Satellite System Adds to Capabilities Menu

July 1, 2013
By Rita Boland

On-the-move communications go digital for 
troops in regular or disadvantaged locations. 

Personnel work on a Mobile User Objective System (MUOS) satellite to prepare it before it launches into space. When complete, the MUOS constellation will have four active geosynchronous satellites and one on-orbit spare.

Military users of narrowband communications worldwide will have a range of upgraded capabilities once a new satellite constellation takes full flight. The second satellite in the set is scheduled for launch this month, meaning that soon half the globe will be covered by the enhanced services. When the system reaches full operational capability in 2015, it will include four active geosynchronous satellites and one on-orbit spare.

The Mobile User Objective System (MUOS) is a third-generation network that will provide cellphone-type capabilities to units on the move. However, it requires specifically designed equipment on the ground to tap into the services; it does not play into any military bring your own device initiatives. MUOS will employ both legacy ultrahigh frequency (UHF), or narrowband, satellite communications (SATCOM) payloads and digital Wideband Code Division Multiple Access (WCDMA) payloads. The arrangement allows the system to support legacy terminals and Joint Tactical Radio System-compatible terminals. The commercial third generation WCDMA cellular phone network architecture combines with the geosynchronous satellites in place of cell towers. It offers a 16-fold increase in transmission throughput over the former UHF offerings. The WCDMA waveform gives troops more capability in stressed environments such as urban canyon or double canopy jungle.

Compared to MUOS’s predecessor—the UHF Follow-On (UFO) constellation—the new system offers a 10-fold increase in capacity, allowing more users to access the communications. They also have access to higher data rates and the Global Information Grid. Troops can connect to both the nonsecure Internet protocol router network and the secret Internet protocol router network for secure communications. As the UFO reaches the end of its useful lifecycle, MUOS can transition smoothly to take over its load and offer digital upgrades.

MUOS is Internet-protocol based, primarily designed to carry voice and data communications. Because it uses narrowband rates, video transmissions will not be the norm. Imagery, chat, positioning and similar data will be more common. On-the-move data rates will reach speeds of up to 384 kilobits per second, but standard rates will be slower.

Along with the satellites that make up the constellation, the larger system includes four ground communications systems in Hawaii, Italy, Australia and Virginia. Each satellite will communicate with two ground stations, and each ground station will communicate with two satellites for redundancy. According to the Navy, these “ground sites are interconnected to switching and network management facilities located in Hawaii and Virginia. These facilities identify the destination of the communications and route the information to the appropriate ground site for Ka-band uplink to the satellite and UHF WCDMA downlink to the correct users.”

The satellites are scheduled to go up one per year each July until the constellation is complete. They launch aboard evolved expendable launch vehicles from Cape Canaveral, Florida. MUOS additionally has a ground control and network management system. The ground portion handles the transport, network management, satellite control and associated infrastructure to fly the birds and manage users’ communications, according to the Navy.

Once the second satellite—MUOS-2—launches, project personnel will conduct a full end-to-end testing of the WCDMA waveform. When the operational test and evaluation, or OT&E, is complete, those services will be available to troops. Legacy services already are in use. After satellites are launched, Lockheed Martin—the main contractor working on the project—typically takes three to four months to complete on-orbit test and verifications and then hand them over to customers. That time ensures the satellite operates correctly before it is tested by an independent government agency and commissioned into service.

The launches of the third and fourth satellites will not increase capabilities. “The additional satellites simply add more coverage,” says Cmdr. Patrick Hanrahan, USN, narrowband SATCOM requirements officer in the U.S. Navy’s N2/N6 Communications and Networks Division. The Navy is the lead for MUOS, though the capabilities will be available to all military branches. The U.S. Army is expected to employ the capabilities most often. The Navy’s Program Executive Office for Space Systems and its Communications Satellite Program Office are responsible for the MUOS program. The U.S. Strategic Command is the operational user, which includes tasks such as deciding where to position each satellite. MUOS-1 is stationed over the Pacific Ocean and connects to the ground stations in Hawaii and Australia.

Iris Bombelyn, vice president of Narrowband Communications at Lockheed Martin Space Systems, says that where the existing satellite system covers a large area with one beam, MUOS covers the same space with 16 beams. The arrangement allows for greater control and makes signals more available to users regardless of their location, she says. The WCDMA capability provides an added benefit over the existing system. Users in places where signal multipathing is an issue are better able to connect via the MUOS ground system and terminals, which combine multipath signals for a more reliable link. Thus, communications are enabled even without establishing line of sight. “One reason why it’s kind of a game changer for fighters in the field is that they never have to come out of cover now to be able to get a satellite and send a signal,” Bombelyn explains. That benefit comes both from the way the frequency band combines the signals and from the global coverage the constellation offers.

The new waveform also enables administrators to set up users on the fly without dedicating lines to terminals. They can assign priorities and data rates as appropriate, modifying as necessary. Bombelyn believes that will make a big difference in the government’s ability to use the capacity it has. For example, texting requires hardly any bits, so network managers can reallocate data from users needing that capability to other units that need to send images. Another example involves a remote team out in the field, capturing images of important targets. In the past the team would be limited largely to voice communications until it returned to a point with more robust capabilities. With MUOS, warfighters can immediately send the data to others who need it.

MUOS is designed to support a mixed terminal population. How the various services employ the system will be up to each branch individually. The Navy, which has been using UHF SATCOM at the tactical unit level since the 1970s, plans to outfit all its ships and submarines with terminals for the system. Sailors also are looking into aviation terminals. General Dynamics developed the two-channel AN/PRC-155 Manpack radio that completed successful tests with secure radio-to-radio voice and data communications through MUOS, the first off-the-shelf radio to demonstrate such capability. The Army’s 4th Brigade Combat Team, 10th Mountain Division, has the Manpacks now, and Cmdr. Hanrahan says the Navy is buying some of them as well. He adds that sailors also are considering upgrading other terminals such as the Digital Modular Radio to support MUOS.

Lockheed Martin and the Navy have had discussions to determine if the U.S. government has interest in providing some of the capabilities of MUOS to allies. Bombelyn says features such as beyond-line-of-sight communications offer huge advantages others could benefit from having. Countries procuring the F-35 also could have particular interest in procuring access to the system. “We have an entirely separate set of frequencies the Navy has reserved that would allow us to put up another four satellites to provide double the capability for the first MUOS system,” Bombelyn explains. “And if [the military] wanted to provide that capability to our allies, then we would be more than happy to build this second set of MUOS satellites.” Groups such as nongovernmental organizations should never need the system’s capabilities because several faster, unsecure communications waveforms already are available.


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