Satellite designers blend commercial and military technology
By J.R. Wilson
U.S. military leaders rely more than ever before on commercially developed satellites and satellite communications, yet continue to pursue unique new military satellite constellations to fulfill their expanding global communications needs.
Communication should not be a constraint" is an age-old premise in military operations, but one that is taking on special meaning in the Bush Administration's push to transform military communications — especially space-based communications as they relate to the overall restructuring of U.S. forces.
Military communications satellite systems fall into three general categories: wideband, narrowband, and protected.
The current primary wideband system, which provides high-capacity communications, is the Defense Satellite Communications System — otherwise known as DSCS. The Ultrahigh-frequency Follow-On (UFO) constellation now fills the narrowband need to support mobile users with voice and low-rate data communications. MILSTAR, short for Military Strategic and Tactical Relay, has been the military's protected system for hardened, covert, antijam satellite communications.
As part of the newly evolving transformational communications architecture (TCA), military leaders plan to replace these systems in the coming decade with the Wideband Gapfiller Satellites (WGS), the Mobile User Objective System (MUOS) for narrowband, and the Advanced Extremely High Frequency (AEHF) system in the protected arena.
In September 2002, defense officials created the joint Transformational Communications Office (TCO) to bring those three programs, among others, and all service components together as a team to develop the TCA as a comprehensive, worldwide architecture of satellites, networks, terminals, as well as ground facilities such as gateways and portals.
Overseeing TCO is U.S. Navy Rear Adm. Rand Fisher, who also serves as director of the National Reconnaissance Office Communications Directorate and commander of the Space & Naval Warfare Systems Command (SPAWAR) Space Field Activity. "We also will be working the processes necessary to synch up all the acquisition programs that will drive the architecture," Fisher says.
Christine Anderson is deputy director of the TCO and the MILSATCOM Joint Program Office. "We have formed a team that involves representatives at the flag and senior executive level across the intelligence community, all the services and NASA," Fisher explains. TCO also works closely with the office of John Stenbit, assistant secretary of defense for command, control, communications and intelligence, who also serves as Department of Defense (DOD) chief information officer. Together, these top officials are developing a global information grid integrated architecture.
New architecture
"The architecture is an operational framework, a system framework, and a technical framework," Fisher explains. "The technology component represents the high-level standards and protocols that will ensure the different elements of the architecture can interoperate. The operational framework is a higher-level view of how the pieces fit together to deliver the capability the architecture must deliver. The systems view is a more granular view depicting each of the pieces.
"We're on track to complete our work in phase one spiral one of the architecture," Fisher continues. "It's not something we will just paste up and not change in the next decade." Program mangers are set to have the first iteration of the TCO architecture ready by late May. Then officials will work their first efforts through joint required operational capability (JROC) and mission review board (MRB), which in the intelligence community is similar to a JROC.
"The satellite systems, presuming the architecture is approved, will start to show up in the 2009-11 timeframe," Fisher says. "When we come forward with the architecture, we will have a better roadmap to guide us in the acquisition. We expect to see some influence early in the ground network terminals, perhaps in the 2007-08 timeframe."
Air Force Brig. Gen. Steve Ferrell, the National Security Space Architect (NSSA), developed the guideposts for the TCO and TCA in a transformational study last year that outlined a joint integrated communications network that includes radio frequency (RF) and laser communications capabilities. The position of NSSA was established in March 1998, replacing the DOD Space Architect post created three years earlier.
Undersecretary of the Air Force Peter Teets says Ferrell's study "confirmed that our baseline program plan would not meet forecast requirements and that we needed to transform our communications architecture. The study also suggested we now have a window of opportunity to provide an architectural framework for a compatible communications system across the Department of Defense and the intelligence community that could increase our capabilities by a factor of 10."
Teets says another important role for TCO is ensuring systems integrators smoothly phase DOD's multibillion-dollar investment in relatively old systems into the new TCA so that the new architecture leaves no one using that equipment behind. This includes the nation's allies throughout the world as they convert from a channelized communications system to a packet-switched system using Internet-style protocols.
Far-reaching program
Fisher says capturing the existing programs and bringing them into the TCA is part of the process, even as it leads to the eventual replacement of existing satellite and ground systems. Existing programs include ones already in process and those systems that connect U.S. forces to allied militaries. TCO leaders also are looking at new communications needs related to homeland security.
