ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper describes and interference cancellation technique appropriate for ARTM Tier-1 waveforms. The technique requires the estimators for the bit sequences for the adjacent channels as well as the power levels of the adjacent channels. Simulation results show that the interference canceller allows a more dense “channel packing” thereby creating a channel utilization 67% ~ 100% greater than the current IRIG 106 recommendations.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper will present measured data in an adjacent channel interference (ACI) environment for both filtered continuous phase frequency shift keying (CPFSK) and Feher’s patented quadrature phase shift keying (FQPSK-B) [1]. The quantity measured was bit error probability (BEP) versus signal energy per bit to noise power spectral density ratio (E(b)/N(o)). The interferers were either CPFSK or FQPSK-B signals. The results presented in this paper will be for bit rates of 5 Mb/s, one interferer 20 dB larger than desired signal, various channel spacings, and two different telemetry receivers. The ACI test effort will collect data sets at several bit rates and with one and two interferers. The results will be useful to system designers and range operators as they attempt to maximize the number of Mb/s that can be simultaneously transmitted in the telemetry bands.

RF front-ends are nonlinear systems that have nonlinear frequency response and, hence, can impair receiver performance by harmful adjacent channel interference in non-intuitive ways. Next generation wireless networks will see unprecedented diversity across receiver and radio technologies accessing the same band of spectrum in spatio-temporal proximity. Ensuring adjacent channel co-existence is of prime importance for successful deployment and operations of next generation wireless networks. Vulnerabilities of receiver front-end can have a severe detrimental effect on network performance and spectrum co-existence. This dissertation addresses the technological challenges in understanding and accounting for receiver sensitivities in the design of next generation wireless networks. The dissertation has four major contributions. In the first contribution, we seek to understand how receiver nonlinearity impacts performance. We propose a computationally efficient framework to evaluate the adjacent channel interference in a given radio/spectrum environment. We develop novel tractable representation of receiver front-end nonlinearity to specify the adjacent channel signals that contribute to the interference at the desired channel and the total adjacent channel interference power at a given desired channel. In the second contribution, we seek to understand how the impact of receiver nonlinearity performance can be quantified. We quantify receiver performance in the presence of adjacent channel interference using information theoretic metrics. We evaluate the limits on achievable rate accounting for RF front-end nonlinearity and provide a framework to compare disparate receivers by forming generalized metrics. In the third contribution, we seek to understand how the impact of receiver nonlinearity can be managed at the network level. We develop novel and comprehensive wireless network management frameworks that account for the RF nonlinearity, impairments, and diversity of heterogeneous wireless devices. We further develop computationally efficient algorithms to optimize the proposed framework and examine network level performance. We demonstrate through extensive network simulations that the proposed receiver-centric frameworks provide substantially high spectrum efficiency gains over receiver-agnostic spectrum access in dense and diverse next generation wireless networks. In the fourth contribution, we seek to understand how scalable interference networks are with receiver nonlinearity. We propose practical achievable schemes for interference avoidance and assess the scalability of the next generation wireless networks with interference due to receiver nonlinearity. Further, we develop an algorithmic scheme to evaluate the upper bound on scalability of nonlinear interference networks. This provides valuable insights on scalability and schemes for nonlinear adjacent channel interference avoidance in next generation shared spectrum networks. / Ph. D.

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 paper will provide recommended channel spacing requirements when the Tactical Targeting Network Technology (TTNT) System is utilized in conjunction with airborne telemetry systems at airborne test ranges. The recommendation will be in the form of an equation similar in form to the adjacent channel interference (ACI) equation currently in the Telemetry Standard IRIG-106. Test results will be presented to support this recommendation.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / In this paper we describe a new method that is applicable to mitigating both multipath interference and adjacent channel interference (ACI) in aeronautical telemetry applications using ARTM Tier-1 waveforms. The proposed method uses a linear equalizer that is derived using Kalman filtering theory, which has been used for channel equalization for high-speed communication systems. We illustrate the proposed method with numerical examples obtained from simulations that show the bit error rate performance (BER) for different modulation schemes.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper will present equations for calculating the minimum recommended frequency separation of two digital telemetry signals. The signals can be filtered continuous phase frequency shift keying (CPFSK), multi-h continuous phase modulation (CPM) [1], shaped offset quadrature phase shift keying-Telemetry Group (SOQPSK-TG, aka SOQPSK-A*) [2], or Feher’s patented quadrature phase shift keying FQPSK-B (or FQPSK-JR [3]). The equations are based on measured data in an adjacent channel interference (ACI) environment for filtered CPFSK (aka PCM/FM), multi-h CPM (or CPM for short), SOQPSK-TG, FQPSK-JR, and FQPSK-B. This paper is an extension of my 2001 and 2002 International Telemetering Conference papers on this topic [4, 5]. The quantity measured was bit error probability (BEP) versus frequency separation at a given signal energy per bit to noise power spectral density ratio (Eb/No). The interferers were CPFSK, CPM, SOQPSK-TG or FQPSK-B (-JR) signals. The results presented in this paper will be for a desired signal bit rate of 1 to 20 Mb/s, one interferer 20 dB larger than the desired signal (a few tests included two interferers), and various center frequency spacings, interfering signals, receivers, and demodulators. The overall ACI test effort has collected data sets at several bit rates and with one and two interferers. The results will be useful to system designers and range operators as they attempt to maximize the number of Mb/s that can be simultaneously transmitted with minimal interference in the telemetry bands.