Reference measurement timing selection for wireless communication mobility

Aspects relate to selecting a physical cell identifier (PCI) that a user equipment (UE) uses to obtain a timing reference for a mobility measurement. A serving base station (BS) associated with multiple cells may select a set of these cells as candidate cells for a UE and send to the UE a set of candidate PCIs associated with those cells (e.g., one PCI for each cell). The BS may select a subset of the candidate cells to serve to the UE and indicate to the UE the corresponding subset of PCIs. The UE may select a PCI from the set of candidate PCIs (or from the subset of PCIs) to use for obtaining a timing reference for a synchronization signal block (SSB) measurement. The UE may select a PCI based on a defined rule. The UE may select a PCI based on signaling from the BS.

TECHNICAL FIELD

The technology discussed below relates generally to wireless communication and, more particularly, to selecting reference measurement timing for a mobility operation.

INTRODUCTION

Next-generation wireless communication systems (e.g., 5GS) may include a 5G core network and a 5G radio access network (RAN), such as a New Radio (NR)-RAN. The NR-RAN supports communication via one or more cells. For example, a wireless communication device such as a user equipment (UE) may access a first cell of a first base station (BS) such as a gNB and/or access a second cell of a second BS.

A network may support mobility operations that enable a UE to communicate with one or more a nearby cells. For example, as a UE moves across a service area of the network, handovers may take place such that the UE initially communicates with at least one cell and then communicates with at least one other cell.

BRIEF SUMMARY OF SOME EXAMPLES

In some examples, the disclosure provides a method for wireless communication at a user equipment. The method may include receiving, from a base station, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment, selecting a first PCI from the set of candidate PCIs, determining a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI, and conducting the SSB measurement using the timing reference.

In some examples, the disclosure provides a user equipment that includes a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory. The processor and the memory may be configured to receive, from a base station via the transceiver, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment, select a first PCI from the set of candidate PCIs, determine a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI, and conduct the SSB measurement using the timing reference.

In some examples, the disclosure provides a user equipment. The user equipment may include means for receiving, from a base station, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment, means for selecting a first PCI from the set of candidate PCIs, means for determining a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI, and means for conducting the SSB measurement using the timing reference.

In some examples, the disclosure provides an article of manufacture for use by a user equipment. The article of manufacture may include a non-transitory computer-readable medium having stored therein instructions executable by one or more processors of the user equipment to receive, from a base station, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment, select a first PCI from the set of candidate PCIs, determine a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI, and conduct the SSB measurement using the timing reference.

In some examples, the disclosure provides a method for wireless communication at a base station. The method may include transmitting a physical cell identifier (PCI) selection indication to a user equipment. The PCI selection indication may specify a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement. The method may also include receiving a measurement report from the user equipment after transmitting the PCI selection indication, and conducting a mobility operation for the user equipment based on the measurement report.

In some examples, the disclosure provides a base station that includes a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory. The processor and the memory may be configured to transmit a physical cell identifier (PCI) selection indication to a user equipment via the transceiver. The PCI selection indication may specify a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement. The processor and the memory may also be configured to receive a measurement report from the user equipment via the transceiver after transmitting the PCI selection indication, and conduct a mobility operation for the user equipment based on the measurement report.

In some examples, the disclosure provides a base station. The base station may include means for transmitting a physical cell identifier (PCI) selection indication to a user equipment. The PCI selection indication may specify a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement. The base station may also include means for receiving a measurement report from the user equipment after transmitting the PCI selection indication, and means for conducting a mobility operation for the user equipment based on the measurement report.

In some examples, the disclosure provides an article of manufacture for use by a base station. The article of manufacture may include a non-transitory computer-readable medium having stored therein instructions executable by one or more processors of the base station to transmit a physical cell identifier (PCI) selection indication to a user equipment. The PCI selection indication may specify a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement. The computer-readable medium may also have stored therein instructions executable by one or more processors of the base station to receive a measurement report from the user equipment after transmitting the PCI selection indication, and to conduct a mobility operation for the user equipment based on the measurement report.

These and other aspects of the disclosure will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and examples of the present disclosure will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, example aspects of the present disclosure in conjunction with the accompanying figures. While features of the present disclosure may be discussed relative to certain examples and figures below, all examples of the present disclosure can include one or more of the advantageous features discussed herein. In other words, while one or more examples may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various examples of the disclosure discussed herein. In similar fashion, while example aspects may be discussed below as device, system, or method examples it should be understood that such example aspects can be implemented in various devices, systems, and methods.

DETAILED DESCRIPTION

Various aspects of the disclosure relate to determining timing to be used for a reference measurement for a mobility operation. In some networks, a UE may concurrently connect to several cells and/or several transmission and reception points (TRPs). For example, a base station may be configured to serve several cells or may be configured with several remotely deployed TRPs (e.g., each of which includes a radio head and at least one antenna) to extend the coverage of the base station. Each cell or transmission and reception point (TRP) may use a unique (e.g., locally unique) physical cell identifier (PCI).

The base station may configure the UE with a set of candidate PCIs (e.g., the PCIs of nearby cells and/or TRPs that are candidates for serving the UE). In addition, the base station may select a subset of the candidate PCIs and send an indication of this subset to the UE. For example, based on signal measurements made by the UE and reported to the base station, the base station may determine that a particular (e.g., a specific) subset of cells and/or TRPs are best suited for serving the UE at this time. This selection may be based on different criteria in different scenarios. As one example, the base station may select the number of PCIs to be included in the subset based on current traffic requirements for the UE. As another example, the base station may select the PCIs to include in the subset based on the received signal strengths measured by the UE (e.g., the PCIs of the cells and/or TRPs associated with the four highest received signal strengths may be included in the subset).

The disclosure relates in some aspects to selecting a PCI of a set of candidate PCIs that the UE will use to determine a timing reference for a mobility measurement. For example, the UE may select a PCI from the subset of PCIs identified by the base station and measure a downlink signal based on this PCI. The UE may then determine a timing reference from the measured downlink signal and use the timing reference for a synchronization signal block (SSB) measurement. In some examples, the UE may select the PCI based on a defined rule. In some examples, the UE may select the PCI based on signaling from the serving base station.

As illustrated, the RAN104includes a plurality of base stations108. Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. In different technologies, standards, or contexts, a base station may variously be referred to by those skilled in the art as a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B (NB), an eNode B (eNB), a gNode B (gNB), a transmission and reception point (TRP), or some other suitable terminology. In some examples, a base station may include two or more TRPs that may be collocated or non-collocated. Each TRP may communicate on the same or different carrier frequency within the same or different frequency band. In examples where the RAN104operates according to both the LTE and 5G NR standards, one of the base stations108may be an LTE base station, while another base station may be a 5G NR base station.

The radio access network104is further illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus may be referred to as user equipment (UE)106in 3GPP standards, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE106may be an apparatus that provides a user with access to network services. In examples where the RAN104operates according to both the LTE and 5G NR standards, the UE106may be an Evolved-Universal Terrestrial Radio Access Network—New Radio dual connectivity (EN-DC) UE that is capable of simultaneously connecting to an LTE base station and a NR base station to receive data packets from both the LTE base station and the NR base station.

Within the present document, a mobile apparatus need not necessarily have a capability to move, and may be stationary. The term mobile apparatus or mobile device broadly refers to a diverse array of devices and technologies. UEs may include a number of hardware structural components sized, shaped, and arranged to help in communication; such components can include antennas, antenna arrays, RF chains, amplifiers, one or more processors, etc. electrically coupled to each other. For example, some non-limiting examples of a mobile apparatus include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC), a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA), and a broad array of embedded systems, e.g., corresponding to an Internet of Things (IoT).

A mobile apparatus may additionally be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotics device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and/or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player), a camera, a game console, etc. A mobile apparatus may additionally be a digital home or smart home device such as a home audio, video, and/or multimedia device, an appliance, a vending machine, intelligent lighting, a home security system, a smart meter, etc. A mobile apparatus may additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling electric power (e.g., a smart grid), lighting, water, etc., an industrial automation and enterprise device, a logistics controller, agricultural equipment, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, i.e., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be given preferential treatment or prioritized access over other types of information, e.g., in terms of prioritized access for transport of critical service data, and/or relevant QoS for transport of critical service data.

Wireless communication between a RAN104and a UE106may be described as utilizing an air interface. Transmissions over the air interface from a base station (e.g., base station108) to one or more UEs (e.g., UE106) may be referred to as downlink (DL) transmission. In some examples, the term downlink may refer to a point-to-multipoint transmission originating at a base station (e.g., base station108). Another way to describe this point-to-multipoint transmission scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE106) to a base station (e.g., base station108) may be referred to as uplink (UL) transmissions. In some examples, the term uplink may refer to a point-to-point transmission originating at a UE (e.g., UE106).

