CELL RESELECTION EVALUATION BASED ON A LOW-RECEPTION-POWER SIGNAL

Methods and apparatuses for a cell reselection evaluation based on a low-reception-power signal in a wireless communication system. A method of a UE comprises: receiving first configuration information including an identification (ID) of at least one cell capable of using low-power (LP) signals and second configuration information including a set of threshold parameters for a cell reselection operation using the LP signals; performing, based on the first configuration information, a measurement operation on the LP signals; and performing, based on the set of threshold parameters and a measurement result of the measurement operation, the cell reselection operation.

TECHNICAL FIELD

The present disclosure relates generally to wireless communication systems and, more specifically, the present disclosure relates to a cell reselection evaluation based on a low-reception-power signal in a wireless communication system.

BACKGROUND

SUMMARY

The present disclosure relates to wireless communication systems and, more specifically, the present disclosure relates to a cell reselection evaluation based on a low-reception-power signal in a wireless communication system.

In one embodiment, a user equipment (UE) in a wireless communication system is provided. The UE comprises a transceiver configured to receive first configuration information including an identification (ID) of at least one cell capable of using low-power (LP) signals and second configuration information including a set of threshold parameters for a cell reselection operation using LP signals. The UE further comprises a processor operably coupled to the transceiver, the processor configured to: perform, based on the first configuration information, a measurement operation on the LP signals, and perform, based on the set of threshold parameters and a measurement result of the measurement operation, the cell reselection operation.

In another embodiment, a method of a UE in a wireless communication system is provided. The method comprises: receiving first configuration information including an ID of at least one cell capable of using LP signals and second configuration information including a set of threshold parameters for a cell reselection operation using the LP signals; performing, based on the first configuration information, a measurement operation on the LP signals; and performing, based on the set of threshold parameters and a measurement result of the measurement operation, the cell reselection operation.

In yet another embodiment, a base station (BS) in a wireless communication system is provided. The BS comprises a processor configured to generate first configuration information including an ID of at least one cell capable of using LP signals and second configuration information including a set of threshold parameters for a cell reselection operation using the LP signals. The BS further comprises a transceiver operably coupled to the processor, the transceiver configured to transmit, to a UE, the first configuration information and the second configuration information, wherein: a measurement operation on the LP signals is performed based on the first configuration information, and the cell reselection operation is performed based on the set of threshold parameters and a measurement result of the measurement operation.

DETAILED DESCRIPTION

The following documents are hereby incorporated by reference into the present disclosure as if fully set forth herein: “3GPP, TS 38.300 v17.3.0, 5G; NR; NR and NG-RAN Overall Description; Stage2”; “3GPP, TS 38.331 v17.3.0, 5G; NR; Radio Resource Control (RRC); Protocol specification”; and “3GPP, TS 38.304 v17.3.0, NR; User Equipment (UE) procedures in Idle mode and RRC Inactive state.”

As described in more detail below, one or more of the UEs111-116include circuitry, programing, or a combination thereof, for supporting a cell reselection evaluation based on a low-reception-power signal in a wireless communication system. In certain embodiments, and one or more of the gNBs101-103includes circuitry, programing, or a combination thereof, for supporting a cell reselection evaluation based on a low-reception-power signal in a wireless communication system.

The controller/processor225is also capable of executing programs and other processes resident in the memory230, such as an OS. The controller/processor225can move data into or out of the memory230as required by an executing process. The controller/processor225is also capable of executing programs and other processes resident in the memory230, such as processes for supporting a cell reselection evaluation based on a low-reception-power signal in a wireless communication system.

The transceiver(s)310receives from the antenna305, an incoming RF signal transmitted by a gNB of the network100. The transceiver(s)310down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by RX processing circuitry in the transceiver(s)310and/or processor340, which generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuitry sends the processed baseband signal to the speaker330(such as for voice data) or is processed by the processor340(such as for web browsing data).

FIG.4andFIG.5illustrate example wireless transmit and receive paths according to this disclosure. In the following description, a transmit path400may be described as being implemented in a gNB (such as the gNB102), while a receive path500may be described as being implemented in a UE (such as a UE116). However, it may be understood that the receive path500can be implemented in a gNB and that the transmit path400can be implemented in a UE. In some embodiments, the receive path500is configured to support a cell reselection evaluation based on a low-reception-power signal in a wireless communication system.

