Leaking interleavers for UEP Turbo codes

Abstract

Interleaving is a key to Turbo coding's exceptional performance. An interleaver provides bit-permutation designed to ensure deterministic randomness. When applying interleavers to unequal error protecting (UEP) Turbo codes, typically, priority classes protected with different rates are kept separate. This work, however, gives insight, how the performance changes, when block boundaries are relaxed, leaking bits to other classes.The effect of this leakage is an improvement of the average performance due to a virtually bigger interleaver size, with the drawback of a flooring of the individual performances to the worst protection (highest code rate) involved in a certain class.

Rate-Compatible LDPC and Turbo Codes for Link Adaptivity and Unequal Error Protection

“…Some leakage will, however, interconnect data thereby realizing a bigger interleaver, improving the average performance. Wakeel et al [36] introduced the relaxation of the class boundaries permuting a limited portion of data between the priority classes.…”

Joint space-time algebraically-interleaved turbo-like Coded Incoherent MIMO systems with optimal and suboptimal MAP probability decoders

“…In particular, the performance of short-length turbo codes is highly determined by the permutation structure [23]. Permutation is a process of interleaving the order of a data sequence in a one-to-one deterministic format in order to create statistical independence between disturbances on parity symbols related to the same information symbol entering the channel encoders [24]. Many permutation algorithms have been investigated to improve the distance properties of the code while maintain the simple and practical hardware implementations.…”