Power Delay Profile Research Articles

Zenneck Waves in Decision Agriculture: An Empirical Verification and Application in EM-Based Underground Wireless Power Transfer

In this article, the results of experiments for the observation of Zenneck surface waves in sub GHz frequency range using dipole antennas are presented. Experiments are conducted over three different soils for communications distances of up to 1 m. This empirical analysis confirms the existence of Zenneck waves over the soil surface. Through the power delay profile (PDP) analysis, it has been shown that other subsurface components exhibit rapid decay as compared to the Zenneck waves. A potential application of the Zenneck waves for energy transmission in the area of decision agriculture is explored. Accordingly, a novel wireless through-the-soil power transfer application using Zenneck surface waves in electromagnetic (EM) based wireless underground communications is developed.

Measurement‐based wireless channel analysis and modelling for shipping environments

To guarantee shipping safety, it is crucial to build a reliable wireless communication network. This study presents characteristic analysis of shipping wireless channel based on measurements. The authors conduct five channel measurements for two important water mobile communications, covering inland river and sea scenarios. Channel characteristics, e.g. power delay profile, amplitude distribution, delay spread and shadow fading, are extracted and compared for the two scenarios. It is found that the main difference between the them lies in more obstacles and scatterers in inland river propagation environment. The results show that more obstacles and scatterers can result in richer multipath effect and larger shadow fading decorrelation distance. A triple Gaussian mixture distribution (TGMD) is proposed to characterize the wireless channel with LOS, obstructed LOS and non-LOS situations in the practical propagation. To verify the effectiveness of TGMD, the goodness of fit between measurement and analysis results in terms of Rician K-factor, root mean square (RMS) delay spread and RMS Doppler spread is calculated. Furthermore, the cross-correlation among shadow fading, Rician K-factor and RMS delay spread are studied. Larger cross-correlation can be found in inland river and sea than vehicular communication due to the open propagation environment.

Frequency-Selective Wallpaper for Indoor Interference Reduction and MIMO Capacity Improvement

This paper presents the design and features of frequency-selective wallpaper—based on periodic and symmetric metallic hexagons—intended to be attached to standard walls for filtering out 5 GHz signals (e.g., IEEE 802.11a systems) without blocking other selected radio communication services (e.g., cellular mobile communication signals). It analyzes the characteristics of the radio channel—as found within standard indoor environments—with both regular walls and walls with the proposed frequency-selective wallpaper, examined using a ray-launching program for single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems. This allows the harvesting of parameters, including channel capacity, power delay profile, and signal-to-interference ratio, for proper comparison between the two environments under study: with and without the presented wallpaper. The achieved results clearly show that the use of the proposed frequency-selective wallpaper in an indoor scenario reduces interference levels by an additional attenuation of up to 20 dB in comparison to an unpapered wall. Additionally, with MIMO systems, radio channel characteristics, such as capacity, are improved due to the increase in the magnitude of all singular values of the channel transfer matrix compared to the unpapered wall case, thereby leading to the existence of more relevant subchannels.

Channel Measurement and Modeling of the Small-Scale Fading Characteristics for Urban Inland River Environment

In this study, radio channel measurements were conducted in an urban inland river environment at 5.9GHz. The measurements consisted of both the line of sight (LOS) and non-line of sight (NLOS) cases. We estimate and model channel characteristics based on the measured data. For small-scale fading properties, best fit small-scale fading distribution is determined. Statistical models of the Ricean K-factors and Weibull shape parameters are provided. In addition, a distance-dependent Ricean K-factor model for the urban inland river environment is proposed. For the power delay profile (PDP), we perform cluster identification and obtain the cumulative distribution function (CDF) of the inter-cluster interval. A statistical model of the intracluster decay time constant is also presented, and an exponential decay model is applied for modeling the inter-cluster decay of the PDP. For delay spread and Doppler spread, the root mean square (RMS) delay spreads in the LOS case are compared with those in the NLOS case. Moreover, we estimate and analyze RMS Doppler spreads in both the LOS and NLOS cases. Finally, a bimodal Gaussian mixture distribution (BGMD) is employed to characterize the RMS delay spreads and RMS Doppler spreads. The BGMDs exhibit good matching levels.

