Design Related Investigations for Media Access Control Protocol Service Schemes in Wavelength Division Multiplexed All Optical Networks

All-optical networks (AON) are emerging through the technological advancement of various optical components, and promise to provide almost unlimited bandwidth. To realise true network utilisation, software solutions are required. An active area of research is media access control (MAC) protocol. This protocol should address the multiple channels by wavelength division mutiplexing (WDM) and bandwidth management. Token-passing (TP) is one such protocol, and is adopted due to its simplicity and collisionless nature. Previously, this protocol has been analysed for a single traffic type. However, such a study may not substantiate the protocol's acceptance in the AON design. As multiple traffic types hog the network through the introduction multimedia services and Internet, the MAC protocol should support this traffic. Four different priority schemes are proposed for TP protocol extension, and classified as static and dynamic schemes. Priority assignments are a priori in static scheme, whereas in the other scheme, priority reassignments are carried out dynamically. Three different versions of dynamic schemes are proposed. The schemes are investigated for performance through analytical modelling and simulations. The semi-Markov process (SMP) modelling approach is extended for the analyses of these cases. In this technique, the behaviour of a typical access node needs to be considered. The analytical results are compared with the simulation results. The deviations of the results are within the acceptable limits, indicating the applicability ofthe model in all-optical environment. It is seen that the static scheme offers higher priority traffic better delay and packet loss performance. Thus, this scheme can be used beneficially in hard real-time systems, where knowledge of priority is a priori. The dynamic priority scheme-l is more suitable for the environments where the lower priority traffic is near real-time traffic and loss sensitive too. For such a scheme, a larger buffer with smaller threshold limits resulted in improved performance. The dynamic scheme-2 and 3 can be employed to offer equal treatment for the different traffic types, and more beneficial in future AONs. These schemes are also compared in their performance to offer constant QoS level. New parameters to facilitate the comparison are proposed. It is observed that the dynamic scheme-l outperforms the other schemes, and these QoS parameters can be used for such QoS analysis. It is concluded that the research can benefit the design of the protocol and its service schemes needed in AON system and its applications

THE INFLUENCE OF MAC BUFFER ON THE CONTENTION-BASED ACCESS SCHEME WITH BURSTING OPTION FOR IEEE 802.11E WIRELESS NETWORKS

Wireless LANs are increasingly being used for inelastic applications. Currently, there is little support for quality of service in the IEEE 802.11 MAC protocol, and IEEE task group E has defined the 802.11e MAC extension. Enhanced distributed channel access (EDCA) is a contention-based scheme of the 802.11e standard. To allow a station to transmit more than one frame from a single contention, an optional feature known as controlled frame-bursting (CFB) is introduced in the standard. In this paper, we initially performed an average analysis to determine a suitable burst duration limit. Then, a detailed evaluation and comparison of the EDCA protocol with the CFB option is carried out through simulation to quantify its performance gain. The impact of the MAC transmit buffer size is also incorporated. Accordingly, we have proposed a suitable approach to guide the configuration of the burst duration limit. It is demonstrated that an optimized CFB configuration allows the MAC protocol to achieve 30% more capacity than the basic EDCA scheme

A token-passing variable buffer model for a double-layered hierarchical WDM all-optical network

Presents a hierarchical all-optical network, employing wavelength division multiplexing for multiple channel transmission. A double-layered network with multiple sub-network implementation which provides for spatial wavelength reuse is considered. The piggybacked token-passing medium access protocol as a fair and non-contentious access scheme is studied for performance. The average delay in getting access to the network medium is determined from the semi-Markov process. The performance of the protocol model design with variable buffer sizes of the transmitter is analysed. It is shown from the double-layered hierarchical network that alternative route for data transmission can be implemented to improve on performance

Design of simulation system for performance predictions of WDM single-hop networks

Describes the design, development and use of a software architecture for a simulation environment to examine, validate and predict the performance of piggybacked token passing protocol for a wavelength division multiplexed (WDM) optical network. This simulation environment overcomes many of the limitations found with analytical models. A set of the principal components and their dynamics, which make up the simulation design has been identified. It is shown that this protocol optimises the usage of the bandwidth available in the optical fibre with more than 70% used for data transmission. It is also suggested that the number of channels required to accomplish a single-hop connection within a local environment is small with number of channels to nodes ratio of 1:4. This is comparatively small and requires only limited-tuneable transceivers

A scheduling algorithm for WDM optical networks

This paper proposes a scheduling algorithm for time-slotted WDM broadcast-and-select optical networks. The algorithm is free from collision and supports a particular class of quality of service (QoS), namely constant bit rate (CBR). The running time complexity of the algorithm is O(Mlog2N)1, where M and N are the number of packets used for scheduling and the number of nodes, respectively. This running time can be improved to O(log3N) by parallel processing

Incomplete LU preconditioner for FMM implementation

An incomplete LU (ILU) preconditioner using the near-field matrix of the fast multipole method (FMM) is investigated to increase the efficiency of the iterative conjugate gradient squared (CGS) solver. Unlike the conventional LU, ILU requires no fill ins, and hence no extra memory and CPU time in computing the LU decomposed preconditioner. It is shown that, due to the nature of the near-field matrix, ILU preconditioning decreases the number of iterations dramatically. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 265–267, 2000.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35044/1/18_ftp.pd

The time controlled clustering algorithm for optimised data dissemination in Wireless Sensor Networks

As the communication task is a significant power consumer, there are many attempts to improve energy efficiency. Node clustering, to reduce direct transmission to the base station, is one such attempt to control data dissemination. Here, we derived the optimal number of clusters for TCCA clustering algorithm based on a realistic energy model using results in stochastic geometry

A configurable time-controlled clustering algorithm for wireless sensor networks

Future large-scale sensor networks may comprise thousands of wirelessly connected sensor nodes that could provide an unimaginable opportunity to interact with physical phenomena in real time. These nodes are typically highly resource-constrained. Since the communication task is a significant power consumer, there are various attempts to introduce energy-awareness at different levels within the communication stack. Clustering is one such attempt to control energy dissipation for sensor data routing. Here, we propose the time-controlled clustering algorithm to realise a network-wide energy reduction by the rotation of clusterhead role, and the consideration of residual energy in its election. A realistic energy model is derived to accurately quantify the network\u27s energy consumption using the proposed clustering algorithm