In this paper we report a successful experiment of adaptive polarization mode dispersion (PMD) compensation up to second-order in a 40Gb/s optical time-division multiplexed (OTDM) communication system by using two-stage compensator. In the experiment the PMD monitoring technique based on degree of polarization (DOP) was adopted. And the Particle Swarm Optimization (PSO) algorithm was introduced in adaptive PMD compensation, with the desirable features of fast convergence to the global optimum point for compensation without being trapped in local sub-optima and with good robustness to noise. The comparison was made to estimate the performance effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO). The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The ability of tracking changed PMD using PSO algorithm was also investigated. The two-stage PMD compensator is shown to be effective for both first- and second-order PMD, and the compensator is shown to be bit rate independent. The compensation time is within several hundreds of milliseconds. The response time for recovery from a sharp disturbance is about 11ms.
The main purpose of this paper is to propose mobile IP network architecture based on dense wavelength-division multiplexing (DWDM), with GMPLS as a common control plane of the optical layer. A novel probability-based wavelength assignment (PWA) scheme for facilitating handoff in the proposed GMPLS-based mobile IP network is also presented. This paper studies the effects of network mobility and handoff path rerouting on the wavelength assignment scheme in a GMPLS-based mobile IP network. In order to support the same quality of service (QoS) for mobile services when handoff occurs, it is preferable to use the same wavelength in the newly established partial label switched path (LSP). In the proposed PWA scheme, when a mobile router (MR) begins to establish a new connection with the correspondent node, a wavelength is assigned based on the vacant probability of every wavelength in the new partial LSP after handoff. We use M/M/1(0) queue to model the dynamic traffic in a GMPLS-based mobile IP network and derive the close-form expression of wavelength vacant probability.
The main purpose of this paper is to propose a novel bandwidth allocation scheme for facilitating quality of service (QoS) routing in mobile ad hoc networks (MANETs). In a MANET using time division multiple access (TDMA), each node communicates with its neighbors in the same time slot. In general, finding a route with the maximum end-to-end bandwidth subject to the constraint of collision-free transmission is an NP-complete problem. This paper proposed a sub-optimal solution to this problem. The solution is based on a centrally controlled bandwidth allocation scheme to properly assign the available time slots to each intermediate link. The advantage of our proposed scheme is that the resource utilization of MANET is maximized and the end-to-end QoS is guaranteed during the route establishment period. Performance analyses show that when using the proposed scheme with AODV to perform QoS routing, it achieves about 25% throughput higher than its best-effort counterpart if the node is moving at 5mps speed.