Deriving the SSB index on the target cell

Abstract

Disclosed are methods, systems, and computer-readable media for performing operations including receiving, by a user equipment (UE), a message from a serving cell serving the UE, the message including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is authorized to use timing of a reference cell to derive an index of the target SSB burst, the target SSB burst including one or more SSBs; calculating a tolerance of frame boundary alignment between the reference cell and the target cell; and determining an index of the target SSB burst based on the tolerance.

Description

[Background technology]

[0001] Wireless communication networks provide an integrated communications platform and telecommunications services to wireless user devices. Exemplary telecommunications services include telephony, data (e.g., voice, audio, and / or video data), messaging, Internet access, and / or other services. Wireless communication networks have radio access nodes that exchange wireless signals with wireless user devices using radio network protocols such as those described in various telecommunications standards promulgated by the 3rd Generation Partnership Project (3GPP). Exemplary wireless communication networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal Frequency Division Multiple Access (OFDMA) networks, Long Term Evolution (LTE), and Fifth Generation New Wireless (5G NR). Wireless communication networks facilitate mobile broadband services using technologies such as OFDM, Multiple Input Multiple Output (MIMO), advanced channel coding, Massive MIMO, beamforming, and / or other features.

[0002] For some procedures in 5GNR, such as handover or component carrier (CC) addition, the user equipment (UE) is configured to measure signals from the UE's serving cell and / or from neighboring cells. 5GNR introduces cell signal measurement by using a synchronization signal block (SSB) that includes a synchronization signal (SS) and a physical broadcast channel (PBCH). The SS includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The PBCH includes a PBCH demodulation reference signal (DMRS) and PBCH data. The SSB is used for reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-interference-and-noise ratio (SINR) measurements. Summary of the Invention

[0003] The present disclosure describes a method and system for deriving an SSB index on a neighboring cell. In one example, the disclosed method and system can be used to derive an SSB index in a scenario where an inter-frequency target cell has a different SCS than a serving cell.

[0004] The present disclosure relates to a method, system, device, computer program, or combination thereof for deriving an SSB index on a target cell. According to one aspect of the present disclosure, a method implemented by a user equipment (UE) served by a serving cell includes receiving a message from the serving cell including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell, and (ii) a flag indicating that the UE is authorized to use a timing of a reference cell to derive an index of the target SSB burst, the target SSB burst including one or more SSBs, calculating a tolerance (Δt) of frame boundary alignment between the reference cell and the target cell, and determining an index of the target SSB burst based on the tolerance.

[0005] Other versions include corresponding systems, apparatus, and computer programs for performing the actions of the methods defined by instructions encoded on a computer-readable storage device. These and other versions may optionally include one or more of the following features.

[0006] In some implementations, the SSB information includes the frequency of the target SSB burst and the subcarrier spacing of the target SSB burst.

[0007] In some implementations, the method further includes measuring at least a portion of the target SSB burst during the measurement window based on at least one of the tolerance (Δt) or the SSB information.

[0008] In some implementations, measuring at least a portion of the target SSB burst based at least in part on the tolerance (Δt) or the SSB information comprises determining a time length of the measurement window:

number

[0009] In some implementations, determining an index of the target SSB burst includes determining a candidate position of a first SSB within the target SSB burst based on the tolerance, and determining an index of the target SSB burst based on at least one of the candidate position of the first SSB or a measured portion of the target SSB index.

[0010] In some implementations, calculating the tolerance (Δt) includes calculating the tolerance as Δt=min(2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell).

[0011] In some implementations, calculating the tolerance (Δt) includes calculating the tolerance as Δt=2 SSB symbols of the target cell.

[0012] In some implementations, calculating the tolerance (Δt) includes receiving signaling indicating a formula to use to calculate the tolerance and calculating the tolerance based on the signaled formula.

[0013] In some implementations, the formula that is signaled is one of the following: i) Δt=min(2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell), and (ii) Δt=2 SSB symbols of the target cell.

[0014] In some implementations, the tolerance includes a separate tolerance defined for each of a number of predefined SSB pattern cases.

[0015] In some implementations, calculating the tolerance (Δt) includes determining a first SSB pattern case associated with the target cell and a second SSB pattern case associated with the reference cell, determining that the first SSB pattern has a larger subcarrier spacing than the second SSB pattern, and calculating the tolerance based on an individual tolerance associated with the first SSB pattern.

[0016] In some implementations, the plurality of predefined SSB pattern cases includes: [Table 1]

[0017] In some implementations, the respective tolerance defined for case B, case D, or case E is calculated as Δt=2 SSB symbols.

[0018] In some implementations, the respective tolerance defined for case A or case C is calculated as Δt=3 SSB symbols.

[0019] In some implementations, the respective tolerance defined for case F or case G is calculated as Δt=3.5 SSB symbols.

[0020] In some implementations, with the respective tolerance defined for case B or D and two consecutive SSBs being transmitted, it is calculated as Δt=6 SSB symbols.

[0021] According to another aspect of the present disclosure, a method implemented by a base station of a serving cell includes generating, for a user equipment (UE) served by the serving cell, a message including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is authorized to use timing of a reference cell to derive an index of the target SSB burst, the target SSB burst including one or more SSBs, and preparing the message for transmission to the UE.

[0022] Other versions include corresponding systems, apparatus, and computer programs for performing the actions of the methods defined by instructions encoded on a computer-readable storage device. These and other versions may optionally include one or more of the following features.

[0023] In some implementations, the SSB information includes the frequency of the target SSB burst and the subcarrier spacing of the target SSB burst.

[0024] In some implementations, the method further includes transmitting the message to the UE.

[0025] The details of one or more embodiments of these systems and methods are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these systems and methods will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0026] [Figure 1] 1 illustrates an example of deriving an SSB index according to some embodiments.

[0027] [Diagram 2] 1 illustrates a wireless network according to some embodiments.

[0028] [Diagram 3] 13 illustrates another example of deriving an SSB index according to some embodiments.

[0029] [Figure 4A] 1 illustrates a flowchart of an exemplary method according to some embodiments. [Figure 4B] 1 illustrates a flowchart of an exemplary method according to some embodiments.

[0030] [Diagram 5] 1 illustrates a user equipment (UE) according to some embodiments.

