• Journal of Korea Society of Industrial Information Systems
• /
• v.17 no.1
• /
• pp.31-38
• /
• 2012

Next generation cellular applications and smart phone usage generate very heavy wireless data traffic. It becomes ineluctable for mobile network operators to have multiple core network entities such as Serving Gateway and Packet Data Network Gateway in 4G-LTE to share this high traffic generated. A typical configuration consists of multiple serving gateways behind a load-balancer which would determine which serving gateway would service a end-users'request. Such hardware is expensive, has a rigid policy set, and is a single point of failure. Another perspective of today's increasingly high data traffic is that besides it is being widely accepted that the high bandwidth L TE provides is creating bottlenecks for service providers by the increasing user bandwidth demands without creating any corresponding revenue improvements, a hidden problem that is also passively advancing on the newly emerging 4G-LTE that may need more immediate attention is the network signaling traffic, also known as the control-plane traffic that is generated by the applications developed for smartphones and tablets. With this as starting point, in this paper, we propose a solution, by a new approach considering OpenFlow switch connected to a controller, which gains flexibility in policy, costs less, and has the potential to be more robust to failure with future generations of switches. This also solves the problem of scaling the control-plane traffic that is imperative to preserve revenue and ensure customer satisfaction. Thus, with the proposed architecture with OpenFlow, mobile network operators could manipulate the traffic generated by the control-plane signaling separated from the data-plane, besides also reducing the cost in installing multiple core-network entities.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.410-414
• /
• 2006

In the present, Orthogonal Frequency Division Multiple Access (OFDMA) that wireless access scheme for high speed data transmission is noticed in mobile communication market and OFDMA/TDD scheme will be used combining Time Division Duplex (TDD) scheme based on OFDMA. The Base Station's receiver synchronizes the symbol timing to anyone user's symbol and the other user's symbols have some Symbol Timing Offset (STO). Linear phase shift is occurred by each user's STO in an OFDMA symbol and the Multiple Access Interference (MAI) caused by the summation of each user's linear phase shift degrades the performance of ranging code detection. In this paper, we analyze the ranging code detection performance for each users STO in OFDMA/TDD system. Simulation results show that the more users access and mobile speed increase, the more ranging code detection performance degrades.

• Journal of IKEEE
• /
• v.4 no.2 s.7
• /
• pp.281-287
• /
• 2000

A mobile ad-hoc network is composed of only mobile nodes, which are distributed dynamically, without any wired backbone or centralized entities. Since the existing works on ad-hoc routing protocol are mostly biased toward a military application, we need a new routing scheme for a support of multimedia services in mobile ad-hoc networks. Therefore, we propose a novel scheme that can support a variety of traffic attributes and can be applicable to high-speed and multimedia data services in mobile ad-hoc networks by using adaptive transmission power level. As a result of simulation, the proposed scheme has better performance than conventional method, which is performed with uniform transmission power level, in view of route query delay time.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.3
• /
• pp.1047-1062
• /
• 2018

In this paper the problem of massive multiple input multiple output (MIMO) channel estimation with sparsity aware adaptive algorithms for $5^{th}$ generation mobile systems is investigated. These channels are shown to be non-stationary along with being sparse. Non-stationarity is a feature that implies channel taps change with time. Up until now most of the adaptive algorithms that have been presented for channel estimation, have only considered sparsity and very few of them have been tested in non-stationary conditions. Therefore we investigate the performance of several newly proposed sparsity aware algorithms in these conditions and finally propose an enhanced version of RZA-LMS/F algorithm with variable threshold namely VT-RZA-LMS/F. The results show that this algorithm has better performance than all other algorithms for the next generation channel estimation problems, especially when the non-stationarity gets high. Overall, in this paper for the first time, we estimate a non-stationary Rayleigh fading channel with sparsity aware algorithms and show that by increasing non-stationarity, the estimation performance declines.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.8
• /
• pp.831-840
• /
• 2013

In this paper, we analyze the telecom services and their socio-economic value for sharing spectrum, which is suitable to access. For this, we suggest a concept and a classification model of sharing spectrum and make a survey for analyzing the socio-economic value of spectrum, 910 MHz which is candidated for sharing between 1.4~4.5 GHz in Korea. Also, we propose mobile telecom service, WiFi, ASA, public service, M2M, and smart home and factory service as service for suitable to sharing spectrum.

