• 한국전자통신학회논문지
• /
• 제10권11호
• /
• pp.1257-1264
• /
• 2015

4세대 이동통신인 LTE의 성공적인 도입과 함께 최근 유럽, 중국, 일본 등 주요국은 2020년 5세대 이동통신 상용화를 목표로 기술, 표준화, 시장 주도를 위해 경쟁적으로 연구 개발 및 투자를 본격화하고 있다. 본 논문에서는 5G 이동통신의 향후 발전 방향을 가늠해보기 위해서 현재 국내외에서 진행되고 있는 5G 이동통신시스템의 전반적인 동향과 함께 각 국가에서 설정하고 있는 시스템 요구사항에 대해서 살펴보고자 한다.

• Journal of Communications and Networks
• /
• 제13권1호
• /
• pp.56-62
• /
• 2011

In this paper, we propose a block-based selective orthogonal frequency division multiplexing (OFDM) decode-and-forward relaying scheme for 4G mobile communication systems. In the scheme, an OFDM symbol is divided into blocks and one relay is selected for each block. Theoretical outage performance and error performance are analyzed and evaluated. A unified outage expression is given for our scheme and the other two schemes and the lower bound of the bit error rate of the three schemes is also obtained. The effect of the coherence bandwidth on the proposed scheme is also investigated. Monte Carlo simulations are carried out to validate our analysis. The scheme can obtain a good tradeoff between complexity and performance and can be used in future 4G mobile communication systems.

• 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 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.

• 한국인터넷방송통신학회논문지
• /
• 제8권3호
• /
• pp.101-113
• /
• 2008

사용자 요구의 다양화와 그에 따른 트래픽 증가 등 현재의 IMT-2000 기반에서 수용할 수 없는 보다 복잡한 이동 멀티미디어 환경이 도래하고 있다. 이러한 이동 멀티미디어 서비스를 원활히 제공하기 위해 ITU-R을 중심으로 한 전 세계 이동통신 업계는 이미 4세대용 시스템 규격 및 개발에 상당한 진전을 보이고 있다. 본 논문에서는 4세대 이동통신용 기술기준을 기존의 35세대인 WiBro의 기술기준을 근간으로 하였다. 향후 이동통신의 전송특성은 상/하향의 비대칭적인 통신 트래픽이 예상된다. 따라서 본 논문에서는 상/하향의 점유주파수 대역폭을 1:3과 1:6인 경우를 고려하여 물리계층 파라미터를 제안하였다. 그리고 모의실험을 통해 검증하였다. 따라서 본 논문의 결과를 4세대 이동통신을 위한 기술기준으로 제안한다.

• 전자통신동향분석
• /
• 제33권5호
• /
• pp.24-32
• /
• 2018

With the advent of new convergence services, the requirements of 5G mobile communication systems are being newly derived. The 5G mobile communication system has been evolving to solve requirements that cannot be satisfied with existing 4G mobile communication systems, such as a high user experience transmission rate, short transmission delay, and high connection density. The evolution of a 5G mobile communication system to meet the new requirements is expected to be dominated by the UDN environment in which a number of small cells are concentrated. The 5G wireless backhaul system, which has advantages in terms of initial installation and operation cost, is expected to be an indispensable choice for connecting many small cells and core networks. This paper therefore looks at the frequency band characteristics and requirements applicable to 5G wireless backhaul systems that can accommodate new situations, and introduces key related technologies that can satisfy the 5G wireless backhaul requirements.. In addition, we describe the research and development trends of a 5G wireless backhaul system that is currently under development.

