Patent Description:
In some examples, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In a Long Term Evolution (LTE) or LTE Advanced (LTE-A) network, a set of one or more base stations may define an eNodeB (eNB). In other examples (e.g., in a next generation or <NUM> network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., a new radio base station (NR BS), a new radio node-B (NR NB), a network node, <NUM> NB, gNB, gNodeB, etc.). A base station or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

<CIT> relates to methods, user equipment (UEs) and base stations for transmitting uplink signals. After receiving uplink synchronization command information, the UE may transmit an uplink signal on at least one idle unlicensed cell. Besides, the UE may try to transmit the uplink signal on multiple uplink signal resources within an uplink signal transmission window. By using the present disclosure, transmission probability of uplink signals may be improved, and time delay of uplink synchronization may be shortened. <CIT> relates to a discovery signal processing method. The method comprises: a base station configuring part of available resources of a designated reference signal as DS (Discovery Signal) resources; the base station sending a DS according to the configuration, and a terminal measuring the DS according to the configuration. Also disclosed in the embodiment of the present invention is a base station, which at least comprises: a configuration module configured to configure the DS resources and including taking part of available resources of the designated reference signal as the DS resources; and a sending module configured to send the DS according to the configuration. Also disclosed in the embodiment of the present invention is a computer storage medium in which a computer-executable command for executing the discovery signal processing method is stored.

The invention is defined in the appended independent claims. Further advantageous aspects are defined in the dependent claims.

NR may support various wireless communication services, such as Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM>), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra reliable low latency communications (URLLC).

mmW communications bring gigabit speeds to cellular networks, due to availability of large amounts of bandwidth. The unique challenges of heavy path-loss faced by millimeter-wave systems necessitate new techniques such as hybrid beamforming (analog and digital), which are not present in <NUM> and <NUM> systems. Hybrid beamforming may enhance link budget/signal to noise ratio (SNR) that may be exploited during the RACH.

Spectrum bands in high frequencies (e.g., <NUM>, may be referred to as mmW (or mmWave)) provide large bandwidths capable of delivering multi-Gbps data rates, as well as extremely dense spatial reuse which may increase capacity. Traditionally, these higher frequencies were not robust enough for indoor/outdoor mobile broadband applications due to high propagation loss and susceptibility to blockage (e.g., from buildings, humans, and the like).

Despite these challenges, at the higher frequencies in which mmW operate, small wavelengths enable a large number of antenna elements in a relatively small form factor. Unlike microwave links, which may cast very wide footprints, reducing the achievable amount of reuse of the same spectrum within a geographical area, mmW links cast very narrow beams (for example, beams may have a narrow angle). This characteristic of mmW may be leveraged to form directional beams that may send and receive more energy to overcome propagation and path loss challenges.

These narrow directional beams can also be utilized for spatial reuse. This is one of the key enablers for utilizing mmW for mobile broadband services. In addition, the non-line-of-site (NLOS) paths (e.g., reflections from nearby building) can have very large energies, providing alternative paths when line-of-site (LOS) paths are blocked.

In a beamformed wireless communication system, a wireless device may transmit and receive using directional beams. A UE may receive, from a BS one or more downlink signals. The UE may receive the downlink signals using one or more receive beams at the UE.

Certain aspects of the present disclosure generally relate to methods and apparatus for a SS which may be used to facilitate mobility. The SS is transmitted using a UE-specific configuration of time/frequency resources. In certain aspects, the SS may be a UE-specific SS, wherein the SS is specific to one or a group of UE. In certain aspects, the SS may be transmitted using a UE-specific allocation of resources. In this manner, an SS, which is not cell-specific is transmitted by serving and/or target BSs and used for mobility purposes. In certain aspects, UE-specific RACH resources are used for mobility.

As described herein, a BS may transmit an indication of SS resources that may be used for an SS, UE-specific SS, and/or UE-specific RACH. In certain scenarios, a BS serving the UE may transmit an indication of the UE-specific resources used by the serving BS and the UE specific resources used by a non-serving, target BS. The serving BS may transmit an indication of UE-specific RACH resources the UE may use in a RACH procedure with the target BS. As described herein, mobility may refer handover. Mobility may refer to L3 mobility, wherein a UE maintains at least one internet protocol (IP) session while moving from a serving BS to a target BS. Aspects described herein may be used for connected mode L3 mobility, wherein the UE has an active RRC connection with a BS.

