Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A New Zigbee Backoff Approach for Home Healthcare Devices

Most of Healthcare Monitoring System (HMS) used ZigBee, one of the Wireless Sensor Network technologies that offer better mobility, low power consumption and better network scalability. However, ZigBee-based devices face overlapping channel with Wi-Fi devices which cause interference when deployed under the same operating frequency. In this paper, we proposed a new ZigBee algorithm based on Carrier Sense Multiple Access with Collision Avoidance (CSMA-CA) to minimize the Wi-Fi interference using experimental approach. Further elaboration highlights the approach, experiment set-up and the analysis metrics for the ZigBee and Wi-Fi coexistence issues. By minimizing the effect of Wi-Fi interference, it will improve the ZigBee transmission reliability which critically required for developing a reliability HMS application. A fragmentation packet management can be considered in the future development to improve packet allocation for large type packet to avoid collision with Wi-Fi packets for better HMS application performance

Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of data dissemination techniques for opportunistic networks

An opportunistic network is an infrastructure-less peer to peer network, created between devices that are mobile and wireless enabled. The links between devices are dynamic and often short-lived. Therefore, disseminating data from a source to recipients with a quality of service guarantee and efficiency is a very challenging problem. Furthermore, the interactions between devices are based on opportunity and are dependent on the devices mobility, which have extreme diverse patterns. The aim of this thesis is to investigate dissemination of data in opportunistic networks. In particular two conflicting objectives are studied: minimising the overhead costs and maximising the information coverage over time. We also take into account the effects of mobility. Extensive computer simulation is developed to explore models for information dissemination and mobility. On top of existing mobility models (i.e. Random Walk, Random, Waypoint and Gauss Markov) a hybrid model is derived from the Random Waypoint and Gauss Markov mobility models. The effect on mobility model on dissemination performance is found to be highly significant. This is based on sensitivity analysis on mobility and node density. We first consider different baseline push techniques for data dissemination. We propose four different push techniques, namely Pure Push, Greedy, L-Push and Spray and Relay to analyse the impact of different push techniques to the information dissemination performances. The results present different trade-offs between objectives. As a strategy to manage overheads, we consider controlling to which nodes information is pushed to by establishing a social network between devices. A logical social network can be built between mobile devices if they repeatedly see each other, and can be defined in different ways. This is important because it shows how content may potentially flow to devices. We explore the effects of mobility for different definitions of the social network. This shows how different local criteria for defining links in a social network lead to different social structures. Finally we consider the effect of combining the social structure and intelligent push techniques to further improve the data dissemination performance in opportunistic networks. We discover that prioritising pushing over a social network is able to minimise the overhead costs but it introduces a dissemination delay

Load balancing based on nodes distribution in mobile sensor network

In a large scale mobile sensor network, some coordinators may exhaust energy earlier if they are connected with excessive number of mobile nodes compared to the others. Balancing the load could stable and prolong the network lifetime, maximizes coordinators capabilities and improves net-work performance. In this paper, a mechanism to balance the coordinators' load based on the distribution of mobile sensor nodes in IEEE 802.15.4 protocol is presented. In this scheme, a coordinator is a static cluster head that collects data from the associated mobile sensor nodes. From the simulation results, the load balancing scheme successfully balances the distribution of mobile sensor nodes that attached to each coordinators. This therefore balances the energy consume among the coordinators and indirectly, delay in data reception is reduced when there are large number of mobile nodes in the system

Towards Achieving Intelligent Event Correlation for End-to-End Internet Performance Monitoring

The Internet has become a necessity to many organizations and also to the general public, similar to utilities such as electricity and water supply. Disruption or interruption to Internet availability would means reduced productivity and can be of negative consequence to many organizations. Therefore, it is critical that there is a mechanism to monitor Internet performance periodically in order to detect performance issues, and more importantly a mechanism to correlate the changes in the performance metrics with the event that causes the changes. Currently, there is no existing event correlation mechanism that is able to provide automated correlation between the changes in the end-to-end Internet performance with the occurrence of certain events or activities within an organization. Our goal is to develop an event correlation mechanism for end-to-end Internet performance monitoring which is automated and intelligent. In this paper, we describe in details the PingER monitoring framework, the challenges in interpreting the data collected from the framework, and finally discuss the requirements to develop an intelligent correlation engine for events correlation

Performance Evaluation of Beacon Enabled IEEE 802.15.4 MAC for Mobile Wireless Sensor Networks under NS-2

Wireless Sensor Network (WSN) has a large number of nodes capable of sensing, communicating and computing. WSNs have limitations due to limited storage, processing and transmission power. The IEEE802.15.4 Medium Access Control (MAC) protocol is used for low-rate wireless personal area network (LR-WPAN). LR-WPAN is basically designed for static wireless sensor networks. However, from literatures, we observed that IEEE802.15.4 is able to support weak mobility in mobile sensor networks [7]. This paper evaluates the IEEE802.15.4 MAC for strong mobility in mobile sensor network environments. We evaluate the performance of IEEE802.15.4 MAC based on both static and mobile coordinators, and taking into account two parameters which are speed and number of beacon orders. We observed the effect on association period, disassociation, and synchronization between the mobile node and the coordinator in strong mobility of mobile nodes. From the experiments, we obtained results on throughput, association and synchronization with different speed and beacon orders. We found that the IEEE802.15.4 cannot maintain association period in strong mobility. The weaknesses of mobile node association attempt and synchronization process degrade the overall performance of a network. We also identify some research problems that need to be addressed for successful implementation of MAC protocol with strong mobility in Mobile Wireless Sensor Networks

Fast Association Process (FAP) of Beacon Enabled for IEEE 802.15.4 in Strong Mobility

In strong mobility the mobile node association with a coordinator (static or mobile) is an important part of IEEE802.15.4 protocol. This research analyzes the mobile node association attempt process flows in detail. This research also proposes an enhanced association procedure names Fast Association Process (FAP) in strong mobility. FAP is introduced with new Association_Data request MAC command that increases the association period and provides fast association process in strong mobility. It reduces the redundant service primitives, avoid collision and decrease association attempt process delay. Comparing FAP with the original IEEE802.15.4 protocol, the number of association service primitives in FAP is 67% less than the original protocol, and the simulation results show that the association attempt time decreases 75%. FAP will get fast association attempt as the number of mobile nodes increased and nodes having strong mobility. It can be widely used in mobile wireless sensor network application