The Challenge of Shared Military Communications

Mak King and Malina M. Hills

European military satellite communication technologies have never reached the level of their U.S. counterparts—and the gulf appears to be widening. As a result, the United States and its allies will have to work harder to share military communications and coordinate front-line operations.

Recent world events have highlighted the importance of coordinated action between the United States and its primary allies in achieving common military and political objectives. Central to improved coordination is the free flow of information, and military planners have come to rely on military satellite communications (milsatcom) to provide the needed services; however, the level of U.S. funding for milsatcom projects and the advances made by the U.S. communications industry have created a technology gap that could itself hinder the flow of information during allied military campaigns. As the British journal The Economist reported in June 2001, "With more than $1 billion a day to spend, the Pentagon's budget dwarfs those of any of America's allies or antagonists. Expenditure on defense research alone is four times the combined European total. America's lead in the use of sensors and telecoms is so wide, and growing, that one of its biggest problems is stooping low enough to fight alongside its crudely armed allies."

Skynet 2, the first European-built milsatcom system, marked a turning point in the history of European milsatcom. From then on, the desire for indigenous national space systems, combined with limited budgets and expertise, drove Europe away from interoperability with U.S. milsatcom systems.

Milsatcom is not cheap. Since the end of the Cold War, new and emerging milsatcom programs have felt the same budget pressures as all other military procurements. As a result, procurement schedules have slipped, and systems have been redefined to accommodate budget restrictions. Nonetheless, progress in the United States has been steady, albeit slower than originally anticipated. On the other hand, the milsatcom systems of major European allies have lagged behind. A looming gulf in relative capability may make front-line communications between U.S. and allied forces nearly impossible. The importance of this observation is itself controversial; not all European allies believe front-line "shooter-to-shooter" communication is necessary or even desirable. Their alternative viewpoint is that headquarters-to- headquarters communication is adequate and more appropriate.

In spite of this controversy—or possibly because of it—the United States has pushed for international agreements in hopes of facilitating future interoperability of allied milsatcom systems. These efforts have taken the forms of direct technical negotiations, attempts to gain acceptance of U.S. waveforms as NATO (North Atlantic Treaty Organization) standards, and more recently, bilateral and multilateral negotiations for the joint development of future milsatcom systems.

The Birth of European Milsatcom

The first European milsatcom systems were actually built by the United States, which invited certain allies to participate in the Initial Defense Communication Satellite Program (IDCSP), begun in the mid-1960s. The program provided relatively narrow-bandwidth transponder service in the X-band (7.2–8.4 gigahertz) from a spin-stabilized platform. In 1969, the United States launched an augmented version of the IDCSP system for the United Kingdom, called Skynet. NATO also undertook operation of two IDCSP satellites, followed by two more in 1970 and 1971. (See milsatcom timeline, page 56.) All of these U.S.-built systems were fully interoperable with IDCSP, communicating to both land-based and shipborne terminals.

During the 1970s, the United States replaced IDCSP with the Defense Satellite Communications System (DSCS) program, which provided wider-bandwidth channels as well as a higher-power payload. A parallel evolution occurred in the U.S.-built NATO II satellites, which also operated at higher powers and wider bandwidths. Separately, the British government developed the Skynet 2 satellites, which incorporated a higher-power payload while maintaining the narrower bandwidth of the first Skynet. The Skynet 2 system was the first European-built milsatcom system (with U.S. assistance on the payload), and it marked a turning point in the history of European milsatcom. From then on, the desire for indigenous national space systems, combined with limited budgets and expertise, drove European countries away from interoperability with U.S. milsatcom systems.

The French Telecom communication satellites hosted the Syracuse payloads, built by the French Ministry of Defense. In Europe, such ventures combining government and commercial funding and management are not uncommon. The Telecom program was directed and operated by the French national telecommunications agency.

While Europe remained committed to these spin-stabilized, low-capacity superhigh-frequency (SHF) milsatcom systems through the 1970s and most of the 1980s, the United States fielded an enhanced array of milsatcom systems. For example, U.S. advances in satellite bus technology led to the development of three-axis-stabilized spacecraft, which greatly facilitated improvements in many system applications. The U.S. Navy embarked upon a series of milsatcom developments in the ultrahigh-frequency (UHF) range and beyond—including Tacsat, the Lincoln Experimental Satellite series, the UHF Gapfiller program, Marisat, and FLTSATCOM—to provide both UHF (0.3–3 gigahertz) and SHF (3–30 gigahertz) links to mobile and shipborne terminals. The United States also expanded military frequency use into the extremely high frequency (EHF) range (30–300 gigahertz) with the development of the FLTSATCOM EHF Package. This system saw the introduction of sophisticated onboard processing subsystems that provided frequency hopping for antijam communications, low probability of interception/detection, and mitigation of natural and induced atmospheric scintillation. It provided the proof of concept for the highly secure onboard waveform processing that was subsequently used in the Milstar satellites launched in the 1990s.

