The voice activity detection (VAD) recorder and VAD network recorder : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Computer Science at Massey University

The project is to provide a feasibility study for the AudioGraph tool, focusing on two application areas: the VAD (voice activity detector) recorder and the VAD network recorder. The first one achieves a low bit-rate speech recording on the fly, using a GSM compression coder with a simple VAD algorithm; and the second one provides two-way speech over IP, fulfilling echo cancellation with a simplex channel. The latter is required for implementing a synchronous AudioGraph. In the first chapter we introduce the background of this project, specifically, the VoIP technology, the AudioGraph tool, and the VAD algorithms. We also discuss the problems set for this project. The second chapter presents all the relevant techniques in detail, including sound representation, speech-coding schemes, sound file formats, PowerPlant and Macintosh programming issues, and the simple VAD algorithm we have developed. The third chapter discusses the implementation issues, including the systems' objective, architecture, the problems encountered and solutions used. The fourth chapter illustrates the results of the two applications. The user documentations for the applications are given, and after that, we analyse the parameters based on the results. We also present the default settings of the parameters, which could be used in the AudioGraph system. The last chapter provides conclusions and future work

A Comprehensive Survey of Voice over IP Security Research

We present a comprehensive survey of Voice over IP security academic research, using a set of 245 publications forming a closed cross-citation set. We classify these papers according to an extended version of the VoIP Security Alliance (VoIPSA) Threat Taxonomy. Our goal is to provide a roadmap for researchers seeking to understand existing capabilities and to identify gaps in addressing the numerous threats and vulnerabilities present in VoIP systems. We discuss the implications of our findings with respect to vulnerabilities reported in a variety of VoIP products. We identify two specific problem areas (denial of service, and service abuse) as requiring significant more attention from the research community. We also find that the overwhelming majority of the surveyed work takes a black box view of VoIP systems that avoids examining their internal structure and implementation. Such an approach may miss the mark in terms of addressing the main sources of vulnerabilities, i.e., implementation bugs and misconfigurations. Finally, we argue for further work on understanding cross-protocol and cross-mechanism vulnerabilities (emergent properties), which are the byproduct of a highly complex system-of-systems and an indication of the issues in future large-scale systems

Link failure testing project on a satellite SDN network using Bidirectional Forwarding Detection

This project focuses on implementing a variable grid topology network for simulating an inter-satellite links connection to evaluate link failure detection times in a satellite SoftwareDefined Networking (SDN) using the Bidirectional Forwarding Detection (BFD) protocol (RFC 5880). Today, there is significant growth and deployment of LEO satellite networks, and SDN technology is being successfully used in these LEO satellite constellation networks due to the flexibility that this technology offers in the face of dynamic variation in topology network, limited bandwidth and traffic variations. An important point for the correct operation of these networks is the reliability and stability of the links that interconnect the satellites of the constellation, since this constellation is in permanent motion, orbiting the earth. The work developed in this project is directly related to this topic and the BFD detection protocol has been used to determine the connectivity failures of the test network links. The BFD is a protocol which provides fast forwarding path failure detection times and it is independent from physical media, routing protocols and data protocols. The BFD protocol works in the forwarding plane and is well suited for use with SDN switches. The testbed has been built using the "ContainerNet" Python API to implement the network topology and link interconnection of each satellite node. The satellite switching service is implemented in a docker instance, using OpenVirtualSwitch (OVS) as the internal packet switch of each node. OpenVirtualSwitch is an SDN-compliant programmable switching network device that has support for the BFD protocol. A transmission scenario is built on this switching network. This scenario includes two nodes that work as communication endpoints. The nodes have been configured so that between the endpoints there are two separate alternative paths. In addition to the datapath configuration, the BFD protocol has been configured to monitor the status of each link. A software developed running in all intermediate nodes are able to notify a link failure upstream of the datapath until the end nodes. An then end nodes can switch to another path. The final results must determine which are the BFD parameters to achieve a compromise between the BFD packet signaling period and the bandwidth used to keep the VoIP communication parameters within the acceptable limits in the event of a link failure with a route update

