Antenna power scaling in fronthaul lower layer split

1 . A method for antenna power scaling in a fronthaul lower-layer split, LLS, the method performed by a baseband unit (BBU) for assisting a Radio Unit (RU) in scaling a transmit power of one or more antennas when performing beamforming, the method comprising:

obtaining a plurality of beamforming weights (BFWs) for beamforming of a signal to be transmitted to at least one wireless device via the one or more antennas;

based on the plurality of BFWs, determining the at least one antenna power scaling factor to be applied to scale the transmit power of at least one of the antennas; and

transmitting at least one antenna power scaling factor to the RU for scaling the transmit power of the one or more antennas,

wherein the at least one antenna power scaling factor is determined after all of the plurality of BFWs are obtained, and

wherein the BBU is further adapted to transmit at least one BFW of the plurality of BFWs before the at least one antenna power scaling factor is determined.

2 . A method by a radio Unit (RU) comprising one or more antennas for performing beamforming for a communication between the RU and at least one wireless device, the method comprising:

receiving, from a baseband unit (BBU) at least one antenna power scaling factor for scaling a transmit power of the one or more antennas; and

receiving, from the BBU, a plurality of beaming forming weights (BFWs), associated with at least one subcarrier,

wherein the at least one antenna power scaling factor is based on the plurality of BFWs, and

wherein at least one of the plurality of BFWs is received from the BBU before the at least one antenna power scaling factor is received from the BBU.

3 . A baseband unit (BBU) for assisting a Radio Unit (RU) in scaling a transmit power of one or more antennas when performing beamforming, the BBU adapted to:

obtain a plurality of beamforming weights (BFWs) for beamforming of a signal to be transmitted to at least one wireless device via the one or more antennas;

based on the plurality of BFWs, determine the at least one antenna power scaling factor to be applied to scale the transmit power of at least one of the antennas; and

transmit at least one antenna power scaling factor to the RU for scaling the transmit power of the one or more antennas,

wherein the at least one antenna power scaling factor is determined after all of the plurality of BFWs are obtained, and

wherein the BBU is further adapted to transmit at least one BFW of the plurality of BFWs before the at least one antenna power scaling factor is determined.

4 . The BBU of claim 3 , wherein the at least one antenna power scaling factor is transmitted with at least one additional scaling factor that is not determined based on the plurality of BFWs.

5 . The BBU of claim 3 , further adapted to normalize the plurality of BFWs based on at least one power scaling criteria.

6 . The BBU of claim 3 , wherein the at least one antenna power scaling factor is determined based on a power contribution of all BFWs on all scheduled resource elements.

7 . The BBU of claim 3 , wherein each of the at least one antenna power scaling factor is determined after the plurality of BFWs are obtained for all scheduled resource elements.

8 . The BBU of claim 3 , wherein the at least one antenna power scaling factor is associated with one carrier of a plurality of carriers transmitted on the one or more antennas.

9 . The BBU of claim 3 , wherein the at least one antenna power scaling factor comprises at least a first antenna power scaling factor to be applied to scale the transmit power of a plurality of antennas.

10 . The BBU of claim 3 , wherein the at least one antenna power scaling factor comprises a plurality of antenna power scaling factors, and wherein each of the plurality of antenna power scaling factors is to be applied to scale the transmit power of an associated one of a plurality of antennas.

11 . The BBU of claim 3 , wherein the at least one antenna power scaling factor is transmitted via a control-plane message.

12 . The BBU of claim 3 , further adapted to:

after determining and transmitting the at least one antenna power scaling factor to the RU, obtain at least one updated BFW;

based on at least the updated BFW, determine at least one updated antenna power scaling factor; and

transmit the at least one updated antenna power scaling factor to the RU.

13 . A radio Unit (RU) comprising one or more antennas for performing beamforming for a communication between the RU and at least one wireless device, the RU adapted to:

receive, from a baseband unit (BBU), at least one antenna power scaling factor for scaling a transmit power on the one or more antennas; and

receiving, from the BBU, a plurality of beaming forming weights (BFWs), associated with at least one subcarrier,

wherein the at least one antenna power scaling factor is based on the plurality of BFWs, and

wherein the plurality of BFWs are received from the BBU before the at least one antenna power scaling factor is received from the BBU.

14 . The RU of claim 13 , further adapted to:

apply the at least one antenna power scaling factor to scale the transmit power of the one or more antennas; and

using the one or more antennas with the scaled transmit power to transmit a signal to the at least one wireless device.

15 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the antenna transmit power of the one or more antennas, the RU is adapted to:

apply a single antenna power scaling factor to scale the antenna transmit power of each of a plurality of antennas.

16 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the transmit power of the one or more antennas, the RU is adapted to:

apply each one of a plurality of antenna power scaling factors to scale an associated one of a plurality of antennas.

17 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the transmit power of the one or more antennas, the RU is adapted to:

apply the at least one antenna power scaling factor to a plurality of beamforming weights, BFWs, received from the BBU on IQ data of one or more scheduled resource elements.

18 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the transmit power of the one or more antennas, the RU is adapted to:

apply the at least one antenna power scaling factor to a plurality of frequency-domain IQ data of the signal before the signal is multiplied with the BFWs associated with each antenna.

19 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the transmit power of the one or more antennas, the RU is adapted to:

apply the at least one antenna power scaling factor to a plurality of frequency-domain IQ data of the signal after the signal is multiplied with the BFWs associated with each antenna.

20 . The RU of claim 14 , wherein when applying the at least one antenna power scaling factor to scale the transmit power of the one or more antennas, the RU is adapted to:

apply the at least one antenna power scaling factor to a plurality of time-domain IQ data of the signal for each of a plurality of antennas.

21 . The RU of claim 14 , wherein the at least one antenna power scaling factor is associated with a carrier.

22 . The RU of claim 13 , wherein the plurality of BFWs received from the BBU do not include a BFW for at least one scheduled subcarrier, and wherein the RU is further adapted to: based on the plurality of BFWs received from the BBU, obtain at least one additional BFW for at least one scheduled subcarrier for which a BFW was not received from the BBU.