Chi-Wah Kok | IEEE - Academia.edu (original) (raw)
Papers by Chi-Wah Kok
Proceedings 25th Annual IEEE Conference on Local Computer Networks. LCN 2000, 2000
Page 1. Inter Bridge VLAN Registration Protocol for IP Subnet VLAN Chan Wai Kok 1 , M. Salim Beg ... more Page 1. Inter Bridge VLAN Registration Protocol for IP Subnet VLAN Chan Wai Kok 1 , M. Salim Beg 1 , Narayan Gehlot 2 1 Multimedia University, CyberJaya, Malaysia 2 Bell Labs, Lucent Technologies, Holmdel, NJ, USA wkchan ...
In recent years there has been a rapid increase in the deployment of multimedia streaming applica... more In recent years there has been a rapid increase in the deployment of multimedia streaming applications such as audio and video broadcasting. However, since the best-effort Internet is an unreliable network with a high packet loss rate and nonuniform packet arrival, it does not provide any QoS control. This is crucial to sustain real-time multimedia traffic. To resolve the problem, a multimedia bitrate adaptation flow control for streaming multimedia data over the Internet is proposed. It constantly maintains the buffer at a prescribed capacity, even with bursty network loss, by adapting the multimedia bitrate at the streaming encoder. Simulation results showed that the proposed system with multimedia bitrate adaptation can maintain a higher buffer fill-up rate and larger amount of stored playtime, even in bursty loss period, compared to systems without such an adaptation scheme. A loss packet recovery mechanism and a nonuniform packet arrival mechanism are also proposed to provide error recovery for the system and to deal with the out-of-sequence packet arrival problems. Moreover, a client-based congestion control algorithm able to resolve network congestion problems by adapting the sending rate of the server is presented. Simulation results showed that the proposed client-based congestion control maintains a degree of TCP-friendliness compared to that of the TFRC scheme used in the TCP-friendly congestion control for multimedia traffic. It also provides better resource allocation among different multimedia traffic using a simple weight factor scheme. Next, a novel gateway-assisted congestion control mechanism called “Jitter Detection” (JD) is described. This improves the QoS in multimedia networking by detecting and discarding useless packets that have accumulated a large enough delay jitter. The JD scheme helps to maintain a high bandwidth for packets within the delay jitter tolerance of the multimedia traffic. The JD can further be used to stream layered multimedia multicast traffic over the Internet in order to preserve the base layer traffic with the best-effort when passing through the gateways. Simulation results have shown that the proposed JD scheme can effectively lower the average received packet delay jitter and increase the goodput of the received packets while maintaining the same TCP-friendliness compared to those using RED and DropTail schemes. The results have also shown that the modified JD scheme can provide better quality in terms of PSNR than that of using RED for layered multimedia multicast traffic. Lastly, a “Minimum Redundancy Tree” (MRT) is presented for key distribution in secure multimedia multicast, in order to reduce the update communication overhead for re-keying. (Abstract shortened by UMI.)
Thin Solid Films, 2006
It was recently found that the silicon oxynitride prepared by oxidation of silicon-rich silicon n... more It was recently found that the silicon oxynitride prepared by oxidation of silicon-rich silicon nitride (SRN) has several important features. The high nitrogen and extremely low hydrogen content of this material allows it to have a high dielectric constant and a low trap density. The present work investigates in further detail the electrical reliability of this kind of gate dielectric films by studying the charge trapping and interface state generation induced by constant current stressing. Capacitance–voltage (C–V) measurements indicate that for oxidation temperatures of 850 and 950 °C, the interface trap generation is minimal because of the high nitrogen content at the interface. At a higher oxidation temperature of 1050 °C, a large flatband shift is found for constant current stressing. This observation can be explained by the significant reduction of the nitrogen content and the phase separation effect at this temperature as found by X-ray photoelectron spectroscopy study. In addition to the high nitrogen content, the Si atoms at the interface exist in the form of random bonding to oxygen and nitrogen atoms for samples oxidized at 850 and 950 °C. This structure reduces the interface bonding constraint and results in the low interface trap density. For heavily oxidized samples the trace amount of interface nitrogen atoms exist in the form of a highly constraint SiN4 phase and the interface oxynitride layer is a random mixture of SiO4 and SiN4 phases, which consequently reduces the reliability against high energy electron stressing.
