• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1135-1140
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• 2016

The main challenge in designing wearable WBANs is to guarantee the balance of QoS demands in the network with the low power constraints of limited battery powered nodes. Low power devices implanted in or attached to the body should be designed to meet minimum energy requirements due to their limited battery life and be small in size to be easily wearable. In this paper, we propose a method for optimizing channel allocation method that is compatible with the IEEE 802.15.6 standard, enables the maximum amount of power charge at idle, guarantees the QoS of a WBAN, and provides the reliable date transmission between nodes and hubs in the network. Our extensive simulations will show that the method we propose not only maximizes the QoS in packet transmission but also improves the level of energy efficiency.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.36-44
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• 2016

In this paper, an Impulse Radio-Ultra Wide band RF Transceiver for WBAN applications is implemented in $0.18{\mu}m$ CMOS technology. The designed RF transceiver support 3-5GHz UWB low band and employs OOK(On-Off Keying) modulation. The receiver employs non-coherent energy detection architecture to reduce complexity and power consumption. For the rejection of the undesired interferers and improvement of the receiver sensitivity, RF active notch filter is integrated. The VCO based transmitter employs the switch mechanism. As adapt the switch mechanism, power consumption and VCO leakage can be reduced. Also, the spectrum mask is always same at each center frequency. The measured sensitivity of the receiver is -84.1 dBm at 3.5 GHz with 1.579 Mbps. The power consumption of the transmitter and receiver are 0.3nJ/bit and 41 mW respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.32-41
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• 2010

We propose the use of multi-preambles using Gold codes and analyze its performance. The multi-preamble is a way of utilizing different codes for preambles according to operation modes or applications in a system. The receiver can be easily implemented using the maximum likelihood algorithm. The performance is robust against noise due to the good correlation characteristic of the Gold codes. We use 128-bit-long multi-preambles generated by 127 bit Gold codes in deriving the detection error probability and in verifying the validity through computer simulation. The results show that the theory and the experiment are in good agreement within the approximation error.

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.28-33
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• 2013

This paper proposes a miniaturized high-isolation diversity antenna for wearable wireless body area network (WBAN) applications. An inverted-F type radiating element is used to reduce the overall dimension of the proposed antenna to $30mm{\times}30mm{\times}2.5mm$. The antenna performance on the human body phantom is analyzed through simulation and the performance of the fabricated antenna is verified by comparing the measured data with that of the simulation when the antenna is placed on a semi-solid flat phantom with equivalent electrical properties of a human body. The fabricated antenna has a 10 dB return loss bandwidth over the Industrial Scientific Medical (ISM) band from 2.35 GHz to 2.71 GHz and isolation is higher than 28 dB at 2.45 GHz. The measured peak gain of antenna elements # 1 and # 2 is -0.43 dBi and -0.54 dBi, respectively. Performance parameters are analyzed, including envelope correlation coefficient (ECC), mean effective gain (MEG), and the MEG ratio. In addition, the specific absorption ratio (SAR) distributions of the proposed antenna are measured for consideration in use.

• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1391-1398
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• 2012

Time synchronization is crucial in wireless sensor networks such as Wireless USB and WBAN for diverse purposes from the MAC to the application layer. This paper proposes online clock skew estimators to achieve energy-efficient time synchronization for wireless sensor networks. By using recursive least squares estimators, we not only reduce the amount of data which should be stored locally in a table at each sensor node, but also allow offset and skew compensations to be processed simultaneously. Our skew estimators can be easily integrated with traditional offset compensation schemes. The results of simulation and experiment show that the accuracy of time synchronization can be greatly improved through our skew compensation algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4436-4452
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• 2015

The IEEE 802.15.6 standard is introduced to satisfy all the requirements for monitoring systems operating in, on, or around the human body. In this paper, analytical models are developed for evaluating the performance of the IEEE 802.15.6 CSMA/CA-based medium access control protocol for wireless body area networks (WBAN) under unsaturation condition. We employ a three-dimensional Markov chain to model the backoff procedure, and an M/G/1/K queuing system to describe the packet queues in the buffer. The throughput and delay performances of WBAN operating in the beacon mode are analyzed in heterogeneous network comprised of different user priorities. Simulation results are included to demonstrate the accuracy of the proposed analytical model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.62-69
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• 2014

In this paper, WBAN(Wireless Body Area Network) On-body system using the surface-oriented antenna about the impact of human internal organs were analyzed through experiments. The received signal strength is measured for effect of human using the human model and the phantom of torso. Experiments are performed in anechoic chamber without moving and measured by Vector Network Analyzer. This paper confirms the effect of human body by comparing the human model and the phantom of torso. And also know the human internal organs effect on the antennas loss of received signal strength by measured data.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.109-112
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• 2017

WBAN (Wearable Body Area Network)는 옷이나 몸에 이식된 디바이스들이 몸을 중심으로 결합이나 통신하는 네트워크를 뜻한다. 여기서 사람이 몸에 착용하는 장치인 웨어러블 디바이스는 가벼운 형태의 배터리를 요구한다. 그로 인해, 다른 기기들과는 달리 짧은 배터리 수명을 가질 뿐만 아니라 통신에 관한 제약을 발생시킨다. 따라서 본 논문에서는 저전력 프로토콜을 지원하는 다중대역 웨어러블 디바이스 제어 시스템을 제안한다. 이를 위해 BLE (Bluetooth Low Energy) 기반의 프로토콜 스택으로 BLE, 6LoWPAN (IPv6 over Low power WPAN), CoAP (Constrained Application Protocol)을 적용해 데이터 패킷 크기를 감소 시키고 BLE/Wi-Fi 선택 기능을 통해 통신 제약을 완화하고 전체적인 WBAN 에서의 소비 전력을 감소하고자한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.985-994
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• 2012

This paper presents the real channel measurements and investigates their statistical characterization in wireless body area network(WBAN). In on-/off body channel, the measurements are performed with some representative human movements for considering human movements. Moreover, three signal transmission schemes with outage constraint are studied for getting total power consumption in each transmission scheme. Using the real channel measurements, between theoretical and realistic simulation are compared. This paper shows that power efficiency is improved through cooperative communication, and how much position of sensor node and human movement affect signal transmission power.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.995-1002
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• 2018

A Contention Access Period(: CAP) with high contention in priority-based MAC protocols can result in higher number of collisions and retransmissions. High-Priority traffic dominates low-priority traffic during CAP depleting low-priority traffic, adversely affecting WBAN throughput, delay, and energy consumption. This paper proposes a Emergency data-First-Priority MAC(: EFP-MAC) superframe structure that is able to reduce contention in the CAP period, and provides a fair chance for low-priority traffic. As a result, the proposed Emergency data-First Priority MAC(; EFP-MAC) The Simulation results show that the proposed MAC achieves lower energy consumption, higher throughput and low latency than the IEEE 802.15.4 standard.