Channel Estimation in a Multi-Channel Communication System Using Pilot Signals Having Quasi-Orthogonal Subpilots

An apparatus comprising:

• an access node comprising a plurality of transmitters adapted for communication with at least one receiver;
• the access node being operative to transmit pilot signals from respective associated ones of the transmitters, to estimate channel coefficients between the transmitters and the receiver, and to utilize the estimated channel coefficients to control at least one data signal sent by at least one of the transmitters;
• wherein the pilot signals are partitioned into a plurality of sets of pilot signals such that pilot signals from the same set have respective subpilots that are orthogonal to one another and pilot signals from different sets have respective subpilots that are not orthogonal to one another but are instead quasi-orthogonal to one another;
• and
• wherein the pilot signals are associated with the respective transmitters based on said partitioning of the pilot signals into sets.

A communication system comprising:

• a plurality of transmitters;
• and
• a plurality of receivers;
• wherein the transmitters are adapted for communication with respective ones of the receivers over respective channels;
• wherein pilot signals are transmitted from respective associated ones of the transmitters, and channel coefficients between the transmitters and a given one of the receivers are estimated and utilized to control at least one data signal sent by at least one of the transmitters to at least one of the receivers;
• wherein the pilot signals are partitioned into a plurality of sets of pilot signals such that pilot signals from the same set have respective subpilots that are orthogonal to one another and pilot signals from different sets have respective subpilots that are not orthogonal to one another but are instead quasi-orthogonal to one another;
• and
• wherein the pilot signals are associated with the respective transmitters based on said partitioning of the pilot signals into sets.