We consider the downlink of a multiuser multi-input multi-output (MIMO) broadcast channel under a single cell structure. To study the achievable link coverage performance of zero-forcing beamforming (ZFB) and zero-forcing dirty-paper coding (ZF-DPC) when the channel state information (CSI) is available to the transmitter. First we develop analytical closed-form expressions for the link outage probability and coverage reliability of baseline ZFB and ZF-DPC when no multiuser scheduling involved. We find that the coverage performance of ZFB can only approach to that of the weakest link of ZF-DPC under predetermined required SNR and outage probability. Secondly, for exploring the achievable cell coverage, we discuss the strongest link performance of both broadcast beam-forming schemes under multiuser scheduling. Under a framework of analysis for ZF-DPC and simulation for ZFB, we show that a soft coverage enhancement can be easily done by using scheduling techniques without extra hardware power consumption.