The article examines the issues of regional security and prospects of cooperation between the countries of Central Asia in the context of a new world order. As factors of sustainable development and security, the auth...The article examines the issues of regional security and prospects of cooperation between the countries of Central Asia in the context of a new world order. As factors of sustainable development and security, the author considers the following issues: preservation of the geopolitical balance in Central Asia; development of a multivariate system of transportation and communication corridors; cardinal increase in the efficiency of counterterrorism and religious extremism; a solution to the Afghan problem; and resolution to the problems of fair water use and ecology in the region.展开更多
Japan-UK security cooperation has been deepening as the Indo-Pacific Strategy has converged with Global Britain,which has become strongly Indo-Pacific-oriented.In terms of their cooperation on security,the two countri...Japan-UK security cooperation has been deepening as the Indo-Pacific Strategy has converged with Global Britain,which has become strongly Indo-Pacific-oriented.In terms of their cooperation on security,the two countries have close security interactions,high-level security consultations,numerous mechanisms on security cooperation,frequent defense cooperation and exchanges between forces,and cooperation geared at a response to the Korean nuclear issue.In particular,Japan and the UK regard Indo-Pacific security as the strategic focus of their cooperation,and this underscores the rules-based international order.There are multiple motivations for Japan and the UK to strengthen their security cooperation,and the deepening of their security cooperation in the Indo-Pacific region is to a great extent due to strategic factors,including responding to the US strategic adjustment,Japan and Britain’s respective proactive strategic demands,the improving strategic positions of the Indopacific region,their seeking to shape the regional order in the Indo-Pacific,and so on.Despite facing challenges,Japan-UK security cooperation is continuously strengthening against a background of deepening strategic convergence between the two countries and great power competition.展开更多
Non-traditional security issues have arisen since the 1960s,especially after the end of the Cold War,and are becoming a major issue in world security and politics.This reflects tremendous changes in the world situatio...Non-traditional security issues have arisen since the 1960s,especially after the end of the Cold War,and are becoming a major issue in world security and politics.This reflects tremendous changes in the world situation.With diverse causes and plural referent objects,non-traditional security issues cover nearly all the problems in the world today and make development difficult to sustain.This raises the question of whether human society and the earth can survive.Power politics one-sidedly stresses the role of power,endangering the harmonious development of nations and the whole of human society.It is not at all conducive to the solution of non-traditional security issues.The solution of non-traditional security issues demands cooperation from all actors in the international community.Multiple means are needed to solve these issues.Equal dialogue between all the actors,which can easily be attained,will play an effective role,as long as all actors respect each other's differences.展开更多
Energy security is an issue that many countries pay more attention to. Cooperation is a good way to solute it. According to the complex system theory, the regional energy cooperation means a state or process of balanc...Energy security is an issue that many countries pay more attention to. Cooperation is a good way to solute it. According to the complex system theory, the regional energy cooperation means a state or process of balance system formed by the interaction and behavior coordination between agents. The features of the regional energy cooperation risk include: uncertainty, potential, fuzziness, diversity, relevance and particularity. And the regional energy cooperation risk can be divided into risk inside the system such as main body ability structure of the risk and main body decision-making risk, and the risk outside the system such as external environment factors and cooperation pattern factors.展开更多
In recent years, India-US security cooperation has accelerated, overall defense cooperation framework has become increasingly mature and has been continuously updated with the times. The scale of India* s imports of w...In recent years, India-US security cooperation has accelerated, overall defense cooperation framework has become increasingly mature and has been continuously updated with the times. The scale of India* s imports of weapons and military supplies from the United States has continued to expand, and India-US joint military exercises have deepened. Since the Modi government took office in 2014, it has signed two basic military cooperation pacts with the United States, paving the way for further upgrading the two countries' defense cooperation in the future. India-US counter-terrorism cooperation is starting from scratch and continuing to deepen, further expanding the contents of their security cooperation. India-US close security cooperation has had a serious negative impact on India’s overall foreign strategy, especially its tradition of long-standing strategic independence. It has eroded material and institutional foundations for India ’ s strategic autonomy, and deteriorated India’ s geostrategic environment, which is not conducive to realizing its dream of being a great power.展开更多
