• Title, Summary, Keyword: existence and uniqueness

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A Utility-Based and QoS-Aware Power Control Scheme for Wireless Body Area Networks

  • Li, Yanjun;Pan, Jian;Tian, Xianzhong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.9
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    • pp.4188-4206
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    • 2016
  • Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

Energy-Efficient Power Control for Underlaying D2D Communication with Channel Uncertainty: User-Centric Versus Network-Centric

  • Ding, Jianfeng;Jiang, Lingge;He, Chen
    • Journal of Communications and Networks
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    • v.18 no.4
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    • pp.589-599
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    • 2016
  • Most existing resource management problem models arise from the original desire of allocating resources in either a user-centric or network-centric manner. The difference between their objectives is obvious: user-centric methods attempt to optimize the utility of individual users, whereas network-centric models intend to optimize the collective utilities of the entire network. In this paper, from the above two aspects, we analyze the robust power control problem in device-to-device (D2D) communication underlaying cellular networks, where two types of channel uncertainty set (e.g., ellipsoidal and column-wise) are considered. In the user-centric method, we formulate the problem into the form of a Stackelberg game, where the energy efficiency (EE) of each user is the ingredient of utility function. In order to protect the cellular user equipment's (CUE) uplink transmission, we introduce a price based cost function into the objectives of D2D user equipment (DUE). The existence and uniqueness of the game with the influence of channel uncertainty and price are discussed. In the network-centric method, we aim to maximize the collective EE of CUEs and DUEs. We show that by the appropriate mathematical transformation, the network-centric D2D power control problem has the identical local solution to that of a special case of the user-centric problem, where price plays a key role. Numerical results show the performance of the robust power control algorithms in the user-centric and network-centric models.

Optimized Medium Access Probability for Networked Control Systems (네트워크 제어 시스템을 위한 최적화된 매체 접근 확률)

  • Park, Pangun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.10
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    • pp.2457-2464
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    • 2015
  • Distributed Networked Control Systems (NCSs) through wireless networks have a tremendous potential to improve the efficiency of various control systems. In this paper, we define the State Update Interval (SUI) as the elapsed time between successful state vector reports derived from the NCSs. A simple expression of the SUI is derived to characterize the key interactions between the control and communication layers. This performance measure is used to formulate a novel optimization problem where the objective function is the probability to meet the SUI constraint and the decision parameter is the channel access probability. We prove the existence and uniqueness of the optimal channel access probability of the optimization problem. Furthermore, the optimal channel access probability for NCSs is lower than the channel access probability to maximize the throughput. Numerical results indicate that the improvement of the success probability to meet the SUI constraint using the optimal channel access probability increases as the number of nodes increases with respect to that using the channel access probability to maximize the throughput.

Feature of Intertextuality Environmental Arts -Focusing on Feature of fantasy post-place, speciality of place as well as temporal-spatial expression method- (상호텍스트적인 환경예술의 특성 -환상성.탈 장소성, 장소의 특수성과 시공간 표현방법에 대한 특성을 중심으로-)

  • Jang, Il-Young;Kim, Jin-Seon
    • Archives of design research
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    • v.18 no.3
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    • pp.63-74
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    • 2005
  • Modern society is diversified society and is under complicated situation as the boundary of each area has been disappeared. To understand and accept such complicated situation as widely as possible, it is required to understand interaction. of receiver with intertextual environmental arts as the structure of open text. This study examined interaction of environmental arts in terms of intertextual feature based on experience of receiver on combined element of different space and time, combination of genres. This is the concept of meaning personal experience or situation as receiver participates the process of completing art works, and set the fantasy, post-place and speciality of location and temporal-spatial expression method, as characteristics of intertextuality. Features of such experience elements are used as methodology of analyzing characteristics of each work. Feature of fantasy uses strategy of inducing spatial experience of receiver with dematerialization for post-place and expands the place where events occur with intervention of contingency and event situation. It suggests the spatial-temporal expression method as the features focusing on process and reflecting changes in spatial-temporal continuum and speciality of place emphasizing context of place. In conclusion, environmental arts needs to be deep rooted on complicated existence aspect of receiver beyond metaphysical dimension depending on presence and to accomplish conversion of awareness of supplying bisection of life from that place. By doing so, environmental arts can live textual life as it gets together with all other texts in terms of text dimension and creativity can be reborn as practical creativity in intertextuality rather than uniqueness. Such combination with other areas and acceptance of various aspects of receivers who see and experience this will result to creation of open works which can be create newly over and over again in multi-dimensional aspects.

