• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1354-1362
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• 2015

Heterogeneous network technology is expected to be a core technology for 5G mobile communications. 5G mobile network would be composed of many base stations even have mobility, then the operator should connect base stations through the wireless backhaul technology. This paper presents Ultra Wide Area Wireless Backhaul Network System with massive array antenna. We conducted link budget analysis for Ultra Wide Area Wireless Backhaul Network and performance analysis of massive array antenna system through the transmission simulator based on beamforming technology. In wide area ($10km^2$) wireless backhaul system composed of massive antenna, we achieved 5 bps/Hz average spectral efficiency with 1 W transmission power per beam.

• ETRI Journal
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• v.42 no.5
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• pp.643-657
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• 2020

Sixth generation will exploit satellite, aerial, and terrestrial platforms jointly to improve radio access capability and unlock the support of on-demand edge cloud services in three-dimensional (3D) space, by incorporating mobile edge computing (MEC) functionalities on aerial platforms and low-orbit satellites. This will extend the MEC support to devices and network elements in the sky and forge a space-borne MEC, enabling intelligent, personalized, and distributed on-demand services. End users will experience the impression of being surrounded by a distributed computer, fulfilling their requests with apparently zero latency. In this paper, we consider an architecture that provides communication, computation, and caching (C3) services on demand, anytime, and everywhere in 3D space, integrating conventional ground (terrestrial) base stations and flying (non-terrestrial) nodes. Given the complexity of the overall network, the C3 resources and management of aerial devices need to be jointly orchestrated via artificial intelligence-based algorithms, exploiting virtualized network functions dynamically deployed in a distributed manner across terrestrial and non-terrestrial nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.240-249
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• 2011

In this paper, we consider a cell management and handover method in an IEEES02.16e based femto-cell systems. In a femto-cell system, Mobile Stations (MS) and Base Stations (BS) are temporarily overloaded during the process of MOB_NBR-ADV message because it includes huge information of macro-cell and a large number of femto-cells. Also, MS can be handover into another cell frequently, i.e. ping-pong phenomenon, if it is located in a overlapped cell area. In a femtocell system, so-called ping-pong phenomenon will burden the network opreation. In this paper, we propose construction of MOB_NBR-ADV message and it provides fast scanning and efficent handover by means of preselecting the candidate target femto-cells. Also, an adaptive method of hysteresis margin for handover is proposed. The simulation results show that the proposed schemes improve the MS's handover-related performance in terms of scanning power and scanning time compared with the conventional managements scheme of femto-cell systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.2 no.1
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• pp.20-28
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• 1977

The shipping business which consistutes main stream of foreign trades in the world desires more larger and higher speed ships to convey a large amount of cargo at a time rapidly and safely. They also want to introduce new techniques into transportation system so to meet the rapid growing demand of maritime mobile communications with the improvement of efficiency of radio apparatus and reduction of the hard labors of radio operators mechanization and modernization of radio apparatus is necessary. Now HF band is used mainly for communications between maritime mobile stations and coast stations but the quality of received signal is not so good and the coverage is not sufficient by the condition of propagation of waves. There is also limitation of channel capacity in HF band. So to cope with or improve of these defects and meet the demands of modern maritime communication it is essential to introduce maritime satellite communication system in this field. By using the maritime satellite we can establish high quality communication circuits as maritime Telex, Faximile, high speed data transmission line and can expand coverages. Therefore industrial rationalization of marine transportation is possible with the reduction of painful labors of radio operators by improving safety and promoting of efficiency of movement of ships and freights. Obviously it is prospected that the introduction of maritime satellite communication system will bring a rapid promotion of its usuage in maritime mobile communication field and also anticipated that maritime satellite communication system will be a main current in maritime mobile communication field over the world in the near future with moderated cost of transmission links as in the case of INTELSAT in the past 10 years after its first launching.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.385-398
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• 2002

