g., for candidate cells 1 to 8. At step 3, the UE 210 may store the LTM candidate configurations and transmit an RRC reconfiguration complete message to the gNB 220. At step 4, the UE 210 may perform LI measurements on the configured candidate cell(s) and transmit LI measurement reports to the gNB 220. The gNB 220 may then determine to perform early TCI activation. Therefore, at step 5, the gNB 220 may send a TCI activation command to the UE 210 toactivate TCI state 1 for candidate cell 1. At step 5.1, the UE 210 may maintain pathloss estimate for the activated TCI state 1.

[0089] At step 6 of FIG. 3, the UE 210 may perform LI measurements on the configured candidate cell(s) and transmit LI measurement reports to the gNB 220. At step 7, the gNB 220 may send a TCI activation command to the UE 210 to activate TCI states 1, 2, 3, and 4 for candidate cell 2. At step 7.1, the UE 210 may maintain pathloss estimates for the activated TCI states 1, 2, 3, and 4 of candidate cell 2 and may stop maintaining the pathloss estimate for the TCI state 1 of the candidate cell 1. The gNB 220 may determine or decide to execute cell switch to a target cell 230. Then at step 8, the gNB 220 may transmit a MAC-CE for a cell switch command to the UE 210. The cell switch command may indicate TCI state 2, and candidate cell 2. For example, the MAC-CE may trigger a cell switch by including (or indicating) the candidate (or candidate cell) configuration index of the target cell 230. Based on receiving the MAC-CE (or cell switch command), the UE 210 may then perform cell switch (or RRC) processing for the target cell 230 (e.g., candidate cell 2). In an example, the UE 210 may perform a cell switch to the target cell 230 (candidate cell 2) and may apply the target cell 230 configuration indicated by candidate configuration index. At step 8.1, the UE 210 may detach from the source or serving cell 220 and apply the target cell 230 configurations. At step 9, the UE 210 may perform the RACH procedure towards the target cell 230.

[0090] FIG. 4 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment. Operation 410 includes receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells. Operation 420 includes receiving, by the user device from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells. Operation 430 includes determining by the user device, N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates. Operation 440 includes maintaining the pathloss estimates for the N activated TCI states. Operation 450 includes receiving a cell switch command indicating a TCI state and a candidate cell.

[0091] With respect to the method of FIG. 4, the method may further include: wherein the user device is capable of maintaining N pathloss estimates associated with the configured one or more candidate cells.

[0092] With respect to the method of FIG. 4, the method may further include: selecting N TCI states for which TCI state activations were received recently; and wherein the determining is based on the selected N TCI states of the at least one candidate cell for which the TCI state activation was received recently.

[0093] With respect to the method of FIG. 4, the method may further include: wherein the determining of the N activated TCI states for maintaining the pathloss estimates is based on the N TCI states associated with RSs with strongest received signals.

[0094] With respect to the method of FIG. 4, the method may further include: stopping maintaining the pathloss estimates for a RS for which a TCI state is deactivated.

[0095] With respect to the method of FIG. 4, the method may further include: stopping maintaining of the pathloss estimates for a TCI state that was activated before the N activated TCI states of the at least one candidate cell.

[0096] With respect to the method of FIG. 4, the method may further include: receiving one TCI activation command for k TCI states of the at least one candidate cell, wherein k>N; selecting the N TCI states out of the k TCI states based on an ordered list of the k TCI states listed in the TCI activation command or based on RSs associated with TCI states with strongest received signals; and wherein the determining to maintain the pathloss estimates is based on the selected N TCI states of the at least one candidate cell.

[0097] E With respect to the method of FIG. 4, the method may further include: wherein the cell switch command indicates one of the N activated TCI states and the method further including performing by the user device a cell switch to the candidate cell for which the cell switch command was received.

[0098] With respect to the method of FIG. 4, the method may further include: wherein maintaining the pathloss estimates includes maintaining the pathloss estimates simultaneously; and wherein: the pathloss estimates are maintained for N TCI states or N activated TCI states per candidate cell; the pathloss estimates are maintained for N TCI states or N activated TCI states of the at least one candidate cell; the pathloss estimates are maintained for the N TCI state or N activated TCI states of the N candidate cells, wherein each TCI state or each activated TCI state is associated with one of the N candidate cells;up to L pathloss estimates are maintained for up to S candidate cells, wherein S is less than or equal to a number of the one or more candidate cells; the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs of the N candidate cells, wherein each RS is associated with one of the N candidate cells.

[0099] With respect to the method of FIG. 4, the method may further include: wherein maintaining the pathloss estimate of a TCI state, an activated TCI state, a candidate cell or a RS of the candidate cell includes estimating a pathloss at least once for the RS associated with the TCI state or the activated TCI state of the candidate cell, wherein the estimate of the pathloss includes a measure of a loss in signal strength of the RS through free space.

[0100] With respect to the method of FIG. 4, the method may further include: determining that a number of RSs for which the TCI state is activated is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, based on at least one of: a most recent measurement of strongest received RSs of the remaining set of RSs associated with the at least one candidate cell; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs associated with the at least one candidate cell; and wherein the strongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0101] With respect to the method of FIG. 4, the method may further include: determining that a number of RSs for which the TCI state is activated is less than N; wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, for which at least a timing advance (TA) acquisition procedure was performed once recently; and wherein the TA acquisition procedure is based on at least one of: a physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) transmission; or a user device based TA acquisition that is based on the information of the LTM configuration.

[0102] With respect to the method of FIG. 4, the method may further include: wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates arefor X activated TCI states of the serving cell and Y activated TCI states of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0103] With respect to the method of FIG. 4, the method may further include: stopping maintaining the pathloss estimates for one or more activated TCI states of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0104] With respect to the method of FIG. 4, the method may further include: wherein the maintaining the pathloss estimates for the N activated TCI states includes maintaining the pathloss estimates for reference signals (RSs) associated with the activated TCI states.

