900 MHz for real-time location: how it works, range and accuracy

900 MHz refers to a group of unlicensed ISM bands that sit below Wi-Fi and Bluetooth's more familiar 2.4 GHz, most commonly 902–928 MHz in North America and a narrower 863–870 MHz allocation in Europe. It's used by a mix of proprietary active RFID systems, some low-power wide-area network (LPWAN) technologies, and passive UHF RFID (covered separately on our passive RFID page). This page focuses on active, location-relevant use of the band.

Key specifications

Because 900 MHz covers a range of proprietary and regional technologies rather than one single standard, these figures vary more than for a single defined protocol like BLE or UWB.

How it works

900 MHz sits at a lower frequency than the bands most other technologies in this series use, and that has predictable consequences based on the physics covered in our radio frequencies guide: longer wavelengths generally travel further for a given transmit power and diffract more readily around obstacles, giving 900 MHz systems an advantage in range and building penetration over higher-frequency alternatives like 2.4 GHz or UWB.

Most active 900 MHz location systems rely on RSSI, the same fundamental measurement described in our measurement basics guide: signal strength at one or more fixed readers is used to estimate proximity or a rough zone, rather than a precise coordinate. Because 900 MHz systems are typically proprietary rather than built around a single common standard, the exact measurement approach, and the resulting accuracy, varies considerably between vendors. Some systems use denser reader networks and more sophisticated signal processing to improve on basic RSSI zoning, but centimetre- or even sub-metre-level accuracy generally isn't the goal of this band.

Regulatory power limits at 900 MHz differ substantially by region, which directly affects achievable range: a system designed around North American 902–928 MHz allocations may need reconfiguration or different hardware for Europe's narrower and more restricted 863–870 MHz band.

Measurement methods available

• RSSI-based proximity and zone estimation – the primary method used across most active 900 MHz systems
• Vendor-specific ranging techniques – some proprietary systems layer additional timing or signal-processing methods on top of RSSI, though these aren't standardised across the band

Advantages

• Longer range and better building penetration than higher-frequency bands like 2.4 GHz, for a given transmit power
• Less crowded than the 2.4 GHz ISM band in many environments, reducing interference from Wi-Fi and Bluetooth traffic
• Active tags can achieve long battery life, particularly with infrequent transmission intervals
• Well suited to covering large areas with relatively few fixed readers, given the longer range per reader

Limitations

• Accuracy is generally coarser than 2.4 GHz-based or UWB systems, usually zone- or room-level rather than precise
• Lack of a single dominant standard means systems and tags from different vendors are often not interoperable
• Regional regulatory differences in power limits and exact frequency allocation complicate global deployments
• Narrower bandwidth than technologies like UWB limits the precision of any timing-based ranging that is attempted

Typical applications

900 MHz systems are typically used where covering a large area with relatively few fixed readers matters more than precise positioning: wide-area asset tracking across large facilities or yards, and some active RFID or LPWAN-based telemetry and monitoring applications where proximity or zone-level location is sufficient.

Frequently asked questions

Is 900 MHz better than 2.4 GHz for indoor location? It depends on the priority. 900 MHz generally offers better range and penetration through building materials, while 2.4 GHz technologies like BLE typically offer better accuracy and a more standardised, interoperable ecosystem.

Why does 900 MHz range vary so much between regions? Regulatory bodies set different power limits and exact frequency allocations for the 900 MHz ISM band in different parts of the world, which directly affects how far a given system can transmit.

Can 900 MHz achieve precise, sub-metre location? Generally not as a primary characteristic of the band. Most 900 MHz location systems are built around zone or proximity detection rather than the precise ranging or angle measurements used by technologies like UWB or BLE AoA.

Related reading

• What are radio frequencies and how are they used for indoor location
• Measurement basics of location systems: distance and direction
• 433 MHz for real-time location
• Passive RFID for real-time location