System and method of providing a medium access control scheduler
A method of operating an uplink scheduler as part of a medium access control scheduler on a satellite includes selecting, from a plurality of user terminals, a first number of zero-bandwidth request user terminals from the plurality of user terminals, selecting, from the plurality of user terminals, a second number of non-zero-bandwidth request user terminals from the plurality of user terminals, binning the second number of non-zero-bandwidth request user terminals into a plurality of bins based on a respective bandwidth requirement for each non-zero-bandwidth request user terminal and based on a minimum user terminal grant and allocating, according to a grant allocation algorithm, a respective grant of radio resources in an uplink frame to each user terminal of the plurality of user terminals into a respective bin of the plurality of bins in an order associated with increasing bandwidth needs. A downlink scheduler is also disclosed.
1. A method for operating a user terminal communicating with a satellite in a communication system, the method comprising:
receiving a downlink map from the satellite, the downlink map identifying a respective grant of radio resources in a downlink frame for the user terminal and at least one additional user terminal representing a set of user terminals, wherein the downlink map is generated by the satellite performing operations comprising:
allocating the respective grant of radio resources in the downlink frame to each user terminal of the set of user terminals into a respective bin of a plurality of bins associated with bandwidth needs to yield an allocation;
generating, based on the allocation, the downlink map; and
receiving data in the downlink frame allocated for the user terminal based on the downlink map.
2. The method of claim 1 , wherein the satellite, when generating the downlink map, performs further operations comprising:
selecting a number of non-zero buffer occupancy user terminal/service-flow-identification (SFID) pairs in a round robin fashion from a plurality of user terminals to yield a set of user terminals; and
binning each user terminal of the set of user terminals into a plurality of bins based on a respective bandwidth requirement for each user terminal and based on a minimum user terminal grant.
3. The method of claim 2 , wherein the satellite, when generating the downlink map, performs further operations comprising applying the downlink map for data broadcasted to the set of user terminals.
4. The method of claim 2 , wherein the satellite allocates the respective grant of radio resources by:
(1) computing a user terminal grant based on an available modulation symbol value divided by a number of user terminals in the set of user terminals;
(2) adding an unused modulation symbol to the user terminal grant to yield an unused user terminal grant;
(3) obtaining the unused user terminal grant after packing service data units (SDUs);
(4) calculating a number of unused code words and residual code word modulation symbols from the unused user terminal grant;
(5) updating an available OFDM (orthogonal frequency division multiplexing) symbol value to be: available_ofdm_symb−(a user terminal grant−(unused_code_words*mod_symb_per_code_word));
(6) updating the unused modulation symbol to be equal to the unused modulation symbol plus a residual code word modulation symbol value; and
(7) repeating steps (1) to (6) until all of the number of non-zero buffer occupancy user terminal/SFID pairs are allocated.
5. The method of claim 4 , wherein the satellite allocates the respective grant of radio resources by a grant allocation algorithm that packs user terminals with similar or a same MCS into a same downlink frame.
6. The method of claim 1 , further comprising, at the satellite, calculating a required number of modulation symbols for each user terminal from the set of user terminals.
7. The method of claim 1 , further comprising, at the satellite, determining one or more of a multiplexing extended header (MEH) modulation and coding scheme (MCS), a minimum of all user terminal MCSs, a generic MAC header (GMH) size and a MEH header size.
8. A user terminal communicating with a satellite in a communication system, the user terminal comprising:
processor; and
a computer-readable storage device storing instructions which, when executed by the processor, cause the processor to perform operations comprising:
receiving a downlink map from the satellite, the downlink map identifying a respective grant of radio resources in a downlink frame for the user terminal and at least one additional user terminal representing a set of user terminals, wherein the downlink map is generated by the satellite performing operations comprising:
allocating the respective grant of radio resources in the downlink frame to each user terminal of the set of user terminals into a respective bin of a plurality of bins associated with bandwidth needs to yield an allocation; and
generating, based on the allocation, the downlink map; and
receiving data in the downlink frame allocated for the user terminal based on the downlink map.
9. The user terminal of claim 8 , wherein the satellite further performs operations comprising:
selecting a number of non-zero buffer occupancy user terminal/service-flow-identification (SFID) pairs in a round robin fashion from a plurality of user terminals to yield a set of user terminals; and
binning each user terminal of the set of user terminals into a plurality of bins based on a respective bandwidth requirement for each user terminal and based on a minimum user terminal grant.
10. A method of operating a user terminal of a plurality of user terminals communicating with a satellite, the method comprising:
receiving an uplink map from the satellite, the uplink map that identifying a respective grant of radio resources in an uplink frame to the user terminal as part of a plurality of user terminals, wherein the uplink map is generated by the satellite performing operations comprising:
binning a number of non-zero-bandwidth request user terminals in the plurality of user terminals into a plurality of bins based on a respective bandwidth requirement for each non-zero-bandwidth request user terminal;
allocating a respective grant of radio resources in a respective uplink frame to each respective user terminal of the plurality of user terminals into a respective bin of the plurality of bins associated with bandwidth needs to yield an allocation;
generating, based on the allocation, the uplink map; and
transmitting data from the user terminal on the uplink frame according to the uplink map.
