Xiongwen Zhao

Channel Measurements, Modeling, Simulation and Validation at 32 GHz in Outdoor Microcells for 5G Radio Systems

In this paper, based on outdoor microcellular channel measurements at 32 GHz for 5G radio systems, a comprehensive channel modeling, simulation, and validation are performed. The directional-scan-sounding measurements using a horn antenna rotated with an angular step at the receiver are carried out, which constitutes a virtual array to form a single-input multiple-output radio channel. The directional- and omni-directional path-loss models are developed by using close-in and floating-intercept methods. Non-parametric and parametric methods are applied to extract large-scale channel parameters (LSPs). The non-parametric method is based on the definition of a channel parameter, whereas the parametric method is derived by the space-alternating generalized expectation–maximization (SAGE) algorithm, which can de-embed an antenna pattern. It is found that the LSPs in the angular domain are significantly different by using the two methods; however, the LSPs in the delay domain almost stay the same. By comparing the LSPs with the parameter table at 32 GHz with 3GPP standard, it is found that 3GPP LSPs should be corrected at the International Telecommunications Union-assigned millimeter wave (mmWave) frequencies for 5G. In this paper, the channel simulation is implemented by using the quasi-deterministic radio channel generator (QuaDRiGa) platform recommended by 3GPP. By comparing the LSPs with the simulated and measured results, it is found that QuaDRiGa is a good platform at the mmWave band, even if it is originally developed for channel simulation below 6 GHz. The results of this paper are important and useful in the simulations and design of future 5G radio systems at 32 GHz.

Mobile-to-Mobile Wideband MIMO Channel Realization by Using a Two-Ring Geometry-Based Stochastic Scattering Model

Abstract In this paper, a geometry-based stochastic scattering model (GBSSM) for wideband multiple-input multiple-output mobile-to-mobile (M2M) isotropic scattering fading channels is proposed. The model is based on a two-ring scattering model which can be applied for the line-of-sight (LOS) and non-LOS scenarios by considering the single- and double-bounced components. The target of developing the GBSSM is to realize the channel in typical environments for future internet-of-thing networks such as shopping malls, logistics centers and so on to be used in the link and system level simulations in M2M new radio systems. The channel realization in this paper is more straight forward and concise to study the channel characteristics compare with the too complicated analytical solutions available so far.

mmWave channel sounder based on COTS instruments for 5G and indoor channel measurement

5G, the new generation of mobile networks, attracts lots of interests and attentions in wireless communication with its aggressive performance goals. To be able to provide much higher data rate than today, 5G mobile networks will operate at frequencies higher than the crowded frequency bands used today, with broader bandwidth. Understanding the propagation characteristics of the wireless channel under the new frequency bands is essential for the research of 5G mobile networks. This requires a channel sounder (CS) system for channel measurement and modeling. To meet the 5G performance goals, 5G channel sounder is required to support mmWave frequency bands, ultra-broad bandwidth and massive multiple-input/multiple-output (MIMO). These requirements can be very challenging for design and implementation. In this paper, we provide a novel mmWave channel sounder architecture which can use commercial Off-The-Shelf (COTS) instruments to set up the system with high performance and reliability to meet 5G channel sounder requirements. We show validation test results to prove the mmWave channel sounder system performance. 1GHz bandwidth SISO channel measurement campaign in open office has been done at 26GHz.

Two-Cylinder and Multi-Ring GBSSM for Realizing and Modeling of Vehicle-to-Vehicle Wideband MIMO Channels

A new geometry-based stochastic scattering model (GBSSM) for wideband multiple-input-multiple-output vehicle-to-vehicle (V2V) channels is proposed in this paper. The proposed GBSSM with cross-polarized antennas combines three-dimensional two cylinders to model the stationary scatterers and two-dimensional multirings to imitate the moving scatterers. The channel realization by using the channel matrix in this paper is much more straightforward and concise to study the channel characteristics compared with the too complicated analytical solutions available so far. Because V2V propagation channels are nonstationary, the time-varying channel properties and parameters are further investigated based on the proposed GBSSM and realized channels, which can be used in the link and system-level simulations in V2V radio systems.

Energy-Efficient Routing Algorithm Based on Multiple Criteria Decision Making for Wireless Sensor Networks

To solve the problem of using a single routing method and insufficient dynamic adjustment ability in existing energy-efficient routing algorithms for wireless sensor networks, a novel routing algorithm is presented in this paper, which turns the selection of next hop into a multiple criteria decision making procedure. First of all, the concept of potential energy in classical physics is introduced to create a hybrid virtual potential field, then chaos genetic algorithm is adopted to optimize the weight of each potential field, so that the data packet is forwarded to the next hop driven by the joint force generated from the hybrid virtual field and finally reaches the sink. Simulation results show that, the proposed scheme performs better on the effectiveness as well as balance of nodes energy consumption and prolongs the network lifetime compared with the existing typical energy-efficient routing algorithms.

