A method for operating a transmission point, the method comprising: transmitting, by the transmission point, a plurality of first directional reference signals, the plurality of first directional reference signals sweeping different first beams in a first plane which are constrained by a first beam group of a second plane; transmitting, by the transmission point, a plurality of second directional reference signals, the plurality of second directional reference signals sweeping the different first beams of the first plane which are constrained by a second beam group of the second plane; receiving from a reception point, by the transmission point, a request for the transmission point to commence operations in the second plane and a first feedback, the first feedback indicating at least one first beam of the first plane and at least one beam group of the second plane, where measurements of reference signals in the at least one first beam and the at least one beam group of the second plane satisfy a first selection criterion; and when the transmission point is capable of performing beam sweeping in the second plane, transmitting, by the transmission point, a plurality of third directional reference signals, the plurality of third directional reference signals oriented in accordance with the at least one first beam and sweeping in the at least one beam group of the second plane, and receiving, by the transmission point, a second feedback from the reception point, the second feedback indicating that at least one third directional reference signal meets a second selection criterion. transmitting, by the transmission point, a plurality of first directional reference signals, the plurality of first directional reference signals sweeping different first beams in a first plane which are constrained by a first beam group of a second plane; transmitting, by the transmission point, a plurality of second directional reference signals, the plurality of second directional reference signals sweeping the different first beams of the first plane which are constrained by a second beam group of the second plane; receiving from a reception point, by the transmission point, a request for the transmission point to commence operations in the second plane and a first feedback, the first feedback indicating at least one first beam of the first plane and at least one beam group of the second plane, where measurements of reference signals in the at least one first beam and the at least one beam group of the second plane satisfy a first selection criterion; and when the transmission point is capable of performing beam sweeping in the second plane, transmitting, by the transmission point, a plurality of third directional reference signals, the plurality of third directional reference signals oriented in accordance with the at least one first beam and sweeping in the at least one beam group of the second plane, and receiving, by the transmission point, a second feedback from the reception point, the second feedback indicating that at least one third directional reference signal meets a second selection criterion. transmitting, by the transmission point, a plurality of third directional reference signals, the plurality of third directional reference signals oriented in accordance with the at least one first beam and sweeping in the at least one beam group of the second plane, and receiving, by the transmission point, a second feedback from the reception point, the second feedback indicating that at least one third directional reference signal meets a second selection criterion.