Performance study of the OFDM modulation for the use in Wireless communication Systems of the 4G

---------------------------------------------------------------------***--------------------------------------------------------------------Abstract Communication is ensured by the links between the base station and the different mobiles. It is provided by allocating a channel to each mobile. A channel typically uses two transmission frequencies: one is used to communicate information from the base station to the mobile and called downlink communication; the other is used to communicate information to the mobile station base and is called uplink. The transmission channel is the central issue that must be addressed in different transmission solutions. When a symbol is sent through the channel, it will be received in the form of delayed and attenuated versions superposed which can lead to interference between the transmitted symbols. One remedy would be to increase the time interval between the symbols but at the expense of throughput desired. To maintain high data rates and cancel the interference between symbols, a more sophisticated solution consists of a parallel transmission of data with sufficiently long periods such as OFDM achieves it “Orthogonal Frequency Division Multiplexing. ''