[0105] FIG. 5 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment. Operation 510 includes receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells. Operation 520 includes performing, by the user device, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells. Operation 530 includes determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed. Operation 540 includes maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed. Operation 550 includes and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

[0106] With respect to the method of FIG. 5, the method may further include: wherein the user device is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0107] With respect to the method of FIG. 5, the method may further include: wherein the performing the TA acquisition procedure includes: receiving from the network node, a network triggered physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) procedure indicating a request to perform the PRACH procedure with a candidate cell of the at least one candidate cell using a RS; and transmitting, by the user device to the candidate cell, a random access request message.

[0108] With respect to the method of FIG. 5, the method may further include: receiving, by the user device from the network node, a radio resource control (RRC) message indicating a candidate cell for which the user device can perform user devicebased TA acquisition procedure; performing measurements to estimate a received downlink timing difference between the serving cell and the candidate cell; and estimating the TA for the candidate cell using the received downlink timing difference between the serving cell and the candidate cell and the TA of the serving cell.

[0109] With respect to the method of FIG. 5, the method may further include: wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes selecting N most recent RSs for which the TA acquisition procedure was performed.

[0110] With respect to the method of FIG. 5, the method may further include: stopping maintaining of the pathloss estimates for RSs for which the TA acquisition procedure was performed before the TA acquisition procedure of the N RSs was performed.[OHl] With respect to the method of FIG. 5, the method may further include: wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes maintaining the pathloss estimates based on the N RSs with strongest received signal, wherein the strongest received signal is determined based on a measurement of at least one of: layer 1 reference signal received power (RSRP) of the RSs; or layer 1 signal to interference plus noise ratio (SINR) of the RSs.

[0112] With respect to the method of FIG. 5, the method may further include: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, based on at least one of: a most recent measurement of strongest received RSs of the remaining set of RSs; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs; and wherein the strongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0113] With respect to the method of FIG. 5, the method may further include: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which a most recent transmission configuration indicator (TCI) state activation was received.

[0114] With respect to the method of FIG. 5, the method may further include: wherein: the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs, wherein each RS is associated with one candidate cell.

[0115] With respect to the method of FIG. 5, the method may further include: wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0116] With respect to the method of FIG. 5, the method may further include: stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0117] With respect to the method of FIG. 5, the method may further include: wherein the cell switch command is associated with one of the N RSs, and the method further including performing by the user device a cell switch to the candidate cell for which the cell switch command was received.

[0118] FIG. 6 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment. Operation 610 includes receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells. Operation 620 includes receiving, by the user device from the network node, information of maintaining pathloss estimates associated with M candidate cells. Operation 630 includes determining by the user device, N reference signals (RSs) associated with at least one candidate cell of the M candidate cells. Operation 640 includes maintaining the pathloss estimates for the N RSs. Operation 650 includes receiving a cell switch command for a candidate cell.

[0119] With respect to the method of FIG. 6, the method may further include: wherein N is less than or equal to M, and the user device is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0120] With respect to the method of FIG. 6, the method may further include: wherein the information of maintaining the pathloss estimates associated with the M candidate cells includes a set of M candidate cells listed in a sequential order of candidate cells for maintaining the pathloss estimates.

[0121] With respect to the method of FIG. 6, the method may further include: selecting the N RSs associated with the at least one candidate cell, wherein the at least one candidate cell is selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the selected N RSs of the selected at least one candidate cell.

[0122] With respect to the method of FIG. 6, the method may further include: selecting N candidate cells, wherein the N candidate cells are selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for RSs of the selected N candidate cells.

[0123] With respect to the method of FIG. 6, the method may further include: selecting the N RSs associated with the at least one candidate cell, based on at least one of a best received signal strength or a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; wherein the best received signal strength is determined based on at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the N RSs; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the N RSs; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the N RSs with the best received signal strength.

[0124] With respect to the method of FIG. 6, the method may further include: wherein the information of maintaining the pathloss estimates includes at least one of: instructions indicating criteria for selecting the N RSs associated with the at least one candidate cell for which the pathloss estimates to be maintained; information of the N RSs for which the pathloss estimates to be maintained; instructions indicating criteria for selecting N candidate cells for which the pathloss estimates to be maintained; or information of the N candidate cells for which the pathloss estimates to be maintained.

[0125] With respect to the method of FIG. 6, the method may further include: wherein the criteria for selecting the N candidate cells includes at least one of: selecting N most recent candidate cells for which a timing advance (TA) acquisition procedure was performed by the user device; or selecting N most recent candidate cells for which a condition for an event triggered measurement reporting is fulfilled; or selecting N most recent candidate cells for which a TCI activation was performed; or selecting N candidatecells with a strongest received reference signal (RS); and the criteria for selecting the N RSs includes selecting the N RSs with a strongest received reference signal (RS); and wherein the strongest received RS is determined based on a measurement of at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the RS; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the RS.

[0126] With respect to the method of FIG. 6, the method may further include: wherein: the information of the N RSs includes identifiers of the N RSs; and the information of the N candidate cells includes identifiers of the N candidate cells.

[0127] With respect to the method of FIG. 6, the method may further include: receiving an update of the information of maintaining the pathloss estimates associated with the M candidate cells, wherein the update is received via at least one of: a medium access control (MAC) control element (MAC-CE) command; a downlink control information (DCI); or lower layer or layer 1 message in an abstract syntax notation one (ASN. l) format.

[0128] With respect to the method of FIG. 6, the method may further include: determining by the user device to maintain the pathloss estimates for the N reference signals (RSs) associated with at least one of the updated M candidate cells or the at least one candidate cell of the updated M candidate cells.

[0129] With respect to the method of FIG. 6, the method may further include: wherein the user device starts maintaining the pathloss estimates based on at least one of: receiving a configuration information of measurement reporting of a candidate cell; or receiving an activation of the configuration information of the measurement reporting.

[0130] With respect to the method of FIG. 6, the method may further include: wherein the configuration information of the measurement reporting includes indication of at least one of: an identifier of the candidate cell; periodic measurement reporting; or aperiodic measurement reporting.

[0131] With respect to the method of FIG. 6, the method may further include: wherein the information of maintaining the pathloss estimates associated with the M candidate cells is received via at least one of: a radio resource control (RRC) message; a medium access control (MAC) control element (MAC-CE) command; a downlink control information (DCI); or a lower layer or layer 1 message in an abstract syntax notation one (ASN.1) format.