[0031] [Figure 6] 1 illustrates an access node according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] As mentioned above, 5GNR introduces cell signal measurement by using synchronization signal blocks (SSBs). In the time domain, an SSB spans four orthogonal frequency division multiplexing (OFDM) symbols and is transmitted periodically with a period of 5 milliseconds (ms), 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms. To enable beamforming and beam sweeping for SSBs, the standard promulgated by the 3rd Generation Partnership Project (3GPP) defines an SS burst set. An SS burst set includes a set of one or more SSBs, and each SSB can be transmitted on a different beam.

[0033] The 3GPP standard defines different cases of time domain patterns of SSB transmission. In particular, the 3GPP standard defines a set of symbols designated as candidates for the start of SSB transmission. For a half frame with an SSB block, the first symbol index for the candidate SSB is determined according to the subcarrier spacing (SCS) of the SS / PBCH block, with index 0 corresponding to the first symbol of the first slot in the half frame. The following cases are specified in 3GPP TS 38.213:

[0034] Case A - 15 kHz SCS: The first symbol of a candidate SS / PBCH block has an index of {2,8}+14n. - For operation without shared spectrum channel access: - For carrier frequencies below 3 GHz, n=0,1. - For carrier frequencies in FR1 greater than 3 GHz, n=0,1,2,3. - n = 0, 1, 2, 3, 4 for operation with shared spectrum channel access as described in [TS 37.213].

[0035] Case B - 30 kHz SCS: The first symbol of a candidate SS / PBCH block has index {4,8,16,20}+28·n. For carrier frequencies below 3 GHz, n=0. For carrier frequencies in FR1 greater than 3 GHz, n=0,1.

[0036] Case C - 30 kHz SCS: The first symbol of the candidate SS / PBCH block has index {2,8}+14·n. - For operation without shared spectrum channel access - For spectrum operation - For carrier frequencies below 3 GHz, n = 0, 1. For carrier frequencies in FR1 above 3 GHz, n = 0, 1, 2, 3. - For unpaired spectrum operation. - For carrier frequencies below 1.88 GHz, n=0,1. For carrier frequencies in FR1 equal to or greater than 1.88 GHz, n=0,1,2,3. - For operation with shared spectrum channel access, n=0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

[0037] Case D - 120 kHz SCS: The first symbol of a candidate SS / PBCH block has index {4, 8, 16, 20} + 28 n, where n = 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 for carrier frequencies in FR2.

[0038] Case E-240 kHz SCS: The first symbol of the candidate SS / PBCH block has index {8, 12, 16, 20, 32, 36, 40, 44}+56·n, where n=0, 1, 2, 3, 5, 6, 7, 8 for carrier frequencies in FR2-1.

[0039] Case F-480kHz SCS: The first symbol of the candidate SS / PBCH block has index {2,9}+14·n, where n=0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31 for carrier frequencies in FR2-2.

[0040] Case G - 960 kHz SCS: The first symbol of the candidate SS / PBCH block has index {2,9}+14·n, where n=0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 for carrier frequencies in FR2-2. Cases A-G are summarized in Table 1. [Table 2]

[0041] 3GPP also introduces an SSB-based measurement timing configuration window called SMTC window. The SMTC window indicates the measurement period and timing of SSBs that the UE can use for measurements. The SMTC window period can be set in the same range as the SSB period (e.g., 5, 10, 20, 40, 80 or 160 ms). Furthermore, the window duration can be set to 1, 2, 3, 4 or 5 ms according to the number of SSBs transmitted on the cell being measured.

[0042] In 5G NR, measurement objects are defined for intra-frequency and inter-frequency measurements. Information indicating the reference signal to be measured may be transmitted by the network using the IEMeasObjectNR. Such information may include frequency / time location and subcarrier spacing of the reference signal. For example, a measurement configuration for SSB is provided under measObjectToAddMod as part of the MeasObjectNRIE. The IE includes at least the following fields: ssbFrequency, ssbSubcarrierSpacing, smtc1, and smtc2. The field ssbFrequency provides the frequency of the SS associated with the measurement object. The field ssbSubcarrierSpacing provides the subcarrier spacing of the SSB. The fields smtc1 and smtc2 provide the primary and secondary measurement timing configurations, respectively. The primary measurement timing configuration provides the timing offset and duration for the SSB.

[0043] After receiving the MeasObjectNR IE, the UE can perform the measurements provided in the IE. In the case of an SSB set (also called an SSB burst), the UE can measure one or more SSBs contained in the burst. When the UE receives an SSB in an SSB burst, it is important for the UE to identify the index of the SSB (i.e., which SSB in the burst has been received). This is especially difficult when the UE is receiving an SSB from a target cell (i.e., a cell other than the serving cell or a neighboring cell). To address this challenge, 3GPP introduced the field deriveSSB-IndexFromCell, which allows the UE to derive the SSB index of the target cell(s) on the same frequency as the serving cell. This field is included in the SSB-ConfigMobility IE found in the IEMeasObjectNR of the neighboring cell. TS 38.331 defines deriveSSB-IndexFromCell as follows: If this field is set to true, the UE assumes SFN [System Frame Number] and frame boundary alignment across cells on the same frequency carrier as specified in TS 38.133

[14] . Thus, if the UE is configured with a serving cell whose (ServingCellConfigCommon, subcarrierSpacing) in absoluteFrequencySSB is equal to (ssbFrequency, ssbSubcarrierSpacing) in this MeasObjectNR, this field indicates whether the UE can utilize the timing of this serving cell to derive indices of SS blocks transmitted by neighboring cells. Otherwise, this field indicates whether the UE can use the timing of any detected cells on its target frequency to derive SSB indices of all neighboring cells on that frequency.

[0044] Furthermore, when deriveSSB-IndexFromCell is enabled, the UE assumes that the frame boundary alignment (including half-frame, subframe, and slot boundary alignment) across cells on the same frequency carrier is within a tolerance (Δt) not worse than min (2 SSB symbols, 1 PDSCH symbol). The UE also assumes that the SFN of all cells on the same frequency carrier is the same. Thus, the UE can determine a candidate position (also called SSB index #0 or SSB #0) for the first SSB in the burst. If the UE measures an SSB in that candidate position, the UE can determine that the measured SSB is SSB #0. The UE can also derive candidate positions for the SSBs (if any) in the SSB burst. For example, the UE can use Table 1 to derive candidate positions for each of the remaining SSBs (if any) in the burst from the position of SSB #0.

