Patent Description:
Wireless communication systems, as for example described in 3GPP R1-<NUM>, are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (for example, bandwidth, transmit power, etc.).

New radio (for example, <NUM> NR) is an example of an emerging telecommunication standard.

However, as the demand for mobile broadband access continues to increase, further improvements, e.g., improvements in latency, reliability, and the like, in NR and LTE technology remain useful.

A control resource set (CORESET) for systems, such as an NR and LTE systems, may comprise one or more control resource (e.g., time and frequency resources) sets, configured for conveying PDCCH, within the system bandwidth. Within each CORESET, one or more search spaces (e.g., common search space (CSS), UE-specific search space (USS), etc.) may be defined for a given UE.

One innovative aspect of the subject matter described in this disclosure can be implemented in a method for wireless communication by a user equipment (UE). The method generally includes receiving, from a network entity, cell information for neighbor cells; searching for synchronization symbols from the neighbor cells based on the cell information; based on the synchronization symbols from the neighbor cells, identifying one of the neighbor cells to perform a handover to; and initiating a handover from a serving cell to the identified one of the neighbor cells.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

The following description and the appended drawings set forth in detail some illustrative features of the one or more aspects.

In the following description, the invention is described with particular reference to <FIG>, while the description of the remaining figures is provided for illustrative purposes for a better understanding of the invention.

However, the accompanying drawings illustrate only some typical aspects of this disclosure and are therefore not to be considered limiting of its scope.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for detecting neighbor cells using cell identifier and cell timing information.

The following description provides examples of detecting neighbor cells using cell identifier and cell timing information, and is not limiting of the scope, applicability, or examples set forth in the claims.

For example, as shown in <FIG>, UE 120a may include a neighbor cell detection module <NUM> that may be configured to perform (or cause UE 120a to perform) operations <NUM> of <FIG>. Similarly, a base station 110a may include a neighbor cell configuration module <NUM> that may be configured to communicate cell identifier and cell timing information that UE 120a can use to identify and hand over to a neighboring cell, as discussed in further detail below.

NR access (for example, <NUM> NR) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (for example, <NUM> or beyond), millimeter wave (mmWave) targeting high carrier frequency (for example, <NUM> or beyond), massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, or mission critical services targeting ultra-reliable low-latency communications (URLLC). In addition, these services may co-exist in the same time-domain resource (for example, a slot or subframe) or frequency-domain resource (for example, component carrier).

In some examples, the BSs <NUM> may be interconnected to one another or to one or more other BSs or network nodes (not shown) in wireless communication network <NUM> through various types of backhaul interfaces (for example, a direct physical connection, a wireless connection, a virtual network, or the like) using any suitable transport network. The UEs <NUM> (for example, 120x, 120y, etc.) may be dispersed throughout the wireless communication network <NUM>, and each UE <NUM> may be stationary or mobile.

Wireless communication network <NUM> may also include relay stations (for example, relay station 110r), also referred to as relays or the like, that receive a transmission of data or other information from an upstream station (for example, a BS 110a or a UE 120r) and sends a transmission of the data or other information to a downstream station (for example, a UE <NUM> or a BS <NUM>), or that relays transmissions between UEs <NUM>, to facilitate communication between devices.

The BSs <NUM> may also communicate with one another (for example, directly or indirectly) via wireless or wireline backhaul.

<FIG> shows a block diagram illustrating an example base station (BS) and an example user equipment (UE) in accordance with some aspects of the present disclosure.