[0132] With respect to the method of FIG. 6, the method may further include: wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0133] With respect to the method of FIG. 6, the method may further include: stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0134] With respect to the method of FIG. 6, the method may further include: wherein the cell switch command is associated with one of the N RSs, and the method further including performing by the user device a cell switch to a candidate cell associated with one of the N RSs for which the cell switch command was received.

[0135] FIG. 7 is a flow chart illustrating operation of an apparatus (e.g., which may be a UE or user device, or other apparatus) according to an example embodiment. Operation 710 includes receiving, by a user device, information of M candidate cells. Operation 720 includes determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received. Operation 730 includes maintaining the pathloss estimates for the N RSs of the at least one candidate cell. Operation 740 includes transmitting, by the user device to a serving cell of a network node, information of the N RSs of the at least one candidate cell for which the user device maintained the pathloss estimates. Operation 750 includes receiving, by the user device from the serving cell of the network node, a cell switch command for a candidate cell.

[0136] With respect to the method of FIG. 7, the method may further include: wherein N is less than or equal to M, and the user device is capable of maintaining N pathloss estimates associated with the M candidate cells.

[0137] With respect to the method of FIG. 7, the method may further include: wherein the information of the M candidate cells includes at least one of: information of layer 1 / layer 2 triggered mobility (LTM) configuration of the M candidate cells; transmission configuration indicator (TCI) state activation for the M candidate cells; or information to perform timing advance (TA) acquisition with the M candidate cells.

[0138] With respect to the method of FIG. 7, the method may further include: wherein the information of the N RSs associated with the at least one candidate cell for which theuser device maintained the pathloss estimates includes at least one of: identifiers of the N RSs; or identifiers of the at least one candidate cell associated with the N RSs.

[0139] With respect to the method of FIG. 7, the method may further include: wherein the information of the N RSs of the at least one candidate cell includes measurement information of signal strength of the N RSs for which the pathloss estimates were maintained, wherein the measurement information includes at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0140] With respect to the method of FIG. 7, the method may further include: wherein the information of the N RSs of the at least one candidate cell includes a single bit flag indication for each of the N RSs indicating whether a pathloss estimate is maintained for each of the N RSs.

[0141] With respect to the method of FIG. 7, the method may further include: wherein: the single bit flag indication being 1 indicates that the pathloss estimate for a corresponding RS is maintained; and the single bit flag indication being 0 indicates that the pathloss estimate for the corresponding RS is not maintained.

[0142] With respect to the method of FIG. 7, the method may further include: wherein the information of the N RSs of the at least one candidate cell is transmitted via at least one of: a radio resource control (RRC) message; an uplink medium access control (MAC) control element (UL MAC-CE) command; or a lower layer or layer 1 message in an abstract syntax notation one (ASN.l) format.

[0143] With respect to the method of FIG. 7, the method may further include: wherein the cell switch command is associated with the candidate cell associated with one of the N RSs, and the method further including performing by the user device a cell switch to the candidate cell associated with one of the N RSs for which the cell switch command was received.

[0144] With respect to the method of FIG. 7, the method may further include: wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0145] With respect to the method of FIG. 7, the method may further include: stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0146] Some examples will now be described, based on the description and figures provided herein.

[0147] Example 1. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells; determining N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates; maintaining the pathloss estimates for the N activated TCI states; and receiving a cell switch command indicating a TCI state and a candidate cell.

[0148] Example 2. The apparatus of Example 1, wherein the apparatus is capable of maintaining N pathloss estimates associated with the configured one or more candidate cells.

[0149] Example 3. The apparatus of Example 2, wherein the apparatus is further caused to perform: selecting N TCI states for which TCI state activations were received recently; and wherein the determining is based on the selected N TCI states of the at least one candidate cell for which the TCI state activation was received recently.

[0150] Example 4. The apparatus of Example 2, wherein the determining of the N activated TCI states for maintaining the pathloss estimates is based on the N TCI states associated with RSs with strongest received signals.

[0151] Example 5. The apparatus of Example 2, wherein the apparatus is further caused to perform stopping maintaining the pathloss estimates for a RS for which a TCI state is deactivated.

[0152] Example 6. The apparatus of Example 2, wherein the apparatus is further caused to perform stopping maintaining of the pathloss estimates for a TCI state that was activated before the N activated TCI states of the at least one candidate cell.

[0153] Example 7. The apparatus of Example 2, wherein the apparatus is further caused to perform receiving one TCI activation command for k TCI states of the at least one candidate cell, wherein k>N; selecting the N TCI states out of the k TCI states based on an ordered list of the k TCI states listed in the TCI activation command or based on RSsassociated with TCI states with strongest received signals; and wherein the determining to maintain the pathloss estimates is based on the selected N TCI states of the at least one candidate cell.

[0154] Example 8. The apparatus of Example 2, wherein the cell switch command indicates one of the N activated TCI states and the apparatus is further caused to perform performing by the apparatus a cell switch to the candidate cell for which the cell switch command was received.

[0155] Example 9. The apparatus of Example 2, wherein maintaining the pathloss estimates includes maintaining the pathloss estimates simultaneously; and wherein: the pathloss estimates are maintained for N TCI states or N activated TCI states per candidate cell; the pathloss estimates are maintained for N TCI states or N activated TCI states of the at least one candidate cell; the pathloss estimates are maintained for the N TCI state or N activated TCI states of the N candidate cells, wherein each TCI state or each activated TCI state is associated with one of the N candidate cells; up to L pathloss estimates are maintained for up to S candidate cells, wherein S is less than or equal to a number of the one or more candidate cells; the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs of the N candidate cells, wherein each RS is associated with one of the N candidate cells.

[0156] Example 10. The apparatus of Example 9, wherein maintaining the pathloss estimate of a TCI state, an activated TCI state, a candidate cell or a RS of the candidate cell includes estimating a pathloss at least once for the RS associated with the TCI state or the activated TCI state of the candidate cell, wherein the estimate of the pathloss includes a measure of a loss in signal strength of the RS through free space.

