In Fall 2022 I will be looking for one PhD student; there is a requirement for US citizen/permanent resident for this projects. For more information, please read the brief project descriptions below and also the guidelines for contacting me.
Ph.D. in progress
M.S. in progress
Participants:
The basic objective of the proposal is to increase the spectral efficiency of methods that solve the “two-antenna problem” in aeronautical telemetry. The motivation for this effort is the success of space-time coding techniques to solve the two-antenna problem when using SOQPSK-TG.
The recent loss of spectral allocations to aeronautical mobile telemetry (AMT) motivates the search for more bandwidth efficient methods for using the remaining spectrum. Because the two-antenna problem exists when two (or more) transmit antennas are used no matter what modulation is used, there is interest in migrating the existing space-time coding technique to the more spectrally efficient ARTM CPM.
In the context of the AWS auctions, this project addresses the goal of more spectrally efficient method of mitigating the two-antenna problem in the remaining AMT spectrum. The problem will be approached by a combination of mathematical analysis, simulations, and prototype hardware. The prototype hardware will be used in field trials to validate the assumptions drawn from the analysis and simulations.
This project was featured in a KU press release that can be found here.
This project is managed by the Test Resource Management Center (TRMC) and is funded by the National Spectrum Consortium (NSC) through the Spectrum Access R&D Program via Picatinny Arsenal under Contract No. W15QKN-15-9-1004, from 11/01/2017–10/30/2022. The Executing Agent and Program Manager work out of the AFTC.
Participants:
The basic objective of this research is to assess the viability of coded amplitude shift keying (APSK) in the aeronautical telemetry environment. The motivation for the effort is the potential for improved spectral efficiency (over SOQPSK-TG and ARTM CPM) offered by APSK.
The challenge associated with using APSK, or any other spectrally efficient linear modulation, is peak-to-average power ratio (PAPR). Test articles impose weight, volume, and power constraints on transmitters. In the transmitter, the most significant consumer of power is the RF power amplifier. The most power efficient mode of operation for an RF power amplifier is in full saturation (this maximizes the ratio of RF output power to DC input power). RF power amplifiers operating in full saturation require signals with unity (0 dB) PAPR. For this reason, the modulations used in aeronautical telemetry since the 1970s (PCM/FM, SOQPSK-TG, and ARTM CPM) all have unity PAPR.
The cost of this constraint is spectral efficiency. By allowing a greater-than-unity PAPR more spectrally efficient modulations may be used. But greater-than-unity PAPR means the RF power amplifier must operate at less than full power, which is bad for power efficiency. Consequently, the linear modulations with spectrally efficient pulse shapes and only modest PAPR are of interest. The APSK family of modulations is the best example. This is why APSK has been adopted as the modulation in the DVB-S2 satellite standard.
In the context of the AWS auctions, this research addresses the goal of more efficient use of the remaining AMT spectrum. The problem will be approached by a combination of mathematical analysis, simulations, and prototype hardware. The prototype hardware will be used in field trials to validate the assumptions drawn from the analysis and simulations.
This project was featured in a January 2017 article published in Popular Mechanics. It was also featured in a great KU press release found here.
This project is managed by the Test Resource Management Center (TRMC) and is funded by the National Spectrum Consortium (NSC) through the Spectrum Access R&D Program via Picatinny Arsenal under Contract No. W15QKN-15-9-1004, from 10/03/2016–09/02/2022. The Executing Agent and Program Manager work out of the AFTC.
Participants:
This project aims to improve the understanding of delay-sensitive communications over modern wireless systems and networks where the physical layer transmission is based on transport blocks. Information theory, communication theory, and queuing theory will be integrated to provide a framework to analyze wireless system performance by jointly considering decoding error probability and delay-violation probability. To be specific, a transport block-based channel dispersion will be developed to understand the interplay among channel coding over finite transport blocks, channel knowledge feedback, modulation, and probability of decoding error for modern wireless systems. Performance of hybrid automatic repeat request (HARQ) systems will also be analyzed under this framework.
The outcome of this project is expected to provide design guidance for modern and future wireless systems and networks that supports delay-sensitive traffic. Wireless devices are an integral part of society and are currently used by over 95% of the global population. Research that leads to improving their performance under delay-sensitive traffic offers the potential to improve how these devices serve the needs of their users. In addition to global technological impact, this project has an educational plan that will immerse students from various backgrounds in the exciting field of mobile wireless communications.
This work was funded by the National Science Foundation, award number 1422241, from 08/01/2014–07/31/2016 (24 months).
