Exam 10: Cellular Wireless Networks

As the mobile user covers distances well in excess of a wavelength,the urban environment changes as the user passes buildings of different heights,vacant lots, and intersections.Over these longer distances,there is a change in the average received power level about which the rapid fluctuations occur.This is referred to as ________.

In a mobile environment one of the two antennas is moving relative to the other,therefore the relative location of various obstacles moves also,so as not to hinder transmission.

First generation cellular networks ________.

A cellular network uses multiple low power ________.

The number of cells in a repetitious pattern,(each cell in the pattern uses a unique band of frequencies),is termed the ________.

Affecting not only mobile phones in automobiles,but even a mobile phone user walking down an urban street,________ occurs when there are rapid variations in signal strength.

________ occurs when an electromagnetic signal encounters a surface that is large relative to the wavelength of the signal.

The objective of the ________ of wireless communication is to provide fairly high speed wireless communications to support multimedia,data,and video,in addition to voice.

Second generation cellular networks were analog.

Nonselective,or ________,is the type of fading in which all frequency components of the received signal fluctuate in the same proportions simultaneously.

Only one mobile user unit may be active and communicating with the base station at a time.

All first and second generation cellular networks provide encryption.

If there is no clear line-of-sight to the transmitter,such as in an urban area at street level,then diffraction and ________ are the primary means of signal reception.

Cellular technology is the foundation of mobile wireless communications.

________ occurs at the edge of an impenetrable body that is large compared to the wavelength of the radio wave.When a radio wave encounters such an edge, waves propagate in different directions with the edge as the source.Thus,signals can be received even when there is no unobstructed line-of-sight from the transmitter.

Even though cells are sufficiently distant from each other,they still need to be assigned different frequencies to avoid interference or crosstalk.

One of the most widely used models to develop guidelines for cell size was developed by ________.

Second generation systems provide multiple channels per cell,but each channel is dynamically shared by a number of users using time division multiple access or ________.

Third generation wireless communication supports ________.

A wireless cellular system limits the opportunity to use the same frequency for different communications because the signals can interfere with one another even if geographically separated.