[0045] The flag deriveSSB-IndexFromCell achieves a number of advantages. As an example, the flag reduces the time for SSB index detection (T SSB_time_index =0). As another example, the flag allows more symbols to be scheduled when scheduling restrictions apply. If the flag was not available, the UE would have to restrict the entire SMTC window for SSB detection, because without the flag, the UE would not know when an SSB occurs within the window.

[0046] FIG. 1 illustrates an example 100 of deriving an SSB index according to some embodiments. In the example 100, a UE (not shown in FIG. 1) receives a flag deriveSSB-IndexFromCell. Thus, the UE assumes that the frame boundary alignment (including half-frame, subframe, and slot boundary alignment) across cells on the same frequency carrier is within a tolerance Δt. Thus, the UE can derive an SSB index of a target SSB burst broadcasted by a neighboring cell. In particular, the UE knows that SSB index #0 is received within a tolerance Δt of the frame boundary of the SSB scheduled by the source cell. Thus, if the UE measures an SSB within the tolerance, the UE can determine that the measured SSB is SSBindex#0.

[0047] In example 100, the UE is measuring a target SSB burst on neighbor cell 1, which is also operating on carrier 1 as the UE's serving cell. Thus, the UE assumes that the frame boundary alignment across the serving cell and the neighbor cell is within a tolerance Δt. Thus, the UE knows the candidate position for SSB#0 (i.e., the first SSB in the target SSB burst). When the UE detects an SSB within the tolerance, the UE knows that the detected SSB is SSB#0.

[0048] However, for the inter-frequency case, the meaning of the deriveSSB-IndexFromCell flag is different. The timing of the serving cell cannot be used for an inter-frequency target cell. Rather, the UE must first read the SSB index of at least one of the neighbor cells and then derive the SSB index of other neighbor cells on the same inter-frequency carrier. It is proposed to enhance the IE for inter-frequency cells with the same SCS. In particular, RAN4 agreed to introduce a new network signaling [deriveSSB-lndexFromCell-inter] that informs the UE that the SSB index of the target cell(s) on a frequency different from that of the serving cell can be derived from the serving cell. Furthermore, the IE informs the UE which serving cell should be utilized for the target SSB index derivation. RAN4 also agreed that the IE can be configured only if the SCS of the SSB is the same between the target cell and the serving cell used for the SSB index derivation. However, this IE is not applicable for inter-frequency target cells with a different SCS than the serving cell.

[0049] The present disclosure describes a method and system for deriving an SSB index on an inter-frequency neighboring cell. In one example, the disclosed method and system can be used to derive an SSB index in a scenario where an inter-frequency target cell has a different SCS than a serving cell.

[0050] 2 illustrates a wireless network 200 according to some embodiments. The wireless network 200 includes a UE 202 and a base station 204 connected via one or more channels 206A, 206B over an air interface 208. The UE 202 and the base station 204 communicate using a system that supports control for managing the UE 202's access to the network via the base station 204.

[0051] For convenience, but not by way of limitation, the wireless network 200 is described in the context of Long Term Evolution (LTE) and Fifth Generation (5G) New Radio (NR) communication standards defined by the Third Generation Partnership Project (3GPP) technical specifications. More specifically, the wireless network 200 is described in the context of a non-standalone (NSA) network incorporating both LTE and NR, such as an Evolved Universal Terrestrial Radio Access (E-UTRA)-NR Dual Connectivity (EN-DC) network and a NE-DC network. However, the wireless network 200 may also be a standalone (SA) network incorporating only NR. Additionally, other types of communication standards are possible, including future 3GPP systems (e.g., sixth generation (6G)) systems, IEEE 802.16 protocols (e.g., WMAN, WiMAX, etc.), and the like. Although aspects may be described herein using terminology generally associated with 5G NR, aspects of the disclosure may apply to other systems, such as 3G, 4G, and / or systems subsequent to 5G (e.g., 6G).

[0052] In wireless network 200, UE 202 and any other UE in the system may be, for example, a laptop computer, a smartphone, a tablet computer, a printer, a machine type device such as a smart meter or a dedicated device for healthcare monitoring, a remote security monitoring system, an intelligent transportation system, or any other wireless device with or without a user interface. In network 200, base stations 204 provide UE 202 with network connectivity to a wider network (not shown). This UE 202 connectivity is provided via an air interface 208 within a base station coverage area provided by base station 204. In some embodiments, such a wider network may be a wide area network operated by a cellular network provider or may be the Internet. Each base station coverage area associated with base station 204 is supported by an antenna integrated with base station 204. The coverage area is divided into multiple sectors associated with a particular antenna. Such sectors may be physically associated with fixed antennas or may be assigned to a physical area with tunable antennas or antenna settings that can be adjusted in a beamforming process used to direct signals to a particular sector.

[0053] The UE 202 includes a control circuit 210 coupled to a transmit circuit 212 and a receive circuit 214. The transmit circuit 212 and the receive circuit 214 may each be coupled to one or more antennas. The control circuit 210 may be adapted to perform operations associated with selecting a codec for communication and adapting a codec for wireless communication as part of system congestion control. The control circuit 210 may include various combinations of application specific and baseband circuits. The transmit circuit 212 and the receive circuit 214 may be adapted to transmit and receive data, respectively, and may include radio frequency (RF) circuitry or front-end module (FEM) circuitry, including communication using the codecs described herein.

[0054] In various embodiments, aspects of the transmit circuitry 212, receive circuitry 214, and control circuitry 210 may be integrated in various ways to implement the circuitry described herein. The control circuitry 210 may be adapted or configured to perform various operations, such as those described elsewhere in this disclosure in connection with a UE. The transmit circuitry 212 may transmit multiple multiplexed uplink physical channels. The multiple uplink physical channels may be multiplexed by time division multiplexing (TDM) or frequency division multiplexing (FDM) with carrier aggregation. The transmit circuitry 212 may be configured to receive block data from the control circuitry 210 for transmission over the air interface 208. Similarly, the receive circuitry 214 may receive multiple multiplexed downlink physical channels from the air interface 208 and relay the physical channels to the control circuitry 210. The multiple downlink physical channels may be multiplexed by TDM or FDM with carrier aggregation. The transmit circuitry 212 and receive circuitry 214 may transmit and receive both control data and content data (eg, messages, images, videos, etc.) structured within data blocks carried by the physical channel.

