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Quantification of uncertainties in the results of channel sounding measurements is important for their interpretation and further usage. In this paper, a novel uncertainty analysis methodology to quantify uncertainties of condensed parameters in measurements of dynamic millimeter-wave channels is presented. The bandwidth limitation and multipath threshold are identified as important impairments. Therefore, the methodology provides three uncertainty metrics for condensed parameters, namely a standard uncertainty to quantify the impact of random variations; a bias due to the multipath threshold; and a total bias including the impact of the bandwidth limitation. These uncertainty metrics are highly channel dependent. Therefore, the proposed methodology creates reference channels, which are representative of corresponding measured channels. Hardware and processing impairments are included in the analysis via a Monte Carlo simulation. This results in a general methodology that can quantify uncertainties in both static and dynamic channel measurements of any wideband channel sounder. The methodology is implemented, verified and demonstrated for the TU/e channel sounder, which exemplifies how it can be used. The proposed methodology can improve the analysis, interpretation and reporting of channel measurement results.

Human blockage and its dynamics are potential challenges for millimeter-wave (mm-wave) mobile communication. This article presents the results of wideband measurements at 27 GHz with one human blocker close by a dynamic mobile terminal (MT) as well as one or multiple dynamic human blockers further away from an MT. The measured human blockage loss is largest when the direct path (DP) in a line-of-sight (LOS) is blocked, but this loss is limited by other multipath components (MPCs). For nonline-of-sight (NLOS) channels, it is shown that human blockage loss is typically negligible. The presented measurement results show that human blockage loss in multipath channels is much smaller than that reported in diffraction-and measurement-based models, which neglect or minimize the contribution of all MPCs other than the DP. This suggests that the multipath nature of the indoor wireless channel highly limits the impact of human blockage.

In recent years, as more devices are connected to wireless communication systems, the demand for spectrum has increased. As conventional spectrum resources are limited, the THz band becomes an interesting option of more spectrum for wireless communication. However, the channel in THz band has different characteristics compared to the channels in typical frequency bands, and therefore, it is necessary to perform more research to understand the THz channel propagation. In this paper, we focus on the time domain THz channel model under line of sight (LoS) propagation conditions and investigate the channel propagation characteristics in time domain. Firstly, in the full frequency band (FFB) scenario, the time domain impulse responses, which correspond to the time domain THz channel model, are presented for different distances. In the impulse responses, there are significantly delayed paths due to the molecular absorption which causes significant frequency selectivity. Secondly, we extend the model to the limited frequency band (LFB) scenario by applying the root raised cosine filters. The results indicate that the richness of the delayed paths in the impulse response depends on the selected frequency band. In addition, the results indicate that the time delay and total energy strongly depend on the distance whereas the delay spread varies as a function of frequency.

In this paper, we propose a novel underwater acoustic (UWA) communication scheme that achieves energy and spectrum efficiency simultaneously by combining Doppler-resilient orthogonal signal division multiplexing (D-OSDM) and multiple-input-multiple-output (MIMO) signaling. We present both the transmitter processing and the receiver processing for MIMO D-OSDM. We evaluate the performance of MIMO D-OSDM in simulations with a large intersymbol interference of 25 symbols and a Doppler spread with a maximum Doppler shift of 8 Hz. In addition, the sea trial is performed in Suruga Bay, where the receiver is mounted on a barge and a research vessel with the transmitter makes round trips along a line with a speed of 4 kn. In the experiments, we obtain an intersymbol interference of 3.6-29.7 symbols and a Doppler spread of several Hertz (leading to a spread of over two to three subcarrier spacings). The simulation results suggest that MIMO D-OSDM has an advantage over normal D-OSDM, Doppler-resilient MIMO orthogonal frequency division multiplexing (MIMO D-OFDM), and classical OFDM with MIMO signaling (MIMO OFDM) - MIMO D-OSDM achieves better bit error rate performance than the benchmarks. The sea trial results also support the advantage of MIMO D-OSDM - it achieves a coded block error rate of 3.2% while normal D-OSDM and MIMO D-OFDM achieve a coded block error rate of 9.7% and 9.3%, respectively. We conclude that MIMO D-OSDM can become a viable technique that achieves reliable and effective UWA communication., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Circuits and Systems

In this paper, we propose a novel underwater acoustic communication scheme that achieves energy and spectrum efficiency simultaneously by combining Doppler-resilient orthogonal signal division multiplexing (D-OSDM) and multiple-input multiple-output (MIMO) signaling. We present both the transmitter and receiver processing for MIMO D-OSDM. We evaluate the performance of MIMO D-OSDM in simulations with a large inter-symbol interference (60 symbols) and Doppler spread (maximum Doppler shift of 15 Hz). The simulation results show that MIMO D-OSDM achieves almost the same energy efficiency as normal D-OSDM while doubling the spectrum efficiency. We conclude that MIMO D-OSDM can become a viable technique that achieves reliable and effective UWA communication., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Circuits and Systems

