• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.73-79
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• 2004

While CDMA systems are proven to be excellent solutions for cellular communications, they suffer from severe multi-path interferences and are unable to support high-data-rate transmissions over frequency-selective fading channels. This paper introduces a novel downlink transmission method for next generation mobile communication systems. The proposed method allows frequency-domain equalization at the receiver while maintaining the compatibility with the 3rdgeneration CDMA systems.

• Information and Communications Magazine
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• v.25 no.9
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• pp.49-56
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• 2008

본고에서는 3G 이후 망에 대한 사업자 요구 사항 및 요구 사항을 만족시키기 위해서 필요한 기능 등을 논의하고 관련 논의를 실제 표준화 기구에 반영하기 위해 주요 사업자 중심으로 결성 된 NGMN (Next Generation Mobile Network)의 활동 상황을 살펴보고 NGMN에서 LTE 및 SAE 관련 논의진행 현황과 향후 과제 등을 점검해 본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1303-1309
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• 2012

In this paper, we propose a handover scheme for seamless mobile multicast service in next generation access networks. For this, we drew optimum handover scheme when applying MIP(mobile IP), FMIP(Fast MIP), HMIP(Heterogeneous MIP), PMIP(Proxy MIP) to XG-PON1. And, we analyze handover scheme for seamless mobile multicast service in XG-PON1. The prosed handover scheme remove tunnel convergence and reduces handover delay, packet delivery cost.

• ETRI Journal
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• v.28 no.4
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• pp.435-443
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• 2006

This paper presents an efficient carrier recovery algorithm combined with a turbo-coding technique in a mobile communication system. By using a block turbo code made up of independently decodable block codes, we can efficiently recover the fast time-varying carrier phase as well as correct channel errors. Our simulation results reveal that the proposed scheme can accommodate mobiles with high speed, and at the same time can reduce the number of iterations to lock the phase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1283-1293
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• 1996

This paper descries design concepts, structure and charracteristics of personal communications system based on wideband CDMA under developing for general low-tier mobile telecommunications services as the first step of the next generation mobile telecommunications systems that provide timely exchange of various types of information with anyone, from anywhere, at anytime. Also, wedesign a reverse linktransmitter/receiver structure for personal communications system based on wideband CDMA and validata the performance of the designed structure and establish the each parameter via computer simulation. Simulaation results on the effects of reverse link synchronous transmission and the effects of power control and control and channel coding in pedestrian environment for low-tier services are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.6
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• pp.454-472
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• 2013

The development of wireless network technology and the increasing use of wireless networks to mobile users with a variety of wireless network systems has arisen. Wireless sensor networks, they can be nested together, and the need to switch between the network, depending on your needs. Next Generation Wireless Networks(NGWN) gives the mobile user a wide coverage and optimized service etc. Previous hand off management protocol is not enough to secure support of the NGWN application program. Cross-layer Handoff(CLH) protocol technique has been developed to support between and inside networks of handoff management of NGWN. CLH supports mobility management in a wireless network environment and also utilizes mobility speed and handoff signaling delay information to improve the handoff performance ability. For the analysis of handoff performance ability, we analyzed sensitivity of link layer and network layer, therefore, CLH technique is suggested based on this analysis.

• Journal of Satellite, Information and Communications
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• v.4 no.1
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• pp.1-7
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• 2009

As the information age comes out, the aspect of future war brings about the many changes in terms of war-fighting environment. Accordingly, information superiority and intelligence-centric warfare have been important and new war-fighting concept such as NCW(network centric warfare) have been turned up. This paper proposed all-weather core-strategy communications systems guaranteeing not only the real-time transmission of the information collected in a battlefield and expansion, automation, and rapidity of a battlefield but also broadband, mobility, survivability, and flexibility. The proposed military satellite communications system is classified into wideband mass capacity link, survivability, and the system supporting OTM(on the move) communication for the real-time transmission of battlefield information. This paper analyzed the essential operation concepts and core schemes of the U.S. Army's next generation system, TSAT(Transformational Satellite Communication System). Base on the analysis results, this paper proposed that the architecture of next generation military satellite communications systems for NCW have to provide the data rate, anti-jamming capability, network control and management capability which are optimally adaptable for the wireless channel environments such as jamming and interference and to support the variety of platforms like high-speed mobile vehicles, micromini devices, super-high speed unmanned aerial vehicles. Finally, this paper also proposed that next generation military satellite communications systems need the technologies such as the adaptable multi-antenna, laser link, and next-generation anti-jamming waveform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.544-550
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• 2006

Next-generation wireless/mobile networks are envisioned to have an IP-based infrastructure. One of the research challenges for next-generation all IP-based networks is the design of intelligent mobility management technologies that have a seamless mobility and minimal signaling overhead. Recently, HMIPv6 was proposed by the IETF for efficient mobility management. HMIPv6 reduces the amount of signaling and improves the performance of MIPv6 in terms of handover latency. However the MAP can be a single point of performance bottleneck when there are a lot of local movements. HMIPv6 can cause signaling overhead due to the unnecessary location update of idle mobile nodes. Therefore, in this paper, we propose the dynamic paging Mobile IPv6 that reduces the signaling cost of the unnecessary location updates using IP paging and organizes dynamically optimal MAP area according to user's mobility and traffic. We show performance results that are obtained from the average total location update cost and packet delivery cost.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.63-65
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• 2006

As OFDM-based systems exhibits robustness over wireless channel, it is possible to consider them the next generation of the wireless communications including the mobile communications. However, there is a critical point that OFDM-based systems can receive the distorted signal due to the frequency-offset. Therefore, it is necessary to accurately estimate the frequency-offset for OFDM-based systems to be adopted as the next wireless communication systems. In this paper, the efficient frequency-offset estimation scheme based on MUSIC is presented in 802,1la WLAN systems. As shown in the simulation result, this scheme can improve and optimize the estimation performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3133-3151
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• 2012

The optimal price strategy selection of two bounded rational cognitive mobile virtual network operators (MVNOs) in a duopoly spectrum sharing market is investigated. The bounded rational operators dynamically compete to sell the leased spectrum to secondary users in order to maximize their profits. Meanwhile, the secondary users' heterogeneous preferences to rate and price are taken into consideration. The evolutionary game theory (EGT) is employed to model the dynamic price strategy selection of the MVNOs taking into account the response of the secondary users. The behavior dynamics and the evolutionary stable strategy (ESS) of the operators are derived via replicated dynamics. Furthermore, a reward and punishment mechanism is developed to optimize the performance of the operators. Numerical results show that the proposed evolutionary algorithm is convergent to the ESS, and the incentive mechanism increases the profits of the operators. It may provide some insight about the optimal price strategy selection for MVNOs in the next generation cognitive wireless networks.