Neco Ventura
University of Cape Town, Electrical Engineering, Faculty Member
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Telecommunication operators have begun moving to an all IP-based Next Generation Network (NGN) to save costs as well as enabling the rapid development of new services. A NGN is defined as a packet-based network where the service... more
Telecommunication operators have begun moving to an all IP-based Next Generation Network (NGN) to save costs as well as enabling the rapid development of new services. A NGN is defined as a packet-based network where the service functionality is independent of the underlying transport techno-logies. The IP Multimedia Subsystem (IMS) is considered to be an intrinsic part of a NGN, and it provides mechanisms such as user authentication, Quality of Service (QoS) and charging. Traditionally, these mechanisms had to be created for each new service that the network operator wished to offer. The ability to reuse these features greatly speeds up the development of new services. This, together with the open protocols being used for the control signalling, is predicted to create a vast increase in the number of services being offered by the network operator as specialised telephony knowledge is no longer needed to develop new services. This increase in the number of potential services on offe...
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Mobile Network Operators provide wireless communication services to their customers using their own network infrastructures. For providers, in particular in low income countries, access to latest network functions to offer 4G/5G services... more
Mobile Network Operators provide wireless communication services to their customers using their own network infrastructures. For providers, in particular in low income countries, access to latest network functions to offer 4G/5G services can be a large burden as this is directly impacted by financial restrictions of operators. Although some network sharing solutions between operators to reduce the total cost of ownership exist in standards and literature, none address specific requirements of the operating environment of low income countries. In our approach, we are exploiting the raising interest in the cloudification of the related infrastructure, namely Network Function Virtualization (NFV) over Software Defined Networks (SDN), to allow each operator in these countries to offer specific network functions as a service in a federation in order to share them and to increase their revenue. Initial results are presented based on the development of a commercial toolkit (OpenSDNCore) and a federated testbed research project (TRESCIMO). As a result, we define the notion of a Mobile Federated Network Operator (MFNO) and provide an analysis of the underlying requirements for such a use case and potential approaches to address them.
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This paper investigate the effect of using heterogeneous mobile terminals (e.g. single-mode, dual-mode, triple-mode, etc.) on call blocking and call dropping probabilities in next generation wireless networks (NGWN). We develop an... more
This paper investigate the effect of using heterogeneous mobile terminals (e.g. single-mode, dual-mode, triple-mode, etc.) on call blocking and call dropping probabilities in next generation wireless networks (NGWN). We develop an analytical model for heterogeneous mobile terminals in NGWN. Using a two-class three-RAT heterogeneous wireless network as an example, the effect of using heterogeneous terminals in the network is evaluated.
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This paper examines an AAL2 signalling protocol in a hybrid ATM/AAL2 network. After an overview of AAL2 signalling is given, the important issues relating to AAL2 signalling are discussed. These issues include the independence between ATM... more
This paper examines an AAL2 signalling protocol in a hybrid ATM/AAL2 network. After an overview of AAL2 signalling is given, the important issues relating to AAL2 signalling are discussed. These issues include the independence between ATM signalling and AAL2 signalling, the choice of which AAL type to utilise in transporting the AAL2 signalling messages as well as the importance of
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— Dense deployment of Small Cell Access Networks (SCAN) at street level has generally been accepted as a solution to improve capacity, coverage and reduce operational expenses in 5G access networks. This deployment strategy necessitates... more
— Dense deployment of Small Cell Access Networks (SCAN) at street level has generally been accepted as a solution to improve capacity, coverage and reduce operational expenses in 5G access networks. This deployment strategy necessitates new cost-effective, high capacity, scalable and flexible backhaul solutions especially in urban environments where traditional solutions, such as fiber and Digital Subscriber Line (DSL) are too expensive and time consuming to deploy. Traditional microwave solutions have capacity and coverage limitations. The new SCAN backhaul systems must have Non-Line-of-Sight (NLOS) and Self-Organizing-Network (SON) capabilities to address the coverage and cost problems. In earlier work we proposed a NLOS Small Cell Backhaul (SCB) system based on diffracted signals where Cognitive Radio Technology (CRT) is proposed to add intelligence to the radio devices, giving the system SON capabilities expected of 5G systems. NLOS operation and Millimeter Wave (mmW) technology are proposed to address the coverage and capacity problems respectively. In this paper experimental results of NLOS radio link and QoS performance measurements for a prototype 17GHZ radio system designed for use as a SCB system are presented. The system addresses the cost problem by using unlicensed spectrum bands and diffracted signals to enable NLOS operation, thus addressing the street level to roof top backhaul coverage problem. The results obtained show that NLOS links that meet the radio and QoS performance requirements of small cell backhaul links can be established in an urban canyon type of environment.