Wideband Millimeter-Wave Channel Characterization Based on LOS Measurements in an Open Office at 26GHz

This paper presents wideband millimeter-wave channel characterization based on measurements at 26GHz with 1GHz bandwidth carried out in an open office at KeySight Beijing, China, which is a representative of an indoor hotspot scenario. In the time domain measurements, an omni-directional biconical horn is used as the transmitter, while at the receiver a 26dBi horn is applied and rotated with 5o angular step in the whole azimuth plane, and from -10o - 30o in the elevation plane with 10o angular step. Based on the line-of-sight (LOS) measured channel impulse responses at 39 locations, this paper investigates the directional and mean path-loss models and their relevant shadow fading. The channel parameters such as root mean square (RMS) delay spread, RMS angular spread at the azimuth and elevation planes, Ricean factor and power angular profiles (PAPs) etc. are analyzed for the purpose of channel simulations and propagation mechanism studies at 26GHz.

A 3D geometry-based scattering model for vehicle-to-vehicle wideband MIMO relay-based cooperative channels

In this paper, a three-dimensional (3D) geometry-based stochastic scattering model (GBSSM) for wideband multi-input multi-output (MIMO) vehicle-to-vehicle (V2V) relay-based cooperative fading channel based on geometrical three-cylinder is proposed. Non-line-of-sight (NLOS) propagation condition is assumed in amplify-and-forward (AF) cooperative networks from the source mobile station (S) to the destination mobile station (D) via the mobile relay station (R). We extend the proposed narrowband model to wideband and also introduce the carrier frequency and bandwidth into the model. To avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions, the channel is realized first. By using the realized channel matrix, the channel properties are further investigated.

Comparisons of Channel Parameters and Models for Urban Microcells at 2 GHz and 5 GHz [Wireless Corner]

The goal of this paper was to find the differences of the channel models and parameters as well as the correlations of the channel parameters between 2 GHz and 5 GHz with 100 MHz bandwidth when measurements were performed in exactly the same routes for urban microcells. The path-loss models and shadow fading were studied by using single-input single-output (SISO) measurements. The channel characteristics were investigated by the rms delay spread, rms angular spread, shadow fading, Ricean factor, number of clusters, cross-polar discrimination, and channel capacities using both SISO and MIMO (multiple-input multiple-output) measurements. Static measurements at 5 GHz were also performed in both micro- and macro-cells to investigate clustering effects. Moreover, the channel models and parameters were compared with WINNER work to test their validity in urban microcells. The main conclusion was that the 2 GHz and 5 GHz frequencies can have different propagation behaviors causing the independent channel parameters. However, it was found that their coherence bandwidths were highly correlated. The WINNER path-loss models over-estimate the path losses, both in the line-of-sight (LOS) and non-line-of-sight (NLOS) street canyons where strong guided waves exist. Irrespective of carrier frequencies, the channel parameters offered by WINNER may roughly estimate the channel by implementing its generic model.

A Non-Stationary Geometry-Based Street Scattering Model for Vehicle-to-Vehicle Wideband MIMO Channels

In this paper, a non-stationary geometry-based street scattering model for wideband multi-input multi-output vehicle-to-vehicle fading channels is proposed. It is assumed that the static scatterers on the both roadsides are uniformly distributed on time-varying ellipses, and the mobile scatterers are uniformly distributed in time-varying segments of the road. Both the relatively low- and high- speed mobile scatterers are under consideration, and the velocity distributions of the low- and high- speed moving scatterers are assumed to follow exponential and mixed Gaussian, respectively. In this work, we extend the proposed narrowband model to wideband and also introduce the carrier frequency and bandwidth into the model. In order to avoid complicated procedure in deriving the analytical expressions of the channel parameters and functions, the channel is realized first, then the channel properties and parameters are investigated.

Positioning Algorithms by Information Fusion in Wireless Sensor Networks

To overcome the disadvantages of the positioning technologies by fuzzy theory in Wireless Sensor Networks (WSNs), positioning algorithms based on information fusion are presented in this article. The fuzzy theory is used to deal with the randomness and fuzziness in the WSNs. And the information fusion is introduced to improve the location accuracy. If the collinearity of the anchor nodes is larger, the misjudged reference nodes may be caused. They are removed by using clustering method. The algorithms in this paper can enhance the location accuracies compared with using the fuzzy theory and alleviate the effect of the RSSI (Received Signal Strength Indication) measure errors. Moreover, the algorithms avoid the high complexity of computation and the requirement of more anchor nodes. Simulation results indicate that the algorithms are more precise, robust as well as with good suitability.