The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), etc. The data may be for the physical downlink shared channel (PDSCH), etc. The processor <NUM> may process (for example, encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor <NUM> may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (for example, precoding) on the data symbols, the control symbols, or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a-232t. Each modulator <NUM> may process a respective output symbol stream (for example, for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE <NUM>, the antennas 252a-252r may receive the downlink signals from the BS <NUM> and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator <NUM> may condition (for example, filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (for example, for OFDM, etc.) to obtain received symbols. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (for example, demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE <NUM> to a data sink <NUM>, and provide decoded control information to a controller/processor <NUM>.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data (for example, for the physical uplink shared channel (PUSCH)) from a data source <NUM> and control information (for example, for the physical uplink control channel (PUCCH) from the controller/processor <NUM>. The transmit processor <NUM> may also generate reference symbols for a reference signal (for example, for the sounding reference signal (SRS)). The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the demodulators in transceivers 254a-254r (for example, for SC-FDM, etc.), and transmitted to the BS <NUM>.

A scheduler <NUM> may schedule UEs for data transmission on the downlink or uplink. In one example, memory <NUM> or memory <NUM> can be a non-transitory computer-readable medium comprising instructions (e.g., instructions that instruct a processor, e.g., controller/processor <NUM>, controller/processor <NUM>, or other processor) to perform any aspects of <FIG> and/or <NUM>. Additionally or alternatively, such instructions may be copied or installed onto memory <NUM> or memory <NUM> from a non-transitory computer-readable medium.

The controller/processor <NUM> or other processors and modules at the UE <NUM> may perform or direct the execution of processes for the techniques described herein. As shown in <FIG>, the controller/processor <NUM> of the UE <NUM> has a neighbor cell detection module <NUM> that may be configured to perform operations <NUM> of <FIG>, as discussed in further detail below. The controller/processor <NUM> of the base station <NUM> includes a neighbor cell configuration module <NUM> that may be configured to configure a UE (e.g., UE <NUM>) with cell identifier and cell timing information that the UE can use to detect and hand over to neighbor cells, as discussed in further detail below. Although shown at the Controller/Processor, other components of the UE or BS may be used to perform the operations described herein.

A control resource set (CORESET) for systems, such as an NR and LTE systems, may comprise one or more control resource (e.g., time and frequency resources) sets, configured for conveying PDCCH, within the system bandwidth. Within each CORESET, one or more search spaces (e.g., common search space (CSS), UE-specific search space (USS), etc.) may be defined for a given UE. According to aspects of the present disclosure, a CORESET is a set of time and frequency domain resources, defined in units of resource element groups (REGs). Each REG may comprise a fixed number (e.g., twelve) tones in one symbol period (e.g., a symbol period of a slot), where one tone in one symbol period is referred to as a resource element (RE). A fixed number of REGs may be included in a control channel element (CCE). Sets of CCEs may be used to transmit new radio PDCCHs (NR-PDCCHs), with different numbers of CCEs in the sets used to transmit NR-PDCCHs using differing aggregation levels. Multiple sets of CCEs may be defined as search spaces for UEs, and thus a NodeB or other base station may transmit an NR-PDCCH to a UE by transmitting the NR-PDCCH in a set of CCEs that is defined as a decoding candidate within a search space for the UE, and the UE may receive the NR-PDCCH by searching in search spaces for the UE and decoding the NR-PDCCH transmitted by the NodeB.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for discovering neighbor cells using cell identifier and cell timing information.

Typically, to discover a potential neighbor cell, a UE may perform a blind search for neighboring cells. A blind search may entail searching for all possible combinations of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) to identify one of a plurality of physical cell identifiers. For example, each combination of a PSS and SSS may map to one of <NUM> physical cell identifiers (PCIs).

Generally, the PSS and SSS may be transmitted by a cell periodically. For example, the PSS and SSS may be transmitted every <NUM> milliseconds or with a periodicity of a half frame (HF). In a blind search, however, the UE may not know specific information about the timing at which the PSS and SSS are transmitted. That is, the UE may know that the PSS and SSS may be transmitted with a specific periodicity but may not have information about a reference point in time from which to attempt to detect the PSS and/or SSS. Thus, to detect a neighboring cell, the UE may attempt to detect a PSS and an SSS in each possible time instance to identify accurate timing information for the detected neighboring cell.