As illustrated inFIG.4, the channel coding and modulation block405receives a set of information bits, applies coding (such as a low-density parity check (LDPC) coding), and modulates the input bits (such as with quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency-domain modulation symbols.

The serial-to-parallel block410converts (such as de-multiplexes) the serial modulated symbols to parallel data in order to generate N parallel symbol streams, where N is the IFFT/FFT size used in the gNB102and the UE116. The size N IFFT block415performs an IFFT operation on the N parallel symbol streams to generate time-domain output signals. The parallel-to-serial block420converts (such as multiplexes) the parallel time-domain output symbols from the size N IFFT block415in order to generate a serial time-domain signal. The add cyclic prefix block425inserts a cyclic prefix to the time-domain signal. The up-converter430modulates (such as up-converts) the output of the add cyclic prefix block425to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to the RF frequency.

A transmitted RF signal from the gNB102arrives at the UE116after passing through the wireless channel, and reverse operations to those at the gNB102are performed at the UE116.

The 3GPP has developed technical specifications and standards to define the new 5G radio-access technology, known as 5G new radio (NR). UE energy efficiency is critical to 5G system design, especially for small form-factor devices without continuous energy source, e.g., IoT devices, industrial sensors, controllers, and wearables. To save UE power consumption, extended discontinuous reception (eDRX) with long wake-up periods is expected to be used. However, large eDRX cycles cannot meet the low latency requirement for latency-critical use cases. On the other hand, the UE needs to periodically wake up per eDRX cycle even there is no signaling or data traffic, which may waste power. It is desired that the UE can wake up with short delay, while only at triggered occasions. To this end, a wake-up signal (WUS) to trigger the main radio (MR) is to be designed and a separate receiver, namely, lower power radio (LR), which has the ability to monitor wake-up signal with ultra-low power consumption is expected to be used. Main radio works for data transmission and reception, which can be turned off or set to deep sleep unless the main radio is turned on.

In an RRC_IDLE/INACTIVE state, a UE can monitor a type of signal with low reception power (e.g., lower-power wake-up signal (LP WUS)) to reduce power consumption. To enable UE-controlled mobility in the RRC_IDLE/INACTIVE state, the UE needs to perform neighbor cell measurements and cell (re-)selection based on a low-reception-power signal, instead of SSB as in legacy operation. Thus, the criteria for cell reselection evaluation based on the low-reception-power signal needs to be designed.

In the present disclosure, the procedure and the criteria for cell reselection evaluation based on measurements of a type of low-reception-power signal are specified. Embodiments covers inter-frequency, and/or inter-frequency and/or inter-RAT cell reselection evaluation. In one instance, the terminology LP WUS can refer to a type of signal received by low power receiver with low power and can be replaced by equivalent terminology such as low power synchronization signal (LP SS). In one example, a UE in RRC_CONNECTED state monitors LP WUS.

For a UE operation with lower power consumption in an RRC_IDLE/INACTIVE state, a UE can perform a cell reselection based on LP WUS. The UE can perform neighbor cell measurement of LP WUS while monitoring the serving cell's LP WUS. One embodiment of LP WUS based cell reselection procedure is illustrated inFIG.6.

FIG.6illustrates a flowchart of a UE method600for a cell reselection based on LP WUS according to embodiments of the present disclosure. The method600as may be performed by a UE (e.g.,111-116as illustrated inFIG.1). An embodiment of the method600shown inFIG.6is for illustration only. One or more of the components illustrated inFIG.6can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.

As illustrated inFIG.6, at step602, the UE receives LP WUS based cell reselection configuration. The configuration can include at least one of frequency band lists for LP WUS measurement, neighbor cell lists for LP WUS measurement, LP WUS measurement timing configuration, frequency priorities and parameters for LP WUS measurement evaluation, or cell access restriction information. The configuration or part of the configuration can be provided in system information, and/or in the RRCRelease message, and/or by inheriting from another RAT.

At step604, the UE starts to measure LP WUS of neighbor cells according to the measurement timing configuration on at least one of the intra-frequency band (i.e., the serving cell frequency), inter-frequency bands, or inter-RAT frequency bands. The UE can start to measure neighbor cells when the current serving cell is not in good radio condition.

