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Home Events Events Archive 2014 Cognitive Access Policies under a Primary ARQ process via Forward-Backward Interference Cancellation

Cognitive Access Policies under a Primary ARQ process via Forward-Backward Interference Cancellation

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  • Visitor Seminars
When Nov 22, 2013
from 10:00 AM to 11:30 AM
Where Engr. IV Bldg., Tesla Room 53-125
Contact Name
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Michele Zorzi 

University of Padova



This paper introduces a novel technique for access by a cognitive Secondary User (SU) using best-effort transmission to a spectrum with an incumbent Primary User (PU), which uses Type-I Hybrid ARQ. The technique leverages the primary ARQ protocol to perform Interference Cancellation (IC) at the SU receiver (SUrx). Two IC mechanisms that work in concert are introduced: Forward IC, where SUrx, after decoding the PU message, cancels its interference in the (possible) following PU retransmissions of the same message, to improve the SU throughput; Backward IC, where SUrx performs IC on previous SU transmissions whose decoding failed due to severe PU interference. Secondary access policies are designed that determine the secondary access probability in each state of the network so as to maximize the average long-term SU throughput by opportunistically leveraging IC, while causing bounded average long-term PU throughput degradation and SU power expenditure. It is proved that the optimal policy prescribes that the SU prioritizes its access in the states where SUrx knows the PU message, thus enabling IC. An algorithm is provided to optimally allocate additional secondary access opportunities in the states where the PU message is unknown. Numerical results are shown to assess the throughput gain provided by the proposed techniques.


Michele Zorzi is a Professor at the Department of Information Engineering of the University of Padova. Prior to his current appointment, he was employed at the Politecnico di Milano, the University of Ferrara and the University of California at San Diego, with which he still has an active collaboration. He received a PhD in Electrical Engineering from the University of Padova in 1994. Michele was the EiC of the IEEE Wireless Communications magazine in 2003-2005, and the EiC of the IEEE Transactions on Communications in 2008-2011, and has served on the Editorial Boards of the top journals in his area of research and on the Organizing and Technical Program Committee for many international conferenced. He is an IEEE Fellow. His main research interests are in the area of wireless communications and networking, sensor networks and IoT, underwater communications and networks, cognitive networking, and energy-efficient protocol design. His work is widely cited, with a total of more than 11000 citations and an h-index of 52.

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