Browsing by Author "Lin, Chih-Che"

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A rule-based inter-session network coding scheme over IEEE 802.16(d) mesh CDS-mode networks
(2012-02-02)
Wang, Shie-Yuan
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Lin, Chih-Che
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Chang, Yu-Chi
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資訊工程學系
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Department of Computer Science
In the literature, an opportunistic inter-session network coding scheme needs to exchange extra control messages to maintain traffic flow states to operate. However, such a requirement increases the implementation complexity of a network coding scheme. In this paper, we propose a rule-based network coding scheme (RNC) that performs opportunistic intersession network coding using a stateless design. By exploiting this stateless design, the proposed coding scheme is easy to implement and deploy. In addition, in this paper based on RNC we study the hidden terminal problems between different coding structures. Such a problem may result in severe packet collisions in a network-coding-based network and thus degrade network coding performance. To alleviate this problem, based on RNC we propose a smart handshake procedure (called RNC-SHP) over the IEEE 802.16(d) mesh coordinated distributed scheduling (CDS) mode to reduce the number of hidden terminals between pairwise network coding structures. Our simulation results show that the proposed RNC schemes can greatly outperform the original routing-based scheme on end-to-end flow goodputs and packet delays. (C) 2011 Elsevier B.V. All rights reserved.
A vehicle collision warning system employing vehicle-to-infrastructure communications
(2008)
Wang, Shie-Yuan
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Cheng, Yow-Wei
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Lin, Chih-Che
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Hong, Wei-Jyun
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He, Ting-Wei
Road safety has become an important issue and gained much attention for many years. To avoid vehicle collisions on the roads, researchers have proposed various collision warning systems (CWS) using different technologies. Compared with CWS using other technologies, a radio based CWS is more capable of avoiding collisions in off sight scenarios (such as the four corners of an intersection). Most existing radio based CWSs operate using vehicle to vehicle communications. However, in such CWSs, high mobility of moving vehicles easily results in message collisions and link breakage, impairing the reliability of these CWSs. An alternative is employing vehicle to infrastructure communication to build CWSs. In this paper, we propose a radio based CWS employing vehicle to infrastructure communications. Our simulation results show that the proposed CWS can effectively reduce the number of vehicle collisions without degrading the traffic throughput of a road network.
An IEEE 802.11 Cognitive Radio MAC Protocol with Dynamic Bandwidth Allocation Capabilities
(2012)
Lau, Lee-Chin
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Lin, Chih-Che
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Wang, Shie-Yuan
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資訊工程學系
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Department of Computer Science
The Cognitive Radio (CR) technology has emerged as a hot research area recently due to its high potential in addressing the spectrum underutilization problem. In this paper, the CR is applied to unauthorized CR users (CRUs) such that these nodes can access the 802.11 spectrum opportunistically to flexibly use the detected "spectrum holes," with the ultimate goal of improving the 802.11 spectrum utilization. In [5], the authors proposed a bi-directional CR MAC protocol such that the CRUs can smartly negotiate and reserve bandwidth either uni-directionally or bi-directionally, to better support both the TCP and UDP flows. However, the protocol design is inadequate in supporting traffic demands in more complicated network cases. To address this problem, we proposed a CR MAC protocol with a dynamic bandwidth allocation capability, which can well support various types of network traffic, particularly asymmetric two-way traffic flows. We used the NCTUns network simulator to conduct the study. Our simulation results show that the proposed protocols can further utilize the "spectrum holes" in a more effective way while guaranteeing QoS support to both the surrounding CRUs and authorized 802.11 nodes.
