• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.299-300
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• 2010

This paper presents experimental results on frequency interference phenomena between WiFi and ZogBee communication systems which are used for wireless communication in a port. When communication systems use a frequency band in a region, it hurts communication reliability. Hence, understanding and analysis on frequency interference phenomena through experiments. With various experiments between WiFi and ZigBee, we find out that 26th channel of ZigBee collides with WiFi communication channels, which is unknown result yet.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.73-83
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• 2010

This paper investigates protocol architecture of a Web-ZigBee gateway for interconnecting TCP/IP-based networks and ZigBee/IEEE802.15.4-based wireless sensor networks. The Web-ZigBee gateway delivers data between the TCP/IP network and the ZigBee network. Since those two networks have different communication protocols, a protocol translation mechanism is needed. Herein, we propose a method to deliver query messages from the Internet to the sensor network and receive data from sensors. The protocol translation is performed in the translation layer that is placed above the two application layers, i.e., the Internet application layer and ZigBee application layer. Among various interfaces, we use CGI programming to take care of translation functions efficiently. The CGI manages query information from a client on the Internet and data from the ZigBee sensor network. Whereas the TCP/IP enabled sensor network overlays two heterogeneous communication protocols, overlaying layers increase the complexity and cost of implementing the sensor network. On the contrary, the sensors in our gateway-based system are not only light (because each communication protocol works independently without overlaying), but also efficient because the translation layer mostly alleviates header overloading.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.980-997
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• 2013

Nowadays, wireless communication has a great advantage in technology. We use wireless devices almost in all expected life such as: entertainment, working and recently in the healthcare area, where Wireless Body Area Networks (WBANs) become a hot topic for researchers and system designers. Recent work on WBANs focus on related issues to communication protocol, especially ZigBee network is fine tuned to meet particular requirements in healthcare area. For example, some papers present real-time patient monitoring via ZigBee communication given the short distance between body sensors and remote devices, while the other work solve the limited coverage problem of Zigbee by designing mechanisms to relay Zigbee data to other types of wire or wireless infrastructure. However, very few of them investigate the scenarios of ZigBee coexisting or integrated with other networks. In this paper, we present the real-time data transmission from ZigBee end devices to Wide Area Network (WAN), Worldwide interoperation for microwave access network (WiMAX) and Long Term Evolution network (LTE). We provide in detail the ZigBee gateway components. Our simulation is conducted by OPNET, we visualize many topology network scenarios in ZigBee hybrid system. The results in simulation show that ZigBee end devices can successfully transmit data in real-time to other network end devices.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.280-285
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• 2008

ZigBee is Low Power and Low Data Rate Wireless Communication protocol. It apply to much Ubiquitous Sensor Network. ZigBee PAN is two type PAN. One is Beacon Enabled PAN, the other is Non Beacon Enabled PAN. To support Low Power in Non Beacon Enabled PAN, End-Device enter Active status at End-Device's wishing time and send a data. So, Router does not know End-Device sends a data time. To solving this problem, Router must always exist to Active status. In this case, Router receive a power supply always in Non Beacon Enabled PAN. But Router does not receive a power supply always, Router can not normal operation, such as Router use a battery. To solve this problem, Router will be support low power. In this paper, we will present Router's Low Power Algorithm. And we suggest 'PAN Time'. Device use 'PAN Time' for PAN synchronous. Router using Low Power Algorithm can be enter to inactive status. So Non Beacon Enabled PAN of Router support the low power mode Therefore Router does not receive a power supply always, Router can normal operation.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.4
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• pp.1-7
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• 2012

This paper proposes a new indoor location recognition system using a ZigBee network and a global positioning system(GPS). The proposed location recognition system applies GPS values that are mainly used for outdoor location recognition, to indoor location recognition; hence the techniques conventionally separated for the indoor and outdoor location recognition are integrated into one location recognition technique. The proposed system recognizes a location using the distance between nodes. Although the distance between nodes can be calculated by measuring the strength of the received ZigBee signals, generally the measured distance is not accurate and has high error rates since the strength of the ZigBee signals is different depending on the distance. In order to reduce the error rate, we have subdivided the output power of the received ZigBee signals into five levels. When a moving node generates a signal, each fixed node transmits the received signal strength and its own GPS information to other nodes, so the moving node can find its own accurate location in terms of the received signals.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.153-161
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• 2007

