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Channel modeling often provides a basis for the design and deployment of wireless technology. Engineers design systems to operate under certain expected channel conditions. Channel models are typically based on the statistics of a collection of many measurements performed by channel sounders in nominally similar radio-propagation environments. In 2016, researchers at the US Department of Commerce National Institute of Standards and Technology (NIST) and the National Telecommunications and Information Administration Institute for Telecommunication Sciences (ITS) began a collaboration to conduct a series of channel sounder verifications to identify sources of uncertainty due to systematic and random effects in a channel sounder hardware. This report describes conducted-channel measurements designed to focus on errors within the channel sounding hardware as a base-line test of the channel sounder’s performance. Repeat measurements and an analysis of the random components of uncertainty were performed. Sample results are reported and analyzed. The work concludes with guidance and best-practice procedures with the intent of allowing users to perform similar verifications of their channel sounders.

This letter analyzes the impact of interuser distance and angular separation on the channel correlation and achievable sum-rate for a massive multiple-input-multiple-output (MIMO) system in non-line-of-sight (NLOS) conditions. The investigation is based on outdoor measurements on a channel sounding system capturing the dynamic channel of two user arrays. The letter analyzes correlation and sum-rate with varying interuser distance and angular separation of dominant beams toward the users. A large span of correlation and sum-rate values are found across the range of distances and angular separation. The investigation shows a moderate link between interuser distance and correlation, but a strong impact on correlation is found only for low angular separation of the users. The results of this NLOS scenario suggest that a distance-based criteria alone is not sufficient to accurately model shared clusters and their correlation.

Industry 4.0 is the scenario in which the 5G and beyond networks are expected to show all their potential. However, while propagation at sub-6 GHz has been widely investigated in industry environments, mm-waves propagation and channel modelling in those scenarios is still under early research. Therefore, we introduce novel simultaneous multiband ultra-wideband measurements at 6.75 GHz and 30 GHz in LOS and NLOS with RX below and above clutter level. This unique set-up allows a direct comparison between the sub-6 GHz and mm-wave channel. Results have shown larger specular to dense multi-path components power ratio and shorter large-scale parameters at mm-waves.

The paper addresses the problem of mitigation of dispersion distortions in transionospheric satellite communication channels with the use of the data on the propagation medium obtained from global navigation systems. Distortions mitigation is performed by a correction device that operates in the following modes: compensation for dispersion, channel sounding, equalizer training. In addition to this, the influence of stochastic errors that corrupts the total electron content (TEC) measurements on the dispersion correction was considered. The full-scale experiments carried out in Yoshkar-Ola allowed to produce daily variations in the total electron content, frequency dispersion parameters and channel lifetime with the use of data from the GLONASS / GPS satellite systems.

To explore the eventual deployment of communication systems in Terahertz (THz) band (0.1-10 THz) frequencies, extensive channel measurement campaigns are essential. In this regard, we conducted an indoor line-of-sight (LoS) measurement campaign up to 5.5 m on a THz channel sounding system that covers 140-220GHz. We use a frequency-domain channel sounder that is based on a vector network analyzer (VNA) and frequency extenders for these measurements. Using the log-distance path loss model, we estimate the values of path loss exponent and the fading distribution standard deviations. The power delay profile analysis of our measurements shows that there are negligible multipaths in the LoS channels for the current scenario. Our results provide a platform for future exploration of THz band communication in the 140-220 GHz frequency range.

The large gains provided by millimeter-wave (mmWave) frequencies in terms of available bandwidth have made them a popular choice to be included in different standards like the 5G-NR and IEEE 802.11ay. Although mmWave frequencies offer an opportunity for large capacities, they face many challenges related to the propagation channel such as strong blockage or attenuation losses. In this paper, 60 GHz in-street backhaul propagation channel is measured and evaluated along with ray-based simulations in two different scenarios; urban canyoning and residential. The channel sounder allows for bi-directional path-loss measurements with highly-directive beamforming at both sides. And the simulator takes benefit from highly accurate LiDAR point cloud data in order to identify the obstacles and compute losses along the direct and indirect paths. Both the measurements and simulations show strong channel sparsity when antennas are located at 3 meters above the ground, caused by the many in-street obstacles.

The 802.15.4z standard, still under development, advances the secure ranging protocol by encryption of PHY timestamp sequence using AES-128 encryption algorithm. The paper analyses the key parts of PHY which have a great contribution in range estimation precision, particularly: UWB pulse, channel sounding and timestamp estimation using ciphered sequence. The propagation analysis in UWB channel shows that the frequency selective fading gives worse effects than multipath propagation in the timestamp estimation.

