Carrier aggregation promises to open new possibilities to LTE network operators
The LTE-Advanced feature that enables users and operators to access bandwidth capacity from networks operating on different spectrum bands is known as carrier aggregation, and the impacts associated with the capability are intriguing, to say the least.
Traditionally, the only way for operators to provide mobile broadband wireless services is to have access to large swaths of contiguous spectrum in a single band, with the 20 MHz of paired 700 MHz spectrum licensed to Verizon Wireless being a prime example. Conversely, those without big chunks of contiguous spectrum certainly struggled to compete with the large carriers that had such spectral assets, and some simply could not offer broadband services to customers in a manner that would be profitable.
Through carrier aggregation, the game potentially changes. Instead of requiring lots of contiguous spectrum, LTE-Advanced with carrier aggregation lets an operator effectively combine the bandwidth throughputs from networks operating in multiple spectrum bands. In addition, where operators have had to choose between technologies operating on paired spectrum (FDD) and those operating on unpaired spectrum (TDD), carrier aggregation will enable an operator to leverage both kinds of solutions.
LTE manufacturer Huawei demonstrated carrier aggregation working across both FDD and TDD spectrum at the recent Mobile World Congress, promising peak throughputs of more than 500 MB/s, according to Steven Hartley, principal analyst at Ovum. This capability could mean that TDD spectrum, which traditionally has been less expensive than FDD spectrum, may be more appealing to network operators than it has been in the past, he said.
In the U.S., a potential beneficiary from this development would be Sprint, which has massive TDD spectral holdings in the 2.5 GHz band, as well as paired spectrum at 1.9 GHz, a contiguous swath at 800 MHz (thanks to rebanding) and could get some contiguous spectrum in the 900 MHz band, if a proposed repurposing of LMR airwaves becomes reality.
“That’s where I would probably expect an aggressive deployment of this technology to happen, if it was to happen anywhere,” Hartley said, noting that some combination of Sprint, Japanese company Softbank (majority owner of Sprint) and T-Mobile—a rumored acquisition target of Softbank—would be particularly interesting.