Optimizations for zero-forcing precoding
View Patent ↗Massive MIMO systems provide impressive spectral efficiencies through beam forming techniques such as Zero-Forcing Precoding (ZFP). Unfortunately, ZFP imposes a considerable computational burden for each additional user. Relationships between the antennas, the users, and the environment must be rapidly, and accurately, reassessed during ZFP on an ongoing basis. Brute force approaches to these reassessments may be unfeasible for certain hardware and design conditions. Accordingly, various of the proposed embodiments implement representational optimizations which reduce the computational burden for each reassessment. Some embodiments employ “dynamic sectorization”, whereby the serviced environment is divided into regions and the corresponding representation is modified to reduce the computations of each reassessment. A backplane, antenna separation/directivity and thresholds for environment noise may each be adjusted to reduce the computational burden.
1. A communications system, comprising:
a plurality of antennas;
a backplane configured to physically separate a first group of the plurality of antennas and a second group of the plurality of antennas;
at least one processor;
at least one memory comprising instructions configured to cause the at least one processor to:
transmit a pilot signal from an antenna of the plurality of antennas;
receive feedback from a user device based upon the pilot signal;
generate a channel matrix based upon the feedback;
assign zero values to entries in the channel matrix below a threshold;
determine a precoder matrix based upon the channel matrix;
adjust the backplane upon determination of the precoder matrix; and
adjust a directional pattern of a third group of the plurality of antennas based upon the precoder matrix.
2. The communications system of claim 1 , wherein the backplane is configured to be dynamically adjusted.
3. The communications system of claim 1 , wherein the antennas are directional.
4. The communications system of claim 1 , wherein determining the precoder matrix comprises using Cholesky Factorization and the Minimum Degree Algorithm upon assigning the zero values.
5. The communications system of claim 1 , wherein the plurality of antennas comprises patch elements.
6. The communications system of claim 5 , wherein each of the patch elements has a length of approximately half the transmission wavelength.
7. The communications system of claim 1 , wherein the plurality of antennas comprises more than 90 antennas.
8. A computer-implemented method, comprising:
transmitting a pilot signal from an antenna of a plurality of antennas, the first group of the plurality of antennas separated with a backplane from a second group of the plurality of antennas;
receiving feedback from a user device based upon the pilot signal;
generating a channel matrix based upon the feedback;
assigning zero values to entries in the channel matrix below a threshold;
determining a precoder matrix based upon the channel matrix, wherein determining the precoder matrix comprises using Cholesky Factorization and a Minimum Degree Algorithm upon assigning the zero values; and
adjusting a directional pattern of a third group of the plurality of antennas based upon the computed precoder matrix.
9. The computer-implemented method of claim 8 , further comprising adjusting the backplane upon determination of the precoder matrix.
10. The computer-implemented method of claim 8 , wherein the plurality of antennas comprises patch elements.
11. The computer-implemented method of claim 10 , wherein each of the patch elements has a length of approximately half the transmission wavelength.
12. The computer-implemented method of claim 8 , wherein the plurality of antennas comprises more than 90 antennas.
13. A non-transitory computer-readable medium, comprising instructions configured to cause a communication system to:
transmit a pilot signal from an antenna of a plurality of antennas, the plurality of antennas comprising first group and a second group of antennas, the first group of the plurality of antennas separated with a backplane from the second group of the plurality of antennas, wherein the plurality of antennas comprises patch elements, and wherein each of the patch elements has a length of approximately half the transmission wavelength;
receive feedback from a user device based on the pilot signal;
generate a channel matrix based upon the feedback;
assign zero values to entries in the channel matrix below a threshold;
determine a precoder matrix based upon the channel matrix; and
adjust a directional pattern of a third group of the plurality of antennas based upon the precoder matrix.
14. The non-transitory computer-readable medium of claim 13 , wherein determining the precoder matrix comprises using Cholesky Factorization and a Minimum Degree Algorithm upon assigning the zero values.
15. The non-transitory computer-readable medium of claim 13 , further comprising adjusting the backplane upon determination of the precoder matrix.
16. The non-transitory computer-readable medium of claim 13 , wherein the plurality of antennas comprises more than 90 antennas.