Autophagy-related gene LC3 expression in tumor and liver microenvironments significantly predicts recurrence of hepatocellular carcinoma after surgical resection
(2018-07-02)
Lin, Chih-Wen
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Chen, Yaw-Sen
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Lin, Chih-Che
;
Lee, Po-Huang
;
Lo, Gin-Ho
Background: The role of autophagy-related markers as the prognostic factor of post-operative hepatocellular carcinoma (HCC) recurrence remained controversial. Methods: Overall, 535 consecutive HCC patients undergoing curative resection from 2010 to 2014 were followed and classified with early (ER, < 2 years) or late recurrence (LR). Autophagy-related markers, LC3, Beclin-1, and p62 expression was immunohistochemically assessed in HCC and adjacent non-tumor (ANT) tissues. Results: HCC recurred in 245 patients: 116 with ER and 129 with LR. The cumulative incidence of recurrence at 1, 3, 5, and 7 years was 9.7%, 33.9%, 53.3%, and 66.3%, respectively. In multivariate analysis, HCC recurrence was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (hazard ratio/95% confidence interval: 6.12/2.473-17.53, 4.18/1.285-13.61, and 1.89/1.299-2.757) and macrovascular invasion (1.63/1.043-2.492) and cirrhosis (1.59/1.088-2.326). ER was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (6.54/2.934-15.81, 3.26/1.034-10.27, and 2.09/1.313-3.321) and macrovascular and microvascular invasion (2.65/1.306-5.343 and 2.55/1.177-5.504). LR was significantly associated with low LC3 expression in tumor and ANT tissues, HCC tissues only and ANT tissues only (5.02/1.372-18.83, 3.19/1.13-12.09, and 1.66/1.051-2.620) and cirrhosis (1.66/1.049-2.631). Patients with low and high LC3 expression in tumor and ANT tissues showed a 5-year cumulative recurrence of 94.3% and 41.7%, respectively (p < 0.001). Conclusions: The high LC3 expression in the tumor and liver microenvironments is significantly associated with lower HCC recurrence. Furthermore, tumor characteristics and liver microenvironment were also significantly associated with ER and LR, respectively. Translational impact: The analysis for LC3 expression in both the HCC and ANT tissues could identify patients at risk of HCC recurrence.
Bi-directional Cognitive Radio MAC Protocol for Supporting TCP Flows
(2011)
Lau, Lee-Chin
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Lin, Chih-Che
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Wang, Shie-Yuan
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資訊工程學系
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Department of Computer Science
The Cognitive Radio (CR) technology has emerged as a recent breakthrough radio technology to meet future wireless demands in terms of both spectrum efficiency and performance of new wireless applications. In an 802.11 Cognitive Radio Network (CRN), when the spectrum is not used, unauthorized users with CRs can access the frequencies assigned to authorized users in an opportunistic manner, thus dramatically improving spectrum efficiency of the network. In [5], the authors proposed a CR MAC protocol for 802.11 CRNs such that the unauthorized CR users (CRUs) can flexibly use the "spectrum holes" without affecting the performance of the authorized users. However, the protocol design proposed in [5] can degrade the throughput performance of TCP flows. Since TCP is a primary transport protocol for most of the internet applications today, it is imperative that a proposed CR MAC protocol can well support TCP flows. To address this problem, in this paper we propose a Bi-directional CR MAC (Bi-MAC) protocol such that the CRUs can smartly negotiate and reserve bandwidth based on the anticipated packet exchanges on the data channels. Our simulation results show that the Bi-MAC protocol can effectively improve both the TCP and UDP performance of CRUs and increase the network goodputs.
Enhanced MAC Protocol for Cognitive Radios over IEEE 802.11 Networks
(2011)
Wang, Shie-Yuan
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Huang, Yu-Ming
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Lau, Lee-Chin
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Lin, Chih-Che
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資訊工程學系
The Cognitive Radio (CR) technology is proposed for solving the spectrum underutilization problem and has gained great attention. By allowing unauthorized users to opportunistically access frequencies authorized to specific networks (called primary networks), the CR technology can increase the bandwidth utilization of the radio spectrum in a global perspective. In [1], the authors proposed a MAC protocol for CRs that aims to "borrow" the link bandwidth from IEEE 802.11 networks. This protocol allows CR users to opportunistically exchange data on an idle 802.11 channel. However, the protocol proposed in [1] selects an 802.11 channel for data exchange in a random manner. This random channel selection process is time-consuming for CR users to start a data transmission. In addition, the protocol does not consider the effects of hidden terminals (HTs), which often exist in wireless networks and significantly decrease the goodputs of a network. To address these problems, in this paper we propose enhancements to the protocol proposed in [1]. The proposed protocol is evaluated using extensive simulations. Our simulation results show that our proposed protocol can effectively decrease the time required for finding an idle 802.11 channel to transmit data and therefore increase the network goodputs in networks with and without the existence of HTs.
