Efforts to reduce peak electrical demand has led to the introduction of demand response programs ... more Efforts to reduce peak electrical demand has led to the introduction of demand response programs for residences. Demand response programs allow customers to reduce or shift their electrical consumption from peak periods in response to dynamic prices of electricity. Utility companies broadcasts the prices to the customers who then respond by reducing consumption during peak periods or shift the consumption to off-peak periods. Similarly, direct load control programs entice consumers with special rates or other incentives for allowing the utility to control load (typically air conditioning) for a number of days per year. Both uses require a ubiqituous and cost-effective communication network to allow utilities to communicate with users and appliances. The Radio Data System (RDS) has been identified as one strong candidate technology. However, security concerns arise due to the wireless nature of the communication channel. Source authentication is crucial in demand response to ensure t...
Implementation of electrical demand response (DR) in home devices requires a robust and secure co... more Implementation of electrical demand response (DR) in home devices requires a robust and secure communication channel with which to deliver pricing and event messages. The RBDS network has been identified as a good candidate to deliver messages to DR enabled devices. Through simulations, we show that RBDS can be employed to effectively deliver DR messages. Effective targeting of devices is non-trivial in a broadcast network like RBDS. We propose an addressing scheme to efficiently group devices logically, by location, and individually over RBDS with minimal overhead. We also address the security concerns for DR messages delivered over RBDS by investigating three strong authentication protocols. Simulations show that devices up to 120km can receive authenticated messages with high probability but beyond that, messages experience losses due to larger messages introduced by signatures. ECDSA provides the strongest security but is more computationally expensive than BiBa and HORSE. ii De...
Dynamic Structure DEVS allows one to model systems that under go structural and behavioural chang... more Dynamic Structure DEVS allows one to model systems that under go structural and behavioural changes. Dynamic Structure CD++ is a modelling and simulation tool that allows models to be changed at run time to facilitate accurate modelling of dynamic systems. We model and simulate two different examples of dynamic systems focusing on their dynamic behaviour using DS-CD++.
A broadband slotted bow-tie antenna is presented. The antenna is fed by coplanar waveguide (CPW) ... more A broadband slotted bow-tie antenna is presented. The antenna is fed by coplanar waveguide (CPW) and fabricated on an InP substrate for same chip integration with the promising resonant tunnelling diode (RTD) terahertz (THz) oscillator which has the capability of room temperature operation and with relative high power. The antenna exhibits a very wide bandwidth (return loss S11 < −10 dB) around the design frequency (300 GHz). However, due to the large dielectric constant of the InP substrate, most of the radiation is directed into the substrate. To re-direct the energy into air, a bow tie antenna employing a reflector ground plane underneath a thin substrate of low dielectric constant is presented. Initial simulation results of this technique are reported and experimental validation at lower frequency (17 GHz) shows the feasibility of the concept
In this paper, an informax based source deflation algorithm of the loudspeaker (far-end) signal f... more In this paper, an informax based source deflation algorithm of the loudspeaker (far-end) signal for acoustic echo cancellation is introduced. The aim is to continually model the loudspeaker-environment-enclosure filter even under double-talk and noisy conditions, something the current methods fail to do. The deflation filter is learned using the informax principle where a prior knowledge about the near-end signal's approximate probability density function is required for optimal filter convergence. Simulation results are used to illustrate the performance of the algorithm under double-talk conditions, as well as simulation comparisons to the normalized least-mean-square algorithm for echo cancellation under varying noise conditions with no double-talk
This paper introduces a new point estimation algorithm, with particular focus on coherent noise s... more This paper introduces a new point estimation algorithm, with particular focus on coherent noise suppression, given several measurements of the device under test where it is assumed that 1) the noise is first-order stationery and 2) the device under test is linear and time-invariant. The algorithm exploits the robustness of the Pitman estimator of the Cauchy location parameter through the initial scaling of the test signal by a centred Gaussian variable of predetermined variance. It is illustrated through mathematical derivations and simulation results that the proposed algorithm is more accurate and consistently robust to outliers for different tailed density functions than the conventional methods of sample mean (coherent averaging technique) and sample median search. Keywords—Central limit theorem, Fisher-Cramer Rao, gamma function, Pitman estimator.
