• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1036-1057
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• 2013

Wireless body area network (WBAN) is a promising candidate for future health monitoring system. Nevertheless, the path to mature solutions is still facing a lot of challenges that need to be overcome. Energy efficient scheduling is one of these challenges given the scarcity of available energy of biosensors and the lack of portability. Therefore, researchers from academia, industry and health sectors are working together to realize practical solutions for these challenges. The main difficulty in WBAN is the uncertainty in the state of the monitored system. Intelligent learning approaches such as a Markov Decision Process (MDP) were proposed to tackle this issue. A Markov Decision Process (MDP) is a form of Markov Chain in which the transition matrix depends on the action taken by the decision maker (agent) at each time step. The agent receives a reward, which depends on the action and the state. The goal is to find a function, called a policy, which specifies which action to take in each state, so as to maximize some utility functions (e.g., the mean or expected discounted sum) of the sequence of rewards. A partially Observable Markov Decision Processes (POMDP) is a generalization of Markov decision processes that allows for the incomplete information regarding the state of the system. In this case, the state is not visible to the agent. This has many applications in operations research and artificial intelligence. Due to incomplete knowledge of the system, this uncertainty makes formulating and solving POMDP models mathematically complex and computationally expensive. Limited progress has been made in terms of applying POMPD to real applications. In this paper, we surveyed the existing methods and algorithms for solving POMDP in the general domain and in particular in Wireless body area network (WBAN). In addition, the papers discussed recent real implementation of POMDP on practical problems of WBAN. We believe that this work will provide valuable insights for the newcomers who would like to pursue related research in the domain of WBAN.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.53-64
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• 2009

For a realization of the ubiquitous society, applying IT to vehicle industry has recently been an attractive issue to make wireless communication in body area network possible to everywhere. In this paper, we propose the physical layer symbol structure based on PPM scheme of the IEEE 802.15.4a for the off-body high data rate WBAN system. We propose four symbol structures which is classified according to the number of the chip and whether the channel coding is used or not. We calculate the required SNR through the link budget calculation and the recently proposed off-body WBAN channel environment was applied in the simulation. The results of four systems show that small number of burst's chip enhances the performance and the system is capable to achieve the data rate of 10 Mbps.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1589-1598
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• 2014

To support the WBAN, IEEE 802.15 Task Group 6 announced standardized documents on technical requirements of the PHY and MAC. In the IEEE 802.15.6 MAC protocol, CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) algorithm is performed based on the eight-level priorities according to the type of traffics of the periodic data from medical sensor nodes. Several nodes, which detected the changed bio signals, transmit emergency data at the same time, so latency could be higher than emergency latency and energy consumption will increase. In this thesis, we proposed a CSMA/CA algorithm in WBAN to solve these problems. Simulations are performed using a Castalia based on the OMNeT++ network simulation framework to estimate the performance of the proposed superframe and algorithms. Performance evaluation results show that the packet transmission success rate and energy efficiency are improved by reducing the probability of collision using the proposed MAC protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10A
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• pp.823-829
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• 2011

Recently, wireless body area network (WBAN) has received much attention as an application for the ubiquitous healthcare system. In WBAN, each sensor nodes and a personal base station such as PDA have an energy constraint and computation overhead should be minimized due to node's limited computing power and memory constraint. The reliable data transmission also must be guaranteed because it handles vital signals. In this paper, we propose a systematic network coding scheme for WBAN to reduce the network coding overhead as well as total energy consumption for completion the transmission. We model the proposed scheme using Markov chain. To minimize the total energy consumption for completing the data transmission, we made the problem as a minimization problem and find an optimal solution. Our simulation result shows that large amount of energy reduction is achieved by proposed systematic network coding. Also, the proposed scheme reduces the computational overhead of network coding imposed on each node by simplify the decoding process.

