Tetsuro Imai

5G 3GPP-Like Channel Models for Outdoor Urban Microcellular and Macrocellular Environments

For the development of new 5G systems to operate in bands up to 100 GHz, there is a need for accurate radio propagation models at these bands that currently are not addressed by existing channel models developed for bands below 6 GHz. This document presents a preliminary overview of 5G channel models for bands up to 100 GHz. These have been derived based on extensive measurement and ray tracing results across a multitude of frequencies from 6 GHz to 100 GHz, and this document describes an initial 3D channel model which includes: 1) typical deployment scenarios for urban microcells (UMi) and urban macrocells (UMa), and 2) a baseline model for incorporating path loss, shadow fading, line of sight probability, penetration and blockage models for the typical scenarios. Various processing methodologies such as clustering and antenna decoupling algorithms are also presented.

Time-Varying Path-Shadowing Model for Indoor Populated Environments

This paper presents a path-shadowing model for indoor populated environments that has been developed based on computer simulations. The propagation paths between the transmitting and receiving points in an empty rectangular space are determined using the ray-tracing method, in which moving quasi-human bodies that are modeled as cylinders with a finite height are generated in the space, and intersections of the paths with the bodies are counted. From the results, the shadowing probabilities, durations, and intervals are evaluated for each propagation path, and this shadowing process is characterized as a Markov process. This paper proposes a method that individually generates the shadowing effects on each propagation path. The measurement results of the path-shadowing characteristics using a 5.2-GHz high-resolution channel sounder are presented, and the validity of this model is confirmed. Similar measurement results using a photoelectric sensor are also presented to reinforce the channel-sounding measurement results.

Indoor 5G 3GPP-like channel models for office and shopping mall environments

Future mobile communications systems are likely to be very different to those of today with new service innovations driven by increasing data traffic demand, increasing processing power of smart devices and new innovative applications. To meet these service demands the telecommunications industry is converging on a common set of 5G requirements which includes network speeds as high as 10 Gbps, cell edge rate greater than 100 Mbps, and latency of less than 1 msec. To reach these 5G requirements the industry is looking at new spectrum bands in the range up to 100 GHz where there is spectrum availability for wide bandwidth channels. For the development of new 5G systems to operate in bands up to 100 GHz there is a need for accurate radio propagation models which are not addressed by existing channel models developed for bands below 6 GHz. This paper presents a preliminary overview of the 5G channel models for bands up to 100 GHz in indoor offices and shopping malls, derived from extensive measurements across a multitude of bands. These studies have found some extensibility of the existing 3GPP models (e.g. 3GPP TR36.873) to the higher frequency bands up to 100 GHz. The measurements indicate that the smaller wavelengths introduce an increased sensitivity of the propagation models to the scale of the environment and show some frequency dependence of the path loss as well as increased occurrence of blockage. Further, the penetration loss is highly dependent on the material and tends to increase with frequency. The small-scale characteristics of the channel such as delay spread and angular spread and the multipath richness is somewhat similar over the frequency range, which is encouraging for extending the existing 3GPP models to the wider frequency range. Further work will be carried out to complete these models, but this paper presents the first steps for an initial basis for the model development.

Identification of Scattering Objects in Microcell Urban Mobile Propagation Channel

A series of measurements in two streets in a dense urban area were accomplished. The measurement scenario was small microcell line-of-sight (LoS) with low antenna height at both link ends where dipole sleeve transmitter (Tx) antenna, directive receiver (Rx) antenna, wideband pseudo-noise (PN) signal and correlator were employed. We analyze the data obtained from the measurements by careful investigation of the single-bounce scattering power distribution conforming to precise maps of the environments including all present objects. We try to identify the single-bounce scatterers for the cluster received waves appearing in the single-bounce scattering power distribution. A number of objects were identified by this method as single-bounce scatterers within the spatial resolution bins. The identified objects are signboards, traffic signs, etc. and we conclude that any metallic object visible to both Tx and Rx with dimensions in orders of tens of wavelengths can be a significant source of scattering in small cell scenarios with low antenna heights. The contribution of the scattering from these identified objects to the received power compared to other micromechanisms is evaluated. Results show that the scattering from these objects can be comparable to the wall reflections

Statistical scattering model in urban propagation environment

A statistical scattering model for mobile radio channels that has the following three features is proposed: 1) the effective scattering area (ESA) is expressed by an ellipse, the center of which is the mobile station (MS) location; 2) the major axis of the ellipse runs parallel along the street where the MS is located; and 3) the scattering power density function around the MS is expressed by a combination of two Laplacian distributions in which the standard deviations are different. To verify the proposed model and obtain realistic values for the model parameters, the spatiotemporal path data observed at a base station (BS) were measured using a 2.2-GHz band in a macrocell scenario (BS antenna height is 60 m) in a typical urban area. The scattering positions are detected from the path information such as the azimuth arrival angle and path length, assuming a single bounce. The spatial distribution of the scattering power is analyzed using principal component analysis. The results showed the ESA to be the anticipated ellipse with the major and minor axes of approximately 210 and 120 m, respectively (axis ratio: approximately 1.7). Furthermore, the power profiles that are projected for each axis of the ellipse can be approximated as Laplacian distributions. Finally, simplification of the proposed model is discussed