This work presents a study of low-cost antennas and communication systems to support the burgeoni... more This work presents a study of low-cost antennas and communication systems to support the burgeoning demand for bandwidth in the next generation wireless communications and networks (5G) and/or Internet of Things (IoT). The work was divided into three different fields all aimed at low-cost solutions of enabling next generation networks (5G) and IoT. The first part of the study involves study of low-cost fabrication of antennas and radio frequency (RF) guided wave structures up to 10 GHz using the thermal transfer printing (TTP) technique on renewable, light weight, flexible and low-cost substrates. The thermal transfer printing method for electronics was characterised from DC to 10 GHz and benchmarked for performance against inkjet printing technique which is an established technique for printed electronics. TTP achieved similar or better read range to inkjet printed radio frequency identification (RFID) antennas that were used in this study. Applications of the TTP method in IoT tak...
In this paper, an independent component analysis (ICA) acoustic echo cancellation (AEC) algorithm... more In this paper, an independent component analysis (ICA) acoustic echo cancellation (AEC) algorithm is introduced where a sliding discrete Fourier transform window is adopted such that there is only one AEC parameter to estimate (reduced computational load), as opposed to thousands of coefficients modeling the room response. Conventional adaptive filtering techniques such as the least mean square (LMS) algorithm often fail under double-talk condition (and excessive noise) due to a corrupted measure of the objective function (i.e. minimization of the error output). Recent study has shown that ICA allows continual adaptation of the AEC parameters, hence it is adopted here as the optimization method of our AEC parameter. Simulation results are used to illustrate the superiority of the proposed algorithm over the LMS methods.
Efforts to reduce peak electrical demand has led to the introduction of demand response programs ... more Efforts to reduce peak electrical demand has led to the introduction of demand response programs for residences. Demand response programs allow customers to reduce or shift their electrical consumption from peak periods in response to dynamic prices of electricity. Utility companies broadcasts the prices to the customers who then respond by reducing consumption during peak periods or shift the consumption to off-peak periods. Similarly, direct load control programs entice consumers with special rates or other incentives for allowing the utility to control load (typically air conditioning) for a number of days per year. Both uses require a ubiqituous and cost-effective communication network to allow utilities to communicate with users and appliances. The Radio Data System (RDS) has been identified as one strong candidate technology. However, security concerns arise due to the wireless nature of the communication channel. Source authentication is crucial in demand response to ensure t...
Implementation of electrical demand response (DR) in home devices requires a robust and secure co... more Implementation of electrical demand response (DR) in home devices requires a robust and secure communication channel with which to deliver pricing and event messages. The RBDS network has been identified as a good candidate to deliver messages to DR enabled devices. Through simulations, we show that RBDS can be employed to effectively deliver DR messages. Effective targeting of devices is non-trivial in a broadcast network like RBDS. We propose an addressing scheme to efficiently group devices logically, by location, and individually over RBDS with minimal overhead. We also address the security concerns for DR messages delivered over RBDS by investigating three strong authentication protocols. Simulations show that devices up to 120km can receive authenticated messages with high probability but beyond that, messages experience losses due to larger messages introduced by signatures. ECDSA provides the strongest security but is more computationally expensive than BiBa and HORSE. ii De...
Dynamic Structure DEVS allows one to model systems that under go structural and behavioural chang... more Dynamic Structure DEVS allows one to model systems that under go structural and behavioural changes. Dynamic Structure CD++ is a modelling and simulation tool that allows models to be changed at run time to facilitate accurate modelling of dynamic systems. We model and simulate two different examples of dynamic systems focusing on their dynamic behaviour using DS-CD++.
