An Energy-Efficient Hybrid Precoging With Low-Complexity For Mmwave Massive MIMO Systems

Millimeter wave?mmWave?and massive multiple-input multiple-output?MIMO?are key technologies for 5G(5^thGeneration)mobile communication.However,the energy consumption of the RF chain is high for mmWave.Therefore,the high energy consumption is main problem for mmWave massive MIMO systems.Hybrid precoding is necessary in wireless communication.The precoding is divided into fully digital precoding and hybrid precoding.Fully digital precoding cannot be realized due to high energy consumption in mmWave massive MIMO systems.Therefore,the hybrid precoding is adopted in massive MIMO systems to reduce consumption.The hybrid precoding is divided into fully connected architecture and sub-connected architecture.For fully-connected architecture,each RF chain is connected to all BS antennas.While for sub-connected architecture,each RF chain is connected to only a subset of BS antennas.Therefore,it can significantly reduce the energy consumption.But the capacity will also decrease.In this paper,the high energy efficiency and low complexity hybrid precoding in millimeter-wave massive MIMO system is deeply studied against the problem of high hardware energy consumption.The contributions of this paper can be summarized as follows:?1?We propose a kind of architecture for hybrid precoding named partly-connected architecture,which is a trade-off between fully-connected architecture and sub-connected architecture.Although this kind of architecture leads to increasing of the number of PSs,the performance of total achievable rate and the energy-efficiency can be significantly improved.?2?The total achievable rate optimization problem is decomposed into a series of sub-rate optimization problems based on partly-connected architecture.Each sub-rate optimization problem corresponding to sub antenna array is optimized one by one.?3?We propose partly Singular Value Decomposition?SVD?,which can replace SVD.The partly SVD can reduce the complexity of the hybrid precoding based on partly-connected architecture.An energy-efficient hybrid precoding with low-complexity for mmWave massive MIMO systems is obtained.