Browsing by Author "Hsu, Yi-Huai"

Now showing 1 - 16 of 16

A dynamic MBS zone framework for cost-effective inter-MBS zone handover in WiMAX networks
(2016-04)
Lee, Lung-Sheng
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
To synchronize multicast broadcast service (MBS) zone data transmissions, the WiMAX standard defines a coordination mechanism to coordinate data transmissions over the WiMAX network; however, the packet loss recovery procedures, which are parts of the coordination mechanism, enlarge packet transmission latency and packet buffer pool requirement. Therefore, we propose an in-frame control (IFC) scheme to decrease packet error rate and packet retransmission count, so as to reduce the packet transmission latency and packet buffer pool requirement. To support level-2 frame-offset coordination, we also propose a dynamic MBS zone (DMZ) framework that can provide data continuity between any two adjacent MBS zones. Based on the proposed DMZ framework, a seamless dynamic inter-MBS zone handover (called DMZ HO) scheme is proposed to resolve the data discontinuity (or packet loss) problem during inter-MBS zone HO. Compared to the WiMAX standard scheme, the proposed IFC scheme reduces packet error rate and packet retransmission count by 49.8 and 49.73 %, respectively. The proposed DMZ HO scheme also outperforms an overlapping zones (OLZ) scheme in terms of channel occupation time and channel bandwidth consumption (in terms of channel idle ratio). Therefore, by resolving data discontinuity, the proposed DMZ HO scheme is more cost-effective and more feasible in providing smooth multimedia content delivery services without disruption to multiple mobile stations (MSs) during HO, and thus will enhance user experience.
A Fast Consensus Algorithm for Multiple Controllers in Software-Defined Networks
(2016)
Ho, Chia-Chen
;
Wang, Kuochcn
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
Multiple SDN controllers architecture has been proposed to improve the scalability problem and to avoid a single point of failure. One major issue in the SDN multiple controllers architecture is how to reach a consistent network state among SDN controllers. In order to resolve the above issue and to make sure that all controllers have the same network state and the whole network becomes consistent, an efficient consensus mechanism to synchronize the control state of each controller is required. In view of this, we propose a Fast Paxos-based Consensus algorithm (FPC) which provides strong consistency. The proposed FPC uses a controller priority mechanism to guarantee a proposal must be elected in each round and no additional round is needed even more than two proposers get the same votes. Using Estinet, simulation results have shown that the proposed FPC has lower average consensus time (35.3% lower) than Raft. With a low consensus time, the proposed FPC can improve the data store access performance (26.0% faster at retrieving data and 59.7% faster at storing data via the REST API comparing with the Raft). Therefore, the proposed FPC is feasible for multiple SDN controller networks.
A Fast Window-based Scalar Multiplication Algorithm for Elliptic Curve Cryptography in Wireless Sensor Networks
(2015-01-01)
Ye, Hung-Nan
;
Wang, Kuochen
;
Jan, Rong-Hong
;
Hu, Yuh-Jyh
;
Tseng, Yu-Chee
In this paper, we propose an enhanced window-based mutual opposite form (EW-MOF) for scalar multiplication with ECC in WSNs. The proposed EW-MOF combines MOF with an enhanced window method that can reduce not only pre-computation time and memory usage, but also average key generation time that includes pre-computation time in each sensor node. Our analysis has shown that the proposed EW-MOF requires a smaller number of essential pre-computed points than the one's complement. Therefore, it is very suitable for WSNs. Simulation results show that the proposed EW-MOF is 24.69% faster than the one's complement method, which is the best method available, in the average key generation time of ECC that includes pre-computation time under different field sizes. In summary, the proposed EW-MOF is more feasible than the one's complement for wireless sensor networks in terms of key generation time and power saving.
Adaptive Routing for Video Streaming with QoS Support over SDN Networks
(2015)
Yu, Tsung-Feng
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose an adaptive routing approach for video streaming with QoS (Quality of Service) support over Software Defined Networks (SDN), called ARVS. In our approach, base layer packets and enhancement layer packets of video bit streams are treated separately as two levels of QoS flows (level-1 and level-2 QoS flows). During video streaming, if the shortest path does not satisfy the delay variation constraint, the base layer packets have the first priority to be rerouted to a calculated feasible path based on the available bandwidth of this path, and the enhancement layer packets will stay on the shortest path. However, if there is no available bandwidth in this path, the base layer packets will stay on the shortest path while the enhancement layer packets will be rerouted to this path. In this way, the video quality would be enhanced due to the congestion of the shortest path has been mitigated. Simulation results have shown that, compared with OpenQoS, our approach can reduce up to 77.3% of the packet loss rate for the base layer packets of video bit streams and also enhance at least 51.4% coverage under various network loads of the shortest path and the feasible path.
