ers build these networks. When Verizon Wireless upgraded its backhaul network to fiber, it used the wholesale division of Verizon Communications to build it out. Verizon's wholesale division offers backhaul services on a wholesale basis to other providers in addition to Verizon Wireless. Cable Multiple System Operators (MSOs), AT&T, and other long-haul network carriers also provide backhaul links to mobile carriers. The traffic is transported on the same fiber that transmits traffic from landline carriers. The Functions of Radios and Modems in Mobile Networks Every wireless device contains a radio. Radios in mobile networks extract radio frequency signals from the air and convert them into small bits of frequency compatible with the devices. The radios then hand off slices of bits of data to modems within devices. At the transmitting end, radios convert signals to the frequencies used in the cellular network, and then transmit these wireless signals over the air. At the receiving end, modems remove noise caused by interference and decode the radio frequency data signals into those compatible with the landline network. If the amount of noise is SO great that the signal can't be decoded, the modem requests that the base station retransmit the signals. Removing the noise from signals is the most complex function in modems. At the www.TechnicalPDF.com transmitting end, modems encode (modulate) the signals to make them compatible with the radio frequency wireless network. Modems also add encryption at the transmission end for protection from eavesdroppers. Elements of LTE Infrastructure LTE has a simplified infrastructure and cell sites with fewer pieces of equipment to manage than early generations of mobile protocols. Moreover, LTE software and hardware can be installed on standard computer platforms SO that carriers can choose from a wide range of equipment manufacturers. LTE cell sites also support more users per cell site than 3G technologies because the air interface is more flexible and uses spectrum more effic