Why Telephone Channels Have A Band Width Of About 3.1khz

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Lienphuong Nguyen Professor: Laura Ingraham Dec 6, 2014 Assignment 2 (Chap 6, Thought Question #2) Telephone channels have a band-width of about 3.1kHz Television Channel 's signal-to-noise ratio is 1000 The signal strength is 1000 times larger than the noise strengths. Telephone modems operate at about 30kbps. C= B[log2 (1 + S/N)] a) B 3.1 (kHz) S/N 1000 log2 (1 + S/N) 9.97 C 30.90 (kbps) b) B 3.1 (kHz) S/N 10000 log2 (1 + S/N) 13.29 C 41.19 (kbps) c) B 4 (kHz) S/N 1000 log2 (1 + S/N) 9.97 C 39.87 (kbps) d) We can increase the Maximum possible speed by increasing Signal-to-noise ratio or increasing channel’s bandwidth. However, increasing the channel’s band-width is more efficient in…show more content…
Finally “Rogue Access Points” are the access points which are set up by a department or an individual for some reasons. These Rogue access points are unsecured, so the “drive-by-hacker” can have an entry points to the network. This is really dangerous because only one Rogue access point can make the network in threat of hacker although you protect all of your official access point very well. Although there are many threat of WLAN, you still can reduce those threats by applying some technology in your network. For example, you can use a Core Security Standard. It provides protection, which are confidentiality, authentication and message integrity, between the wireless access point and the wireless host. Furthermore, you also can use Wired equivalent privacy (WEP) security. In WEP, everyone shares the same access point, which requires the same key, and WEP’s key is not automated mechanism for changing. On the other hand, Wireless Protected Access (WPA) is also an option for you. WPA is developed by using the concept of Core security standard, so it could be used on older wireless access points and it is stronger than WEP. Finally, 802.11i is another solution for your concerns about the network security. 802.11i is considered as WAP2, and it uses extremely strong AES-CCMP encryption, which has 129-bits keys and a key management method for automatically changing keys. That’s all about the

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