M.2.2 Coarse and fine measurement grids

38.521-23GPPNRPart 2: Range 2 StandaloneRadio transmission and receptionRelease 17TSUser Equipment (UE) conformance specification

The baseline beam peak search is based on a single and fine beam peak search grid to determine the TX/RX beam peak of the DUT in any given direction. This means that even in sectors where poor EIRP/EIS performance is observed, a very fine grid is used to search for the TX/RX beam peak.

An optimized approach, based on an initial coarse search followed by a subsequent fine search could reduce the number of beam peak search grid points significantly. The basis for this approach is to use a coarse grid with fewer number of points than the ones described in section M.2.1 in the first stage to identify candidate regions that contain the global beam peak and search for the global beam peak with the fine grid in the second stage with a minimum number of points described in section M.2.1.

As an example, Figure M.2.2-1 illustrates the coarse and fine measurement grid approach applied to TX beam search; while this illustration is for EIRP, it can easily be extended to RX beam peak search using EIS or throughput metrics For simplification purposes, 2D coarse and fine searches are illustrated but the concept can be extended to 3D easily. The UE is assumed to form a total of six beams in the 2D plane as illustrated on the left of Figure M.2.2-1. In the centre of Figure M.2.2-1, the 36 coarse beam peak search grid points in the 2D plane are illustrated. On the right, the grey circles on the respective antenna patterns illustrate the measured EIRP values towards each coarse grid point direction based on the respective beam steering directions. This illustration shows that the EIRP beam peak of the coarse search, EIRP_CSBP, is found to be the peak of the orange beam while the global TX beam peak (red beam) was not identified due to the coarse sampling of the grid points.

Figure M.2.2-1: Illustration of the Coarse Search Approach for TX Beam Peak Search. Left: Antenna Pattern assumptions in 2D, Centre: Coarse beam peak search grid points/discrete antenna measurement positions, Right: TX beam EIRP measurements per grid point

The proposed fine search approach is illustrated further in Figure M.2.2-2. A fine search region starting from the beam peak identified in the coarse search, EIRP_CSBP, over a range of _FS is used to identify the regions that need to be investigated more closely with the fine search algorithm. The fine search range _FS is a function of the angular spacing of the coarse beam peak search grid as well as the beam width of the reference antenna pattern considered for smartphone UEs.

Figure M.2.2-2: Illustration of the fine beam peak search grid. Left: identify the measurement grid points that yielded EIRP values within the fine search region, right: placement of fine beam peak search grid points

Figure M.2.2-3 illustrates coarse and fine grids for constant step size measurement grids while Figure M.2.2-4 illustrates the same for constant density grid.

Figure M.2.2-3: Illustration: Coarse & Fine Constant Step Size Grids

Figure M.2.2-4: Illustration: Coarse & Fine Constant Density Grids

The metric using a coarse & fine grid approach for the TX beam peak search is EIRP for both grids. For RX beam peak search either EIS or Throughput could be used for coarse grids while only EIS for fine grid,