If you have both cellular and Wi-Fi, why not use both? At Mobile World Congress, Alcatel-Lucent is demonstrating a way to do that as part of the same network.

Cellular and Wi-Fi are rubbing shoulders more than ever, even if that can cause friction in some cases. It’s all part of the quest for more mobile capacity for applications like video streaming. Several ways of using them together are on show at MWC.

Like other vendors, Alcatel is pursuing LTE-U, which lets an LTE network use the unlicensed spectrum that powers Wi-Fi. But the French-American company is also demonstrating a technique it calls Wi-Fi boost, where users can upload data to the Internet over cellular and download it using Wi-Fi. The company plans trials of Wi-Fi boost in the second quarter of this year and will start selling it in the second half.

+ See our full coverage of MWC 2015 +

The technology doesn’t make the networks swap spectrum and doesn’t require new cells, access points or mobile devices. It’s all done in software, both in devices and on the back end of the carrier’s network.

Wi-Fi boost is designed for locations where there’s both Wi-Fi and cellular service, such as in homes, enterprises and public hotspots. It can boost download speed by using Wi-Fi’s fatter spectrum band, and because Wi-Fi doesn’t have to handle both download and upload traffic on the same frequencies, it can actually improve performance in both directions, said Mike Schabel, general manager and vice president of small cells at Alcatel-Lucent.

Users could get up to a 70 percent boost on downloads and an order of magnitude increase in upload capacity, the company says. A later version would allow the two networks to combine their download signals, too, leading to an even bigger boost.

To make Wi-Fi boost happen, a mobile operator would update the software that controls its network with the new version that can split up traffic between Wi-Fi and cellular. The capability would also require an OS update for subscribers’ devices. Wi-Fi boost complies with current standards, Schabel said.

A mobile operator couldn’t just arbitrarily pull in any Wi-Fi network for this service. It will be a matter of planned provisioning with subscribers, enterprise customers and partners. That’s good news if you’re worried about your carrier taking over your home network, but it could make the job tougher for carriers that want to add a lot of Wi-Fi networks to their coverage.

Setting up Wi-Fi boost would be more complicated than, for example, just handing subscribers off to a third-party Wi-Fi hotspot, said analyst Peter Jarich of Current Analysis.

“If we’re talking about mixing and matching uplink and downlink, that implies a tighter coordination,” Jarich said. It could be complicated on the business side as well: If the Wi-Fi router in your home were supplied by one carrier and your cell provider was a competitor, you might have to buy your own router for Wi-Fi boost to work, Alcatel’s Schabel said.

Yet Alcatel’s new approach might show up sooner than LTE-U, which requires new cell and device hardware. It’s a way of reusing today’s networks.

“The reality is, we have huge Wi-Fi networks that are already out there,” Schabel said. “Let’s go use them.”