• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2507-2517
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• 2015

In this research, we aim to analyze the trend of Huawei's PCT patent applications. As a result of analyzing Huawei's PCT patents by dividing temporal spans into three periods - the early 2000s, the late 2000s, and the early 2010s -, the following characteristics have been observed. First, the number of PCT patent applications has conspicuously increased from the early 2000s to the late 2000s and this trend has continued during the early 2010s. Second, in terms of a core technological field, whereas Huawei focused on the development of technologies in the 'H04L: transmission of digital information' sector during the early/late 2000s, it changed this field to the 'H04W: wireless communication networks' sector during the early 2010s. Lastly, in the case of the patent maps, it was found that while general communications technologies, as expressed with such keywords as 'user' and 'network,' were actively developed during the early/late 2000s, mobile phone-related technologies grasped this leading position, as shown with the keywords including 'user equipment,' 'base station,' and 'MME,' during the early 2010s. It was also noticeable that Huawei filed LTE-related patent applications more actively than Apple and Samsung Electronics, which implies that it will presumably pioneer the global market more aggressively than its competitors in the future.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.86-95
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• 2011

Sensor nodes in wireless sensor networks are vulnerable to security than wired network due to using limited hardware performance and wireless communications that network topology changes frequently. Among techniques to enhance the security, the node authentication mechanism is used to defend against data forgery attacks using the ID of the node or to interfere with the routing of the network routing. In this paper, we proposed the AM-E mechanism that makes authentication key by using the energy value of node requesting authentication and performs the communication procedures for data transfer between different nodes. Because the energy value of node is changed depending on time, every time the authentication request is, an authentication key is changed. These features enhance the security of sensor networks and will help to configure the more secure WSN.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.76-83
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• 2011

The IEEE WAVE-based communication systems do not provide handover services since most of the application layer messages of a small amount containing text data that are related to safe driving. Multimedia data service such as web pages and CCTV video clips, however, require a seamless handover for continuation of a session via multiple RSUs. In this paper, we propose a new proactive handover protocol based on IEEE WAVE. According to the proposed handover protocol, the OBU notifies the old RSU of its departure from the coverage such that the old RSU forwards to the new RSU the data heading towards the OBU to be cached for the further delivery upon its entry into the new RSU's coverage. The simulation results are presented which shows the performance of the proposed protocol in terms of throughput, delivery ratio and handover delay.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.4
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• pp.195-204
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• 2010

Due to improved wireless communication technologies, it is possible to provide multimedia streaming service for mobile device clients like PDAs and cellphones. Wireless networks are serviced on low bandwidth channels and mobile devices work on limited hardware specifications. In these conditions, transcoding technologies are needed to adapt the media for streaming services to given mobile environments. To transcode from the source media to the target media for corresponding grades, transcoding servers perform transcoding jobs as exhausting their resources. Since various transcoding loads occur according to the target transconding grades, an effective transcoding load balancing policy is required among transcoding servers. In addition to transcoding process, servers should maintain QoS streams for mobile clients for total serviced times. It requires real-time requirements to support QoS for various mobile clients. In this paper, a new transcoding load distribution method is proposed. The proposed method can be driven for fair load balance between distributed transcoding servers. Based on estimated transcoding time, movie information and target transcoding bit-rate, it provides fair transcoding load distribution and also performs admission control to support QoS streams for mobile clients.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.9_10
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• pp.466-475
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• 2008

Owing to the improved wireless communication technologies, it is possible to provide streaming service of multimedia with PDAs and mobile phones in addition to desktop PCs. Since mobile client devices have low computing power and low network bandwidth due to wireless network, the transcoding technology to adapt media for mobile client devices considering their characteristics is necessary. Transcoding servers transcode the source media to the target media within corresponding grades and provide QoS in real-time. In particular, an effective load balancing policy for transcoding servers is inevitable to support QoS for large scale mobile users. In this paper, the transcoding load estimation algorithm is proposed for load balance on the distributed transcoding environments. The proposed algorithm estimates transcoding time from transcoding server information, movie information and target transcoding bit-rate. The estimated transcoding time is proved based on experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.587-595
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• 2015

A by-pass path in wireless sensor networks is the alternative path which be able to forward data when a routing path is being broken. One reason of depleting energy is occurred by the path. The method for solving prior to addressed the problem is proposed. However, this method may deplete radio resource. The best path has advantage that network lifetime of sensor nodes is prolonged; on the contrary, in order to maintain the best path it have to share their information between the entire nodes. In this paper, we propose the best path searching algorithm in the distributed three dimensional sensor networks. Through the neighboring informations sharing in the proposed method, the proposed algorithm can decide the best k-path as well as the extension of network lifetime.