Frequency-Agile Pathloss Models for Urban Street Canyons

Frequency-agile pathloss models for urban street canyons are discussed in this paper. The models are floating intercept (FI), fixed reference (FR), and ITU-R M.2135 urban microcellular (UMi) line-of-sight (LOS) and Manhattan-grid non-LOS (NLOS) models. These models are parameterized based on channel sounding campaigns in three cities covering radio frequencies ranging from 0.8 to 60 GHz. Fitting the models with measured pathloss reveals that the models are usable to cover the considered frequency range. The FI and FR models are equally simple and robust, with a slight advantage of the FI model in accuracy because of the larger number of model parameters. The original M.2135 LOS model is based on a two-ray model that includes a break point (BP). The model is extended for a better fit with measurements by including new model parameters such as a pathloss offset and a BP scaling factor that represent local scattering conditions of surrounding environments. The new model parameters are found frequency dependent in many cases. The original M.2135 model is furthermore simplified in NLOS scenarios while maintaining the model accuracy. The model parameters are derived using maximum likelihood estimation, which also showed that the modified M.2135 model offers up to 50% better accuracy compared to the FI and FR models in terms of the employed log-likelihood function (LLF). The improvement in accuracy is particularly remarkable in NLOS scenarios. A full set of parameters is provided for the models, allowing a choice for any given requirements on accuracy and complexity. Finally, applicability of the proposed models to other street canyons is discussed using independent pathloss measurements.

Wideband Polarimetric Directional Propagation Channel Analysis Inside an Arched Tunnel

A wideband directional measurement campaign was managed inside an arched highway tunnel to analyze the radio propagation channel inside such tunnel for future cellular systems in terms of coverage, delay spread and dominant scatterers. Measurements were performed in 3 rounds with different transmitter positions. Using a wideband channel sounder equipped with a cylindrical dual polarized array at the receiver, the spatio-temporal characteristics of the received propagation paths could be estimated by means of a super-resolution estimation algorithm. The extracted paths using this super-resolution algorithm constitute 88% of the total received power. It was also observed that the line-of-sight component (53%) plus single-bounce scattering (26%) comprise up to 79% of the total received power. In other words, more than 90% (i.e. 79% in 88%) of the extracted paths consists of the line-of-sight component and single-bounce scatterings. The strong contribution from single-bounce scattering paths causes the path gain exponent along the tunnel to be larger than -2 which is the value for free space. This validates that there is wave guiding effect in the tunnel and coverage is extended relative to open space. The rms delay spreads are generally less than 20 ns and increase when influenced by scattering objects such as jetfans. The dominant scatterers are identified and classified into 6 classes based on the structure of the tunnel and existing objects such as ground, wall, light-frame, ceiling, jetfan and cleaner-parking. It was observed that scattering from ground was dominant among all classified scatterers in all scenarios.

Interference Cancellation Using Relay Station in Heterogeneous Networks

This paper proposes interference cancellation that utilizes relay stations (RSs).In Long Term Evolution (LTE)-Advanced, heterogeneous networks in which femto and picocells are overlaid onto macrocells are extensively discussed. However, interference between macro and pico(femto)cells arises due to their different transmit power levels. Unlike conventional cooperative transmission schemes, the RS decodes interference in the first transmit timing period and forwards it to the user equipment (UE) in the second period. Moreover, cooperative transmission can be achieved without stopping the transmission from the base station (BS) to UE when forwarding the interference from the RS to the UE by utilizing the fact that signal to noise power ratio (SNR) between the RS and UE is much greater than that between the BS and UE. The effectiveness of the proposed method and the optimal relay arrangement are shown based on computer simulation when considering heterogeneous pathloss models.

Basic study on spatio-temporal dynamic channel properties based on channel sounder measurements

On the air (OTA) measurement has attracted attention as a method for evaluating MIMO user equipment (UE), and represents a promising candidate for the LTE and IMT-Advanced systems. Moreover, we have to simulate spatiotemporal dynamic channel properties in the OTA measurement systems to evaluate MIMO systems with dynamic radio resource assignment. In this paper, we report the basic studies of the spatio-temporal dynamic channel properties based on the measured data obtained using the channel sounder in an outdoor environment to establish the dynamic channel model for the spatial fading emulator (SFE) in order to evaluate MIMO UEs.

Analysis of DSRC Service Over-Reach inside an Arched Tunnel

In this paper, the prediction of received power in the out-of-zone of a dedicated short range communications (DSRC) system operating inside a typical arched highway tunnel is discussed. By conducting wideband directional channel sounding inside the tunnel, the gain, angle-of-arrival and delay of each propagation path are estimated by means of a multidimensional maximum likelihood estimation algorithm from the measured data. Using these estimated parameters and by employing simulations of application antennas according to the DSRC standard, the received power in the out-of-zone is predicted for 2 roadside unit (RSU) antenna positions. The dominant scatterers causing the over-reach of radiated power to the out-of- zone were identified and attributed to the ground and sidewalk. These scatterers can affect the received power level in the out- of-zone by as much as 10 dB. It can therefore be concluded that suppressing ground and sidewalk scatterings in the vicinity of RSU by installing composite pavement materials are needed to increase the electromagnetic absorption in order to guarantee DSRC services.