D
Space Communications Systems and Capabilities

The Navy and Marine Corps currently employ a wide range of space communications services and will employ new Department of Defense (DOD) satellite communications systems as they come online. Some of these systems are geared primarily for voice (walkie-talkie) service, others for Internet Protocol (IP) datagrams; some are protected and robust against jamming, others are very fragile; and some are designed for handheld devices, others for high-speed data to large-deck ships. As the wide range of these systems can be very confusing, the following discussion summarizes the basic structure of DOD space communications strategy, in the context of space communications programs. Military space communications can be categorized in four areas on the basis of communications systems requirements: wideband services, narrowband services, assured secure communications services, and commercial communications services.

Figure D.1 provides a notional mapping onto user classes of the newer DOD satellite systems, circa 1999, when the new satellite systems were being defined. Reading down the “Navy Ships” column, one observes that the Advanced Extremely High Frequency (AEHF) expanded data rate (XDR), Wideband Gapfiller System (WGS) Ka- and X-band, and UHF (ultrahigh frequency) Follow-on (UFO) services were considered most relevant for the surface Navy, with the Global Broadcast Service (GBS) services being added and the AEHF XDR and WGS Ka-band being unused in the “Command Ships” column. The Marine Corps is noted as utilizing AEHF XDR service for brigades (“Brigade” column) and WGS and UFO/GBS service for Corps-level communications (“Corps” column). Strike aircraft (“Strike A/C”) similarly rely on AEHF XDR and UFO/UHF service.



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Navy’s Needs in Space for Providing Future Capabilities D Space Communications Systems and Capabilities The Navy and Marine Corps currently employ a wide range of space communications services and will employ new Department of Defense (DOD) satellite communications systems as they come online. Some of these systems are geared primarily for voice (walkie-talkie) service, others for Internet Protocol (IP) datagrams; some are protected and robust against jamming, others are very fragile; and some are designed for handheld devices, others for high-speed data to large-deck ships. As the wide range of these systems can be very confusing, the following discussion summarizes the basic structure of DOD space communications strategy, in the context of space communications programs. Military space communications can be categorized in four areas on the basis of communications systems requirements: wideband services, narrowband services, assured secure communications services, and commercial communications services. Figure D.1 provides a notional mapping onto user classes of the newer DOD satellite systems, circa 1999, when the new satellite systems were being defined. Reading down the “Navy Ships” column, one observes that the Advanced Extremely High Frequency (AEHF) expanded data rate (XDR), Wideband Gapfiller System (WGS) Ka- and X-band, and UHF (ultrahigh frequency) Follow-on (UFO) services were considered most relevant for the surface Navy, with the Global Broadcast Service (GBS) services being added and the AEHF XDR and WGS Ka-band being unused in the “Command Ships” column. The Marine Corps is noted as utilizing AEHF XDR service for brigades (“Brigade” column) and WGS and UFO/GBS service for Corps-level communications (“Corps” column). Strike aircraft (“Strike A/C”) similarly rely on AEHF XDR and UFO/UHF service.

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.1 Notional breakdown of Department of Defense satellite systems, by users. (A list of acronyms is provided in Appendix G.) SOURCE: Christine M. Anderson, Program Director, Military Satellite Communications Joint Program Office. 2002. “Transformational Communications,” slide 6, presentation to Ground System Architectures Workshop, El Segundo, Calif., March 14. WIDEBAND SERVICES Wideband services currently are allocated into channelized communications channels provided by both commercial and DOD satellites. Current wideband services are provided by the Defense Satellite Communications System (DSCS) satellites, and by the GBS through an additional payload on the most recent UFO satellites. Services include unprotected and some secure data services, from 2.4 to 128 kb/s, voice channel capacity from 16 to 72 kb/s, and broadcast data and video services at up to 6 Mb/s. In addition to these services there are wideband space-to-space links provided by national space relays and commercial sources. The basic roadmap for DOD wideband services is shown in Figure D.2. Current wideband satellite services provided by DSCS-Service Life Extension Program (SLEP) and GBS satellites will be augmented by the WGS, now under contract to the Boeing Company. WGS will provide two-way communications in X, K, and Ka bands, with broadcast services in K and X bands. The aggregate throughput of each system will be approximately 3.6 Gb/s, with a bus power capacity of 18 kW. According to Boeing, WGS will offer 4.875 GHz of instantaneously switchable bandwidth. The WGS system will provide capacity

