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Integrating Portable Internet with cdma2000 Mobile Communication Networks for Seamless Service (연속적인 서비스를 위한 휴대 인터넷과 cdma2000 이동통신망의 연동 방안)

  • Cho Jinsung;Kim Jeong Gem
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.11B
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    • pp.920-929
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    • 2004
  • Nowadays, wireless packet data services are provided over cdma2000 1x/1xEV-DO mobile communication network and Portable Internet are being standardized for users demanding higher data rate services. Portable Internet can provide high data rate services, but its service coverage is relatively small. If Portable Internet may be integrated with cdma2000 mobile networks, users are able to choose the best service according to service areas and get seamless services while they are moving around. At the same time, it is cost-effective for operators to construct and maintain the integrated network. For the purpose of effectively integrating Portable Internet into cdma2000 networks, we propose an integration scheme including network architecture, protocol architecture, functions in network elements, interfaces between them, and call-flow procedures. The integration scheme proposed in this paper adopts a tightly-coupled architecture for unified authentication/accounting and seamless services. In addition, the scheme can be implemented without modifying the existing cdma2000 mobile communication networks. It is also simple to develop the dual-mode mobile station. Through the simulation results based on the performance model for handoffs between cdma2000 and Portable Internet, it has teen validated that the proposed scheme diminishes packet losses compared with the loosely-coupled architecture.

Two-step Scheduling With Reduced Feedback Overhead in Multiuser Relay Systems (다중 사용자 릴레이 시스템에서 감소된 피드백 정보를 이용한 두 단계 스케줄링 기법)

  • Jang, Yong-Up;Shin, Won-Yong;Kim, A-Jung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5A
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    • pp.511-520
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    • 2011
  • In this paper, we introduce a multiuser (MU) scheduling method for multiuser amplify-and-forward relay systems, which selects both the transmission mode, i.e., either one- or two-hop transmission, and the desired user via two steps. A closed-form expression for the average achievable rate of the proposed scheduling is derived under two transmission modes with MU scheduling, and its asymptotic solution is also analyzed in the limit of large number of mobile stations. Based on the analysis, we perform our two-step scheduling algorithm: the transmission mode selection followed by the user selection that needs partial feedback for instantaneous signal-to-noise ratios (SNRs) to the base station. We also analyze the average SNR condition such that the MU diversity gain is fully exploited. In addition, it is examined how to further reduce a quantity of feedback under certain conditions. The proposed algorithm shows the comparable achievable rate to that of the optimal one using full feedback information, while its required feedback overhead is reduced below half of the optimal one.

Two Stage Dropping Scheme Considering Latency of rtPS Class in IEEE 802.16/WiBro System (IEEE 802.16/WiBro 시스템에서의 rtPS 클래스의 지연을 고려한 두 단계 드롭 기법)

  • Baek, Joo-Young;Yoon, Jong-Pil;Kim, Sok-Hyong;Suh, Young-Joo
    • Journal of KIISE:Computing Practices and Letters
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    • v.14 no.8
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    • pp.783-787
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    • 2008
  • IEEE 802.16/WiBro, one of the representative Broadband Wireless Access (BWA) systems, defines QoS negotiation between BS and SS and five service classes to guarantee QoS for flows. The five service classes are UGS, ertPS, rtPS, nrtPS, and BE, but the standard does not define how to provide services to flows according to the service classes. Existing research works have been studied about the scheduler architecture to effectively utilize the IEEE 802.16/WiBro systems. These works use the original packet scheduling algorithm for service classes. However, it is necessary to consider bandwidth allocation mechanisms in scheduling algorithms since bandwidth allocation mechanisms are different according to service classes. Especially, bandwidth allocation mechanisms should be considered for the scheduling of rtPS class since rtPS class uses the polling mechanism that takes time to allocate bandwidth and has the minimum latency constraint. Therefore, we propose two stage dropping scheme for rtPS class that is sensitive to latency, and thus it reduces the wasted resources and provides efficient service to rtPS class.

A Study about the Users's Preferred Playing Speeds on Categorized Video Content using WSOLA method (WSOLA를 이용한 동영상 미세배속 재생 서비스에 대한 콘텐츠별 배속 선호도 분석 연구)

  • Kim, I-Gil
    • Journal of Digital Contents Society
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    • v.16 no.2
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    • pp.291-298
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    • 2015
  • In a fast-paced information technology environment, consumption of video content is changing from one-way television viewing to VOD (Video on Demand) playing anywhere, anytime, on any device. This video-watching trend gives additional importance to videos with fine-speed-control, in addition to the strength of the digital video signal. Currently, many video players provide a fine-speed-control function which can speed up the video to skip a boring part, or slow it down to focus on an exciting scene. The audio information is just as important as the visual information for understanding the content of the speed-controlled video. Thus, a number of algorithms for fine-speed-control video-playing technologies have been proposed to solve the pitch distortion in the audio-processing area. In this study, well-known techniques for prosodic modification of speech signals, WSOLA (Waveform-Similarity-Based Overlap-Add), have been applied to analyze users' needs for fine-speed-control video playing. By surveying the users' preferred speeds on categorized video content and analyzing the results, this paper proposes that various fine-speed adjustments are needed to accommodate users' preferred video consumption.