At step606, the UE evaluates the neighbor cells by applying the frequency priorities and the parameters for cell reselection evaluation based on LP WUS, and reselects a cell based on the evaluation result. At step608, the UE checks the cell access restriction information for the selected cell. At step610, the UE camps on the selected cell if not restricted/barred/reserved. If the selected cell is restricted/barred/reserved, the UE excludes the cell, and considers other neighbor cells in cell reselection evaluation at step606.

For step602, in one embodiment, the some of the LP WUS based cell reselection configuration can be provided per frequency band, while some can be provided commonly for a list of frequency bands. For one frequency band, either the intra-frequency band (i.e., the frequency band of the serving cell) or an inter-(RAT) frequency band, the configuration can include one or multiple of the following elements as shown in examples.

In one example, the configuration can include a carrier frequency of LP WUS from neighbor cells on this frequency band.

In one example, the configuration can include an indication of whether LP WUS is supported on an existing frequency for cell reselection.

In one example, the configuration can include a priority of the frequency band for LP WUS based cell reselection.

In one example, the configuration can include a list of frequencies for which the LP WUS based cell reselection parameters indicated for this frequency band apply.

In one example, the configuration can include a LP WUS measurement timing configuration (LMTC), indicating the timing occasions at which the UE measures one or more LP WUS quantities. The LMTC can include at least one of a duration, a periodicity, or an offset to indicate the measurement window in which to receive LP WUS, and/or the indexes of subframes and/or slots and/or impulses of LP WUS in a measurement window to measure a specific quantity, and/or a list of cell IDs (e.g., PCIs) that indicates the cells following this timing configuration.

In one example, the configuration can include a number of LP WUS impulses to be used to derive a measurement quantity, for which, as an example, a linear average of a measurement quantity is derived from the number of LP WUS impulses.

In one example, the configuration can include a threshold to be used to derive a LP WUS measurement quantity, for which, as an example, only the LP WUS impulse above the threshold is used to derive a measurement quantity.

In one example, the configuration can include a list of thresholds, offsets for LP WUS based cell reselection evaluation on this frequency.

In one example, the configuration can include a list of cell IDs (e.g., PCIs) that indicates the neighbor cells providing LP WUS on this frequency band.

In one example, the configuration can include a list of cell IDs (e.g., PCIs) that indicates the neighbor cells on this frequency band allowing camping through LP WUS based cell reselection.

In one example, the configuration can include a list of cell IDs (e.g., PCIs) that indicates the neighbor cells on this frequency band to be excluded for LP WUS based cell reselection.

In one example, the configuration can include a list of neighbor cells, where each entry of the list includes a cell ID (e.g., PCIs) and cell-specific information elements, where the elements can include one or more of the followings: (1) PLMN related information for the neighbor cell, which can include an index referring to a configured PLMN ID and the corresponding PLMN related information, a PLMN identity, one or more tracking area codes, one or more RAN area codes, a cell ID, a gNB ID, and a cell reserved state; (2) assistance information to acquire MIB and SIB1 of the neighbor cell, which can include the frequency, time, spatial resource location to acquire MIB and SIB1; and (3) cell-specific thresholds and offsets for cell reselection evaluation based on LP WUS.

For step604, in an embodiment, the UE can measure LP WUS of intra-frequency, and/or inter-frequency, and/or inter-RAT frequency neighbor cells. Regarding the frequencies and/or the neighbor cells to be measured, the UE can measure LP WUS of neighbor cells on an inter-(RAT) frequency band for which the carrier frequencies and/or frequency bands are indicated supporting LP WUS in the LP WUS based cell reselection configuration. If frequencies for LP WUS are not provided, the UE can scan the frequencies for cell reselection based on existing reference signals (e.g., SSB). If the list of cell IDs for neighbor cells providing LP WUS is present, the UE measures the listed neighbor cells on the corresponding frequency. If the list of cell IDs for neighbor cells allowing camping through LP WUS based cell reselection is present, the UE measures the listed neighbor cells on the corresponding frequency. If the list of cell IDs for neighbor cells to be excluded for LP WUS based cell reselection is present, the UE ignores the listed neighbor cells on the corresponding frequency for cell reselection measurement. If none of LP-WUS-specific cell lists is present, the UE can follow the existing cell lists configured for cell reselection based on existing reference signals (e.g., SSB). If cell-specific information for a list of neighbor cells is present, the UE can measure the indicated neighbor cells on the corresponding frequency.

