Wireless networks in the form of ad hoc networks and sensor networks have gained lot of attention in recent years. The rapidly increasing capabilities and declining costs of computing and communication devices have made it possible to use wireless networks in a wide range of applications that can improve quality of life, and even save lives. One of the key challenges in the deployment of wireless networks is how to prolong the lifetime of the networks. In project “Energy Efficient Communication in Sensor Networks” (CCF 0329741), we proposed to study energy management techniques for wireless sensor networks. The key idea is that we take advantage of the physical layer design that facilitates the combining of partial information. A node can receive several partial signals and combine these signals to retrieve the complete signal. We refer to this as hitchhiking. Hitchhiking can potentially conserve energy for transmitting data in sensor networks. By the effective use of partial signals, a packet can be delivered with less nodes and/or less transmission power at each node. The focus was the physical layer design, including timing acquisition, preamble designing, and packet scheduling in interference limited environments. We propose here to study the use of the hitchhiking-based cooperative communication to support energyefficient design at upper layers. More specifically, we systematically study two types of power-efficient design using cooperative communication: power saving protocols and power control for transmission. A power saving protocol aims to put wireless nodes into periodical sleep state in order to reduce the power consumption in the idle listening mode. Power control for transmission manages energy consumption by adjusting transmission ranges. We plan to devise a new graph model that can capture the nature of cooperative communication. One key concept we introduce is the new notion of “path” on which other graph terminologies are defined. The power saving protocol is illustrated through the use of an extended notion of domination as a virtual backbone while power control for transmission is discussed through the topology control based on a new notion of “connectivity” under the cooperative communication. Out second thrust of research is to integrate some more recent wireless communication technologies, including directional antennas, to energy-efficient design which the proposed graph model is extended to a directed graph model. The goals of the proposed research are the following: (1) Systematic study of fundamental theoretical and algorithmic solutions using cooperative communication. (2) Propose a generic framework for energyefficient design at upper layers using cooperative communication. (3) Seamless integration of energy-efficient design and directional antennas. (4) Explore efficient and local sub-optimal solutions for various hard problems. (5) Integrate different components in energy-efficient design and fine tune the technique through an empirical study based on a set of well-defined quantitative performance metrics.
Intellectual Merits: The proposed framework is the first to systematically study the use of hitchhikingbased cooperative communication for energy-efficient design and to integrate such a design to various new wireless communication technologies. The central theme fits well to the object of SING program on fundamental theoretical and algorithmic studies involving coordination and communication. We believe that the proposed framework offers a very promising and unique combination of energy-saving models. In addition, the framework enriches the theory of energy-efficient design in wireless networks.
Broader Impact: We envision that the insights and results from this research will provide guidelines for energy-efficient for a wide range of wireless network applications. This research will also exploit and contribute to theoretical studies in topology control and virtual backbone. The results obtained from this project are believed to be useful in various applications of wireless networks, including mobile ad hoc networks and wireless sensor networks. We believe that the proposed study will contribute to make these networks more practical.