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.2 Roadmap for Department of Defense wideband satellite services. (A list of acronyms is provided in Appendix G.) SOURCE: Adapted from Col J. Barry Patterson, Chief of Satellite Communications Division (J6S), U.S. Space Command, “Transformational Communications Study,” February 28, 2002. ranging from 1.2 Gb/s to more than 3.6 Gb/s to tactical users, depending on the mix of ground terminals, data rates, and modulation schemes employed. The WGS design includes 19 independent coverage areas that can be directed throughout the field of view of each satellite to serve warfighters between 65 degrees North and South latitudes. The connectivity capabilities of WGS enable users talk to other users with efficient use of satellite bandwidth, using subchannel routing techniques. A total of three WGS satellites have been contracted to date, with an initial launch scheduled for 2005. The Wideband System (WBS) shown in the roadmap in Figure D.2 is being studied today under an overarching concept of the Transformational Communications Architecture (TCA). Over the past 2 years, this architecture has been developed to address the issues of (1) explosive growth of DOD bandwidth needs; (2) data efficiency, as circuit switching migrates to packet-based technologies; and (3) complexity of terminal needs to support current (legacy) systems. TCA will implement a gigabits-per-second Internet-like backbone in space, to provide worldwide high-speed packetized information and data services to mobile and fixed-site users. Its scope includes the space segment, providing radio frequency (RF) and laser communications linking air and space data between theater and continental United States users, a user terminal segment providing laser and RF user terminal development and production in concert with the space segment, and a terrestrial segment providing network control and interface services into the Global Information Grid (GIG). Wideband Gapfiller System The WGS program will provide the next generation of wideband communications for the DOD while maintaining compatibility with existing and pro-

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Navy’s Needs in Space for Providing Future Capabilities TABLE D.1 General Characteristics of Wideband Gapfiller System   Description Primary function High-capacity military communications satellite Primary contractor Boeing Satellite Systems Satellite bus Boeing 702 Weight Approximately 13,000 lb at launch; 7,700 lb on-orbit Orbit altitude 22,300 miles; geosynchronous Payload Transponded, crossbanded X- and Ka-band communications suite Antennas 8 beams, transmit and receive X-band phased arrays; 10 Ka-band gimbaled dish antennas; 1 X-band Earth coverage Capability 39 channels, 125 MHz each via digital channelized/router SOURCE: Air Force Space and Missile Systems Center Web site <http://www.losangeles.af.mil/SMC/MC/wgs.htm>. Accessed May 5, 2004. grammed X- and Ka-band terminals.1 Broad WGS characteristics are provided in Table D.1. The WGS implementation plan calls for three to six geosynchronous spacecraft. The contract award was made in January 2001, and at the time of this writing, initial operational capability is planned for April 2006 and full operational capability for February 2007.2 These new satellites will transmit an aggregate of several gigabits of data per second—up to 10 times the data flow of the satellites that the WGS will replace—though, as shown below, the objective maximum rate for the Navy’s new WGS terminal supports, at most, 40 Mb/s for even the most advantaged Navy platforms. The WGS constellation will supplement the two-way military X-band (7 to 8 GHz) communications capability now provided by the DSCS and the receiveonly military Ka-band (20 to 21 GHz) downlink provided by the GBS. In addition, the WGS will provide a high-capacity two-way Ka-band capability to support mobile and tactical personnel. Early estimates indicated that one WGS satellite could provide transmission capacity up to 2.4 Gb/s. This capability alone exceeds the capacity of the entire existing DSCS and GBS constellations. Capacity gains will be matched by improved features, such as multiple high-gain spot beams that are particularly important for small terminal and mobile users. Each WGS satellite supports 9 X-band beams and 10 Ka-band beams. Eight of the X-band beams are formed by separate transmitting and receiving phased- 1   Information in this section was adapted from the Air Force Space and Missile Systems Center Web site on WGS <http://www.losangeles.af.mil/SMC/MC/wgs.htm>; SPAWAR PMW176, available at <http://enterprise.spawar.navy.mil/pmw176/products.htm>; and G. Elfers and S.B. Miller, 2002, Future U.S. Military Satellite Communication Systems, Aerospace Corporation, Los Angeles, Calif., available at <http://www.aero.org/publications/crosslink/winter2002/08.html>. All accessed May 5, 2004. 2   DOD Press Release, “Department of Defense Releases Selected Acquisition Reports,” August 15, 2003, available at <http://www.defenselink.mil/releases/2003/nr20030815-0374.html>. Accessed May 5, 2004.

