Simulation and analysis of concurrent BLE link layer state machines running within the same physical device

Since the Bluetooth Low Energy (BLE) technology was first introduced in 2010 as a part of the Bluetooth 4.0 core specification, there were different improvements applied in the Link Layer (MAC) of the version iterations followed by. One of the key concepts in this layer is the possibility for creating multiple Link Layer state machines (often abstracted as roles), which are able to run concurrently within the same physical device. As BLE is one of the most important technologies in the Internet of Things (IoT), this functionality attracted many researchers and developers. Possibly the most well-known state machine combination is the Advertiser-Scanner, that is used in relay devices of every multihop communication solution based on the broadcast mesh approach, but in other application areas there can occur many other combinations also, especially if one takes into consideration the edge (or fog) computing concept in the IoT world. For being capable to assess the key performance metrics (e.g. delay, throughput, etc.) of these state machines running concurrently on the same device, there was a simulator developed, which is presented in this paper, as well as the analysis of different scenarios (including their practical occurrence, possible bottlenecks and workarounds) based on the results obtained with it.