Performance Analysis Of Indoor THz Communication With Low-resolution DACs And ADCs

In this paper,we investigate the performance of downlink Terahertz(THz)communication systems with one-bit digital-to-analog converters(DACs)at the Access Point(AP)and finite-bit analog-to-digital converters(ADCs)at user sides and discussed in three cases.Array-of-subarrays architecture is assumed for the antennas at the AP,where each RF chain uniquely activates a disjoint subset of antennas,each of which is connected to an exclusive phase shifter.Hybrid beamforming,with analog beamforming and digital beamforming,is applied,and consider the digital precoding such as maximum ratio transmission(MRT)and zero-forcing(ZF)precoding.Through theoretical analysis and numerical simulation results,we find that the best beamsteering direction for the phase shifters in the large subarray antenna regime is first proved to be the direction of the line-of-sight(LoS)path.Subsequently,the closed-form expression of the lower-bound of the achievable rate in the large subarray antenna regime is derived,which is the same for both MRT and ZF and is independent of the transmit power.Moreover,the rate loss caused by the phase uncertainties can be negligible in large subarray antenna regime.Numerical results validating the analysis are provided as well.Overall,the impact of one-bit precoding and finite-bit ADCs on the achievable rate of indoor THz communication systems is characterized.