Advanced Signal Processing for Wireless Communications Jerry Shapiro, Principal Investigator Problems:
The replacement of hard information binary block codes with soft-information-based turbo and low-density parity check codes changed point-to-point communications profoundly. Recent developments in communication theory make the time ripe for the development of soft-information-based networks. This project will attempt to solve pressing problems with current mobile ad hoc networks (MANETs) by developing simple networks of intelligent nodes capable of advanced signal processing.
Objectives:
We will make fundamental contributions to signal processing for wireless communication that have broad impacts in MANETs, sensor networks, special communications, and low probability of intercept/low probability of detection (LPI/LPD) communications. We will develop capacity-approaching rateless coding solutions, combine rateless coding with cooperative diversity to achieve high-performance wireless ad hoc networks, and combine rateless coding with LPI/LPD techniques to produce a high-throughput waveform.
Activities:
We will develop signal-processing-based physical layer solutions to increase throughput and to simplify the higher layers of the network protocol. This approach to wireless network design reduces overhead, increases spectral efficiency in bandwidth-limited environments, increases power efficiency in power-limited and secure communications, improves connectivity, reduces network complexity, and shortens session setup time. We will explore how these techniques might affect information assurance and security.
Impact:
We expect our research to change the way engineers view the design of both mobile and sensor ad hoc networks. Additionally, we expect this work to have great value to our traditional customer base in special communications. We will submit contributions to standards bodies so that military requirements relevant to our research can be included.
Approved for Public Release: 06-1225 Presentation [PDF]
Advanced Tactical Networking John Stine, Principal Investigator Problems:
The wireline networking paradigm has dominated R&D efforts to build wireless tactical networks, but it does not account for the spatial and spectral interdependence of RF communications and encourages the use of protocols that quickly consume channel capacity. These approaches remain inefficient in their use of spectrum, ineffective in delivering quality of service, and nearly incapable of exploiting the new physical layer technologies.
Objectives:
This project aims at creating a comprehensive set of protocols for wireless networking based on the wireless paradigm. We will determine how to predict connectivity, create location awareness and synchronization in a contention-based ad hoc network, and integrate networks built using the wireless paradigm with networks built using wireline paradigms. We will examine ways to engineer network performance, manage spectrum and waveform use, and establish trust amongst nodes.
Activities:
Our research will develop a comprehensive set of OPNET models to compare multiple different physical layers and protocol algorithms. We will create and evaluate algorithms for network synchronization, location awareness, propagation modeling, routing, information assurance, and spectrum management in ad hoc networks. We will also create a network operations management suite and link it with the OPNET simulation using an HLA interface.
Impact:
Our work will solve hard problems of ad hoc networking, such as protection against the adverse effects of hidden terminals, exposed terminals, and congestion, and support for quality of service, multicasting, and energy conservation. It will enable exploitation of special wireless technologies including channelization, code division multiple access, space division multiple access, smart antennas, and multiple input multiple output. It will enable real-time network operations management.
Approved for Public Release: 05-0434 Presentation [PDF]
Atmospheric Mitigation Techniques for Free-Space Optical Communication David Gervais, Principal Investigator Problems:
The atmosphere imposes many limitations on free-space optical communication (FSOC) links. By understanding and quantifying these limitations, we can develop mitigation strategies to overcome many of these limitations and extend the performance bounds for FSOC links.
Objectives:
We will construct and deliver a modeling and simulation tool to characterize the atmospheric channel for FSOC. By capturing the results from these simulations, we will be able to construct a laboratory setup designed to replicate aspects of the simulations and to model and test several mitigation strategies within a representative laboratory environment.
Activities:
A simulation tool will provide detailed models of clear-air turbulence and wave-optic propagation. Additional theoretical investigations of mitigation methodologies will be considered. The results collected and deduced from the investigations will be experimentally proven within a laboratory environment and will lead to the construction of an FSOC terminal. The terminal will optimize performance given user needs and the atmospheric channel response.
Impact:
As more and more government programs and assets migrate to FSOC, atmospheric modeling, simulation, and mitigation techniques will become dominant themes for critical application areas ranging from increased communications bandwidth to covert sensor networks. Through our research, MITRE will play a key role in extending the currently accepted bounds of FSOC usability and practicality for our sponsors.
