Microwave connectivity is a technology that uses a wireless link between two points.  This technology is extremely reliable, with high bandwidth capacity when using these types of links.  It provides several important benefits: When using microwave, the infrastructure is only at the two end points (or ALMR towers) with nothing in-between.  Contrast that with fiber optic cable, which is often buried or strung on power poles.  That type of connection is at risk from intentional or accidental disruption due to digging or other activity.
Microwave connections are much easier to establish than a terrestrial cable, due to the lack of extensive infrastructure required.  This allows the State to create a network based on the needs of the system, and provides for redundancy at many sites.  With two microwave connections at a site, that allows the radio traffic to take either path.  That means in case of a failure or scheduled maintenance, the ALMR site remains online.
There are some disadvantages.  Mainly, the connections require extremely accurate alignment and line of sight.  this means that each point of the microwave network must be able to visually see the next node in the network.  That can be difficult due to the terrain in Alaska, however the cost is typically much less than trying to connect via fiber or other types of terrestrial cable.