Channel Sounder Research Articles

Enhancing Bluetooth Channel Sounding Performance in Complex Indoor Environments

Enhancing Bluetooth Channel Sounding Performance in Complex Indoor Environments

A Framework for Developing and Evaluating Algorithms for Estimating Multipath Propagation Parameters From Channel Sounder Measurements

A Framework for Developing and Evaluating Algorithms for Estimating Multipath Propagation Parameters From Channel Sounder Measurements

Blockage Effects of Road Bridge on mmWave Channels for Intelligent Autonomous Vehicles

Vehicular communication and sensing technologies are key to enabling 6G Intelligent Autonomous Transportation Systems (IATS). With the introduction of massive sensors and artificial intelligence (AI) fusion applications, IATS is needed to support data transmission rates up to 10 Gb/s. Millimeter-wave (mmWave) technology has attracted extensive attention owing to abundant spectrum resources, which can support the timely transmission of massive data. However, performance degradation of mmWave due to signal blockage has become one of the critical technical challenges. Road bridges as one of the common obstacles in urban scenarios, which has severe blockage effects on communication links. Therefore, this paper comprehensively studies the impact of road bridge blockage effects on mmWave vehicle-to-infrastructure (V2I) links and proposes an empirical model that can accurately characterize the bridge blockage effect. First, we use a self-developed mmWave channel sounder to carry out channel measurements on typical urban roads. Measurement results indicate that a maximum extra propagation loss of up to 23 dB is caused by road bridges. In addition, to address the deficiencies of existing propagation prediction models, the Single Road Bridge (SRB) model is proposed in this work. This model reveals for the first time the extra propagation loss caused by the road bridge to the channel. Compared with existing models, the SRB model can make the mean absolute error (MAE) and root mean square error (RMSE) within 5 dB. The proposed SRB model is of great value for accurately simulating real-world road bridge blockage events when designing future IATS.

Lessons Learned from a Decade of THz Channel Sounding

Lessons Learned from a Decade of THz Channel Sounding

A Novel Low-Cost Channel Sounder for Double-Directionally Resolved Measurements in the MmWave band

A Novel Low-Cost Channel Sounder for Double-Directionally Resolved Measurements in the MmWave band

A Millimeter-Wave Phased-Array Channel Sounder for Double Directional Communication and Localization Channel Descriptions

A Millimeter-Wave Phased-Array Channel Sounder for Double Directional Communication and Localization Channel Descriptions

A Survey on Channel Sounding Technologies and Measurements for UAV-Assisted Communications

A Survey on Channel Sounding Technologies and Measurements for UAV-Assisted Communications

Virtual Antenna Array Based Channel Sounding at 300 GHz: Implementation and Field Measurements

Virtual Antenna Array Based Channel Sounding at 300 GHz: Implementation and Field Measurements

A Tensor-Based Data-Driven Approach for Multidimensional Harmonic Retrieval and Its Application for MIMO Channel Sounding.

A Tensor-Based Data-Driven Approach for Multidimensional Harmonic Retrieval and Its Application for MIMO Channel Sounding.

Tunable SRS-Aware Robust Coordinated Beamforming Design With Channel Aging

Coordinated beamforming holds tremendous potential to maximize network capacity, whose effect largely depends on the period sounding reference signal (SRS)-based channel sounding. However, the huge discrepancy between the sounding channel and the real-time channel is inevitable and nonnegligible with channel aging, which results in severe degradation of coordinated beamforming gain. In this paper, the discrepancy is modeled as a random error term with the effect of channel aging included, and a robust coordinated beamforming design with channel aging is further proposed, exploiting the potential capacity gain through the channel statistical information, which provides the potential for tuning the SRS period. Specifically, the joint correlation properties of channels are modeled in the random error matrix with the static statistical information collected from practical channel samples. To cope with multiple random terms, the deterministic equivalent method is adopted to obtain the approximate closed-form expression of the ergodic capacity, aiming at deriving a robust beamformer that can achieve a stationary point of the expected weighted sum-rate maximization problem. In addition, by adopting the proposed beamforming design, the tuning guidance for the SRS period is provided for practical networks satisfying different capacity requirements and mobile scenarios. Simulation results show that the proposed design can extend the SRS period more than 1× at 10% capacity loss when user speed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$v=30\rm {km/h}$</tex-math></inline-formula> , compared with the traditional beamforming design.

Path Loss Characterization in an Outdoor Corridor Environment for IoT-5G in a Smart Campus University at 850 MHz and 3.5 GHz Frequency Bands.

