Signal Processing, Communications, and Networking

Georgios Giannakis
Ramesh Harjani
Tian He
Tom Luo
Andrew Odlyzko
Zhi-Li Zhang

Professor Georgios Giannakis

We are focused on Signal Processing (SP) research and development projects In Networking (N) and COMmunication (COM) systems. On par with the dramatic upswing in modern telecommunications and information technology worldwide, our SPINCOM team contributes enthusiastically its "basic research and education bits" towards realizing the dream of "communicating with anyone, anywhere, anytime."

Since 1994, the group has emphasized wireless, mobile telecommunications and networking research. Current topics include complex-field, space-time and network coding, multicarrier, cooperative wireless communications, cognitive radios, cross-layer designs, mobile ad hoc networks, and wireless sensor networks. Research funding comes from the National Science Foundation (NSF), the Army Research Office (ARO), the Army's Research Lab (ARL), and the Office of Naval Research (ONR); we are thankful to all our sponsors for their support through the years.

Historically, SPINCOM started with the SPIRIT group at the University of Virginia (1987–1998) that performed research in applications and algorithms for signal processing, estimation and detection theory, time-series analysis, and system identification. Specific subjects included (poly) spectral analysis, wavelets, cyclostationary, and non-Gaussian signal processing with applications to sonar, array, and image processing (SAR).

Current Research Thrusts:

Wireless Cooperative Communications

  • Link-Adaptive Relay Protocols
  • Multi-Source Cooperation and Network Coding
  • Cooperative Synchronization

Ultra-Wideband and Cognitive Radios

  • Synchronization and (De-)modulation
  • Dynamic Spectrum Management
  • Sensing and Scheduling

Cross-Layer Designs

  • Adaptive Modulation/Coding with ARQ and Queuing
  • Random Access with Decentralized Channel Information
  • Scheduling and QoS Support in Wireless Access

Wireless Sensor Networks

  • Decentralized Detection and Classification
  • Joint Compression-Estimation
  • Distributed Consensus-Based Estimation

Wireless Mobile Ad Hoc Networks

  • Fundamental Limits and Optimality
  • Stochastic Routing Protocols
  • Joint Contention and Congestion Control
  • Scheduling for Distributed Access

Professor Tian He

My research interests lie broadly in wireless and sensor networking, distributed systems and real-time computing. Currently, my research is focusing on Wireless Sensor Networks (WSNs), a new information paradigm based on the collaboration of a large number of self-organized sensing nodes. These networks form the basis for many promising applications such as immersive gaming, intelligent battlefields, hazard response systems, smart hospitals and cyber-physical systems. My research is mainly system-oriented - building practical systems. Specifically we are aiming at four major interleaved efforts: 1) Integrated sensor systems such as VigilNet , 2) sensor network service such as energy management, localization, networking, coverage and privacy issues, 3) in-situ empirical modeling and related protocol enhancement, and 4) architecture, system, language and development support for large-scale integrated sensor network systems. The ultimate research goal is to contribute to the design, implementation, deployment, use and maintenance of practical sensor systems.

Current Research Thrusts:

Minnesota Embedded Sensor System Group

APL - In road networks, sensor nodes are deployed sparsely (hundreds of meters apart) to save costs. This makes the existing localization solutions based on the ranging ineffective. To address this issue, we introduce an Autonomous Passive Localization (APL) scheme. Our work is inspired by the fact that vehicles move along routes with a known map. Using vehicle-detection timestamps, we can obtain distance estimates between any pair of sensors on roadways to construct a virtual graph composed of sensor identifications (i.e., vertices) and distance estimates (i.e., edges). The virtual graph is then matched with the topology of road map, in order to identify where sensors are located in roadways. We evaluate our design in local roadways and simulated environments, where we found no location matching error, even with a maximum sensor time synchronization error of 0.3sec and the vehicle speed deviation of 10km/h. This system has been reported in Infocom 2008.

Mirage is a large indoor sensor network test-bed, supporting up to 360 nodes. The whole test-bed is composed of six 4 feet by 8 feet boards. Each board in the system can be used as an individual sub-system, because each board is designed to be separately powered, separately controlled and separately metered. Each individual board can support up to 60 nodes, therefore, the whole system can support up to 360 nodes working simultaneously. In the first phase of construction, three high-end HIT HITCPX1250 projectors are used to generate event (it is capable to create mirage ). In the second phase of construction, motorize objects are introduced to create another sets of mobile targets. The ultimate goal of this testbed is to allow researchers to conduct all kinds of system research locally and remotely with realistic sensing modality as inputs. The first phase of construction is finished during 2007. In the second phase, mobility support will be added.

VigilNet is one of the major efforts in the sensor network community to build an integrated sensor network system for surveillance missions. The focus of this effort is to acquire and verify information about enemy capabilities and positions of hostile targets. Such missions often involve a high element of risk for human personnel and require a high degree of stealthiness. Hence, the ability to deploy unmanned surveillance missions, by using wireless sensor networks, is of great practical importance for the military. In this work, we design and implement a complete running system, called VigilNet, for energy-efficient surveillance. It currently consists about 40,000 lines of NesC and Java code, running on XSM, Mica2 and Mica2dot platforms. The complete system is designed to scale to at least 1000 XSM motes and cover minimal 100x1000 square meters to ensure operational applicability. We evaluate middleware and system performance extensively on a network of 203 MICA2 motes.

Professor Zhi-Li Zhang

Computer Networking and Multimedia Research Lab

We conduct research on a broad range of topics related to computer and communication networks, helping transform the current best-effort Internet to a more reliable, available and secure information infrastructure for all kinds of communication activities. Our research spans packet scheduling disciplines, (Quality of Service) routing, network resource management, network architecture design, network performance analysis, video streaming, collaborative systems, and more. In carrying out our research, we blend formal modeling/analysis, experimentation/implementation, and testing/evaluation.

Current Research Thrusts: