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
An inductorless Ultra-Wide Band （UWB） receiver frontend chip design used in wireless communications for the frequency band of 3.1 - 4.8 GHz is presented. This ho-nodyne receiver mainly consists of a diffexential Low...An inductorless Ultra-Wide Band （UWB） receiver frontend chip design used in wireless communications for the frequency band of 3.1 - 4.8 GHz is presented. This ho-nodyne receiver mainly consists of a diffexential Low Noise Amplifier （LNA） circuit followed by a down-converting mixer. The proposed LNA circuit with a noise canceling resistor is connected to the CMOS device＇s body to reduce the substrate thermal noise. Simulation and measuremnt results show that the chip can reduce the froat-end Noise Figure （NF） about 0.5dB and achieve the Conversion Gain （03） of 19.44-21.57 dB and double-sideband NF less than 7.8 dB. Also, the input third-order interoept point （IIP3） is - 11 dBm, and the input second-order intercept point （IIP2） is 49 dBm. Fabricated in TSMC 0.18 tan technology, this chip occupies only 0. 167 Iron2 and dissipates power 59.2 roW.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.
文摘An inductorless Ultra-Wide Band （UWB） receiver frontend chip design used in wireless communications for the frequency band of 3.1 - 4.8 GHz is presented. This ho-nodyne receiver mainly consists of a diffexential Low Noise Amplifier （LNA） circuit followed by a down-converting mixer. The proposed LNA circuit with a noise canceling resistor is connected to the CMOS device＇s body to reduce the substrate thermal noise. Simulation and measuremnt results show that the chip can reduce the froat-end Noise Figure （NF） about 0.5dB and achieve the Conversion Gain （03） of 19.44-21.57 dB and double-sideband NF less than 7.8 dB. Also, the input third-order interoept point （IIP3） is - 11 dBm, and the input second-order intercept point （IIP2） is 49 dBm. Fabricated in TSMC 0.18 tan technology, this chip occupies only 0. 167 Iron2 and dissipates power 59.2 roW.
