• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.131-136
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• 2010

Reducing the energy consumed by sensor node is a critical issue in wireless sensor networks. In particular, energy in each sensor node is too limited to waste on overhearing of packets that are not relevant. In this paper, we propose a wakeup scheme to reduce overhearing energy through the wakeup time difference between neighboring nodes. Other research papers on wakeup schemes usually focus on decreasing the latency. We propose a technique to reduce wasted energy for overhearing using the wakeup scheme. Simulation results indicate that our proposed wakeup scheme improves the sensor network lifetime.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.45-55
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• 2012

The energy efficiency is extremely significant in Wireless Sensor Networks (WSN) which deliver the data sensed in the sensor field, using wireless communications. Under the characteristics of WSN, many MAC protocols employ the Duty Cycle mechanism which continuously operates Wakeup and Sleep periods, for the energy efficiency. However, constant Wakeup period in general Duty Cycle incurs the limited performance of the energy efficiency and the receiving ratio. For addressing this, we design and propose a new scheme called Variable Wakeup Period, considering local traffic conditions. Our scheme enhances receiving ratio by increasing Wakeup period under the high traffic condition, and makes high energy efficiency by decreasing Wakeup period under the otherwise condition. In addition, we evaluate the performance of our scheme by performing the simulation, which experiments the previous synchronous and asynchronous MAC protocols, and which also experiments the same protocols with the proposed scheme, for comparative evaluations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1380-1385
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• 2006

A Pipelined Tone Wakeup(PTW) scheme(1) was proposed to support energy saving and end-to-end delay for sensor networks by providing an asynchronous wakeup pipeline to overlap the wakeup procedures with the packet transmission. But the scheme uses two radios and assumes error-free environments. In this paper, we propose a modified PTW scheme for wireless sensor networks. The proposed scheme is based on the PTW. The difference is that next hop information will be included in the ack packet from receiver node to sender node, So all the other neighbor nodes can stay in sleep mode long enough to save energy. Also ore get enhanced delay performance.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.201-209
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• 2016

In wireless sensor networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN medium access control protocols are bound by the energy-latency tradeoff. To break through the tradeoff, we propose a radio wave sensor called radio frequency (RF) wakeup sensor that is dedicated to sense the presence of a RF signal. The distinctive feature of our design is that the RF wakeup sensor can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF wakeup sensor a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF wakeup sensor detects a communication signal. According to our analysis, the response time of the RF wakeup sensor is much shorter than the minimum transmission time of a typical communication module. Therefore, we apply duty cycling to the RF wakeup sensor to further reduce the energy consumption without performance degradation. We evaluate the circuital characteristics of our RF wakeup sensor design by using Advanced Design System 2009 simulator. The results show that RF wakeup sensor allows a sensor node to completely turn off their communication module by performing the around-the-clock carrier sensing while it consumes only 0.07% energy of an idle communication module.

• Journal of IKEEE
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• v.22 no.3
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• pp.862-865
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• 2018

The proposed scheme minimizes the Idle time under the residual energy of the sensor node to adjust the Sleep-Wakeup period and minimize unnecessary energy consumption. It is The proposed scheme minimizes the Idle time under the residual energy of the sensor node to adjust the Sleep-Wakeup period and minimize unnecessary energy consumption. It is an important process to control the Application Packet Framework including the PHY and the MAC layer at each node's Idle time with the Idle time mechanism state before the proposed function is executed. The Current Control Level of the Report Attribute is fixed at one sending / receiving node where power consumption can occur, by changing Sleep-Wakeup time, the low power consumption efficiency was improved while satisfying the transmission requirement of the given delay time constraint.