Multiplexer Technology in Utility Automation

In utility automation systems, data communication links have the essential role to convey real-time system between control centers and substations. Therefore, reliable and flexible communications are vital to run modern utility network in a safe and properly controlled way. In this thesis, possibilities of multiplexer technology in communications for utility automation systems are reviewed. At the beginning of this thesis, theory about multiplexing, especially SDH data transmission technology, and essential utility automation systems are discussed. Thereafter, the thesis concentrates on the characteristics and potential applications of the employer’s multiplexer device. Eventually, the performance requirements for the device are analyzed from the utility automation systems’ perspective and also some performance figures are measured with a build-up test system. Multiplexer technology was found to be well suitable for the underlying communications in utility automation systems. Especially the efficient protection schemes and network manageability makes SDH systems highly available and ensures quick reconfiguration in fault situations. Teleprotection that makes very fast operating times for power line protection possible, came up as the most important application.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Converged IP-over-standard ethernet progress control networks for hydrocarbon process automation applications controllers

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The maturity level of Internet Protocol (IP) and the emergence of standard Ethernet interfaces of Hydrocarbon Process Automation Application (HPAA) present a real opportunity to combine independent industrial applications onto an integrated IP based network platform. Quality of Service (QoS) for IP over Ethernet has the strength to regulate traffic mix and support timely delivery. The combinations of these technologies lend themselves to provide a platform to support HPAA applications across Local Area Network (LAN) and Wide Area Network (WAN) networks. HPAA systems are composed of sensors, actuators, and logic solvers networked together to form independent control system network platforms. They support hydrocarbon plants operating under critical conditions that — if not controlled — could become dangerous to people, assets and the environment. This demands high speed networking which is triggered by the need to capture data with higher frequency rate at a finer granularity. Nevertheless, existing HPAA network infrastructure is based on unique autonomous systems, which has resulted in multiple, parallel and separate networks with limited interconnectivity supporting different functions. This created increased complexity in integrating various applications and resulted higher costs in the technology life cycle total ownership. To date, the concept of consolidating HPAA into a converged IP network over standard Ethernet has not yet been explored. This research aims to explore and develop the HPAA Process Control Systems (PCS) in a Converged Internet Protocol (CIP) using experimental and simulated networks case studies. Results from experimental and simulation work showed encouraging outcomes and provided a good argument for supporting the co-existence of HPAA and non-HPAA applications taking into consideration timeliness and reliability requirements. This was achieved by invoking priority based scheduling with the highest priority being awarded to PCS among other supported services such as voice, multimedia streams and other applications. HPAA can benefit from utilizing CIP over Ethernet by reducing the number of interdependent HPAA PCS networks to a single uniform and standard network. In addition, this integrated infrastructure offers a platform for additional support services such as multimedia streaming, voice, and data. This network‐based model manifests itself to be integrated with remote control system platform capabilities at the end user's desktop independent of space and time resulting in the concept of plant virtualization

A novel approach to emergency management of wireless telecommunication system

The survivability concerns the service continuity when the components of a system are damaged. This concept is especially useful in the emergency management of the system, as often emergencies involve accidents or incident disasters which more or less damage the system. The overall objective of this thesis study is to develop a quantitative management approach to the emergency management of a wireless cellular telecommunication system in light of its service continuity in emergency situations – namely the survivability of the system. A particular wireless cellular telecommunication system, WCDMA, is taken as an example to ground this research.The thesis proposes an ontology-based paradigm for service management such that the management system contains three models: (1) the work domain model, (2) the dynamic model, and (3) the reconfiguration model. A powerful work domain modeling tool called Function-Behavior-Structure (FBS) is employed for developing the work domain model of the WCDMA system. Petri-Net theory, as well as its formalization, is applied to develop the dynamic model of the WCDMA system. A concept in engineering design called the general and specific function concept is applied to develop a new approach to system reconfiguration for the high survivability of the system. These models are implemented along with a user-interface which can be used by emergency management personnel. A demonstration of the effectiveness of this study approach is included.There are a couple of contributions with this thesis study. First, the proposed approach can be added to contemporary telecommunication management systems. Second, the Petri Net model of the WCDMA system is more comprehensive than any dynamic model of the telecommunication systems in literature. Furthermore, this model can be extended to any other telecommunication system. Third, the proposed system reconfiguration approach, based on the general and specific function concept, offers a unique way for the survivability of any service provider system.In conclusion, the ontology-based paradigm for a service system management provides a total solution to service continuity as well as its emergency management. This paradigm makes the complex mathematical modeling of the system transparent to the manager or managerial personnel and provides a feasible scenario of the human-in-the-loop management