Human Blockage Research Articles

Blockage loss and shadow fading behavior of millimeter‐wave signals due to human bodies at 28 GHz

AbstractAs the millimeter‐wave (mm‐Wave) spectrum is considered to be an essential enabler to the fifth generation (5G) wireless communication systems. Human movements are one of the most significant factors that cause transient blockage in indoor mm‐wave channels. In this letter, human blockage measurements and shadow fading statistics due to human body movements in an indoor office environment are reported for the 28 GHz band. The effect of human bodies on the channel is measured for several scenarios including a variety of population and using diverse antenna heights. The reported shadow fading statistics include both the duration and the depth of the blockage fade, and accordingly, we propose several empirical models that cater for such blockage events. The findings reported in this letter could improve the modeling of indoor radio channels at 28 GHz bands by considering the presence of humans, as well as their movements.

Multi-Wavelength Path Loss Model for Indoor VLC with Mobile Human Blockage

Visible light communication (VLC) is one of the candidate technologies for the sixth generation (6G) networks. The path loss model is particularly important for link budget estimation and network planning in VLC. Due to the wideband nature and the extremely poor diffraction capacity of light, the path loss of the VLC channel is susceptible to wavelength dependence and blockage effect. In this paper, we propose a novel path loss model which can characterize the impact of wavelength dependence combined with mobile human blockage for both the single-LED (light emitting diode) and the multi-LED scenario. When there is no blockage in the channel, the multi-wavelength path loss under free space propagation is modeled with a small standard deviation of 0.262 in the single-LED scenario and a small root mean square error of 0.009 in the multi-LED scenario which indicates the high accuracy of the model. When considering the mobile human blockage, the blockage probability (BP) is modeled with full consideration of realistic human mobility and human body shadowing. The results indicate that the BP in single-LED scenario can reach 0.08, while the BP in multi-LED scenario is 0.022. This demonstrates that the distributed deployment of transmitters can effectively reduce the occurrence of the blockage state in VLC.

Distributed Reconfigurable Intelligent Surfaces for Energy-Efficient Indoor Terahertz Wireless Communications

With the fifth-generation (5G) networks widely commercialized and fast deployed, the sixth-generation (6G) wireless communication is envisioned to provide competitive quality of service (QoS) in multiple aspects to global users. The critical and underlying research of the 6G is, firstly, highly dependent on the precise modeling and characterization of the wireless propagation when the spectrum is believed to expand to the terahertz (THz) domain. Moreover, future networks' power consumption and energy efficiency are critical factors to consider. In this research, based on a review of the fundamental mechanisms of reconfigurable intelligent surface (RIS) assisted wireless communications, we utilize the 3D ray-tracing method to analyze a realistic indoor THz propagation environment with the existence of human blockers. Furthermore, we propose a distributed RISs framework (DRF) to assist the indoor THz wireless communication to achieve overall energy efficiency. The numerical analysis of simulation results based on more than 2,900 indoor THz wireless communication sub-scenarios has demonstrated the significant efficacy of applying distributed RISs to overcome the mobile human blockage issue, improve the THz signal coverage, increase signal-to-noise ratios (SNRs), and QoS. With practical hardware design constraints investigated, we eventually envision how to utilize the existing integrated sensing and communication techniques to deploy and operate such a system in reality. Such a distributed RISs framework can also lay the foundation of efficient THz communications for Internet-of-Things (IoT) networks.

A Body-Blockage Analysis and Comparison Between Humans and a Full-Body Phantom: Using measurements at 28 GHz

Human blockage is an important phenomenon that should be considered in millimeter-wave (mm-wave) communication systems. Realizing that blockage behavior could be very valuable in mm-wave link simulations, several blockage models have been proposed in previous works based on knife-edge diffraction (KED), high-frequency simulations, and measurements. This article investigates blockage using a full-body phantom and proves that a body phantom is accurate enough to replace a human subject in blockage studies for both data and talk modes. A campaign of measurements for these two modes with 17 human subjects of different heights and genders is conducted. The effect of different types of clothing on body blockage is studied for a body phantom and a human subject. The impact of the relative antenna-user position on the body-blockage intensity is investigated as accurate measurements are difficult to achieve with human subjects.