The DSCS III satellites, first launched in 1982, further enhanced U.S. military communications by providing new features—such as adaptive nulling—to counteract jamming (see related article, "Adaptive Nulling Antennas for Military Communications"). These features were enhanced even further in the Milstar satellites. By the late 1980s, U.S. milsatcom advancements had greatly outpaced European developments.

Separate Evolutions

During the 1980s and 1990s, European nations pursued autonomous milsatcom capabilities along two independent paths: The Skynet and NATO programs acquired dedicated satellites that maintained a level of interoperability with U.S. systems, while other nations such as France, Spain, and Italy chose to go their separate ways (see table, Historical Record of U.S. and EU Milsatcom Launches).

The Skynet 4 satellites (Skynet 3 was cancelled in 1974) enhanced the United Kingdom's X-band coverage with higher-power channels; it also added two UHF channels for connectivity to mobile platforms and housed an experimental EHF uplink for increased jam resistance. The Skynet 4 series provided increased power output for the two UHF and four SHF transponders, a steerable high-power SHF spot beam, wider SHF channel bandwidths, and two S-band (1.7–2.7 gigahertz) transponders. This was the first payload that was built by British contractors with no U.S. assistance.

NATO also replenished its satellite resources, launching NATO IVA and IVB in 1991 and 1993. The NATO IV satellites were almost identical to Skynet 4 because they were procured by the UK Ministry of Defense.

The Spanish Hispasat satellites are owned and operated by a combined public-private company formed by the Spanish government. Hispasat provides X-band service through bent-pipe transponders.

In France, Spain, and Italy, military and commercial communication satellite programs were combined to offset each country's relatively limited space-technology capabilities and to provide support to their national industries. For example, the first French milsatcom system, Syracuse, was built by the French Ministry of Defense and hosted on the commercial Telecom communication satellites. Syracuse provided X-band "bent-pipe" transponders, which provide no onboard processing of uplink and downlink signals. Spread-spectrum modulation was used to provide jam resistance, and Telecom used a standard bus to help minimize cost (Syracuse 2 was only a $2 billion program). Syracuse blended not only government and private system operations and funding, but also management. The Telecom program was directed and operated by the French national telecommunications agency. In contrast, U.S. laws and regulations generally prohibit a government role in ownership or management of commercial satellite communications systems.

Similar to the French acquisition model, the Spanish acquisition model combines federal government and commercial oversight. Spain's Hispasat satellites are owned and operated by a combined public-private company formed by the Spanish government. Like Syracuse, the Hispasat satellites provide X-band service through bent-pipe transponders (3 channels of 125 megahertz bandwidth), with directive antenna coverage that is provided by a simple steerable horn-antenna assembly feeding a parabolic dish.

The Italsat program provided the development platform for Italy's dual-use military and commercial communication satellite technology. It provided the first European implementation of onboard processing.

Civil Systems

In the United States, public expenditures for space are balanced more or less equally between the civil and defense sectors, and defense funding for space research and development is four to five times that of commercial funding, according to figures published by the National Science Foundation and various research groups. Thus, defense and civil space technology developments have both played a large role in U.S. commercial space advances. In Europe, on the other hand, public expenditures for space come predominantly from the European Space Agency (52 percent), followed by the national space agencies (31 percent) and military programs (17 percent). The funding balance reflects a European emphasis on developing a strong regional space industry rather than military space systems. As a result, advancements in civil space systems tend to enable military and commercial space systems, and not vice versa. Civil space programs that have assisted European milsatcom developments include the Italsat, Olympus, Artemis, and Stentor programs.

The Italsat program provided the development platform for Italy's dual-use military and commercial communication satellite technology. While the first Italsat satellites did not include overt military payloads, they supported the Italian milsatcom program, known as SICRAL, by providing the first European implementation of onboard processing. They also included an L-band (1.5–1.7 gigahertz) and Ku-band (10.7–14.5 gigahertz) mobile communications package (Italsat 2) and an EHF-propagation experiment (Italsat 1).

The Olympus program began in 1982 and ended with a launch in 1989. The satellite improved upon previous European communications satellites by providing higher-power capabilities (3.5 kilowatts), steerable beams at the Ka band (27–31 gigahertz), a Ka-band propagation experiment, and higher bandwidths—including one 700-megahertz channel. Sponsored by the European Space Agency, Olympus was truly a pan-European effort, involving project members from 11 European countries (and Canada).

