olved NodeB (eNodeB). The eNodeB allocates radio frequency (wireless spectrum) to users' devices and passes calls off to other cell sites and to the mobile carrier's core IP network. Importantly, the eNodeB manages Multiple-Input Multiple-Output (MIMO) antenna functions and Orthogonal Frequency-Division Multiplexing (OFDM) signaling. See the section "The LTE Orthogonal Frequency-Division Multiplexing Air Interface" later in this chapter. Coaxial cabling connects the eNodeB to the cell site's antenna. The eNodeB contains a blade with a software- defined radio containing the air interfaces tuned to the applicable spectrum. A blade is a densely packed, horizontally placed circuit board with many ports. The modem in the software-defined radio translates radio frequency signals into those compatible with landline networks, and vice versa for outgoing traffic. The eNodeB is also referred to as the base station. Together with the antennas, amplifiers, and spectrum, it is used to access the mobile network. In combination, this equipment and spectrum make up the Radio Access Network (RAN). The eNodeB manages the RAN. www.TechnicalPDF.com LTE architecture is streamlined in terms of the amount of equipment and protocols required compared to earlier generations of mobile networks. Figure 7-4 presents a diagram of LTE architecture. This streamlining and distribution of functions at fewer servers results in data stream transmissions that use fewer protocols and equipment hops. This decreases latency (delays). The LTE evolved packet core data center supports multiple antennas and controllers Broadband Network Internet Signals Voice & data traffic Packet Gateway HSS-Home subscriber server Roaming & subscriber databases MME*** www.TechnicalPDF.com : Serving Gateway transmits *PGW: Converts wire signals to landline signals Mobility Management Entir LTE chips transmits device Takes signals off and on Figure 7-4 Fourth-generation (4G) Long-Term Evolution (LTE) architecture in the Radio Access Network (RAN) and the evolved packet cor