nordic to nordic BLE, is it faster then nordic to other BLE capable device ?

Question

hello Nordic 
 
 recently i encounter a claim that nordic to nordic BLE is faster, or capable of transferring more bits of data per second, then a nordic communicating with a non nordic device which is BLE capable. 
 i am referring to the nrf52 series, but the question is general. 
 is there a base in hardware or software to this claim ? is there some specific software configuration, change in the BLE low level protocol, or special hardware ability use that allow faster data transfer over BLE with nordic to nordic device in compare to nordic and non nordic device ? 
 
 best regards 
 Ziv

daviddedwin · Answer

This is definitely possible and likely. I can think of at least 2 examples: 
 1. The Nordic softdevice is capable of filling the entire connection event with TX/RX if data is available and enough memory buffers have been provided to the controller/link layer, so if 2 Nordic devices are operating as master and slave, they can each fill the entire connection event, thus maximizing bandwidth. 
 However lets assume that one of the other devices is not Nordic and can only handle 6 packets in a connection event due to memory or stack constraints, then when the non Nordic and Nordic device are in a link, the connection event will close after a maximum of 6 TX and RX (since the non Nordic can only do 6 packets in an connection event). This will effectively constrain the bandwidth of the link to the less efficient device. 
 2. The speed at which the Nordic device (nRF52) can setup the encryption in a connection between bonded devices is 2-3 connection events, this means that data flow can happen as soon as the link is encrypted. If two Nordic devices are in the connection then data starts flowing after 2-3 events, however if a non Nordic device is in the connection and takes 5-10 events to setup the encrypted link, then data will be delayed by the extra connection events thus impacting the latency of the data in the link. 
 There may be more but these are the top ones in my list, maybe others will remember more. You should be able to capture these on a sniffer to verify them. Please accept my answer and upvote if this answers your question.