As the Navy charts a course for future shipboard deployments of 4G Long Term Evolution, the commercial world is making strides that help enable high-speed connections at sea. To understand what solutions the Navy may be able to grab hold of in the near future, it helps to take a look at where commercial LTE technologies are headed.

Navy already has made it clear it wants to bring high-speed connectivity to sea. As early as 2012 it was running afloat trials of 4G LTE. More recently, a $16 million demonstration put LTE on a pair of vessels operating in the Persian Gulf: the amphibious assault ship Kearsarge and the transport dock San Antonio.

The ships were equipped with a microwave-based wireless wide-area network (WWAN) that gave sailors access to voice, text and video communications between ships and to real-time streaming video produced by helicopter-based systems up to 20 nautical miles away.

That pilot program showed that LTE is possible at sea, but it's a complicated affair. Ships are structurally unsuited for LTE: too many antennas in not enough space. Ocean conditions can drive signal instability in ship-to-ship communications, and crowded spectrum make portside 4G a dicey proposition.

Benefiting from leaky signals

Shipboard LTE faces geometric problems. Space on board is limited, and yet successful LTE can require the deployment of dozens of antennas. Moreover, structural issues arise: A closed steel door between two antennas can cut off signal.

It may not be a perfect fix, said Jan Kwiatkowski, vice president of consulting at global telecom consultancy P3 Communications, Inc. "It is a lot of effort, a lot of cable to use," he said.

Rethinking satellite configurations

At the Trident Warrior 2015 event in June, the Navy's 7th Fleet got a look at an emerging approach to satellite deployment that could help bring LTE to ships at sea. Integrator Oceus Networks joined with TrustComm and O3b Networks to demonstrate what O3b calls a more efficient satellite configuration.

Unlike legacy geostationary satellites, Medium Earth orbit (MEO) satellites can deliver LTE at higher broadband and with less latency, said Nat Gough, vice president of business development at O3b.

Orbiting four times closer than legacy satellites, the MEOs can deliver very high speeds in a single 700km/450NM wide beam, Gough said.

The advantage to an MEO solution may be one of infrastructure: By achieving LTE simply through a modified satellite configuration, Navy might sidestep questions of antenna configuration and other hardware-related concerns.

Connecting ship to ship

Bringing LTE to a ship and distributing it throughout the vessel are just a part of the overall high-speed equation. The Navy also is challenged to maintain LTE in ship-to-ship communications. "LTE was ever only meant as a platform for a single ship," said Jeramey Franklin, marketing manager at Bats Wireless, which has been working with the Navy on LTE projects since 2012 with Cambium and Oceus Networks.

One possible fix comes in the form of the stabilized microwave, a technique for maintaining a direct radio line between ships moving at sea. "This eliminates the need for satellites for inter-fleet communications, and allows for the ships to be more than a half mile away from one another. Depending on environment, they can be as far as 20 miles away," Franklin said.

An alternative to this would be to combine a high-frequency advanced millimeter wave with advanced optics to create a single narrow beam that could maintain a steady high-speed connection between two unstable points, such as ships at sea. Such a setup might help to overcome the effects of weather and other destabilizing elements, said Christina Richards, vice president at wireless solutions developer AOptix.

Minimizing interference

Shipboard antennas can create a logistical problem, with limited space and complex configurations, while the sheer volume of equipment needed also creates telecommunications hurdles. "When you have 20 different antennas co-located, you are going to have some bleed-over effect," said Andrew McCandless, president of Bascom Hunter, a wireless telecommunications firm that has worked with the Navy on anti-jamming technologies for littoral combat ships.

One typical solution to this kind of interference is to skip signal over to another channel. On a ship where there's already a logjam, the next channel will likely hit the same problem. One option may be to look instead at cleaning up the interference as it arises. "You basically have to remove the interference that is in your channel. That is a key part of getting more capacity and having a more robust network," McCandless said.

The commercial world has a number of interference cancellation technologies in various stages of maturity. Successive interference cancellation, for example, can detect and remove noise from the signal. It's also possible to minimize interference through strategic placement of antennas.

Spectrum solutions

Spectrum crowding is a problem that reaches across all of telecommunications, but it may have special implications for the Navy.

To support the boom in wireless usage, a 2010 Presidential initiative directed the Secretary of Commerce to make available some 500 megahertz of federal and nonfederal spectrum for broadband use. While the project has generated some $41 billion in revenue, "continuing to auction spectrum is not realistic or sustainable given the finite nature of spectrum and the military's dependence on it for mission critical systems/equipment," writes Arthur R. DeLeon, federal spectrum policy lead for the Department of the Navy, in the Navy publication CHIPS.

Jupiter Research findings show more than 220 million 4G LTE subscribers in 2014 and that number continues to grow. While overcrowding may not be an issue for the Navy while operating on the open seas, problems arise as ships get closer to shore.

A possible solution may lie in frequency management technologies, while another would involve passive surveillance systems. These can monitor very large portions of the wireless spectrum simultaneously with the goal of identifying areas that may be unused.

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