"One of the things we've learned since the late '80s and early '90s is that when we have a problem, we don't always have the connectivity, either in terms of access or bandwidth, that we need," Fisher says. "And that applies not only to the DOD segment; you're seeing that as a tremendous effort in the homeland security arena. So one of the things this office is going to try to do is re-vector the road we're on and it will be changed in a sequenced arena in time to allow us to get information from anywhere on the Earth to anywhere on the Earth in a short fashion."
Teets has said that means high bandwidth and easy access for anyone in the national security community who needs it, including the ability to provide streaming video from a Predator unmanned aerial vehicle (UAV) operating anywhere in the world directly to the Pentagon, or information from any U.S. facility to any individual warfighter anywhere on Earth.
That will involve the introduction of new technologies, such as laser communications (lasercom), that have taken part in terrestrial applications but never before in Earth-to-space, air-to-space, or satellite-to-satellite applications to meet the growing demand for capacity.
"If you look at the technology that is conceivably available today, when you introduce lasercom into the equation, you see a picture wherein perhaps the technology would support enough increase in bandwidth that you really can satisfy the needs going forward," Teets says. "I say that with some hesitation, because 10 years from now, chances are the demands will even surpass the capacity at that point in time. But if we can get a factor of 10 on bandwidth and a factor of 10 or even more on accessibility, we will have gone a long way toward satisfying the appetites as we see them developing. The TCO will look at the technology evolution and provide as much bandwidth as we can. We'd like to really, ultimately, eliminate bandwidth as a constraint."
Stenbit calls it adopting and adapting to Information Age technologies by DOD.
"The entry fee to the Information Age is a ubiquitous, secure, robust, trusted, protected, and routinely used wide-bandwidth net populated with the information and information services our forces need," he told the Air Force Communications Agency (AFCA). "It also requires DOD to change its organizational processes and behaviors to move power to the edge.
"Whoever confronts a problem is 'on the edge' whether a leader of a special forces unit thousands of miles from the Pentagon or the secretary of defense working in his office," Stenbit says. " Moving power to the edge is the driving force behind network-centric warfare and the transformation of DOD."
Communications transform
For many of those involved in this transformation, the spark that moved it from theory and discussion to development and implementation was a confluence of 9/11, the resulting global complexities of the war on terrorism, and technology advances that have been moving at warp speed.
"The merger of broadband communications and computing technologies means it is now possible for nearly unlimited quantities of data to flow instantaneously among all mission participants wherever they are located, because they all will be connected to a secure, ubiquitous network of fiber optic cable, RF, and laser links," Stenbit predicts. "Exploiting Information-Age technology will allow us to achieve an agile, fast-reacting network-centric warfare (NCW) capability. This is the capability we need to face the new and widely varying threats of the 21st Century.
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"When we have achieved the transformation to a fully mature NCW capability, mission participants from all the services will be seamlessly connected to the net," Stenbit says. "Moreover, that network will be central to all their operations and behavior, because in NCW, the single greatest contributor to combat power is the network itself."
Fisher sees his new organization as the focal point for identifying the new technologies that can make that happen and how they will fit seamlessly into the transformational communications architecture.
"The optical technologies, including laser communications, might ultimately get down into the photonic arena, allowing very wideband capability," he says. "What we are finding is optical technology, which is a large part of the TCA, is scalable; the same fiber can carry huge amounts of communications, scaling in the tens of gigabits range. RF technologies also are important because they give us the capability to transmit in a very assured domain. The growth in knowledge in software-configurable radios also is very important. Unless the architecture connects, it won't be very useful. The work ongoing in phased-array antennas also is critical. There is a tremendous amount of connective, collaborative hardware and software in the Internet domain that transfers pretty well to space.
"Those technologies will really enable the architecture," Fisher says. "The opportunity for the TCA is afforded by three elements. One of those clearly is technology. You have increases in RF, software-configurable radios, antenna technology, and all of the Internet protocol and web server arenas. All of those combined provide a wonderful opportunity to transform. Our lessons learned from the desert war and 9/11 have given us a resolve and urgency to change the stovepipe system so they interact. All of our [communications] programs need to be recapitalized in the next few years, so we have a window of opportunity afforded by this confluence of technology, programmatics, and urgency to make this a pretty compelling story."
