  Since star network of spins was proposed, generating entanglement directly
through spin interactions between distant parties became much possible. We
propose an architecture which involves coupled spin chains based on
nitrogen-vacancy centers and nitrogen defect spins to expand star network, the
numerical analysis shows that the length of spin chains $M$ and spin noise can
determine the maximally achievable entanglement $E_m$. The entanglement
capability of this configuration under effect of disorder and spin loss is also
studied. Moreover, it is shown that with this kind of architecture, star
network of spins is feasible in measurement of magnetic-field gradient.
