# 4G LTE

> 4G cellular links that bring remote sites online anywhere with coverage

- **URL**: https://www.iiotsys.net/technologies/4g-lte
- **Markdown**: https://www.iiotsys.net/technologies/4g-lte.md

## Overview

4G LTE cellular connectivity gives industrial devices a wide-area uplink where wired broadband or plant Wi-Fi is unavailable. Typical IIoT uses include remote pump stations, solar farms, roadside cabinets, temporary construction sites, and backup WAN for critical gateways when the primary fiber or DSL link fails.

LTE modules and routers present a familiar IP interface to the rest of the system, so Modbus TCP, MQTT, VPN, and HTTPS traffic can ride the cellular bearer with the same application logic used on Ethernet—subject to carrier coverage, SIM policy, and data caps.

## Details

Cellular is the default wide-area option for unmanned sites. A gateway with dual SIM or multi-carrier support can fail over between operators; many deployments terminate an IPsec or WireGuard VPN from the field device into a central OT or cloud broker so that private addressing and firewall rules stay under operator control. Store-and-forward buffers on the gateway matter when coverage drops in tunnels, remote valleys, or during maintenance windows.

Watch the operational constraints. LTE latency and jitter are higher and less predictable than plant Ethernet, so closed-loop control usually stays local; cellular is better for SCADA polling, alarm push, firmware updates, and cloud telemetry. Prefer MQTT or compressed periodic payloads over chatty polling to control SIM cost. Confirm regional band support (FDD/TDD), industrial temperature ratings for outdoor enclosures, and antenna placement away from metal roofs and EMI sources.

Choose 4G LTE when the site has no reliable wired WAN, when you need rapid commissioning without waiting on telco fiber, or when cellular is the secondary path for resilience. For ultra-low-power battery sensors over long range with tiny payloads, LoRaWAN is often a better fit than always-on LTE.