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Navy’s Needs in Space for Providing Future Capabilities array antennas that can adaptively form beams onto specific, desired coverage areas. The ninth X-band beam provides Earth coverage. The 10 Ka-band beams are formed by gimbaled dish antennas and include 3 beams with reversible polarization. An onboard digital channelizer divides the payload’s overall communications capacity into 1,872 subchannels of 2.6 MHz each and independently switches each subchannel. The signals can be crossbanded from one frequency band to another, and any uplink coverage can be connected to any downlink coverage. Also, any uplink signal within one coverage area can be connected to any or all downlink coverages. User terminals capable of operating within the several WGS frequency bands are a fundamental piece of the wideband architecture. The Air Force and Army are acquiring up to 200 lightweight, high-capacity quad-band ground multiband terminals (GMTs) for use with the WGS, DSCS, future Advanced Wideband System (AWS), and commercial satellite systems. In addition, the Army’s Multiband/multimode Integrated Satellite Terminal (MIST) will provide up to a few megabits per second of capacity for on-the-move communications. Navy Wideband Gapfiller Satellite Terminals Within the Navy, the Super High Frequency (SHF)/Commercial Satellite Communications Division is responsible for procuring, fielding, and sustaining satellite communications (SATCOM) terminal systems to provide wideband communications services to the fleet. In addition to fielding SHF (X-band) satellite communications terminals (WSC-6) to the fleet, the division is inserting new technology to leverage the increase in capability in the SLEP and WGS programs. Recent Navy documents indicate that the Navy is not planning to develop terminals to provide a full utilization of the SHF bandwidths. Rather, the Navy is focusing its future developments on terminals that are more modest in size and thus enable lower inherent bandwidth to the satellite. In particular, a recent article on the Navy’s AN/WSC-6(V)XX SHF communications terminal program states that “four antenna aperture diameters are currently envisioned to be approximately 38, 60, 93 and 108 in. (3 ft, 5 ft, 7 1/4 ft, and 9 ft) although the actual sizes shall be proposed by offeror…. With its four antenna size variants, the AN/ WSC-6(V)XX will see service on virtually all U.S. Navy and Military Sealift Command (MSC) surface ship classes…. The AN/WSC-6(V)XX Dual Antenna Handover System (DAHS) shall mitigate SATCOM disruptions caused by antenna handover switching when the AN/WSC-6(V)XX operates at full-duplex data rates from 64 kilobits per second to at least 24 megabits per second, with an objective maximum of 40 megabits per second (emphasis added).”3 Thus, the 3   See <http://www.fbodaily.com/archive/2002/10-October/11-Oct-2002/FBO-00185320.htm>. Accessed May 5, 2004.

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Navy’s Needs in Space for Providing Future Capabilities Navy’s long-term bandwidth capabilities, available through the WGS, will be limited to 40 Mb/s at most. Marine Corps Wideband Gapfiller System Terminals The lightweight multiband satellite terminal (LMST) is a tri-band SATCOM terminal capable of operation in the military X band and commercial C and Ku bands.4 At present it is capable of military Ka-band “receive only,” but there is a Program Objective Memorandum (POM) 04 initiative to improve the Ka band to two-way communications, synchronizing with the launch of the WGS. Each LMST can support four links and an aggregate data rate of 8.448 Mb/s and is upgradeable to 20 Mb/s. The LMST is a transit case system that can be moved by 2 high-mobility multipurpose wheeled vehicles (HMMWVs) and operated by a two-person crew. The Marine Requirements Oversight Council directed that the LMST compete to retire the legacy suite of ground mobile forces SATCOM terminals to reduce the operational risk involved in maintaining the current 20-year-old terminals. The LMST approved acquisition objective of 50 systems has now been approved. The full approved acquisition objective replaces legacy ground mobile forces terminals, thus providing a ten-fold improvement in Marine Expeditionary Force bandwidth, plus reduced operations and maintenance costs on 20-year-old terminals and simplified support for just the SHF SATCOM terminal type. Transformational Communications The Transformational Communications (TC) program will provide a revolutionary leap forward in DOD space-based communications. It is part of an overall plan that calls for a new IPv6-based DOD network architecture, a new end-to-end cryptographic architecture based on IP security employing the High Assurance Internet Protocol Encryptor (HAIPE), a new Advanced Polar Satellite (APS) constellation, airborne laser communications terminals, and a new DOD network management architecture. The TC implementation plan calls for a total of up to eight geosynchronous TC spacecraft and APS satellites connected by laser crosslinks. The entire TC program is still early in its development, with Phase B acquisition of the space segment starting in the fall of 2003 under two competing contractor teams; at the time of this writing, first launch is scheduled for December 2009. These new satellites will be capable of extremely high communications capacity. Figure D.3 presents the current view of the TC system in context: TC is the shaded cloud in the center with interfaces to other systems as depicted. As can be 4   LtCol Wayne R. Martin, USMC. 2003. Health of Command Element Advocacy, U.S. Marine Corps, Washington, D.C., February 10.

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.3 Transformation communications system in context. (A list of acronyms is provided in Appendix G.) SOURCE: CDR J.J. Shaw, USN, “Transformational Communications Architecture,” Office of the Chief of Naval Operations (N611), Washington, D.C., August 11, 2003. seen, one of TC’s objectives is to merge assured communications functions, over the long term, from the MILSTAR (Military Strategic, Tactical, and Relay) satellite and AEHF programs, and to utilize the AEHF system and Mobile User Objective System (MUOS) as edge systems for implementing information delivery to users, while providing the overall high-speed, space-space, and space-ground links. Table D.2 presents the current view of the capabilities of an individual TC satellite. As can be seen, these satellites are currently expected to support a number of beams in a wide variety of bands ranging from 7 to 44 GHz. Each satellite will also perform onboard packet routing. Terminals for Transformational Communications The Navy and Marine Corps will need to develop new terminals to take proper advantage of TC. The Navy terminal program associated with TC has as an objective to develop an architecture, execute research and development (R&D), and prepare for the procurement of a single, multiband, multifunctional terminal suite. The suite would be configurable to meet diverse shipboard, submarine, air, and shore terminal requirements. Figure D.4 displays a notional terminal migration path to support TC links to Navy ships, and Table D.3 presents the Navy’s baseline fielding schedule for TC Spiral 1 terminals. As shown, this baseline includes surface ships, submarines, and aircraft.