In this article, a novel vector network analyzer (VNA)-based ultrawideband (UWB) channel sounder using radio-over-fiber (RoF) techniques is presented. Benefiting from the usage of optical fiber cable, the measurement range and the dynamic range are significantly increased compared with the conventional coaxial-based VNA system. Specifically, using RoF increases the dynamic range to a maximum of 112 dB at 30 GHz for the back-to-back connection with an optical fiber cable of length 300 m. Moreover, a state-of-the-art phase compensation scheme using optical circulators is proposed for the first time. The novel scheme renders the channel sounder immune to stochastic phase changes in the optical fiber cable due to thermal changes and mechanical stress, thus permitting the remoting of virtual antenna arrays. The proposed channel sounder is experimentally validated in back-to-back measurements, an anechoic chamber, and practical indoor scenarios. The indoor channel measurements are conducted using a virtual uniform rectangular array (URA) at the millimeter-wave (mm-wave) band from 26.5 to 30 GHz. The measured results demonstrate the developed channel sounder's capability to perform UWB large-scale antenna array measurements with a long measurement range.

A comprehensive treatment of wireless underground channel modeling is presented in this chapter. The impacts of the soil on bandwidth and path loss are analyzed. A mechanism for the UG channel sounding and multipath characteristics analysis is discussed. Moreover, novel time-domain impulse response model for WUC is reviewed with the explanation of model parameters and statistics. Furthermore, different types of the through-the-soil wireless communications are surveyed. Finally, the chapter concludes with discussion of the UG wireless statistical model and path loss model for through-the-soil wireless communications in decision agriculture. The model presented in this chapter is also validated with empirical data.

Large scale multiple-input multiple-output (MIMO) or Massive MIMO is one of the pivotal technologies for future wireless networks. However, the performance of massive MIMO systems heavily relies on accurate channel estimation. While the acquisition of channel state information (CSI) in such systems requires an increasingly large amount of training overhead as the number of users grows. To tackle this issue, in this paper, we propose a deep learning assisted blind channel estimation technique for orthogonal frequency division multiplexing (OFDM) based massive MIMO systems. We prove that by exploiting the asymptotic orthogonality of the massive MIMO channels, the channel distortion can be averaged out without the prior knowledge of channel impulse responses, and after some mathematical manipulation, different users transmitted data symbols can be extracted. Thus, by deploying a denoising convolutional neural network algorithm (DnCNN), we mitigate a remaining channel and noise effect to accurately detect the transmitted data symbols at the channel sounding stage. Using the detected data symbols as virtual pilots, we estimate the CSI of all the users at each BS antennas. Our simulation results testify the efficacy of our proposed technique and demonstrate that it can provide a mean square error (MSE) performance which coincides with that of the data-aided channel estimation technique., Comment: 6 pages and 4 figures

We report an ultra-wideband channel sounding enabled by an optical dual-comb and photonic asynchronous sampling. A 2-18 GHz rich-multipath wireless channel is measured by a 1 kHz highest refresh rate.

In this work we present low cost time-domain wireless channel sounding using software defined radio (SDR). We performed SDR based time-domain wireless indoor channel sounding using random sequences. We used three random sequences for channel measurements because of their excellent auto-correlation and cross-correlation properties. More specifically PN code sequence, Gold code sequence, and Zadoff-Chu sequences are used. The channel measurements are performed in indoor laboratory environment at two locations at RF frequency of 5.2 GHz and 5.8 GHz respectively. Channel measurements are performed by transmitting sequences with software defined radio in indoor laboratory environment.

This paper presents the results of a mmWave channel sounding campaign in a bulk carrier vessel. Using the Terragraph channel sounder, we measured path loss at 60.48 GHz for different separations between the transmit and receiving nodes in the engine room and steering control room of the vessel. The path loss at reference distance 1.5 m is 74.6 dB, which is higher than the free space path loss, whereas the path loss exponent of 1.7 is lower than in free space. The one-slope path loss model is used to estimate throughput via link budget calculations, which shows that 60 GHz propagation realizes high data rate communication in the engine room of a vessel if the Line-of-Sight path is not obstructed. Due to the highly metallic nature of the propagation environment, reflections make communication possible in an obstructed Line-of-Sight configuration, but there is no clear distance relationship.