Evaluating and Improving the TCP/UDP Performances of IEEE 802.11(p)/1609 Networks
(2008)
Wang, Shie-Yuan
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Chao, Hsi-Lu
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Liu, Kuang-Che
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He, Ting-Wei
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Lin, Chih-Che
The IEEE 802.11(p)/1609 standard is an emerging technology for vehicular communication networks. It amends the IEEE 802.11-2007 standard and defines a new WAVE operational mode for vehicular environments. The WAVE mode utilizes a combined FDMA/TDMA scheme to manage network bandwidth. In this mode, a node must periodically switch its frequency channel between two different channels over time. Such a design may result in bandwidth wastage due to the residual time caused by channel switching. In this paper, we propose two easy-to-implement schemes to mitigate this problem and compare their TCP/UDP performances with those of the original scheme. Our simulation results provide many insights into the operations of these schemes on IEEE 802.11(p)/1609 networks and show that the proposed schemes always outperform the original scheme.
Exploiting Event-Level Parallelism for Parallel Network Simulation on Multicore Systems
(2012-04-01)
Wang, Shie-Yuan
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Lin, Chih-Che
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Tzeng, Yan-Shiun
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Huang, Wen-Gao
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Ho, Tin-Wei
This paper proposes a parallel simulation methodology to speed up network simulations on modern multicore systems. In this paper, we present the design and implementation of this approach and the performance speedups achieved under various network conditions. This methodology provides two unique and important advantages: 1) one can readily enjoy performance speedups without using an unfamiliar simulation language/library to rewrite his protocol module code for parallel simulations, and 2) one can conduct parallel simulations in the same way as when he conducts sequential simulations. We implemented this methodology and evaluated its performance speedups on the popular ns-2 network simulator. Our results show that this methodology is feasible and can provide satisfactory performance speedups under high event load conditions on wired networks.
Facilitating the network entry and link establishment processes of IEEE 802.16 mesh networks
(2007)
Wang, Shie-Yuan
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Lin, Chih-Che
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Fang, Ku-Han
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Hsu, Teng-Wei
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資訊工程學系
The IEEE 802.16 standard is a promising next-generation broadband technology. It contains two operational modes - PMP and mesh. The PMP mode defines one-hop communication between a base station (BS) and a subscriber station (SS), while the mesh mode allows traffic to be directly exchanged and forwarded among neighboring SSs. In the mesh mode, network initialization is composed of the network entry (NENT) and link establishment (LinkEst) processes. In this paper, we identify that the NENT process is prone to fail in dense networks and propose a solution to remedy this problem. Besides, we propose an extension to the LinkEst process to improve its efficiency. Both proposals are compatible with the current standard. Our simulation results show that our solution to the NENT process can on average increase the success rate by 22.5%, and our extension to the LinkEst process can on average speed up the process by 2.57 times.
Improving the Data Scheduling Efficiency of the IEEE 802.16(d) Mesh Network
(2008)
Wang, Shie-Yuan
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Lin, Chih-Che
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Fang, Ku-Han
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資訊工程學系
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Department of Computer Science
In an IEEE 802.16(d) (WiMAX) mesh network, network bandwidth can be managed by either the centralized scheduling (CS) mode or the distributed scheduling (DS) mode. Compared with the CS mode, the DS mode provides a larger bandwidth capacity and is more scalable. However, because the DS mode uses an on-demand three-way handshake procedure to establish data schedules, the network quality experienced by application programs may fluctuate drastically. To address this problem, in this paper we propose three schemes to improve the data scheduling efficiency of the DS mode of the IEEE 802.16(d) mesh network. Our simulation results show that network performances and qualities experienced by application programs are significantly improved under our schemes.
