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DARPA, is proposing a new Mosaic Warfare strategy for evolving multidomain battlefield. Dr. Timothy Grayson, Director of the Strategic Technology Office is advocating for a “system of systems” approach that he’s calling mosaic warfare: the ability to piece together different systems to build new overarching warfighting capabilities. DARPA’s Strategic Technology Office seeks to turn complexity into a powerful new asymmetric weapon via rapidly composable networks of low-cost sensors, multi-domain command and control nodes, and cooperative manned and unmanned systems. Using the concept of a mosaic, which comprises many smaller individual pieces, STO is applying “mosaic warfare” to link together lower-cost, less complex systems in a vast number of ways to create desired, interwoven effects tailored to any scenario.
“In the Mosaic concept, platforms are ‘decomposed’ into their smallest practical functions, creating collaborative ‘nodes’ in a networked kill web that is highly resilient, and can remain operationally effective even if an adversary destroys some of it,” explained David Deptula, Mitchell’s dean, and a member of the Breaking Defense Board of Contributors.
The collaboration between nodes depends on the resilient long-range communications which require antennas on all these nodes. Antennas are our electronic eyes and ears on the world. They play a very important role in mobile networks, satellite communications systems, military communications, radars, and electronic warfare by transforming a Radiofrequency ( RF) signal, traveling on a conductor, into an electromagnetic wave in free space and vice versa. The RF current flowing through the antenna produces electromagnetic waves which radiate into the atmosphere.
Presently, troops in faraway locations require giant parabolic dishes, tall pole-mounted antennas, large antenna domes, and high-power amplifiers. Besides their significant weight, power, and cost (SWAP-C), these antennas present large visual and radio frequency (RF) signatures, are vulnerable to jamming, and constitute a single point of failure. The United States Defense Advanced Research Projects Agency (DARPA) has introduced a new program to eliminate large, power-hungry antennas for better long-range tactical communications for US troops in remote locations.
Distributed beamforming
With recent advancements in both size and power efficient computing, the concept of the ubiquitous wireless sensor network has quickly emerged as a legitimate research topic. It is now possible to have a large network of relatively small devices distributed over a large area, all with limited means of communications, and precious little power to spare for long-haul links. Significant research has been done on efficient routing algorithms, mutual information coding, and multi hop transmission schemes in an effort to reduce the amount of power required to transfer sensor data from the individual nodes in a network to a final destination where the data can be used.
In an effort to further reduce power consumption, the use of distributed phased arrays has come into focus as a method for nodes to collaborate in their transmissions, saving power overall during the data transfer. By cooperating, the nodes are able to emulate a traditional fixed array of antenna elements and achieve the same gains in terms of main lobe enhancement, side lobe reduction, and null pointing to improve the intended receiver’s SNR and remove the interference caused by unwanted transmitters. These arrays are called distributed smart antennas, or distributed beamformers, and have their own unique set of problems over fixed beamformers when it comes to ideal weight calculation.
Use of the term “distributed” has two distinct meanings in the sense of distributed beamforming. The first meaning indicates that the antennas of the array themselves are distributed over the receiving plane in some randomly structured fashion. This is a departure from traditional beam-forming literature, which relies on a strict, uniform placement of the antenna elements to reduce the complexity of the analysis through the removal of dependence on the individual locations of nodes within the arrays. When the nodes are no longer structured so nicely, the location of each element must be considered on its own, rather than simply considering the location of the array as a whole. In this scenario, the elements are still controlled by some central source; hence the locations, phase offsets, and transmit capabilities of each node are known quantities to be taken advantage of during ideal weight calculations.
The second meaning builds on the first, implying that the elements are not only distributed in terms of location, but are also independent processing units, such as with a wireless sensor network in a field. This second scenario severely limits the quantity and quality of information available to a beamformer. In this case, methods for determining ideal complex weights must distributed in the sense that they can be carried out by each node individually without sharing significant amounts of information. If the nodes were allowed to share the total amount of information about them-selves, such as through some pre-communication phase, the second scenario would collapse into the first, where ideal weights could be calculated based on the global information and disseminated through the network by a single cluster head.
DARPA Resilient Networked Distributed Mosaic Communications (RN DMC) program
To break this dependence on big antennas and amplifiers, DARPA recently announced the Resilient Networked Distributed Mosaic Communications (RN DMC) program. RN DMC aims to provide long-range communications through “mosaic” antennas composed of spatially distributed low SWaP-C transceiver elements or “tiles.” This approach replaces high-powered amplifiers and large directional antennas with mosaics of dispersed tile transceivers. Transmit power is distributed among the tiles, and gain is achieved through signal processing rather than by a physical antenna aperture to concentrate energy.
“This is a fundamentally different way to think about long-range tactical communications that supports DARPA’s Mosaic Warfare concept of busting monolithic systems and distributing capability for greater resilience at less expense,” said Paul Zablocky, program manager in DARPA’s Strategic Technology Office. “RN DMC seeks to develop a mobile, self-forming, self-healing mosaic antenna comprising numerous low-cost and low-power transceiver tiles that can be placed aboard ships, vehicles, unmanned and manned aircraft, and satellites, as well as individual squad members.”
In a traditional tactical communications system, a radio connects to a directional antenna through a physical cable or RF coupler. RN DMC, on the other hand, provides a physical communications connective layer that is independent of nearby tactical networks. This approach also will provide the relative positions for each local tile a squad leader with a tactical radio and an Android Tactical Assault Kit (ATAK) or other visualization tool to track the locations of his or her squad members — even in environments that deny use of the Global Positioning System (GPS).