Approved for Public Release: 04-1288 Presentation [PDF]
Cognitive Spectrum Use Bill Horne, Principal Investigator Problems:
Communications, navigation, and surveillance systems depend on transmitting, receiving, or measuring energy transferred through the multidimensional space constituting the electromagnetic spectrum. Network-centric warfare, emergency response, and other emerging operational concepts require automated, dynamic, and adaptive decision making for spectrum use not satisfied by current spectrum management techniques. Consequently, improving spectrum access and developing cognitive radio is a valuable research area.
Objectives:
The objective for this research is to develop spectrum-access architectures, algorithms, and radio device designs that utilize cognitive techniques to improve access to the electromagnetic spectrum. The scope of cognition includes: awareness of a system's context including policy, radiofrequency environment, and operational needs; the ability to make inferences based on the context and rules; and the ability to act.
Activities:
Utilizing a multi-disciplinary approach to improve spectrum access, the project will: (1) define architectures for conveying contextual awareness including policy and operational constraints; (2) develop radio designs including autonomous inference tools; (3) develop a spectrum ontology and inference engine based on semantic web and related cognitive techniques for decision making; and (4) apply economic optimization and authorization transaction techniques.
Impact:
This research will assist MITRE's sponsors to improve and automate spectrum utilization. This work can also maintain MITRE's continued leadership in spectrum and cognitive radio through publications, standards and technology organization participation, and improved staff skills. Finally, the research will provide knowledge that can be transferred to regulatory organizations, government agencies, and industry to develop new policy and design practices.
Approved for Public Release: 05-0422 Presentation [PDF]
Commercial Technologies for Tactical Radio (CTTR) Peter Weed, Principal Investigator Problems:
One challenging aspect of designing tactical radios for portability is energy consumption. The push to use software-defined-radio (SDR) components and the desire for ad hoc networking make this challenge even more difficult. Soldiers often need to communicate in conditions where self-interference introduced by multipath impairs reliable communications. Trying to overcome multipath with higher transmit power only compounds the energy use problem.
Objectives:
We will demonstrate improved energy efficiency by implementing key aspects of ongoing MITRE research into ad hoc network communications over non-line-of-sight (NLOS) terrain. In particular, we will use multiple-input/multiple-output (MIMO) signal processing techniques to reduce transmit power while maintaining a reliable radio link and will use the synchronous-collision-resolution (SCR) media access control (MAC) approach to conserve energy during opportunistic sleep periods.
Activities:
Most of this effort will involve developing signal processing Very High Speed Integrated Circuit Hardware Description Language (VHDL) code for a system-on-a-chip class field-programmable gate array (FPGA) and packet handling C code to run under the RT-Linux operating system. We also hope to integrate our custom transceiver onto an existing radio stack-up, translate MIMO research results into an FPGA implementation, and implement key SCR MAC approaches.
Impact:
The advanced signal processing techniques we plan to demonstrate may assist programs developing tactical radios -- especially those struggling with heat dissipation, size-weight-power, and reliable communications within an NLOS environment. MITRE research programs interested in over-the-air field demonstrations may benefit from the rapid prototyping capability we will provide with this battery-powered SDR platform.
Approved for Public Release: 06-1488 Presentation [PDF]
Control Based Mobile Ad Hoc Networks (CBMANET) Emaan Osman, Principal Investigator
Disruption Tolerant Networking (DTN) Robert C. Durst, Principal Investigator Problems:
Current visions of network-centric warfare depend on the use of Internet protocols. These protocols assume low latency, unconstrained power, and a network constantly connected end-to-end. While these assumptions may sometimes be valid, tactical and sensor networks frequently cannot provide this environment. The resultant disruptions and changes in round trip times either completely break Internet protocols or severely degrade their performance.
Objectives:
DARPA wishes to develop a robust and secure networking architecture and protocols that efficiently support both constantly and intermittently connected operations. Disruption Tolerant Networking (DTN) seeks to improve reliability and reduce latency by in-network store-and-forward, selective caching, and appropriate use of replication. DTN will allow applications to use a single interface to any type of network.
Activities:
We are finalizing the architecture and main protocol. We are conducting research and prototyping in reliable multicast, new methods of infrastructure security, and content-based addressing and caching. The project is extending the DTN reference implementation by adding external interfaces for DoD-specific enhancements. Additionally, we are working with the uniformed services to identify opportunities for early transition of this technology to operational use.
