OpenUCT :: Browsing by Author "Ventura, Neco"

Browsing by Author "Ventura, Neco"

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Open Access
AAL2 signalling framework to support a Gigabit AAL2 switching node
(2003) Van Zyl, André; Ventura, Neco
Although Asynchronous Transfer Mode (ATM) Adaptation Layer type 2 (AAL2) has been in existence for a few short years, it is widely being adopted as the technology of choice in VoDSL. VOTA trunking, as well as in UMTS wireless networks. The two most important concerns when transporting voice in a packet based network, are end-to-end delay and the efficient use of available bandwidth.
Open Access
AAL2 switching node to support voice services in 3rd and 4th generation networks
(2002) Shepstone, Sven E; Ventura, Neco
The research community and industry alike have, over the past decade, been showing considerable interest in packet-switching networks to support voice services as well as data services. A technology that was standardised to accommodate these delay-sensitive requirements is Asynchronous Transfer Mode (ATM), which deals particularly well at transporting uncompressed voice and data. However, due to the exponential increase in wireless applications and their supporting access technologies, a need has arisen for an infrastructure in the wide area network to support and maintain the QoS requirements of low-bit rate, compressed voice. An adaptation layer known as AAL2 was re-standardised to support these specialised voice services. However, a severe side-effect of using AAL2 with traditional ATM switches results in inefficient routing and waste-age of resources. In this study, a design for an AAL2 switching node will be proposed to address the above-mentioned issues. The design is comprised of modules that perform the following functions: Buffering, payload interrogation, protocol translations, packet classification, packet re- routing, timing, scheduling and support for signalling and management interfacing. The supporting architecture is targeted towards an embedded >286-based computing system, which itself is overlaid upon one or several ports of a high-speed, research-oriented ATM switch, known as the Washington University Gigabit Switch (WUGS). In order to evaluate the operation and performance of the AAL2 switch architecture, a testbed is proposed and implemented, comprising the AAL2 switch at the core, with a supporting infrastructure to emulate the generation and analysis of low bit-rate voice traffic over an AAL2 connection. By conducting a set of experiments, a series of operational and performance results will be presented. Particular focus will be placed on the performance and efficiency of the AAL2 layer over ATM, as well as the ability of the switch to route packets from multiple sources to a set of output connections in the correct manner.
Open Access
Access network selection schemes for multiple calls in next generation wireless networks
(2017) Orimolade, Joseph Folorunsho; Ventura, Neco; Falowo, Olabisi E
There is an increasing demand for internet services by mobile subscribers over the wireless access networks, with limited radio resources and capacity constraints. A viable solution to this capacity crunch is the deployment of heterogeneous networks. However, in this wireless environment, the choice of the most appropriate Radio Access Technology (RAT) that can Tsustain or meet the quality of service (QoS) requirements of users' applications require careful planning and cost efficient radio resource management methods. Previous research works on access network selection have focused on selecting a suitable RAT for a user's single call request. With the present request for multiple calls over wireless access networks, where each call has different QoS requirements and the available networks exhibit dynamic channel conditions, the choice of a suitable RAT capable of providing the "Always Best Connected" (ABC) experience for the user becomes a challenge. In this thesis, the problem of selecting the suitable RAT that is capable of meeting the QoS requirements for multiple call requests by mobile users in access networks is investigated. In addressing this problem, we proposed the use of Complex PRoprtional ASsesment (COPRAS) and Consensus-based Multi-Attribute Group Decision Making (MAGDM) techniques as novel and viable RAT selection methods for a grouped-multiple call. The performance of the proposed COPRAS multi-attribute decision making approach to RAT selection for a grouped-call has been evaluated through simulations in different network scenarios. The results show that the COPRAS method, which is simple and flexible, is more efficient in the selection of appropriate RAT for group multiple calls. The COPRAS method reduces handoff frequency and is computationally inexpensive when compared with other methods such as the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Simple Additive Weighting (SAW) and Multiplicative Exponent Weighting (MEW). The application of the proposed consensus-based algorithm in the selection of a suitable RAT for group-multiple calls, comprising of voice, video-streaming, and file-downloading has been intensively investigated. This algorithm aggregates the QoS requirement of the individual application into a collective QoS for the group calls. This new and novel approach to RAT selection for a grouped-call measures and compares the consensus degree of the collective solution and individual solution against a predefined threshold value. Using the methods of coincidence among preferences and coincidence among solutions with a predefined consensus threshold of 0.9, we evaluated the performance of the consensus-based RAT selection scheme through simulations under different network scenarios. The obtained results show that both methods of coincidences have the capability to select the most suitable RAT for a group of multiple calls. However, the method of coincidence among solutions achieves better results in terms of accuracy, it is less complex and the number of iteration before achieving the predefined consensus threshold is reduced. A utility-based RAT selection method for parallel traffic-streaming in an overlapped heterogeneous wireless network has also been developed. The RAT selection method was modeled with constraints on terminal battery power, service cost and network congestion to select a specified number of RATs that optimizes the terminal interface utility. The results obtained show an optimum RAT selection strategy that maximizes the terminal utility and selects the best RAT combinations for user's parallel-streaming for voice, video and file-download.
