Passive optical network for CDMA-based wireless communication systems

We review the various passive optical networks (PONs) for CDMA-based wireless communication systems. The relaxed dynamic range requirements of CDMA signals allowed us to implement these networks by using various network architectures including double star, bus, and ring. We first review the performance of the PON based on double-star architecture. This network provides optical fiber gain, needs only one optical source for downstream signals, and relaxes the frequency requirement of optical and electrical components. In addition, this network could be implemented by using low-cost LEDs instead of wavelength-selected DFB lasers for upstream signals. We have also demonstrated a bidirectional PON to enhance the cost-effectiveness of the proposed network. There was no significant difference in the performance between unidirectional and bidirectional PONs. This was because the upstream performance of these networks was mainly limited by the OBI noise, while the increased link loss in the bidirectional PON had only minor effect. However, the networks based on the double-star architecture, are vulnerable to fiber failures. We show that the proposed network can also be implemented with ring architecture for self-healing capability. This network could be restored from a fiber or equipment failure within 50 μs when the circumference of the ring was 9.3 km. Both the networks (using double star and ring architectures) could accommodate about 8 remote base stations