System Level Performance of Multimedia Broadcast Multicast Service (MBMS) with Macro Diversity

The aim of this paper is to evaluate the system level performance of multimedia broadcast multicast service (MBMS) in WCDMA networks. To enhance coverage and data rates of MBMS users, two macro diversity concepts were introduced in 3GPP release 6: soft and selective combining. Prior work on the evaluation of MBMS with macro diversity schemes has been restricted to link level studies or to very limited scenarios in system level studies. This paper examines the concepts in more detail with dynamic system level tool in which e.g. mobility of users and interactions of the radio resource management functionalities are explicitly taken into account. The evaluation of combining set size and data rates with different thresholds and delays in the combining procedures are especially emphasized. Considering point-to-multipoint (p-t-m) mode of MBMS, the studies indicated clear performance improvements to be gained with macro diversity. In addition, the impact of delays in combining set update procedures was observed to be rather small.