  We propose a scheme that can realize a class of positive-operator-valued
measures (POVMs) by performing a sequence of projective measurements on the
original system, in the sense that for an arbitrary input state the probability
distribution of the measurement outcomes is faithfully reproduced. A necessary
and sufficient condition for a POVM to be realizable in this way is also
derived. In contrast to the canonical approach provided by Neumark's theorem,
our method has the advantage of requiring no auxiliary system. Moreover, an
arbitrary POVM can be realized by utilizing our protocol on an extended space
which is formed by adding only a single extra dimension.
