Professor Yonghe Liu

Dept. of Computer Science and Engineering
The Univeristy of Texas at Arlington

tel: (817)2727606


Our research covers wireless networking in general and wireless sensor networks in particular. Below is a list of projects we are performing


(Supported by the National Science Foundation: CNS-0721951)

Wireless sensor networks have revealed vast potential in providing accurate and cost-effective monitoring for a plethora of applications. In stark contrast with traditional data forwarding networks exemplified by the Internet, wireless sensor networks are uniquely characterized by drastically low data rate, often at several bytes per minute, owing to application specific requirements. Despite numerous groundbreaking work in this field, the underlying communication techniques, particularly at the physical and link layers, are still largely germinating along the Internet root and its wireless extensions. Moreover, energy efficiency has overwhelmingly relied on coordinated sleep/wakeup schemes, where communications are synchronized into a short time window. Inevitably this will augment the collision probability and irrelevant packet listening, the two dominant power consumption components in wireless networks. Motivated by recent advancements in semi-passive RFID technology, this project will develop an innovative asynchronous communication architecture, in which a sensor node is allowed to directly write data into a special, reactive module (RFID tag based) residing on the receiving node while its main platform (the central controller) is asleep. Owing to the low duty cycle of a sensor node, the proposed asynchronous architecture will liberate the network from collisions and idle listening by fully exploiting time as one dimension of resource (no conventional MAC needed) and hence achieve high energy efficiency. Furthermore, with this fundamentally new paradigm for communication in energy-constrained systems, this project will also study the overlaying computation paradigm, including sampling, in-network processing, and routing, in order to accommodate, fully unleash, and demonstrate its enormous impact.

DoC - Distributed Opportunistic Computing

(Supported by the National Science Foundation: CNS-0834493. Prof. Mohan Kumar is leading this project.)

The objective of this project is to carry out preliminary, fundamental research work in the area of opportunistic computing. When pairs of devices come within each others? communication range, opportunistically, short-lived links (or opportunistic links) are created. Opportunistic computing exploits the opportunistic links created by pair-wise contacts, to share information content, resources and services, leading to a wide variety of applications. Groups of computing nodes and their associated pair-wise contacts in an opportunistic network give rise to a distributed opportunistic computing system. Essentially, opportunistic computing can be described as distributed computing with the caveats of intermittent connectivity and delay tolerance. The novelty of the proposed work lies in the exploitation of opportunistic communication contacts to provide collaborative computing services to applications and users. The unique contributions of this project include the development of an adaptive protocol for opportunistic communication in support of computing, a middleware architecture for masking the disruptive nature of the underlying network from applications and users, and a mechanism for delay tolerant, remote execution of tasks.

CoVo: Collaborative Virtual Observation in Dynamic Environments

(Supported by the National Science Foundation: ECCS-0824120. Prof. Mohan Kumar is leading this project.)

The objective of this project is to develop a framework for anytime, anywhere collaborative virtual observation of events occurring in dynamic environments. The approach is to enhance recently developed virtual observation concepts by adapting software service composition mechanisms developed for pervasive computing systems. The observations, made at different points in time and space, are stitched together based on location, query, device, and other variables. Protocols for soft-real time delivery of data packets in heterogeneous networks comprising a combination of continuous and disruption tolerant communication channels are being developed. Middleware tools are being created to perform reactive and proactive query processing, matching, and synthesis of integrative panoramic views. The intellectual merit of the proposed work lies in the launching of the virtual observers, in retrospect, in soft real-time, on any device in a mobile environment and the concatenation of successive virtual observers to create virtual tours. Development of an integrated framework for video acquisition, stream processing, video synthesis, opportunistic networking, and integrated pervasive services in dynamic and heterogeneous environments are contributions of this project.

Defending Against Compromised Nodes in Wireless Sensor Networks: A Multi-Layer Security Framework

(Supported by Texas Advanced Research Program, ARP 2006)

In this project, we propose an integrated framework to dynamically manage deployed WSNs in a predictable, dependable and timely manner, with a goal to defend internal or external attacks in hostile and unattended environments. In particular, we propose to develop powerful and yet tractable design principles for high information assurance based on rich theoretical concepts like secret key sharing, epidemic theory, belief and trust modeling, information theory and game theory. By combining advanced mathematical tools with efficient cryptographic techniques, our framework will not only be capable of defending against simple attacks such as packet dropping, eavesdropping, and replaying, but also be capable of identifying, isolating, revoking entirely compromised nodes and purging corresponding tampered data. Our fundamental research will be augmented with prototype sensor design, manufacturing, and system integration.

Resource Allocation in Delay Tolerant Networks

(Supported by Research Gift from Cerion Networks)

delay tolerant networks, custody transfer can provide certain degree of reliability as a custodian node cannot discard a message unless its life time expires or the custody is transferred to another node after a commitment. We are intevestigating resource allocation strategies for a node to decide when a custody should be accepted.

Green Roof Monitoring

We have established a sensor network monitoring the green roof on the UT-Arlington campus. The network will allow researchers to measure and study the correlation of the sunlight, soil moisture (rainfall/irrigation) and soil temperature to plant growth.