Week 2 Ilab

Week 1 iLab Report

Carol Jones

DeVry University

NETW360: Wireless Technologies and Services

OPNET Preparation and Spread Spectrum Transmission Comparison

Submitted to:

Professor: Raef Yassin

Date: 10 March 2013

OPNET Preparation

OPNET Preparation

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Spread Spectrum Transmission Comparison

Introduction to Spread Spectrum Transmission

Guidelines

* What is it? It is a RF transmission technique that takes a narrow band signal and spreads it over a broader portion of the radio frequency band

* Why is it important? Low probability of detection, interception or determination of the transmitter's location. To an observer who does not possess information about the carrier, the transmission is indistinguishable from other sources of noise.

* What issues are addressed?

* How does it work? Input is fed into a channel encoder that produces an analog signal with a narrow bandwidth around a center frequency. This signal is further modulated using a sequence of digits known as a spreading code or spreading sequence. On the receiving end, the same digit sequence is used to demodulate the spread spectrum signal. And then, the signal is fed into a channel decoder to recover the data

Frequency Hopping Spread Spectrum (FHSS)

Guidelines

* What is it? Frequency hopping uses a range of frequencies that change during the transmission.

* How does it work? It keeps moving, making it hard for any kind of interference to hit it.

* What issues are addressed?

* Why is it important? Its important when flying RC models, and there are only 2 systems available in 2.4 ghz.

Direct Sequence Spread Spectrum (DSSS)

Guidelines

* What is it? It’s a modulation technique. It uses a signal structure in which the sequence of chips produced by the transmitter is already known by the receiver.

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