• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2033-2042
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• 1996

In this papre, we describe a recently implemented echo canceller for digital cellular communication of Code Division Multiple Access(CDMA) that features time sharing of digital signal processor(DSP) over four channels in one DSP to reduce per channel costs. In the Public Land Mobile Network(PLMN), it is important to cancel the echo reflected from the Public Switched Telephone Network(PSTN) side. In case of digital mobile system, the round-trip delay of the echo is in excess of about 180 milliseconds due to frame-by-frame voice coding. It is necessary to cancel the echo in PLMN. We have developed a multi-channel echo canceller tht operates with Time Switch Module in a Mobile Switching Center(MSC). The general echo canceller needs PCM trunk interface circuits and the tone detection and disabling circuits, but the multi-channel echo canceller linked with Time Switch Module does not need them. Therefore we could develop the effective and economical echo canceller.

• Journal of Information Display
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• v.9 no.1
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• pp.6-13
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• 2008

Mobile phones use the embedded memory in LDI (LCD Driver IC). In memory accessing mode, data overlapping phenomenon can occur. These days, various contents such as DMB, Camera, Game are merged to phone. Accordingly, with more data transmission, there would be more data overlapping phenomenon in memory accessing mode. Human eyes perceive this data overlapping phenomenon as simply horizontal line noise. The cause of the data overlapping phenomenon was analysed in this paper. The data overlapping phenomenon can be changed by the speed of data transmission between the host and LDI. The optimum memory accessing position can be defined. This paper proposes a new algorithm for avoiding data overlapping.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2107-2112
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• 2006

As growing up of elderly population, the interesting on healthcare system in normal life using W is increasing. An integrated u-healthcare service architecture with IEEE 802.11 and IEEE 802.15.4 based sensor network and code divisi(m multiple access(CDMA) public mobile telecommunication networks was designed and developed. Sensor nodes with electrocardiogram(ECG), body core temperature sensors are attached on the patients' body. The healthcare parameters are transferred to web server via CDMA mobile network or through existed LAN network. The existed LAN network is suggested to be used for continuous monitoring of patient's health status in hospital while mobile networks can be used for general purpose at home or outdoor where infra networks unavailable. This system enable healthcare personal to be able to continuously access, review, monitor and transmit the patients information whereever they are, whenever they want. And immediately check their status by using cellular phone and obtain detail information by communication with medical information server through CDMA. By using this developed integrated u-healthcare service architecture, we can monitor patients' health status for 24 hours.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.211-215
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• 2015

It comes into the spotlight as the new Blue Ocean in which the connected car industry in which the car and mobile communication technology is convergence. All sorts of infortainments services connecting with the portable electronic device(Smart phone, tablet PC, and MP3 player) and car are rapidly grown. The Connected car emphasizes the vehicle connectivity with the concept that the car has communication with the around on a real time basis and it provides the safety and expedience to the operator and using the thing of Internet (IoT) in the car and supports the application, presently, the entertainment service including the real-time Navigation, parking assistant function, not only the remote vehicle control and management service but also Email, multimedia streaming service, SNS and with the platform. Intelligent vehicle network is studied as the kind according to MANET(Mobile Ad Hoc Network) for the safety operation of the cars of the road and improving the efficiency of the driving. The intelligent vehicle network is comprised for the driving information offering changing rapidly of the communication(V2V: Vehicle to Vehicle) between the car and the car, communication(V2I : Vehicle to Infrastructure) between the infrastructure and the car, and V2X (Vehicle to Nomadic).

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.175-181
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• 2009

All of the military aircrafts in Korea Air Force are administered and operated together in the same system regardless of whether they are equipped with the data communication capability or not. The absence of the data communication capability in some of the aircrafts might increase whole kill chain hour at the point of the Network Centric Warfare achievement. Network synergy effects cannot also be desired if the section which is not connected to the network influences to the whole tactical network. Equipping aircrafts with the data communication capability could be done by upgrading the aircrafts, but resulting in high costs and long updating time. This paper is a research about the design and implementation of the UMPC based Data Link System to aircrafts that do not have the data communication capability. The proposed system grafts the UHF-based wireless modem technology and the aircraft flight mission support software onto the off-the-shelf UMPC and GPS system. The employed UHF radio equipment allows communicating tactic data with another aircrafts on the air, the ground control point, and even the Tactical Air Control Party(TACP) control vehicle that achieve missions with aircrafts. It thereby increases such capabilities as navigation aid, situation awareness, quick target identification and attack. We also applied Closed Air Support(CAS) scenarios, which is very close to the real environment, to the experiments of the proposed system. The experimental results show that the proposed system could support the data communication capability effectively and the flight mission at low costs of money and time.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.1-8
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• 2021

