  Reconfigurable intelligent surface (RIS) technique stands as a promising
signal enhancement or signal cancellation technique for next generation
networks. We design a novel passive beamforming weight at RISs in a
multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA)
network for simultaneously serving paired users, where a signal cancellation
based (SCB) design is employed. In order to implement the proposed SCB design,
we first evaluate the minimal required number of RISs in both the diffuse
scattering and anomalous reflector scenarios. Then, new channel statistics are
derived for characterizing the effective channel gains. In order to evaluate
the network's performance, we derive the closed-form expressions both for the
outage probability (OP) and for the ergodic rate (ER). The diversity orders as
well as the high-signal-to-noise (SNR) slopes are derived for engineering
insights. The network's performance of a finite resolution design has been
evaluated. Our analytical results demonstrate that: i) the inter-cluster
interference can be eliminated with the aid of large number of RIS elements;
ii) the line-of-sight of the BS-RIS and RIS-user links are required for the
diffuse scattering scenario, whereas the LoS links are not compulsory for the
anomalous reflector scenario.