In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station108) allocates resources for communication among some or all devices and equipment within its service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities (e.g., UEs). That is, for scheduled communication, a plurality of UEs106, which may be scheduled entities, may utilize resources allocated by the scheduling entity108.

Base stations108are not the only entities that may function as scheduling entities. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs). For example, UEs may communicate with other UEs in a peer-to-peer or device-to-device fashion and/or in a relay configuration.

As illustrated inFIG.1, a scheduling entity108may broadcast downlink traffic112to one or more scheduled entities106. Broadly, the scheduling entity108is a node or device responsible for scheduling traffic in a wireless communication network, including the downlink traffic112and, in some examples, uplink traffic116and/or uplink control information118from one or more scheduled entities106to the scheduling entity108. On the other hand, the scheduled entity106is a node or device that receives downlink control information114, including but not limited to scheduling information (e.g., a grant), synchronization or timing information, or other control information from another entity in the wireless communication network such as the scheduling entity108.

In addition, the uplink and/or downlink control information and/or traffic information may be time-divided into frames, subframes, slots, and/or symbols. As used herein, a symbol may refer to a unit of time that, in an orthogonal frequency division multiplexed (OFDM) waveform, carries one resource element (RE) per sub-carrier. A slot may carry 7 or 14 OFDM symbols in some examples. A subframe may refer to a duration of 1 millisecond (ms). Multiple subframes or slots may be grouped together to form a single frame or radio frame. Within the present disclosure, a frame may refer to a predetermined duration (e.g., 10 ms) for wireless transmissions, with each frame consisting of, for example, 10 subframes of 1 ms each. Of course, these definitions are not required, and any suitable scheme for organizing waveforms may be utilized, and various time divisions of the waveform may have any suitable duration.

Referring now toFIG.2, by way of example and without limitation, a schematic illustration of a RAN200is provided. In some examples, the RAN200may be the same as the RAN104described above and illustrated inFIG.1.

FIG.2further includes an unmanned aerial vehicle (UAV)220, which may be a drone or quadcopter. The UAV220may be configured to function as a base station, or more specifically as a mobile base station. That is, in some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station, such as the UAV220.

Within the RAN200, the cells may include UEs that may be in communication with one or more sectors of each cell. Further, each base station210,212,214, and218may be configured to provide an access point to a core network102(seeFIG.1) for all the UEs in the respective cells. For example, UEs222and224may be in communication with base station210; UEs226and228may be in communication with base station212; UEs230and232may be in communication with base station214by way of RRH216; and UE234may be in communication with base station218. In some examples, the UEs222,224,226,228,230,232,234,236,238,240, and/or242may be the same as the UE/scheduled entity106described above and illustrated inFIG.1. In some examples, the UAV220(e.g., the quadcopter) can be a mobile network node and may be configured to function as a UE. For example, the UAV220may operate within cell202by communicating with base station210.

In a further aspect of the RAN200, sidelink signals may be used between UEs without necessarily relying on scheduling or control information from a base station. Sidelink communication may be utilized, for example, in a device-to-device (D2D) network, peer-to-peer (P2P) network, vehicle-to-vehicle (V2V) network, vehicle-to-everything (V2X) network, and/or other suitable sidelink network. For example, two or more UEs (e.g., UEs238,240, and242) may communicate with each other using sidelink signals237without relaying that communication through a base station. In some examples, the UEs238,240, and242may each function as a scheduling entity or transmitting sidelink device and/or a scheduled entity or a receiving sidelink device to schedule resources and communicate sidelink signals237therebetween without relying on scheduling or control information from a base station. In other examples, two or more UEs (e.g., UEs226and228) within the coverage area of a base station (e.g., base station212) may also communicate sidelink signals227over a direct link (sidelink) without conveying that communication through the base station212. In this example, the base station212may allocate resources to the UEs226and228for the sidelink communication.

In the radio access network200, the ability for a UE to communicate while moving, independent of its location, is referred to as mobility. The various physical channels between the UE and the radio access network are generally set up, maintained, and released under the control of an access and mobility management function (AMF, not illustrated, part of the core network102inFIG.1), which may include a security context management function (SCMF) that manages the security context for both the control plane and the user plane functionality, and a security anchor function (SEAF) that performs authentication.

A set of continuous or discontinuous resource blocks may be referred to herein as a Resource Block Group (RBG), sub-band, or bandwidth part (BWP). A set of sub-bands or BWPs may span the entire bandwidth. Scheduling of scheduled entities (e.g., UEs) for downlink, uplink, or sidelink transmissions typically involves scheduling one or more resource elements306within one or more sub-bands or bandwidth parts (BWPs). Thus, a UE generally utilizes only a subset of the resource grid304. In some examples, an RB may be the smallest unit of resources that can be allocated to a UE. Thus, the more RBs scheduled for a UE, and the higher the modulation scheme chosen for the air interface, the higher the data rate for the UE. The RBs may be scheduled by a scheduling entity, such as a base station (e.g., gNB, eNB, etc.), or may be self-scheduled by a UE implementing D2D sidelink communication.

In this illustration, the RB308is shown as occupying less than the entire bandwidth of the subframe302, with some subcarriers illustrated above and below the RB308. In a given implementation, the subframe302may have a bandwidth corresponding to any number of one or more RBs308. Further, in this illustration, the RB308is shown as occupying less than the entire duration of the subframe302, although this is merely one possible example.

Although not illustrated inFIG.3, the various REs306within an RB308may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs306within the RB308may also carry pilots or reference signals. These pilots or reference signals may provide for a receiving device to perform channel estimation of the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within the RB308.

In some examples, the slot310may be utilized for broadcast, multicast, groupcast, or unicast communication. For example, a broadcast, multicast, or groupcast communication may refer to a point-to-multipoint transmission by one device (e.g., a base station, UE, or other similar device) to other devices. Here, a broadcast communication is delivered to all devices, whereas a multicast or groupcast communication is delivered to multiple intended recipient devices. A unicast communication may refer to a point-to-point transmission by a one device to a single other device.

The PBCH in the SSB may further include a master information block (MIB) that includes various system information, along with parameters for decoding a system information block (SIB). The SIB may be, for example, a SystemInformationType 1 (SIB1) that may include various additional (remaining) system information. The MIB and SIB1 together provide the minimum system information (SI) for initial access. Examples of system information transmitted in the MIB may include, but are not limited to, a subcarrier spacing (e.g., default downlink numerology), system frame number, a configuration of a PDCCH control resource set (CORESET) (e.g., PDCCH CORESET0), a cell barred indicator, a cell reselection indicator, a raster offset, and a search space for SIB1. Examples of remaining minimum system information (RMSI) transmitted in the SIB1 may include, but are not limited to, a random access search space, a paging search space, downlink configuration information, and uplink configuration information. A base station may transmit other system information (OSI) as well.

As the SI may change over time, the scheduling entity may send paging messages that indicate a change in the SI. Accordingly, a UE may periodically monitor a paging channel for these and other paging messages. If a paging message indicates that the SI has changed, the UE monitors a broadcast channel or some other designated channel for the new SI.

In an UL transmission, the scheduled entity (e.g., UE) may utilize one or more REs306to carry UL control information (UCI) including one or more UL control channels, such as a physical uplink control channel (PUCCH), to the scheduling entity. UCI may include a variety of packet types and categories, including pilots, reference signals, and information configured to enable or assist in decoding uplink data transmissions. Examples of uplink reference signals may include a sounding reference signal (SRS) and an uplink DMRS. In some examples, the UCI may include a scheduling request (SR), i.e., request for the scheduling entity to schedule uplink transmissions. Here, in response to the SR transmitted on the UCI, the scheduling entity may transmit downlink control information (DCI) that may schedule resources for uplink packet transmissions. UCI may also include HARQ feedback, channel state feedback (CSF), such as a CSI report, or any other suitable UCI.

In addition to control information, one or more REs306(e.g., within the data region314) may be allocated for data traffic. Such data traffic may be carried on one or more traffic channels, such as, for a DL transmission, a physical downlink shared channel (PDSCH); or for an UL transmission, a physical uplink shared channel (PUSCH). In some examples, one or more REs306within the data region314may be configured to carry other signals, such as one or more SIBs and DMRSs.

