Asymmetric RTS/CTS for Exposed Node Reduction in IEEE 802.11 Ad Hoc Networks

Matoba, Akihisa,Hanada, Masaki,Kanemitsu, Hidehiro,Kim, Moo Wan Korean Institute of Information Scientists and Eng 2014 Journal of Computing Science and Engineering Vol.8 No.2

One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, such as RTS/CTS assumed to be sent at 1 Mbps. The 802.11 standard has been enhanced several times since then and now it supports multi-rate transmission up to 65 Mbps in the currently popular 802.11n (20 MHz channel, single stream with long guard interval). As a result, the difference in transmission rates and coverages between the data frame and control frame can be very large. However adjusting the RTS/CTS transmission rate to optimize network throughput has not been well investigated. In this paper, we propose a method to decrease the number of exposed nodes by increasing the RTS transmission rate to decrease RTS coverage. Our proposed method, Asymmetric Range by Multi-Rate Control (ARMRC), can decrease or even completely eliminate exposed nodes and improve the entire network throughput. Experimental results by simulation show that the network throughput in the proposed method is higher by 20% to 50% under certain conditions, and the proposed method is found to be effective in equalizing dispersion of throughput among nodes.

Asymmetric RTS/CTS for Exposed Node Reduction in IEEE 802.11 Ad Hoc Networks

Akihisa Matoba,Masaki Hanada,Hidehiro Kanemitsu,Moo Wan Kim 한국정보과학회 2014 Journal of Computing Science and Engineering Vol.8 No.2

One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, such as RTS/CTS assumed to be sent at 1 Mbps. The 802.11 standard has been enhanced several times since then and now it supports multi-rate transmission up to 65 Mbps in the currently popular 802.11n (20 MHz channel, single stream with long guard interval). As a result, the difference in transmission rates and coverages between the data frame and control frame can be very large. However adjusting the RTS/CTS transmission rate to optimize network throughput has not been well investigated. In this paper, we propose a method to decrease the number of exposed nodes by increasing the RTS transmission rate to decrease RTS coverage. Our proposed method, Asymmetric Range by Multi-Rate Control (ARMRC), can decrease or even completely eliminate exposed nodes and improve the entire network throughput. Experimental results by simulation show that the network throughput in the proposed method is higher by 20% to 50% under certain conditions, and the proposed method is found to be effective in equalizing dispersion of throughput among nodes.

Comparison of mdLVs Based Methods for Nonlinear Receding Horizon Control

Shunsuke Matoba,Hisakazu Nakamura,Hirokazu Nishitani 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

Receding horizon (RH) control attracts much attention in both the control theory and control applications. For RH control, we have proposed a new computation method for solving simultaneous linear equations by using a Moore-Penrose pseudoinverse and a singular value decomposition (SVD). In our proposed method, SVD is achieved by mdLVs and newly developed simultaneous error correction (SEC) method. However, we did not compare our proposed method with I-SVD that also equips mdLVs. In this paper, we compare our proposed method mdLVs/SEC with I-SVD by theoretical analysis and numerical experiments, and we show SEC needs a much smaller computation cost than I-SVD. Finally, we elucidate advantages of SEC in nonlinear RH control in numerical experiments.

The association between the socioeconomic deprivation level and ischemic heart disease mortality in Japan: an analysis using municipality-specific data

Tasuku Okui(Tasuku Okui ),Tetsuya Matoba(Tetsuya Matoba ),Naoki Nakashima(Naoki Nakashima ) 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: Geographical variation in the standardized mortality ratio (SMR) for ischemic heart disease (IHD) among municipalities has not been assessed in Japan. Additionally, associations between area-level socioeconomic deprivation indices and IHD mortality have not been identified in Japan. The present study investigated this association. METHODS: Information on IHD mortality was extracted from Vital Statistics data from 2018 to 2020 for each municipality in Japan. The socioeconomic deprivation level was derived from multiple socioeconomic characteristics. We classified municipalities into quintiles based on the deprivation level and investigated the association between the deprivation level and the SMR of IHD. Additionally, a Bayesian spatial regression model was used to investigate this association, adjusting for other municipal characteristics. RESULTS: Geographical variation in the SMR of IHD was revealed, and municipalities with high SMRs were spatially clustered. There was a weak negative correlation between the socioeconomic deprivation level and the SMRs (correlation coefficient, -0.057 for men and -0.091 for women). In contrast, the regression analysis showed a statistically significant positive association between deprived areas and the IHD mortality rate, and the relative risks for the most deprived municipalities compared with the least deprived municipalities were 1.184 (95% credible interval [CrI], 1.110 to 1.277) and 1.138 (95% CrI, 1.048 to 1.249) for men and women, respectively. CONCLUSIONS: A weak negative correlation between the socioeconomic deprivation level and the SMR was observed in the descriptive analysis, while the regression analysis showed that living in deprived areas was statistically positively associated with the IHD mortality rate.