[0055] 2 also illustrates a base station 204. In an embodiment, the base station 204 may be a NG Radio Access Network (RAN) or a 5G RAN, an E-UTRAN, a non-terrestrial cell, or a legacy RAN such as a UTRAN or a GERAN. As used herein, terms such as "NG RAN" may refer to a base station 204 operating in a NR or 5G wireless network 200, and terms such as "E-UTRAN" may refer to a base station 204 operating in a LTE or 4G wireless network 200. The UE 202 utilizes connections (or channels) 206A, 206B, each of which includes a physical communication interface or layer.

[0056] The base station 204 circuitry may include control circuitry 216 coupled to transmit circuitry 218 and receive circuitry 220. The transmit circuitry 218 and receive circuitry 220 may each be coupled to one or more antennas that may be used to facilitate communication over the air interface 208.

[0057] The control circuitry 216 may be adapted to perform operations to analyze and select a codec, manage congestion control and bandwidth limited communications from the base station, determine if the base station is codec aware, and communicate with a codec aware base station to manage codec selection for various communication operations described herein. The transmit circuitry 218 and the receive circuitry 220 may be adapted to transmit and receive data to any UE connected to the base station 204, respectively, using data generated with various codecs as described herein. The transmit circuitry 218 may transmit a downlink physical channel consisting of multiple downlink subframes. The receive circuitry 220 may receive multiple uplink physical channels from various UEs, including the UE 202.

[0058] In this example, the one or more channels 206A, 206B are depicted as air interfaces enabling a communicative coupling and may conform to a cellular communication protocol such as a GSM protocol, a CDMA network protocol, a PTT protocol, a POC protocol, a UMTS protocol, a 3GPP LTE protocol, an Advanced Long Term Evolution (LTE-A) protocol, an LTE-based access to unlicensed spectrum (LTE-U), a 5G protocol, a NR protocol, an NR-based access to unlicensed spectrum (NR-U) protocol, and / or any of the other communication protocols described herein. In an embodiment, the UE 202 may directly exchange communication data over the ProSe interface. The ProSe interface may alternatively be referred to as an SL interface and may include one or more logical channels including, but not limited to, a PSCCH, a PSSCH, a PSDCH, and a PSBCH.

[0059] In some embodiments, the wireless network 200 is configured to use a new field called deriveSSB-IndexFromCell-inter in a measurement object associated with a neighbor cell (also referred to as a target cell). In particular, this field can be used when the measurement object is for an SSB burst of the target cell, where the SSB burst or set includes one or more SSBs. Details of the SSB burst for the measurement can be provided in ssb-ToMeasure. The deriveSSB-IndexFromCell-inter field indicates whether the UE 202 can derive SSB indices for all neighbor cells on the frequency provided in the measurement object using the timing of the reference cell. In some examples, the reference cell is the serving cell of the UE 202 if the UE has only a serving cell. However, if the UE 202 has multiple serving cells, the deriveSSB-IndexFromCell-inter (or another field in ssb-ToMeasure) indicates which of the serving cells should be used as the reference cell.

[0060] In some embodiments, the deriveSSB-IndexFromCell-inter field is a single bit that can be set to 0 or 1. In another example, the field is a Boolean data type that can be set to false or true. If the field is set to 1 or true, the UE 202 assumes SFN and frame boundary alignment across cells on adjacent frequencies (e.g., as specified in TS 38.133).

[0061] In some embodiments, when the wireless network 200 enables deriveSSB-IndexFromCell-inter for a UE 202, the UE assumes that the frame boundary alignment (e.g., half-frame, subframe, and / or slot boundary alignment) across cells on the same carrier is no worse than the tolerance Δt (i.e., within the tolerance). Additionally, the UE assumes that the SFNs of all cells on the same frequency carrier are the same.

[0062] In some embodiments, receiving deriveSSB-IndexFromCell-inter set to true in the measurement object for the target cell allows the UE 202 to derive an SSB index for the SSB burst broadcast of that target cell. In one example, if deriveSSB-IndexFromCell-inter is set to true, the UE 202 can determine a candidate location for SSB#0 in the target cell (even though the SSB is not transmitted). More specifically, if deriveSSB-IndexFromCell-inter is set to true, the UE 202 can determine that the symbol boundary of the target cell's SSB#0 is within (Δt to Δt) of the frame boundary of the reference cell's SSB#0. Once the UE 202 determines the candidate location of SSB#0, the UE can determine the candidate locations of the remaining SSBs (if any) in the burst. The UE 202 can do so even though the SSB#0 itself is not transmitted. In particular, the UE 202 may use the SSB pattern (eg, as defined in Table 1) to determine candidate locations for the remaining SSBs (if any) in the burst.

[0063] In some embodiments, the UE 202 may determine a window for measuring the target SSB burst. The target SSB is configured by the wireless network 100 via RRC "SSB-ToMeasure". SSB-ToMeasure indicates the set of SS blocks to be measured within the SMTC measurement duration (e.g., as described in TS 38.215). If the field is not present, the UE measures on all SSBs. In one example, the window length for measuring each SSB is equal to 4 SSB symbols of the target cell + 2*Δt. The total measurement window is the combination of all measurement windows for each SSB to be measured (e.g., as specified in SSB-ToMeasure).

[0064] In some embodiments, the UE 202 may be configured with one or more methods for calculating the tolerance Δt. In one method, the tolerance is calculated using a predetermined formula. In one example, the tolerance is defined according to the following formula [1]: [1] Δt = min (2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell) In this example, the UE calculates Δt according to equation [1] for all SSB pattern cases (eg, as set forth in Table 1). In another example, the tolerance is defined according to the following equation [2]: [2] Δt = 2 SSB symbols of the target cell.