Underwater acoustic (UWA) channels are one of the historical mobile ultrawideband channels characterized by large delay and Doppler spreads, but reliable UWA communication remains challenging. Here we performed an initial demonstration of the Doppler-resilient orthogonal signal division multiplexing (D-OSDM) technique in an actual sea environment. D-OSDM spreads data symbols in both time and frequency with guardbands to exploit the time and frequency diversity of UWA channels. The experiment was performed in a challenging scenario: the transmitter was fixed on a floating pier, and the receiver was mounted on a moving remote-controlled boat. The harbor UWA channel had a delay spread of 50 ms and a Doppler spread of up to 4.5 Hz, in the presence of additive Gaussian noise, and the combination of two Rayleigh fading models (a two-path model without Doppler spread and a multi-path model with Doppler spread) was able to successfully model the actual environment. Our results also confirmed that a UWA communication link using D-OSDM will deliver excellent reliability even for a harbor UWA channel with a mobile receiver; D-OSDM achieves better communication quality compared to other communication schemes in both simulations and experiments., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Circuits and Systems

IEEE This paper presents design, LTCC fabrication, and full experimental verification of novel dielectric flat lens antennas for future high data rate 5G wireless communication systems in the 60 GHz band. We introduce and practically completely evaluate and compare the performance of three different inhomogeneous gradient-index dielectric lenses with the effective parameters circularly and cylindrically distributed. These lenses, despite their planar profile antenna configuration, allow full 2-D beam-scanning of high gain radiation beams. A time-domain spectroscopy system is used to practically evaluate the permittivity profile achieved with the LTCC manufacturing process, obtaining very good results to confirm the viability of fabricating inhomogeneous flat lenses in a mass production technology. Then, the lenses performance is evaluated in terms of radiation pattern parameters, maximum gain, beam-scanning, bandwidth performance, efficiencies, and impedance matching in the whole frequency band of interest. Finally, the performance of the three lenses is also experimentally evaluated and compared to a single omni-directional antenna and to a 10-element uniform linear array (ULA) of omni-directional antennas in real 60 GHz WPAN indoor line-of-sight (LOS) and obstructed-LOS environments, obtaining interesting and promising remarkable results in terms of measured received power and root mean square (RMS) delay spread. At the end of the paper, an innovative switched-beam antenna array concept based on the presented cylindrically distributed effective parameters lens is also introduced and completely evaluated, confirming the potential applicability of the proposed antenna solution for future 5G wireless millimeter-wave communication system.

[EN] This paper presents the design, low-temperature co-fired ceramics (LTCC) fabrication, and full experimental verification of novel dielectric flat lens antennas for future high data rate 5G wireless communication systems in the 60 GHz band. We introduce and practically completely evaluate and compare the performance of three different inhomogeneous gradient-index dielectric lenses with the effective parameters circularly and cylindrically distributed. These lenses, despite their planar profile antenna configuration, allow full 2-D beam scanning of high-gain radiation beams. A time-domain spectroscopy system is used to practically evaluate the permittivity profile achieved with the LTCC manufacturing process, obtaining very good results to confirm the viability of fabricating inhomogeneous flat lenses in a mass production technology. Then, the lenses performance is evaluated in terms of radiation pattern parameters, maximum gain, beam scanning, bandwidth performance, efficiencies, and impedance matching in the whole frequency band of interest. Finally, the performance of the three lenses is also experimentally evaluated and compared to a single omni-directional antenna and to a ten-element uniform linear array of omni-directional antennas in real 60 GHz wireless personal area network indoor line-of-sight (LOS) and obstructed-LOS environments, obtaining interesting and promising remarkable results in terms of measured received power and root-mean-square delay spread. At the end of this paper, an innovative switched-beam antenna array concept based on the presented cylindrically distributed effective parameters lens is also introduced and completely evaluated, confirming the potential applicability of the proposed antenna solution for future 5G wireless millimeter-wave communication system.

