Satellite communication is a technology that is used to transfer the signals from the transmitter to a receiver with the help of satellites. Communications via satellite have the unique characteristic of the ability to cover the globe with a flexibility that cannot be duplicated with terrestrial links. Mobile satellite service (MSS) is the term used to describe telecommunication services delivered by the satellites directly to mobile users on ships, vehicles, and airplanes or directly to handheld terminal carried by an individual. MUOS is the DoD’s next-generation satellite communications (SATCOM) system, designed to provide voice and data communications for U.S. forces anytime, anywhere.
More than 60 percent of US military satellite communication users are supported via the UHF band. The UHF spectrum is the military’s communications workhorse because it is the only radio frequency that can penetrate jungle foliage, inclement weather and urban
terrain. Approximately 67,000 UHF terminals are currently in military use on more than 50 terminal configurations, many of them designed to be small and portable enough to be carried deep into theaters of operation.
The UHF Follow-On, or UFO, constellation is the present narrowband military satellite communication system. UFO achieved Initial Operational Capability in November 1993 and Full Operational Capability in February 2000. However, the current UHF constellation is approaching its end of life and warfighter demand for satellite communication capability is increasing.
MUOS is the next-generation military Ultra High Frequency (UHF) Satellite Communication (SATCOM) system offering 10 times more capacity than the current UHF Follow-On (UFO) system. The Mobile User Objective System (MOUS), a Lockheed Martin-built ultra-high-frequency (UHF) satcom programme, consists of five geosynchronous earth orbit (GEO) satellites connected to four ground stations via fibre-optic network. Users with new MUOS terminals will be able to connect BLOS around the world and into the Global Information Grid (GIG), as well as into the Defense Switched Network, according to Lockheed Martin.
MUOS capabilities include simultaneous voice, video, and mission data to the ground, naval, and air tactical warfighters on-the-move over a secure high-speed Internet Protocol (IP)-based system. It shall provide improved connectivity in difficult terrain conditions, including Urban, Canyon, Mountain, Jungle, and Urban. It will also provide support to disaster relief and humanitarian efforts around the globe. The network provides near-global coverage, including communications into polar regions. MUOS also has demonstrated successful communication of Integrated Broadcast Service (IBS) messages to in-flight test aircraft.’
The US DOD’s Mobile User Objective System (MUOS) is a narrowband military satellite communications system that supports a worldwide, multi-service population of users, providing modern netcentric communications capabilities while supporting legacy terminals. Today there are more than 55,000 radio terminals currently fielded that can be upgraded to be MUOS-compatible, with many of them requiring just a software upgrade.
The Mobile User Objective System (MUOS), constellation developed by prime contractor Lockheed Martin with ground systems provider General Dynamics Mission Systems, was deemed operationally effective, operationally suitable, and cyber survivable, following completion of its Multiservice Operational Test and Evaluation (MOT&E) said an October 2019 statement by Naval Information Warfare Systems Command (NAVWAR). The MUOS is expected to extend narrowband communications availability well past 2025.
US Army tactical radio and networked communications specialists demonstrated, for the first time, the ability to integrate Mobile User Objective System (MUOS) capability to mounted and dismounted radio platforms, in 2021. The implementation of MUOS capability into the army’s tactical manpack radio system variants “provided additional beyond the line-of-sight communications … and leverage the ability to fully dominate both the data and voice spectrum”, during the exercise, said Colonel Rob Ryan, chief of operations for Army Future Command’s Network Cross-Functional Team. The MUOS demonstration took place during recent exercises at the Joint Readiness Training Center in Fort Polk with units from the 1st Brigade Combat Team, 82nd Airborne Division.
“Sailors and Marines can already use MUOS in situations like humanitarian response, disaster assistance and training,” said a statement from John Pope, who leads the Navy’s Program Executive Office for Command, Control, Communications, Computers, Intelligence and Space Systems (PEO C4I and Space Systems). “Now, these same advanced communications capabilities will be available in the tactical warfare environment. The advantages MUOS provides will help the warfighter compete, deter and win on the battlefield.”
