Advancement of MIMO technology in WiMAX: from IEEE 802.16d/e/j to 802.16m

WiMAX is the first cellular standard that employs OFDMA technology and provides true integrated services for both fixed and mobile broadband access. Among the many new technologies adopted in WiMAX, MIMO antenna technology plays an essential role in delivering fast, rich-content, mobile broadband service reliably over extended coverage areas. In this article we provide a survey on the state of art of MIMO technologies in current WiMAX standards with an emphasis on practical engineering considerations. Moreover, we also briefly discuss the ongoing MIMO technologies in the evolution toward the next-generation WiMAX network.