Open Access
An admission control scheme for IEEE 802.11e wireless local area networks
(2008) Smith, Conroy; Ventura, Neco
Recent times has seen a tremendous increase in the deployment and use of 802.11 Wireless Local Area Networks (WLANs). These networks are easy to deploy and maintain, while providing reasonably high data rates at a low cost. In the paradigm of Next-Generation-Networks (NGNs), WLANs can be seen as an important access network technology to support IP multimedia services. However a traditional WLAN does not provide Quality of Service (QoS) support since it was originally designed for best effort operation. The IEEE 802. 11e standard was introduced to overcome the lack of QoS support for the legacy IEEE 802 .11 WLANs. It enhances the Media Access Control (MAC) layer operations to incorporate service differentiation. However, there is a need to prevent overloading of wireless channels, since the QoS experienced by traffic flows is degraded with heavily loaded channels. An admission control scheme for IEEE 802.11e WLANs would be the best solution to limit the amount of multimedia traffic so that channel overloading can be prevented. Some of the work in the literature proposes admission control solutions to protect the QoS of real-time traffic for IEEE 802.11e Enhanced Distributed Channel Access (EDCA). However, these solutions often under-utilize the resources of the wireless channels. A measurement-aided model-based admission control scheme for IEEE 802.11e EDCA WLANs is proposed to provide reasonable bandwidth guarantees to all existing flows. The admission control scheme makes use of bandwidth estimations that allows the bandwidth guarantees of all the flows that are admitted into the network to be protected. The bandwidth estimations are obtained using a developed analytical model of IEEE 802.11e EDCA channels. The admission control scheme also aims to accept the maximum amount of flows that can be accommodated by the network's resources. Through simulations, the performance of the proposed admission control scheme is evaluated using NS-2. Results show that accurate bandwidth estimations can be obtained when comparing the estimated achievable bandwidth to actual simulated bandwidth. The results also validate that the bandwidth needs of all admitted traffic are always satisfied when the admission control scheme is applied. It was also found that the admission control scheme allows the maximum amount of flows to be admitted into the network, according the network's capacity.
