LTE in unlicensed spectrum has been getting a lot of attention this month, most notably from the Federal Communications Commission. It is clear that some Wi-Fi equipmentmakers will not welcome cellular networks in the 5 GHz band. An alternative may be LTE Wi-Fi link aggregation, or LWA, a technology developed by Qualcomm and first demonstrated by Alcatel-Lucent.
“It achieves a lot of the same benefits as LTE-unlicensed, but doesn’t need to have new handsets,” said analyst Monica Paolini of Senza Fili Consulting, a strong advocate of LWA as a way for carriers to integrate Wi-Fi and cellular. LWA uses LTE for the uplink and both LTE and Wi-Fi for the downlink. It requires a software update for devices so they can engage their Wi-Fi radios to handle some LTE traffic, which is collected at Wi-Fi access points and then sent to an LTE small cell.
“It’s expected that LWA will proceed rapidly through the standards process and emerge in 3GPP Release 13 in the summer of 2016,” blogged Steve Hratko of Ruckus Wireless earlier this year. “With LWA, Wi-Fi runs in the unlicensed bands and LTE runs in the licensed bands, and the two radio technologies are combined to offer a compelling user experience.”
“It allows you integrate LTE and Wi-Fi in the RAN,” said Paolini. “You optimize the way you split traffic between the two interfaces.”
Integrating Wi-Fi and LTE may not be on the roadmaps of most mobile operators, but some argue that it should be. Cisco projects that by next year more mobile data traffic will be offloaded to Wi-Fi than will remain on cellular networks.
“Wi-Fi is more than offload, it really is the dominating interface for IP traffic in general, and mobile devices in particular,” said Paolini. “So most of the traffic that you see in a mobile device actually goes through Wi-Fi so in that sense Wi-Fi has been sort of a free ride for mobile operators. It really helped them build the usage case … in a way Wi-Fi is the main interface for wireless access.”
Operators can choose to let users handle their own Wi-Fi offload, something many mobile subscribers do already when they enter their homes or offices. But as Wi-Fi takes an increasing share of mobile traffic, and expands to include voice calls, operators may want to take control and integrate Wi-Fi with their core networks. This can be accomplished through LWA, opening up the possibility that carriers could eventually bill subscribers for time spent on partner Wi-Fi networks.
For more on Wi-Fi offloading and Wi-Fi/cellular integration, download the RCR Wireless News on-demand feature report and watch the complimentary webinar: Strategies for Effective Wi-Fi Offloading.