In an example of sidelink communication over a sidelink carrier via a proximity service (ProSe) PC5 interface, the control region312of the slot310may include a physical sidelink control channel (PSCCH) including sidelink control information (SCI) transmitted by an initiating (transmitting) sidelink device (e.g., Tx V2X device or other Tx UE) towards a set of one or more other receiving sidelink devices (e.g., an Rx V2X device or some other Rx UE). The data region314of the slot310may include a physical sidelink shared channel (PSSCH) including sidelink data traffic transmitted by the initiating (transmitting) sidelink device within resources reserved over the sidelink carrier by the transmitting sidelink device via the SCI. Other information may further be transmitted over various REs306within slot310. For example, HARQ feedback information may be transmitted in a physical sidelink feedback channel (PSFCH) within the slot310from the receiving sidelink device to the transmitting sidelink device. In addition, one or more reference signals, such as a sidelink SSB, a sidelink CSI-RS, a sidelink SRS, and/or a sidelink positioning reference signal (PRS) may be transmitted within the slot310.

The channels or carriers described above with reference toFIGS.1-3are not necessarily all of the channels or carriers that may be utilized between a scheduling entity and scheduled entities, and those of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels.

FIG.4Aillustrates an example400of various downlink channels within a subframe of a frame including channels used for initial access and synchronization. As shown inFIG.4A, a physical downlink control channel (PDCCH)402is transmitted in at least two symbols (e.g., symbol 0 and symbol 1) and may carry DCI within at least one control channel element (CCE), with each CCE including nine RE groups, and each RE group (REG) including four consecutive REs in an OFDM symbol. Additionally,FIG.4Aillustrates an exemplary synchronization signal block (SSB)404that may be periodically transmitted by a base station or gNB. The SSB404carries synchronization signals PSS406and SSS408and broadcast channels (PBCH)410. In this example, the SSB404contains one PSS symbol (shown in symbol 2), one SSS symbol (shown in symbol 4) and two PBCH symbols (shown in symbols 3 and 5). The PSS and SSS combination may be used to identify physical cell identities. A UE uses the PSS to determine subframe/symbol timing and a physical layer identity. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Also, based on the PCI, the UE can determine the locations of the aforementioned DMRS. The physical broadcast channel (PBCH), which carries a master information block (MIB), is logically grouped with the PSS and SSS to form the synchronization signal; i.e., the SSB404. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN).

FIG.4Bis a diagram illustrating various broadcast information450related to initial cell access according to some examples. The broadcast information450may be transmitted by a RAN node (e.g., a base station, such as an eNB or gNB) on resources (e.g., time-frequency resources) allocated for the transmission of the broadcast information450in a cell. The broadcast information450includes the SSB404illustrated inFIG.4A. It is noted that the PBCH in SSB404includes the MIB carrying various system information (SI) including, for example, a cell barred indication, the subcarrier spacing, the system frame number, and scheduling information for a CORESET0452. For example, the PBCH in the SSB404may include scheduling information indicating time-frequency resources allocated for a CORESET0452. In some examples, the CORESET 0452may be transmitted within the first four symbols (e.g., within a control region) of a slot. In addition, the CORESET0452carries a PDCCH with DCI that contains scheduling information for scheduling a SIB1454. The SIB1454is carried within a physical downlink shared channel (PDSCH) within a data region of a slot. In addition, the SIB1454may be referred to as RMSI and includes, for example, a set of radio resource parameters providing network identification and configuration. For example, the set of radio resource parameters may include a bandwidth (e.g., number of BWPs) on which a UE may communicate with a base station.

The MIB in the PBCH may include system information (SI), along with parameters for decoding a SIB (e.g., SIB1). Examples of SI transmitted in the MIB may include, but are not limited to, a subcarrier spacing, system frame number, a configuration of a PDCCH control resource set (CORESET) (e.g., PDCCH CORESET0), and a search space for SIB1. Examples of SI transmitted in the SIB1 may include, but are not limited to, a random access search space, downlink configuration information, and uplink configuration information. The MIB and SIB1 together provide the minimum SI for initial access.

A brief summary of an example of an initial access procedure for a UE using the above information follows. As discussed above, a BS may transmit synchronization signals (e.g., including PSS and SSS) in the network to enable UEs to synchronize with the BS, as well as SI to facilitate initial network access. A UE attempting to access a RAN may perform an initial cell search by detecting a PSS from a BS (e.g., the PSS of a cell of the BS) of the RAN. As discussed above, the PSS may enable the UE to synchronize to period timing of the BS and may indicate a physical layer identity value assigned to the cell. The UE may also receive an SSS from the BS that enables the UE to synchronize on the radio frame level with the cell. The SSS may also provide a cell identity value, which the UE may combine with the physical layer identity value to determine a PCI of the cell.

Wireless communication networks such as NR networks may support carrier aggregation in a multi-cell transmission environment where, for example, different base stations and/or different transmission and reception points (TRPs) may transmit on different component carriers. In some aspects, the term component carrier may refer to a carrier frequency (or band) utilized for communication within a cell. In some examples, different TRPs may be associated with a single serving cell (e.g., a single base station). In some examples, different TRPs may be associated with different serving cells (e.g., different base stations may employ different TRPs).

An example of a multi-cell transmission environment500is shown inFIG.5. The multi-cell transmission environment500includes a primary serving cell (PCell)502and one or more secondary serving cells (SCells)506a,506b,506c, and506d. The PCell502may be referred to as the anchor cell that provides a radio resource control (RRC) connection to a UE (e.g., the UE510). In some examples, the PCell and one or more of the SCells may be co-located. For example, a TRP for the PCell and a TRP for an SCell may be installed at the same location.

When carrier aggregation is used in the multi-cell transmission environment500, one or more of the SCells506a-506dmay be activated or added to the PCell502to form the serving cells serving the UE510. In this case, each of these serving cells corresponds to a component carrier (CC). The CC of the PCell502may be referred to as a primary CC, and the CC of an SCell (e.g., SCell506a-506d) may be referred to as a secondary CC. Each of the PCell502and the SCells506a-506dmay be served by a respective base station or scheduling entity as described inFIGS.1and2. In the example ofFIG.5, the PCell502is served by the base station504and the SCells506a-506care each served by a respective base station508a-508c. In addition, the SCell506dis co-located with the PCell502. For example, the base station504may include multiple TRPs, each supporting a different carrier. The coverage of the PCell502and the coverage of the SCell506dmay differ as shown inFIG.5. For example, component carriers in different frequency bands may experience different path loss and, thus, provide different coverage.

In some examples, the PCell502may utilize a first radio access technology (RAT), such as LTE, while one or more of the SCells506may utilize a second RAT, such as NR. In this case, the multi-cell transmission environment may be referred to as a multi-RAT-dual connectivity (MR-DC) environment. In some examples, the PCell502may be a low band cell, and the SCells506may be high band cells. A low band (LB) cell uses a CC in a frequency band lower than that of the high band cells. For example, the high band cells may use a mmWave CC, and the low band cell may use a CC in a band (e.g., sub-6 GHz band) that is lower than mmWave. In general, a cell using a mmWave CC can provide greater bandwidth than a cell using a low band CC. In addition, when using above-6 GHz frequency (e.g., mmWave) carriers, beamforming may be used to transmit and receive signals.

In some scenarios, the base station504may add/remove one or more of the SCells506a-506dto/from a set of CCs. For example, as the UE510moves or as channel conditions or data requirements change over time, the UE510may be better served by a different SCell. Thus, the base station504may elect to use a different SCell for the set of CCs to, for example, improve the reliability of a connection to the UE510and/or increase the data rate for such a connection.

In addition, the UE510may be handed over from the PCell502to another PCell. For example, as the UE510moves or as channel conditions or data requirements change over time, the UE510may be better served by a different PCell (e.g., a PCell that is served by a different base station).

To enable a UE to be handed off between cells (inter-cell mobility), a base station may collect measurement reports from its served UEs. These measurement reports may be based on UE measurements of the signal quality (e.g., signal strength) of signals received from nearby cells. Based on these signal quality measurements, base station may identify the best candidate cells for the UE.

For some types of mobility measurements, the UE may use a timing reference (e.g., of a cell) to measure a signal from a cell. For example, in NR, a protocol Layer 3 (hereafter simply referred to as L3) mobility measurement may be based on an SSB measurement timing configuration (SMTC). In some examples, the SMTC may specify a time window, along with SSB positions and slots within the time window, that a UE can use to measure the SSB of a neighbor cell for mobility purposes.

In some examples, the SMTC may be based on a timing reference of a cell. For example, in NR, the following timing references may be used for a change in a primary cell (PCell), a change in a primary secondary cell (PSCell), or the addition of a secondary cell (SCell). For an NR PCell change, the SMTC may be based on the timing reference of a source PCell. For an NR PSCell change, the SMTC may be based on the timing reference of a source PSCell. For an NR SCell addition, the SMTC may be based on the timing of a SpCell of an associated cell group. An SpCell refers to either a PCell (e.g., a Pcell of an MCG) or a PSCell (e.g., of an SCG).

