Compatible Port Connections

Note carefully that to connect a wave digital element to port $i$ of the adaptor, we route the signal $f^{{-}}(n)$ coming out of the element to become $f^{{+}}_i(n)$ on the adaptor port, and the signal $f^{{-}}_i(n)$ coming out of port $i$ of the adaptor goes into the element as $f^{{+}}(n)$ . Such a connection is said to be a compatible port connection. In other words, the connections must be made such that the arrows go in the same direction in the wave flow diagram.