One of the most important features to migrate from LTE system to LTE-A system is Carrier aggregation. It is used to achieve high data rates of the order of 1Gbps. Furthermore an LTE Advanced user is backward compatible with LTE. Carrier aggregation is a multi carrier technique, where we will be combining unused SCC with the PCC that is allocated to the user equipment. By combining five component carriers, each of 20 Mhz, we can extend the bandwidth to 100 Mhz and hence achieve high data rates. In this paper we will analyze the performance of carrier aggregation and compare it with the conventional LTE system.