Adaptive Duty Cycling MAC Protocols Using Closed-Loop Control for Wireless Sensor Networks

The fundamental design goal of wireless sensor MAC protocols is to minimize unnecessary power consumption of the sensor nodes, because of its stringent resource constraints and ultra-power limitation. In existing MAC protocols in wireless sensor networks (WSNs), duty cycling, in which each node periodically cycles between the active and sleep states, has been introduced to reduce unnecessary energy consumption. Existing MAC schemes, however, use a fixed duty cycling regardless of multi-hop communication and traffic fluctuations. On the other hand, there is a tradeoff between energy efficiency and delay caused by duty cycling mechanism in multi-hop communication and existing MAC approaches only tend to improve energy efficiency with sacrificing data delivery delay. In this paper, we propose two different MAC schemes (ADS-MAC and ELA-MAC) using closed-loop control in order to achieve both energy savings and minimal delay in wireless sensor networks. The two proposed MAC schemes, which are synchronous and asynchronous approaches, respectively, utilize an adaptive timer and a successive preload frame with closed-loop control for adaptive duty cycling. As a result, the analysis and the simulation results show that our schemes outperform existing schemes in terms of energy efficiency and delivery delay

Exploiting the Capture Effect to Enhance RACH Performance in Cellular-Based M2M Communications

Cellular-based machine-to-machine (M2M) communication is expected to facilitate services for the Internet of Things (IoT). However, because cellular networks are designed for human users, they have some limitations. Random access channel (RACH) congestion caused by massive access from M2M devices is one of the biggest factors hindering cellular-based M2M services because the RACH congestion causes random access (RA) throughput degradation and connection failures to the devices. In this paper, we show the possibility exploiting the capture effects, which have been known to have a positive impact on the wireless network system, on RA procedure for improving the RA performance of M2M devices. For this purpose, we analyze an RA procedure using a capture model. Through this analysis, we examine the effects of capture on RA performance and propose an Msg3 power-ramping (Msg3 PR) scheme to increase the capture probability (thereby increasing the RA success probability) even when severe RACH congestion problem occurs. The proposed analysis models are validated using simulations. The results show that the proposed scheme, with proper parameters, further improves the RA throughput and reduces the connection failure probability, by slightly increasing the energy consumption. Finally, we demonstrate the effects of coexistence with other RA-related schemes through simulation results

Energy Efficient and Reliable ARQ Scheme (ER-ACK) for Mission Critical M2M/IoT Services

Wireless sensor networks (WSNs) are the main infrastructure for machine to machine (M2M) and Internet of thing (IoT). Since various sophisticated M2M/IoT services have their own quality-of-service (QoS) requirements, reliable data transmission in WSNs is becoming more important. However, WSNs have strict constraints on resources due to the crowded wireless frequency, which results in high collision probability. Therefore a more efficient data delivering scheme that minimizes both the transmission delay and energy consumption is required. This paper proposes energy efficient and reliable data transmission ARQ scheme, called energy efficient and reliable ACK (ER-ACK), to minimize transmission delay and energy consumption at the same time. The proposed scheme has three aspects of advantages compared to the legacy ARQ schemes such as ACK, NACK and implicit-ACK (I-ACK). It consumes smaller energy than ACK, has smaller transmission delay than NACK, and prevents the duplicated retransmission problem of I-ACK. In addition, resource considered reliability (RCR) is suggested to quantify the improvement of the proposed scheme, and mathematical analysis of the transmission delay and energy consumption are also presented. The simulation results show that the ER-ACK scheme achieves high RCR by significantly reducing transmission delay and energy consumption

The coverage rates for influenza vaccination and related factors in Korean adults aged 50 and older with chronic disease: based on 2016 Community Health Survey data

