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The National Science Foundation has awarded Wilmot Assistant Professor Azadeh Vosoughi a grant for her project, Cooperative Sensing and Communications for Cognitive Radio Networks. As Principal Investigator, Vosoughi is collaborating with Assistant Professor Nazanin Rahnavard of Oklahoma State University. The total project budget is close to half a million dollars and spans three years.

Cognitive radio network (CRN) technology is an emerging field that addresses our depletion of frequency bandwidths. Vosoughi maintains that spectrum scarcity is largely due to the inefficient use of the spectrum rather than the shortage of the spectrum. In fact, she says, CRN technology enables unlicensed users to dynamically access the white spaces in licensed frequency bands without causing harmful interference to licensed users.

Central to the success of CRN is reliable spectrum sensing. The key to smooth operation may lie with a new system design that allows unlicensed users to cooperate and reliably sense the spectrum. In this design, each unlicensed user decides whether licensed users are accessing the spectrum and then transmits this information to central decision-making logic. The central logic fuses the local decisions and forms a reliable global decision, controlling the access of unlicensed users to the spectrum.

"Current cooperative spectrum sensing schemes," says Vosoughi, "are developed based on the assumption that local decisions are available error-free at the central logic for fusion and inference. While this approach simplifies the system design, it is susceptible to significant performance loss in spectrum sensing. Integrated design of signal processing and communication for data fusion and inference can capture the deteriorating effect of wireless channels between unlicensed users and the central logic." Vosoughi also proposes a semi-distributed decision architecture, which combines existing centralized and decentralized decision systems, and provides performance and complexity gains over the two systems.

As a theorist, Assistant Professor Vosoughi uses detection and estimation theory to design optimal distributed detection and fusion rules that maximize the reliability of spectrum sensing. Her mathematical framework is not tied to CRNs and can be extended to wireless sensor networks that are tasked with a wide range of applications, including battlefield surveillance, health care monitoring, environmental monitoring, electric transmission line monitoring, and underwater acoustic communications. The common theme in these applications is that the central logic is expected to provide a reliable global decision by fusing a collection of unreliable local decisions transmitted over unreliable channels. Her collaborator, Nazanin Rahnavard, is also a theorist who specializes in cooperative wireless communication protocols for cognitive radio.

Vosoughi's general interest lies in the broad area of signal processing for wireless communications. Since coming to the University of Rochester, she has focused mainly on distributed signal processing for wireless networks. Using communication theory, detection and estimation theory, and information theory, she explores distributed signal processing techniques that enable reliable and efficient transmission over unreliable channels. With several projects underway, Vosoughi currently works with three graduate students: Yupeng Jia, Hamidreza Ahmadi (3rd year PhD) and Nahal Maleki (1rst year PhD). Yupeng is working on cooperative wireless communications. Hamid and Nahal will be involved in various parts of the new project.

Vosoughi received her PhD in Electrical and Computer Engineering from Cornell University in May 2006. She received the Furth award from the University of Rochester in 2006 and is currently serving a two-year term as Wilmot Assistant Professor.