Deployment and implementation strategies for massive MIMO in 5G

Massive MIMO has emerged as one technology enabler for the next generation mobile communications 5G. The gains promised by massive MIMO are augured to overcome the capacity crunch in today's mobile networks and to pave the way for the ambitious targets of 5G. The challenge to realize massive MIMO for 5G is a successful and cost-efficient integration in the overall network concept. This work highlights deployment and implementation strategies for massive MIMO in the context of 5G indoor small cell scenarios. Different massive MIMO deployment scenarios are analyzed for a standard 3GPP indoor office scenario. In particular stand-alone MIMO at a single location, distributed MIMO without cooperation and network MIMO with full cooperation are investigated for varying array configurations. For the performance analysis of the different MIMO configurations the ratio of total transmit antennas to spatial streams is varied stepwise from equality to a factor of ten. For implementation of massive MIMO in 5G networks trends in beamforming techniques, mutually coupled subarrays, over the calibration procedure and estimated ADC performance in 2020 time-frame are discussed. Based on the debate the paper indicates how to integrate large-scale arrays in future 5G networks.