An Overview of Massive MIMO Research at the University of Bristol

Abstract

Abstract-Massive Multiple-Input, Multiple-Output (MIMO) has rapidly gained popularity as a technology crucial to the capacity advances required for 5G wireless systems. Since its theoretical conception six years ago, research activity has grown exponentially, and there is now a developing industrial interest to commercialise the technology. For this to happen effectively, we believe it is crucial that further pragmatic research is conducted with a view to establish how reality differs from theoretical ideals. This paper presents an overview of the massive MIMO research activities occurring within the Communication Systems & Networks Group at the University of Bristol centred around our 128-antenna real-time testbed, which has been developed through the Bristol Is Open (BIO) programmable city initiative in collaboration with National Instruments (NI) and Lund University. Through recent preliminary trials, we achieved a world first spectral efficiency of 79.4 bits/s/Hz, and subsequently demonstrated that this could be increased to 145.6 bits/s/Hz. We provide a summary of this work here along with some of our ongoing research directions such as large-scale array wave-front analysis, optimised power control and localisation techniques.

Employing Ray-Tracing and Least-Squares Support Vector Machines for Localisation

“…Ray-tracing is conducted at a carrier frequency of 3.51 GHz to match the carrier frequency used on the Bristol massive MIMO testbed [ 12 ]. The transmit power is set to 32 dBm and the receiver sensitivity is configured to be −120 dBm.…”

“…This meant that, no ray data was generated for those links and consequently those mobile positions were excluded from the study. In all ray-tracing data generation, the parameters are chosen to match those of the massive MIMO testbed at Bristol University [ 12 ]. Key outputs from the ray-tracer, that are used in this study, are the BS and MS locations (x and y coordinates), the azimuth AOA at BS, the received power and the time delay, for each ray or path.…”

A Brief Survey on 5G Wireless Mobile Network

“…Bristol and Lund University with National Instruments (NI) achieved a spectral efficiency of 79.4 bits/s/Hz for the first time, and are trying to increase it to 145.6 bits/s/Hz. All of these results were accomplished via the real-time 128-antenna massive-MIMO testbed, which has been developed by the programmable city initiative-Bristol Is Open (BIO) with National Instruments (NI) and Lund University [70]. Along that they are working in many fields including client localisation, wave front analysis and optimised power control algorithms.…”

Design and Prototyping of Hybrid Analog–Digital Multiuser MIMO Beamforming for Nonorthogonal Signals

“…Multiple input multiple output (MIMO) is now widely used to improve capacity and achieve diversity and multiplexing gains. There are a number of renowned MIMO testbeds such as Argos [15], Ngara [16], TitanMIMO [17], Lund University's MIMO [18] and Bristol University's MIMO [19]. To achieve high diversity and multiplexing gains, pure digital precoding is normally used to pre-equalize inter-user interference in MIMO systems.…”