MUOS supports US arctic strategy
MUOS extends UHF communications further into polar regions than ever before, surpassing its original 65-degree latitude north/south requirement, reaching as far as 89.5 degrees latitude north – about 30 miles from the pole – during testing.
The transfer of megabyte data files has been demonstrated in the Arctic as part of the radio testing laboratory that make up the soldier’s network. As part of the Navy’s Ice Exercise (ICEX) program, MUOS satellites have already provided nearly 150 hours of secure data connections.
With melting of the ARCTIC, this capability shall support the growth in shipping, tourism, resource exploration, and search and rescue, as well as defense needs. Arctic Capabilities Assessment Working Group (ACAWG) had identified four capabilities Areas Communications, Maritime domain awareness, Infrastructure and Presence.
The Mobile User Objective Systems is the Defense Department’s next-generation narrowband military satellite communications system. MUOS includes a satellite constellation of four operational satellites with one on-orbit spare, a ground control and network management system, and a new waveform for user terminals. The ground system includes the transport, network management, satellite control and associated infrastructure to both fly the satellites and manage users’ communications.
Today, narrowband UHF communications is used by every combatant command in aircraft, ships, submarines, ground vehicles, as well as by troops in the field and special operations. It will support a worldwide, multiservice population of UHF band users, providing increased communications capabilities to smaller terminals while still supporting interoperability with legacy terminals. MUOS is designed to support users that require mobility, high data rates and improved operational availability.
MUOS is a system consisting of five satellites, four ground stations across the globe, a network management system and an integrated WCDMA waveform. The first four MUOS satellites are already operational via their legacy payloads, providing UHF satellite communications (SATCOM) for the DoD and mitigating potential gaps in UHF communications capabilities.
The four ground segment systems located in Australia, Hawaii, Virginia and Europe, connect users on the ground with the MUOS satellites and route the calls. The ground system also provides control and management of each of the satellites. The fiber optic terrestrial network connects all four ground stations (radio access facilities).
MUOS 5 satellite is now delivering secure, Beyond-Line-Of-Sight (BLOS) communications to troops with legacy Ultra High Frequency (UHF) radios. MUOS network users will be able to talk direct to, text and transfer mission data amongst any other MUOS users around the world beyond line-of- sight. Previously UHF satellite communication systems users could only ‘talk’ as long as they are under the coverage footprint of the same satellite.
MUOS adapts a commercial third generation Wideband Code Division Multiple Access cellular phone network architecture and combines it with geosynchronous satellites to provide a new and more capable UHF system. Eventually, legacy narrowband UHF communications will transition to next-generation Wideband Code Division Multiple Access (WCDMA) capabilities provided by MUOS. To facilitate that transition, Lockheed Martin intentionally designed MUOS with two communications payloads: one supporting the faster Wideband Code Division Multiple Access and another that retrofits the legacy system — ultra-high-frequency satellites that power the Ultra High Frequency Follow-On — to these updated standards.
Naval Satellite Operations Center (NAVSOC) officials have also accepted full operation control of the fifth Mobile User Objective System (MUOS) satellite from Lockheed Martin and the Navy’s Communications Satellite Program Office. This milestone was followed by the completion of the MUOS-5 satellite’s on-orbit testing and delivery of all operational products needed to “fly” the satellite.
Each MUOS satellite uses a multibeam antenna (MBA) for both transmission and reception of the MUOS WCDMA signals that significantly increases the number of users and traffic the system can support. The MBA forms 16 beams that cover the entire footprint of the satellite. Harris built 10 multiple-beam reflectors for the MUOS constellation, two per satellite – a 14-meter diameter unit for operation, and a 5.4-meter diameter unit for legacy operations. The onboard two unfurlable antenna gold mesh reflectors are secured to the satellite by Harris precision booms.