The African economy,with average annual growth of 5%during 1995 to 2014,greatly interests investors but the current security situation hampers regional development and foreign direct investment.Investment in Africa ha...The African economy,with average annual growth of 5%during 1995 to 2014,greatly interests investors but the current security situation hampers regional development and foreign direct investment.Investment in Africa has featured high return and high risk historically,and it remains clear that no single entity can properly solve current security challenges that Africa faces.The moment calls for international joint collaboration and concerted effort on the part of China,the US and African countries.展开更多
Everyone is surrounded by crisis just like the air we breathe at every moment;therefore, all countries, organizations and person are confronted with the risk challenges. Nowadays, the human society has evolved to a re...Everyone is surrounded by crisis just like the air we breathe at every moment;therefore, all countries, organizations and person are confronted with the risk challenges. Nowadays, the human society has evolved to a relatively advanced stage, and along with society progress, complicated social relationship and environment will result in more dangerous elements, thus bringing in more risks. This paper introduces the public security crisis management model based on diversified cooperation in detail from the concept of public security crisis and puts forward safeguard mechanism construction for enhancing the crisis management under diversified cooperation in a brief manner, thus improving the efficiency of crisis management under diversified cooperation.展开更多
To integrate the satellite communications with the LTE/5G services, the concept of Hybrid Satellite Terrestrial Relay Networks(HSTRNs) has been proposed. In this paper, we investigate the secure transmission in a HSTR...To integrate the satellite communications with the LTE/5G services, the concept of Hybrid Satellite Terrestrial Relay Networks(HSTRNs) has been proposed. In this paper, we investigate the secure transmission in a HSTRN where the eavesdropper can wiretap the transmitted messages from both the satellite and the intermediate relays. To effectively protect the message from wiretapping in these two phases, we consider cooperative jamming by the relays, where the jamming signals are optimized to maximize the secrecy rate under the total power constraint of relays. In the first phase, the Maximal Ratio Transmission(MRT) scheme is used to maximize the secrecy rate, while in the second phase, by interpolating between the sub-optimal MRT scheme and the null-space projection scheme, the optimal scheme can be obtained via an efficient one-dimensional searching method. Simulation results show that when the number of cooperative relays is small, the performance of the optimal scheme significantly outperforms that of MRT and null-space projection scheme. When the number of relays increases, the performance of the null-space projection approaches that of the optimal one.展开更多
In cognitive radio networks(CRNs), through recruiting secondary user(SU) as friendly jammer, the secrecy rate obtained by primary user(PU) can be improved. Previous work only considered a simple scenario with a single...In cognitive radio networks(CRNs), through recruiting secondary user(SU) as friendly jammer, the secrecy rate obtained by primary user(PU) can be improved. Previous work only considered a simple scenario with a single PU in their frameworks. In this paper, we will consider a more complicated scenario with multiple PUs and try to investigate the cooperative jamming between multiple PUs and a single SU. When there are multiple PUs in CRN, in order to obtain more spectrum for data transmission, SU will cooperate with multiple PUs at the same time. Considering that both PU and SU are rational and selfish individuals, the interaction between PUs and SU is formulated as a multi-leaders and single-follower Stackelberg game, wherein PU is the leader and SU is the follower. And the Stackelberg Equilibrium(SE) is considered as the final decisions accepted by all PUs and SU. Furthermore, we also prove that when a specific condition is satisfied, the existence of SE can be guaranteed. And a Gauss-Jacobi iterative algorithm is proposed to compute a SE. Finally, simulation results are given to verify the performance and demonstrate that both of the PUs' secrecy rate and the SU's transmission rate can be improved through cooperation.展开更多
Current status of several management models of the agriculture industry is introduced,as well as its impacts on industrial security.The management models are mainly the enterprise-like operation model,"enterprise...Current status of several management models of the agriculture industry is introduced,as well as its impacts on industrial security.The management models are mainly the enterprise-like operation model,"enterprise + peasant household" model,small-scale peasants' operation model,and peasant specialized cooperative model.Functions of peasant specialized cooperative in ensuring the security of agricultural industry are introduced,which are enhancing the industrial security by organization degree,promoting the industrial security by scale economy formed by cooperative organizations,fully utilizing the resources by the factor allocation capability,and ensuring the industrial security by industrial chain improvement.Development predicaments of the peasant specialized cooperative at present are analyzed,such as small scale,poor economic benefits,and non-standard operation.Analysis shows that institutional absence is the main reason causing these predicaments.And suggestions on improving the cooperatives system in the Law of the People's Republic of China on Peasants Specialized Cooperatives are put forward,in order to better ensure the security of agriculture展开更多
