Ericsson pushing for 3GPP's Release 13 to enable LTE in unlicensed spectrum

Ericsson (NASDAQ:ERIC) is more widely publicizing its desire to get 3GPP on board with the idea of enabling LTE for use over unlicensed spectrum, such as that used by Wi-Fi.

"Getting access to additional licensed spectrum is the highest priority," because it enables operators to control network interference to provide higher quality service, wrote Stefan Parkvall, principal researcher at Ericsson Research, in a recent blog post.

But he added that unlicensed spectrum can serve as a complement, particularly if it is aggregated with licensed spectrum to increase bandwidths. "With this in mind, Ericsson is proposing to extend LTE in Release 13 so that unlicensed spectrum can be exploited for offloading best-effort traffic through the carrier-aggregation framework," he said.

"Mobility, critical control signaling and services demanding high quality-of-services rely on the licensed spectrum while (parts of) less demanding traffic can be handled by the unlicensed spectrum," Parkvall added.

Ericsson proposes extending LTE in release 13 so that unlicensed spectrum can be exploited for offloading best-effort traffic through the carrier-aggregation framework.

Qualcomm (NASDAQ:QCOM) began championing so-called "LTE-U" or unlicensed LTE back in November 2013. However, some supporters of opening more unlicensed spectrum have pushed back, alleging that LTE does not belong on unlicensed spectrum. The debate appears to pit cellular industry players against parties supporting the availability of more unlicensed spectrum vs. licensed spectrum.

Nick Karter, vice president of  business development for Qualcomm Atheros, told FierceWirelessTech during the recent  Mobile World Congress trade show in Barcelona, Spain, that deploying LTE in unlicensed bands would be no different that enabling other unlicensed uses.

"LTE is just another airlink you can put there. It could be Bluetooth. Nobody is complaining about Bluetooth using 2.4 GHz. DECT phones are all at 5 GHz. Do you see people complaining about DECT phones at 5 GHz?" said Karter.

He cited Ericsson and Verizon (NYSE:VZ) as companies supporting LTE-U. Alcatel-Lucent (NYSE:ALU) also backs the concept.

In addition to LTE-U, Parkvall explained other visions Ericsson has for the future evolution of LTE with regard to the upcoming 3GPP Release 13, which he noted the industry hopes to finalize by the end of 2015. 3GPP is currently finalizing Release 12.

Parkvall said new takes on multi-antenna techniques, including beamforming, can be used to boost data rates and system capacity. For example, while the azimuthal direction is usually used for evaluations, research has shown that exploiting the elevation domain can also help increase capacity in some scenarios, such as city centers with high-rise buildings.

"Therefore, we propose to explore the potential gains with elevation-domain beamforming in 3GPP. One example of an enhancement is pathloss measurements to multiple candidate beams to determine the beam best suitable to serve a particular terminal," Parkvall said.

Noting that LTE will be "a cornerstone of the overall 5G solution," he also recommends 3GPP pursue some other avenues that many see as key to the next generation of wireless. 5G researchers have focused on reducing latency to enable new use cases, and, similarly, Ericsson wants 3GPP to investigate more ways to slash latency.

For example, Parkvall notes that "instant uplink access" could be enabled via an extension to the specifications. In this case, a terminal would be granted permission to transmit in advance, rather than having to request permission when the uplink data arrives to the terminal.

Enabling support for M2M communications using "low-cost, low-power, simple devices" is another example of where current LTE work might complement 5G efforts. "We would like to continue the work started in release 12 and we are aiming for further improving the support for massive machine communication," Parkvall wrote.

For more:
- see this Ericsson Labs blog post

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