• Title/Summary/Keyword: Adaptive resource allocation

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An Efficient AMC Schemes for Mobile Satellite Communication Systems based on LTE (LTE 기반 이동 위성통신 시스템에서의 효율적인 AMC 방식)

  • Yeo, Sung-Moon;Hong, Tae-Chul;Kim, Soo-Young;Ku, Bon-Jun
    • Journal of Satellite, Information and Communications
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    • v.5 no.1
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    • pp.43-47
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    • 2010
  • In future mobile networks, hybrid/integrated satellite and terrestrial systems will play an important role. Most of the mobile communication systems are focused on the terrestrial systems, in this case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. Terrestrial systems of all the 4G mobile communication adopted the adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation in an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. In the paper, we propose the method to apply AMC to mobile satellite systems. In addition, in order to effectively counteract to short term fadings, we present the simulation results of the AMC combined with an interleaver.

Knowledge-driven Dynamic Capability and Organizational Alignment: A Revelatory Historical Case

  • Kim, Gyeung-Min
    • Asia pacific journal of information systems
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    • v.20 no.1
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    • pp.33-56
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    • 2010
  • The current business environment has been characterized as less munificent, highly uncertain and constantly evolving. In this environment, the company with dynamic capability is reported to be more successful than others in building competitive advantage. Dynamic capability focuses on the link between a dynamically changing environment, strategic agility, architectural reconfiguration, and value creation. Being characterized to be flexible and adaptive to market circumstance changes, an organization with dynamic capability is described to have high resource fluidity, which represents business process, resource allocation, human resource management and incentives that make business transformation faster and easier. Successful redeployment of the resources for dynamic adaptation requires organizational forms and reward systems to be well aligned with firm's technological infrastructures and business process. The alignment is considered to be an executive level commitment. Building dynamic capability is knowledge driven; relying on new knowledge to reconfigure firm's resources. Past studies established the link between the effective execution of a knowledge-focused strategy and relevant setting of architectural elements such as human resources, structure, process and information systems. They do not, however, describe in detail the underlying processes by which architectural elements are adjusted in coordinated manners to build knowledge-driven dynamic capability. In fact, understandings of these processes are one of the top issues in IT management. This study analyzed how a Korean corporation with a knowledge-focused strategy aligned its architectural elements to develop the dynamic capability and thus create value in the dynamically changing markets. When the Korean economy was in crisis, the company implemented a knowledge-focused strategy, restructured the organization's architecture by which human and knowledge resources are identified, structured, integrated and coordinated to identify and seize market opportunity. Specifically, the following architectural elements were reconfigured: human resource, decision rights, reward and evaluation systems, process, and IT infrastructure. As indicated by sales growth, the reconfiguration helped the company create value under an extremely turbulent environment. According to Ancona et al. (2001), depending on the types of lenses the organization uses, different types of architecture will emerge. For example, if an organization uses political lenses focusing on power, influence, and conflict. the architecture that leverage power and negotiate across multiple interest groups would emerge. Similarly, if an organization uses economic lenses focusing on the rational behavior of organizational actors making choices based on the costs and benefits of action, organizational architecture should be designed to motivate and provide incentives for the actors (Smith, 2001). Compared to this view, information processing perspectives consider architecture to be designed to maximize the capacity of information processing by the actors. Using knowledge lenses, the company studied in this research established architectural elements in a manner that allows the firm to effectively structure knowledge resources to form dynamic capability. This study is revelatory single case with a historic perspective. As a result of this study, a set of propositions and a framework are derived, which can be used for architectural alignment.

