• 한국인터넷방송통신학회논문지
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• 제13권2호
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• pp.77-82
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• 2013

모바일 인터넷 통신 표준인 WiMax2는 PKMv2 프로토콜을 이용한다. PKMv2는 키에 기반한 암호화를 사용하여 통신 기지국과 단말간의 데이터를 보호한다. 따라서 WiMax2 단말 또는 기지국을 개발하는 경우 PKMv2 프로토콜을 구현하여야만 하며, 상호 동작에 대한 적합성 테스트를 통과하여야 한다. 또한 저성능 프로세서를 이용하는 단말의 경우 암호화 모듈의 처리 성능이 WiMax2 통신의 데이터 처리 능력에 병목이 될 수 있으므로 해당 프로세서에서의 암호화 모듈 처리 성능의 적절성을 측정하여야 한다. 본 논문은 이러한 경우에 사용할 수 있는 WiMax2 PKMv2에 따르는 동작성 시험 및 성능 측정 테스트베드를 구현하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권2호
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• pp.63-81
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• 2008

WiMAX has been introduced as a competitive alternative for metropolitan broadband wireless access technologies. It is connection oriented and it can provide very high data rates, large service coverage, and flexible quality of services (QoS). Due to the large number of connections and flexible QoS supported by WiMAX, the uplink access in WiMAX networks is very challenging since the medium access control (MAC) protocol must efficiently manage the bandwidth and related channel allocations. In this paper, we propose and investigate a cost-effective WiMAX bandwidth management scheme, named the WiMAX partial sharing scheme (WPSS), in order to provide good QoS while achieving better bandwidth utilization and network throughput. The proposed bandwidth management scheme is compared with a simple but inefficient scheme, named the WiMAX complete sharing scheme (WCPS). A maximum entropy (ME) based analytical model (MEAM) is proposed for the performance evaluation of the two bandwidth management schemes. The reason for using MEAM for the performance evaluation is that MEAM can efficiently model a large-scale system in which the number of stations or connections is generally very high, while the traditional simulation and analytical (e.g., Markov models) approaches cannot perform well due to the high computation complexity. We model the bandwidth management scheme as a queuing network model (QNM) that consists of interacting multiclass queues for different service classes. Closed form expressions for the state and blocking probability distributions are derived for those schemes. Simulation results verify the MEAM numerical results and show that WPSS can significantly improve the network’s performance compared to WCPS.

• 디지털산업정보학회논문지
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• 제8권1호
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• pp.117-123
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• 2012

This paper implements mobile Worldwide Interoperability for Microwave Access (WiMAX) receiver using Software Defined Radio (SDR) technology. SDR system is difficult to implement on the mobile handset because of restrictions that are computing power and under space constraints. The implemented receiver processes mobile WiMAX software modem on Open Multimedia Application Platform (OMAP) System on Chip (SoC) and Field Programmable Gate Array (FPGA). OMAP SoC is composed of ARM processor and Digital Signal Processor (DSP). ARM processor supports Single Instruction Multiple Data (SIMD) instruction which could operate on a vector of data with a single instruction and DSP is powerful image and video accelerators. For this reason, we suggest the possibility of SDR technology in the mobile handset. In order to verify the performance of the mobile WiMAX receiver, we measure the software modem runtime respectively. The experimental results show that the proposed receiver is able to do real-time signal processing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권4호
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• pp.171-183
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• 2008

Nowadays, wireless packet data services are provided over Wireless MAN (WMAN) at a high data service rate, while 3G cellular networks provide wide-area coverage at a low data service rate. The integration of mobile WiMAX and 3G networks is essential, to serve users requiring both high-speed wireless access as well as wide-area connectivity. In this paper, we propose a cross-layer optimization scheme for a vertical handover between mobile WiMAX and 3G cellular networks. More specifically, L2 (layer 2) and L3 (layer 3) signaling messages for a vertical handover are analyzed and reordered/combined, to optimize the handover procedure. Extensive simulations using ns-2 demonstrate that the proposed scheme enhances the performance of a vertical handover between mobile WiMAX and 3G networks: low handover latency, high TCP throughput, and low UDP packet loss ratio.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1145-1152
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• 2010

현재 해상통신망에는 고속의 데이터 송수신을 위한 경제적인 통신기술이 요구되고 있다. 해상에서는 무선통신에 전적으로 의존할 수밖에 없는 환경으로 인해 취약한 데이터 통신보안에 대한 해결책도 함께 제시되어야 한다. 이 논문에서는 광대역 해상통신망의 위와 같은 현안들을 해결하기 위하여 다중 홉 자율통신망 형성기술 가운데 하나인 WiMAX MMR 기술을 도입하고, 육상과 달리 기지국이 없는 해상 상황에서 안전한 자율망을 형성하기 위해 확장된 프로토콜을 제안한다.

