Bit-Interleaving in Fast FH/SSMA Systems with Convolutional Codes and Turbo Codes

Bit-interleaving is generally believed to be an effective measure when convolutional codes and turbo codes are employed with M-ary signaling. It is shown in this paper that bit-interleaving should not be blithely employed in fast FH/SSMA systems with M-ary FSK. Both theoretical upper bounds and simulation results show that bit-interleaving coded sequences before mapping increases the bit error rates for convolutional codes, except when bit error rates is very small. Simulation results also show that for turbo codes, both bit-interleaving data sequences in encoders and bit-interleaving coded sequences before mapping drastically degrade the performance of the system.