Network node, wireless device and methods therein for performing and handling superposed transmissions in a wireless communications network

A network node for performing a superposed transmission in a wireless communications network, the superposed transmission comprising a first signal intended for a first wireless device from the network node and a second signal intended for a second wireless device from the network node that are superposed and transmitted simultaneously by the network node on the same transmission resources in the wireless communications network, the network node comprising processing circuitry being configured to cause the network node to:

• transmit first information indicating at least one of a first and a second ratio of a total transmission power, P, allocated for the superposed transmission to at least the first wireless device in the wireless communications network, the first ratio to be used for the first signal in the superposed transmission, the second ratio to be used for the second signal in the superposed transmission;
• when the network node is configured to perform the superposed transmission using a transmission mode comprising Cell-specific Reference Signals, CRS, transmit second information indicating a third ratio between an average transmission power allocated for the superposed transmission per Resource Element, RE, in the Orthogonal Frequency Division Multiplexing, OFDM, grid not comprising CRS, and an average CRS transmission power allocated per RE;
• and
• perform the superposed transmission to the first and second wireless device simultaneously on the same transmission resources by transmitting the first signal using a transmission power according to the first ratio and by transmitting the second signal using a transmission power according to the second ratio, and by allocating the total transmission power, P, of the first and second signals according to the third ratio.

A method performed by a first wireless device for handling a superposed transmission from a network node in a wireless communications network, the superposed transmission comprising a first signal intended for the first wireless device and a second signal intended for a second wireless device that are superposed and transmitted simultaneously by the network node on the same transmission resources in the wireless communications network, the method comprising:

• receiving first information indicating at least one of a first and a second ratio of a total transmission power, P, allocated for the superposed transmission, the first ratio to be used for the first signal in the superposed transmission, and the second ratio to be used for the second signal in the superposed transmission;
• receiving the superposed transmission;
• processing the first signal intended for the first wireless device using at least one estimated channel associated with the first and second wireless device and an estimated second signal;
• and
• when the network node is configured to perform the superposed transmission using a transmission mode comprising a cell specific reference signal, CRS, receiving second information indicating a third ratio between an average transmission power allocated for the superposed transmission per Resource Element, RE, in the Orthogonal Frequency Division Multiplexing, OFDM, grid not comprising CRS, and an average CRS transmission power allocated per RE, the total transmission power, P, of the first and second signals being allocated according to the third ratio.