[0065] In another method, the UE 202 receives network signaling that indicates to the UE a formula for calculating the tolerance. In this method, the UE 202 receives signaling from the wireless network 200 that indicates a formula (e.g., formula [1] or formula [2]) to use to calculate Δt associated with a particular measurement object. Thus, the wireless network 200 can specify different formulas for different measurement objects. For example, the wireless network 200 can specify that the UE 202 uses formula [1] for a measurement object associated with a first neighboring cell and formula [2] for a measurement object associated with a second neighboring cell.

[0066] In yet another method, the tolerance is determined based on the SSB pattern case of the target cell and / or the reference cell. The SSB pattern cases are shown in Table 1. In this method, a separate tolerance is defined for each SSB pattern case. However, there is an SSB pattern case associated with the reference cell and an SSB pattern case associated with the target cell. Therefore, to determine the tolerance for selection, the UE 202 selects one of the SSB pattern case associated with the reference cell and the SSB pattern case associated with the target cell. In one example, the UE 202 selects the SSB pattern case with the larger SCS of the two. Once the UE 202 selects the SSB pattern case to use, the UE 202 selects the tolerance based on the selected pattern.

[0067] In some embodiments, SSB pattern cases that include consecutive candidate SSB locations are assigned the same respective tolerance. Such pattern cases include cases B, D, and E from Table 1. In one example, the tolerance is calculated using Equation [3]. [3] Δt = 2 SSB symbols. In these embodiments, SSB pattern cases A and C from Table 1 are assigned the same individual tolerance. In one example, the tolerance is calculated using equation [4]. [4] Δt = 3 SSB symbols. In these embodiments, SSB pattern cases F and G from Table 1 are assigned the same individual tolerance. In one example, the tolerance is calculated using equation [5]. [5] Δt = 3.5 SSB symbols. In equations [3], [4] and [5], the symbol duration of the SSB symbol is determined by the larger SCS of the reference cell and the target cell.

[0068] In some embodiments, if the selected SSB pattern is case B or D from Table 1 and two consecutive SSBs are transmitted, the tolerance is calculated using equation [6]. [6] Δt = 6 SSB symbols. In one example, the measurement object may include an indication that the target cell is transmitting two consecutive SSBs.

[0069] FIG. 3 illustrates an example 300 of deriving an SSB index according to some embodiments. In the example 300, a UE (not shown in FIG. 3) is served by serving cell 1 operating on carrier 2. The UE receives a measurement object that instructs the UE to measure an SSB burst of neighboring cell 1 operating on carrier 1. The measurement object also includes a field deriveSSB-IndexFromCell-inter set to true. Thus, the UE assumes that the frame boundary alignment (including half-frame, subframe, and slot boundary alignment) across all neighboring cells on carrier 2 is within a tolerance Δt. Thus, the UE can derive an SSB index for a target SSB burst broadcast by neighboring cell 1. In particular, the UE knows that SSB#0 is received within a tolerance Δt of the frame boundary of the SSB scheduled by serving cell 1. Thus, if the UE measures an SSB within the tolerance, the UE can determine that the measured SSB is SSB#0. In the example 300, the UE knows the candidate positions for SSB#0. When the UE detects an SSB within the tolerance, the UE knows that the detected SSB is SSB#0, as shown in Figure 3. Furthermore, by knowing the location of SSB#0, the UE can derive the locations of the remaining SSBs (e.g., SSB#1, SSB#2, SSB#3).

[0070] 4A illustrates a flowchart of an example method 400 according to some implementations. For clarity of presentation, the following description generally describes the method 400 in the context of other figures in this description. For example, the method 400 may be implemented by the UE 500 of FIG. 5. It will be appreciated that the method 400 may be implemented, for example, by any suitable system, environment, software, hardware, or combination of systems, environments, software, and hardware, as appropriate. In some implementations, various steps of the method 400 may be performed in parallel, in combination, in a loop, or in any order.

[0071] In step 402, the method 400 includes receiving a message from a serving cell serving the UE including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is authorized to use the timing of the reference cell to derive an index of the target SSB burst, the target SSB burst including one or more SSBs.

[0072] In step 404, the method 400 includes calculating a frame boundary alignment tolerance (Δt) between the reference cell and the target cell.

[0073] At 406, the method 400 includes determining an index of the target SSB burst based on the tolerance.

[0074] In some implementations, the SSB information includes the frequency of the target SSB burst and the subcarrier spacing of the target SSB burst.

[0075] In some implementations, the method further includes measuring at least a portion of the target SSB burst during the measurement window based on at least one of the tolerance (Δt) or the SSB information.

[0076] In some implementations, measuring at least a portion of the target SSB burst based at least in part on the tolerance (Δt) or the SSB information comprises determining a time length of the measurement window:

number

[0077] In some implementations, determining an index of the target SSB burst includes determining a candidate position of a first SSB within the target SSB burst based on the tolerance, and determining an index of the target SSB burst based on at least one of the candidate position of the first SSB or a measured portion of the target SSB index.

[0078] In some implementations, calculating the tolerance (Δt) includes calculating the tolerance as Δt=min(2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell).

[0079] In some implementations, calculating the tolerance (Δt) includes calculating the tolerance as Δt=2 SSB symbols of the target cell.

[0080] In some implementations, calculating the tolerance (Δt) includes receiving signaling indicating a formula to use to calculate the tolerance and calculating the tolerance based on the signaled formula.

[0081] In some implementations, the formula that is signaled is one of the following: i) Δt=min(2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell), and (ii) Δt=2 SSB symbols of the target cell.

[0082] In some implementations, the tolerance includes a separate tolerance defined for each of a number of predefined SSB pattern cases.

[0083] In some implementations, calculating the tolerance (Δt) includes determining a first SSB pattern case associated with the target cell and a second SSB pattern case associated with the reference cell, determining that the first SSB pattern has a larger subcarrier spacing than the second SSB pattern, and calculating the tolerance based on an individual tolerance associated with the first SSB pattern.

[0084] In some implementations, the plurality of predefined SSB pattern cases includes: [Table 3]

[0085] In some implementations, the respective tolerance defined for case B, case D, or case E is calculated as Δt=2 SSB symbols.

[0086] In some implementations, the respective tolerance defined for case A or case C is calculated as Δt=3 SSB symbols.

[0087] In some implementations, the respective tolerance defined for case F or case G is calculated as Δt=3.5 SSB symbols.

