Deterministic identification for Bernoulli channels and related channels with continuous input

2026-05-06

AI Summary

This work addresses the long-standing gap between achievability and converse bounds for deterministic identification (DI) capacity over memoryless channels with continuous inputs. By introducing a channel reduction method based on input constraints to subintervals and developing a novel “galaxy” code construction, the paper establishes a unified DI capacity analysis framework applicable to Bernoulli channels and a broader class of channels with continuous output distributions. It proves for the first time that the DI capacity equals 1/2 for a wide family of continuous-input channels, thereby closing a longstanding open problem in the field. Furthermore, in the regime of small error exponents, the proposed approach significantly approaches the converse bound, improving the known lower bound on the rate-reliability tradeoff.

Abstract

For memoryless channels with continuous input alphabets, deterministic identification (DI) typically exhibits a linearithmic ($n\log n$) message growth. However, the exact DI capacity has long remained open due to a persistent gap between the best known achievability and converse bounds. This gap was recently closed for AWGN channels via a novel code construction optimising the "galaxy" codes. Here, we extend this approach to the Bernoulli channel and subsequently to any channel $W$ whose image contains a continuous curve of output probability distributions, and hence admits a reduction to the Bernoulli channel restricted to a subinterval of inputs. As a consequence, we prove that the converse bound is tight and establish $\dot{C}_{\text{DI}}(W) = \frac 12$ for this broad class of channels, thereby closing the long-standing capacity gap. A similar gap was also observed for the DI rate-reliability tradeoff. We analyse the tradeoff between rate and error of the proposed code and derive improved lower bounds on the reliability function, approaching the converse at leading order in the regime of small error exponents.

Problem

• Deterministic Identification
• Channel Capacity
• Bernoulli Channel
• Rate-Reliability Tradeoff
• Memoryless Channels

Innovation

• Deterministic Identification
• galaxy codes
• Bernoulli channel
• DI capacity
• reliability function