An Adaptive Energy Saving Mechanism for LTE-A Self-Organizing HetNets
(2015)
Hsu, Yi-Huai
;
Wang, Kuochen
;
資訊工程學系
;
Department of Computer Science
Since the information and communication technology industry is one of contributors to global warming, how to utilize self-organizing networks (SONs), which can simplify network management, to achieve energy saving over future cellular networks has been a significant issue. We propose an adaptive energy saving mechanism (AES) for LTE-A self-organizing heterogeneous networks (HetNets). The proposed AES is designed for multi-hop cellular networks, in which each cell has an enhanced Node B (eNB) and multiple relay nodes (RNs). The AES uses two-level multi-threshold load management for each RN under different eNBs (inter-cell level) and for each RN within the same eNB (intra-cell level) so as to reduce the congestion in hot spot eNBs and RNs. In addition, the AES can dynamically switch an RN between active and sleep modes to maximize the number of sleep RNs for adaptive energy saving. It can also dynamically change an RN\'s coverage area to reduce energy consumption and to increase radio resource utilization. Besides, the AES adopts a neural network predictor to forecast the loading of each RN to determine whether it is appropriate to switch an RN to sleep mode. Simulation results show that with slightly sacrificing average throughput (1.16% lower) and radio interface delay (1.4% higher), the proposed AES\'s percentage of sleep RNs is from 0.28 to 0.19 under the percentage of active UEs from 0.7 to 1. Comparing with a representative related work, reinforcement learning (RL), the proposed AES\'s average energy consumption is 26.44% lower than RL\'s.
An Integrated Edge and Fog System for Future Communication Networks
(2018-01-01)
Kuo, Ping-Heng
;
Mourad, Alain
;
Lu, Chenguang
;
Berg, Miguel
;
Duquennoy, Simon
Put together, the edge and fog form a large diverse pool of computing and networking resources from different owners that can be leveraged towards low latency applications as well as for alleviating high traffic volume in future networks including 5G and beyond. This paper sets out a framework for the integration of edge and fog computing and networking leveraging on ongoing specifications by ETSI MEC ISG and the OpenFog Consortium. It also presents the technological gaps that need to be addressed before such an integrated solution can be developed. These noticeably include challenges relating to the volatility of resources, heterogeneity of underlying technologies, virtualization of devices, and security issues. The framework presented is a Launchpad for a complete solution under development by the 5G-CORAL consortium.
Application-aware Resource Allocation for SDN-based Cloud Datacenters
(2013-01-01)
Hong, Weifan
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
In cloud datacenters, since resource requirements change frequently, how to assign and manage resources efficiently while meeting service level agreements (SLAs) of different types of applications is an important research issue. In this paper, we propose an Application-aware Resource Allocation (App-RA) scheme to predict resource requirements and allocate an appropriate number of virtual machines (VMs) for each application in SDN-based cloud datacenters. To the best of our knowledge, the proposed App-RA is the first application-aware resource allocation scheme that adapts to all types of applications. The App-RA can meet SLAs, allocate resources efficiently, and reduce power consumption for each application in cloud datacenters. The proposed App-RA adopts the neural network based predictor to forecast the requirements of resources (CPU, Memory, GPU, Disk I/O and bandwidth) for an application. In the proposed App-RA, we have designed two algorithms which allocate appropriate numbers of virtual machines and use the VM allocation threshold to avoid SLA violations for five different types of applications. In addition, we adopt an SDN-based OpenFlow network with CICQ switches to appropriately schedule packets for different types of application in the network layer. Finally, simulation results show that the power consumption of the proposed App-RA is only 9.21% higher than that of the best case (oracle) and the power consumption of EAACVA, which is a representative resource allocation method for non-graphic applications, is 104.58% worse than that of App-RA. Furthermore, the SLA violation rate of the proposed App-RA is less than 4% for all applications.