We explore the feasibility of Multiple-Input-Multiple-Output (MIMO) communication through vibrations over human skin. Using off-the-shelf motors and piezo transducers as vibration transmitters and receivers, respectively, we build a 2x2 MIMO testbed to collect and analyze vibration signals from real subjects. Our analysis reveals that there exist multiple independent vibration channels between a pair of transmitter and receiver, confirming the feasibility of MIMO. Unfortunately, the slow ramping of mechanical motors and rapidly changing skin channels make it impractical for conventional channel sounding based channel state information (CSI) acquisition, which is critical for achieving MIMO capacity gains. To solve this problem, we propose Skin-MIMO, a deep learning based CSI acquisition technique to accurately predict CSI entirely based on inertial sensor (accelerometer and gyroscope) measurements at the transmitter, thus obviating the need for channel sounding. Based on experimental vibration data, we show that Skin-MIMO can improve MIMO capacity by a factor of 2.3 compared to Single-Input-Single-Output (SISO) or open-loop MIMO, which do not have access to CSI. A surprising finding is that gyroscope, which measures the angular velocity, is found to be superior in predicting skin vibrations than accelerometer, which measures linear acceleration and used widely in previous research for vibration communications over solid objects.

The upcoming fifth-generation (5G) mobile communication system is expected to support high mobility up to 500 km/h, which is envisioned in particular for high-speed trains. Millimeter wave (mmWave) spectrum is considered as a key enabler for offering the “best experience” to highly mobile users. Despite that channel characterization is necessary for the mmWave system design and validation, it is still not feasible to directly do extensive mmWave mobile channel measurements on moving high-speed trains (HST) at a speed up to 500 km/h in the present. Thus, rather than conducting mmWave HST channel sounding directly with high mobility, this study proposes a viable paradigm for realizing the realistic HST channels at the 5G mmWave band. We first propose the whole paradigm. Then, we define the scenario of interest and select the main objects and materials. Afterwards, the electromagnetic and scattering parameters of the materials are measured and estimated between 26.5 GHz and 40 GHz. With this information, the most influential materials are determined through significance analysis. Correspondingly, we reconstruct the three-dimensional mmWave outdoor HST and tunnel scenario models. Through extensive ray-tracing simulations, we determine the main propagation mechanisms in these two scenarios, the channel models based on that are validated by measurements. This verifies the whole paradigm proposed in this paper.

Wireless body area networks (BANs) have many important applications such as wearable communication devices and Internet of Things. Wireless propagation in on-body channels has been measured and modeled in the past. However, a crucial element that is usually ignored is the impact of the body size of the user—a 50-kg person obviously creates a different on-body channel than a 150-kg person. The status-quo “one-size-fits-all” approach to channel characterization in BAN is thus incomplete. In this paper, we provide a detailed description of a propagation measurement campaign that employs a self-developed $4 \times 4$ ultrawideband multiple-input-multiple-output array channel sounding system to perform BAN channel sounding both in an anechoic chamber and indoor laboratory environments. A total of 60 human subjects were investigated in our work. These human subjects had widely varying body mass index (BMI) values, which were grouped into three different categories, i.e., 20 per BMI category. Various propagation properties such as path gain, frequency-decay factor, shadowing gain, rms delay spread, amplitude fading, and spatial correlation are extracted for each on-body channel under consideration. A comparison of statistics among the BMI categories reveals considerable differences, emphasizing the fact that the aforementioned propagation properties are BMI dependent. Parameters such as path gain showed a monotonic decrease across the BMI categories with values ranging from 1–2 to almost 13 dB in some channels. This paper proposes a propagation channel model for the BMI-dependent parameters and validates that it can reproduce the measured channel capacities.

This paper proposes a closed-loop sparse channel estimation (CE) scheme for wideband millimeter-wave hybrid full-dimensional multiple-input multiple-output and time division duplexing based systems, which exploits the channel sparsity in both angle and delay domains. At the downlink CE stage, random transmit precoder is designed at base station (BS) for channel sounding, and receive combiners at user devices (UDs) are designed to visualize hybrid array as a low-dimensional digital array for facilitating the multi-dimensional unitary ESPRIT (MDU-ESPRIT) algorithm to estimate respective angle-of-arrivals (AoAs). At the uplink CE stage, the estimated downlink AoAs, namely, uplink angle-of-departures (AoDs), are exploited to design multi-beam transmit precoder at UDs to enable BS to estimate the uplink AoAs, i.e., the downlink AoDs, and delays of different UDs using the MDU-ESPRIT algorithm based on the designed receive combiners at BS. Furthermore, a maximum likelihood approach is proposed to pair the channel parameters acquired at the two stages, and the path gains are then obtained using least squares estimator. According to spectrum estimation theory, our solution can acquire the super-resolution estimations of the AoAs/AoDs and delays of sparse multipath components with low training overhead. Simulation results verify the better CE performance and lower computational complexity of our solution over existing state-of-the-art approaches., 16 pages, 9 figures; 3 tables. Accepted by IEEE Transactions on Communications

