Phongsak Keeratiwintakorn | King Mongkut's University of Technology North Bangkok (original) (raw)

Papers by Phongsak Keeratiwintakorn

This research aims to develop a prototype of 3-DOF robot that use for pick and place objects with... more This research aims to develop a prototype of 3-DOF robot that use for pick and place objects with high speed movement and low cost to produce, named parallel robot or delta robot. The robot can approach special applications with fast and smooth control. Thus, it is easy to movement in different positions. It is suitable for transporting workpieces or be able to move in various points. The payload can be up to 500 g. In current application, it can be applied to the food manufacturing industry. Therefore, the robot prototype can be used for food industry companies or related industries field. The project has co-operative from both public sector and private sector. The research and development are conducted by the researchers from the public sector. The private sector provides support materials and equipment. After producing a prototype, the test is carried out by the private sector, evaluates the performance and satisfaction of users to use. When the prototype is completed, the privat...

2021 Research, Invention, and Innovation Congress: Innovation Electricals and Electronics (RI2C)

Industrial now a day has become more active in automation system. Both in terms of cost reduction... more Industrial now a day has become more active in automation system. Both in terms of cost reduction, price, human error, quality as well as the introduction of automatic system technology. It able to work with the least manual labor required but quick and efficient. Today, the technology of automation and industrial robots is increasingly playing a role in the industry. It can work for human beings in various fields such as lifting products from production lines, assembly work, packing products. Work with repetitive processes, tasks that require the same quality standards. It can be seen that before the introduction of automation technology. To be used in industrial plants will require a lot of labor. It costs more to hire than automation and industrial robots to work instead of humans. This paper use automation system and industrial robot to sorting the equipment. It focuses on speed, accuracy and efficiency. Digital image processing is used to classify the text on equipment and shape of the equipment.

Telemedicine is a future trend of medical care due to the increasing cost of treatment and the ag... more Telemedicine is a future trend of medical care due to the increasing cost of treatment and the aging of population around the World. Several telecommunication technologies are proposed for transferring medical data between a point of care and a hospital. However, it does not provide full mobility where a patient still needs to be attached with wired monitoring devices. In this paper, we proposed a wireless three-lead electrocardiogram (ECG) device using a mote-based Wireless Sensor Network (WSN) to transfer heart signals from a patient to a personal computer for monitoring and storing. Our proposed device augments the mote-based Telos node and TinyOS. Our device is designed using low-cost, low-power components, and it provides full mobility to a patient by eliminating noise due to patient’s movement. The experiment results show the similarity of the ECG signals between our three-lead wireless ECG device and a 12-lead wired commercial ECG device.

Ecti Con2010 the 2010 Ecti International Confernce on Electrical Engineering Electronics Computer Telecommunications and Information Technology, 2010

ABSTRACT Wireless communication becomes important part of everyday life, and in the future, there... more ABSTRACT Wireless communication becomes important part of everyday life, and in the future, there will be new wireless technologies. Vertical handoff between networks with different wireless network interface becomes so important especially in mobile devices that move at high speed such as vehicles. The vertical handoff is required for a vehicle to connect to different wireless networks for different purpose. For example, vehicles may connect to cellular network to send short messages such as news or email, and may connect to short range networks to acquire some localized information. In this paper, we investigate the possibility and the performance of using GSM/GPRS module as an interface to cellular networks and Zigbee module as an interface to short range networks. In our experiments, we set up both soft and hard handoff scenario to measure the packet round trip time and delay. From the results, it shows that the packet round trip time (RTT) in GPRS networks on the average is around 1 - 2.5 seconds and in Zigbee network is less than 100 msec. In case of a hard handoff, mobile device needs to prepare for a connection to attach to networks before transferring data. From the results, the network attach time in GPRS network on the average is around 4.5 - 5 seconds while in Zigbee network is less than 10 msec.

Vehicle communication provide useful information from information networks to vehicle such as roa... more Vehicle communication provide useful information from information networks to vehicle such as road traffic, car accident and road construction to avoid delays and accidents. It also provide useful information from vehicle to information networks for use in road traffic calculation and accident warning, and especially help in better traffic management for Intelligent Transportation System. In this paper, we overview the ubiquitous communication as it is probably the next generation communication for vehicles to communicate seamlessly over different wireless technologies. We propose the prototypes of the road side equipment (RSE) and the on-board equipment (OBE) for communication between vehicles and road side stations based on IEEE 802.15.4 and Zigbee wireless technologies. The experiments and results of the prototype under various vehicle operation tests are shown. The results have shown the possibility of using IEEE 802.15.4 and Zigbee as the communication protocol and device for vehicle-to-vehicle (V2V) and vehicle-toinfrastructure (V2I) communications.

