A turbo iteration algorithm in 16QAM hierarchical modulation

In the next generation communication protocol “DVB-SH”, it offers a new transmitting scheme based on the turbo code, OFDM modulation and 16QAM hierarchical modulation to increase the flexibility in the information delivery. This scheme is using Hierarchical modulation to enhance the UE (user equipment) performance which is in the center of a sector and also ensure the basic service when UE move to the region of a sector. Hierarchical modulation uses two different bit streams on to different constellation of the constellation map. This scheme ensures two different bit streams have corresponding BER performance and then bring on the flexibility to the transmitting service. The simulation results indicates that in the Rayleigh and Gaussian channel, this scheme can gain a very high BER performance of high priority bit stream, and in the high SNR, it can also gain a high BER performance of low priority bit stream.