A Novel Construction of Multi-group Decodable Space-Time Block Codes

Complex Orthogonal Design (COD) codes are known to have the lowest detection complexity among Space-Time Block Codes (STBCs). However, the rate of square COD codes decreases exponentially with the number of transmit antennas. The Quasi-Orthogonal Design (QOD) codes emerged to provide a compromise between rate and complexity as they offer higher rates compared to COD codes at the expense of an increase of decoding complexity through partially relaxing the orthogonality conditions. The QOD codes were then generalized with the so called g-symbol and g-group decodable STBCs where the number of orthogonal groups of symbols is no longer restricted to two as in the QOD case. However, the adopted approach for the construction of such codes is based on sufficient but not necessary conditions which may limit the achievable rates for any number of orthogonal groups. In this paper, we limit ourselves to the case of Unitary Weight (UW)-g-group decodable STBCs for 2^a transmit antennas where the weight matrices are required to be single thread matrices with non-zero entries in {1,-1,j,-j} and address the problem of finding the highest achievable rate for any number of orthogonal groups. This special type of weight matrices guarantees full symbol-wise diversity and subsumes a wide range of existing codes in the literature. We show that in this case an exhaustive search can be applied to find the maximum achievable rates for UW-g-group decodable STBCs with g>1. For this purpose, we extend our previously proposed approach for constructing UW-2-group decodable STBCs based on necessary and sufficient conditions to the case of UW-g-group decodable STBCs in a recursive manner.Comment: 12 pages, and 5 tables, accepted for publication in IEEE transactions on communication

A New Low-Complexity Decodable Rate-1 Full-Diversity 4 x 4 STBC with Nonvanishing Determinants

Space-time coding techniques have become common-place in wireless communication standards as they provide an effective way to mitigate the fading phenomena inherent in wireless channels. However, the use of Space-Time Block Codes (STBCs) increases significantly the optimal detection complexity at the receiver unless the low complexity decodability property is taken into consideration in the STBC design. In this letter we propose a new low-complexity decodable rate-1 full-diversity 4 x 4 STBC. We provide an analytical proof that the proposed code has the Non-Vanishing-Determinant (NVD) property, a property that can be exploited through the use of adaptive modulation which changes the transmission rate according to the wireless channel quality. We compare the proposed code to existing low-complexity decodable rate-1 full-diversity 4 x 4 STBCs in terms of performance over quasi-static Rayleigh fading channels, detection complexity and Peak-to-Average Power Ratio (PAPR). Our code is found to provide the best performance and the smallest PAPR which is that of the used QAM constellation at the expense of a slight increase in detection complexity w.r.t. certain previous codes but this will only penalize the proposed code for high-order QAM constellations.Comment: 5 pages, 3 figures, and 1 table; IEEE Transactions on Wireless Communications, Vol. 10, No. 8, AUGUST 201

A New Low-Complexity Decodable Rate-5/4 STBC for Four Transmit Antennas with Nonvanishing Determinants

The use of Space-Time Block Codes (STBCs) increases significantly the optimal detection complexity at the receiver unless the low-complexity decodability property is taken into consideration in the STBC design. In this paper we propose a new low-complexity decodable rate-5/4 full-diversity 4 x 4 STBC. We provide an analytical proof that the proposed code has the Non-Vanishing-Determinant (NVD) property, a property that can be exploited through the use of adaptive modulation which changes the transmission rate according to the wireless channel quality. We compare the proposed code to the best existing low-complexity decodable rate-5/4 full-diversity 4 x 4 STBC in terms of performance over quasi-static Rayleigh fading channels, worst- case complexity, average complexity, and Peak-to-Average Power Ratio (PAPR). Our code is found to provide better performance, lower average decoding complexity, and lower PAPR at the expense of a slight increase in worst-case decoding complexity.Comment: 5 pages, 2 figures and 1 table; IEEE Global Telecommunications Conference (GLOBECOM 2011), 201

Assessing Chinas Development Cooperation Policy Towards African Countries: the case of Egypt

