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CC2541: Encryption impact on throughput

Part Number: CC2541

I need to send a lot of bytes via BLE. I am able to view current consumption of CC2541 on oscilloscope. So i see how CC2541 transmit and receive packets each connection interval. And i noticed that when my connection isn`t encrypted CC2541 sends 3 or 4 packets per connection interval. Such situation provides sufficient level of throughput at 30ms connection interval condition. But i need encrypted connection. After enabling pairing and bonding i noticed that CC2541 sends 2 or rarely 3 packet per connection interval. It`s not enough to provide desirable level of throughput. I use BLE Bridge application on CC2541 and nRF connect on Nexus 5 smartphone. I have no idea which side makes such impact on throughput. And my question is - is it common for ble stack (CC2541) to reduce amount of packet per connection interval if encryption is enabled?

  • Hello Bulat,

    The CC2541 can send & receive four 27 byte PDUs during a connection event when encryption is enabled. This assumes you have queued these packets prior to the start of the connection event. One way to check is to take a BLE packet (air) sniffer trace. You can see if the central is transmitting during the 3rd packet of the connection event. If not, then the peer device is not able to accept the packet.

    Best wishes