[0157] Example 11. The apparatus of Example 2, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TCI state is activated is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, based on at least one of: a most recent measurement of strongest received RSs of the remaining set of RSs associated with the at least one candidate cell; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs associated with the at least one candidate cell; and wherein thestrongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0158] Example 12. The apparatus of Example 2, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TCI state is activated is less than N; wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, for which at least a timing advance (TA) acquisition procedure was performed once recently; and wherein the TA acquisition procedure is based on at least one of: a physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) transmission; or an apparatus based TA acquisition that is based on the information of the LTM configuration.

[0159] Example 13. The apparatus of Example 1, wherein the apparatus maintains up to N pathloss estimates, wherein the N pathloss estimates are for X activated TCI states of the serving cell and Y activated TCI states of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0160] Example 14. The apparatus of Example 13, wherein the apparatus is further caused to perform stopping maintaining the pathloss estimates for one or more activated TCI states of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0161] Example 15. The apparatus of Example 1, wherein the maintaining the pathloss estimates for the N activated TCI states includes maintaining the pathloss estimates for reference signals (RSs) associated with the activated TCI states.

[0162] Example 16. A method including: receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, by the user device from the serving cell of the network node, at least one transmission configuration indicator (TCI) state activation for at least one TCI state associated with at least one candidate cell of the one or more candidate cells; determining by the user device, N activated TCI states associated with the at least one candidate cell for which to maintain pathloss estimates; maintaining the pathloss estimates for the N activated TCI states; and receiving a cell switch command indicating a TCI state and a candidate cell.

[0163] Example 17. The method of Example 16, wherein the user device is capable of maintaining N pathloss estimates associated with the configured one or more candidate cells.

[0164] Example 18. The method of Example 17, further including: selecting N TCI states for which TCI state activations were received recently; and wherein the determining is based on the selected N TCI states of the at least one candidate cell for which the TCI state activation was received recently.

[0165] Example 19. The method of Example 17, wherein the determining of the N activated TCI states for maintaining the pathloss estimates is based on the N TCI states associated with RSs with strongest received signals.

[0166] Example 20. The method of Example 17, further including stopping maintaining the pathloss estimates for a RS for which a TCI state is deactivated.

[0167] Example 21. The method of Example 17, further including stopping maintaining of the pathloss estimates for a TCI state that was activated before the N activated TCI states of the at least one candidate cell.

[0168] Example 22. The method of Example 17, further including receiving one TCI activation command for k TCI states of the at least one candidate cell, wherein k>N; selecting the N TCI states out of the k TCI states based on an ordered list of the k TCI states listed in the TCI activation command or based on RSs associated with TCI states with strongest received signals; and wherein the determining to maintain the pathloss estimates is based on the selected N TCI states of the at least one candidate cell.

[0169] Example 23. The method of Example 17, wherein the cell switch command indicates one of the N activated TCI states and the method further including performing by the user device a cell switch to the candidate cell for which the cell switch command was received.

[0170] Example 24. The method of Example 17, wherein maintaining the pathloss estimates includes maintaining the pathloss estimates simultaneously; and wherein: the pathloss estimates are maintained for N TCI states or N activated TCI states per candidate cell; the pathloss estimates are maintained for N TCI states or N activated TCI states of the at least one candidate cell; the pathloss estimates are maintained for the N TCI state or N activated TCI states of the N candidate cells, wherein each TCI state or each activated TCI state is associated with one of the N candidate cells; up to L pathloss estimates aremaintained for up to S candidate cells, wherein S is less than or equal to a number of the one or more candidate cells; the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs of the N candidate cells, wherein each RS is associated with one of the N candidate cells.

[0171] Example 25. The method of Example 24, wherein maintaining the pathloss estimate of a TCI state, an activated TCI state, a candidate cell or a RS of the candidate cell includes estimating a pathloss at least once for the RS associated with the TCI state or the activated TCI state of the candidate cell, wherein the estimate of the pathloss includes a measure of a loss in signal strength of the RS through free space.

[0172] Example 26. The method of Example 17, further including: determining that a number of RSs for which the TCI state is activated is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, based on at least one of: a most recent measurement of strongest received RSs of the remaining set of RSs associated with the at least one candidate cell; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs associated with the at least one candidate cell; and wherein the strongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0173] Example 27. The method of Example 17, further including: determining that a number of RSs for which the TCI state is activated is less than N; wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which TCI states are activated, for which at least a timing advance (TA) acquisition procedure was performed once recently; and wherein the TA acquisition procedure is based on at least one of: a physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) transmission; or a user device based TA acquisition that is based on the information of the LTM configuration.

[0174] Example 28. The method of Example 16, wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X activated TCI states of the serving cell and Y activated TCI states of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0175] Example 29. The method of Example 28, further including stopping maintaining the pathloss estimates for one or more activated TCI states of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0176] Example 30. The method of Example 16, wherein the maintaining the pathloss estimates for the N activated TCI states includes maintaining the pathloss estimates for reference signals (RSs) associated with the activated TCI states.

[0177] Example 31. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; performing, by the apparatus, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determining to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

[0178] Example 32. The apparatus of Example 31, wherein the apparatus is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0179] Example 33. The apparatus of Example 32, wherein the performing the TA acquisition procedure includes: receiving from the network node, a network triggered physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) procedure indicating a request to perform the PRACH procedure with a candidate cell of the at least one candidate cell using a RS; and transmitting, by the apparatus to the candidate cell, a random access request message.

[0180] Example 34. The apparatus of Example 32, wherein the apparatus is further caused to perform: receiving, by the apparatus from the network node, a radio resource control (RRC) message indicating a candidate cell for which the apparatus can perform apparatus based TA acquisition procedure; performing measurements to estimate a received downlink timing difference between the serving cell and the candidate cell; and estimating the TA for the candidate cell using the received downlink timing difference between the serving cell and the candidate cell and the TA of the serving cell.

[0181] Example 35. The apparatus of Example 32, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes selecting N most recent RSs for which the TA acquisition procedure was performed.

[0182] Example 36. The apparatus of Example 32, wherein the apparatus is further caused to perform stopping maintaining of the pathloss estimates for RSs for which the TA acquisition procedure was performed before the TA acquisition procedure of the N RSs was performed.

