Coded PHY and CTE are mutually exclusive

[p143]

According to BLE 5.1 Core Specification Coded PHY and CTE are mutually exclusive. But losing 4xRange to implement Direction Finding is a big loss if, for instance, you need working in a very noisy environment or it happens that you want to implement direction-finding outdoors (in a restricted area though), rather than GPS.

So my question is. Are both features going to be mutually excluding forever (that is, is theoretically impossible for both features to work together), or on the contrary, this could change in the future with some workarounds on the Long Range Specification? Thanks.

[Dmitry]

This requirement doesn't mean that you cannot use both features together. BLE specification allows to send extended advertisements and establish a connection at CODED PHY, but send AUX_ADV_IND (or LL_PERIODIC_SYNC_IND in connected state) pointing to periodic sync sequence containing CTE info at 1M PHY.  Also, in AoD case you can build an asymmetric (1M/CODED) channel - good antenna array with PA will give even better distance than long-range channel from mobile device. There's only one problem - almost no support for these features from manufacturers...

[p143]

Thanks Dmitry. But if your Project must have a footprint and consumption very limited as is in my case,  using a PA is out of consideration. What I specifically would need is transmitting CTE and advertising data from the mobile asset and both Coded PHY, that is, using AoA and in connectionless mode. Would this be possible with the actual BT5.1 Core Specification? Thanks

[Dmitry]

I don’t think using Coded PHY for AoA would make any sense. Let’s say, we have a central module with antenna array and some mobile devices, working in a very noisy environment. Coded PHY allows you to receive payload more reliably, but it wouldn’t improve reliability or accuracy of AoA measurement because direction finding operates with raw radio signal – it would just add significant overhead to payload transmission time (the one actually we don't need at all in CTE packet). If there are many devices working as AoA targets, an accuracy with Coded PHY will be even worse because of higher probability of interference from other devices.

The only thing I consider wrong is the requirement to have AUX_ADV_IND and AUX_SYNC_IND to be at the same PHY. If AUX_ADV_IND could be sent at 128K, we could reliably receive SyncInfo message, then, knowing time parameters and hopping sequence, listen for short (two-byte) access address at 1M – just to launch DFE (if SNR is so low that receiver can’t sync even on two-byte AA, I don’t think we will take any meaningful angle measurements).