Unbalanced Power Allocation for Turbo Coded Psam and Pilot Assisted Sova Decoder

In communication systems, channel coding is widely employed in order to have reliable data transmissions. Turbo codes were first introduced by C.Berrou in 1993 [I] as a powerful channel coding technique, and were shown to achieve performance near Shannon capacity over an additive white Gaussian noise (AWGN) channel. In this thesis, two schemes related to turbo codes are proposed, and are shown to have superior performance over previous work. In [I], turbo codes were applied to Pilot Symbol Assisted Modulation for iterative channel estimation and decoding over correlated flat-fading channels. The first scheme of this thesis extends the work in [I] by allocating different power values to the pilot symbols and turbo coded symbols. When compared with previous work in this field, simulation results show a significant performance gain. The second scheme is based on the Soft Output Viterbi Algorithm. Pilot symbols are introduced to detect errors as well as to correct errors. Simulation results show a coding gain of 0.43 dB when using the pilot assisted turbo SOVA decoder over the conventional SOVA decoder