[0183] Example 37. The apparatus of Example 32, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes maintaining the pathloss estimates based on the N RSs with strongest received signal, wherein the strongest received signal is determined based on a measurement of at least one of: layer 1 reference signal received power (RSRP) of the RSs; or layer 1 signal to interference plus noise ratio (SINR) of the RSs.

[0184] Example 38. The apparatus of Example 32, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, based on at least one of: a most recent measurement of strongest received RSs of the remaining set of RSs; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs; and wherein the strongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0185] Example 39. The apparatus of Example 32, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which a most recent transmission configuration indicator (TCI) state activation was received.

[0186] Example 40. The apparatus of Example 32, wherein: the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs, wherein each RS is associated with one candidate cell.

[0187] Example 41. The apparatus of Example 31, wherein the apparatus maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0188] Example 42. The apparatus of Example 41, wherein the apparatus is further caused to perform stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0189] Example 43. The apparatus of Example 31, wherein the cell switch command is associated with one of the N RSs, and the apparatus is further caused to perform performing by the apparatus a cell switch to the candidate cell for which the cell switch command was received.

[0190] Example 44. A method including: receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; performing, by the user device, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

[0191] Example 45. The method of Example 44, wherein the user device is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0192] Example 46. The method of Example 45, wherein the performing the TA acquisition procedure includes: receiving from the network node, a network triggered physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) procedure indicating a request to perform the PRACH procedure with a candidate cell of the at least one candidate cell using a RS; and transmitting, by the user device to the candidate cell, a random access request message.

[0193] Example 47. The method of Example 45, further including: receiving, by the user device from the network node, a radio resource control (RRC) message indicating a candidate cell for which the user device can perform user device based TA acquisitionprocedure; performing measurements to estimate a received downlink timing difference between the serving cell and the candidate cell; and estimating the TA for the candidate cell using the received downlink timing difference between the serving cell and the candidate cell and the TA of the serving cell.

[0194] Example 48. The method of Example 45, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes selecting N most recent RSs for which the TA acquisition procedure was performed.

[0195] Example 49. The method of Example 45, further including stopping maintaining of the pathloss estimates for RSs for which the TA acquisition procedure was performed before the TA acquisition procedure of the N RSs was performed.

[0196] Example 50. The method of Example 45, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell includes maintaining the pathloss estimates based on the N RSs with strongest received signal, wherein the strongest received signal is determined based on a measurement of at least one of layer 1 reference signal received power (RSRP) of the RSs; or layer 1 signal to interference plus noise ratio (SINR) of the RSs.

[0197] Example 51. The method of Example 45, further including: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, based on at least one of a most recent measurement of strongest received RSs of the remaining set of RSs; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs; and wherein the strongest received RSs is determined based on at least one of a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0198] Example 52. The method of Example 45, further including: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which a most recent transmission configuration indicator (TCI) state activation was received.

[0199] Example 53. The method of Example 45, wherein: the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs, wherein each RS is associated with one candidate cell.

[0200] Example 54. The method of Example 44, wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0201] Example 55. The method of Example 54, further including stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0202] Example 56. The method of Example 44, wherein the cell switch command is associated with one of the N RSs, and the method further includes performing by the user device a cell switch to the candidate cell for which the cell switch command was received.

[0203] Example 57. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, from the network node, information of maintaining pathloss estimates associated with M candidate cells; determining N reference signals (RSs) associated with at least one candidate cell of the M candidate cells; maintaining the pathloss estimates for the N RSs; and receiving a cell switch command for a candidate cell.

[0204] Example 58. The apparatus of Example 57, wherein N is less than or equal to M, and the apparatus is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0205] Example 59. The apparatus of Example 58, wherein the information of maintaining the pathloss estimates associated with the M candidate cells includes a set of M candidate cells listed in a sequential order of candidate cells for maintaining the pathloss estimates.

[0206] Example 60. The apparatus of Example 59, wherein the apparatus is further caused to perform: selecting the N RSs associated with the at least one candidate cell, wherein the at least one candidate cell is selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; andwherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the selected N RSs of the selected at least one candidate cell.

[0207] Example 61. The apparatus of Example 59, wherein the apparatus is further caused to perform: selecting N candidate cells, wherein the N candidate cells are selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for RSs of the selected N candidate cells.

[0208] Example 62. The apparatus of Example 59, wherein the apparatus is further caused to perform: selecting the N RSs associated with the at least one candidate cell, based on at least one of a best received signal strength or a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; wherein the best received signal strength is determined based on at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the N RSs; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the N RSs; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the N RSs with the best received signal strength.

[0209] Example 63. The apparatus of Example 58, wherein the information of maintaining the pathloss estimates includes at least one of: instructions indicating criteria for selecting the N RSs associated with the at least one candidate cell for which the pathloss estimates to be maintained; information of the N RSs for which the pathloss estimates to be maintained; instructions indicating criteria for selecting N candidate cells for which the pathloss estimates to be maintained; or information of the N candidate cells for which the pathloss estimates to be maintained.

[0210] Example 64. The apparatus of Example 63, wherein the criteria for selecting the N candidate cells includes at least one of: selecting N most recent candidate cells for which a timing advance (TA) acquisition procedure was performed by the apparatus; or selecting N most recent candidate cells for which a condition for an event triggered measurement reporting is fulfilled; or selecting N most recent candidate cells for which a TCI activation was performed; or selecting N candidate cells with a strongest received reference signal (RS); and the criteria for selecting the N RSs includes selecting the N RSs with a strongest received reference signal (RS); and wherein the strongest received RS is determined based on a measurement of at least one of: a layer 1 or layer 3 reference signal received power(RSRP) of the RS; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the RS.

[0211] Example 65. The apparatus of Example 63, wherein: the information of the N RSs includes identifiers of the N RSs; and the information of the N candidate cells includes identifiers of the N candidate cells.

[0212] Example 66. The apparatus of Example 58, wherein the apparatus is further caused to perform receiving an update of the information of maintaining the pathloss estimates associated with the M candidate cells, wherein the update is received via at least one of: a medium access control (MAC) control element (MAC-CE) command; a downlink control information (DCI); or lower layer or layer 1 message in an abstract syntax notation one (ASN.l) format.

