On the impact of channel coding, Viterbi decoding and SOVA for a single carrier system with frequency domain equalization

In this work we investigate the effect of convolutional coding, interleaving and Viterbi decoding, as they are used for OFDM (orthogonal frequency division multiplexing) in the IEEE 802.11a standard, for a single carrier system with frequency domain equalization (SC/FDE). We will characterize the effect of decision length (maximal length of the trellis) and code rate in terms of bit error behavior, reliability of soft decisions and implementation effort for the classical Viterbi algorithm as well as for the soft output Viterbi algorithm (SOVA). The (coding) parameters of the simulated system are adapted to the IEEE 802.1 Ia standard for WLAN applications. In detail we will elaborate on the advantages of pilot symbols, that are multiplexed into the data stream as a method to reduce the necessary decision length as well as to reduce the implementation effort and to improve the SOVA output. It will be demonstrated that the use of pilot symbols shows significant advantages that dominate the disadvantages.