This paper starts with a review of 2G-3G CDMA based wireless systems from a network operation perspective. In particular, the challenges faced by current CDMA technologies will be addressed with the focus on their possible applications in 4G wireless networks. We will show that many advanced operational requirements in future 4G networks, such as high-speed bunt traffic, cross-layer network design, seamless integration of different net works with and without infrastructure, will make all current CDMA technologies unsuitable due to their rigid and voice-centric physical layer architecture. To respond to the call for CDMA innovation, a novel OCC-CDMA/OS physical layer architecture is proposed in this paper for its possible applications in futuristic wireless networks. One of the most important features of OCC-CDMA/OS physical layer 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 networks