[0213] Example 67. The apparatus of Example 66, wherein the apparatus is further caused to perform determining by the apparatus to maintain the pathloss estimates for the N reference signals (RSs) associated with at least one of the updated M candidate cells or the at least one candidate cell of the updated M candidate cells.

[0214] Example 68. The apparatus of Example 58, wherein the apparatus starts maintaining the pathloss estimates based on at least one of: receiving a configuration information of measurement reporting of a candidate cell; or receiving an activation of the configuration information of the measurement reporting.

[0215] Example 69. The apparatus of Example 68, wherein the configuration information of the measurement reporting includes indication of at least one of: an identifier of the candidate cell; periodic measurement reporting; or aperiodic measurement reporting.

[0216] Example 70. The apparatus of Example 58, wherein the information of maintaining the pathloss estimates associated with the M candidate cells is received via at least one of: a radio resource control (RRC) message; a medium access control (MAC) control element (MAC-CE) command; a downlink control information (DCI); or a lower layer or layer 1 message in an abstract syntax notation one (ASN. l) format.

[0217] Example 71. The apparatus of Example 57, wherein the apparatus maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0218] Example 72. The apparatus of Example 71, wherein the apparatus is further caused to perform stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0219] Example 73. The apparatus of Example 57, wherein the cell switch command is associated with one of the N RSs, and the apparatus is further caused to perform performing by the apparatus a cell switch to a candidate cell associated with one of the N RSs for which the cell switch command was received.

[0220] Example 74. A method including: receiving, by a user device from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; receiving, by the user device from the network node, information of maintaining pathloss estimates associated with M candidate cells; determining by the user device, N reference signals (RSs) associated with at least one candidate cell of the M candidate cells; maintaining the pathloss estimates for the N RSs; and receiving a cell switch command for a candidate cell.

[0221] Example 75. The method of Example 74, wherein N is less than or equal to M, and the user device is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

[0222] Example 76. The method of Example 75, wherein the information of maintaining the pathloss estimates associated with the M candidate cells includes a set of M candidate cells listed in a sequential order of candidate cells for maintaining the pathloss estimates.

[0223] Example 77. The method of Example 76, further including: selecting the N RSs associated with the at least one candidate cell, wherein the at least one candidate cell is selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the selected N RSs of the selected at least one candidate cell.

[0224] Example 78. The method of Example 76, further including: selecting N candidate cells, wherein the N candidate cells are selected based on a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for RSs of the selected N candidate cells.

[0225] Example 79. The method of Example 76, further including: selecting the N RSs associated with the at least one candidate cell, based on at least one of a best received signal strength or a priority according to the sequential order of the M candidate cells for maintaining the pathloss estimates; wherein the best received signal strength is determined based on at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the N RSs; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the N RSs; and wherein the maintaining the pathloss estimates includes maintaining the pathloss estimates for the N RSs with the best received signal strength.

[0226] Example 80. The method of Example 75, wherein the information of maintaining the pathloss estimates includes at least one of: instructions indicating criteria for selecting the N RSs associated with the at least one candidate cell for which the pathloss estimates to be maintained; information of the N RSs for which the pathloss estimates to be maintained; instructions indicating criteria for selecting N candidate cells for which the pathloss estimates to be maintained; or information of the N candidate cells for which the pathloss estimates to be maintained.

[0227] Example 81. The method of Example 80, wherein the criteria for selecting the N candidate cells includes at least one of: selecting N most recent candidate cells for which a timing advance (TA) acquisition procedure was performed by the user device; or selecting N most recent candidate cells for which a condition for an event triggered measurement reporting is fulfilled; or selecting N most recent candidate cells for which a TCI activation was performed; or selecting N candidate cells with a strongest received reference signal (RS); and the criteria for selecting the N RSs includes selecting the N RSs with a strongest received reference signal (RS); and wherein the strongest received RS is determined based on a measurement of at least one of: a layer 1 or layer 3 reference signal received power (RSRP) of the RS; or a layer 1 or layer 3 signal to interference plus noise ratio (SINR) of the RS.

[0228] Example 82. The method of Example 80, wherein: the information of the N RSs includes identifiers of the N RSs; and the information of the N candidate cells includes identifiers of the N candidate cells.

[0229] Example 83. The method of Example 75, further including receiving an update of the information of maintaining the pathloss estimates associated with the M candidate cells, wherein the update is received via at least one of: a medium access control (MAC)control element (MAC-CE) command; a downlink control information (DCI); or lower layer or layer 1 message in an abstract syntax notation one (ASN. l) format.

[0230] Example 84. The method of Example 83, further including determining by the user device to maintain the pathloss estimates for the N reference signals (RSs) associated with at least one of the updated M candidate cells or the at least one candidate cell of the updated M candidate cells.

[0231] Example 85. The method of Example 75, wherein the user device starts maintaining the pathloss estimates based on at least one of: receiving a configuration information of measurement reporting of a candidate cell; or receiving an activation of the configuration information of the measurement reporting.

[0232] Example 86. The method of Example 85, wherein the configuration information of the measurement reporting includes indication of at least one of: an identifier of the candidate cell; periodic measurement reporting; or aperiodic measurement reporting.

[0233] Example 87. The method of Example 75, wherein the information of maintaining the pathloss estimates associated with the M candidate cells is received via at least one of: a radio resource control (RRC) message; a medium access control (MAC) control element (MAC-CE) command; a downlink control information (DCI); or a lower layer or layer 1 message in an abstract syntax notation one (ASN. l) format.

[0234] Example 88. The method of Example 74, wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0235] Example 89. The method of Example 88, further including stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0236] Example 90. The method of Example 74, wherein the cell switch command is associated with one of the N RSs, and the method further including performing by the user device a cell switch to a candidate cell associated with one of the N RSs for which the cell switch command was received.

[0237] Example 91. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus, information of M candidate cells;determining by the apparatus to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received; maintaining the pathloss estimates for the N RSs of the at least one candidate cell; transmitting, to a serving cell of a network node, information of the N RSs of the at least one candidate cell for which the apparatus maintained the pathloss estimates; and receiving, from the serving cell of the network node, a cell switch command for a candidate cell.

