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SUMMARY:Next Generation Dynamic Spectrum Networks - Heather Zheng\,  Compu
 ter Science Dept\, University of California\, Santa Barbara
DTSTART:20070802T153000Z
DTEND:20070802T163000Z
UID:TALK7757@talks.cam.ac.uk
CONTACT:Wenjun Hu
DESCRIPTION:Today’s static spectrum assignment policy has led to a criti
 cal spectrum shortage. While innovative wireless networks such as WiMAX ar
 e denied from spectrum access\, the majority of existing networks use only
  10-15% of their assigned spectrum. To reuse “wasted” spectrum\, the r
 ecent proposal on dynamic spectrum access allows unlicensed (secondary) us
 ers to sense\nthe presence of legacy licensed spectrum holders (primary us
 ers such as TV broadcasts) and opportunistically utilize unused licensed s
 pectrum on a non-interfering basis. This “creates” new capacity and co
 mmercial value from existing under-utilized spectrum.\n\nWhile it shows gr
 eat promise\, the technology nderlying dynamic spectrum systems is still i
 n its infancy. Issues in wireless communications and networking\, once add
 ressed in the context of fixed spectrum assignment\,\noffer new research c
 hallenges in the realm of dynamic spectrum systems. In this talk\, we desc
 ribe some initial studies on dynamic spectrum systems.\nWe begin by descri
 bing spectrum heterogeneity\, a result of the dual-user nature of these sy
 stems that drastically complicates spectrum management. We then present th
 ree algorithms for secondary users to access spectrum fairly and efficient
 ly. Specifically\, we introduce (1) a centralized graph coloring approach 
 that optimizes spectrum allocation for a static\ntopology\, (2) a distribu
 ted coordination approach where devices use local bargaining to adapt spec
 trum assignment over topology variations\, and (3) a light-weight rule-bas
 ed distributed solution that requires minimum coordination.  We conclude b
 y summarizing this work in context\, and discussing current and future dir
 ections in combining these results with higher layer mechanisms to produce
  an end-to-end programmable and adaptive network.\n\nSpeaker Bio:\nSince A
 ugust 2005\, Heather Zheng has been an assistant professor at Department o
 f Computer Science\, University of California\, Santa Barbara. Her researc
 h area includes wireless networking and communications\, and multimedia co
 mputing. She currently focuses on Cognitive Radios and dynamic spectrum ne
 tworks. Her research on Cognitive Radios was selected as one of the 10 Eme
 rging Technologies of 2006 by MIT Technology Review Magazine\, and the Bes
 t Student Paper in IEEE DySPAN 2007. Dr. Zheng was named as the MIT Techno
 logy Review’s Top 35 Innovators under the age of 35 in 2005. She also re
 ceived 2006 World Technology Award (top 5 in communication)\, 2002 Bell-La
 bs President’s Gold Award\, 1998-99 George Harhalakis Outstanding Gradua
 te Student Award from University of Maryland\,\nCollege Park. Dr. Zheng re
 ceived her Ph.D. from University of Maryland\, College Park in 1999 and th
 en joined wireless research lab\, Bell-Labs\, Lucent Technologies. She the
 n moved to Microsoft Research Asia as a project lead and researcher in Mar
 ch 2004 and later joined UCSB.
LOCATION:Lecture Theatre 2\, Computer Laboratory\, William Gates Builiding
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