Performance of a 4-State Turbo Code with Data Puncturing and a BCH Outer Code

Abstract

The performance of a concatenated Turbo code with an outer BCH code is examined. The Turbo code was based on simple 4-state constituent codes with a constrained high spread random (HSR) interleaver. Data puncturing, as opposed to puncturing only the parity bits, was used with the Turbo code to improve the convergence performance in the waterfall region. It is shown that this simple approach achieves performance better than the rate 1/2 DVB-S2 concatenated LDPC-BCH code.

Turbo and Turbo-Like Codes: Principles and Applications in Telecommunications

“…Comparable performance can be achieved by combining BCH outer codes with other forms of turbo FEC. For example, it was found in [40] that performance superior to the DVB-S2 code can be achieved at rate 1/2 using a well-designed 4-state turbo code concatenated with a BCH code.…”

“…1) Concatenate the turbo or turbo-like code with a high-rate outer code on some or all of the transmitted bits, for example a BCH code [40], [81], [115]- [117]. This incurs penalties in energy per coded bit and code rate that grow as the block length decreases.…”

Improving the Performance of 4-State Turbo Codes with the Correction Impulse Method and Data Puncturing

“…The minimum spread was 32 and occurred for just two of the indices; most of the indices were associated with spreads greater than 40. This same interleaver was also studied in [12].…”

“…The latter method can deliver substantial reductions in the flare in return for reductions in code rate and energy per coded bit. These penalties are small for larger blocks but can be substantial for blocks of a few thousand bits or less (e.g., see [12]). A third is to analyze the distance spectrum and insert known symbols at positions associated with low-distance codewords [13].…”

“…One is to improve the distance spectrum of the code by optimizing the interleaver and puncturing patterns for a fixed constituent decoder [5,6,8]. Another is to serially concatenate the Turbo code with an algebraic code, typically a BCH code [11,12]. The latter method can deliver substantial reductions in the flare in return for reductions in code rate and energy per coded bit.…”