Photoacoustic lymphangiography before and after lymphaticovenular anastomosis

Oh, Anna,Kajita, Hiroki,Matoba, Eri,Okabe, Keisuke,Sakuma, Hisashi,Imanishi, Nobuaki,Takatsume, Yoshifumi,Kono, Hikaru,Asao, Yasufumi,Yagi, Takayuki,Aiso, Sadakazu,Kishi, Kazuo Korean Society of Plastic and Reconstructive Surge 2021 Archives of Plastic Surgery Vol.48 No.3

Background Lymphaticovenular anastomosis (LVA) is a minimally invasive surgical procedure used to treat lymphedema. Volumetric measurements and quality-of-life assessments are often performed to assess the effectiveness of LVA, but there is no method that provides information regarding postoperative morphological changes in lymphatic vessels and veins after LVA. Photoacoustic lymphangiography (PAL) is an optical imaging technique that visualizes the distribution of light-absorbing molecules, such as hemoglobin or indocyanine green (ICG), and provides three-dimensional images of superficial lymphatic vessels and the venous system simultaneously. In this study, we performed PAL in lymphedema patients before and after LVA and compared the images to evaluate the effect of LVA. Methods PAL was performed using the PAI-05 system in three patients (one man, two women) with lymphedema, including one primary case and two secondary cases, before LVA. ICG fluorescence lymphography was performed in all cases before PAL. Follow-up PAL was performed between 5 days and 5 months after LVA. Results PAL enabled the simultaneous visualization of clear lymphatic vessels that could not be accurately seen with ICG fluorescence lymphography and veins. We were also able to observe and analyze morphological changes such as the width and the number of lymphatic vessels and veins during the follow-up PAL after LVA. Conclusions By comparing preoperative and postoperative PAL images, it was possible to analyze the morphological changes in lymphatic vessels and veins that occurred after LVA. Our study suggests that PAL would be useful when assessing the effect of LVA surgery.

The Use of Embryo Transfer for the Improvement of Pregnancy Rate in Repeat Breeding Dairy Cattle

Osamu Dochi,Satoko Matoba,Hisaichi Koyama 한국동물생명공학회(구 한국동물번식학회) 2009 발생공학 국제심포지엄 및 학술대회 Vol.2009 No.1

Histone Demethylase Expression Enhances Human Somatic Cell Nuclear Transfer Efficiency and Promotes Derivation of Pluripotent Stem Cells

Chung, Young Gie,Matoba, Shogo,Liu, Yuting,Eum, Jin Hee,Lu, Falong,Jiang, Wei,Lee, Jeoung Eun,Sepilian, Vicken,Cha, Kwang Yul,Lee, Dong Ryul,Zhang, Yi Elsevier 2015 Cell stem cell Vol.17 No.6

<P><B>Summary</B></P> <P>The extremely low efficiency of human embryonic stem cell (hESC) derivation using somatic cell nuclear transfer (SCNT) limits its potential application. Blastocyst formation from human SCNT embryos occurs at a low rate and with only some oocyte donors. We previously showed in mice that reduction of histone H3 lysine 9 trimethylation (H3K9me3) through ectopic expression of the H3K9me3 demethylase Kdm4d greatly improves SCNT embryo development. Here we show that overexpression of a related H3K9me3 demethylase KDM4A improves human SCNT, and that, as in mice, H3K9me3 in the human somatic cell genome is an SCNT reprogramming barrier. Overexpression of KDM4A significantly improves the blastocyst formation rate in human SCNT embryos by facilitating transcriptional reprogramming, allowing efficient derivation of SCNT-derived ESCs using adult Age-related Macular Degeneration (AMD) patient somatic nuclei donors. This conserved mechanistic insight has potential applications for improving SCNT in a variety of contexts, including regenerative medicine.</P> <P><B>Highlights</B></P> <P> <UL> <LI> H3K9me3 is a barrier for human SCNT reprogramming as in mouse </LI> <LI> Injection of human KDM4A mRNA improves SCNT success in mouse oocytes </LI> <LI> KDM4A also improves human SCNT blastocyst formation and NT-ESC derivation </LI> <LI> H3K9me3 removal facilitates zygotic genome activation in human SCNT embryos </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Selecting Ordering Policy and Items Classification Based on Canonical Correlation and Cluster Analysis