Additionally, the UE may have information about a center frequency on which a neighboring cell operates. To detect a neighboring cell, a UE may need at least <NUM> milliseconds of samples from each frequency layer. The UE may thus hypothesize the location of the PSS and SSS of the neighboring cell <NUM>,<NUM> times, assuming a sampling rate of <NUM> to detect a neighbor cell having one of <NUM> different PCIs.

Further, UEs operating in coverage enhanced modes (e.g., for Machine Type Communication (MTC) or enhanced MTC (eMTC) UEs) may have limited communications resources (e.g., a single receive/transmit chain) and operate in low signal-to-noise ratio (SNR) environments. Because these UEs may have limited communications resources, these UEs may correlate received signals across multiple half frames to detect neighboring cells. This may further delay the identification of neighbor cells to which the UE can hand over.

Generally, the efficiency of neighbor cell detection and handover processes may be impacted by the number of timing and frequency hypotheses a UE makes in order to detect a neighboring cell. For example, detection probability generally increases as the UE makes more hypotheses; however, increased detection probability may be correlated with increased power consumption and longer timing delays in detecting and handing over to neighboring cells. Power consumption and timing delays in detecting and handing over to neighboring cells may be exasperated for UEs that have fewer communications resources (e.g., MTC/eMTC UEs operating in coverage enhanced modes), as these UEs may operate in environments where it is more difficult to detect and decode the PSS and SSS of a neighboring cell.

To accelerate the detection of neighboring cells, aspects described herein provide for the communication of neighbor cell identifier and cell timing information from a serving network entity to a UE. Using this cell identifier and cell timing information, a UE can attempt to identify neighboring cells with the cell identifiers provided by the serving network entity and attempt to hand over to one of the identified neighboring cells. Because the UE may have information about neighboring cell timing and cell identifiers, the UE may reduce the number of timing hypotheses needed to identify a neighboring cell. Neighbor cell detection may be improved, for example, in low SNR environments. Further, neighbor cell detection may be accelerated, which may accelerate handover procedures, improve throughput, and reduce power usage at a UE.

<FIG> illustrates operations <NUM> that are performed by a user equipment (UE) to detect neighboring cells based on cell identifier and cell timing information received from a serving network entity.

As illustrated, operations <NUM> begin at block <NUM>, where the UE receives, from a network entity, cell information for neighbor cells. As discussed in further detail herein, the cell information for neighbor cells generally includes information that the UE can use to accelerate the process of searching for and synchronizing with neighbor cells. For example, the cell information may include cell identifier information, timing synchronization information, and other information that the UE can use in identifying neighbor cells to which the UE can hand over.

At block <NUM>, the UE searches for synchronization signals from the neighbor cells based on the cell information. The UE can search for synchronization signals using the cell identifier and timing information (and other cell information) provided by the network to the UE at block <NUM>. For example, the UE can search for a PSS and SSS that maps to one of a plurality of cell identifiers (e.g., a cell identifier associated with a specific neighbor cell), and the UE can use timing information associated with the neighbor cell to adjust its clock such that the PSS and SSS mapping to the one of the plurality of cell identifiers associated with the neighbor cell is successfully received without needing to attempt to blindly search for the PSS and SSS.

At block <NUM>, the UE identifies, based on the synchronization signals from the neighbor cells, one of the neighbor cells to perform a handover to. The UE can identify a neighbor cell to which the UE is to hand over based on cell measurements for each of the neighbor cells detected by the UE at block <NUM>. Generally, the UE can select the neighbor cell to which the UE is to hand over as the neighbor cell having sufficient signal strength for communications with the UE. For example, the UE can select one of a plurality of neighbor cells having a measured signal strength exceeding a threshold. In another example, the UE can select the neighbor cell having a highest measured signal strength of the plurality of neighbor cells identified at block <NUM>.

At block <NUM>, the UE initiates a handover from a serving cell to the identified one of the neighbor cells.