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A Study on the Spatiotemporal Interpretation of Derek Jarman's Garden (데릭 저먼의 정원에 대한 시공간적(時空間的) 해석)

  • Yun, Jiayan;Zoh, Kyungjin
    • Journal of the Korean Institute of Landscape Architecture
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    • v.44 no.1
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    • pp.66-79
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    • 2016
  • This study looks at spatiotemporal theories regarding the pluralism of time inherent in garden space, and attempts to establish spatiotemporal theories suitable for garden spaces. Based on the established theories, this study analyzes the intimacy of garden spaces by focusing on the objective and subjective time of garden spaces in Derek Jarman's garden through a literature review. The sense of time inherent to a garden space was divided into objective and subjective time. The former refers to ecological time that is quantified and has durability, while the latter indicates time that changes according to the consciousness of the human subject. It also includes time that is emotionalized by the sense of the human subject. This study first interpreted Jarman's garden space from the perspective of objective time. The garden transforms itself into a sensitive space according to Jarman's personal emotions in the current space within objective time, showing the multilayered attributes of space. Therefore, a garden space that exists in objective time is ultimately not objective, and is transformed according to the active reception of the human subject. Next, this study examined Jarman's garden space from the perspective of subjective time. The garden space lost in Jarman's memories and the one in his future illusion turn into a space that connotes abundant meaning according to Jarman's imagination or perception. Therefore, in subjective time, garden space is transformed according to Jarman's consciousness. This study verified that garden space, regardless of whether time is objective or subjective, can create infinite space according to the consciousness or emotions of the human subject beyond the existence of physical space. Since garden space has a unique intimacy unlike urban space, this study presented the uniqueness of garden space with an approach that differs from previous studies on gardens.

Aesthetic Landscape Assessment Based on Landscape Units in the Han River Riparian Area (경관단위 기반 수변환경의 심미적 평가 - 한강 수변을 대상으로 -)

  • Bae, Min-Ki;Park, Chang-Sug;Oh, Chung-Hyun
    • Journal of the Korean Institute of Landscape Architecture
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    • v.40 no.1
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    • pp.43-56
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    • 2012
  • The purpose of this study was to propose management strategies through aesthetic landscape assessments for landscape units in the Han River riparian(HRR) area. First, this research reclassified the HRR into "natural," "artificial," "agricultural," and mixed landscape types and selected 37 representative case areas(about $1km{\times}1km$). This study found 71 landscape units in consideration of topography and land surface classification. Landscape assessment consisted of landscape quality and landscape integration assessment. The criteria for assessing landscape quality were "naturalness," "interest," "uniqueness," and "landscape function." "Landscape quality" was ranked into five grades using a matrix. The landscape integration assessment consisted of an inner integration assessment in each landscape unit and outer integration assessment among landscape units. As a result of the field study, case sites were found to have 4,288 landscape units and an area of $42.8km^2$. The forest area was found to have the most space with $11,580,905m^2$(27.1%), while the wet lands had just $52,348m^2$(0.1%). In the landscape quality assessment, about 30.5% of the total area consisted of landscape units that scored highest in "naturalness". In the landscape integration assessment, about 39.3% of the total area consisted of landscape units which scored highest in "integration", denoting visual interrelation and harmony. The existence of disparities in landscape quality in accordance with the form of the landscaping was determined using a Oneway ANOVA, with "naturalistic" landscaping scoring the highest and "artificial" landscaping scoring lowest. This study may contribute to making the HRR area a more ecologically sound and visually attractive landscape space. It is recommended that the aesthetical and ecological value of the landscape unit should be assessed simultaneously in the future.

Evolution of the National Pension Scheme in Korea: Uniqueness and Sustainability of the Korean Model (국민연금제도 전개의 한국적 특징과 지속가능성)

  • Kim, Yong-Hha;Seok, Jae-Eun
    • Korean Journal of Social Welfare
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    • v.37
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    • pp.89-118
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    • 1999
  • The goal of this paper is to define the distinguishing characteristics of Korea's National Pension Scheme compared to the National Pension types of other countries and sees if those characteristics are significant enough in order to warrant calling these the "Korean Model". Also, another point to consider is, if this "Korean Model" does indeed exist, whether it is a 'sustainable' model or not. The National Pension Scheme, which was implemented in 1988, is similar to the public pension system formerly used in Japan. The National Pension Scheme broke away from this 'Japanese Model' in 1995 with implementation of the Farmers and Fishermen Pension, and the unique "Korean Model National Pension" was completed in 1998 with revision of the National Pension Law. The characteristics of the Korean National Pension can be defined as being balanced equally on ability and equality, possessing strong intergenerational income redistribution, having a nationally integrated structure, an incomplete funded method financial neutralism of the government and also as being a Monroe-oriented pension system. There are several limits to the sustainable development of this Korean Model National Pension, though. Even though the precondition of "the income determination problem of self-employed persons", which has strong intra-generational income redistribution. in actuality there are still many policy issues to be confronted such as the structure which 'transfers the burden to the future generation', the 'inter-generational inequity' of the incomplete funded system, persons excluded from coverage under the national integrated structure, 'compulsory loaning of the public sector by the National Pension Fund' under the government's principle of finance neutralism, the separate existence of the 'Monroe-oriented National Pension' from other pensions, etc.,. Therefore, it need to reform of NPS once again to sustainable development of KMNP.

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