Aspects of the present disclosure provide techniques and apparatus for using a UE-specific or group of UE-specific SS blocks for connected mode handover. As described herein, a BS may transmit the UE-specific SS signal (or UE-specific SS block). The SS or SS block may be UE-specific or specific to a group of UEs. According to aspects, a BS may also transmit an allocation of UE-specific contention-free RACH resources for a connected mode handover. According to an example, the allocation of UE-specific contention-free RACH resources may be UE-specific or specific to a group of UEs. As described in more detail herein, the UE-specific contention-free RACH resources may be based, at least in part, on the UE-specific SS. The UE-specific SS and UE-specific contention-free RACH resources may be aperiodic.

<FIG> illustrates an example wireless network <NUM> in which aspects of the present disclosure may be performed. For example, the wireless network may be a new radio (NR) or <NUM> network.

Aspects of the present disclosure relate to a BS conveying an allocation of UE-specific SS or group of UE-specific SS for mobility in a connected mode. Mobility may refer to hand over from a serving BS to target BS. As an example, mobility may refer to a connected mode hand over where a UE maintains at least one active IP session during the hand over. According to an example, the BS may also transmit an allocation of UE-specific contention-free RACH resources. In one example, the UE-specific SS and UE-specific RACH resources may be aperiodic.

According to aspects, a BS may assign at least one UE-specific configuration. The UE-specific configuration comprises an allocation of resources for an SS. The BS may communicate with the UE based, at least in part, on the UE-specific configuration. In one aspect, the BS may communicate with a BS serving the UE. The BS serving the UE may transmit an indication of the allocation of resources to the UE.

Correspondingly, a UE may receive an assignment of at least one UE-specific configuration, wherein the UE-specific configuration comprises an allocation of resources for an SS. A UE may communicate with a BS based, at least in part, on the UE-specific configuration.

UEs <NUM> may be configured to perform the operations <NUM> and other methods described herein and discussed in more detail below associated with UE-specific SS communication. Base station (BS) <NUM> may comprise a transmission reception point (TRP), Node B (NB), <NUM> NB, access point (AP), new radio (NR) BS, gNB, etc.). The NR network <NUM> may include the central unit. The BS <NUM> may perform the operations <NUM> and other methods described herein.

A BS 110a may be a serving BS for the UE <NUM>. A non-serving or target BS 110b or 110c may communicate with a BS 110a. As an example, the non-serving or target BS may exchange scheduling information, BS or UE <NUM> capability information, or configuration information associated with an SS (which may be a UE-specific SS) or UE-specific RACH resources.

As illustrated in <FIG>, the wireless network <NUM> may include a number of base stations (BSs) <NUM> and other network entities. A BS may be a station that communicates with user equipments (UEs). Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term "cell" and next generation NodeB (gNB), new radio base station (NR BS), <NUM> NB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network <NUM> through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

In some examples, access to the air interface may be scheduled, wherein a. A scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within its service area or cell.

<FIG> illustrates example components of the BS <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. As described above, the BS may include a TRP. One or more components of the BS <NUM> and UE <NUM> may be used to practice aspects of the present disclosure including the operations <NUM> and <NUM> illustrated in <FIG> and <FIG>. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, Tx/RX <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to <FIG>.

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the BS <NUM> and the UE <NUM>, respectively.

A mini-slot is a subslot structure (e.g., <NUM>, <NUM>, or <NUM> symbols).

In some wireless systems, such as LTE, mobility is based on an SS transmitted from one or more BSs. The SS signals (or SS blocks) are periodic and cell-specific. Additionally, RACH resources are tied to the SS. RACH resources, similar to SS resources, may also be cell-specific and periodic.

In NR, however, connected mode L3 mobility is based on SS blocks, which may include, for example, a primary synchronization signal (PSS), secondary synchronization signal (SSS), demodulation reference signal (DRMS) for a physical broadcast channel (PBCH), and/or CSI-RS (if CSI-RS is configured). In NR, SSs are transmitted from multiple antenna ports may share the same time/frequency resources. For example, <NUM> antenna ports at a BS may transmit SSs in <NUM> different directions; however, within a single symbol, the SS may be located within the same set of tones. In NR, CSI-RS may occupy different time/frequency resources.

