(A) cooperative clustering protocol for energy saving of multi-radio wireless devices

Abstract

One of the most widely used wireless communication standards is Wireless Local Area Network (IEEE 802.11). However, WLAN has a serious power consumption problem: energy consumed by WLAN interfaces accounts for more than 50\% of the total energy consumption in hand-held devices. This thesis proposes a novel energy saving approach that exploits the multi-radio feature of recent mobile devices equipped with WLAN and Bluetooth interfaces. About 70\% of smartphones in the market have a Bluetooth interface as a secondary radio for personal area networking. The Bluetooth standard is primarily designed for low power consumption, requiring only about a tenth of the WLAN power. However, because of its limited power, Bluetooth supports a low bandwidth of only 2 Mbps (version 2.0 + EDR), with a short range of 10 meters (class 2). In this work, we explore the idea of using this coexistence of high-power/high-bandwidth WLAN and low-power/low-bandwidth Bluetooth in a single mobile platform to solve the power consumption problem in WLAN-based communication systems. Several previous works have exploited Bluetooth as a secondary radio to reduce the overall power consumption. Unlike previous approaches, our work is based on clustering. In our work, a cluster is a Bluetooth Personal Area Network (PAN), which consists of one cluster head and several regular nodes. The cluster head acts as a gateway between the PAN and the WLAN, enabling the regular nodes to access the WLAN infrastructure via low-power Bluetooth. One unique requirement of our clustering problem is that, unlike sensor nodes which are left unattended after deployment, mobile devices (e.g., smartphones) are arbitrarily controlled by their users. This necessitates the consideration of node mobility as well as a large variance of bandwidth requirements of various applications. Moreover, because all devices have equal significance, rotating the CH role among all devices is necessary to distribute energy consumption. Mobi...