The properties of broadcast nature, high densities of deployment and severe resource limitations of sensor and mobile networks make wireless networks more vulnerable to various attacks, including modification of messa...The properties of broadcast nature, high densities of deployment and severe resource limitations of sensor and mobile networks make wireless networks more vulnerable to various attacks, including modification of messages, eavesdropping, network intrusion and malicious forwarding. Conventional cryptography-based security may consume significant overhead because of low-power devices, so current research shifts to the wireless physical layer for security enhancement. This paper is mainly focused on security issues and solutions for wireless communications at the physical layer. It first describes the RSSI-based and channel based wireless authentication methods respectively, and presents an overview of various secrecy capacity analyses of fading channel, MIMO channel and cooperative transmission, and then examines different misbehavior detection methods. Finally it draws conclusions and introduces the direction of our future work.展开更多
The ultra-dense low earth orbit(LEO)integrated satellite-terrestrial networks(UDLEO-ISTN)can bring lots of benefits in terms of wide coverage,high capacity,and strong robustness.Meanwhile,the broadcasting and open nat...The ultra-dense low earth orbit(LEO)integrated satellite-terrestrial networks(UDLEO-ISTN)can bring lots of benefits in terms of wide coverage,high capacity,and strong robustness.Meanwhile,the broadcasting and open natures of satellite links also reveal many challenges for transmission security protection,especially for eavesdropping defence.How to efficiently take advantage of the LEO satellite’s density and ensure the secure communication by leveraging physical layer security with the cooperation of jammers deserves further investigation.To our knowledge,using satellites as jammers in UDLEO-ISTN is still a new problem since existing works mainly focused on this issue only from the aspect of terrestrial networks.To this end,we study in this paper the cooperative secrecy communication problem in UDLEOISTN by utilizing several satellites to send jamming signal to the eavesdroppers.An iterative scheme is proposed as our solution to maximize the system secrecy energy efficiency(SEE)via jointly optimizing transmit power allocation and user association.Extensive experiment results verify that our designed optimization scheme can significantly enhance the system SEE and achieve the optimal power allocation and user association strategies.展开更多
A series of water disputes and conflicts have gradually emerged between China and some neighboring countries after 2000, influencing China's neighborhood relations. China increasingly realizes the importance and u...A series of water disputes and conflicts have gradually emerged between China and some neighboring countries after 2000, influencing China's neighborhood relations. China increasingly realizes the importance and urgency of the water resource governance in the regional cooperation, but under complicated geopolitical context, China's water resource governance must serve several important main functions in its regional cooperation. Overall, water resource governance is the demands of crisis management and conflict prevention, and also is a kind of positive factor that promotes sub-regional cooperation. From the perspective of the current situation, China should take more proactive attitude toward the water resource governance, expand the areas and stakeholders of the water resource governance, and thus promote the formulation of water resource governance strategy.展开更多
As to the safety threats faced by sensor networks (SN), nodes limitations of computation, memory and communication, a secure location algorithm (node cooperative secure localization, NCSL) is presented in this pap...As to the safety threats faced by sensor networks (SN), nodes limitations of computation, memory and communication, a secure location algorithm (node cooperative secure localization, NCSL) is presented in this paper. The algorithm takes the improvements of SN location information security as its design targets, utilizing nodes' cooperation to build virtual antennae array to communicate and localize, and gains arraying antenna advantage for SN without extra hardware cost, such as reducing multi-path effects, increasing receivers' signal to noise ratio and system capa- bility, reducing transmitting power, and so on. Simulations show that the algorithm based on virtual antennae array has good localization ability with a at high accuracy in direction-of-arrival (DOA) estimation, and makes SN capable to resist common malicious attacks, especially wormhole attack, by using the judgment rules for malicious attacks.展开更多
Space is an important part of the Sino-US relationship. It reflects the general direction of bilateral relations, yet has its own development trajectory. As Sino-US relations had their ups and downs in the 1990 s, spa...Space is an important part of the Sino-US relationship. It reflects the general direction of bilateral relations, yet has its own development trajectory. As Sino-US relations had their ups and downs in the 1990 s, space cooperation between the two countries was relatively consistent and stable. But as economy and trade became more and more deeply intertwined in the 21 st century, space cooperation lost its momentum. This paper intends to explore the reasons behind this strange development trajectory by analyzing the security, political, legislative and economic factors affecting bilateral space cooperation. It also tries to analyze the prospect of Sino-US space cooperation in President Trump's term.展开更多