In some examples, inter-cell mobility in NR involves operations at different protocol layers. Protocol Layer 1 inter-cell mobility may be referred to herein as L1 inter-cell mobility. Protocol Layer 2 inter-cell mobility may be referred to herein as L2 inter-cell mobility. L1 and L2 inter-cell mobility may involve two different modes of operation in some examples.

In a first mode of operation (mode1), a serving cell is configured with multiple TRPs. These TRPs may be at different locations. In addition, different TRPs may have different PCIs. For a given TRP, the corresponding PCI may be carried by the SSB transmitted by the TRP as discussed above.

FIG.6illustrates an example of a wireless communication system600where a UE602is served by a set of TRPs (TRP604a, TRP604b, TRP604c, and TRP604d) of a BS606associated with a serving cell. In some scenarios, other cells (not shown) may be in the vicinity of the UE602. In some examples, the UE602may correspond to any of the UEs or scheduled entities shown in any ofFIGS.1,5,7,8,9, and10. In some examples, each of the TRP604a, TRP604b, TRP604c, and TRP604dmay be TRPs of any of the BSs or scheduling entities shown in any ofFIGS.1,5,7,8,9, and13.

Each of the TRP604a, the TRP604b, the TRP604c, and the TRP604dmay use a unique (e.g., locally unique) PCI. For example, the TRP604amay use a first PCI, the TRP604bmay use a second PCI, the TRP604cmay use a third PCI, and the TRP604dmay use a fourth PCI. These PCIs enable the UE602to uniquely identify each corresponding TRP. In some examples, the cells served by the TRPs may be referred to as sub-cells of a serving cell (e.g., a serving cell of the BS606).

At a given point in time, a UE may be served by a subset of the serving cell's total number of sub-cells (e.g., the cells of the TRPs that have been selected to serve the UE). In addition, the serving cell may change this subset from time to time.

For example, inFIG.6, the BS606that is serving the UE602may have selected the four TRPs (TRP604a, TRP604b, TRP604c, and TRP604d) in the vicinity of the UE602as candidate sub-cells for the UE602. In addition, the BS606may have configured the UE602to be served by two of the TRPs (TRP604band TRP604c) as represented by a dashed line608aand a dashed line608b. Thus, in this case, the UE602may be served by a first sub-cell associated with the TRP604band a second sub-cell associated with the TRP604c.

In some examples, a decision by a serving cell to change the serving subset for a UE may be based on measurements made by the UE. For example, the UE may be configured to measure L1 metrics (e.g., for each serving TRP, for each candidate TRP, or for some other group of TRPs). The metrics may include, for example, one or more of reference signal received power (RSRP), signal-to-interference-plus-noise ratio (SINR), or reference signal received quality (RSRQ).

Upon determining that a change in the subset is warranted (e.g., if there has been a non-trivial change in the measured metrics with respect to one or more of the TRPs), the serving cell may send an indication of the change (e.g., identifying any PCIs that have been added or removed from the subset) to the UE. In some examples, the serving cell (e.g., a gNB) may send this indication via downlink control information (DCI), via a media access control-control element (MAC-CE), via a radio resource control (RRC) message, via some other type of signaling technique, or via a combination of two or more of these signaling techniques.

In the example ofFIG.6, the BS606will send to the UE602an indication of the PCIs of the TRPs of the subset. For example, the BS606may send to the UE602an indication of the PCI of the TRP604band the PCI of the TRP604c.

In a second mode of operation (mode2), a UE is configured (e.g., by a primary serving cell) with a group of serving cells (e.g., a candidate set of cells). Here, different serving cells have different PCIs (e.g., there is a single PCI per serving cell). For a given serving cell, this PCI may be carried by the SSB transmitted by the serving cell.

FIG.7illustrates an example of a wireless communication system700where a UEs702is served by a set of serving cells represented by BS704a, BS704b, BS704c, BS704d, and BS704e. In some scenarios, other cells (not shown) may be in the vicinity of the UEs702. In some examples, the UE702may correspond to any of the UEs or scheduled entities shown in any ofFIGS.1,5,6,8,9, and10. In some examples, each of the BS704a, BS704b, BS704c, BS704d, and BS704emay correspond to any of the BSs or scheduling entities shown in any ofFIGS.1,5,6,8,9, and13.

Each of the BS704a, the BS704b, the BS704c, the BS704d, and the BS704emay use a unique (e.g., locally unique) PCI. For example, the BS704amay use a first PCI, the BS704bmay use a second PCI, the BS704cmay use a third PCI, the BS704dmay use a fourth PCI, and the BS704emay use a fifth PCI. These PCIs enable a UE to uniquely identify each corresponding cell.

At a given point in time, a UE may be served by a subset of the group of serving cells. This subset may change from time to time. For example, one of the serving cells (e.g., a primary serving cell such as a gNB) may select the subset based on L1 reports (e.g., L1 RSRP, SINR, RSRQ) from a UE. The UE may send these reports to a selected set of serving cells or to an anchor serving cell in the group of serving cells in some examples. Upon determining that a change in the subset is warranted (e.g., if there has been a non-trivial change in the measured metrics with respect to one or more measured cells), the primary serving cell may send an indication of the change (e.g., identifying a PCI that have been added or removed from the subset) to the UE as discussed above.

For example, inFIG.7, the BS704a(e.g., a primary cell or an anchor cell) that is serving the UE702may have selected the five BSs (BS704a, BS704b, BS704c, BS704d, and BS704e) in the vicinity of the UE702as candidate cells for the UE702. In addition, the BS704amay have configured the UE702to be served by three of the BSs (BS704a, BS704b, BS704c) as represented by a dashed line706a, a dashed line706b, and a dashed line706c. The BS704awill therefore send to the UE702an indication of the PCIs of the cells of the subset. For example, the BS704amay send to the UE702an indication of the PCI of the BS704a, the PCI of the BS704b, and the PCI of the BS704c.

Thus, in the scenarios ofFIG.6andFIG.7, each of the BS606and the BS704amay perform mobility operations in an attempt to ensure that served UEs are being served by the best cells. For example, over time, the BS606and the BS704amay change the set of selected candidate cells/TRPs and/or serving cells/TRPs for a particular UE. Such a change may be triggered by, for example, movement of a UE, a change in channel conditions, a change in data throughput requirements, or some other type of operational change.

The disclosure relates in come aspects to mobility operations in a multi-cell environment. For example, a UE that is served by multiple cells, where each cell has its own unique PCI, may select one of these PCIs to use for a timing reference for a mobility measurement.

In some examples, a UE may conduct L3 mobility measurements in a scenario where the UE is served by multiple cells and/or TRPs. In this case, the timing reference used for the L3 mobility measurement may be selected from a set of cells and/or TRPs that are in the neighborhood of the UE. This set of cells and/or TRPs may be referred to herein as a candidate set of cells/TRPs. In addition, the PCIs associated with the candidate set of cells/TRPs may be referred to herein as a set of candidate PCIs. Two examples of selecting the timing reference used for the L3 mobility measurement follow.

In the first example, a timing reference for an L3 mobility measurement (e.g., for an SSB measurement timing configuration (SMTC)) in L1 and/or L2 mobility may be based on the timing reference of one PCI in a subset of PCI(s) that have been selected for serving a UE. In some examples, the subset of PCI(s) is a subset of a set of candidate PCIs for the UE. If there is only one PCI in the subset, the timing reference for the SMTC may be based on the downlink receive timing for this PCI.

If there are multiple PCIs in the subset, the timing reference may be based on one of the PCIs in the subset. Two options for determining which PCI of the subset to use follow. Other techniques for determining which PCI of the subset to use may be used in other examples.

In a first option, the UE determines the PCI to use based on a rule. This rule may take different forms in different implementations.

In some examples, the rule may be a predefined rule (e.g., an implicit rule). In some examples, the rule may be specified by a communication standard such as a 3GPP Technical Specification. In some examples, the rule may be programmed into the wireless communication during initial deployment in a network.

In some examples, the rule may be a defined rule (e.g., a rule that a UE receives from a base station). In some examples, the rule may specify that the UE uses the PCI having the lowest PCI value in the subset of PCIs selected for serving the UE. In some examples, the rule may specify that the UE uses the PCI having the highest PCI value in the subset of PCIs selected for serving the UE. Other rules may be used in other examples.

In a second option, the UE determines the PCI to use based on explicit signaling. For example, a base station (e.g., a gNB) may send to the UE an indication of the PCI that the UE is to use to determine the timing reference. The base station may send this indication via downlink control information (DCI), via a media access control-control element (MAC-CE), via a radio resource control (RRC), via some other type of signaling technique, or via a combination of two or more of these signaling techniques.

