I have implemented a stripping algorithm to extract forward volatilities from cap/floor flat volatilities for different currencies. I am however struggling a bit when implementing a method to convert the first 2 year 3M flat vols into 6M flat vols for the EUR currency.
The information I have available is the forecast curves (1M, 3M, 6M) and discount curve.
I have found some papers detailing a solution that involves the calculation of the correlation coefficient between different 3M forward rates, but that is unfortunately information that is not available to me. I have also found a paper from Bloomberg ("Bloomberg Volatility Cube" by Zhang and Wu) with some standard formulas to do the conversion, but they do not take into account the basis spread, which to me it seems key in doing the conversion.
Any help or guidance from professional practitioners would be very helpful.
Thanks in advance!