Blog (EN)
A Device Suddenly Disconnected from the Network — The Reality of 3G Service Shutdown
2026-04-18
3G services in Japan have been fully shut down. IoT devices that support only 3G can no longer communicate. This article breaks down why connectivity fails using the connection flow (Scan, RRC, NAS) and explains structurally where the failure occurs.
Why Can Devices Stay Connected After Attach? — The Mechanics Behind Handover
2026-04-11
A structural explanation of why IoT devices maintain connectivity while moving, focusing on the post-Attach state, RRC control, and the internal mechanics of handover
Why Can Devices Access the Internet from a Nearby P-GW After Attach?
2026-04-04
A structured explanation of how Local Breakout is realized from the perspective of the Attach procedure and P-GW selection
Why Can We Access the Internet After Attach?
2026-03-28
This article explains why Attach alone does not enable communication, and how a GTP session establishes Internet connectivity.
How Devices Discover Cellular Networks
2026-03-21
Explains how cellular devices detect radio signals and select networks from the perspectives of Band, frequency, RAT, and PLMN
Why Initial Roaming Connection Takes Time?
2026-03-14
This article explains, in a structured way, why initial connection takes time in cellular roaming environments and what can be done in design to improve it.
Think of IoT as Structure
2026-03-07
A framework for breaking down IoT systems into layers — and why it matters for design.
Introduction
2026-02-28
Overview of this blog