  Some properties of multi-qubit systems interacting with noisy environment is
discussed. The amount of the survival entanglement is quantified for the GHZ
and W-states. It is shown that the entanglement decay depends on the noise type
( correlated or non-correlated), number of interacted qubits with the
environment and the initial state which passes through this noisy environment.
In general, the GHZ is more fragile than the W-state. The phenomena of
entanglement sudden death appears only for non-correlated noise.
