A method in a radio network node for transmission of an information entity to a receiver in a wireless communication system over at least one antenna port in a subframe comprising a plurality of time-frequency resources, the method comprising: defining a set of at least two distinct Demodulation Reference Signal, DM-RS, patterns, wherein the defined set of at least two distinct DM-RS patterns comprises a first DM-RS pattern having a first reference signal density per antenna port and a second DM-RS pattern having a second reference signal density per antenna port, wherein the second reference signal density per antenna port is higher than the first reference signal density per antenna port, the first DM-RS pattern comprises a first set of positions of the time-frequency resources, wherein the positions in the first DM-RS pattern are associated with antenna ports, and the second DM-RS pattern comprises a second set of positions of the time-frequency resources, wherein the positions in the second DM-RS pattern are associated with antenna ports, wherein the second set of positions of the time-frequency resources of the second DM-RS pattern comprises a set of positions of the time-frequency resources of the first DM-RS pattern, which are associated with a subset of the antenna ports associated with the first DM-RS pattern and to which additional time-frequency resources are added, assigning one DM-RS pattern from the defined set of at least two distinct DM-RS patterns to the receiver; and transmitting the information entity in the subframe on the antenna ports associated with the assigned DM-RS pattern, and the DM-RS signal comprising the assigned DM-RS pattern. defining a set of at least two distinct Demodulation Reference Signal, DM-RS, patterns, wherein the defined set of at least two distinct DM-RS patterns comprises a first DM-RS pattern having a first reference signal density per antenna port and a second DM-RS pattern having a second reference signal density per antenna port, wherein the second reference signal density per antenna port is higher than the first reference signal density per antenna port, the first DM-RS pattern comprises a first set of positions of the time-frequency resources, wherein the positions in the first DM-RS pattern are associated with antenna ports, and the second DM-RS pattern comprises a second set of positions of the time-frequency resources, wherein the positions in the second DM-RS pattern are associated with antenna ports, wherein the second set of positions of the time-frequency resources of the second DM-RS pattern comprises a set of positions of the time-frequency resources of the first DM-RS pattern, which are associated with a subset of the antenna ports associated with the first DM-RS pattern and to which additional time-frequency resources are added, the defined set of at least two distinct DM-RS patterns comprises a first DM-RS pattern having a first reference signal density per antenna port and a second DM-RS pattern having a second reference signal density per antenna port, wherein the second reference signal density per antenna port is higher than the first reference signal density per antenna port, the first DM-RS pattern comprises a first set of positions of the time-frequency resources, wherein the positions in the first DM-RS pattern are associated with antenna ports, and the second DM-RS pattern comprises a second set of positions of the time-frequency resources, wherein the positions in the second DM-RS pattern are associated with antenna ports, wherein the second set of positions of the time-frequency resources of the second DM-RS pattern comprises a set of positions of the time-frequency resources of the first DM-RS pattern, which are associated with a subset of the antenna ports associated with the first DM-RS pattern and to which additional time-frequency resources are added, assigning one DM-RS pattern from the defined set of at least two distinct DM-RS patterns to the receiver; and transmitting the information entity in the subframe on the antenna ports associated with the assigned DM-RS pattern, and the DM-RS signal comprising the assigned DM-RS pattern.