Thin Solid Films
2000 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.00CH37100)
This paper proposed a mixed time and frequency domain ap- proximation algorithm that approximates... more This paper proposed a mixed time and frequency domain ap- proximation algorithm that approximates a high order FIR filter using an IIR filter with lower order. The high order FIR filter is first shortened by an eigenfilter based time do- main equalizer. The equalization residue is approximated in the spectral domain using, for example, the minimax criteria, such that the
2007 IEEE Conference on Electron Devices and Solid-State Circuits, 2007
ABSTRACT The effect of nitrogen implantation on thin lanthanum oxide (La2O3) films grown by e-bea... more ABSTRACT The effect of nitrogen implantation on thin lanthanum oxide (La2O3) films grown by e-beam evaporation are investigated using X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and capacitance-voltage (C-V) measurements. The amount of nitrogen incorporation in the oxide film by plasma immersion ion-implantation (PII) is found to be quite low (about 3% near the surface). However, the introduction of nitrogen atoms into the La2O3 network results in a significant reduction in the oxide traps and leads to a notable improvement in both material and electrical properties of the dielectric.
2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 2000
Microelectronics Journal, 2015
Journal of The Electrochemical Society
ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196), 2001
Channel precoding for an ISI channel is discussed in this paper with emphasis on the complexity o... more Channel precoding for an ISI channel is discussed in this paper with emphasis on the complexity of the equalizer. An FIR filterbank based precoder with a simple decoder utilizing nonuniform sampling is derived. Such a precoder is then generalized to an equalizer constructed from nonconsecutive samples. The latter system is shown to be more computationally efficient. Design examples are presented to demonstrate the derived channel precoders
2005 IEEE Conference on Electron Devices and Solid-State Circuits, 2005
... Topics Quantum Electron. 4 (1998) 930. [5] C. David, D. Wiesmann, R. Germann, F, Horst, BJ Of... more ... Topics Quantum Electron. 4 (1998) 930. [5] C. David, D. Wiesmann, R. Germann, F, Horst, BJ Offerin, R. Beyeler, H..WM Salemink, GL Bona, Microelectron. Eng., 57-58 (2001) 713. ... [9] F. Ay and A. Aydinli, Optical Matter. 26 (2004) 33. [10] MI Alayo, D. Criado, MNP Carreno, L ...
IEEE International Conference on Acoustics Speech and Signal Processing, 1993
Proceedings 25th Annual IEEE Conference on Local Computer Networks. LCN 2000, 2000
Page 1. Inter Bridge VLAN Registration Protocol for IP Subnet VLAN Chan Wai Kok 1 , M. Salim Beg ... more Page 1. Inter Bridge VLAN Registration Protocol for IP Subnet VLAN Chan Wai Kok 1 , M. Salim Beg 1 , Narayan Gehlot 2 1 Multimedia University, CyberJaya, Malaysia 2 Bell Labs, Lucent Technologies, Holmdel, NJ, USA wkchan ...
In recent years there has been a rapid increase in the deployment of multimedia streaming applica... more In recent years there has been a rapid increase in the deployment of multimedia streaming applications such as audio and video broadcasting. However, since the best-effort Internet is an unreliable network with a high packet loss rate and nonuniform packet arrival, it does not provide any QoS control. This is crucial to sustain real-time multimedia traffic. To resolve the problem, a multimedia bitrate adaptation flow control for streaming multimedia data over the Internet is proposed. It constantly maintains the buffer at a prescribed capacity, even with bursty network loss, by adapting the multimedia bitrate at the streaming encoder. Simulation results showed that the proposed system with multimedia bitrate adaptation can maintain a higher buffer fill-up rate and larger amount of stored playtime, even in bursty loss period, compared to systems without such an adaptation scheme. A loss packet recovery mechanism and a nonuniform packet arrival mechanism are also proposed to provide error recovery for the system and to deal with the out-of-sequence packet arrival problems. Moreover, a client-based congestion control algorithm able to resolve network congestion problems by adapting the sending rate of the server is presented. Simulation results showed that the proposed client-based congestion control maintains a degree of TCP-friendliness compared to that of the TFRC scheme used in the TCP-friendly congestion control for multimedia traffic. It also provides better resource allocation among different multimedia traffic using a simple weight factor scheme. Next, a novel gateway-assisted congestion control mechanism called “Jitter Detection” (JD) is described. This improves the QoS in multimedia networking by detecting and discarding useless packets that have accumulated a large enough delay jitter. The JD scheme helps to maintain a high bandwidth for packets within the delay jitter tolerance of the multimedia traffic. The JD can further be used to stream layered multimedia multicast traffic over the Internet in order to preserve the base layer traffic with the best-effort when passing through the gateways. Simulation results have shown that the proposed JD scheme can effectively lower the average received packet delay jitter and increase the goodput of the received packets while maintaining the same TCP-friendliness compared to those using RED and DropTail schemes. The results have also shown that the modified JD scheme can provide better quality in terms of PSNR than that of using RED for layered multimedia multicast traffic. Lastly, a “Minimum Redundancy Tree” (MRT) is presented for key distribution in secure multimedia multicast, in order to reduce the update communication overhead for re-keying. (Abstract shortened by UMI.)