Improving the performances of distributed coordinated scheduling in IEEE 802.16 mesh networks
(2008-07-01)
Wang, Shie-Yuan
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Lin, Chih-Che
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Chu, Han-Wei
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Hsu, Teng-Wei
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Fang, Ku-Han
The IEEE 802.16 mesh network is a promising next-generation wireless backbone network. In such a network, setting the holdoff time for nodes is essential to achieving good performances of medium-access-control-layer scheduling. In this paper, we propose a two-phase holdoff time setting scheme to improve network utilization. Both static and dynamic approaches of this scheme are proposed, and their performances are compared against those of the original schemes. Our simulation results show that both approaches significantly increase the utilization of the control-plane bandwidth and decrease the time required to establish data schedules. In addition, both approaches provide efficient and fair scheduling for IEEE 802.16 mesh networks and generate good application performances.
NCTUns 5.0: A Network Simulator for IEEE 802.11(p) and 1609 Wireless Vehicular Network Researches
(2008)
Wang, Shie-Yuan
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Lin, Chih-Che
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資訊工程學系
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Department of Computer Science
NCTUns is a novel network simulator and emulator that has many unique features over traditional network simulators and emulators. It is an open-source software running on Linux and is being used by many researchers in the world. According to the NCTUns official web site (http://NSL.csie.nctu.edu.tw/nctuns.html), as of June 1, 2008, more than 11,546 people from 124 countries have registered and downloaded this software and these numbers are still fast increasing. In its 5.0 release, NCTUns provides a complete implementation of the IEEE 802.11(p)/1609 standards defined for wireless vehicular networks. In this paper, we present the capabilities of NCTUns 5.0 focusing on its uses for IEEE 802.11(p)/1609 wireless vehicular network researches.
On Multi-hop Forwarding over WBSS-based IEEE 802.11(p)/1609 Networks
(2009)
Wang, Shie-Yuan
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Lin, Chih-Che
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Liu, Kuang-Che
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Hong, Wei-Jyun
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資訊工程學系
The IEEE 802.11(p)/1609 network is a promising candidate for future vehicular communication networks. Due to the deployment cost consideration, roadside units (RSUs) in such networks are usually installed only at hot spots and intersections, causing the service coverage of RSUs to be discontinuous. To overcome this problem, multihop data forwarding among vehicles can be used to extend the service coverage of RSUs. In this paper, we propose a receiver-centric WBSS (Wave Basic Service Set)-creating scheme to support multihop data forwarding in WBSS-based IEEE 802.11(p)/1609 networks and evaluate its performances using simulations. Our simulation results show that this scheme outperforms a typical sender-centric WBSS-creating scheme on end-to-end flow goodputs under different traffic loads.
On the performances of forwarding multihop unicast traffic in WBSS-based 802.11(p)/1609 networks
(2011-08-04)
Wang, Shie-Yuan
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Lin, Chih-Che
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Hong, Wei-Jyun
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Liu, Kuang-Che
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資訊工程學系
The IEEE 802.11(p)/1609 network is a promising candidate for future vehicular communication networks. In this new network, the operation of a new Wave Basic Service set (WBSS) is defined for vehicular environments. Due to the deployment cost consideration, roadside units (RSUs) in such networks are usually installed only at hot spots and intersections, causing the service coverage of RSUs to be discontinuous. To overcome this problem, multihop data forwarding among vehicles can be used to extend the service coverage of RSUs. The multihop geocasting problem has been studied and addressed in our previous work [1], where we proposed a receiver-centric WBSS geocasting scheme to increase multihop geocasting performances in WBSS-based networks. However, multihop unicasting, a more common facility in many network applications and services, was not dealt with in [1]. In this paper, we propose a new Receiver-centric WBSS Forwarding Scheme for Unicast traffic (called RWFS-U), which uses a prioritized receiver-centric WBSS creation design to efficiently support unicast data forwarding in WBSS-based networks. Extensive performance evaluations using both analyses and simulations are presented to understand the effects of the designs of WBSS forwarding schemes on the goodputs of end-to-end flows. Our results show that RWFS-U can significantly outperform the traditional sender-centric schemes on multihop unicasting in WBSS-based networks. (C) 2011 Elsevier B.V. All rights reserved.
