Rank step-down for MIMO SCW design employing HARQ
Systems and methodologies are described that facilitate reducing rank (e.g., of a user device) as a number of transmissions there from increases. Such rank step-down can improve interference resistance and facilitate maintaining code rate despite transmission propagation. Additionally, rank step-down information can be encoded along with CQI information to generate a 5-bit CQI signal that can facilitate updating a user's rank upon each CQI transmission (e.g., approximately every 5 ms). The described systems and/or methods can be employed in a single code word (SCW) wireless communication environment with a hybrid automatic request (HARQ) protocol.
1. A method of performing rank step-down to preserve code rate across multiple transmissions in a transmission frame, comprising:
generating a plurality of coded symbols at an access point;
updating a MIMO transmission rank in a deterministic manner to reflect a rank step down sequence such that the MIMO transmission rank is reduced with successive transmissions,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
demultiplexing the coded symbols to determine a value, M, of MIMO layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1≦M≦M T ; and
spatially mapping M layers using a spatial mapping matrix.
2. The method of claim 1 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
3. The method of claim 1 , wherein the spatial mapping matrix is a permutation matrix.
4. The method of claim 3 , further comprising generating the spatial mapping matrix as an M T ×M matrix.
5. The method of claim 1 , further comprising transmitting the coded symbols using a packet format that has a predefined rank.
6. The method of claim 1 , further comprising transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
7. A method of performing rank step down in a transmission frame at an access point in a wireless communication environment, comprising:
generating a plurality of coded symbols at an access point;
updating a rank for a MIMO transmission to a user device in a deterministic manner to reflect a rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions according to the rank step-down sequence;
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
demultiplexing the coded symbols to generate M MIMO transmission layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1≦M≦M T ; and
spatially mapping the M T MIMO transmission layers using a spatial mapping matrix.
8. The method of claim 7 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
9. The method of claim 7 , wherein the spatial mapping matrix is a permutation matrix.
10. The method of claim 9 , further comprising generating the spatial mapping matrix as an M T ×M T matrix.
11. The method of claim 7 , further comprising transmitting the coded symbols using a packet format that has a predefined rank.
12. The method of claim 7 , further comprising transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
13. A non-transitory computer readable medium having stored thereon computer executable instructions for:
generating a plurality of coded symbols at an access point;
updating a MIMO transmission rank in a deterministic manner to reflect rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
demultiplexing the coded symbols to determine a value, M, of MIMO layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1≦M≦M T ; and
spatially mapping M layers using a spatial mapping matrix.
14. The non-transitory computer-readable medium of claim 13 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
15. The non-transitory computer-readable medium of claim 13 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
16. The non-transitory computer-readable medium of claim 15 , further comprising instructions for generating the spatial mapping matrix as an M T ×M matrix.
17. The non-transitory computer-readable medium of claim 13 , further comprising instructions for transmitting the coded symbols using a packet format that has a predefined rank.
18. The non-transitory computer-readable medium of claim 13 , further comprising instructions for transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
19. A processor executing from a non-transitory computer readable medium comprising computer-executable instructions for:
generating a plurality of coded symbols at an access point;
updating a MIMO transmission rank in a deterministic manner to reflect a rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions according to the rank step-down sequence,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
demultiplexing the coded symbols to determine a, value, M, of MIMO layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1≦M≦M T ; and
spatially mapping M layers using a spatial mapping matrix.
20. The processor of claim 19 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
21. The processor of claim 19 , wherein the spatial mapping matrix is a permutation matrix.
22. The processor of claim 21 , wherein the non-transitory computer readable medium further comprises instructions for generating the spatial mapping matrix as an M T ×M matrix.
23. The processor of claim 19 , wherein the non-transitory computer readable medium further comprises instructions for transmitting the coded symbols using a packet format that has a predefined rank.
24. The processor of claim 19 , wherein the non-transitory computer readable medium further comprises instructions for transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
25. An apparatus that facilitates performing rank step-down to preserve code rate across multiple transmissions in a transmission frame, comprising:
a processor configured to:
generate a plurality of coded symbols at an access point;
update a MIMO transmission rank in a deterministic manner to reflect a rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
demultiplex the coded symbols to determine a value, M, of MIMO layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1≦M≦M T ; and
spatially map M layers using a spatial mapping matrix.
26. The apparatus of claim 25 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
27. The apparatus of claim 25 , wherein the spatial mapping matrix is a permutation matrix.
28. The apparatus of claim 27 , wherein the processor is further configured to generate the spatial mapping matrix as an M T ×M matrix.
29. The apparatus of claim 25 , wherein the processor is further configured to transmit the coded symbols using a packet format that has a predefined rank.
30. The apparatus of claim 25 , wherein the processor is further configured to transmit a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
31. A wireless communication apparatus, comprising:
means for generating a plurality of coded symbols at an access point;
means for updating a MIMO transmission rank in a deterministic manner to reflect a rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
means for demultiplexing the coded symbols to determine a value, M, of MIMO layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1<M<M T ; and
means for spatially mapping M layers using a spatial mapping matrix.
32. The apparatus of claim 31 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
33. The apparatus of claim 31 , wherein the spatial mapping matrix is a permutation matrix.
34. The apparatus of claim 33 , further comprising means for generating the spatial mapping matrix as an M T ×M matrix.
35. The apparatus of claim 31 , further comprising means for transmitting the coded symbols using a packet format that has a predefined rank.
36. The apparatus of claim 31 , further comprising means for transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.
37. A wireless communication apparatus, comprising:
means for generating a plurality of coded symbols at an access point;
means for updating a rank for a MIMO transmission to a user device in a deterministic manner to reflect a rank step-down sequence such that the MIMO transmission rank is reduced with successive transmissions according to the rank step-down sequence,
wherein the MIMO transmission rank is determined based on spectral efficiency, modulation, code rate, and transmission number;
means for demultiplexing the coded symbols to generate M MIMO transmission layers with information symbols and (M T −M) MIMO layers with erasure symbols, where M and M T are integers and 1<M<M T ; and
means for spatially mapping the M T MIMO transmission layers using a spatial mapping matrix.
38. The apparatus of claim 37 , wherein the spatial mapping matrix is a generalized delay diversity matrix.
39. The apparatus of claim 37 , wherein the spatial mapping matrix is a permutation matrix.
40. The apparatus of claim 39 , further comprising means for generating the spatial mapping matrix as an M T ×M T matrix.
41. The apparatus of claim 34 , further comprising means for transmitting the coded symbols using a packet format that has a predefined rank.
42. The apparatus of claim 34 , further comprising means for transmitting a rank indicator signal to an access terminal with the coded symbols to indicate to the access terminal a rank to use when decoding the coded symbols.