Convergence and BER Approximation of HIC Detector for DS-CDMA System in Rayleigh Fading Multipath Environment

In this paper we present mathematic analysis and implementation of hybrid interference canceller (HIC) for direct sequence-code division multiple access (DS-CDMA) system in multipath environment over Rayleigh channel. The HIC detector is examined for convergence. The bit error rate (BER) for the system is obtained using Simplified Improved Gaussian Approximation (SIGA). Using this expression, BER is plotted for the Rayleigh channel having exponentially decaying power delay profile (PDP) as well as flat PDP. The theoretical results are compared with the simulated system results.

Outage Performances of 5G Channel Model Influenced by Barometric Pressure Effects in Yogyakarta

The need of using telecommunications networks is driving develop to increasing a cellular technology. Cellular technology has reached the fifth-generation (5G) which is expected to be launched in 2020. 5G technology is predicted to use high frequencies, where high frequencies present a new challenge namely wave propagation attenuation problems that are affected by natural conditions such as barometric pressure, rain rate, humadity, and vegetation density. Differences from the shape of the earth's contours and natural conditions in each region require research to find the most appropriate channel model to be used in the region.The channel model is obtained based on the representative value of Power Delay Profile (PDP) simulation resul ts using the NYUSIM channel simulator. The frequency used is 28 GHz with a scenario under the influence of minimum and maximum barometric using environment parameters based on the city of Yogyakarta. PDP value is used to calculate the outage probability of channel capacity (C) is smaller than the coding rate (R) so that it indicates a failure of detection at the receiver based on the shannon theory. Outage probability is obtained by the cumulative distribution function of the capacity evaluated against the coding rate. Outage probability result in both scenarios are able to reach a point of 10-4, for coding rate ½ it needs 17.649883 dB, for coding rate ¾ it needs 20.020953 dB, dan coding rate 1 it needs 22 dB. This shows that barometric does not significantly influence the performance of the 5G communication system.

5G Channel Model for 28 GHz frequency in Palembang

Next generation wireless technology require a wide frequency band. Current technology use a frequency of below 3 GHz which cannot provide a wide frequency band due to quite dense frequency utilization. The mm-Wave frequency guarantee to provide a wide band frequency band. The use of mm-Wave frequency will be influenced by climate factors. The characteristics of a place will cause a different channel model. Channel Model is useful for minimizes errors and maximizes information transmission or bitrate in communication model. The Channel Model will be represented as a PDP (Power Delay Profile). Channel model performance uses the Outage performance parameter in Shannon Theorem Implementation. Validation results using the CP-OFDM system with 5G BPSK. The parameters used for validation are FER and BER. In this paper, channel models will be analysed based on the characteristic of Palembang area as a reference channel model in Outer of Indonesia. Hopefully, it can be used as a reference for the development 5G wireless system.

Modeling of 300 GHz Chip-to-Chip Wireless Channels in Metal Enclosures

This paper proposes a two dimensional (2-D) statistical channel model for Terahertz (THz) chip-to-chip wireless communication in desktop size metal enclosures. This model differs from traditional statistical channel models as it models both traveling and resonant waves that exist inside metal enclosures. Based on the cavity environment and the statistical properties of the channel inside the metal cavity, the geometrical model which describes propagation in resonant cavity as a superposition of LoS, single bounced (SB), double bounced (DB), and multi-bounced (MB) rays is proposed. Based on the geometrical model, a parametric reference model is proposed. Furthermore, the path loss model that captures signal strength variation in a resonant cavity is proposed. Frequency correlation functions (FCF) and power delay profiles (PDP) for different possible chip-to-chip communication scenarios are derived and compared with the measured ones. The results show a good agreement between the simulated and measured statistics.

Fine time synchronization and residual ISI influence in SC-FDE systems

We show a novel method for a fine time synchronization in a presence of residual intersymbol interferences (ISIs). The proposed method is compared with a (1) Cramér-Rao lower bound (CRLB) for data-aided timing estimators and with a (2) maximum likelihood (ML) estimator both in (a) ISI-free additive white Gaussian noise (AWGN) channel and (b) in a residual ISI channel. The effect of the residual ISI is introduced via a power-delay profile (PDP) with a delay spread spanning over several samples. We consider a single-carrier system with a frequency domain channel estimation. The proposed method almost reaches the performance of the ML estimator in AWGN, while in the presence of the residual ISI, the proposed method shows superior performance evaluated in terms of error vector magnitude improvement of up to 10%.

