Granted Patent B2

US 12,395,953 · App. 18/470,218 · Granted Aug 19, 2025

Inventors: Sujuan Feng (Frankfurt, DE); Lilei Wang (Beijing, CN); Hidetoshi Suzuki (Kanagawa, JP); Prateek Basu Mallick (Hessen, DE)

Assignee: Sun Patent Trust

H04W56/0015H04W56/0025H04B7/15507H04B17/309

Abstract

Claims (33)

1. A communication system comprising:

a synchronization source, which, in operation, transmits a synchronization signal; and

a user equipment comprising:

a receiver, which, in operation, receives the synchronization signal from the synchronization source; and

circuitry, which, in operation,

measures a quality of the received synchronization signal;

determines the synchronization source as a synchronization source candidate when the measured quality exceeds a defined threshold;

periodically selects a synchronization reference User Equipment (UE) from among the synchronization source candidate(s), within every defined period set by a reselection timer, according to a following priority order:

first, a UE that is the synchronization source candidate being in-coverage and having a highest result of the measured quality;

second, a UE that is the synchronization source candidate having transmitted the synchronization signal, which is a network originated signal, and having a highest result of the measured quality; and

third, a UE that is the synchronization source candidate being out-of-coverage and having transmitted the synchronization signal, which is a network independent signal, and having a highest result of the measured quality; and

uses the synchronization signal of the selected synchronization reference UE to adjust timing of transmission or reception of data.

2. The communication system according to claim 1 , wherein the user equipment comprises a transmitter which transmits a synchronization signal generated at the user equipment responsive to the circuitry determining the user equipment is out-of-coverage and determining no synchronization source candidate.

3. The communication system according to claim 1 , wherein the circuitry, in operation, determines whether the received synchronization signal is a network originated signal or a network independent signal based on the received synchronization signal.

4. The communication system according to claim 1 , wherein the circuitry, in operation, measures the quality of the received synchronization signal based on a received power wherein the defined threshold is a defined hysteresis.

5. The communication system according to claim 1 , wherein the circuitry, in operation, adjusts the timing of reception or transmission within every defined period.

6. The communication system according to claim 1 , wherein the defined threshold is preconfigured on the user equipment.

7. The communication system according to claim 1 , wherein the circuitry, in operation, uses another defined threshold different from the defined threshold.

8. A method performed by a communication system, which includes a user equipment and a synchronization source, the method comprising:

receiving, by the user equipment, a synchronization signal from the synchronization source;

measuring, by the user equipment, a quality of the received synchronization signal;

determining, by the user equipment, the synchronization source as a synchronization source candidate when the measured quality exceeds a defined threshold;

periodically selecting, by the user equipment, a synchronization reference User Equipment (UE) from among the synchronization source candidate(s), within every defined period set by a reselection timer, according to a following priority order:

first, a UE that is the synchronization source candidate being in-coverage and having a highest result of the measured quality;

second, a UE that is the synchronization source candidate having transmitted the synchronization signal, which is a network originated signal, and having a highest result of the measured quality; and

third, a UE that is the synchronization source candidate being out-of-coverage and having transmitted the synchronization signal, which is a network independent signal, and having a highest result of the measured quality; and

using, by the user equipment, the synchronization signal of the selected synchronization reference UE to adjust timing of transmission or reception of data.

9. The method according to claim 8 , which comprises transmitting, by the user equipment, a synchronization signal generated at the user equipment when the user equipment determines it is out-of-coverage and determines no synchronization source candidate.

10. The method according to claim 8 , wherein whether the received synchronization signal is a network originated signal or a network independent signal is determined, by the user equipment, based on the received synchronization signal.

11. The method according to claim 8 , wherein the quality of the received synchronization signal is measured, by the user equipment, based on a received power wherein the defined threshold is a defined hysteresis.

12. The method according to claim 8 , wherein the timing of reception or transmission is adjusted, by the user equipment, within every defined period.

13. The method according to claim 8 , wherein the defined threshold is preconfigured on the user equipment.

14. The method according to claim 8 , which comprises using, by the user equipment, another defined threshold different from the defined threshold.

Continuity (4)

References Cited (60)