According to aspects of the present disclosure, a BS transmits a UE-specific configuration for an SS signal or SS block (or a group of UE-specific SS or SS blocks) for connected mode handover. UE-specific SS refers to SS transmitted in a direction of the UE. As an example, UE-specific SS may be transmitted using beam which are focused in a direction of the UE. Connected mode handover may refer to handover of a UE from a serving BS to a target BS, wherein the UE maintains at least one IP session during the handover.

In certain situations, the BS may also transmit an allocation for UE-specific contention-free RACH resources. In one example, the BS may transmit an allocation for a group of UEs, wherein the allocation of contention-free RACH resources is specific to the group of UEs. The SS blocks, which according to certain aspects, may be UE-specific, and RACH resources may be aperiodic.

As described herein, an SS block may include one or more of a PSS, SSS, PBCH, and/or DMRS of PBCH. As used herein, signaling (SS or RACH, which according to aspects may be UE-specific SS and/or UE-specific RACH) may refer to transmissions from a BS which are focused in the direction of the UE. As an example the BS may use more beams concentrated in a direction associated with the location of the UE.

According to aspects of the present disclosure a BS may use a same set of beams while transmitting UE-specific/group of UE-specific SS blocks and while receiving UE-specific/group of UE-specific contention free RACH resources. The set of beams may be different from the beams used for regular SS block transmissions/regular RACH reception. According to aspects, the UE selects the RACH resource and preamble from the UE-specific/group of UE-specific contention-free RACH resources based on a suitable SS block and transmits accordingly.

As noted above, in some wireless systems, like LTE, a BS transmits a cell-specific SS. For example, the PSS and SSS may be transmitted every <NUM> and the PBCH may be transmitted every <NUM>. In NR, instead of transmitting a SS in one location of a <NUM> period, the BS may transmit multiple SSs in different directions (using different directional beams, for example, as illustrated in <FIG>) within the <NUM> time period.

<FIG> illustrates an SS block time pattern <NUM> that may be used for <NUM> subcarrier spacing in NR. As shown at <NUM>, a first slot may include <NUM> symbols (e.g., as illustrated in the second row at <NUM>, which may be numbered <NUM>-<NUM>). The mapping pattern preserves <NUM> symbols (symbols <NUM>-<NUM>) for DL control at the beginning of the first slot of <NUM> symbols. This allows larger aggregation level for DL control for <NUM> and <NUM> subcarrier spacing and allows TDM multiplexing of at least one SS block within the LTE subframe.

The mapping <NUM> preserves <NUM> symbols at the end of the first slot of <NUM> symbols are for guard period and UL control for <NUM>. The mapping preserves <NUM> symbols for DL control at the beginning of the second slot of <NUM> symbols, which may be used for DL control for <NUM>. The mapping preserves <NUM> symbols at the end of the second slot of <NUM> symbols for guard period and UL control.

As illustrated at <NUM> and <NUM>, two SS blocks may be mapped to the first slot of <NUM> symbols. The first location <NUM> may be at symbols <NUM>-<NUM>. The second location <NUM> may be at symbols <NUM>-<NUM>.

As illustrated at <NUM> and <NUM>, two SS blocks may be mapped to the second slot of <NUM> symbols. At <NUM>, the third location is at symbols <NUM>-<NUM>. As <NUM>, the fourth location is at symbols <NUM>-<NUM>.

<FIG> illustrates an example <NUM> of a BS and UE in an NR system, in accordance with aspects of the present disclosure. As noted above, a BS may transmit signals in a cell-specific manner. The BS may attempt to cover most (or all) directions of the cell, such that a UE may receive a transmitted signal, irrespective of its location within the cell. The BS may receive RACH signals from different areas of the cell. The BS <NUM> and the UE <NUM> may communicate using beamformed communication, wherein signals are transmitted and received using directional beams. A beam may be associated with one or more (beamformed) antenna ports.

