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 presents the issues related to the modeling and performance of the Radio Channel used in Telemetry. Because of the physical environment one expects stressed channel conditions due to multipath, shadowing, and high doppler shift caused by high speeds of up to mach 3. Prior work has created useful data and models for analysis of these radio channels. This paper will develop features of a channel simulator that will allow for evaluation of radio protocols for iNET. Substantial work has also been done to develop requirements for the iNET networked radio environment. This paper will map these requirements into technical features required for the radio link and consider how these will relate to the effects of the channels.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Dynamic hardware and software schemes for trajectory based simulation of LEO satellite channel are presented and evaluated. The simulation models are based on the practical LEO satellite channels and change dynamically with the trajectory using the latitude and longitude of the LEO satellite as input. The hardware simulator is consisted of a trajectory based selective fade generator, a trajectory based Doppler shifter, trajectory based time shadowing simulator and a standard channel for addition of noise, ACI and CCI. A FQPSK modulated signal is passed through a trajectory based dynamic fade generator and the spectrum is distorted. Then the resulting signal is exposed to a trajectory based dynamic Doppler Shifter, simulating the passage of the satellite overhead. Then the proper AWGN, ACI or CCI is added to the signal. At the final stage the signal is passed through a trajectory based time Shadowing simulator. The software simulator is a dynamic real time simulator written in MatLab and its structure is similar to the hardware simulator.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / Flight and weapons test ranges typically include multiple Telemetry Sites (TM Sites) that receive telemetry from platforms being flown on the range. Received telemetry is processed and forwarded by them to a Range Control Center (RCC) which is responsible for flight safety, and for delivering captured best source telemetry to those responsible for the platform being flown. When range equipment or operations are impaired in their ability to receive telemetry or process it correctly, expensive and/or one-of-a-kind platforms may have to be destroyed in flight to maintain safety margins, resulting in substantial monetary loss, valuable data loss, schedule disruption and potential safety concerns. Less severe telemetry disruptions can also result in missing or garbled telemetry data, negatively impacting platform test, analysis and design modification cycles. This paper provides a high level overview of a physics-compliant Range Test System (RTS) built upon Radio Frequency (RF) Channel Simulator technology. The system is useful in verifying range operation with most range equipment configured to function as in an actual mission. The system generates RF signals with appropriate RF link effects associated with range and range rate between the flight platform and multiple telemetry tracking stations. It also emulates flight and RF characteristics of the platform, to include signal parameters, antenna modeling, body shielding and accurate flight parameters. The system is useful for hardware, software, firmware and process testing, regression testing, and fault detection test, as well as range customer assurance, and range personnel training against nominal and worst-case conditions.

Underwater acoustic channel models have been studied in the context of communication and sonar applications. Acoustic propagation channel in an underwater environment exhibits multipath, time-variability and Doppler eects. In this thesis, multipath fading channel models, underwater physical properties and sound propagation characteristics are studied. An underwater channel model for sonar applications is proposed. In the proposed model, the physical characteristics of underwater environment are considered in a comprehensive manner. Experiments /simulations were carried out using real-life data. Model parameters are estimated for a specific location, scenario and physical conditions. The channel response is approximated by fitting the model output to the recorded data. The optimization and estimation are conducted in frequency domain using Mean Square Error criterion.