To accommodate the increasing number of mobile terminals in the limited radio spectrum, wireless systems have been designed as micro/picocellular architectures for a higher capacity. This reduced coverage area of a cell has caused a higher rate of hand-off events, and the hand-off technology for efficient process becomes a necessity to provide a stable service. Population-based Bandwidth Reservation(PBR) Scheme is proposed to provide prioritized handling for hand-off calls by dynamically adjusting the amount of reserved bandwidth of a cell according to the amount of cellular traffic in its neighboring cells. We analyze the performance of the PBR scheme according to the changes of a fractional parameter, f, which is the ratio of request reservation to the total amount of bandwidth units required for hand-off calls that will occur for the next period. The vague of this parameter, f should be determined based on QoS(Quality of Service) requirement. To meet the requirement the value of Parameter(f) must be able to be adjusted dynamically according to the changing traffic conditions. The best value of f can be determined by a function of the average speed of mobile stations, average call duration, cell size, and so on. This paper considers the average call duration and the cell size according to the speed of mobile stations. Although some difference exists as per speed, in the range of 0.4 $\leq$ f $\leq$ 0.6, Blocking Probability, Dropping Probability and Utilization show the best values.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.533-540
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• 2003

According to the development of mobile communications, many people have been offered high qualify of the application services using portable terminals. But those works nay have many vulnerabilities and have the limit of excutaions. Because the application services are provided in mobile network and the performance of portable terminals is lower than that of base stations. To improve these problems, in this paper, we propose one-time proxy signature scheme that can reduce the computational ctsost on a user and prevent a proxy agent's dishonesty. The proposed scheme is based on the KBLK scheme [2] which applied the fail-stop signature scheme [1]. It is constructed that a proxy signer can sign only one message with a proxy key and we add anonimity to it for the user's identity protection in mobile communication like a M-commerce.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.104-112
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• 2002

Dynamic Handoff Control Scheme (DHCS), which is propose d in this paper, suggests the method to request handoff at the optimal time. To accomplish this, DHCS measures the speed of the mobile station and sets the pilot strength for handoff request. When the pilot strength of the current base station is bigg or than the pilot strength for handoff request, which means the pilot strength of the current base station is big enough so the possibility of the call to be disconnected is low, DHCS doesn't request for the handoff even though the pilot strength of the adjacent base station is bigger than the pilot strength of the curent base station. DHCS guarantees the QoS (Quality of Service) by processing the handoff calls prior to new calls at the base station and providing continuous service for the mobile station by setting the priorities for the calls according to the queue waiting time transmitted from the mobile stations.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.48-51
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• 2016

Many studies have been carried out in order to develop a frequency efficient communication system than the current communication system for satisfying the increasing demands of wireless data services in mobile communication systems. Service providers must maintain a lot of base station equipments to meet the increasing demands of wireless data service. Therefore service provider needs a system or method to reduce maintenance costs. The amount of wireless data service are changed according to the time of day, geographical location and so on. Power consumption can be reduced if the supplied power of communication systems is controlled by the amount of wireless data traffics. In this paper, power management system of base station's equipment for mobile communication is designed and implemented. The proposed power management system controls the power supplied to the mobile communication infrastructures depending on the service amount of wireless data. Field test result of the implemented system shows the proposed system saves 26% of the power consumption in the base stations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.167-172
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• 2000

This paper is aimed at developing an location tracking for mobile station employing currently available mobile communication network of cellular phone and PCS(Personal Communication System). When the location tracking of mobile stations is in services, the services such as Emergency-119, crime investigation, effective urban traffic management or the safety protection of Alzheimer's patients, ran be available. This paper is to track the mobile station in communication network in NLOS environment. To achieve reduction of the standard noise, Kalman filter is used. In terms of the distance, positions are located by using TOA and TDOA methods in the environment that removes NLOS bias in the measured data. And then smoothing method is used. to achieve reduction of the position error values

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.9
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• pp.1357-1366
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• 2022

It is important to quickly and accurately build a disaster network or tactical mobile communication network adapting to the field. In configuring the traditional wireless communication systems, the parameters of the base station are set through cell planning. However, for cell planning, information on the environment must be established in advance. If parameters which are not appropriate for the field are used, because they are not reflected in cell planning, additional optimization must be carried out to solve problems and improve performance after network construction. In this paper, we present a rapid mobile communication network construction and optimization method using artificial intelligence and SON technologies in mobile communication base stations. After automatically setting the base station parameters using the CNN model that classifies the terrain with path loss prediction through the DNN model from the location of the base station and the measurement information, the path loss model enables continuous overage/capacity optimization.