Modeling and measurement of human body blockage loss at 28 GHz

ABSTRACT Millimeter-wave (mm-Wave) spectrum is an essential enabler to the fifth generation (5G) wireless technology. Humans are one of the most noticeable blockers that cause temporal variation in indoor radio channels. This paper presents human blockage measurements at 28 GHz, with several humans of different sizes. The effect of the crossing orientations of the human bodies is investigated for three different transmitter heights. A human blockage model based on the Fresnel diffraction scheme is shown to be applicable in estimating the human blockage loss in indoor radio links considering various body sizes, different crossing orientations, and different transmitter heights. The findings reported in this paper could help improve indoor radio channel models at 28 GHz bands for 5G technologies considering the presence of human body blockages.

Channel Measurements and Modeling for Low Terahertz Communications in an Aircraft Cabin

The low terahertz band (0.1–1 THz) offers very high data rates for novel mobile applications and constitutes a promising candidate to meet the requirements in aviation, enabling future wireless in-flight entertainment (IFE) systems. An extensive knowledge of the propagation effects in the radio channel in complex scenarios is a prerequisite to successfully design a communication system. This article presents a measurement campaign in a real aircraft investigating the radio channel at 300 GHz for different deployments of a wireless IFE system. The propagation effects as well as temporal and spatial channel characteristics are analyzed for likely communication links between an access point and a user equipment (UE). In the same way, interference links between two UEs are studied, reporting transmission and reflection losses for various components of the aircraft. A deterministic and geometry-based channel model is derived and extended to cover the effect of human blockage that suggests an integration of the access point into the passenger service unit. The measurement and realistic path loss models can be used in further link and system level simulations and contribute to the design of future IFE systems.

Indoor mm-Wave Coverage Enhancement: Reconfigurable Intelligent Surface Deployment Strategy Based on Human Mobility Model

Reconfigurable intelligent surface (RIS) is regarded as a promising technology to assist indoor millimeter wave (mm-Wave) communication due to its ability to manipulate electromagnetic waves directionally. Due to the complexity of indoor environment, different RIS deployment strategies significantly affect the system performance. However, the existing work investigating RIS indoor deployment ignored the influence of human mobility to indoor signal coverage, therefore a practical indoor deployment strategy remains unknown. In this letter, based on the consideration of human blockage to mm-Wave signal and probability distribution of human location, we propose an indoor RIS deployment strategy with human mobility model to minimize the outage probability, which is more applicable to the realistic indoor environment. An algorithm is presented to minimize the outage probability at a subspace scale of the room geometry and calculate the corresponding RIS location for single RIS deployment and multiple RISs cooperative deployment. Numerical results are provided to display how our deployment strategy works, which indicate that deploying RIS correctly can decrease the indoor communication outage probability significantly.

Impact of Human Blockage on Dynamic Indoor Multipath Channels at 27 GHz

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.

Broadband Channel Based on Polar Codes At 2.3 GHz Frequency for 5G Networks in Digitalization Era

