Cognitive radio and cooperative communication can greatly improve the spectrum efficiency in wireless communications.We study a cognitive radio network where two secondary source terminals exchange their information w...Cognitive radio and cooperative communication can greatly improve the spectrum efficiency in wireless communications.We study a cognitive radio network where two secondary source terminals exchange their information with the assistance of a relay node under interference power constraints.In order to enhance the transmit rate and maintain fairness between two source terminals,a practical 2-phase analog network coding protocol is adopted and its optimal power allocation algorithm is proposed.Numerical results verify the superiority of the proposed algorithm over the conventional direct transmission protocol and 4-phase amplify-and-forward relay protocol.展开更多
We study the transmission capacities of two coexisting spread-spectrum wireless networks (a primary network vs. a secondary network) that operate in the same geographic region and share the same spectrum. We defi ne t...We study the transmission capacities of two coexisting spread-spectrum wireless networks (a primary network vs. a secondary network) that operate in the same geographic region and share the same spectrum. We defi ne transmission capacity as the product among the density of transmissions, the transmission rate, and the successful transmission probability. The primary (PR) network has a higher priority to access the spectrum without particular considerations for the secondary (SR) network, while the SR network limits its interference to the PR network by carefully controlling the density ofits transmitters. Considering two types of spread-spectrum transmission schemes (FH-CDMA and DS-CDMA) and the channel inversion power control mechanism, we quantify the transmission capacities for these two networks based on asymptotic analysis. Our results show that if the PR network permits a small increase ofits outage probability, the sum transmission capacities of the two networks (i.e., the overall spectrumefficiency per unit area) will be boosted significantly over that of a single network.展开更多
We carry out a comprehensive analysis of a range of wireless network efficiency considerations. Firstly, we explore the properties and the implications of the power-versus bandwidth-efficiency criteria. Secondly, we p...We carry out a comprehensive analysis of a range of wireless network efficiency considerations. Firstly, we explore the properties and the implications of the power-versus bandwidth-efficiency criteria. Secondly, we perform a detailed top-down analysis of a typical commercial wireless network, which emphasizes the inherent differences between the aforementioned two efficiency metrics, while demonstrating that the appropriate choice of the network optimization criterion can have a profound effect on the overall network performance. Finally, we address the issue of resource management and its impact on the definition of the overall system efficiency. Our results suggest that no substantial area spectral efficiency gains beyond those exhibited by the 2G cellular technol- ogy may be economically achieved, and hence, no significant economic gains may be realized by simply increasing the bps/Hz bandwidth efficiency. In contrast, manifold utility and throughput gains as well as substantial Quality of Service enhancements may be attained by the appropriate combination of improved power efficiency, bandwidth expansion as well as the appropriate evolution of the networking paradigm.展开更多
The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireles...The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN and cellular network is introduced, adding several models to the original systems. Furthermore, new radio access schemes for different types of Mobile Terminals (MTs) are proposed. Particularly, Spectrum Sharing (SS) between WLAN and cellular networks is discussed. Here, a new radio access scheme and channel assignment mechanism with code-division duplex (CDD) and Frequency Hopping (FH) technologies are raised, for the purpose of avoiding interference between heterogeneous networks. Finally, the performance of the above radio access schemes is analyzed, and simulation results proved its validation.展开更多
With the fast development of highspeed railways,a call for fulfilling the notion of communication at "anytime,anywhere" for high-speed train passengers in the Train Operating Control System is on the way.In ...With the fast development of highspeed railways,a call for fulfilling the notion of communication at "anytime,anywhere" for high-speed train passengers in the Train Operating Control System is on the way.In order to make a realization of that,new railway wireless communication networks are needed.The most promising one is the Long Term Evolution for Railway which will provide broadband access,fast handover,and reliable communication for high mobility users.However,with the increase of speed,the system is subjected to high bit error rate,Doppler frequency shift and handover failure just like other system does.This paper is trying to solve these problems by employing MIMO technique.Specifically,the goal is to provide higher data rate,higher reliability,less delay,and other relative quality of services for passengers.MIMO performance analysis,resource allocation,and access control for handover and various services in a two-hop model are proposed in this paper.Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.展开更多
