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home > November/December, 2007 issue > article
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| Photography by Rick Steele |
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| Dan Fraley Jr., chief technology officer at Hughes Network Systems, said spot-beam technology “can ultimately be deployed down to the smallest tactical level and mounted on tanks, Humvees and other vehicles.” |
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Wireless comms: change is in the air
By Peter A. Buxbaum
Special to Defense Systems
Forthcoming satellite program should give warfighters a much-needed boost in bandwidth
When military leaders first conceived the wideband gap-filler satellite constellation in the late 1990s, they were seeking a way to give warfighters a boost in high-speed communications while the Defense Department made the transition from the aging Defense Satellite Communications System to the incipient Transformational Satellite Communications System.
DOD studies at the time found that the demand for wideband communications would exceed DSCS’ capacity before the military could get TSAT off the ground — creating the need for a gap filler.
Earlier this year, DOD renamed the program the Wideband Global Satcom to signify its emerging role as an important independent satellite communications system.
“WGS started out in 1997 as a shorter-term solution to plug that gap,” said Col. Donald Robbins, WGS program manager at the Air Force Space and Missile Systems Center at the Los Angeles Air Force Base. “In the last few years, we realized that WGS did not just fill a gap but provided a long-term solution as well.”
Several factors converged to give WGS its new prominence, including significant delays in the TSAT program. At one time, DOD had hoped to deploy TSAT as early as 2009, but that deployment appears to be unlikely before 2019 because of evolving requirements. Therefore, a gap filler system would not be sufficient.
Another factor was the need to reduce reliance on commercial systems. The primary gap filler in recent years has been the Ku band, the portion of the spectrum generally used for satellite TV and other civilian applications. As operations ramped up in Iraq and Afghanistan, the military increasingly turned to leased commercial satellite capacity for in-theater communications. WGS would reduce the military’s reliance on commercial bandwidth — and its $1 billion annual cost.
In addition, DOD’s current satellite fleet is aging and running out of fuel.
“We need to replace our space assets in total over the next 12 years,” said Air Force Secretary Michael Wynne at a recent symposium on military modernization held in Washington. “We have developed a way to rendezvous with and refuel satellites — maybe — but refuelable satellites are not up there now.” The Air Force, which manages most U.S. military space assets, is spending $20 billion per year to replace its satellite constellation, Wynne said.
Change is in the air
WGS will have a wide effect by providing a boost to a number of major military communications systems now in the field.
The WGS constellation will supplement and eventually replace the two-way military X band — which operates at 7 GHz to 8 GHz — communications capability provided by DSCS. The new high-capacity two-way Ka-band will provide mobile and tactical personnel with data rates as fast as 3.6 gigabits/sec. The Joint Network Node, an Army program that provides IP-based communications at the tactical level, will use WGS to provide mobile communications capabilities to U.S. forces in the Middle East.
WGS also will replace the one-way communications on the Ka band — of 20 GHz to 21 GHz — frequency now used by the Global Broadcast System via Navy satellites, enabling GBS to serve a greater number of concurrent users.
The first WGS satellite was launched Oct. 9. Four more are scheduled to be launched by 2012, with another five launches possible in the future.
Once the first satellite’s capacity is tested and brought online, probably in April 2008, warfighters will benefit immediately, Robbins said.
The total increase in bandwidth will be dramatic, with a single WGS satellite providing 10 times the bandwidth of a DSCS counterpart — which essentially equals the capacity of the entire DSCS constellation.
“DSCS is now the backbone for military wideband communications,” Robbins said. “Communications over the WGS satellite will produce a marked improvement in the transmission of large datasets. This is a capability the warfighter does not have now.”
For example, the WGS satellite can transmit images from unmanned aerial vehicles hovering over Baghdad neighborhoods to U.S. warfighters seeking to root out insurgents.
“If I’m a soldier in Baghdad in an urban setting, I need to understand the situation and to call in whatever weapons are required to win the encounter,” said Mark Spiwack, wideband global satellite communications program director at Boeing Satellite Systems, the prime contractor for WGS. “The ability to locate where the bad guys are will enable the warfighter to communicate with the different services to call in the right assets.”
A flexible solution
Also, WGS offers more capacity and more flexibility, and that combination is crucial, Spiwak said.
“The increased throughput allows for the tailoring of bandwidth easily and quickly to the needs of individual units,” he said. “The digital signal processor router is the brain behind the capability and is the key to its flexibility. It functions like a switchboard in the sky and allows flexible communications between the X-band and Ka-band frequencies.” The capabilities offered by WGS are made possible by several other technological innovations. For example, WGS builds on a new generation of spectrum monitoring equipment to ensure the smooth flow of traffic despite the increased complexity that comes with using the digital router.
WGS also exploits spot-beam technology and small-aperture antennas to smooth communications for troops as they move from one place to the next.
