No Free Lunch-Characterizing the Performance of 6TiSCH When Using Different Physical Layers

Area of Science:

• Wireless communication
• Internet of Things (IoT)
• Embedded systems

Background:

• Low-power wireless applications demand careful balancing of latency, reliability, data rate, and power consumption.
• The 6TiSCH (IPv6 over the Time Slotted Channel Hopping) protocol stack is standardized for industrial IoT applications, requiring optimized physical layer selection.

Purpose of the Study:

• To evaluate the performance of different IEEE802.15.4g physical layers within the 6TiSCH protocol stack.
• To determine the optimal physical layer strategy for diverse low-power wireless application requirements.

Main Methods:

• Augmented the OpenWSN (Open Wireless Network) 6TiSCH implementation to support three IEEE802.15.4g physical layers: FSK 868 MHz, OFDM 868 MHz, and O-QPSK 2.4 GHz.
• Deployed and tested the modified firmware on a 42-mote OpenTestbed in an office environment.
• Collected and analyzed performance data across various metrics for each physical layer.

Main Results:

• No single physical layer (FSK 868 MHz, OFDM 868 MHz, O-QPSK 2.4 GHz) demonstrated superior performance across all evaluated metrics (latency, reliability, data rate, power consumption).
• Performance varied significantly depending on the specific metric and the chosen physical layer.

Conclusions:

• A generalized 6TiSCH architecture should integrate multiple physical layers to adapt to varying application needs.
• Technology-agile radio chips, controlled by a dynamic protocol stack, can select the most appropriate physical layer on a frame-by-frame basis for enhanced efficiency.