The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communic...The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communication of primary system operated in the same frequency band. In this work, the problem of the capacity analyses of cognitive UWB networks is investigated. Different from the conventional cognitive spectrum sharing model which can only utilize the idle spectrum hole, the cognitive UWB system can operate adaptively based on spectrum sensing results. Taking into account several factors such as the transmission power constraint of UWB, the interference constraint of the receivers in primary systems, the secondary UWB network capacity problem is modeled as a convex optimization problem over the transmission power. The optimal power allocation strategy and algorithm are derived based on this optimization problem. Two cases (Perfect Spectrum Sensing and Imperfect Spectrum Sensing) are studied in the paper. Numerical simulation results show that the proposed adaptive power allocationscheme improves the ergodic and outage capacity under both transmission power and interference constraints compared with constant transmission power scheme.展开更多
Equipped with millions of sensors and smart meters in smart gird,a reliable and resilient wireless communication technology is badly needed.Mobile networks are among the major energy communication networks which contr...Equipped with millions of sensors and smart meters in smart gird,a reliable and resilient wireless communication technology is badly needed.Mobile networks are among the major energy communication networks which contribute to global energy consumption increase rapidly.As one of core technologies of smart grid employing mobile networks,Demand Response(DR) helps improving efficiency,reliability and security for electric power grid infrastructure.Security of DR events is one of the most important issues in DR.However,the security requirements of different DR events are dynamic for variousactual demands.To address this,an event-oriented dynamic security service mechanism is proposed for DR.Three kinds of security services including security access service,security communication service and security analysis service for DR event are composited dynamically by the fine-grained sub services.An experiment prototype of the network of State Grid Corporation of China(SGCC) is established.Experiment and evaluations shows the feasibility and effectiveness of the proposed scheme in smart grid employing mobile network.展开更多
基金Acknowledgements The work was supported by National Natural Science Foundation of China （Grant No.60972008）. The corresponding author is Jiang Wei.
文摘Cognitive radio and cooperative communication can greatly improve the spectrum efficiency in wireless communications.We study a cognitive radio network where two secondary source terminals exchange their information with the assistance of a relay node under interference power constraints.In order to enhance the transmit rate and maintain fairness between two source terminals,a practical 2-phase analog network coding protocol is adopted and its optimal power allocation algorithm is proposed.Numerical results verify the superiority of the proposed algorithm over the conventional direct transmission protocol and 4-phase amplify-and-forward relay protocol.
基金supported in part by the China 863 Program grants 2007AA10Z235, 2007AA01Z179, 2006BAJ09B05, 2008BADA0B05the NSFC grants 60972073, 60871042, 60872049, and 60971082+1 种基金the China National Great Science Specifi c Project grant 2009ZX03003-011the China 973 Program grant 2009CB320407
文摘We study the transmission capacities of two coexisting spread-spectrum wireless networks (a primary network vs. a secondary network) that operate in the same geographic region and share the same spectrum. We defi ne transmission capacity as the product among the density of transmissions, the transmission rate, and the successful transmission probability. The primary (PR) network has a higher priority to access the spectrum without particular considerations for the secondary (SR) network, while the SR network limits its interference to the PR network by carefully controlling the density ofits transmitters. Considering two types of spread-spectrum transmission schemes (FH-CDMA and DS-CDMA) and the channel inversion power control mechanism, we quantify the transmission capacities for these two networks based on asymptotic analysis. Our results show that if the PR network permits a small increase ofits outage probability, the sum transmission capacities of the two networks (i.e., the overall spectrumefficiency per unit area) will be boosted significantly over that of a single network.
基金part of the Delivery Efficiency Core 4 Research Programme of the Virtual Centre of Excellence in Mobile & Personal Communications, Mobile VCE
文摘We carry out a comprehensive analysis of a range of wireless network efficiency considerations. Firstly, we explore the properties and the implications of the power-versus bandwidth-efficiency criteria. Secondly, we perform a detailed top-down analysis of a typical commercial wireless network, which emphasizes the inherent differences between the aforementioned two efficiency metrics, while demonstrating that the appropriate choice of the network optimization criterion can have a profound effect on the overall network performance. Finally, we address the issue of resource management and its impact on the definition of the overall system efficiency. Our results suggest that no substantial area spectral efficiency gains beyond those exhibited by the 2G cellular technol- ogy may be economically achieved, and hence, no significant economic gains may be realized by simply increasing the bps/Hz bandwidth efficiency. In contrast, manifold utility and throughput gains as well as substantial Quality of Service enhancements may be attained by the appropriate combination of improved power efficiency, bandwidth expansion as well as the appropriate evolution of the networking paradigm.
