Energy detectionfor Cognitive Radio

A discussion on channel sensing techniques

By James Xu

Presentation overview

Introduction to wireless communications What is Cognitive Radio (CR)? Why do we need CR? What is energy detection Our workbench Standard energy detector Problem with the detector Our improved detection model

Wireless communications

What is Cognitive Radio (CR) Able to sense spectral environment Able to provide opportunistic access

Find gaps in the spectrumAdjust system parameters to utilize it

Why do we need CR?

Unlicensed spectrum is scarce Almost none available under 3GHz

Why do we need CR? Licensed to primary user only (Incumbent) We are running out of space, and higher frequency

has problems We are under utilizing licensed space

CR is allowed usage (guarantee interference free)

Energy detection

The first step in CR is to identify free spectrum

Energy detection is being used

What is energy detection? All radio transmission have energy

Based on hypothesis testing

Our CR workbench

Energy detector

Energy detector

Problems with the detector Misdetection on Narrowband signals

Problems with the detector Misdetection on partial signals

Adaptive energy detection We proposed an

improvement Introduced adaptive

detection

Improved detection

Adaptive ED characteristics

Adaptive ED characteristics

Thank you for listening

Any questions?