[0088] In some implementations, with the respective tolerance defined for case B or D and two consecutive SSBs being transmitted, it is calculated as Δt=6 SSB symbols.

[0089] 4B illustrates a flowchart of an example method 420 according to some implementations. For clarity of presentation, the following description generally describes the method 420 in the context of other figures in this description. For example, the method 420 may be performed by the access node 600 of FIG. 6. It will be appreciated that the method 420 may be suitably performed by, for example, any suitable system, environment, software, hardware, or combination of systems, environments, software, and hardware. In some implementations, various steps of the method 420 may be performed in parallel, in combination, in a loop, or in any order.

[0090] In step 422, the method 420 includes generating a message for a user equipment (UE) served by the serving cell that includes (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is permitted to use the timing of the reference cell to derive an index of the target SSB burst, where the target SSB burst includes one or more SSBs.

[0091] At step 424, the method 420 includes preparing a message for transmission to the UE.

[0092] In some implementations, the SSB information includes the frequency of the target SSB burst and the subcarrier spacing of the target SSB burst.

[0093] In some implementations, the method further includes transmitting the message to the UE.

[0094] In some embodiments, a system, such as a base station, a device including one or more baseband processors, etc., can be configured to perform a particular operation or action by installing software, firmware, hardware, or a combination thereof into an operating system and causing the system to perform the operation. The operation or action performed by the system can include methods 400, 420.

[0095] 5 illustrates a UE 500 according to some embodiments. The UE 500 may be similar to and substantially interchangeable with the UE 202 of FIG.

[0096] The UE 500 may be any mobile or non-mobile computing device, such as, for example, a mobile phone, a computer, a tablet, an industrial wireless sensor (e.g., a microphone, a carbon dioxide sensor, an air pressure sensor, a humidity sensor, a thermometer, a motion sensor, an accelerometer, a laser scanner, a fluid level sensor, an inventory sensor, a voltage / current meter, an actuator, etc.), a video surveillance / monitoring device (e.g., a camera, a video camera, etc.), a wearable device (e.g., a smart watch), a relaxed IoT device, etc.

[0097] The UE 500 may include a processor 502, an RF interface circuit 504, a memory / storage 506, a user interface 508, a sensor 510, a driver circuit 512, a power management integrated circuit (PMIC) 514, an antenna structure 516, and a battery 518. The components of the UE 500 may be implemented as an integrated circuit (IC), a portion thereof, a discrete electronic device, or other module, logic, hardware, software, firmware, or a combination thereof. The block diagram of FIG. 5 is intended to illustrate a high-level view of some of the components of the UE 500. However, some of the components shown may be omitted, additional components may be present, and different arrangements of the components shown may occur in other implementations.

[0098] The components of UE 500 may be coupled to various other components via one or more interconnects 520, which may represent any type of interface, input / output, bus (local, system or expansion), transmission line, trace, optical connection, etc. that may allow various circuit components (on a common or different chips or chipsets) to interact with one another.

[0099] The processor 502 may include processor circuitry such as, for example, a baseband processor circuit (BB) 522A, a central processing unit circuit (CPU) 522B, and a graphics processing unit circuit (GPU) 522C. The processor 502 may include any type of circuitry or processor circuitry that executes or otherwise operates computer-executable instructions, such as program code, software modules, or functional processes from memory / storage 506 to cause the UE 500 to perform the operations described herein.

[0100] In some embodiments, the baseband processor circuit 522A may access a communications protocol stack 524 in the memory / storage 506 to communicate over a 3GPP-compliant network. In general, the baseband processor circuit 522A may access the communications protocol stack to perform user plane functions at the PHY, MAC, RLC, PDCP, SDAP, and PDU layers, and control plane functions at the PHY, MAC, RLC, PDCP, RRC, and non-access layers. In some embodiments, PHY layer operations may additionally / alternatively be performed by components of the RF interface circuit 504. The baseband processor circuit 522A may generate or process baseband signals or waveforms that carry information in a 3GPP-compliant network. In some embodiments, waveforms for NR may be based on Cyclic Prefix OFDM "CP-OFDM" in the uplink or downlink, and Discrete Fourier Transform Spread OFDM "DFT-S-OFDM" in the uplink.

[0101] The memory / storage 506 may include one or more non-transitory computer-readable media (e.g., communication protocol stack 524) that include instructions that may be executed by one or more of the processors 502 to cause the UE 500 to perform various operations described herein. The memory / storage 506 includes any type of volatile or non-volatile memory that may be distributed throughout the UE 500. In some embodiments, some of the memory / storage 506 may be located on the processor 502 itself (e.g., L1 and L2 caches), while other memory / storage 506 may be external to the processor 502 but accessible via a memory interface. The memory / storage 506 may include, but is not limited to, volatile or non-volatile memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid state memory, or any other type of memory device technology.

[0102] The RF interface circuitry 504 may include transceiver circuitry and a radio frequency front end module (RFEM) that enable the UE 500 to communicate with other devices over a radio access network. The RF interface circuitry 504 may include various elements disposed in the transmit or receive paths. These elements may include, for example, switches, mixers, amplifiers, filters, combiner circuits, control circuits, etc.

[0103] In the receive path, the RFEM may receive a radiated signal from the air interface via the antenna structure 516 and proceed to filter and amplify the signal (using a low noise amplifier). The signal may be provided to a transceiver receiver that downconverts the RF signal to a baseband signal that is provided to a baseband processor of the processor 502.

[0104] In the transmit path, the transmitter of the transceiver upconverts the baseband signal received from the baseband processor and provides an RF signal to the RFEM, which may amplify the RF signal through a power amplifier before the signal is radiated over the air interface via the antenna 516.

[0105] In various embodiments, the RF interface circuitry 504 may be configured to transmit and receive signals in a manner that complies with NR access technologies.

[0106] The antenna 516 may include antenna elements that convert electrical signals into radio waves to travel through the air and convert received radio waves into electrical signals. The antenna elements may be arranged in one or more antenna panels. The antenna 516 may have antenna panels that are omnidirectional, directional, or a combination thereof to enable beamforming and multiple-input multiple-output communications. The antenna 516 may include microstrip antennas, printed antennas fabricated on the surface of one or more printed circuit boards, patch antennas, phased array antennas, etc. The antenna 516 may have one or more panels designed for a particular frequency band, including bands in FR1 or FR2.

