Mobile operators including Verizon, SK Telecom and T-Mobile US are investigating the performance benefits that LTE Advanced in unlicensed spectrum can have for their networks, after Ericsson and Qualcomm reported they have reached peak rates of 450 Mbps by combining licensed and 5 GHz unlicensed spectrum on small cells.
LTE Advanced in unlicensed spectrum, more officially known as License Assisted Access (LAA) and generally referred to as LTE-U, is described as a mobile technology innovation that improves indoor coverage for smartphone users. As the name suggests, the technology makes use of unlicensed spectrum in the 5 GHz frequency band.
As Ericsson explains it, LAA or LTE-U extends the benefits of LTE to unlicensed spectrum, providing reliable and predictable performance. The licensed band provides an anchor to ensure a seamless user experience with full mobility while the unlicensed band provides incremental capacity and enables faster data speeds.
“It is very encouraging to see License Assisted Access live in the Ericsson labs already delivering on the promises of both a better mobile broadband customer experience and the fair sharing and co-existence within the 5 GHz band among wireless and Wi-Fi devices. With over 500 MHz of under-utilised spectrum in the 5 GHz Unlicensed National Information Infrastructure (UNII) band, LAA can provide our customers with superior network performance while effectively co-existing with other Wi-Fi devices to ensure a better experience for all wireless users," said Neville Ray, T-Mobile US CTO.
Work on the technology is contentious, nonetheless, and indeed has elicited warnings from the Wi-Fi Alliance over the impact that LTE-U could have on existing Wi-Fi services in the 5 GHz band.
“There is a risk that LAA, and especially pre-standard systems deployed ahead of coexistence work being done in the industry, will negatively impact billions of Wi-Fi users who rely on 5 GHz today for networking and device connectivity. It is generally agreed in principle that fair sharing is required, but there needs to be further work from all parties to address this risk in practice,” the industry body said in a statement.
The Wi-Fi Alliance added that it is planning to collaborate with the 3GPP, and is “eager to work with those planning pre-standard deployments to help them continue to satisfy the expectations of Wi-Fi users.”
Ericsson said it will be adding LAA to its indoor small cell portfolio from the fourth quarter of 2015. This includes the Ericsson RBS 6402 Indoor Picocell (targeted at smaller buildings under 50,000 square feet) and the Ericsson Radio Dot System (for medium and large buildings).
The Sweden-based vendor also noted t hat LAA’s use of higher frequencies on small cell architectures, and the aggregation of licensed with unlicensed spectrum bands, reflect 5G technology focus areas, highlighting the way that vendors expect today’s LTE networks to evolve into future 5G standards.