Application-aware Routing Scheme for SDN-based Cloud Datacenters
(2015)
Cheng, Li-Chia
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose an Application-aware Routing Scheme (App-RS) to meet network requirements of all classes of applications in SDN-based cloud datacenters. The proposed App-RS takes into account end-to-end delay and link load for real time applications (class 1), delay variation and link load for streaming applications (class 2), and link load for miscellaneous applications (class 3) to improve the performance of all classes of applications. Using Estinet, simulation results have shown that the average bandwidth ratio of class 1, class 2, and class 3 applications of the proposed App-RS are 9.86%, 4.53%, and 4.07% better than that of CORouting, respectively. The average end-to-end delay of class 1 applications of App-RS is 25.47% lower than that of CORouting. The average delay variation of class 2 applications of App-RS is 49.65 % lower than that of CORouting. Therefore, the proposed App-RS can better meet the network requirements of all classes of applications in SDN-based cloud datacenters than CORouting.
Dynamic Load-balanced Path Optimization in SDN-based Data Center Networks
(2016)
Lan, Yuan-Liang
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
We propose a Dynamic Load-balanced Path Optimization (DLPO) algorithm which can suit for different SDN-based data center network topologies. The proposed DLPO changes paths of flows during flow transmissions, achieves load balancing among different links, and efficiently resolves the network congestion problem in SDN-based data center networks. We also propose a priority-based flow table updating strategy to ensure that flows of a congested path will be redirected to a light-loaded path as soon as all flow tables of the associated switches in the light-loaded path have been updated successfully so as to avoid packet loss caused by changing paths of flows. The proposed DLPO is composed of two algorithms, which are multi-link DLPO algorithm and single-link DLPO algorithm. The multi-link DLPO algorithm can balance link loads in a network quickly to resolve some congested paths and the single-link DLPO algorithm can reroute flows to avoid using links with large loads to resolve congested paths that the multi-link DLPO algorithm cannot handle. Simulation results show that, compared to LABERIO, the proposed DLPO increases 18.9% and 9.5% of throughput per flow and bandwidth utilization, respectively, in the fat-tree topology, and 24.8% and 8.3% in the fully populated topology, both under a hot-spot traffic pattern.
Dynamic Resource Provisioning with Hotspot Anticipation for MMOG Clouds
(2015-01-01)
Chang, Yenchih
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
We propose a dynamic resource provisioning with hotspot anticipation scheme, called NN-Player+DRP-HA that employs a finite state machine model to monitor the movement of avatars in a virtual world. Furthermore, we use a finite state machine to represent possible avatar states and state transitions. By combining the state of each avatar in a game zone with a neural network (NN) predictor, we may figure out potential workload produced by hotspots, and then allocate appropriate computing resources to support the game zone. Experimental results support that the proposed NN-Player+DRP-HA scheme can avoid most of under-allocation events with an acceptable over-allocation rate. Compared with a representative dynamic resource provisioning method, called NN-Player+DRP, the proposed NN-Player+DRP-HA reduces the probability of under-allocation events from 2.16% to 0.42% (80% improvement) in terms of CPU capacity of a VM, under the premise of controlling the CPU over-allocation rate within the CPU capacity of one VM.
Efficient cooperative access class barring with load balancing and traffic adaptive radio resource management for M2M communications over LTE-A
(2014-11-14)
Hsu, Yi-Huai
;
Wang, Kuochen
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
We propose two efficient cooperative access class barring with load balancing (CACB-LB) and traffic adaptive radio resource management (TARRM) schemes for M2M communications over LTE-A. The proposed CACB-LB uses the percentage of the number of Machine-Type Communication (MTC) devices that can only access one eNB between two adjacent eNBs as a criterion to allocate those MTC devices that are located in the overlapped coverage area to each eNB. Note that an eNB is a base station of LTE-A. In this way, the proposed CACB-LB can achieve better load balancing among eNBs than CACB, which is the best available related work. The proposed CACB-LB also uses the ratio of the channel quality indication that an MTC device received from an eNB over the number of MTC devices that attach to the eNB as a criterion to adjust the estimated number of MTC devices that may access the eNB. As a result, the proposed CACB-LB can have a better set of barring rates of access class barring than CACB and can reduce random access delay experienced by an MTC device, which is also applicable to user equipment (UE). After an MTC device successfully accesses to an eNB, the eNB needs to allocate radio resources for the MTC device. In addition, the proposed TARRM allocates radio resources for an MTC device based on the random access rate of the MTC device and the amount of data uploaded and downloaded by the MTC device in a homogeneous MTC device network, and the priority of an MTC device in a heterogeneous MTC device network. Furthermore, we use the concept from cognitive radio networks such that if there are unused physical resource blocks (PRBs) of UEs, an eNB can schedule MTC devices to use these PRBs to enhance the throughput performance. Simulation results show that either in a homogeneous MTC device network or in a heterogeneous MTC device network, the proposed CACB-LB\'s average access delay of UEs/MTC devices and average throughput from UEs/MTC devices are better than CACB\'s. The proposed CACB-LB with TARRM\'s average throughput from UEs/MTC devices is also higher than CACB\'s. Therefore, the proposed CACB-LB with TARRM is feasible for M2M communications over LTE-A. (C) 2014 Elsevier B.V. All rights reserved.
