Simeon Miteff | University of the Witwatersrand (original) (raw)

Papers by Simeon Miteff

Research paper thumbnail of Teaching the Theory of Estimation and Detection via a GSM Radio Interface Simulation

A new way to teach advanced undergraduate and graduate students the theory of estimation and dete... more A new way to teach advanced undergraduate and graduate students the theory of estimation and detection is described. The paper shows that the global system mobile (GSM) radio interface is well suited to the teaching of estimation and detection theory because it entails the understanding and application of several concepts within estimation and detection, as well as information theory, signal processing, and radio-wave propagation. With GSM now a mature system with specifications available in the public domain, the students created an open-source (OS) GSM simulator, including all four modulation and coding schemes (MCS 1,2,3,4) with puncturing, a channel estimator, a minimum phase prefilter, a Max log maximum a posteriori probability (MAP) equalizer, and a convolutional decoder. Studying and understanding the theory of estimation and detection is now possible by creating algorithms for the simulator and evaluating the impact of the algorithm on the GSM block error rate (BLER). Several experiments that are possible with the simulator are described. Africa, where he provides Unix support for researchers. His interests include open-source software and the Linux operating system.

Research paper thumbnail of Remotely sensed phenology for mapping biomes and vegetation functional types

2009 IEEE International Geoscience and Remote Sensing Symposium, 2009

This study used remotely-sensed phenology data derived from Advanced Very High Resolution Radiome... more This study used remotely-sensed phenology data derived from Advanced Very High Resolution Radiometer (AVHRR), in a fully supervised decision-tree classification based on the new biome map of South Africa. The objectives were: (i) to investigate the long-term spatial patterns and inter-annual variability in satellite-derived vegetation phenology in relation to the recently revised biome map and (ii) to identify the phenological attributes that distinguishes between the different biomes. The long term phenometrics gave ecologically-meaningful results which reflect our current understanding of the spatial patterns of production and seasonality of vegetation growth in southern Africa. Regression tree analysis based on remotely-sensed phenometrics performed as good as, or better than, previous climate-based predictors of biome distribution.

Research paper thumbnail of HiTempo: a platform for time-series analysis of remote-sensing satellite data in a high-performance computing environment

International Journal of Remote Sensing, 2012

Course resolution earth observation satellites offer large data sets with daily observations at g... more Course resolution earth observation satellites offer large data sets with daily observations at global scales. These data sets represent a rich resource that, because of the high acquisition rate, allows the application of time-series analysis methods. To research the application of these time-series analysis methods to large data sets, it is necessary to turn to high-performance computing (HPC) resources and

Research paper thumbnail of NFShunt: a Linux firewall with OpenFlow-enabled hardware bypass

Conference on Network Function Virtualization and Software Defined Network (NFV-SDN)

Data-intensive research computing requires the capability to transfer files over long distances a... more Data-intensive research computing requires the capability to transfer files over long distances at high throughput. Stateful firewalls introduce sufficient packet loss to prevent researchers from fully exploiting high bandwidth-delay network links. To work around this challenge, the Science DMZ design trades off stateful packet filtering capability for loss-free forwarding via an ordinary Ethernet switch. We propose a novel extension to the Science DMZ design, which uses an SDN-based firewall. This paper introduces NFShunt, a firewall based on Linux’s Netfilter combined with OpenFlow switching. Implemented as an OpenFlow 1.0 controller coupled to Netfilter’s connection tracking, NFShunt allows the bypass-switching policy to be expressed as part of an iptables firewall rule-set. Our implementation is described in detail, and latency of the control-plane mechanism is reported. TCP throughput and packet loss is shown at various round-trip latencies, with comparisons to pure switching, as well as to a high-end Cisco firewall. The results support reported observations regarding firewall introduced packet-loss, and indicate that the SDN design of NFShunt is a viable approach to enhancing a traditional firewall to meet the performance needs of data-intensive researchers.

Research paper thumbnail of Teaching the Theory of Estimation and Detection via a GSM Radio Interface Simulation

A new way to teach advanced undergraduate and graduate students the theory of estimation and dete... more A new way to teach advanced undergraduate and graduate students the theory of estimation and detection is described. The paper shows that the global system mobile (GSM) radio interface is well suited to the teaching of estimation and detection theory because it entails the understanding and application of several concepts within estimation and detection, as well as information theory, signal processing, and radio-wave propagation. With GSM now a mature system with specifications available in the public domain, the students created an open-source (OS) GSM simulator, including all four modulation and coding schemes (MCS 1,2,3,4) with puncturing, a channel estimator, a minimum phase prefilter, a Max log maximum a posteriori probability (MAP) equalizer, and a convolutional decoder. Studying and understanding the theory of estimation and detection is now possible by creating algorithms for the simulator and evaluating the impact of the algorithm on the GSM block error rate (BLER). Several experiments that are possible with the simulator are described. Africa, where he provides Unix support for researchers. His interests include open-source software and the Linux operating system.

Research paper thumbnail of Remotely sensed phenology for mapping biomes and vegetation functional types

2009 IEEE International Geoscience and Remote Sensing Symposium, 2009

This study used remotely-sensed phenology data derived from Advanced Very High Resolution Radiome... more This study used remotely-sensed phenology data derived from Advanced Very High Resolution Radiometer (AVHRR), in a fully supervised decision-tree classification based on the new biome map of South Africa. The objectives were: (i) to investigate the long-term spatial patterns and inter-annual variability in satellite-derived vegetation phenology in relation to the recently revised biome map and (ii) to identify the phenological attributes that distinguishes between the different biomes. The long term phenometrics gave ecologically-meaningful results which reflect our current understanding of the spatial patterns of production and seasonality of vegetation growth in southern Africa. Regression tree analysis based on remotely-sensed phenometrics performed as good as, or better than, previous climate-based predictors of biome distribution.

Research paper thumbnail of HiTempo: a platform for time-series analysis of remote-sensing satellite data in a high-performance computing environment

International Journal of Remote Sensing, 2012

Course resolution earth observation satellites offer large data sets with daily observations at g... more Course resolution earth observation satellites offer large data sets with daily observations at global scales. These data sets represent a rich resource that, because of the high acquisition rate, allows the application of time-series analysis methods. To research the application of these time-series analysis methods to large data sets, it is necessary to turn to high-performance computing (HPC) resources and

Research paper thumbnail of NFShunt: a Linux firewall with OpenFlow-enabled hardware bypass

Conference on Network Function Virtualization and Software Defined Network (NFV-SDN)

Data-intensive research computing requires the capability to transfer files over long distances a... more Data-intensive research computing requires the capability to transfer files over long distances at high throughput. Stateful firewalls introduce sufficient packet loss to prevent researchers from fully exploiting high bandwidth-delay network links. To work around this challenge, the Science DMZ design trades off stateful packet filtering capability for loss-free forwarding via an ordinary Ethernet switch. We propose a novel extension to the Science DMZ design, which uses an SDN-based firewall. This paper introduces NFShunt, a firewall based on Linux’s Netfilter combined with OpenFlow switching. Implemented as an OpenFlow 1.0 controller coupled to Netfilter’s connection tracking, NFShunt allows the bypass-switching policy to be expressed as part of an iptables firewall rule-set. Our implementation is described in detail, and latency of the control-plane mechanism is reported. TCP throughput and packet loss is shown at various round-trip latencies, with comparisons to pure switching, as well as to a high-end Cisco firewall. The results support reported observations regarding firewall introduced packet-loss, and indicate that the SDN design of NFShunt is a viable approach to enhancing a traditional firewall to meet the performance needs of data-intensive researchers.