Papers by Keyword: Multi-Carrier

Abstract: In order to realize multi-carrier transmission of MPPSK modulation, a method was proposed after analyzing the cause of the internal channel interference (ICI) among multi MPPSK signals. The ICI was eliminated by reducing the modulation order of each MPPSK signal to a certain level and modulating MPPSK signals to different parts of a same symbol cycle. The information rates of single carrier modulation and multi-carrier modulation were compared to illustrate the role of order reduction. The BER performances of single carrier modulation and multi-carrier modulation were also carried out by simulations. Results show that: the proposed method can achieve MPPSK multi-carrier transmission, with higher information rate than that with single carrier modulation and no BER performance loss, which is expected to be an available scheme for improving spectrum efficiency.

Abstract: Carrier transport properties of AlGaN/GaN heterostructures have been analyzed with the quantitative mobility spectrum analysis (QMSA) technique. The nominally-undoped Al0.15Ga0.85N/GaN sample was grown by metal-organic vapor phase epitaxy. Variable-magneticfield Hall measurements were carried out in the temperature range of 4-160 K and magnetic field range of 0-6.6 T. QMSA was applied to the experimental variable-field data to extract the concentrations and mobilities associated with the high-mobility 2DEG and the relatively lowmobility bulk electrons for the temperature range investigated. For temperatures below 100 K the calculated mobility and carrier density values were close to the experimental results. No bulk conduction was observed in this temperature range. At 160 K, QMSA results show that parallel conduction in 3 mm thick GaN layer started to affect the average electron mobility.