| Popis: |
In this work we propose a coded modulation technique which combines different types of modulation including QPSK, QAM, 4D-QAM, and OFDM modulation with a short block systematic turbo code. We aim to achieve exceptional energy efficiency in extremely noisy environments, where moderate data rates and short messages are required. For this proposed model, the performance improvement is produced by a unique mapping of trellis structure error correcting code and spectral efficiency is achieved by exploiting different modulation schemes. Further, we utilize puncturing for parity symbols to increase overall rate of the system and improve bandwidth efficiency. The resulting performance of our designed system compared with the theoretical sphere packing lower bound indicates a very small gap (less than 0.5 dB) which means a substantially close approach to the Shannon limit. |