Stroke is the second most significant disease leading to death in Korea. The conventional therapeutic approach is mainly based on physical training, however, it usually provides the limited degree of recovery of the normal brain function. The electric stimulation therapy is a novel and candidate approach with high potential for stroke recovery. The feasibility was validated by preliminary rat experiments in which the motor function was recovered up to 80% of the normal performance level. It is thought to improve the neural plasticity of the nerve tissues around the diseased area in the stroked brain. However, there are not so much research achievements in the electric stimulation for stroke recovery as for the Parkinson's disease or Epilepsy. This study aims at the developments of a wireless variable pulse generator using ZigBee communication for future implantation into human brain. ZigBee is widely used in wireless personal area network (WPAN) and home network applications due to its low power consumption and simplicity. The developed wireless pulse generator controlled by ZigBee can generate various electric stimulations without any distortion. The electric stimulation includes monophasic and biphasic pulse with the variation of shape parameters, which can affect the level of recovery. The developed system can be used for the telerehabilitation of stroke patient by remote control of brain stimulation via ZigBee and internet. Furthermore, the ZigBee connection used in this study provides the potential neural signal transmission method for the Brain-Machine Interface (BMI).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1164-1172
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• 2007

To solve scalability problem in the ZigBee Network, this paper presents a new mesh routing protocol for ZigBee, called ZigBee Cluster Label (ZiCL). ZiCL divides the ZigBee network into one or more logical clusters and then assigns a unique Cluster Label to each cluster so that it discovers a route of a destination node based on Cluster Label. When a node collects new Cluster Label information of a destination node according to discovery based on Cluster Label, ZiCL encourages nodes with the same Cluster Label to share the information. Consequen tly, it contributes on reducing numerical potential route discoveries and improving network performances such as routing overhead, end-to-end delay, and packet delivery ratio. Simulation results using NS-2 show ZiCL performs well.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.1
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• pp.62-69
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• 2008

In this paper, we proposed the real-time bio-signals monitoring system that is based on the ZigBee wireless sensor network and SIP. This system makes medical team and user easily confirm user's medical state irrelative to their location and time. The communication between medical sensors and the user's end device uses the ZigBee wireless sensor network. The power consumption was decreased because wireless sensor network does not use the Ad-hoc routing protocol but routing protocol that is based on tree structure. Our proposed system includes a wireless user's end device, monitoring console, SIP server and database server. This real-time bio-signals monitoring system makes possible to implement the U-health care services and improving efficiency of medical treatment services.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.217-222
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• 2006

To find a location, GPS has been wildly used. But, it is hard to use in indoor because of very weak signal level. To meet indoor requirements, there have been many studies applying wireless communication networks such as WLAN, UWB and ZigBee. Among these, ZigBee is widely adopted in many WSN applications because it has an advantage of low-power and low-cost. In ZigBee, the RSSI is used as range measurement for ad-hoc network. The RSSI are converted to ranges using the signal attenuation model and these ranges become inputs of positioning methods. The obtained position with RSSI has large error because of its poor accuracy. To overcome this problem, ultrasonic sensors are added in many researches. By measuring the arrival time difference of ZigBee and ultrasound as a range measurement, the precise position can be found. However, there are still many problems: scheduling of beacons to transmit signals in a correct order, addition and synchronization of beacons and low-rate positioning rate. At this paper, an efficient method to solve these problems is proposed. In the proposed method, a node transmits ZigBee and ultrasound signal simultaneously. And beacons find the range with the received signals and send it back to a node with ZigBee. The position is computed in a node with the received ranges. In addition, a new positioning algorithm to solve the risk of the divergence in the linearization method and the singularity problem in the Savarese method is presented. Both static and dynamic experimental results show 0.02m RMS errors with high output rate.

• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.559-564
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• 2008