Artemis is sponsored by the European Space Agency. Despite initial launch difficulties Artemis, successfully demonstrated its laser crosslinks.

Artemis, also sponsored by the European Space Agency, included Ka-band and laser crosslinks, spot beams, and L-band capabilities to mobile users that were somewhat derivative of the Italsat payloads. Unfortunately, the failure of the upper stage during the 2001 launch left Artemis in an inclined orbit far below its targeted geostationary course. Efforts to salvage the operation were partly successful, and Artemis demonstrated its laser crosslinks in November 2001, establishing an optical data-transmission link with a French Earth-observation satellite, SPOT 4.

The Stentor program, developed by the French Space Agency, was designed to demonstrate advanced bus technologies, including ion propulsion, lithium-ion batteries, deployable thermal radiators, fluid loops for heat transport, and autonomous stationkeeping using the Global Positioning System. In addition, the program contains communication technology demonstrations such as its active-array antennas and onboard digital processing. The Ku-band payload includes one wideband transponder, three transponders with surface-acoustic-wave filters and onboard multiplexers, a 48-element phased-array antenna, a deployed reflector, and a steerable spot-beam antenna. Stentor also has an EHF-propagation experiment. These communication technologies are expected to benefit the French Syracuse 3 and 4 programs.

Pan-European Milsatcom Efforts

Given the cooperation seen on civil programs such as Olympus, one might have anticipated the creation of a pan-European milsatcom system; however, the path toward a multinational milsatcom system has proved tortuous.

In 1992, the Western European governments began collaborative discussions geared toward initiating a pan-European system. In 1993, three separate programs were being studied: EuMilSatCom, which would involve eight countries; BiMilSatCom, involving the United Kingdom and France; and InMilSat, involving the United Kingdom, France, and the United States.

Sponsored by the European Space Agency, Olympus improved upon previous European communication satellites by providing higher-power capabilities, steerable beams at the Ka band, a Ka-band propagation experiment, and higher bandwidths.

By 1995, the EuMilSatCom discussions were discontinued when Italy dropped out, citing the program's estimated costs. InMilSat was dropped because of differences between U.S. and European operational requirements. At the same time, two new potential programs emerged: GEFsatcom, involving Germany and France; and TriMilSatCom, involving the United Kingdom, France, and Germany. Discussions for both ended unsuccessfully in 1996.

In 1997, the United Kingdom, France, and Germany signed a TriMilSatCom Memorandum of Understanding, and it appeared that a European milsatcom system was on the horizon. One year later, however, the United Kingdom withdrew after deciding to focus on a separate national system (Skynet 5).

At this point, given the substantial difficulties in reconciling performance requirements, achieving interoperability with legacy systems, controlling cost, and apportioning national workloads, most other countries also decided to focus on national systems. The single remaining exception is a potential collaboration between France and Germany in the Syracuse 3 system.

Current Developments

The United States has been actively encouraging milsatcom interoperability with major European allies since the 1980s and has been aggressively promoting the use of shared waveforms. The model for this effort is the Milstar system, which achieved interoperability among three U.S. military branches by imposing an interface control document—in effect, a waveform interoperability standard. In the early and mid-1980s, Aerospace began to document the Milstar low-data-rate (LDR) waveform as a standard that could be made available to a variety of U.S. space programs. This effort was eventually adopted by the Air Force and resulted in the official military EHF LDR Waveform Interoperability Standard. When medium-data-rate (MDR) capability was added to the Milstar program in the early 1990s, the idea of a waveform standard was already well accepted, and Aerospace contributed significantly to a broad-based government effort to document the new waveform as the official military EHF MDR Waveform Interoperability Standard.

These two EHF U.S. military waveform standards, along with standards associated with other frequency bands, have been shared with selected major allies over the years in hopes that they would be used in systems developed by those allies. In addition, with the help of allies, several U.S. waveform standards have been adapted and ratified as NATO Standardization Agreements. Still, while the United States has had some success in influencing NATO Standardization Agreements, it's had very little success in convincing allies to introduce systems that are interoperable with U.S. milsatcom systems.

For example, Italy's SICRAL, first launched in 2001, uses technologies that were tested on Italsat. Consequently, 90 percent of the technology was developed in Italy. The system boasts the first operational EHF communications capacity produced in Europe; however, it does not include onboard demodulation and remodulation and therefore is not interoperable with U.S. systems or compatible with recently approved NATO EHF Standardization Agreements. Only the SHF and UHF military capabilities were built in accordance with NATO Standardization Agreements. The next generation of SICRAL is expected to include an onboard SHF processing capability and frequency-hopping protocols compatible with the Universal Modem, a multinational effort to provide jamproof satellite communications using the nonprocessing transponders on DSCS III, NATO, or Skynet 4. Of course, the United States stopped working on equipment employing the Universal Modem standard several years ago, deciding instead to focus on EHF systems for antijam communications.

