Li Suoping

Full-vector improved effective index method for analysis of fiber Bragg gratings formed in photonic crystal fibers

The reflectivity and the Bragg wavelength of a fiber Bragg grating formed in a photonic crystal fiber with central pure core defect and a regular hexagonal array of microscopical holes cladding were investigated by the full vector improved effective index method, the calculated results indicate that the effective index of the FSFM decreases with increasing the filling factor, the reflectivity increases with the filling factor increasing, the Bragg wavelength decreases from 1544.133 nm to 1540.509 nm with the filling factor increasing.

Study on dispersion of optical fiber with cladding made of uniaxial crystal materials

The dispersion of the fiber with cladding made of uniaxial anisotropic crystal material with optical axis running along its length was investigated by means of numeric solution. The calculated results indicate that the parameter Kd has a strong impact on the dispersion and the zero dispersion wavelength of this kind of fiber, and the zero dispersion wavelength decreases with Kd increasing These studies provide an important basis for designing different zero dispersion fiber and for electric field or strain sensing.

A AQM Model with Multi-Priority and Multi-Receiver for Mobile Ad Hoc Networks

AQM (Active Queue Management) is an effective scheme to enhance congestion control. Most of the mobile networks today use queue management to manage and improve network performance. In this paper, we deploy AQM mechanism in Mobile Ad Hoc networks to manage the packets queue in the network nodes. By modeling a node with multi-receiver in Ad Hoc networks, we develop an analytical model for a multi-server and finite capacity queuing system with AQM mechanisms under multi-classes of traffic. We consider multiple classes of traffic modeled by Poisson arrival and exponentially service processes. It deduced the performance metrics including the average queue length, system throughput, probability of drop packet and the average waiting time. Then, it illustrated the relationship between above metrics and the number of servers. Finally, by demonstrating the effective number of servers, it illuminate that we should deploy appropriate number of servers for a certain condition.

Study on Subcarrier and Power Allocation Algorithm for Downlink Transmission in Multiuser OFDM System

In this paper, we consider the problem of resource allocation (in terms of subcarrier, bit and corresponding power) for downlink transmission in multiuser OFDM system. An improved subcarrier and power allocation algorithm is proposed, which uses two steps to allocate recourses dynamically. Given the system?s total power and BER, this algorithm tends to maximize the bit rate to make effective use of the resources. By using the greedy algorithm, this algorithm can get the maximum bit rate and reduce the power dissipation properly. The simulation result shows that this algorithm is better than the static allocation algorithm and has similar performance compared with the joint allocation algorithm, at the same time it has lower power dissipation.