Testing 5G: evolution or revolution?

The emergence of the fifth generation of mobile communications with its emphasis on massive MIMO and channel bandwidths over 1 GHz at mmWave frequencies is set to change everything we used to know about the design, validation and operation of cellular systems. This paper looks at the technical implications of the validation of cellular systems, and in particular the necessity of moving to radiated testing of systems where beam-steered antenna arrays are used at both ends of the link in highly dynamic 3D fading environments. This testing challenge is unprecedented in the history of cellular radio. Credible solutions need to be found urgently if the timescales for the proposed deployment of 5G in 2020 are to be realized.