Channel-Token Attention for Reliable Dynamic Spectrum Access under Bursty Primary-User Traffic
2026-08-24 • Networking and Internet Architecture
Networking and Internet ArchitectureMachine Learning
AI summaryⓘ
The authors developed TACAN, a system that helps secondary users share wireless channels without interfering with primary users who use the channels irregularly. TACAN uses tokens to represent channel activity and user information, and employs a Transformer-based approach to decide channel assignments. Their tests show TACAN improves access success and reduces delays compared to other methods, especially under heavy primary-user load. However, it does not increase the total number of packets delivered, only the reliability and timeliness of access.
dynamic spectrum accesssecondary usersprimary userschannel assignmentTransformer encoderproximal policy optimizationautomatic modulation classificationpacket delivery delaypacket reliability
Authors
Krishna Acharya, Dinanath Padhya, Utsab Dahal, Ashish Kandel, Binod Sapkota
Abstract
Dynamic spectrum access must coordinate secondary users under bursty primary-user activity while preserving packet reliability and delay. We present TACAN, a centralized policy that represents each channel as a token containing occupancy history and automatic-modulation-classification entropy; a context token supplies queue class, delay and user identity. A Transformer encoder is warm-started from an occupancy-greedy policy and refined with proximal policy optimization. The frozen policies were trained to maintain a channel assignment in every slot, including when queues were empty. We therefore replay them on held-out trajectories and distinguish standby assignment success from packet-present access and packet delivery. In a 20-channel network with 60 primary devices and 4 secondary users, TACAN achieves 92.53% +/- 0.47 packet-present access success, compared with 89.94% for Greedy and 83.53% for PPO+MLP. Its paired gain over Greedy is 2.59 points (parametric 95% CI 1.89-3.29), with wins in all five seeds; the exact two-sided sign-test value is 0.0625. The gain rises from 0.57 points at normal primary-user load to 7.67 points at extreme load. TACAN also reduces mean delivery delay from 1.208 to 1.123 slots and the conditional user-reliability gap from 9.69 to 3.15 points. Delivered packets per SU-slot remain arrival-limited (30.12% versus 30.11%), so no packet-throughput gain is claimed.