Channel estimation in mimo systems

A multiple-input multiple-output (MIMO) communication system comprising a downlink device and an uplink device configured to communicate over a communication channel;

• the uplink device comprising:
• a plurality of antennas;
• and
• a processing unit configured to:
• analyze a first channel vector representing channel gains between the downlink device and a first antenna of the uplink device in an angular domain to identify a set of angular domain support points each indicating a respective element of the first channel vector in the angular domain;
• generate from the set of angular domain support points a value vector containing the elements of the first channel vector in the angular domain representing the largest channel gains;
• and
• feed back to the downlink device an indication of the value vector;
• the downlink device comprising:
• a plurality of antennas;
• and
• a processing unit configured to:
• analyze a second channel vector representing channel gains between the downlink device and a second antenna of the uplink device in the angular domain to identify the set of angular domain support points;
• generate from the set of angular domain support points a transmit steering matrix;
• and
• generate an estimate of the first channel vector from the indication of the value vector fed back from the uplink device and the generated transmit steering matrix.