MUOS_1 was launched in Feb 2012; MUOS-2 was launched from Cape Canaveral Airforce station in July 2013. MUOS-3 that was successfully launched in Jan 2015, while MUOS-4 was launched in Sep 2015 . Originally launched on June 24, 2016, MUOS 5 experienced an anomaly with its orbit raising propulsion system on its way to geosynchronous orbit. The Navy and Lockheed Martin engineering teams were able to isolate the issue and deliver MUOS to operational orbit using alternative propulsion. The most powerful configuration of United Launch Alliance’s Atlas 5 rocket family is used to launch the MUOS satellites, which weigh nearly 15,000 pounds fueled for liftoff.
Each MUOS satellite carries a legacy payload, which is the equivalent of one UHF satellite’s capacity and capability, and the Wideband Code Division Multiple Access (WCDMA), the 3G cellular technology that will increase available narrowband satellite communications (satcom) channels.
MUOS uses Internet Protocol Version 4 and 6 (IPv4/IPv6) to give the warfighter global roaming connectivity to the Global Information Grid. The system represents a paradigm shift in UHF SATCOM from circuit-based, assigned networks to on-demand, global IP-based, net-centric networks.
It adapts a commercial third-generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone network architecture over geosynchronous satellites (in place of cell towers). “The MUOS Wideband Code Division Multiple Access (WCDMA) system provides significantly increased capacity and coverage, superior voice quality and Internet-like capabilities, enabling warfighters the flexibility to better communicate what they need to, when they need to,” said Capt. Joe Kan, program manager for the Navy Communications Satellite Program Office (PMW 146).
The MUOS also has access to the Non-secure Internet Protocol (IP) Router Network (NIPRNet), the Secure Internet Protocol Router Network (SIPRNet), and the Defense Switched Network (DSN), and enables communication between itself and 3G WCDMA, as well as legacy systems from an end-to-end perspective.
US Navy nanosatellite to boost UHF communications for polar regions
The US Navy has launched a nanosatellite from the Vandenberg Air Force Base (AFB) in California that is intended to expand the range of ultra-high frequency (UHF) communications into the polar regions. Known as the Integrated Communications Extension Capability (ICE-Cap), with aim to demonstrate the ability of low-Earth orbit satellites in expanding coverage of the Mobile User Objective System (MUOS) and conventional ultra-high frequency (UHF) follow-on (UFO) satellite constellations to the polar regions.
US Navy PEO Space Systems Communications Satellite Program Office programme manager captain Chris DeSena said: “This is a force multiplier. We are delivering warfighting capability that naval forces and their partners need to compete, deter and win. “The Arctic portion of maritime domain is becoming more active and important, and MUOS and ICE-Cap help ensure we have advantages in any challenges we might face there.”
The ICE-Cap nanosatellite will serve as a relay to the existing MUOS constellation. Based on its orbit, the satellite will extend communications into the polar regions for mobile forces. Built by the US Navy, the smaller satellites will act as calibration targets and technology demonstrations that would help enhance their capabilities to track small objects in space. In addition, the nanosatellites will host different combinations of radio frequency reflectors that reflect radar for increased space-object tracking and optical reflectors that are used to reflect lasers for the accurate measurement of satellite altitude.
PEO Space Systems Science and Technology assistant programme manager lieutenant commander Shawn Kocis said: “The development and launch of these four nanosatellites demonstrates the navy’s interest in leveraging the significant growth and private-sector investment in disruptive, new-space technologies aimed at driving down the costs of developing, building, launching and operating constellations of small satellites, increasing access to space.”
Integrated with manpack radios and tactical communication network
Once MUOS is declared operational, the number of MUOS users is expected to grow rapidly. Already, more than 55,000 currently fielded radio terminals can be upgraded to be MUOS-compatible, with many of them requiring just a software upgrade.
The U.S. Air Force Research Laboratory (AFRL) has conducted two weeks of MUOS ground and airborne testing successfully using the Rockwell Collins ARC-210 radio.