This research using a polar code and without polar codes -based broadband channel that is affected by human blockage using one of the 5G cellular network frequencies at 2.3 GHz, 99 MHz bandwidth, 128 blocks of Fast Fourier Transform (FFT) with Cyclic prefix-Orthogonal Frequency Division Multiplexing ( CP-OFDM) and Binary Shift Keying (BPSK) modulation. The use of high frequencies causes the technology to be sensitive to the surrounding environment and attenuation such as human blockage. The purpose of this research is to determine the performance results and analyze the BER parameters that use polar codes and without polar codes on 5G network broadband channels that are affected by human blockage. Broadband channel modeling on a 5G network is presented in a representative Power Delay Profile (PDP) with the influence of human blockage, which is obtained as many as 41 paths which have multiple delays of 10 ns on each path. This research also uses the scaling method on representative PDP because the use of FFT will produce 128 blocks, and the results of this scaling show that there are 9 lanes with multiple delays of 50 ns. The results of this study are close to the average Bit Error Rate (BER) of 10-4. BER performance without polar code is affected by human blockage requires Signal to Noise (SNR) of 30 dB, for theory BER on BPSK modulation requires SNR of 34.5 dB and BER performance using polar code only requires SNR of 23 dB. These results indicate that using a polar code can reduce or save power usage by 7 dB without a polar codes. Polar codes can minimize errors in the 5G network system, because polar codes are one of the strong codes and are one of the channel coding recommended by ITU to be applied to 5G network systems

Sub-terahertz propagation characteristics up to 150 GHz for 6G mobile communication systems

AbstractExtreme-high-speed communication exceeding 100 Gbps is one requirement for 6G. To satisfy extreme-high-speed-communication, one solution is to utilize terahertz bands above 100 GHz. To determine the new radio-interface technologies and service frequency bands for 6G, terahertz propagation characteristics above 100 GHz need to be understood. In this paper, we introduce our new radio-network topology for 6G and then show the frequency dependency of key propagation phenomena such as the characteristics of path loss in an urban environment, human blockage, and scattering from a rough building surface up to 150 GHz. Human blockage loss increases and the scattering is more diffused as the frequency increases. In the path-loss characteristics, it was found that path-loss frequency dependency is stronger than that given by conventional path-loss model because of scattering effects from a rough building surface.

Performance Analysis at different millimetre wave frequencies for indoor shopping complex and outdoor UAV applications towards 5G

This paper provides descriptions and implementations of NYUSIM, a novel framework for simulation of networks and applications for the three essential characteristics of channel design, spatial consistency, human blockage, and outdoor-to-indoor penetration. This paper also introduces NYUSIM 2.0, an enhanced channel simulator that can simulate spatially consistent channel parameters according to the NYUSIM 2.0 drop-dependent simulator. The 5 G Network Analysis special interest community introduced a parabolic model for outdoor-indoor penetration failure to model the excess route failure due to penetration through buildings and enforced in NYUSIM 2.0. It is a powerful measuring-based channel emulator for the fifth generation and beyond the configuration and measurement of the mm-Wave communication network.

Throughput and Delay Performance Measurements in Multi-Floor Building Employing Private LTE

The private LTE/5G networks are now getting a lot of attention since it can offer a secure and flexible indoor network such as smart factories and buildings by the cellular-based technologies. However, the cell planning and physical layer parameter optimization to achieve the wide indoor coverage and low latency, which are important performance in such deployments, remain very important and difficult issues to be solved. Therefore, this paper measures the reference signal received power (RSRP), throughput, and delay performance with the shared extended global platform (sXGP) system following TD-LTE specification employing the 1.9 GHz band with 5 MHz bandwidth in the multi-floor building. We employ the automated guided vehicle (AGV), which enables highly accurate measurements while moving at walking speed. We measure the indoor spatial distribution of the performance under various conditions, such as opening and closing of doors and human blockage. Since the delay performance depends more on the physical layer procedure and parameter settings such as scheduling request (SR) periodicity than on the channel conditions, we evaluate the influence of the SR periodicity on the delay performance, and analyze the physical layer procedure in detail. We estimate the delay based on the analysis, and show that the estimated and the measured delays are in good agreement.

