Description:
TECHNOLOGY AREA(S): Info Systems
OBJECTIVE: Develop cost-effective smart modules and/or smart antennas that can be bolt-on or added to TCDL transceivers on multiple platforms to enable simultaneous TCDL links at the same band.
DESCRIPTION: Tactical Common Data Link (TCDL) supports omni-directional antennas. Omni directional antennas are lightweight and provide connectivity in all bearings. However, employing multiple frequency-separated omni-directional TCDL links in a congested and contested area results in waste of vital spectrum. Furthermore, those airborne assets carrying TCDL have an undesired vulnerability to unintended and intended interference. Due to advances in multiple-input-multiple-output (MIMO) radio [1], airborne line of sight MIMO [2], blind MIMO channel estimation [3,4], and blind interference mitigation [5], it is anticipated that a smart low-cost bolt-on module or a smart add-on antenna could increase spectral efficiency and reduce vulnerability to interference. A system that supports multiple TCDL links on the same frequency will need to have a simple applique on the TCDL transmit terminal and have a simple receive array to support spatial multiplexing. The TCDL links will need to maintain performance in when multiplex, thus, tight constraint should be imposed on the TCDL smart modules/antennas performance (e.g. 0.5 dB RF loss). Combining commercial-off-the-shelf (COTS) mixed signal devices, analog and digital signal processing techniques, and advanced antennas can provide attractive cost (<$10K) per module/antenna while enhancing operational spectral efficiency and interference resistance levels.
PHASE I: Phase I will study candidate designs for smart modules/antennas and their performance and anticipated SWAP-C for different con-ops. Phase I results should quantify the benefits of different approaches for varying link distances, interference levels, and scintillation environments using analysis and/or simulations, accounting for practical implementation constraints. Work with the government to identify the requirements for a Phase II demonstration.
PHASE II: Implement the selected technology in hardware and demonstrate the gains at an AFRL test range. Present a path toward optimizing SWAP-C. Show compatibility among demonstrator systems and legacy (in-use systems) radios.
PHASE III: Develop and deliver flight-qualified units with a complete RF system for transition to appropriate platforms. The product could be used in a variety of homeland security areas, such as border patrol and the Coast Guard.
REFERENCES:
1: M. J. Gans, "Aircraft free-space MIMO communications," in Proc. 43rd Asilomar Conf. on Signals, Systems and Computers, pp.663-666, Pacific Grove, CA, Nov. 1-4, 2009.
2: W. Su, J. D. Matyjas, M. J. Gans and S. Batalama, "Maximum Achievable Capacity in Airborne MIMO Communications with Arbitrary Alignments of Linear Transceiver Antenna Arrays," in IEEE Transactions on Wireless Communications, vol. 12, no. 11, pp. 5584-5593, November 2013. (Updated on 8/28/17)
3: E. Serpedin, A. Chevreuil, G. B. Giannakis and P. Loubaton, "Blind channel and carrier frequency offset estimation using periodic modulation precoders," in IEEE Transactions on Signal Processing, vol. 48, no. 8, pp. 2389-2405, Aug 2000. (Updated on 8/28/17)
4: A. K. Jagannatham and B. D. Rao, "Whitening-rotation-based semi-blind MIMO channel estimation," in IEEE Transactions on Signal Processing, vol. 54, no. 3, pp. 861-869, March 2006. (Updated on 8/28/17)
5: G. Okamoto and C. W. Chen, "Minimal complexity blind interference mitigation via Non-Eigen Decomposition beamforming," MILCOM 2008 - 2008 IEEE Military Communications Conference, San Diego, CA, 2008, pp. 1-7. (Updated on 8/28/17)
KEYWORDS: MIMO, Blind Channel Estimation, Spectral Efficiency