Open Access
Architecture of a cognitive non-line-of-sight backhaul for 5G outdoor urban small cells
(2017) Malila, Bessie; Falowo, Olabisi E; Ventura, Neco
Densely deployed small cell networks will address the growing demand for broadband mobile connectivity, by increasing access network capacity and coverage. However, most potential small cell base station (SCBS) locations do not have existing telecommunication infrastructure. Providing backhaul connectivity to core networks is therefore a challenge. Millimeter wave (mmW) technologies operated at 30-90GHz are currently being considered to provide low-cost, flexible, high-capacity and reliable backhaul solutions using existing roof-mounted backhaul aggregation sites. Using intelligent mmW radio devices and massive multiple-input multiple-output (MIMO), for enabling point-to-multipoint (PtMP) operation, is considered in this research. The core aim of this research is to develop an architecture of an intelligent non-line-sight (NLOS) small cell backhaul (SCB) system based on mmW and massive MIMO technologies, and supporting intelligent algorithms to facilitate reliable NLOS street-to-rooftop NLOS SCB connectivity. In the proposed architecture, diffraction points are used as signal anchor points between backhaul radio devices. In the new architecture the integration of these technologies is considered. This involves the design of efficient artificial intelligence algorithms to enable backhaul radio devices to autonomously select suitable NLOS propagation paths, find an optimal number of links that meet the backhaul performance requirements and determine an optimal number of diffractions points capable of covering predetermined SCB locations. Throughout the thesis, a number of algorithms are developed and simulated using the MATLAB application. This thesis mainly investigates three key issues: First, a novel intelligent NLOS SCB architecture, termed the cognitive NLOS SCB (CNSCB) system is proposed to enable street-to-rooftop NLOS connectivity using predetermined diffraction points located on roof edges. Second, an algorithm to enable the autonomous creation of multiple-paths, evaluate the performance of each link and determine an optimal number of possible paths per backhaul link is developed. Third, an algorithm to determine the optimal number of diffraction points that can cover an identified SCBS location is also developed. Also, another investigated issue related to the operation of the proposed architecture is its energy efficiency, and its performance is compared to that of a point-to-point (PtP) architecture. The proposed solutions were examined using analytical models, simulations and experimental work to determine the strength of the street-to-rooftop backhaul links and their ability to meet current and future SCB requirements. The results obtained showed that reliable multiple NLOS links can be achieved using device intelligence to guide radio signals along the propagation path. Furthermore, the PtMP architecture is found to be more energy efficient than the PtP architecture. The proposed architecture and algorithms offer a novel backhaul solution for outdoor urban small cells. Finally, this research shows that traditional techniques of addressing the demand for connectivity, which consisted of improving or evolving existing solutions, may nolonger be applicable in emerging communication technologies. There is therefore need to consider new ways of solving the emerging challenges.
Open Access
An artificial Intelligence Approach to improving Speech Recognition
(2009) Lopes, Luis Ramos dos Santos; Mashao, Daniel; Ventura, Neco
Speech Recognition is a technology with promising applications. However, the performance of current speech recognizers greatly limit their widespread use. Approaches to reducing the word error rate have mainly been associated with statistical techniques. As a consequence, speech recognition results can still contain sentences that are nonsensical. The method proposed here, is to analize the output of any chosen speech recognition system, in order to determine whether a sentence contains syntactic or semantic errors. This is done via a software agent that uses the information from its knowledge base to attempt to correct the errors found. A system was implemented with a small vocabulary speaker-independent continuous speech recognition system, with limited sentence structures. The achieved increase in speech recognition accuracy, shows that there are bene ts in using this approach.
Open Access
Carrier grade resilience in geographically distributed software defined networks
(2017) Lewis, John Arundel; Ventura, Neco
The Internet is a fundamental infrastructure in modern life, supporting many different communication services. One of the most critical properties of the Internet is its ability to recover from failures, such as link or equipment failure. The goal of network resilience heavily influenced the design of the Internet, leading to the use of distributed routing protocols. While distributed algorithms largely solve the issue of network resilience, other concerns remain. A significant concern is network management, as it is a complex and error-prone process. In addition, network control logic is tightly integrated into the forwarding devices, making it difficult to upgrade the logic to introduce new features. Finally, the lack of a common control platform requires new network functions to provide their own solutions to common, but challenging, issues related to operating in a distributed environment. A new network architecture, software-defined networking (SDN), aims to alleviate many of these network challenges by introducing useful abstractions into the control plane. In an SDN architecture, control functions are implemented as network applications, and run in a logically centralized network operating system (NOS). The NOS provides the applications with abstractions for common functions, such as network discovery, installation of forwarding behaviour, and state distribution. Network management can be handled programmatically instead of manually, and new features can be introduced by simply updating or adding a control application in the NOS. Given proper design, an SDN architecture could improve the performance of reactive approaches to restoring traffic after a network failure. However, it has been shown in this dissertation that a reactive approach to traffic restoration will not meet the requirements of carrier grade networks, which require that traffic is redirected onto a back-up route less than 50 ms after the failure is detected. To achieve 50 ms recovery, a proactive approach must be used, where back-up rules are calculated and installed before a failure occurs. Several different protocols implement this proactive approach in traditional networks, and some work has also been done in the SDN space. However, current SDN solutions for fast recovery are not necessarily suitable for a carrier grade environment. This dissertation proposes a new failure recovery strategy for SDN, based on existing protocols used in traditional carrier grade networks. The use of segment routing allows for back-up routes to be encoded into the packet header when a failure occurs, without needing to inform other switches of the failure. Back-up routes follow the post-convergence path, meaning that they will not violate traffic engineering constraints on the network. An MPLS (multiprotocol label switching) data plane is used to ensure compatibility with current carrier networks, as MPLS is currently a common protocol in carrier networks. The proposed solution was implemented as a network application, on top of an open-source network operating system. A geographically distributed network testbed was used to verify the suitability for a geographically distributed carrier network. Proof of concept tests showed that the proposed solution provides complete protection for any single link, link aggregate or node failure in the network. In addition, communication latencies in the network do not influence the restoration time, as they do in reactive approaches. Finally, analysis of the back-up path metrics, such as back-up path lengths and number of labels required, showed that the application installed efficient back-up paths.
