  The cross-section for the process e+e- -> W+W- has been measured with the
data sample collected by DELPHI at an average centre-of-mass energy of 189 GeV
and corresponding to an integrated luminosity of 155 pb^{-1}. Based on the 2392
events selected as WW candidates, the cross-section for the doubly resonant
process e+e- -> W+W- has been measured to be 15.83 +- 0.38 (stat) +- 0.20
(syst) pb. The branching fractions of the W decay were also measured and found
to be in good agreement with the Standard Model expectation. From these a value
of the CKM mixing matrix element |V_{cs}| = 1.001 +- 0.040 (stat) +- 0.020
(syst) was derived.
