An LED backlight unit has a substrate, a plurality of light emitting diodes disposed on the substrate, and a light guide plate is placed adjacent to the light source. The first gain module is configured to receive first signals generated based on a plurality of data streams mapped to a plurality of antennas including a first antenna and a second antenna, and to apply a first gain corresponding to the first antenna to the first signals. A cavity is introduced into the cap layer and is completely or partially filled with a luminescence conversion material. The controller determines whether the first data set is different from a second data set.