Open Access
Connection admission control and packet scheduling for IEEE 802.16 networks
(2012) Falowo, Samuel Kehinde; Ventura, Neco
The IEEE 802.16 standard introduced as one of the Wireless Metropolitan Area Networks (WMAN) for Broadband Wireless Access (BWA) which is known as Worldwide Interoperability for Microwave Access (WiMAX), provides a solution of broadband connectivity to areas where wired infrastructure is economically and technically infeasible. Apart from the advantage of having high speeds and low costs, IEEE 802.16 has the capability to simultaneously support various service types with required QoS characteristics. ... While IEEE 802.16 standard defines medium access control (MAC) and physical (PHY) layers specification, admission control and packet scheduling mechanisms which are important elements of QoS provisioning are left to vendors to design and implement for service differentiation and QoS support.
Open Access
Cooperation enforcement in ad-hoc wireless networks
(2005) Waiting, David; Ventura, Neco
Ad-hoc networks consist of a system of wireless nodes that can freely and dynamically self-organise into a working network topology. This allows people to internetwork seamlessly in areas that have no preexisting communication infrastructure. Nodes are expected to forward the traffic of other nodes in order for the packets to reach their final destination. It is envisaged that community ad-hoc networks will become widespread in the near future, as they require no administrative support. Nodes will be able to enter and leave the network as they choose. An unfortunate result is that in an open multi-agent system such as this, the role-players tend to be unreliable and self-interested.
Open Access
Delivering personalised advertising in IMS-based IPTV through direct marketing
(2010) Wilson, Phillipa R; Ventura, Neco
Multimedia applications and communication services are offered to users free of charge over the open Internet. However, since the Internet is a best effort network, these services are not associated with any Quality of Service (QoS) and Quality of Experience (QoE) guarantees. Furthermore, security cannot be guaranteed when using these services over the open Internet.
Open Access
Dynamic service orchestration in the IP multimedia subsystem
(2017) Spiers, Richard; Ventura, Neco
The continued growth of the Internet has resulted in a massive uptake of different communication services. An ever-increasing number of users are utilising rich multimedia services, and are both consuming and producing user generated content. This rapid growth in bandwidth and complexity has resulted in challenges for the previous architectures used in telecommunication networks. As a result, two of the major challenges faced by telecommunication network operators are an increase in the number of services that an end user expects to be able to use, as well as the desire to have personalised, custom use of these services. Over-the-top providers have begun to offer telecommunication services over the physical infrastructure of the traditional network operator, bypassing the lengthy and costly development cycle involved in offering carrier grade communication services. To adapt to this new landscape, the IP Multimedia Subsystem (IMS) was proposed. Its ongoing standardisation is being led by the 3rd Generation Partnership Project (3GPP) and it is a Next Generation Network (NGN) that is heading towards converged multimedia services. This NGN contains IP based network services that allow telecommunication operators the reuse of common building blocks for new services, reducing the time and cost to provision a new service. The thesis begins with an overview of the current landscape that plays a critical role in the formation and deployment of the IMS. This is followed by a literature review of service provisioning in the IMS. It looks at both the current, standardised architecture as well as several new approaches currently being researched. It determines that there is a need for further work in this area, and this concurs with the view of the standards body responsible for the IMS. However, there are limits on what can be proposed moving forward as deployment of the IMS architecture has already begun. The work continues with the creation of a novel architecture that would allow a network operator greater flexibility in routing service requests, as well as the ability to expose this functionality to the end user. This allows the end user to customise their service usage, something which is in great demand with the rise of user generated content and the new services being used over the internet. A prototype of the architecture is evaluated to determine the feasibility of the proposed architecture. Emphasis is placed on ensuring correct operation and increasing the range of functionality available. The prototype is evaluated in a test-bed provisioned through the use of Amazon's Elastic Compute Cloud (EC2). This is an Infrastructure as a Service (IaaS) offering that provides resizeable or elastic computing resources to researchers or developers, allowing the rapid deployment and reconfiguration of many different virtual servers. Different combinations of services that were identified as not being possible under the previous standardised architecture are evaluated in this test-bed. The proof of concept implementation provides the necessary functionality to execute these service combinations successfully without adding custom combined services. The evaluation is comprised of both functional and performance tests although the emphasis is on the former. As all components have been made available under open source licenses, it is possible for other researchers to reproduce this work and continue investigating this area. The work successfully demonstrates improved service triggering in the IMS whilst providing end users a much higher degree of control over the use of their telecommunication services.
