A method of operating a network node comprising one or more transmit antennas that are associated with a plurality of antenna ports includes transmitting a first user-equipment-(UE-) specific reference signal on a first antenna port and reusing the first UE-specific reference signal to transmit a second UE-specific reference signal on one of the first antenna port and a second antenna port. The second UE-specific reference signal is orthogonal to the first UE-specific reference signal.