An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver. The access node is 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. 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. The pilot signals are associated with the respective transmitters based on the partitioning of the pilot signals into sets.