Maulin Dahyabhai Patel

Applications, challenges, and prospective in emerging body area networking technologies

Advances in wireless technology and supporting infrastructure provide unprecedented opportunity for ubiquitous real-time healthcare and fitness monitoring without constraining the activities of the user. Wirelessly connected miniaturized sensors and actuators placed in, on, and around the body form a body area network for continuous, automated, and unobtrusive monitoring of physiological signs to support medical, lifestyle and entertainment applications. BAN technology is in the early stage of development, and several research challenges have to be overcome for it to be widely accepted. In this article we study the core set of application, functional, and technical requirements of the BAN. We also discuss fundamental research challenges such as scalability (in terms of data rate, power consumption, and duty cycle), antenna design, interference mitigation, coexistence, QoS, reliability, security, privacy, and energy efficiency. Several candidate technologies poised to address the emerging BAN market are evaluated, and their merits and demerits are highlighted. A brief overview of standardization activities relevant to BANs is also presented.

Energy efficient methods of encoding destination address to address overhearing problem in BAN

Many duty cycling MAC protocols exploit preamble sampling technique to improve the energy efficiency. In this technique, all the devices periodically listen to the medium for a short duration and then go back to sleep if medium is found idle. When a device wants to send data it transmits a long preamble followed by data bits. When the receiver wakes up and detects the preamble it stays awake until it receives the data. This technique suffers from overhearing problem (i.e. the non target neighboring devices will also overhear the preambles and stay awake until data transmission begins) which wastes energy. To address overhearing problem, XMAC protocol embeds the ID of the target device into the preamble frame which enables nontarget neighboring devices to go back to sleep. The problem with this approach is that the receiver has to demodulate and decode the received frame to recover the destination address which is more complex and energy hungry process than pure preamble sampling. To decode the destination address without demodulating the received frame we encode the destination address as the length of the preamble frame. Thus, by measuring the duration of the preamble frame the receiving device can determine whether it is the intended target of the frame without invoking expensive demodulation process. We derive the energy consumption model for XMAC protocol and compare the performance of the proposed technique against the XMAC. Numerical results derived using the IEEE 802.15.4 compliant CC 2530 radio parameters show that proposed method outperforms XMAC in energy efficiency and latency thereby improving QoS.

A Data-Driven Approach for Accurate Estimation and Visualization of Energy Savings from Advanced Lighting Controls

Despite occupancy-based switching and daylight-based dimming controls being widely believed to have tremendous energy saving potential, there is often a lot of variability in the actual savings across customer sites. A major challenge in a reliable, site-specific assessment of these advanced lighting controls is the skew associated with time-logging using a low-power clock. We develop a robust analytical approach based on grid-search optimization and linear regression to correct the clock skew by exploiting the information stored in the cyclical nature of occupancy patterns in commercial buildings. We provide independent validation of the results using illuminance data to illustrate the strength of our approach. We also conduct comprehensive sensitivity analyses of the results by varying the assumptions about the underlying parameters values. Our results demonstrate that believable visualizations and reliable savings estimates can be generated using a low-power clock and a set of data-driven algorithms and analytics.

Preliminary results from an advanced lighting controls demonstration at Fort Irwin

In this paper we present preliminary results from a demonstration of the OccuSwitch wireless system deployed at Ft. Irwin, CA. Preliminary post-retrofit Energy Use Intensity (EUI) and Lighting Power Density (LPD) are compared with a pre-retrofit metered baseline (MB), an adjusted metered baseline (AMB) derived to account for changes in lamp distribution, and a code baseline (CB) representing a relatively old lighting system with 10 operating hours per workday. Early results (based on 3 months of post-retrofit data) indicate a 4% savings in EUI over the MB, 22% savings over the AMB, and 62% savings over the CB.