In some embodiments, to initiate a handover from a serving cell to the identified one of the neighbor cells, the UE may transmit a measurement report to the serving cell. The measurement report may include measurements from the one or more detected neighbor cells, including the one of the neighbor cells identified by the UE as a neighbor cell to perform a handover to. The identified one of the neighbor cells may include, for example, the detected neighbor cell having a highest signal quality metric (e.g., received signal strength) measured by the UE. Subsequent to transmitting the measurement report, the UE may receive a handover trigger identifying the neighbor cell with which the UE is to communicate (e.g., the one of the neighbor cells identified based on the synchronization signals received from the detected neighbor cells), and the UE may attach and synchronize with the identified neighbor cell.

In some embodiments, the UE may receive cell information for neighbor cells from a serving network entity. The cell information may be received, for example, when a UE attaches to a serving network entity, on request, or periodically. For example, a UE may request the cell information when a signal quality metric falls below a threshold value. In some embodiments, the signal quality metric may be a metric measured over a time window such that a decrease in signal quality of a sufficient amount indicates that the UE may hand over from a serving network entity to another network entity at a future point in time.

The cell information includes a subset of neighboring cell identifiers on a plurality of frequency bands and time synchronization information for each of the neighbor cells. The neighboring cell identifiers are cell identifiers included in intra-frequency and/or inter-frequency neighboring cell lists (e.g., in intraFreqNeighCellList and/or interFreqNeighCellList). In some embodiments, the serving network entity may pass the inter-frequency and/or inter-frequency neighboring cell lists to a UE automatically if the network supports communications with coverage enhanced UEs (e.g., MTC/eMTC UEs).

The time synchronization information may be provided to a UE on a per-cell basis. In some embodiments, the time synchronization information may be time offset information, relative to the timing of the serving network entity. The time offset information may be expressed at varying levels of granularity, such as a symbol duration, a slot duration, a subframe duration, or the like. In some embodiments, the time synchronization information may be a synchronization flag or other binary indicator. The synchronization flag may be set to a first value (e.g., binary <NUM>, Boolean TRUE, etc.) where cells in a network are synchronous and set to a second value (e.g., binary <NUM>, Boolean FALSE, etc.) where cells in a network are not synchronous (e.g., maintain timing independently).

As discussed, by communicating neighbor cell timing information to a user equipment, the timing hypotheses needed for a UE to detect the PSS and SSS of a neighboring cell may be reduced. For example, the number of timing hypotheses may be reduced from hypotheses over a half frame (e.g., <NUM>,<NUM> timing hypotheses over a <NUM> millisecond time frame) to hypotheses over a number of symbols (e.g., <NUM> timing hypotheses over a duration of <NUM>-<NUM> symbols). Because a UE may need less time to detect a PSS and SSS of a neighboring cell, a UE may hand over to a neighboring cell faster, which may improve throughput (from reductions in failed transmissions and resulting retransmissions of data signals to a serving network entity over a weak connection), reduce power usage (from using a transmission power less than a maximum transmission power supported by a UE), and the like. Detection performance may further be improved when a list of cell identifiers is included, as a UE may have a priori knowledge of which cell IDs (and correspondingly, which PSSs and SSSs) to monitor for in detecting neighboring cells.

<FIG> shows a call flow diagram of example messages that may be exchanged between a UE <NUM>, a serving network entity <NUM>, and a neighbor network entity <NUM> to configure a UE to detect neighbor cells based on information provided about neighbor cell identities and timing and initiate a handover to the neighbor cells, according to certain embodiments. As illustrated, a UE <NUM> may receive a configuration message <NUM> from a serving network entity <NUM> (e.g., a serving cell, serving gNB, etc.). Configuration message <NUM> generally includes information that may allow a UE to quickly identify neighboring cells. This information, as discussed, may include cell identity information (e.g., a physical cell identifier (PCI)) for each of a plurality of neighboring cells and cell timing information used by each of the plurality of neighboring cells to transmit synchronization signals (e.g., PSS and SSS).

