• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.12
• /
• pp.2301-2306
• /
• 2008

SIP(Session Initiation Protocol) has become an universal standard for multimedia communications for both wired and wireless networks since it has been adopted as a standard protocol for IMS platform in 3GPP standardization organization at November 2000. In this paper, we design and implement a SIP-based softphone client program which provides telephony service between internet users and a call center equipped with VoIP gateway. A softphone client based on PC-to-phone connection should guarantee to provide interoperability with various VoIP gateways and higher portability to be able to operate on different PC environments. The softphone client program in this paper has been developed with SIP 2.0 standard protocol to support interoperability and with JAIN SIP and JMF package to achieve higher portability.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.11 no.6
• /
• pp.631-637
• /
• 2018

In 5G mobile communication, it is necessary to provide different mobility to user equipments(UE) that do not require mobility management or need limited mobility management. In this paper, we propose a two-layer mobility management system that classifies multiple MTC devices with similar mobility levels into c-MTC and m-MTC groups. In order to improve the energy efficiency and service life by reducing the number of control signals generated when TAU is performed, the group header typically performs a Tracking Area Update(TAU) request and adjusts the periodic TAU update period according to the mobility level. The TAU update period of the m-MTC is set to 54 minutes proposed by the 3GPP standard and the c-MTC is set to 12 minutes. Compared to when the UEs perform TAU individually, it is found that the number of control signals decreases by 33% when the MME is not changed and by 49% when the MME is not changed in the m-MTC or c-MTC group.

• KNOM Review
• /
• v.21 no.2
• /
• pp.35-45
• /
• 2018

As Network Slicing functionality gets applied to mobile networking, a mechanism that enables the selection of network slices becomes indispensable. Following the 3GPP Technical Specification for the 5G Architecture, the inclusion of the Network Slice Selection Function (NSSF) in order to leverage the process of slice selection is apparent. However, actual implementation of this network function needs to deal with the dynamic changes of network instances, due to this, a platform that supports the orchestration of Virtual Network Functions (VNF) is required. Our proposed solution include the use of the Central Office Rearchitected as a Data Center (CORD) platform, with the specified profile for mobile networks (M-CORD) that integrates a service orchestrator (XOS) alongside solutions oriented to Software Defined Networking (SDN), Network Function Virtualization (VNF) and virtual machine management through OpenStack, in order to provide the right ecosystem where our implementation of NSSF can obtain slice information dynamically by relying on synchronization between back-end services and network function instances.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.2
• /
• pp.230-238
• /
• 2022

Internet of Things(IoT) is a communication technology that collects information of object remotely and controls the function of object by adding a communication function to object that does not have a communication function. For the IoT, various communication technologies such as Wi-Fi, 3GPP, and Bluetooth are available, and Long Range(LoRa) is communication technologies specialized in the IoT concept. LoRa is a communication technology that support long-distance, low-power, and low-speed communication, and is suitable for collecting information generated form object in remote equipment and controlling equipment. Because of these characteristics, it is used in many application field, and various performance improvement studies are in progress. This paper intends to propose an ultra-long-range LoRa communication module that can be used in a wider range of applications. We design and implement hardware, firmware, and application software for testing to develop ultra-long-range LoRa communication modules. The implemented module will be tested in a real environment to verify its performance and to check its utilization.

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

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.752-757
• /
• 2016

Machine to Machine (M2M) communications is communications between a business application and devices via a communication network without any direct human interaction. The aim of our research is to connect any M2M device with an M2M AS (Application server) through an IMS (IP Multimedia Subsystem) Network Core using a M2M Gateway, in order to develop an M2M Horizontal Services Platform over IMS. An IP Multimedia Subsystem (IMS) is an architectural framework defined by the wireless standards body of the 3rd Generation Partnership Project (3GPP) for delivering IP multimedia services to mobile users. This paper shows the design and implementation of a Horizontal M2M Network Services Platform over an IP Multimedia Subsystem (IMS) using the Message Session Relay Protocol (MSRP). We summarize the protocols and architectures that formed the basis for the creation of our architecture. We provide a detailed description of our architecture design, describing the call flow of the proposed architecture and the entities operating in each process. We also describe the design and implementation process detailing the different tools used, explaining the selection of each component and its importance; also how we designed and implemented the M2M gateway, M2M Application Server, Open IMS Core, business application and M2M devices.