• TTA Journal
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• s.128
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• pp.77-81
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• 2010

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.476-482
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• 2012

In this paper, we analyze and compare several co-channel interference mitigation algorithms for WBAN application in 2.4 GHz ISM frequency bands. ML (Maximum Likelihood), OC (Optimal Combining) and MMSE (Minimum Mean Square Error) has been considered for the possible techniques for interference cancellation in view of the trade off between the performance and the complexity of implementation. Based on the channel model of IEEE 802.15.6 standard, simulation results show that ML and OC attains the lower BER performance than that of MMSE if we assume the perfect channel estimation. But, ML and OC have the additional requirement of implementation for his own and other users's channel estimation process, hence, besides the BER performance, the complexity of implementation and the sensitivity to channel estimation error should be considered since it requires the simple and small sized equipment for WBAN system application. In addition, the gap of detection BER performance between ML, OC and MMSE is much decreased under the imperfect channel estimation if we adopt real channel estimation process, therefore, in order to apply to WBAN system, the trade off between the BER performance and complexity of implemetation should be seriously considered to decide the best co-channel interference cancellation for WBAN system application.

• Journal of Convergence Society for SMB
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• v.3 no.2
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• pp.27-32
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• 2013

Wireless Body Area Networks (WBAN) have been made possible by the emergence of small and lightweight wireless systems such as Bluetooth, enabled devices and PDAs. Antennas are an essential part of any WBAN system and due to various technical requirements and physical constraints, careful consideration of their design and deployment is needed. This paper is proposing on the design of wearable antenna as parts of clothing to serve communications functions, such as tracking and navigation in health care applications. The substrates of the wearable antennas will be made from textile materials and since it is wearable, it should have a small size, be light weight, low maintenance, and unobtrusive. This proposed paper will also investigate the influence of different parameters for wearable antenna including types of textile/substrate to ensure that the antenna design satisfies WBAN requirements. The characteristics and behavior of the antenna need to adhere to specifications set by wireless standards and system technology requirements. This means that the transmitting and receiving frequency bands of the various units need to be chosen accordingly. Since there are restrictions on the level of power to which the human body can be exposed to, the antenna as well as other RF system components must be designed to meet these restrictions. Antenna gain, which directly affects power transmitted, is a critical parameter in ensuring power levels fall within the safety guidelines and so will be of primary importance in the design. The electromagnetic interaction between WBAN antennas and devices and the human body will also be explored.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.133-138
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• 2009

In this paper, we propose a ZCD (Zero Correlation Duration) code based Ultra Wide Band(UWB) MODEM(modulation and demodulation) technique for WBAN as a hunman body wireless communication operating in WBAN (Wireless Body Area Network) environment. We certified ZCD code based UWB schemes are available for hunman body wireless communications by various simulation and performance analysis using WBAN transmission channels. Furthermore, we suggested some possibility of RFIC implementation related to human body based UWB communication module by presenting some related examples.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.229-234
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• 2012

This paper presents channel measurements for wireless body area network(WBAN) and provides performance evaluation from the measurement. We measured the radio propagation in 2.45 GHz ISM band in an anechoic chamber according to various human movements and the position of transmit antennas. Two transmit antennas are mounted on different positions of human body for the purpose of comparing the diversity gain and correlation between the channels in $2{\times}1$ multiple-input single-output(MISO) systems. The experimental results show that the outage capacity is closely related with the correlation coefficient between channels in transmit diversity system.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.98-104
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• 2013

This paper presents a WBAN UWB receiver circuit for RTLS(real time location system) and wireless data communication. The UWB receiver is designed to OOK modulation for energy detection. The UWB receiver is designed for sub-sampling techniques using 4bit ADC and DLL.The proposed UWB receiver is designed in $0.18{\mu}m$ CMOS and consumes 61mA with a 1.8V supply voltage. The UWB receiver achieves a sensitivity of -85.7 dBm, a RF front-end gain of 42.1 dB, a noise figure of 3.88 dB and maximum sensing range of 4 meter.