  LiteBIRD is a space-borne experiment dedicated to detecting large-scale
$B$-mode anisotropies in the linear polarization of the Cosmic Microwave
Background (CMB) predicted by the theory of inflation. It is planned to be
launched in the late 2020s to the second Lagrange point (L2) of the Sun-Earth
system. LiteBIRD will map the sky in 15 frequency bands. In comparison to
$\it{Planck}$ HFI, the previous low-temperature bolometer-based satellite for
CMB observations, the number of detector has increased by two orders of
magnitude, up to $\sim$5000 detectors in total. The data rate is 19 Hz from
each detector. The bandpass to the ground is limited to 10 Mbps using the
X-band for a few hours per day. These require the data to be compressed by more
than 50 %. The exact value depends on how much information entropy is contained
in the real data. We have thus evaluated the compression by simulating the
time-ordered data of polarization sensitive bolometers. The foreground
emission, detector noise, cosmic ray glitches, leakage from the CMB intensity
to polarization, etc. are simulated. We investigated several algorithms and
demonstrated that the required compression ratio can be achieved by some of
them. We describe the details of this evaluation and propose algorithms that
can be employed in the on-board digital electronics of LiteBIRD.
