Adaptive reinforcement learning for heterogeneous network selection

Next generation 5G mobile wireless networks will consist of multiple technologies for devices to access the network at the edge. One of the keys to 5G is therefore the ability for device to intelligently select its Radio Access Technology (RAT). Current fully distributed algorithms for RAT selection although guaranteeing convergence to equilibrium states, are often slow, require high exploration times and may converge to undesirable equilibria. In this dissertation, we propose three novel reinforcement learning (RL) frameworks to improve the efficiency of existing distributed RAT selection algorithms in a heterogeneous environment, where users may potentially apply a number of different RAT selection procedures. Although our research focuses on solutions for RAT selection in the current and future mobile wireless networks, the proposed solutions in this dissertation are general and suitable to apply for any large scale distributed multi-agent systems. In the first framework, called RL with Non-positive Regret, we propose a novel adaptive RL for multi-agent non-cooperative repeated games. The main contribution is to use both positive and negative regrets in RL to improve the convergence speed and fairness of the well-known regret-based RL procedure. Significant improvements in performance compared to other related algorithms in the literature are demonstrated. In the second framework, called RL with Network-Assisted Feedback (RLNF), our core contribution is to develop a network feedback model that uses network-assisted information to improve the performance of the distributed RL for RAT selection. RLNF guarantees no-regret payoff in the long-run for any user adopting it, regardless of what other users might do and so can work in an environment where not all users use the same learning strategy. This is an important implementation advantage as RLNF can be implemented within current mobile network standards. In the third framework, we propose a novel adaptive RL-based mechanism for RAT selection that can effectively handle user mobility. The key contribution is to leverage forgetting methods to rapidly react to the changes in the radio conditions when users move. We show that our solution improves the performance of wireless networks and converges much faster when users move compared to the non-adaptive solutions. Another objective of the research is to study the impact of various network models on the performance of different RAT selection approaches. We propose a unified benchmark to compare the performances of different algorithms under the same computational environment. The comparative studies reveal that among all the important network parameters that influence the performance of RAT selection algorithms, the number of base stations that a user can connect to has the most significant impact. This finding provides some guidelines for the proper design of RAT selection algorithms for future 5G. Our evaluation benchmark can serve as a reference for researchers, network developers, and engineers. Overall, the thesis provides different reinforcement learning frameworks to improve the efficiency of current fully distributed algorithms for heterogeneous RAT selection. We prove the convergence of the proposed reinforcement learning procedures using the differential inclusion (DI) technique. The theoretical analyses demonstrate that the use of DI not only provides an effective method to study the convergence properties of adaptive procedures in game-theoretic learning, but also yields a much more concise and extensible proof as compared to the classical approaches.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

