Title :
Optimal turbo decoding metric generation in a pilot assisted coherent wireless communication system
Author_Institution :
Qualcomm Inc., San Diego, CA, USA
Abstract :
In this paper, we derive the exact expressions of the log-likelihood ratio (LLR) values generated from coherent demodulation using the channel coefficient estimated based on the pilot signal. These results are obtained based on the analytical results given in Ling (1999). It is shown that for Rayleigh fading channels, the LLR values for turbo decoding are the scaled dot products of the channel estimate and the sample of the coded bits. Examples of the computation of the LLR values are given. Considerations and principles for practical implementations are discussed. Simulation results are provided to demonstrate the importance of choosing the proper scaling factor in achieving optimal decoding performance
Keywords :
Rayleigh channels; channel coding; decoding; demodulation; land mobile radio; turbo codes; LLR values; Rayleigh fading channels; channel coefficient; coherent demodulation; log-likelihood ratio; mobile radio; optimal turbo decoding metric generation; pilot assisted coherent wireless communication system; scaled dot products; scaling factor; 3G mobile communication; Computational modeling; Concatenated codes; Demodulation; Error correction codes; Fading; Iterative decoding; Maximum likelihood decoding; Mobile communication; Wireless communication;
Conference_Titel :
Vehicular Technology Conference, 2000. IEEE-VTS Fall VTC 2000. 52nd
Conference_Location :
Boston, MA
Print_ISBN :
0-7803-6507-0
DOI :
10.1109/VETECF.2000.886668
