Massive MIMO Ultra-Efficient Transmission

• Applicants: Professor Dr.-Ing. Eduard Axel Jorswieck; Professor Dr.-Ing. Dirk Plettemeier
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269256272

Wireless communications with more than 100~Gbit/s can be achieved by a very high spectral efficiency, at high carrier frequencies and large bandwidths. In this project, a frequency range of 57--63~GHz and a spectral efficiency of 15~bit/s/Hz using multi-antenna systems with more than 100 antennas at both the transmitter and the receiver (multiple-input multiple-output, MIMO) will be considered. Due to the large bandwidth of 6~GHz a very efficient and simple baseband signal processing technique has to be provided. For example, QPSK modulation on eight parallel spatial multiplexed data streams is sufficient to realize a spectral efficiency of up to 16~bit/s/Hz.In theory, the achievable spectral efficiency scales linearly with the minimum number of antennas at the transmitter nT and the receiver nR, respectively. Hence, a transmission of minimum nT,nR parallel spatial data streams is possible. However, in the implementation of large antenna arrays the following two effects can occur and limit the theoretical result: spatial correlation and coupling of the antennas. Moreover, operating hundreds of antennas simultaneously including the RF frontend at the transmit and receive side of a massive MIMO communication system is not energy efficient. Consequently, a novel design approach is required.This project is intended to fundamentally investigate the feasibility of a system as proposed above. Thereto, a unified model for the spatial correlation and the antenna coupling is going to be induced from field theory and propagation modeling of high frequency technology to stochastic MIMO channel matrices for signal processing and information theory. Also, fundamental limits of the achievable bandwidth efficiency in the target scenario will be derived, taking into account the channel, the antenna characteristics, the available signal processing capabilities in the space, time, and frequency domain, and the channel information. This is achieved using methods of the random matrix theory and the majorization theory. Further, measurements will be taken in the frequency range 57--63~GHz to develop a stochastic channel and antenna model. Field simulations will provide a realistic model of the coupling between the elements of the entire antenna array.Finally, theoretical results, measured and simulated data are going to be used to suggest a system design that provides the following features: an innovative antenna design for massive MIMO systems, an optimal and sub-optimal energy-efficient transceiver design that achieves a bandwidth efficiency of 15~Bit/s/Hz, channel measurements with the new designs and verification of achievable rates, practical validation by data transmission and receiver side bit error rate evaluation using an offline data processing.Altogether, this project will provide both a theoretical contribution to the fundamental limits of massive MIMO systems and a practical design for the 100~Gbit/s wireless data transmission.

• DFG Programme: Research Grants