Week 1 iLab Report
NETW360: Wireless Technologies and Services
OPNET Preparation and Spread Spectrum Transmission Comparison
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Spread Spectrum Transmission Comparison
Introduction to Spread Spectrum Transmission
What is it? Why is it important? What issues are addressed? How does it work?
Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is deliberately varied. This technique takes a narrow, weaker signal and spreads it over a broader portion of the radio frequency band. This result in a much greater bandwidth than the signal would have if its frequency were not varied.
There are at least two problems with conventional wireless communications that can occur under certain circumstances. First, a signal whose frequency is constant is subject to catastrophic interference, which occurs when another signal is transmitted on, or very near, the frequency of the desired signal. Second, a constant-frequency signal is easy to intercept, and is therefore not well suited to applications in which information must be kept confidential.
The benefits of spread-spectrum technology address the common conventional wireless communication problems. Resistance to interference is the most important advantage. Intentional or unintentional interference and jamming signals are rejected because they do not contain the spread-spectrum key. Resistance to interception is the second advantage provided by spread-spectrum techniques. Because non-authorized listeners do not have the key used to spread the original signal, those listeners cannot decode it. Without the right key, the spread-spectrum signal appears as noise or as an interferer. Resistance to fading is another benefit to...