Enhanced Cooperative Access Class Barring and Traffic Adaptive Radio Resource Management for M2M Communications over LTE-A
(2013)
Hsu, Yi-Huai
;
Wang, Kuochen
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
We propose enhanced cooperative access class barring (ECACB) and traffic adaptive radio resource management (TARRM) for M2M communications over LTE-A. We use the number of Machine-Type Communication (MTC) devices that attach to an eNB, which is the base station of LTE-A, as a criterion to determine the probability that an MTC device may access the eNB. In this way, we can have a better set of access class barring parameters than CACB, which is the best available related work, so as to reduce random access delay experienced by an MTC device or user equipment (UE). After an MTC device successfully accesses an eNB, the eNB allocates radio resources for the MTC device based on the random access rate of the MTC device and the amount of data uploaded or downloaded by the MTC device. In addition, we use the concept from cognitive radio networks that when there are unused physical resource blocks (PRBs) of UEs, the eNB can schedule MTC devices to use these PRBs to enhance network throughput. Simulation results show that the proposed ECACB's average (worst) access delay of UEs is 33.19% (29.89%) lower than CACB's. Its average (worst) access delay of MTC devices is 12.15% (15.1%) lower than that of CACB. Its average (worst) throughput from UEs is 20.93% (26.44%) higher than that of CACB. Its average (worst) throughput from MTC devices is 19.95% (12.25%) higher than that of CACB. The proposed ECACB+TARRM's average (worst) throughput from UEs is 26.16% (31.42%) higher than CACB's. Its average (worst) throughput from MTC devices is 25.11% (20.76%) higher than that of CACB. To the best of our knowledge, no existing approach integrates access class barring with radio resource management for M2M communications over LTE-A.
Fast Controller Failover for Multi-domain Software-Defined Networks
(2015)
Chan, Yi-Chen
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
We propose a Fast Controller Failover for Multidomain Software-Defined Networks (SDNs) (FCF-M) to handle SDN controller failures. The proposed FCF-M is composed of controller failure detection and switch reassignment. In the controller failure detection, each controller checks the timestamp of its preceding controller. If a controller is failed, its succeeding controller will check its preceding controller. Because a failed controller does not prevent its preceding controller from healthy check, the proposed FCF-M can prevent a single point of failure (SPOF) for healthy check. We also make use of an adaptive timeout delay to reduce failure detection time. In the switch reassignment, when a controller is failed, we need to reassign the switches under the failed controller to an alternative controller. We consider controller load and distance between a switch and a controller to choose an alternative controller for reducing delay. The proposed FCF-M can achieve intra-domain controller failover and inter-domain controller failover. Using EstiNet, simulation results show that the proposed FCF-M outperforms the Devolved controller (DC) in terms of average end-to-end delay and failover time.
Multipath Routing in SDN-based Data Center Networks
(2015)
Lei, Yi-Chih
;
Wang, Kuochen
;
Hsu, Yi-Huai
;
資訊工程學系
;
Department of Computer Science
We propose an SDN-based adaptive worst-fit multipath routing (AWMR) algorithm for Data Center Networks (DCNs) which can select multiple routing paths and determine the number of paths used for a new-coming flow according to the available network resources and the demanded bandwidth of the new-coming flow, instead of using a fixed number of routing paths for each flow. The proposed AWMR is composed of two stages. The first stage of the proposed A WMR finds an initial routing path set that includes paths whose lengths are the shortest between source and destination hosts, and computes available bandwidth of such a path set. The second stage of the proposed AWMR, which utilizes an improved widest disjoint path (iwdp) scheme, then selects the worst-fit paths according to the demanded bandwidth of the new-coming flow. Since the proposed AWMR minimizes the number of routing paths used effectively, the cost of constructing multiple paths can be decreased. Since the proposed AWMR selects multiple paths in a global view rather than in a local view of DFS+worst-fit-link, which is a representative related work, the proposed AWMR can get smaller average end-to-end delay by avoiding the shared bottleneck link problem among multiple paths. Using EstiNet, simulation results show that the proposed A WMR outperforms DFS+worst-fit-link in terms of average end-to-end delay, average throughput per flow, and average packet delivery ratio.
