Universal mobile telecommunication system(UMTS) is an interference-limited system since frequency reuse factor is one (FR-1) for all uniquely coded User Equipment(UE). Inter-cell Interference(ICI) has been still a challenging problem for third Generation(3G) mobilesystemswhichlimitstheperformanceofsystemespeciallyforuserlocatedtoedge of cell. For seamless communication, soft handover is very well-known ICI mitigation technique since UE has a number of radio links. So that fast power control along with soft handover are an important inter-cell interference mitigation tool for WCDMA system. The goal of this work is to study the impact of inter cell interference for downlink UMTS-FDD cellular network. The Results of this allows to verify downlink transmission power increase and decrease for current serving and adjacent NodeB respectively. Hence, inter-cell interference are mitigated. On the other hand, Quality of service for all active NodeB in relation to target energy per bit to spectral Interference power, Eb Io are analyzed as a function of path loss for each perspective distance between UE and all generic NodeB. Important parameters to understand this work are Eb Io est , Eb Io tar, SIRtar and SIRest . Eb Io tar, SIRtar aretargetSIR, Eb Io definedformNodeBandRNCrespectively. Besides, the result of this work allows us to compare related mitigation technique for downlink UMTS-FDD performance.