Feedback holds a pivotal role in practical communication schemes, even though it does not enhance channel capacity. Its main attribute includes adaptability in transmission that allows for a higher rate of convergence of the error probability to zero with respect to blocklength. Motivated by this fact, we present a non-asymptotic achievability bound for variable-length coding with stop-feedback. Specifically, a general achievability bound is derived, that employs a random coding ensemble in combination with minimum distance decoding. The general bound is particularized for the Gaussian channel. Numerical evaluation of the bound confirms the significant value of feedback compared to transmission with fixed blocklength coding and without feedback.

翻译：反馈在实际通信方案中扮演着关键角色，尽管它并未提升信道容量。其主要特性包括传输的自适应性，能够使错误概率随码长增长以更高速率收敛至零。基于此，我们提出了变长停传反馈编码的非渐进可达界。具体而言，推导了一个通用可达界，该界采用随机编码集合结合最小距离译码。将通用界特化为高斯信道情形。数值评估证实，与无反馈的固定码长编码相比，反馈具有显著优势。