Scalable Modeling of Human Blockage at Millimeter-Wave: A Comparative Analysis of Knife-Edge Diffraction, the Uniform Theory of Diffraction, and Physical Optics Against 60 GHz Channel Measurements

Scalable Modeling of Human Blockage at Millimeter-Wave: A Comparative Analysis of Knife-Edge Diffraction, the Uniform Theory of Diffraction, and Physical Optics Against 60 GHz Channel Measurements

Millimeter-Wave Human Blockage Model Enhancements for Directional Antennas and Multiple Blockers

The Third Generation Partnership Project (3GPP) has defined a blockage model as an add-on feature to the channel model used in its evaluations of the physical layer in the 0.5-100 GHz frequency range. This letter focuses on the human body blockage losses in the millimeter-wave band proposing: (i) a new criterion to place the diffraction points over the edges of the blockers that considers the precise position of the blocker with regard to the line-of-sight between the transmitter and the receiver, (ii) a specific criterion to determine which potential blockers, from a set of human bodies present in a certain scenario, should be considered effective blockers given the positions of a transmitter, a receiver, and those bodies, and (iii) a modification of the model to provide more accurate estimations in the case in which several blockers are closely located. The validity of our criteria and the accuracy improvement are confirmed by a set of measurements performed at 30 GHz with directional antennas and with multiple human blockers in different positions.

Human Blockage Loss Characteristics of 5 GHz Wi-Fi Band in a Crowded Stadium

This letter reports on human body blockage loss characteristics based on the measurement results under unoccupied and crowded conditions in a stadium environment. The measurements were taken at the Japan National Stadium, which will be used at the opening ceremonies of the Tokyo 2020 Olympics and Paralympics (which is postponed until 2021). We measured the received signal strength with smartphones [user terminals (UEs)] using the Wi-Fi signal from various access points (APs) laid inside the stadium for actual service. The measurement data were acquired at the opening event of the Japan National Stadium on December 21, 2019, and the measurements were performed both in the unoccupied environment before the event and in the crowded environment after the event started. We analyzed the human blockage loss characteristics by comparing the measurement data taken under the crowded and unoccupied conditions and clarified the location dependence and time variation characteristics of the human blockage loss in a crowded stadium. The results showed that while the location dependence of the human blockage loss does not depend on the distance between the APs and UEs, it does differ depending on the location and follows a normal distribution with a median value of 7.2 dB and standard deviation of 5.5 dB. We also found that the time variation characteristics of human blockage loss follow a normal distribution with a standard deviation of 2.4 dB.

An experimental study of the performance of IEEE 802.11ad in smartphones

We present the first extensive measurement study of the performance of the 60 GHz 802.11ad technology on commercial smartphones. We focus on five major perspectives: (i) TCP throughput and communication range in static scenarios, (ii) spatial and temporal variations, (iii) coverage, (iv) performance under realistic smartphone user mobility patterns, and (v) impact of human blockage. We also compare for the first time 802.11ad against its two main competitors in the 5 GHz band: the state-of-the-art 802.11ac and the upcoming 802.11ax, which also promises multi-Gbps data rates. Finally, we present a preliminary evaluation of the 802.11ad power consumption on a smartphone under Gbps data rates. Overall, our results show that, in spite of earlier concerns, 802.11ad has higher potential to address the needs of emerging bandwidth-intensive applications in smartphones than its 5 GHz counterparts. At the same time, our study identifies several open challenges and key research directions towards fully realizing this potential for future smartphone users.

Geometrical-Empirical Channel Propagation Model for Human Presence at 60 GHz

Previous efforts to develop simulation and/or measurement-based channel propagation models for the effect of human blockage on millimeter-wave communication systems have yielded important results, but lack either accuracy, generality, or simplicity. To fill that void, in this paper we propose a hybrid geometrical-empirical model for human presence; we refer to it as human presence because reflection from the body before and after blockage occurs in addition to diffraction around the body during blockage (as in previous efforts) is incorporated. Specifically, propagation is modeled as the superposition of the main transmission path and reflected and/or diffracted paths from the body; the geometrical component of the model accounts for the phase of each path while the empirical component accounts for its amplitude. To validate the proposed model and extract its empirical parameters, an exhaustive measurement campaign with 120 blockage scenarios, comprising varying human subjects and transmitter-human-receiver configurations, was conducted; a total of 180,000 channel acquisitions was recorded with our precision, state-of the-art 60-GHz channel sounder. The overall model is shown to be computationally efficient yet general enough to accurately represent a wide range of scenarios.

