  This paper aims to achieve scalable exact output and regulated output
synchronization for discrete-time multi-agent systems in presence of
disturbances and measurement noise with known frequencies. Both homogeneous and
heterogeneous multi-agent systems are considered, with parts of agents' states
accessible in the latter case. The key contribution of this paper is on the
distributed protocol that only uses the information of agent models, rather
than the communication network information and the agent number, so as to
achieve the scalable exact synchronization under disturbances and measurement
noise. The validity of the protocol is verified by numerical simulations with
arbitrarily chosen number of agents.
