Coexistence of multiple air interface side-links on adjacent channels

1. A method for using different air interfaces on adjacent frequency channels for side-link communications, the method comprising:

transmitting a first side-link communication using a first subcarrier spacing on a first bandwidth part of a first side-link channel using a first air interface;

transmitting a second side-link communication using a second subcarrier spacing on a second bandwidth part of the first side-link channel using the first air interface, wherein:

the first bandwidth part of the first side-link channel is directly adjacent to a second side-link channel that uses the first subcarrier spacing; and

transmitting a third side-link communication using the first subcarrier spacing on the second side-link channel using a second air interface.

2. The method of claim 1 , further comprising:

receiving, by a user equipment (UE), subcarrier spacing assignment for the first air interface indicative of the first bandwidth part using the first subcarrier spacing and the second bandwidth part using the second subcarrier spacing.

3. The method of claim 2 , wherein the UE transmits the first side-link communication, the second side-link communication, and the third side-link communication.

4. The method of claim 3 , wherein the UE is a vehicle system.

5. The method of claim 4 , wherein the first side-link communication comprises a basic safety message (BSM).

6. The method of claim 1 , further comprising:

performing a smart scheduling technique to avoid interference between side-link communications on the first side-link channel in the first bandwidth part and the second bandwidth part.

7. The method of claim 1 , further comprising:

splitting, by an air interface management server system, the first side-link channel into the first bandwidth part and the second bandwidth part.

8. The method of claim 7 , further comprising:

assigning, by the air interface management server system, the first subcarrier spacing to the first bandwidth part of the first side-link channel; and

assigning, by the air interface management server system, the second subcarrier spacing to the second bandwidth part of the first side-link channel.

9. The method of claim 1 , the method further comprising:

determining, by an air interface management server system, to set subcarrier spacing in the first side-link channel based on subcarrier spacing of the second side-link channel.

10. The method of claim 1 , wherein the second air interface is a 4G LTE air interface.

11. The method of claim 10 , wherein the first air interface is a 5G NR air interface.

12. The method of claim 1 , further comprising:

changing the second subcarrier spacing to a third subcarrier spacing for the second bandwidth part of the first side-link channel while maintaining the first subcarrier spacing for the first bandwidth part of the first side-link channel.

13. The method of claim 1 , wherein the side-link communications are selected from a group consisting of:

vehicle to vehicle communications;

vehicle to infrastructure communications; and

vehicle to pedestrian communications.

14. A system, comprising:

one or more pieces of user equipment (UE), configured to:

transmit a first side-link communication using a first subcarrier spacing on a first bandwidth part of a first side-link channel using a first air interface;

transmit a second side-link communication using a second subcarrier spacing on a second bandwidth part of the first side-link channel using the first air interface, wherein:

the first bandwidth part of the first side-link channel is directly adjacent to a second side-link channel that uses the first subcarrier spacing; and

transmit a third side-link communication using the first subcarrier spacing on the second side-link channel using a second air interface.

15. The system of claim 14 , wherein the one or more pieces of UE are further configured to:

receive subcarrier spacing assignment for the first air interface indicative of the first bandwidth part using the first subcarrier spacing and the second bandwidth part using the second subcarrier spacing.

16. The system of claim 14 , wherein the one or more pieces of UE are selected from the group consisting of: vehicle communication systems; infrastructure communication systems; and pedestrian systems.

17. The system of claim 14 , further comprising an air interface management system, configured to:

assign the first subcarrier spacing to the first bandwidth part of the first side-link channel; and

assign the second subcarrier spacing to the second bandwidth part of the first side-link channel.

18. The system of claim 14 , wherein the first side-link communication, the second side-link communication, and the third side-link communication comprises a basic safety message (BSM).

19. The system of claim 14 , wherein:

the first air interface is a 5G New Radio (NR) air interface; and

the second air interface is a 4G Long Term Evolution (LTE) air interface.

20. A non-transitory processor-readable medium for user equipment, comprising processor-readable instructions configured to cause one or more processors to:

transmit a first side-link communication using a first subcarrier spacing on a first bandwidth part of a first side-link channel using a first air interface;

transmit a second side-link communication using a second subcarrier spacing on a second bandwidth part of the first side-link channel using the first air interface, wherein:

the first bandwidth part of the first side-link channel is directly adjacent to a second side-link channel that uses the first subcarrier spacing; and

transmit a third side-link communication using the first subcarrier spacing on the second side-link channel using a second air interface.