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