International Agents: LTE Unlicensed

Unlicensed Spectrum Open the Door to Resellers

By: Tara Seals
CV_MayJune16_Cover
[Excerpt from ChannelVision May – June 2016]

Faced with the scarcity, cost and difficult propagation characteristics of the remaining greenfield licensed spectrum, one of the first steps in achieving a nextgen wireless network vision that can stand up to the growing thirst for rich content will likely be the use of unlicensed LTE approaches.

LTE-U, as it’s known, will allow operators to extend and enhance their LTE coverage and network performance – but it also paves the way for higher-margin MVNO services that could reinvigorate the global wireless resale market.

Unlicensed LTE approaches typically aggregate Wi-Fi and unlicensed spectrum in order to get the maximum benefit out of Wi-Fi’s heightened bandwidth throughput – while leveraging LTE links for signal control and management.

One approach is now under development by 3GPP for standardization in Release 13 – to be known as License Assisted Access (LAA). That standard is expected to be finalized this summer. Heavy hitters such as Verizon and Qualcomm are embracing the approach.

It works like this: The LTE control channels, and primary uplink/downlink channels, are handled in the licensed bands, using LTE-A Carrier Aggregation (CA) to do channel bonding between the licensed and unlicensed downlinks, and possibly the uplinks in follow-on iterations. The purpose of the unlicensed bands is to provide additional data plane performance – a data plane boost, in effect.

To minimize interference, it has a “listen before talk” (LBT) mechanism, which is the same approach that Wi-Fi uses to share the unlicensed spectrum with other Wi-Fi systems.

“LTE in unlicensed spectrum will be an important part of the network densification initiatives to increase network capacity, using small cells that support LTE in 5GHz,” said Adam Koeppe, vice president of network technology planning at Verizon. “LTE in unlicensed spectrum also offers an evolutionary path based on specifications being developed in global standards groups (3GPP), to continuously enhance the capabilities of LTE in unlicensed spectrum. For example, a future 3GPP release (3GPP Release 14) will allow uplink operation using 5GHz.”


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While LAA does have LBT involved, there are still concerns from other stakeholders when it comes to interference. With LAA, LTE is operating in both the licensed bands and within the same spectrum that Wi-Fi uses – so there are two signals in the same band, and therefore the potential for coexistence problems.

To address this, Verizon and all other LTE-U Forum members are collaborating with the Wi-Fi Alliance (WFA) in the development of a very comprehensive coexistence test plan geared toward the lab validation of coexistence with Wi-Fi. But, there is also another technology approach that could save the day.

Licensed Wi-Fi Access, or LWA, is also on track to have a final iteration in the 3GPP Release 13 spec.

As its name would suggest, LWA represents true LTE-Wi-Fi convergence. With LWA, Wi-Fi runs in the unlicensed bands and LTE runs in the licensed bands, and the two radio technologies are combined to offer a compelling user experience. The control channel for the traffic remains in an LTE uplink. Meanwhile, on the downlink, operators get a significant speed boost from using Wi-Fi for transmission.

From a more technical standpoint, LWA tunnels LTE traffic in the 802.11 MAC frame, so it will look like Wi-Fi to another network, even though it is carrying LTE data.

It also eliminates interference worries, because with LWA, LTE is aggregated only in the licensed bands, leaving Wi-Fi the master of its domain.


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Cable operators and others that have extensive Wi-Fi holdings could be in the catbird seat with this one, either because of the opportunity for leasing their footprints to wireless carriers or by enabling new entrants on an MVNO basis. They could leverage their footprints themselves as well, working with LTE providers for the signaling and management piece but maintaining their own last-mile footprint themselves. In theory this could radically lower the economic barrier to entry to get into wireless resale – a notoriously low-margin business in a white label or pure-play resale iteration.

Both of these existing unlicensed LTE approaches require anchor spectrum; in other words, operators still need a licensed band to handle signaling, while the unlicensed spectrum is used to boost capacity. But a new approach called MulteFire proposes a standalone LTE-based technology for small cells that would allow anyone, even those without any licensed spectrum, to build an LTE network.

This means that cable MSOs and others could use MulteFire as a path to creating their own large-scale networks, with the aim of either providing add-on retail service to the triple play or for business customers, or becoming neutral host providers. That neutral wholesale environment can augment wireless network operator environments by providing enterprise penetration, and spawn a new kind of MVNO opportunity. Because MulteFire is a variant of LTE, synching up for roaming agreements presents limited technical obstacles.


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About ChannelVision Magazine:

ChannelVision is a bi-monthly digital and print magazine, read by channel partners selling all manner of voice, data, access, managed and business services (both on premise and “in the cloud”), as well as, technology, gear, and equipment.  ChannelVision is a highly focused and efficient way for service providers, hardware, and software companies to reach experienced channel partners targeting the small/medium business space.  Serving a controlled circulation of providers and indirect distributors of communications, network, IT and cloud-based business services, ChannelVision is telecom’s gateway to perspective on how to adapt, what to sell, and how to sell it.