• 한국통신학회논문지
• /
• 제32권7A호
• /
• pp.730-737
• /
• 2007

사용자 요구의 다양화와 그에 따른 트래픽 증가 등 현재의 IMT-2000 기반에서 수용할 수 없는 보다 복잡한 이동 멀티미디어 환경이 도래하고 있다. 이러한 이동 멀티미디어 서비스를 원활히 제공하기 위해 ITU-R을 중심으로 한 전 세계 이동통신 업계는 이미 4세대용 시스템 규격 및 개발에 상당한 진전을 보이고 있다. 본 논문에서는 4세대 이동통신용 기술기준을 기존의 3.5세대인 WiBro의 기술기준을 근간으로 하여, 주요 기술기준 파라메터를 분석하였다. 또한 주요 기술기준 중 송 수신측의 공통요소인, 점유주파수 대역폭을 WiBro의 기술기준을 참고하여 도출하였으며, 모의실험을 통해 검증하였다. 따라서 본 논문의 결과를 4세대 이동통신용 점유주파수 대역폭으로 제안한다.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
• /
• pp.525-530
• /
• 2008

There are a few core technologies to enable high-performance $4^{th}$ generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate transmission such as Mobile WiMAX and WLAN. Efficient decrease of inter-carrier interference (ISI) and inter-carrier interference (ICI) are the reasons for why OFDM is suitable for high-performance transmission, 4G mobile communication. In this paper, we mainly focus on two of objects, combination between MIMO and OFDM, and OFDM channel simulator using Ray-tracing algorithm. The results of this paper can be used implementation of a Wireless Software Platform for 4G Mobile Communication Systems.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권2호
• /
• pp.369-390
• /
• 2023

Technologies for disaster management are highly sought areas for research and commercial deployment. Landslides, Flood, cyclones, earthquakes, forest fires and road/train accidents are some causes of disasters. Capturing video and accessing data in real time from the disaster site can help first responders make split second decisions which may save human lives and valuable resource destructions. In this context the communication technologies performing the task should have high bandwidth and low latency which only 5G can deliver. But unfortunately in India, deployment of the 5G mobile communication systems is yet to give a shape and again in remote areas unavailability of 4G signals is still severe. In this situation the authors have proposed, simulated and experimented a 4G-5G communication scheme where from the disaster site the signals will be transmitted by a 5G terminal to a nearby 4G-5G gateway installed in a mobile vehicle. The received 5G signal will be further relayed by the 4G-5G gateway to the fixed 4G base station for onward transmission towards the disaster management station for decision making, deployment and relief monitoring. The 4G-5G gateway acts as a relay and converter of 5G signal to 4G signal and vice versa. This relayed system can be further mounted on a vehicle mounted relay (VMR) as proposed by 3GPP in Release 18. The scheme is also in the same line of context with Verizon's, "Tactical Humanitarian Operations Response" (THOR) vehicle concept. The performance of the link is studied in different channel conditions, the throughput achieved is superb. The authors have implemented the above mentioned system towards smart campus networking and monitoring landslides activities which are common in their regions.

• 한국전자통신학회논문지
• /
• 제7권1호
• /
• pp.135-139
• /
• 2012

LTE (long-term evolution) 를 비롯한 4G 이동통신 기지국 시스템에 있어서 최근에 DU(digital unit)와 RU(radio unit) 로 분리된 형상의 기지국들이 많이 등장하고 있다. 이러한 형태의 기지국에서 DU 는 전화국사에 설치하고 RU 는 옥외에 설치하는 형태로서, DU와 RU 간의 분리 가능한 거리는 이동통신 망 설계를 하는데 있어서 매우 중요한 요소가 된다. 하지만, DU와 RU 간 허용거리는 이동통신의 물리계층 기술에 의해 제약을 받을 수 있다. 본 논문에서는 FDD (frequency division duplexing) 기반의 4G 이동통신 시스템에서 Closed-Loop MIMO (multiple input multiple output) 기술에 의해 제한되는 DU와 RU 간 한계거리에 대해 분석하였다. DU와 RU 간 한계거리는 이동통신 시스템의 동작 주파수에 따라 다른 결과를 나타내며, 2 GHz의 동작주파수를 가정할 경우에는 약 11 km의 한계거리를 가지는 것으로 분석되었다.