Naval Communications Architecture (1994) / Chapter Skim
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GOAL ARCHITECTURE-NAVSATCOM-21
GOAL ARCHITECTURE-NAVSATCOM-21
Pages 44-64
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From page 44... ...
NAVSATCOM-21 was designed to provide communications both within and among the four levels shown in Figure 4.1. At the global level such connectivities supplement several other means of communications, such as terrestrial systems and commercial communications satellites.
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From page 45... ...
Accordingly, the panel investigated ways for the Navy to maximize the utility of major fielded/planned terminal programs, to augment critical communications services in a cost-effective manner, to incorporate dual-use systems, and to affect DOD's opportunity for modernization decisions on its scheduled military satellite communications. To correct, within the above constraints, the performance shortfalls of current systems, the panel established five goals for NAVSATCOM-21: increased capacity; improved interference (antijam)
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From page 46... ...
and Detectability (LPI) Protection X X X X Interoperability X X Flexible Connectivity X Smaller Terminals X X X Directive antennas on a communications satellite concentrate their receiving and transmitting capabilities on regions of interest and thereby permit capacity increases and/or terminal size reductions.
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From page 47... ...
DETECTION FOOTPRINTS UJ o z IU oc UJ u. oc Ul WITH AJ WAVEFORM ANTENNA DISCRIMINATION WITH AJ WAVEFORM IU _J 5 UHF SHF EHF UPLINK FREQUENCY DIRECTION TO SATELLITE t 8 GHz MILES FUTURE AJ/COVERT SYSTEMS USING EHF FOR INCREASED CAPACITY AND ROBUSTNESS; INCORPORATING SUFFICIENT LINK MARGIN FOR WEATHER FIGURE 4.2 Frequency considerations.
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From page 48... ...
Although more capable, processing communications pay loads are more complex than transponding ones, to date, most UHF, SHF, and commercial communications satellite systems have been implemented with transponders. The developing EHF systems are incorporating processing for the increased protection and flexibility discussed earlier.
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From page 49... ...
. TABLE 4.3 Requirements Satisfaction FEATURE CURRENT NAVSATCOM NAVSATCOM-21 GOALS Network Capacity Protection Connectivity Interoperability kbps Limited Mbps Hard/Soft Core Flexible Transmission/Baseband Standards NAVSATCOM-21 achieves its goals at limited cost by Leveraging planned activities in DOD and commercial SATCOM Minimizing the number of shipborne terminal types Maintaining compatibility with Navy communications and networking modernization efforts (Copernicus, CSS)
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From page 50... ...
Accordingly, the panel considered a number of options, including military communications satellites operating at EHF and SHF and commercial SATCOM systems.
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From page 51... ...
PROCESSING PAYLOAD T COVERAGE RATE EARTH 10 KBPS 800 NMI 500 KBPS 400 NMI 2MBPS 10W 44 GHz 20 GHz COVERAGE RATE EARTH 40 KBPS 800 NMI 2M8PS 400 NMI 8MBPS • SHORE LINKS HAVE GREATER CAPABILITY • MILSTAR II OFFERS FOUR TIMES GREATER DOWNLINK CAPABILITY FIGURE 4.4 Soft-core communications: representative EHF capability.
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From page 52... ...
As such, all planned EHF systems incorporate directive antenna and processing payloads. Hence, adding MDR capabilities to these systems primarily requires incorporating the appropriate signal processing features into the terminals' modems and the payloads' demodulation/remodulation subsystems.
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From page 53... ...
On the other hand, it is important to note that other users in the SHF pay load's transponders could limit the achievable ship-to-ship rates to 10 percent or less of the values shown in Figure 4.5. The indicated example capacities were obtained by assuming that the terminal had exclusive use of a transponder.
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From page 54... ...
Because of the proximity in frequency of the C-, military SHF, and Ku-bands, as well as the transponder-type payloads used in all three of these frequency bands, a C- or Ku-band ship terminal would be similar in size to the one in the military SHF example (Figure 4.5) and the resulting capacity would be approximately the same (i.e., the lower end of the MDR range with earth coverage pay load antennas and the upper end with payload antennas with high directivity)
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From page 55... ...