—WLAN offloading has been identified as a novel solution to leverage the channel capacity crunch over the cellular networks. However, this solution does not consider the congestion states of the target access network and the method of... more
—WLAN offloading has been identified as a novel solution to leverage the channel capacity crunch over the cellular networks. However, this solution does not consider the congestion states of the target access network and the method of selecting the best access for offloading. To assist the User Equipment(UE) with the discovery and selection of candidate access network for offloading, 3GPP in Release 10 introduce the Access Network Discovery and Selection Function (ANDSF), which contains preconfigured intersystem mobility and routing policies that can guide the UE to discover and select available access network for handover. The current ANDSF however, cannot make discovery and selection policies which reflect the current state of the available access networks. This can lead to the selection of unavailable or inappropriate access network for offloading. In this paper, we propose a scheme which incorporates a Network Event Reporting Function (NERF) at access network level, and enhancements to the ANDSF. The scheme obtains dynamic characteristics of the access networks, which are used as input to a Multi attribute decision making (MADM) module in the ANDSF to update the statically configured mobility and routing policies provided to the UE for access selection. The scheme provides the best access network for data offloading.
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One of the major challenges in mobile wireless ATM (WATM) networks is to support high speed ATM services like real time multimedia applications with stringent Quality of Service (QoS) requirements. To support these broadband applications... more
One of the major challenges in mobile wireless ATM (WATM) networks is to support high speed ATM services like real time multimedia applications with stringent Quality of Service (QoS) requirements. To support these broadband applications with mobile services, the WATM networks must cater for the rerouting of the connections during inter-cluster handoff so as to yield path optimization of new routes. In existing handoff techniques, a two-phase handoff protocol has been proposed; path extension followed by the path optimization of the new connection. These current handoff techniques result in a large signaling overhead causing handoff latency due to both path extension and optimization. We are now proposing a new inter-cluster handoff technique for real time applications based on the sharing of information at the cluster boundaries so that only intra-cluster handoff is invoked followed by path optimization. Both analytical and simulation models are presented to evaluate the overall system performance in terms of wired link resources and the inter-cluster handoff processing overhead. Results show a significant saving in the allocated virtual channels and a very low inter-cluster handoff processing load.
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In a saturating telecommunications marketplace network operators want to rapidly deploy services with minimum capital investment, while maximizing on revenue from service usage by customers. One way to achieve this is to create interfaces... more
In a saturating telecommunications marketplace network operators want to rapidly deploy services with minimum capital investment, while maximizing on revenue from service usage by customers. One way to achieve this is to create interfaces for 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
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In recent years the volume of spam in the Internet has far surpassed legitimate email. Marketers, fraudsters and political parties enjoy positive returns due to the large number of messages that can be transmitted at very low costs.... more
In recent years the volume of spam in the Internet has far surpassed legitimate email. Marketers, fraudsters and political parties enjoy positive returns due to the large number of messages that can be transmitted at very low costs. Unfortunately there is an emerging trend that spam is now also being transmitted via instant messaging and voice calls. This is a
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... A sustainable business case for the private network operator to realize return on investment (ROI) Wide variety of content, locally-relevant IPTV content and advertising, eg dissemination of e-Services information (e-Health,... more
... A sustainable business case for the private network operator to realize return on investment (ROI) Wide variety of content, locally-relevant IPTV content and advertising, eg dissemination of e-Services information (e-Health, e-Education, e-Farming, e-Skills etc.) Deploying ...
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The adoption of the IP Multimedia Subsystem (IMS) has faced a number of challenges. Furthermore, countries with developing infrastructure face additional difficulties. It is important for such countries to overcome these obstacles in... more
The adoption of the IP Multimedia Subsystem (IMS) has faced a number of challenges. Furthermore, countries with developing infrastructure face additional difficulties. It is important for such countries to overcome these obstacles in order to adopt Next Generation Network (NGN) architectures and compete globally with operators offering IMS services. Funding the deployment of NGNs is a major hurdle for developing
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One of the serious challenges, which hamper application of multiple-input multiple-output (MIMO) multicarrier (MC) transmission systems in the cognitive radio (CR) environments, is the synthesis of reliable pilot signals, which can be... more
One of the serious challenges, which hamper application of multiple-input multiple-output (MIMO) multicarrier (MC) transmission systems in the cognitive radio (CR) environments, is the synthesis of reliable pilot signals, which can be used for the CR channel sounding. This paper addresses design of the optimal pilot pattern for MIMO-MC CRs. The principal novelty of this work in contrast to the previous ones is that the proposed solution is optimal from both performance and receiver complexity standpoint. To be more specific, we consider pilot sequence precoding, which leads to the best channel estimation accuracy, ensured by the optimal pilot power distribution and joint estimation of the second-order channel response statistics.
