Synchronization for sidelink based on prioritization of synchronization signals

Patent metadata

Field	Value
Publication number	US-11533695-B2
Application number	US-201917259126-A
Country	US
Kind code	B2
Filing date	Aug 8, 2019
Priority date	Aug 10, 2018
Publication date	Dec 20, 2022
Grant date	Dec 20, 2022

Abstract

Embodiments of a User Equipment (UE) and methods of communication are generally described herein. The UE may attempt to detect synchronization signals, including Long Term Evolution (LTE) synchronization signals from eNBs, New Radio (NR) synchronization signals from gNBs, and sidelink synchronization signals (SLSSs) from other UEs. The UE may prioritize an LTE synchronization signal over an SLSS, and may prioritize an NR synchronization signal over an SLSS. If the UE does not detect an LTE synchronization signal or an NR synchronization signal, the UE may select an SLSS. The UE may prioritize an SLSS from a UE that is directly synchronized to an eNB or a gNB over an SLSS from another UE that is indirectly synchronized to an eNB or a gNB.

First claim

What is claimed is:

1. An apparatus comprising:
a memory; and
at least one processor coupled to the memory, configured to, when executing instructions stored in the memory, cause the apparatus to:
detect at least two synchronization signals, including at least one Long Term Evolution (LTE) synchronization signal, at least one New Radio (NR) synchronization signal, at least one sidelink synchronization signal (SLSS), or any combination thereof; and
select one of the at least two detected synchronization signals for usage in determination of a reference timing for sidelink transmissions, wherein selecting one of the at least two detected synchronization signals comprises:
if an LTE synchronization signal and an SLSS are detected, selecting the LTE synchronization signal,
if an NR synchronization signal and an SLSS are detected, selecting the NR synchronization signal, and
if an LTE synchronization signal or an NR synchronization signal is not detected, and if two or more SLSSs are detected, selecting one of the detected SLSSs based on a selection criterion wherein an SLSS from a user equipment (UE) that is directly synchronized to a network is selected over an SLSS from another UE that is indirectly synchronized to a network.

2. The apparatus according to claim 1 , wherein the at least one processor further configured to:
determine the reference timing for sidelink transmissions based on the selected synchronization signal; and
encode a physical sidelink shared channel (PSSCH), physical sidelink control channel (PSCCH), or SLSS for transmission in accordance with the determined reference timing, wherein the PSSCH, PSCCH, or SLSS are encoded for transmission over an NR PC5 interface to another UE.

3. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
if the at least two detected synchronization signals are LTE synchronization signals or NR synchronization signals:
select, for usage in determination of the reference timing, a synchronization signal for which a corresponding signal quality measurement is highest.

4. The apparatus according to claim 3 , wherein the signal quality measurement is a reference signal received power (RSRP).

5. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
select one of the at least two detected synchronization signals for usage in determination of the reference timing based on a set of prioritization rules, wherein the set includes one or more of:
a first prioritization rule based on types of the at least two detected synchronization signals, wherein LTE synchronization signals and NR synchronization signals are of equal priority and are of higher priority than SLSSs;
a second prioritization rule based on synchronization hop information, wherein SLSSs from UEs directly synchronized to the network are of higher priority than SLSSs from UEs that are indirectly synchronized to the network,
a third prioritization rule based on stationarity, wherein SLSSs from stationary UEs are of higher priority than SLSSs from non-stationary UEs, and
a tie-breaking rule based on corresponding signal quality measurements.

6. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
if an LTE synchronization signal or an NR synchronization signal is not detected, and if two SLSSs are detected, wherein synchronization hop information of both SLSSs is the same:
if one of the detected SLSSs is received from a stationary UE and the other detected SLSS is received from a non-stationary UE, select the SLSS from the stationary UE for usage in the determination of the reference timing.

7. The apparatus according to claim 6 , wherein the at least one processor is further configured to:
detect SLSSs from:
non-stationary UEs, and
stationary UEs, including road side units (RSUs).

8. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
encode, for transmission, an SLSS that includes one or more of: a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH),
encode the S-PSS based on a single sequence.

9. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
encode, for transmission, an SLSS that includes one or more of: a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH),
encode the S-PSS based on two sequences,
encode the S-PSS based on one or more of: a synchronization hop count, an original synchronization source type, and an in-coverage/out-of-coverage state.

10. The apparatus according to claim 1 , wherein resources for SLSS transmission are configured in accordance with one or more of:
a center frequency is an arbitrary value preconfigured within a carrier, and
resources are periodically allocated in time with periodicity taken from a set of periodicities, each of which is a multiple of system frame number (SFN) or hyperframe number (HFN).

11. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
encode a predetermined signal for transmission at the beginning of each slot of a plurality of slots in accordance with a common transmission by multiple UEs occupying a same slot for sidelink communication,
wherein the predetermined signal is in a set that includes at least a sidelink primary synchronization signal (S-PSS), and a sidelink secondary synchronization signal (S-SSS).

12. The apparatus according to claim 1 , wherein: the at least one processor is configured to:
attempt to detect global navigation satellite system (GNSS) signals,
in a GNSS-based prioritization, if a GNSS synchronization signal is detected, select the GNSS synchronization signal for usage in determination of the reference timing; and
in a network based prioritization, if an LTE synchronization signal or an NR synchronization signal is not detected, and if a GNSS synchronization signal is detected, select the GNSS synchronization signal for usage in determination of the reference timing.

13. The apparatus according to claim 1 , wherein the at least one processor is further configured to:
detect the LTE synchronization signals in resources allocated for LTE communication, wherein the LTE synchronization signals are detected in accordance with an LTE protocol; and
detect the NR synchronization signals in resources allocated for NR communication, wherein the NR synchronization signals are detected in accordance with an NR protocol.

14. The apparatus according to claim 1 , wherein the LTE synchronization signals include one or more of: a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and a cell-specific reference signal (CRS).

15. The apparatus according to claim 1 , wherein the sidelink transmission include one or more of:
a vehicle-to-vehicle (V2V) transmission, a vehicle-to-everything (V2X) transmission, and an enhanced V2X (eV2X) transmission.

16. The apparatus of claim 1 ,
wherein the at least one processor includes a baseband processor to select one of the at least two detected synchronization signals, and
wherein the apparatus further comprises a transceiver to receive the at least two detected synchronization signals.

17. A non-transitory computer-readable storage medium that stores instructions for execution by pr

Assignees

• Apple Inc

Inventors

• Khoryaev Alexey
• Parron Jerome
• Shilov Mikhail
• Panteleev Sergey

Classifications

• H04W72/30

  Resource management for broadcast services · CPC title

• H04W4/40

  for vehicles, e.g. vehicle-to-pedestrians [V2P] · CPC title

• H04W56/0015 Primary

  one node acting as a reference for the others · CPC title

• H04W24/10

  Scheduling measurement reports {; Arrangements for measurement reports} · CPC title

• H04W84/047

  using dedicated repeater stations · CPC title