Wang Rong Chang

An Integrated WiMAX/WiFi Architecture with QoS Consistency over Broadband Wireless Networks

WiMAX and WiFi have emerged as promising broadband access solutions for the latest generation of wireless MANs and LANs, respectively. Their complementary features enable the use of WiMAX as a backhaul service to connect multiple dispersed WiFi hotspots to the Internet. This study proposes an integrated architecture utilizing a novel WiMAX/WiFi Access Point (W2-AP) device to effectively combine the WiMAX and WiFi technologies. In the proposed architecture, the protocol operation of the WiFi hotspots is the same as that of the WiMAX system. As a result, the WiFi network can support connection-oriented transmissions and QoS in a similar fashion to the WiMAX system, and thus a considerable improvement in the delay performance is obtained. The numerical results obtained using a Qualnet simulator confirm both the effectiveness and the efficiency of the proposed architecture.

FARE: An efficient integrated MAC protocol for differentiated services in WDM metro rings

This study investigates the fairness control, collision avoidance and QoS support issues of a particular WDM dual-ring network known as FT^2-TR^2. This system is an extended version of the original uni-directional FT-TR ring architecture, in which every node is equipped with a fixed-tuned transmitter and a tunable receiver on each ring. This study proposes a novel FAirness and REservation integrated protocol, designated FARE, which incorporates three mechanisms designed specifically to resolve the receiver collision problem, to achieve fairness among all of the network nodes, and to meet the tight delay requirements of multimedia applications. Simulation results are presented to demonstrate that FARE provides a high performance for real-time traffic while simultaneously providing significant performance improvements for best-effort traffic.

Design and Analysis of a WDM EPON for Supporting Private Networking and Differentiated Services

Although EPONs have been proposed as a means of overcoming the bandwidth bottleneck problem in local access networks, they may not be able to meet the ever-growing bandwidth demand from users in the near future. Accordingly, this study presents what we believe to be a novel wavelength-division-multiplexing (WDM) Ethernet passive optical network (EPON) system based on an arrayed-waveguide-grating (AWG) module to meet the rapidly increasing bandwidth demand anticipated in the future. The use of the AWG enables the proposed WDM EPON architecture to achieve wavelength spatial reuse and to provide an intercommunication capability between optical network units (ONUs). As a result, the architecture not only allows upstream access to the central office, but also facilitates a truly shared LAN capability among the end users. Furthermore, the proposed WDM EPON scheme takes account of the requirement for backward compatibility with the IEEE 802.3ah multipoint control protocol and incorporates a dynamic bandwidth allocation scheme and a quality-of-service provisioning mechanism to arbitrate the access of the individual ONUs over the WDM layer. An analytical framework is developed for evaluating the mean packet delay and mean queue length of the proposed WDM EPON system. The analytical results derived using this framework are found to be in good agreement with those obtained from computer simulations.

SPON: A slotted long-reach PON architecture for supporting internetworking capability

Long-reach optical access technologies have emerged as a promising solution for combining access and metro backhaul networks in a cost-effective manner. This study develops a Slotted PON (SPON) architecture based upon an AWG for long-reach optical access networks. The AWG enables the SPON to achieve wavelength spatial-reuse and to provide an internetworking capability amongst ONUs located within different local access networks. In addition, a Slotted MAC (SMAC) protocol is proposed to arbitrate the access of the individual ONUs over the DWDM layer. The simulation results show that the SPON architecture integrated with SMAC protocol enhances the bandwidth utilization within the network, and therefore achieve a significant reduction in the average packet delay.

CORNet: An OBS metro ring network with QoS support and fairness control

The rapid evolution of networks has been driven by new advances in enabling technologies and the explosive growth of Internet traffic. Optical Burst Switching (OBS) is not only cost-effective, but also provides high throughput, high bandwidth utilization, and low transmission latency. These benefits make OBS a viable solution for next-generation Metro Area Networks (MANs) in which the traffic models will be changed more dramatically than in todays networks. This paper employs Wavelength Division Multiplexing (WDM) technology to construct a loss-free OBS metro ring architecture designated as the Collision-free Optic-burst Ring Network (CORNet). The proposed architecture ensures a collision-free transmission of data bursts, while retaining the advantage of the statistical multiplexing provided by conventional OBS networks. A novel distributed Medium Access Control (MAC) protocol to integrate the support of differentiated service and fairness access in CORNet is presented. The proposed Quality of Service (QoS) provisioning mechanism adopts a bandwidth-reservation approach which combines real-time transmission establishment and termination routines. Furthermore, a credit-based fairness control scheme is designed to guarantee the transmission fairness of best-effort traffic. Simulation results are presented to demonstrate that the proposed CORNet system provides good performance for real-time traffic while simultaneously providing significant performance improvements for best-effort traffic.