FIG.8is a signaling diagram800illustrating an example of signaling for the first example in a wireless communication system including a UE802and a base station (BS)804that serves several cells and/or TRPs (e.g., cell/TRP806through cell/TRP808). As discussed herein, each of the cell/TRPs may be associated with a unique PCI. In some examples, the UE802may correspond to any of the UEs or scheduled entities shown in any ofFIGS.1,2,5,6,7,9, and10. In some examples, the BS804may correspond to any of the base stations or scheduling entities shown in any ofFIGS.1,2,5,6,7,9, and13.

At810ofFIG.8, the BS804selects a set of candidate PCIs for the UE802. For example, based on measurement reports received from the UE802, the BS804may identify a set of cells or TRPs in the vicinity of the UE802. At812, the BS804may transmit an indication of the set of candidate PCIs to the UE802.

At814, the BS804selects a subset of the set of candidate PCIs to serve the UE802. For example, based on measurement reports received from the UE802, the BS804may identify a subset of the candidate PCIs that would best serve the UE802at this point in time. At816, the BS804may transmit an indication of the subset of PCIs to the UE802.

At optional818, the BS804may select a timing reference to be used by the UE802for SSB measurements. For example, the BS804may determine that the UE802should use the anchor cell of the UE802as the timing reference. At820, the BS804may transmit an indication of the selected timing reference (e.g., the PCI of the anchor cell) to the UE802.

At822, if there is only one PCI in the subset, the UE802may select that PCI for determining the timing reference to be used by the UE802for SSB measurements. Alternatively, at824, if there are multiple PCIs in the subset, the UE802may use a rule (e.g., highest/lowest PCI value) or received signaling (e.g., the PCI signaled at820) to select the PCI from the subset.

At826, the UE802determines the timing of a received downlink (DL) signal828associated with the selected PCI. At830, the UE802measures the SSBs832transmitted by one or more cells/TRPs (e.g., from the candidate set of cells/TRPs associated with the set of candidate PCIs) using the timing determined at826as the timing reference for the SMTC.

At834and836, the UE802and the BS804conduct mobility operations. For example, the UE802may generate a measurement report based on the SSB measurements at830and send the measurement report to the BS804. Based on this measurement report, the BS804may elect to change one or more of: the candidate set of cells/TRPs for the UE802, the subset of serving cells/TRPs for the UE802, the anchor cell for the UE802, or perform some other mobility operation (e.g., handover).

In the second example referred to above, the timing reference used for the Layer 3 mobility measurement may be selected from the set of PCIs (e.g., candidate PCIs) that are assigned to the UE. For example, the timing reference may be selected based on the timing reference of one PCI in the set of candidate PCIs, regardless of which PCIs have (or which PCI has) been selected as a serving PCI. If there is one PCI in the PCI set (e.g., an anchor PCI), this PCI is selected. In some examples, the anchor PCI may be dedicated for broadcast, control, and/or measurement report signaling. In some examples, primary data traffic may be served by other PCIs a subset of PCIs selected to serve the UE.

If there are multiple PCIs in the PCI set, the timing reference may be based on one of PCIs in the PCI set. Two options for determining which PCI of the PCI set to use follow. Other techniques for determining which PCI of the PCI set to use may be employed in other examples.

In a first option, the UE determines the PCI to use based on a rule. This rule may take different forms in different implementations.

In some examples, the rule may be a predefined rule (e.g., an implicit rule). In some examples, the rule may be specified by a communication standard such as a 3GPP Technical Specification. In some examples, the rule may be programmed into the wireless communication during initial deployment in a network.

In some examples, the rule may be a defined rule (e.g., a rule that a UE receives from a base station). In some examples, the rule may specify that the UE uses the PCI having the lowest PCI value in the subset of PCIs selected for serving the UE. In some examples, the rule may specify that the UE uses the PCI having the highest PCI value in the subset of PCIs selected for serving the UE. Other rules may be used in other examples.

In a second option, the UE determines the PCI to use based on explicit signaling. For example, a base station (e.g., a gNB) may send to the UE an indication of the PCI that the UE is to use to determine the timing reference. The base station may send this indication via downlink control information (DCI), via a media access control-control element (MAC-CE), via a radio resource control (RRC), via some other type of signaling technique, or via a combination of two or more of these signaling techniques.

FIG.9is a signaling diagram900illustrating an example of signaling for the first example in a wireless communication system including a UE902and a base station (BS)904that serves several cells and/or TRPs (e.g., cell/TRP906through cell/TRP908). As discussed herein, each of the cell/TRPs may be associated with a unique PCI. In some examples, the UE902may correspond to any of the UEs or scheduled entities shown in any ofFIGS.1,2,5,6,7,8, and10. In some examples, the BS904may correspond to any of the base stations or scheduling entities shown in any ofFIGS.1,2,5,6,7,8, and13.

At910ofFIG.9, the BS904selects a set of candidate PCIs for the UE902. For example, based on measurement reports received from the UE902, the BS904may identify a set of cells or TRPs in the vicinity of the UE902. At912, the BS904may transmit an indication of the set of candidate PCIs to the UE902.

At914, the BS904selects a subset of the set of candidate PCIs to serve the UE902. For example, based on measurement reports received from the UE902, the BS904may identify a subset of the candidate PCIs that would best serve the UE902at this point in time. At916, the BS904may transmit an indication of the subset of PCIs to the UE902.

At optional918, the BS904may select a timing reference to be used by the UE902for SSB measurements. For example, the BS904may determine that the UE902should use the anchor cell of the UE902as the timing reference. At920, the BS904may transmit an indication of the selected timing reference (e.g., the PCI of the anchor cell) to the UE902.

At922, the UE902selects a particular PCI (e.g., a specific PCI) from the set of candidate PCIs for determining the timing reference to be used by the UE902for SSB measurements. For example, the UE902may select the PCI associated with the anchor cell for the UE902. Alternatively, at924, the UE902may use a rule (e.g., highest/lowest PCI value) or received signaling (e.g., the PCI signaled at920) to select the PCI from the set of candidate PCIs.

At926, the UE902determines the timing of a received downlink (DL) signal928associated with the selected PCI. At930, the UE902measures the SSBs932transmitted by one or more cells/TRPs (e.g., from the candidate set of cells/TRPs) using the timing determined at926as the timing reference for the SMTC.

At934and936, the UE902and the BS904conduct mobility operations. For example, the UE902may generate a measurement report based on the SSB measurements at930and send the measurement report to the BS904. Based on this measurement report, the BS904may elect to change one or more of: the candidate set of cells/TRPs for the UE902, the subset of serving cells/TRPs for the UE902, the anchor cell for the UE902, or perform some other mobility operation (e.g., handover).

FIG.10is a block diagram illustrating an example of a hardware implementation for a UE1000employing a processing system1014. For example, the UE1000may be a device configured to wirelessly communicate with a base station, as discussed in any one or more ofFIGS.1-9. In some implementations, the UE1000may correspond to any of the UEs or scheduled entities shown in any ofFIGS.1,2,5,6,7,8, and9.

In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with the processing system1014. The processing system1014may include one or more processors1004. Examples of processors1004include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. In various examples, the UE1000may be configured to perform any one or more of the functions described herein. That is, the processor1004, as utilized in a UE1000, may be used to implement any one or more of the processes and procedures described herein.

The processor1004may in some instances be implemented via a baseband or modem chip and in other implementations, the processor1004may include a number of devices distinct and different from a baseband or modem chip (e.g., in such scenarios as may work in concert to achieve the examples discussed herein). And as mentioned above, various hardware arrangements and components outside of a baseband modem processor can be used in implementations, including RF-chains, power amplifiers, modulators, buffers, interleavers, adders/summers, etc.

In this example, the processing system1014may be implemented with a bus architecture, represented generally by the bus1002. The bus1002may include any number of interconnecting buses and bridges depending on the specific application of the processing system1014and the overall design constraints. The bus1002communicatively couples together various circuits including one or more processors (represented generally by the processor1004), a memory1005, and computer-readable media (represented generally by the computer-readable medium1006). The bus1002may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface1008provides an interface between the bus1002and a transceiver1010and between the bus1002and an interface1030. The transceiver1010provides a communication interface or means for communicating with various other apparatus over a wireless transmission medium. The interface1030provides a communication interface or means of communicating with various other apparatuses and devices (e.g., other devices housed within the same apparatus as the UE or other external apparatuses) over an internal bus or external transmission medium, such as an Ethernet cable. Depending upon the nature of the apparatus, the interface1030may include a user interface (e.g., keypad, display, speaker, microphone, joystick). Of course, such a user interface is optional, and may be omitted in some examples, such as an IoT device.

The processor1004is responsible for managing the bus1002and general processing, including the execution of software stored on the computer-readable medium1006. The software, when executed by the processor1004, causes the processing system1014to perform the various functions described below for any particular apparatus. The computer-readable medium1006and the memory1005may also be used for storing data that is manipulated by the processor1004when executing software. For example, the memory1005may store PCI information1015used by the processor1004for the PCI-related operations described herein.

