• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.437-452
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• 2008

IEEE 802.16j MR networks introduce RSs (Relay Stations) within the IEEE 802.16 system in order to enhance the data throughput and extend the coverage. However, the current standardization defines that the BS (Base Station) controls MS's (Mobile Station's) handover, not only it induces the large signaling overhead but also handover latency could increase. In this paper, we propose a handover protocol in the MR networks where the high capability RSs that can process the MS's control functions are deployed. First, we classify the handover scenarios for the MR networks with the high capability RSs. Then, we define the MAC handover procedure, corresponding MAC management messages and the transmission routes for the proposed messages so that an 802.16e MS can perform seamless handover without noticing it is attached to an MR network. The simulation results show that the proposed handover protocol not only reduces the MAC management message overhead transferred through the wireless links compared to IEEE 802.16j/D1, which is the current standard for MR networks, but also performs the rapider and more secure MS handover than IEEE 802.16e and IEEE 802.16j/D1.

• ETRI Journal
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• v.35 no.2
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1199-1202
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• 2007

광대역 무선 액세스 기술에 대한 관심이 증폭되면서, IEEE 802.16 워킹그룹에서는 광대역 무선 도시권 통신망을 정의하였고, 802.16j 태스크그룹에서는 높은 전송 속도와 넓은 커버리지 제공을 위해서 802.16 시스템에 중계기를 도입하는 작업이 진행중이다. 차세대 네트워크 환경에서는 단말의 이동에도 지속적인 서비스를 제공해야 하므로 본 논문에서는 이동 단말과 기지국 간의 통신을 정의하는 802.16e의 핸드오버 절차를 확장하여 802.16j 네트워크에서 단말의 이동성을 제공하기 위한 방안을 정의하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.723-733
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• 2012

In wireless ad hoc networks, packet loss and latency are frequently occurred by movement of node. As the number of transmission hops increases in these networks, the throughput is increasingly deteriorated. In this paper, we design the wireless ad hoc network system based on IEEE 802.16j MMR (Mobile Multi-hop Relay), which improves the network performance. Our wireless ad hoc network system used adaptively the nearest BS and Farthest BS scheduling algorithms for efficient data transmission and chose the optimal path that minimize data loss and latency. In order to evaluate performance of the wireless ad hoc network system based on IEEE 802.16j MMR, we used the LWX (Light Wimax) model of NS-2 simulator. Through the simulation, we analyzed the network performance for various scenarios.

• Journal of Communications and Networks
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• v.10 no.4
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• pp.412-421
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• 2008

We observe simultaneous transmission of relay stations (RSs) allowed in current IEEE 802.16j draft standard for multi-hop relay networks may involve severe interference among the RSs, hence leading to throughput degradation. Allowing only 1/3 of the RSs to simultaneously transmit instead of 1/2 RSs as in the current draft standard reduces the interference but results in reduced throughput. To remedy this problem, we devise schemes to incorporate network coding at link-layer level (decode-and-forward) into the simultaneous transmission of RSs. Data movement is rearranged to maximize coding gain. Formula is derived to dictate exact movement of packets traveling between base station (BS) and mobile stations (MSs) via intermediate RSs. The frame structure in the current IEEE 802.16j draft standard does not allow broadcast needed for network coding. We devise a new frame structure which supports the broadcast. A new R-MAP (pointers to the burst data) is introduced to implement the broadcast. Since our new frame structure is used only for BS to RS or RS to RS communication, our schemes retain backward compatibility with legacy MSs based on IEEE 802.16e standard. Simulation based on simple configuration of RSs shows considerable improvement in terms of system throughput and round trip delay. For a 4-hop relay network with 1 BS and 4 RSs with symmetric traffic in uplink (UL) and downlink (DL), throughput is improved by 49% in DL and by 84% in UL traffic compared with IEEE 802.16j draft standard under the assumption that omni-directional antennae are used in BS and RSs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.1
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• pp.64-77
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• 2013

In this paper, we propose a joint bandwidth allocation and path selection scheme for IEEE 802.16j networks in uplink with cooperative relaying, and we evaluate the performance of the proposed scheme by using OPNET based simulation in hilly terrain with heavy tree density. The proposed scheme maximizes the system throughput in uplink with cooperative relaying in IEEE 802.16j networks. Then, we transform the proposed scheme into multi-dimensional multiple choice knapsack problem (MMKP) based scheme. We also propose uplink throughput maximization scheme and MMKP based scheme without cooperative relaying. We show that the system throughput of the proposed MMKP based scheme is higher than that of link quality based scheme, and cooperative relaying provides higher system throughput than the conventional case without cooperative relaying in uplink.

• Journal of Industrial Technology
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• v.32 no.A
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• pp.3-8
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• 2012

In IEEE 802.16j standard document, two modes about usage of RS are proposed; one is transparent mode to enhance data throughput and the other is non-transparent mode to extend coverage. In this paper, we focus on non-transparent mode and find that the mode also affects data throughput. We analyze data throughput on various RS topology and their extended coverage area in non-transparent mode. From the analysis, we see that higher throughput can be obtained when MR-BS and RS are located distantly.

• Electronics and Telecommunications Trends
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• v.21 no.2 s.98
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• pp.192-199
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• 2006

본 고에서는 IEEE 802.16/와이브로 망에서의 IPv6 적용에 따른 시나리오 및 기존IPv6 프로토콜에 대한 네트워크 이슈들을 기술한다. 이를 위해 먼저 IEEE 802.16 망의 특성 및 IPv6 적용에 따른 문제점들을 분석하고, IPv6 적용 가능한 시나리오를 서비스 방법, 시스템 구조, CS 적용 방법, 프리픽스(prefix) 할당 방법에 따라 구분하여 제안한다. 이를 기준으로 IPv6 이웃 탐색(neighbor discovery), IPv6 패킷 전송, 이동성, 멀티캐스트, 보안 프로토콜 등이 어떠한 제한 및 수정이 요구되는지에 대해 기술한다.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.51-58
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• 2012

In IEEE 802.16j MMR protocol, two modes about usage of RS are proposed; one is transparent mode to enhance data throughput and the other is non-transparent mode to extend coverage. In this paper, we focus on non-transparent mode and find that the mode can also improve data throughput. Therefore, we analyze data throughput on various RS topology and their extended coverage area by simulation in IEEE 802.16j non-transparent mode. We also compare the simulation results with the single MR-BS system of which coverage is extended by higher transmission power. From the comparisons of simulation results, we see that higher throughput can be obtained in the proposed non-transparent mode.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.5
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• pp.510-516
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• 2010

In this paper, a dynamic GTS allocation method of wireless control networks is proposed for the use of factory automation using IEEE 802.15.4 MAC protocol. A superframe of IEEE 802.15.4 is applied to the transmission method of real-time periodic I/O data of wireless control systems within the limited time in factory environment. The method is proposed for efficient transmission of real-time periodic I/O traffic. The simulation results show the average network utilization and available I/O node numbers could be increased by the proposed method.