• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.210-216
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• 2004

This paper propose a new structure and procedure that provides fast handover for moving users, who are using real-time applications, in next generation IP networks. This paper also show the excellency of proposed scheme with the delay analysis. The analysis shows that the delay of proposed scheme is lower than existing methods, especially in the situation where the delay between MAP and AR is considerable.

• ETRI Journal
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• v.26 no.5
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• pp.405-412
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• 2004

MC-CDMA, a multicarrier (MC) modulation scheme based on code division multiple access (CDMA), is the most likely candidate for the next generation of mobile radio communications. The rate compatible punctured turbo (RCPT) coded hybrid automatic repeat request (HARQ) has been found to give improved throughput performance in a direct sequence (DS) CDMA system. However, the extent to which the RCPT HARQ improves the throughput performance of an MC-CDMA system has not been fully understood. In this paper, we apply the RCPT HARQ to MC-CDMA and evaluate by computer simulations its performance in a frequency selective Rayleigh fading channel. We found that the performance of RCPT HARQ MC-CDMA is almost insensitive to channel characteristics. The performance can be drastically improved with receive diversity combined with space-time transmit diversity. In addition, the comparison of RCPT HARQ MC-CDMA, orthogonal frequency division multiplexing, and DS-CDMA shows that under similar conditions the throughput of MC-CDMA is the best in a frequency selective fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.60-70
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• 2011

IPTV was introduced as the new growth engine of the broadcasting and telecommunications industry and has experienced a high growth rate as its subscribers exceeded 2 million in early 2010. However there have been some doubts on if the IPTV market will keep current growth drift. One of such suspicions is that IPTV market has not been developed by the competitiveness of IPTV industry itself. In addition, the recent slowdown of subscribers' growth and IPTV players' operating at a loss has been suggested as obstacles to the IPTV market growth. This sort of phenomenon has been brought about by ambiguous proposition of IPTV's own value as well as IPTV service positioning gap. To resolve these problems this study empirically investigates what customers want to get from IPTV service by analyzing switching value of IPTV subscribers. This study also identifies which values must be strategically considered to develop next generation IPTV services, in particular mobile IPTV services. Following the investigation, this study analyzes the possible positioning gap of mobile IPTV. Through this analysis, this study suggests which sort of service values need to be reconciled.

• ETRI Journal
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• v.43 no.4
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• pp.660-673
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• 2021

To efficiently use frequency resources, the next 6th generation mobile communication technology must solve the problem of out-of-band emission (OoBE) of cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM), which is not solved in 5th generation technology. This study describes a new zero insertion technique to replace an existing filtering scheme to solve this internal problem in OFDM signals. In the development of the proposed scheme, a precoder with a two-dimensional structure is first designed by generating a two-dimensional mapper and using the specialty of each matrix. A spectral shaping technique based on zero insertion instead of a long filter is proposed, so it can be applied not only to long OFDM symbols, but also very short ones. The proposed method shows that the transmitted signal is completely blocked at the bandwidth boundaries of signals according to the current standards, and it is confirmed that the proposed scheme is ideal with respect to bit error rate (BER) performance because its BER is the same as that of CP-OFDM. In addition, the proposed scheme can transformed into a real time structure through vectorizing process with minimal complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.454-461
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• 2007

The next-generation computer is the ultra-lightweight mobile computer that communicates with peripheral handhold devices and provides dynamically the services appropriate to user. To provide the dynamic services on the ultra-lightweight mobile computer, security problem for user or computer system information should be solved and security mechanism is necessary for the ultra-lightweight mobile computing environment that has battery limit and low performance. In this paper, the security mechanism on the component based middleware for the ultra-lightweight mobile computer was implemented using RC-5 cipher algorithm and SHA-1 authentication algorithm. The security components are dynamically loaded and executed into the component based middleware on the ultra-lightweight mobile computer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.628-640
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• 2004

The demand for next generation networks can be condensed into always-best-connected, ubiquitous, mobile, all-lP, and converged networks. IPv6 has been introduced for all-IP ubiquitous communications, and vehicles are coming to represent an important communication platform. In this paper. we propose various resource management schemes for in-vehicle mobile networks, which are adaptive to different hardware configurations. We focus on power and wireless bandwidth since they are critical resources for mobile communications. Based on the mobility characteristics of in-vehicle networks, we propose vehicle-aware power saving schemes. The main idea behind these power saving schemes is to adjust mobile router (MR) advertisement interval and binding lifetime. In addition, according to different wireless environments, we propose adaptive bandwidth management schemes using multihoming: best-connected MR selection based on location, and high-data-rate MR selection based on priority By mathematical analysis, it is shown that our schemes save power prominently for both the dormant nodes and active nodes. In addition, simulation results show that proposed multiple mobile router architecture outperforms previous simple redundant router architecture in preserving session and providing sufficient bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.573-587
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• 2003

Due to the growth of mobile communication and the popularization of Internet, it is expected that wired and wireless communication network of the next generation will be integrated and flourished with IP-based. There have been a great deal of research efforts to provide mobile IP service onthe existing lower layer. The location update and the paging scheme is one of the most challenging technical issues for this topic. In this thesis, a paging method based on the distance-based location update scheme is proposed for IP network to support mobility in layer 3. The proposed scheme is implemented and verified with the OPNET.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.888-893
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• 2012

Quality of Service (QoS) provisioning is an important issue in the design of next generation wireless network. In visible light communication (VLC) networks, link switching is a solution to maintain or improve the quality of communication. In this paper, we propose a novel link switching scheme using the location of mobile nodes (MNs). The current serving transmitter uses location history of the MN to find out which neighbor transmitter the MN is approaching. This neighbor transmitter is chosen to inform the MN as the next serving transmitter. The simulation results show that our proposed scheme gains better performance than non-predictive link switching scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.760-770
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• 2011

The existing mobility management schemes do not fully support the next generation network, which is composed of IP-based core network and various access networks. Currently, ETRI has been developing the AIMS (Access Independent Mobility Service) system which satisfies the ITU-T requirements of mobility management in the next generation network. The AIMS system is designed to provide a mobile host with a fast and reliable mobility service among heterogeneous access networks. Recently, many user devices have multiple communication interfaces, e.g., 3G and WLAN, and thus they can make two or more network connections at the same time. In this paper, we design a scheme of flow mobility, i.e., the movement of selected data flows from one access technology to another, to be applied in the AIMS system, and verify the proposed scheme through the NS-3 simulation study. From the simulation results, we can know that the proposed flow mobility scheme can utilize the network resource efficiently in the heterogeneous mobile networks.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.249-250
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• 2008

In the field of mobile communications, load balancing between 3GPP LTE and other networks is expected to be an important topic from the perspective of current technical development. The load balancing technique includes the definition of functions and structures needed to incooperate 3G LTE E-Node B and base-stations designed for heterogeneous networks. The major goal attained from this paper is to ensure an algorithm for the mechanism of load balancing and to achieve a technical leading for the next generation mobile network.