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Navy’s Needs in Space for Providing Future Capabilities TABLE D.2 General Capabilities and Features of the Transformational Communications Satellite (TSAT) Capability/Feature Description Notional TSAT Capabilities EHF Communications 44 GHz up; 20 GHz down —Raw capacity per TSAT 0.8 to 3.1 Gb/s; does not include IP gain, link margin management, and so on (AEHF 0.2 to 0.3 Gb/s) —Space-based IP router Bandwidth on demand —Waveform XDR —Input channels 40 active processed —Output channels 17 active —Nuller antennas Two 80 in. 19 element EHF —Multibeam antennas One 40 in. EHF —Gimbaled dish antenna Six 24 in. —Rx phased array Two 10-beam —Tx phased array Two single-beam Ka-band payload 30 GHz up; 20 GHz down X-band payload 8 GHz up; 7 GHz down Optical communications Five laser heads TSAT Payload Features Theater multibeam antenna Two 80 in. 44/20 GHz, include single 8/7 GHz Tx/Rx Gimbaled dish antenna Six 24 in., include 44/20, 8/7, and 30 GHz Active receive phased array One (ten 44 GHz beams) Active transmit phased array Two (one 20 GHz beam each) Waveform Includes broadband communications XDR modes Routing Onboard packet Transmitters 17 D/L, including one 20 GHz per ATPA, three 20 GHz and two 7 GHz for GDAs, eight 20 GHz and one 7 GHz for theater multibeam arrays Apertures 5 optical, all single access (spiral 1) and 1 multiaccess (spiral 2) NOTE: A list of acronyms is provided in Appendix G. SOURCE: MILSATCOM Joint Program Office, 2003, “Transformation Communications MILSATCOM Industry Day Brief,” Air Force Space Command, El Segundo, Calif., March 5-7; and Michael Frankel, OSD, “Implementing the Global Information Grid (GIG),” presentation to the committee on June 27, 2003. Navy’s Active Role in Transformational Communications Because the TC program will have an extremely important impact on naval communications, the Navy has been active in the development and management of the architecture. This role includes recent Navy leadership of the Transformational Communications Architecture (TCA) office. It is essential for the Navy and Marine Corps to continue to engage as full partners in the ongoing design, refinement, and acquisition of the TC system. It is likely that numerous trade-offs will be made in the course of system design, and the Navy and Marine Corps must be knowledgeable and fully “in the loop” as

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.4 Navy terminal migration strategy for Transformational Communications (TC): path to support TC links to Navy ships. (A list of acronyms is provided in Appendix G.) SOURCE: Michelle Bailey, PEO C4ISR, “Navy Transformational Communications (TC) Terminal Acquisition,” May 20, 2003. these decisions are made. This participation is not only the most effective way to influence implementation of Navy bandwidth needs, but it would also protect against the possibility that essential naval capabilities could be obscured or modified in the requirements versus cost trade-offs occurring during the course of program development. To this end, there is concern that the Navy and Marine Corps have not developed an overall support strategy for TCA and other key space communications acquisitions. Such a strategy would need to have continuity over TCA’s acquisition lifetime and should include seniority in key assignments, depth and knowledge of support staff, and communications regarding the status of acquisitions and key issues within naval stakeholding organizations. While the TC architecture and acquisition program matures, it should be recognized that TC is an extraordinarily ambitious program, and it is fairly predictable that this program, like other ambitious space programs, will overrun its current cost projections and extend its currently projected launch dates. Thus, the Navy and Marine Corps will need to continue to provide upgrades to current capabilities as they migrate to the new communications capability, but they will need to ensure that robust operational capability be provided via existing commercial, UHF, MUOS, GBS, AEHF, and MILSTAR programs, first as the fall-back path until TC dates are better understood, then as assured capability until the

