Xijun Zhang

As wavelength division multiplexing (WDM) technology matures and multicast applications become increasingly popular, supporting multicast at the WDM layer becomes an important and yet challenging topic. In this paper, we study constrained multicast routing in WDM networks with sparse light splitting, i.e., where some switches are incapable of splitting light (of copying data in the optical domain) due to evolutional and/or economical reasons. Specifically, we propose four WDM multicast routing algorithms, namely, re-route-to-source, re-route-to-any, member-first, and member-only. Given the network topology, multicast membership information, and light splitting capability of the switches, these algorithms construct a source-based multicast "light-forest" (consisting one or more multicast trees) for each multicast session. While the first two algorithms can build on a multicast tree constructed by IP (which does not take into consideration the splitting capability of the WDM switches), the last two algorithms attempt to address the joint problem of optimal multicast routing and sparse splitting in WDM networks. The performance of these algorithms are compared in terms of the average number of wavelengths used per forest (or multicast session), average number of branches involved (bandwidth) per forest as well as average number of hops encountered (delay) from a multicast source to a multicast member. The results obtained from this research should present new and exciting opportunities for further theoretical as well as experimental work.

According to the time series characteristics of the trajectory history data, we predicted and analyzed the traffic flow. This paper proposed a LSTMXGBoost model based urban road short-term traffic flow prediction in order to... | Find, read and cite all the research you need on Tech Science Press

In this paper, a new electrostatic discharge (ESD) testing system is designed and the influence of the approach speed and charge voltage on ESD parameters, e.g., discharge current, rise time, and induced voltage in a semicircular loop antenna, and also the reproducibility of experimental results are analyzed. It is concluded that, as the charge voltage is constant, ESD parameters are linearly proportional to the approach speed, the reproducibility increases with growth of the approach speed, especially at 0.8 m/s. As the approach speed is constant, the field strength generated at low charge voltage is stronger than that at high charge voltage; better reproducibility can be also reached at low charge voltage. These important conclusions provide the foundation for developing standard method for air ESD immunity tests.

Scheduling all-to-al connections in a network of limited physical connectivity provides a way to trade bandwidth for reduced routing control as well as deterministic connection latency. In this paper, we consider the problem of scheduling all-to-all connections in a WDM ring. For a given number of wavelengths, K, and a given number of transmitter/receiver pairs per node, T, we determine the theoretical lower bound (TLB) on the scheduling length. A basic scheduling strategy called complementary assembly with dual strides (CADS) is proposed. In a special case when K equals 1 and T equals 1, the TLB can be achieved based on CADS. Heuristic algorithms based on either homogeneous or heterogeneous CADS are then proposed for the case when K > 1, and near minimum scheduling length can be achieved for any T. Our analysis also indicate that there is an optimal value of T for a given K such that neither T nor K would become the performance bottleneck. Impact of wavelength-tuning delay, ring propagation delay, laser array fabrication especially wavelength drift of the WDM sources on the scheduling method is also discussed.