文摘The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN and cellular network is introduced, adding several models to the original systems. Furthermore, new radio access schemes for different types of Mobile Terminals (MTs) are proposed. Particularly, Spectrum Sharing (SS) between WLAN and cellular networks is discussed. Here, a new radio access scheme and channel assignment mechanism with code-division duplex (CDD) and Frequency Hopping (FH) technologies are raised, for the purpose of avoiding interference between heterogeneous networks. Finally, the performance of the above radio access schemes is analyzed, and simulation results proved its validation.
基金the support from NSFC under Grant 61222105the 863 Plan of China under Grant 2014AA01A706+3 种基金the project of State Key Lab under Grant RCS2012ZT013the Key Project of Chinese Ministry of Education under Grant 313006the Key Project for Railway Ministry of China under Grant 2012X008-Athe project of State Key Lab under Grant No. RCS2011ZZ002
文摘With the fast development of highspeed railways,a call for fulfilling the notion of communication at "anytime,anywhere" for high-speed train passengers in the Train Operating Control System is on the way.In order to make a realization of that,new railway wireless communication networks are needed.The most promising one is the Long Term Evolution for Railway which will provide broadband access,fast handover,and reliable communication for high mobility users.However,with the increase of speed,the system is subjected to high bit error rate,Doppler frequency shift and handover failure just like other system does.This paper is trying to solve these problems by employing MIMO technique.Specifically,the goal is to provide higher data rate,higher reliability,less delay,and other relative quality of services for passengers.MIMO performance analysis,resource allocation,and access control for handover and various services in a two-hop model are proposed in this paper.Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.
基金supported by following projects:NSFC (No. 60432040, 60972079)Beijing Natural Science Foundation (No. 4052021)+1 种基金The Research Fund for the Doctoral Program of Higher Education(No.20060013008, 200700130293)UWB-ITRC Inha University, Korea,and iCHIP Project financed by Italian Ministry of Foreign Affairs,And it is partly supported by Project iCHIP financed by Italian Ministry of Foreign Affairs
文摘The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communication of primary system operated in the same frequency band. In this work, the problem of the capacity analyses of cognitive UWB networks is investigated. Different from the conventional cognitive spectrum sharing model which can only utilize the idle spectrum hole, the cognitive UWB system can operate adaptively based on spectrum sensing results. Taking into account several factors such as the transmission power constraint of UWB, the interference constraint of the receivers in primary systems, the secondary UWB network capacity problem is modeled as a convex optimization problem over the transmission power. The optimal power allocation strategy and algorithm are derived based on this optimization problem. Two cases (Perfect Spectrum Sensing and Imperfect Spectrum Sensing) are studied in the paper. Numerical simulation results show that the proposed adaptive power allocationscheme improves the ergodic and outage capacity under both transmission power and interference constraints compared with constant transmission power scheme.
基金supported by National Natural Science Foundation of China(Grant No. 61401273 and 61431008)Doctoral Scientific Fund Project of the Ministry of Education of China(No.20130073130006)JSPS KAKENHI Grant Number 15K15976,26730056,JSPS A3 Foresight Program
文摘Equipped with millions of sensors and smart meters in smart gird,a reliable and resilient wireless communication technology is badly needed.Mobile networks are among the major energy communication networks which contribute to global energy consumption increase rapidly.As one of core technologies of smart grid employing mobile networks,Demand Response(DR) helps improving efficiency,reliability and security for electric power grid infrastructure.Security of DR events is one of the most important issues in DR.However,the security requirements of different DR events are dynamic for variousactual demands.To address this,an event-oriented dynamic security service mechanism is proposed for DR.Three kinds of security services including security access service,security communication service and security analysis service for DR event are composited dynamically by the fine-grained sub services.An experiment prototype of the network of State Grid Corporation of China(SGCC) is established.Experiment and evaluations shows the feasibility and effectiveness of the proposed scheme in smart grid employing mobile network.