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Navy’s Needs in Space for Providing Future Capabilities TABLE D.3 Navy Baseline Transformational Communications Terminal Fielding Schedule Funding Source No. of Terminals Scheduled OPN Funded FY09 FY10 FY11 FY12 FY13 FY14 FY15 Total AGF   4   4 CG 4 2 4 4 5 6 2 27 CV/CVN/CVNX 4 2 4 4 4 4 2 24 DDG 5 4 5 8 10 12 9 53 LCC   2     2     4 LHA 2 2   2 2   2 10 LHD 2     4 4 4 2 16 LPD   1   6 5 3 2 17 LSD   5 5   2 12 LCS 1 1 1 1   4 SSBN/SSGN   4 4 4 6 2 2 22 SSN (Los Angeles Class) 2 3 4 11 11 9 9 49 SSN (Seawolf Class)     1 1 1     3 SSN (Virginia Class)     1 1 1 1   4 Operations (Shore)   6 7 20 10 3 3 49 Training (Ship/Submarine/Shore) 6   6 Test (Ship/Submarine/Shore) 5   5 Total OPN Funded 31 31 31 71 66 44 35 309 SCN Funded FY09 FY10 FY11 FY12 FY13 FY14 FY15 Total CV/CVN/CVNX   2   2   4 DDG   3 3 3 9 JCC(X)   2 2 2 6 LCS     4 4 4 1   13 Total SCN Funded     4 6 9 8 5 32 APN Funded FY09 FY10 FY11 FY12 FY13 FY14 FY15 Total E-6 Aircraft     5 5 5 5   20 UAV   2 7 10 12 11 9 51 UCAV   8 8 16 Total APN Funded 0 2 12 15 17 24 17 87 NOTES: OPN, other procurement, Navy; AGF, miscellaneous command ship; CG, guided missile cruiser; CV, aircraft carrier; CVN, nuclear-powered aircraft carrier; CVNX, future aircraft carrier; DDG, guided missile destroyer; LCC, amphibious command ship; LHA, amphibious assault ship (general purpose); LHD, amphibious assault ship (multipurpose); LPD, amphibious transport dock; LSD, landing ship, dock; LCS, landing craft support; SSBN, nuclear-powered ballistic missile submarine; SSGN, nuclear-powered guided-missile submarine; SSN, nuclear-powered attack submarine; SCN, ship and construction, Navy; JCC(X), joint command and control ship; APN, aircraft procurement, Navy; UAV, unmanned aerial vehicle; UCAV, uninhabited combat aerial vehicle. SOURCE: Michelle Bailey, PEO C4ISR, “Navy Transformational Communications (TC) Terminal Acquisition,” May 20, 2003.

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.5 Department of Defense narrowband satellite communications systems roadmap. (A list of acronyms is provided in Appendix G.) SOURCE: Adapted from Col J. Barry Patterson, Chief of Satellite Communications Division (J6S), U.S. Space Command, “Transformational Communications Study,” February 28, 2002. TC systems are mature and integrated, and then as backup until retirement of all legacy systems occurs. NARROWBAND COMMUNICATIONS Narrowband communications services are defined as 64 kb/s or less of raw channel capacity to a user device (platform). These services, primarily unprotected narrowband tactical circuit-switched communications, are now provided by eight UFO satellites, the first launched in 1993 and reaching design lifetime around 2008. The narrowband constellation now supplies two-way low-rate voice and tactical switched circuits to the fleet. Functions include command and control communications between the combatant commanders and their components; connectivity for command and control of tactical forces; connectivity for deployed Special Operating Forces; connectivity supporting rapid deployments of land, air, and naval forces worldwide; and connectivity for tactical communications in all operating environments. Figure D.5 shows the nominal roadmap for the future development of narrowband (UHF) satellite communications systems. The UFO constellation is complete with the activation of the eleventh UFO satellite (UFO-11), which was successfully launched in December 2003. Because the design lifetime of the initial UFO satellites (15 years) is nearing an end, the Navy is leading the acquisition of the next-generation narrowband system, the Mobile User Objective System. This continues the 30-year history of naval leadership in narrowband space communications.5 5   For a review of U.S. Navy involvement in narrowband communications, see Jerry Ingerski, SPAWAR, PMW 146, and Alfred Sapp, Naval Network Warfare Command, 2002, “Mobile Tactical Communications, The Role of UHF Satellite Constellation, and Its Successor, the Mobile User Objective System,” paper and brief presented at the 2002 Military Communications Conference, Armed Forces Communications and Electronics Association (AFCEA) International, Anaheim, Calif., October 7-10.

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Navy’s Needs in Space for Providing Future Capabilities The Mobile User Objective System is the successor to today’s UHF Follow-On (UFO) system—UFO satellites were first launched in 1993 and UFO will remain the principal narrowband constellation until MUOS comes online. MUOS is currently expected to achieve initial operational capability in 2009, with full operational capability in 2013. In August 1996, the Deputy Undersecretary of Defense for Space was tasked by the Joint Space Management Board to further define the DOD Space Architect’s Military Satellite Communications (MILSATCOM) recommended architecture and to develop an affordable transition roadmap for this system. In November 1996, the Navy volunteered to lead the Joint Mobile User Study, which analyzed three main areas: requirements, systems engineering, and costing and acquisition strategy, and from more than 100 mobile user narrowband requirements, the study determined the following eight primary requirements, in descending order of priority: Assured access, Netted communications, Communications on the move, Joint interoperability, Worldwide coverage, Point-to-point communications, Broadcast, and Polar coverage. MUOS is being designed for compatibility with more than 50 types of existing UHF satellite communications terminals, including the AN/PSC-5 Spitfire, URC-133 Federated, ARC-210, and WSC-3. The Space and Naval Warfare Systems Command (SPAWAR) has succinctly described its rationale for the choice of the UHF band for user services as follows: There is a great need for the UHF portion of the spectrum because it gives the warfighter the ability to penetrate heavy weather, foliage, and concrete reinforced buildings. UHF generally includes the frequencies from 300 MHz to 3 GHz. The portion of the UHF spectrum that does the job for the warfighter today is from 200 MHz to 400 MHz. UFO satellites, the first launched in 1993, are the mainstay UHF communications for the mobile warfighter. They operate in the general range of 290-320 MHz Uplink, and 240-270 MHz Downlink. These frequencies are well suited for low-cost, low power, portable radios that reliably penetrate severe environments and offer assured access and netted communication.6 6   CAPT James Loiselle, USN, Robert Tarleton, and Jerry Ingerski, Communications Satellite Program Office, Space and Naval Warfare Systems Command, San Diego, California. 1998. “The Next Generation Mobile User Objective System (MUOS),” American Institute of Aeronautics and Astronautics of Aeronautics and Astronautics, Inc., AIAA-98-5246.

