US 2008/0303699 A1 · MIMO wireless precoding system robust to power imbalance

Abstract

The present invention relates to methods and apparatus for preventing power imbalance in a multiple input multiple output (MIMO) wireless precoding system. According to one aspect of the present invention, a codebook is constructed with a first subset of codewords that are constant modulus matrices, and a second subset of codewords that are non-constant modulus matrices. A mapping scheme is established between the first subset of codewords and the second subset of codewords. When a unit of user equipment feeds back a first codeword that is a non-constant modulus matrix, the Node-B may replace the first codewords with a second codeword that is selected from the first subset of codewords and that corresponds to the first codeword in accordance with the mapping scheme.

Claims32

Dependent claims

A method for communication, the method comprising the steps of:

generating a codebook comprising a first set of codewords and a second set of codewords, with each one of the first set of codewords being a constant modulus matrix, and each one of the second set of codewords being a non-constant modulus matrix;
establishing a mapping scheme from the codewords in the first set of codewords to the codewords in the second set of codewords;
transmitting, via a first node to a second node, information regarding a first codeword selected from the codebook in dependence upon a condition of a transmission channel between first node and the second node in a multiple input multiple output communication system;
determining, at the second node, whether the first codeword selected by the first node is a constant modulus matrix or a non-constant modulus matrix;
and
when the second node determines that the first codeword selected by the first node is a non-constant modulus matrix, replacing, by the second node, the first codeword with a second codeword that is selected from the first set of codewords and that corresponds to the first codeword in accordance with the mapping scheme established.

3 more elements

A method for communication, the method comprising the steps of:

generating codebooks for various transmission ranks in a communication system, with each of the codebooks being one of a first type codebook in which all of the codewords are constant modulus matrices, and a second type codebook in which a first half of the codewords are constant modulus matrices, and a second half of the codewords are non-constant modulus matrices;
establishing a mapping scheme, for each one of the second type codebooks, from the first half of the codewords to the second half of the codewords;
transmitting, via a first node to a second node, information regarding a transmission rank and information regarding a first codeword selected from a codebook corresponding to the transmission rank, with the first codeword being selected in dependence upon a condition of a transmission channel between first node and the second node in a multiple input multiple output communication system;
determining, at the second node, whether the first codeword selected by the first node is a constant modulus matrix or a non-constant modulus matrix;
when the second node determines that the first codeword selected by the first node is a constant modulus matrix, precoding and transmitting a data packet, at the second node, by using the first codeword;
and
when the second node determines that the first codeword selected by the first node is a non-constant modulus matrix, replacing, by the second node, the first codeword with a second codeword that is selected from the first half of the codewords in the codebook and that corresponds to the first codeword in accordance with the mapping scheme established corresponding to the codebook, and preceding and transmitting a data packet by using the second codeword.

4 more elements

A method for communication, the method comprising the steps of:

generating a codebook comprising a plurality of codewords, with each of the codewords being a constant modulus matrix;
transmitting a reference signal, from a second node to a first node, via a plurality of transmission antennas;
in response to the reference signal received, feeding back, via the first node to the second node, a polarization indicator indicating whether the first node receives energy from a first subset of the transmission antennas that are oriented with a first polarization, or from a second subset of the transmission antennas that are oriented with a second polarization, or from both of the first subset and the second subset of the transmission antennas;
transmitting, from the second node to the first node, an alternative indicator indicating which one of two alternatives to be used by the first node to calculate a channel quality indicator and a preceding matrix index;
calculating the channel quality indicator and the precoding matrix index at the first node by using one of two alternatives, with:
in the first alternative, calculating the channel quality indicator and the precoding matrix index by using the codewords in the codebook;
and
in the second alternative, calculating the channel quality indicator and the precoding matrix index in dependence upon the polarization indicator, with:
when the polarization indicator indicates that the first node receives energy from the first subset of the transmission, revising all of the codewords in the codebook by replacing the rows that correspond to the second subset of the transmission antennas with zero values, and calculating the channel quality indicator and the preceding matrix index by using the revised codewords;
when the polarization indicator indicates that the first node receives energy from the second subset of the transmission, revising all of the codewords in the codebook by replacing the rows that correspond to the first subset of the transmission antennas with zero values, and calculating the channel quality indicator and the preceding matrix index by using the revised codewords;
and
when the polarization indicator indicates that the first node receives energy from both of the first subset and the second subset of the transmission antennas, calculating the channel quality indicator and the preceding matrix index by using the codewords in the codebook without any revision;
transmitting, via the first node to the second node, the calculated channel indicator and the precoding matrix index;
and
in response to the channel indicator, the precoding matrix index and the alternative indicator received, preceding and transmitting a data packet in dependence upon the alternative indicator, with:
when the alternative indicator indicates that the first alternative is used for calculating the channel indicator and the preceding matrix index, precoding the data packet by using a codeword selected from the plurality of codewords in the codebook in accordance with the precoding matrix index, and transmitting the precoded data packet via the plurality of transmission antennas;
and
when the alternative indicator indicates that the second alternative is used for calculating the channel indicator and the precoding matrix index, precoding the data packet by using a codeword selected from the plurality of codewords in the codebook in accordance with the precoding matrix index, and transmitting the precoded data packet in dependence upon the polarization indicator, with
when the polarization indicator indicates that the first node receives energy from the first subset of the transmission antennas, transmitting the precoded data packet via at least one of the first subset of the transmission antennas;
when the polarization indicator indicates that the first node receives energy from the second subset of the transmission antennas, transmitting the precoded data packet via at least one of the second subset of the transmission antennas;
and
when the polarization indicator indicates that the first node receives energy from both of the first subset and the second subset of the transmission antennas, transmitting the precoded data packet via at least one of the first subset and the second subset of transmission antennas.

19 more elements

Dependencies are inferred from the claim text.

MIMO wireless precoding system robust to power imbalance

Life of this patent

MIMO wireless precoding system robust to power imbalance

Life of this patent

Abstract

Claims32