The usage scenarios defined in the ITU-M2150-1 recommendation for IMT-2020 systems, including enhanced Mobile Broadband (eMBB), Ultra-reliable Low-latency Communication (URLLC), and massive Machine Type Communication (mMTC), allow the possibility of accessing different services through the set of Radio Interface Technologies (RITs), Long-term Evolution (LTE), and New Radio (NR), which are components of RIT. The potential of the low and medium frequency bands allocated by the Federal Communications Commission (FCC) for the fifth generation of mobile communications (5G) is described. In addition, in the Internet of Things (IoT) applications that will be covered by the case of use of the mMTC are framed. In this sense, a propagation channel measurement campaign was carried out at 850 MHz and 5.9 GHz in a covered corridor environment, located in an open space within the facilities of the Pedagogical and Technological University of Colombia campus. The measurements were carried out in the time domain using a channel sounder based on a Universal Software Radio Peripheral (USRP) to obtain the received signal power levels over a range of separation distances between the transmitter and receiver from 2.00 m to 67.5 m. Then, a link budget was proposed to describe the path loss behavior as a function of these distances to obtain the parameters for the close-in free space reference distance (CI) and the floating intercept (FI) path loss prediction models. These parameters were estimated from the measurements made using the Minimum Mean Square Error (MMSE) approach. The estimated path loss exponent (PLE) values for both the CI and FI path loss models at 850 MHz and 3.5 GHz are in the range of 2.21 to 2.41, respectively. This shows that the multipath effect causes a lack of constructive interference to the received power signal for this type of outdoor corridor scenario. These results can be used in simulation tools to evaluate the path loss behavior and optimize the deployment of device and sensor network infrastructure to enable 5G-IoT connectivity in smart university campus scenarios.

Physical Layer Security: Channel Sounding Results for the Multi-Antenna Wiretap Channel.

Many physical-layer security works in the literature rely on purely theoretical work or simulated results to establish the value of physical-layer security in securing communications. We consider the secrecy capacity of a wireless Gaussian wiretap channel using channel sounding measurements to analyze the potential for secure communication in a real-world scenario. A multi-input, multi-output, multi-eavesdropper (MIMOME) system is deployed using orthogonal frequency division multiplexing (OFDM) over an 802.11n wireless network. Channel state information (CSI) measurements were taken in an indoor environment to analyze time-varying scenarios and spatial variations. It is shown that secrecy capacity is highly affected by environmental changes, such as foot traffic, network congestion, and propagation characteristics of the physical environment. We also present a numerical method for calculating MIMOME secrecy capacity in general and comment on the use of OFDM with regard to calculating secrecy capacity.

Channel measurement and characterisation for 5G multi‐scenarios at 26 and 38 GHz

AbstractMillimetre‐wave (mmWave) frequencies play a vital role in fifth‐generation (5G) wireless systems and beyond due to the vast available bandwidth of several GHz. This paper presents channel characteristics and their channel models for mmWave based on extensive channel measurements at 26 and 38 GHz conducted in 5G scenarios, such as the rooftop, the high‐speed railway, and the Industrial Internet of Things scenarios. The channel sounder receiver (Rx) uses an omnidirectional or phased array antenna to meet the requirements of channel measurement, such as recording absolute delay and obtaining 3‐dimensional angular information. We use the classical close‐in model and floating‐intercept model to model path loss. Meanwhile, channel statistics in the delay domain are derived from the measured power delay profiles. Note that the different scenarios are measured with the same channel sounder, making the measurement results of different scenarios comparable. It is shown that the shadow fading parameter σ is 0.7 dB as fewer large scatterers exist in the rooftop scenario. Moreover, due to the significant dependence of delay spread on the geometric relationship between the transmitter (Tx), Rx, and surrounding environment, the statistical data in the delay domain varies significantly in different scenarios. The channel characteristics and models will guide future air‐interface, beamforming, and transceiver designs for 5G and beyond.

SDR-Based 28 GHz mmWave Channel Modeling of Railway Marshaling Yard.

Compared with railway communication service requirements on the mainline, requirements in hotspots such as stations and yards are more complicated in terms of service types as well as bandwidth, of which railway-dedicated mobile communication systems such as 5G-R facilitated with dedicated frequency support cannot meet the entire communication requirements. Therefore, other radio-communication technologies need to be adopted as a supplement, among which the mmWave communication system is a promising technology, especially for large bandwidth communication between train and trackside. However, there is a lack of evaluation of the 28 GHz mmWave channel characteristics for the railway marshaling yard scenario. In this paper, the railway marshaling yard mmWave propagation scenario is deeply analyzed and classified into three typical categories, based on which, a measurement campaign is conducted using an SDR channel sounding system equipped with a 28 GHz mmWave phased-array antenna. A self-developed software under the LabVIEW platform is used to derive the channel parameters. Conclusions on the relationship between the parameters of MPC numbers, time-spread, and received power and position, as well as the impact of typical obstructions such as the Catenary, adjacent locomotives, and buildings are drawn. The statistical results and conclusions of this paper are helpful for facilitating the design and performance evaluation of future mmWave communication systems for railway marshaling yards and can also be further extended and applied to the research of mmWave utilization in 6G and other future communication technologies for more scenarios.