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Navy’s Needs in Space for Providing Future Capabilities This rationale is a sound basis for the development of the MUOS program. Although the Under Secretary of the Air Force is the DOD Executive Agent for Space, the Navy has been delegated responsibility for unprotected, narrowband satellite development.7 Accordingly, the Navy is procuring MUOS as the DOD narrowband satellite system for worldwide UHF communications. The Deputy Chief of Naval Operations for Warfare Requirements and Programs is the Navy’s satellite communications program sponsor, and the Communications Satellite Program Office at SPAWAR is the Navy’s Communications Satellite Acquisition Program Office. Two contractor teams are currently performing Phase II Concept Advanced Development, the updated operational requirements document is scheduled to be presented for Joint approval in early 2004, and acquisition will begin in mid-2004. As stated above, the MUOS constellation is planned for initial launch in 2009 and full operation in 2013. As the Navy’s only space program, MUOS is very important for the Navy. It is unclear how the Navy plans to integrate MUOS into the evolving GIG and TCA in order to meet launch dates and achieve initial operation prior to lifetime expiration of the current UFO constellation. As FORCEnet develops its communications requirements over the next year, it is important to clarify how MUOS will function as an edge system in the TCA. It may be possible to adjust the MUOS system design and capabilities during the upcoming advanced development phase to better accommodate Transformational Communications interfaces. MUOS will be an unprotected, narrowband system supporting a worldwide, multiservice population of mobile and fixed-site users. MUOS space and ground segments will include a network of advanced UHF satellites and the ground infrastructure necessary to manage the information network, control the satellites, and interface with other systems of the GIG. The network management will include improved capability for dynamic bandwidth allocation so as to be more responsive to changing operational communications requirements. During the transition from the UFO constellation, the MUOS will serve a user population consisting of a mix of legacy and new terminals. The new terminals will be Joint Tactical Radio System (JTRS)-compliant, designed to provide the mobile user with higher data rates and an improved link margin. It is clear that MUOS, as a narrowband system, will not resolve Navy and Marine Corps current and future bandwidth needs. For the purposes of MUOS, narrowband is defined to be 64 kb/s or less of raw channel capacity to a user 7   Information in this section is derived from the MUOS Draft Solicitation, dated September 10, 2003; Robert Tarleton, Deputy Program Manager, Space and Naval Warfare Systems Command, 2003, “Mobile User Objective System (MUOS) Brief to the Naval Studies Board,” presented on November 14, 2003; and CAPT James Loiselle, USN, Robert Tarleton, and Jerry Ingerski, Communications Satellite Program Office, Space and Naval Warfare Systems Command, San Diego, California, 1998, “The Next Generation Mobile User Objective System (MUOS),” American Institute of Aeronautics and Astronautics of Aeronautics and Astronautics, Inc., AIAA-98-5246.

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Navy’s Needs in Space for Providing Future Capabilities device (platform). In many cases, the planned user date rates will probably be significantly slower than this upper bound, on the order of 2.4 to 9.6 kb/s for handheld devices in urban terrain and 32 kb/s for large aircraft or submarines. However, MUOS does provide high-availability connectivity for basic communications needs for the mobile tactical user, who now relies on the oversubscribed UFO system. In addition to developing a better understanding of the interface between the TCA and the MUOS system, there are two areas in which the MUOS program may be able to adjust to become a more effective system. First, because the MUOS system is backward-compatible with the UFO system, it specifies a set of narrowband channels that can be allocated to users (5 or 25 kHz wide). Fixed channelization is an inefficient use of bandwidth, particularly for the burst data communications likely to dominate MUOS traffic. During terminal development, the Navy may need to consider baselining the capability to multiplex multiple narrowband channels to form broader channels (100 kHz or more) and to allow utilization of the aggregate as a single channel of higher bandwidth. Second, because MUOS is an unprotected communications asset, it should not be used as the sole means of communications with any tactical user whose combat capabilities are reliant upon satellite communications. The MUOS system may be able to accommodate increased robustness against jamming through error protection or increased nulling capability in order to reduce this limitation. ASSURED SECURE COMMUNICATIONS SERVICES Assured communications capability (supplied by the MILSTAR and AEHF satellites) is the most recently developed of the families of military communications available from space. The objective of the assured communications capability is to provide worldwide, secure, survivable, protected communications for U.S. and allied forces. The capabilities are now supplied by the series of MILSTAR geosynchronous communications satellites and will be augmented by the AEHF satellites now being readied for an initial launch in 2006. In the longer term, the TCA program will provide higher-bandwidth assured capabilities. These series of satellites are hardened in multiple ways to ensure the survivability of communications in case of a spectrum event of natural or hostile force actions. In fact, the MILSTAR system is the only protected and truly survivable space communications system available for U.S. military forces. It provides the unique capability for communications that the U.S. executive branch and DOD top commanders have to maintain positive command and control of strategic forces in the event of concerted and sophisticated enemy action. It is essential that the Navy communications strategy incorporate an understanding of the protected nature of the assured communications assets and plan capacities to retain essential warfighting capability in the event of loss of most or all of its unprotected communications links. The roadmap for assured space communica-