The BS <NUM> may transmit using various transmit beam directions, in an effort to cover all directions of the cell. A UE <NUM> located in the cell may thus receive a signal transmitted by the BS <NUM>, regardless of the location of the UE within the cell.

In one example, the BS <NUM> may typically transmit in <NUM> directions covering all possible angles in azimuth and elevation. In other words, the BS may cover <NUM> degrees in azimuth and <NUM> degrees around the horizontal line in elevation. The BS may split this area into equal angular portions (regions) and transmit a beam in each of these portions. If a BS has some idea of where a UE is located in a cell, the BS may transmit more SS signals (SS blocks) towards the UE's location. In this manner, the SS signaling may be UE-specific or specific to a group of UEs. By transmitting more signaling in the direction of a UE, the BS may achieve greater beamforming gains in that direction.

According to one example, initially, a non-serving, target BS may transmit a cell-specific SS or beam refinement signal (BRS). A UE may detect the cell-specific SS or BRS transmitted by this non-serving BS. The UE may report to its serving BS detection of this cell-specific SS or BRS and the direction of the target cell as seen by the UE.

The UE's serving BS may communicate with the target BS, indicating the UE's angular direction relative to the target BS. Thereafter, the target BS may transmit one or more SS signaling using a UE-specific configuration in the direction of the UE. This may allow the serving BS to better estimate the link gain from the SS transmitted by the target BS. According to aspects, the UE's serving BS may also transmit SS signaling using a UE-specific configuration.

The UE may receive the SS, transmitted us the UE-specific configuration, from the serving and target BS and may take signal quality measurements associated with the SS. According to aspects, the UE-specific configuration may include a time and/or frequency location of a SS block (SSB), SS signal, or SS burst, a periodicity of a SS signal used for mobility, locations of SSBs in the SS burst that need to be measured.

The UE may report the measurements to the serving BS. With this information, the serving BS may decide to handover the UE to the target cell. Alternatively, if the link quality of the target cell is not better (or does not exceed the link quality associated with serving BS by a threshold amount), the serving BS may decide not to handover the UE to the target BS.

If the UE is to be handed over to the target BS, the target BS may generate UE-specific RACH resources which correspond to UE-specific configuration used to transmit the SS block. Stated otherwise, the SS and UE-specific contention free RACH resources may be mapped to each other. The UE may select a preamble and use the UE-specific RACH resources to access and connect to the target BS. In an example, UE-specific configuration for the RACH procedure indicates beams that the BS may use to receive a RACH preamble transmitted by the UE. Additionally or alternatively, the UE-specific configuration for the RACH procedure indicates the RACH occasions (time and frequency resources) for the RACH procedure.

According to another example, a connected mode UE receives SS blocks transmitted using a UE-specific configuration from its serving BS. To trigger transmission of SS from a target BS, the UE may detect the presence of the target BS and may report the link quality and associated transmit beams of target BS. This may occur based on the SS from the target BS or BRS.

The UE may measure the signal strength associated with the SS from the serving BS and the target BS. This information may be used to compare link quality associated with both cells. If the UE has strong link quality with the target BS, the UE's serving BS may inform the target BS to transmit a UE-specific SS to the UE.

Furthermore, to speed up handover, the target BS may assign UE-specific contention-free RACH resource to the UE. The assignment may be communicated to the UE via the UE's serving BS. According to aspects, the target BS may indicate the receive beam directions the target BS may use during a RACH procedure with the UE. The serving BS may communicate the receive beam directions to the UE.

Notably, UE-specific contention-free RACH resources may use a different receive beam as compared to receive beams used in a typical RACH procedure. This is, in part, because the target BS has some information associated with the UE's location. Accordingly, the target BS may create more receive beams in the direction of the UE. The UE may receive an indication of the receive beam used by the BS during the RACH procedure.

According to aspects, the target BS may convert or repurpose a subframe typically used for data transmission. For example, a subframe typically used for data may be used for contention-free RACH. In this manner, the UE-specific RACH may be aperiodic.

According to aspects, the SS transmitted using a UE-specific configuration may be transmitted in a subframe typically reserved for data transmissions. The SS may not need to be transmitted in locations used for cell-specific SS transmissions.

