Channel Modeling for UCA and URA Massive MIMO Systems

Abstract

In this paper, we change the geometric structure of antenna array and extend our previous channel model of massive MIMO system with uniform linear array (ULA) to that of massive MIMO systems with uniform circular array (UCA) and uniform rectangular array (URA). Three massive MIMO systems with UCA, URA and ULA antenna array structures are named as UCA, URA and ULA Massive MIMO Systems, respectively, whose performance are analyzed and compared. The ULA massive MIMO system can make full use of space degree of freedom due to the large antenna array to achieve the best performance, however it is very difficult to be installed and placed on Base Station (BS) due to the large antennas array. The UCA massive MIMO system outperforms the URA massive MIMO system in many communication scenarios. The URA massive MIMO system is also sensitive to the elevation angle spread (EAS) by developing the degree of freedom in the vertical direction, and the spherical wave (SW) effect is very weak for URA antenna array because of the compact antenna structure. Finally, we give some guidelines for choosing the appropriate antenna array structures according to the communication scenarios and requirements.