The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2002

Location aware services are becoming attractive with the deployment of next generation wireless n... more Location aware services are becoming attractive with the deployment of next generation wireless networks and broadband multimedia wireless networks especially in indoor and campus areas. To provide location aware services, obtaining the position of a user accurately is important. While it is possible to deploy additional infrastructure for this purpose, using existing communications infrastructure is preferred for cost reasons. Because of technical restrictions, location fingerprinting schemes are the most promising. In this paper we are presenting a systematic study of the performance/tradeoff and deployment issues. In this paper we present some experimental results towards such a systematic study and discuss some issues related to the indoor positioning problem. I.

IEEE Transactions on Magnetics, 2015

ABSTRACT Bit-patterned media recording (BPMR) is the promising technology to enhance an areal den... more ABSTRACT Bit-patterned media recording (BPMR) is the promising technology to enhance an areal density (AD) of hard disk drives beyond the limit imposed by the current perpendicular recording technology. Practically, a T -spaced equalizer is employed in a conventional (symbol-rate) BPMR system to shape the overall channel response to a target response before performing the data detection process, where T is a bit period. Because the BPMR channel response has a large excess bandwidth, we then propose to use a fractionallyspaced equalizer (FSE) in the oversampled BPMR system so as to improve the system performance. A design of the FSE and its corresponding one-dimensional and two-dimensional targets will be given. Thus, we compare the performance of the oversampled BPMR system with the symbol-rate one. Results indicate that the oversampled system performs better than the symbol-rate one in terms of bit-error rate (BER). Specifically, at BER = 10−4 and no media noise, the oversampled system can provide about 1 dB gain at the ADs of 2.0 and 2.5 terabit per square inch (Tb/in2) over the symbol-rate system. In addition, we found that the oversampled system is more robust to media noise than the symbol-rate one.

Wireless communication becomes important part of everyday life, and in the future, there will be ... more Wireless communication becomes important part of everyday life, and in the future, there will be new wireless technologies. Vertical handoff between networks with different wireless network interface becomes so important especially in mobile devices that move at high speed such as vehicles. The vertical handoff is required for a vehicle to connect to different wireless networks for different purpose. For example, vehicles may connect to cellular network to send short messages such as news or email, and may connect to short range networks to acquire some localized information. In this paper, we investigate the possibility and the performance of using GSM/GPRS module as an interface to cellular networks and Zigbee module as an interface to short range networks. In our experiments, we set up both soft and hard handoff scenario to measure the packet round trip time and delay. From the results, it shows that the packet round trip time (RTT) in GPRS networks on the average is around 1 - 2...

A study on robustness of location determination techniques using wireless sensor network (WSN) is... more A study on robustness of location determination techniques using wireless sensor network (WSN) is presented in this manuscript. The location estimation technique used by the wireless sensor network is based on location fingerprinting technique. Theoretically, the robustness of the location estimation depends on the availability of the number of sensor nodes in the system. The degradation of location precision performance is proportional to the decrement of number of nodes in the WSN. The analysis of this study is derived from the real deployment and measurement of a test bed in a building that is deployed with TelosB mote based wireless sensor network. The preliminary results suggest that an outage of a large number of sensor nodes has detrimental effect on the performance of the location determination system. In our case, the WSN with 17 nodes yields 82% of locations accurately estimated within 4 meters. After the outage occurred in the network and the number of sensor nodes was re...

