• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제2권4호
• /
• pp.171-183
• /
• 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 information and communication convergence engineering
• /
• 제2권4호
• /
• pp.209-213
• /
• 2004

With the commercialization of CDMA 2000-1x late in 2000, a high-speed wireless Internet, based on a mobile communication networks, appeared in Korea. This will develop into the next-generation of mobile communications(4G) in the future and the new cell layout will be required the cellular configuration of 4G. We would need the legislation with respect to base-stations and to building the mobile communication networks, as well as the optimization of mobile communication systems. In this study, in order to provide 4G, I examined and analyzed that the current laws & regulations related to licensing and operating a mobile communication base-stations in KOREA.

• 한국통신학회논문지
• /
• 제37권7B호
• /
• pp.499-504
• /
• 2012

4G 이동통신 기지국에 있어서 최근에 DU (Digital Unit) 와 RU (Radio Unit) 로 분리되는 형상의 기지국이 많이 등장하고 있다. 본 논문에서는 차세대 4G LTE 및 LTE-Advanced 이동통신망에서 DU 와 RU 사이를 연결하는 CPRI (common public radio interface) 링크에 요구되는 통신망의 규격을 살펴보고 이를 WDM-PON 으로 구현하기 위한 요구규격을 분석하여 본 응용 시장에 뛰어들고자 하는 WDM-PON 시스템의 개발목표를 설정하고자 한다.

• International Journal of Internet, Broadcasting and Communication
• /
• 제15권4호
• /
• pp.84-89
• /
• 2023

Recently, the sixth generation (6G) networks have become tremendous research topics. Intelligent reflecting surface (IRS) technologies have been envisioned, to increase spectrum and energy efficiency for the fifth generation (5G) mobile networks, towards the sixth generation (6G) communications. In this paper, especially for the strongest channel gain user, we investigate the bit-error rate (BER) of non-orthogonal multiple access (NOMA) systems with intelligent reflecting surface (IRS). First, we derive a BER expression in a closed-form of Q functions. Second, we investigate the BER performance improvement of IRS NOMA systems over NOMA systems versus the power allocation. Moreover, we analyze the BER performance improvement of IRS NOMA systems over NOMA systems versus the number of IRS devices. In results, NOMA equipped with IRS technologies could play an important role in the paradigm shift from 5G mobile networks to 6G mobile networks.

• Journal of Information Processing Systems
• /
• 제16권4호
• /
• pp.743-749
• /
• 2020

Internet of Things (IoT) is a growing technology along with artificial intelligence (AI) technology. Recently, increasing cases of developing knowledge services using information collected from sensor data have been reported. Communication is required to connect the IoT and AI, and 5G mobile networks have been widely spread recently. IoT, AI services, and 5G mobile networks can be configured and used as sensor-mobile edge-server. The sensor does not send data directly to the server. Instead, the sensor sends data to the mobile edge for quick processing. Subsequently, mobile edge enables the immediate processing of data based on AI technology or by sending data to the server for processing. 5G mobile network technology is used for this data transmission. Therefore, this study examines the challenges, opportunities, and solutions used in each type of technology. To this end, this study addresses clustering, Hyperledger Fabric, data, security, machine vision, convolutional neural network, IoT technology, and resource management of 5G mobile networks.

• 산업기술연구
• /
• 제22권A호
• /
• pp.95-100
• /
• 2002

When the wireless PKI is applied to 3G/4G mobile network which requires mutual authentication among all entities, the wired PKI procedure is not feasible for validating visited network's certifications because of the wireless environmental limitations. Also, if we depend on WAP based PKI, we cannot support confidence about certification validation since the information offered from visited network is not authenticated. Therefore, in this paper we consider various and unique characteristics of mobile environment for certification validation at 3G/4G mobile networks based on wireless PKI and then propose two certification validation procedures.

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (D)
• /
• pp.217-219
• /
• 2006

4G mobile networks are expected to support various multimedia services over IP networks and also satisfy high spectral efficiency requirement. In cellular systems including 4G networks, hotspot cells can occur when available wireless resources at some location are not enough to sustain the needs of users. The hotspot cell can potentially lead to blocked and dropped calls, which can deteriorate the service quality for users. In a 4G mobile network, a band of users enjoying multimedia services can move around, which may generate heavy flows of traffic load. This situation can generate the hotspot cell which has a short life span of only a few minutes. In this paper, we propose a handover-based scheme which can effectively manage hotspot cells in 4G mobile networks. With the scheme, the current serving cell can recognize the load status of the target cell in advance before handover execution. Adaptive handover time control according to the amount of traffic load of cells can effectively and flexibly manage the hotspot cell in the network. And, through our hotspot cell management scheme, acceptable service quality can be supported as users continuously maintain connections with the network. In the simulation results, we find that our scheme generates smaller number of hotspot cells and supports higher service quality than the compared schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제7권10호
• /
• pp.2395-2410
• /
• 2013

Many telecommunication operators around the world have multiple networks. The networks run by each operator are always of different generations, such as 2G and 3G or even 4G systems. Each system has unique characters and specified requirements for optimal operation. It brings about resource allocation problem among these networks for the operator, because the budget of each operator is limited. However, the evaluation of resource allocation among various networks under each operator is missing for long, not to mention resource allocation optimization. The operators are dying for an algorithm to end their blind resource allocation, and the Resource Allocation Optimization Algorithm for Multi-network Operator (RAOAMO) proposed in this paper is what the operators want. RAOAMO evaluates and optimizes resource allocation in the view of overall cost for each operator. It outputs a resource distribution target and corresponding optimization suggestion. Evaluation results show that RAOAMO helps operator save overall cost in various cases.

• Journal of Information Processing Systems
• /
• 제16권4호
• /
• pp.896-914
• /
• 2020

With the rapid growth of network traffic, a large number of connected devices, and higher application services, the traditional network is facing several challenges. In addition to improving the current network architecture and hardware specifications, effective resource management means the development trend of 5G. Although many existing potential technologies have been proposed to solve the some of 5G challenges, such as multiple-input multiple-output (MIMO), software-defined networking (SDN), network functions virtualization (NFV), edge computing, millimeter-wave, etc., research studies in 5G continue to enrich its function and move toward B5G mobile networks. In this paper, focusing on the resource allocation issues of 5G core networks and radio access networks, we address the latest technological developments and discuss the current challenges for resource management in 5G.

• 한국정보과학회논문지:정보통신
• /
• 제35권4호
• /
• pp.355-366
• /
• 2008

본 논문에서는 3G 이동통신망과 WiBro 망간 수직 핸드오버 지원을 위한 mobile SCTP (mSCTP) 핸드오버 기법 적용방안을 제안한다. 제안하는 이종망간 mSCTP 핸드오버 기법의 성능분석을 위해 이동 단말에서 mSCTP 핸드오버를 자동적으로 지원하는 시스템을 개발하였다. 리눅스 기반 테스트베드 실험을 통해 핸드오버 지연 관점에서 성능을 분석하고 실험결과를 Mobile IP 핸드오버 기법과 비교하였다. 실험결과, 이종망간 중첩영역에서 이동 단말의 체류시간이 충분히 클 때 mSCTP 핸드오버 지연시간이 상당히 감소될 수 있고, 또한 Mobile IP 보다 상대적으로 더 좋은 핸드오버 성능을 보여주고 있음을 알 수 있었다.