System and method for downlink scheduling that optimizes downlink (DL) capacity

1. A method comprising:

scheduling, by a satellite, one or more protocol data units (PDUs) in a slot, wherein the one or more PDUs are associated with a first spreading factor (SF), wherein the first SF is lower than a second SF;

determining, by the satellite, whether available capacity of the slot is less than a predetermined threshold;

responsive to determining that the available capacity of the slot is not less than the predetermined threshold, scheduling, by the satellite, a second one or more PDUs in the slot, wherein the second one or more PDUs are associated with the second SF; and

responsive to determining that the available capacity of the slot is less than that the predetermined threshold, transmitting, by the satellite, the slot to an endpoint.

2. The method of claim 1 , further comprising ranking a plurality of PDUs from a lowest SF to a highest SF, wherein the plurality of PDUs includes the one or more PDUs and the second one or more PDUs.

3. The method of claim 1 , further comprising determining whether all PDUs associated with the first SF are scheduled in the slot.

4. The method of claim 1 , wherein the predetermined threshold is a size of the second one or more PDUs.

5. The method of claim 1 , further comprising calculating a SF for each of a plurality of PDUs, wherein the plurality of PDUs includes the one or more PDUs and the second one or more PDUs.

6. The method of claim 5 , wherein calculating the SF of each the plurality of PDUs is based on a received power level of a corresponding uplink PDU.

7. The method of claim 5 , further comprising updating the SF for each of the plurality of PDUs that is not scheduled in the slot.

8. The method of claim 7 , wherein the updated SF of each the plurality of PDUs is based on a second received power level of a second corresponding uplink PDU.

9. A method comprising:

calculating, by a satellite, a first spreading factor (SF) of a first one or more downlink (DL) protocol data units (PDUs) using a first received power of a first one or more uplink (UL) PDUs;

calculating, by the satellite, a second SF of a second one or more DL PDUs using a second received power of a second one or more UL PDUs, wherein the first SF is lower than the second SF;

scheduling, by the satellite, the first one or more DL PDUs in a slot based on the first SF being lower than the second SF; and

transmitting, by the satellite, the slot to an endpoint.

10. The method of claim 9 , further comprising determining, by the satellite, whether available capacity of the slot is less than a predetermined threshold.

11. The method of claim 10 , further comprising, responsive to determining that the available capacity of the slot is not less than the predetermined threshold, scheduling, by the satellite, the second one or more DL PDUs in the slot.

12. The method of claim 10 , further comprising, responsive to determining that the available capacity of the slot is less than that the predetermined threshold, scheduling the second one or more DL PDUs in a second slot transmitted after the slot is transmitted.

13. The method of claim 9 , further comprising receiving, by the satellite, from the endpoint, the first one or more uplink (UL) protocol data units (PDUs) at the first received power and the second one or more UL PDUs at the second received power.

14. A system comprising an endpoint and a satellite, wherein the satellite includes programmed instructions that, when executed, cause the satellite to:

schedule one or more protocol data units (PDUs) in a slot, wherein the one or more PDUs are associated with a first spreading factor (SF), wherein the first SF is lower than a second SF;

determine whether available capacity of the slot is less than a predetermined threshold;

responsive to determining that the available capacity of the slot is not less than the predetermined threshold, schedule a second one or more PDUs in the slot, wherein the second one or more PDUs are associated with the second SF; and

responsive to determining that the available capacity of the slot is less than that the predetermined threshold, transmit the slot to the endpoint.

15. The system of claim 14 , wherein the programmed instructions, when executed, further cause the satellite to rank a plurality of PDUs from a lowest SF to a highest SF, wherein the plurality of PDUs includes the one or more PDUs and the second one or more PDUs.

16. The system of claim 14 , wherein the predetermined threshold is a size of the second one or more PDUs.

17. The system of claim 14 , wherein the programmed instructions, when executed, further cause the satellite to calculate a SF for each of a plurality of PDUs, wherein the plurality of PDUs includes the one or more PDUs and the second one or more PDUs.

18. The system of claim 17 , wherein calculating the SF of each the plurality of PDUs is based on a received power level of a corresponding uplink PDU.

19. The system of claim 17 , wherein the programmed instructions, when executed, further cause the satellite to update the SF for each of the plurality of PDUs that is not scheduled in the slot.

20. The system of claim 19 , wherein the updated SF of each the plurality of PDUs is based on a second received power level of a second corresponding uplink PDU.