Pilot design for massive MIMO communication
View Patent ↗Embodiments recognize that in MIMO and M-MIMO systems, physical antennas tend to be closely spaced to each other (e.g., a grid). As a result, a spatial correlation typically exists between physical antennas as well as between transmissions from logical antenna ports. Embodiments exploit this characteristic to reduce the amount of pilot signaling needed to enable downlink channel estimation. Specifically, embodiments limit pilot signaling to only a subset of supported logical antenna ports and rely on spatial correlation information to interpolate channels from logic antenna ports for which no pilot signaling is used.
1. A method for determining a channel from a transmitter having a plurality of physical antennas and supporting a plurality of logical antenna ports, comprising:
determining a physical antenna spatial configuration of the transmitter;
determining a logical antenna port pilot transmission configuration of the transmitter that includes information regarding first logical antenna ports of the plurality of logical antenna ports with pilot signal transmission and second logical antenna ports of the plurality of logic antenna ports without pilot signal transmission;
receiving a pilot signal from one or more physical antennas of the plurality of physical antennas of the transmitter;
estimating a first channel for a first logical antenna port of the plurality of logical antenna ports, based on the received pilot signal; and
interpolating the first channel, using the physical antenna spatial configuration and the logical antenna port pilot transmission configuration, to estimate a second channel for a second logical antenna port of the plurality of logical antenna ports,
wherein pilot signals are transmitted using the first logical antenna ports and are not transmitted using the second logical antenna ports.
2. The method of claim 1 , wherein determining the physical antenna spatial configuration comprises receiving actual positions of the plurality of physical antennas of the transmitter.
3. The method of claim 1 , wherein determining the physical antenna spatial configuration comprises receiving relative positions of the plurality of physical antennas of the transmitter.
4. The method of claim 1 , wherein determining the physical antenna spatial configuration comprises receiving a spatial correlation matrix of the plurality of physical antennas of the transmitter.
5. The method of claim 1 , wherein determining the physical antenna spatial configuration comprises receiving a value from the transmitter, wherein the value identifies a known physical antenna configuration.
6. The method of claim 1 , wherein determining the physical antenna spatial configuration comprises determining the physical antenna spatial configuration based at least in part on Angle of Arrival (AoA) information associated with signals received from the transmitter.
7. The method of claim 1 , wherein the physical antenna spatial configuration includes a spatial correlation matrix of the plurality of physical antennas of the transmitter, the method further comprising:
receiving actual or relative positions of the plurality of physical antennas of the transmitter;
calculating the spatial correlation matrix of the plurality of physical antennas using the actual or relative positions of the plurality of physical antennas.
8. The method of claim 1 , wherein the first logical antenna port is mapped to a single physical antenna of the plurality of physical antennas, and wherein the first channel includes a channel from the single physical antenna.
9. The method of claim 1 , wherein the first logical antenna port is mapped to multiple physical antennas of the plurality of physical antennas, and wherein the first channel includes a composite channel from the multiple physical antennas.
10. The method of claim 8 , wherein the composite channel includes respective transmission weights associated with the multiple physical antennas.
11. A method for determining a channel from a transmitter having a plurality of physical antennas and supporting a plurality of logical antenna ports, the method comprising:
receiving spatial correlation information from the transmitter;
determining a logical antenna port pilot transmission configuration of the transmitter that includes information regarding first logical antenna ports of the plurality of logical antenna ports with pilot signal transmission and second logical antenna ports of the plurality of logic antenna ports without pilot signal transmission;
receiving a pilot signal from one or more physical antennas of the plurality of physical antennas of the transmitter;
estimating a first channel for a first logical antenna port of the plurality of logical antenna ports, based on the received pilot signal, wherein the first logical antenna port is mapped to the one or more physical antennas of the transmitter; and
interpolating the first channel to estimate a second channel for a second logical antenna port of the plurality of logical antenna ports.
12. The method of claim 11 , wherein interpolating the first channel comprises interpolating the first channel, using the spatial correlation information and the logical antenna port pilot transmission configuration, to estimate the second channel.
13. The method of claim 11 , wherein the spatial correlation information includes a physical antenna spatial configuration.
14. The method of claim 13 , wherein the physical antenna spatial configuration includes one of: actual positions of the plurality of physical antennas of the transmitter, relative positions of the plurality of physical antennas of the transmitter, a spatial correlation matrix of the plurality of physical antennas of the transmitter, and a value that identifies a known physical antenna configuration.
15. The method of claim 13 , wherein the spatial correlation information further includes a mapping of the plurality of logical antenna ports to the plurality of physical antennas.
16. The method of claim 11 , wherein the spatial correlation information includes a spatial correlation matrix of the plurality of logical antenna ports.
17. A method for determining a channel from a transmitter having a plurality of physical antennas and supporting a plurality of logical antenna ports, comprising:
determining a physical antenna spatial configuration of the transmitter;
determining a logical antenna port pilot transmission configuration of the transmitter;
receiving a pilot signal from one or more physical antennas of the plurality of physical antennas of the transmitter;
estimating a first channel for a first logical antenna port of the plurality of logical antenna ports, based on the received pilot signal; and
interpolating the first channel, using the physical antenna spatial configuration and the logical antenna port pilot transmission configuration, to estimate a second channel for a second logical antenna port of the plurality of logical antenna ports,
wherein the first logical antenna port is mapped to a single physical antenna of the plurality of physical antennas, and wherein the first channel includes a channel from the single physical antenna.
18. The method of claim 17 , wherein determining the physical antenna spatial configuration comprises receiving actual positions of the plurality of physical antennas of the transmitter.
19. The method of claim 17 , wherein determining the physical antenna spatial configuration comprises receiving relative positions of the plurality of physical antennas of the transmitter.
20. The method of claim 17 , wherein determining the physical antenna spatial configuration comprises receiving a spatial correlation matrix of the plurality of physical antennas of the transmitter.
21. The method of claim 17 , wherein determining the physical antenna spatial configuration comprises receiving a value from the transmitter, wherein the value identifies a known physical antenna configuration.