Channel-assisted iterative precoder selection

A device for providing a quantized representation of a precoding matrix for a codebook-based precoder, said precoder being operable for precoding information symbols for multi-antenna transmission from a transmitter to a receiver in a mobile communications network, said device comprising:

• a channel estimator that estimates a channel matrix representing multi-antenna channel characteristics between said transmitter and said receiver in said mobile communications network, said transmitter having at least two antennas and said receiver having at least one antenna;
• an iterative vector selector that performs an iterative vector selection procedure for iteratively selecting precoding vectors for said precoding matrix, wherein said iterative vector selector comprises:
• a channel-assisted performance evaluator that evaluates, at each of a number of iterations of said iterative vector selection procedure, performance of each one of a set of candidate vectors included in a given vector codebook with respect to a predetermined performance measure that is dependent on the estimated channel matrix;
• and
• a vector selector that selects, at each of a number of iterations of said iterative vector selection procedure, one of said set of candidate vectors as a respective precoding vector for said precoding matrix based on the evaluated performance;
• and
• a quantization compiler that compiles information representative of a set of selected precoding vectors to form said quantized representation of said precoding matrix for transmission to said transmitter.