Electromagnetic interference (EMI) noise in time and frequency mixed domains is analyzed to understand the influence of noise source behavior on the conducted emissions in boost converters. The switching characteristics of a sillicon PiN diode and a sillicon carbide Schottky barrier diode in a boost converter are compared and evaluated as EMI noise sources, and the influence of diode switching operation on the generation and attenuation of conducted emissions are discussed on the basis of spectrogram analysis.
It has been conventionally assumed that a single leaky coaxial (LCX) cable only is utilized as one antenna to configure a multiple-input multiple-output (MIMO) system. In this letter, we show one single LCX cable can be used as two antennas to configure a MIMO system owing to the designed intersection angle between the different radiation directivities of both input signals. The measurement results of 2 × 2 LCX-MIMO channel quality confirm that our proposed LCX-MIMO can realize a promising channel condition over 5 GHz frequency band. It also points out that the intersection angle between radiation directivities of LCX cable needs to be considered carefully to reduce the channel degradation at the both edge portions of the LCX cable.
A path loss model based on the Rec. ITU-R P.1411 model, which can cover the frequency range from microwave to millimeter-wave bands, is presented. The path loss characteristics are analyzed on the basis of measurement results obtained using the 2 to 37 GHz band in street microcell environments. It is clarified that the characteristics depend on distance from transmitter to intersection and frequency dependency. By taking these dependencies into account, the proposed model can decrease the root mean square error of prediction results to within about 5 dB in the 2 to 37 GHz band.
Multi-user multiple-input and multiple-output (MU-MIMO) transmission has been extensively studied to enhance the spectral efficiency of wireless communication systems. The performance of MU-MIMO suffers due to the presence of residual multi-user interference. Linear interference cancellation can offer excellent performance when a large number of antennas are available. This, however, is impractical in a mobile station. In this paper, we apply a collaborative interference cancellation scheme to a precoded MU-MIMO system. In order to effect collaboration, we implement received signal sharing among mobile stations using wireless local area network connections. We carried out transmission experiments in an indoor environment to test the performance of our precoded MU-MIMO system with collaborative interference cancellation.
We propose a wideband and dual polarized open-ended waveguide for planar array antennas. The proposal forms most of the antenna structures including waveguide and feeding networks in the dielectric substrates. This yields two advantages. First, it reduces the antenna dimensions because the waveguide is filled with dielectric; this yields 30% bandwidth and short element spacing without grating lobes. Second, it simplifies the machining process, especially for the case of large scale arrays consisting of several hundred elements. We design antenna elements and a four-element array, and then fabricate the four-element array using a 7-layer board of PTFE. Though the calculated and measured reflection characteristics diverge slightly, the radiation patterns well match.
This letter proposes RSSI (Received Signal Strength Indicator) based 60 GHz WLAN discovery for multiband WLAN (Wireless LAN), which uses both 2.4/5 GHz band and 60 GHz band to achieve high transmission speed, sufficient reliability and power-saving of a multiband WLAN device. The proposed 60 GHz WLAN discovery detects 60 GHz WLAN coverage by using RSSI of 2.4/5 GHz WLAN signals. Space/time diversity is employed to improve the false detection probability of 60 GHz WLAN discovery. Ray-tracing simulation results confirm that 60 GHz WLAN discovery is feasible and space/time diversity is effective to improve the reliability of 60 GHz WLAN discovery.