The global adoption of LTE services risks being hampered by device interoperability issues unless spectrum fragmentation challenges can be overcome, according to a new Wireless Intelligence report.

The new report – Global LTE network forecasts and assumptions – one year on – predicts that there will be 38 different spectrum frequency combinations used in LTE deployments by 2015, a fragmented scenario fuelled by ongoing spectrum auctions, licence renewals and re-farming initiatives across a wide range of frequency bands.

The lack of spectrum harmonisation represents a key challenge for the emerging LTE ecosystem, potentially preventing vendors from delivering globally compatible LTE products such as devices and chipsets.

"Spectrum fragmentation has the potential to hinder global LTE roaming if device manufacturers are required to include support for many disparate frequencies in their devices," said Wireless Intelligence senior analyst and report author Joss Gillet (pictured). "Given the backwards compatibility already required for either HSPA or EV-DO connectivity, we are unlikely to see a 'world' device in a handset form-factor soon."

Wireless Intelligence forecasts that there will be over 200 live LTE networks in 70 countries by 2015, up from 40 networks in 24 countries today. The number of LTE connections is forecast to grow from 7 million to close to 300 million over the same period.

The report notes that the IMT-extension band (2500/2600MHz) is the most common band used in LTE deployments to date, accounting for over half of live networks. However, more than two thirds of global LTE connections today relate to deployments at 700MHz due to the large-scale rollouts underway in the US.