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Research Interests: Distributed Computing, Modeling, System Design, Communication System, Computer Communications, and 15 moreAntenna, Broadband Wireless Access, Adaptive System, Analytical Solution, Antena, Upper Bound, Input Output, Spectral Efficiency, Multipath, Signal to Noise Ratio, Electrical And Electronic Engineering, Orthogonal Frequency Division Multiplexing, Weak solution, Minimum Mean Square Error, and Channel State Information
ABSTRACT
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This paper presents a gap mechanism for evaluating the performance of three energy minimisation models in wireless multicast networks. The first model is the existing coded packet that is based on simulation technique. The second and the... more
This paper presents a gap mechanism for evaluating the performance of three energy minimisation models in wireless multicast networks. The first model is the existing coded packet that is based on simulation technique. The second and the third models are the recently proposed techniques that are based on data envelopment analysis (DEA) methodology. The input-oriented Banker, Chanes and Cooper (BCC) and Chanes, Cooper and Rhodes (CCR) approaches are considered for DEA model development. It is fund that the proposed input-oriented BCC and CCR models provide better energy gap in wireless networks compared to the coded packet model.
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This work investigates the performance of interference cancellation based detectors in MIMO OFDM systems. It compares linear estimators with interference cancellation in Rayleigh fading channel. Interference cancellation greatly improves... more
This work investigates the performance of interference cancellation based detectors in MIMO OFDM systems. It compares linear estimators with interference cancellation in Rayleigh fading channel. Interference cancellation greatly improves bit error rate (BER) of a linear estimator. The performance of successive, parallel and hybrid interference cancellation methods is further investigated in case of the ill-conditioned channel matrix. The paper investigates
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ABSTRACT
MIMO-OFDM systems operating in the wireless doubly-selective channels rely on the pilot-assisted transmissions to acquire channel state information. Application of the two-dimensional filtering algorithms to channel estimation in the MIMO... more
MIMO-OFDM systems operating in the wireless doubly-selective channels rely on the pilot-assisted transmissions to acquire channel state information. Application of the two-dimensional filtering algorithms to channel estimation in the MIMO configurations is challenging due to the complexity considerations. Furthermore, different pilot structures employed in different spatial links necessitate development of scalable and reconfigurable estimator structures. The estimation scheme should also
Research Interests: Statistical Analysis, OFDM, MIMO, Channel Estimation, Mean square error, and 12 moreAdaptive Filter, Adaptive Filters, Robustness, TRANSMITTERS, Communication Complexity, Multipath, Bandwidth, Multiple Input Multiple Output, Transceivers, Channel State Information, Robust estimator, and OFDM modulation
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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... more
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 load ed channels. An admission control
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Spatially multiplexed multiple-input-multiple-output orthogonal frequency division multiplexing (SM-MIMO-OFDM) systems are expected to provide a considerable increase of transmission capacity paving the way for the next generation... more
Spatially multiplexed multiple-input-multiple-output orthogonal frequency division multiplexing (SM-MIMO-OFDM) systems are expected to provide a considerable increase of transmission capacity paving the way for the next generation broadband wireless communication standards. Considered MIMO-OFDM receiver performs estimation of the channel state information based on transmission of pilots concurrently with data symbols. The channel estimates are subsequently used for data detection. In this
Research Interests: Probability, OFDM, MIMO, Channel Estimation, Boosting, and 15 morePower allocation, Next Generation, Spatial Multiplexing, Signal to Noise Ratio, Wireless Communication, Channel Capacity, Orthogonal Frequency Division Multiplexing, Probability of Detection, Multiple Input Multiple Output, Minimum Mean Square Error, Channel State Information, Minimum Mean Squared Error, Performance Estimation, Multipath channel, and OFDM modulation
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An AAL2 switch is capable of breaking up AAL2 cells into individual voice packets, where switching is performed based on information presented in the packet headers as well as the ATM cell header. Since an AAL2 switch comprises... more
An AAL2 switch is capable of breaking up AAL2 cells into individual voice packets, where switching is performed based on information presented in the packet headers as well as the ATM cell header. Since an AAL2 switch comprises segmentation and reassembly units to convert cells to packets, and vice versa, the performance of such a switch is heavily dependent on the efficiency of the underlying AAL2 technology. This paper discusses the performance of an AAL2 switching node that was implemented on the Washington University Gigabit Switch. We present a series of novel tests that lead to verification of the switch's correct operation and allow several important performance results to be deduced.