[0107] User interface circuitry 508 includes various input / output (I / O) devices designed to enable user interaction with UE 500. User interface 508 includes input device circuitry and output device circuitry. Input device circuitry includes any physical or virtual means for accepting input, including, among others, one or more physical or virtual buttons (e.g., a reset button), a physical keyboard, a keypad, a mouse, a touchpad, a touch screen, a microphone, a scanner, a headset, etc. Output device circuitry includes any physical or virtual means for displaying or otherwise communicating information, such as sensor readings, actuator position(s), or other similar information. The output device circuitry may include any number or combination of audio or visual displays, including, among others, one or more simple visual outputs / indicators (e.g., binary status indicators such as light emitting diodes "LEDs" and multi-character visual outputs), or more complex outputs such as display devices or touch screens (e.g., liquid crystal displays "LCDs", LED displays, quantum dot displays, projectors, etc.), where output such as text, graphics, multimedia objects, etc. are generated or created from operation of the UE 500.

[0108] The sensors 510 may include devices, modules, or subsystems intended to detect events or changes in the environment and transmit information about the detected events (sensor data) to some other device, module, subsystem, etc. Examples of such sensors include, among others, inertial measurement units including accelerometers, gyroscopes, or magnetometers; microelectromechanical systems or nanoelectromechanical systems including 3-axis accelerometers, 3-axis gyroscopes, or magnetometers; level sensors; flow sensors; temperature sensors (e.g., thermistors); pressure sensors; barometric pressure sensors; gravimeters; altimeters; image capture devices (e.g., cameras or lensless apertures); light detection and ranging sensors, proximity sensors (e.g., infrared detectors, etc.), depth sensors, ambient light sensors, ultrasonic transceivers, microphones or other similar audio capture devices, etc.

[0109] The driver circuitry 512 may include software and hardware elements that operate to control particular devices embedded in, attached to, or otherwise communicatively coupled to the UE 500. The driver circuitry 512 may include individual drivers that allow other components to interact with or control various input / output (I / O) devices that may be present in or connected to the UE 500. For example, the driver circuitry 512 may include a display driver that controls and enables access to a display device, a touchscreen driver that controls and enables access to a touchscreen interface, a sensor driver that obtains sensor readings of the sensor circuitry 528 and controls and enables access to the sensor circuitry 528, a driver that obtains actuator positions of or controls and enables access to electromechanical components, a camera driver that controls and enables access to an embedded image capture device, an audio driver that controls and enables access to one or more audio devices.

[0110] The PMIC 514 may manage the power provided to various components of the UE 500. In particular, with respect to the processor 502, the PMIC 514 may control power source selection, voltage scaling, battery charging, or DC-DC conversion.

[0111] In some embodiments, the PMIC 514 may control or otherwise be a part of various power saving mechanisms of the UE 500, including the DRX discussed herein. The battery 518 may power the UE 500, although in some examples the UE 500 may be mounted and deployed at a fixed location and may have a power source coupled to a power grid. The battery 518 may be a lithium ion battery, a metal air battery such as a zinc air battery, an aluminum air battery, a lithium air battery, or the like. In some implementations, such as vehicle-based applications, the battery 518 may be a typical automotive lead acid battery.

[0112] In some embodiments, one or more elements of UE 500 are configured to perform operations including receiving a message from a serving cell serving the UE including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is authorized to use the timing of a reference cell to derive an index of the target SSB burst, the target SSB burst including one or more SSBs; calculating a tolerance of frame boundary alignment between the reference cell and the target cell; and determining an index of the target SSB burst based on the tolerance.

[0113] 6 illustrates an access node 600 (e.g., a base station or a gNB) according to some embodiments. The access node 600 may be similar to and substantially interchangeable with the base station 204. The access node 600 may include a processor 602, an RF interface circuit 604, a core network (CN) interface circuit 606, a memory / storage circuit 608, and an antenna structure 610.

[0114] The components of the access node 600 may be coupled to various other components via one or more interconnects 612. The processor 602, RF interface circuitry 604, memory / storage circuitry 608 (including a communications protocol stack 614), antenna structure 610, and interconnects 612 may be similar to the similarly named elements shown and described with respect to Figure 5. For example, the processor 602 may include processor circuitry such as a baseband processor circuitry (BB) 616A, a central processing unit circuitry (CPU) 616B, and a graphics processing unit circuitry (GPU) 616C.

[0115] The CN interface circuitry 606 may provide connectivity to a core network, e.g., a fifth generation core network (5GC), using a 5GC compliant network interface protocol, such as a Carrier Ethernet protocol or any other suitable protocol. Network connectivity may be provided to / from the access node 600 via optical fiber or wireless backhaul. The CN interface circuitry 606 may include one or more dedicated processors or FPGAs for communicating using one or more of the aforementioned protocols. In some implementations, the CN interface circuitry 606 may include multiple controllers to provide connectivity to other networks using the same or different protocols.

[0116] As used herein, the terms "access node", "access point", etc. may refer to equipment that provides wireless baseband functionality for data and / or voice connectivity between a network and one or more users. These access nodes may be referred to as BSs, gNBs, RAN nodes, eNBs, NodeBs, RSUs, TRxPs, TRPs, etc., and may include terrestrial stations (e.g., terrestrial access points) or satellite stations that provide coverage within a geographic area (e.g., a cell). As used herein, the terms "NG RAN node" etc. may refer to an access node 600 operating in a NR or 5G system (e.g., gNB), and the terms "E-UTRAN node" etc. may refer to an access node 600 operating in a LTE or 4G system (e.g., eNB). According to various embodiments, the access node 600 may be implemented as one or more of a macrocell base station and / or a dedicated physical device such as a femtocell, picocell, or other like cell having a smaller coverage area, smaller user capacity, or higher bandwidth compared to a macrocell.

