Research On Iterative Interference Cancellation And Implementation Of Physical Layer In Forward Link Of EV-DO

Multi-Code technique is widely used in the third generation mobile communication systems,and flexibly provides high-rate packet data services for users. The basic idea of Multi-Code technique is to assign multiple coded channels to any given user by orthogonal codes. The received multi-code signals maintain orthogonal to each other in single-path environments. However, in multi-path environments, these intra-user multi-code signals from different delay paths are no longer orthogonal to each other, the cross-correlation between different delay paths results in Multi-Code Interference (MCI). MCI degrades the system performance.At the first part of this thesis, a signal model of Multi-User Detection (MUD) and non-linear detection algorithms are described. Base on a common multi-code transmission system and receiving system with Iterative Interference Cancellation (IIC), we investigate the signal models of symbol-level IIC and chip-level IIC in forward link receiving system of EV-DO, deducing the algorithms of symbol-level IIC and chip-level IIC. Then we study the basic performances of EV-DO forward link receiving system with symbol-level IIC and chip-level IIC. The simulation results show that IIC is comparatively a good solution to the problem of high-rate data transmission in forward link of EV-DO system. Focusing on the complexity of IIC algorithms, we propose different methods to reduce them. The Iterative time and bit-width's impacts on the performances of EV-DO system are also investigated.The forward link transmission system of EV-DO is described in chapter five. Then we exhibit the design of the channel estimation of basic receiving system detailedly. The performances of basic forward link receiving system are presented at the end of chapter five.