In another embodiment for step604, regarding the measurement timing of neighbor cells, one or multiple LP WUS measurement timing configurations can be provided for neighbor cells on a frequency. If the LP WUS measurement timing configuration (LMTC) for a frequency is absent, the UE can follow the existing SSB measurement timing configuration (SMTC) configured for the same frequency to receive and measure LP WUS of neighbor cells. If the LP WUS measurement timing configuration for a frequency is present, the UE setups the LP WUS measurement timing configuration in accordance with the received parameters, including periodicity, and/or offset, and/or duration. If a cell list is included in the LMTC, for the cells indicated in the list, the UE applies the LTMC to receive and measure LP WUS. If any of periodicity, offset, and duration is not present in LMTC, the UE uses the corresponding parameter indicated in the SMTC configured for the same frequency/cell. For instance, LMTC includes only an offset parameter for a certain frequency/cell, then the UE can follow the periodicity and the duration in the SMTC configured for the same frequency/cell. In one example, the LMTC parameters (e.g., periodicity, and/or offset, and/or duration) can be indicated in subframes and/or in slots explicitly.

Alternatively, the LMTC parameters (e.g., periodicity, and/or offset, and/or duration) can be indicated based on the SMTC parameters for the same frequency/cell. For example, the periodicity/offset/duration in LMTC can be an integer multiple or a fraction of the periodicity/offset/duration in SMTC for the same frequency/cell, where a scalar is used to indicate the integer multiple or the fraction. The UE can identify the LP WUS measurement window by the SFN and/or the subframe derived as follows. SFN mod T=(FLOOR (offset/10)), where T=CEIL(periodicity/10); if the periodicity is larger than sf5, subframe=offset mod 10; else, subframe=offset or (offset+5), where the periodicity and offset are indicated in subframes.

In one more embodiment for step604, for the measurement quantities, one or more measurement quantities defined for LP WUS (e.g., RSRP, RSRQ, RSSI, SINR, RSARP) can be measured by the UE. The UE can measure a quantity of LP WUS at specific timing within the measurement window if the measurement timing for the quantity is configured. The timing information can be provided by indications of subframes, and/or slots, and/or impulses. For example, the indexes of the subframes, and/or slots, and/or impulses in a measurement window can be indicated to measure a specific quantity.

In yet another embodiment for step604, to consolidate the measurement result, if the number of LP WUS impulses to be used to derive a measurement quantity is indicated, the UE measures the indicated number of LP WUS impulses to derive the corresponding quantity. The UE can derive the quantity by averaging the measured number of LP WUS impulses. In another example, if one or more thresholds to be used to derive a LP WUS measurement quantity is indicated, the UE can use the LP WUS impulses above the minimum threshold to derive a quantity.

For step606, when performing cell reselection evaluation based on LP WUS measurement, frequency priorities can be used for evaluation. In one embodiment, if the priority of a frequency for LP WUS based cell reselection is configured, the UE performs cell reselection evaluation for the frequencies whose priority is indicated and follows the indicated LP WUS based frequency priority; if the frequency priority for LP WUS based cell reselection is absent and the frequency priority for cell reselection evaluation based on existing reference signals (e.g., SSB) is present, the UE can follow the existing frequency priority. If the neither the LP WUS based priority nor the SSB-based priority for a frequency is present, the UE excludes the frequency for cell reselection evaluation.

In another embodiment for step606, to determine the neighbor cells to be evaluated, if the list of cell IDs indicating neighbor cells providing LP WUS is present, the UE performs cell reselection evaluation for the indicated neighbor cells on the corresponding frequency. If the list of cell IDs indicating neighbor cells allowing camping through LP WUS based cell reselection is present, the UE performs cell reselection evaluation for the indicated neighbor cells on the corresponding frequency. If the list of cell IDs indicating neighbor cells to be excluded for LP WUS based cell reselection is present, the UE excludes the indicated neighbor cells on the corresponding frequency for cell reselection evaluation. If cell-specific information (e.g., parameters for cell reselection evaluation) of a list of neighbor cells is present, the UE performs cell reselection evaluation for the indicated neighbor cells on the corresponding frequency.

