The present invention relates to a NbO2 sintered compact characterized in that the intensity proportion of the X-ray diffraction peak intensity of a plane or plane of Nb2O5 relative to the X-ray diffraction peak intensity of a plane of NbO2 is 1% or less. Platform overhead associated with exchanging information for authentication andor validation on each new connection during mobility is reduced by enabling prior authenticated network access to influence subsequent network access. A symbol estimate may be identified for erasure when a coordinate of the corresponding soft decision is within an erasure area defined by the threshold. The microcontroller IC is connected to the driving circuit and includes a phase-sensing module, a control unit, and a driving signal generator.