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., IEEE This paper presents design, LTCC fabrication, and full experimental verification of novel dielectric flat lens antennas for future high data rate 5G wireless communication systems in the 60 GHz band. We introduce and practically completely evaluate and compare the performance of three different inhomogeneous gradient-index dielectric lenses with the effective parameters circularly and cylindrically distributed. These lenses, despite their planar profile antenna configuration, allow full 2-D beam-scanning of high gain radiation beams. A time-domain spectroscopy system is used to practically evaluate the permittivity profile achieved with the LTCC manufacturing process, obtaining very good results to confirm the viability of fabricating inhomogeneous flat lenses in a mass production technology. Then, the lenses performance is evaluated in terms of radiation pattern parameters, maximum gain, beam-scanning, bandwidth performance, efficiencies, and impedance matching in the whole frequency band of interest. Finally, the performance of the three lenses is also experimentally evaluated and compared to a single omni-directional antenna and to a 10-element uniform linear array (ULA) of omni-directional antennas in real 60 GHz WPAN indoor line-of-sight (LOS) and obstructed-LOS environments, obtaining interesting and promising remarkable results in terms of measured received power and root mean square (RMS) delay spread. At the end of the paper, an innovative switched-beam antenna array concept based on the presented cylindrically distributed effective parameters lens is also introduced and completely evaluated, confirming the potential applicability of the proposed antenna solution for future 5G wireless millimeter-wave communication system., Peer Reviewed, Postprint (author's final draft)

This thesis describes in quite depth the channel behaviour in wireless communications, pointing some of the complexities that communication systems must face. The document is then focused in Delay Spread Compression (DSC) as one of the solutions to significant problems in Wideband communications. With this objective, Time Reversal (TR) in its simplest mode has been studied and implemented in Matlab for a Multiple-Input Single-Output (MISO) system. Then, a possible upgrade has been done regarding the antenna weighting. In the second place, for the same system, a Constrained Least-Squares (CLS) Filter has also been studied and implemented, as a different approach to the same problem. To test the filters and be able to compare their performance, measurements of the channel impulse responses (amplitude and phase) of a real scatterer channel have been done for a 4x1 MISO system. The document then shows the simulations of both techniques used on the processed data and compares their performance in terms of DSC and InterSymbol Interference (ISI), showing good robustness in time in terms of DSC for the TR filters, and a CLS filter dominance in terms of ISI mitigation., Este trabajo describe en profundidad el comportamiento del canal en comunicaciones sin cable, apuntando a algunas de las complejidades que los sistemas de comunicaciones deben afrontar. El documento se fija consecutivamente en la compresión del "Delay Spread" (CDS) como una de las soluciones a problemas relevantes en comunicaciones de banda ancha. Con este objetivo, se ha estudiado e implementado el "Time reversal" (TR) en su modo más simple para un sistema "Multiple-Input Single-Output" (MISO). Posteriormente, se le ha aplicado una posible mejora relacionada con el repartimiento de los pesos en las diferentes antenas transmisoras. En segundo lugar, para el mismo sistema, un filtro "Constrained Least Squares" (CLS) se ha también estudiado e implementado, como enfoque distinto para solucionar el mismo problema. Para probar los filtros y hacer posible la comparación de su rendimiento, se han hecho medidas de la respuesta impulsional del canal (amplitud i fase) de un canal dispersor real, sobre un sistema MISO 4x1. El documento acaba mostrando las simulaciones de las dos técnicas utilizadas sobre los datos procesados y compara sus rendimientos en términos de CDS e "InterSymbol Interference" (ISI), mostrando buena robustez por lo que respecta a CDS por parte de los filtros TR y un dominio claro por parte del filtro CLS por lo que respecta a mitigación de ISI., Aquest treball descriu en profunditat el comportament del canal en comunicacions sense cable, apuntant algunes de les complexitats que els sistemes de comunicació han de enfrontar. El document s'enfoca després en la Compressió del "Delay Spread" (CDS) com una de les solucions a problemes rellevants en comunicacions de banda ample. Amb aquest objectiu, s'ha estudiat i implementat el "Time Reversal" (TR) en el seu mode més simple per a un sistema "Multiple-Input Single-Output" (MISO). Posteriorment, se li ha aplicat una possible millora relacionada amb el repartiment de pes en les antenes. En segon lloc, per a el mateix sistema, un filtre de "Constrained Least Squares" (CLS) ha estat també estudiat i implementat, com a un enfocament diferent per solucionar el mateix problema. Per provar els filtres i fer possible la comparació del seu rendiment, s'han fet mesures de la resposta impulsional del canal (amplitud i fase) de un canal dispersor real, sobre un sistema MISO 4x1. El document acaba per mostrar les simulacions de les dues tècniques utilitzades sobre les dades processades i compara els seus rendiments en termes de CDS i "InterSymbol Interference" (ISI), mostrant bona robustesa en termes de CDS per part dels filtres TR i un domini clar per part del filtre CLS pel que fa a mitigació de ISI.

