The broadband spectrum, which serves all our wireless needs, is subdivided into many sections based on frequencies allocated for different purposes. That is why carriers in the US are constantly competing for bandwidth space, because T-Mobile owns a different section of the spectrum from, say, Verizon. Often, these carriers don’t own a large continuous chunk of spectrum, rather, slivers distributed throughout the entire length.
After Verizon began deploying LTE technology for its 4G network, LTE rose to the top of its league. The next generation of LTE, named LTE Advanced, will provide higher capacity for large data transfers such as video streaming through a clever technology known as carrier aggregation. This technology takes pieces of the spectrum that were previously scattered around and combines it into a single broad channel. Even spectrum of different types can be mixed and matched.
This means the maximum amount of spectrum that LTE can operate in will be pushed from 20 MHz to 100 MHz, translating to theoretical download speeds as high as 1 Gbps.
T-Mobile USA had announced last week that it is deploying an iteration of this technology in the dual-carrier HSPA+ technology. This move doubles the speed of its 3G network from 21 Mbps to 42 Mbps by combining two HSPA+ downlink carriers. Nokia Siemens Networks used carrier aggregation technology earlier this year when it combined an 800 MHz and a 2.6 GHz spectrum, two bands that Europe is going to use for 4G technologies. Nokia used the same base station with two radios tuned to the two different spectrum bands.
LTE Advanced with carrier aggregation would result in a more reliable LTE service with higher transfer speeds for larger chunks of data, and eventually, movement of voice service into LTE. AT&T and Verizon Wireless could be expected to move all users into the 700 MHz band for LTE in the future.