As with many other areas of military technology, much of the satellite-based advancement is coming from commercial developments. Fisher, however, says he believes it will continue to be a two-way street.
"Our intent is to leverage all of the great work being done by the commercial industry and network industry. We're looking for commercial standards and processes. In some areas, we also are investing to meet the demands we have that are different, albeit parallel, to commercial interests. We have some very wideband demands in the optical arena as well as the RF arena that are probably broader than normally seen in the commercial world. In some areas, we are trying to expedite that technology, assessing the technical level of such things as lasercom and encryption, then invest in expediting the maturity of those technologies for military applications," he says.
From DSCS to WGS
With the first satellite launched in 1982, a constellation of 10 Phase III DSCS satellites, orbiting at 22,230 miles above the Earth, has provided high-priority, secure voice and high-rate data S-Band and X-Band command-and-control communications between battlefield commanders and higher command. Each carries six super-high-frequency (7.9 to 8.4 GHz) transponder channels and one single-channel transponder for emergency action and force direction messages to nuclear-capable forces.
The Wideband Gapfiller Satellites that will replace DSCS will bring new technology and tremendous additional capacity. One WGS will provide more capacity than the entire DSCS fleet, supporting a throughput data rate of 2.4 to 3.6 gigabits per second per satellite, depending on the mix of ground terminals using the spacecraft and where they are located. They also will provide X-band and Ka-band coverage, with a digital channelizer and switcher that can key the uplink frequency to match any downlink frequency.
Jointly funded by the Air Force and Army, the WGS contract awarded to Boeing Satellite Systems in El Segundo, Calif., in January 2001 includes options for as many as six Boeing 702 satellites, each with a 14-year design life, and associated spacecraft and payload ground control equipment, along with operational and logistics support and training valued at as much as $1.3 billion.
Boeing has launched a half dozen commercial versions of the 702 satellite since December 1999, including the ANIK F1 for Telesat Canada and the Galaxy IIIC for PanAmSat. Another four are scheduled for 2003, including two Hughes Network Systems Spaceway multimedia satellites. The digital channelizer, developed for those commercial customers, is considered an enabling technology, along with the X-band phased array, for WGS to replace DSCS.
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The WGS constellation will cover 19 independent areas between 65 degrees north and south latitudes. The constellation will include eight steerable/shapable X-band beams formed by separate transmit and receive phased arrays; 10 steerable Ka-band beams served by independently steerable, diplexed gimbaled dish antennas — including three with selectable polarization; and one X-band Earth coverage beam. These enhanced-connectivity capabilities will enable sufficient bandwidth for a full range of voice, data, and graphical communications among users throughout the world. The digital channelizer divides the uplink bandwidth into nearly 1,900 independently routable 2.6 MHz subchannels, covering several different user systems, including X-to-Ka and Ka-to-X crossbanding, multicast and broadcast services, and flexible uplink spectrum monitoring capability for network control.
Xenon-ion propulsion
The satellite itself also employs technology advancements, including a xenon-ion propulsion system (XIPS), triple-junction gallium arsenide solar cells and deployable radiators with flexible heat pipes. XIPS is 10 times more efficient than conventional bipropellant systems. Four 25-centimeter thrusters from produced by Boeing Electron Dynamic Devices in El Segundo, Calif., remove orbit eccentricity during transfer orbit operations. These thrusters are for orbit maintenance and to perform station change maneuvers as required throughout the mission life. The substantially large radiator area provides a cool, stable thermal environment for bus and payload, which Boeing officials say will increase component reliability and reduce performance variations over the spacecraft's service life.
The satellite's Ka-band antenna subsystem and system engineering support for satellite-to-ground terminal interface verification are from Harris Corp. of Melbourne, Fla. ITT Industries in White Plains, N.Y., will develop and integrate the WGS payload command-and-control element for installation within the Army's global network of Wideband Satellite Operations Centers (WSOCs). Northrop Grumman Information Technology in Herndon, Va., is supplying wideband satellite communications network planning software and SAIC is supporting the overall satellite communications systems engineering effort.
