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Introduction A cognitive radio (CR) is effectively a transceiver that implements
dynamic spectrum management (DSM) so that the network(s) operating on a
given bandwidth has both the greatest possible throughput as well as the best
link performance possible for its nodes by continually determining the best
means of transmission and/or reception at the moment. Software defined
radio (SDR) systems make the implementation of cognitive radios possible.
Cognitive Radio Cognitive radios are entirely aware of the RF environment in which
they operate including both channel conditions and link performance and
adapt to current conditions to ensure that a minimum quality of service is
met. Cognitive radios could potentially:
Use any current modulation system
Be updated easily to use any future modulation system
Serve as gateways between incompatible networks
Digital Radio Hardware Used
USRP N200 RFX1200 1.15-1.45 GHz
Rx/Tx Daughter Board
Software Defined Transceiver Overview
GNU Radio is a free open source software development toolkit that
includes both signal processing and runtime code blocks that are then used
to implement SDR systems with RF hardware and computers
Applications are Python scripts that tap into low level performance-
critical signal processing code blocks written in C++
Supports bpsk, apsk, gmsk, bpsk, psk, qam, and qpsk modulation as
well as ODFM
Used in academic, commercial, and hobbyist environments for both
research and real-word applications
ODFM Networks Orthogonal frequency-division multiplexing (ODFM), a wide band
communication scheme, uses a large number of closely spaced orthogonal
sub-carrier signals to encode data. Each of the orthogonal sub-carrier
frequencies is modulated at a low symbol rate and carries data that is then
further subdivided into several channels.
ODFM is advantageous for use in cognitive radios as it:
Eliminates cross-talk, intercarrier guardbands, intersymbol interference
Displays resilience in severe channel conditions
Achieves high spectral efficiency
Is compatible with many different modern modulation schemes
Has an efficient implementation using Fast Fourier Transform (FFT)
ODFM Example
Current Progress Signal level communications have been achieved. Multi-hop networking
is in progress. Packet level communications have not yet been achieved as
channel communication errors are encountered upon receiving packets.
Packets are currently able to be transmitted. The goal of this project was to
create a six node network that could route packets.
Six Node Network Goal
Cognitive Radio: Optimized Networking with Software Defined Radio Systems College of Science of Technology, Temple University
Andrew Daniels Mentor: Dr. Jie Wu
References
Gef. (2010, December 02). Home [Online] Available: http://www.cognitiveradio.wireless.vt.edu/dokuwiki/doku.php?id=home
J. P. Lang. (2012, June 28). GNU Radio [Online] Available: http://www.gnuradio.org
A. L. Intini. (2000, December 01). Orthogonal Frequency Division Multiplexing for Wireless Networks [Online] Available: http://www.create.ucsb.edu/ATON/01.01/OFDM.pdf