Impact:
DTN solves previously unsolved problems in network-centric warfare by providing efficient communications in and between connected and disrupted environments. MITRE functions as an integral part of the DTN research community through the Internet Research Task Force’s Delay Tolerant Research Group, is a coauthor of the current DTN architecture and protocol documents, and is defining the reference implementation's external interfaces.
Approved for Public Release: 07-0299 Presentation [PDF]
Host-Based Firewall with Dynamic Encryption Capability Kurt Sherman, Principal Investigator Problems:
There exists a Federal agency which supports hundreds of individual offices with absolute local autonomy and independence. The local authorities at each location consider the content and purpose of their network activity restricted and confidential. The wide area network which connects these enclaves does not provide end-to-end management in response to this privacy requirement. The resulting lack of robust network management makes it challenging, if not impossible, to deploy converged services such as VoIP throughout the agency enterprise.
Objectives:
This research effort will develop a transparent mechanism for ensuring that the payload of all network traffic is encrypted using government-accepted protocols and standards. This capability will be combined with host-based firewalls to secure the endpoints. Such a security model would provide confidentiality and eliminate the local authorities' privacy concerns associated with end-to-end network management.
Activities:
Key activities include the development of a system using open source software (OpenVPN) to dynamically encrypt traffic between hosts if the traffic is not natively encrypted. We will also develop a policy server capable of distributing appropriate rules and any necessary patches to client systems. This system will function with third party or original equipment manufacturer firewalls.
Impact:
The system will ensure the confidentiality of traffic content within the domain and mitigate insider threats. Deploying this system in conjunction with host-based firewalls will establish an additional layer to the "defense-in-depth" model that protects data both in transit and at rest. This additional security will benefit IPv6 networks where the elimination of Network Address Translation barriers will expose previously hidden hosts and systems.
Approved for Public Release: 07-0272 Presentation [PDF]
Information Theory for Mobile Ad Hoc Networks (ITMANET) Emaan Osman, Principal Investigator
Investigating Applications of Wireless Broadband for Airport Operations Izabela Gheorghisor, Principal Investigator Problems:
Data transmissions that require broadband capabilities are rapidly increasing in the airport area. Running new cable or fiber, especially under runways, carries high installation costs. Airports also need to provide broadband connectivity to mobile users on the airport surface. Therefore, the National Airspace System needs wireless broadband networks to support aeronautical applications on the airport surface.
Objectives:
The first objective for this research is to investigate potential airport surface applications that could be supported by a wireless broadband network. The second objective is to evaluate the performance of such a broadband network in supporting a given set of aeronautical applications.
Activities:
This project will analyze the requirements of potential aeronautical applications that could be supported by a wireless broadband network and study the mechanisms for providing various levels of service to network users. We will evaluate modeling and simulation tools for analyzing network performance, build an aeronautical scenario, and evaluate the performance of a broadband network that would support communication goals.
Impact:
This research will assist the FAA in evaluating the performance of future wireless broadband networks for the airport environment. These networks will support high-data-rate applications to improve airport situational awareness, security, and efficiency, and may reduce the cost of infrastructure improvements in the airport area. Broadband networks will also support efficient use of aviation spectrum -- an issue that concerns government policy makers.
Approved for Public Release: 07-0101 Presentation [PDF]
Near Term Tactical IP Enhancements Chris Niessen, Principal Investigator Problems:
As the Department of Defense works to extend the Internet Protocol (IP) network to all users, it is important that tactical IP links be used effectively to carry as much of the most important data as possible. This requires the ability to classify and prioritize existing flows. The network itself is composed of heterogeneous links that need to be monitored.
Objectives:
This project will investigate and prototype solutions for a set of near-term critical issues, including maximizing link bandwidth via optimization of the IP over Legacy (IPoL) radio driver, determining and applying quality of service (QoS) for traffic flows, and investigating link-independent monitoring mechanisms. Dynamic Link Management implementations will also be investigated to assess integration with QoS and IPoL solutions.
Activities:
This project will investigate approaches to QoS, and will prototype a traffic analysis and marking engine. Additionally, the IPoL driver will be enhanced to adjust dynamic link parameters. Methods for monitoring and reporting the state of heterogeneous links will be investigated. The end result will be a set of tools that improve the performance of emerging tactical IP networks.