General Dynamics has received a contract from the U.S. Army to support upgrades to the Mobile User Objective System (MUOS) waveform used in the Army’s AN/PRC-155 two-channel MUOS-Manpack radios. U.S. Special Operations Command has given Harris Corporation an order for additional Falcon III radios for its wideband tactical communications network. The radios to be supplied under the $27 million order are the AN/PRC-117G manpack radio system and the AN/PRC-152A handheld radio system. Both are ready for use with the military’s Mobile User Objective System, or MUOS.
General Dynamics Mission Systems (GDMS) announced in Dec 2019 that it has been awarded a $731.8 million cost-plus-award-fee and firm-fixed-price indefinite delivery/indefinite quantity sole-source contract for the Mobile User Objective System (MUOS) ground system sustainment. GDMS provides the integrated ground segments for MUOS, which will soon provide secure cell phone-like communications for warfighters on the move. The contract was awarded by the U.S. Navy on November 8.
“MUOS will provide our warfighters with the ability to communicate securely, anywhere, anytime, with voice clarity and data transmission speed similar to using a civilian cellphone,” says Manny Mora, vice president and general manager for the Space and Intelligence Systems line of business at GDMS. “This capability delivers a whole new level of connectivity for troops in the field.”
Harris Corporation has reported that it successfully conducted satellite communications calls with two Falcon 3 AN/PRC-117G tactical radios using the Mobile User Objective System (MUOS) waveform. The demonstration validated the multiband manpack radio’s ability to run the narrowband MUOS service with a software-only upgrade.
Rockwell Collins awarded first long-term contract with DoD to provide MUOS SATCOM-capable airborne radios
Rockwell Collins was awarded the first long-term contract with the U.S. Department of Defense (DoD) to supply Mobile User Objective System (MUOS)-capable airborne radios and ancillaries for DoD platforms including fixed and rotary-wing aircraft, ships and ground installations.
“This is the next big step in arming warfighters with next-generation communications capabilities including those available through MUOS, which brings greater overall capacity and signal quality for high reliability when it’s needed most,” said Troy Brunk, vice president and general manager, Communication, Navigation and Electronic Warfare Solutions for Rockwell Collins.
The ARC-210 RT-2036(C) can utilize the MUOS network to provide military forces with worldwide, crystal-clear voice, video and mission data over a secure high-speed Internet Protocol-based system. The radio is also part of Rockwell Collins’ TruNet™ family of products that ensures secure connectivity between ground and airborne units.
As the sixth-generation solution, the ARC-210 RT-2036(C) features a software-defined radio architecture enabling multiple legacy and advanced waveforms, high-speed mobile ad hoc networking and beyond-line-of-sight connectivity capabilities. It will join the more than 45,000 highly-reliable ARC-210 radios currently fielded across the globe on more than 180 platforms
Fixed and portable SATCOM antennas
TACO Antenna currently produces UHF SATCOM antennas for both portable and fixed ground station applications. These antennas are both MUOS and Legacy/UFO compatible. Our portable/manpack antenna is easily carried by an individual and quickly deployed in under 30 seconds. Its performance provides the user a peak gain of 11dbic covering the full UHF TACSAT (Tactical Satellite) frequency band of 240-400MHz. This is a single piece unit with no additional parts. Its design is lightweight, modular, and compact, said Jeff Kunkle, Global Business Development.
“Our fixed station UHF SATCOM antennas are available in several models offering slightly different frequency coverage starting at 225MHz up to 520MHz and gain performance up to a peak gain of 15dbic. They feature a 2-piece ground plane with mesh design for reduced wind loading which assemble with no tools required. Their construction is rugged and reliable with additional mounting hardware available for either a mast mounted application or a tripod. Through our partner, SystemWare Europe, we can also provide Electrical Pan & Tilt positioners for more complex networked antenna systems where bearings can be changed remotely by the user.”