Subsequent to being configured with information about the neighboring cells via configuration message <NUM>, UE <NUM> can determine that a handover may be warranted (e.g., based on a signal strength metric measured for a connection between the UE <NUM> and the serving UE <NUM>, retransmission metrics, etc.) and, at block <NUM>, monitors for a PSS and SSS <NUM> transmitted by a neighboring network entity <NUM>. The UE may monitor for the PSS/SSS <NUM> using the information received via configuration message <NUM>. For example, the UE may monitor for PSS/SSS <NUM> that is associated with one of the cell identifiers (e.g., PCIs) included in the configuration information based on the timing information included in the configuration message <NUM>. The timing information may indicate, for example, a timing offset for detecting PSS/SSS from neighboring cells relative to PSS/SSS timing for a serving cell, an absolute timing for detecting PSS/SSS from neighboring cells (e.g., based on a common timing mechanism, such as timing from one or more satellite positioning systems, such as NAVSTAR GPS, GALILEO, GLONASS, or the like).

After detecting one or more neighboring cells and performing measurements with respect to the detected one or more neighboring cells at block <NUM>, the UE <NUM> may generate a measurement report <NUM> including measurements of signals detected from the one or more neighboring cells. The one or more neighboring cells may include, for example, a subset of neighboring cells identified in the configuration information having a highest received signal strength or other signal quality metric. In some embodiments, the measurement report may include measurements for one or more detected neighboring cells having a signal strength or signal quality metric over a threshold value. The UE may transmit the measurement report <NUM> to a serving network entity <NUM> to initiate a handover from the serving network entity <NUM> to the neighbor network entity <NUM>.

The serving network entity <NUM>, after receiving measurement report <NUM> from UE <NUM>, may determine that a handover is warranted to a neighbor cell identified in the measurement report (e.g., to neighbor network entity <NUM>). Based on determining that a handover is warranted, the serving network entity <NUM> may transmit a handover request <NUM> to the neighbor network entity <NUM> and, in response, receive a handover response <NUM> indicating that the neighbor cell is ready to communicate with the UE <NUM>. The serving network entity <NUM> may transmit a handover trigger <NUM> to UE <NUM> to indicate that the UE is to synchronize and begin communications with the neighbor network entity <NUM>. After synchronization, the UE <NUM> and the neighbor network entity <NUM> may perform communications <NUM> of uplink and/or downlink data between the UE <NUM> and the neighbor network entity <NUM>.

<FIG> illustrate detection probability of neighboring cells based on blind detection, a list of neighboring cell identifiers, and a list of neighboring cell identifiers and timing information.

In <FIG>, a serving network entity to which a UE is connected may have two neighboring cells. As illustrated in detection probability graph 600A, over eight half frames (HFs) with a HF duration of <NUM> milliseconds, covering a <NUM> millisecond duration, a UE may have a probability of detecting the two neighboring cells of less than <NUM> (i.e., a less than <NUM>% chance of detecting the two neighboring cells) below a signal-to-noise ratio (SNR) of -10dB. At an SNR of -10dB, the UE has a probability of over <NUM> of detecting both neighboring cells. At an SNR of -8dB, the probability of detecting both neighboring cells increases to just under <NUM>, and probability of detecting both neighboring cells reaches <NUM> at an SNR of -<NUM>.

As illustrated, the probability of detecting the two neighbor cells over eight HFs when a UE is configured with information about neighboring cell IDs is less than <NUM> at SNRs of -14dB or less. At an SNR of -12dB, the UE as a probability of detecting both neighboring cell IDs is over <NUM>, which is significantly higher than the probability of discovering both neighboring cell IDs using blind detection. For an SNR of -<NUM>. 8dB or greater, the probability of detecting both neighboring cells exceeds <NUM>.

