For operators solving the 1000x challenge, licensed spectrum is the foundation. Equally important is leveraging all of the available spectrum, including unlicensed. The best way to make use of unlicensed spectrum is to aggregate it with a licensed LTE anchor.
There are two solutions for aggregation: LTE – Wi-Fi link aggregation, for existing and new carrier Wi-Fi utilizing both 2.4 GHz and 5 GHz; and LTE in unlicensed (LTE-U) for new small cells utilizing 5GHz. Many operators will do both.
Mobile wireless has spanned across many technologies (3G/4G/Wi-Fi), across several bands, and across different licensing models (licensed, unlicensed, and LSA). Aggregating all the available spectrum resources enables operators to increase overall network capacity and to provide best possible mobile broadband experience to users.
Carrier aggregations defined in EV-DO, HSPA+, LTE allows combining different bands of the same technology, as well as across licensed and unlicensed spectrum (for LTE Advanced). Supplemental Downlink (SDL) is a special case of carrier aggregation enabled by HSPA+ and LTE Advanced. It aggregates unpaired spectrum with the downlink of paired spectrum substantially increasing downlink capacity. SDL is on track to be commercially deployed globally (e.g. L-band/1400 MHz in Europe & 700MHz band in the US).