Nonproliferation cooperation has always been a bright spot in China-US security cooperation for over more than a decade. China and the U.S. should timely adjust the focus of their nonproliferation cooperation on a mor...Nonproliferation cooperation has always been a bright spot in China-US security cooperation for over more than a decade. China and the U.S. should timely adjust the focus of their nonproliferation cooperation on a more equal basis, expanding common interests and exploring new patterns for cooperation so as to create a model for the two countries to join hands in global governance and maintenance of regional order.展开更多
With the low cost and low hardware complex considerations,cooperative systems are a tendency in the future communications.This work considers the secure cooperative communications systems.For a practical situation in ...With the low cost and low hardware complex considerations,cooperative systems are a tendency in the future communications.This work considers the secure cooperative communications systems.For a practical situation in the system,the scenario includes multiple source stations,multiple relay stations,multiple destination stations,and eavesdroppers.To analyze the optimal relay selection in the system,we begin with the performance analysis for a single source station and a single destination station.By applying two cooperative models,the amplify-andforward(AF) mode and decode-and-forward(DF)mode,the secrecy capacity is derived.Then,we apply the derived results to the considered environment to find the optimal relay assignment.By the way,the relay selection can be obtained by the exhaustive search algorithm.However,there are a lot of steps needed if the number of source stations is large.Hence,applying the characters of the cooperative modes in the relay selection,the pre-selection step is proposed with a mathematical derivation.It could be used for the practical situation without a long-time calculation.展开更多
Global climate change-essentially an adverse consequence of global warming, is principally caused by progressive build-up and extensive spread of greenhouse gases (GHGs) across countries, regions or continents because...Global climate change-essentially an adverse consequence of global warming, is principally caused by progressive build-up and extensive spread of greenhouse gases (GHGs) across countries, regions or continents because of earth’s rotational movement. The potent sources of GHGs are fossil-fuels and biomass. With the increasing pace of globalization, industrialization and rapid change of life-style the demand and consumption of these feed-stocks to stimulate economic growth is steadily rising-both in the developing and developed economy. In the process, the emissions level is also rising phenomenally;and of late become quite alarming-more in the former than latter case, affecting thereby the environmental quality as also its security concerns globally. This paper highlights the major impacts of global warming and consequential climate change on the environmental quality and overall security aspects-including commercial, strategic and defense angles for the South-Asian region. The paper also discusses some relevant aspects linking the larger question of energy security with environmental security through the approach of sustainable energy development for envisioning a balanced economic development as well as growth perspective for South Asia. The significance of International cooperation in the mitigation and adaptation of climate change impacts with special reference to Asia- Pacific and South Asian region is also discussed at some length in the paper.展开更多
基金the initial result of a major research project funded by the National Social Science Foundation, titled "The Belt and Road Initiative and the Building of International Rules" (Project No.:18DVL002)
文摘The article examines the issues of regional security and prospects of cooperation between the countries of Central Asia in the context of a new world order. As factors of sustainable development and security, the author considers the following issues: preservation of the geopolitical balance in Central Asia; development of a multivariate system of transportation and communication corridors; cardinal increase in the efficiency of counterterrorism and religious extremism; a solution to the Afghan problem; and resolution to the problems of fair water use and ecology in the region.
基金This article is a phased outcome of the National Social Sciences Foundation project:“Japan’s Adjustment of China Strategy in the Context of Belt and Road Initiative and China’s Response”(Project Number:18BGJ056).
文摘Japan-UK security cooperation has been deepening as the Indo-Pacific Strategy has converged with Global Britain,which has become strongly Indo-Pacific-oriented.In terms of their cooperation on security,the two countries have close security interactions,high-level security consultations,numerous mechanisms on security cooperation,frequent defense cooperation and exchanges between forces,and cooperation geared at a response to the Korean nuclear issue.In particular,Japan and the UK regard Indo-Pacific security as the strategic focus of their cooperation,and this underscores the rules-based international order.There are multiple motivations for Japan and the UK to strengthen their security cooperation,and the deepening of their security cooperation in the Indo-Pacific region is to a great extent due to strategic factors,including responding to the US strategic adjustment,Japan and Britain’s respective proactive strategic demands,the improving strategic positions of the Indopacific region,their seeking to shape the regional order in the Indo-Pacific,and so on.Despite facing challenges,Japan-UK security cooperation is continuously strengthening against a background of deepening strategic convergence between the two countries and great power competition.