Modeling Human Blockage at 5G Millimeter-Wave Frequencies

Millimeter-wave (mm-wave) spectrum unravels the humongous and accelerating demand for wireless data rates and, therefore, it will be a fundamental ingredient of the fifth-generation (5G) wireless technology. In case of mm-wave access links, humans are the most noticeable blockers of electromagnetic waves from access points to mobile stations and hence cause temporal variation in the radio channel. This article presents human blockage measurements in the anechoic chamber at 15, 28, and 60 GHz frequencies employing 15 human subjects of different sizes and weights. An effective 3-D human blockage model as a double-truncated multiple knife-edge (DTMKE) scheme is also proposed. By calculating diffraction from the DTMKE, the frequency, body orientation, and antenna height dependence of the blockage are most accurately reproduced compared to the existing models, such as absorbing double knife-edge model and third-generation partnership project (3GPP) human blockage model. The results demonstrate that the losses are proportional to the cross section of the human body with respect to the radio link. Furthermore, the blockage loss decreases as the height of the transmitting antenna increases.

Millimeter-Wave Base Station Diversity for 5G Coordinated Multipoint (CoMP) Applications

Millimeter-wave (mmWave) will be used for fifth-generation (5G) wireless systems. While many recent empirical studies have presented propagation characteristics at mmWave bands, macrodiversity and Coordinated Multipoint (CoMP) have not been carefully studied. This paper describes a large-scale mmWave base station diversity measurement campaign at 73 GHz in an urban microcell (UMi) in downtown, Brooklyn, NY, USA, and provides the first detailed analysis of CoMP and macrodiversity performance based on extensive measurements. The research employed nine different base station locations in a 200 m by 200 m area and considered 36 individual transmitter-receiver combinations for extensive co- and cross-polarized varying directional beam channel impulse response measurements. From the measured data, hypothesis testing with cross-validation shows that large-scale shadow fading of directional path loss at an RX from multiple base stations can be modeled as being independent. To consider life-like human blockage in CoMP and macrodiversity analysis, simulated human blockage traces are superimposed on the directional measurements to quantitatively show that a user that is served by multiple base stations undergoes dramatically less outage in the presence of rapid fading events, compared to a single serving base station. Moreover, the base station diversity measurements are used to determine the effectiveness of downlink precoding techniques for mmWave CoMP. While results show that the coordination can improve network performance by suppressing interference when it exists, nearly half of the 680 000 directional CoMP measurements (~43%) result in no interference for either user, meaning that macrodiversity alone may offer sufficient link and capacity improvement and that CoMP may not be necessary for interference coordination at mmWave when narrow directional beams are used.

Joint User-AP Association and Resource Allocation in Multi-AP 60-GHz WLAN

The advancement of integrated millimeter-wave products opens the possibility of leveraging communications in 60-GHz band to meet the unprecedented traffic demand in WLAN. Despite the vast bandwidth available, millimeter-wave signals suffer from high attenuation and weak diffraction ability. Therefore, wireless communication at 60 GHz is characterized by the inherent directivity and susceptibility to blockage. Multiple Access Point (AP) architecture is proposed for 60-GHz WLAN to enhance spatial reuse and survive blockage. In the presence of multiple APs in the network, this paper addresses the important problem of user-AP association and resource allocation. We study three schemes of different complexity and investigate how to maximize user throughput with joint consideration of AP assignment and transmission scheduling. To solve the formulated problem, we propose a branch-and-cut-based solution procedure. We perform a detailed comparative analysis of the three schemes and advocate to use one-shot AP assignment-based scheduling scheme due to its simplicity and good performance. To deal with real-time traffic and human blockage, we propose an online algorithm to implement the one-shot AP assignment-based scheme to avoid frequent service disruption. Our results show that the proposed online algorithm is competitive when compared with the optimal offline algorithm.