• 한국통신학회논문지
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• 제35권2A호
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• pp.196-201
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• 2010

Measurement of Quality of Service (QoS) parameters and its statistical analysis becomes a key issue for Mobile WiMAX service providers to manage the converged network efficiently and to support end-to-end QoS. In this paper, we investigate the population distribution of end-to-end one-way delay which is the most important QoS parameter in Mobile WiMAX networks. The samples are analyzed with Chi-Square Goodness-of-Fit test, Kolmogorov-Smirnov (K-S), and Anderson-Darling (A-D) test to verify the distribution of parent population. The relation with confidence level and the minimum number of sample size is also performed for logistic distribution. The statistical analysis is a promising approach for measuring the performance Mobile WiMAX networks.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.17-18
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• 2007

Mobile WiMAX technology is the key solution for providing high speed internet services at anytime and anywhere in mobile environments as 3.5th wireless technology between 3rd generation and 4th generation wireless technology, and the service demands shall be rapidly increased in future some years. This paper analyzed the QoS performance of Mobile WiMAX technology recommended by IEEE 802.16e specification under the restricted simulation conditions and environments. The major metrics for analyzing QoS performance of Mobile WiMAX are 1) total packet drop rates; 2) transmission / receive packet sizes; 3) end to end delay in node 2; 4) packet drop rate by mobile terminal mobility.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.454-458
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• 2008

This article describes an interference reduction scheme for Mobile WiMAX in an indoor environment. The feasibility of user deployed femtocells in the same frequency channel as an existing macro cell network is investigated. One of the important requirements for co-channel operation of femtocells such as auto-configuration and self optimization are discussed. In femtocell deployments, leakage of the pilot signal to the outside of a house can result of the higher number of mobility events caused by passing user of macrocell. This interference effect can be minimized by reducing the pilot power using proper scheme. This paper introduces existing auto-configuration method of power control and proposed interference reduction scheme using power control for Mobile WiMAX in an indoor environment.

• 한국통신학회논문지
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• 제34권3B호
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• pp.288-303
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• 2009

In the near future it is foreseen that a genuine multimedia service over the WiMAX system is provided in a worldwide manner by exploiting the QoS technologies introduced in the wireless and wired broadband network. In this work we propose a pricing scheme for the multimedia service over the generic WiMAX system that supports a full QoS functionality. We assume real-time services such as the voice and video as well as the nonreal-time service such as the conventional high-speed data, and we propose a pricing and charging scheme for those services by investigating the inherent characteristics of those services and the multiple-class of QoS-service provided to them. After that we propose a method to compute expected revenue that is obtained from the WiMAX system by using an analytic method to estimate the usage of the bandwidth resources for the different class of services. Via numerical experiment, we verify the implication of the work.

• 인터넷정보학회논문지
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• 제16권6호
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• pp.1-9
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• 2015

본 논문에서는 이기종 네트워크를 구성하는 대표 무선접속 기술인 WiMAX, CDMA, 무선랜 간의 주파수 공유 분석을 수행하였다. 3가지 접속기술은 각기 다른 주파수 대역을 사용하지만 대역외 방사특성으로 인해 타 무선접속 기술에 간섭을 일으킬 수 있다. 따라서 간섭 허용기준을 만족하기 위한 최소 인접채널 간섭률을 산출하고 이를 바탕으로 간섭/피간섭 시스템간의 최소 주파수 이격(보호대역)을 산출하였다. 분석 결과 WiMAX와 무선랜 간에는 적어도 20 MHz의 보호대역, WiMAX와 CDMA시스템 간에는 적어도 15 MHz의 보호대역이 필요함을 확인하였다.