Several other commercial mobQe satellite oommcnicaboaxs s> 'Satellite-based signal processing has been incorporated into onN EHF saeLnr ajiiiiiiinivaajag syacns x As time. It could potentially also be employed on SHF or co^nerr.£ systems, bm n wouic pctihtti:> IK mMnracihit with the large numbei of terminals already deployed in these bands.
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From page 56... ...
signaling formats and transponder-based pay loads was assumed.5 Two types of airborne platforms were envisioned. One involved an aircraft-mounted sensor with a terminal that has a 2-ft aperture and a 100-W transmitter.
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From page 57... ...
30 Mbps from CM 300 Mbps from AC Typically downlinks to CONUS ground terminal NOTES: Data compression would ease communications impact Multiple beams needed for large area of operations Larger terminals/lower data rates -»smaller satellite antennas TDRSS availability/EHF transponder deployment considerations As shown in Table 4.5, a 6-ft EHF satellite antenna could support the relay of 4 Mbps from a cruise missile to a 10-ft ground terminal. Alternatively, 300 Mbps could be relayed from an aircraft installation.
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From page 58... ...
As shown in Table 4.6, LDR service can be provided either by an EHF approach with an Earth Coverage satellite uplink antenna or by a UHF technique. Alternately, the use of a directive EHF uplink antenna (1° beamwidth; 400-nmi coverage)
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From page 59... ...
Being incorporated into equipment -- High/very high data rates: CDL standard Compatible with transponded systems at SHF, EHF, C-, Ku-bands At SHF, the United States, the United Kingdom, and France are developing the Universal Modem, which will provide interoperable service over SHF/transponder-based pay loads at data rates up to 64 kbps. A NATO STANAG based on the Universal Modem signal formats is being 59
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From page 60... ...
In addition, there are other interoperable SHF modems and several evolving SHF DAMA techniques that the architecture accommodates. Similarly, the emerging UHF DAMA and other link and baseband standards for both 25-kHz and 5-kHz UHF SATCOM channels can be used with NAVSATCOM-21.
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From page 61... ...
BASELINE ARCHITECTURE COMMERCIAL UFO DSCS MILSTAR MODERNIZATION DECISION \S OPPORTUNITIES KEY TECHNOLOGY DEVELOPMENT AREAS TECHNOLOGY INSERTION OPPORTUNITIES SPACECRAFT TERMINALS NETWORKING AND CONTROL DEMONSTRATION OBJECTIVES: • SATISFY COMMUNICATIONS REQUIREMENTS • IMPROVE USER FLEXIBILITY/INTEROPERABILITY •REDUCE COST FIGURE 4.6 MILSATCOM architecture evolution. TABLE 4.8 DOD MILSATCOM Decision Opportunities OPPORTUNITY TIME FRAME EXPECTED EMPHASIS 1 1A : 3 4 1992 1993/1994 1993/1994 1997/1998 1998 Mid-1990s EHF systems Polar coverage SHF replenishment and commercial Post-2000 EHF systems UHF replenishment Two joint ARPA/service technology initiatives planned • ASTEC small LDR/MDR/VHDR EHF satellite • IMPACT terminal technology program 61
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From page 62... ...
The basic services are obtained via EHF (hard /soft core) , SHF (interim soft core on selected platforms; possibility for long-term backup via multiband terminal)
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From page 64... ...
Field multiband/beam terminal Exploit as available Commercial Services Selective installation for additional general-purpose capability Small, Airborne Platforms Develop cruise missile terminal Deploy cruise missile terminal Increase data rates Participate in DOD Activities Technology Programmatic ARPA satellite and terminal initiatives Wideband gateways EHF buoy EHF beam hopping MILSTAR II + augmentation SHF replenishment Commercial utilization SHF DAMA Post-2000 EHF UHF replenishment Low-cost replenishment terminals The panel believes very strongly that NAVSATCOM-21 provides economical corrections for current shortfalls in Navy satellite communications (capacity, protection, interoperability, connectivity) as well as the flexibility to evolve in response to changing requirements and technology advances.
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