With the rapid development of green communications,energy consumption issue plays more and more important role in cooperative communication strategies and communication systems.Based on cooperative transmission model,...With the rapid development of green communications,energy consumption issue plays more and more important role in cooperative communication strategies and communication systems.Based on cooperative transmission model,a cooperative user selection scheme is proposed in consideration of both energy efficiency and interference factor.With the proposed scheme,the selected cooperative user consumes less energy and receives less interference.Furthermore,the main factor is analyzed to affect system performance,including signal-to-noise ratio(SNR)of source user and cooperative user,distance between source user and cooperative user or base station(BS),and fading factor in the transmission model.Through the proposed scheme,energy consumption and influence of interference are jointly taken into account during the cooperative user selection process.Besides,bit error rate(BER)in proposed scheme is also superior to existing schemes.Simulation results are presented to show the performance improvement of the proposed scheme.展开更多
In cognitive relay networks, the transmission of Secondary Users （SUs） suffers from the activity of Primary Users （PUs） and wireless channel fading. Therefore, how to achieve robust transmission for cognitive rela...In cognitive relay networks, the transmission of Secondary Users （SUs） suffers from the activity of Primary Users （PUs） and wireless channel fading. Therefore, how to achieve robust transmission for cognitive relay networks is a challenging task. In this paper, we propose a relaying transmission scheme which exploits robust beamforming at the physical layer and rateless codes at higher layers. We derive the optirml beamforng weight vector and analyze the perforrmnce of the pro- posed scheme when the channel estirmtion is not accurate between two SU nodes. We also study how the anaount of channel information between SU and PU impacts the system perforroance. Sinlation results validate our theoretical analysis and demonstrate that the proposed scheme can signifi- cantly enhance the system throughput.展开更多
Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, th...Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, the University of Natural Resources and Applied Life Sciences in Vienna, Austria, analysed impacts of Flexible Transport Services focusing on Demand Responsive Public Transport （DRT）. This includes the analysis of site characteristics, the existing mobility demand, accessibility, area needs, current environmental impact, operational, financial and organisational constraints; designing of the service and definition of the supporting organisational measures required. Examples of realised services in Alpine areas in Austria confirm the effects on people＇s daily mobility and all its consequences towards society and environment. Main effects are the decrease of public funding needs and ensuring a basic transport supply even in rural areas. Additionally, there is a strong component of social inclusion in this service, increasing the quality of life capable to contribute to the deceleration of the out migration. As secondary effects, economic effects and environmental effects can be observed. The potential of these services are not fully utilised today and can be achieved through further extensions of service area as well as technical developments.展开更多
China＇s cormaaunications industry is an important part of the electronic information industry, and plays a significant role in the national informatization process. In 2006, China issued its National Plans for Medium...China＇s cormaaunications industry is an important part of the electronic information industry, and plays a significant role in the national informatization process. In 2006, China issued its National Plans for Medium and Long-term Development of Science and Technology （2006-2020） （NPMLDST）. Since 2006, there has been a rapid increase in the number of citations of China＇s interna- tional papers in the field of communications. In accordance with the goals listed in the NPMLDST, China needs to over- take several competitors by 2020 to be among the top five countries in the field of natural science field. By comparing two Essential Science Indicators （ESI） （i.e., the total number of citations and the number of citations per paper） for China and other countries, China＇s annual growth rate is found to exceed that of other influential countries in the field of sci- ence and technology, and exhibits evident growth-type characteristics. Besides, our study also shows that the short- age of high-quality academic papers in China is the main obstacle to improving the impact of China＇s academic publications.展开更多
基金Supported by the National Natural Science Foundation of China(No.61372089,61571021)Beijing Natural Science Foundation(No.4132019)
文摘With the rapid development of green communications,energy consumption issue plays more and more important role in cooperative communication strategies and communication systems.Based on cooperative transmission model,a cooperative user selection scheme is proposed in consideration of both energy efficiency and interference factor.With the proposed scheme,the selected cooperative user consumes less energy and receives less interference.Furthermore,the main factor is analyzed to affect system performance,including signal-to-noise ratio(SNR)of source user and cooperative user,distance between source user and cooperative user or base station(BS),and fading factor in the transmission model.Through the proposed scheme,energy consumption and influence of interference are jointly taken into account during the cooperative user selection process.Besides,bit error rate(BER)in proposed scheme is also superior to existing schemes.Simulation results are presented to show the performance improvement of the proposed scheme.
基金Acknowledgements The authors would like to thank the editor and anonymous reviewers for their detailed reviews and constructive comments, which have helped to greatly improve the quality of this paper. This work was supported by the National Natural Science Foundation of China under Grants No. 60832008, No. 60902001 Beijing Natural Science Foundation Program and Scientific Research Key Program of Beijing Municipal Commission of Education under Grant No. KZ201010009009 the Tsinghua National Laboratory for Infomation Science and Technology （TNList） Cross-discipline Foundation.
文摘In cognitive relay networks, the transmission of Secondary Users （SUs） suffers from the activity of Primary Users （PUs） and wireless channel fading. Therefore, how to achieve robust transmission for cognitive relay networks is a challenging task. In this paper, we propose a relaying transmission scheme which exploits robust beamforming at the physical layer and rateless codes at higher layers. We derive the optirml beamforng weight vector and analyze the perforrmnce of the pro- posed scheme when the channel estirmtion is not accurate between two SU nodes. We also study how the anaount of channel information between SU and PU impacts the system perforroance. Sinlation results validate our theoretical analysis and demonstrate that the proposed scheme can signifi- cantly enhance the system throughput.
文摘Embedded in an INTERREG IVc project called Flexible Transport Services （FTS） and Information and Communication Technology （ICT） platform for Eco-Mobility in urban and rural European areas （acronym： FLIPPER）, the University of Natural Resources and Applied Life Sciences in Vienna, Austria, analysed impacts of Flexible Transport Services focusing on Demand Responsive Public Transport （DRT）. This includes the analysis of site characteristics, the existing mobility demand, accessibility, area needs, current environmental impact, operational, financial and organisational constraints; designing of the service and definition of the supporting organisational measures required. Examples of realised services in Alpine areas in Austria confirm the effects on people＇s daily mobility and all its consequences towards society and environment. Main effects are the decrease of public funding needs and ensuring a basic transport supply even in rural areas. Additionally, there is a strong component of social inclusion in this service, increasing the quality of life capable to contribute to the deceleration of the out migration. As secondary effects, economic effects and environmental effects can be observed. The potential of these services are not fully utilised today and can be achieved through further extensions of service area as well as technical developments.
基金supported by National High-tech R&D Program of China (863 Program) under Grant No.2011AA01A206
文摘China＇s cormaaunications industry is an important part of the electronic information industry, and plays a significant role in the national informatization process. In 2006, China issued its National Plans for Medium and Long-term Development of Science and Technology （2006-2020） （NPMLDST）. Since 2006, there has been a rapid increase in the number of citations of China＇s interna- tional papers in the field of communications. In accordance with the goals listed in the NPMLDST, China needs to over- take several competitors by 2020 to be among the top five countries in the field of natural science field. By comparing two Essential Science Indicators （ESI） （i.e., the total number of citations and the number of citations per paper） for China and other countries, China＇s annual growth rate is found to exceed that of other influential countries in the field of sci- ence and technology, and exhibits evident growth-type characteristics. Besides, our study also shows that the short- age of high-quality academic papers in China is the main obstacle to improving the impact of China＇s academic publications.