The UE1000may be configured to perform any one or more of the operations described herein (e.g., as described above in conjunction withFIGS.1-9and as described below in conjunction withFIGS.11-12). In some aspects of the disclosure, the processor1004, as utilized in the UE1000, may include circuitry configured for various functions.

The processor1004may include communication and processing circuitry1041. The communication and processing circuitry1041may be configured to communicate with a base station, such as a gNB. The communication and processing circuitry1041may include one or more hardware components that provide the physical structure that performs various processes related to wireless communication (e.g., signal reception and/or signal transmission) as described herein. The communication and processing circuitry1041may further include one or more hardware components that provide the physical structure that performs various processes related to signal processing (e.g., processing a received signal and/or processing a signal for transmission) as described herein. In some examples, the communication and processing circuitry1041may include two or more transmit/receive chains. The communication and processing circuitry1041may further be configured to execute communication and processing software1051included on the computer-readable medium1006to implement one or more functions described herein.

In some implementations where the communication involves receiving information, the communication and processing circuitry1041may obtain information from a component of the UE1000(e.g., from the transceiver1010that receives the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium), process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry1041may output the information to another component of the processor1004, to the memory1005, or to the bus interface1008. In some examples, the communication and processing circuitry1041may receive one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry1041may receive information via one or more channels. In some examples, the communication and processing circuitry1041may include functionality for a means for receiving. In some examples, the communication and processing circuitry1041may include functionality for a means for decoding.

In some implementations where the communication involves sending (e.g., transmitting) information, the communication and processing circuitry1041may obtain information (e.g., from another component of the processor1004, the memory1005, or the bus interface1008), process (e.g., encode) the information, and output the processed information. For example, the communication and processing circuitry1041may output the information to the transceiver1010(e.g., that transmits the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium). In some examples, the communication and processing circuitry1041may send one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry1041may send information via one or more channels. In some examples, the communication and processing circuitry1041may include functionality for a means for sending (e.g., a means for transmitting). In some examples, the communication and processing circuitry1041may include functionality for a means for encoding.

The processor1004may include PCI selection circuitry1042configured to perform PCI selection-related operations as discussed herein (e.g., as described above in conjunction withFIGS.8and9). The PCI selection circuitry1042may include functionality for a means for receiving an indication of a set of candidate PCIs (e.g., functionality as described at812and/or816ofFIG.8, and/or at912and/or916ofFIG.9, and/or at block1102ofFIG.11). The PCI selection circuitry1042may include functionality for a means for selecting a PCI (e.g., functionality as described at822and/or824ofFIG.8, and/or at922and/or924ofFIG.9, and/or at block1104ofFIG.11). The PCI selection circuitry1042may further be configured to execute PCI selection software1052included on the computer-readable medium1006to implement one or more functions described herein.

The processor1004may include mobility circuitry1043configured to perform mobility-related operations as discussed herein (e.g., as described above in conjunction withFIGS.8and9). The mobility circuitry1043may include functionality for a means for determining a timing reference (e.g., functionality as described at826ofFIG.8, and/or at926ofFIG.9, and/or at block1106ofFIG.11). The mobility circuitry1043may include functionality for a means for conducting an SSB measurement (e.g., functionality as described at830ofFIG.8, and/or at930ofFIG.9, and/or at block1108ofFIG.11). The mobility circuitry1043may include functionality for a means for generating a measurement report (e.g., functionality as described at834ofFIG.8, and/or at934ofFIG.9, and/or at block1110ofFIG.11). The mobility circuitry1043may include functionality for a means for transmitting a measurement report (e.g., functionality as described at834ofFIG.8, and/or at934ofFIG.9, and/or at block1112ofFIG.11). The mobility circuitry1043may further be configured to execute mobility software1053included on the computer-readable medium1006to implement one or more functions described herein.

FIG.11is a flow chart illustrating an example wireless communication method1100according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the disclosure, and some illustrated features may not be required for implementation of all examples. In some examples, the method1100may be carried out by any of the UEs or scheduled entities shown in any ofFIGS.1,2,5,6,7,8,9, and10. In some examples, the method1100may be carried out by the processing system1014ofFIG.10. In some examples, the method1100may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block1102, a UE may receive, from a base station, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment. For example, the communication and processing circuitry1041and the transceiver1010, shown and described above in connection withFIG.10, may receive a message from a base station that identifies the PCIs of the cells and/or TRPs that have been identified as candidates to serve the UE.

In some examples, a subset of the set of candidate PCIs may include at least one PCI selected for serving the UE. In some examples, the subset only includes the first PCI.

In some examples, a first transmit receive point of a first serving cell for the user equipment may be identified by a second PCI of the set of candidate PCIs and second transmit receive point of the first serving cell may be identified by a third PCI of the set of candidate PCIs. In some examples, a first serving cell for the UE may be identified by a second PCI of the set of candidate PCIs and a second serving cell for the UE may be identified by a third PCI of the set of candidate PCIs.

In some examples, the set of candidate PCIs may include a plurality of PCIs of at least one serving cell for the UE. In some examples, the first PCI may include an anchor PCI for the UE. In some examples, the anchor PCI may be associated with at least one of broadcast traffic, control traffic, measurement report traffic, or any combination thereof. In some examples, one or more PCI of the plurality of candidate PCIs may be associated with data traffic.

In some examples, the set of candidate PCIs may be associated with a plurality of transmit receive points (TRPs) of a serving cell for the UE. In some examples, the serving cell may include a primary cell, a secondary cell, or a primary secondary cell.

In some examples, the set of candidate PCIs may be associated with a plurality of serving cells for the UE. In some examples, the serving cells may include at least one of a primary cell, a secondary cell, or a primary secondary cell.

At block1104, the UE may select a first PCI from the set of candidate PCIs. For example, the PCI selection circuitry1042, shown and described above in connection withFIG.10, may select one of PCIs of the set of candidate PCIs or one of the PCIs of a subset of the set of candidate PCIs. In some examples, if a subset of the set of candidate PCIs specified for the UE only includes one PCI, the PCI selection circuitry1042may select that PCI. As another example, if the subset includes multiple PCIs, the PCI selection circuitry1042may select one of those PCIs (e.g., based on an implicit rule or based on explicit signaling from the base station).

At block1106, the UE may determine a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI. For example, the mobility circuitry1043together with the communication and processing circuitry1041and the transceiver1010, shown and described above in connection withFIG.10, may measure downlink receive timing associated with the first PCI. In addition, the mobility circuitry1043may elect to use the measured downlink receive timing as a timing reference for an SMTC.

At block1108, the UE may conduct the SSB measurement using the timing reference. For example, the mobility circuitry1043together with the communication and processing circuitry1041and the transceiver1010may use an SMTC based on the timing reference determined at block1106to measure L1 metrics from SSB transmissions by neighboring cells/TRPs as discussed herein.

In some examples, the SSB measurement uses an SSB measurement timing configuration (SMTC) that may be based on the timing reference. In some examples, the SSB measurement may include a Protocol Layer 3 measurement.

At optional block1110, the UE may generate a measurement report based on the SSB measurement. For example, the mobility circuitry1043may generate a report that identifies the measured PCIs and their associated L1 metrics.

At optional block1112, the UE may transmit the measurement report to the base station. For example, the mobility circuitry1043together with the communication and processing circuitry1041and the transceiver1010may transmit the measurement report to a serving cell (e.g., the serving cell if there is only one serving cell, or a primary serving cell if there are multiple serving cells).

In some examples, the process may further include receiving, from the base station, a second indication of a subset of the set of candidate PCIs. In some examples, wherein the selecting the first PCI from the set of candidate PCIs may include selecting the first PCI from the subset. In some examples, the subset only includes the first PCI.

In some examples, the process may further include receiving, from the base station, a physical cell identifier (PCI) selection indication, wherein selecting the first PCI from the set of candidate PCIs may include using the PCI selection indication to select the first PCI. In some examples, the PCI selection indication specifies that the UE is to use a predefined rule to select the first PCI. In some examples, the process may further include receiving, from the base station, a second indication of a subset of the set of candidate PCIs. In some examples, the method may further include using the predefined rule to select the first PCI from the subset. In some examples, the set of candidate PCIs may include a plurality of PCIs of at least one serving cell for the UE and the method may further include using the predefined rule to select the timing reference from the plurality of candidate PCIs. In some examples, the predefined rule specifies that the UE is to select a PCI associated with a lowest PCI value. In some examples, the predefined rule specifies that the UE is to select a PCI associated with a highest PCI value. In some examples, the PCI selection indication specifies that the UE is use to a particular PCI (e.g., a specific PCI) identified by the base station.

