Transmission scheduling for TDMA networks

• US 7,596,113 B1
• Filed: 09/28/2006
• Issued: 09/29/2009
• Est. Priority Date: 09/28/2006
• Status: Active Grant

• Current Assignee: L3 Technologies, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Inventors: Giallorenzi, Thomas R., Kingston, Samuel C., Harris, Johnny M.
• Primary Examiner(s): Harper; Vincent P
• Assistant Examiner(s): COSME, NATASHA W
• Application Number:
  US11/540,138
• Time in Patent Office: 1,097 Days
• Field of Search: 370/320
• US Class Current: 370/320
• CPC Class Codes: H04W 56/003 Arrangements to increase tolerance to errors in transmission or reception timing
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver

Abstract

A technique for scheduling transmissions for a plurality of transmitters in a TDMA network is described. The technique includes assigning guard time between each pair of successive transmitters, where the guard time is related to the propagation delay between the pair of successive transmitters. Total guard time is minimized by selecting an order of transmission for the plurality of transmitters to minimize the total guard time.

Claims

1. A method of scheduling transmissions for a plurality of transmitters within a time division multiple access communications network, comprising the steps of:

determining a location of each of the plurality of transmitters, the location suitable for use in determining a distance between pairs of transmitters;

selecting an order of transmission for the plurality of transmitters to minimize a sum of all distances between each successive pair of transmitters; and

assigning a guard time between each successive pair of transmitters, the guard time being equal to or greater than a propagation delay between each successive pair of transmitters and less than a propagation delay across the entire network.

2. The method of claim 1, wherein the guard time is non-negative.

3. The method of claim 1, wherein the step of determining a location of each of the plurality of transmitters comprises communicating the location of each transmitter to a controller.

4. The method of claim 1, wherein the step of selecting an order of transmission comprises the step of finding a nearest neighbor for each transmitter.

5. The method of claim 4, wherein the step of selecting an order of transmission comprises the step of finding a next nearest neighbor for each transmitter.

6. The method of claim 1, wherein the step of assigning a guard time between each successive pair of transmitters comprises the step of setting the guard time equal to the propagation delay between the locations of each successive pair of transmitters.

7. The method of claim 1, wherein the step of assigning a guard time between each successive pair of transmitters comprises the step of setting the guard time equal to a sum of the propagation delay between the locations of each successive pair of transmitters and a predetermined constant.

8. The method of claim 1, wherein the step of assigning a guard time between each successive pair of transmitters comprises the step of setting the guard time proportional to the propagation delay between the locations of each successive pair of transmitters.

9. The method of claim 1, further comprising the step of scheduling a transmission time for each transmitter based on the guard times.

10. The method of claim 9, wherein the step of scheduling a transmission time comprises the step of scheduling each successive pair of transmitters to transmit at times separated by an interval equal to the length of a transmission of the first transmitter in the successive pair plus the guard time between the successive pair of transmitters.

11. The method of claim 9, wherein the step of scheduling a transmission time comprises the step of communicating scheduled transmit times from a controller to the plurality of transmitters.

12. The method of claim 1, further comprising the step of updating the location of at least one of the plurality of transmitters to obtain at least one updated location.

13. The method of claim 12, further comprising reordering the order of transmission for the plurality of transmitters based on the at least one updated location to minimize a sum of distances between the locations of each successive pair of transmitters.

14. The method of claim 1, further comprising scheduling each of the plurality of transmitters for transmission once per frame interval.

15. The method of claim 1, further comprising scheduling only a subset of the plurality of transmitters for transmission within a frame interval, the subset consisting of those transmitters which have data to transmit.

16. The method of claim 1, further comprising scheduling a transmission for an additional transmitter within the time division multiple access communication network sequentially in time after one of the plurality of transmitters.

17. A method of managing transmission sequencing and guard times for a plurality of transmitters within a time division multiple access communication network, comprising the steps of:

scheduling a first one of the plurality of transmitters to transmit at a first scheduled time within a frame; and

repeatedly;

selecting a next transmitter that has not already been scheduled to transmit within the frame from the plurality of transmitters, and

scheduling the next transmitter for transmission at a next scheduled time,

until each of the plurality of transmitters has been scheduled in the frame,

wherein the next scheduled time includes a guard time equal to or greater than the propagation delay between the next transmitter and the immediately preceding transmitter.

18. The method of claim 17, wherein the step of scheduling the next scheduled time further comprises the step of ordering the scheduled times to minimize a total guard time equal to the sum of guard times between each successive pair of transmitters.

19. The method of claim 17, wherein the guard time is substantially less than the propagation delay across the entire network.

20. The method of claim 17, wherein the guard time between successive pairs of transmitters is equal to the propagation delay between the successive pair of transmitters plus a predetermined constant.

21. A time slot controller for a time division multiple access communication network having a plurality of transmitter units, comprising:

a solver configured to accept a plurality of locations of the transmitter units and find a transmit ordering of the plurality of transmitter units that produces a minimum of the total distance, wherein the total distance equals the sum of distances between the locations of each pair of successive transmitter units;

a time slot assigner coupled to the solver to accept the transmit ordering and configured to schedule a plurality of transmission times, wherein the plurality of transmit times includes guard times between each successive pair of transmitter units equal to a propagation delay between the locations of each pair of successive transmitter units; and

a communications unit coupled to the time slot assigner to accept the plurality of transmission times and configured to communicate the plurality of transmission times to the plurality of transmitter units.

22. A time division multiple access system comprising:

a plurality of transmitter units, each transmitter unit configured to transmit data during a dynamically assigned time slot; and

a scheduler, in communication with the plurality of transmitter units, the scheduler configured to;

dynamically assign time slots to the plurality of transmitter units, wherein time slot assignments are assigned to minimize total guard time, where the guard time between successive time slots is related to the propagation delay between the transmitter units scheduled for transmission in the successive time slots, and

communicate time slot assignments to the plurality of transmitter units.

23. The system of claim 22, wherein the scheduler is located within one of the plurality of transmitter units.

24. The system of claim 22, wherein each transmitter unit is capable of operating as the scheduler and one transmitter unit is active as the scheduler at any given time.

25. The system of claim 24, wherein each transmitter unit takes turns operating as the scheduler.

26. The system of claim 24, wherein each transmitter unit communicates updated position information to the scheduler.

27. The system of claim 22, further comprising a controller, wherein the controller includes the scheduler.

28. The system of claim 27, wherein the scheduler is assigned a time slot during which the scheduler transmits time slot assignments to the plurality of transmitter units.