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
Based on the analysis of printed elliptical slot (PES) UWB antenna,a dual-banded PES antenna is designed for WLAN and UWB bands at 2.4 GHz.The design cooperates two important wireless commutation system antennas into ...Based on the analysis of printed elliptical slot (PES) UWB antenna,a dual-banded PES antenna is designed for WLAN and UWB bands at 2.4 GHz.The design cooperates two important wireless commutation system antennas into one printed antenna.In the design,a circular slot structure is presented,which is suitable for the band ejection.Characteristics of the designed antenna are analyzed and key parameters,such as S11,S21 and VSWR are measured.E-field distribution of the surface is simulated and analyzed.展开更多
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Sponsored by the National Basic Research Program of China(Grant No.2007CB3106XX) and Qualcomm
文摘Based on the analysis of printed elliptical slot (PES) UWB antenna,a dual-banded PES antenna is designed for WLAN and UWB bands at 2.4 GHz.The design cooperates two important wireless commutation system antennas into one printed antenna.In the design,a circular slot structure is presented,which is suitable for the band ejection.Characteristics of the designed antenna are analyzed and key parameters,such as S11,S21 and VSWR are measured.E-field distribution of the surface is simulated and analyzed.
