One of the most difficult task for any mobile network operator is to efficiently manage anrnincreasing number of mobile data users especially in a congested urban areas. These high numberrnof data users require higher bandwidth and high speed throughput. To overcome these problems,rnhigh capital investments are required which are not economically viable. Mobile network operatorsrnare forced to see another alternative to solve the problem by using mobile data offloadingrntechnologies. Mobile data offloading is one of the technique to efficiently handle the growingrnmobile data traffic by offloading cellular data traffic to other complementary networks. This willrndecrease the burden on mobile network operators and increase the capacity of data network. rnCollected data from ethio telecom shows that there is high number of mobile data traffic usage inrn3G network that creates network congestion. Currently in Ethiopia ethio telecom solves thernproblem by upgrading cellular network to 4G/LTE, using smaller cell/sector method and upgraderncellular network by adding base stations/transmitters and enhance software resources. Since thernnumber of peoples in the urban areas like Addis Ababa are increasing dynamically, it is difficultrntask for ethio telecom to manage rapid growth of mobile data usage using the above techniquesrnonly. Hence offloading cellular network to other complementary network provides ethio telecomrnan advantage to enhance the data network capacity easily. rnThis thesis also proposes Wi-Fi offloading technique as one of the alternative way to solve mobilernnetwork congestion problems in a congested urban areas in Addis Ababa city Addis Ketema area.rnThe thesis also shows how Wi-Fi offloading will improve the capacity of the whole mobilernnetwork using Atoll simulation tools and presents options on the technical integration of Wi-Firnand cellular network. And finally the paper shows the challenges and future works of Wi-Firnoffloading in Ethiopia. The simulation result shows that after offloading a percentage of 3G datarntraffic to Wi-Fi network the required grade of service for both voice and data improved.