LTE TDD is a mode of the common LTE standard specified for unpaired spectrum and benefit from the common LTE ecosystem. Initially, the choice between FDD and TDD is driven by spectrum availability, but it is expected that most operators will deploy both networks to leverage all their spectrum assets.
LTE TDD is a mode of the common LTE standard, that is specified for the unpaired spectrum. Being a common standard, LTE TDD has the same features and evolution as LTE FDD. This commonality enables vendors to develop common TDD/FDD products and leverage from the single, vast and expanding LTE ecosystem. Initially, the choice between FDD and TDD is driven purely by spectrum availability, but it is reasonable to expect that most operators will deploy both networks to take advantage of all available spectrum resources.
Qualcomm Technologies’ industry-first Qualcomm® GobiTM modem LTE/3G multimode modems have been supporting both FDD and TDD modes from their first generation itself. The common chipsets have immensely helped vendors to develop common devices and rapidly bring a full range of LTE TDD devices— including popular smartphones— to market, in a cost-effective manner. Our recently announced fourth generation Gobi LTE modems, which are also integrated into Qualcomm® SnapdraonTM processor, will propel both LTE FDD and TDD to new heights.
LTE TDD has been commercial since 2011 and is gaining global momentum. The initial global unpaired bands include 2.3GHz (B40) used in India and 2.6 GHz (B38) used Europe, with variations (B41) in the U.S. and Japan. China is expected to launch LTE TDD in multiple global bands.
LTE TDD is truly global and many operators have both FDD and TDD modes in the same network. That trend will continue and it is reasonable to expect that most of the operators will deploy both the FDD and TDD modes to utilize all spectrum assets—paired, unpaired, lower bands and new higher bands.
Being a common LTE standard, LTE TDD inherently interworks with LTE FDD to offer seamless voice and data services, as well as common seamless 2G/3G interworking. In the future, this interworking will evolve in many directions and will become even more robust. For example, carrier aggregation across paired and unpaired spectrum and aggregation across different cells of LTE TDD and FDD (mulitflow). The interworking is especially beneficial in Hetnets; for example, aggregation across LTE FDD macros and LTE TDD small cells to best utilize spectrum resources.
In the effort to increase data capacity by 1000x, small cell densification is a crucial step and that starts with the existing spectrum. However, getting more spectrum is a critical requirement. In addition to lower bands, operators have to consider bandwidth-rich higher bands with 3.5GHz being the first target. In most regions, this band, as well as many other higher bands are unpaired. So, LTE TDD is a must to access these bands.
LTE TDD small cells in higher bands are one of the most potent solutions to solve the 1000x challenge.