Participants:
Multipath interference continues to be the dominant cause of telemetry link outages low- elevation angle reception scenarios. The most reliable solution to this problem is spatial diversity (achieved using multiple ground station tracking antennas) with best source selection. In addition to being very expensive, spatial diversity with best source selection is not always possible for geographic or logistical reasons. Consequently, a less expensive and universally applicable solution in the form of equalization is of interest. Previous work in the area was devoted exclusively the CMA equalizer operating in a blind adaptive mode. Government test results proved inconclusive.
The objective of the proposed research is to identify equalization algorithms suitable for use with SOQPSK-TG that are capable of exploiting the presence of a periodically inserted pilot block. The equalization algorithms to be explored are based on the CMA+AMA algorithms, the MMSE criterion, decision feedback algorithms, and the MLSE criteria. Evaluation includes analysis, computer simulation, and a hardware demonstration in a real telemetry environment.
This work was funded by the T&E/S&T Program through the U.S. Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI), contract number W900KK-13-C-0026 for Preamble Assisted Equalization for Aeronautical Telemetry (PAQ), from 03/06/2013–12/23/2015 (34 months).
Participants:
The focus of this effort is to research, design, and develop radio frequency (RF) transmitters that operate in the 4400−4940, 5091−5150, and 5925−6700 MHz C-Band frequency ranges. These transmitters are required to be very small and very power efficient, while operating at high output power. This makes it difficult to dissipate waste heat, etc.
STTR projects require that a small business and a university partner up to complete the work. KU’s main research objectives are:
This work was funded in part by the Missile Defense Agency through the SBIR/STTR Topic MDA11-T004, contract number HQ0147-14-C-7703, from 02/05/2014–12/07/2016 (24 months); and in part by the Air Force Office of Scientific Research through the SBIR/STTR Topic AF12-BT07, contract number FA9550-14-C-0054, from 09/01/2014–08/31/2016 (24 months).
Participants:
In order for a communication link to be functional, synchronization between the transmitter and receiver is absolutely required. By synchronization we mean carrier frequency synchronization, carrier phase synchronization, and symbol timing synchronization. This project has two distinct facets. The first is a general scientific inquiry in the fundamentals of packet-based burst-mode communication using continuous phase modulation (CPM). The specific questions addressed in this facet are: (1) What are the theoretical limits on the estimation accuracy of the synchronization parameters in the burst-mode setting? (2) Which preamble sequence and preamble length provide the optimal estimation accuracy? Once these questions are answered, two additional tasks follow: (3) the design of practical synchronization algorithms that approach the theoretical performance limits found above, and (4) the implementation of these algorithms in a prototype receiver. The CPM portion of the work was supported by internal funds at ITTC.
The second facet is a detailed application of our basic results in the long-term migration within the aeronautical telemetry community (NASA, Air Force, Army, Navy) toward a modern, packet-based, airborne test and telemetry network. This effort is centered around SOQPSK-TG, a modulation scheme that was developed for use in aeronautical telemetry. This portion of the work was funded by the T&E/S&T Program through the U.S. Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI), contract number W900KK-11-C-0032 for Burst Mode Synchronization for SOQPSK (SYNC), from 09/09/2011–09/30/2014 (36.5 months).
Participants:
A key component of the Smart Grid is the fact that two-way communication will overlay the existing power infrastructure. Some of this connectivity may be achieved with existing wireless services (such as cellular or Wi-Fi networks). However, Smart Grid communication is mainly machine-to-machine (M2M) communication, and machines differ from humans in their sheer numbers, lower bandwidth requirements, and remoteness and harshness of location. Therefore, with M2M communication, there is greater emphasis on communication approaches that are friendly toward low-cost, low-power, robust devices that can be deployed in a wide range of locations and conditions. This research is centered on developing such devices for use in distributed communication over power lines. Because power lines are designed to transport power and not information, they present a number of formidable challenges. However, they have the advantage that they can always be assumed to be present (unlike wireless services), and because they are physically part of the grid, they can also be used to sense the health and stability of the grid. The starting point for this project is to collect field measurements of power line communication channels. These measurements will be used to obtain important theoretical results, such as the channel capacity, as well as practical results, such as prototype communication systems for these channels.
Participants:
Future Lunar and Martian surface communication systems will operate under severe size, weight, and power (SWaP) constraints. These systems are also required to transmit large amounts of data (i.e., they are required to have high throughput). The objective of this project is to develop modern iterative- (turbo-) based demodulators and decoders that can satisfy these SWaP and throughput constraints in a wireless environment, at a practical (low-cost) level of complexity and in miniature form. Four specific communication scenarios have been identified: (1) astronaut to the surface assets in his immediate vicinity, (2) astronaut to the main hub/base (assuming line of sight), (3) astronaut to the main hub/base (assuming no line of sight), (4) main hub/base to Earth.
