Novel results on adaptive UMTS outer block interleaving using SOVA turbo decoder

Outer block interleaving improves the performance of turbo codes, especially in correlated Rayleigh fading wireless channels. The choice of inappropriate number of columns for the outer block interleaver can increase BER. Therefore, the idea of an adaptive outer block interleaver with column number optimized according to the operating environment or mobile terminal speed and date rate has gained considerable attention. SOVA and log-MAP represent the main algorithms for turbo decoding. This work presents simulation scenarios for urban or suburban outdoor operating environment (50 km/h terminal speed) for the different UMTS outer block interleaver configurations. Particularly, simulation results are demonstrated using four different data rates, 5114 bits frame length and SOVA turbo decoding algorithm. Comparing the corresponding outer block interleaver number of columns proposed in for log-MAP turbo decoding algorithm, in this work we observe different values for a data rate of 384 kbps and BER performance. For higher data rates, as well as FER performance, the proposed values are the same.