Channel models are important tools to evaluate the performance of new concepts in mobile communications. However, there is a tradeoff between complexity and accuracy. In this paper, we extend the popular Wireless World Initiative for New Radio (WINNER) channel model with new features to make it as realistic as possible. Our approach enables more realistic evaluation results at an early stage of algorithm development. The new model supports 3-D propagation, 3-D antenna patterns, time evolving channel traces of arbitrary length, scenario transitions and variable terminal speeds. We validated the model by measurements in a coherent LTE advanced testbed in downtown Berlin, Germany. We then reproduced the same scenario in the model and compared several channel parameters (delay spread, path gain, K-factor, geometry factor and capacity). The results match very well and we can accurately predict the performance for an urban macro-cell setup with commercial high-gain antennas. At the same time, the computational complexity does not increase significantly and we can use all existing WINNER parameter tables. These artificial channels, having equivalent characteristics as measured data, enable virtual field trials long before prototypes are available.
The main objective of this paper is to present major challenges regarding the fifth generation (5G) mobile communications propagation modelling work in the European 7th framework project METIS (Mobile and wireless communications Enablers for the Twenty-twenty Information Society). The goal of the propagation work in METIS is to provide adequate propagation models for 5G. For this purpose corresponding deficiencies of present commonly used models are identified. Further, the lack of available channel models for several propagation scenarios has been assessed. Based on this assessment the framework of 5G channel modelling is sketched. As propagation measurement campaigns are a crucial part of this work they are illustrated with a few examples
It is common to use channel models such as the 3GPP spatial channel model (SCM), the WINNER model or ray tracing to evaluate multiple-antenna multiple-user techniques in wireless communications. Cross-polarized antennas can enhance the channel rank and thus the throughput of such systems especially in case of a line-of-sight (LOS) connection. This requires an exact model of the polarization characteristics. To increase the accuracy of the existing channel models, we propose a new method that predicts the polarization state of a microwave link based on findings in the field of optics. We verified the method by cross-polarized multiple-input-multiple-output (MIMO) measurements at 2.6 GHz with 16 transmitters and ten receivers in an urban macrocell environment under strong LOS conditions in downtown Berlin, Germany. Comparisons of simulation and measurement results show that the coefficients of the polarized LOS channel can be predicted very well by the new method. Measured capacities at 10-dB signal-to-noise ratio (SNR) were in between 14.2 and 19.1 b/s/Hz-values that can be predicted by the channel model with more than 90% accuracy. This increase in modeling accuracy is an important feature for many applications such as heterogeneous networks, space-to-ground satellite communications, and cooperative communications.
As 4G wireless networks are vastly and rapidly deployed worldwide, 5G with its advanced vision of all connected world and zero distance communications is already at the corner. Along with the super quality of user experience brought by these new networks, the shockingly increasing energy consumption of wireless networks has become a worrying economic issue for operators and a big challenge for sustainable development. Green Transmission Technologies (GTT) is a project focusing on the energy-efficient design of physical-layer transmission technologies and MAC-layer radio resource management in wireless networks. In particular, fundamental trade-offs between spectrum efficiency and energy efficiency have been identified and explored for energy-efficiency-oriented design and optimization. In this article, four selected GTT solutions are introduced, focusing on how they utilize the degrees of freedom in different resource domains, as well as how they balance the trade-off between energy and spectrum efficiency. On top of the elaboration of separated solutions, the GTT toolbox is introduced as a systematic tool and unified simulation platform to integrate the proposed GTT solutions together
Optical and microwave engineers ask for the required data rates when developing fourth generation (4G) mobile backhaul solutions. Backhauling emerges into an important question since advanced interference mitigation techniques are used to improve the performance at the cost of higher backhaul traffic. In this paper, we provide an efficient method for estimating the backhaul traffic when using joint transmission (JT) coordinated multi-point (CoMP). With this technique, a cluster of base stations (BSs) performs joint signal processing to cancel the mutual interference between adjacent cells. The information exchange between the BSs depends on the cluster size that can be very dynamic depending on the actual interference situation at the mobile terminal. We observe that, on average, 2/3 of the exchange requires inter-site links. This simplifies the analysis and we can refer to the cluster size distribution to compute the backhaul traffic. Results depend on a threshold in the mobility management and on the antenna down-tilt. During busy hours, operators can serve up to 1.3 Gb/s per cell in 50 MHz bandwidth. Backhaul traffic for JT CoMP can reach 5 and 20 Gb/s per triple-sector site for up- and downstream, respectively
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