AI and Cognitive Radio Enable 5G and Naval Radar Coexistence

This article provides an overview of how radio frequency spectrum sharing systems enable commercial 5G networks to operate alongside military naval radar bands without causing harmful interference. By leveraging cognitive radio sensing to detect active military transmissions and deploying interference-avoidance artificial intelligence to dynamically reallocate commercial signals, these systems ensure maximum bandwidth efficiency and strict operational security for both defense and civilian sectors.

The Challenge of Spectrum Scarcity

The rapid expansion of commercial 5G networks requires vast amounts of radio frequency (RF) spectrum, particularly in the mid-band frequencies (such as the 3.5 GHz band). Historically, the federal government and the military have held exclusive rights to these bands, using them primarily for high-powered naval radar systems.

Relocating military systems to different frequencies is prohibitively expensive and technologically complex. The solution is dynamic spectrum sharing. In this framework, military users remain the primary incumbents with absolute priority, while commercial 5G providers act as secondary users. 5G networks can utilize the frequencies only when and where naval radars are inactive.

Cognitive Radio Sensing: Detecting the Radar

To prevent 5G networks from interfering with vital defense operations, the sharing system must know precisely when a naval ship activates its radar near a coastline. This is achieved through cognitive radio sensing, often deployed via a network of coastal sensors known as an Environmental Sensing Capability (ESC).

Cognitive radios are intelligent transceivers capable of perceiving their RF environment. Unlike traditional radios locked into specific frequencies, cognitive radios continuously monitor wide swaths of the spectrum. They accomplish this through:

  • Energy Detection: Measuring the raw RF energy in a specific band to determine if a signal is present above the background noise floor.
  • Feature Detection: Identifying the unique physical characteristics of a signal, such as the specific pulse width and repetition intervals of a naval radar.
  • Noise Floor Differentiation: Distinguishing between an actual military transmission and random atmospheric noise or overlapping commercial broadcasts.

Interference-Avoidance Artificial Intelligence

While cognitive radios act as the ears of the system, interference-avoidance artificial intelligence acts as the brain. Once a sensor detects a naval radar, the system typically has less than a minute to clear commercial 5G traffic from that frequency. AI makes this real-time transition possible through several mechanisms.

Signal Classification

Deep learning models analyze raw RF data collected by the cognitive sensors to accurately classify the signal. The AI is trained to recognize the exact "fingerprint" of military radar pulses. This ensures the system does not accidentally shut down a 5G network due to a false positive, while guaranteeing that genuine military signals are never ignored.

Predictive Modeling

Instead of simply reacting to a radar signal after it appears, machine learning algorithms analyze historical spectrum data and interference patterns. By understanding the temporal and spatial habits of spectrum usage, the AI can predict potential conflicts and proactively prepare commercial networks to shift frequencies before interference occurs.

Dynamic Resource Allocation

When a naval radar enters a coastal zone, the AI calculates the exact geographical area where 5G signals might cause interference. Using reinforcement learning, the AI determines the most efficient way to adjust the 5G network. Depending on the proximity and power of the naval radar, the AI will automatically command specific 5G base stations to:

  • Lower their transmission power to shrink their coverage footprint.
  • Shift commercial traffic to a completely different, uncontested frequency band.
  • Alter the direction of the 5G antennas (beamforming) to point away from the naval vessel.

The Spectrum Access System Architecture

The integration of cognitive sensing and AI happens within a centralized cloud architecture, commonly referred to as a Spectrum Access System (SAS). The SAS acts as an automated traffic controller for the airwaves.

  1. Detection: Coastal cognitive radio sensors detect a naval radar pulse in the 3.5 GHz band.
  2. Verification: Edge-based AI confirms the signal is an incumbent military system and not an anomaly.
  3. Calculation: The centralized AI calculates the precise "exclusion zone" required to protect the radar from 5G interference.
  4. Execution: The SAS sends automated commands to the commercial 5G base stations within that zone, migrating civilian mobile traffic to clear channels in milliseconds.

Through this continuous loop of sensing, analysis, and automated action, commercial 5G users experience uninterrupted connectivity, and military naval radars operate with zero degradation to national security capabilities.