advanced technique in GSM VS 3G

<font color=#FF0000>When comparing GS</font>M and 3G technologies, 3G allows much higher data rates (bandwidth) to the end user than the GSM. Also, 3G technologies uses packet switched technology for data while GSM uses circuit switched data.
Multiple access method used in GSM is TDMA (Time Division Multiple Access) and FDMA whereas, in 3G it is WCDMA. So in 3G each user spread its signal in entire bandwidth, so that, other users see it as pseudo white noise (WCDMA) whereas, in GSM, each user select separate frequency channel and separate time slot in that channel to communicate. GSM is considered as a 2nd Generation technology while 3G is the 3rd Generation latest technologies standardized by 3GPP.When comparing the architecture, 3G introduced new nodes called Node-B and RNC (Radio Network Controller) to replace the existing BTS (Base Transceiver Station) and BSC (Base Station Controller) respectively. These architectural changes forced most of the mobile operators to invest again (less opportunities to upgrade) in 3G technology on top of the existing GSM network, because of the incompatibility of technologies. Also, mobile devices are evolved to support both technologies simply because of above reason.