Open Access
E-learning : virtual classrooms as an added learning platform
(2011) Nyarko, Michael; Ventura, Neco
Some of the challenges being face by the South African Department of education are the shortage of teachers, over-crowded classrooms and lack of teaching resources such as textbooks. Alternative teaching and learning platforms are needed to supplement traditional classroom teaching and learning.
Open Access
Efficient radio resource management in integrated terrestrial and non-terrestrial networks
(2024) Birabwa, Denise Joanitah; Ramotsoela, Daniel; Ventura, Neco
The beyond 5G (B5G) networks are envisaged to provide terra bps data rates and ubiquitous and unlimited wireless coverage. However, the terrestrial deployment of 5G networks poses a limitation in achieving a truly ubiquitous and seamlessly connected network. To this end, it has been proposed to integrate terrestrial networks (TNs) with non-terrestrial networks (NTNs), such as satellite communications, high-altitude platforms and low-altitude platforms. NTNs are characterised by wide coverage and less vulnerability to physical attacks and natural disasters, and hence, will complement TNs in providing ubiquitous wireless connectivity and enhanced broadband services to unserved and underserved areas. In addition, NTNs will provide network resilience to physical attacks and natural disasters, improve the quality of service (QoS) for overloaded TNs, and enhance service continuity for moving platforms. Consequently, the B5G network will be an integrated terrestrial and nonterrestrial network (ITNTN) consisting of multiple radio access networks (RANs) coexisting to provide radio access to multi-mode user equipment. This thesis addresses the problem of efficient user association and resource allocation in the ITNTN. The RANs in the ITNTN have different capabilities and limitations in meeting the envisioned B5G contrasting user requirements such as throughput, latency, and mobility. Therefore, determining an optimal association and resource allocation scheme that maps the heterogeneous users to the appropriate RANs while at the same time maximising resource utilisation, and providing the required user QoS, is rigorous and complex. Besides, such coexistence of the different RANs implies an increase in the number of wireless access nodes and thus raises a justifiable concern over the drastic increase in energy consumption and carbon emission expected to ensue. Accordingly, there is a need to develop efficient radio resource management (RRM) algorithms for the ITNTN that consider not only the heterogeneity in user QoS requirements but also the uniqueness of the different RANs in meeting these demands. To this end, this research aims at developing efficient RRM schemes that achieve a spectrum-efficient and energy-efficient ITNTN while minimising mobility-induced handoffs. RRM takes the form of user association and resource allocation in this work. First, the research formulates the user association and resource allocation problem in the ITNTN as a multi-objective optimisation problem (MOOP) that jointly maximises the total data rate of the ITNTN while minimising the probability of mobility-induced handoffs. The problem is subjected to constraints on the resource budget and minimum user QoS requirements in terms of data rate. Moreover, the problem is formulated to allow differentiated service provisioning and priority-based user association and resource allocation, thus prioritising mission-critical users' service provisioning. The weighted sum method is adopted to simplify and transform the MOOP into a single-objective optimisation problem (SOOP). The SOOP's complexity is reduced by decomposing it into two sub-problems: the user association sub-problem and the resource distribution sub-problem. A service-aware greedy heuristic algorithm is proposed to solve the user association sub-problem and its performance compared to the serviceunaware scheme. Simulation results reveal that the service-aware algorithm achieves higher overall network spectrum efficiency (SE), user acceptance ratio (AR), and lower handoff probability. Furthermore, the resource distribution sub-problem is reformulated into a waterfilling problem and solved utilising