Emerging LTE Direct standard would go peer to peer for 4G mobile location

Qualcomm is promoting a peer-to-peer cellular technology as a potential new standard called LTE Direct, which it says would make location-based services faster and more efficient.

The proposal grew out of FlashLinq, a system Qualcomm developed in its own labs. FlashLinq lets two cellular devices communicate over the air without relying on a fixed network infrastructure. Qualcomm sees two main applications for the technology: public safety communications in areas where mobile networks are down or unavailable, and a "discovery mode" that provides information about what interesting things and people are nearby. Qualcomm is primarily interested in the discovery mode, which it says has more commercial potential.

LTE Direct eliminates steps in the location process, allowing users to find things more quickly, Qualcomm says. Though the technology can be used for ongoing communication at high speeds, including streaming video, in discovery mode it would only broadcast tiny 128-bit packages of data. Those packages, called "expressions," would contain basic information about the device or user. Each LTE Direct device would look for expressions nearby, choosing among them using filters customized for the user or for specific applications.

"What you do is, every so often, you broadcast this 128 bits of information, which are expressing your desire ... so devices and services around you can listen to (your expressions) and figure out what you're interested in," said Mahesh Makhijani, senior director of technical marketing at Qualcomm.

Mobile consumers as well as businesses could send and receive expressions. If an application detects an expression that's relevant to what it does, that application can then go into action, providing something to the user. For example, if two friends have devices that are sending out expressions, then a social-networking app that both of them use might pop up notifications for each saying the other friend is nearby. A classic example of an application that might take advantage of discovery mode is the location check-in app Foursquare, Makhijani said.

Decentralized process

Current location-based services rely on a central database of location data. Every party's location, determined by GPS or other methods, has to be collected in that database and then sent out to other interested parties who request it, Makhijani said. LTE Direct finds nearby devices directly over the air.

Finding a match between one user and other people or services nearby is also quicker, because "service layer" information is contained in the 128-bit expression, Makhijani said. That service layer information determines whether something is of interest to you, such as whether someone uses Facebook and is a friend, or whether your favorite store nearby is offering a deal. To determine these things with LTE Direct, it's not necessary to query a central server over the Internet or even to establish a dedicated connection with the nearby device, he said.

LTE Direct isn't intended to provide exact location or replace GPS for finding out exactly where you are, but it could complement existing location systems and speed up the process of finding out where you are, Makhijani said. Its benefits include the speed of proximity-based location as well as its ability to work indoors, where GPS often has trouble getting a fix because it relies on satellites, he said.

Even though the technology works directly between devices and not over a fixed network, Qualcomm believes licensed spectrum is essential for achieving the efficiency and scalability that LTE Direct promises in discovery mode, Makhijani said. The key is having the frequencies under the command of a service provider, with interference controlled. Carriers could carve out a very small part of their regular uplink band, perhaps 1 percent or 2 percent, for LTE Direct, he said. For public safety or other modes, LTE Direct could run over unlicensed spectrum.

Developers of mobile apps could take advantage of LTE Direct through an API (application programming interface) provided by the mobile operator or a third party, Makhijani said. Users could turn LTE Direct on and off when they chose, and turn specific types of expressions on and off depending on the context, such as home or work, he said.

Born in company labs

Qualcomm worked on FlashLinq for about four years in the company's New Jersey research facility, Makhijani said.

"Last year, we decided that it would make sense from an overall ecosystem perspective ... to bring some of those concepts into LTE," Mahesh said. However, not everything about the technology is set down yet, and the company doesn't expect its idea necessarily to be adopted wholesale. Its hope is to get others involved in refining it and finding use cases, he said.

Qualcomm submitted the technology as a Study Item in the Services and Architecture group of the 3GPP (Third-Generation Partnership Project) last September. 3GPP oversees the LTE standard. Qualcomm hopes to also make it a Study Item in 3GPP's RAN (Radio-Access Network) group in September. The next phase would be for LTE Direct to become a Work Item. If the idea continued to advance, the system could then become part of LTE Release 12 or Release 13, which will probably come out in 2014 or 2015, Makhijani said.

Making the technology part of LTE would be a significant boon to adoption, even though it has so many possible applications that may be hard for developers to grasp exactly what it's good for, said analyst Peter Jarich of Current Analysis. "It's a little bit confusing," Jarich said. "Is it location? Is it advertising? Is it marketing?"

Speed matters

However, the underlying benefit of quickness has value, he said. Speed is a hot issue in mobile location, because when users consult a map or a location-based app on their phones, they want it to be oriented to their current location instantly, Jarich said. He thinks LTE Direct could become part of a basket of location technologies that complement GPS, allowing an application to combine information from various sources.

In some cases, location can be crucial to an app, Jarich said. For example, a fitness device designed to track and calculate your movements is useless until it can determine its location. The usefulness of a location-based app or any other tool tends to drive more use, which helps carriers and application providers, Jarich said.

LTE Direct might also prevent false-positive results about things being nearby, Jarich said. When current location technologies can't give precise enough information, location-based services may show that a mobile user is near to a business that is actually miles away, which helps no one, he said.

"If you had something that could look for your location based on proximity, then you be much more accurate with that stuff," Jarich said.

Stephen Lawson covers mobile, storage and networking technologies for The IDG News Service. Follow Stephen on Twitter at @sdlawsonmedia. Stephen's e-mail address is stephen_lawson@idg.com