2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011

In bit-patterned media recording (BPMR) channels at ultra high areal densities, the inter-track i... more In bit-patterned media recording (BPMR) channels at ultra high areal densities, the inter-track interference (ITI) is extremely severe, which significantly degrades the system performance. The partial-response maximum-likelihood (PRML) technique that uses a one-dimensional (1D) partial response target might not be able to cope with this severe ITI, especially in the presence of media noise and track mis-registration (TMR). This paper

Vehicular Technology, IEEE Conference, 2004

Energy sayings are extremely important in wireless networks where devices operate using battery p... more Energy sayings are extremely important in wireless networks where devices operate using battery power. Security in wireless networks is also becoming crucial with the deployment of wireless local area networks in hot spot areas, organizations, hospitals and so on. Security protocols depend on energy consuming operations that occur in the cryptographic primitives used in the protocols. It has been observed

Proceedings of the 2003 International Conference on Machine Learning and Cybernetics (IEEE Cat. No.03EX693), 2003

SMC'03 Conference Proceedings. 2003 IEEE International Conference on Systems, Man and Cybernetics. Conference Theme - System Security and Assurance (Cat. No.03CH37483), 2003

Rapid advances in consumer electronics have led to the anomaly that consumer off the shelf (COTS)... more Rapid advances in consumer electronics have led to the anomaly that consumer off the shelf (COTS) gaming hardware and software now provide better interactive graphics than military and other specialized systems costing orders of magnitude more. UTSAF is bridging software written to take advantage of the power of gaming systems by allowing them to participate in distributed simulations with military simulators such as OneSAF which use the DIS protocol. UTSAF parses DIS PDUs and uses the information gained to control entities within the Unreal game engine using the Game-Bots modification. This paper describes the advantages of game engine based simulation and the UTSAF bridging and control architecture. Our main contribution is to build a simulation bridge that enables affordable highquality 3-D viewers for military simulations.

2008 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008

A location and tracking system becomes very important to our future world of pervasive computing,... more A location and tracking system becomes very important to our future world of pervasive computing, where information is all around us. Location is one of the most needed information for emerging and future applications. Since the public use of GPS satellite is allowed, several state-of-the-art devices become part of our life, e.g. a car navigator and a mobile phone with a built-in GPS receiver. However, location information for indoor environments is still very limited. Several techniques are proposed to get location information in buildings such as using a radio signal triangulation, a radio signal (beacon) emitter, or signal fingerprinting. Using Radio Frequency Identification (RFID) tags is a new way of giving location information to users. Due to its passive communication circuit, RFID tags can be embedded almost anywhere without an energy source. The tags stores location information and gives it to any reader that is within a proximity range which can be up to 10-15 meters for UHF RFID systems. We propose an RFID-based system for navigation in a building for blind people or visually impaired. The system relies on the location information on the tag, a user's destination, and a routing server where the shortest route from the user's current location to the destination. The navigation device communicates with the routing server using GPRS networks. We build a prototype based on our design and show some results. We found that there are some delay problems in the devices which are the communication delay due to the cold start cycle of a GPRS modem and the voice delay due to the file transfer delay from a MMC module.

2009 6th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2009

Thermal asperity (TA) causes a crucial problem in magnetic recording systems because it can disto... more Thermal asperity (TA) causes a crucial problem in magnetic recording systems because it can distort the readback signal to the extent of causing possible sector read failure. This problem becomes more severe in perpendicular recording channels because these channels contain a d.c. component. This paper presents a novel TA suppression method by use of a bandpass filter. We also investigate the effect of different bandpass filters for TA suppression. Results indicate that the proposed TA suppression method using a bandpass filter polynomial G(D) = (1+D) 2 (1-D) yields lower bit-error rate than the existing ones, and is robust to large peak TA amplitudes.

Lecture Notes in Computer Science, 2004

Energy efficiency has been an important factor in protocol design in wireless networks where smal... more Energy efficiency has been an important factor in protocol design in wireless networks where small handheld wireless devices rely solely on battery power. Security is also of great concern in wireless networks. Several security protocols adapted from wired networks have been used in wireless networks to provide identity authentication. Security protocols could contribute significantly to energy consumption, especially authentication protocols such as Wireless Transport Layer Security (WTLS) or Transport Layer Security (TLS) Handshake protocol that are based on computationally intensive public key cryptography. There have been many efforts trying to reduce cryptographic load and energy consumption at wireless devices. Some are complicated and others may not comply with existing WTLS/TLS standards. In this paper, we propose a simple variant of TLS Handshake protocol for mutual authentication and key exchange, which reduces energy consumption in wireless devices. The proposed protocol uses RSA and ECC algorithms differently to make the Handshake protocol more energy efficient. With our proposed protocol, we can save about 25% compared to 1024-bit RSA or 70% compared to 163-bit ECC Handshake protocol. Our proposed protocol can also be easily integrated into the standard WTLS protocol with small modification.

