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WALNUT - Hard to crack

Wireless Ad-hoc Links using robust Noise-based Ultra-wideband Transmission

Project Number: STW 11317

Project Manager: Dr.ir.M.J.Bentum

Faculty of Electrical Engineering, Mathematics and Computer Science

Tel.: +31-53-4892108

Email: m.j.bentum@utwente.nl

Project website:

Summary

Wireless Sensor Networks (WSNs) are widely seen as a key enabling technology to create an "internet of things" which can support numerous new applications (see utilization summary paragraph). Once the sensor nodes are very cheap and small, "smart dust" networks might even become a reality. Such WSNs should preferably work autonomously, creating ad-hoc networks. They should also consume very low power to allow for battery-less operation of sensor nodes via energy harvesting. Recent research results indicate that this is only feasible using communication protocols that allow for very low-duty-cycle operation [1],[2], bringing average power down a few hundred μW [3]. Still, for energy harvesting less power and hence lower duty-cycle is desired.

As the feasibility of WSNs has been shown, they are used more and more. However, WSNs might quickly become a hazard to themselves as there are only a few radio bands in which these devices communicate (e.g. the 2.4 GHz ISM band). The spectrum thus easily becomes overcrowded. Moreover, other devices with more powerful transmitters often work in the same frequency bands. Hence the robustness of WSNs is likely to become the next major challenge. It might even become a major roadblock for successful ubiquitous deployment of WSNs.

In this project we intend to focus on the communication robustness problem while maintaining or even reducing low power consumption, compatible with energy harvesting. We propose to explore wideband modulation to enable robust wireless communication in a crowded, interference-rich environment. Spread spectrum techniques use wideband modulation and can provide such robustness [4],[5]. However, they are usually power-hungry, most notably due to timing synchronization issues. We believe we can tackle these issues employing a noise-based ultra- wideband transmission technique that we proposed in [6],[7], which exploits a transmitted reference technique. This technique can achieve high processing gain with very small synchronization times [6],[7] and hence low duty-cycle and low power. Initial research shows promising results and we would like to pursue this path further.

The goal of the project is to develop robust radio links for WSNs that operate in an

extremely crowded radio spectrum, at very low power.

To realize this vision we propose to work cross-disciplinary with three PhD students in three neighboring but distinct fields: 1) the (noise-based) modulation technique ("MOD-PhD"); 2) low- power IC Design ("ICD-PhD") of the radio transmitter (modulation) and receiver (demodulation); 3) communication protocols ("MAC protocols", "MAC-PhD"). We will work closely with interested industrial partners with experience in the WSN field from the application to the implementation platform level (DevLab, NXP, Thales). The results will be validated by prototypes on silicon.

Project duration: 2011-2015

Project budget: 636.752 €

Number of person/years: 3.6 fte /yr

Involved groups: Telecommunication Engineering (TE), Integrated Circuit Design (ICD), Design and Analysis of Communication Systems (DACS)