Coordination Games on Weighted Directed Graphs

We study strategic games on weighted directed graphs, where each player’s payoff is defined as the sum of the weights on the edges from players who chose the same strategy, augmented by a fixed nonnegative integer bonus for picking a given strategy. These games capture the idea of coordination in the absence of globally common strategies. We identify natural classes of graphs for which finite improvement or coalition-improvement paths of polynomial length always exist, and consequently a (pure) Nash equilibrium or a strong equilibrium can be found in polynomial time. The considered classes of graphs are typical in network topologies: simple cycles correspond to the token ring local area networks, whereas open chains of simple cycles correspond to multiple independent rings topology from the recommendation G.8032v2 on Ethernet ring protection switching. For simple cycles, these results are optimal in the sense that without the imposed conditions on the weights and bonuses, a Nash equilibrium may not even exist. Finally, we prove that determining the existence of a Nash equilibrium or of a strong equilibrium is NP-complete already for unweighted graphs, with no bonuses assumed. This implies that the same problems for polymatrix games are strongly NP-hard.

SURVIVABILITY IN METRO RING NETWORK USING OXADM

The optical cross add and drop multiplexing (OXADM) node described in this paper increases the capacity, flexibility and reliability of the trunk-line optical network used for data communication. It features two different bandwidths which operate in working and protection line in a ring configuration. The OXADM has the same features of the conventional OADM node but with more efficiency and reliability. The OXADM prototype system focuses on providing survivability through restoration against failures, such as cable/fiber cut in optical layer with ring topology. Two types of restoration scheme have been proposed to ensure data flow continuously by means of linear/ multiplex protection and ring protection. Comparison between OXADM and OADM restoration schemes is also described. The BER characteristics were measured at 2.5 Gbps (OC-48) and small degradation was observed, as confirmed by a comparison of these simulation results with those obtained from systems without restoration element. Restoration schemes in OXADM node are more reliable and efficient compare to conventional device due to internally routing mechanisms and no ‘drop and re-add function’ is needed to route the signal to alternative path or processed the signals in both electronic and optical domain as practice in conventional nodes today.

An oligothiophene chromophore with a macrocyclic side chain: synthesis, morphology, charge transport, and photovoltaic performance

Molecular chromophores tend to form crystals beyond nanometer sizes upon thermal aging. A novel ring-protection structure has shown promise to solve morphological stability problem of solution-processed small molecule solar cell devices.

Research of Ethernet Ring Protection Technology

Ethernet ring networks are used widely recently, and the research on the ring protection switching is carried out. Spanning Tree Protocol (STP) was the first technology to control ring networks to avoid the storm. Rapid Spanning Tree Protocol (RSTP) is an upgraded version of STP[1]. RSTP can provide shorter convergence time than STP. Ethernet Automatic Protection switching (EAPS) is designed for a single ring topology [2]. The convergence time of EAPS is below 50ms and EAPS can meet the real-time requirements and high-reliability requirements of network services.G.8032 is a standardized scheme for achieving sub-50ms service protection in ring topologies which is recommended by ITU-T[3]. This paper intelligent Ethernet ring protection technologes about Spanning Tree Protocol, RFC3619 and G.8032 .These technologies appear in different times, and have their advantages and disadvantages. This article outlines these Ethernet ring protection switching technology and explains their basal principles.