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.6 Department of Defense assured space communications roadmap. (A list of acronyms is provided in Appendix G.) SOURCE: Adapted from Col J. Barry Patterson, Chief of Satellite Communications Division (J6S), U.S. Space Command, “Transformational Communications Study,” February 28, 2002. tions capabilities is shown in Figure D.6. These programs and their capabilities are discussed below. MILSTAR With the launch of the last MILSTAR II communications satellite in the spring of 2003, the Air Force completed implementing the MILSTAR constellation of five satellites. The early MILSTAR satellites provided assured communications link capacities of a few tens of kb/s, and MILSTAR II provides an upgraded capacity of up to 1 Mb/s. The MILSTAR constellation provides secure transmission of critical command and control information (including voice, data, and imagery, as well as voice and video teleconferencing) between deployed forces and the command structure. MILSTAR provides rapid link establishment and switching, allowing space-space transmission of data and thus eliminating many space-to-ground communications hops. The capabilities of MILSTAR, and in particular MILSTAR II, were quickly pressed into service in support of Operation Iraqi Freedom. Early lessons learned from the war are indicated in the value of increased bandwidth to warfighting capability. For example, one review stated, “The real star in supporting/exploiting ISR was MILSTAR II: high data rate, antijam, encrypted and 100% available transmission of NRO/CIA processed intelligence to theater, remote tasking of Global Hawk, critical communications support of special operations, and rapid retargeting of Tomahawk missiles.”8 8   Loren B. Thompson. 2003. “ISR Lessons of Iraq,” presentation at Defense News ISR Integration Conference, November 18.

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Navy’s Needs in Space for Providing Future Capabilities U.S. Navy ships and tactical users routinely use MILSTAR and will, in the future, utilize the AEHF systems as an integral part of their communications structure. These systems provide the assured communications required to ensure continuity of command in all threat environments. Advanced Extremely High Frequency Satellite System The Advanced Extremely High Frequency (AEHF) program now in development will provide a series of advanced, protected communications satellites that will augment and eventually replace the current MILSTAR system as it reaches its design lifetime.9 The overall objective of the AEHF program is to develop and field a constellation of four geosynchronous AEHF satellites to provide worldwide secure, survivable, protected communications that are backward-compatible with MILSTAR but that significantly advance the capacity and capabilities for assured protected worldwide communications. The AEHF system will improve ease of operations, facilitate satellite control and monitoring, and effectively interface with evolving terminal designs. AEHF will consist of four cross-linked satellites covering the globe from 65 degrees North to 65 degrees South latitude, providing 10 times the data rate available through MILSTAR. The system provides uplinks in the EHF spectrum and downlinks in SHF spectrum. The AEHF system is currently in its system development and demonstration/ production acquisition phase, with the first launch currently scheduled for 2006 and initial operational capability scheduled for 2007. The system will provide backward compatibility with the existing MILSTAR low data rate (LDR) and medium data rate (MDR) services. It will also provide a new, expanded data rate (XDR) service. It will support a range of user data rates between 75 b/s and 8 Mb/s. Table D.4 presents the general characteristics of the AEHF system. Advanced Extremely High Frequency Aircraft Terminals Naval aircraft may employ the family of advanced beyond-line-of-sight terminals (FAB-T) that are currently being procured by the Air Force. FAB-T will develop robust, secure, survivable EHF voice and data satellite communications terminals for nuclear and conventional forces. FAB-T variants will provide ground and airborne command posts and other aircraft with connectivity to MILSTAR and AEHF satellites, while providing an open architecture terminal to support future increments for WGS, EHF payloads on polar and UFO satellites, GBS payloads, and TSAT. 9   Information in this section is derived from the Air Force Space and Missile Command Web site at <http://www.losangeles.af.mil/SMC/MC/aehf.htm>. Accessed May 5, 2004.