Further improvements in the probability of detecting the two neighbor cells over eight HFs may be increased if a UE receives information about the cell identifiers and timing information of the neighboring cells. As illustrated, at an SNR of -16dB, the probability of detecting both neighbor cells is over <NUM>, as opposed to the almost <NUM> probability of detecting both neighbor cells using blind detection or when a UE is aware of neighbor cell identifiers. At an SNR of -14dB, the probability of detecting both neighboring cells increases to over <NUM>, and at an SNR of -<NUM>. 6dB, the probability of detecting both neighboring cells increases to <NUM>. Thus, by communicating neighboring cell identifier and timing information to a UE, the UE has a probability of detecting both neighboring cells over <NUM> at an SNR that is 5dB weaker than the SNR at which the UE has a probability of detecting both neighboring cells of <NUM> using blind detection. Thus, in this example, a UE may experience a gain of about <NUM>. 5dB when the UE is configured with neighbor cell identifier information, and the UE may experience a gain of about 5dB when the UE is configured with both neighbor cell identifier information and neighbor cell timing information.

Improvements in the probability of detecting both neighboring cells over <NUM> HFs may also be seen in <FIG>. As illustrated, using blind detection, the probability of detecting both neighboring cells using blind detection is over <NUM> at an SNR of about - <NUM>. In contrast, where a UE is configured with neighbor cell identifier information or neighbor cell identifier information and neighbor cell timing information is over <NUM> at an SNR of under -16dB. For example, where a UE is configured with neighbor cell identifier information, the probability of detecting both neighbor cells reaches <NUM> at an SNR of -<NUM>. 4dB, and where a UE is configured with both a list of neighbor cell identifiers and neighbor cell timing information, the probability of detecting both neighbor cells reaches <NUM> at an SNR of -<NUM>. Thus, in this example, by configuring a UE with neighbor cell identifier information, a gain of almost 4dB may be experienced, and by configuring a UE with neighbor cell identifier information and neighbor cell timing information, a gain of almost 5dB may be experienced.

<FIG> illustrates a situation in which a UE has four neighboring cells to detect. As illustrated in detection probability graph 600B, over a period of <NUM> HFs, a UE using blind detection may have a probability of less than <NUM> of detecting all four neighboring cells up to an SNR of roughly -9dB. A probability of <NUM> of detecting all four neighboring cells using blind detection over a period of 8HFs is reached at an SNR of - <NUM>.

In contrast, if a UE is configured with information about the cell identifiers of the four neighboring cells, over a period of <NUM> HFs, the UE has a probability of detecting all four neighboring cells of less than <NUM> up to an SNR of roughly -12dB. The probability of detecting all four neighboring cells reaches <NUM> at an SNR of -<NUM>. If a UE is configured with information about both the cell identifiers of the four neighboring cells and cell timing information for the four neighboring cells, the UE has a probability of detecting all four neighboring cells of less than <NUM> up to an SNR of roughly -14dB. The probability of detecting all four neighboring cells when a UE is configured with information about both the cell identifiers of the four neighboring cells and cell timing information for the four neighboring cells reaches <NUM> at an SNR of -<NUM>. Thus, in this example, a UE may experience a gain of about <NUM>. 4dB when a UE is configured with neighbor cell identifier information and a gain of about <NUM>. 3dB when a UE is configured with neighbor cell identifier information and neighbor cell timing information.

Improvements in the SNR needed to detect all four neighboring cells may also be seen in detection over a period of <NUM> HFs (e.g., over <NUM> milliseconds for a <NUM> millisecond HF duration). As illustrated, using blind detection, the probability of a UE detecting all four neighboring cells is less than <NUM> up to an SNR of roughly -13dB. The probability of the UE detecting all four neighboring cells using blind detection reaches <NUM> at an SNR of -<NUM>. When a UE is configured with cell identifier information, over a period of <NUM> HFs, the probability of detecting all four neighboring cells is less than <NUM> up to an SNR of roughly -16dB. The probably of detecting all four neighboring cells reaches <NUM> at an SNR of -<NUM>. Finally, when a UE is configured with cell identifier information and cell timing information, the probability of the UE detecting all four neighboring cells is less than <NUM> up to an SNR of roughly -17dB. The probability of detecting all four neighboring cells when a UE is configured with cell identifier information and cell timing information reaches <NUM> at an SNR of -<NUM>. Thus, cell detection over four neighboring cells may experience a gain of about 3dB when a UE is configured with cell identifier information and a gain of about 4dB when a UE is configured with cell identifier information and cell timing information.