文摘Non-traditional security issues have arisen since the 1960s,especially after the end of the Cold War,and are becoming a major issue in world security and politics.This reflects tremendous changes in the world situation.With diverse causes and plural referent objects,non-traditional security issues cover nearly all the problems in the world today and make development difficult to sustain.This raises the question of whether human society and the earth can survive.Power politics one-sidedly stresses the role of power,endangering the harmonious development of nations and the whole of human society.It is not at all conducive to the solution of non-traditional security issues.The solution of non-traditional security issues demands cooperation from all actors in the international community.Multiple means are needed to solve these issues.Equal dialogue between all the actors,which can easily be attained,will play an effective role,as long as all actors respect each other's differences.
文摘Energy security is an issue that many countries pay more attention to. Cooperation is a good way to solute it. According to the complex system theory, the regional energy cooperation means a state or process of balance system formed by the interaction and behavior coordination between agents. The features of the regional energy cooperation risk include: uncertainty, potential, fuzziness, diversity, relevance and particularity. And the regional energy cooperation risk can be divided into risk inside the system such as main body ability structure of the risk and main body decision-making risk, and the risk outside the system such as external environment factors and cooperation pattern factors.
文摘In recent years, India-US security cooperation has accelerated, overall defense cooperation framework has become increasingly mature and has been continuously updated with the times. The scale of India* s imports of weapons and military supplies from the United States has continued to expand, and India-US joint military exercises have deepened. Since the Modi government took office in 2014, it has signed two basic military cooperation pacts with the United States, paving the way for further upgrading the two countries' defense cooperation in the future. India-US counter-terrorism cooperation is starting from scratch and continuing to deepen, further expanding the contents of their security cooperation. India-US close security cooperation has had a serious negative impact on India’s overall foreign strategy, especially its tradition of long-standing strategic independence. It has eroded material and institutional foundations for India ’ s strategic autonomy, and deteriorated India’ s geostrategic environment, which is not conducive to realizing its dream of being a great power.
文摘The African economy,with average annual growth of 5%during 1995 to 2014,greatly interests investors but the current security situation hampers regional development and foreign direct investment.Investment in Africa has featured high return and high risk historically,and it remains clear that no single entity can properly solve current security challenges that Africa faces.The moment calls for international joint collaboration and concerted effort on the part of China,the US and African countries.
文摘Everyone is surrounded by crisis just like the air we breathe at every moment;therefore, all countries, organizations and person are confronted with the risk challenges. Nowadays, the human society has evolved to a relatively advanced stage, and along with society progress, complicated social relationship and environment will result in more dangerous elements, thus bringing in more risks. This paper introduces the public security crisis management model based on diversified cooperation in detail from the concept of public security crisis and puts forward safeguard mechanism construction for enhancing the crisis management under diversified cooperation in a brief manner, thus improving the efficiency of crisis management under diversified cooperation.
基金supported in part by the National Natural Science Foundation of China under Grant No.61871032in part by Chinese Ministry of Education-China Mobile Communication Corporation Research Fund under Grant MCM20170101in part by the Open Research Fund of Key Laboratory of Cognitive Radio and Information Processing,Ministry of Education (Guilin University of Electronic Technology) under Grant CRKL190204
文摘To integrate the satellite communications with the LTE/5G services, the concept of Hybrid Satellite Terrestrial Relay Networks(HSTRNs) has been proposed. In this paper, we investigate the secure transmission in a HSTRN where the eavesdropper can wiretap the transmitted messages from both the satellite and the intermediate relays. To effectively protect the message from wiretapping in these two phases, we consider cooperative jamming by the relays, where the jamming signals are optimized to maximize the secrecy rate under the total power constraint of relays. In the first phase, the Maximal Ratio Transmission(MRT) scheme is used to maximize the secrecy rate, while in the second phase, by interpolating between the sub-optimal MRT scheme and the null-space projection scheme, the optimal scheme can be obtained via an efficient one-dimensional searching method. Simulation results show that when the number of cooperative relays is small, the performance of the optimal scheme significantly outperforms that of MRT and null-space projection scheme. When the number of relays increases, the performance of the null-space projection approaches that of the optimal one.
