  We consider the extra degree of freedom offered by the rotation of the
reconfigurable intelligent surface (RIS) plane and investigate its potential in
improving the performance of RIS-assisted wireless communication systems. By
considering radiation pattern modeling at all involved nodes, we first derive
the composite channel gain and present a closed-form upper bound for the system
ergodic capacity over cascade Rician fading channels. Then, we reconstruct the
composite channel gain by taking the rotations at the RIS plane, transmit
antenna, and receive antenna into account, and extract the optimal rotation
angles after investigating their impacts on the capacity. Moreover, we present
a location-dependent expression of the ergodic capacity and investigate the RIS
deployment strategy, i.e. the joint rotation adjustment and location selection.
Finally, simulation results verify the accuracy of the theoretical analyses and
deployment strategy. Although the RIS location has a big impact on the
performance, our results showcase that the RIS rotation plays a more important
role. In other words, we can obtain a considerable improvement by properly
rotating the RIS rather than moving it over a wide area. For instance, we can
achieve more than 200\% performance improvement through rotating the RIS by
42.14$^{\circ}$, while an 150\% improvement is obtained by shifting the RIS
over 400 meters.
