I will briefly review the impact of primordial gravitational waves into CMB polarization, and present some of the observational efforts in which I am involved.
I will describe the observational target and the most relevant measurement issues due to sensitivity, foreground emission and systematic effects.
In particular I will focus on the LSPE ground+balloon experiment, and on the LiteBIRD satellite.
LSPE is due in the next years, and aims at measure the large scales of the CMB polarization in the northern hemisphere.
LiteBIRD is a satellite devoted to CMB polarization to be launched in late 2020's. It is approved and coordinated by JAXA, with a strong involvement of European institutions (two of the three instruments on board are under European responsibility), and a relevant NASA contribution.