Examenspresentation av Vaidyanathan Kumar (MPICT)

Supervisors: Johannes Arvidsson (LumenRadio AB); Jafar Banar; Tommy Svensson (Chalmers)
Examiner: Tommy Svensson (Chalmers)

Abstract:
Wireless technology in globally available unlicensed frequency bands, also known as ISM bands, is facing greater challenges due to overcrowding caused by the growing number of wireless devices. The Internet of Things (IoT) expansion across various industries and applications has led to increased congestion, particularly in commercial buildings and industrial settings. In many cases, the congestion has become so severe that wireless solutions are no longer reliable and cannot effectively function. There is a clear need for resilient wireless technology capable of handling congestion, particularly in critical applications.

Wireless Sensor networks (WSNs) are low-power lossy networks that are widely used for different applications across various industries on the 2.4 GHz band. Frequency hopping techniques are used to effectively counteract the disturbance and interference. Time-slotted channel hopping (TSCH) is one of the frequency hopping techniques used in the MAC layer of low-power lossy networks. Therefore, evaluating the WSNs with TSCH is the main focus of this thesis. Particularly, the application of channel adaptivity used together with TSCH to avoid sources of disturbances will be investigated. This possibly mitigates/avoids packet losses and delays in transmissions, improving the overall behavior in an effective way.

The thesis investigates and evaluates the performance of Adaptive Frequency hopping. It will quantify the relationship between bandwidth and congestion for static hopping sequences, and how it changes by introducing more informed frequency choices. It will evaluate methods of updating hopping sequences, their efficacy, and potential diminishing returns. An implementation of the WiFi behaving as a jammer is made in LumenRadio’s in-house simulator MiraSim and from predefined use cases, simulations are run to evaluate the performance of different classes of channel implementations against multiple types of disturbances.
The results show that large mesh networks using adaptive frequency hopping perform better in the presence of multiple jammers. There is a significant increase in the PDR, which reduces the latency and current consumption of the nodes by adapting well to good channel conditions and successfully avoiding the channels interfered with by the jammers. There is also a comparison made with other classes of channel utilisation to observe how well adaptive frequency hopping performs.

Welcome!

Vaidyanathan and Tommy