  Individual subpulses of pulsars are regarded as the basic emission
components, providing invaluable information to understand the radio emission
process in the pulsar magnetosphere. Nevertheless, subpulses are overlapped
with each other along the rotation phase for most pulsars, making it difficult
to study the statistical properties of subpulses. Among the pulsars observed by
the Five-hundred-meter Aperture Spherical radio Telescope, PSR B1916+14 has a
large number of isolated well-resolved subpulses in the high time resolution
observations, having a typical width of 0.15 ms and a high linear polarization.
We find that the number distribution of subpulses contributes dominantly to the
mean profile. According to the emission geometry, these emission units come
from a region roughly 155 km above the polar cap in the pulsar magnetosphere,
and the length scale of basic emission units is approximately 120 m. The
deviations of polarization position angles for these single subpulses from the
standard S-shaped curve are closely related to their fractional linear and
circular polarization, and the large deviations tend to come from drifting
subpulses.
