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Subterranean Wireless Communications for Counter-WMD Missions


OUSD (R&E) MODERNIZATION PRIORITY: 5G, General Warfighting Requirements (GWR); Network Command, Control and Communications; Cybersecurity


TECHNOLOGY AREA(S): Electronics;Information Systems


OBJECTIVE: Investigate novel means to provide practical wireless communications which outperform traditional free-space radio frequency (RF) communications in subterranean environments during DoD missions.  Characterize technology performance in underground spaces, especially man-made underground facilities typical of those used for production, storage, and deployment of weapons of mass destruction (WMDs).  Demonstrate the ability of the technology to be used for remote operation of multiple robotic systems in an environment typifying an underground facility used for WMD production, storage, or use.


DESCRIPTION: Traditional wireless communications links (RF and non-RF) suffer a number of impairments when used in subterranean spaces.  The Army Techniques Publication for subterranean operations acknowledges this, stating:


"Wireless communications [in subterranean spaces] are usually very limited. These include within the [subterranean] facility, subterranean to surface (vice versa), and potentially even surface to surface near a subterranean facility due to excessive noise, confusion, depth (overburden), confined space acoustics, little to no light, combined with surface terrain that is usually restrictive and with limited lines of sight. Strained communications, degraded global positioning systems, confined space in unknown terrain, and other difficult environmental factors make navigation, command and control, and even fratricide prevention measures extremely difficult. [1]"


Underground facilities provide concealment and protection for an array of activities conducted by US adversaries, including production, storage, and deployment of WMDs.  These facilities have proliferated globally, with “hundreds” being acknowledged to exist at the turn of the century, and many more being constructed.  Their multitude has created a number of challenges which the DoD has made a priority to solve. [2]   The problem of communicating in sprawling underground facilities while conducting counter-WMD operations is one such challenge, the solution to which currently relies on conventional free-space RF radio links.


While above-ground radio links are ubiquitous, well understood, and can be accurately modeled in most cases, RF propagation underground is not well understood, in part because it is less commonly needed and also because it is highly dependent on the geometry and electrical properties of a given subterranean environment. [3]   The variable and unknown nature of adversary subterranean facilities greatly inhibits the ability of engineers to optimize communication links for these environments, and leads to conventional radio links being repurposed without significant modification for use during subterranean operations.  This, combined with the impacts of tunnel curvature, corners, intersections, and discontinuities, results in greatly reduced and highly variable radio link performance in subterranean environments. [4]


Missions conducted by DoD personnel in subterranean environments require the real-time exchange of substantial amounts of information such as voice, video, and sensor data among personnel, sensors, and robotic systems.  Accomplishing this with traditional RF radio links requires the use of relay nodes, which may be either static or mobile, and may be separate from or part of the robotic systems being used.  Creating an RF communications network within a large underground facility requires the use of a substantial number of network nodes, as well as the means to command and the logistics to deploy them.  A method of communicating in subterranean environments which is not reliant on traditional RF propagation, and which reduced the operational and logistics burdens on the operator, would significantly contribute to the success of operations conducted in underground facilities.


Such a novel solution may rely on the innovative use of a number of physical phenomena (optical, magnetic, plasmonic, acoustic, etc.) to transmit and receive information, and may also leverage infrastructure typically found in underground facilities.  Solutions may require a multidisciplinary approach to combine phenomena in order to account for the impacts of dust, smoke, loud noises, illuminators, and other link impairments that may be encountered during DoD operations.  Technology developed under this SBIR topic would be invaluable to DoD groups conducting operations in underground facilities, as well as those operating in dense, urban environments, which also are affected by impaired RF propagation.  The nature of a non-traditional, non-RF communications capability also lends itself to many other military applications, especially those requiring a low probability of detection (LPD) such as unattended ground sensors, robotic systems, data exfiltration, and intra-squad communications, as well as use in systems which are susceptible to conventional electronic warfare attacks.


PHASE I: The Phase I deliverables are a report and proof of concept demonstrating point-to-point information exchange using novel means of wireless communications as described above.  The performer shall characterize basic properties of the communications link in a representative environment, including throughput, latency, and bit error rate as a function of transmitter/receiver separation distance in line-of-sight and non-line-of-sight configurations.  The report shall discuss the advantages/disadvantages of the proposed approach, characterization data & metrics, potential network configurations, and suggested applications beyond subterranean communications.


PHASE II: The Phase II deliverable is a final report and final proof of concept demonstration of 3 small unmanned ground vehicles (sUGVs) being simultaneously operated in a relevant environment via the novel wireless communications network developed during this phase.  The performer shall execute all integration necessary to remotely control the sUGVs during this phase, and shall characterize the operational utility of the network by conducting simulated, simplified counter-WMD scenarios in a relevant environment and assessing mission outcomes.  The performer shall also characterize performance of the communications link in the presence of environmental impairments, as applicable.  The performer shall continue to measure performance based on characterization methods developed in Phase I.  The final report shall discuss the advantages and disadvantages of the technology, characterization data, and potential use cases beyond subterranean environments.  The final report shall also outline a fieldable configuration of the technology.


PHASE III DUAL USE APPLICATIONS: During Phase III, the performer would develop and produce fieldable prototypes using accepted systems engineering practices to ensure satisfaction of functional requirements and proper management of system configuration.  The performer would also enable preliminary usage by DoD customers, including DTRA RD-CX and counter-WMD stakeholders, and develop configurations for other DoD systems requiring LPD communication solutions.  Although additional funding may be provided through DoD sources, the awardee should look to other public or private sector funding sources for assistance with transition and commercialization.



  1. US Department of the Army, Army Techniques Publication 3-21.51: Subterranean Operations (2019).  Accessible at: 3-21x51 FINAL WEB.pdf
  2. The MITRE Corporation, JASON Report: Characterization of Underground Facilities (1999).  Accessible at:
  3. IEEE Antennas & Propagation Magazine, RF Propagation in Mines and Tunnels (2015).  Accessible with subscription at:
  4. Aerospace Conference, A Self-Deployed Multi-Channel Wireless Communications System for Subterranean Robots (2020).  Accessible with subscription at:


KEYWORDS: Subterranean, Communications, Underground Facilities, UGF, Low Probability of Detection, Low Probability of Intercept, LPI, LPD

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