Exam 10: Cellular Wireless Networks

The dominant technology for third generation systems is ________.

The efforts to compensate for the errors and distortions introduced by multipath fading fall into three general categories: forward error correction,diversity techniques,and ________.

A technique in widespread use in second generation cellular networks is ________.

The key technology for 4G systems is ________.

Each base station is connected to a ________,which serves multiple base stations.

Since the early 1980s the most common first-generation system in North America has been the ________ developed by AT&T.

An important design goal for all three generation systems is to limit channel usage to 5 MHz.

In a multipath environment,if the multiple versions of a signal arrive more than one chip interval apart from each other,the receiver can recover the signal by correlating the chip sequence with the dominant incoming signal.The remaining signals are treated as noise.However,even better performance can be achieved if the receiver attempts to recover the signals from multiple paths and then combine them with suitable delays.This principle is used in the ________ receiver.

A major technical problem for cellular networks is fading.

One unwanted effect of multipath propagation is that multiple copies of a signal may arrive at different phases.

________ can be applied to transmissions that carry analog information or digital information and is used to combat intersymbol interference.

________ are useful in city streets in congested areas,along highways,and inside large public buildings.

The term ________ refers to the provision of multiple fixed data rate logical channels to a given user,in which different data rates are provided on different logical channels.The traffic on each logical channel can be switched independently through the wireless and fixed networks to different destinations.

The most widely used second generation CDMA scheme is IS-95.

Each cell in a cellular network is allocated a band of frequencies and is served by a ________ consisting of transmitter,receiver and control unit.

The time variation of received signal power caused by changes in the transmission medium is referred to as ________,which is a major technical problem for cellular networks.

A ________ is used to identify the user and register its location.

The ________ connects calls between mobile units,makes connections between a fixed subscriber to the public network and a mobile subscriber to the cellular network,assigns the voice channel to each call,performs handoffs,and monitors the call for billing information.

The area to be covered in a cellular network is divided into cells in a pentagonal tile pattern that provide full coverage of the area and equidistant antennas.

Scattering effects are difficult to predict.