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This paper evaluates the performance of symmetric turbo codes using LOG-MAP, SOVA and MAP decoding algorithms and suggests the most relevant decoding algorithm. Since 1993 ie from the discovery of turbo codes till 2008, symmetric turbo codes got great attention by researchers and asymmetric codes were not given much importance.

LOG-MAP and SOVA decoding algorithms are implemented for symmetric turbo codes. Then, the performance of these algorithms is evaluated in terms of BER/SNR by varying parameters like user data frame size, generator polynomial/constraintlength and code rate, etc. Out of these two algorithms, the performance of LOG-MAP algorithm is better. But complexity of LOG-MAP is higher, due to large number of multiplication operations used in the calculation. On the other hand, SOVA is implemented using less complexity. Simulation results show that with the increase in frame size of user data, BER performance improves for both algorithms