[0238] Example 92. The apparatus of Example 91, wherein N is less than or equal to M, and the apparatus is capable of maintaining N pathloss estimates associated with the M candidate cells.

[0239] Example 93. The apparatus of Example 92, wherein the information of the M candidate cells includes at least one of: information of layer 1 / layer 2 triggered mobility (LTM) configuration of the M candidate cells; transmission configuration indicator (TCI) state activation for the M candidate cells; or information to perform timing advance (TA) acquisition with the M candidate cells.

[0240] Example 94. The apparatus of Example 92, wherein the information of the N RSs associated with the at least one candidate cell for which the apparatus maintained the pathloss estimates includes at least one of: identifiers of the N RSs; or identifiers of the at least one candidate cell associated with the N RSs.

[0241] Example 95. The apparatus of Example 94, wherein the information of the N RSs of the at least one candidate cell includes measurement information of signal strength of the N RSs for which the pathloss estimates were maintained, wherein the measurement information includes at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0242] Example 96. The apparatus of Example 95, wherein the information of the N RSs of the at least one candidate cell includes a single bit flag indication for each of the N RSs indicating whether a pathloss estimate is maintained for each of the N RSs.

[0243] Example 97. The apparatus of Example 96, wherein: the single bit flag indication being 1 indicates that the pathloss estimate for a corresponding RS is maintained; and the single bit flag indication being 0 indicates that the pathloss estimate for the corresponding RS is not maintained.

[0244] Example 98. The apparatus of Example 91, wherein the information of the N RSs of the at least one candidate cell is transmitted via at least one of: a radio resource control (RRC) message; an uplink medium access control (MAC) control element (UL MAC-CE) command; or a lower layer or layer 1 message in an abstract syntax notation one (ASN.l) format.

[0245] Example 99. The apparatus of Example 91, wherein the cell switch command is associated with the candidate cell associated with one of the N RSs, and the apparatus is further caused to perform performing by the apparatus a cell switch to the candidate cell associated with one of the N RSs for which the cell switch command was received.

[0246] Example 100. The apparatus of Example 91, wherein the apparatus maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0247] Example 101. The apparatus of Example 100, further including stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0248] Example 102. A method including: receiving, by a user device, information of M candidate cells; determining by the user device to maintain pathloss estimates for N reference signals (RSs) associated with at least one candidate cell of the M candidate cells for which the information was received; maintaining the pathloss estimates for the N RSs of the at least one candidate cell; transmitting, by the user device to a serving cell of a network node, information of the N RSs of the at least one candidate cell for which the user device maintained the pathloss estimates; and receiving, by the user device from the serving cell of the network node, a cell switch command for a candidate cell.

[0249] Example 103. The method of Example 102, wherein N is less than or equal to M, and the user device is capable of maintaining N pathloss estimates associated with the M candidate cells.

[0250] Example 104. The method of Example 103, wherein the information of the M candidate cells includes at least one of: information of layer 1 / layer 2 triggered mobility (LTM) configuration of the M candidate cells; transmission configuration indicator (TCI)state activation for the M candidate cells; or information to perform timing advance (TA) acquisition with the M candidate cells.

[0251] Example 105. The method of Example 103, wherein the information of the N RSs associated with the at least one candidate cell for which the user device maintained the pathloss estimates includes at least one of: identifiers of the N RSs; or identifiers of the at least one candidate cell associated with the N RSs.

[0252] Example 106. The method of Example 105, wherein the information of the N RSs of the at least one candidate cell includes measurement information of signal strength of the N RSs for which the pathloss estimates were maintained, wherein the measurement information includes at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

[0253] Example 107. The method of Example 106, wherein the information of the N RSs of the at least one candidate cell includes a single bit flag indication for each of the N RSs indicating whether a pathloss estimate is maintained for each of the N RSs.

[0254] Example 108. The method of Example 107, wherein: the single bit flag indication being 1 indicates that the pathloss estimate for a corresponding RS is maintained; and the single bit flag indication being 0 indicates that the pathloss estimate for the corresponding RS is not maintained.

[0255] Example 109. The method of Example 102, wherein the information of the N RSs of the at least one candidate cell is transmitted via at least one of: a radio resource control (RRC) message; an uplink medium access control (MAC) control element (UL MAC-CE) command; or a lower layer or layer 1 message in an abstract syntax notation one (ASN.l) format.

[0256] Example 110. The method of Example 102, wherein the cell switch command is associated with the candidate cell associated with one of the N RSs, and the method further including performing by the user device a cell switch to the candidate cell associated with one of the N RSs for which the cell switch command was received.

[0257] Example 111. The method of Example 102, wherein the user device maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

[0258] Example 112. The method of Example 111, further including stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

[0259] FIG. 8 is a block diagram of a wireless station or node (e.g., UE, user device, AP, BS, eNB, gNB, RAN node, network node, TRP, or other node) 1300 according to an example embodiment. The wireless station 1300 may include, for example, one or more (e.g., two as shown in FIG. 8) RF (radio frequency) or wireless transceivers 1302 A, 1302B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit / entity (controller) 1304 to execute instructions or software and control transmission and receptions of signals, and a memory 1306 to store data and / or instructions.

[0260] Processor 1304 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 1304, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 1302 (1302A or 1302B). Processor 1304 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down- converted by wireless transceiver 1302, for example). Processor 1304 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above. Processor 1304 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and / or any combination of these. Using other terminology, processor 1304 and transceiver 1302 together may be considered as a wireless transmitter / receiver system, for example.

[0261] In addition, referring to FIG. 8, a controller (or processor) 1308 may execute software and instructions, and may provide overall control for the station 1300, and may provide control for other systems not shown in FIG. 8, such as controlling input / output devices (e.g., display, keypad), and / or may execute software for one or more applications that may be provided on wireless station 1300, such as, for example, an email program,audio / video applications, a word processor, a Voice over IP application, or other application or software.

[0262] In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 1304, or other controller or processor, performing one or more of the functions or tasks described above.

