On the Impact of Coarse Synchronization on the Performance of Broadcast/Multicast Single Frequency Network Operation in WCDMA

We evaluate the system-level performance and potential capacity gain of MBSFN (Multicast/Broadcast Single Frequency Network) operation in wideband CDMA (WCDMA) and compare it to conventional multimedia broadcast/multicast service (MBMS) provision with macro-diversity combining. MBSFN operation has recently been specified in the 3rd Generation Partnership Project (3GPP) as an enhancement to MBMS. It aims to mitigate the cell-edge problem of multicast/broadcast applications, which are typically dimensioned for a predefined coverage. In WCDMA as considered here, MBSFN operation refers to the use of a single common scrambling code and the same set of spreading codes to simultaneously broadcast bit identical MBMS data in a number of cells that form an MBMS cluster. Since intercell interference is drastically reduced by this concept, it has the potential of considerably increasing the spectral efficiency of MBMS. Nevertheless, coarse synchronization of the transmitting base stations is expected to degrade the performance of MBSFN. We study the system-level performance of MBSFN for WCDMA with imperfect synchronization of the base stations considering different equalization strategies.