• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.117-121
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• 2008

In ad hoc network, the scarce energy management of the mobile devices has become a critical issue in order to extend the network lifetime. Therefore, the energy consumption is important in the routing design, otherwise cluster schemes are efficient in energy conserving. For the above reasons, an Energy conserving Context aware Clustering algorithm (ECC) is proposed to establish the network clustering structure, and a routing algorithm is introduced to choose the Optimal Energy Routing Protocol (OERP) path in this paper. Because in ad hoc network, the topology, nodes residual energy and energy consuming rate are dynamic changing. The network system should react continuously and rapidly to the changing conditions, and make corresponding action according different conditions. So we use the context aware computing to actualize the cluster head node, the routing path choosing. In this paper, we consider a novel routing protocol using the cluster schemes to find the optimal energy routing path based on a special topology structure of Resilient Ontology Multicasting Routing Protocol (RODMRP). The RODMRP is one of the hierarchical ad hoc network structure which combines the advantage of the tree based and the mesh based network. This scheme divides the nodes in different level found on the node energy condition, and the clustering is established based on the levels. This protocol considered the residual energy of the nodes and the total consuming energy ratio on the routing path to get the energy efficiently routing. The proposed networks scheme could get better improve the awareness for data to achieve and performance on their clustering establishment and messages transmission. Also, by using the context aware computing, according to the condition and the rules defined, the sensor nodes could adjust their behaviors correspondingly to improve the network routing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2259-2266
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• 2016

Recently dense wireless local area networks (WLANs) emerge as the number of WLAN cells and stations increases. In such dense WLAN environment, this paper proposes a new distributed medium access control (MAC) protocol. The proposed MAC protocol extends the previous CSMA with collision resolution (CSMA/CR) that uses a single collision detection (CD) phase and employs multiple CD phases to resolve more collisions. It checks the collision detection in each CD phase and stops the CD phase if consecutive non-detected CD phases occur more than the threshold. Therefore, the proposed protocol can control the number of CD phases adaptively according to the number of accessing stations and increase the probability of collision resolution while decreasing the packet overhead. The simulation results show that the proposed adaptive CSMA/CR protocol employs a variable number of CD phases according to the number of stations and achieves a greater throughput than the previous CSMA/CR protocol using the fixed number of CD phases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.9
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• pp.548-556
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• 2014

To cope with recently increasing demand for data traffics, heterogeneous networks have been actively studied, where small cells are deployed within a macro cell coverage with the same frequency band. To mitigate the interference from the macro cell to small cells, an enhanced Inter-cell Interference Coordination (eICIC) technique has been proposed, where ABS (Almost Blank Subframe) is used in time domain. However, there is a waste of resource since no data is transmitted in a macro-cell in ABS. In this paper, we propose a new interference management method by using a 3D sector beam based on Active Antenna System (AAS), where Genetic Algorithm (GA) is applied to reduce the antenna gain toward a small-cell. With the proposed scheme, the macro-cell and small cells can transmit data at the same time with the AAS antenna pattern generating reduced interference to small cells. The performance of the proposed scheme is evaluated by using an LTE-Advanced system level simulator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.708-715
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• 2016

Quality of experience (QoE) for multimedia services in macro-femtocell networks is one of the key issues for 5G mobile and wireless communications. A service management structure needs to guarantee the QoE for mobile users based on end-to-end negotiation to support service continuity. Resource management is necessary to maintain the QoE requirements of different multimedia applications, because service continuity may be impeded by delays. This paper proposes four types of resource management scheme to support consistent QoE for different multimedia services. For this purpose, a QoE structure is suggested, and a resource allocation scheme is proposed by utilizing a fixed amount of radio resources reserved for dedicated use to support QoE. Various multimedia services with different requirements (such as voice, image, and data) can be serviced simultaneously, because QoE can be provided under our proposed scheme. Simulation results show that our scheme provides better performance than a conventional scheme with respect to outage probability and total data throughput.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.525-532
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• 2007

Recently, broadband access networks have been competitively deployed all over the world with the development of various multimedia services for such a network. ETRI(Electronics and Telecommunications Research Institute) built the FTTH(Fiber-to-the-Home) service center to develop a next-generation equipment and a high-quality service/platform as well as to promote domestic industry in the field of optical communication. The FTTH service center has a variety of test equipments such as FTTH standard testbed for a BMT(Bench Mark Test), a network operation center, and IPTV service equipments. Also, ETRI deployed a new type of commercial optical access networks cooperating with ISP(Internet service provider). In this paper, we analyzed the quality degradation appeared in QoE(Quality of Experience), when IP data broadcasted from the FTTH service center is transmitted to subscribers through the commercial optical access network. Moreover, we proposed a noble solution to address this problem.