[0263] According to another example embodiment, RF or wireless transceiver(s) 1302A / 1302B may receive signals or data and / or transmit or send signals or data. Processor 1304 (and possibly transceivers 1302A / 1302B) may control the RF or wireless transceiver 1302 A or 1302B to receive, send, broadcast or transmit signals or data.

[0264] Example embodiments are provided or described for each of the example methods, including: An apparatus (e.g., 1300, FIG. 8) including means (e.g., processor 1304, RF transceivers 1302A and / or 1302B, and / or memory 1306, in FIG. 8) for carrying out any of the methods; a non-transitory computer-readable storage medium (e.g., memory 1306, FIG. 8) comprising instructions stored thereon that, when executed by at least one processor (processor 1304, FIG. 8), are configured to cause a computing system (e.g., 1300, FIG. 8) to perform any of the example methods; and an apparatus (e.g., 1300, FIG. 8) including at least one processor (e.g., processor 1304, FIG. 8), and at least one memory (e.g., memory 1306, FIG. 8) including computer program code, the at least one memory (1306) and the computer program code configured to, with the at least one processor (1304), cause the apparatus (e.g., 1300) at least to perform any of the example methods.

[0265] Embodiments of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Embodiments may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine- readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Embodiments may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Embodiments of the various techniques may also include embodiments provided via transitory signals or media, and / or programs and / or software embodiments that are downloadable via the Internet or other network(s), either wired networks and / or wirelessnetworks. In addition, embodiments may be provided via machine type communications (MTC), and also via an Internet of Things (IOT).

[0266] As used in this application, the term ‘circuitry’ or “circuit” refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of circuits and soft-ware (and / or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s) / software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor s) or a portion of a microprocessor s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of ‘circuitry’ applies to all uses of this term in this application. As a further example, as used in this application, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

[0267] The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and / or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer, or it may be distributed amongst a number of computers.

[0268] Furthermore, embodiments of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the embodiment and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, ...) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyberphysical systems. Examples of mobile physical systems include mobile robotics andelectronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various embodiments of techniques described herein may be provided via one or more of these technologies.

[0269] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0270] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0271] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magnetooptical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0272] To provide for interaction with a user, embodiments may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display(LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0273] Embodiments may be implemented in a computing system that includes a backend component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a frontend component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an embodiment, or any combination of such backend, middleware, or frontend components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.

[0274] While certain features of the described embodiments have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the various embodiments.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: receiving, by the apparatus from a serving cell of a network node, information of layerl / layer2 triggered mobility (LTM) configuration for one or more candidate cells; performing, by the apparatus, a timing advance (TA) acquisition procedure with at least one candidate cell of the one or more candidate cells; determining to maintain pathloss estimates for N reference signals (RSs) associated with the at least one candidate cell for which the TA acquisition procedure was performed; maintaining the pathloss estimates for the N RSs associated with the at least one candidate cell for which the TA acquisition procedure was performed; and receiving from the serving cell of the network node, a cell switch command for a candidate cell.

2. The apparatus of claim 1, wherein the apparatus is capable of maintaining N pathloss estimates associated with configured one or more candidate cells.

3. The apparatus of claim 2, wherein the performing the TA acquisition procedure comprises: receiving from the network node, a network triggered physical downlink control channel (PDCCH) ordered physical random access channel (PRACH) procedure indicating a request to perform the PRACH procedure with a candidate cell of the at least one candidate cell using a RS; and transmitting, by the apparatus to the candidate cell, a random access request message.

634. The apparatus of claim 2, wherein the apparatus is further caused to perform: receiving, by the apparatus from the network node, a radio resource control (RRC) message indicating a candidate cell for which the apparatus can perform apparatus based TA acquisition procedure; performing measurements to estimate a received downlink timing difference between the serving cell and the candidate cell; and estimating the TA for the candidate cell using the received downlink timing difference between the serving cell and the candidate cell and the TA of the serving cell.

5. The apparatus of claim 2, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell comprises selecting N most recent RSs for which the TA acquisition procedure was performed.

6. The apparatus of claim 2, wherein the apparatus is further caused to perform stopping maintaining of the pathloss estimates for RSs for which the TA acquisition procedure was performed before the TA acquisition procedure of the N RSs was performed.

7. The apparatus of claim 2, wherein the determining to maintain the pathloss estimates for the N RSs associated with the at least one candidate cell comprises maintaining the pathloss estimates based on the N RSs with strongest received signal, wherein the strongest received signal is determined based on a measurement of at least one of: layer 1 reference signal received power (RSRP) of the RSs; or layer 1 signal to interference plus noise ratio (SINR) of the RSs.

8. The apparatus of claim 2, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates comprises maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, based on at least one of:a most recent measurement of strongest received RSs of the remaining set of RSs; or whether a condition for an event triggered measurement reporting is fulfilled for RSs of the remaining set of RSs; and wherein the strongest received RSs is determined based on at least one of: a layer 1 reference signal received power (RSRP); or a layer 3 RSRP.

9. The apparatus of claim 2, wherein the apparatus is further caused to perform: determining that a number of RSs for which the TA acquisition procedure was performed is less than N; and wherein the maintaining the pathloss estimates comprises maintaining the pathloss estimates for a remaining set of the RSs, other than the RSs for which the TA acquisition procedure is performed, for which a most recent transmission configuration indicator (TCI) state activation was received.

10. The apparatus of claim 2, wherein: the pathloss estimates are maintained for N RSs per candidate cell; or the pathloss estimates are maintained for the N RSs, wherein each RS is associated with one candidate cell.

11. The apparatus of claim 1, wherein the apparatus maintains up to N pathloss estimates, wherein the N pathloss estimates are for X RSs of the serving cell and Y RSs of the at least one candidate cell, wherein a total number of pathloss estimates X+Y does not exceed N.

12. The apparatus of claim 11, wherein the apparatus is further caused to perform stopping maintaining the pathloss estimates for one or more RSs of the serving cell such that the total number of pathloss estimates X+Y does not exceed N.

13. The apparatus of claim 1, wherein the cell switch command is associated with one of the N RSs, and the apparatus is further caused to perform performing by the apparatus a cell switch to the candidate cell for which the cell switch command was received.66

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