  The reconfigurable intelligent surface (RIS) is one of the promising
technology contributing to the next generation smart radio environment. The
application scenarios include massive connectivity support, signal enhancement,
and security protection. One crucial difficulty of analyzing the RIS-assisted
networks is that the channel performance is sensitive to the change of user
receiving direction. This paper tackles the problem by categorizing the RIS
illuminated space into four categories: perfect alignment, coherent alignment,
random alignment, and destructive alignment. These four categories cover all
the possible phase alignment conditions that a user could experience within the
overall $2$ pi solid angle of RIS-illuminated space. We perform analysis for
each of these categories, deriving analytical expressions for the outage
probability and diversity order. Simulation results are presented to confirm
the effectiveness of the proposed analytical results.
