• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10C
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• pp.764-777
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• 2008

In 4G environments, which is the next generation technology for mobile network, it is forecasted that the wireless Internet using a mobile devices such as a mobile phone, PDA will increase because of expansion of Internet and integration of heterogeneous networks. Therefore, we need a Digital ID management technology that can prevent illegal uses and manage private information efficiently in wired and wireless environments. In this paper, we analyze various Digital ID management technologies, and then define requirements of user-centric Digital ID management technology. In addition, we newly propose the authentication mechanism for mobile applications in LTE/SAE network. Finally, we propose the mobile Digital ID Wallet mechanism suitable for 4G environments.

• Journal of Information Technology Services
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• v.11 no.2
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• pp.339-353
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• 2012

Mobile communication technology is advancing forward to deliver more connected devices and richer content and applications. The number of subscriptions continues to grow along with an explosive increase in the mobile data traffic demand. Thereby, it creates a significant network capacity shortage concerns for mobile network operators. In order to address this problem, it is essential to increase the network capacity at a low additional cost. The device-to-device (D2D) communication based proximity service is believed to have a promising future mobile communication technology that is capable to create new mobile service opportunities and offload traffic to the eNB. In addition, it is also required to develop new mobile communication services and its business models not only to accommodate the increasing mobile traffic demand but also to foster profitability of mobile business service providers such as the network providers, contents providers and platform providers. In this article, we first analyze current mobile business eco-system in the context of CPNT based value chain. Then, propose service development framework and business model creation methodologies for the device-to-device communication based services in the beyond LTE/LTE-Advanced systems.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.57-66
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• 2010

In this paper, we propose the reliability constrained resource allocation scheduling algorithm in cellular network for uplink transmission, where uplink transmission is supported via packet switching schemes without the dedicated uplink circuit links. We evaluate the performance of the proposed algorithm, and compared with the conventional works to identify the pros and cons. The proposed uplink scheduling algorithm is to satisfy the constraints requirements of the MTC services which is considered as the core technology for future mobile wireless networks. It is different to conventional works which target to maximize the link capacity. The proposed algorithm provides reliable uplink transmission independent to the location and the quality of the wireless link of the mobile terminal. Based on the performance evaluation results, we conclude that the proposed method provides enhanced reliability performance than conventional works.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.998-1005
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• 2009

In the uplink of OFDMA (Orthogonal Frequency Division Multiple Access) based M-WiMAX(Mobile-Worldwide Interoperability for Microwave Access) system, linear phase shift is caused by signals transmitted from multiuser with different delay time and thus, MAI (Multiple Access Interference) occurs. MAI degrades the performance of ranging code detection and delay time estimation in the uplink. Therefore, in this paper, we propose ranging algorithm, applying SIC (Successive Interference Cancellation) to the conventional ranging algorithm, to minimize MAI and to improve ranging performance. The proposed ranging algorithm is verified through the Monte Carlo simulation, which shows the improved performance of ranging code detection and delay time estimation compared to the conventional algorithms. Through compared with random access of the 3GPP LTE, we can know limit of ranging performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.33-47
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• 2015

Cellular Network assisted device-to-device (D2D) communication has been growing to reduce the overload of eNodeB and mitigate the frequency shortage. However, by sharing the uplink frequency resource with the cellular network, the interference between cellular and D2D is increased. In this paper, we propose an advanced receiver for full suppression cancellation (FSC) to reduce the interference between cellular and D2D. The proposed receiver can suppress and cancel the interference by integrating the interference rejection combining (IRC) technique with successive interference cancellation (SIC). We perform a system level simulation based on the 20-MHz bandwidth of the 3GPP LTE-A system. Simulation results show that the proposed receiver can improve SINR, throughput and spectral efficiency compared to conventional receivers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.15-23
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• 2016

In this paper we presented 4G security models in an open environment. 4G networks have still more security holes and open issues for expert to notice. In here. we show that a number of new security threats to cause unexpected service interruption and disclosure of information will be possible in 4G due mainly to the fact that 4G is an IP-based, heterogeneous network. it tells about the security issues and vulnerabilities present in the above 4G standards.. we try to present several architectures behind 4G infrastructure for example WiMAX and 3GPP LTE architecture. Finally, we point to potential areas for future vulnerabilities and evaluate areas in 4G security which warrant attention. When you make a big dada program, If you use this network architecture then you can improve your learning speed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2085-2094
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• 2012

In this paper, we propose a wireless access network virtualization algorithm based on a digital unit (DU)-radio unit (RU) separated network structure in a cellular network with multiple radio access technologies (RATs). The proposed wireless access network virtualization algorithm consists of a baseline access network virtualization, RAT virtualization, and access path migration algorithms. Final wireless access network virtualization is performed by sequentially performing these procedures. Through system-level simulations which assume 3GPP LTE and WiMAX systems, the performance of the proposed wireless access network virtualization is evaluated in terms of system throughput for two scenarios according to asymmetry of network traffic load. Numerical results show that our proposed wireless access network virtualization algorithm achieves significant system throughput gain even in asymmetric traffic load and user distribution situations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.413-423
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• 2014

With the increasing demands on high data rate, there has been growing interests in multi-input multi-output (MIMO) technology based on spatial multiplexing (SM) since it can transmit independent information in each spatial stream. Recent standards such as 3GPP LTE-advanced and IEEE 802.11ac support up to eight spatial streams, and massive MIMO and mm-wave systems that are expected to be included in beyond 4G systems are considering employment of tens to hundreds of antennas. Since the complexity of the optimum maximum likelihood based detection method increases exponentially with the number of antennas, low-complexity SM MIMO detection becomes more critical as the number of antenna increases. In this paper, we first review the results on the detection schemes for SM MIMO systems. In addition, massive MIMO reception schemes based on simple linear filtering which does not require exponential increment of complexity will be explained, followed by brief description on receiver design for future high dimensional SM MIMO systems.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.5
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• pp.104-112
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• 2017

The CRE (Cell Range Expansion) that selects the small cell with more efficient uplink resources has been developed by 3GPP to relieve the problem of the traffic imbalance due to the power differences between macro and small cells in HetNet. In addition, ABS (Almost Blank Subframes) has been proposed to resolve the signal interference problem due to the operation CREs. This paper proposes an effective method to calculate the ABS ratio by considering the proportion of the number of UEs in CRE and macro cell ranges, as well as the number of small cells in a macro cell. The proposed method has been implemented on the LTESim simulator, and compared with previously proposed methods. The experimental results show that the proposed method can improve the throughput and packet loss ratio performances. In particular, it is also shown that CRE bias values affect those performances, and there exist effective CRE bias values to derive the best performances.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.885-896
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• 2013

MTC(Machine Type Communications), providing a variety of services anytime and anywhere by connecting the cellular network to the machine and things without human intervention, is being considered as a major challenge of the next-generation communications. Currently, When a massive MTC devices simultaneously connect to the network, each MTC device needs an independent access authentication process. Because of this process, authentication signaling congestion and overload problems will cause in LTE-Advanced. In this paper, we propose a group-based authentication protocol and a key management protocol. For managing the MTC devices as group units, the proposed protocol elects a group leader and authentications only once with the core network. After the authentication is completed, a group leader manages the rest members and MME(Mobility Management Entity) by constructing a binary tree. Finally, the propose protocol analysis show that the proposed protocol not only can reduces the authentication signaling which generated in between the MTC devices and the core network but also can manages the MTC devices, efficiently.