Performance of a Frequency-Hopped Real-Time Remote Control System in a Multiple Access Scenario

The ubiquitous presence of powerful low-power wireless systems on chip (SoC) able to operate in the Industrial, Scientific and Medical (ISM) band has brought a new enhanced operational choice for real-time Radio Control (RC) applications such as aircrafts and cars in the hobby grade category. Frequency Hopping Spread Spectrum (FHSS) has become the dominant transmission technique for the previously mentioned hardware platform. Even though, FHSS provides for resilience to noise and interference, partial-band type of interference could be specially harmful with regards to the overall system performance. This is critical in real-time RC applications as it could increase system latency. The present paper characterizes the performance of a single real-time RC application, which operates in a realistic multi-user ISM environment by means of two main metrics: System Lag Occurrence Probability (SLOP) and Probability of Losing a Packet (PoLP). Both Synchronous FHSS Multiple Access (SFHSS-MA) and Asynchronous FHSS Multiple Access (AFHSSMA) environments have been modeled. Simulation results show the level of impact on system performance of key engineering parameters such as clock drift, number of co-located users, and variable data packet duty cycle.