An upstream transmission scheme of asymmetric clipping optical orthogonal frequency division multiplexing (ACO-OFDM) based WDMA-PON is proposed. Performance of 10Gbit/s/ONU upstream ACO-OFDM signal is analyzed. The scheme is high capacity and power efficient.

We focus the solution space of a most fundamental problem - Minimum Vertex-Cover problem - in theoretical computer science. After some rigorous analysis, we provide the formation mechanism of minimum vertex-cover solutions on the tree and give the organization of these solutions on arbitrary lattice structure. By the results, we can easily calculate the solution numbers on these structures and have better understanding of the hardness of Minimum Vertex-Cover problem. The proposed study and algorithm can make a new way on detecting the essential difficulty of NP-complete problems and designing efficient algorithms on solving them.

Research progress of network survivability during the last few years were briefly introduced, including definitions, methods, qualitative and quantitative survivability evaluation, etc. Technical measures of survivability including IOT were summarized. Cooperative survivability and further possible research problems were investigated. Based on the idea of machine learning, survivability information can be got from other systems, and were utilized by the local system to enhance local survivability in time. Some research aspects on cooperative network survivability were summarized. Peers in a system collaborate with each other, which can improve the survivability of the whole systems.