In one embodiment for step606, regarding cell reselection criteria, the UE performs cell reselection evaluation following the existing intra-frequency, and/or inter-frequency, and/or inter-RAT frequency cell reselection criteria. When applying the existing criteria for LP WUS based cell reselection evaluation, in one example, the LP-WUS-specific parameters (e.g., thresholds, offsets) are used if configured; in another example, the UE derives a parameter value by altering the value of an existing parameter (e.g., thresholds and/or offsets for SSB based cell reselection) by an offset, where the offset is configured for LP-WUS based cell reselection evaluation.

In another embodiment for step606, the UE evaluates the inter-frequency cells following the criteria specified for LP WUS based cell reselection. Given the absolute priorities of frequencies, the UE performs cell reselection evaluation and attempts to camp on a cell on the highest priority frequency available. The example for evaluation criteria of inter-(RAT) frequencies are specified as follows.

For a NR frequency or inter-RAT frequency that has a higher priority than the serving cell frequency: (1) if the relevant parameters are provided and the UE has camped on the current serving cell for more than a certain duration (e.g., 1 second), the UE performs cell reselection to a cell on the higher priority frequency if Quantity-1 of the cell satisfies ConditionHigh-1 during a cell reselection time interval, where the relevant parameters are applied in ConditionHigh-1; and (2) otherwise (i.e., the relevant parameters are absent), if the UE has camped on the current serving cell for more than a certain duration (e.g., 1 second), the UE performs cell reselection to a cell on the higher priority frequency if Quantity-2 of the cell satisfies ConditionHigh-2 during a cell reselection time interval.

In one example, Quantity-1 and Quantity-2 can be the same or different quantities, e.g., RSRP, RSRQ, RSSI, SINR, RSARP. Quantity-1 and Quantity-2 can be derived based on pre-defined rules applying the configured thresholds and offsets for inter-(RAT) frequency cell reselection evaluation based on LP WUS. For example, Quantity-1 can be SqualLPWUSwhich is the LP WUS quality level value, and Quantity-2 can be SrxlevLPWUSwhich is the LP WUS received level value. SqualLPWUSand SrxlevLPWUScan be derived as follows, respectively, as shown in TABLE 1.

In one example, ConditionHigh-1 can be that Quantity-1 of a cell on a higher priority frequency is larger or smaller than a threshold, and ConditionHigh-2 can be that Quantity-2 of a cell on a higher priority frequency is larger or smaller than another threshold. For example, for SqualLPWUSand SrxlevLPWUS, ConditionHigh-1 and ConditionHigh-2 can be as follows, respectively, as shown in TABLE 2.

TABLE 2SqualLPWUSand SrxlevLPWUS-SqualLPWUS> ThreshHighQLPWUS, where ThreshHighQLPWUSis a threshold of LP WUSquality level to be applied for reselecting a cell on a higher priority frequency;-SrxlevLPWUS> ThreshHighPLPWUS, where ThreshHighPLPWUSis a threshold of LP WUSreceived level to be applied for reselecting a cell on a higher priority frequency.

In one example, the cell reselection time interval can be LP-WUS specific; alternatively, the UE can follow the time interval for cell reselection based on existing reference signals (e.g., SSB) if LP-WUS-specific value is not provided. In another example, a duration offset can be indicated, and the UE derive the LP-WUS specific cell reselection time interval by altering the existing time interval by the indicated duration offset.

For a NR frequency or inter-RAT frequency that has a lower priority than the serving cell frequency, the UE evaluates the inter-frequency cells by applying the criteria specified for LP WUS based cell reselection as follows: (1) if the relevant parameters are provided and the UE has camped on the current serving cell for more than a certain duration (e.g., 1 second), the UE performs cell reselection to a cell on the lower priority frequency if Quantity-1 of the cell satisfies ConditionLowX-1 during a cell reselection time interval and Quantity-1 of the current serving cell satisfies ConditionLowServing-1, where the relevant parameters are applied in ConditionLowX-1 and ConditionLowServing-1; and (2) otherwise (i.e., the relevant parameters are absent), if the UE has camped on the current serving cell for more than a certain duration (e.g., 1 second), the UE performs cell reselection to a cell on the lower priority frequency if Quantity-2 of the cell satisfies ConditionLowX-2 during a cell reselection time interval and Quantity-2 of the current serving cell satisfies ConditionLowServing-2.