Η βελτιστοποίηση των συστημάτων επικοινωνίας πολλαπλών εισόδων-εξόδων (MIMO) απαιτεί τη δοκιμή τους υπό ρεαλιστικές συνθήκες και σε πολλά διαφορετικά περιβάλλοντα. Η δοκιμή απ’ ευθείας σε πραγματικά ασύρματα περιβάλλοντα δεν είναι αποδοτική μέθοδος, ειδικά κατά τα στάδια της σχεδίασης και του ελέγχου σωστής λειτουργίας, καθώς το κανάλι είναι πολύ ευαίσθητο, μη ελέγξιμο και μη αιτιατό. Επιπροσθέτως, η δοκιμή σε πραγματικά κανάλια δεν είναι πρακτική μέθοδος όταν χρειάζεται να δοκιμάσουμε πολλά διαφορετικά περιβάλλοντα ή να συμπεριληφθεί η κίνηση μέσα στις δοκιμές. Η δημιουργία ρεαλιστικών μοντέλων για κανάλια, χρησιμοποιώντας εργαλεία λογισμικού (Software) είναι μια δεύτερη επιλογή η οποία όμως δεν παράγει αποτελέσματα σε πραγματικό χρόνο και είναι επιπρόσθετα αρκετά χρονοβόρα. Ο λόγος είναι ότι αφού παραχθούν οι συντελεστές του καναλιού στο λογισμικό, η συνέλιξη των συντελεστών αυτών που συνιστούν την κρουστική απόκριση του καναλιού με τα μεταδιδόμενα σήματα είναι μια σχετικά αργή διαδικασία που θέτει φραγμούς στην εξομοίωση πραγματικού χρόνου. Σε κάποια συστήματα δοκιμών βασισμένα σε λογισμικό, τα διαμορφωμένα δεδομένα και τα διαλείπτοντα σήματα συντίθεται ώστε να δημιουργήσουν μιγαδικές (I/Q) κυματομορφές οι οποίες μεταφορτώνονται στη μνήμη μιας γεννήτριας αυθαίρετων κυματομορφών για να παραχθούν από τη γεννήτρια ραδιοκυμάτων. Υπάρχουν αρκετά εργαλεία λογισμικού που μπορούν να επιταχύνουν τη διαδικασία δημιουργίας κυματομορφών με διαλείψεις, όπως για παράδειγμα το εργαλείο MatlabΤΜ της εταιρείας MathWorks, αλλά αυτά περιορίζονται στα παραδοσιακά μοντέλα διαλείψεων. Ακόμα οι γεννήτριες αυθαίρετων κυματομορφών διαθέτουν περιορισμένη μνήμη, με αποτέλεσμα οι παραγόμενες κυματομορφές να είναι αρκετά μικρές και να επαναλαμβάνονται απλώς στο χρόνο. Για όλους αυτούς τους λόγους χρειάζεται να επιστρατεύσουμε ειδικού σκοπού υλικό το οποίο εξομοιώνει ρεαλιστικά κανάλια πολλαπλών εισόδων-εξόδων ώστε να δώσουμε μια λύση στις απαιτητικές αυτές συνθήκες εξομοίωσης. Στην παρούσα διπλωματική σχεδιάσαμε έναν προσομοιωτή καναλιών για κανάλια βασικής ζώνης πολλαπλών εισόδων πολλαπλών εξόδων (baseband MIMO), σε αρχιτεκτονική υλικού και συγκεκριμένα σε συστοιχίες προγραμματιζόμενων πυλών (FPGA). Ο προσομοιωτής αυτός μπορεί να χρησιμοποιηθεί για την πιστοποίηση της λειτουργίας μιας σειράς επεξεργαστών για σύγχρονα και επόμενης γενιάς τηλεπικοινωνιακά συστήματα. / Optimization of multiple input multiple output (MIMO) communication systems, requires testing under realistic conditions and various channel environments. Direct tests on real-world channel environments, is not an efficient method since the channel is very sensitive, not controllable and non–causal. Moreover, testing in a real channel is not a practical method when various different channels need to be tested or mobility to be included in the tests. A second option is to create realistic channel models, using software tools but this does not produce real time results and can also be prohibitively time-consuming. The reason for this, is that after creating the channel coefficients in software that form the channel’s impulse response, the convolution of these coefficients with the transmitted signals is a relatively slow process that hinders real-time simulation. In some software-based test systems the modulated data and fading signals are used to create complex (I/Q) waveforms that are downloaded into the memory of an arbitrary waveform generator in order to be generated by the RF signal generator. Many software tools exist, that can accelerate the process of fading waveform creation, such as MathWorks’ MatlabΤΜ but these tools are limited to traditional fading models. Moreover the arbitrary waveform generators consist of limited memory resulting in short waveforms that simply repeat over time. For these reasons, a requirement for specialized instrumentation arises, one that can emulate realistic multiple input-multiple output channels, in order to provide an efficient solution to these demanding simulation conditions. In the context of the current thesis, we design a baseband multiple input-multiple output (MIMO) emulator into hardware, specifically into Field Programmable Gate Array (FPGA). This particular hardware component is suitable for the functional verification of a variety of baseband processors for current and next generation telecom equipment.