2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011

IEEE 802.16 or WiMAX is the communication technology which has been designed to support high-spee... more IEEE 802.16 or WiMAX is the communication technology which has been designed to support high-speed data communication in a wide area for multimedia applications. Thus, there is a need to provide a guaranteed quality of service (QoS) for such multimedia applications while maintaining the overall network performance. This research proposes a scheduling algorithm to improve the network latency in Coordinated Distributed Scheduling approach by adjusting the transmission holdoff exponent to align with the data priority. The holdoff exponent is adaptively adjusted according to node state information to increase transmission opportunity that could reduce average data transfer delay. To demonstrate the performance of the proposed method, we use NCTU-ns simulation with a mesh network topology and multimedia traffic sources such as Voice over IP (VoIP) and real-time video traffic. The results have shown the improvement using the proposed method over a traditional static holdoff exponent method as defined in IEEE 802.16 standard, especially in the network with dense traffic.

The 8th Electrical Engineering/ Electronics, Computer, Telecommunications and Information Technology (ECTI) Association of Thailand - Conference 2011, 2011

ABSTRACT th, phongsakk@kmutnb .ac.th Abstract -This paper focuses on Ad Hoc routing problems on I... more ABSTRACT th, phongsakk@kmutnb .ac.th Abstract -This paper focuses on Ad Hoc routing problems on IEEE 802.15.4 in which nodes' speeds and courses are different. The objective is to optimize the performance of the proactive OLSR routing protocol in terms of key metrics for real time services -End-to-End Delay and Throughput - within the selected stable-connectin g route, in terms of the number of link disconnection during a unit of time. The fuzzy heuristic probability is used as the key for routing metric. For validation purposes, the protocol is applied to compare to conventional OLSR algorithm, in terms of the minimum hop, and the fuzzy routing metric. Simulations are evaluated with focusing on the constant packet traffic within the realistic­ road mobility scenario. The simulation results show that the proposed algorithm approaches the significant performance improvement of the scenarios and metrics of interest. The contribution for this routing is for solving inter-vehicle communications, or V ANET routing problems.

2008 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008

This research aims to develop a prototype of 3-DOF robot that use for pick and place objects with... more This research aims to develop a prototype of 3-DOF robot that use for pick and place objects with high speed movement and low cost to produce, named parallel robot or delta robot. The robot can approach special applications with fast and smooth control. Thus, it is easy to movement in different positions. It is suitable for transporting workpieces or be able to move in various points. The payload can be up to 500 g. In current application, it can be applied to the food manufacturing industry. Therefore, the robot prototype can be used for food industry companies or related industries field. The project has co-operative from both public sector and private sector. The research and development are conducted by the researchers from the public sector. The private sector provides support materials and equipment. After producing a prototype, the test is carried out by the private sector, evaluates the performance and satisfaction of users to use. When the prototype is completed, the privat...

2021 Research, Invention, and Innovation Congress: Innovation Electricals and Electronics (RI2C)

Industrial now a day has become more active in automation system. Both in terms of cost reduction... more Industrial now a day has become more active in automation system. Both in terms of cost reduction, price, human error, quality as well as the introduction of automatic system technology. It able to work with the least manual labor required but quick and efficient. Today, the technology of automation and industrial robots is increasingly playing a role in the industry. It can work for human beings in various fields such as lifting products from production lines, assembly work, packing products. Work with repetitive processes, tasks that require the same quality standards. It can be seen that before the introduction of automation technology. To be used in industrial plants will require a lot of labor. It costs more to hire than automation and industrial robots to work instead of humans. This paper use automation system and industrial robot to sorting the equipment. It focuses on speed, accuracy and efficiency. Digital image processing is used to classify the text on equipment and shape of the equipment.

Telemedicine is a future trend of medical care due to the increasing cost of treatment and the ag... more Telemedicine is a future trend of medical care due to the increasing cost of treatment and the aging of population around the World. Several telecommunication technologies are proposed for transferring medical data between a point of care and a hospital. However, it does not provide full mobility where a patient still needs to be attached with wired monitoring devices. In this paper, we proposed a wireless three-lead electrocardiogram (ECG) device using a mote-based Wireless Sensor Network (WSN) to transfer heart signals from a patient to a personal computer for monitoring and storing. Our proposed device augments the mote-based Telos node and TinyOS. Our device is designed using low-cost, low-power components, and it provides full mobility to a patient by eliminating noise due to patient’s movement. The experiment results show the similarity of the ECG signals between our three-lead wireless ECG device and a 12-lead wired commercial ECG device.

