Modified turbo codes for next generation wireless networks

Turbo Convolutional Codes (TCC) are widely used to reduce Bit Error Rate (BER) for Second Generation (2G) and Third Generation (3G) wireless networks. However, TCC require large decoding complexity. Recently, Low Density Parity Check Codes (LDPC) have been included in standards for 3G wireless networks. But encoding complexity of LDPC is larger than that of TCC. Modified Turbo codes (MTC) are low complexity turbo-like codes with error performance which is equivalent to that of Turbo codes. However, MTC require 2-dimensional interleavers with large spreading factor and dispersion. In this paper, it is shown that BER of MTC is almost equivalent to TCC. Moreover, MTC decoders require 50% less computations than those of TCC and LDPC. Spreading factor and dispersion for various interleavers are compared. It is observed that 2-stage interleaver achieves large spreading factor and dispersion.