Binghao Chen

In this paper, the impact of mutual coupling on LTE-R MIMO capacity for antenna array configurations in high speed railway scenario is investigated. In order to evaluate the impact of mutual coupling for different antenna array configurations, the extended 3D clustered channel model is presented primarily in this paper. The impact of mutual coupling can be added to channel models using coupling matrix which is modeled based on S-parameters obtained from CST Microwave Studio. We study the impact of coupling on LTE-R MIMO capacity from the perspective of antenna array configurations: antenna array deployment, interelement spacing and fixed total physical space. The simulations illustrate that the impact on the capacity caused by mutual coupling is significant and differs among various antenna array configurations, which yields meaningful insight into the LTE-R antenna array configurations in high speed railway scenario.

Some channel characteristics in high-speed railway, such as path loss and Ricean K factor, have been intensively studied in several certain scenarios. Due to the limitation of channel measurement, some small-scale channel properties, especially the DoA (Angle of Departure) and AoA (Angle of Arrival) information, which is important for a MIMO channel model, are difficult to estimate from the current data. In this paper, the semi-deterministic method based upon geometry-based stochastic channel modeling is applied on cutting scenario. Some channel parameters are extracted from the Zhengxi high-speed railway measurement. The other part of the model is based on cutting geometry and cluster analysis. The cluster size is determined by the channel parameters. And the variation of the cluster size over the distance from the train is investigated.

The need for improving the safety and the efficiency of transportation systems has become of extreme importance. In this regard, the concept of vehicle-to-X (V2X) communication has been introduced with the purpose of providing wireless communication technology in vehicular networks. Not like the traditional views, the wide-sense V2X (WSV2X) communications in this paper are defined by including not only vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications but also train-to-X (T2X) communications constituted of train-to-train (T2T) and train-to-infrastructure (T2I) communications. All the information related to the wide-sense V2X channels, such as the standardization, scenarios, characters, and modeling philosophies, is organized and summarized to form the comprehensive understanding of the development of the WSV2X channels.

A discussion about which of the two factors, rich multipath (in NLOS) or signal-to-noise ratio (SNR) (usually in LOS), affects the Multiple-Input Multiple-Output (MIMO) channel capacity more is presented in this paper. This interesting discussion is investigated by performing simulations using simple circle scatterer model and WINNER II channel model. And the simulation shows that these two factors behave differently as the channel condition varyies. When the scatterer number in channel is low, the high receive SNR is more important to capacity. The multipath richness will have greater influence when the scatterer number exceeds a certain threshold. However, the channel capacity will not change much as the scatterers continue to increase.

The geometry-based stochastic channel models are proposed in this paper for the terrain cutting, suburb, and urban scenarios in high-speed railway. First, the special scenarios in high-speed railway are described. And the channel models based on the geometry scenarios are introduced. Some channel parameters are based on measurement data. Then, the space-time correlation functions in analytical form are obtained in suburb and urban scenarios. Finally, the space correlation characteristics in three scenarios are compared.

Radio wave propagation scene partitioning is necessary for wireless channel modeling. As far as we know, there are no standards of scene partitioning for high-speed rail (HSR) scenarios, and therefore we propose the radio wave propagation scene partitioning scheme for HSR scenarios in this paper. Based on our measurements along the Wuhan-Guangzhou HSR, Zhengzhou-Xian passenger-dedicated line, Shijiazhuang-Taiyuan passenger-dedicated line, and Beijing-Tianjin intercity line in China, whose operation speeds are above 300 km/h, and based on the investigations on Beijing South Railway Station, Zhengzhou Railway Station, Wuhan Railway Station, Changsha Railway Station, Xian North Railway Station, Shijiazhuang North Railway Station, Taiyuan Railway Station, and Tianjin Railway Station, we obtain an overview of HSR propagation channels and record many valuable measurement data for HSR scenarios. On the basis of these measurements and investigations, we partitioned the HSR scene into twelve scenarios. Further work on theoretical analysis based on radio wave propagation mechanisms, such as reflection and diffraction, may lead us to develop the standard of radio wave propagation scene partitioning for HSR. Our work can also be used as a basis for the wireless channel modeling and the selection of some key techniques for HSR systems.

The impact of antenna array geometry on MIMO (Multiple-input Multiple-output) system in high speed railway scenario is investigated in this paper. The capacity of different antenna arrays and the effect of ULA (uniform linear array) azimuthal orientation on capacity are studied with a double-directional channel model including antenna effects and Doppler shift.

This paper summaries the new topics about MIMO (Multiple-input-multiple-output) channel modeling. The scenarios are focused on transportation, such as VTV (Vehicle-to-Vehicle) and high speed railway. The sparse channel and time-variant channel are discussed. Afterwards, some novel methods for MIMO channel modeling are described and challenges for each method are summarized.