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 instructions (e.g., computer-executable code) that when executed by the processor <NUM>, cause the processor <NUM> to perform the operations illustrated in FIG. <NUM>, or other operations for recovering a sidelink communication that is missed by a wireless node due to the wireless node transmitting while the sidelink communication is occurring. In certain aspects, computer-readable medium/memory <NUM> stores code <NUM> for receiving, from a network entity, cell information for neighbor cells; code <NUM> for searching for synchronization signals from the neighbor cells based on the cell information; code <NUM> for identifying, based on the synchronization signals from the neighbor cells, one of the neighbor cells to perform a handover to; and code <NUM> for initiating a handover from a serving cell to the identified one of the neighbor cells. In certain aspects, the processor <NUM> has circuitry configured to implement the code stored in the computer-readable medium/memory <NUM>. The processor <NUM> includes circuitry <NUM> for receiving, from a network entity, cell information for neighbor cells; circuitry <NUM> for searching for synchronization signals from the neighbor cells based on the cell information; circuitry <NUM> for identifying, based on the synchronization signals, from the neighbor cells, one of the neighbor cells to perform a handover to; and circuitry <NUM> for initiating a handover from a serving cell to the identified one of the neighbor cells.

Clause <NUM>: A method for wireless communications by a user equipment, comprising: receiving, from a network entity, cell information for neighbor cells; searching for synchronization symbols from the neighbor cells based on the cell information; based on the synchronization symbols from the neighbor cells, identifying one of the neighbor cells to perform a handover to; and initiating a handover from a serving cell to the identified one of the neighbor cells.

Clause <NUM>: The method of Clause <NUM>, wherein the cell information comprises a list of cell identifiers for a subset of neighbor cells operating in intra or inter frequency bands relative to a frequency band on which the serving cell is operating.

Clause <NUM>: The method of any one of Clauses <NUM> or <NUM>, wherein the cell information comprises time synchronization information for each of the neighbor cells.

Clause <NUM>: The method of Clause <NUM>, wherein the time synchronization information comprises time offset information measured in a number of slots.

Clause <NUM>: The method of Clause <NUM>, wherein the time synchronization information comprises time offset information measured in a number of subframes.

Clause <NUM>: The method of Clause <NUM>, wherein the time synchronization information comprises a flag indicating that the neighbor cells are synchronized.

Clause <NUM>: The method of any one of Clauses <NUM> through <NUM>, wherein the cell information for the neighbor cells is received from a network entity supporting communications with the UE using enhanced coverage.

Clause <NUM>: A system, comprising: a memory having executable instructions stored thereon; and a processor configured to execute the executable instructions to cause the system to perform the operations of any one of Clauses <NUM> through <NUM>.

Clause <NUM>: A system, comprising: means for performing the operations of any one of Clauses <NUM> through <NUM>.

Clause <NUM>: A computer-readable medium having instructions stored thereon which, when executed by a processor, performs the operations of any one of Clauses <NUM> through <NUM>.

The techniques described herein may be used for various wireless communication technologies, such as NR (for example, <NUM> NR), 3GPP Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks.

For clarity, while aspects may be described herein using terminology commonly associated with <NUM>, <NUM>, or <NUM> wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

In 3GPP, the term "cell" can refer to a coverage area of a Node B (NB) or a NB subsystem serving this coverage area, depending on the context in which the term is used. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, or other types of cells. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having an association with the femto cell (for example, UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.).

As discussed, by configuring a UE with neighboring cell identifier information and/or neighboring cell timing information, detection performance for neighboring cells may be improved. A smaller number of timing and/or frequency hypotheses may be needed to detect neighboring cells. Further, the probability of false alarms (e.g., false detections of neighboring cells) may be reduced.