The antenna mosaic concept could prove more robust against failure or attack since tiles are distributed across air, ground, and sea assets. Tiles also promise to be lower cost – targeted at $1,000 or less apiece – making individual tiles expendable without losing the mosaic antenna functionality.
DARPA researchers say the mosaic approach would work with unmodified military tactical radios and waveforms, and be affordable enough to be expendable. It also can be secure and available only to authorized users. Because spatial distribution allows for relatively low power from each tile, it is inherently low probability of detection compared to traditional transmitters. Furthermore, the approach will enable computing the relative position of each tile within a mosaic. Because there are several tiles involved that self-form into an array, the loss of individual tiles does not cause the entire array to fail.
“Powerful signal processing in a small, inexpensive form factor is the key enabling mosaic antenna technology,” Zablocky said. “We will leverage small form factor software-defined radios and radio frequency systems on a chip as well as previous DARPA research and development efforts that have validated the feasibility of basic distributed coherent radio transmissions.”
RN DMC includes three focus areas: system design, experimental performance validation, and operational architecture definition. The effort is divided into three planned phases, totaling 45 months.
Phase-one RN DMC performers will test long link capability in the laboratory, and in controlled outdoor long-range environments to validate the technology’s ability to operate over at least 31 miles. The test will have at least two tactical radios; two ground tactical waveforms and one satellite communications (SATCOM) waveform; and 10 SWaP-optimized mosaic tiles. Phase-two performers will refine their designs, and support a terrestrial test and a relay field test.
The terrestrial test will validate distributed-to-distributed coherent communications over a terrestrial link at least 0.6 miles long between two mosaic element antennas and will include static and moving user test cases. This test will be for about 10 months. The mosaic antennas will have at least ten tiles each — 20 tiles total — and the system will be tested with at least two tactical radios and two terrestrial tactical waveforms. This test will demonstrate an Army use case where two squads separated by about a mile could communicate through RN DMC technology.
A relay test exercise at the end of phase 2 will demonstrate a relay from a ground mosaic antenna to an airborne mosaic back down to a remote mosaic ground antenna about 62 miles away. The third phase will involve adapting RN DMC technology to U.S. military service needs, and will demonstrate at a service-led field exercise. The end of the third phase will include service-specific systems ready for experimentation, design documents, and performance assessments; as well as a field exercise.
DARPA Awards Silvus Up to $13.1M to Develop Distributed Beamforming Solution in March 2021
Silvus Technologies, Inc. (“Silvus”) announced the company has been awarded a contract worth up to $13.1 million as part of DARPA’s Resilient Networked Distributed Mosaic Communications (RN DMC) program. Under RN DMC, Silvus will develop a distributed beamforming/beamnulling solution to enable resilient, long-range terrestrial communications of up to 100km using multiple collaborative radios distributed over hundreds of meters.
RN DMC stems from DARPA’s investment in mosaic warfare, a concept in which large numbers of lower-cost systems, referred to as “tiles,” are deployed to perform complex mission functions in a coordinated fashion. By building a mosaic of inter-connected tiles, functions such as command and control, communications, and sensing can be performed with more resilience and higher performance.
Building on a proven track record of developing real-time solutions enabling distributed frequency and time synchronization, Silvus’ solution for RN DMC is dubbed Mosaic Scattered Wide-Area Resilient Network (MScWRN or M2N). M2N will enable spatially distributed beamforming and beamnulling with minimal communications required between tiles, resulting in mosaic clusters that are able to bridge large range gaps while seamlessly interoperating with the rest of a traditional Silvus mesh network.
“The reliability of long-range communications utilizing multiple radios distributed over large distances is a critical component in DARPA’s vision of mosaic warfare,” said Dr. Babak Daneshrad, Chief Executive Officer of Silvus. “The RN DMC program will enable the continued development of our M2N solution, and we look forward to demonstrating its matured operation.”
Perspecta Labs to Develop Radio Communications on DARPA Contract Worth $18.5M awarded in April 2021
Perspecta Inc.’s applied research arm Perspecta Labs has received a prime award for work on low-cost, resilient tactical radio communications under the Defense Advanced Research Projects Agency’s Resilient Networked Distributed Mosaic Communications, or RN DMC, program.
The contract, which represents new work for the company, has a potential total value of $18.5 million over a 45-month period of performance, if all options are exercised. “We are excited to design, develop and demonstrate low-cost, resilient long-range communications for challenging non-line-of-sight radio environments,” said Perspecta Labs President Petros Mouchtaris. “With innovative use of tiles, our solution will deliver a high-performance tactical radio communications solution which is flexible, robust and has significantly lower risk of detection, interference and jamming.”
The directional antennas and high-powered amplifiers currently used to support long-range tactical communications in remote areas are expensive and vulnerable to jamming and interference. The RN DMC program aims to deliver resilient, long-range tactical communications via self-forming, self-healing “mosaic” antennas made up of small, low power and cost transceiver elements (tiles) that can be hard-carried by warfighters and hosted on ground vehicles, high-altitude platforms and satellites. Perspecta Labs is to prototype, implement, test and validate an adaptive distributed array system solution that works with existing tactical radios and unmodified tactical waveforms.
References and Resources also include:
https://www.militaryaerospace.com/communications/article/14177403/communications-swap-transceivers