Nagasawa, Keisuke,Irohara, Takashi,Matoba, Yosuke,Liu, Shuling Korean Institute of Industrial Engineers 2012 Industrial Engineeering & Management Systems Vol.11 No.2

It is difficult to find an appropriate ordering policy for a many types of items. One of the reasons for this difficulty is that each item has a different demand trend. We will classify items by shipment trend and then decide the ordering policy for each item category. In this study, we indicate that categorizing items from their statistical characteristics leads to an ordering policy suitable for that category. We analyze the ordering policy and shipment trend and propose a new method for selecting the ordering policy which is based on finding the strongest relation between the classification of the items and the ordering policy. In our numerical experiment, from actual shipment data of about 5,000 items over the past year, we calculated many statistics that represent the trend of each item. Next, we applied the canonical correlation analysis between the evaluations of ordering policies and the various statistics. Furthermore, we applied the cluster analysis on the statistics concerning the performance of ordering policies. Finally, we separate items into several categories and show that the appropriate ordering policies are different for each category.

Applying Genetic Algorithm for Can-Order Policies in the Joint Replenishment Problem

Nagasawa, Keisuke,Irohara, Takashi,Matoba, Yosuke,Liu, Shuling Korean Institute of Industrial Engineers 2015 Industrial Engineeering & Management Systems Vol.14 No.1

In this paper, we consider multi-item inventory management. When managing a multi-item inventory, we coordinate replenishment orders of items supplied by the same supplier. The associated problem is called the joint replenishment problem (JRP). One often-used approach to the JRP is to apply a can-order policy. Under a can-order policy, some items are re-ordered when their inventory level drops to or below their re-order level, and any other item with an inventory level at or below its can-order level can be included in this order. In the present paper, we propose a method for finding the optimal parameter of a can-order policy, the can-order level, for each item in a lost-sales model. The main objectives in our model are minimizing the number of ordering, inventory, and shortage (i.e., lost-sales) respectively, compared with the conventional JRP, in which the objective is to minimize total cost. In order to solve this multi-objective optimization problem, we apply a genetic algorithm. In a numerical experiment using actual shipment data, we simulate the proposed model and compare the results with those of other methods.

Genetic Algorithm-Based Coordinated Replenishment in Multi-Item Inventory Control

Nagasawa, Keisuke,Irohara, Takashi,Matoba, Yosuke,Liu, Shuling Korean Institute of Industrial Engineers 2013 Industrial Engineeering & Management Systems Vol.12 No.3

We herein consider a stochastic multi-item inventory management problem in which a warehouse sells multiple items with stochastic demand and periodic replenishment from a supplier. Inventory management requires the timing and amounts of orders to be determined. For inventory replenishment, trucks of finite capacity are available. Most inventory management models consider either a single item or assume that multiple items are ordered independently, and whether there is sufficient space in trucks. The order cost is commonly calculated based on the number of carriers and the usage fees of carriers. In this situation, we can reduce future shipments by supplementing items to an order, even if the item is not scheduled to be ordered. On the other hand, we can reduce the average number of items in storage by reducing the order volume and at the risk of running out of stock. The primary variables of interest in the present research are the average number of items in storage, the stock-out volume, and the number of carriers used. We formulate this problem as a multi-objective optimization problem. In a numerical experiment based on actual shipment data, we consider the item shipping characteristics and simulate the warehouse replenishing items coordinately. The results of the simulation indicate that applying a conventional ordering policy individually will not provide effective inventory management.