CVXPY, consequently analysing the effect of distributing the unallocated basic bandwidth units to the associated users. Second, since the greedy heuristic solution to the user association sub-problem does not ordinarily produce an optimal solution, the work further proposes a polynomial-time solution based on the genetic algorithm (GA). The performance of the GA is evaluated by comparing it to the ILP solution, the greedy heuristic solution, and the random user association (RUA) algorithm. Simulation results reveal that the GA outperforms all algorithms in terms of SE and user acceptance ratio. Moreover, the GA achieves a handoff probability of zero, unlike the RUA algorithm. Third, the proposed greedy heuristic and GA solutions to the user association subproblem utilise a central node that requires nearly-complete information, which may not be available in real-time. Therefore, this research further proposes a centralised training and distributed execution multi-agent duelling double deep Q network (MA3DQN) solution that facilitates real-time decision-making. Each user collects the channel state and access node loading information in this approach and makes an association decision that considers its quality of service requirements. This section of the thesis further adopts the effective capacity theorem to guarantee the delay QoS requirements for mission-critical users. The MA3DQN's performance is validated through comparison with the GA, the ILP solution, a heuristic approximation-based solution, the greedy approach, and the RUA algorithm. Moreover, the multi-agent deep Q network (MADQN) solution is also simulated as an additional benchmark algorithm. Simulation results reveal that as the number of users in the network increases, the acquired data rate of the MA3DQN is within 0.48% and 0.42% of that achieved by the GA and ILP, respectively, and outperforms all other algorithms. Notably, the proposed MA3DQN algorithm presents the best running time, attaining a gain of 99.9% over the GA algorithm, which performs the poorest among the algorithms characterised by polynomial worst-case time complexity. Besides, the MA3DQN approach maintains a handoff probability of zero, unlike the approximation-based, and RUA solutions. Lastly, the thesis presents a weighted sum SOOP that maximises the energy efficiency (EE) of the ITNTN while simultaneously minimising the mobility-induced handoff probability. The formulated problem is a non-convex and mixed integer non-linear programming problem whose complexity is reduced through decomposition into two sub-problems: the user association and resource allocation (UARA) problem and the power allocation (PA) problem. The equivalent UARA problem maximises the total network data rate and minimises the mobility-induced handoffs, thus can be solved by the GA or the MA3DQN already discussed. On the other hand, the PA problem is a fractional programming problem (FPP) that is simplified through transformation into a weighted sum SOOP and solved using the particle swarm optimisation (PSO) approach. Simulation results reveal that depending on the value of the weighting factor in the SOOP, the particle swarm optimisation power allocation (PSOPA) algorithm either minimises power consumption, thereby maximising the EE of the ITNTN, or maximises the total network data rate. When the power consumption is minimised, the PSOPA outperforms the equal power allocation (EPA) technique in EE. On the other hand, when the achieved network data rate is maximised, the PSOPA's achieved data rate approaches the upper bound set by the EPA algorithm. Unlike many recent proposals in the literature on user association and resource allocation in the ITNTN, the algorithms proposed in this thesis consider the heterogeneity in user traffic types. Moreover, the capabilities and limitations of the different networks in meeting the contrasting user demands are considered. For instance, to the best of our knowledge, no work in literature prioritises the wide coverage non-terrestrial networks over terrestrial networks for long-distance and highly mobile applications. Such a consideration reduces the handoff rate, ultimately reducing the probability of handoff failure, delays, and communication overheads.
