A Primary Wireless Communications Device, a Secondary Wireless Communications Device and Methods for Synchronization of Device-to-Device Wireless Communication

A method performed by a secondary wireless communications device for synchronization of Device-to-Device (D2D) wireless communication with a primary wireless communications device, wherein the secondary wireless communications device comprising a first Radio Frequency (RF) receiver for wireless communication with the primary wireless communications device and a second RF receiver operating at a reduced energy consumption relative to the first RF receiver, the method comprises:

• receiving, with the second RF receiver via a D2D wireless communications channel, a single-tone synchronization signal for synchronization of the secondary wireless communications device to the primary wireless communications device, wherein the single-tone synchronization signal is modulated with a data sequence;
• tuning a common reference oscillator (XO) of the first RF receiver and the second RF receiver using a frequency difference between a carrier frequency of the single-tone synchronization signal and a Local Oscillator (LO) frequency of the second RF receiver, such that the frequency difference obtains a target value;
• synchronizing the secondary wireless communications device in time with the primary wireless communications device based on the second RF receiver correlating the modulating data sequence with a reference data sequence in a time domain;
• and
• communicating, by the first RF receiver based on the tuned XO and the synchronization in time, control signals and/or data signals via the D2D wireless communications channel with the primary wireless communications device.

A secondary wireless communications device configured for synchronization of Device-to-Device (D2D) wireless communication with a primary wireless communications device, wherein the secondary wireless communications device comprises:

• a first Radio Frequency (RF) receiver for wireless communication with the primary wireless communications device;
• a second RF receiver operating at a reduced energy consumption relative to the first RF receiver;
• and
• processing circuitry operably coupled to the first and second RF receivers, wherein the processing circuitry and the first and second RF receivers are configured to:
• receive, with the second RF receiver via a D2D wireless communications channel, a single-tone synchronization signal for synchronization of the secondary wireless communications device to the primary wireless communications device, wherein the single-tone synchronization signal is modulated with a data sequence;
• tune a common reference oscillator (XO) of the first RF receiver and the second RF receiver using a frequency difference between a carrier frequency of the single-tone synchronization signal and a Local Oscillator (LO) frequency of the second RF receiver, such that the frequency difference obtains a target value;
• synchronize the secondary wireless communications device in time with the primary wireless communications device based on the second RF receiver correlating the modulating data sequence with a reference data sequence in a time domain;
• and
• communicate, by the first RF receiver based on the tuned XO and the synchronization in time, control signals and/or data signals via the D2D wireless communications channel with the primary wireless communications device.