Type of Document Master's Thesis Author Cho, Youngjeon URN etd-04072008-134508 Title A Capacity-Approaching Coded Modulation Scheme for Non-Coherent Fading Channels Degree Master of Science in Electrical Engineering (M.S.E.E.) Department Electrical & Computer Engineering Advisory Committee
Advisor Name Title Xue-bin Liang Committee Chair Guoxiang Gu Committee Member Shuangqing Wei Committee Member Keywords
- turbo codes
- LDPC codes
- non-coherent fading channel
Date of Defense 2008-03-25 Availability unrestricted AbstractApproaching the Shannon limit of the communication channels has been studied by many researchers to efficiently and reliably transmit data through the channels. To solve this problem, various methods and schemes have been proposed for approaching the theoretical limit for Shannon’s channel capacity. Among them, both low-density parity check (LDPC) codes and Turbo codes have been proposed to minimize the bit error rate (BER). Therefore, understanding of LDPC codes and Turbo codes is useful for their applications in modern communication systems.
The study about non-coherent channels, which do not require explicit knowledge or estimation of the channel state information, has become a major issue in mobile communication. Specifically, a new signaling scheme called unitary space-time modulation has been invented which is suitable for non-coherent channels. Combining channel coding with unitary space-time modulation is expected to make good performance for non-coherent fading channels.
In this thesis, non-coherent capacity of a mobile communication channel in Rayleigh flat fading is calculated for the case of coherence time of length two. Also, LDPC codes and Turbo codes are combined with unitary space-time modulation to enhance the efficiency and reliability of communication over non-coherent fading channels. The performance results are compared to the calculated channel capacity. Simulation results show that both LDPC codes and Turbo codes are well performed for non-coherent fading channels. The LDPC and Turbo coded unitary space-time modulation schemes have BER performance much better than the uncoded modulation schemes and the performance is close to the calculated channel capacity.
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