Estimating the entire channel state information (CSI) is essential for building and keeping a robust RF link between a master device and the mobile-station and base-station in a wireless transmission system. The channel sounding system can be used to evaluate the radio environment for wireless communication to take account the effect of terrain and obstacles, wireless signals propagate in multiple paths (the multipath effect). In a multipath system, the wireless channel is frequency dependent, time dependent, and position dependent. The parameters describe the channel in a multipath system [1], including direction of departure (DOD), direction of arrival (DOA), time delay, Doppler shift, and complex polarimetry path weight matrix. Generally Space-Alternating Generalized Expectation Maximization (SAGE) algorithm [2] or the Multiple Signal Classification (MUSIC) estimation algorithm [3] can be used to estimate the angle information but those methods demand a MCPU with highly computing power. To reduce the computing load, this study proposes the use of monopulse [4] tracking algorithm for angle estimation. Numerical simulation results validate the proposed method.

The IEEE 802.11ac amendment enhances WLAN throughput by exploiting the spatial diversity of the antennas in a multi-user multi-input multi-output downlink transmission. Still, network resources remain under-utilized in uplink transmission due to single-user communication. In this paper, we propose an access point-controlled MAC protocol (A-MAC) that enables simultaneous transmissions from multiple STAs in uplink. The protocol uses the EDCA channel access technique to initiate multi-user transmission and the OFDMA method to transmit multiple RTSs simultaneously. It also introduces the explicit channel sounding technique by using dedicated OFDM subcarrier blocks for each user. Performance measurement shows that network throughput of the A-MAC is 150% higher than that of a single uplink transmission, thanks to the availability of concurrent multiple RTS transmissions in the uplink. The proposed protocol shortens the backoff time by up to 50% for all traffic categories due to concurrent multiple transmissions and thus enhances the battery life of the nodes. We observe that although the smaller backoff window of high-priority traffic category enhances the network throughput, higher intensity of high-priority traffic drives the network faster to saturation. Furthermore, better network stability and fairness among different traffic categories can be achieved when the dominant traffic has low priority.

This paper investigates the cross-correlation characteristics of large-scale parameters (LSPs) and small-scale fading (SSF) for high-speed railway (HSR) multilink propagation scenarios, based on realistic measurements conducted on Beijing to Tianjin HSR line in China. A long-term evolution-based channel sounding system is utilized in the measurements to obtain the channel data. By applying a proposed time-delay based dynamic partition method, multi-link channel impulse responses are extracted from the raw channel data. Then, the statistical results of LSPs, including shadow fading, K-factor, and root-mean-square delay spread are derived and the cross-correlation coefficients of these LPSs are calculated. Moreover, the SSF spatial correlation and cross-correlation of SSF are analyzed. These results can be used to exploit multi-link channel model and to optimize the next-generation HSR communication system.

In communications, channel models are useful approximations to the performance of a real channel, which most of the time is not available for repeated tests. In this work we present the problem of the real Near Vertical Incidence Skywave (NVIS) ionospheric scenario channel sounding, and evaluate the channel propagation characteristics in terms of frequency and time spread, with the final goal of designing a channel model. An NVIS channel model can be obtained from the evaluated channel parameters; however, on one hand, there is the problem of missing data due to bad channel performance in some frequencies, and, on the other hand, the measured parameters have strong dependencies between them that cannot be evinced directly. In this work, we conduct a first set of analyses of the measured parameters of the soundings to determine the dependencies in terms of quality of the channel propagation but refer mainly to the Doppler spread and the delay spread in the sensor. This classification approach allows us to face the second part of the research focusing on the design of the channel model for the ionospheric communication of remote sensors.