On the performances of IEEE 802.16(d) mesh CDS-mode networks using Single-Switched-Beam Antennas
(2012-03-16)
Lin, Chih-Che
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Wang, Shie-Yuan
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Hsu, Teng-Wei
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資訊工程學系
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Department of Computer Science
The IEEE 802.16(d) mesh coordinated distributed scheduling (CDS) mode is a novel technology for future fixed wireless backbone networks and designed for the use of omnidirectional antennas. The use of Single-Switched-Beam Antennas (SSBAs) may have great potential to increase network capacity due to the antenna directivity. However, a network designed for omnidirectional antennas usually cannot operate well or achieve good performance with the presence of antenna directivity. In this paper, we review the designs of the IEEE 802.16 mesh CDS-mode network, study the issues of this network with the use of Single-Switched-Beam Antennas (SSBAs), and propose a complete solution to solve these issues. The performances of our proposed scheme is evaluated using simulations. The simulation results show that our proposed scheme can effectively solve the issues of using SSBAs in the IEEE 802.16 mesh CDS-mode network and greatly increase its network capacity. (C) 2011 Elsevier B.V. All rights reserved.
Significant predictors of overall survival in patients with hepatocellular carcinoma after surgical resection
(2018-09-04)
Lin, Chih-Wen
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Chen, Yaw-Sen
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Lin, Chih-Che
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Lee, Po-Huang
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Lo, Gin-Ho
Background The predictive factors of overall survival after hepatectomy for HCC remain controversial and need to be investigated. Methods In total, 535 consecutive HCC patients undergoing resection were included and their clinicopathological data and overall survival were recorded. Both the tumor and adjacent nontumor (ANT) tissues were subjected to immunohistochemistry analysis for the expression of autophagy-related markers. Results Death was observed for 219 patients, and the cumulative overall survival rates at 1, 3, 5 and 7 years were 91.0%, 72.3%, 58.8%, and 27.7%, respectively. In the multivariate analysis, mortality was significantly associated with the following: diminished LC3 expression in both the tumor and ANT tissues, in the HCC tissues alone and in the ANT tissues alone (hazard ratio/95% confidence interval: 6.74/2.052 +/- 22.19, 6.70/1.321 +/- 33.98 and 2.58/1.499 +/- 4.915, respectively); recurrent HCC (5.11/3.136 +/- 8.342); HBV infection (2.75/1.574 +/- 4.784); cirrhosis (1.78/1.059 +/- 2.974); and antiviral therapy (0.42/0.250 +/- 0.697). The 5-year overall survival rates were 70.2%, 57.3%, 49.6% and 10.7% for patients with positive LC3 expression in both tissue types, in the HCC tissues alone, in the ANT tissues alone, and in neither tissue type, respectively. The 5-year overall survival rates were 56.7%, 47.3%, 51.2% and 38.7% for patients with HBV-related HCC, cirrhosis, no antiviral therapy, and recurrent HCC, respectively, and these rates were significantly lower than those in their counterparts. Conclusions Patients with recurrent HCC, HBV-related HCC, cirrhosis, and the absence of antiviral therapy showed significantly lower overall survival rates. Furthermore, LC3 expression in both the tumor and liver microenvironments were significantly predictive of overall survival after resection for HCC.
The Effects of Underlying Physical Network Topologies on Peer-to-peer Application Performances
(2010)
Wang, Shie-Yuan
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Lin, Chih-Che
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Huang, Chao-Chan
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資訊工程學系
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Department of Computer Science
In this decade, peer-to-peer (P2P) applications have emerged as popular tools for sharing data and they have gained much attention. Such P2P applications build overlay networks on top of existing infrastructure networks and disseminate data in a peer-to-peer manner. How well the P2P overlay network maps onto the underlying physical network topology can significantly impact P2P application performances. In the literature, little work has quantitatively studied the effects of underlying physical network topologies on P2P application performance. In this paper, we used simulations to evaluate the effects of underlying physical network topologies on the performance of the real-life BitTorrent protocol and application. Our results show that underlying physical network topologies significantly affect P2P application performances.