Channel Estimation and Rake Reception for 3G Air Interface Wideband Coded Division Multiple Access

The existing mobile communication systems operate in selected environments only; it would be desirable to have a new universal system, which could operate anywhere, anytime using unified equipment. Also, taking into account the limitations imposed by the finite amount of radio spectrum available, the focus of third generation (3G) mobile systems is to provide seamless service from the customer perspective such as multimedia, internet and speech with wire line quality. Wideband coded division multiplexing (WCDMA) is one of the four air interfaces defined by International Mobile Telecommunication- 2000 (IMT-2000) and developed by Third Generation Partnership Project (3GPP). WCDMA operates in two modes namely frequency division duplex (FDD) and time division duplex (TDD). The paper discusses the technical specifications, frame structure of common pilot channel (CPICH) and basic idea for spreading and scrambling in WCDMA. The simulation is performed for transmitter and receiver operating in FDD mode for downlink channel generation for CPICH, channel estimation by least mean square algorithm (LMS) and rake reception for predetermined bit pattern.