基金supported in part by the National Key Research and Development Program of China under Grant 2016QY01W0204in part by Key Industrial Innovation Chain in Industrial Domain under Grant 2016KTZDGY-02in part by National High-Level TalentsSpecial Support Program of China under Grant CS31117200001
文摘In cognitive radio networks(CRNs), through recruiting secondary user(SU) as friendly jammer, the secrecy rate obtained by primary user(PU) can be improved. Previous work only considered a simple scenario with a single PU in their frameworks. In this paper, we will consider a more complicated scenario with multiple PUs and try to investigate the cooperative jamming between multiple PUs and a single SU. When there are multiple PUs in CRN, in order to obtain more spectrum for data transmission, SU will cooperate with multiple PUs at the same time. Considering that both PU and SU are rational and selfish individuals, the interaction between PUs and SU is formulated as a multi-leaders and single-follower Stackelberg game, wherein PU is the leader and SU is the follower. And the Stackelberg Equilibrium(SE) is considered as the final decisions accepted by all PUs and SU. Furthermore, we also prove that when a specific condition is satisfied, the existence of SE can be guaranteed. And a Gauss-Jacobi iterative algorithm is proposed to compute a SE. Finally, simulation results are given to verify the performance and demonstrate that both of the PUs' secrecy rate and the SU's transmission rate can be improved through cooperation.
文摘Current status of several management models of the agriculture industry is introduced,as well as its impacts on industrial security.The management models are mainly the enterprise-like operation model,"enterprise + peasant household" model,small-scale peasants' operation model,and peasant specialized cooperative model.Functions of peasant specialized cooperative in ensuring the security of agricultural industry are introduced,which are enhancing the industrial security by organization degree,promoting the industrial security by scale economy formed by cooperative organizations,fully utilizing the resources by the factor allocation capability,and ensuring the industrial security by industrial chain improvement.Development predicaments of the peasant specialized cooperative at present are analyzed,such as small scale,poor economic benefits,and non-standard operation.Analysis shows that institutional absence is the main reason causing these predicaments.And suggestions on improving the cooperatives system in the Law of the People's Republic of China on Peasants Specialized Cooperatives are put forward,in order to better ensure the security of agriculture
基金supported in part by State Key Program of National Nature Science Foundation of China under Grant No.60932003National High Technical Research and Development Program of China (863 Program ) under Grant No.2007AA01Z452
文摘The properties of broadcast nature, high densities of deployment and severe resource limitations of sensor and mobile networks make wireless networks more vulnerable to various attacks, including modification of messages, eavesdropping, network intrusion and malicious forwarding. Conventional cryptography-based security may consume significant overhead because of low-power devices, so current research shifts to the wireless physical layer for security enhancement. This paper is mainly focused on security issues and solutions for wireless communications at the physical layer. It first describes the RSSI-based and channel based wireless authentication methods respectively, and presents an overview of various secrecy capacity analyses of fading channel, MIMO channel and cooperative transmission, and then examines different misbehavior detection methods. Finally it draws conclusions and introduces the direction of our future work.
基金supported by National Key R&D Program of China(2022YFB3104200)in part by National Natural Science Foundation of China(62202386)+6 种基金in part by Basic Research Programs of Taicang(TC2021JC31)in part by Fundamental Research Funds for the Central Universities(D5000210817)in part by Xi’an Unmanned System Security and Intelligent Communications ISTC Centerin part by Special Funds for Central Universities Construction of World-Class Universities(Disciplines)and Special Development Guidance(0639022GH0202237 and 0639022SH0201237)in part by the Henan Key Scientific Research Program of Higher Education(23B510003,21A510008 and 21A510009)in part by Henan Key Scientific and Technological Projects(212102210553)。
文摘The ultra-dense low earth orbit(LEO)integrated satellite-terrestrial networks(UDLEO-ISTN)can bring lots of benefits in terms of wide coverage,high capacity,and strong robustness.Meanwhile,the broadcasting and open natures of satellite links also reveal many challenges for transmission security protection,especially for eavesdropping defence.How to efficiently take advantage of the LEO satellite’s density and ensure the secure communication by leveraging physical layer security with the cooperation of jammers deserves further investigation.To our knowledge,using satellites as jammers in UDLEO-ISTN is still a new problem since existing works mainly focused on this issue only from the aspect of terrestrial networks.To this end,we study in this paper the cooperative secrecy communication problem in UDLEOISTN by utilizing several satellites to send jamming signal to the eavesdroppers.An iterative scheme is proposed as our solution to maximize the system secrecy energy efficiency(SEE)via jointly optimizing transmit power allocation and user association.Extensive experiment results verify that our designed optimization scheme can significantly enhance the system SEE and achieve the optimal power allocation and user association strategies.
