Abstract
Recent years have witnessed a massive growth in the number of wireless devices designed to be worn on the human body. Thanks to significant advances in computing, battery design and communication innovations, wearable technology has been finding an increasing number of applications in various aspects of our life. For example, the healthcare domain has seen widespread adoption of body area network (BAN) devices to provide remote health monitoring for patients away from medical centers. Wearable technology has also seen a surge in the popularity of high-end applications such as virtual reality devices, smart watches, etc. However, since wearable devices are typically small and battery-operated, efficient energy management is a fundamental requirement to prevent frequent battery charging or replacement. This dissertation proposes and investigates novel power control techniques which can be used to simultaneously prolong the lifetime of wearable devices and improve performance.The first technical chapter investigates some novel practical adaptive power control protocols based on channel deviation to enhance the energy efficiency and link reliability simultaneously in BAN applications. The proposed schemes are shown to be both flexible and relatively simple to implement on hardware platforms with constrained resources making them inherently suitable for BAN applications. The performance of proposed algorithms are profiled against traditional, optimal and other existing schemes for which it is demonstrated that not only does the outage probability reduce significantly, but the proposed algorithms also save up to 35% average transmit power compared to the competing schemes.
The second technical chapter introduces an analytical framework to analyze the performance of a practical adaptive power control method which has been used widely in BANs. Based on this, the average transmission power and average signal reliability are determined considering operation at 5.8 GHz and 60 GHz using physically-informed body centric channel models. It is shown that using a 60 GHz operating frequency for future BANs holds much more promise. The results show that, under certain conditions, combining the adaptive power control method with a millimeter-wave (mmWave) frequency can save up to 17 dB per transmission compared with broadcasting at a conventional microwave frequency such as 5.8 GHz. The final technical chapter utilizes multiple access points equipped with very large number of antennas to not only receive data, but also to supply wireless energy for wearable devices. In this context, power control mechanisms are introduced to ensure the fairness among users. It is shown that using radio energy harvesting combined with massive multiple-input multiple-output (MIMO) technology will be a viable solution for prolonging the lifetime of wearable devices while still guaranteeing an outage probability per-user of less than 10%, which satisfies the requirements of the IEEE 802.15.6 standard.
| Date of Award | Dec 2019 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Simon Cotton (Supervisor) |