Codebook subset selection
The present invention provides for an improved application of signal strength weightings in a SDMA sectorized cellular network. The improved signal strength weightings application is conducted through the improved selection of weightings from a new codebook subset or by the selection of weightings from a larger codebook subset. In a further embodiment, an antenna beam index or bit map can be used to select the best beam(s) in a SDMA sectorized cellular network. In another embodiment, a field or factor in an uplink or downlink transmission packet can designate which directional transmission beam is best suited for the transmission or when the directional transmission beam should be activated.
1. A method for operating a first communication station to facilitate communication between the first communication station and a remote communication station, wherein the first communication station includes a plurality of antennas, the method comprising:
acquiring information about the channel condition between the first communication station and the remote communication station;
selecting a codebook weighting matrix for the remote communication station from a designated subset of a codebook based on an analysis of data including the channel condition information, wherein the codebook includes at least six codebook weighting matrices, wherein each of the codebook weighting matrices includes one or more layer-related columns, wherein each of the layer-related columns includes a plurality of complex weight values having absolute value less than or equal to one;
precoding one or more layer signals based on the selected codebook weighting matrix to obtain transmit signals for the respective antennas; and
transmitting the transmit signals respectively through the antennas.
2. The method of claim 1 , wherein the complex weight values of the codebook weighting matrices in the designed subset have constant modulus.
3. The method of claim 1 , wherein, in one or more cases, said selection of the codebook weighting matrix is determined by the channel condition information.
4. The method of claim 1 , wherein, in one or more cases, said selection of the codebook weighting matrix overrides a codebook weight matrix indicated by the channel condition information.
5. The method of claim 1 , wherein the at least six codebook weighting matrices include at least one antenna selection codeword.
6. The method of claim 1 , wherein said acquiring information about the channel condition is based on an application of a direction finding algorithm to transmissions from the remote communication station.
7. The method of claim 1 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein, for a given sector in which the remote communication station resides, the first communication station is configured so that all UEs in the given sector that are configured for two-antenna based PMI feedback are constrained to use codebook weighting matrices from within the designated subset.
8. The method of claim 1 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein all UEs in the same sector as the remote communication station are required to use the designated subset.
9. A base station to facilitate communication with a remote communication station, the base station comprising:
a plurality of antennas; and
circuitry configured to:
acquire information about the channel condition between the base station and the remote communication station;
select a codebook weighting matrix for the remote communication station from a designated subset of a codebook based on an analysis of data including the channel condition information, wherein the codebook includes at least six codebook weighting matrices, wherein each of the codebook weighting matrices includes one or more layer-related columns, wherein each of the layer-related columns includes a plurality of complex weight values having absolute value less than or equal to one;
precode one or more layer signals based on the selected codebook weighting matrix to obtain transmit signals for the respective antennas; and
transmit the transmit signals respectively through the antennas.
10. The base station of claim 9 , wherein the complex weight values of the codebook weighting matrices in the designed subset have constant modulus.
11. The base station of claim 9 , wherein, in one or more cases, said selection of the codebook weighting matrix is determined by the channel condition information.
12. The base station of claim 9 , wherein, in one or more cases, said selection of the codebook weighting matrix overrides a codebook weight matrix indicated by the channel condition information.
13. The base station of claim 9 , wherein the at least six codebook weighting matrices include at least one antenna selection codeword.
14. The base station of claim 9 , wherein said acquiring information about the channel condition is based on an application of a direction finding algorithm to tranmsissions from the remote communication station.
15. The base station of claim 9 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein, for a given sector in which the remote communication station resides, the circuitry is configured so that all UEs in the given sector that are configured for two-antenna based PMI feedback are constrained to use codebook weighting matrices from within the designated subset.
16. The base station of claim 9 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein the circuitry is configured so that all UEs in the same sector as the remote communication station are required to use the designated subset.
17. A non-transitory memory medium for operating a first communication station to facilitate communication between the first communication station and a remote communication station, wherein the first communication station includes a plurality of antennas, wherein the memory medium stores program instructions, wherein the program instructions, when executed by a processor, cause the processor to implement:
acquiring information about the channel condition between the first communication station and the remote communication station;
selecting a codebook weighting matrix for the remote communication station from a designated subset of a codebook based on an analysis of data including the channel condition information, wherein the codebook includes at least six codebook weighting matrices, wherein each of the codebook weighting matrices includes one or more layer-related columns, wherein each of the layer-related columns includes a plurality of complex weight values having absolute value less than or equal to one;
precoding one or more layer signals based on the selected codebook weighting matrix to obtain transmit signals for the respective antennas; and
transmitting the transmit signals respectively through the antennas.
18. The memory medium of claim 17 , wherein the complex weight values of the codebook weighting matrices in the designed subset have constant modulus.
19. The memory medium of 17 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein, for a given sector in which the remote communication station resides, the first communication station is configured so that all UEs in the given sector that are configured for two-antenna based PMI feedback are constrained to use codebook weighting matrices from within the designated subset.
20. The memory medium of claim 17 , wherein the designated subset consists of six codebook weighting matrices, wherein the complex weight values of the six codebook weighting matrices have constant modulus, wherein the first communication station is configured so that all UEs in the same sector as the remote communication station are required to use the designated subset.