The United Kingdom is replacing the aging Skynet 4 constellation with Skynet 5, which will provide UHF, SHF, and EHF communication capabilities, though not necessarily from a single satellite design. British requirements do not explicitly call for processed EHF, although they do require interoperability with U.S. networks—especially U.S. Navy networks. EHF service will most likely be provided as part of an anticipated bilateral agreement involving participation in the Advanced Extremely High Frequency (AEHF) program, the successor to Milstar; but this EHF service could potentially be a separate payload on a Skynet 5 bus. In this case, a U.S. contractor would probably build the EHF payload.

The Telecom 2 satellite, which hosts the Syracuse 2 payload, will reach the end of its service life in 2006; thus, a Syracuse 3A launch is required in 2003, a Syracuse 3B launch in 2006. The Syracuse 3 will include SHF channels cross-strapped with EHF feeder-links, but the EHF capability will not be processed onboard and therefore will not be compatible with U.S. systems.

The Spanish government is also seeking a replacement for its Hispasat satellites, to be called XTAR/SpainSat. It appears that the military payload will be nine SHF bent-pipe transponders, with no onboard processing.

The desire to enhance indigenous space capabilities has fostered the development of four separate European milsatcom systems, none of which will be fully interoperable with U.S. systems or with each other. Only the Skynet 5 EHF capability is expected to be interoperable with U.S. systems, thanks to the anticipated U.S. involvement in the payload's design and manufacture.

Future Prospects for Interoperability

The NATO IV satellites are reaching the end of their service lives, and NATO must decide soon on a replacement strategy. Possible acquisition methods for NATO V include a standard acquisition contract, shared capacity with a national system, or a publicly financed (fee-for-service) initiative. Separately, the governments of the United States, United Kingdom, France, and Italy have all proposed that their national systems be used as the basis for either a gapfiller to NATO V or for the NATO V system itself. The United States also proposed a partnership in the AEHF program as a solution to NATO's future highly protected milsatcom requirements.

France will launch Syracuse 3 in 2003. The satellite will include SHF channels cross-strapped with EHF feeder-links, but the EHF capability will not be compatible with U.S. systems. The SHF payload will have four spot beams, one global beam, one beam for metropolitan France, and nine 40-megahertz channels. The EHF payload will include two spot beams, one global beam, and six 40-megahertz channels. (Photo by George Rock)

The AEHF program is already international, as the United States and Canada have signed a bilateral Memorandum of Understanding detailing a partnership in the system's development. The Aerospace Corporation was heavily involved in the development of this document, providing most of the technical support to the U.S. delegations in these discussions. Aerospace also provided direct contracted support to the Canadian Department of National Defense in its evaluation of the program's ability to meet Canadian national communication requirements.

In addition, similar agreements with the United Kingdom and the Netherlands are nearing completion. Aerospace has also played a central technical support role in these negotiations. The Italian Ministry of Defense has stated that it would consider cooperative developments with the United States, but asserts that this would require transfer of U.S. technology to Europe—presumably a benefit to European industry. While NATO has documented needs for UHF, SHF, and EHF systems, it may not implement processed-EHF service until 2007 or later. The path toward resolution of the NATO V acquisition decisions and the potential for direct NATO interoperability with U.S. systems is not clear.

Hopes for allied milsatcom cooperation may ride on recent European Union statements calling for a common European rapid-reaction force. Further transatlantic cooperation may also drive the perceived need for an interoperable (at least by NATO standards) European milsatcom system. Cooperative space efforts are not necessarily viewed as more economical; indeed, the Italian Ministry of Defense estimates that its SICRAL system was cheaper to build than any cooperative system could have been.

Conclusions

The need for milsatcom interoperability with America's major European allies was clearly established during the Gulf War and remains a crucial factor for future development. As one path toward the goal of interoperability, the United States has tried to obtain agreements on waveform standardization. These efforts have been moderately successful on paper, but they have not led to the development of interoperable systems—probably because of Europe's inability to match America's relatively high funding levels and fast development schedules.

Similarly, efforts to pursue future system developments on an equal-partner basis have also failed because of the lack of equality in the capability, requirement levels, and funds available. International interest in America's AEHF program appears to provide the best hope yet for eventual front-line milsatcom interoperability. While the value of true interoperability that spans all levels of military operations is not yet universally accepted, its desirability appears clear to U.S. decision makers, who will undoubtedly emphasize allied interoperability in all future milsatcom developments.