SAN FRANCISCO – More than a dozen companies are supporting a proposed standard for device-to-device links in Long Term Evolution handsets. They believe Direct LTE will offer capabilities and power efficiency for location-based applications not available with today’s Wi-Fi Direct and GPS links.
Direct-LTE is based on line-of-sight links at a range up to 500 meters and 20-23 dBm signaling limits. The technique could discover local users more quickly with less processing overhead than Wi-Fi Direct or GPS, said Mahesh Makhijani, a director of technical marketing at Qualcomm, in a presentation at
the conference here of the NGMN Alliance.
Qualcomm said in its internal tests, LTE Direct discovered as many as 7,200 terminals in 0.64 seconds compared to 369 terminals found in using Wi-Fi Direct that took 82 to 119 seconds. The chip makers tests also found latency for Wi-Fi Direct discovery degraded significantly as device density increased.
Nevertheless, Makhijani said LTE Direct could work with Wi-Fi Direct. For example, in some cases it might be more useful to send data via Wi-Fi Direct after devices had been found using LTE Direct, he said.
A wide range of operators, system and chip companies back the idea, including Alcatel-Lucent, Deutche Telekom, LG, NEC and Nokia. They proposed adding Direct LTE to the 3GPP group’s LTE Release 12, slated to be available in 2015. However, the group may consider defining an ad hoc standard to get Direct LTE into products earlier.
Direct LTE could support “proximity services that provide more value to the mobile network,” said Makhijani.
A handful of emerging mobile applications are adopting the concept of ambient awareness including FourSquare Radar and the Twitter Discovery tab. Venture capitalists spent an estimates $500 million on the theme over the last year, said Makhijani.
Qualcomm showed a simulation of Direct LTE at the event. The technique requires upgraded transceivers in handsets, not yet available in current chip sets.