A broadband slotted bow-tie antenna is presented. The antenna is fed by coplanar waveguide (CPW) ... more A broadband slotted bow-tie antenna is presented. The antenna is fed by coplanar waveguide (CPW) and fabricated on an InP substrate for same chip integration with the promising resonant tunnelling diode (RTD) terahertz (THz) oscillator which has the capability of room temperature operation and with relative high power. The antenna exhibits a very wide bandwidth (return loss S11 < −10 dB) around the design frequency (300 GHz). However, due to the large dielectric constant of the InP substrate, most of the radiation is directed into the substrate. To re-direct the energy into air, a bow tie antenna employing a reflector ground plane underneath a thin substrate of low dielectric constant is presented. Initial simulation results of this technique are reported and experimental validation at lower frequency (17 GHz) shows the feasibility of the concept
In this paper, an informax based source deflation algorithm of the loudspeaker (far-end) signal f... more In this paper, an informax based source deflation algorithm of the loudspeaker (far-end) signal for acoustic echo cancellation is introduced. The aim is to continually model the loudspeaker-environment-enclosure filter even under double-talk and noisy conditions, something the current methods fail to do. The deflation filter is learned using the informax principle where a prior knowledge about the near-end signal's approximate probability density function is required for optimal filter convergence. Simulation results are used to illustrate the performance of the algorithm under double-talk conditions, as well as simulation comparisons to the normalized least-mean-square algorithm for echo cancellation under varying noise conditions with no double-talk
This paper introduces a new point estimation algorithm, with particular focus on coherent noise s... more This paper introduces a new point estimation algorithm, with particular focus on coherent noise suppression, given several measurements of the device under test where it is assumed that 1) the noise is first-order stationery and 2) the device under test is linear and time-invariant. The algorithm exploits the robustness of the Pitman estimator of the Cauchy location parameter through the initial scaling of the test signal by a centred Gaussian variable of predetermined variance. It is illustrated through mathematical derivations and simulation results that the proposed algorithm is more accurate and consistently robust to outliers for different tailed density functions than the conventional methods of sample mean (coherent averaging technique) and sample median search. Keywords—Central limit theorem, Fisher-Cramer Rao, gamma function, Pitman estimator.
This work presents a study of low-cost antennas and communication systems to support the burgeoni... more This work presents a study of low-cost antennas and communication systems to support the burgeoning demand for bandwidth in the next generation wireless communications and networks (5G) and/or Internet of Things (IoT). The work was divided into three different fields all aimed at low-cost solutions of enabling next generation networks (5G) and IoT. The first part of the study involves study of low-cost fabrication of antennas and radio frequency (RF) guided wave structures up to 10 GHz using the thermal transfer printing (TTP) technique on renewable, light weight, flexible and low-cost substrates. The thermal transfer printing method for electronics was characterised from DC to 10 GHz and benchmarked for performance against inkjet printing technique which is an established technique for printed electronics. TTP achieved similar or better read range to inkjet printed radio frequency identification (RFID) antennas that were used in this study. Applications of the TTP method in IoT tak...
In this paper, an independent component analysis (ICA) acoustic echo cancellation (AEC) algorithm... more In this paper, an independent component analysis (ICA) acoustic echo cancellation (AEC) algorithm is introduced where a sliding discrete Fourier transform window is adopted such that there is only one AEC parameter to estimate (reduced computational load), as opposed to thousands of coefficients modeling the room response. Conventional adaptive filtering techniques such as the least mean square (LMS) algorithm often fail under double-talk condition (and excessive noise) due to a corrupted measure of the objective function (i.e. minimization of the error output). Recent study has shown that ICA allows continual adaptation of the AEC parameters, hence it is adopted here as the optimization method of our AEC parameter. Simulation results are used to illustrate the superiority of the proposed algorithm over the LMS methods.
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Papers by Monageng Kgwadi