Multi-Scenario Millimeter Wave Channel Measurements and Characteristic Analysis in Smart Warehouse at 28 GHz

Smart warehouses are revolutionizing traditional logistics operations by incorporating advanced technologies such as Internet of Things, robotics, and artificial intelligence. In these complex and dynamic environments, control and operation instructions need to be transmitted through wireless networks. Therefore, wireless communication plays a crucial role in enabling efficient and reliable operations. Meanwhile, channel measurements and modeling in smart warehouse scenarios are essential for understanding and optimizing wireless communication performance. By accurately characterizing radio channels, communication systems can be better designed and deployed to meet unique challenges in smart warehouse scenarios. In this paper, we present an overview of smart warehouse scenarios and explore channel characteristics in smart warehouse scenarios. We conducted a measurement campaign for millimeter wave radio channels in smart warehouse scenarios. A vector network analyzer-based channel sounder was exploited to record channel characteristics at 28 GHz. Based on the measurements, large-scale channel parameters, including path loss, root-mean-square (RMS) delay spread, and Rician K factor were investigated. The unique channel characteristics in smart warehouse scenarios were explored.

High-Resolution Parameter Estimation for Wideband Radio Channel Sounding

Multidimensional channel sounding measures the geometrical structure of mobile radio propagation. The parameters of a multipath data model in terms of directions, time-of-flight and Doppler shift are estimated from observations in frequency, time and space. A maximum likelihood estimation framework allows joint high-resolution in all dimensions. The prerequisite for this is an appropriate parametric data model that represents the multipath propagation correctly. At the same time, a device data model is necessary that typically results from calibration measurements. The used model should be as simple as possible since its structure has a considerable effect on the estimation effort. For instance, the inherent effort in parameter search is reduced if the influence of the parameters is kept independent. Therefore, the data model is characterized by several approximations. The most important is the “narrowband assumption” which assumes a low relative bandwidth and also avoids considering any frequency response in magnitude and phase. We extend the well-known multidimensional RIMAX parameter estimation framework by including proper frequency responses. The advantage reveals itself with high bandwidth in the mmWave and sub-THz range. It allows for a more realistic modeling of antenna arrays, it breaks with the usual narrowband model and allows a better modeling of mutual coupling and time delay effects. If the interacting object extends over several delay bins (hence an extended target in radar terminology) we propose a model that assigns a short delay spread, respectively a frequency response to the propagation path that associates it to the respective object. We verify the validity of the device model by numerical experiments on simulated and measured antenna data and compare it to RIMAX. Additionally, we use synthetic data based on ray-tracing results and measurements both ranging from 27.0GHz to 33.0GHz with known ground truth information and show that the proposed estimator delivers better performance for higher relative bandwidths than the conventional RIMAX implementation.

Methods to Estimate the Channel Delay Profile and Doppler Spectrum of Shallow Underwater Acoustic Channels

In this paper, we present the methods to detect the channel delay profile and the Doppler spectrum of shallow underwater acoustic channels (SUAC). In our channel sounding methods, a short impulse in form of a sinusoid function is successively sent out from the transmitter to estimated the channel impulse response (CIR). A bandpass filter is applied to eliminate the interference from out-of-band (OOB). A threshould is utilized to obtain the maximum time delay of the CIR. Multipath components of the SUAC are specified by correlating the received signals with the transmitted sounding pulse with its shifted phases from 0 to 2Π. We show the measured channel parameters, which have been carried out in some lakes in Hanoi. The measured results illustrate that the channel is frequency selective for a narrow band transmission. The Doppler spectrum can be obtained by taking the Fourier transform of the time correlation of the measured channel transfer function. We have shown that, the theoretical maximum Doppler frequency fits well to that one obtained from measurement results.

Open-access millimeter-wave software-defined radios in the PAWR COSMOS testbed: Design, deployment, and experimentation

While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will largely facilitate the research and allow the community to make significant progress in this area. In this paper, we present the design and implementation of various programmable and open-access mmWave software-defined radios (SDRs) that have been deployed in the PAWR COSMOS advanced wireless testbed, in both indoor and outdoor environments. These programmable mmWave radios are based on the IBM 28GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RFSoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios.

The Design and Implementation of a Steganographic Communication System over In-Band Acoustical Channels

This article presents SoundSticker, a system for steganographic, in-band data communication over an acoustic channel. In contrast with recent works that hide bits in inaudible frequency bands, SoundSticker embeds hidden bits in the audible sounds, making them more reliably survive audio codecs and bandpass filtering, while achieving a higher data rate and remaining imperceptible to a listener. The key observation behind SoundSticker is that the human ear is less sensitive to the audio phase changes than the frequency and amplitude changes, which leaves us an opportunity to alter the phase of an audio clip to convey hidden information. We take advantage of this opportunity and build an OFDM-based physical layer. To make this PHY-layer design work for a variety of end devices with heterogeneous computation resources, SoundSticker addresses multiple technical challenges including perceivable waveform artifacts caused by the phase-based modulation, bit rate adaptation without channel sounding and real-time preamble detection. Our prototype on both smartphones and ESP32 platforms demonstrates SoundSticker’s superior performance against the state of the arts, while preserving excellent sound quality and remaining unaffected by common audio codecs like MP3 and AAC. Audio clips produced by SoundSticker can be found at https://soundsticker.github.io/ .

Virtual Antenna Array for W-Band Channel Sounding: Design, Implementation, and Experimental Validation

Virtual Antenna Array for W-Band Channel Sounding: Design, Implementation, and Experimental Validation