Open Access
Energy management for the smart home
(2017) Sikasote, Nataizya; Ventura, Neco
Utility providers are under constant pressure to meet the ever-increasing demand for energy with a finite production capacity. Due to this, utility providers need to ensure that the demand does not exceed the supply. The use of demand response programs has been used as a solution to better match the available supply to the demand experienced on the grid. While demand response programs may improve the relationship between the supply and the demand, increasing consumer participation can further improve the effectiveness of demand response programs. The level of consumer participation is highly dependent on the incentives offered and the convenience of participating in the demand response program. However, most of these programs require consumers to actively monitor the available services and take appropriate action on their appliances. Home energy management systems attempt to provide convenience to consumers as well as increase their participation in demand response programs. They do this by enabling autonomous control and remote control of appliances. In addition, a home gateway makes it possible for the consumer and utility provider to interact with devices in the home remotely. Current solutions host the home energy management software on a home gateway or on a dedicated device in the home. Furthermore, these systems make use of proprietary software and devices to monitor and control the home environment. However, proprietary systems are costly to implement and maintain due to their dependence on the developers and the varying needs of consumers. This dissertation proposes a home energy management system solution that makes use of a standardized distributed machine-to-machine (M2M) middleware framework to support heterogeneous devices, technologies and protocols. In addition, the proposed solution shifts the software logic of the home energy management system from the gateway to a private cloud. This allows the system to leverage the benefits of virtualization and cloud computing such as cost efficiency, faster deployment and easier maintenance of the system. The proposed solution was implemented using a European Telecommunications Standards Institute (ETSI) compliant distributed M2M middleware framework (i.e. OpenMTC) and an open-source private cloud platform (i.e. OpenStack). A prototype was developed and tested with demand response programs that included a control demand response (DR) service, a consumption monitoring service and a time-of-use (ToU) service. In addition, the prototype made use of various third party applications, protocols and devices to support the aforementioned demand response services and provide automated and remote control of home appliances. Finally, an evaluation of the proposed system was conducted and concluded that the number of home energy management systems subscribed to the defined services influenced the effectiveness of these services because of the additional processing that the utility provider is required to perform.
Open Access
Enhanced link layer handover based on localization
(2008) Kumbuza, Xola; Ventura, Neco
Wireless Technologies over the past years have become cheaper and more available to users. In the Infrastructure Mode of operation, when a mobile node moves from the coverage of one Access Point (AP) to the coverage of another AP, it is said to undergo handoffs. The mobile node has to complete a link layer handoffs together with other tasks associated with handoffs in order to effectively have a new wireless link with the new AP. The link layer handoffs currently specified and practiced in IEEE 802.11 is normally carried out in three time steps. These are; the Scanning Phase; the Authentication Phase and the Association Phase. During the three steps the mobile node is unable to send or receive data meaning that packets are lost or delayed causing real-time applications such as video streaming or VoIP, which can only tolerate an end-to-end delay of 50 ms during handoffs, to suffer. The Scanning phase can be done passively or actively. In passive scanning, the mobile node listens on every bandwidth channel for Beacon Frames from the APs. In active scanning, the mobile node sends Probe Requests frames on every channel expecting to receive Probe Responses from the APs operating on each channel. Localization is the process of a node ending its position in space. Localization methods include the Global Positioning Service (GPS), Cricket, Ultrasonic Location and many more. This study investigates how localization can be used to decrease the latency delay experienced at the link layer during wireless handoffs. In our method, a mobile node is given the ability to have knowledge of the APs through an AP-Table server. The mobile node then uses localization to and the closest APs to it and make faster, smarter handoffs. Our simulations are implemented using the NCTUns network simulator and emulator. The simulations comprise of a mobile node undergoing handoffs between APs in the same subnet and APs in different subnets. Added to that, the direction of the mobile node is monitored and used to further assist the handoffs process to alleviate the number of total handoffs. Our research shows the disadvantages and advantages of the proposed system as it integrates localization and direction into WLAN and mobile communication.
Open Access
A flexible medium access control framework for multimedia application support in wireless ATM
(2002) How, Dale Graham; Ventura, Neco
The field of wireless communications has seen phenomenal development over the last decade. With the current abundance of applications that use broadband multimedia over wired networks it is logical that users will want to have access to these same multimedia streams [rom a mobile terminal. Wireless solutions for connectivity to networks such as Ethernet networks already exist, however, a method of supporting access to an ATM network from a mobile terminal has not yet been standardised. Transporting ATM data over the wireless medium poses a number of problems. The Medium Access Control (MAC) layer of any proposed wireless ATM network would be responsible for resolving many of these problems. Unfortunately, research into MAC layers is hampered by the fact that most existing MAC layers cannot be modified in order to experiment with the effectiveness of the many MAC protocol techniques that exist.