Mobile User Objective System Dynamic Scanning Improvement
As with any Department of Defense (DoD) radio system, radio frequency spectrum is shared and there is always the increased possibility of mutual or co-site interference. For MUOS capable radios, there are three types of interference mitigated by Spectrum Adaptation (SA): first, the MUOS radio transmission interference with the reception of non-MUOS radios (commonly called victims); second, interference to the satellite caused by other ground-based radios operating in the MUOS radio uplink frequency bands; and third, interference with the MUOS radio reception caused by non-MUOS radios operating locally within the MUOS radio’s receive carrier.
Navy launched SBIR with the objective to develop a second-generation spectrally adaptive dynamic scanning algorithm to improve Mobile User Objective System (MUOS) Wideband Code Division Multiple Access (WCDMA) capable terminal UHF transmission efficiency and co-sharing spectrum supportability.
The principal approach to defining interference limits within the Ultra High Frequency (UHF) bands is defined in the National Telecommunications and Information Administration (NTIA) Redbook. Typical narrow band radios have an equivalent isotropically radiated power (EIRP) in the 10 to 100 watt range. Applying the National Telecommunications and Information Administration (NTIA) Redbook criterion, the required out-of-band emission must be in a range no greater than -25dBW to -15dBW, with spurious emissions no larger than -43dBW.
Narrow band radios must comply with this Spectral Emission Mask to avoid having additional coordination requirements imposed upon it. Currently, the MUOS spectrally adaptive waveform transmits in the UHF (300 MHz – 320 MHz) band (20 MHz with 5 MHz distinct and separate channel) – equivalent to multi-carrier WCDMA. To avoid and protect other users within the transmitted band, the MUOS waveform is designed with the capability to scan the transmitted band, determine the presence of a victim signal (based on the pre-determined threshold), and then create RF masks in the amplifier and mask out the transmitted band. The algorithm employed in this case is a modified Discrete Fourier Transform (mDFT) using a polyphaser filterbank technique and amplified further.
The envisioned second-generation spectrally adaptive algorithm would improve the frequency resolution, achievable notch depth, minimum notch bandwidth, computation cost, and design flexibility. From there, the algorithm would be implemented into a design suitable for incorporation with the MUOS waveform software. The goal for notching bandwidth is to reduce it to 25 kiloHertz or smaller per bin. The goal for notch depth is at least 27 decibels with an objective of 30 or more. The improved notching capability must require the same or less computational complexity in order to allow for software-only updates to existing radios.
GAO report released in Sep 2021 identified gaps in MUOS system fielding
DOD has invested $7.4 billion to develop, build, and begin delivering MUOS. However, longstanding gaps between the fielding of the satellite system and compatible user terminals have limited DOD’s ability to fully use the system. The Department of Defense (DOD) is not using the full capabilities of its latest ultra high frequency (narrowband) military satellite communications system, the Mobile User Objective System (MUOS). MUOS provides secure communications less vulnerable to weather conditions or other potential impediments.
The full constellation of MUOS satellites has been on orbit for over 4 years, but DOD has not been able to use the system’s advanced capabilities—such as its 10-fold increase in communications capacity. A key reason is the military services’ delayed delivery of compatible radio terminals to users. DOD is funding and developing plans to accelerate procurement and delivery of these terminals.
DOD faces other challenges to its narrowband communications capabilities.
- In the near term, users continue to rely on the communications system that preceded MUOS, which is oversubscribed and will remain so while DOD works to field terminals and transition to MUOS. DOD has not explored and adopted narrowband communication options, which, if implemented, could help to meet unmet near-term communication needs.
- In the longer term, the five MUOS satellites that are on orbit have limited design lives. DOD plans to buy and launch additional satellites to sustain the constellation’s availability, but without the legacy capability of the older system.
GAO recommends DOD (1) explore and implement an option for narrowband satellite communications capabilities to meet near-term needs, and (2) reexamine its future narrowband satellite needs. DOD concurred with our recommendations and provided comments, which we incorporated as appropriate.