• Electronics and Telecommunications Trends
• /
• v.21 no.3 s.99
• /
• pp.36-47
• /
• 2006

이동통신 시스템은 점차 고품질 및 고속의 멀티미디어 서비스를 제공하는 방향으로 가고 있다. 3GPP에서는 기존의 WCDMA 기반의 3세대 이동통신 시스템의 기술적 한계를 극복하기 위해 2004년 말에 3rd Generation Long Term Evolution(3G LTE) Plan을 발표하고, 2006년 6월까지 Technical Report 규격을 작성완료하고 2007년 6월까지 Technical Standard 작성완료를 목표로 2005년 초부터 규격 작업을 수행하고 있다. 본 고에서는 3G LTE 물리계층 및 MAC 계층의 기술 표준화 동향을 살펴본다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2001.06a
• /
• pp.256-260
• /
• 2001

본 논문은 광대역 무선통신환경에서 3GPP(3rd Generation Partnership Project)에 기반한 비동기 IMT-2000 시스템의 송수신 시스템을 구성하여 기지국의 수신성능을 분석하였다. 이동국과 기지국간의 Uplink 채널 환경을 고려하였으며, 기지국의 수신신호는 다중경로 페이딩(Multi-path Fading)과 다중접속간섭(Mult Access Interference : MAI)의 영향으로 성능일 열화된다. 이에 대한 대책으로 Array 안테나를 채용하였을 경우와 MRC-Diversity(Maximal Combining Diversity)를 채용하였을 경우의 수신성능을 동일한 환경에서 비교 분석하였으며, 각각의 시스템에 간섭제거기를 직렬로 비교분석하였다. 본 논문에서 적용한 Array 안테나는 수신 신호의 방향에 따라 적응적으로 추적하여 수신 SNR(Singnal-to-Noise power Ratio)을 최대로 형성하여 시스템의 성능을 개선하는 기법이며, 안테나의 방향성(Directivity :D=2.67)을 이용하는 3-element Array 안테나를 채용하였다. 최대비 합성 다이버시티 기법은 다이버시티 기법 중 수신효율이 가장 좋으며 가지수(L=2)를 함수를 사용하였다. 성능분석 결과 다중경로 페이딩과 다중접속간섭 환경에서 최대비 합성 다이버시티 기법이 Array 안테나보다 수신효율이 우수하였다.

• Electronics and Telecommunications Trends
• /
• v.16 no.1 s.67
• /
• pp.1-9
• /
• 2001

오늘날 이동통신 시대를 맞이하여 사용자에게 Anywhere, Anytime, Anybody, 그리고 Anyplace(4A) 조건을 보장해 주는 3세대인 Universal Mobile Telecommunication System/International Mobile Telecommuni-cation-2000(UMTS/IMT-2000) 비동기 시스템은 기존의 여러 종류의 서비스를 제공하기 위하여 개선된 무선 접속으로 다양한 이동 환경 하에서 여러 가입자에게 다양한 서비스를 제공하는 것을 목표로 하고 있다. 이와 같이 UMTS/IMT-2000 비동기 시스템에서는 저속의 음성에서 2Mbps까지의 전송속도를 가지는 데이터, 영상 등의 멀티미디어 서비스와 이동 가입자에게 전 세계 어디를 가든 통화할 수 있는 국제 로밍 서비스를 제공하여야 한다. 본 고에서는 UMTS/IMT-2000 기반인 Third Generation Project Partnership(3GPP)의 제3세대 이동통신망인 UMTS에 대하여 살펴 본 후 최대 2Mbps급의 트래픽 및 실시간 멀티미디어 응용을 위한 개선된 QoS를 지원하는 UMTS Terrestrial Radio Access Network (UTRAN)의 구조를 기술하였다. 특히, 기지국 및 핵심망과 접속되는 무선망 제어국의 구조, 특성, 그리고 기능에 대하여 논하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.12A
• /
• pp.1836-1842
• /
• 2000

이 논문은 레일레이 감쇄 채널 환경에서 IMT-2000 파일럿 심볼 구조의 W-CDMA 시스템 역방향 링크의 채널 추정에 관한 LMS 적용형 알고리즘 성능을 WMSA(Weighted Multi-Slot Averaging)(K=1,2,3), 일정 추정이득 (Constant estimation gain) 및 RLS 알고리즘 성능과 비교 분석하였다. 이 논문의 모형은 IMT-2000 3GPP 규격의 W-CDMA 채널 구조, 변조 및 파일럿 패턴을 이용하였다. 파일럿 심볼 위치의 채널추정은 LMS 알고리즘을 이용하고 데이터 심볼 위치의 채널보상은 선형 보간으로 수행하였다. 저속 도플러 주파수에서는 WMSA(K=1,2,3) 성능이 일정 추정이득, RLS 및 LMS 적응형 알고리즘 성능보다 우수하며, WMSA(K=1) 성능의 경우 일정 추정이득, RLS 및 LMS 적응형 알고리듬 성능과는 큰 차이가 없다. 그리고 LMS 알고리즘 성능은 WMSA(K=1) 성능과 매우 비슷한 결과를 얻었다. 그러나 도플러 주파수가 고속화될수록 LMS 알고리즘의 성능이 WMSA(K=1), 일정 추정이득 및 RLS 알고리즘 성능보다 우수함을 확인하였다.