Massive MIMO: Communicating in the Near Field of a Large Aperture Massive Array System

SupervisorElisabeth de Carvalho, edc@es.aau.dk

Project Description

Massive MIMO [RPL+12] has been recently introduced for cellular networks. In a massive array system, the base stations are equipped with a very large number of antennas. While 4G base stations are expected to have at most 8 antennas, massive BS will be equipped with a number of antennas, larger than 100 and as high as 1000. The main enabler of such systems is the multi-antenna processing at the massive array, which focuses the energy very precisely towards the end user. Therefore no energy is lost in other directions. This enables a longer communication reach, hence a better coverage, very high rates, extreme energy efficiency and reduced inter-cell interference.

In this project, we propose to extend to concept of massive MIMO to an indoor scenario where a massive array of large aperture is deployed to serve as access points for wireless communications in new infrastructures, such as airport halls, shopping malls, stadium, concert stages, etc. Such a large aperture massive array system (LA-MASS) is conceived as part of the new infrastructure and is integrated in its construction. Our general objective is the study of LA-MASS in such a hot-spot area in a multi-user setting where a large array serves multiple users simultaneously. The main characteristic of LA-MASS is that communications happen in the near-field of the array.

The project contains 2 main components:

Channel characterization: the purpose is to exhibit the main properties of the channel in the near field of the massive array, including the following aspects: number of degrees of freedom in the channel, conditioning of the channel, correlation between users, 2D and 3D array configurations. Note that a simulator has been already

Figure 1. Example of deployment of a large aperture array in an indoor environment

developed accounting for the line of sight propagation [A06] [JI05] [SN05]. The students are expected to build on the existing simulator where different scattering distribution will be included.

Communication design: the purpose is an appropriate beamforming design that is adapted to channel characteristics in the near-field. The focus will be given on designs that have a low computational complexity. Schemes that are based on full channel knowledge, or only statistics of the channel can be considered.

Expected Outcome

The students will acquire a deep knowledge on MIMO communications, including propagation, signal processing and information theory aspects. The students will learn and simulate the main MIMO transmission techniques and adapt them to a propagation environment that is different from the environment for which MIMO has been originally proposed.

Prerequisites

Mathematical and statistics fundamentals Linear Algebra Propagation fundamentals Matlab.

References

[RPL+12] F. Rusek, D. Persson, B. K. Lau, E. G. Larsson, T. L. Marzetta, O. Edfors and F. Tufvesson, “Scaling up MIMO: Opportunities and Challenges with Very Large Arrays”, IEEE Signal Processing Magazine, 2012, http://arxiv.org/abs/1201.3210 .

[A06] J.B. Andersen, “Propagation aspects of MIMO channel modelling”, Space-Time Wireless Systems: From Array Processing to MIMO Communications. ed. / H. Bolcskei; C. Papadias; D. Gesbert; A-J van der Veen. Cambridge University Press, 2006.

[JI05] Jeng-Shiann Jiang and M.-A Ingram, "Spherical-wave model for short-range MIMO," IEEE Transactions on Communications, Sept. 2005.

[SN05] I. Sarris and A.R. Nix, "Maximum MIMO Capacity in Line-of-Sight," Fifth International Conference on Information, Communications and Signal Processing, 2005.