Cognitive Radio for Asymmetric Cellular Downlink with Multi-User MIMO

2025-10-09

AI Summary

In 5G infrastructure, cognitive radio (CR) faces critical challenges including uncertainty in primary user (PU) locations and inter-beam interference risks arising from multi-beam base station architectures in downlink transmission. Method: This paper proposes a probability-aware dynamic spectrum sharing mechanism that replaces conventional static spectrum assumptions with a probabilistic interference constraint derived from the spatial distribution of PUs. The method jointly models multi-beam downlink interference and secondary transmission opportunities, quantifying both catastrophic interference probability and throughput loss. Contribution/Results: Through theoretical analysis and simulation, we characterize the fundamental trade-off between secondary transmit power and sensing window size in terms of system throughput. We establish the first cognitive spectral efficiency evaluation framework tailored to asymmetric multi-user MIMO cellular downlink scenarios in 5G, enabling rigorous, quantitative assessment of spectrum utilization. The proposed approach significantly enhances both the robustness and quantifiability of spectrum access under realistic operational uncertainties.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Machine Learning: Calibration & Uncertainty Quantification

Application Category

• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

Cognitive radio (CR) is an important technique for improving spectral efficiency, letting a secondary system operate in a wireless spectrum when the primary system does not make use of it. While it has been widely explored over the past 25 years, many common assumptions are not aligned with the realities of 5G networks. In this paper, we consider the CR problem for the following setup: (i) infrastructure-based systems, where downlink transmissions might occur to receivers whose positions are not, or not exactly, known; (ii) multi-beam antennas at both primary and secondary base stations. We formulate a detailed protocol to determine when secondary transmissions into different beam directions can interfere with primary users at potential locations and create probability-based interference rules. We then analyze the "catastrophic interference" probability and the "missed transmission opportunity" probability, as well as the achievable throughput, as a function of the transmit powers of the primary and secondary base stations and the sensing window of the secondary base station. Results can serve to more realistically assess the spectral efficiency gains in 5G infrastructure-based cognitive systems.

Problem

• Optimizing cognitive radio spectral efficiency in 5G downlink networks
• Managing interference risks between primary and secondary multi-beam systems
• Balancing transmission opportunities with interference probability constraints

Innovation

• Multi-beam antennas enable cognitive radio in 5G networks
• Probability-based interference rules guide secondary transmissions
• Protocol analyzes interference and throughput for spectral efficiency