According to aspects, the allocation of UE-specific time/frequency resources of the SS transmitted by the target BS may be selected such that the SS from the target BS does not collide with the SS from a serving BS. The serving and target BS may exchange information regarding communication schedules, UE capability, and BS capability, in an effort to avoid collisions. According to one example, signals from a serving BS and target BS may be received by the UE using different subarrays at the UE. Depending on a UE's capability, the UE may not be able activate multiple subarrays simultaneously. If, for example, the UE has only one subarray or one receive chain, it may not be able to simultaneously receive transmissions from both the serving BS and a target BS. If the UE has multiple subarrays, it may be able to simultaneously receive a SS from a target BS while receiving data from a serving BS.

According to aspects, a target BS may generate a UE-specific RACH resources which correspond to a SS block. Stated otherwise, the SS, transmitted using a UE-specific configuration, and the UE-specific RACH are mapped to each other. A UE-specific RACH may refer to a BS generating more RACH beams in the angular region of the UE, in an effort to receive a RACH preamble from the UE. The BS may achieve better beamforming gains while receiving RACH signaling when the BS generates more RACH beams in the direction of the UE.

<FIG> illustrates example operations <NUM> which may be performed by a BS, in accordance with aspects of the present disclosure. The BS may include one or more components illustrated in <FIG>.

At <NUM>, the BS may assign at least one UE-specific configuration, wherein the UE-specific configuration comprises an allocation of resources for an SS which may be used for mobility. According to aspects, the SS may be a UE-specific SS. At <NUM>, the BS may communicate with the UE based, at least in part, on the UE-specific configuration.

<FIG> illustrates example operations <NUM> which may be performed by a UE, in accordance with aspects of the present disclosure. The UE may include one or more components illustrated in <FIG>.

At <NUM>, the UE may receive an assignment of at least one UE-specific configuration, wherein the UE-specific configuration comprises an allocation of resources for an SS which may be used for mobility. As noted above, according to aspects, the SS may be a UE-specific SS. At <NUM>, the UE may communicate with a BS based, at least in part, on the UE-specific configuration.

In one example, the target BS may transmit the UE-specific configuration to the UE's serving BS. The BS serving the UE may transmit the UE-specific configuration to the UE. According to an aspect, a network entity may configure or transmit the UE-specific configuration to one or both of the serving BS and a target BS.

The configuration may include resources used by the BS to transmit the SS. As described above, in certain situations, both a serving BS and a target BS may transmit SSs on UE-specific resources. The BS serving the UE may transmit an indication of the SS transmitted by the serving BS and an indication of the SS transmitted by target BS.

The UE-specific configuration associated with the SS may include one or more parameters described herein. For example, the configuration may indicate the time/frequency resources used for transmitting the SS. The configuration may include an indication of a transmit beam sweeping pattern used by the BS to transmit the SS. The configuration may include a composition of a SS block used to transmit the SS. Thus, the configuration may indicate the constituent signals within the SS block and their relative location in time/frequency. As an example, the configuration may indicate if a Physical Broadcast Channel (PBCH) is transmitted with the SS and/or a content of the PBCH.

The configuration may include number of SS bursts (e.g., burst sets) transmitted by a BS. NR, an SS burst set may include a number of SS blocks wherein the SS blocks of the burst may be transmitted in different directions. The configuration may include the relative location in time and frequency of the SS block. For example, in LTE, the PSS/SSS may arrive at the beginning of each <NUM> period; however, as described above, a data slot may be repurposed to transmit a SS using a UE-specific configuration.

An SS block may include the combination of PSS, SSS, tertiary synchronization signal (TSS), and PBCH. A BS may transmit SS blocks (in a burst set) in different directions (e.g., using beamformed transmissions). Assuming a SS burst set contains N SS blocks, the BS may transmit every Nth SS block of the burst set (e.g., SS blocks having an index of <NUM>, N+<NUM>, 2N+<NUM>, etc.) in a same direction.

