Abstract:

With the proliferation of wireless technologies and devices, the wired connections are being replaced by wireless ones in many areas of our life. Wireless devices provide freedom and mobility. Wireless Personal Area Network (WPAN) is a network of such wireless devices with low power consumption. Bluetooth, Zigbee, and Ultrawideband (UWB) are the main technologies enabling WPAN. The main purpose of WPAN is to provide seamless data exchange between personal wireless devices such as cell phones, PDAs, and laptops that are often very mobile. HealthNet is an instance of WPAN in which sensors that monitor health conditions of people use the aforementioned wireless technologies to transfer gathered data to medical professionals for further analysis.

Very often, connectivity, throughput, and power are not a problem in wired network. However, these are the real problems in wireless network due to the various surrounding conditions, especially in WPAN. The merit of having WPAN is reduced power consumption which translates into reduced overhead and throughput, and these are directly related to connectivity. Also, WPAN devices are mobile devices which is another advantage of wireless network. But this mobility also introduces obstacles to maintaining permanent connectivity. Due to the nature of being wireless, security becomes another issue to consider in WPAN, especially in HealthNet.

This thesis proposes several potential solutions to the challenges mentioned above and shows their feasibilities through analysis, simulations and test-bed experiments. Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS) is invented to overcome the difficulty of maintaining permanent Bluetooth connections through scatternet in mobile environment. We have shown that OBP and TS is very comparable in terms of efficiency for throughput and power consumptions while solving the connectivity problem. BlueTorrent is a content sharing method among Bluetooth users by creating temporary and opportunistic connections, and it can be used in other areas of emergency situations and medical and hospital environments. Many health monitoring devices often adopt ZigBee technology and several interconnection methods are proposed to support HealthNet. Also, in order to overcome the connection setup latency of Bluetooth, Bluetooth 2.1 technology is adopted for emergency situations that require very fast and secure response.

The solutions proposed in this thesis attempt to support the challenges arise in WPAN, namely, connectivity, mobility and security. No perfect solution that support all these issues exists, but with tradeoff considerations, we can find better solutions for each scenario.