<div>Millimeter-wave (mmWave) bands have become the most promising candidate for enlarging the usable radio spectrum in future wireless networks such as 5G. Since frequent and location-specific blockages are expected for mmWaves, the challenge is understanding the propagation characteristics of mmWave signals and accordingly predicting the channel state information. This research direction has garnered great attention worldwide from industry, academia, and government. However, the majority of current research on mmWave communications has focused on urban areas with high population densities, with very few measurement campaigns in suburban and rural environments. These environments are extremely important for future wireless applications in areas including residential welfare, digital agriculture, and transportation. To fill in this research gap, we developed broadband mmWave channel sounding systems and carried out intensive measurement campaigns at 28 GHz, covering clear line-of-sight as well as non-line-of-sight scenarios over buildings and foliage clutters, to fully characterize the mmWave propagation in suburban and rural environments.</div><div><br></div><div>Moreover, the accuracy provided by traditional statistical models is insufficient for next-generation wireless networks with higher-frequency carriers, because they are unable to predict abrupt channel changes caused by site-specific blockages. To overcome this issue, we explored the possibility of utilizing site-specific geographic features such as buildings and trees in improving mmWave propagation models. A new channel modeling methodology highlighting site-specific parameter evaluation based on easily obtainable data sources (e.g., LiDAR) was proposed for accurate, fast, and automated channel state predictions. Accordingly, an overall root mean square error (RMSE) improvement of 11.79 dB was achieved in a one-building blockage scenario and a regional RMSE improvement of over 20 dB was observed in a coniferous forest. This approach also enables channel simulations for large-scale system performance evaluation, demonstrating a powerful and promising approach for planning and tuning future wide-area wireless networks. The simulation results showed that network densification alone is not enough for closing the digital gap, especially with mmWaves because of the impractical number of required towers. They also backed up supplementary solutions including private data relays, e.g., via drones and portable towers.</div>

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / RF Communication (COMMS) systems where receivers and transmitters are in motion must be proven rigorously over an array of natural RF link perturbations such as Carrier Doppler shift, Signal Doppler shift, delay, path loss and noise. These perturbations play significant roles in COMMS systems involving satellites, aircraft, UAVs, missiles, targets and ground stations. In these applications, COMMS system devices must also be tested against increasingly sophisticated intentional and unintentional interference, which must result in negligible impact on quality of service. Field testing and use of traditional test and measurement equipment will need to be substantially augmented with physics-compliant channel emulation equipment that broadens the scope, depth and coverage of such tests, while decreasing R&D and test costs and driving in quality. This paper describes dynamic link emulation driven by advanced antenna and motion modeling, detailed propagation models and link budget methods for realistic, nominal and worst-case hardware-in-the-loop test and verification.

Several emerging wireless applications require direct transmission between mobile terminals. Examples of these applications are mobile ad-hoc wireless networks, intelligent transportation systems, relay-based cellular networks, and future combat systems. Development of these mobile-to-mobile (M-to-M) systems depends on a good characterization of channel propagation. Another important consideration in modern communication systems is the use of multipath propagation to improve reliability and capacity of wireless systems. This is achieved by employing multiple antennas in multiple-input multiple-output (MIMO) systems and using techniques such as transmit and receive diversity. Considering the demand for high-speed wireless services, MIMO M-to-M systems are the leading candidates for future communication systems. To enable the successful design of MIMO M-to-M systems, our research focuses on modeling of MIMO M-to-M multipath fading channels and on diversity techniques for MIMO systems. Specifically, we propose two-dimensional (2-D) and three-dimensional (3-D) MIMO M-to-M statistical channel models that encompass narrowband and wideband MIMO channel scenarios for macro- and micro-cell environments. Furthermore, we validate the new models against measured data and find very close agreement between them. Using our 3-D models, we also investigate different antenna array configurations and their effect on the capacity of MIMO M-to-M systems. Contrary to common assumptions, we have found that there is no significant loss of capacity if the antenna array is tilted from the horizontal plane. Finally, we propose the design criteria for space-time coded continuous phase modulated systems. Our work would provide other researchers the tools needed to design and test future MIMO M-to-M communication systems.