OBJECTIVES This study aims to identify the coverage rates for influenza vaccination and related factors depending on chronic disease in Korean adults aged 50 and older. METHODS The 2016 Korea Community Health Survey was used for analysis. Chi-square test was performed to investigate the coverage rates for influenza vaccination depending on chronic disease, and a multiple logistic regression analysis was used to identify the factors associated with influenza vaccination, by chronic disease. RESULTS In men with ≥1 chronic disease, 39.8% of 50-64 years of age, and 86.8% of elderly (over 65 years of age) received influenza vaccination. In women with ≥1 chronic disease, 58.7% of 50-64 years of age, and 89.9% of elderly (over 65 years of age) received influenza vaccination (p<0.001). The chronic diseases associated with influenza vaccination were hypertension (odds ratio [OR], 1.27; 95% confidence interval [CI], 1.19 to 1.37), diabetes (OR, 1.41; 95% CI, 1.28 to 1.55) in men aged 50-64, hypertension (OR, 1.34; 95% CI, 1.20 to 1.49), diabetes (OR, 1.17; 95% CI, 1.02 to 1.33), chronic cardiovascular disease (OR, 1.31; 95% CI, 1.07 to 1.60) in elderly (over 65 years of age). In women aged 50-64, hypertension (OR, 1.39; 95% CI, 1.30 to 1.49), diabetes (OR, 1.51; 95% CI, 1.35 to 1.68), chronic cardiovascular disease (OR, 1.31; 95% CI, 1.05 to 1.64), and hypertension (OR, 1.55; 95% CI, 1.40 to 1.71), diabetes (OR, 1.27; 95% CI, 1.12 to 1.43) in elderly (over 65 years of age). CONCLUSIONS Populations in aged 50-64 are recommendation subject for vaccination or classified as high-risk group in case with chronic disease. Though subject over 60 years old is age close to the elderly, the coverage rates for vaccination was low. It is necessary to devise strategies to raise the coverage rates for vaccination

Continuity of Care for Elderly Patients with Diabetes Mellitus, Hypertension, Asthma, and Chronic Obstructive Pulmonary Disease in Korea

We sought to assess continuity of care for elderly patients in Korea and to examine any association between continuity of care and health outcomes (hospitalization, emergency department visits, health care costs). This was a retrospective cohort study using the Korea National Health Insurance Claims Database. Elderly people, 65-84 yr of age, who were first diagnosed with diabetes mellitus (n=268,220), hypertension (n=858,927), asthma (n=129,550), or chronic obstructive pulmonary disease (COPD, n=131,512) in 2002 were followed up for four years, until 2006. The mean of the Continuity of Care Index was 0.735 for hypertension, 0.709 for diabetes mellitus, 0.700 for COPD, and 0.663 for asthma. As continuity of care increased, in all four diseases, the risks of hospitalization and emergency department visits decreased, as did health care costs. In the Korean health care system, elderly patients with greater continuity of care with health care providers had lower risks of hospital and emergency department use and lower health care costs. In conclusion, policy makers need to develop and try actively the program to improve the continuity of care in elderly patients with chronic diseases

On reducing IP mobility cost in mobile networks

Hierarchical Mobile IPv6 (HMIPv6) was proposed by the Internet Engineering Task Force (IETF) for efficient mobility management. HMIPv6 reduces the amount of signaling in the wired network link that exists in Mobile IPv6. But, HMIPv6 cannot reduce the signaling cost in the wireless link. In mobile networks, the wireless link has far less available bandwidth resources and limited scalability compared with the wired network link. Therefore, the signaling overhead associated with mobility management severely degrades the wireless link. In this paper, we propose virtual-IP (VIP) allocation scheme with dynamic VIP zone to reduce the wireless signaling cost in mobile networks. The performance of the proposed scheme is compared with HMIPv6. Based on the numerical analysis and simulation. we show that VIP allocation scheme reduces the wireless signaling cost under various system conditions

Mobility and QoS support in 4G wireless networks

Fourth-generation (4G) wireless networks will be the IP-based cellular networks integrating Internet with the existing cellular networks. Two important issues should be concerned in the IP-based cellular networks, IP mobility, and quality-of-service (QoS) guarantees. In this paper, we proposed two mechanisms to solve the problems with IP mobility and RSVP-based QoS provisioning. First, virtual-IP (VIP) allocation scheme in areas with a large rate of handoff can minimize the wireless signaling overhead due to IP mobility. The access routers (ARs) create dynamically the VIP zone by using the measured handoff rate derived from the history of the handolf into neighboring ARs. We show that VIP allocation scheme reduces the binding update messages in the wireless link than hierarchical mobile IPv6. Second, the new advance resource reservation protocol called proportional aggregate RSVP (PA-RSVP) can minimize waste of bandwidth and soft state refresh overhead due to IP mobility. It allocates the bandwidth in advance between the mobility anchor point and neighboring ARs using proportional aggregate reservation. We also show that PA-RSVP provides an improved performance over existing protocols