Measurement‐based V2V radio channel analysis and modelling for bridge scenarios at 5.9 GHz

In this study, vehicle-to-vehicle (V2V) radio channel measurements at 5.9 GHz were conducted on a suspension bridge and a beam bridge. Given that a different structure of the two bridges will result in different channel properties, the authors study small-scale and large-scale propagation characteristics for the bridge scenarios based on measurement data. By using Akaike's information criteria, the study determines optimal small-scale fading distribution. Owing to that Ricean distribution occupies the dominant position, Ricean K-factors in the two bridge scenarios are modelled separately and compared with each other. Afterwards, power delay profiles, Doppler power spectral densities, root-mean-square (RMS) delay spread and RMS Doppler spread are estimated and analysed in different cases. They employ bimodal Gaussian mixture distribution (BGMD) to model the RMS delay spreads and the RMS Doppler spreads. Fitting results of the BGMDs show good matching levels. For the large-scale propagation characteristics, path loss model for the beam bridge scenario is proposed based on the two-ray theory. On the other hand, path loss for the suspension bridge scenario is modelled by using an empirical function derived from WINNER II. Finally, grey relational grade–mean absolute percentage error, and RMS error criteria prove the effectiveness of the two proposed path loss models.

Doppler filtering approach to reduce the effect of in‐band interference in FMCW propagation data

This Letter proposes a method to reduce the effect of in-band interference in average power delay profiles obtained from frequency modulated continuous wave (FMCW) radio propagation data. The method is based on filtering the detector output in the Doppler domain. Results show that the Doppler filtering can be effective.

HUMIDITY EFFECT TO 5G PERFORMANCES UNDER PALEMBANG CHANNEL MODEL AT 28 GHZ

The telecommunication has a tremendous improvement in terms of data rates and bandwidth requiring sufficient frequency allocation and wideband spectrum availability. The millimeter-wave frequency band is one of the solution to these requirements, however communications in this band is facing new challenges on the climate effect to the channel propagation In this paper, we propose a 5G channel model considering the effect of humidity based on the characteristic of the natural environment of Palembang city. The channel model is represented by power levels and delay called a Power Delay Profile (PDP and is derived based on a series of computer simulations using parameters of nature in Palembang. The 5G channel model is important to further derive the outage performance to be used as the theoretical performance of 5G in Palembang since the the Shannon Channel Capacity Theorem is involved in the derivation. We conduct a series of computer simulations to evaluate the validity of the proposed channel model and its characteristics. We found that humidity affect to the performances, where high humidity makes the performances of outage and BER slightly worse, although the effect may be ignored for some applications. The results of this paper are expected to be the references for the development and implementation of 5G Networks especially at the mm-Wave band in Palembang.

The Comparative Study of S-V Model Between 3.5 and 28 GHz in Indoor and Outdoor Scenarios

The 3.5 GHz and 28 GHz bands are both very important for the fifth-generation (5 G) wireless communication system. To model their propagation characteristics and study their channel properties, we conduct measurements at these two bands in indoor and outdoor scenarios. The measured bandwidths at 3.5 and 28 GHz are 100 and 400 MHz, respectively. To make a fair comparison, the measurement results at 28 GHz are divided into four groups with bandwidths from 100 to 400 MHz. This is also helpful to study the effect of bandwidth on the channel properties, especially numbers of clusters and their growth rate. We choose the Saleh-Valenzuela (S-V) model to analyze the wireless channel. Its cluster-based property is very suitable to describe the power delay profiles (PDPs) in our measurement. To maintain the time continuity of multipath components (MPCs) during the clustering, we propose a new heuristic cluster algorithm. Based on the clustering results, we obtain the channel parameters, i.e., the number of clusters, inter-cluster interval, intra-cluster root mean square (RMS) delay spread, cluster decay factor, and ray decay factor. From the comparative study, we can find that the rays suffer a larger attenuation at 28 GHz than at 3.5 GHz. Increasing bandwidth can increase the ray decay factor. But the effects of frequency on the cluster decay rate are different in indoor and outdoor scenarios. The cluster decay rate is smaller at 28 GHz in the indoor scenario.

