Comparison of Contention-Based vs Timeslotted Channel Hopping Medium Access in Wireless Sensor Networks under Noisy Environment
32nd International Telecommunication Networks and Applications Conference (ITNAC 2022)
Contribution to Conference
Tiny sensors with a radio transceiver offer ubiq- uitous connectivity and ease of maintenance for Internet of Things (IoT) applications compared to wired counterparts. Most Wireless Sensor Networks (WSNs) utilize IEEE 802.15.4 standard for communication, which defines physical and Medium Access Control (MAC) layers architecture. Two most promi- nent MAC modes are unslotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and Timeslotted Channel Hopping (TSCH), which represent a randomized and scheduled solution, respectively. Considering diverse use-case requirements, the choice of a suitable MAC is error-prone. Existing literature only evaluates contention-based TSCH with a simplified physical layer and no external interference, obscuring TSCH strengths and limitations in comparison to CSMA/CA. This work fills the gap in understanding the potential of both MAC modes by comparing their performance using detailed simulations in OMNeT++ with a realistic radio model. A 100-node network with bidirectional communication is evaluated under variable WLAN interference, using the end-to-end delay and packet delivery ratio as performance indicators. Contrary to expectations, CSMA/CA may outperform TSCH depending on the interference pattern. At the expense of latency, TSCH achieves 100% reliability even in a highly congested medium thanks to the channel hopping. Overall, presented insights contribute greatly to the MAC selection process during an IoT network planning stage.