Open Access
A framework to provide charging for third party composite services
(2010) Mwangama, Joyce Bertha; Ventura, Neco
Over the past few years the trend in the telecommunications industry has been geared towards offering new and innovative services to end users. A decade ago network operators were content with offering simple services such as voice and text messaging. However, they began to notice that these services were generating lower revenues even while the number of subscribers increased. This was a direct result of the market saturation and network operators were forced to rapidly deploy services with minimum capital investment and while maximising revenue from service usage by end users. Network operators can achieve this by exposing the network to external content and service providers. They would create interfaces that would allow these 3rd party service and content providers to offer their applications and services to users. Composing and bundling of these services will essentially create new services for the user and achieve rapid deployment of enhanced services. The concept of offering a wide range of services that are coordinated in such a way that they deliver a unique experience has sparked interest and numerous research on Service Delivery Platforms (SDP). SDP‟s will enable network operators to be able to develop and offer a wide-variety service set. Given this interest on SDP standardisation bodies such as International Telecommunications Union – Telecommunications (ITU-T), Telecoms and Internet converged Servicers and Protocols for Advanced Networks) (TISPAN), 3rd Generations Partnership Project (3GPP) and Open Mobile Alliance (OMA) are leading efforts into standardising functions and protocols to enhance service delivery by network operators. Obtaining revenue from these services requires effective accounting of service usage and requires mechanisms for billing and charging of these services. The IP Multimedia subsystem(IMS) is a Next Generation Network (NGN) architecture that provides a platform for which multimedia services can be developed and deployed by network operators. The IMS provides network operators, both fixed or mobile, with a control layer that allows them to offer services that will enable them to remain key role players within the industry. Achieving this in an environment where the network operator interacts directly with the 3rd party service providers may become complicated.
Open Access
Host mobility management with identifier-locator split protocols in hierarchical and flat networks
(2012) Mulam, Muhana Magboul Ali; Chan, H Anthony; Ventura, Neco
As the Internet increasingly becomes more mobile focused and overloaded with mobile hosts, mobile users are bound to roam freely and attach to a variety of networks. These different networks converge over an IP-based core to enable ubiquitous network access, anytime and anywhere, to support the provision of services, that is, any service, to mobile users. Therefore, in this thesis, the researcher proposed network-based mobility solutions at different layers to securely support seamless handovers between heterogeneous networks in hierarchical and flat network architectures.
Open Access
A hybrid network/host mobility management scheme for next generation networks
(2011) Masuabi, Francis Mphakiseng; Ventura, Neco
The author proposes a hybrid network/host interworking scheme to allow the MN to transition smoothly between different access networks supporting two distinct mobility approaches.
Open Access
Implementation and Performance Evaluation of an NGN prototype using WiMax as an Access Technology
(2012) Malila, Bessie; Ventura, Neco
Telecommunications networks have evolved to IP-based networks, commonly known as Next Generation Networks (NGN). The biggest challenge in providing high quality realtime multimedia applications is achieving a Quality of Service (QoS) consistent with user expectations. One of the key additional factors affecting QoS is the existence of different QoS mechanisms on the heterogeneous technologies used on NGN platforms. This research investigates the techniques used to achieve consistent QoS on network technologies that use different QoS techniques. Numerous proposals for solving the end-to-end QoS problem in IP networks have adopted policy-based management, use of signalling protocols for communicating applications QoS requirements across different Network Elements and QoS provisioning in Network Elements. Such solutions are dependent on the use of traffic classification and knowledge of the QoS requirements of applications and services on the networks. This research identifies the practical difficulties involved in meeting the QoS requirements of network traffic between WiMax and an IP core network. In the work, a solution based on the concept of class-of-service mapping is proposed. In the proposed solution, QoS is implemented on the two networks and the concept of class-of-service mapping is used to integrate the two QoS systems. This essentially provides consistent QoS to applications as they traverse the two network domains and hence meet end-user QoS expectations. The work is evaluated through a NGN prototype to determine the capabilities of the networks to deliver real-time media that meets user expectations.

Browsing by Author "Ventura, Neco"

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