Ecti Con2010 the 2010 Ecti International Confernce on Electrical Engineering Electronics Computer Telecommunications and Information Technology, 2010

ABSTRACT Wireless communication becomes important part of everyday life, and in the future, there... more ABSTRACT Wireless communication becomes important part of everyday life, and in the future, there will be new wireless technologies. Vertical handoff between networks with different wireless network interface becomes so important especially in mobile devices that move at high speed such as vehicles. The vertical handoff is required for a vehicle to connect to different wireless networks for different purpose. For example, vehicles may connect to cellular network to send short messages such as news or email, and may connect to short range networks to acquire some localized information. In this paper, we investigate the possibility and the performance of using GSM/GPRS module as an interface to cellular networks and Zigbee module as an interface to short range networks. In our experiments, we set up both soft and hard handoff scenario to measure the packet round trip time and delay. From the results, it shows that the packet round trip time (RTT) in GPRS networks on the average is around 1 - 2.5 seconds and in Zigbee network is less than 100 msec. In case of a hard handoff, mobile device needs to prepare for a connection to attach to networks before transferring data. From the results, the network attach time in GPRS network on the average is around 4.5 - 5 seconds while in Zigbee network is less than 10 msec.

Vehicle communication provide useful information from information networks to vehicle such as roa... more Vehicle communication provide useful information from information networks to vehicle such as road traffic, car accident and road construction to avoid delays and accidents. It also provide useful information from vehicle to information networks for use in road traffic calculation and accident warning, and especially help in better traffic management for Intelligent Transportation System. In this paper, we overview the ubiquitous communication as it is probably the next generation communication for vehicles to communicate seamlessly over different wireless technologies. We propose the prototypes of the road side equipment (RSE) and the on-board equipment (OBE) for communication between vehicles and road side stations based on IEEE 802.15.4 and Zigbee wireless technologies. The experiments and results of the prototype under various vehicle operation tests are shown. The results have shown the possibility of using IEEE 802.15.4 and Zigbee as the communication protocol and device for vehicle-to-vehicle (V2V) and vehicle-toinfrastructure (V2I) communications.

The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2002

Location aware services are becoming attractive with the deployment of next generation wireless n... more Location aware services are becoming attractive with the deployment of next generation wireless networks and broadband multimedia wireless networks especially in indoor and campus areas. To provide location aware services, obtaining the position of a user accurately is important. While it is possible to deploy additional infrastructure for this purpose, using existing communications infrastructure is preferred for cost reasons. Because of technical restrictions, location fingerprinting schemes are the most promising. In this paper we are presenting a systematic study of the performance/tradeoff and deployment issues. In this paper we present some experimental results towards such a systematic study and discuss some issues related to the indoor positioning problem. I.

IEEE Transactions on Magnetics, 2015

ABSTRACT Bit-patterned media recording (BPMR) is the promising technology to enhance an areal den... more ABSTRACT Bit-patterned media recording (BPMR) is the promising technology to enhance an areal density (AD) of hard disk drives beyond the limit imposed by the current perpendicular recording technology. Practically, a T -spaced equalizer is employed in a conventional (symbol-rate) BPMR system to shape the overall channel response to a target response before performing the data detection process, where T is a bit period. Because the BPMR channel response has a large excess bandwidth, we then propose to use a fractionallyspaced equalizer (FSE) in the oversampled BPMR system so as to improve the system performance. A design of the FSE and its corresponding one-dimensional and two-dimensional targets will be given. Thus, we compare the performance of the oversampled BPMR system with the symbol-rate one. Results indicate that the oversampled system performs better than the symbol-rate one in terms of bit-error rate (BER). Specifically, at BER = 10−4 and no media noise, the oversampled system can provide about 1 dB gain at the ADs of 2.0 and 2.5 terabit per square inch (Tb/in2) over the symbol-rate system. In addition, we found that the oversampled system is more robust to media noise than the symbol-rate one.