• Journal of Information Processing Systems
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• v.6 no.3
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• pp.269-294
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• 2010

The interconnection of mobile devices in urban environments can open up a lot of vistas for collaboration and content-based services. This will require setting up of a network in an urban environment which not only provides the necessary services to the user but also ensures that the network is secure and energy efficient. In this paper, we propose a secure, energy efficient dynamic routing protocol for heterogeneous wireless sensor networks in urban environments. A decision is made by every node based on various parameters like longevity, distance, battery power which measure the node and link quality to decide the next hop in the route. This ensures that the total load is distributed evenly while conserving the energy of battery-constrained nodes. The protocol also maintains a trusted population for each node through Dynamic Trust Factor (DTF) which ensures secure communication in the environment by gradually isolating the malicious nodes. The results obtained show that the proposed protocol when compared with another energy efficient protocol (MMBCR) and a widely accepted protocol (DSR) gives far better results in terms of energy efficiency. Similarly, it also outdoes a secure protocol (QDV) when it comes to detecting malicious nodes in the network.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.100-113
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• 2018

The Proximity Service, which is one of the most popular network capacity improvement methods, uses the frequency reuse in order to increase the frequency efficiency. As a result, inter-cell interference between cellular and proximity service users occurs at a cell edge. In this paper, we proposed a mitigation scheme for inter-cell interference, where we suggested a new function of and eNB with ProSe function exchanging information about ProSe parameters and ProSe user equipment with neighboring cells via the X2 interface. As the first step, the resource which did not cause the inter-cell interference problem were pre-allocated through the frequency sensing in the ProSe direct discovery. As the next step, the inter-cell interference problem was solved by reallocating appropriate resources based on the ProSe application code, the ProSe application QoS, the ProSe application ID and validity timer in ProSe direct communication.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.695-700
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• 2005

In the sensor network, a lot of sensor nodes are scattered sparsely and organizes a united communication network between each node. After that, environmental information around each sensor node are gathered and analyzed. Because each node operates under resource constraint, the efficiency and hardware specification of a node should be maximized. There exist technical constraints until now but recent technical progress in IC fabrication and wireless network enables to construct a tiny embedded system, which has the properties of low cost, low power consumption, multi functions. Wireless sensor network becomes a modern research field with technical improvements, is studied in numerous laboratories, and is called as diverse different project names - Wireless Integrated Network Sensors (WINS), Mobile Ad hoc NETwork (MANET), Ubiquitous Sensor Network (USN). TinyOS is one of leading project and is widely used. In this paper, we suggest a sensor network, which uses TinyOS platforms and aims for context awareness in a home environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2207-2216
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• 2012

Recently, wireless Internet environment with mobile phones and wireless sensor networks with severe resource restrictions have been actively studied. Moreover, an overall security issues are essential to build a reliable and secure sensor network. One of secure solution is to develop a fast cryptographic algorithm for data encryption. Therefore, we propose a 128-bit stream cipher, AA128 which has efficient implementation of software and hardware and is suitable for real-time applications such as wireless Internet environment with mobile phones, wireless sensor networks and Digital Right Management (DRM). AA128 is stream cipher which consists of 278-bit ASR and non-linear transformation. Non-linear transformation consists of Confusion Function, Nonlinear transformation(SF0 ~ SF3) and Whitening. We show that the proposed stream cipher AA128 is faster than AES and Salsa20, and it satisfies the appropriate security requirements. Our hardware simulation result indicates that the proposed cipher algorithm can satisfy the speed requirements of real-time processing applications.