A3Sim // Universal 3GPP LTE / 5G NR Mobility & Retainability Suite

A3Sim is a vendor-agnostic, web-based radio network optimization (RNO) and mobility simulator designed to model cellular handovers, Event A3 triggers, and retainability (Radio Link Failure / RLF) across diverse macro-cell and micro-cell propagation environments.

🌐 Access the Live A3Sim Dashboard Here

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🚀 Key Features & Capabilities

1. 3GPP Compliant Propagation Profiles

Model different deployment topologies with profile-aware path-loss slopes, fading frequencies, and dynamic distance scaling:

• Urban Macro (UMa - 500m ISD): Standard urban macro layout with moderate path loss.
• Suburban Macro (1km ISD): Wide-area suburban deployment with gradual signal degradation.
• Rural Macro (RMa - 1.5km+ ISD): Open-terrain long-range link requiring high link stability and large TTT windows.
• Urban Micro / Small Cell: Dense small-cell deployment with rapid signal drops and tight handover boundaries.
• Microcell Cluster (Ping-Pong Risk): Overlapping sectors prone to frequent handovers and potential RLF during fast movement.

2. Rigorous Mobility Analytics & Visualization

• Precision Event A3 Marker: Handover success (HO Event) and ping-pong (Ping-Pong Event) markers explicitly bind to exact coordinates on the A3 threshold curve (Serving RSRP + A3 Offset + Hysteresis), guaranteeing mathematical compliance and visual clarity on the canvas.
• Retainability & RLF Monitoring: Real-time tracking of signal drop limits and headroom margins against custom thresholds.
• Interactive Controls: Fine-tune parameters instantly using standardized sliders:
  • A3 Offset (CIO): $-12\text{ dB}$ to $+12\text{ dB}$
  • Hysteresis: $0\text{ dB}$ to $4\text{ dB}$
  • Time-To-Trigger (TTT): Standard 3GPP TS 36/38 values ($0\text{ ms}$ to $5120\text{ ms}$)
  • RLF Drop Limit: $-120\text{ dBm}$ to $-95\text{ dBm}$

3. Professional OSS/BSS Interface & Mobile Support

• Dark-Mode Command Center: Built with Tailwind CSS and styled for telecom and RF engineering workflows.
• 3GPP Audit Trail Console: Real-time status stream logging simulation lifecycle events, threshold violations, and severity badges (INFO, SUCCESS, WARN, ERROR) with automatic auto-scrolling.
• Fully Responsive Mobile Layout: Optimized grid layouts, flexible headers, and font scaling designed to run seamlessly across desktop workstations, tablets, and mobile devices.
• CSV Telemetry Export: Export complete simulation datasets for offline drive-test and post-processing analysis.

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📐 Mathematical & 3GPP Standards Formulation

A3Sim implements standard 3GPP mobility evaluation criteria (TS 36.331 / TS 38.331) to model realistic radio link behavior:

1. Event A3 Condition (Neighbor Becomes Offset Better Than Serving)

A handover trigger condition is met when the neighbor cell's RSRP exceeds the serving cell's RSRP by the configured Offset plus Hysteresis over a sustained duration: $$RSRP_{neigh} - Hysteresis > RSRP_{serv} + CIO_{offset}$$

2. A3 Threshold Curve

The dynamic threshold line plotted on the chart is calculated at each distance step $d$: $$A3_{thresh}(d) = RSRP_{serv}(d) + CIO_{offset} + Hysteresis$$

• Note: Precision marker binding locks success (HO Event) and ping-pong (PP Event) markers directly to A3_thresh[trigIdx] at the precise trigger index.

3. Propagation & Signal Degradation

Signal attenuation across distance $d$ follows profile-aware path-loss slopes combined with multi-path fading and pseudo-random noise: $$RSRP(d) = Base - (Slope \cdot d) - Fading(d) + Noise(d)$$

4. Time-To-Trigger (TTT) Filtering

To prevent premature handovers in fluctuating signal conditions, the A3 condition must remain continuously satisfied across consecutive distance steps corresponding to the selected TTT duration ($0\text{ ms}$ to $5120\text{ ms}$).

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🛠️ Tech Stack

• Frontend: HTML5, Vanilla JavaScript (ES6+)
• Styling: Tailwind CSS (Dark Theme Configuration)
• Charting: Chart.js with responsive multi-axis rendering and custom canvas styling
• Typography: Inter & JetBrains Mono

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🏃‍♂️ Getting Started

You can test the application instantly via the Live Demo, or run it locally since it is a fully self-contained, single-file application (index.html):

1. Clone the repository:

   git clone [https://github.com/ethanfrancisco/A3Sim.git](https://github.com/ethanfrancisco/A3Sim.git)
   cd A3Sim