文摘A series of water disputes and conflicts have gradually emerged between China and some neighboring countries after 2000, influencing China's neighborhood relations. China increasingly realizes the importance and urgency of the water resource governance in the regional cooperation, but under complicated geopolitical context, China's water resource governance must serve several important main functions in its regional cooperation. Overall, water resource governance is the demands of crisis management and conflict prevention, and also is a kind of positive factor that promotes sub-regional cooperation. From the perspective of the current situation, China should take more proactive attitude toward the water resource governance, expand the areas and stakeholders of the water resource governance, and thus promote the formulation of water resource governance strategy.
基金the National Natural Science Foundation of China (60272014)the National High Technology Research and Develop-ment Program of China (2005AA121520)
文摘As to the safety threats faced by sensor networks (SN), nodes limitations of computation, memory and communication, a secure location algorithm (node cooperative secure localization, NCSL) is presented in this paper. The algorithm takes the improvements of SN location information security as its design targets, utilizing nodes' cooperation to build virtual antennae array to communicate and localize, and gains arraying antenna advantage for SN without extra hardware cost, such as reducing multi-path effects, increasing receivers' signal to noise ratio and system capa- bility, reducing transmitting power, and so on. Simulations show that the algorithm based on virtual antennae array has good localization ability with a at high accuracy in direction-of-arrival (DOA) estimation, and makes SN capable to resist common malicious attacks, especially wormhole attack, by using the judgment rules for malicious attacks.
文摘Space is an important part of the Sino-US relationship. It reflects the general direction of bilateral relations, yet has its own development trajectory. As Sino-US relations had their ups and downs in the 1990 s, space cooperation between the two countries was relatively consistent and stable. But as economy and trade became more and more deeply intertwined in the 21 st century, space cooperation lost its momentum. This paper intends to explore the reasons behind this strange development trajectory by analyzing the security, political, legislative and economic factors affecting bilateral space cooperation. It also tries to analyze the prospect of Sino-US space cooperation in President Trump's term.
文摘Nonproliferation cooperation has always been a bright spot in China-US security cooperation for over more than a decade. China and the U.S. should timely adjust the focus of their nonproliferation cooperation on a more equal basis, expanding common interests and exploring new patterns for cooperation so as to create a model for the two countries to join hands in global governance and maintenance of regional order.
文摘With the low cost and low hardware complex considerations,cooperative systems are a tendency in the future communications.This work considers the secure cooperative communications systems.For a practical situation in the system,the scenario includes multiple source stations,multiple relay stations,multiple destination stations,and eavesdroppers.To analyze the optimal relay selection in the system,we begin with the performance analysis for a single source station and a single destination station.By applying two cooperative models,the amplify-andforward(AF) mode and decode-and-forward(DF)mode,the secrecy capacity is derived.Then,we apply the derived results to the considered environment to find the optimal relay assignment.By the way,the relay selection can be obtained by the exhaustive search algorithm.However,there are a lot of steps needed if the number of source stations is large.Hence,applying the characters of the cooperative modes in the relay selection,the pre-selection step is proposed with a mathematical derivation.It could be used for the practical situation without a long-time calculation.
文摘Global climate change-essentially an adverse consequence of global warming, is principally caused by progressive build-up and extensive spread of greenhouse gases (GHGs) across countries, regions or continents because of earth’s rotational movement. The potent sources of GHGs are fossil-fuels and biomass. With the increasing pace of globalization, industrialization and rapid change of life-style the demand and consumption of these feed-stocks to stimulate economic growth is steadily rising-both in the developing and developed economy. In the process, the emissions level is also rising phenomenally;and of late become quite alarming-more in the former than latter case, affecting thereby the environmental quality as also its security concerns globally. This paper highlights the major impacts of global warming and consequential climate change on the environmental quality and overall security aspects-including commercial, strategic and defense angles for the South-Asian region. The paper also discusses some relevant aspects linking the larger question of energy security with environmental security through the approach of sustainable energy development for envisioning a balanced economic development as well as growth perspective for South Asia. The significance of International cooperation in the mitigation and adaptation of climate change impacts with special reference to Asia- Pacific and South Asian region is also discussed at some length in the paper.