e carrier to the cus- tomer) and another band is used for the uplink (transmissions from the subscriber to the cell site). When carriers that use FD-LTE acquire new spectrum, they obtain one Fourth-Generation Advanced Mobile Services band specified by the government for uplink service and a different band specified for downlink service. By contrast, TD-LTE uses the same frequencies for uplink and downlink trans- missions. TD-LTE does not require paired spectrum, and unlike FD-LTE, it is asym- metric. A different amount of spectrum can be used in the downlink and in the uplink. For example, more spectrum can be allocated to the downlink than the uplink. China Mobile, the largest mobile carrier in the world, uses TD-LTE and some carriers in the rest of Asia are following suit and have announced plans to implement TD-LTE. The potential purchasing power of China Mobile makes it likely that manufacturers will supply a sufficient variety of TD-LTE-compatible handsets. Most of the rest of the world, including China Telecom, AT&T Mobility, and Verizon Wireless, are imple- menting or testing FD-LTE. Chinese companies manufacture and develop TD-LTE equipment. Core networks are the same for both types of LTE. The network core consists of portions of the network where traffic from multiple base stations (cell sites) is aggre- gated and transmitted to either a mobile central office or the Internet. Chip designers are integrating both TD and FDD into their platforms SO that carriers are able to support both types of LTE. Carriers able to support FDD and TD-LTE will be able to utilize spectrum suitable for either and support roaming for users with both types of handsets. 4G Multiple-Input Multiple-Output Antennas LTE, HSPA+, and WiMAX use Multiple-Input Multiple-Output (MIMO) base sta- tions. Equipment with MIMO antennas benefit by having more than one antenna and multiple input/output channels. Thus, they can carry the number of separate streams of voice or data as they have input/output channels. Each stream of traffic is car