  The Gaussian broadcast channel (GBC) with $K$ transmit antennas and $K$
single-antenna users is considered for the case in which the channel state
information is obtained at the transmitter via a finite-rate feedback link of
capacity $r$ bits per user. The throughput (i.e., the sum-rate normalized by
$K$) of the GBC is analyzed in the limit as $K \to \infty$ with $\frac{r}{K}
\to \bar{r}$. Considering the transmission strategy of zeroforcing dirty paper
coding (ZFDPC), a closed-form expression for the asymptotic throughput is
derived. It is observed that, even under the finite-rate feedback setting,
ZFDPC achieves a significantly higher throughput than zeroforcing beamforming.
Using the asymptotic throughput expression, the problem of obtaining the number
of users to be selected in order to maximize the throughput is solved.