WGS also is unique in terms of program management, with all of the contractor team and the Air Force program office co-located at Boeing's El Segundo facility, which Boeing Air Force programs director John Peterson says has greatly improved the communication and decision-making process and helped keep the program on track.
The WGS passed its critical design review (CDR) last year and is scheduled to go into integration and test later this year, with first launch planned for late summer or early fall of 2004. Follow-on launches are expected about every six months, with the last of the three now planned for mid-2005.
"Because it is compatible with the DSCS format, it will provide the same universal compatibility with NATO terminals that DSCS does," Peterson says. "It provides the kind of communications the warfighter needs for inter- and intra-theater, as well as back to CONUS."
That will include the current generation of Ku-band unmanned aerial vehicle (UAV) terminals and the anticipated move to Ka-band for future UAV terminals.
"One advantage on the ground [of Ka] Is the terminals are smaller and more mobile due to the higher frequency and require a smaller antenna," notes Richard Johnson, the Boeing WGS program manager. "Typically, the higher the frequency, the more problems you have with respect to blockage, so you always want to go to lower frequencies with ground clutter, so you would go to the X-band side in those circumstances.
"Having Ka-band provides additional capacity in X-band, because the demand on it will not be as heavy as it currently is because some communications will migrate to Ka," Johnson continues. "Ka also is for growth capability beyond what X-band can support. So when we look at the utilization forecast for DSCS and WGS, we are predicting significant growth, which is one of the reasons for deploying this system."
The DSCS constellation has been supplemented in recent years with four Service Life Enhancement Program (SLEP) satellites, the last of which is scheduled for launch in mid-2003 to complete the DSCS fly-out. Those satellites will continue to operate alongside the WGS system at least through the end of this decade.
"While we're on contract for three spacecraft, we have options for three additional spacecraft and are continuing to work with the Air Force to find additional mission capabilities we could put on those to help continue in the direction of the TCA," Peterson says. "Those are additional options the Air Force could exercise to provide additional capability or as spares. In addition, with four spacecraft, we would provide full global coverage, including CONUS [which currently is not covered] and it could be used for homeland defense."
He says Boeing officials hope to come to an agreement on those options soon to avoid a break in production, which would make any additional orders more expensive.
MUOS Supplants UFO
The primary providers of military UHF satellite communications today are the Navy's Ultra High frequency Follow-On constellation and the older Fleet Satellite (FLTSAT) system. Supplementing these are commercial L-band communications at sea from the Intelligence Satellite (INTELSAT) and International Maritime Satellite (INMARSAT).
Initially launched in 1993, the eight satellites in the UFO constellation operate in the general range of 290-320 MHz uplink and 240-270 MHz downlink, frequencies well-suited for low-cost, low power, portable radios that reliably penetrate severe environments and offer assured access and netted communication. Each satellite contains 38 UHF communication channels (at 5 and 25 kilohertz) plus one additional 25-kilohertz channel for Fleet Broadcast and for narrowband tactical satellite communications to Joint Forces and coalition partners.
In March 1996, Navy officials ordered a high-power, high-speed Global Broadcast Service payload for UFO satellites F8 through F10, replacing the UFO's super high-frequency X-band payload with four 130-watt military Ka-band transponders derived from commercial satellite development. GBS added high-speed digital communications at data rates as fast as 30 megabits per second (Mb/s) per transponder.
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The last UHF Follow-On satellite, F11, is a gapfiller scheduled to be launched in early fall 2003 to prevent UHF availability from dropping below an acceptable level. In the interim until MUOS is in place, about 25 percent of tactical UHF communications will offload to commercial mobile satellite services.
According to the Communications Satellite Program Office at SPAWAR, the demand for UHF communications has led to a proliferation of UHF terminals on practically every type of military aircraft, submarine, warship, tank, and truck, with more than 7,500 terminals in use today and significantly more anticipated in the next few years. As many as 82,000 narrowband satellite communications terminals of all types are to be in use by 2010. About half of those will be handheld Combat Survivor Evader Locator units, the remainder predominately legacy and advanced Joint Tactical Radio System (JTRS) terminals. Commercial systems already in place indicate that one satellite of the MUOS type could service more than 10,000 low-rate data handheld terminals.
