Devry Network 360 Wk 1 Ilab Essay

453 WordsFeb 2, 20142 Pages
OPNET Preparation 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 transmission is the process of spreading a signal across a certain frequency domain, giving the signal more bandwidth. This technique is important since it addresses concerns of security, jamming, noise, and natural interference. It also has a lower power requirement and is able to transmit more information than narrowband transmission. Spread spectrum transmission is accomplished by a modulation technique known as frequency hopping (FHSS). Frequency Hopping Spread Spectrum (FHSS) * What is it? How does it work? What issues are addressed? Why is it important? FHSS is when a signal is transmitted across several channels. This is done by sending short burst of the signal across many bandwidths until the entire message has been transmitted. FHSS is important because it is resistant to deliberate jamming and eavesdropping. Direct Sequence Spread Spectrum (DSSS) * What is it? How does it work? What issues are addressed? Why is it important? DSSS converts each bit into a series of bits to be transmitted known as chipping or chipping code. This is accomplished by inserting extra bits into the actual signal bits. This process is accomplished by the Boolean operation of exclusive or (XOR) and is known as pseudorandom sequence. The signal being transmitted is at a higher frequency than the original signal. This new signal resembles “white noise”. It is recovered on the receiving end by the same pseudorandom sequence and is known as de-spreading. The importance of this type of transmission is that it is less susceptible to interference, and can recover scrambled transmissions using advanced statistical techniques eliminating the need to retransmit the

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