As the only major U.S. carrier to deploy TDD-LTE, Sprint takes a unique approach to utilizing spectrum.
February 24, 2014
By Dr. John Saw, SVP, Technical Architecture, Sprint
This week as the wireless industry makes its way to Barcelona, we’ll be participating in the 2014 Global TD LTE Initiative (GTI) Summit held annually at Mobile World Congress. We’re pleased to join an impressive roster of executives from leading companies such as SoftBank Group Corp Mobile, China Mobile, Bharti Enterprises, Vodafone and others, to discuss how we can work together to further the global TDD-LTE ecosystem.

Sprint is in a unique position as the only carrier in the U.S. to utilize both TDD-LTE and FDD-LTE in its network design (other major carriers rely solely on FDD-LTE). These two access technology protocols are extremely similar, but with one main important difference – how they utilize spectrum.

TDD-LTE offers the flexibility to allocate bandwidth to downlink and uplink traffic; whereas with FDD-LTE, uplink and downlink channels are symmetrical. In practical terms, with TDD-LTE, Sprint can create a wider channel for busy downlink traffic (say, for video streaming during primetime viewing hours each evening) and a narrower channel for uplink traffic. This allows us to adjust the network to apply capacity and speed where and when customers need it most.

With Sprint Spark™ and TDD-LTE, we’re able to combine our unpaired spectrum bands and therefore achieve greater spectral efficiency. We typically use FDD-LTE spectrum to provide baseline coverage for our customers. And we use TDD-LTE for capacity and higher speeds - this is our performance layer. What brings it all to life is our tri-band devices that allow customers to seamlessly move between spectrum bands.

Looking ahead, we’re particularly interested in Sprint Spark and TDD-LTE for small cell solutions to add capacity in densely populated areas with high mobile data usage. As data usage grows, offload to Wi-Fi will also be increasingly important. And with TDD-LTE there is the potential to provide offload that is always on, with users moving easily in and out of WiFi networks in the home, at work, and virtually everywhere in between.