Thin Solid Films, 2006
It was recently found that the silicon oxynitride prepared by oxidation of silicon-rich silicon n... more It was recently found that the silicon oxynitride prepared by oxidation of silicon-rich silicon nitride (SRN) has several important features. The high nitrogen and extremely low hydrogen content of this material allows it to have a high dielectric constant and a low trap density. The present work investigates in further detail the electrical reliability of this kind of gate dielectric films by studying the charge trapping and interface state generation induced by constant current stressing. Capacitance–voltage (C–V) measurements indicate that for oxidation temperatures of 850 and 950 °C, the interface trap generation is minimal because of the high nitrogen content at the interface. At a higher oxidation temperature of 1050 °C, a large flatband shift is found for constant current stressing. This observation can be explained by the significant reduction of the nitrogen content and the phase separation effect at this temperature as found by X-ray photoelectron spectroscopy study. In addition to the high nitrogen content, the Si atoms at the interface exist in the form of random bonding to oxygen and nitrogen atoms for samples oxidized at 850 and 950 °C. This structure reduces the interface bonding constraint and results in the low interface trap density. For heavily oxidized samples the trace amount of interface nitrogen atoms exist in the form of a highly constraint SiN4 phase and the interface oxynitride layer is a random mixture of SiO4 and SiN4 phases, which consequently reduces the reliability against high energy electron stressing.
Thin Solid Films
2000 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.00CH37100)
This paper proposed a mixed time and frequency domain ap- proximation algorithm that approximates... more This paper proposed a mixed time and frequency domain ap- proximation algorithm that approximates a high order FIR filter using an IIR filter with lower order. The high order FIR filter is first shortened by an eigenfilter based time do- main equalizer. The equalization residue is approximated in the spectral domain using, for example, the minimax criteria, such that the
2007 IEEE Conference on Electron Devices and Solid-State Circuits, 2007
ABSTRACT The effect of nitrogen implantation on thin lanthanum oxide (La2O3) films grown by e-bea... more ABSTRACT The effect of nitrogen implantation on thin lanthanum oxide (La2O3) films grown by e-beam evaporation are investigated using X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and capacitance-voltage (C-V) measurements. The amount of nitrogen incorporation in the oxide film by plasma immersion ion-implantation (PII) is found to be quite low (about 3% near the surface). However, the introduction of nitrogen atoms into the La2O3 network results in a significant reduction in the oxide traps and leads to a notable improvement in both material and electrical properties of the dielectric.
2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 2000
Microelectronics Journal, 2015
Journal of The Electrochemical Society
ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196), 2001
Channel precoding for an ISI channel is discussed in this paper with emphasis on the complexity o... more Channel precoding for an ISI channel is discussed in this paper with emphasis on the complexity of the equalizer. An FIR filterbank based precoder with a simple decoder utilizing nonuniform sampling is derived. Such a precoder is then generalized to an equalizer constructed from nonconsecutive samples. The latter system is shown to be more computationally efficient. Design examples are presented to demonstrate the derived channel precoders
2005 IEEE Conference on Electron Devices and Solid-State Circuits, 2005
... Topics Quantum Electron. 4 (1998) 930. [5] C. David, D. Wiesmann, R. Germann, F, Horst, BJ Of... more ... Topics Quantum Electron. 4 (1998) 930. [5] C. David, D. Wiesmann, R. Germann, F, Horst, BJ Offerin, R. Beyeler, H..WM Salemink, GL Bona, Microelectron. Eng., 57-58 (2001) 713. ... [9] F. Ay and A. Aydinli, Optical Matter. 26 (2004) 33. [10] MI Alayo, D. Criado, MNP Carreno, L ...
IEEE International Conference on Acoustics Speech and Signal Processing, 1993