Mobile broadband services are undergoing a period of dramatic growth causing a tremendousrnincrease in data tra c. One main reason for this rise of tra c is being driven byrnthe growing number of mobile subscribers. This increment in data tra c is handled byrnnew technologies. LTE-Advanced extends the capabilities originally de ned in LTE tornincrease data throughput by using a combination of new technologies, like OrthogonalrnFrequency Division Multiple Access (OFDMA), Carrier Aggregation (CA) and Multi InputrnMulti Output (MIMO) techniques. CA is one of the most signi cant LTE-Advancedrnfeatures that combine multiple Component Carriers (CCs) across an available spectrumrnto create a wider bandwidth channel for increasing the network data throughput andrnoverall capacity.rnThis thesis analyzes throughput enhancement using CA technique, by conducting radiornpropagation using WinProp and system level simulation using Matlab, for di erent CArnscenarios of a selected high tra c area in Addis Ababa city, Ethiopia. The addition ofrn10 MHz CC over 20 CC provides 49%, and 20 MHz provides 105% throughput gains atrncell center for case of 1800 MHz (band 3). All the three frequency bands (1800 MHz,rn2600 MHz (band 7) and 3700 MHz (band 43)) with two 20 MHz CC provide over 100%rnthroughput gain at the cell center, compare to 1 CC at 1800 MHz. When using lowrnfrequency bands, such as the 1800 MHz band, the Signal to Interference and Noise Ratiorn(SINR) value is low thus providing a better throughput from the cell center to edge.