Unified Upper Bounds on the ML decoding Error Probability of Spinal Codes over Fading Channels
Aimin Li, Xiaomeng Chen, Shaohua Wu, Gary C. F. Lee, Sumei Sun
TL;DR
This work develops two deterministic finite-blocklength BLER upper bounds for Spinal codes over fading channels, unifying analysis across complex and real mappings. The first bound adapts a Gallager-based approach to fading, while a refined bound proves tighter by exploiting Spinal-code structure and a new F(L_a,σ,γ) term. The framework yields explicit closed-form bounds for Nakagami-m and Rician fading, and demonstrates that tail transmission pattern (TTP) is optimal under ML decoding. Simulations confirm the bounds are tight and that the refined bound significantly outperforms the Gallager-based one, providing practical guidance for evaluating and designing Spinal codes in diverse fading environments.
Abstract
Performance evaluation of particular channel coding has been a significant topic in coding theory, often involving the use of bounding techniques. This paper focuses on the new family of capacity-achieving codes, Spinal codes, to provide a comprehensive analysis framework to tightly upper bound the block error rate (BLER) of Spinal codes in the finite block length (FBL) regime. First, we resort to a variant of the Gallager random coding bound to upper bound the BLER of Spinal codes over the fading channel. Then, this paper derives a new bound without resorting to the use of Gallager random coding bound, achieving provable tightness over the wide range of signal-to-noise ratios (SNR). The derived BLER upper bounds in this paper are generalized, facilitating the performance evaluations of Spinal codes over different types of fast fading channels. Over the Rayleigh, Nakagami-m, and Rician fading channels, this paper explicitly derived the BLER upper bounds on Spinal codes as case studies. Based on the bounds, we theoretically reveal that the tail transmission pattern (TTP) for ML-decoded Spinal codes remains optimal in terms of reliability performance. Simulations verify the tightness of the bounds and the insights obtained.
