Danping He

On Indoor Millimeter Wave Massive MIMO Channels: Measurement and Simulation

The millimeter wave (mmWave) communications and massive multiple-input multiple-output (MIMO) are both widely considered to be the candidate technologies for the fifth generation mobile communication system. It is thus a good idea to combine these two technologies to achieve a better performance for large capacity and high data-rate transmission. However, one of the fundamental challenges is the characterization of mmWave massive MIMO channel. Most of the previous investigations in mmWave channel only focus on single-input single-output links or MIMO links, whereas the research of massive MIMO channels mainly focus on a frequency band below 6 GHz. This paper investigates the channel behaviors of massive MIMO at a mmWave frequency band around 26 GHz. An indoor mmWave massive MIMO channel measurement campaign with 64 and 128 array elements is conducted, based on which, path loss, shadow fading, root-mean-square (RMS) delay spread, and coherence bandwidth are extracted. Then, by using our developed ray-tracing simulator calibrated by the measurement data, we make the extensive ray-tracing simulations with 1024 antenna elements in the same indoor scenario, and get insights into the variation tendency of mean delay and the RMS delay with different array elements. It is observed that the measurement and the ray-tracing-based simulation results have reached a good agreement.

Cluster-Based Nonstationary Channel Modeling for Vehicle-to-Vehicle Communications

In this letter, a three-dimensional (3-D) cluster-based nonstationary channel model is proposed for vehicle-to-vehicle (V2V) communications. To efficiently describe the scattering environment and reflect the nonstationarity of V2V channels, the proposed model considers the single- and double-bounced clusters in 3-D space, and includes the effect of activity of clusters by introducing visibility regions. Furthermore, based on the geometrical relationships in the model, the channel impulse response is derived as a sum of the line-of-sight, single- and double-bounced rays, and the space-time-frequency correlation properties are analyzed. Finally, the accuracy of the proposed model is validated by realistic V2V channel measurements.

On the high-speed railway communication at 30 GHz band: Feasibility and channel characteristics

Simulations for studying novel high-speed railway millimeter-wave radio propagation channels in urban city are presented in this paper by using verified ray-tracing tool. Based on setups of three antenna beam steering strategies at transceiver, the comparisons among these strategies are given by system feasibility and radio channel characteristics. Numerical results of the simulations are shown to illustrate that adaptive antenna beam steering could greatly improve system performances. However, jointly using fixed and adaptive beam steering is recommended as a trade off between technology implementation and channel performance. Moreover, the system effects from different distances between base station and railroad track are investigated. By selecting a reasonable distance, the detailed radio channel characteristics are extracted including delay spread and Doppler spread, which could serve as a guide for future physical layer design.

Wideband Channel Modeling for mm-Wave inside Trains for 5G-Related Applications

Passenger trains and especially metro trains have been identified as one of the key scenarios for 5G deployments. The wireless channel inside a train car is reported in the frequency range between 26.5 GHz and 40 GHz. These bands have received a lot of interest for high-density scenarios with a high-traffic demand, two of the most relevant aspects of a 5G network. In this paper we provide a full description of the wideband channel estimating Power-Delay Profiles (PDP), Saleh-Valenzuela model parameters, time-of-arrival (TOA) ranging, and path-loss results. Moreover, the performance of an automatic clustering algorithm is evaluated. The results show a remarkable degree of coherence and general conclusions are obtained.

Calibration of ray-tracing simulator for millimeter-wave outdoor communications

Ray-tracing (RT) simulator plays an important role in analyzing the channel characteristics of radio waves propagation environment. In this paper, the reflection coefficient of the existing ray-tracing simulator is calibrated based on the results measured in New York Universitys (NYU) Manhattan campus at 28 GHz. Both the dielectric constant and loss tangent parameters are optimized by calibration. As the measurement dimension is very limited, calibrated RT simulator can be used more effectively for the outdoor system design in millimeter-wave bands.

