We propose a cross-layer switching method of orthogonal frequency division multiple access (OFDMA) and multiuser multiple input multiple output (MU-MIMO) for the future wireless local area network systems. The proposed method, employed on the medium access control layer, switches between OFDMA and MU-MIMO as the transmission method after processing by using physical layer information such as an overhead of channel state information feedback, station number, and data length in order to improve the transmission efficiency. Simulation results show that the proposed method achieves higher total throughput than conventional OFDMA or MU-MIMO where switching is not performed.

View full abstract

This study focuses on the effect of diode operating temperature on the conducted noise, induced by the reverse recovery current of the diode, of the continuous-current-mode boost DC–DC converter for the Si PiN diode (PiND) and SiC Schottky barrier diode (SBD). The result shows that the SiC SBD exhibits invariant switching behavior and predicts conducted emission level at the operating temperature. The peak reverse recovery current of the Si PiND increases at high operating temperatures. This study indicates that the temperature can affect the noise spectrum distribution for the variation of reverse recovery time and ringing oscillation.

View full abstract

Network protection is a key feature of communications systems to ensure minimal packet loss when failure occurs in the data path. Segment protection is typically used to reroute data around a failed link, using secondary backup paths. We propose a novel solution to this problem, proposing an Independent Transient Plane (ITP) design that reduces the complexity of the path configuration process and the usage of resources in the routing elements, compared to current solutions. This work complements our previous studies, by reporting the results of an international testbed implementation over a pan-European network, showing protection times below 20 ms.

View full abstract

In this paper, we present a very simple multi-band technique for a wire inverted-F antenna designed for cellular application inside handset terminals, using multiple branch elements, single feeding port and only one shorting strip to simultaneously obtain good impedance matching at many different frequencies. The results in our investigation show that, the proposed technique is extremely straightforward, and can be simply applied to multi-band design of inverted-F antenna, so that it is possible to control easily and independently both the position and the number of all resonant frequencies.

View full abstract