LONG TERM EVOLUTION
The first commercial Long Term Evolution (LTE) networks were deployed on a limited scale in Scandinavia at the end of 2009. Currently, 49 LTE operators have launched commercial services, while 285 operators have committed to commercial LTE network deployments or are engaged in trials, technology testing, or studies. Big operators include AT&T, Verizon Wireless, and China Mobile. In the United States, at the start of 2012, Verizon’s LTE network has rolled out 400 markets covering over 200 million points of presence (POPs). Currently, subscribers have 10 LTE devices to choose from, including three smartphones, two tablets, two hotspot devices, and three USB modems. Outside of the operator’s LTE footprint, customers automatically connect to the 3G network. AT&T has set up 72 markets with over 100 million POPs. Worldwide LTE deployments are detailed in .
Heterogeneous networks are expected to be an integral component of future LTE network deployments. The ability to coordinate and manage interference in networks is key to enabling additional gains in capacity and performance, which is needed to keep up with exponentially growing traffic demands. LTE is currently being deployed in the traditional macrocell network architecture. However, there is tremendous interest from cellular operators and vendors to include small, inexpensive, self-configurable base stations in that architecture. It is expected that a large number of these small cells will be multimode, ...