Method and system for initial synchronization and collision avoidance in device to device communications without network coverage
AssigneeBlackBerry Limited
InventorsNam NGUYEN, Yufei Wu BLANKENSHIP, Sagar DHAKAL
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Abstract
A method at a first device for enabling a device-to-device wireless link, the method detecting whether a presence signal of a second device is received over a first time period, the presence signal of the second device having a time-slot boundary; and if the presence signal of the second device is not detected, initiating a time-slot boundary by the first device including: transmitting a first presence signal of the first device in a selected time-slot; and checking for an acknowledgment to the first presence signal.
Claims20
A method at a first device for enabling a device-to-device wireless link, the method comprising:
- detecting whether a presence signal of a second device is received;
- if the presence signal of the second device is not detected, initiating a time-slot boundary by the first device including:
- selecting a first presence signal based on Zadoff-Chu root sequence indexes different from ones used by a base station;
- and
- transmitting the first presence signal of the first device in a selected time-slot in a radio frame.
A device comprising:
- a processor;
- and
- a communications subsystem;
- wherein the processor and the communications subsystem cooperate to:
- detect whether a presence signal of a second device is received;
- if the presence signal of the second device is not detected, initiate a time-slot boundary by the first device including:
- selecting a first presence signal based on Zadoff-Chu root sequence indexes different from ones used by a base station;
- and
- transmitting the first presence signal of the first device in a selected time-slot in a radio frame.
A non-transitory computer readable medium having stored thereon executable code for execution by a processor of a device, the executable code comprising instructions for:
- detecting whether a presence signal of a second device is received;
- if the presence signal of the second device is not detected, initiating a time-slot boundary by the first device including:
- selecting a first presence signal based on Zadoff-Chu root sequence indexes different from ones used by a base station;
- and
- transmitting the first presence signal of the first device in a selected time-slot in a radio frame.
Dependencies are inferred from the claim text.