Utilization of multiple non-orthogonal polarization channel with reduced correlation using polarization reuse transmitter antenna for 5G MIMO channel capacity enhancement

Abstract

5G communication promises fast and large data stream which requires higher capacity of a cellular wireless network. A higher capacity could be achieved with wider bandwidth and network densification, but they are expensive approaches. Instead, upgrading the wireless network with higher-order Multiple Input Multiple Output (MIMO) antenna system with polarization diversity can inexpensively escalate the peak data rate for higher capacity. In the present scenerio, the application of multiple polarization in MIMO communication system is limited to only two polarization, which are orthogonal to each other. The orthogonality of polarization is important for low channel correlation and to provide high communication capacity. However, the orthogonal polarization condition limits the data rate in the present scenario where both the base station and mobile phones are equipped with high number of antennas, at least 4. A 3-sector 4x4 MIMO is the current state of the art in a cellular network. 4 terminals in Tx and Rx counterparts with 4 polarization can improve the system communication data rate if correlation among 4 non-orthogonal polarization could be minimized. We proposed and evaluated 4 polarization 4x4 MIMO system, each antenna with unique polarization, for the current 4T4R cellular network. A systemic theoretical analysis is performed to find the suitable choice of 4 polarization for 4x4 MIMO 5G NR network in order to enhance the network capacity. 4 polarization (vertical, Horizontal, ±45◦ slant) MIMO system is analysed and optimized to perform better than conventional dual polarized MIMO system with separation of 0.5λ. In order to further improve the 4 polarization system performance with co-located and smaller separation of 4 polarized antennas, polarization reuse diversity technique is introduced. In polarization reuse technique, the antenna beam are separated by an optimized angle to reduce the correlation among the channel formed with 4 polarization. With the novel polarization reuse technique, the 4 polarized 4T4R MIMO system with 0.5λ separation as well as ‘zero’ separation among antennas are analyse to perform better than baseline dual pol MIMO system. This beam-separated polarization reuse technique minimizes the channel correlation which maximizes the probability of four independent data streams (rank 4). The field trial of the presented network indicates a higher portion of rank 4, supporting four independent data streams in the rich scattering environment of a cellular network. The important fact of the present work is that proposed scheme does not require changing the size of the existing BS and does not require more number of antennas compared to the existing BS for channel capacity enhancement. Also, the proposed scheme of beam separated multi-polarized antenna can be a good candidate for mMIMO system for increasing number of Tx antenna in compact form.