Code assignment for IMT-2000 on forward radio link

High-speed multimedia data transmission is a sign significant feature in the third-generation mobile communication systems. Wideband CDMA is widely studied and accepted as the transmission scheme over the air. The single-code and multi-code transmission schemes over the CDMA were also investigated by many researchers. OVSF codes were proposed by the 3GPP as the forward channelization codes to the IMT-2000, the property the OVSF code tree and the code manipulations are important in achieving the high spectral efficiency, which is also the key issue of resource management. This paper proposed an efficient and fast channelization code assignment scheme (FEX scheme), by utilizing the code exchange and garbage collection technique, to reduce the blocking rate of the system. The simulations demonstrated the effectiveness of this scheme by comparing to an "ideal system". The results also revealed the importance of the code exchange and multi-code property to greatly reduce the blocking rate of the system