11. The method of claim 10 , wherein the satellite further performs operations comprising:
selecting, from the plurality of user terminals, a number of zero-bandwidth request user terminals from the plurality of user terminals;
selecting, from the plurality of user terminals, the number of non-zero-bandwidth request user terminals from the plurality of user terminals; and
broadcasting the uplink map to the plurality of user terminals.
12. The method of claim 10 , wherein the respective bandwidth requirement for a respective user terminal is calculated as a number of required modulation symbols based on a number of code words times a number of symbols per code word plus a number of modulation symbols.
13. The method of claim 12 , wherein the number of code words is calculated based on a total bandwidth required for the respective user terminal, a minimum or maximum size reported in a medium access control multiplexing extended header, and a bits per code word value.
14. The method of claim 10 , wherein a minimum user terminal grant is calculated based on a minimum number of orthogonal frequency division multiplexing symbols, a number of frequency domain resource blocks, an uplink maximum user terminals per burst and a number of sub carriers per resource block.
15. The method of claim 10 , wherein the plurality of bins comprises one or more of a bandwidth request allocation bin for user terminals with zero-bandwidth requests, a low-bandwidth bin, a medium-bandwidth bin and a high-bandwidth bin.
16. The method of claim 15 , wherein binning the number of non-zero-bandwidth request user terminals from the plurality of user terminals comprises binning into one of the low-bandwidth bin, the medium-bandwidth bin and the high-bandwidth bin based on the respective bandwidth requirement for each non-zero-bandwidth request user terminal and based on a minimum user terminal grant further comprises:
if a respective non-zero-bandwidth request user terminal has a respective bandwidth requirement that is less than a minimum user terminal grant, then adding the respective non-zero-bandwidth request user terminal to the low-bandwidth bin;
if the respective non-zero-bandwidth request user terminal has a respective bandwidth requirement that is greater than the minimum user terminal grant and less than 2 times the minimum user terminal grant, then adding the respective non-zero-bandwidth request user terminal to the medium-bandwidth bin; and
otherwise, adding the respective non-zero-bandwidth request user terminal to a high-bandwidth bin.
17. A user terminal communicating with a satellite in a communication system, the user terminal comprising:
a processor; and
a computer-readable storage device storing instructions which, when executed by the processor, cause the processor to perform operations comprising:
receiving an uplink map from the satellite, the uplink map that identifying a respective grant of radio resources in an uplink frame to the user terminal as part of a plurality of user terminals, wherein the uplink map is generated by the satellite performing operations comprising:
binning a number of non-zero-bandwidth request user terminals in the plurality of user terminals into a plurality of bins based on a respective bandwidth requirement for each non-zero-bandwidth request user terminal;
allocating a respective grant of radio resources in a respective uplink frame to each respective user terminal of the plurality of user terminals into a respective bin of the plurality of bins associated with bandwidth needs to yield an allocation;
generating, based on the allocation, the uplink map; and
transmitting data from the user terminal on the uplink frame according to the uplink map.
18. The user terminal of claim 17 , wherein the satellite further performs operations comprising:
selecting, from the plurality of user terminals, a number of zero-bandwidth request user terminals from the plurality of user terminals;
selecting, from the plurality of user terminals, the number of non-zero-bandwidth request user terminals from the plurality of user terminals; and
broadcasting the uplink map to the plurality of user terminals.
19. The user terminal of claim 17 , wherein the respective bandwidth requirement for a respective user terminal is calculated as a number of required modulation symbols based on a number of code words times a number of symbols per code word plus a number of modulation symbols.
20. The user terminal of claim 19 , wherein the number of code words is calculated based on a total bandwidth required for the respective user terminal, a minimum or maximum size reported in a medium access control multiplexing extended header, and a bits per code word value.
21. The user terminal of claim 17 , wherein a minimum user terminal grant is calculated based on a minimum number of orthogonal frequency division multiplexing symbols, a number of frequency domain resource blocks, an uplink maximum user terminals per burst and a number of sub carriers per resource block.
22. The user terminal of claim 17 , wherein the plurality of bins comprises one or more of a bandwidth request allocation bin for user terminals with zero-bandwidth requests, a low-bandwidth bin, a medium-bandwidth bin and a high-bandwidth bin.
23. The user terminal of claim 22 , wherein binning the number of non-zero-bandwidth request user terminals from the plurality of user terminals comprises binning into one of the low-bandwidth bin, the medium-bandwidth bin and the high-bandwidth bin based on the respective bandwidth requirement for each non-zero-bandwidth request user terminal and based on a minimum user terminal grant further comprises:
if a respective non-zero-bandwidth request user terminal has a respective bandwidth requirement that is less than a minimum user terminal grant, then adding the respective non-zero-bandwidth request user terminal to the low-bandwidth bin;
if the respective non-zero-bandwidth request user terminal has a respective bandwidth requirement that is greater than the minimum user terminal grant and less than 2 times the minimum user terminal grant, then adding the respective non-zero-bandwidth request user terminal to the medium-bandwidth bin; and
otherwise, adding the respective non-zero-bandwidth request user terminal to the high-bandwidth bin.