With the increasing volume of wireless traffic that military operations require, the likelihood of transmissions interfering with each other is steadily growing to the point that new techniques need to be employed. Furthermore, to combat remotely operated improvised explosive devices, many ground convoys transmit high-power broadband jamming signals, which block both hostile as well as friendly communications. These wide-band jamming fields pose a serious technical challenge to existing anti-jamming solutions that are currently employed by the Navy and Marine Corps. This thesis examines the feasibility of removing such deterministic jammers from the spectral environment, enabling friendly communications. Anti-jamming solutions in self-jamming environments are rarely considered in the literature, principally due to the non-traditional nature of such jamming techniques. As a result, a combination of approaches are examined which include: Antenna Subset Selection, Spectral Subtraction, and Source Separation. These are combined to reduce environmental interference for reliable transmissions. Specific operational conditions are considered and evaluated, primarily to define the limitations and utility of such a system. A final prototype was constructed using a collection of USRP software defined radios, providing solid conclusions of the overall system performance.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This design adopts the software radio and DBPSK（Differential Binary Phase Shift Keying）modulation-demodulation, which detects the telecommand receiving by the guided-missile system correctly. The DBPSK modulation module in Altera FPGA chip converts the binary telecommand into DBPSK signal, which will be frequency modulated after D/A conversion. In the receiver, the FM signal is demodulated and A/D converted before sending to the FPGA. The DBPSK demodulation module in FPGA finally gets the telecommand which will be tally with the telecommand from transmitter. At last, the whole DBPSK modulation-demodulation module is embedded into the remote control test system. The design is working properly and meeting the requirements of the test system.

Enhancement of network data-plane functionality is an open problem that has recently gained momentum. Addition and programmability of new functions inside the network data-plane to enable high speed, complex network functions with minimum resource utilization, is main focus of this thesis. In this work, we look at different levels of the network data-plane design and using network virtualization and software defined networking we propose data-plane enhancements to achieve these goals. This thesis is divided into two parts, in first part we take a ground up approach where we focus our attention at the fast path packet processing. Using hardware and software based network virtualization we show how hardware and software based network switches can be designed to achieve above mentioned goals. We then present a switch design to quickly add these custom fast path packet processors to the network data-plane using software defined networking. In second part of this thesis we take a top to bottom approach where we present a programming abstraction for network operators and a network function deployment system for this programming abstraction. We use network virtualization and software defined networking to introduce new functions inside the network data-plane while alleviating the network operators of the deployment details and minimizing the network resource utilization.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / Legacy telemetry systems, although widely deployed, are being severely taxed to support the high data rate requirements of advanced aircraft and missile platforms. Increasing data rates, in conjunction with loss of spectrum have created a need to use available spectrum more efficiently. In response to this, new modulation techniques have been developed which offer more data capacity in the same operating bandwidth. Demodulation of these new waveforms is a computationally challenging task, especially at high data rates. This paper describes the design, implementation and performance of a high-speed, multi-mode demodulator for the Advanced Range Telemetry (ARTM) program which meets these challenges.

Time-compression overlap-add (TC-OLA) is presented as a novel method of communications over a (wireless) channel, which is shown to have benefits over other methods in some applications. TC-OLA is initially explored in an experimental context using a custom wideband software-defined radio (SDR) to gain insight into some of the possibilities of this method. Basic analysis is developed showing the processing gain, transmitted spectrum, and behaviour in fading channels. The method is considered as a candidate for low power wide area network (LPWAN) applications, highlighting the equivalent channel property, channel averaging, and ability to handle more simultaneous users in the uplink than other schemes in this application area.The method is then considered as an alternative to single carrier frequency domain equalization (SC-FDE) for ultrawideband (UWB) applications, where the ability to reduce or eliminate the cyclic prefix (CP) overhead while still using frequency domain equalization (FDE) techniques is highlighted. Additional application areas for this technology are briefly considered, including cognitive radio and radar. The process of patenting this technology is outlined in an appendix. The issued patent can be found through the United States Patent and Trademark Office (USPTO) as U.S. Patent 9,479,216. / Graduate

