Femtocells, an emerging technology for improving cellular coverage in homes and enterprises, have attracted the interest of none other than Google.

The search giant participated in a US$25 million round of funding for Ubiquisys, a femtocells vendor based in Swindon, U.K. Technology venture funds Accel Partners, Atlas Venture and Advent Venture Partners also invested, Ubiquisys announced Friday.

Femtocells, named for an order of size in physics that is smaller than "pico" or "nano," are cellular base stations for individual homes or offices. Mobile operators hope to sell them to customers who will install them and immediately enjoy better coverage for data and entertainment services. Weak cellular signals indoors, where most high-speed data services are used, have stunted the growth of those lucrative offerings, according to industry analysts.

Google invested in Ubiquisys as part of efforts to help people use the Internet wherever they are, with the richest possible experience, spokesman David-John Collins said.

"It's about promoting different ways and platforms for people to access the Internet itself," Collins said.

Also Friday, the company told the U.S. Federal Communications Commission it would bid at least US$4.6 billion in an upcoming auction of 700MHz wireless spectrum if it imposes certain conditions. They include letting consumers buy any phone, use it on any network, and download any applications, services or content they want. Google also wants the auction winner to have to sell access wholesale to other service providers.

Google's investments in unused optical fiber networks and a free Wi-Fi system for its hometown, plus its planned involvement in a San Francisco Wi-Fi network, have led to theories that it plans to compete with incumbent broadband providers. The company has also invested in Wi-Fi sharing technology vendors Fon Technology SL and Meraki Networks and powerline broadband provider Current Communications Services, Collins said.

Privately held Ubiquisys was founded in 2004 and earlier this year introduced the ZoneGate femtocell system. Many established carrier equipment vendors, including Nokia Siemens Networks, Motorola and Alcatel-Lucent, also are developing and testing femtocell technology. Commercial deployment of the devices is expected to start in earnest next year.