Design and performance evaluation of aquatic-pollution monitoring scheme over a Waterborne Wireless Sensor Network

Spillages of pollutants such as oil or biochemical materials at sea have the potential to damage not only the offshore environments, but also the regional economy. Accordingly, this study develops an aquatic-pollution detection and tracking scheme, designated as AquaView, based on a Wireless Sensor Network deployed over an offshore region (i.e., a Waterborne Wireless Sensor Network (WWSN)) to track the moving boundary of a pollution spill such that cleanup operation can be effectively monitored and controlled. In evaluating the boundary tracking performance of AquaView, a 3D Floating Mobility Model (3D FMM) is used to simulate the movement of the sensor nodes floating on the ocean surface. The numerical results confirm that the 3D FMM model accurately reproduces the statistical features of the ocean current, wind and surface wave effects on the 3D trajectories of the sensor nodes. Moreover, it is shown that AquaView achieves a significantly improvement in a satisfactory boundary estimation performance and a low communication cost.

FIPACT: A Frame-Oriented Dynamic Bandwidth Allocation Scheme for Triple-Play Services over EPONs

Ethernet Passive Optical Networks (EPONs) are not only cost-effective, but also provide high throughput, high bandwidth utilization, and low transmission latency. As a result, EPONs are a viable solution for overcoming the bandwidth bottleneck problem in local access networks. This study develops a novel Dynamic Bandwidth Allocation (DBA) scheme, designated as Frame-oriented Interleaved Polling with Adaptive Cycle Time (FIPACT), to provide a differentiated Quality-of-Service (QoS) capability in EPONs. FIPACT adopts a framed approach, in which the upstream network bandwidth is partitioned into successive frames. Within each frame, each Optical Network Unit (ONU) is guaranteed the network resources necessary to transmit a specific quota of Voice over Internet Protocol (VoIP), video, and Internet access traffic, respectively. Since FIPACT permits these three types of traffic stream to share the available bandwidth efficiently whilst still satisfying their respective QoS requirements, it provides an effective means of achieving differentiated triple-play services in EPONs. The simulation results demonstrate the effectiveness and efficiency of the proposed approach.

A Game-Theoretic Framework for Intra-ONU Scheduling in Integrated EPON/WiMAX Networks

An integrated EPON/WiMAX network has been an attractive attention due to its features of achieving stable backhaul transmissions to WiMAX users and reducing the expenditure of network deployment. In implementing such a network, realizing a scheduling mechanism capable of sharing the available bandwidth between the heterogeneous Ethernet and WiMAX traffic in an effective manner is problematic. In the present study, this problem is addressed by using a game-theoretic-based scheme comprising a bankruptcy game and a bargaining game to perform an intra-ONU scheduling function at each ONU within the network. In the proposed approach, each ONU distributes the total amount of bandwidth allocated by the OLT between the Ethernet and WiMAX traffic buffers in accordance with the results of the bankruptcy game. By applying bargaining games, the allocated bandwidth is then further distributed to the different traffic classes within the Ethernet or WiMAX traffic in accordance with their QoS requirements. The simulation results confirm the validity and effectiveness of the proposed approach.

THE DESIGNS OF A SCALABLE OPTICAL PACKET SWITCHING ARCHITECTURE

Abstract This paper proposes a new switching architecture to be used in all optical packet switching networks. The proposed switch is derived from an original 2 × ?2 two‐stage multi‐buffer switched delay line based optical switching node, known as an M‐Quadro node. By incorporating bypass lines into the M‐Quadro architecture and employing a novel switch control strategy, the optical packet switching node can effectively resolve packet contentions, thus reducing the packet deflection probability substantially. Furthermore, we show that such architecture is scalable for a generic multiple stages optical packet switch with a larger number of input/output ports.

ActionView: a movement-analysis ambulatory monitor in elderly homecare systems

This paper develops a movement-analysis ambulatory monitor, designated as ActionView, which can be used in an elderly homecare system to analyze the body movements of elderly individuals whilst in their homes. ActionView monitor is equipped with a kinematic sensor to effectively detect the changes in the upper-body orientation and vertical acceleration of the individual. Furthermore, a remote backend server receives the detected signal from the kinematic sensor via a Wireless Sensor Network (WSN) and then identifies the corresponding body motion. The experimental results show that ActionView has a classification accuracy of approximately 90% when applied to the recognition of everyday elderly actions such as standing up, sitting down, walking, and so forth.