The advent of LTE has resulted in a dramatic increase in the complexity of the mobile landscape. Whereas a 2G/3G smartphone required interoperability testing between GSM, GPRS, EDGE, and HSPA+, a 4G smartphone requires additional interoperability testing, incorporating LTE and soon LTE-Advanced (LTE-A).
Furthermore, network equipment and device testing must accommodate a wide range of frequency bands. There are over 40 frequency bands currently specified for LTE operation. Add to all of that multiple channel bandwidths, FDD/TDD variants, and varying antenna configurations, and the complexity and number of test combinations increases substantially.
LTE-A adds further complications to the mix. Carrier aggregation introduces multiple combinations of contiguous/non-contiguous frequency bands with various combinations of channel bandwidths. New uplink and downlink antenna configurations, associated MIMO (multiple-input multiple-output) schemes, HetNet, improved support for HetNet with enhanced Inter-cell Interference Coordination (eICIC), and many more new features are driving increased requirements for highly capable testing solutions to guarantee, ultimately, a high-quality end-user experience.
As a result of this complex environment, interoperability requirements are expanding with LTE and soon with LTE-A. New devices will need to continue to interoperate with pre-existing legacy standards. As new technologies and standards are introduced, there is an increased opportunity for things to go wrong. It is imperative that LTE equipment be able to interoperate on legacy standards when necessary.
Spectrum resources are scarce. Different countries have unique frequency-band availability for LTE, which currently has 12 commercially deployed frequency bands and could potentially make use of more than 40 bands. LTE equipment will need to undergo rigorous testing to ensure that it can work effectively across several networks, in various countries, and also in non-contiguous frequency bands.
This capability is essential to support data roaming, not just between LTE networks that have a limited footprint at present, but across legacy networks to ensure users have a consistent mobile data experience.