Question and Answers

500,0000x 25000=1000,000

3)

4)

5) Error detection is the detection of errors caused by noise or other impairments

During transmission from the transmitter to the receiver. Summer is another

Name for error detection.

The receiver can detect a change in the original code word.

• 1. The receiver has (or can find) a list of valid code words.

• 2. The original code word has changed to an invalid one.

PROCESS OF ERROR DETECTION

6)

Message = 10111100, Pattern = 11011

Frame check sequence =000111

7) Input: 1011, Locally Generated PN bit stream: 101011011010, T = 3Tc

(101011011010-1011)3

101011011111x3=30303303333

8) Ad hoc mode:

An Ad-hoc network allows each device to communicate directly with each other. There is no central Access Point controlling device communication. Ad-hoc networks are only able to communicate with other Ad-hoc devices, they are not able to communicate with any Infrastructure devices or any other devices connected to a wired network. In addition, Ad-hoc mode security is less sophisticated compared to an Infrastructure mode network.

Infrastructure mode:

An Infrastructure mode network requires the use of an Access Point. The Access Point controls Wireless communication and offers several important advantages over an Ad-hoc network. For example, a Infrastructure based network supports increased levels of security, potentially faster data transmission speeds and integration with a wired network.

9) Considering the meanings of the two reference models, the OSI model is just a conceptual model. It is mainly used for describing, discussing, and understanding individual network functions. However, TCP/IP is firstly designed to solve a specific set of problems, not to function as a generation description for all network communications as OSI model. OSI model is generic, protocol independent, yet most protocols and systems adhere to it, while TCP/IP model is based on standard protocols which the Internet has developed. Another thing should be noted in OSI model is that not all layers are used in simpler applications. While the layers 1, 2, 3 are mandatory for any data communication, the application may use some unique interface layer to the application instead of the usual upper layers in the model.

10)

i) Hexagonal shapes are preferred than square or circle in cellular architecture because it covers an entire area without overlapping.

ii)The frequency reuse become possible using this shape. The radiation pattern of the antennas used is 60 degree which means 6 are required for the full 360 degrees coverage which is the same no. of sides the hexagon consists