Configuring a UE with neighboring cell identifier information and/or neighboring cell timing information may reduce an amount of delay imposed in handing over from a serving cell to a neighboring cell, as a UE may take less time to identify neighboring cells that are potential handover candidates. A shorter time period (e.g., fewer HFs) may be needed for a UE to detect neighboring cells when a UE is configured with neighboring cell identifier information and/or neighboring cell timing information relative to an amount of time needed for a UE to blindly detect neighboring cells. In high SNR environments, a UE configured with neighboring cell identifier information and/or neighboring cell timing information may detect neighboring cells in a shorter amount of time (e.g., <NUM> milliseconds) than would be needed to detect neighboring cells using blind detection. In connected mode and using blind detection, a single <NUM> millisecond gap may be dedicated for a single layer for collecting PSS/SSS samples; however, when a UE is configured with neighboring cell identifier and/or neighboring cell timing information, a single timing gap may be used to detect neighboring cells on multiple frequency layers utilizing the timing information and timing offsets between different frequency layers.

Configuring a UE with neighboring cell identifier information and/or neighboring cell timing information may also reduce an amount of power used by a UE. in idle mode, search and measurement of neighbor cells may occur after power-on, and PSS/SSS sample capturing and post-processing may affect the amount of time that a UE can be in a sleep or low power mode. For example, a UE may be awake for at least <NUM> milliseconds plus an additional amount of time needed to process detected PSSs/SSSs, and for enhanced coverage UEs (e.g., MTC/eMTC UEs), additional time may be needed to detect neighboring cells due to low SNR of received signals from the neighboring cells. When a UE is configured with neighboring cell identifier information and/or neighboring cell timing information, searching for neighboring cells may be a less time intensive process (e.g., taking <NUM> milliseconds plus a processing overhead time to detect neighboring cells), as a UE may not need to sample as many time/frequency combinations to detect PSSs/SSSs and process the received signals. Improvements may be increased in low SNR environments and for enhanced coverage UEs, where a UE may not need to monitor as many HFs for PSSs/SSSs from neighboring cells.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (for example, a smart ring, a smart bracelet, etc.), an entertainment device (for example, a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (for example, remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link.

Some wireless networks (for example, LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. For example, a subband may cover <NUM> (for example, <NUM> RBs), and there may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using time division duplexing (TDD). A subframe contains a variable number of slots (for example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>,.

A scheduling entity (for example, a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (for example, one or more other UEs), and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, or in a mesh network.

As used herein, the term "determining" may encompass one or more of a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, looking up (for example, looking up in a table, a database or another data structure), assuming and the like. Also, "determining" may include receiving (for example, receiving information), accessing (for example, accessing data in a memory) and the like.

As used herein, "or" is used intended to be interpreted in the inclusive sense, unless otherwise explicitly indicated. For example, "a or b" may include a only, b only, or a combination of a and b. As used herein, a phrase referring to "at least one of" or "one or more of" a list of items refers to any combination of those items, including single members. For example, "at least one of: a, b, or c" is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.

Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Claim 1:
A method for wireless communications performed by a user equipment (<NUM>), comprising:
receiving (<NUM>), from a network entity, cell information for neighbor cells (<NUM>), wherein the cell information comprises a list of cell identifiers for a subset of neighbor cells (<NUM>) operating in intra or inter frequency bands relative to a frequency band on which a serving cell (<NUM>) is operating and time synchronization information for the neighbor cells (<NUM>);
searching (<NUM>) for synchronization symbols from the neighbor cells (<NUM>) based on the cell information;
based on the synchronization symbols from the neighbor cells (<NUM>), identifying (<NUM>) one of the neighbor cells (<NUM>) to perform a handover to; and
initiating (<NUM>) a handover from the serving cell (<NUM>) to the identified one of the neighbor cells (<NUM>).