Wireless communication becomes important part of everyday life, and in the future, there will be ... more Wireless communication becomes important part of everyday life, and in the future, there will be new wireless technologies. Vertical handoff between networks with different wireless network interface becomes so important especially in mobile devices that move at high speed such as vehicles. The vertical handoff is required for a vehicle to connect to different wireless networks for different purpose. For example, vehicles may connect to cellular network to send short messages such as news or email, and may connect to short range networks to acquire some localized information. In this paper, we investigate the possibility and the performance of using GSM/GPRS module as an interface to cellular networks and Zigbee module as an interface to short range networks. In our experiments, we set up both soft and hard handoff scenario to measure the packet round trip time and delay. From the results, it shows that the packet round trip time (RTT) in GPRS networks on the average is around 1 - 2...

A study on robustness of location determination techniques using wireless sensor network (WSN) is... more A study on robustness of location determination techniques using wireless sensor network (WSN) is presented in this manuscript. The location estimation technique used by the wireless sensor network is based on location fingerprinting technique. Theoretically, the robustness of the location estimation depends on the availability of the number of sensor nodes in the system. The degradation of location precision performance is proportional to the decrement of number of nodes in the WSN. The analysis of this study is derived from the real deployment and measurement of a test bed in a building that is deployed with TelosB mote based wireless sensor network. The preliminary results suggest that an outage of a large number of sensor nodes has detrimental effect on the performance of the location determination system. In our case, the WSN with 17 nodes yields 82% of locations accurately estimated within 4 meters. After the outage occurred in the network and the number of sensor nodes was re...

2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011

In bit-patterned media recording (BPMR) channels at ultra high areal densities, the inter-track i... more In bit-patterned media recording (BPMR) channels at ultra high areal densities, the inter-track interference (ITI) is extremely severe, which significantly degrades the system performance. The partial-response maximum-likelihood (PRML) technique that uses a one-dimensional (1D) partial response target might not be able to cope with this severe ITI, especially in the presence of media noise and track mis-registration (TMR). This paper

Vehicular Technology, IEEE Conference, 2004

Energy sayings are extremely important in wireless networks where devices operate using battery p... more Energy sayings are extremely important in wireless networks where devices operate using battery power. Security in wireless networks is also becoming crucial with the deployment of wireless local area networks in hot spot areas, organizations, hospitals and so on. Security protocols depend on energy consuming operations that occur in the cryptographic primitives used in the protocols. It has been observed

Proceedings of the 2003 International Conference on Machine Learning and Cybernetics (IEEE Cat. No.03EX693), 2003

SMC'03 Conference Proceedings. 2003 IEEE International Conference on Systems, Man and Cybernetics. Conference Theme - System Security and Assurance (Cat. No.03CH37483), 2003

Rapid advances in consumer electronics have led to the anomaly that consumer off the shelf (COTS)... more Rapid advances in consumer electronics have led to the anomaly that consumer off the shelf (COTS) gaming hardware and software now provide better interactive graphics than military and other specialized systems costing orders of magnitude more. UTSAF is bridging software written to take advantage of the power of gaming systems by allowing them to participate in distributed simulations with military simulators such as OneSAF which use the DIS protocol. UTSAF parses DIS PDUs and uses the information gained to control entities within the Unreal game engine using the Game-Bots modification. This paper describes the advantages of game engine based simulation and the UTSAF bridging and control architecture. Our main contribution is to build a simulation bridge that enables affordable highquality 3-D viewers for military simulations.

2008 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008

A location and tracking system becomes very important to our future world of pervasive computing,... more A location and tracking system becomes very important to our future world of pervasive computing, where information is all around us. Location is one of the most needed information for emerging and future applications. Since the public use of GPS satellite is allowed, several state-of-the-art devices become part of our life, e.g. a car navigator and a mobile phone with a built-in GPS receiver. However, location information for indoor environments is still very limited. Several techniques are proposed to get location information in buildings such as using a radio signal triangulation, a radio signal (beacon) emitter, or signal fingerprinting. Using Radio Frequency Identification (RFID) tags is a new way of giving location information to users. Due to its passive communication circuit, RFID tags can be embedded almost anywhere without an energy source. The tags stores location information and gives it to any reader that is within a proximity range which can be up to 10-15 meters for UHF RFID systems. We propose an RFID-based system for navigation in a building for blind people or visually impaired. The system relies on the location information on the tag, a user's destination, and a routing server where the shortest route from the user's current location to the destination. The navigation device communicates with the routing server using GPRS networks. We build a prototype based on our design and show some results. We found that there are some delay problems in the devices which are the communication delay due to the cold start cycle of a GPRS modem and the voice delay due to the file transfer delay from a MMC module.

