Increasing range of DW3000 in NLOS

We are using DWM3000 modules for our project. the transmission distance we get from DW3000 using channel 9 in LOS condition is more than 100 meters but in NLOS condition(one person is standing very close to the transmitter and blocking the LOS) we are getting only 12 meters, How can we increase transmission distance in such NLOS condition.