The configuration may indicate the waveforms of signals transmitted with the SS signals or of the SS signals themselves. The waveforms may include at least one of a primary synchronization signal (PSS), secondary synchronization signal (SSS), tertiary synchronization signal (TSS), or a demodulation reference signal (DMRS) for a physical broadcast channel (PBCH). A TSS may be used to inform a UE of the timing within a <NUM> time period. As noted above, in LTE, the PSS/SSS is transmitted every <NUM>. In <NUM>, there may be up to <NUM> SS blocks every <NUM>. Accordingly, a UE may detect a PSS/SSS and not know the timing of a cell. The TSS may indicate the timing within a <NUM> period.

The configuration may indicate the content of a PBCH, such as how many bits are used for the PBCH transmission and what information is conveyed using those bits.

The configuration may indicate a numerology associated with the SS. The numerology may refer to tone spacing associated with the SS.

According to aspects, the SS is transmitted in a slot typically used for cell-specific SS transmission. According to another example, the SS is transmitted in a slot typically used for data transmission.

The UE-specific configuration may also include an assignment of UE-specific resources for a RACH procedure. The RACH procedure may be contention-based or contention-free. The UE may receive this configuration, select at least one RACH preamble based and perform a RACH procedure with a target BS based, at least in part, on the UE-specific resources for the RACH procedure. The resources for the RACH may be based on the UE-specific SS.

The configuration for the UE-specific RACH procedure may include one or more parameters. The configuration may include an indication of the time/frequency resources used for transmitting RACH signaling by the BS. The configuration for the RACH procedure may include at least one preamble or set of preambles assigned to the UE for the RACH procedure. The UE may select one of the preambles for the RACH procedure. The configuration may include a number of RACH preambles to be transmitted by the UE during the contention-free RACH procedure. The configuration may include an indication of receive beams used by the BS to receive a RACH preamble during the contention-free RACH procedure. The configuration may include a numerology (tone spacing) associated with the contention-free RACH procedure.

According to aspects, the UE may transmit RACH using cell-specific RACH time/frequency resources, even if the UE is assigned UE specific RACH resource. According to an example, A BS may provide a group of UE-specific RACH resource and allow contention-based RACH in those resources.

Contention-free RACH resources may be allocated to slot that is typically used for contention-based RACH procedures. According to aspects, a data slot is repurposed for UE-specific RACH procedures. For example, the BS and UE exchange RACH signaling in a slot typically used for data transmission.

The resources for SS or UE-specific RACH may be aperiodic.

According to aspects, a UE-specific configuration (for SS or for both SS and UE-specific RACH) may be based, at least in part on the BS's capability. The capability may be based on a BS's a beam correspondence capability. A beam correspondence capability refers to a BS's ability to map a BS transmit beam to a BS receive beam. Stated otherwise, with beam correspondence, a BS may use a same beam or a same set of beam to transmit a SS and receive RACH signaling from a UE.

The BS capability may be based on a radio frequency (RF) or digital processing capability, and/or a number of antenna ports at the BS. For example, if the BS has multiple antenna ports, it may allocate more time to transmit SS to the UE or receive RACH from the UE, as some of the antenna ports may be used to communicate with other UEs.

The BS capability may indicate whether a BS can communicate with other nodes (UEs or BSs) within a same slot (as the SS or UE-specific contention-free RACH).

According to aspects, the configuration is determined based on a communication schedule associated with the BS and at least one other BS or another UE. For example, resources for the SS or UE-specific contention-free RACH may be allocated in an effort to align or avoid overlapping with transmission to/from other BSs.

According to aspects, the UE-specific configuration is based, at least in part on a UE's capability. The capability may include a beam correspondence capability of the UE. If the UE has beam correspondence capabilities, the BS may reserve less resources for a UE's RACH transmission. If the UE does not have beam correspondence, the UE may not be able to map a receive beam used for UE-specific SS to a transmit beam used for RACH transmission.

The UE-specific configuration may be based on the RF capability, a number of antenna ports at the UE, or antenna configuration at the UE. A greater number of antenna ports may allow a UE to spend more time receiving SS or transmitting RACH. The configuration may be based on whether the UE may communicate with other nodes within the same slot while receiving SS or transmitting RACH.

The UE-specific configuration may be based on a communication schedule associated with the UE and another NB.

