Week 1 iLab Report

DeVry University
NETW360: Wireless Technologies and Services

OPNET Preparation and Spread Spectrum Transmission Comparison

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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
Guidelines
* What is it? Spread spectrum is the use of smaller transmissions over a broader range of radio frequencies. * Why is it important? Spread spectrum is important because it is resistant to outside interference and it is the primary alternative to narrowband transmission. * What issues are addressed? The issues addressed are the restriction of mulit-path distortion, lower power requirements, less interference on other systems, and increased security. * How does it work? Spread spectrum transmission works by sending out small transmissions over a broad radio frequencies by direct sequence spread spectrum, orthogonal frequency division multiplexing, and frequency hopping spread spectrum transmission.

Frequency Hopping Spread Spectrum (FHSS)
Guidelines
* What is it? Frequency Hopping Spread Spectrum uses bandwidths that change during the transmission. The closest thing I can think of that it could relate to is a military radio with a piece of equipment that changes the codes on a routine basis. * How does it work? This works by sending a transmission burst for 100ms then quickly changes frequency after its dwell time. * What issues are addressed? With FHSS we cover the peak transmit power of no more that 1W, that the hop channel separations are at least 25KHz, the hops are random, and the maximum dwell time is 400ms(or 30 seconds). * Why is it important? FHSS is important because it increases security and is hard to track from an outside source.

Direct Sequence Spread Spectrum (DSSS)
Guidelines
* What is it? Direct Sequence Spread Spectrum is the 2nd type of spread spectrum that breaks up the bits of transmissions to smaller bits that are transmitted. * How does it work? DSSS works by chipping the bits of data to smaller bits, then converts them by inversing the data and adding the original bit to the transmission. * What issues are addressed? The issues addressed with DSSS are that it has less interference on other systems, it is on a shared frequency bandwidth, and security is much better. You must have the original bit or key to decipher the transmission. * Why is it important? DSSS is important because you can use it to send secured information over a shared line if absolutely necessary. It also goes ignored because it acts like a low power noise on the net.
Comparison between FHSS and DSSS Technique | Advantages | Disadvantages | FHSS | Average dwell time on each frequencyUses a code with preset frequenciesRandom hops | The receiving station must know the code.Errors must be resentSpeed limitations set by FCC | DSSS | Error correctionLess interference on other systemsShared Frequency bandwidth.Better security | Without the cipher, DSSS is hard to translate.Maximum power is 1w.Less tolerant of signal interference. |

Guidelines * Summarize what was learned in a concise table format.
I learned that DSSS seems to be a much better route because it is far more secure and is more widely used over WLANS. FHSS is more complicated to use because you must preset all frequencies and the frequencies hop for security reasons. FHSS also does not have error recovery and you must resend the data lost during a transmission, DSSS does this for you.

Conclusion
Guidelines: Minimum one paragraph; best practice is two or more paragraphs * What did you learn? * How does it relate to this week’s TCOs and course material? * Why is it important? * How do you feel it will benefit you in your academic and professional career?
During week one I learned that radio frequencies are used in a variety of applications. I have learned that spread spectrum transmissions are employed to help ease the flow of the radio frequencies and are also used to encode certain information. This can help with security and allow for faster data transmission as well. Although we cover frequency hopping, it is not commonly used because direct sequence seems to work better. DSSS is more secure because it works by breaking up all bits into smaller bits. This can relate to the TCOs this week by allowing me to identify what type of spread spectrum would be better for different businesses.

I can use this knowledge to help my organization improve our network security because we do have smaller patrol stations around the county. Academically I can use this information to further improve my self –knowledge and attain more certifications. This will allow me to seek higher grades of employment within my organization.

References
Ciampa, Mark. CWNA Guide to Wireless LANs, 3rd Edition. Delmar, 6/19/12. VitalBook file.
IEEE 802.11 Direct Sequence Spread Spectrum (DSSS) | IEEE 802.11 Standard Overview | InformIT. (n.d.). Retrieved from http://www.informit.com/articles/article.aspx?p=19825&seqNum=5