• The KIPS Transactions:PartD
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• v.11D no.7 s.96
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• pp.1507-1516
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• 2004

Recently, the most remarkable word is 'ubiuuitous' in field of information and communication. Ubiquitous has a meaning 'exist everywhere' that means our daily life is connect as network. It means we can get the information which in need whenever and wherever with safety. We predict this word will be symbolical keyword which lead an information-oriented society including the internet a quite long it. It's already per-meate to us the Ubiquitous. It's taken by CCTV when we visit bank. It's made to us can know the fastest way the GPS system to be connected by an artificial satcllite on mobile, and many people use mobile and PDA for investment in stocks. Among them, it has begun to spread many mobile services to us. In this paper, it's the aim a creation of value added through an efficient mobile services to use wireless internet different with previous way, cutting down on expenses and business modeling.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.1
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• pp.7-14
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• 2014

The rapid increase of mobile devices such as smart phone and smart pad have raised the needs for seamless multimedia services during moving at anytime and anywhere. Current 4G mobile devices are equipped with both 4G (LTE) and WLAN (WiFi) interfaces, and mobile services operators provide wireless Internet services using 4G network with a wider coverage and WiFi zone. Generally users prefer to use the Internet services through WLAN rather than LTE in the coverage of WLAN. However, since WLAN has a long L2 handover latency, it is difficult to support seamless services during a handover. In this paper, we proposed an efficient handover scheme based on flow mobility for WLANs to support a seamless service during handovers by using the overlaid 4G network with a wider coverage. Also, we showed the outperformance of the proposed scheme on a testbed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.77-88
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• 2010

Wireless Mesh Networks are consist of mobility mesh clients and mesh routers. WMNs can communicate with heterogeneous networks such as IEEE 802.11, IEEE 802.15, IEEE 802.16 and sensor networks. WMNs which is based on ad hoc network are on research and developing to enhance WLANs, WPANs, or WMANs. WMNs can offer environment to serve human, service to person area, campus, and metro. But WMNs has many problems to solve about enhancing performance and generalization. Among them, Existing protocol layers has many problems enhancing to optimize WMNs. This document issues problems about WMNs in protocol layer and suggest the solutions. Also, suggests the requirements and the methods of QoS supporting issue.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.325-336
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• 2005

Mobile ad hoc networks (MANET) are composed of moving wireless hosts which, within range of each other, form wireless networks. For communication to occur between hosts that are not within each other's range, routes involving intermediate nodes must be established; however, since the hosts may be in motion, a host that was part of a route may move away from its upstream and downstream partners, thus breaking the route. In this paper, we propose anticipated route maintenance (ARM) protocol with two extensions to route discovery based routing scheme: Extend the route when nodes on a link move apart from each other and they have common neighbor that can be 'inserted' in the path, and shrink route when a node discovers that one of its neighbor which is not the next hop is also on the same route several hops later on. By utilizing only local geographic information (now a part of some route finding algorithms), a host can anticipate its neighbor's departure and, if other hosts are available, choose a host to bridge the gap, keeping the path connected. We present a distributed algorithm that anticipates route failure and performs preventative route maintenance using location information to increase a route lifespan. The benefits are that this reduces the need to find new routes (which is very expensive) and prevents interruptions in service. As the density of nodes increases, the chance to successfully utilize our route maintenance approach increases, and so does the savings. We have compared the performance of two protocols, pure dynamic source routing (DSR) protocol and DSR with ARM. The simulation results show how ARM improves the functionality of DSR by preventing the links in the route from breaking. Packets delivery ratio could be increased using ARM and achieved approximately $\100%$ improvement. The simulations clarify also how ARM shows a noticeable improvement in dropped packets and links stability over DSR, even though there is more traffic and channel overhead in ARM.