Precoding codebooks for MIMO communication systems
A method includes configuring a transmitter and a receiver with first precoding matrices for mapping onto N transmit antenna ports of the transmitter R1≦N data streams. Each first precoding matrix is derived from respective second and third precoding matrices, which are configured for mapping onto respective numbers of antenna ports that are less than N. A set of precoding matrices is defined for mapping r<R1 data streams onto the transmit antenna ports. Each matrix in the set includes a subset of columns of a given matrix selected from the first precoding matrices. A candidate matrix is included in the set when the candidate matrix cannot be expressed as a weighted permutation of the columns of another matrix in the set. The data streams are mapped onto the transmit antenna ports using a precoding scheme based on one of the first precoding matrices.
1. A method for communication, comprising:
configuring a communication system that includes a transmitter and a receiver with first precoding matrices for mapping onto N transmit antenna ports of the transmitter R1 data streams, R1≦N, each of at least some of the first precoding matrices derived from respective second and third precoding matrices configured for mapping onto respective numbers of transmit antenna ports that are less than N, and defining a set of the precoding matrices for mapping r data streams onto the N transmit antenna ports, r<R1, each precoding matrix in the set comprising a subset of columns of a given matrix selected from the first precoding matrices, while including in the set a candidate precoding matrix when the candidate precoding matrix cannot be expressed as a weighted permutation of the columns of another precoding matrix in the set;
mapping the data streams onto the N transmit antenna ports using a precoding scheme based on one of the first precoding matrices; and
transmitting the mapped data streams over the N transmit antenna ports from the transmitter to the receiver.
2. The method according to claim 1 , wherein configuring the communication system comprises producing a given first precoding matrix by computing a Kronecker product between a respective second precoding matrix, selected from among the second precoding matrices and a respective third precoding matrix selected from among the third precoding matrices.
3. The method according to claim 1 , wherein mapping the data streams comprises mapping the r data streams onto the N transmit antenna ports using one of the precoding matrices in the set.
4. The method according to claim 1 , wherein transmitting the mapped data streams comprises transmitting a signal conforming to a Long Term Evolution Advanced (LTE-A) specification.
5. The method according to claim 1 , wherein mapping the data streams comprises selecting the precoding scheme based on feedback from the receiver.
6. The method according to claim 1 , wherein N=8.
7. The method according to claim 1 , wherein configuring the communication system comprises storing in the communication system only the second and third precoding matrices, and computing the one of the first precoding matrices in the transmitter based on the stored second and third precoding matrices.
8. A method for communication, comprising:
configuring a communication system that includes a transmitter and a receiver with first precoding matrices for mapping up to eight data streams onto eight transmit antenna ports of the transmitter, each of at least some of the first precoding matrices derived from respective second precoding matrices that are defined for mapping onto two antenna ports and respective third precoding matrices that are defined for mapping onto four antenna ports;
mapping the data streams onto the eight transmit antenna ports using a precoding scheme based on one of the first precoding matrices; and
transmitting the mapped data streams over the eight transmit antenna ports from the transmitter to the receiver.
9. A method for communication, comprising:
configuring a communication system that includes a transmitter and a receiver with first precoding matrices for mapping up to eight data streams onto eight transmit antenna ports of the transmitter, each of at least some of the first precoding matrices derived from respective second precoding matrices that are defined for mapping onto four antenna ports and third precoding matrices that are defined for mapping onto two antenna ports;
mapping the data streams onto the eight transmit antenna ports using a precoding scheme based on one of the first precoding matrices; and
transmitting the mapped data streams over the eight transmit antenna ports from the transmitter to the receiver.
10. A communication apparatus, comprising:
N transmit antenna ports; and
a transmitter, which is configured to accept a definition of first precoding matrices for mapping onto N transmit antenna ports R1 data streams, R1≦N, each of at least some of the first precoding matrices derived from respective second and third precoding matrices configured for mapping onto respective numbers of transmit antenna ports that are less than N, to define a set of the precoding matrices for mapping r data streams onto the N transmit antenna ports, r<R1, each precoding matrix in the set comprising a subset of columns of a given matrix selected from the first precoding matrices, while including a candidate precoding matrix in the set when the candidate precoding matrix cannot be expressed as a weighted permutation of the columns of another precoding matrix in the set, to map the data streams onto the N transmit antenna ports using a precoding scheme based on one of the first precoding matrices, and to transmit the mapped data streams over the N transmit antenna ports to a receiver.
11. The apparatus according to claim 10 , wherein the transmitter is configured to produce a given first precoding matrix by computing a Kronecker product between a respective second precoding matrix, selected from among the second precoding matrices and a respective third precoding matrix selected from among the third precoding matrices.
12. The apparatus according to claim 10 , wherein the transmitter is configured to select the precoding scheme based on feedback from the receiver.
13. The apparatus according to claim 10 , wherein the transmitter is configured to transmit the mapped data streams in a signal conforming to a Long Term Evolution Advanced (LTE-A) specification.
14. A mobile communication terminal comprising the communication apparatus of claim 10 .
15. A chipset for processing signals in a mobile communication terminal, comprising the communication apparatus of claim 10 .
16. The apparatus according to claim 10 , wherein the transmitter comprises a memory and is configured to store in the memory only the second and third precoding matrices, and to compute the one of the first precoding matrices based on the stored second and third precoding matrices.