Multiband User Equipment Prototype Hardware Design for 5G Communications in Sub-6-GHz Band

Verification of physical (PHY) layer and medium access control (MAC) layer procedures of the fifth-generation (5G) specifications with real hardware prototypes is important in the commercialization of 5G mobile communication systems and is challenging as well. In this paper, we propose a flexible software-defined-radio (SDR)-based prototype hardware design for user equipment (UE), which can be used to implement novel 5G communication concepts. The proposed hardware architecture is featured by using a flexible baseband signal processing module and two independent programmable wideband radio frequency (RF) front ends that, respectively, cover the lower and higher frequencies of sub-6-GHz band. The flexibility of the baseband signal processing module is ensured by using four powerful field-programmable gate arrays (FPGAs) running the PHY entities and a powerful FPGA-based system-on-chip running the MAC entities. The flexibilities of the RF front ends lay in the facts that: 1) the design covers three sub-6-GHz frequency bands, that is, 2.5, 3.5, and 4.9 GHz; 2) it can support dual connectivity for the upcoming 5G networks; and 3) it enables carrier aggregation (CA) over up to three carriers to achieve 300-MHz bandwidth. Accordingly, this prototype is capable of verifying the complicated scheduling procedures, evaluating the sophisticated signal processing algorithms in both PHY and MAC layers, and supporting the 100-MHz 4T4R multiple-input multiple-output (MIMO) or 200-MHz 2T2R MIMO techniques. Experiments have been performed on 256-QAM modulated waveforms to assess transmission power, error vector magnitude, adjacent channel leakage ratio from the UE side, and peak data rates between a base station and the UE.