We present a frequency-diverse based direction of arrival (DoA) estimation technique for millimetre-wave (mmW) 5G channel sounding. Frequency-diversity enables the creation of spatially incoherent radiation masks to encode the plane-wave signals incident on the radar aperture using a single antenna. Leveraging the frequency-diversity concept, spatial information of the plane-wave projections on the radar aperture is retrieved, resulting in high-fidelity DoA estimations by means of a simple Fourier transform operation applied to the retrieved plane-wave projection patterns. It is demonstrated that using the frequency-diversity concept, DoA estimation can be achieved through a simple frequency sweep, compressing the incoming plane-waves into a single channel through the transfer function of the radar aperture. This results in a significant simplification in the system hardware, requiring only a single antenna to achieve DoA estimation. It is also shown that the proposed technique can simultaneously detect the DoA information for multiple sources with a diffraction limited resolution.

The standard polyphase channelizer from the software-defined radio literature is modified to produce a highly-efficient system for computing the narrowband output samples corresponding to the 64 unmodulated subcarriers in an IEEE 802.11p channel sounding signal. The reduction in computational complexity is important because V2V channel sounding experiments produce very large data files that must be processed as efficiently as possible. The results show that the reduction in the number of real-valued multipliers is more than 200,000 for downsample rates of interest.

Wideband channel emulation is a key component to testing 5G mmWave systems. In this paper we use a channel sounding system to validate a novel real-time Hardware-In-the-Loop (HIL) wideband channel emulator previously designed for the performance evaluation and verification of 5G mmWave systems. The HIL system was designed using novel spectral stitching and channel partitioning. The HIL platform is calibrated and validated in both the time and frequency domains. We then compare back-to-back results using a pair of 60GHz mmWave modems with results for the mmWave modems connected through the RF channel emulator via wideband I/Q up and down conversion. Finally, emulated path loss was generated for an Additive White Gaussian Noise (AWGN) channel to characterize the data throughput versus Signal-to-Noise Ratio (SNR) for a fixed point-to-point deployment using the mmWave modems.

This paper analyzes statistical properties of the wireless vehicle-to-vehicle (V2V) communication channel in mountainous terrain near Provo, Utah with a channel sounding experiment. We employ a software-defined radio (SDR) wideband channel sounder that transmits a 64-carrier unmodulated waveform that conforms to the IEEE 802.11p standard. The channel statistics analyzed are the complementary cumulative distribution function (CCDF) of the received power and its correlation with the line-of-sight (LOS) signal, the power delay profile, and the average delay spread. The experimental results indicate the presence of non-LOS signals that appear capable of supporting short intervals of communication, although the LOS signal is still the dominant factor for V2V communication in mountainous terrain. The power delay profile also indicates the presence of non-LOS signals, and furthermore follows an exponential decay model in general.

Pilot contamination in the uplink (UL) puts asymptotic limits on the downlink (DL) spectral efficiency in time-division duplex (TDD) massive multiple-input multiple-output (MIMO) systems relying on TDD channel reciprocity. Pilot contamination can be induced by the UL pilot reuse across different neighboring cells. In this paper, we show that receiver front-end impairments also contribute to pilot contamination. In particular, we consider a TDD multi-user (MU) massive MIMO orthogonal frequency-division multiplexing (OFDM) system, where either time-division multiplexed (TDM) pilots or frequency-division multiplexed (FDM) pilots are utilized for UL channel sounding. We endeavor to characterize the impacts of the residual timing offsets (TOs) and the carrier frequency offsets (CFOs) on the DL performance of the massive MIMO-OFDM system. Closed-form expressions of the asymptotic DL MU spectral efficiencies are derived in the presence of both TOs and CFOs under different scenarios. Our analytical results reveal how the residual TOs and CFOs destroy the orthogonality among the UL training sequences from different users and give rise to pilot contamination. Specifically, we show that the DL spectral efficiencies become bounded even when the number of antennas goes toward infinity. Furthermore, to alleviate the impacts of TOs and CFOs, we propose different pilot decontamination methods based on our analyses for both the TDM pilots and the FDM pilots. Numerical simulation results corroborate our analyses and designs.

Asynchronous automatic link establishment (ALE) has been utilized for decades in high-frequency communications due to its operational simplicity. During the process of ALE, the nodes select the channel with the best channel quality based on a link quality analysis (LQA) matrix, which is derived mainly from channel sounding. However, some elements in the matrix can be missing because of the failure of the channel sounding caused by interference or noise in the sounding phase. The incomplete LQA matrix may lead to bad channel selection. In this paper, by exploiting characteristics of low rank and periodicity in LQA matrix, a matrix completion approach is introduced to improve the channel selection in the asynchronous ALE with the goal of achieving maximum throughput in the data transmission. Simulation results show that, compared with the algorithm in current high-frequency ALE standard, the proposed approach of channel selection not only effectively selects the channel with the better channel quality, but also reduces the link establishment time, increasing the throughput of data transmission. In addition, the performance of the proposed algorithm approaches the channel selection algorithm with perfect LQA matrix.