In one example, Quantity-1 and Quantity-2 can be the same or different quantities, e.g., RSRP, RSRQ, RSSI, SINR, RSARP. Quantity-1 and Quantity-2 can be derived based on pre-defined rules applying the configured thresholds and offsets for inter-(RAT) frequency cell reselection evaluation based on LP WUS. Examples for higher priority frequencies mentioned above that specify SqualLPWUSand SrxlevLPWUSfor Quantity-1 and Quantity-2 can be applied. In one example, ConditionLowX-1 can be Quantity-1 of a cell on a lower priority frequency is large or smaller than a threshold, ConditionLowServing-1 can be Quantity-1 of the current serving cell is large or smaller than another threshold, and ConditionLowX-2 can be Quantity-2 of a cell on a lower priority frequency is larger or smaller than one more threshold, ConditionLowServing-2 can be Quantity-2 of the current serving cell is larger or smaller than one another threshold.

In one example, for SqualLPWUSand SrxlevLPWUS, the conditions can be as follows, respectively, as shown in TABLE 3.

TABLE 3SqualLPWUSand SrxlevLPWUS-ConditionLowX-1: SqualLPWUSof a cell on the lower priority frequency >ThreshLowQLPWUS, where ThreshLowQLPWUSis a threshold of LP WUS quality level tobe applied for reselecting a cell on a lower priority frequency;-ConditionLowX-2: SrxlevLPWUSof a cell on the lower priority frequency >ThreshLowPLPWUS, where ThreshLowPLPWUSis threshold of LP WUS received level tobe applied for reselecting a cell on a lower priority frequency.-ConditionLowServingX-1: SqualLPWUSof the current serving cell <ThreshLowServingQLPWUS, where ThreshLowServingQLPWUSis a threshold of LP WUSquality level to be applied on the serving cell for reselecting a cell on a lower priorityfrequency;-ConditionLowServing-2: SrxlevLPWUSof the current serving cell <ThreshLowServingPLPWUS, where ThreshLowServingPLPWUSis a threshold of LP WUSreceived level to be applied on the serving cell for reselecting a cell on a lower priorityfrequency.

In one example, the cell reselection time interval can be LP-WUS specific; alternatively, the UE can follow the time interval configured for SSB based cell reselection, if LP WUS specific value is not provided. In another example, a duration offset can be indicated, and the UE derive the LP-WUS specific cell reselection time interval by altering the existing cell reselection time interval by the indicated duration offset.

In yet another embodiment of step606, for intra-frequency and equal priority inter-frequency neighbor cells, or for inter-frequency bands that more than one cells meets the above criteria for the inter-frequency with higher/lower priorities, the UE performs evaluation by applying the cell-ranking criteria specified for LP WUS based cell reselection and reselects a cell.

In one example, to determine the cells to be ranked, the UE first excludes neighbor cells which does not meet the minimum requirement. The minimum requirement can be that one or more measurement quantities (e.g., RSRP, RSRQ, SINR, RSSI, RSARP) of a neighbor cell are larger than the minimum thresholds, e.g., the S criteria: SqualLPWUS>0, SrxlevLPWUS>0, where SqualLPWUSand SrxlevLPWUSare defined as aforementioned. The UE can use the cell-specific parameters (e.g., thresholds, offsets), if provided, to check the minimum requirement.

As an example of cell ranking, for the cells to be ranked, the UE derives an R value for each cell so that the cell with a larger R value has a higher rank, and the UE reselects the highest ranked cell. One way to derive the R value is as follows, as shown in TABLE 4.

