Internet based enterprise level collaboration tools enable organisations to make decisions faster and more accurately with less effort. However, these tools provide limited real-time group collaboration within and across organisations. This paper proposes a novel IP network layer filter architecture that provides efficient and scalable real-time group collaboration between the required entities within an organisation. This proposed network architecture uses a label filter mechanism to improve privacy, scalability and bandwidth for one-to-one, one-to-many and many-to-many real-time communication on an existing multicast group in an organisation.

Medium access control protocols for wireless sensor networks are almost always designed to be energy efficient. One mechanism used to reduce energy expenditure is to periodically turn off the radio receivers of the sensor nodes in a coordinated manner. The nodes with radio receivers turned off are said to be in the sleep mode. Nodes form virtual clusters based on common sleep schedules. However, protocols like the widely used S-MAC may require some nodes to follow multiple sleep schedules causing them to wake up more often than the other nodes. This paper demonstrates in some wireless sensor networks using S-MAC, a significant proportion of the nodes may have to stay awake much longer than envisaged. A modification of the protocol is then proposed to eliminate the need for some nodes to stay awake longer than the other nodes. The modified version improves the energy efficiency and increases the life span of a wireless sensor network. The paper concludes with the result of simulation studies which indicate that the use of the proposed protocol is expected to increase the life time of wireless sensor networks significantly.

Internet based enterprise level collaboration tools enable organizations to make decisions faster and more accurately with less effort. However, these tools provide limited real-time group collaboration within and across organizations. Multicast protocols were developed to provide efficient group communication. This paper proposes a novel IP multicast network layer filter architecture that provides efficient and scalable real-time group collaboration between the required entities within an organization. This proposed network architecture uses a label filter mechanism to improve scalability and bandwidth for one-to-many and many-to-many real-time collaboration.

Performance and availability are of critical importance when Internet services are integrated into emergency response management. Poor performance or service failure can result in severe economic, social or environmental cost. This paper presents Whirlwind, a software architecture that includes primitives for overload management and fault tolerance. A Whirlwind service is composed of a collection of isolated, independent, sequential processes that communicate through asynchronous message passing. If a process fails, the fault is contained within the process and a message is propagated to monitoring processes that may attempt to recover from the error. Processes are grouped with other processes that share similar resource, computation and concurrency requirements. Each group contains a scheduler and a thread pool that drives execution of processes within the group. The group may also define a message predicate that determines if a message posted to a process in the group is accepted. A rejected message typically signals overload and allows the application the chance to perform load shedding and avoid overcommitment of resources. Principals are shared between processes in different groups, enabling consistent prioritization and admission control across groups. The resource management policies are typically driven by feedback loops that monitor resource availability and system performance, and adjust tuning parameters to meet performance goals. Whirlwind evolved over a period of five fire seasons as part of emergency response software in Victoria, Australia.

Wireless sensor networks (WSNs) aim to fulfill the need for reliable and fault-tolerant sensing services. This has made wireless sensor networks a very active research area. SMAC is an energy efficient sensor MAC protocol. An S-MAC problem is that border nodes have to adopt multiple sleeping schedules, which speed up the energy depletion of border nodes. In this paper, S-MACL is proposed to overcome this problem. In S-MACL, a global sleeping schedule is used. The simulations result shows that S-MACL achieves a greater level of energy efficiency than S-MAC.

Protecting the network layer is an important problem in an ad hoc network. Several base network later protocols were built under the assumption that nodes forming an ad hoc network do not have enough power or processing capabilities to launch a powerful malicious attack. Thus they do not offer any immunity. AODV-S offers enhancement to the AODV protocol by incorporating protection against several routing attacks. However in this paper, we show that AODV-S is not immune to DoS attack using modified hop count. We also provide a solution to this problem using an ordering algorithm.

This paper describes the design and implementation of OBJECTSIM. OBJECTSIM overcomes the narrow focus of previous architecture simulators by specifying a small number of generic simulation objects (and an associated hierarchy) that are capable of implementing a wide range of target systems. Target systems range from multi-stage interconnection networks (MINs) and ATM and BISDN networks, through to bus and network based multiprocessors. OBJECTSIM also provides trace, execution and stochastic driver mechanisms. To simulate large systems ( > 256 nodes ) OBJECTSIM uses a distributed object oriented simulation kernel. The combination of this kernel with the object hierarchy method makes OBJECTSIM a unique contribution to the field. OBJECTSIM runs on a network of SUN stations.

This paper introduces a shared tree multicast filter that uses labels to create one-to-one, one-to-many and many-to-many communication on an existing multi cast tree. All the receivers wishing to communicate privately will be connected virtually by a label to form a subtree within an existing multicast tree. The data packet is sent to the receivers on paths identified by the label. A label manager on the tree will create and manage these labels. This paper describes the benefits of using our filter architecture compared to creating a new multicast tree or using another proposed filter architecture.

This paper defines a new wireless mobility architecture with quality of service (QoS) that uses the fixed network infrastructure for group communication. The mobile core-based tree (M-CBT) architecture uses multicast to provide fast handoff and reduce network utilization costs for group communication. The M-CBT architecture can be coupled with a multicast QoS routing protocol to provide QoS for mobile communication. The explore best path message (EBPM) protocol is a probe- based dynamic distributed multicast QoS routing protocol that is designed to quickly search the network for an optimal QoS path from a joining node to the multicast tree. This paper illustrates how mobile devices using M-CBT and EBPM can participate in group communications and quickly find a QoS path as they handoff to a new network.

This paper describes an architecture that filters packets within a subset of nodes on an existing shared multicast tree. The path connecting the group of nodes that want to communicate privately on the existing tree was given a label. These labels are used to route one-to-one and group communication traffic for selected nodes on a multicast tree. Nodes connected to the tree but are not on this label path do not receive any filtered packets. This filter architecture reduces network resource waste by utilising the existing network resources on the multicast tree like quality of service (QoS). In this paper, we also describe how this architecture can be used for mobile communication when implemented in a shared tree mobile multicast architecture.

This paper defines a new multicast filter algorithm. This algorithm is used to filter packets on a mobile multicast architecture using a multicast shared tree. In a mobile multicast architecture, communications between a corresponding node (source) and the mobile node (receiver) should be private and not be sent to every node (receivers) on the multicast tree. We propose using an algorithm that sets up a label sub-tree on an existing mobile multicast shared tree to filter packets based on these labels. Our proposed label filter architecture is implemented differently to the current MPLS architecture. In this paper, we validate the effectiveness of the label filter in mobile communication compared to the traditional method of creating a new multicast tree by analysing the message and time complexity of the algorithm against the setting up time of a new multicast shared tree.

IP multicasting provides a mechanism for faster handoff support than Mobile IP [9] [16]. Coupled with its location independent addressing, multicasting is a viable alternative to support mobility in the Internet. This paper continues research into using IP multicasting in mobility.Our proposed scheme looks at enabling a mobile node to initiate two way communications with a corresponding node on a shared multicast tree. We use as much of the existing Internet architecture as possible by making the base-station a member of the multicast group. The mobile is not directly connected to the tree but goes through the base-station to send and receive packets.This paper explains the differences and advantages of our proposed scheme compared with other multicast based mobility schemes and Mobile IP.