Method of maintaining coherency of a precoding channel in a communication network and associated apparatus

A method of transmitting at least one of a pilot and data weighted by a precoding matrix, said method carried out in a base station of a wireless communication system, wherein the base station obtains channel status information, the method comprising:

• performing matrix decomposition to the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• performing linear transformation to the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• transmitting to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix
• wherein performing the matrix decomposition comprises:
• performing QR decomposition to the channel status information, wherein a Q matrix resulting from the QR decomposition is the initial precoding matrix.

A method of transmitting at least one of a pilot and data weighted by a precoding matrix, said method carried out in a base station of a wireless communication system, wherein the base station obtains channel status information, the method comprising:

• performing matrix decomposition to the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• performing linear transformation to the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• wherein performing the linear transformation comprises:
• obtaining a first correcting matrix according to an initial precoding channel under a condition of weighting by the initial precoding matrix;
• and
• performing linear transformation to the initial precoding matrix with the first correcting matrix to obtain the linerarly transformed precoding matrix such that a phase of the corrected precoding channel under the condition of weighting by the linearly transformed precoding matrix is continuous;
• and
• transmitting to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix.

A method of transmitting at least one of a pilot and data weighted by a precoding matrix, said method carried out in a base station of a wireless communication system, wherein the base station obtains channel status information, the method comprising:

• performing matrix decomposition to the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• performing linear transformation to the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• wherein performing the linear transformation comprises:
• selecting a first correcting matrix according to an expected maximum multipath delay in time domain;
• and
• performing linear transformation to the initial precoding matrix with the first correcting matrix to obtain the linearly transformed precoding matrix, such that an amplitude of the precoding channel under the condition of weighting by the linearly transformed precoding matrix is smooth;
• and
• transmitting to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix.

A method of transmitting at least one of a pilot and data weighted by a precoding matrix, said method carried out in a base station of a wireless communication system, wherein the base station obtains channel status information, the method comprising:

• performing matrix decomposition to the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• performing linear transformation to the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• transmitting to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix;
• wherein the channel under the condition of weighting of the initial precoding matrix is an initial precoding channel, the associated information comprises eigenvalue matrix of the channel, and performing linear transformation further comprises:
• obtaining eigenvalue matrix of the initial precoding channel according to the initial precoding channel;
• and
• adjusting amplitude of each eigenvalue in the eigenvalue matrix such that amplitudes of the eigenvalue matrix are smooth.

A processing apparatus for transmitting at least one of a pilot and data weighted by a precoding matrix in a base station of a wireless communication system, wherein the base station obtains channel status information, the apparatus comprising:

• an initial precoding matrix obtaining part that performs a matrix decomposition on the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• a correcting part that performs a linear transformation to on the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• a transmitter that transmits to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix.

A processing for transmitting at least one of a pilot and data weighted by a precoding matrix in a base station of a wireless communication system, wherein the base station obtains channel status information, the apparatus comprising:

• an initial precoding matrix obtaining part that performs a matrix decomposition on the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• a correcting part that performs a linear transformation on the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• a transmitter that transmits to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix;
• wherein the correcting part comprises:
• a correcting matrix obtaining part that obtains a correcting matrix according to an initial precoding channel under the condition of weighting by the initial precoding matrix;
• and
• a phase rotation part that performs the linear transformation with the correcting matrix, such that a phase of the corrected precoding channel under the condition of weighting by the linearly transformed precoding matrix is continuous.

A processing apparatus for transmitting at least one of a pilot and data weighted by a precoding matrix in a base station of a wireless communication system, wherein the base station obtains channel status information, the apparatus comprising:

• an initial precoding matrix obtaining part that performs a matrix decomposition on the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• a correcting part that performs a linear transformation on the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• a transmitter that transmits to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix;
• wherein the correcting part comprises:
• a correcting matrix obtaining part that selects a correcting matrix according to an expected maximum multipath delay in time domain;
• and
• an amplitude smoothing part that performs the linear transformation with the correcting matrix, such that an amplitude of the corrected precoding channel under the condition of weighting by the linearly transformed precoding matrix is smooth.

A processing apparatus for transmitting at least one of a pilot and data weighted by a precoding matrix in a base station of a wireless communication system, wherein the base station obtains channel status information, the apparatus comprising:

• an initial precoding matrix obtaining part that performs a matrix decomposition on the channel status information to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique;
• a correcting part that performs a linear transformation on the initial precoding matrix to obtain a linearly transformed precoding matrix such that information associated with a corrected precoding channel under a condition of weighting by the linearly transformed precoding matrix maintains coherency;
• and
• a transmitter that transmits to a mobile terminal the at least one of the pilot and data weighted by the linearly transformed precoding matrix;
• wherein the channel under the condition of weighting by the initial precoding matrix is an initial precoding channel, the associated information comprises an eigenvalue matrix of the channel, and the correcting part comprises:
• an eigenvalue matrix obtaining part that obtains the eigenvalue matrix of the initial precoding channel according to the initial precoding channel;
• and
• the correcting part is further used to correct an amplitude of each eigenvalue in the eigenvalue matrix such that amplitude of the eigenvalue matrix is smooth.