Bluetooth Low Energy with Software-Defined Radio: Proof-of-Concept and Performance Analysis

Software-Defined Radios (SDRs) enable more flexible connectivity solutions than traditional systems, but still face several challenges hindering their widespread adoption. General-Purpose Processor (GPP) based SDRs have generally been too slow for low-latency protocols. Meanwhile Field Programmable Gate Array (FPGA)-based SDR setups suffer from high prices and a steep learning curve for developers. This paper investigates the feasibility of implementing Bluetooth Low Energy (BLE) in a GPP based Peripheral Component Interconnect Express (PCIe) connected SDR. In particular, we focus on adhering to the timing requirements of BLE in a practical SDR implementation. For this, we propose a multi-threaded implementation based on a subset of the open-source BLE library BTLE. Using a signal generator and oscilloscope, we show that the SDR is able to achieve a response time down to 105 μs and can accurately respond in the required $150\pm 2\ \upmu\mathrm{s}$ Inter Frame Space (IFS) time window. Furthermore, we also validate that channel hopping is supported by the SDR-based platform. To the best of our knowledge, this is the first SDR implementation able to meet the IFS requirements of BLE, hereby leading the way for more complete fully software based BLE protocol stacks.