A better understanding of the performance of rate-1/2 binary turbo codes that use odd-even interleavers

Abstract

The effects of the odd-even constraint-as an interleaver design criterion-on the performance of rate-1/2 binary turbo codes are revisited. According to the current understanding, its adoption is favored because it makes the information bits be uniformly protected, each one by its own parity bit. In this paper, we provide instances that contradict this point of view suggesting for a different explanation of the constraint's behavior, in terms of distance spectrum.

An Expurgated Union Bound of Punctured Space-Time Turbo Codes

“…The STTC−1 receives directly the information bits whereas the STTC−2 receives a permuted version of these bits through an interleaver of length K symbols or K log 2 (M ) bits. The interleaving scheme uses two half-length interleavers of odd-even type [4], [16], i.e., it interleaves, separately, symbols on odd and even positions, denoted by π O and π E , respectively. The length of each interleaver is K log 2 (M )/2 bits.…”

“…STTuCs have been analyzed in schemes with high order QAM modulation in order to improve the spectral efficiency and data rates [8]- [11] considering various communications scenarios, such as cooperative communication systems [12], frequency selective channels [13], [14], underwater communications [15]. The STTuC considered in this work has two component recursive STTCs connected in parallel via an oddeven information interleaver [16]. Each component encoder produces at its output a sequence M -PSK symbols that are alternately punctured so that only one encoder accesses the transmit antennas at a given signaling interval.…”