Bandwidth issues
The size and quantity of data transmitted also is on the rise and is choking the capabilities of the decade-old UFO systems. A 1 megabyte air tasking order can take as long as an hour to transmit at the 2.4 kilobits per second rate of UFO, but could flash from sender to receiver in less than a second using current technology. Given the 2010 Combined Major Theaters of War requirement is about 42 megabits per second with more than 2,300 simultaneous accesses, the need is rapidly becoming critical.
The Mobile User Objective System, scheduled for IOC in 2007 and full operational capability no later than 2013, will provide global narrowband (64 kilobits per second and slower) satellite connectivity for voice, video, and data for U.S. and allied services using a constellation of three geosynchronous satellites. Requirements for MUOS include the ability to penetrate two layers of jungle canopy and communicate during extreme weather conditions.
In September 2002, Lockheed Martin Space Systems, Missiles & Space Operations in Sunnyvale, Calif., and Raytheon Systems Co. in St. Petersburg, Fla., won $40 million contracts for the MUOS component advanced development (CAD) phase, to be completed by November 2003. Lockheed Martin is teamed with General Dynamics Decision Systems in Scottsdale, Ariz., and with Boeing Satellite Systems; Raytheon is teamed with Space Systems Loral in Palo Alto, Calif. The CAD phase is preamble to a 2004 System Design and Development competition, leading to a MUOS Program Production and Deployment contract award from SPAWAR in 2006.
"MUOS is aimed at narrow-band connectivity, primarily in the UHF frequency range, and will provide mobile users with wide global connectivity," Fisher says. "We intend to connect MUOS to the transformational architecture via the ground system, teleports, and gateways. The simple vision is to connect worldwide any set of users to any other set of users and we want that to be transparent to them."
From MILSTAR to AEHF
The first MILSTAR (Military Strategic and Tactical Relay) satellite launched in February 1994. After the first two satellites, a Block 2 design gave up heavy and expensive nuclear hardening for a secure satellite-to-satellite crosslinking capability that allows one fixed or mobile station to control the entire constellation. Using frequencies that the Earth's atmosphere absorbs, the crosslink operations cannot be detected by ground stations. The Block 2 spacecraft provide low-rate data 75 to 2,400 bits per second of voice/data across 192 EHF channels and a medium-rate data capability of 4,800 bits per second to 1.544 Mb/s over 32 channels.
Key to the MILSTAR system is the interoperability of terminals. This enables sea-based terminals aboard submarines, cruisers, and destroyers to upload new data onto cruise missiles in real time. Land-based terminals, such as the Several Channel Anti-Jam Man-Portable (SCAMP) and the Secure Mobile Anti-Jam Reliable Tactical Terminal (SMART-T), provide communications and data exchange for mobile, ground-based warfighters.
With MILSTAR 3 lost in 1999 and the final Block 2 satellite MILSTAR 6 launched this year, the need for a full-strength successor has become urgent. That successor is the Advanced Extremely High Frequency System, with a system development and demonstration phase contract for three satellites and associated ground command-and-control elements awarded to a Lockheed Martin Space Systems and TRW Space and Electronics team in November 2001.
How that program plays out is yet to be determined as TCO officials consider their options. According to the MILSATCOM JPO, other protected military satellite communications options are being considered under DOD's transformational initiatives, but if those options do not lead to full operational capability by 2010, then the original program to acquire four AEHF satellites plus one spare will be restored.
Teets says that decision must be made by December 2004; Fisher says he hopes to have enough information to act on even sooner.
Fast data throughput
While AEHF will be compatible with MILSTAR and with the systems of allied forces, each satellite will have as much as 12 times the total throughput of MILSTAR, with single-user data rates as fast as 8 megabits per second. In addition, user access will have nearly a tenfold increase in the number of spot beams, which will focus power to improve reliability and data rates to small and large terminals and to minimize the potential for enemy interception and interference. The AEHF satellites also will support twice as many tactical networks as MILSTAR and will mimic MILSTAR's secured satellite crosslinking capability, but with several times the current data rate.
Driving the 2010 deadline for full operational capability are projections the Army, Navy, Air Force, and Marines will have some 2,500 protected communications terminals in their inventories by then to support ground units, aircraft, surface ships, and submarines. Those will include the Family of Advanced Beyond line-of-sight Terminals (FAB-T), SCAMP, SMART-T the and Submarine High Data Rate (Sub HDR) system. FAB-T combines two previous programs the Airborne Wideband Terminal and Command Post Terminal Replacement to create a family of terminals with a common open architecture for airborne and ground applications.