Reverberation chambers for testing wireless devices and systems

Testing of wireless devices and systems is becoming increasingly important in the technological development of Long Term Evolution (LTE) and 5G mobile networks. Both mobile and base station manufacturers are interested in assessing system performance and user perceived quality in realistic propagation environments, including indoor and outdoor conditions. Real-life electromagnetic environments exhibit rich multipath propagation and a strong attenuation of the wireless signal over the propagation channel. Emulating those conditions in anechoic chambers requires the careful arrangement of many interference sources in multiple configurations, which leads to complex and time-consuming measurements. The reverberation chamber (RC) is a metallic cavity where the signal created by a single source is reflected and diffused to create multipath fading. This paper gives an overview of how an RC can be tuned to emulate channel parameters, e.g., power delay profile, time delay spread, coherence bandwidth and Rician K-factor, of real-life environments The addition of absorbing material inside the RC allows for varying those parameters, thus recreating line of sight and imperfect propagation conditions experienced by the user equipment (UE). Compliant electromagnetic compatibility downlink and uplink tests are shown for selected MIMO configurations as well as for Internet of Things devices. The tests are carried out using a commercial base station connected to the live national mobile network of a mobile operator. Evaluated network parameters are throughput, signal to noise ratio, modulation schemes and other settings of both the base station and of the UE to assess the quality of the digital communication.

Using the Power Delay Profile to Accelerate the Training of Neural Network-Based Classifiers for the Identification of LOS and NLOS UWB Propagation Conditions

ultra-wideband (UWB) technology enables centimeter-level localization systems based on the accurate estimation of the actual distance between transmitter and receiver, by means of the precise estimation of the signal time-of-flight. However, this is only possible when correctly detecting the first path of the incoming signal instead of a bounce or a reflection, which becomes challenging in non line-of-sight (NLOS) situations. There are many different approaches in the literature to alleviate the wrong detection of the first incoming UWB signal path. One of them considers machine learning techniques to design classifiers capable of distinguishing between line-of-sight (LOS) and NLOS propagation from available signal features. However, the performance and complexity of the obtained classifiers depend largely on the size of the input data associated to such features. Thus, features such as the channel impulse response (CIR) produce large amounts of data, yielding very complex classifiers. In this paper, we propose using a downsampled power delay profile (PDP) as an alternative feature consisting of input data much smaller than the CIR, although sufficiently representative, hence resulting in a lower computational cost while exhibiting a similar classification performance. Furthermore, another of the tasks addressed in this work is the study of the impact on the classification results of using a dataset for training where the samples of each class are not balanced from the point of view of energy. Finally, this work also studies how the classifiers based on the CIR or the PDP improve their performance when considering additional signal features such as the estimated range value or its energy level.

A 3D Ray Launching Time-Frequency Channel Modeling Approach for UWB Ranging Applications

Ultrawideband (UWB) has the ability to achieve decimetre level of ranging accuracy, hence, its wider usage nowadays in the field of positioning. In spite of the attractiveness of UWB, its performance is strongly dependent on the propagation channel. In this paper, an analysis of the the UWB channel for ranging applications using an inhouse developed 3D Ray launching (3D RL) algorithm is presented. A parametric study has been performed considering variations of cuboid size resolution of the simulation mesh, in order to analyze convergence impact on estimation accuracy, focusing on Radio frequency (RF) power levels as well as time domain characterization. The RF power results have been used to model the path-loss, small scale fading, and the power delay profile so as to obtain the statistics of the multipath channel as well as time of flight (TOF) estimation values. The results show that the 3D RL is a valuable tool to test UWB systems for ranging applications with a mean accuracy of up to 10 cm in multipath conditions considering complex scatterer distributions within the complete volume of the scenarios under test.