베트남 소비자들의 한국 인삼 제품 구매에 영향을 미치는 요인 분석: 다낭과 후에를 중심으로

학위논문(석사)--서울대학교 대학원 :농업생명과학대학 농경제사회학부(농경제학전공),2019. 8. Jung, Jin Hwa.This study aims to identify factors influencing the purchase intentions of Vietnamese consumers towards Korean ginseng root products and further propose appropriate marketing strategies. The data was collected from 701 consumers in Hue and Da Nang through an online survey and analyzed using the exploratory factor analysis and multiple regression analysis. The results indicated that perceived value and household with elderly affected the purchase intention of consumers in both Hue and Da Nang. While traditional word of mouth was found as a factor influencing consumers in Hue, consumers in Da Nang were positively affected by electronic word of mouth. With further regard to Da Nang, in addition to income, the consumer attitude about social prestige and the social norm that Korean ginseng root products are only used for the elderly was also identified as another positive factor. Based on these findings, 4P marketing strategies are suggested to motivate the purchase intention in Hue and Da Nang. This study pointed out the differences between consumer purchase behavior in Hue and Da Nang, which indicates an incentive for marketers to develop specific marketing strategies for each region.본 연구는 베트남 소비자가 한국 인삼제품을 구매할 때 어떤 요인이 중요하게 작용하는지 분석하고, 이에 대한 마케팅 전략을 제시하는 데 목적이 있다. 분석자료 확보를 위해 베트남 다낭(Da Nang)지역과 후에(Hue)지역 701명의 소비자를 대상으로 온라인 설문조사를 실시했으며, 이를 바탕으로 탐색적 요인 분석과 다중회귀 분석을 수행하였다. 본 연구는 후에(Hue)와 다낭(Da Nang) 지역을 나누어 분석함으로써 지역별 맞춤형 마케팅 전략을 개발할 수 있도록 유도했다는 데 의의가 있다. 주요 분석결과를 요약하면 다음과 같다. 첫째, 인삼제품에 대한 주관적 가치(perceived value)가 높거나 고령자와 함께 거주하는 소비자의 경우, 두 지역 모두에서 한국 인삼제품을 구매할 의향이 높은 것으로 나타났다. 둘째, 후에(Hue)지역 소비자의 인삼제품 구매의향은 전통적 입소문(traditional word of mouth)에 주로 영향을 받았으나, 다낭(Da Nang)지역 소비자는 매체를 통한 입소문(electronic word of mouth)에 많은 영향을 받는 것으로 나타났다. 셋째, 다낭(Da Nang)지역 소비자의 경우, 개인의 소득증가가 인삼제품 구매의향을 증가시키는 요인이었으며, 나아가 한국 인삼제품 소비가 고령자의 권위와 관련된다는 사회적 인식도 인삼제품 구매의향 증대의 주요 요인이었다. 넷째, 높은 영양분 함량이 인삼제품 구매결정에 중요한 영향 요인이며 다음으로 세련된 디자인 및 포장재, 브랜드 가치, 6년근 인삼여부, 신선도의 순서로 중요했다. 다섯째, 인삼제품 구매장소 선호도에서 다낭(Da Nang)과 후에(Hue)의 소비자들은 차이를 보였다. 구체적으로, 다낭(Da Nang)지역 소비자는 전문 매장을 선호하며, 후에(Hue)지역 소비자는 지인을 통해 구매하거나 한국 여행을 통해 직접 구매하는 것을 선호하는 것으로 나타났다. 본 연구는 베트남의 두 지역 모두에서 한국 인삼제품 수요가 개인 및 가족의 건강에 대한 관심, 사회적 명성, 원만한 대인관계 등에 기인하는 것을 보여주고 있다. 다시 말해, 소비자는 인삼제품을 구매하기 위한 일련의 정보(판매처의 연락처 및 신뢰도, 결제방법, 유통 및 저장 방식 등)에 민감하게 반응한다. 이러한 상황에서 가족은 물론 소셜 네트워크, 대중매체, 여행업체 등 많은 외부요인들이 제품정보를 개인에게 효과적으로 제공하고 있으며, 이러한 과정이 베트남 소비자의 한국 인삼제품에 대한 수요에 영향을 미친다고 볼 수 있다. 분석결과를 정리했을 때, 후에(Hue)와 다낭(Da Nang) 소비자의 구매 의향을 높이기 위해 4P 마케팅 전략이 실시될 필요가 있다고 판단된다.Abstract i Table of Contents iii List of Figures v List of Tables vi Chapter 1. Introduction 1 1. Statement of the problem 1 2. Research objectives 5 3. Scope of study 6 4. Significance of the study 6 Chapter 2. Literature Review 8 1. Consumer behavior theory 8 1.1. Consumer purchase intention 8 1.2. Consumer buying behavior 8 1.3. Consumer buying decisions models 10 2. Research on purchase behavior 14 2.1. Factors affecting purchase intention towards healthy products 14 2.2. Consumer behavior towards Korean ginseng products 18 Chapter 3. Theoretical Framework and Hypotheses 22 1. Consumer awareness and its influence on purchase intention 22 2. Perceived value and its influence on purchase intention 23 3. Word of mouth and its influence on purchase intention 25 4. Demographic variables 26 Chapter 4. Methodology 28 1. Data collection 28 2. Data analysis 34 2.1. Results of the reliability of measurements test 34 2.2. Results of exploratory factor analysis 35 2.3. Pearson correlation coefficients 39 Chapter 5. Results 43 1. Purchase behavior towards Korean ginseng root products 43 1.1. Need recognition of Korean ginseng root products 43 1.2. Information search 45 1.3. Evaluation of alternatives 47 1.4. Purchase intention and purchase decision 48 1.5. Post purchase evaluation 49 2. Results of hypothesis test 50 2.1. The case of Hue 50 2.2. The case of Da Nang 52 Chapter 6. Discussion and Conclusion 57 1. Summary and discussion 57 1.1. Purchase behavior towards Korean ginseng root products in Hue and Da Nang 57 1.2. Results of hypothesis test 59 2. Implications 60 2.1. Korean companies 60 2.2. Korean government 63 3. Limitations 63 3.1. The limitation of methodology 63 3.2. The limitation of research scope 64 Appendix 75 국문초록 108 Acknowledgement 111Maste

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学位記番号：医博甲165