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Navy’s Needs in Space for Providing Future Capabilities TABLE D.4 General Characteristics of the Advanced Extremely High Frequency Satellite System   Description Primary function Worldwide, secure, survivable satellite communications Primary contractor Lockheed Martin Satellite Systems Satellite Bus A2100 line Weight Approximately 13,100 lb at launch; 9,000 lb on-orbit Orbit altitude 22,300 miles; Geostationary Payload Onboard signal processing, crossbanded EHF/SHF communications Antennas 8 gimbaled dishes, 1 EHF and 2 SHF phased arrays, 2 Earth coverage horns, 2 crosslinks Capability Data rates from 75 b/s to approximately 8 Mb/s NOTE: A list of acronyms is provided in Appendix G. SOURCE: Accessed from <http://www.losangeles.af.mil/SMC/MC/docs/aehf_bw_200.pdf.>. Accessed May 5, 2004. Advanced EHF Surface Ship, Shore, and Submarine Terminals The Navy Multiband Terminal is planned to support AEHF. In November 2003, SPAWAR awarded competitive 30-month contracts for four prototype terminals under direction of PMW 176-3. The acquisition phase is currently expected to begin in 2006 and to produce as many as 300 terminals. COMMERCIAL SATELLITE SERVICES In addition to DOD-dedicated space communications assets, the Navy routinely augments bandwidth by acquiring large amounts of communications services, including Intelsat, Inmarsat, Iridium, and the Defense Satellite Transmission Service (DSTS). In particular, the Navy is a major user of Inmarsat and Iridium for narrowband and voice services and Intelsat and DSTS-Global (DSTS-G) for wideband transponder-base services, and it is considering new ventures such as Boeing’s proposed Connexion service. These services are of increasing use as a quick way to acquire large amounts of bandwidth, but they are unprotected and require, in most cases, yet another set of dedicated terminals and connections into the local network. ADVANCED DIGITAL NETWORK SYSTEM For platforms with multiple satellite links, it is possible in principle to route traffic dynamically over links, depending on traffic type or priority, current operational or system status, and so forth. This capability is currently provided by the Advanced Digital Network System (ADNS). In fact, the Navy has put much of this capability into its network routers and currently plans to further extend

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Navy’s Needs in Space for Providing Future Capabilities ADNS functionality via procurement during 2004. This upgraded ADNS capability will provide a useful new feature, namely, truly dynamic routing of traffic over multiple satellite links, and perhaps even over other forms of RF links, rather than routing data according to present-day preconfigured rules. Looking farther into the future, the current ADNS capability needs further evolution from its current role of carrying Red (secret-level) traffic to a new Black ADNS system that is compatible with the GIG IP transport architecture. The details of this evolution are beyond the scope of this report, but the Navy will need to follow Black ADNS development as the Navy’s communications capabilities evolve and become compatible with the GIG architecture. HYBRID NETWORK ARCHITECTURES Satellite communications links have traditionally functioned as stand-alone communications pipes that directly tie a ship, submarine, or ground unit to its shore base. Going forward, naval units will be linked into a mesh network that also includes direct peer-to-peer data links (e.g., ship to ship); multihop wireless networks with ship, air, and land components; and high-capacity directional radio links, such as the Common Data Link. This new networking approach offers enormous promise for robust, high-capacity communications for naval forces. In particular, space communications can play a greatly increased role in such hybrid systems because they do not need to provide a complete solution—the inherent weaknesses of satellite communications (e.g., high latency, weather issues with optical links, and so on) can be compensated by augmentation with other communications links as contributory. In short, the great strength of satellite communications—ubiquitous, worldwide communications from anywhere to anywhere—can be married to robust, high-capacity local communications to form an overall network that is far more capable than any of its components in isolation. Figure D.7 provides one schematic illustration of such a hybrid network. The figure shows a naval force linked at very high bandwidth, and with great resilience, into the GIG via a hybrid optical/RF network. Optical links are employed between satellites and high-altitude aircraft (such as Global Hawk or E2-C). In general, these links will operate above the atmospheric effects that make direct optical links to the sea surface or ground problematic. The aircraft in turn may relay traffic down to ships, submarines, or Marine Corps forces via RF communications such as the Man Portable Common Data Link that can provide high capacity (500 Mb/s or higher) with jam-resistant links. As a result, even relatively small surface platforms could achieve total bandwidths of a gigabit per second or more in all weather conditions, plus high degrees of assurance and availability in the face of adversary jamming. Other hybrid network architectures have equally appealing properties. For example, a large-deck ship may contain high-capacity satellite links and then in

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Navy’s Needs in Space for Providing Future Capabilities FIGURE D.7 Notional high-bandwidth hybrid network with optical and radio-frequency (RF) links. turn act as a communications hub for smaller ships in its neighborhood. These ships may be linked by near-Earth RF links running as a peer-to-peer wireless network. For example, the JTRS Wideband Network Waveform may be used in this way. Elevated assets may be included in the mix in order to achieve beyond-line-of-sight connectivity from the large-deck hub to smaller platforms. In this approach, only the large-deck ships require their own large satellite aperture; smaller platforms then achieve high-bandwidth communications with the relatively small, nonstabilized antennas used by wireless ad hoc networks. In summary, it would be a great mistake to analyze or acquire space communications capability in isolation from other naval communications capabilities. Hybrid space/near-Earth communications networks are likely to provide much higher performance, and much greater robustness, than an all-satellite approach, and may become a necessary component of future naval communications systems.