Deep Learning-Based mmWave Beam Selection for 5G NR/6G With Sub-6 GHz Channel Information: Algorithms and Prototype Validation

In fifth-generation (5G) communications, millimeter wave (mmWave) is one of the key technologies to increase the data rate. To overcome this technology's poor propagation characteristics, it is necessary to employ a number of antennas and form narrow beams. It becomes crucial then, especially for initial access, to attain fine beam alignment between a next generation NodeB (gNB) and a user equipment (UE). The current 5G New Radio (NR) standard, however, adopts an exhaustive search-based beam sweeping, which causes time overhead of a half frame for initial beam establishment. In this paper, we propose a deep learning-based beam selection, which is compatible with the 5G NR standard. To select a mmWave beam, we exploit sub-6 GHz channel information. We introduce a deep neural network (DNN) structure and explain how we estimate a power delay profile (PDP) of a sub-6 GHz channel, which is used as an input of the DNN. We then validate its performance with real environment-based 3D ray-tracing simulations and over-the-air experiments with a mmWave prototype. Evaluation results confirm that, with support from the sub-6 GHz connection, the proposed beam selection reduces the beam sweeping overhead by up to 79.3 %.

Learning Parameters of Stochastic Radio Channel Models From Summaries

Estimating parameters of stochastic radio channel models based on new measurement data is an arduous task usually involving multiple steps such as multipath extraction and clustering. We propose two different machine learning methods, one based on approximate Bayesian computation (ABC) and the other on deep learning, for fitting stochastic channel models to data directly. The proposed methods make use of easy-to-compute summary statistics of measured data instead of relying on extracted multipath components. Moreover, the need for post-processing of the extracted multipath components is omitted. Taking the polarimetric propagation graph model as an example stochastic model, we present relevant summaries and evaluate the performance of the proposed methods on simulated and measured data. We find that the methods are able to learn the parameters of the model accurately in simulations. Applying the methods on 60 GHz indoor measurement data yields parameter estimates that generate averaged power delay profile from the model that fits the data.

Non‐geometrical stochastic model for non‐stationary wideband vehicular communication channels

In this study, the authors propose a new non-geometrical stochastic model (NGSM) for non-stationary wideband vehicular communication channels. To include the line-of-sight component, the proposed model first generates a non-uniformly distributed tap phase, which can be obtained from the widely used uniformly distributed tap phase. Moreover, the proposed model can practically experience variable types of Doppler spectra for different delays by modifying the autocorrelation function used in the existing NGSM. In consideration of the non-stationarity in the frequency domain of vehicular communication channels, the authors further consider that the amplitude and phase of different taps are correlated. To evaluate the performance of the proposed model, they derive some significant statistical properties in terms of the power delay profile, tap correlation coefficient matrix and Doppler power spectral density. It is demonstrated that in comparison with the existing NGSMs, the proposed model possesses the ability to better mimic characteristics of real vehicular channels. Finally, the excellent agreement is achieved between the simulation results and the corresponding measured data, confirming the accuracy of the proposed model.

Measurement-Based Feasibility Exploration on Detecting and Localizing Multiple Humans Using MIMO Radio Channel Properties

This paper explores the feasibility of using the multiple-input multiple-output (MIMO) radio channel properties to passively detect and localize multiple humans in indoor environments. We propose to utilize the unique reverberation characteristics of indoor channels for the purpose of detecting, and the power angular delay profile (PADP) for localizing humans. On the one hand, the reverberation time corresponds with the decay rate of multipath in a closed or partially closed cavity, and varies with the change of the number of humans or the moving of humans relative to the antennas at link ends. On the other hand, the PADP is proposed to be calculated by the Multiple Signal Classification (MUSIC) super resolution algorithm with frequency smoothing preprocessing. The proposed approach is evaluated based on real-world MIMO radio channel measurements obtained from a meeting room. Measurements with and without the presence of humans have been conducted, where the maximum number of humans considered is four. Humans facing different directions, either in parallel or orthogonal to the direct line between the transmit and the receive antennas have been taken into account. In term of the detection feasibility, it is found that the change of the number of humans as well as the change of their facing/moving directions inside the partial reverberant region can be reflected on the change of the reverberation time estimated from the power delay profile of channel. In term of the localization feasibility, it is found that single human location can be well associated to the peak of the variation of the PADP during his/her movement, while multiple humans' movements result in obvious power variation in the very vicinity of some of them, and also in the vicinity of some background objects that is far from target humans.