2009 6th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2009

Thermal asperity (TA) causes a crucial problem in magnetic recording systems because it can disto... more Thermal asperity (TA) causes a crucial problem in magnetic recording systems because it can distort the readback signal to the extent of causing possible sector read failure. This problem becomes more severe in perpendicular recording channels because these channels contain a d.c. component. This paper presents a novel TA suppression method by use of a bandpass filter. We also investigate the effect of different bandpass filters for TA suppression. Results indicate that the proposed TA suppression method using a bandpass filter polynomial G(D) = (1+D) 2 (1-D) yields lower bit-error rate than the existing ones, and is robust to large peak TA amplitudes.

Lecture Notes in Computer Science, 2004

Energy efficiency has been an important factor in protocol design in wireless networks where smal... more Energy efficiency has been an important factor in protocol design in wireless networks where small handheld wireless devices rely solely on battery power. Security is also of great concern in wireless networks. Several security protocols adapted from wired networks have been used in wireless networks to provide identity authentication. Security protocols could contribute significantly to energy consumption, especially authentication protocols such as Wireless Transport Layer Security (WTLS) or Transport Layer Security (TLS) Handshake protocol that are based on computationally intensive public key cryptography. There have been many efforts trying to reduce cryptographic load and energy consumption at wireless devices. Some are complicated and others may not comply with existing WTLS/TLS standards. In this paper, we propose a simple variant of TLS Handshake protocol for mutual authentication and key exchange, which reduces energy consumption in wireless devices. The proposed protocol uses RSA and ECC algorithms differently to make the Handshake protocol more energy efficient. With our proposed protocol, we can save about 25% compared to 1024-bit RSA or 70% compared to 163-bit ECC Handshake protocol. Our proposed protocol can also be easily integrated into the standard WTLS protocol with small modification.

2011 International Symposium on Intelligent Signal Processing and Communications Systems (ISPACS), 2011

IEEE 802.16 or WiMAX is the communication technology which has been designed to support high-spee... more IEEE 802.16 or WiMAX is the communication technology which has been designed to support high-speed data communication in a wide area for multimedia applications. Thus, there is a need to provide a guaranteed quality of service (QoS) for such multimedia applications while maintaining the overall network performance. This research proposes a scheduling algorithm to improve the network latency in Coordinated Distributed Scheduling approach by adjusting the transmission holdoff exponent to align with the data priority. The holdoff exponent is adaptively adjusted according to node state information to increase transmission opportunity that could reduce average data transfer delay. To demonstrate the performance of the proposed method, we use NCTU-ns simulation with a mesh network topology and multimedia traffic sources such as Voice over IP (VoIP) and real-time video traffic. The results have shown the improvement using the proposed method over a traditional static holdoff exponent method as defined in IEEE 802.16 standard, especially in the network with dense traffic.

The 8th Electrical Engineering/ Electronics, Computer, Telecommunications and Information Technology (ECTI) Association of Thailand - Conference 2011, 2011

ABSTRACT th, phongsakk@kmutnb .ac.th Abstract -This paper focuses on Ad Hoc routing problems on I... more ABSTRACT th, phongsakk@kmutnb .ac.th Abstract -This paper focuses on Ad Hoc routing problems on IEEE 802.15.4 in which nodes' speeds and courses are different. The objective is to optimize the performance of the proactive OLSR routing protocol in terms of key metrics for real time services -End-to-End Delay and Throughput - within the selected stable-connectin g route, in terms of the number of link disconnection during a unit of time. The fuzzy heuristic probability is used as the key for routing metric. For validation purposes, the protocol is applied to compare to conventional OLSR algorithm, in terms of the minimum hop, and the fuzzy routing metric. Simulations are evaluated with focusing on the constant packet traffic within the realistic­ road mobility scenario. The simulation results show that the proposed algorithm approaches the significant performance improvement of the scenarios and metrics of interest. The contribution for this routing is for solving inter-vehicle communications, or V ANET routing problems.

2008 5th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, 2008