TDI developed in increasing sophistication to account for unequal armlengths, differences between the (unequal)
armlengths on given up- and down-links due to aberration, and time-dependences of the unequal, aberrated armlengths. For a
discussion of this development see [116] and references therein. TDI also allows LISA’s laser noises to be canceled in many
ways [17, 51, 118]. In particular, one laser-noise-free combination is insensitive to GWs, but responds to the instrumental
noises; this combination will be used to discriminate a stochastic GW background due to galactic binary stars from
instrumental noises [114, 45]. Because multiple laser-noise-free combinations can be simultaneously constructed, the
optimum sensitivity of the LISA array can be achieved by appropriately linear combinations of the TDI data
streams [92].