A dedicated mission control segment will comprise communications management, mobile command-and-control centers, Satellite Ground Link Standard/Unified S-Band (SGLS/U.S.B) satellite control, and EHF in-band satellite control.
The next step
DOD officials say they believe the next major advance in military satellite communications will involve the adaptation of lasers, but Teets acknowledges that will require further technology development, a better understanding of the probable timeline for demonstrating satellite-ground capability, and a thorough risk-reduction activity before it will be possible to migrate toward a space-based lasercom capability. The timing on all that also will influence decisions regarding the Advanced Extremely High Frequency System.
Teets says as much of that work as possible will be done in the next two years, spurred by the December 2004 AEHF decision deadline. If by that time there is sufficient confidence in the technology, officials may decide not to procure AEHF satellites 4 and 5 and instead rely on a new high-bandwidth relay network using some form of lasercom.
"We have a number of on-ramps and off-ramps already planned, based on the kind of the current vectors for the programs," Fisher adds. "And we'll be assessing a number of technologies — lasercom is just one of them — looking to meet those thresholds. If we meet them, that would be a positive indicator for one of these gates. If we don't, then we would have to go in a different direction. And as you can imagine, with the number of moving parts we've got, that's a fairly complex road map."
Tim Malac, director of aerospace systems business development for Harris Government Communications Systems Division in Melbourne, Fla., says lasercom is critical to meet the growing demands of military communications, which already are pushing the limits of available RF and microwave frequencies.
"The key benefits of lasercom are greatly increased bandwidth — 5 to 10 gigabits per second, rather than 5 to 10 megabits, which is a huge increase in capacity unlicensed spectrum (no need to acquire a license to operate in another country), covertness (RF energy goes everywhere, where a laser is a highly concentrated pinpoint) and using multiple lightbeams to talk point-to-multipoint," he says. "A satellite would need to be able to point and track to multiple users in the air and on the ground at the same time, an ad hoc mobile network, with some mobile users coming in and out of the network.
"A lot of companies have bits and pieces of it and the basic technologies exist, but some of the more challenging pieces are dealing with dispersion of the light, acquisition, pointing, and tracking on moving platforms. It's not just a laser link, either, but a whole network," Malac says.
Lasercom is key
Frank Prautzsch, business development director for Raytheon Integrated Communications Systems in Marlborough, Mass., says lasercom is likely to play a key role in the future of what he terms a "concentric set of rings regarding military satellites."
The hardcore center requirement is to maintain assured, protected communications capability for strategic command and control for whatever threat or continuum of operations is in progress, Prautzsch explains. The second ring involves commercially procured satellites that allow for the development of COTS-based spacecraft, but that are operated and maintained by the military. The third ring involves pure commercial augmentation services to provide adequate capacity protection and mobility to meet all requirements at all times.
Intertwined with those three rings are four basic communications layers exoatmospheric (spacecraft), aerospace (air-breathing, including UAVs), ground environment, and sea and sub-surface environment — each of which has a network of networks, vertically and horizontally, he adds.
"Each has a user set or cascading effect, depending on the military's need for a mission," Prautzsch explains. "There are some new things tied to the TCA, such as lasercom, that are very visionary that will play out as a defense need, but will find commercial applications over time. Lasercom is crucial to the TCA; the military is pushing the vision and the need for integration in supporting mission requirements.
"The right place at the right time with the right thing is the key that takes you from information dominance into knowledge dominance," Prautzsch continues. "There is no hard cut-over date. I would say 2010 is probably a good target for the first critical assemblages, but in order to address that direction, you have to start looking at investments and opportunities now, then grow and evolve over time to address that. Technology doesn't stay put, nor do requirements."
Critical technologies are emerging in a variety of areas, not only lasercom but also such elements as phased arrays, high-capacity services and networks, advanced power systems, and microminiaturization.
New technologies
"These new technologies are critical, such as electronically steered phased array antennas, which are being used on both WGS and AEHF to provide the ability to put high-gain spot beams on the Earth and move them around to wherever the user is, so you can focus on an area of interest," Malac notes.
