Is feedback a performance equalizer of classic and modern codes?

Abstract

Abstract-It is well known that in general, feedback cannot increase the capacity of a discrete memoryless channel. However, it can help simplify the complexity of encoding and decoding. Schalkwijk and Kailath (1966) developed a class of block codes for Gaussian channels with ideal feedback. They showed that the probability of decoding error decreases as a second-order exponent in block length for rates below capacity. This paper proposes a coding scheme with ideal feedback and is applied to punctured convolutional codes and punctured Turbo codes. Our results seem to indicate that feedback largely equalizes the performance of classic (convolutional) codes and modern (turbo, LDPC) codes.

Forward Error Correction Convolutional Codes for RTAs' Networks: An Overview

“…In hybrid codes the involved algorithms are put either in serial or parallel with the convolutional code, another good example of this can be seen in the work by T-Y. Chen et al [46] where a Modified Incremental Redundancy with Feedback (MIRF) allows short convolutional codes to deliver bit error rate performance similar to a long block length turbo code, but with lower latency. Many other examples of this type can be seen in M. Francis and R. Greens' contribution [47].…”

Incremental redundancy: A comparison of a sphere-packing analysis and convolutional codes

“…This section extends the sphere-packing analysis to examine the latency vs. throughput curve possible with the MIRF scheme of [1] for using incremental redundancy and feedback.…”

“…As a practical demonstration, [1] showed that using modified incremental redundancy with feedback (MIRF) allowed short convolutional codes to deliver bit-error-rate performance comparable to a long blocklength turbo code, but with lower latency. The demonstration of [1] qualitatively agrees with the error exponent analysis in [5]- [8]. However, the error-exponent theory does not provide a crisp prediction of the quantitative latency benefit possible with MIRF at a specific throughput.…”

“…The baseline system has a feedback link but uses it only for ACK/NACK; in other words, it's the simple ARQ scheme. The MIRF system is similar to the one studied in [1]. The analysis uses spherepacking and bounded-distance decoding to model the behavior of a "good" code for the AWGN channel.…”

“…Chen et al [1] demonstrated that a modified incremental redundancy scheme can use noiseless feedback to help short convolutional codes deliver the bit-error-rate performance of a long blocklength turbo code, but with much lower latency. This paper presents a code-independent analysis based on sphere-packing that approximates the throughput-vs.-latency achievable region possible with feedback and incremental redundancy for a specified AWGN SNR.…”