IPhone BLE paired to nrf52840 running at full bandwidth. How many of these systems (IPhone paired to nrf52840s) can be in one room?

[day1ok]

I have many of these types of systems running in a single room but when I try to run more than 8 I start start to get errors. How many systems should be able to run in the same room at the same time?

[awneil]

Just to be clear: is that eight iPhones and eight nRF52840, with each iPhone connected to one nRF52840?

How big is the room?

day1ok said:

I start start to get errors.

What kinds of errors, exactly?

Presumably, these iPhones are also using WiFi?

Are there also other WiFi and/or BLE devices?

[day1ok]

Yes, eight iphones connected to eight nRF52840. 
1) Iphone #1 paired to nrf52840 #1
2) Iphone #2 paired to nrf52840 #2
etc...

Each system (one iphone paired to 1 nrf52840) is within a few feet of each other and the room is 10'x10'.

The error is loss of data that is being transmitted from the nRF to the iphone and this only happens when we have more than eight of these systems in a room. 

Yes, the iphones are also using wifi

It is an office environment and yes there are other wifi and bluetooth devices nearby no more than 10 computers, mice, phones, wireless headphones, etc.

[Sigurd]

day1ok said:

The error is loss of data

 How do you measure that? If you are in a very noisy 2.4GHz environment there might be packet collision, so that some packets might need to be re-transmitted, but you should not lose the data.

Also, can you explain what you mean by "running at full bandwidth" ?

[Markl]

Each of the 8 devices is transmitting data to the phone at max data rate (2Mbit). If we run nine or more devices simultaneously in a common space we begin to see an avalanche of packet collisions. These collisions seem to manifest in at least one of the devices' uP getting trapped in the soft device ISR, which leads to real-time failures such as watchdog timeout and starvation of other real time critical devices. One of our engineers characterized the issue as garbage collection taking a long time at highest priority ISR level, which locks out all other interrupts. I guess we really just want to know if eight device pairs is an expected number that can be supported with regard to high speed BLE data transfer, or if there is some parameters(s) we can try adjusting to improve the situation.