N112-170 TITLE: Wideband Radio Local Interference Optimization Techniques

TECHNOLOGY AREAS: Electronics

ACQUISITION PROGRAM: Mobile User Objective System (MUOS), ACAT I

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports):  This topic is "ITAR Restricted."  The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data.  Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Develop methods and algorithms for mitigating narrowband interference in wideband UHF SATCOM channels.

DESCRIPTION: Interference is one of the major impediments to Satellite Communications (SATCOM). Interference comes from sporadic unregulated RF transmission such as pirate radio and TV stations or other devices, as well as other sources. When strong interference is inside SATCOM channels, signals may be corrupted so that mission critical communications via satellite are disrupted. This impediment exists in both commercial and military systems.

Various methods and algorithms for mitigation of interference in narrowband (5 kHz and 25 kHz) UHF SATCOM systems have been proposed. However, narrowband interference mitigation in wideband (5 MHz) channels remains a difficult task. Coding and interleaving can only achieve limited mitigation. If some information about the interference is available, e.g. its modulation format, then one could try to estimate the wideband interference and subtract it from the received signal. If no prior information is available, however, mitigation of interference seems very difficult. This topic solicits innovative ideas for narrowband interference mitigation in SATCOM channels without prior knowledge of the interference. For example, time and/or spatial diversity could be considered.

The developed system should operate as a "black box", which sits between the original SATCOM antenna system and SATCOM receiver. The system should be able to mitigate multiple narrowband interferers, located anywhere within the UHF SATCOM frequency range. Some interferers will be relatively small (~25 kHz) while others may be larger (~300+ kHz). The interferers may appear and disappear sporadically, and the system should be able to adapt quickly to mitigate emerging interference with minimal communication down time. For signals received from the satellite, the mitigation system should be transparent to the receiver, simply passing the SATCOM signal from the antenna output to the receiver input with interference removed in real time. The ideal system would require no operating parameter information from the antenna or receiver.

PHASE I: Develop methods and algorithms for mitigating narrowband interference in wideband UHF SATCOM channels.

Tasks under this phase could include:
� Develop methods and algorithms
� Validate the proposed approach by computer simulation
� Estimate performance metrics such as bit error rate (BER), the effect of interference bandwidth and strength on BER, and adaptation time for effective mitigation
� Create an initial design of a prototype system

PHASE II: Implement and demonstrate the method(s) or algorithm(s) in a prototype device.

Tasks under this phase could include:
� Implement the new design and demonstrate its performance against expectations
� Evaluate measured performance characteristics versus expectations and make design/process adjustments as necessary
� Using a SATCOM simulator and/or actual over-the-air satellite signal, demonstrate the operation of the system and its effectiveness in mitigating various interference scenarios in UHF SATCOM channels.

PHASE III: This phase will focus on further testing and integrating the technology with existing military SATCOM systems such as the Mobile User Objective System (MUOS).

PRIVATE SECTOR COMMERCIAL POTENTIAL DUAL-USE APPLICATIONS: The technologies produced under this program could be applied to any commercial SATCOM channels/systems that experience similar kinds of interference.

REFERENCES:
1. Naval Open Architecture. https://acc.dau.mil/oa

2. MacMullen, S.J. Strachan, B., "Interference on UHF SATCOM channels," MILCOM 1999

3. L Castanet, A Bolea-Alamañac, M Bousquet, "Interference and fade mitigation techniques for Ka and Q/V band satellite communication systems," Proc. 2nd International Workshop of COST Action, 2003

4. Kohl, M.; Wiesler, A.; Jondral, F., "Suppression of interferences over SATCOM links with transparent transponders," IEEE PIMRC conference, 1997

5. Oak, A. and Jen, T. "MUOS QoS Offerings and the Impact on Future UHF SATCOM". MILCOM 2006

KEYWORDS: MUOS, SATCOM, UFO, Interference Mitigation, Wideband

** TOPIC AUTHOR (TPOC) **

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