[EN] In this paper we show the results of a simulation of channel parameters using a Game Engine Ray based tool, developed by our group, which has been evolving during last few years. We show simulation results and compare it with a set of measurements for an indoor scenario, in the band of 5.4 GHz. We found a good match between the rays based tool and measurements for Delay Spread. Also, we show the use of an Open Source 3D modelling tool for the scenario building, showing the flexibility of the XML description language for this kind of scenarios.

The radio wave propagation prediction is one of the key elements for designing an efficient radio network system. WRAP International has developed a software for spectrum management and radio network planning.This software includes some wave propagation models which are used to predict path loss. Current propagation models in WRAP perform the calculation in a vertical 2D plane, the plane between the transmitter and the receiver. The goal of this thesis is to investigate and implement a 3D wave propagation model, in a way that reflections and diffractions from the sides are taken into account.The implemented 3D wave propagation model should be both fast and accurate. A full 3D model which uses high resolution geographical data may be accurate, but it is inefficient in terms of memory usage and computational time. Based on the fact that in urban areas the strongest path between the receiver and the transmitter exists with no joint between vertical and horizontal diffractions [10], the radio wave propagation can be divided into two parts, the vertical and horizontal part. Calculations along the horizontal and vertical parts are performed independently, and after that, the results are combined. This approach leads to less computational complexity, faster calculation time, less memory usage, and still maintaining a good accuracy.The proposed model is implemented in C++ and speeded up using parallel programming techniques. Using the provided Stockholm high resolution geographical data, simulations are performed and results are compared with real measurements and other wave propagation models. In addition to the path loss calculation, the proposed model can also be used to estimate the channel power delay profile and the delay spread.

In this contribution, a channel measurement campaign recently carried out in the Jiading campus of Tongji University, Shanghai, China, is introduced. The downlink signals of an active Universal Mobile Telecommunications System (UMTS) were collected at more than 4000 locations and processed to extract channel impulse responses (CIRs). The signal to noise power ratios (SNRs), delay spread, Doppler frequency spread, and the status of line-of-sight (LoS) existence are calculated and used to generate channel maps, i.e. geographic maps overlaid with spots at measurement locations being color-coded by the values of channel parameters. The variations of channel parameters with respect to the co-elevation in NodeBs are investigated. Relationships between the delay, Doppler frequency spreads and the LoS occurrence rate at specific co-elevations are analyzed. Based on these results, a new method is proposed which is applicable for generating realistic CIRs in time and frequency domains that satisfy the elevation-dependent statistics extracted from the measurements., Peer Reviewed, Postprint (published version)

This paper presents delay spread, coherence bandwidth, and angle-of-arrival statistics derived from an extensive MIMO channel measurement campaign carried out at a central frequency of 2.6GHz. The measurement scenarios include indoor-indoor, indoor-outdoor and indoor-outdoor-indoor. The results are useful for analytical and performance studies of post-3G wireless communication systems such as femtocell design and deployment., QC 20130220

High-resolution propagation measurements were carried out to verify the angular and delay dispersion predicted by ray-tracing models. To do the comparison between the measured and simulated results, the corresponding waves should first be identified. This paper introduces a method to find the corresponding relationship of waves automatically. The results show that the algorithm can successfully find the matching simulated and measured waves. It also provides the information to find and further investigate the most dominant propagation mechanisms.

In the current radio planning of wireless cellular networks, analysis of system performance is based on Signal to Noise Ratio (SNR). However, for wideband system such as LTE, the performance depends not only on the SNR but also on the amount of frequency and spatial diversity that the system can exploit. These diversities rely on the delay and angular profile of the radio channel which are often quantified in terms of delay spread (DS) and angular spread (AS). From an operator’s point of view, in order to get reliable prediction of network capacity and coverage, delay spread and angular spread should therefore be taken into account in the radio planning. In this thesis, the effect of delay spread and angular spread on LTE system performance is investigated by performing LTE system level simulations. LTE system level simulation models AMC (Adaptive Modulation and Coding) hence it aligns with how the system works in reality. However, to implement AMC, system level simulation needs an accurate prediction of link level performance in terms of BLER. For this reason, AWGN link level simulation is required. The simulation results show that different delay spread values do not significantly affect the performance of LTE. This indicates that delay spread is not an important parameter to be taken into account in LTE radio planning. On the other hand, first result shows that per path angular spread strongly affects the performance of LTE. This suggests that it should be included in the radio planning of LTE., Telecommunications, Electrical Engineering, Mathematics and Computer Science

