OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Integrated Network Systems-of-Systems The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Utilize Canonical Correlation Analysis (CCA) to achieve high levels of interference suppression for tactical communications which supports underlay wireless communications for military networks. DESCRIPTION: The Army communications networks need to operate in a congested and contested electromagnetic spectrum (EMS) environment. The tactical radio receiver in such environments may face significant co-channel interference (significantly higher than the desired received signal level). The interference may result from other EMS users, such as radio stations or radars, or other interferers such as Electronic Warfare (EW) systems. One traditional approach to sustain resilient communications in such environments is spread-spectrum communications or high-coded communications that takes advantage of the capacity vs. Low Probability of Detection (LPD) and Anti Jam (AJ) performance trades space. This approach requires significant channel bandwidth and treats the interference as noise which cannot be excised from the receiver. However, recognizing that interference is not thermal noise, this topic is looking for solutions (e.g., CCA, Singular Value Decomposition, etc) that would enable operation of communications links in the presence of considerable co-channel interference. In cognitive radio literature, the ability to operate a link in the presence of a primary user at sufficiently low power to avoid interference with the primary user is called underlay communications. In the military context, underlay communications have many benefits, including improved spectrum efficiency, improved covertness and improved resistance to interference. The key innovation needed is the ability to operate an underlay network at capacity that is significantly higher than would be expected if the interference was treated as noise. The technology solution should be a physical layer design that supports tactically relevant bandwidths and should be a single-antenna transmitter with single or multiple antenna receiver. The maximum number of receive antennas is four. Also, it is important that the performance of the link not suffer any sharp degradation if the primary signal varies in power or behaves intermittently. The underlay system cannot assume any prior knowledge of the primary signal. PHASE I: The feasibility study should outline the theory of operation, describe relevant signal processing algorithms, any limiting factors and simulation results. The study should also address how the proposed physical layer may be integrated with higher-layer protocols (e.g., layer 3, etc.). The algorithm allows the underlay communications signal the ability to maintain an SER/BER performance with interference degradation no more than a factor of six compared to no interference at the same SNR. PHASE II: Phase II should deliver a functioning underlay link physical layer prototype implemented on a widely used software defined radio (SDR) platform. The prototype should be physically provided to perform independent lab-based assessment of link performance using a set of primary signals selected. During Phase II, it is not required for the demodulation and decoding to occur in real time. For proof of concept, post-processing of the received digital signal samples is a viable approach. An important element in Phase II is the interaction between testing and iterative software refinement by the performer. Therefore, the first iteration of the prototype should be available at least three months before the conclusion of Phase II The algorithm allows the underlay communications signal the ability to maintain an SER/BER performance with interference degradation no more than a factor of five compared to no interference at the same SNR. PHASE III DUAL USE APPLICATIONS: Phase III should deliver a real-time implementation of the algorithm using hardware acceleration if necessary. The algorithm allows the underlay communications signal the ability to maintain an SER/BER performance with interference degradation no more than a factor of five compared to no interference at the same SNR. REFERENCES: M. S. Ibrahim and N. D. Sidiropoulos, "Blind Carbon Copy on Dirty Paper: Seamless Spectrum Underlay via Canonical Correlation Analysis," 2021 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2021, pp. 8123-8127, doi: 10.1109/ICASSP39728.2021.9414621.; M. S. Ibrahim, P. Karakasis, and N. D. Sidiropoulos, A Simple and Practical Underlay Scheme for Short-range Secondary Communication , in IEEE Transactions on Wireless Communications, vol. 21, no. 11, pp. 9990-10004, Nov. 2022, doi: 10.1109/TWC.2022.3181618.; M. S. Ibrahim, and N. D. Sidiropoulos, Cell-Edge Interferometry: Reliable Detection of Unknown Cell-Edge Users via Canonical Correlation Analysis, at the 20th IEEE SPAWC, Cannes, France, July 2020; M. S. Ibrahim, and N. D. Sidiropoulos, Reliable Detection of Unknown Cell-Edge Users via Canonical Correlation Analysis'', IEEE Transactions on Wireless Comm., vol. 19, Mar. 2020.; M. S rensen, C. I. Kanatsoulis and N. D. Sidiropoulos, "Generalized Canonical Correlation Analysis: A Subspace Intersection Approach," in IEEE Transactions on Signal Processing, vol. 69, pp. 2452-2467, 2021, doi: 10.1109/TSP.2021.3061218.; M. S. Ibrahim, and N. D. Sidiropoulos, Underlay Scheme for Short-range Secondary Communication , US Patent pending.; M. S. Ibrahim, A. Hussain and N. D. Sidiropoulos, "A Novel Linear Precoder Design for Reliable UL/DL Detection in TDD Cellular Networks," in IEEE Transactions on Communications, vol. 70, no. 12, pp. 8167-8180, Dec. 2022, doi: 10.1109/TCOMM.2022.3217129.; M. S. Ibrahim, P. A. Karakasis and N. D. Sidiropoulos, "A link between Multiuser MMSE and Canonical Correlation Analysis," in IEEE Wireless Communications Letters, doi: 10.1109/LWC.2023.3319292. KEYWORDS: Underlay networks, spectrum efficiency, congested spectrum, contested spectrum, Symbol Error Rate (SER), Bit Error Rate (BER), Signal to Noise (SNR).