According to aspects, the configuration is specific to a group of UEs. As described herein, the UE-specific configuration may be used to facilitate handover and mobility, including L3 mobility. L3 mobility allows the UE to maintain at least one IP session during handover. L3 mobility may include idle mode L3 mobility (when the UE is in idle mode) or connected mode L3 mobility (when the UE is not in idle mode).

According to aspects, a BS (such as a target BS) may determine the UE-specific configuration based on a measurement report associated with a cell-specific signaling transmitted by target BS. For example, the target BS may transmit cell-specific SS. The UE may detect and measure the cell-specific SS. The UE may provide this information to its serving BS. The UE may also indicate, to the serving BS, the direction in which it receive the cell-specific SS. The serving BS may transmit this information to the target BS. In response, the target BS may determine the UE-specific configuration for the UE.

According to aspects, the target BS may receive from the BS serving the UE, a transmission schedule associated with the serving BS. The SS may be assigned based, at least in part, on the received transmission schedule. The UE-specific SS may avoid colliding with transmissions to/from the serving BS.

As described above, the serving BS may transmit a SS configuration to the UE. This may allow the UE to measure the SS transmitted by both the serving and target BS, in an effort to determine if the UE should handover. For example, the UE may measure both signals and transmit a measurement report. The serving BS may make mobility management decisions based, at least in part, on the received measurement report.

As described herein, SS may be used for mobility management in NR. In an example, a BS may use a same set of beams while transmitting the SS and receiving UE-specific contention-free RACH signaling from the UE.

Aspects of the present disclosure are described with respect to an SS used for mobility management purposes, wherein the SS is transmitted using UE-specific resources. In certain aspects, the SS is a UE-specific SS.

<FIG> depicts a communications device <NUM> that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in <FIG>. The transceiver <NUM> is configured to transmit and receive signals for the communications device <NUM> via an antenna <NUM>, such as the various signals described herein.

The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium/memory <NUM> via a bus <NUM>. In certain aspects, the computer-readable medium/memory <NUM> is configured to store computer-executable instructions that when executed by processor <NUM>, cause the processor <NUM> to perform the operations illustrated in <FIG> or other operations for performing the various techniques discussed herein.

In certain aspects, the processing system <NUM> further includes an assigning component <NUM> and a communicating component <NUM> for performing the operations illustrated in <FIG>. In certain aspects, the communicating component <NUM> may be part of the transceiver <NUM>. In certain aspects, the processing system <NUM> includes one or more other non-illustrated components. The components <NUM>, <NUM>, and components configured to perform the operations describe herein may be coupled to the processor <NUM> via bus <NUM>. In certain aspects, the components <NUM> and <NUM> (and other non-illustrated components) may be hardware circuits. In certain aspects, the components <NUM> and <NUM> (and other non-illustrated components) may be software components that are executed and run on processor <NUM>.

In certain aspects, the processing system <NUM> further includes a communicating component <NUM> for performing the operations illustrated in <FIG>. In certain aspects, the communicating component <NUM> may be part of the transceiver <NUM>. In certain aspects, the processing system <NUM> includes one or more other non-illustrated components. The component <NUM> and other optional components configured to perform the operations describe herein may be coupled to the processor <NUM> via bus <NUM>. In certain aspects, the component <NUM> (and other non-illustrated components) may be hardware circuits. In certain aspects, the component <NUM> (and other non-illustrated components) may be software components that are executed and run on processor <NUM>.

§<NUM>, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for.

For example, instructions for perform the operations described herein and the appended figures.

Claim 1:
A method (<NUM>) for wireless communication by a user equipment, UE, comprising:
receiving (<NUM>) an assignment of at least one UE-specific configuration, wherein the UE-specific configuration comprises an allocation for a group of UE-specific resources for at least one synchronization signal, SS, for mobility, wherein the mobility is a L3 mobility and wherein the UE has an active radio resource control, RRC, connection with a base station; wherein the UE-specific configuration comprises an indication of a first SS of the at least one SS to be transmitted by a serving base station, BS, and an indication of at least a second SS of the at least one SS to be transmitted by a target BS, wherein the indications of the SS indicate locations in time and/or frequency of the SS; and
communicating (<NUM>) with the base station, BS, based, at least in part, on the UE-specific configuration.