TABLE 4Cell ranking-For the current serving cell, Rs = QservmeasLPWUS+QhystLPWUS− QoffsettempLPWUS,where∘QservmeasLPWUSis the serving cell measurement quantity of LP WUS (e.g.,RSRP, RSRQ, SINR, RSSI, RSARP);∘QhystLPWUSis a hysteresis value for cell ranking based on LP WUS;∘QoffsettempLPWUSis an offset temporarily applied to LP WUS measurement.-For a neighbor cell, Rn = QneighmeasLPWUS−QoffsetLPWUS− QoffsettempLPWUS, where∘QneighmeasLPWUSis the neighbor cell measurement quantity of LP WUS (e.g.,RSRP, RSRQ, SINR, RSSI, RSARP);∘QoffsetLPWUSis an offset taking into account the neighbor cell is intra-frequencyor inter-frequency;∘QoffsettempLPWUSis an offset temporarily applied to LP WUS measurement.

In another embodiment, if the UE measures LP WUS in multiple beams of a cell, the number of good beams for some high ranked cells can be considered. For example, the UE can reselect a cell which is ranked within a certain range to the highest rank (e.g., according to parameter RangeToBestCellLPWUSif configured) and has the largest number of beams that a measurement quantity of the beams is larger than a threshold (e.g., absThreshRankingLPWUS) if configured. In one example, the LP-WUS-specific parameter RangeToBestCellLPWUSand/or absThreshRankingLPWUScan be configured; alternatively, the existing parameters (e.g., rangeToBestCell and/or absThreshSS-BlocksConsolidation) for multi-beam SSB-based cell reselection can be used.

For step608, the UE checks the cell access restriction information for the selected cell. In one embodiment, if the cell access restriction information is broadcast in system information and received by the UE (e.g., step602), the UE can check accordingly. If the selected cell can be accessed according to the cell access restriction information, the UE camps on the selected cell (e.g., step610) or the UE further checks cell-specific access information for the selected cell; otherwise, the UE excludes the selected cell and considers other neighbor cells for evaluation and reselection (e.g., step412). In one example, if the list of cell IDs indicating neighbor cells allowing camping through LP WUS based cell reselection is present, the UE checks whether the selected cell is included in the allowed list. If not, the UE excludes the selected cell (e.g., step612) and considers other neighbor cells in the evaluation and reselection. If yes, the UE can further check the cell-specific access information (e.g., PLMN information, cell barred/reserved information).

For another example, if the list of cell IDs indicating neighbor cells to be excluded for LP WUS based cell reselection is present, the UE checks whether the selected cell is indicated to be excluded. If yes, the UE excludes the selected cell (e.g., step612) and considers other neighbor cells in the evaluation and reselection. If not, the UE can further the checks cell-specific access information.

In one embodiment of step608, the cell-specific access information is broadcast in system information for LP WUS based cell reselection. If the selected cell can be accessed according to the cell-specific access information, the UE camps on the selected cell (e.g., step610); otherwise, the UE excludes the selected cell and considers other neighbor cells for evaluation and reselection (e.g., step612). In one example, the cell-specific access information for a cell can include an index referring to a PLMN ID and the corresponding PLMN related information provided by the current serving cell. In another example, the cell-specific access information for a cell can directly include the PLMN identity, and/or closed access group (CAG) IDs, and/or one or more tracking area codes, and/or one or more RAN area codes, and/or a cell ID, and/or a gNB ID, and/or a cell barred/reserved state.

In one example, to camp on a suitable cell, the UE checks if the selected cell meets the access conditions, which can include one or more of the followings, as shown in TABLE 5.

TABL 5Determination the access condition-The cell is part of either the selected PLMN or the registered PLMN or a PLMN of theEquivalent PLMN list, and either∘the PLMN ID is not associated to any CAG-IDs and CAG-only indication isabsent or false; or∘the PLMN ID is associated to a CAG-ID which is indicated in the allowed CAGlist for the cell.-The cell is not barred for a UE operating with LP WUS.-The cell is part of at least one tracking area that is not part of the list of “ForbiddenTracking Areas for Roaming” which belongs to a PLMN that fulfils the PLMN relatedcondition above.-The cell is not reserved.

If the selected cell can be accessed by checking the cell access restriction information and cell-specific access information, it is considered as a suitable cell and the UE camps on the cell in a normal state.