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Organizations such as the National Telecommunications and Information Administration (NTIA), Federal Communications Commission (FCC), International Telecommunications Union (ITU) and various commercial entities use a wide range of spectral efficiency criteria in different broadcast and wireless system applications. These criteria and related specifications have significant differences. This paper briefly reviews some common adjacent channel interference (ACI) definitions as well as issues surrounding the definition of spectral efficiency. The impact of these parameters on system bit error rate (BER) performance and closely "packed" adjacent signals is described. ACI criteria and spectral efficiency definitions considered appropriate for existing telemetry applications and deployment of new generations of spectrally efficient systems are illustrated. Specific ACI and spectral efficiency performance requirements adopted by the Department of Defense (DoD) and Advanced Range Telemetry (ARTM) project are highlighted.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper will present measured data in an adjacent channel interference (ACI) environment for filtered continuous phase frequency shift keying (CPFSK or FM), multi-h continuous phase modulation (multi-h CPM or CPM for short) [1] and Feher’s patented quadrature phase shift keying (FQPSK-B) [2]. This paper is an extension of my 2001 International Telemetering Conference paper on this topic [3]. The quantity measured was bit error probability (BEP) versus signal energy per bit to noise power spectral density ratio (E(b)/N(o)). The interferers were CPFSK, CPM, or FQPSK-B signals. The results presented in this paper will be for a desired signal bit rate of 5 Mb/s, one interferer 20 dB larger than desired signal (a few tests included two interferers), and various center frequency spacings, interfering signals, receivers, and demodulators. The overall ACI test effort will collect data sets at several bit rates and with one and two interferers. The results will be useful to system designers and range operators as they attempt to maximize the number of Mb/s that can be simultaneously transmitted with minimal interference in the telemetry bands.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Multi-h CPM has been selected as the Tier II waveform for the Advanced Range Telemetry (ARTM) program, because it offers 50% better spectral efficiency than Feher-patented FQPSK, which is the Tier I waveform. Shaped Offset QPSK has been shown to be nearly identical in performance to Feher-patented FQPSK. Both the Tier I and Tier II waveforms must operate in the presence of adjacent channel interference in order to meet the range community's telemetry requirements. This paper presents an experimental characterization of SOQPSK and Multi-h CPM in the presence of adjacent channel interference, over a range of channel spacings and differential signal amplitudes. Quantitative results are presented which demonstrate the relative robustness of the ARTM Tier I and Tier II waveforms, with adjacent channel interference representative of a typical range environment.

Vehicular communications are a major subject of research and policy activity in industry, government, and academia. Dedicated Short-Range Communications (DSRC) is currently the main protocol used for vehicular communications, and it operates in the 5.9 GHz band. In addition to DSRC radios, other potential uses of this band include Wi-Fi, LTE-V, and communication among unlicensed devices. This dissertation presents an architecture and a feasibility analysis including field measurements and analysis for vehicle-to-train (V2T) communications, a safety-critical vehicular communication application. The dissertation also presents a survey of research relevant to each of several possible combinations of radio-spectrum and vehicular-safety regulations that would affect use of the 5.9 GHz band, identifies the most challenging of the possible resulting technical challenges, and presents initial measurements to assess feasibility of sharing the band by DSRC radios and other devices that operate on adjacent frequencies using different wireless communication standards. Although wireless technology is available for safety-critical communications, few applications have been developed to improve railroad crossing safety. A V2T communication system for a safety warning application with DSRC radios can address the need to prevent collisions between trains and vehicles. The dissertation presents a V2T early warning application architecture with a safety notification time and distance. We conducted channel measurements at a 5.86–5.91-GHz frequency and 5.9-GHz DSRC performance measurements at railroad crossings in open spaces, shadowed environments, and rural and suburban environments related to the presented V2T architecture. Our measurements and analyses show that the DSRC protocol can be adapted to serve the purpose of a V2T safety warning system. The 5.9 GHz band has been sought after by several stakeholders, including traditional mobile operators, DSRC proponents, unlicensed Wi-Fi proponents and Cellular-Vehicle-to-Everything (C-V2X) proponents. The FCC and National Highway Traffic Safety Administration (NHTSA), the two major organizations that are responsible for regulations related to vehicular communications, have not finalized rules regarding this band. The relative merits of the above mentioned wireless communication standards and coexistence issues between these standards are complex. There has been considerable research devoted to understanding the performance of these standards, but in some instances there are gaps in needed research. We have analyzed regulation scenarios that FCC and NHTSA are likely to consider and have identified the technical challenges associated with these potential regulatory scenarios. The technical challenges are presented and for each a survey of relevant technical literature is presented. In