The primary source/clearinghouse for all things UBI seems to be BIEN, and the definition provides for all people, not just people in a nation.
A simple global structure to provide a basic income would provide market driven motivation to provide not only basic needs, but enfranchisement in the global economy.
Distributing the interest on sovereign debt to each adult on the planet would provide a basic income, by simply allowing Commons shares to be claimed for deposit in trust at local banks.
Requiring sovereign debt to be backed with Commons shares is the only change required. This would require the reinvestment of the money currently backing sovereign debt.
Current sovereign debt would pay each adult human about $10 USD/month. This would create the structure, and a trial for basic income, that has the validity of inclusion, while avoiding problems associated with migration, and relative inflations of currencies.
Funding the structure at this level would not increase taxes, as the debt payments are currently being made. Many states paying higher than 1.25% interest on sovereign debt, would have reduced tax liability.
With the structure in place, as revenue increases due to the reinvestment of a couple hundred trillion dollars, and the increase in spending on basic needs, states may increase their debt, for investment in infrastructure, or cash reserves, to increase the basic income.
Then we can let the level of basic income evolve with market pressures.