Timing synchronization signals and frequency synchronization signals

1 . An apparatus for wireless communications, comprising:

at least one transceiver;

at least one memory comprising executable instructions; and

one or more processors configured to execute the executable instructions to cause the apparatus to:

perform timing synchronization based on a first synchronization signal (SS);

perform frequency synchronization based on a second SS, wherein at least one of the first SS or the second SS is repeated with a configurable periodicity; and

communicate, via the at least one transceiver, after the performance of the timing synchronization and the performance of the frequency synchronization.

2 . The apparatus of claim 1 , wherein the second SS comprises at least one of a continuous wave (CW) signal or a power-optimized waveform (PoW) signal.

3 . The apparatus of claim 1 , wherein, to perform the frequency synchronization, the one or more processors are configured to cause the apparatus to perform the frequency synchronization based on a phase difference between the second SS and a local oscillator frequency.

4 . The apparatus of claim 1 , wherein the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, the first SS and second SS, via separate frequencies.

5 . The apparatus of claim 1 , wherein the one or more processors are further configured to cause the apparatus to process the first SS and the second SS together as a primary SS (PSS) that is repeated with a periodicity.

6 . The apparatus of claim 1 , wherein the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, the second SS in:

one or more fixed time slots;

time slots with a default periodicity; or

time slots with a configured periodicity.

7 . The apparatus of claim 6 , wherein the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, signaling indicating the configured periodicity.

8 . The apparatus of claim 1 , wherein:

the second SS is time division multiplexed with one or more other types of signals obtained in other time slots; and

the one or more processors are further configured to cause the apparatus to demultiplex the one or more other types of signals to receive the second SS.

9 . The apparatus of claim 1 , wherein the one or more processors are further configured to cause the apparatus to transmit, via the at least one transceiver, signaling to request transmission of at least one of the first SS or second SS.

10 . The apparatus of claim 1 , wherein:

the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, the second SS in at least one slot configured for wireless energy transfer (WET),

the one or more processors are further configured to cause the apparatus to harvest energy via the WET from the second SS; and

to communicate, the one or more processors are configured to cause the apparatus to communicate using the harvested energy.

11 . The apparatus of claim 1 , wherein the one or more processors are further configured to cause the apparatus to:

measure signal strengths of signals at multiple frequencies; and

select the second SS for performing the frequency synchronization, based on the measurement.

12 . The apparatus of claim 1 , wherein:

the communication comprises downlink receptions on a first frequency band and uplink transmissions on a second frequency band;

at least the second SS comprises a continuous wave (CW) signal; and

the one or more processors are further configured to cause the apparatus to:

receive, via the at least one transceiver, the CW signal on at least one of the first frequency band or the second frequency band;

measure signal strengths of a first CW signal on the first frequency band and a second CW signal on the second frequency band; and

select one of the first CW signal or second CW signal as the second SS based on the measuring.

13 . The apparatus of claim 1 , wherein the second SS comprises at least one of:

a first sine wave at a first frequency; or

at least a second sine wave at a second frequency.

14 . The apparatus of claim 13 , wherein, to perform the frequency synchronization, the one or more processors are configured to cause the apparatus to perform the frequency synchronization based on a difference between the second frequency and the first frequency.

15 . The apparatus of claim 13 , wherein the one or more processors are further configured to cause the apparatus to transmit, via the at least one transceiver, a backscattered signal based on a frequency shift relative to at least one of the first frequency or second frequency.

16 . The apparatus of claim 1 ,

wherein the apparatus is configured to operate as a user equipment (UE).

17 . An apparatus for wireless communications, comprising:

at least one transceiver;

at least one memory comprising executable instructions; and

one or more processors configured to execute the executable instructions to cause the apparatus to:

transmit, via the at least one transceiver, a first synchronization signal (SS) for timing synchronization;

transmit, via the at least one transceiver, a second SS for frequency synchronization, wherein at least one of the first SS or the second SS is repeated with a configurable periodicity; and

communicate, via the at least one transceiver, in accordance with the first SS and the second SS.

18 . The apparatus of claim 17 , wherein the second SS comprises at least one of a continuous wave (CW) signal or a power-optimized waveform (PoW) signal.

19 . The apparatus of claim 17 , wherein, to transmit the first SS and second SS, the one or more processors are configured to cause the apparatus to transmit the first SS and the second SS via separate frequencies.

20 . The apparatus of claim 17 , wherein, to transmit the first SS and the second SS, the one or more processors are configured to cause the apparatus to transmit the first SS and the second SS together as a primary SS (PSS) that is repeated with a periodicity.

21 . The apparatus of claim 17 , wherein, to transmit the second SS, the one or more processors are configured to cause the apparatus to transmit the second SS in:

one or more fixed time slots;

time slots with a default periodicity; or

time slots with a configured periodicity.

22 . The apparatus of claim 21 , wherein the one or more processors are further configured to cause the apparatus to transmit, via the at least one transceiver, signaling indicating the configured periodicity.

23 . The apparatus of claim 17 , wherein the one or more processors are further configured to cause the apparatus to at least one of:

time division multiplex the second SS with one or more other types of signals received in other time slots; or

transmit, via the at least one transceiver, in at least one slot configured for wireless energy transfer (WET).

24 . The apparatus of claim 17 , wherein the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, signaling to request transmission of at least one of the first SS or second SS.

25 . The apparatus of claim 17 , wherein:

the communication comprises downlink transmissions on a first frequency band and uplink receptions on a second frequency band;

at least the second SS comprises a continuous wave (CW) signal; and

to transmit the second SS, the one or more processors are configured to cause the apparatus to transmit the CW signal on at least one of the first frequency band or the second frequency band.

26 . The apparatus of claim 17 , wherein:

the second SS comprises at least one of:

a first sine wave at a first frequency; or

at least a second sine wave at a second frequency; and

the one or more processors are further configured to cause the apparatus to receive, via the at least one transceiver, a backscattered signal based on a frequency shift relative to at least one of the first frequency or second frequency.

27 . The apparatus of claim 17 ,

wherein the apparatus is configured to operate as a network entity.

28 . A method of wireless communications by a wireless node, comprising:

performing timing synchronization based on a first synchronization signal (SS);

performing frequency synchronization based on a second SS, wherein at least one of the first SS or the second SS is repeated with a configurable periodicity; and

communicating after performing the timing synchronization and performing the frequency synchronization.