To resolve the crowded radio spectrum problem observed in conventional microwave bands (below 6 GHz), new frequency bands higher than 6 GHz are being considered to facilitate the use of a much wider bandwidth for next-generation wireless systems. Various channel sounding measurements have been conducted to elucidate the radio propagation properties at such new frequency bands. For a high-frequency channel sounding measurement, directional scanning with high-gain antennas is a popular method adopted to save the development cost of a full antenna array. This letter presents the analysis of the maximum likelihood multipath component parameter estimation accuracy where a Gaussian beam antenna pattern obtained by the scaled von Mises distribution function is used for the ease of analysis. The numerical analysis shows that the angle estimation error is approximately proportional to the square of the antenna half-power beamwidth (HPBW) and the square root of the angular sampling interval (ASI), respectively, and the amplitude and phase estimation error is approximately proportional to the HPBW and the square root of the ASI, respectively. The intrinsic performance of the used antenna is also discussed.

Advanced public safety communication (PSC) services call for fast, reliable and low-latency communication technologies, capable of supporting diverse communication modes (aerial, unmanned, vehicular, and peer-to-peer), fast channel dynamics, and ad hoc or mesh structures. For this reason, PSC has been identified as one of the key potential uses cases for the next generation of communication systems, the so-called 5G. In this scenario, the millimeter wave (mmWave) bands and other frequencies above 6 GHz are particularly interesting, since they are largely untapped and offer vastly more spectrum than current cellular allocations in the highly congested bands below 6 GHz, thus enabling orders of magnitude greater data rates and reduced latency. For example, new PSC networks in the mmWave bands could support high-definition video, virtual reality, and other broadband data to large numbers of first responders. Surveillance drones or ambulances could also be provided high-speed connectivity along with machine-type communication for remotely controlled robotic devices entering dangerous areas. However, the way towards this ambitious goal is hindered by a number of open research challenges. In this paper, after a brief introduction to PSC services and requirements, we illustrate the potential of the frequencies above 6 GHz for PSC and discuss the open problems that need to be solved in order to pave this way. Finally, we describe the main components of a test platform for mmWave systems that is functional to the study of such complex scenarios and that we plan to develop as an invaluable tool for realizing mmWave PSC networks.

There has been an increasing interest in the millimeter wave (mmW) frequency regime in the design of next-generation wireless systems. The focus of this work is on understanding mmW channel properties that have an important bearing on the feasibility of mmW systems in practice and have a significant impact on physical (PHY) layer design. In this direction, simultaneous channel sounding measurements at 2.9, 29 and 61 GHz are performed at a number of transmit-receive location pairs in indoor office, shopping mall and outdoor environments. Based on these measurements, this paper first studies large-scale properties such as path loss and delay spread across different carrier frequencies in these scenarios. Towards the goal of understanding the feasibility of outdoor-to-indoor coverage, material measurements corresponding to mmW reflection and penetration are studied and significant notches in signal reception spread over a few GHz are reported. Finally, implications of these measurements on system design are discussed and multiple solutions are proposed to overcome these impairments., 13 pages, 8 figures, Accepted for publication at the IEEE Transactions on Antennas and Propagation

The increasing bandwidths and frequencies proposed for new mobile communications give rise to new challenges for system designers. Channel sounding and channel characterization are important tasks to provide useful information for the design of systems, protocols, and techniques to fight the propagation impairments. In this paper, we present a novel radio channel sounder capable of dealing with non-stationary channels. It can be operated in real-time and has a compact size to ease transport. For versatility and cost purposes, the core of the system is implemented in Field Programmable Gate Arrays (FPGAs). Three measurement campaigns have been conducted to illustrate the performance of the sounder in both static and non-static channels. In its current configuration, the sounder reaches an RF null-to-null bandwidth of 1 GHz, providing a delay resolution of 2 ns, a maximum measurable Doppler shift of 7.63 kHz, and 4.29 s of continuous acquisition time. A comparison with other channel sounders in the literature reveals that our proposal achieves a good combination of performance, cost, and size. Xunta de Galicia | Ref. ED481A-2020/049 Xunta de Galicia | Ref. ED431C 2019/26 Agencia Estatal de Investigación | Ref. PID2020-112545RB-C52 Agencia Estatal de Investigación | Ref. TEC2017-85529-C3-3R