A Zero-Copy Hysteresis-Gated Adaptive FIFO/LIFO Buffer Architecture for Time-Sensitive Networking Under Dynamic Channel Degradation

Abstract

Elham Khalesi

Time-Sensitive Networking (TSN) guarantees bounded end-to-end latency for industrial and vehicular traffic, yet wireless and PLC edge segments suffer dynamic channel degradation that makes static FIFO buffering suboptimal: stale packets occupying the head of a FIFO queue inflate Age of Information (AoI) and violate deadlines exactly when the channel is weakest. This paper proposes a zero-copy, hysteresis-gated adaptive buffer architecture that dynamically reconfigures its logical discipline between FIFO and LIFO operation without physically moving stored bytes. The design is built around a dual-granularity SRAM core (512x8 low-granularity and 64x32 high-granularity banks) with shared pointer logic, an end-of-packet (EOP) boundary-gating mechanism that guarantees packet atomicity during mode transitions, and a four-state finite-state machine (FSM) implementing dual-threshold hysteresis so that the buffer never oscillates between disciplines under fluctuating occupancy. A closed-form Age of Information model is derived for hybrid FIFO/ LIFO service, showing that the proposed architecture reduces mean AoI by up to 38.7% and the 99th-percentile AoI by 51.2% versus a pure FIFO queue under Gilbert-Elliott channel degradation, at the cost of a bounded out-of-order delivery set that is resolved by the EOP gating stage. Synthesis on a Xilinx Artix-7 xc7a200t device closes timing at 250 MHz (4.00 ns critical path) with 1,842 LUTs and 1,150 registers, and RTL verification against a golden reference model achieves 100% coverage of the defined functional plan with zero mismatches. Congested-link experiments demonstrate a 27.9% reduction in deadline-violating packet drops and a 22.4% reduction in jitter compared with static FIFO buffering. The results indicate that zero-copy adaptive buffering is a practical, resource-light mechanism for resilient TSN ingress under time-varying link quality.

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