In another embodiment, if the UE is currently camping on any cell state, the UE can reselect a cell based on the cell reselection evaluation (e.g., operation606), checks the selected the cell is not barred to the UE by using the provided cell access restriction information and/or cell-specific access information, and camps on any cell state.

When attempting to camp on the selected cell, in one embodiment of operation610, the UE can turn on the MR and acquire the MIB and/or SIB1 of the selected cell by applying the MIB/SIB1 acquisition assistance information if provided. The MIB/SIB1 acquisition assistance information can include the radio resource location information in frequency, time, or space domain for the UE to identify MIB/SIB1. For example, the time domain location can be indicated by SFN, and/or subframe, and/or slot number; the space domain location can be indicated by beam index, and/or QCL information, and/or SSB index.

FIG.7illustrates a flowchart of a UE method700for a cell reselection based on LP WUS and SSBs according to embodiments of the present disclosure. The method700as may be performed by a UE (e.g.,111-116as illustrated inFIG.1). An embodiment of the method700shown inFIG.7is for illustration only. One or more of the components illustrated inFIG.7can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.

In yet another embodiment as illustrated inFIG.7, the UE may receive the SSBs of the selected cell by the MR and acquire the MIB and/or SIB1 of the selected cell. As shown inFIG.7, the UE first receives LP WUS based cell reselection configuration using the MR, then starts to measure LP WUS from neighbor cells for cell reselection, performs cell reselection evaluation, and reselects a cell. The embodiments aforementioned for steps602,604,606,608can be applied to steps702,704,706. At step708, the UE receives SSBs of the selected cell by the MR and acquires MIB and/or SIB1 of the selected cell. At steps710,712, If the selected cell can be accessed according to the cell access information (e.g., PLMN related information, barring information) in SIB1, the UE camps on the cell; otherwise, the UE excludes the cell and continues to perform cell reselection evaluation based on LP WUS measurements, or SSB measurements, or both LP WUS and SSB measurements.

In one example, the UE searches and receives the SSBs of the selected cell by MR whenever the UE reselects a cell by LP WUS based cell reselection evaluation and attempts to camp on the selected cell. In another example, the UE searches and receives the SSBs of the selected cell with MR if the selected cell's cell access restriction information or cell-specific access information (e.g., PLMN information) or the MIB/SIB1 acquisition assistance information is absent in the current serving cell's system information. By receiving the SSBs of the selected cell and acquiring the MIB and SIB1, the UE can check the selected cell's cell access restriction information or cell-specific access information (e.g., PLMN information, barring information). In yet another example, the UE can be triggered to turn on MR by a certain cause, (e.g., system information update).

FIG.8illustrates a flowchart of a UE method800for a cell reselection evaluation based on a low-reception-power signal according to embodiments of the present disclosure. The method800as may be performed by a UE (e.g.,111-116as illustrated inFIG.1). An embodiment of the method800shown inFIG.8is for illustration only. One or more of the components illustrated inFIG.8can be implemented in specialized circuitry configured to perform the noted functions or one or more of the components can be implemented by one or more processors executing instructions to perform the noted functions.

As illustrated inFIG.8, the method800begins at step802. In step802, a UE receives first configuration information including an ID of at least one cell capable of using LP signals and second configuration information including a set of threshold parameters for a cell reselection operation using the LP signals.

In step802, the first configuration information further includes at least one of frequency information to communicate with the LP signals and LP signal measurement timing information including at least one of a periodicity, a duration, and a timing offset.

In step804, the second configuration information further includes at least one of a set of offset parameters for the cell reselection operation and cell access information.

In step804, the UE performs, based on the first configuration information, a measurement operation on the LP signals.

In step806, the UE performs, based on the set of threshold parameters and a measurement result of the measurement operation, the cell reselection operation.

In one embodiment, the UE performs the measurement operation for the LP signals over a frequency identified by the frequency information included in the first configuration information.

In one embodiment, the UE performs, based on the LP signal measurement timing information, the measurement operation for the LP signals.

In one embodiment, the UE obtains, based on the set of offset parameters, a set of parameter values of the LP signal for the cell reselection operation.

In one embodiment, the UE determines, based on the cell access information, a cell where the UE camps.

In one embodiment, the UE receives the LP signals, wherein the LP signal comprise an LP WUS or an LP SS.