reported [@senthilkumar06; @senthilkumar08]. However, these investigations are carried out so far only in a system of two coupled time-delay systems. Very recently, the occurrence of global phase synchronization in a linear array of Mackey-Glass time-delay systems in the chaotic regime has been reported in Suresh [*[et al.,]{}*]{} \[2010\] for open end boundary conditions. It has been shown that global phase synchronization occurs via a sequential type synchronization as the coupling strength increases. To verify the generic nature of the results of Suresh [*[et al.,]{}*]{} \[2010\], we consider in this paper two different piecewise linear time-delay systems with complex topological structures and investigate the occurrence of global phase synchronization along with the underlying mechanism for open end boundary conditions. In addition we consider the case of closed end boundary conditions (ring topology) and identify the occurrence of partial phase synchronization via cluster formation.

Specifically, in the first part of this paper, we investigate the generic nature of the phenomenon of global phase synchronization in an linear array, with free ends, of unidirectionally coupled (i) piecewise linear and (ii) threshold nonlinear time-delay systems in hyperchaotic regimes. In the second part, we report the phenomena of partial phase synchronizations in the array of 