Spot-beam technology sends concentrated bandwidth to specific geographic locations and allows satellites to reuse the same frequency in different locations. Ku-band-based communications do
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| Photography by Stephanie Diani/WPN |
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| Col. Donald Robbins, Wideband Global Satcom program manager at the Air Force Space and Missile Systems Center, said, “in the last few years, we realized that WGS did not just fill a gap but provided a long-term solution as well.” |
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not offer that capability.
The WGS design includes 19 independent coverage areas. Ten Ka-band and eight X-band spot beams can be positioned anywhere in the field of view of each satellite, with full-Earth coverage in the X band also available. Using phased-array technology allows the eight X-band beams to be steered and shaped to apply power where it is needed.
Communications between users is enhanced by using a digital channelizer, which allows for efficient use of a satellite’s bandwidth. It divides the uplink bandwidth into nearly 1,900 independently routable subchannels, providing the connection from any uplink coverage area to any downlink coverage area.
“Small-aperture antennas fully support spot-beam technology,” said Dan Fraley Jr., chief technology officer at Hughes Network Systems, a provider of commercial satellite services. “This can ultimately be deployed down to the smallest tactical level and mounted on tanks, Strykers, Humvees and other vehicles. The very-small aperture lowers the vehicle’s physical profile as a target on the battlefield.”
Something for everyone
Robbins said that as a joint program, the WGS program office supports the hardware needs of U.S. military services. “We work closely with all of the services to understand their requirements.
We have issued a series of documents which allows them to build terminals that will communicate with the wideband platform.”
The Air Force’s Military Satellite Communications program also supports the testing and integration into the wideband environment of communications hardware developed for the other services. “We are all tightly integrated in a joint environment,” Robbins said.
Also, the Army’s Warfighter Information Network-Tactical network will likely use WGS to provide persistent bandwidth to tactical units in Iraq and Afghanistan.
WIN-T, conceived as the Army’s tactical intranet, was recently restructured to incorporate the Joint Network Node-Network (JNN-N) into the program as Increment 1. With Increment 1 already available, WIN-T is providing a communications and information infrastructure to U.S. forces in Iraq and Afghanistan.
“The idea behind JNN-N was to use commercially available technologies to provide beyond-line-of-sight capabilities to the operational force,” said Col. William Hoppe, WIN-T project manager at Fort Monmouth, N.J. The key enhancement with JNN was to provide an IP standard for transmitting both voice and data in the Army. “JNN offers pretty good throughput,” Hoppe said.
The WIN-T program plans on plugging into WGS.
“We are posturing to take advantage of the constellation once it is active,” Hoppe said. This will involve switching from the commercial Ku band and providing warfighters with a newly configured satellite dish. That effort is the subject of a competitive-bidding process.
WGS will also provide a new home for the military’s GBS, a satellite-based system that uses commercial technologies to provide imagery and video feeds to the field. GBS, sometimes called DirecTV for the warfighter, operates via Ka-band transponders on the Navy’s UHF Follow-On satellites and via Ku-band transponders on leased commercial satellites.
GBS originated in the aftermath of the 1991 Gulf War, when the military experienced problems broadcasting imagery to the desert. After the war, DOD initiated a pilot project. The first contract, awarded in 1997, focused on developing transmission and receiving hardware and software and information management processes. In 2002, a second phase of GBS started, dealing primarily with transplanting older communications modes with IP technologies.
The IP upgrades will enable GBS users to pass information through WGS, which will enable more troops to use GBS simultaneously.
A broad horizon
Clearly, WGS is no longer a gap-filler program. Its five satellites will be fully operational by 2013, Robbins said, and present plans call for the system to be used through 2030, and perhaps beyond that.
“There are a number of programs that are looking at how to use WGS,” he said. “This is the first brand-new family of communications satellites in 10 years, and we believe it will be viable well into the future.” Robbins added that plans are already being worked on to procure as many as five additional WGS satellites.
Meanwhile, WGS will be working concurrently with DSCS, but eventually the older satellite system will have to be retired. “DSCS has been up there for a while,” Robbins said. “We in the military like to get every possible use out of our systems, but eventually DSCS will have to go away.” In addition, TSAT, the original endpoint for the wideband satellite effort, is undergoing changes. “It looks like it keeps on getting modified as requirements change,” Downey said. “The best that can be said is that it is something under development.” Bruce Elbert, president of Application Technology Strategy, said he thinks that TSAT, once launched, will focus on protected communications and the communications needs of specific and specialized platforms, such as nuclear submarines, and applications such as homeland security.
In some ways, WGS has emerged as an independent transformational capability, Downey said. “WGS supports multiple bands where previous satellites supported only one. It has a more flexible payload and is able to route communications more flexibly than previous satellite constellations. The sheer communications capacity on the WGS satellites overshadows the capacity of the previous generation.”
That is why Downey concludes that the “WGS satellite is the workhorse satellite system for the foreseeable future.”
The first WGS satellite has already been launched but not yet deployed. It takes about 100 days to get the satellite into its orbit, Spiwack said, and a total of six months for the Air Force to complete its testing before the satellite’s capacity comes on line.
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