This paper begins with a review of CDMA based 2-3G systems from a network perspective. In particular, the challenges faced by current CDMA technologies are addressed. We will show that many advanced operational requirements in future 4G networks, such as highspeed burst traffic, cross layer network design, seamless integration of different networks with and without infrastructure, will make the current CDMA technologies unsuitable due to their rigid and voice-centric physical (PHY) layer architecture. To respond to the call for CDMA innovation, a new physical layer architecture, namely Orthogonal Complementary Coded CDMA with Offset Stacking (OCC-CDMA/OS) spreading scheme, is proposed in this paper for its possible applications in futuristic wireless networks. One of the most important features of OCC-CDMA/OS PHY architecture is its unique elasticity, which facilitates implementation of a fully-adaptive CDMA transceiver to work harmonically with various advanced upper-layer designs in 4G networks. Many other technical issues on CDMA based 4G networks will also be discussed. It is concluded that OCC-CDMA/OS has a great potential for its applications in future 4G wireless.