Low Complexity RF Front-End for Hybrid mmWave MIMO 5G Mobile Networks

2019 Grand Prize Winner
Queen’s University Belfast, ECIT, Centre for Wireless Innovation

Dr. Muhammad Ali Babar Abbasi

PostDoc Research Fellow, Centre of Wireless Innovation (CWI)

5G NR standards are now set and deployment is on its way. Extensive research has shown that multi-input multi-output (MIMO) has the capabilities to meet the high data rate demand of 5G mobile users. Many scenarios have already been tested, but we’re still facing at least 3 main challenges in optimizing mmWave massive MIMO solutions. The first challenge is the huge losses faced by the electromagnetic waves while propagating through the free space in millimetre wave frequencies, hence highly directive radiation is desirable.

Second challenge is the requirement of a network of phase-shifters and power dividers to add steering capabilities is lossy and expensive in mmWave frequencies.

Finally the third challenge, the theoretical principles of MIMO require each antenna to be connected separately to the baseband processing unit, making the overall system cost prohibitively high, especially when we talk about 64 or 128 element massive MIMO system. I therefore propose a two-stage Rotman lens based uniform rectangular array (URA) beamformer, as an RF front-end solution for hybrid mmWave MIMO base stations. This solution attempts to find the best trade-off between cost, complexity and performance.

My design represents a full end-to-end mmWave hardware. The basic requirements considered in developing the beamformer are in line with the ITU standards for mmWave 5G. Unlike existing solutions that require dedicated RF chains per antenna, my approach massively reduces the complexity and the cost of mmWave MIMO RF front-ends in 5G mobile networks.

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