What are our options for a CE and FCC certified product using a custom protocol?

[simmania]

Hello,

We want to build our own custom protocol because the features we need are not available from existing protocols like BLE or Zigbee etc.
But it is beyond our reach to do a complete CE and FCC certification test.

If I understand correctly we can use pre-certified RF modules (precertified for CE and FCC) and build on top of protocols that are supported by that module. In that case we only need to do the standard CE and FCC tests for EMC compliance and one or twee RF tests (Transmitting power and spurious radiation test?).
We are thinking about a BL653 or BL654 modules from Ezurio, which are using the nRF52833 and nRF52840 respectively.

Which are the protocols (with pre-certified CE and FCC) on which we can build our own higher layers?

Are this IEEE802.15.4 and Enhanced Shockburst (ESB)?
Are there any others?

[Simonr]

Hi

Correct, if you use pre-certified modules new testing won't be necessary. In addition to IEEE 802.15.4 and ESB, you can also check out the Gazell Link Layer I guess, but depending on what you need you have to read up on what will be relevant for your use case. 

Best regards,

Simon

[simmania]

Hi Simon, thanks a lot for the answer.

We would like to create a wireless network with the following features:
- support for low latency events (device to master)
- support for multiple continuous parameter updates per device (device to master)
- robustness (BlueTooth and Wifi coexistance)
- support for a lot of devices using multiple masters.

To create this we would need a protocol that includes, or to which we can add:
- frequency hopping
- time slot transfers
- multiple star networks that can be synchronized (using multiple synchronized masters)

We want to add frequency hopping for more robustness and to improve coexistance with other protocols like BlueTooth, Wifi and Zigbee.
We want to add time slots to improve latency and allow all devices to send continuous parameter updates. The master(s) will orchestrate the time slots and tell each device which time slots to use.
We want to increase the number of simultaneous devices by optionally add masters. The masters need to synchronize the frequency hopping and time slots some how.

I studied ESB and Gazelle. It seems that Gazelle already has some frequency hopping and time slot support.
But we still have some questions:

Gazelle:
- Is it correct that Gazelle is based on ESB?
- What is the minimum supported time slot period?
- Is the code open source?
- Is this the main documentation about Gazelle? Or is there more?

ESB:
- Is ESB based on 802.15.4?
- How many frequency bands does ESB support (in the 2.4GHz area)?
- What is the raw transmission speed (for one channel)?
- Is the code open source?
- Is this the main documentation about ESB?
- Is there a commitment from Nordic that ESB will be available for some number of years?

802.15.4
- Can we add frequency hopping and time slots to 802.15.4?
- Is there a faster version of 802.15.4 (faster then 250 Kb/s)?
- Is it correct that 802.15.4 is not supported by the Nordic SDK (protocols that use 802.15.4 have their own implementation)?
- Is 802.15.4e supported?

Which of the three protocols above would you recommend as base?

[Kenneth]

simmania said:

We would like to create a wireless network with the following features:
- support for low latency events (device to master)
- support for multiple continuous parameter updates per device (device to master)
- robustness (BlueTooth and Wifi coexistance)
- support for a lot of devices using multiple masters.

To create this we would need a protocol that includes, or to which we can add:
- frequency hopping
- time slot transfers
- multiple star networks that can be synchronized (using multiple synchronized masters)

I am going to be honest and say that it's not possible unless you have a lot of engineers at hand and don't care about current consumption. But to answer your questions:

simmania said:

Gazelle:
- Is it correct that Gazelle is based on ESB?
- What is the minimum supported time slot period?
- Is the code open source?
- Is this the main documentation about Gazelle? Or is there more?

-Yes
-About 1ms
-No.
-That is the documentation yes.

simmania said:

ESB:
- Is ESB based on 802.15.4?
- How many frequency bands does ESB support (in the 2.4GHz area)?
- What is the raw transmission speed (for one channel)?
- Is the code open source?
- Is this the main documentation about ESB?
- Is there a commitment from Nordic that ESB will be available for some number of years?

-No
-Channel between 2 and 80, so about 79channels with 1MHz spacing in the 2.4GHz ISM band.
-You can get higher than 1MBps if you are using the 2MBps on-air datarate (without packet loss)
-Yes.
-Yes
-Yes.

simmania said:

802.15.4
- Can we add frequency hopping and time slots to 802.15.4?
- Is there a faster version of 802.15.4 (faster then 250 Kb/s)?
- Is it correct that 802.15.4 is not supported by the Nordic SDK (protocols that use 802.15.4 have their own implementation)?
- Is 802.15.4e supported?

-Should be possible to change the frequency yes and maintain whatever timing you want
-No
-The radio driver and source code is available: https://github.com/nrfconnect/sdk-nrfxlib/tree/main/nrf_802154 
-Not familiar engouh to know what the 'e' is.

Kenneth

[simmania]

Thanks Kenneth for the answers.

You start with saying that it is not possible unless...

Why do you say we need a lot of engineers for this? It seems ESB is a good base protocol to build on. Is it so difficult to add frequency hoppling and timeslots to ESB?

If we use a pre-certified module that is certified for ESB, is it correct that we do not have to re-certify the module when building on top of this ESB protocol?

[Kenneth]

It's not difficult to setup a proof of consept, the problem start when you want to make something that can go into a product.

You would need to think of how do you add devices to the system, how do you synchronize them, how do you ensure security, how do you ensure quality of service, how do you handle a device may be out of range, how do you handle multiple device that try to join the system at the same time, how do you add back-off functionality, how do you handle routing and addressing, how to handle buffering, which nodes can act as routers, relays, and central nodes, and the list go on. What ESB provides you is simple point to point communication using a known address, with configurable number of retransmits, everything else is something you need to implement.

Kenneth