"Another key part of those types of satellites is onboard processing. A traditional satellite uses a bent-pipe approach; you send up a signal, the satellite converts it to a slightly different frequency and sends it back down, with no processing, just a simple shift in RF," Malac says. "Virtually all commercial C and Ku-band satellites in geosynchronous orbit use that. Military satellites, with onboard processing, allow for much more robust capability and flexibility; satellite-to-satellite networking will require even more onboard processing and algorithms, on the spacecraft and on the ground."
Development of these technologies often involves commercial lasers and onboard processing with high-end military requirements. Others, such as phased-array antennas, are primarily military, with little commercial need.
The commercial world also has led the movement to using Internet protocols (IP) over satellite systems, which will be key to making network-centric warfare a reality.
"The entire architecture changes when you move from circuit- or channel-based, carrying a trunk group, to IP-based, where everything is burst-based," explains Rick VanderMeulen, director of wideband systems for ViaSat Inc. in Carlsbad, Calif. "Architecturally, we're still talking about the same kind of electronics, like FPGAs, but configured to do things in a burst fashion. So it's not a new fundamental science, but new protocols.
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"Speed doesn't make as much sense when you talk about IP when you are connected on a DSL line, service is better than a modem, so speed is important," VanderMeulen continues. "But in IP, you don't measure speed the way you do with telephony. Instead, you talk about how many packets you can burst per second. So if you want to fill up a 100 Base-T Ethernet LAN, you have to burst thousands of packets per second. Your quality of service will depend on how many packets you can send per second and balancing the channel priorities."
Measuring quality
Another major difference is how quality of service is measured. With telephony, blockage is measured in terms of how often you encounter a busy signal, how long you are connected and how often the signal is dropped from all elements of the physical connection, not what is going over that connection. With an IP-based service, the key is the application being used, because each application will have its own packet numbers and rates and delivery.
"So being IP-based has caused us to look inside the applications for the first time and not just at the connectivity," Malac says, adding that raises yet another important difference between the commercial and military worlds. "The real issue with the military has to do with the fact they have to be very conservative. The rest of the world went from Windows to Windows 95 to Windows 98 to Windows 2000 to Windows XP in only eight years. The government would not have wanted to jump to all these network applications until the technology was standardized.
"So there have been standards issues, cost issues, technology issues. I think those are now being resolved and the majority of the world believes IP has become a fairly stable standard," Malac continues. "As such, the military leadership is saying, 'Let's go there if we start to convert our systems to IP-based applications, five years from now, when those are fielded, IP will still be there, it won't have gone away'."
At other times, Malac says, the military has been the most far-sighted in considering new possibilities, but has relied on the commercial world to bring it to reality.
"If you go back to the mid-1980s, no one in the commercial world was thinking about cell phones. Only the military was really thinking about working off the infrastructure. Now, of course, the commercial world is heavily invested in off-infrastructure and high-speed Internet access," he notes. "A decade ago, the only ones trying to put offices into remote areas were the military and maybe somebody trying to drill an oil well. Now you have an entire commercial sector pushing that state of the art."
That does not mean the military can simply sign on as a customer for commercial services, no matter how ubiquitous or affordable, because the requirements for assured availability, security, reliability, and survivability remain paramount. But some basic parallel requirements feed the dual-development engine; a civilian airline passenger who wants to surf the Internet in real time while in flight has the same basic need as a fighter pilot who needs to download new target data en-route. Neither user cares how he acquires the information, only that it is always available.
"The goal is an end-to-end system that is transparent to the user, whether the signal comes over land or satellite, with equal quality, whether the system is congested or uncongested," Malac says. "So there are a lot of trends. The biggest of those is the move to IP standards."
Once all of these systems are in place, a total of 28 military communications satellites across six families (MILSTAR, DSCS, NATO III/IV, Skynet 4, AEHF and WGS) will come under the Command and Control System-Consolidated (CCS-C), which will employ state-of-the-art commercial telemetry, tracking and control (TT&C) technology. The MILSATCOM JPO says CCS-C will provide the 3rd and 4th Satellite Operations Squadrons (SOPS) of the 50th Space Wing, 14th Air Force, with a modern, flexible and operationally streamlined system to replace functionality currently provided by the 20-year-old Command and Control Segment (CCS).