A Location Management Scheme Using Gateway in PCN (PCN에서 VLR 게이트웨이를 이용한 위치관리 기법)

  • 박남식;유영철;남궁한;진성일
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.8B
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    • pp.1444-1455
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    • 1999
  • In the standard location strategy such as IS-41 and GSM, Home Location Register(HLR) and Visitor Location Register(VLR) databases are used to manage the location of mobile terminals. The primary goal that location management schemes investigate is to reduce the cost of database access and the traffic for signaling network. When mobile terminals move frequently, one of problems in the standard location management scheme is that HLR database is highly updated and the traffic in signaling network can be occurred significantly due to high message transfer rate between HRL and VLR. As a solution to these problems, this paper proposes the location management scheme using VLR Gateway(VG) to reduce the both traffics of HLR update and signaling network which are resulted from location registration requirements of mobile terminals whenever they cross their registration area boundary. VG is a kind of database that is placed between HLR and VLR. It integrates one or more registration area defined in a system into one group and plays a role on behalf of HLR in a integrated registration scope so that the call delivery and the movement of mobile terminals are possible without HLR access in the scope. In order to evaluate performance of IS-41 and proposed scheme, we simulate two schemes based on wide range of call to mobility ratio. Its experiment result shows that in the proposed scheme total database cost increased slightly whereas HLR and signaling traffic decreased remarkably.

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GIS and Geographically Weighted Regression in the Survey Research of Small Areas (지역 단위 조사연구와 공간정보의 활용 : 지리정보시스템과 지리적 가중 회귀분석을 중심으로)

  • Jo, Dong-Gi
    • Survey Research
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    • v.10 no.3
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    • pp.1-19
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    • 2009
  • This study investigates the utilities of spatial analysis in the context of survey research using Geographical Information System(GIS) and Geographically Weighted Regression (GWR) which take account of spatial heterogeneity. Many social phenomena involve spatial dimension, and with the development of GIS, GPS receiver, and online location-based services, spatial information can be collected and utilized more easily, and thus application of spatial analysis in the survey research is getting easier. The traditional OLS regression models which assume independence of observations and homoscedasticity of errors cannot handle spatial dependence problem. GWR is a spatial analysis technique which utilizes spatial information as well as attribute information, and estimated using geographically weighted function under the assumption that spatially close cases are more related than distant cases. Residential survey data from a Primary Autonomous District are used to estimate a model of public service satisfaction. The findings show that GWR handles the problem of spatial auto-correlation and increases goodness-of-fit of model. Visualization of spatial variance of effects of the independent variables using GIS allows us to investigate effects and relationships of those variables more closely and extensively. Furthermore, GIS and GWR analyses provide us a more effective way of identifying locations where the effect of variable is exceptionally low or high, and thus finding policy implications for social development.

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A Study on Dynamic Pile-Soil-Structure Interactions (말뚝-지반-구조물의 동섬 상호작용 연구)

  • Lee, In-Mo;Lee, Gwan-Ho;Kim, Yong-Jin
    • Geotechnical Engineering
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    • v.7 no.1
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    • pp.41-52
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    • 1991
  • A study of the effects of dynamic pile-soil-structure interactions on the response of super- structures, supported by group piles, are presented in this paper. The dynamic impedance functions of single pile generated by soil-pile interactions are obtained and compared among others using the methods proposed by Novak, Gazetas, and Kuhlemeyer, and using the equivalent cantilever method. Group pile effects are also considered by the following approaches : neglecting interaction effects : group efficiency ratio concept : static interaction approach . and dynamic interaction approach. The responses of a nuclear containment structure are obtained by using the elastic half-space analysis, based on the impedance functions mentioned above. Main conclusions drawn from this study are as follows : 1. The numerical results of the impedance functions calculated by each method were quite different : the Novak's was the smallest, and the Kuhlemeyer's the highest. Considering group effects, similar values in each approach were obtained for the stiffness : the difference was very big for the damping. 2. The top displacement of the structure was reduced by 20% or more by pile installations. However, the base shear force, the base moment, and the resonance frequency were increased by more than two times due to stiffening effect of the ground by pile installations. 3. Whether frequency dependant impedence functions or frequency independant functions were used, the responses of the structure were not so much affected by the choice of the impedance functions. 4. The reduction effect of the top displacement increased with the increase of the maximum ground acceleration.