QoS-aware resource management for multimedia traffic report systems over LTE-A
(2016-01-15)
Liu, Tzu-Chin
;
Wang, Kuochen
;
Ku, Chia-Yu
;
Hsu, Yi-Huai
;
資訊工程學系
The multimedia traffic report system is a new type of applications in wireless vehicular networks equipped with sensors. This system can provide various kinds of traffic information, which are directly obtained from on-car sensors and devices via LTE-A. By leveraging LTE-A technologies, the system can support wide-range transmissions and better mobility. Despite of these improvements, the resource management problem is still a challenging issue due to a large number of on-car sensors and devices. Existing resource management studies focus on channel quality or Quality of Service (QoS) requirements for non-vehicular applications. To get the most useful and complete traffic information, including location coverage, an efficient resource management mechanism for multimedia vehicular applications is indispensable. In this paper, we propose a QoS-aware resource management mechanism for multimedia traffic report systems over LTE-A (QoS-MTRS). The main idea is to schedule resources according to the importance degrees of various traffic data. Furthermore, we take channel availability into consideration to make sure that the transmission is feasible. The objective of QoS-MTRS is to improve the diversity, completeness and overall traffic data value under radio resource limitations. We have conducted a system-level simulation that includes an LTE-A network environment to evaluate our design. Simulation results show that the proposed QoS-MTRS is better than BQA (bandwidth and QoS-aware scheduler), Greedy, and FCFS in terms of appearance probability of receiving more than one kind of traffic data types per location block, duplication ratio, overall traffic data value, end-to-end delay, system throughput, location coverage, and flow rejection rate. The significance of this work is the proposed QoS-MTRS can be applied to LTE-A for supporting high-bandwidth demands Internet of Things (IoTs). (C) 2015 Elsevier B.V. All rights reserved.
Self-Organizing Network-based Cell Size Adaption and Traffic Adaptive eICIC in LTE-A HetNets
(2016-11)
Hsu, Yi-Huai
;
Wang, Kuochen
;
資訊工程學系
;
Department of Computer Science
The Long Term Evolution-Advanced (LTE-A) heterogeneous network (HetNet), which can increase the capacity of LTE-A, is composed of high power macrocells and low power picocells. However, unbalanced loading between macro and pico cells and inter-cell interference problems are two major performance bottlenecks in LTE-A heterogeneous networks (HetNets). We propose Self-Organizing Network (SON)-based Cell Size Adaption (SCSA) for load balancing between macro and pico cells and mitigating the inter-cell interference problem. We also propose Traffic Adaptive enhanced Inter-Cell Interference Coordination (TAeICIC) to further mitigate the inter-cell interference problem. The proposed SCSA uses dynamic multi-threshold load management to dynamically set the transmission power of each pico evolved NodeB (eNB) by adjusting the pilot power. In addition, the proposed TAeICIC utilizes a scheduling metric, proportional-fair (PF), which is the estimated throughput based on the channel quality indication (CQI) reported by a user equipment (UE) divided by the estimated long term average throughput achieved by the UE, to dynamically allocate an appropriate number of Almost Blank Subframes (ABSs) in each ABS period in a macrocell so as to mitigate the interference from the macrocell to its adjacent picocells. Simulation results show that the proposed SCSA+ TAeICIC is better than DI, PF-ABS, and IL-ABS in terms of average throughput of eNBs (15.43%, 25.66%, 31.49% improvement, respectively), average throughput of UEs (16.25%, 29.39%, 39.38% improvement, respectively), average radio interface delay of UEs (81.01%, 84.97%, 86.52% improvement, respectively), and average energy consumption per pico eNB (54.38% improvement for each related method). Therefore, the proposed SCSA+ TAeICIC can significantly enhance the Quality of Experience (QoE) of mobile users and reduce the operating expenditure (OPEX) of the operators in LTE-A HetNets.