In Mobile Ad-Hoc Network (MANET) Application, routing protocol is essential to ensure successful data transmission to all nodes. Ad-hoc On-demand Distance Vector (AODV) Protocol is a reactive routing protocol that is mostly used in MANET applications. However, the protocol causes Route Request (RREQ) message flooding issue due to the broadcasting method at the route request stage to find a path to a particular destination, where the RREQ will be rebroadcast if no Request Response (RREP) message is received. A scalable neighbor-based routing (SNBR) protocol was then proposed to overcome the issue. In the SNBR protocol, the RREQ message is only rebroadcast if the number of neighbor nodes less than a certain fix number, known as drop factor. However, since a network always have a dynamic characteristic with a dynamic number of neighbor nodes, the fix drop factor in SNBR protocol could not provide an optimal flooding problem solution in a low dense network environment, where the RREQ message is continuously rebroadcast RREQ message until reach the fix drop factor. To overcome this problem, a new broadcasting method as Dynamic SNBR (DSNBR) is proposed, where the drop factor is determined based on current number of neighbor nodes. This method rebroadcast the extra RREQ messages based on the determined dynamic drop factor. The performance of the proposed DSNBR is evaluated using NS2 and compared with the performance of the existing protocol; AODV and SNBR. Simulation results show that the new routing protocol reduces the routing request overhead, energy consumption, MAC Collision and enhances end-to-end delay, network coverage ratio as a result of reducing the extra route request messages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1261-1266
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• 2014

Smart shipyard, all of the business of shipyard by using a mobile application, and the rapid spread of smart equipment, the overload of infrastructure due to a variety of mobile services is expected. Because macrocell and femtecell to reduce the overloading of existing infrastructure, additional core network devices have a problem, in this paper, the efficiency of resources than the communication over the existing infrastructure smart shipyard network to improve, to apply the D2D communication technology that can reduce the load on the infrastructure. The proposed routing path plan in accordance with the transfer method and the traffic type of network configuration and D2D equipment navigation and data for applying a smart shipyard. Whether to execute the function to overload traffic in the core network can send to the optimized path was confirmed by using the state transition diagram. Smart shipyard, by applying D2D communication allow efficient traffic handling than conventional communication method.

• ETRI Journal
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• v.42 no.5
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• pp.721-733
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• 2020

Recently, there is an increasing demand for ultra-low-latency (ULL) services such as factory automation, autonomous driving, and telesurgery that must meet an end-to-end latency of less than 10 ms. Fifth-generation (5G) New Radio guarantees 0.5 ms one-way latency, so the feasibility of ULL services is higher than in previous mobile communications. However, this feasibility ensures performance at the radio access network level and requires an innovative 5G network architecture for end-to-end ULL across the entire 5G system. Hence, we survey in detailed two the 3rd Generation Partnership Party (3GPP) standardization activities to ensure low latency at network level. 3GPP standardizes mobile edge computing (MEC), a low-latency solution at the edge network, in Release 15/16 and is standardizing time-sensitive communication in Release 16/17 for interworking 5G systems and IEEE 802.1 time-sensitive networking (TSN), a next-generation industry technology for ensuring low/deterministic latency. We developed a 5G system based on 3GPP Release 15 to support MEC with a potential sub-10 ms end-to-end latency in the edge network. In the near future, to provide ULL services in the external network of a 5G system, we suggest a 5G-IEEE TSN interworking system based on 3GPP Release 16/17 that meets an end-to-end latency of 2 ms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.557-566
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• 2008

Some types of network nodes such as mobile network node, mobile access point, and ad-hoc network node can be relocated frequently and, by the nature of its usage, are deployed over broad area. In this environment, the network topology is changed constantly since even the manager node as well as the managed nodes can leave or join the management network frequently. The many of existing network management technologies are mostly for small sized and homogeneous networks with static topologies and not proper for the mobile network devices. In this paper, employing peer-to-peer (P2P), the secure group communication techniques, and simple network management protocol (SNMP), we propose a highly secure and available management technique that can be used to manage the mobile network nodes through insecure management network such as the Internet. The proposed technique is implemented to show that it is practically usable.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.747-754
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• 1999

Mobile Agent is a movable software program that autonomously runs on behalf of its operator in a network environment. It has been widely applied to various kinds of computer engineering. In this paper, a network management architecture using the mobile agent technology in the distributed network environment is proposed. After manager system creates the mobile agent, it searches a proxy, a distributed object that acts as the substitute for a SNMP agent. In order to get the management information that manager requires, the mobile agent goes to the proxy and does operations on it. So, only the concise results from the operation are sent to the managing system. The proposed architecture is based on CORBA that provides several transparent characteristics in the distributed environment. In additional, the proxy object that represents the SNMP agent enables the mobile agent and the SNMP agent to converse with themselves. In this architecture, the mobile agent can carry out an automated management function, easily change and modify management functions. Therefore, it can provide an efficient management way.