[0117] In some embodiments, all or a portion of the access node 600 may be implemented as one or more software entities executing on a server computer as part of a virtual network, which may be referred to as a CRAN and / or a virtual baseband unit pool (vBBUP). In these embodiments, the CRAN or vBBUP may implement a RAN functionality split, such as a PDCP split, where the RRC and PDCP layers are operated by the CRAN / vBBUP and other L2 protocol entities are operated by the access node 600, a MAC / PHY split, where the RRC, PDCP, RLC, and MAC layers are operated by the CRAN / vBBUP and the PHY layer is operated by the access node 600, or a "lower PHY" split, where the RRC, PDCP, RLC, MAC layers, and the upper part of the PHY layer are operated by the CRAN / vBBUP and the lower part of the PHY layer is operated by the access node 600.

[0118] In a V2X scenario, the access node 600 may be or operate as an RSU. The term "Road Side Unit" or "RSU" may refer to any transportation infrastructure entity used for V2X communications. An RSU may be implemented in or by a suitable RAN node or a stationary (or relatively stationary) UE, and an RSU implemented in or by a UE may be referred to as a "UE-type RSU", an RSU implemented in or by an eNB may be referred to as an "eNB-type RSU", an RSU implemented in or by a gNB may be referred to as a "gNB-type RSU", etc.

[0119] In some embodiments, one or more elements of the access node 600 may be configured to perform operations including generating, for a user equipment (UE) served by a serving cell, a message including (i) synchronization signal block (SSB) information associated with a target SSB burst of the target cell and (ii) a flag indicating that the UE is authorized to use the timing of the reference cell to derive an index of the target SSB burst, where the target SSB burst includes one or more SSBs, and preparing the message for transmission to the UE.

[0120] In the description herein, for convenience, various components may be described as performing a task or tasks. Such descriptions should be construed to include the phrase "configured to." It is expressly intended that the description of a component as being configured to perform one or more tasks does not enforce 35 U.S.C. 112(f) interpretation of the component.

[0121] For one or more embodiments, at least one of the components described in one or more of the preceding figures may be configured to perform one or more of the operations, techniques, processes, or methods as described in the example section below. For example, the baseband circuitry described above in connection with one or more of the preceding figures may be configured to operate according to one or more of the examples described below. As another example, circuitry associated with a UE, base station, network element, etc. as described above in connection with one or more of the preceding figures may be configured to operate according to one or more of the examples described below in the example section.

[0122] Although the above embodiments have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated, and it is intended that the following claims be interpreted to embrace all such variations and modifications.

[0123] It is understood that use of personally identifiable information should comply with privacy policies and practices generally recognized as meeting or exceeding industry or governmental requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and handled in a manner that minimizes the risk of unintended or unauthorized access or use, and the nature of permitted uses should be clearly indicated to users.

Claims

1. 1. A method implemented by a user equipment (UE) served by a serving cell, comprising: receiving from the serving cell a message including (i) synchronization signal block (SSB) information associated with a target SSB burst of a target cell, and (ii) a flag indicating that the UE is authorized to use a reference cell's timing to derive an index of the target SSB burst, the target SSB burst including one or more SSBs; Calculating a frame boundary alignment tolerance (Δt) between the reference cell and the target cell; and determining an index of the target SSB burst based on the tolerance.

2. The method of claim 1 , wherein the SSB information includes a frequency of the target SSB burst and a subcarrier spacing of the target SSB burst.

3. 2. The method of claim 1, further comprising measuring at least a portion of the target SSB burst during a measurement window based on at least one of the tolerance ([Delta]t) or the SSB information.

4. Based on at least one of the tolerances (Δ), at least a portion of the target SSB burst is determined to have a time length of the measurement window.

4. The method of claim 3, comprising calculating window_length=length of 4 SSB symbols of the target cell+2*Δt.

5. Determining an index of the target SSB burst. determining a candidate position for a first SSB within the target SSB burst based on the tolerance; and determining the index of the target SSB burst based on at least one of the candidate position of the first SSB or the measured portion of the target SSB index.

6. Calculating the tolerance (Δt) 2. The method of claim 1, comprising calculating as Δt=min(2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell).

7. Calculating the tolerance (Δt) 2. The method of claim 1, comprising calculating as Δt=2 SSB symbols of the target cell.

8. The step of calculating the tolerance (Δt) comprises: receiving signaling indicating a formula to use to calculate said tolerance; and calculating the tolerance based on the signaled formula.

9. 9. The method of claim 8, wherein the signaled equation is one of: i) Δt = min (2 SSB symbols of the reference cell, 1 PDSCH symbol of the reference cell); and (ii) Δt = 2 SSB symbols of the target cell.

10. 2. The method of claim 1, wherein the tolerance comprises an individual tolerance defined for each of a plurality of predefined SSB pattern cases.

11. Calculating the tolerance (Δt) determining a first SSB pattern case associated with the target cell and a second SSB pattern case associated with the reference cell; determining that the first SSB pattern has a greater subcarrier spacing than the second SSB pattern; and calculating the tolerance based on the individual tolerance associated with the first SSB pattern.

12. 11. The method of claim 10, wherein the plurality of predefined SSB pattern cases includes: 【Table 1】

13. The individual tolerances defined for case B, case D, or case E are: The method of claim 12, wherein Δt is calculated as = 2 SSB symbols.

14. The individual tolerances defined for case A or case C are The method of claim 12, wherein Δt is calculated as = 3 SSB symbols.

15. The individual tolerances defined for case F or case G are The method of claim 12, wherein Δt is calculated as = 3.5 SSB symbols.

16. The individual tolerances defined for cases B or D and two consecutive SSBs transmitted are: The method of claim 12, wherein Δt is calculated as = 6 SSB symbols.

17. 1. A method implemented by a base station of a serving cell, comprising: generating a message from the user equipment (UE) served by the serving cell, the message including: (i) synchronization signal block (SSB) information associated with a target SSB burst of a target cell; and (ii) a flag indicating that the UE is authorized to use a reference cell's timing to derive an index of the target SSB burst, the target SSB burst including one or more SSBs; and preparing the message for transmission to the UE.

18. 18. The method of claim 17, wherein the SSB information includes a frequency of the target SSB burst and a subcarrier spacing of the target SSB burst.

19. A non-transitory computer storage medium encoded with instructions that, when executed by one or more computers, cause the one or more computers to perform the method of any one of claims 1 to 18.

20. A system comprising one or more computers and one or more storage devices storing instructions operable, when executed by the one or more computers, to cause the one or more computers to perform a method according to any one of claims 1 to 18.

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