Beamforming is an important feature of 60 GHz communications. We present an analysis of the influence of beamforming in indoor ultrawideband radio channels measured in the mm-wave 60 GHz band. The performance of narrowband and wideband direction-based beamformers is investigated in terms of improving channel metrics such as the delay spread, excess delay, and the signal-to-noise ratio (SNR). The performance of the direction-based beamformers is compared with dominant eigenmode transmission and statistical beamforming. Our analysis reveals that in line-of-sight (LOS) scenarios, the two direction-based beamformers have a similar performance that approaches the upper bound set by dominant eigenmode transmission. In non-LOS (NLOS) scenarios, the direction-based beamformers show a performance degradation in relation to the upper bound, with the narrowband beamformer worse off than the wideband variant. The array gain in our measured NLOS scenarios is observed to exceed the theoretical upper limit valid for a rich scattering environment. We show that this result follows from the spatial structure of the measured NLOS channels that has only a few strong reflected components. We investigate the influence of array size on beamforming performance; 5×5 planar arrays are observed to improve the channel's delay metrics as well as the larger 7×7 planar arrays.

Ultrawideband (UWB) is one of the most promising communication technologies in recent times with the promise of high data rates and spectral reuse. This work analyses the outdoor and outdoor-to-indoor propagating characteristics of the UWB pulse, which can be of the order of a few gigahertz in bandwidth. The aim of the thesis is to provide the parameters needed in order to develop a channel model for such cases. The channel model would then play an important role in determining physical layer (PHY) solutions to optimally exploit these characteristics. The measurements carried out on the Virginia Tech campus are used to compute parameters such as path loss, penetration loss and delay statistics. These are carried out in multiple frequency bands and the results are compared across frequency bands to determine effect of different frequency levels on the parameters. Finally the results are analyzed with respect to similar parameters obtained in other measurement campaigns in an attempt to evaluate the performance of Ultrawideband vis-à-vis narrowband systems.

This paper investigates the use of space-time (ST) coding for high-speed data transmission, as well as studies the effect of time delay spread on such scheme over unequalized fading channels. Using a random variable decomposition technique, we present an analytical model and obtain an approximate bound of the pairwise-error probability for ST coded systems over multipath and time-dispersive fading channels. It is shown that the presence of multipath does not reduce the diversity gain provided by the original design criteria, which is adopted to construct specific ST codes in quasi-static flat fading, but the coding gain diminishes due to the effect of multipath fading.

In this paper, we investigate the effect of time delay spread on trellis coded modulation (TCM) in a wireless radio environment where equalization is not employed to mitigate the effects of frequency selective fading when the time delay spread is small. Using a random variable decomposition technique and a Gaussian approximation of the intersymbol interference terms, we obtain explicit bounds for the pair,vise error probability of TCM over multipath Rayleigh fading channels characterized by various power delay profiles. A method to calculate an upper bound of the bit error rate (BER) based on Jamali and LeNgoc bound is also presented. These bounds are used to evaluate TCM performance as well as investigate the delay spread tolerance limit of TCM, including I-Q TCM, over frequency selective fading channels.

For future mobile multimedia communication, a Mobile Broadband System is in development, which operates at a frequency of 60 GHz. In order to get a better understanding of 60 GHz propagation effects in different environments with different conditions, several measurements were performed, using a spectrum analyzer and synthesized signal generator for the frequency-domain characterization of the radio channel. In the experiments, a carrier wave (CW) was swept with constant amplitude across the 100 MHz band, centered on 59.9 GHz. The channel frequency response was measured at the receiver side. The results can be used for the design of an OFDM (Orthogonal Frequency Division Multiplex) system. The measurement environments were a corridor and a big college room in a high-rise office building (indoor) and a parking and a grassfield at the side of that building (outdoor). The spectrum samples were taken in each of the environments. From such samples, parameters that describe the wireless channel can be calculated like the Rice parameter k, the path loss coefficients, coherence bandwidth and the delay spread. It was necessary to develop an appropriate measurement analysis, stemming from the fact that the spectrum analyzer gives no information on the phase, only amplitude. Measurement analysis method and results are explained. When more and more dense measurements are performed a more detailed and accurate description of the wireless channel for the different environments is possible., Electrical Engineering, Mathematics and Computer Science, Telecommunicatie- en Verkeersbegeleidingssystemen

In outdoor wireless LAN’s the large delay spread is a severe problem. There are different techniques to combat the large delay spread, namely: • multicarrier modulations • equalization • diversity • multilevel modulations In this report a simulator is described to analyze the performance of different techniques., Electrical Engineering, Mathematics and Computer Science, Telecommunicatie- en Verkeersbegeleidingssystemen