LTE-M a.k.a. Cat-M1 Technology

LTE-M. Also called Cat-M1. Like NB-IoT’s less sleepy cousin who actually shows up to work. Still LPWAN. Still over cellular. Still low-power. But faster, more interactive, and actually bi-directional. Meant for wearables, alarms, trackers – stuff that wants to talk more than once a day.

Vendor and URL

This techno-beast is rolled out by:
Main vendor: 3GPP (yeah, them again)
Official docs: https://www.3gpp.org
If the link’s dead, check your SIM card or your sanity. Either could be the issue.

Technical Public Documentation

You like reading? Good. You’ll be buried in LTE specs before you even blink.
Full spec: TS 36.300 (start here and prepare to suffer)
GitHub repo: https://github.com/ARMmbed/mbed-os
TL;DR: it’s all LTE under the hood, just with smaller boots.

Overview

LTE-M gives you low-power, mobile-friendly LTE. It can move, sleep, reconnect fast, and even do voice (VoLTE, baby). Data rates? Decent. Latency? Better than NB-IoT. Range? Still solid. Basically NB-IoT on caffeine with better manners.

Architecture

It’s just LTE. Same towers. Same core. Same operator headaches. Devices (UEs) connect to eNodeBs, talk through the EPC, land in your cloud. You don’t control the infra – you lease airtime and hope the operator did their job.

Device Roles

One role: LTE user equipment. No routers, no mesh, no neighbors. Just your device and the network. It talks, it listens, it does VoLTE if it feels fancy. Everything else is backend magic and billing systems.

Channelization

Licensed spectrum only – same LTE bands (Band 3, 8, 20, etc.) depending on country. Channel width is 1.4 MHz, so it doesn’t hog as much spectrum as full LTE. But don’t worry – you still pay premium rent to be there.

Frames

LTE MAC, RLC, PDCP, NAS – it’s all here. Just slimmed down for the little guys. Payload size is solid. You can send multiple KBs if you’re patient. Header overhead? Still LTE, so... yeah. Bring your frame budget.

Networking

Real IPv6 and IPv4. Real TCP, UDP, MQTT, HTTP – whatever your stack supports. Devices get IPs (via PDN). No peer-to-peer. Everything goes through the carrier. Public or private APNs. Choose wisely or nothing works.

Security

SIM-based auth. Same LTE encryption (128-bit), plus you can slap on TLS, DTLS, or VPN. It's telecom-grade. Until someone forgets to close a port on your cloud backend. Security’s only as good as the guy who configured your device.

Networking Process

Boot up. Attach to the network. Auth via SIM. Negotiate IP. Send data. Receive data. Maybe drop into PSM (Power Saving Mode) or eDRX (Extended Discontinuous Reception). Wake, repeat, or fail and panic-reboot. LTE-M life.

Use Cases

LTE-M is made for wearables, asset tracking, smart alarms, eHealth, VoLTE gadgets, connected trash bins on steroids. If you need mobility, bi-directional traffic, and still want low power – this is your lane. Just don’t expect to stream Netflix or ping every 3 seconds. This isn’t your phone plan.