LTE is still a few years away and many questions about the technology and business model remain unanswered. So why are many operators and equipment vendors betting on LTE today?

This is a simple question, with many different answers. While some operators view LTE as a disruptive technology, others see it either as an evolutionary path from their current technology, or as a complement.

For example, according to Telstra executive director Mike Wright, LTE will not replace the Australian telco's HSPA network that was deployed earlier this year, but rather will serve to complement it where there are capacity issues or more spectrum is needed. Telstra wants to utilize different spectrum ranges.

LTE will provide the flexibility of using 900 MHz; at some point they will want to utilize their 1800 MHz spectrum and may also want to acquire 2.6 GHz spectrum if extra capacity is needed. One major advantage Telstra sees is that LTE is much more flexible when it comes to awkward-shaped channels. For instance, at 900 MHz Telstra has 8.4 MHz of bandwidth. LTE will provide much more efficient usage of that type of channel than would W-CDMA.

The evolution to LTE is also compelling for some operators because of reduced capex and opex compared to previous 3G networks. Some will be able to leverage their existing 3G networks to upgrade to LTE. For those without a mobile/cellular infrastructure, deploying an LTE network might not be a cost effective solution.

For Telecom Italia, LTE will be an overlay technology for its 3G network to provide higher bandwidth services. Alberto Carnellio, director of business innovation at Telecom Italia, argues that 3G and HSPA have been very successful, and sees 4G as an evolution from 3G and HSPA that will bring improvements in terms of efficiency and performance. A question to keep in mind is what would happen if traffic grows beyond HSPA capacities? What about spectrum availability?

Joachim Horn, CTO of T-Mobile International, says that HSPA has been developing well. The operator plans to continue profiting from this development, but foresees a limitation in capacity in a couple of years as traffic increases. T-Mobile will start deploying LTE as a host-spot high traffic zone solution, and as the technology matures and interoperability issues are resolved, it expects a major rollout of LTE.