Impact:
Enabling effective use of emerging IP links provides both short-term gains through increased connectivity and longer term gains by building understanding of the impacts of widespread IP deployment. Providing limited IP connectivity early in the transition process builds momentum toward and increases preparedness for future IP systems. Effective QoS techniques provide improved usability of present and future links.
Approved for Public Release: 05-1400 Presentation [PDF]
Network Theoretic Approaches for Wireless Systems Randall Landry, Principal Investigator Problems:
Most networks exhibit complex behavior that is not well understood from a fundamental perspective. Wireless communications networks are no different in this respect. The complex dynamic behavior associated with wireless networks makes design and management of such systems difficult, particularly in the absence of a fundamental theoretical understanding of how these networks behave.
Objectives:
This project will produce new theoretical approaches for studying and analyzing wireless networks. Our approach will emphasize the importance of understanding performance bounds and their relationship to network predictability or, inversely, complexity. We will provide a framework from which to evaluate system design trades by defining and quantifying quality of service (QoS) functions and evaluating achievable QoS for various network operating conditions.
Activities:
The research plan involves moving from exploration and investigation of suitable models and analytical approaches to development of a network-theoretic methodology capable of answering the key questions and identifying design tradeoffs associated with complex wireless networks. We intend to collaborate with researchers engaged in network science and present our work at relevant conferences and in journals.
Impact:
Any future radio system with networking capabilities will rely heavily during design and development stages on the state of network theory at that time. Today, an absence of fundamental network-theoretic results and processes forces designers to rely on strict protocol layering and commercial-based protocols. This work will influence DoD programs in wireless networking and aid research in academia and industry.
Approved for Public Release: 06-1198 Presentation [PDF]
Plain Text Gateway Glen Nakamoto, Principal Investigator
Source Separation and Equalization for Interference-Limited Communications Robert Taylor, Principal Investigator Problems:
The proliferation of broadband wireless communication systems attempting to access an already crowded radio spectrum has made multiple-user interference the dominant limiting performance factor in today's wireless systems. Unfortunately, nearly all receivers are designed only for the noise-limited (Gaussian) single-user channel case and cannot handle arbitrary interference from other users, particularly those with different signal formats.
Objectives:
We will design, implement, and test a receiver that can jointly separate, equalize, and decode arbitrary wideband signals within an asynchronous multiantenna multiple access channel. The receiver must separate common format signals for wireless network optimization and different format signals for eavesdropping applications. The target system will recover bit streams for all acquired signals of any type in the particular catalog.
Activities:
We will derive and simulate the optimal algorithms for channel estimation, source separation, equalization, symbol synchronization, and channel decoding. We will implement the algorithms on field-programmable gate array development boards and interface them to multichannel RF boards. We will experiment with a simple network (two transmit nodes and one receive node) and use the results to validate simulations and potentially unlock new theoretical concepts.
Impact:
Source separation allows for linear scaling of wireless network throughput capacity, since colliding packets can be perfectly recovered. Thus, this work could lead to a revolution in the physical layer for wireless networks. Collection platforms can extend their range from the targets, since the interference limitation will be removed. This can provide a solution for standoff eavesdroppers.
Approved for Public Release: 06-1408 Presentation [PDF]
System Impact of Optical Band Scrambling Bob Kimball, Principal Investigator Problems:
To provide defense in depth of critical networks as mandated by DoD-NII, manufacturers are introducing technologies that perform bulk encryption of optical wavelength division multiplexed signals into the marketplace. An independent, impartial assessment of the impact of these technologies on optical transmission performance is needed before the government commits resources to incorporate these devices into operational networks.
Objectives:
We will provide a recommendation to DISA, other government agencies, and the public on the impact of this technology. The recommendation will evaluate the suitability for use, provide a quantitative assessment of any transmission impairments, an identification of any restrictions and limitations on use of the technology, and a determination of the impact on the operation of core networks.
Activities:
We will study the impact of optical band scrambler-type bulk encryption on optical transmission systems theoretically by building physical models of the devices and using these models in nonlinear transmission simulations. By executing simulations across a range of optical transmission systems we can quantify any impact of the optical band scrambler.
Impact:
The theoretical analysis will constitute a ground-level assessment of the impact of optical band scrambling on optical transmission systems. Failure at this level would indicate that the technology should not be pursued. Successful transmission at the modeling level would indicate the proper analysis protocol for a follow-on experimental assessment of the technology.
Approved for Public Release: 07-0579
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