Power assisted RF EMF average power control
Systems and methods are disclosed for power assisted Radio Frequency (RF) Electric and Magnetic Field (EMF) average power control for a Radio Access Network (RAN) node of a cellular communications system. In one embodiment, a method of operation of a controller for a RAN node comprises computing an average total transmit power over a control period and computing an initial Physical Resource Block (PRB) limit for transmission of a Physical Downlink Shared Channel (PDSCH) for the cell based on a comparison of the computed average and a reference. The method further comprises determining whether power scaling is to be used, adjusting the initial PRB limit and providing the adjusted PRB limit and a power scaling indication to a scheduler associated to the cell if power scaling is to be used, and otherwise providing the initial PRB limit and an indication of no power scaling to the scheduler.
1 . A method of operation of a controller for a Radio Access Network (RAN) node for a cellular communications system, the method comprising:
computing an average total transmit power for transmission for a cell over a control period that comprises a plurality of transmission time intervals (TTIs);
computing an initial physical resource block (PRB) limit for transmission of a physical downlink shared channel for the cell based on a comparison of the average total transmit power and a reference average total transmit power;
determining whether power scaling is to be used;
if power scaling is to be used:
adjusting the initial PRB limit to provide an adjusted PRB limit; and
providing the adjusted PRB limit and a power scaling indication to a scheduler associated to the cell; and
if power scaling is not to be used:
providing the initial PRB limit and an indication of no power scaling to the scheduler associated to the cell.
2 . The method of claim 1 , wherein power scaling is to be used if the initial PRB limit is less than or equal to a predefined or preconfigured minimum, non-zero PRB threshold.
3 . The method of claim 1 , wherein power scaling is to be used if either:
the initial PRB limit is less than or equal to a predefined or preconfigured minimum, non-zero PRB threshold, or
the initial PRB limit is greater than the predefined or preconfigured minimum, non-zero PRB threshold but a prior initial PRB limit for a prior control period was less than or equal to the predefined or preconfigured minimum, non-zero PRB threshold and a predefined or preconfigured amount of time has not elapsed between a first time instances associated to the prior control period and a second time instance associated to the control period.
4 . The method of claim 1 , wherein determining whether power scaling is to be used comprises determining whether the controller is configured in a power scaling state.
5 . The method of claim 4 , wherein the controller is configured in the power scaling state if the initial PRB limit is less than or equal to a predefined or preconfigured minimum, non-zero PRB threshold.
6 . The method of claim 4 , wherein the controller is configured in the power scaling state if either:
the initial PRB limit is less than or equal to a predefined or preconfigured minimum, non-zero PRB threshold, or
the initial PRB limit is greater than the predefined or preconfigured minimum, non-zero PRB threshold but a prior initial PRB limit for a prior control period was less than or equal to the predefined or preconfigured minimum, non-zero PRB threshold and a predefined or preconfigured amount of time has not elapsed between a first time instance associated to the prior control period and a second time instance associated to the control period.
7 . The method of claim 1 , wherein adjusting the initial PRB limit to provide the adjusted PRB limit comprises applying a scaling factor to the initial PRB limit, the scaling factor corresponding to a power scaling factor to be applied.
8 . The method of claim 7 , wherein the power scaling indication indicates the power scaling factor.
9 . The method of claim 1 , wherein the adjusted PRB limit indicates a number of PRBs that is greater than a number of PRBs indicated by the initial PRB limit.
10 . The method of claim 1 , wherein the power scaling is power de-boosting such that power spectral density per resource element comprised in the physical downlink shared channel is reduced as compared to when power de-boosting is not used.
11 . A method performed by a scheduler for a Radio Access Network (RAN) node for a cellular communications system, the method comprising:
obtaining a recommended physical resource block (PRB) limit for physical downlink shared channel (PDSCH) transmission for an associated cell and a power scaling indication that indicates whether power scaling is needed for PDSCH transmission for the associated cell, the recommended PRB limit and the power scaling indication being for a control period comprising a plurality of transmission time intervals, TTIs;
determining whether the power scaling indication indicates that power scaling is needed;
determining whether the associated cell is cell-edge centric, the associated cell being cell-edge centric if the associated cell predominantly serves cell-edge wireless communication devices; and
performing one or more actions based on whether the power scaling indication indicates that power scaling is needed and whether the associated cell is cell-edge centric.
12 . The method of claim 11 , wherein performing the one or more actions comprises either applying the recommended PRB limit or adjusting the PRB limit based on whether the power scaling indication indicates that power scaling is needed or not needed and whether the associated cell is cell-edge centric or not.
13 . The method of claim 11 , wherein performing the one or more actions comprises either applying power scaling or not based on whether the power scaling indication indicates that power scaling is needed or not needed and whether the associated cell is cell-edge centric or not.
14 . The method of claim 11 , wherein:
determining whether the power scaling indication indicates that power scaling is needed comprises determining that the power scaling indication indicates that power scaling is needed;
determining whether the associated cell is cell-edge centric comprises determining that the associated cell is not cell-edge centric; and
performing the one or more actions comprises applying the recommended PRB limit and power scaling responsive to determining that the power scaling indication indicates that power scaling is needed and determining that the associated cell is not cell-edge centric.
15 . The method of claim 14 , wherein performing the one or more actions further comprises adjusting one or more parameters associated to link adaptation in a manner that makes the link adaptation more conservative relative to the link adaptation prior to adjusting the one or more parameters, responsive to applying the power scaling.
16 . The method of claim 11 , wherein:
determining whether the power scaling indication indicates that power scaling is needed comprises determining that the power scaling indication indicates that power scaling is needed;
determining whether the associated cell is cell-edge centric comprises determining that the associated cell is cell-edge centric; and
performing the one or more actions comprises, responsive to determining that the power scaling indication indicates that power scaling is needed and determining that the associated cell is cell-edge centric:
modifying the recommended PRB limit to provide a modified PRB limit;
applying the modified PRB limit; and
refraining from applying power scaling.
17 . The method of claim 16 , wherein modifying the recommended PRB limit comprises modifying the recommended PRB limit such that the recommended PRB limit is reduced in proportion to a scaling factor associated to the power scaling indication in order to provide the modified PRB limit.
18 . The method of claim 11 , wherein:
determining whether the power scaling indication indicates that power scaling is needed comprises determining that the power scaling indication indicates that power scaling is not needed;
determining whether the associated cell is cell-edge centric comprises determining that the associated cell is not cell-edge centric; and
performing the one or more actions comprises, responsive to determining that the power scaling indication indicates that power scaling is not needed and determining that the associated cell is not cell-edge centric:
modifying the recommended PRB limit to provide a modified PRB limit;
applying the modified PRB limit; and
applying power scaling.
19 . The method of claim 18 , wherein modifying the recommended PRB limit comprises applying a scaling factor to the recommended PRB limit that increases the recommended PRB limit in proportion of an applied power scaling factor to provide the modified PRB limit.
20 . The method of claim 18 , wherein performing the one or more actions further comprises adjusting one or more parameters associated to link adaptation in a manner that makes the link adaptation more conservative relative to the link adaptation prior to adjusting the one or more parameters, responsive to applying the power scaling.