Channel characteristics analysis in smart warehouse scenario

Industry 4.0 aims to connect internet to industry, makes the factories more conomic, efficient and smart. In this paper we focus the study on the wireless channel characteristics in smart warehouse at 5.8 GHz, which is a typical scenario of industrial 4.0 at ISM band. we build a smart warehouse scenario in 3D mode, simulate the channel by using ray-tracing method. The main energy in the channel comes from the direct path, and most multi-paths are continuously varying in the mobile channel.

On the Feasibility of High Speed Railway mmWave Channels in Tunnel Scenario

Rail traffic is widely acknowledged as an efficient and green transportation pattern and its evolution attracts a lot of attention. However, the key point of the evolution is how to develop the railway services from traditional handling of the critical signaling applications only to high data rate applications, such as real-time videos for surveillance and entertainments. The promising method is trying to use millimeter wave which includes dozens of GHz bandwidths to bridge the high rate demand and frequency shortage. In this paper, the channel characteristics in an arched railway tunnel are investigated owing to their significance of designing reliable communication systems. Meantime, as millimeter wave suffers from higher propagation loss, directional antenna is widely accepted for designing the communication system. The specific changes that directional antenna brings to the radio channel are studied and compared to the performances of omnidirectional antenna. Note that the study is based on enhanced wide-band ray tracing tool where the electromagnetic and scattering parameters of the main materials of the tunnel are measured and fitted with predicting models.

Determination of Cell Coverage Area and its Applications in High-Speed Railway Environments

In this paper, a determination method of the cell coverage area for the narrow-strip-shaped cells in high-speed railways (HSRs) is proposed, which is of great importance to HSR dedicated communication network planning. A closed-form expression for the cell coverage area is first derived on the basis of the edge outage probability and the propagation channel parameters, and it is found that the linear coverage in HSRs has a higher percentage of coverage area than the traditional circular coverage of cellular systems. For the convenience of link budget computation, we also present a family of curves related with the percentage of linear coverage. Then, the implementation of the proposed determination of cell coverage area is presented, and it is found that the linear cell of HSRs has a larger maximum communication distance than circular coverage. Furthermore, the impact of frequency on the HSR link budget is investigated, and the results show that a lower frequency band reduces the number of the required base stations. The results can be used in designing and optimizing the wireless coverage and the communication network planning of HSR communications.

Stochastic Channel Modeling for Kiosk Applications in the Terahertz Band

Terahertz (THz) Kiosk application offers ultrahigh downloads of digital information to users’ handheld devices. System configuration and multiple paths between the transmitter and receiver have important impact on the achievable data rates. In this paper, the propagation channel of THz Kiosk downloading application is investigated and a stochastic channel model is proposed. Based on channel measurements using a vector network analyzer, a 3-D ray-tracing simulator is calibrated to conduct simulations for an in-depth analysis of the different channel characteristics. Successively, the observed propagation paths are classified and the key channel parameters in time, frequency, and spatial domains are modeled for each type of ray. The resulting stochastic model is evaluated in terms of Rician K-factor and root mean square delay spread. Compared to the reference data, the mean absolute errors of these two metrics of the three investigated scenarios are less than 1.48 dB and 0.07 ns, respectively. The results show that the target 100 gigabits per second data rate is achievable at tens of gigahertz system bandwidth at proper communication distance and higher order modulation schemes. The developed channel model allows system design engineers to generate realizations of propagation channel efficiently for designing Kiosk-fashion close-proximity communication systems in the THz band.

An accelerated algorithm for ray tracing simulation based on high-performance computation

Ray tracing tool has played an important role in communication channel modeling. However, accurate simulation with complex scenario will greatly challenge the computational capabilities of personal computer. In this paper, a novel accelerated algorithm for traditional ray tracing tool was proposed based on high-Performance distribute computers. The comparison between traditional ray tracing tool and extended ray tracing tool shown that the accelerating performance for later is highly significant. Numerical results of the simulations show that, jointly using ray tracing tool and high performance distribute computers have been illustrated to be high efficient way for high accurate simulation of channel.