This work was funded by a joint grant from the National Aeronautics and Space Administration and the Kansas Technology Enterprise Corporation, grant number NNX08AV84A, from 07/02/2008–07/01/2012 (four years).
Participants:
Cross-layer optimizations are particularly important in wireless networks. The goal of this project is to study and implement cross-layer optimizations between network/transport protocols and MAC/PHY layers for use in highly-dynamic airborne wireless networks. In particular, we study optimizations involving power control, path selection, reliability, FEC selection, TDM slot assignment, and so on.
This work was funded by the T&E/S&T Program through the U.S. Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI), contract number W900KK-09-C-0019 for AeroNP and AeroTP: Aeronautical Network and Transport Protocols for iNET (ANTP), from 05/15/2009–05/14/2012 (three years).
Participants:
Modern forward error correcting (FEC) codes with high-performance iterative decoders are of tremendous interest in the wireless communications research community. On the practical side, these codes have already been adopted in many wireless communication standards and are under consideration in numerous future standards. The widespread use of these codes places tremendous importance on decoder design and implementation. The goal of this research is to develop hardware FEC decoders that are efficient in their use of hardware resources and implementation effort. While our approach is quite general and is widely applicable, we focus on low density parity check (LDPC) codes and serially concatenated convolutional codes (SCCC) as design examples.
This work was funded by the T&E/S&T Program through the U.S. Army Program Executive Office for Simulation, Training and Instrumentation (PEO STRI), contract number W900KK-09-C-0018 for High-Rate High-Speed Forward Error Correction Architectures for Aeronautical Telemetry (HFEC), from 05/15/2009–08/14/2011.
Participants:
There has been much recent effort devoted to improving the spectral efficiency and the detection efficiency of aeronautical telemetry. It is well-known that forward error correction (FEC) codes offer one possible means of improving detection efficiency. For FEC schemes to be viable options in the telemetry setting, they must provide large coding gains with minimal bandwidth expansion and be implementable in the field. The goal of this project is to study and develop FEC schemes that are particularly effective for use with the existing family of telemetry modulations: pulse code modulation/frequency modulation (PCM/FM), shaped-offset quadrature phase-shift keying (SOQPSK), and ARTM (multi-h) CPM. This approach exploits the memory inherent in these modulations and opens the possibility of achieving very large coding gains, on the order of 9 dB, with high-rate (i.e. minimal bandwidth expansion) FEC codes.
This work was supported by the T&E/S&T Test Resource Management Center (TRMC) through the White Sands Contracting Office, contract number W9124Q-06-P-0337, from 05/17/2006–04/30/2008.
Participants:
Continuous phase modulation (CPM) is a communication format that continues to play a significant role in wireless communications. It is very transmitter-friendly, and is the modulation of choice in applications where low-cost circuitry and transmitter power efficiency are essential (e.g. Bluetooth, GSM, land-mobile radio, etc.). However, CPM can be challenging to work with on the receiving end. Therefore, most of the attention given to CPM is focused on improving aspects of receiver performance. The aim of this research is to advance the state-of-the-art for CPM along two major fronts:
Receiver synchronization is a challenge that continues to trouble CPM in some cases. One method of simplifying the synchronization problem is to use noncoherent detection. A fundamentally different approach to designing noncoherent detection algorithms for CPM is being explored here; the main idea is to quantify receiver complexity and performance in terms of “real-world” measures, and then optimize both at the same time; the result is the algorithm with the least complexity and the best performance. Another area of research is a comprehensive synchronization/detection receiver based on popular Laurent-type models for CPM; separate bits and pieces of such a receiver have been developed to-date, but a unified study and characterization of such a receiver does not yet exist.
This work was supported by Nokia Siemens Networks, the KU General Research Fund, and the Spectrum Efficient Technology, Science & Technology (SET T&E) Program, Department of Defense, from 08/18/2005–12/31/2009.
Participants:
The goal of this project was to develop a hardware implementation of a waveform generator for the three modulations used in aeronautical telemetry: pulse code modulation/frequency modulation (PCM/FM), shaped-offset quadrature phase-shift keying (SOQPSK), and ARTM (multi-h) CPM.
This work was sponsored by RT Logic from 05/17/2007–08/17/2007.
[These documents are available at the ITTC website]
Ph.D. Dissertations
M.S. Theses