In some examples, the process may further include receiving an indication of the particular PCI from the base station. In some examples, receiving the indication of the particular PCI may include receiving the indication of the particular PCI via downlink control information (DCI), a medium access control-control element (MAC-CE), or a radio resource control (RRC) message.

FIG.12is a flow chart illustrating an example wireless communication method1200according to some aspects. In some examples, the method1200may be implemented in conjunction with (e.g., in addition to or as part of) the method1100ofFIG.11. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the disclosure, and some illustrated features may not be required for implementation of all examples. In some examples, the method1200may be carried out by any of the UEs or scheduled entities shown in any ofFIGS.1,2,5,6,7,8,9, and10. In some examples, the method1200may be carried out by the processing system1014ofFIG.10. In some examples, the method1200may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block1202, a UE may receive a PCI selection indication from a base station. For example, the communication and processing circuitry1041and the transceiver1010, shown and described above in connection withFIG.10, may receive a DCI that includes the indication via a PDCCH or receive a MAC-CE or an RRC message that includes the indication via a PDSCH.

At block1204, the UE may use the PCI selection indication to select the first PCI. For example, if the PCI selection indication indicates that the UE is to use a rule for the PCI selection, the PCI selection circuitry1042, shown and described above in connection withFIG.10, may select that PCI based on the rule (e.g., select highest or lowest PCI value). As another example, if the PCI selection indication indicates that the UE is to use explicit signaling for the PCI selection, the PCI selection circuitry1042may select a PCI based on an indication of the PCI to use received from the base station.

FIG.13is a conceptual diagram illustrating an example of a hardware implementation for base station (BS)1300employing a processing system1314. In some implementations, the BS1300may correspond to any of the BSs (e.g., gNBs) or scheduling entities shown in any ofFIGS.1,2,5,6,7,8, and9.

In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with the processing system1314. The processing system may include one or more processors1304. The processing system1314may be substantially the same as the processing system1014illustrated inFIG.10, including a bus interface1308, a bus1302, memory1305, a processor1304, and a computer-readable medium1306. The memory1305may store PCI information1315(e.g., PCIs of candidate cells and/or a subset of the candidate cells) used by the processor1304in cooperation with the transceiver1310for mobility operations. Furthermore, the BS1300may include an interface1330(e.g., a network interface) that provides a means for communicating with at least one other apparatus within a core network and with at least one radio access network.

The BS1300may be configured to perform any one or more of the operations described herein (e.g., as described above in conjunction withFIGS.1-9and as described below in conjunction withFIGS.14-15). In some aspects of the disclosure, the processor1304, as utilized in the BS1300, may include circuitry configured for various functions.

The processor1304may be configured to generate, schedule, and modify a resource assignment or grant of time-frequency resources (e.g., a set of one or more resource elements). For example, the processor1304may schedule time-frequency resources within a plurality of time division duplex (TDD) and/or frequency division duplex (FDD) subframes, slots, and/or mini-slots to carry user data traffic and/or control information to and/or from multiple UEs. The processor1304may be configured to schedule resources for the transmission of downlink signals (e.g., SSBs). The processor1304may further be configured to schedule resources for the transmission of uplink signals.

In some aspects of the disclosure, the processor1304may include communication and processing circuitry1341. The communication and processing circuitry1344may be configured to communicate with a UE. The communication and processing circuitry1341may include one or more hardware components that provide the physical structure that performs various processes related to communication (e.g., signal reception and/or signal transmission) as described herein. The communication and processing circuitry1341may further include one or more hardware components that provide the physical structure that performs various processes related to signal processing (e.g., processing a received signal and/or processing a signal for transmission) as described herein. The communication and processing circuitry1341may further be configured to execute communication and processing software1351included on the computer-readable medium1306to implement one or more functions described herein.

The communication and processing circuitry1341may further be configured to transmit a message to the UE. For example, the message be included in a MAC-CE carried in a PUSCH, DCI in a PUCCH or PUSCH, a random access message, or an RRC message.

In some implementations wherein the communication involves receiving information, the communication and processing circuitry1341may obtain information from a component of the BS1300(e.g., from the transceiver1310that receives the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium), process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry1341may output the information to another component of the processor1304, to the memory1305, or to the bus interface1308. In some examples, the communication and processing circuitry1341may receive one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry1341may receive information via one or more channels. In some examples, the communication and processing circuitry1341may include functionality for a means for receiving. In some examples, the communication and processing circuitry1341may include functionality for a means for decoding.

In some implementations wherein the communication involves sending (e.g., transmitting) information, the communication and processing circuitry1341may obtain information (e.g., from another component of the processor1304, the memory1305, or the bus interface1308), process (e.g., encode) the information, and output the processed information. For example, the communication and processing circuitry1341may output the information to the transceiver1310(e.g., that transmits the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium). In some examples, the communication and processing circuitry1341may send one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry1341may send information via one or more channels. In some examples, the communication and processing circuitry1341may include functionality for a means for sending (e.g., a means for transmitting). In some examples, the communication and processing circuitry1341may include functionality for a means for encoding.

The processor1304may include PCI selection circuitry1342configured to perform PCI selection-related operations as discussed herein (e.g., as described above in conjunction withFIGS.8and9). The PCI selection circuitry1342may include functionality for a means for determining a selection procedure. In addition, the PCI selection circuitry1342may include functionality for a means for transmitting a PCI selection indication. For example, the PCI selection circuitry1342may determine whether the UE is to use an implicit rule to determine a timing reference for the SSB measurement or use explicit signaling from the BS to determine a timing reference for the SSB measurement. In addition, the PCI selection circuitry1342may generate for transmission information that indicates that the implicit rule or a particular PCI indicated by the explicit signaling is to be used by the UE. The PCI selection circuitry1342may further be configured to execute PCI selection software1352included on the computer-readable medium1306to implement one or more functions described herein.

The processor1304may include mobility circuitry1343configured to perform mobility-related operations as discussed herein (e.g., as described above in conjunction withFIGS.8and9). The mobility circuitry1343may include functionality for a means for receiving a measurement report. For example, the mobility circuitry1343, in cooperation with the communication and processing circuitry1341, may monitor for measurement report messages on uplink resources (e.g., PUSCH) scheduled for the UE for the transmission of such messages. The mobility circuitry1343may include functionality for a means for conducting a mobility operation. For example, the mobility circuitry1343may process measurement reports received from one or more UE over time and filter the information in the reports (e.g., calculate an average received power metric over a period of time). In addition, based on this information, the mobility circuitry1343may identify the cells/TRPs to be included in a candidate set of cells/TRPs for the UE and/or identify the cells/TRPs that are best suited for serving the UE (e.g., for a period of time until this decision is made again). The mobility circuitry1343may further be configured to execute mobility software1353included on the computer-readable medium1306to implement one or more functions described herein.

FIG.14is a flow chart illustrating an example wireless communication method1400according to some aspects. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the disclosure, and some illustrated features may not be required for implementation of all examples. In some examples, the method1400may be carried out by any of the BSs or scheduling entities shown in any ofFIGS.1,2,5,6,7,8,9, and13. In some examples, the method1400may be carried out by the processing system1314ofFIG.13. In some examples, the method1400may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block1402, a BS may transmit a physical cell identifier (PCI) selection indication to a user equipment, wherein the PCI selection indication specifies a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement. For example, the PCI selection circuitry1342, shown and described above in connection withFIG.13, may determine whether the UE is to use an implicit rule to determine a timing reference for the SSB measurement or use explicit signaling from the BS to determine a timing reference for the SSB measurement. In addition, the PCI selection circuitry1342together with the communication and processing circuitry1341and the transceiver1310, shown and described above in connection withFIG.13, may transmit or broadcast information that indicates that the implicit rule or a particular PCI indicated by the explicit signaling is to be used by the UE.

In some examples, the SSB measurement may be for a change of a primary cell, a change of a secondary cell, or a change of a primary secondary cell. In some examples, the SSB measurement may include a Protocol Layer 3 measurement. In some examples, the SSB measurement may be based on an SSB measurement timing configuration (SMTC).

In some examples, the PCI selection indication may specify that the UE is to use a predefined rule to select the timing reference. In some examples, the PCI selection indication may specify that the UE is to use a predefined rule to select the timing reference from a subset of a plurality of candidate PCIs for the UE. In some examples, the subset may include a plurality of selected PCIs for serving the UE. In some examples, the PCI selection indication may specify that the UE is to use a predefined rule to select the timing reference from a set of candidate PCIs of at least one serving cell for the UE. In some examples, the PCI selection indication may specify that the UE is to select a particular timing reference associated with a lowest PCI value. In some examples, the PCI selection indication may specify that the UE is to select a particular timing reference associated with a highest PCI value.