• Journal of the Korea Society of Computer and Information
• /
• v.22 no.4
• /
• pp.67-74
• /
• 2017

The objective of this paper is to design broadband microstrip patch antenna for mobile communication service. The enhanced features were confirmed and proved by comparing the proposed antenna with the antennae that have been reported in the relevant literatures. The experimental results show that the impedance bandwidth(VSWR ${\leq}2$) of 19.6%(fo=1,920MHz) and the peak gain of 5.53dBi(at 1,900MHz) were obtained by the mobile communication service frequency band. The proposed antenna had the impedance bandwidth of about 3.1% larger than that of the reported microstrip antenna.

• Journal of Korea Multimedia Society
• /
• v.13 no.6
• /
• pp.884-889
• /
• 2010

In this paper, we design a mobile phone based remote control system for PC using SKT WPAN platform and compare the presented platform with that of Windows Mobile. The usability of WPAN is one of the main issues which should be considered for the ubiquitous services. For easy development and easy use of the WPAN applications, SKT WPAN platform provides abstract WPAN APIs and WPAN Application Manager for ubiquitous services. In this paper, we implement a remote control application using the WPAN platform and show the validity of the platform comparing with other platforms. In the implemented application, we use WPAN abstract APIs on the mobile phone side and a general Bluetooth APIs on the PC for a connection between phone and PC. Through the implementation and comparison, we show that the WPAN application can be easily developed with WPAN platform.

• Journal of Korean Institute of Industrial Engineers
• /
• v.27 no.2
• /
• pp.176-180
• /
• 2001

In Korea, the mobile telecommunication service market is expanding rapidly and becoming more competitive. For service providers in such a dynamic environment, it is very important to accurately forecast demand including market potential in order to work out marketing strategies. In this paper, we suggest a general approach to forecast the market potential using a multinomial logit model, which is applied to individual-level market survey data. Then we develop a dynamic market potential model that can adapt to changes in the external environment without requiring further market survey. The proposed model is applied to the mobile telecommunication service market in Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.678-680
• /
• 2012

1970년대 라디오 주파수를 사용하여 컴퓨터 통신 네트워크가 구축된 이후 눈부신 발전을 거듭하여 Personal Computer 뿐만 아니라 Mobile이나 Tablet PC등에서도 인터넷이 가능하다. 이렇게 다양한 매체를 통해 인터넷을 사용함에 따라 보안에 대한 중요성이 높아지고 있다. 하지만 최근 현대 캐피탈이나 농협, 네이트와 같은 해킹 사례를 보면 평문 데이터 사용에 의해 피해가 더욱 확대 되었다. 평문 데이터 사용함에 따라 보안 위협이 커지는데 평문 데이터를 사용하는 이유를 암호화를 사용했을 때보다 QoS 하락 때문이라고 볼 수있다. 이를 해결하기 위해 고정된 인프라에서 잉여 자원인 GPU를 사용하여 암호화를 할 때 QoS 하락을 줄일 수 있을 것이다. 또한 CPU보다는 멀티코어를 사용한 병렬 처리를 활용하여 CPU보다 상대적으로 효율적인 암호화가 가능하다고 생각한다. 본 논문에서는 CPU를 이용한 암호화 처리 속도와 GPU를 이용한 암호화 처리 속도를 비교하여 GPU를 이용한 암호화 처리 가능성을 검토하였다.

• Proceedings of the Korean Society for Quality Management Conference
• /
• 2007.04a
• /
• pp.76-82
• /
• 2007

Upon the basis at the end of March 2005, we have the 38.91 million cellular phone subscribers over the country and the total diffusion rate of the cellular phone is reached up to 76.1%. At this moment, it can be said the most people use it since the demand is still going on. Turning to the operation company, this is serviced by the SK Telecom, LG Telecom, and KTF, and there are at least 7 manufactures producing it including Samsung, LG, KTF ever, Motorola, SKY, Pantac and Curitel, Most users periodically change the service vendor to the others for buying new model or changing the service vendor. It is understood the customer's action occurred by the differences of the brand cognition. In this study, along with some parameters including the difference of the vendor's brand cognition, difference of satisfaction (mobile telecommunication, product), and the possibility to buy the product again, I am going to find out the relationship between the satisfaction of the provider's service