Backhaul Research Note: MIMO Backhaul Radios

MIMO (Multiple Input Multiple Output) takes advantage of multipath propagation by sending more than one data stream using exactly the same spectrum. By making calculations with the received signals, MIMO radios are able to separate the different data streams. Although MIMO technology was specific to wireless access technologies initially, the use of sub-6 GHz spectrum for NLOS backhaul applications opened the door for MIMO to be used in the transport network as well. The number of antennas used at each side of the link is specified by two numbers separated by an ?x?. Unlike in radio access systems, backhaul MIMO implementation is always symmetrical, that is, both ends of the link have the same number of antennas.