Abstract:
OFDM (orthogonal frequency division multiplexing) is a very promising
technique for high bit rate data transmission in multipath fading
environment causing ISI. Coded OFDM is the modulation scheme of
choice in many international standards for all forms of digital
broadcasting including satellite, terrestrial and cable. Many error
correcting codes have been applied to OFDM. In the field of channel
coding recent era belongs to LDPC (low-density parity-check) codes.
Among all practical error correction methods, Turbo codes and LDPC
codes come closest to approaching the Shannon limit.
In this work, comparative performance evaluation of Low Density ParityCheck (LDPC) coded and Turbo coded orthogonal frequency division
multiplexing (OFDM) systems has been carried out by varying a number
of parameters/factors including channel types, data block size, and
number of decoding iterations. OFDM possesses the ability to counter
severe channel conditions if coded with a suitable error correction
scheme. LDPC coding is appearing as a promising choice in upcoming
communication standards. The error rate behavior of LDPC coded OFDM
system has been compared with its toughest competitor i.e. Turbo Coded
OFDM system, especially on six Stanford University Interim (SUI)
multipath channel models. Their computational complexities have also
been worked out to evaluate the latency, efficiency, cost effect and ease of
implementation. The factors that influence performance of LDPC and
turbo codes have also been considered for comparison.