In some examples, the PCI selection indication may specify that the UE is use to a particular timing reference identified by the base station. In some examples, the process may further include selecting the particular timing reference and transmitting an indication of the particular timing reference to the UE. In some examples, selecting the particular timing reference may include selecting the particular timing reference from a subset of a set of candidate PCIs for the UE. In some examples, selecting the particular timing reference may include selecting the particular timing reference from a set of candidate PCIs of at least one serving cell for the UE. In some examples, transmitting the indication of the particular timing reference may include transmitting the indication of the particular timing reference via downlink control information (DCI), a medium access control-control element (MAC-CE), or a radio resource control (RRC) message.

At block1404, the BS may receive a measurement report from the UE after transmitting the PCI selection indication. For example, the mobility circuitry1343in cooperation with the communication and processing circuitry1341and the transceiver1310, shown and described above in connection withFIG.13, may receive a message including measurement report information from the UE. In some examples, the measurement report may be based on a particular timing reference selected by the UE according to the PCI selection indication.

At block1406, the BS may conduct a mobility operation for the UE based on the measurement report. For example, the mobility circuitry1343may determine, based on the measurement report, whether to change the PCIs in the set of candidate PCIs for the UE or change the PCIs in the subset of PCIs selected for serving the UE.

FIG.15is a flow chart illustrating an example wireless communication method1500according to some aspects. In some examples, the method1500may be implemented in conjunction with (e.g., in addition to or as part of) the method1400ofFIG.14. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the disclosure, and some illustrated features may not be required for implementation of all examples. In some examples, the method1500may be carried out by any of the BSs or scheduling entities shown in any ofFIGS.1,2,5,6,7,8,9, and13. In some examples, the method1500may be carried out by the processing system1314ofFIG.13. In some examples, the method1500may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block1502, a BS may select a timing reference. For example, the PCI selection circuitry1342, shown and described above in connection withFIG.13, may determine that the UE is to use a particular timing reference (e.g., timing of an anchor cell) for the SSB measurement.

At block1504, the BS may transmit an indication of the timing reference to the user equipment. For example, the PCI selection circuitry1342together with the communication and processing circuitry1341and the transceiver1310, shown and described above in connection withFIG.13, may transmit the indication in a DCI sent on a PDCCH or in a MAC-CE or RRC message sent on a PDSCH.

The following provides an overview of several aspects of the present disclosure.

Aspect 1: A method for wireless communication at a user equipment, the method comprising: receiving, from a base station, a first indication of a set of candidate physical cell identifiers (PCIs) for the user equipment; selecting a first PCI from the set of candidate PCIs; determining a timing reference for a synchronization signal block (SSB) measurement from downlink receive timing associated with the first PCI; and conducting the SSB measurement using the timing reference.

Aspect 2: The method of aspect 1, further comprising: receiving, from the base station, a second indication of a subset of the set of candidate PCIs, wherein the selecting the first PCI from the set of candidate PCIs comprises selecting the first PCI from the subset.

Aspect 3: The method of aspect 2, wherein the subset only includes the first PCI.

Aspect 4: The method of any of aspects 1 through 3, wherein a first transmit receive point of a first serving cell for the user equipment is identified by a second PCI of the set of candidate PCIs and second transmit receive point of the first serving cell is identified by a third PCI of the set of candidate PCIs.

Aspect 5: The method of any of aspects 1 through 4, wherein a first serving cell for the user equipment is identified by a second PCI of the set of candidate PCIs and a second serving cell for the user equipment is identified by a third PCI of the set of candidate PCIs.

Aspect 6: The method of any of aspects 1 through 5, wherein the set of candidate PCIs comprise a plurality of PCIs of at least one serving cell for the user equipment.

Aspect 7: The method of aspect 6, wherein: the first PCI comprises an anchor PCI for the user equipment; the anchor PCI is associated with at least one of broadcast traffic, control traffic, measurement report traffic, or any combination thereof; and at least one PCI of the plurality of PCIs is associated with data traffic.

Aspect 9: The method of any of aspects 1 through 7, further comprising: receiving a PCI selection indication from the base station; and using the PCI selection indication to select the first PCI.

Aspect 10: The method of aspect 9, wherein the PCI selection indication specifies that the user equipment is to use a predefined rule to select the first PCI.

Aspect 11: The method of aspect 10, further comprising: receiving, from the base station, a second indication of a subset of the set of candidate PCIs; and using the predefined rule to select the first PCI from the subset.

Aspect 12: The method of any of aspects 10 through 11, wherein: the set of candidate PCIs comprise a plurality of PCIs of at least one serving cell for the user equipment; and the method further comprises using the predefined rule to select the timing reference from the plurality of PCIs.

Aspect 13: The method of any of aspects 10 through 12, wherein the predefined rule specifies that the user equipment is to select a PCI associated with a lowest PCI value or a highest PCI value.

Aspect 14: The method of any of aspects 9 through 13, wherein the PCI selection indication specifies that the user equipment is use to a particular PCI identified by the base station.

Aspect 15: The method of aspect 14, further comprising: receiving an indication of the particular PCI from the base station.

Aspect 16: The method of any of aspects 1 through 7 and 9 through 15, wherein: the set of candidate PCIs is associated with a plurality of transmit receive points (TRPs) of a serving cell for the user equipment; or the set of candidate PCIs is associated with a plurality of serving cells for the user equipment.

Aspect 17: A method for wireless communication at a base station, the method comprising: transmitting a physical cell identifier (PCI) selection indication to a user equipment, wherein the PCI selection indication specifies a selection procedure for selecting a timing reference associated with a PCI for a synchronization signal block (SSB) measurement; receiving a measurement report from the user equipment after transmitting the PCI selection indication; and conducting a mobility operation for the user equipment based on the measurement report.

Aspect 18: The method of aspect 17, wherein the PCI selection indication specifies that the user equipment is to use a predefined rule to select the timing reference.

Aspect 19: The method of any of aspects 17 through 18, wherein the PCI selection indication specifies that the user equipment is to use a predefined rule to select the timing reference from a subset of a set of candidate PCIs for the user equipment.

Aspect 20: The method of aspect 19, wherein the subset comprises a plurality of selected PCIs for serving the user equipment.

Aspect 21: The method of any of aspects 17 through 20, wherein the PCI selection indication specifies that the user equipment is to use a predefined rule to select the timing reference from a set of candidate PCIs of at least one serving cell for the user equipment.

Aspect 22: The method of any of aspects 17 through 21, wherein the PCI selection indication specifies that the user equipment is to select a particular timing reference associated with a lowest PCI value.

Aspect 23: The method of any of aspects 1 through 22, wherein the PCI selection indication specifies that the user equipment is to select a particular timing reference associated with a highest PCI value.

Aspect 24: The method of any of aspects 17 through 23, wherein the PCI selection indication specifies that the user equipment is use to a particular timing reference identified by the base station.

Aspect 26: The method of any of aspects 17 through 24, wherein: the PCI selection indication specifies that the user equipment is use to a particular timing reference identified by the base station; and the method further comprises selecting the particular timing reference and transmit an indication of the particular timing reference to the user equipment.

Aspect 27: The method of aspect 26, further comprising: selecting the particular timing reference from a subset of a set of candidate PCIs for the user equipment.

Aspect 28: The method of any of aspects 26 through 27, further comprising: selecting the particular timing reference from a set of candidate PCIs of at least one serving cell for the user equipment.

Aspect 29: The method of any of aspects 26 through 28, further comprising: transmitting the indication of the particular timing reference via downlink control information (DCI), a medium access control-control element (MAC-CE), or a radio resource control (RRC) message.

Aspect 30: The method of any of aspects 17 through 24 and 26 through 29, wherein the measurement report is based on a particular timing reference selected by the user equipment according to the PCI selection indication.

Aspect 31: A user equipment comprising: a transceiver configured to communicate with a radio access network, a memory, and a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to perform any one of aspects 1 through 7 and 9 through 16.

Aspect 32: An apparatus configured for wireless communication comprising at least one means for performing any one of aspects 1 through 7 and 9 through 16.

Aspect 33: A non-transitory computer-readable medium storing computer-executable code, comprising code for causing an apparatus to perform any one of aspects 1 through 7 and 9 through 16.

Aspect 34: A base station comprising: a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to perform any one of aspects 17 through 24 and 26 through 30.

Aspect 35: An apparatus configured for wireless communication comprising at least one means for performing any one of aspects 17 through 24 and 26 through 30.

Aspect 36: A non-transitory computer-readable medium storing computer-executable code, comprising code for causing an apparatus to perform any one of aspects 17 through 24 and 26 through 30.

Several aspects of a wireless communication network have been presented with reference to an example implementation. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.