학위논문 (석사) -- 서울대학교 대학원 : 국제대학원 국제학과(국제지역학전공), 2020. 8. 정영록.본 연구는 아프리카에 대한 중국의 개발협력 정책이 양자간 및 다자간 협력을 통해 이루어지면서 FOCAC가 설립된 이후로 어떻게 변화했는지, 특히 이집트에 대한 정책의 변화를 알아보기 위한 것이다. 이를 위해서는 질문 몇 가지를 던져야 한다. 아프리카에 대한 중국의 발전 협력이 얼마만큼 특별한가? 나아가, 중국은 아프리카에 어느 정도까지 관심이 있으며, 왜 그런가? 아프리카 국가들에 대한 중국의 발전 정책은 무엇인가? 중국이 아프리카 내 세계 은행과 어떻게 협력하는가? 아프리카 국가들은 대륙 내 중국의 존재, 그리고 그 미래를 어떻게 보는가? 또한, 중국의 새로운 국제금융기구들은 아프리카에서 지속가능한 발전을 이룰 수 있는가? 연구 결과에 따르면 중국의 개발 협력은 다른 공여국과는 다르다. 중국은 다른 공여국이 아프리카 국가들에 제공한 원조의 양이나 유형, 그리고 우선순위에 주의를 기울이지 않았다. 또한, 아프리카에 대한 중국의 관심은 단순히 원자재 구매를 넘어서고 있다. 중국은 아프리카에 최대 공여국이 되겠다는 약속을 했고 결국 아프리카의 가장 큰 공여국이 되었으며, 2009~2012년과 2015년 및 2018년 사이에 아프리카에 대한 지원을 두 배로 늘렸다.This study is to figure out the change of Chinas Development Cooperation policy toward Africa Since set up FOCAC, in particular, Egypt, through bilateral and multilateral cooperation. To address some pertinent questions to what extent Chinas developmental cooperation toward Africa is unique? Furthermore, how far is China interested in Africa, and why? What is the Chinese Policy for development toward African countries? How China cooperate with the World Bank in Africa? How do African governments view China's presence on the continent and the future? Moreover, Does Chinas New International Financing Institutions can achieve Sustainable development in African countries? The study result showed that China's development cooperation is different from other donors. China did not pay attention to the amount or types or priorities of aid given to African countries by other donors. In addition to China, interest in Africa goes beyond the procurement of raw materials. China promises to be the largest donor to Africa, and they become the most significant donor eventually to Africa, and they double its aid to African countries between 2009 - 2012, and in 2015 & 2018.CHAPTER I: Introduction 1 1.1 Background 1 1.2 Significance of the study 3 1.3 Purpose of research 3 1.4 Hypothesis and research questions 3 1.5 Scope of the research 4 1.6 Organization of the Study 4 CHAPTER II: LITERATURE REVIEW AND METHODOLOGY 6 2.1 Literature review 6 2.2 Methodology 10 CHAPTER III: China's development cooperation policy toward Africa 12 3.1 Background 12 3.1.1 A brief history of Africa-China relations 12 3.2 The framework of China Development Cooperation 13 3.2.1 China Development Cooperation instruments 13 3.2.1.1 First: Multilateral cooperation 13 3.2.1.2 Second: bilateral cooperation 14 3.2.1.3 Fourth: China International Development Cooperation Agency (CIDCA) 17 3.3 Analysis of the development cooperation instruments in African countries 18 3.3.1 China's Development Cooperation and Africa 18 3.3.2 Chinese infrastructure investment and the effectiveness of Chinese aid in Africa: 20 3.3.3 China Loans to Africa 25 3.3.4 China Africa Trade 29 3.3.5 China FDI to Africa 29 3.3.6 A brief comparison between Japan-China ODA to Africa 30 3.3.7 China Multilateral Cooperation and World Bank Cooperation 31 3.3.8 How China Is Take Advantage of Multilateral cooperation 32 CHAPTER IV: Case study China's Development Cooperation in Egypt 40 4.1 Egypt and China 40 4.2 China Aid to Egypt 41 4.3 Trade between China and Egypt 44 4.1 China FDI to Egypt. 45 4.5 The Case of Egypt: Project is "Remote Education System Upgrade. 47 CHAPTER V: Conclusion & Policy Recommendations 50 5.1 Policy Recommendation for a Better Cooperation 50 5.1.1 To China 50 5.1.2 To Egypt and African Countries 50 5.2 Conclusion 53 5.2.1 Limitations 53 5.2.2 Conclusion 53 REFERENCES 56 APPENDIX. 61 (Korean Abstract) 68Maste

Energy-Efficient Cooperative Protocols for Full-Duplex Relay Channels

In this work, energy-efficient cooperative protocols are studied for full-duplex relaying (FDR) with loopback interference. In these protocols, relay assistance is only sought under certain conditions on the different link outages to ensure effective cooperation. Recently, an energy-efficient selective decode-and-forward protocol was proposed for FDR, and was shown to outperform existing schemes in terms of outage. Here, we propose an incremental selective decode-and-forward protocol that offers additional power savings, while keeping the same outage performance. We compare the performance of the two protocols in terms of the end-to-end signal-to-noise ratio cumulative distribution function via closed-form expressions. Finally, we corroborate our theoretical results with simulation, and show the relative relay power savings in comparison to non-selective cooperation in which the relay cooperates regardless of channel conditions

A New Family of Low-Complexity Decodable STBCs for Four Transmit Antennas

In this paper we propose a new construction method for rate-1 Fast-Group-Decodable (FGD) Space-Time-Block Codes (STBC)s for 2^a transmit antennas. We focus on the case of a=2 and we show that the new FGD rate-1 code has the lowest worst-case decoding complexity among existing comparable STBCs. The coding gain of the new rate-1 code is then optimized through constellation stretching and proved to be constant irrespective of the underlying QAM constellation prior to normalization. In a second step, we propose a new rate-2 STBC that multiplexes two of our rate-1 codes by the means of a unitary matrix. A compromise between rate and complexity is then obtained through puncturing our rate-2 code giving rise to a new rate-3/2 code. The proposed codes are compared to existing codes in the literature and simulation results show that our rate-3/2 code has a lower average decoding complexity while our rate-2 code maintains its lower average decoding complexity in the low SNR region at the expense of a small performance loss.Comment: 5 pages, 4 figures and 1 table. Accepted for publication in IEEE International Conference on Communications (ICC 2012), 201

B738: Costs and Returns in Lowbush Blueberry Production in Maine, 1974 Crop

Blueberry production is primarily a part time enterprise with a wide variation in acreages per grower and a modest investment per acre. Blueberry growers recovered cash costs and most of the variable costs of producing and harvesting the 1974 crop. For a competitive return on investment and a modest wage, the average grower would have had to receive 35 cents rather than 20 cents per pound, considering the yields obtained in 1974. To be reasonably assured of adequate returns, a grower should achieve yields of over 1,000 pounds per acre.https://digitalcommons.library.umaine.edu/aes_bulletin/1086/thumbnail.jp