The common packet channel (CPCH) adopted by 3GPP is used to carry small and medium sized packets, such as SMS (short message service) and web data. We analyze the system performance of the non-real time channel monitoring scheme when the periodic broadcast method is deployed. If user equipment (UE) can continuously monitor the CPCH status, the performance of the channel monitoring scheme is satisfactory. However, in practice, a CPCH status broadcast period exists and, therefore, an UE can request a CPCH channel based on incorrect CPCH status information. This incorrect CPCH status information results in performance degradation in the channel monitoring scheme. We analyze this performance degradation and show the relationship between system performance and the status broadcast period.