our opinion for the most challenging technical requirements that could be mandated by new regulations are interoperability between DSRC and C-V2X and the ability to detect either adjacent channel or co-channel coexisting interference. We conducted initial measurements to evaluate the feasibility of adjacent channel coexistence between DSRC, Wi-Fi, and C-V2X, which is one of the possible regulatory scenarios. We set DSRC at Channel 172, Wi-Fi at Channel 169 for 20 MHz bandwidth and at Channel 167 for 40 MHz, and C-V2X at Channel 174 with almost 100% spectrum capacity. From the measurements, we observed almost no effects on DSRC performance due to adjacent channel interference. Based on our results, we concluded that adjacent channel coexistence between DSRC, C-V2X, and Wi-Fi is possible. DSRC systems can provide good communication range; however, the range is likely to be reduced in the presence of interference and / or Non-Line-of-Sight (NLoS) conditions. Such environmental factors are the major influence on DSRC performance. By knowing the relationship between DSRC and environmental factors, DSRC radios can be set up in a way that promotes good performance in an environment of interest. We chose propagation channel characteristics to generate DSRC performance modelling by using estimation methods. The conducted DSRC performance measurements and propagation channel characteristics are independent; however, they share the same distance parameters. Results of linear regression to analyze the relationship between DSRC performance and propagation channel characteristics indicate that additional V2T measurements are required to provide data for more precise modeling. / PHD / Researchers and regulators in industry, government, and academic institutions are interested in vehicular communications. Dedicated Short-Range Communications (DSRC) is currently the standard protocol for communication between vehicles, including for safety applications, and operates in the band of radio frequencies near 5.9 GHz. In addition to operators of DSRC radios, other potential users are interested in using the 5.9 GHz band. This dissertation presents an architecture and a feasibility analysis including field measurements for vehicle-to-train (V2T) communications, a safety-critical vehicular communication application. The dissertation also identifies major technical challenges that could become important in the future for users of the 5.9 GHz band. The challenges will be different depending on what decisions government regulators make about the types of radios and communication protocols that are allowed in the 5.9 GHz band and about which types of radios should be used for vehicular safety. Although wireless technology is available for safety-critical communications, few applications have been developed to improve railroad crossing safety. To prevent collisions between trains and vehicles, we present a vehicle-to-train (V2T) communication system that uses DSRC radios to provide safety warnings to motorists. Although the term V2T is used, the emphasis is on communication from the train to vehicles. We present a high-level design, or architecture, of the warning system that includes goals for safety notification time and vi distance. We conducted measurements of radio channels near 5.9 GHz as well as measurements of 5.9 GHz DSRC radio link performance at the same locations (railroad crossings in open spaces, shadowed or obstructed environments, and rural and suburban environments). The measurements were performed to help decide whether the V2T warning system architecture would work. A DSRC system can provide good communication range; however, that range could be reduced if the DSRC system experiences interference from other radios or if the signal is partially blocked due to objects between the DSRC radios. The environmental factors are the most important influence on DSRC performance. By knowing the relationship between DSRC and environmental factors, manufacturers and operators can set up the radios to perform well in environments of interest. Although DSRC performance and radio channel characteristics were measured separately, they were measured in the same locations near railroad crossings. This made it possible to perform a statistical analysis of the relationship between DSRC performance and propagation channel characteristics. This analysis indicated that additional measurements will be required to collect enough data to develop robust statistical models that relate DSRC performance directly to measured channel characteristics. However, the results of the V2T measurements that we conducted near rural and suburban railroad crossings with varying numbers and types of obstacles to the radio signals provide a strong indication that DSRC can be used for to provide V2T safety warnings. The 5.9 GHz band has been sought after by several stakeholders, including traditional mobile operators and others who support use of the band for DSRC, unlicensed Wi-Fi, and CellularVehicle-to-Everything (C-V2X) communication. The FCC and National Highway Traffic Safety Administration (NHTSA), the two major organizations that are responsible for vii regulations related to vehicular communications, have not finalized the rules regarding this band. The relative merits of the above mentioned communication standards and coexistence issues between these standards are complex. There has been considerable research devoted to understanding the performance of these standards, but in some instances there are gaps in needed research. We have analyzed regulation scenarios that FCC and NHTSA are likely to consider and have identified the technical challenges associated with these potential regulatory scenarios. The technical challenges are presented and for each a survey of relevant technical literature is presented. In our opinion for the most challenging technical requirements that could result from new regulations are interoperability between DSRC and C-V2X and the ability to detect either adjacent channel or co-channel coexisting interference. We conducted initial measurements to evaluate the feasibility of adjacent channel coexistence between DSRC, Wi-Fi, and C-V2X, which is one of the possible regulatory scenarios. From the measurements, we observed almost no effect on DSRC performance when other types of radios used frequencies adjacent to the frequencies used by the DSRC radios. Based on our results, we concluded that adjacent channel coexistence between DSRC, C-V2X, and Wi-Fi is possible.