An Enhanced OFDM-DS-CDMA Network under High-Speed Mobile Environment

High speed data rates are desired by high speed moving users. The combination techniques of orthogonal Frequency Division Multiplexing (OFDM) and CDMA are proposed to meet this need and improve the frequency spectral efficiency. In this paper, an OFDM-DS-CDMA network of frequency and spreading code reuse is proposed over frequency-selective time-varying channel. It gives a flexible multi-access method and makes an easy way from network design to engineering and optimization. In order to cancel strong adjacent cell interference (ACI) and intra cell interference, a scheme of extended joint detection is adopted in the uplink. When the user located in the edge of the cell under high speed moving, channel impulse response changes rapidly. Doppler spread can not be ignored because of the inter-carrier interference (ICI). A scheme of Doppler diversity receiving is used in the uplink before extended multi-user joint detection.