Thesis advisor: Alicia H. Munnell / Retirement plans for state employees have over $2 trillion in assets, a significant portion of the U.S. retirement market. In the last 10 years, seven states have transitioned their employee retirement plans from traditional annuity-providing defined benefit pensions to individual account-style defined contribution plans. While private-sector employers save money in transitioning to a defined contribution plan, states actually lose money when switching. Why state governments choose to sponsor retirement plans that cost both the state and its employees money is the central question of this study. Several financial and demographic variables are considered; the only variable that cannot be ruled out is political ideology. The probit panel regression finds that states with Republican-controlled governments are far more likely to switch to a defined contribution plan than states with mixed or Democrat-controlled governments. This conclusion illuminates the central importance of unions in the political process of public plan decision-making and reveals the importance of potential economics losses that result from sponsoring defined contribution plans. / Thesis (BA) — Boston College, 2006. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Economics. / Discipline: College Honors Program.

Digital communications devices designed with application-specific integrated circuit (ASIC) technology suffer from one very significant limitation�the integrated circuits are not programmable. Therefore, deploying a new algorithm or an updated standard requires new hardware. Field-programmable gate arrays (FPGAs) solve this problem by introducing what is essentially reconfigurable hardware. Thus, digital communications devices designed on FPGAs are capable of accommodating multiple communications protocols without the need to deploy new hardware, and can support new protocols in a matter of seconds. In addition, FPGAs provide a means to update systems that are physical difficult to access. For these reasons, FPGAs provide us with an ideal platform for implementing adaptive communications algorithms. This thesis focuses on using FPGAs to implement an adaptive digital communications system. Using the Universal Software Radio Peripheral (USRP) as a base, this thesis aims to create a highly-adaptive, plug and play software-defined radio (SDR) that fits CubeSat form-factor satellites. Such a radio platform would enable CubeSat engineers to develop new satellites faster and with lower costs. This thesis presents a new system, the COSMIAC CubeSat SDR, that adapts the USRP platform to better suit the space and power limitations of a CubeSat.

Network operators need detailed understanding of their networks in order to ensure functionality and to mitigate security risks. Unfortunately, legacy networks are poorly suited to providing this understanding. While the software-defined networking paradigm has the potential to, existing switch-based implementations are unable to scale sufficiently to provide information in a fine-grained. Furthermore, as switches are inherently blind to the inner workings of hosts, significantly hindering an operator's ability to understand the true context behind network traffic. In this work, we explore a host-based software-defined networking implementation. We evaluation our implementation, showing that it is able to scale beyond the capabilities of a switch-based implementation. Furthermore, we discuss various detailed network policies that network operators can write and enforce which are impossible in a switch-based implementation. We also implement and discuss an anti-reconnaissance system that can be deployed without any additional components.

No description available.

Adaptive modulation has been actively researched as a means to increase spectral efficiency of wireless communications systems. In general, analytic closed form models have been derived for the performance of the communications system as a function of the control parameters. However, in systems where general error correction coding is employed, it may be difficult to derive closed form performance functions of the communications systems. In addition, in closed form optimization, real time adaptation is not possible. Systems designed with deterministic state optimization are developed offline for a certain set of parameters and hardwired into mobile devices. In this thesis we present stochastic learning algorithms for adaptive modulation design. The algorithms presented allow for adaptive modulation system design in-dependent of error correction coding and modulation constellation requirements. In real time, the performance of the system is measured and stochastic approximation techniques are used to learn the optimal transmission parameters of the system. The technique is applied to Software Defined Radio (SDR) platforms, an emerging wireless technology which is currently being researched as a means of designing intelligent communications devices. The fundamental property that sets SDR apart from traditional radios is that the communications parameters are controlled in software, allowing for real-time control of physical layer communications. Our treatment begins by modeling the time evolution of the adaptive modulation process as a general state space Markov chain. We show the existence and uniqueness of the invariant measure and model performance functions as expectations with respect to the invariant measure. We consider constrained and unconstrained throughput optimization. We show that the cost functions considered are convex. Next we present stochastic approximation algorithms that are used to estimate the gradient of the cost function given only noisy estimates. We conclude by presenting simulation results obtained by the presented method. The learning based method is able to achieve the maximum throughput as dictated by exhaustive Monte Carlo simulation of the communications system, which provide an upper bound on performance. In addition, the learning algorithm is able to optimize communications under various error correction schemes. The tracking abilities of the algorithm are also demonstrated. We see that the proposed method is able to track optimal throughput settings as constraints are changed in time.