NB-IoT realization in active antenna system

1 . A method performed by a network node comprising an active antenna system in a telecommunication network, the method comprising:

identifying a plurality of available branches from a plurality of branches of the active antenna system for supporting a narrow band signal, wherein each of the plurality of branches is loaded with a different amount of power; and

mapping at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal, wherein each of the at least two available branches are mapped to different sets of subcarriers from the plurality of subcarriers from the narrowband signal, and wherein the mapping comprises selecting the available branches having a power loading below a threshold for the each of the plurality of subcarriers from the narrowband signal.

2 . The method of claim 1 , wherein the narrowband signal is deployed in the telecommunications network in at least one of a standalone operation, a guard band operation, and an in-band operation.

3 . The method of claim 1 , wherein the mapping comprises one or more of the following: a dual-polarized beamforming of additional ports, a static mapping, a dynamic mapping with repetition, a dynamic mapping with chance, a channel dependent mapping, and a mapping of a subset of the plurality of subcarriers.

4 . The method of claim 1 , wherein mapping the at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal comprises mapping a maximum of one subcarrier of the plurality of subcarriers from the narrowband signal to each of the at least two available branches of the plurality of available branches.

5 . The method of claim 1 , wherein the plurality of available branches includes fewer branches than the plurality of branches.

6 . The method of claim 1 , wherein the at least one subcarrier of the plurality of subcarriers omits a narrowband reference signal, and wherein the mapping comprises mapping an adjacent subcarrier from the narrowband signal to a branch from the plurality of branches closest in proximity to the at least one of the plurality of subcarriers omitting a narrowband reference signal.

7 . The method of claim 1 , further comprising:

measuring a quality of the received narrowband signal from a communication device at each port of the plurality of antenna ports to obtain a measured quality for each port; and

wherein the mapping comprises using each port for the mapping that has the measured quality above a threshold.

8 . The method of claim 7 , wherein the measured quality comprises one or more of: a signal to noise ratio measurement on an uplink reference symbol and a reference signal received power report from a channel state information reference signal.

9 . The method of claim 1 , wherein the mapping comprises mapping a subset of the plurality of subcarriers from the narrowband signal to more than one of the available branches of the plurality of branches.

10 . The method of 9 , wherein the narrowband signal comprises a data signal, a control signal, and a plurality of reference symbols for a subset of the plurality of subcarriers, and

wherein the mapping is based on at least one of:

the subset of the plurality of subcarriers containing the data signal and/or the control signal are mapped to redundant ports of the plurality of ports; and

the subset of the plurality of subcarriers containing the plurality of reference symbols are mapped to redundant ports of the plurality of ports.

11 . The method of claim 1 , further comprising:

wherein the narrowband signal includes repetition that is re-transmitted; and

wherein the mapping comprises dynamic mapping of each re-transmission of the narrowband signal.

12 . A method performed by a network node comprising an active antenna system in a telecommunication network, the method comprising:

identifying a plurality of available branches from a plurality of branches of the active antenna system for supporting a narrowband signal; and

mapping at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal, wherein each of the at least two available branches are mapped to different sets of subcarriers from the plurality of subcarriers from the narrowband signal, and

wherein the method further comprises:

identifying at least a portion of at least two columns or two rows, respectively, from a plurality of columns or a plurality of rows of the active antenna system that are redundant portions of the at least two columns or the at least two rows prior to the mapping; and

wherein the mapping comprises performing dual polarized beamforming of the redundant portions of the at least two columns or the at least two rows to create a virtual column or a virtual row having a first beamwidth that is substantially the same as a second beamwidth of one of the plurality of columns or one of the plurality of rows.

13 . A network node comprising an active antenna system in a telecommunication network, the network node comprising:

the active antenna system comprising a plurality of branches, wherein each of the plurality of branches comprises a plurality of antenna elements connected to at least one antenna port;

at least one processor;

at least one memory connected to the at least one processor and storing program code that is executed by the at least one processor to perform operations comprising:

identifying a plurality of available branches from the plurality of branches of the active antenna system for supporting a narrowband signal, wherein each of the plurality of branches is loaded with a different amount of power; and

mapping at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal, wherein each of the at least two available branches are mapped to different sets of subcarriers from the plurality of subcarriers from the narrowband signal, and wherein the mapping comprises selecting the available branches having a power loading below a threshold for the each of the plurality of subcarriers from the narrowband signal.

14 . A network node comprising an active antenna system in a telecommunication network performing operations comprising:

identifying a plurality of available branches from a plurality of branches of the active antenna system for supporting a narrowband signal, wherein each of the plurality of branches is loaded with a different amount of power; and

mapping at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal, wherein each of the at least two available branches are mapped to different sets of subcarriers from the plurality of subcarriers from the narrowband signal, and wherein the mapping comprises selecting the available branches having a power loading below a threshold for the each of the plurality of subcarriers from the narrowband signal.

15 . A non-transitory computer readable medium storing a computer program comprising program code to be executed by processing circuitry of a network node, whereby execution of the program code causes the network node to perform operations comprising:

identifying a plurality of available branches from a plurality of branches of the active antenna system for supporting a narrowband signal, wherein each of the plurality of branches is loaded with a different amount of power; and

mapping at least two available branches from the plurality of available branches to at least one subcarrier of a plurality of subcarriers from the narrowband signal, wherein each of the at least two available branches are mapped to different sets of subcarriers from the plurality of subcarriers from the narrowband signal, and wherein the mapping comprises selecting the available branches having a power loading below a threshold for the each of the plurality of subcarriers from the narrowband signal.