Netw360 Lab1

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  • Topic: Direct-sequence spread spectrum, Modulation, Frequency-hopping spread spectrum
  • Pages : 5 (1283 words )
  • Download(s) : 185
  • Published : March 17, 2013
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iLab Grading Rubric
Category| Points| Description|
Screenshot of OPNET properly prepared (25 points)D-number displayedCorrect project highlightedCorrect number of files displayedCorrect project files listed | 10555| Using the example provided, capture a screenshot of your OPNET files using Windows Explorer on Citrix.Requirements: Must clearly show D-number, project, total files in directory, and a listing of the project files.| Spread Spectrum Comparison (45 points)IntroductionFHSSDSSSComparison TableConclusion| 101010510| Using your textbook and web research, in your own words, summarize what you have learned about LAN modeling using OPNET ITGuru. Requirements: Minimum one paragraph per section; best practice is two or more paragraphs per section.| Total| 70| A quality paper will meet or exceed all of the above requirements.|

IMPORTANT: A report template is provided beginning on the next page, and you must use it to submit your assignment. Before submitting your assignment, delete the pages containing the instruction and rubric. Your submitted assignment should begin with the Title Page and only contain your report. Don’t forget to place your name, your professor’s name, and the date on the Title Page.

Week 1 iLab Report
Ahmed ELSeewy
DeVry University
NETW360: Wireless Technologies and Services

OPNET Preparation and Spread Spectrum Transmission Comparison

Submitted to:
Professor: Daniel Dronsick
Date: 03/10/2013

OPNET Preparation
OPNET Preparation
Paste your Windows Explorer screenshot that shows your Citrix NETW360 directory structure here. An example screenshot appears in your Week 1 iLab tab.

Spread Spectrum Transmission Comparison
Introduction to Spread Spectrum Transmission
* What is it?
ANS: Spread spectrum is a technique that takes a narrow, weaker signal and spreads it over a broader portion of the radio frequency band noise and ignore it (Ciampa 116). * Why is it important?

ANS: It is important because it is more resistant to outside interference, so it helps keep the traffic moving. It doesn’t interfere with other spread spectrum signals. Requires less power, It is transmitted beneath the noise level. More information can be transmitted, Increased security and resistance to multipath distortion.

* What issues are addressed?
ANS: It addressed security, continuous of transmission of data , not interfering with other radio signal transmission, and requires less power to operate.

* How does it work?
ANS: It uses two methods to spread the signal over a wider area: Frequency hopping spectrum, and Direct sequence spread spectrum. You simply multiply the received wideband signal by the same code again.

Frequency Hopping Spread Spectrum (FHSS)
* What is it?
ANS: A modulation technique that uses a range of frequencies that change during the transmission. (Ciampa 483)

* How does it work?
ANS: The original narrow band signal with bandwidth B, will be transmitted, at any one time, in one of 2N adjacent bands of bandwidth B. The duration of a chip (chip time) is the length of time the signal will stay in a particular band. The particular band in which the signal is sent during any particular chip time is determined using a pseudorandom sequence of numbers. For 2N adjacent bands N bits of the pseudorandom sequence are used to determine which band is to be chosen. At the beginning of each chip time the next N bits of the pseudorandom sequence are used to determine the band in which the signal will be transmitted during that chip time. In this way the signal appears to be randomly hopping between bands. However, since the hopping is based on a pseudorandom sequence it is possible to generate the same sequence of pseudorandom numbers at both the source and the receiver. Therefore, the receiver can predict which frequency band the next chip of signal will arrive in. The receiver can easily dehop and decode...
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