Spatial dynamics of the 5G millimetre wave channel

Transcription

1 Spatial dynamics of the 5G millimetre wave channel Evangelos Mellios (and colleagues ) Group University of Bristol, UK

2 Introduction 2 5G: The Internet of everyone and everything, everywhere. The vision of the next-generation of communication networks and services is to provide ubiquitous super-fast connectivity and seamless service delivery in all circumstances. [

3 Introduction 3 New applications (e.g. smart cars, smart cities and smart homes ) impose new requirements: Low latency for real-time performance High reliability and very wide area coverage Gigabit data rates and high-quality coverage Billions of connected devices (Internet-of-Things IoT) Virtualised infrastructure of scalable, low-cost systems (Software Define Networks SDNs)... and new 5G enabling technologies must be developed, such as: Millimetre wave (mmwave) communications Sub-6GHz Massive MIMO systems

4 mmwave communications 4 Current wireless systems (e.g. 4G and Wi-Fi) use frequency bands below 6GHz where the available bandwidth is scarce. The large available bandwidth in mmwave bands (up to 100GHz) will enable gigabit data rates. In order to overcome the high path loss as well as the high losses due to blockage from obstacles at these high frequencies, the use of adaptive beamforming and beamtracking techniques is crucial. [ [

5 mmwave communications 5 Characterisation of the wireless channel at mmwave frequencies is important in order to efficiently design, develop and deploy such systems, especially for high-speed mobile applications where the spatial dynamics of the channel change rapidly. Strategic collaboration with Keysight Technologies (USA): World-leading mmwave channel sounder

6 Diffuse scattering measurements 6 Measurements performed at 26GHz and at 60GHz for all polarisation combinations using a bandwidth of 2GHz. The Tx position was fixed and the Rx was mounted on a trolley and moved along an arc recording a channel snapshot every 4mm. Directional antennas (gain of 22dBi at 26GHz and 26dBi at 60GHz) were pointing continuously at the same point on the surface of interest. 1m 14.5 RX Surface ϕi=45 90 RX 135 TX [A.L. Freire, T. Pelham, D. Kong, L. Sayer, V. Sgardoni, F. Tila, E. Mellios, M.A. Beach, A.R. Nix, and G. Steinbock, Polarimetric diffuse scattering channel measurements at 26GHz and 60GHz, 29 th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 9-12 Sep. 2018, Bologna, Italy.]

7 Diffuse scattering measurements 7 Top : Tx pointing at concrete wall Bottom : Tx pointing at metallised window Left : 60 GHz Right : 26 GHz RX TX

8 Diffuse scattering measurements 8 Rough stone wall Left : 60 GHz Right : 26 GHz

9 Diffuse scattering measurements 9 Example frequency responses of the co-pol and cross-pol signal at 60GHz for the concrete wall measurement for a 2cm displacement in the (Left) specular area ( ); (Rght) non specular area ( )

10 Diffuse scattering measurements 10 XPR across the 2GHz bandwidth at 60GHz for a vertically polarised transmitter. Left: Metallised window Right: Stone wall

11 Diffuse scattering modelling 11 Diffuse scattering model for mmwave links based on the Kirchoff model [L. Sayer, A.L. Freire, A.R. Nix, and E. Mellios, A Kirchhoff scattering model for millimetre wavelength wireless links, 12 th European Conference on Antennas and Propagation (EuCAP), 9-13 Apr. 2018, London, UK.]

12 Propagation modelling 12 Indoor and outdoor 3D ray-tracing propagation modelling and planning tools are developed and tuned with the aid of detailed channel measurements.

13 Propagation modelling 13

14 Simulations and hardware-in-the-loop testing 14 The ray-tracing channels are combined with system-level simulators to predict the end-to-end performance of a mmwave communication system*. The ray-tracing channels are also loaded onto a Keysight F8 Propsim channel emulator, and real mmwave modems are connected to the input and output with the aid of up- and down-converters (converting the mmwave signal to an IF frequency suitable for the emulator). We can now measure the performance of 5G hardware in the lab under totally controlled and repeatable channel conditions. [ Collaboration with New York University* ] * [M. Zhang, M. Mezzavilla, R. Ford, S. Panwar, S. Rangan, E. Mellios, D. Kong, A.R. Nix, and Michele Zorzi, Transport layer performance in 5G mmwave cellular, Invited Paper Infocom Millimeter-wave Networking Workshop (mmnet 2016), 11 Apr. 2016, San Francisco, USA.]

15 Conclusions 15 Diffuse scattering at mmwave frequencies may generate large channel variations over very short travel distances (just a few centimetres), which affect not only the received signal strength but also the polarisation characteristics of the signal, even within the channel bandwidth. This may add tough challenges to the design of beam forming / tracking algorithms and equalisers. Using data sets from measurement campaigns is important to inform ray tracers and help calibrate the necessary model parameters, as well as determine the level of detail that is necessary to be considered in the geospatial and building databases. Combining ray-tracing channels with system-level simulators and channel emulators allows the design and testing of a mmwave communication system under controlled and repeatable realistic channel scenarios.

16 Acknowledgments 16 The diffuse scattering channel measurements were supported by Huawei Technologies Thanks to all the students, staff and ex-colleagues at the University of Bristol who helped with this work: Mr Alberto L. Freire, Dr Di Kong, Professor Andrew Nix, Professor Mark Beach, Dr Timothy Pelham, Mr Lawrence Sayer, Dr Victoria Sgardoni, Dr Fai Tila, Mr Denys Berkovskyy, Dr Tom Barratt, Dr Berna Bulut, Dr Jue Cao, Dr Angelos Goulianos, Dr Ghaith Al Juboori, Dr Vaia Kalokidou, Mr Khalid Al Mallack and Mr Stavros Typos.

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