BLE reliability and range for safety-critical alert transmission (>60 m, sub-second latency)

RE: BLE reliability and range for safety-critical alert transmission (>60 m, sub-second latency)

Kai St — Fri, 07 Nov 2025 10:39:56 GMT

Dear Simon,

thanks for your feedback! We will discuss that internally and I will get back to you if we need support with contacting the correct sales representative.

best regards,

Kai

RE: BLE reliability and range for safety-critical alert transmission (>60 m, sub-second latency)

Simonr — Wed, 05 Nov 2025 11:42:52 GMT

Hi Kai

I personally don't have experience with sub-GHz approaches like this, so I can't speak for it being more or less reliable than BLE. I focus on the 2.4GHz band I'm afraid.

The only sub-GHz SiP series we have is the nRF91 series, but that is a LTE-M/NB-IoT based technology and not the best for low latency AFAIK. I think contacting the Nordic sales representative of your area will have a better idea on what is the best fit for your use case to be honest. Let me know if you need help contacting the regional sales manager of your area and I will help you out with that.

Best regards,

Simon

RE: BLE reliability and range for safety-critical alert transmission (>60 m, sub-second latency)

Kai St — Tue, 04 Nov 2025 12:28:36 GMT

Hey Simon,

thanks so much for your detailed and honest feedback — that’s extremely helpful!

To clarify our approach: we are indeed aware of BLE’s limitations for safety-critical communication and are therefore considering a dedicated RF link between two devices. The BLE option was a recommadation of a development partner but we are (as you also wrote) sceptic if the connection would be reliable enough.

Our current plan is to use a sub-GHz link (around 868 MHz, EU) with a proprietary ACK-based protocol (including retries, frequency hopping, and AES encryption) for the primary alarm transmission, while BLE is used only for non-critical functions (configuration, logging, OTA updates).

From your experience —

• would you consider such a proprietary sub-GHz approach significantly more reliable and deterministic than BLE for safety use cases?

• and which Nordic SoC or transceiver would you recommend as the most suitable hardware basis for this type of setup (range ≈ 70 m, low latency < 1 s, low power)?

We’re trying to find the right balance between reliability, power consumption, and integration effort — any guidance on the best-fitting Nordic solution would be highly appreciated.

Many thanks again for your time and expertise.

Best regards,

Kai

RE: BLE reliability and range for safety-critical alert transmission (>60 m, sub-second latency)

Simonr — Tue, 04 Nov 2025 11:23:01 GMT

Hi Kai

Before I get to answering the questions. Note that BLE will never be 100% reliable or safe if this is to be used in a life or death matter we can't recommend that. Potentially look into a proprietary communication protocol for reliable comms like ESB or ANT+ for example.

1. Based on the use case you have given, as long as there aren't multiple other 2.4GHz devices in the same area. 1Mbps should be fine up to 70m in an open field without interference and Coded PHY should be more reliable, but might not be able to deliver an alarm within 1s as Coded PHY communication takes longer.

2. With good antenna design it should be pretty stable, but again, due to Bluetooth as a whole not being 100% reliable it can't be expected.

3. No, not for a critical alert link.

4. The nRF54L series should be capable of this, but not with Bluetooth LE I'd say.

Best regards,

Simon