Adaptive Call Admission and Bandwidth Control in DVB-RCS Systems

  • Marchese, Mario;Mongelli, Maurizio
    • Journal of Communications and Networks
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    • v.12 no.6
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    • pp.568-576
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    • 2010
  • The paper presents a control architecture aimed at implementing bandwidth optimization combined with call admission control (CAC) over a digital video broadcasting (DVB) return channel satellite terminal (RCST) under quality of service (QoS) constraints. The approach can be applied in all cases where traffic flows, coming from a terrestrial portion of the network, are merged together within a single DVB flow, which is then forwarded over the satellite channel. The paper introduces the architecture of data and control plane of the RCST at layer 2. The data plane is composed of a set of traffic buffers served with a given bandwidth. The control plane proposed in this paper includes a layer 2 resource manager (L2RM), which is structured into decision makers (DM), one for each traffic buffer of the data plane. Each DM contains a virtual queue, which exactly duplicates the corresponding traffic buffer and performs the actions to compute the minimum bandwidth need to assure the QoS constraints. After computing the minimum bandwidth through a given algorithm (in this view the paper reports some schemes taken in the literature which may be applied), each DM communicates this bandwidth value to the L2RM, which allocates bandwidth to traffic buffers at the data plane. Real bandwidth allocations are driven by the information provided by the DMs. Bandwidth control is linked to a CAC scheme, which uses current bandwidth allocations and peak bandwidth of the call entering the network to decide admission. The performance evaluation is dedicated to show the efficiency of the proposed combined bandwidth allocation and CAC.

An Adaptive Storage System for Enhancing Data Reliability in Solar-powered Sensor Networks (태양 에너지 기반 센서 네트워크에서 데이터의 안정성을 향상시키기 위한 적응형 저장 시스템)

  • Noh, Dong-Kun
    • Journal of KIISE:Computer Systems and Theory
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    • v.36 no.5
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    • pp.360-370
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    • 2009
  • Using solar power in wireless sensor networks requires a different approach to energy optimization from networks with battery-based nodes. Solar energy is an inexhaustible supply which can potentially allow a system to run forever, but there are several issues to be considered such as the uncertainty of energy supply and the constraint of rechargeable battery capacity. In this paper, we present SolarSS: a reliable storage system for solar-powered sensor networks, which provides a set of functions, in separate layers, such as sensory data collection, replication to prevent failure-induced data loss, and storage balancing to prevent depletion-induced data loss. SolarSS adapts the level of layers activated dynamically depending on solar energy availability, and provides an efficient resource allocation and data distribution scheme to minimize data loss.

A Study of Mobile Ad-hoc Network Protocols for Ultra Narrowband Video Streaming over Tactical Combat Radio Networks (초협대역 영상전송 전투무선망을 위한 Mobile Ad-hoc Network 프로토콜 연구)

  • Seo, Myunghwan;Kim, Kihun;Ko, Yun-Soo;Kim, Kyungwoo;Kim, Donghyun;Choi, Jeung Won
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.4
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    • pp.371-380
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    • 2020
  • Video is principal information that facilitates commander's immediate command decision. Due to fading characteristics of radio link, however, it is difficult to stably transmit video in a multi-hop wireless environment. In this paper, we propose a MANET structure composed of a link adaptive routing protocol and a TDMA MAC protocol to stably transmit video traffic in a ultra-narrowband video streaming network. The routing protocol can adapt to link state change and select a stable route. The TDMA protocol enables collision-free video transmission to a destination using multi-hop dynamic resource allocation. As a result of simulation, the proposed MANET structure shows better video transmission performance than proposed MANET structure without link quality adaption, AODV with CSMA/CA, and OLSR with CSMA/CA structures.

Interleaver Design for Mobile Satellite Communication Systems Using LTE based AMC Scheme (이동 위성통신 시스템에서의 LTE 기반 AMC 방식을 위한 인터리버 설계)

  • Yeo, Sung-Moon;Hong, Tae-Chul;Kim, Soo-Young;Song, Sang-Seob;Ahn, Do-Seob
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.3
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    • pp.8-15
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    • 2010
  • Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the most powerful candidates of the 4G system Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaγer design results considering mobile satellite system based on the LTE and analyze the simulation results.

The Channel Scheduler based on Water-filling Algorithm for Best Effort Forward Link Traffics in AMC/TDM/CDM System (AMC/TDM/CDM 다중접속방식에서의 Best Effort 순방향 서비스를 위한 Water-filling Based 채널 스케줄러)

  • Ma, Dongl-Chul;Ki, Young-Min;Kim, Dong-Ku
    • Journal of Advanced Navigation Technology
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    • v.7 no.1
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    • pp.59-71
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    • 2003
  • The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.

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