• Speech Sciences
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• v.15 no.2
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• pp.169-176
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• 2008

This study was intended to analyze difference of vocal folds movements between upon wakeup and in several hours later in the morning. The difference of vocal fold movements was compared with fundamental frequency and a range of fundamental frequencies from maximum to minimum. The participants were 30 female adults between 20 and 29 years old. Voice samples were collected from their reading sentence (Jeong, 1993). The first sampling was conducted within 5 minutes after wakeup, while the second on 1 hour after the first sampling. Finally, the third voice sample was collected on 6 hours after the second sampling. The results of this study were as follows: First, fundamental frequency of the participants were by hour significantly time-dependent(F=7.843). Post-hoc multiple comparison (LSD) was conducted to determine when the difference could be observed. The result showed significant differences between upon wakeup and 6 hours later (p< .001) and between 1 hour later and 6 hours later (p< .05). Second, there were a significantly time-dependent ranges of fundamental frequencies of participants by hour (F=3.130). According to the results of the LSD analysis the significant differences in range of fundamental frequencies were found between upon wakeup and 1 hour later and also between wakeup and 6 hours later (p< .05). The results above indicate that vocal fold movements upon wakeup is different from those of several hours later.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.519-521
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• 2013

무선 센서 네트워크에서는 에너지가 제한된 배터리로 네트워크를 구성하기 때문에 에너지 효율적 사용에 대한 연구가 주요한 이슈이다. 본 논문에서는 효율적인 에너지 사용을 위하여 트래픽 변화 환경을 위한 Wakeup 주기 제어 메커니즘을 제안한다. 제안되는 MAC 프로토콜은 수신자의 제어 신호로 데이터 전송이 시작된다. 송신 노드는 트래픽이 변화를 데이터 패킷 프레임에 플래그(flag)를 추가하여 수신노드에 전달한다. 수신 노드는 이를 통해 수신 노드의 Wakeup 주기를 제어한다. 제안되는 MAC 프로토콜은 트래픽이 적을 경우 수신 노드의 sleep 구간의 증가를 통하여 에너지가 절약된다. 또한 트래픽이 높은 경우 수신 노드의 Wakeup 주기를 줄여 송신 노드의 idle listening으로 발생하는 에너지 소모를 감소시킨다. 제안되는 MAC 프로토콜은 기존의 프로토콜과 비교하여 빠르게 Wakeup 주기를 조절함으로서 에너지 효율적면에서 더 좋은 성능을 보여준다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1610-1618
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• 2014

Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that performs the hibernation for low power consumption is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. In the proposed hibernation mechanisms, WUSB communications are permitted at each m-periodic inactive periods of WBAN superframes by using the WBAN information of Wakeup Period and Wakeup Phase message fields. In our performance evaluations, performances according to amount of WUSB traffic and Wakeup Periods are analyzed respectively to evaluate the effectiveness of proposed hibernation structure in WUSB over IEEE 802.15.6.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.41-49
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• 2009

A crucial issue in deploying wireless sensor networks is to perform a sensing task in an area of interest in an energy-efficient manner since sensor nodes have limited energy Power. The most practical solution to solve this problem is to use a node wake-up scheduling protocol that some sensor nodes stay active to provide sensing service, while the others are inactive for conserving their energy In this paper, we present a simple wake-up scheduling protocol, which can maintain sensing coverage required by applications and yet increase network lifetime by turning off some redundant nodes. In order to do this, we use the concept of a weighted average distance. A node decides whether it is active or inactive based on the weighted average distance. The proposed protocol allows sensor nodes to sleep dynamically while satisfying the required sensing coverage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.452-458
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• 2014

In Wireless Sensor Networks the Medium access control (MAC) protocol has many challenges to solve such as reducing energy consumption, supporting QoS(quality of service) fairness, and reducing delivery delay. This paper proposed a low-delay supporting MAC protocol in multi-hop Wireless Sensor Networks. The proposed protocol uses the RB(rapid beacon) frame for reducing delivery delay. The RB frame is a modified IEEE 802.15.4 beacon frame. For sender adaptive-wakeup, the RB frame includes a seed number for determining of a receiver wakeup time. And for next hop receiver adaptive-wakeup, the RB frame includes the length of remaining data packet information. Results showed that our LD-MAC protocol outperformed other protocol in terms of data packet delivery delay.