With the increase of the Internet service, it is more and more important to provide better performance and quality in the WDM network. The paper introduces a novel dynamic routing (DR) algorithm based on OSPF with the balance parameter. Due to the limitation to the wavelength continuity, the problem of the routing and wavelength assignment (RWA) is also analyzed comprehensively. In designing the algorithm, RWA is considered, too. The protocol of OSPF may collect the network state information by flooding in WDM network. Furthermore, the algorithm can adapt to the traffic changes with rather little changes in transport performance and blocking probability. In order to prove the method efficient and robust, the simulation with two topologies is done and results are also analyzed and compared. At last, the conclusion and further work are given, too.
This paper considers the problem of Routing and Wavelength Assignment(RWA) in a reconfigurable optical network using wavelength division multiplexing (WDM). The RWA problem consists of two basic sub-problems, namely, routing problem and wavelength assignment problem. We couple the two sub-problems: the paths are decided by the state of the wavelength assignment. This is usually called dynamic (or adaptive) RWA. As Traditional static RWA algorithms only consider to have lower blocking probability, for high priority class light-path, they ignore to optimize the performance of low priority class light-path and result in higher blocking probability for low priority class light-path request. So the average of blocking probability is increased in all-optic networks. In fact, the most efficient service of optic network is for low priority class light-path request. In order to improve the performance of optic network, we must optimize low priority class light-path request. Our method is based on quality of service (QoS), using a layered-graph model and setting a threshold to assign the wavelength dynamically, this threshold decides whether to assign intensively the preferred wavelength in higher priority class wavelength. The value is tuned adaptively by nodes in all optic-networks with the usage of wavelength. Then the nodes select the routing dynamically according to the wavelength assigned. By using our method, the blocking rate of the high priority request is guaranteed to the lower degree, and at the same time performance of the low priority request is improved. So the network’s average blocking rate is minimized. Simulation results of the network performance showed that the proposed method performs well in different dynamic traffic situation.
Position information of individual node is useful in implementing functions such as routing and querying in ad-hoc networks. But adding GPS receivers or other sophisticated sensors to every node can be expensive. In this paper, we present the distributed, hop by hop positioning algorithm for solving the problem of positioning nodes within an ad hoc, wireless network of low powered sensor nodes, low mobility and large size without the aid of GPS aid. It works as an extension of both DV-hop propagation and GPS positioning in order to provide absolute position estimate for all nodes in a network where only a limited fraction of nodes have self location capability we call <i>anchors</i>. The procedure is partitioned into three phases: global location, local refinement and Kalman filter optimization, each phase is described in detail. The simulation environment used to evaluate this algorithm is also explained, including details about the specific implementation of each phase and experimental results, which demonstrate that the algorithm is more robust to measurement error than previous proposals, and it needs much fewer anchor nodes than previous algorithms to get comparable results.
This paper studies the QoS of VPN in an environment where the public network prices connection-oriented services based on source, destination and grade of service, and advertises these prices to its VPN customers (users). As different QoS technologies can produce different QoS, there are according different traffic classification rules and priority rules. The internet service provider (ISP) may need to build complex mechanisms separately for each node. In order to reduce the burden of network configuration, we need to design policy control technologies. We considers mainly directory server, policy server, policy manager and policy enforcers. Policy decision point (PDP) decide its control according to policy rules. In network, policy enforce point (PEP) decide its network controlled unit. For InterServ and DiffServ, we will adopt different policy control methods as following: (1) In InterServ, traffic uses resource reservation protocol (RSVP) to guarantee the network resource. (2) In DiffServ, policy server controls the DiffServ code points and per hop behavior (PHB), its PDP distributes information to each network node. Policy server will function as following: information searching; decision mechanism; decision delivering; auto-configuration. In order to prove the effectiveness of QoS policy control, we make the corrective simulation.
Proc. SPIE. 5282, Network Architectures, Management, and Applications
KEYWORDS: Surface plasmons, Networks, Passive optical networks, Control systems, Telecommunications, Optical networks, Local area networks, Error control coding, Broadband telecommunications, Asynchronous transfer mode
Combining asynchronous transfer mode (ATM) over a passive optical network (APON) can provide broadband services as defined by the international telecommunications union (ITU). The medium access control (MAC) layer is of primary importance to the access scheme as in controls the flow of traffic in the access network. This paper presents a novel MAC protocol-segmented proportional spacing MAC protocol, which complies with ITU-T recommendations, is firstly designed for APON system based on the analysis of different type of bandwidth allocation algorithms. The main idea of protocol is: frame structure adopts the structure regulated by ITU; fine time division for the optical network unit (ONU) to apply bandwidth; the bandwidth’s application is not based on the T-interface but ONU, the bandwidth allocation algorithm uses segmented proportional spacing algorithm. At last, we compare our protocol to other MAC protocols, the results show that proportional spacing and segmented bandwidth allocation control the cell jitter with satisfactory and improve the system bandwidth efficiency at same time, the correlative conclusions are given finally.
In this paper, we propose content-based video retrieval, which is a kind of retrieval by its semantical contents. Because video data is composed of multimodal information streams such as video, auditory and textual streams, we describe a strategy of using multimodal analysis for automatic parsing sports video. The paper first defines the basic structure of sports video database system, and then introduces a new approach that integrates visual stream analysis, speech recognition, speech signal processing and text extraction to realize video retrieval. The experimental results for TV sports video of football games indicate that the multimodal analysis is effective for video retrieval by quickly browsing tree-like video clips or inputting keywords within predefined domain.