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An Early Spectrum Sensing for Efficient Radio Access in Cloud-Conceptual Base Station Systems (클라우드 기지국 시스템에서 효율적 무선 접속을 위한 이른 스펙트럼 감지 기법)

  • Jo, Gahee;Lee, Jae Won;Na, Jee-Hyeon;Cho, Ho-Shin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.1
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    • pp.68-78
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    • 2013
  • In this paper, we propose an early spectrum sensing(ESS) as an advance preparation for radio-access trial, which enables multi-mode terminals to access the most appropriate radio-access system in a cloud-conceptual base station system where multiple radio access technologies(RATs) coexist. Prior to a random access to one of RATs, a multi-mode terminal conducts a spectrum sensing over entire frequency bands of whole RATs, then select the RAT with the lowest sensing power, that is likely to have the most available spectrum. Thus, an access failure caused by that the selected RAT has no available radio spectrum could be avoidable in advance. In computer simulation, we consider as various RATs as possible. First, circuit and packet systems are taken into consideration. In addition, the packet systems are classified according to the feasibility of carrier aggregation(CA). In case of terminal, three modes are considered with circuit-only, packet-only, and multi-mode. Subsequently, packet traffic is classified into real-time and non-real-time traffic with three different tolerable delay levels. The simulation includes a call process starting with a call generation and ending up with a resource allocation reflecting individual user's QoS requirements and evaluates the proposed scheme in terms of the successful access probability, system access time, system balancing factor and packet loss probability.

P2P-based Mobility Management Protocol for Global Seamless Handover in Heterogeneous Wireless Network (이기종망에서 글로벌 끊김 없는 핸드오버를 위한 P2P 기반 이동성 관리 프로토콜)

  • Chun, Seung-Man;Lee, Seung-Mu;Park, Jong-Tae
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.12
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    • pp.73-80
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    • 2012
  • In this article, we propose a P2P-based mobility management protocol for global seamless handover in heterogeneous wireless networks. Unlike previous mobility management protocols such as IETF MIPv4/6 and its variants, the proposed protocol can support global seamless handover without changing the existing network infrastructure. The idea of the proposed protocol is that the location management function for mobility management is separately supported from packet forwarding function, and bidirectional IP tunnels for packet transmission are dynamically constructed between two end-to-end mobile hosts. In addition, early handover techniques have been developed to avoid large handover delays and packet losses using the IEEE 802.21 Media Independent Handover functions. The architecture and signaling procedure of the proposed protocol have been designed in detail, and the mathematical analysis and simulation have been done for performance evaluation. The performance results show that the proposed protocol outperforms the existing MIPv6 and HMIPv6 in terms of handover latency and packet loss.

Design of a Multi-band Internal Antenna Using Half Wavelength Loaded Line Structure for Mobile Handset Applications (반파장 로디드 라인 구조를 이용한 이동 통신 단말기용 다중 대역 내장형 안테나 설계)

  • Shin Hoo;Jung Woo-Jae;Jung Byungwoon;Park Myun-Joo;Lee Byungje
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.12 s.103
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    • pp.1179-1185
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    • 2005
  • In this paper, novel internal antenna with its controllable resonant frequency is presented for triple-band or over mobile handsets. The operating range can include GSM(880${\~}$960 MHz), GPS(1,575$\pm$10 MHz), DCS(1,710${\~}$1,880 MHz), US-PCS(1,850${\~}$l,990 MHz), and W-CDMA(1,920${\~}$2,170 MHz). The proposed antenna is realized by combination of a half wavelength loaded line and a shorted monopole. A single shorting and feeding points are used and they are common to both antenna structures. By controlling a value of lumped inductance element between shorting point and ground plane, the antenna provides enough bandwidth to cover DCS, US-PCS, and W-CDMA respectively. When these higher bands are controlled by the values of inductance, resonant characteristics in GSM and GPS bands are maintained. In this work, maximum value of the inductor is limited within 3.3 nH to mitigate gain degradation from frequency tuning. As a result, measured maximum gain of antenna is -0.58${\~}$-0.30 dBi in the GSM band, -0.57${\~}$0.43 dBi in the GPS band and 0.38${\~}$1.15 dBi in the DCS/US-PCS/W-CDMA band. In higher band, the proposed antenna is certified that resonant frequency of about 240 MHz can be effectively controlled within gain variation of about 0.77 dB by simulation and measurement.