Akio Kurobe

The inter-PHY protocol (IPP): A simple coexistence protocol for shared media

The power line (PL) is a shared medium, so that PL devices deployed on the same PL network must share the available capacity. Since there are today several incompatible technologies in the market and no available standard, it is expected that these different technologies will continue to be deployed for some time thus giving rise to the necessity of adopting coexistence mechanisms, i.e. mechanisms allowing non-interoperable devices to efficiently share channel resources. This problem has seldom been addressed in the literature and the goal of this contribution is to fill this gap. A simple coexistence mechanism is here presented and its performances assessed via simulations. A particular version of this algorithm has been proposed to the IEEE P1901 and to the ITU-T SG15/Q4 G.9960 (G.hn) Working Groups.

A study on transmission of low bit-rate coded video over radio links

Reports on a new method to transmit video signals over the digital cordless telephone system. Employing a video coding system H.261, a new coding control method optimized to visual characteristics, and a method developed to prevent broad frame skipping due to burst errors particular to mobile communication systems, are proposed. Though the spatial resolution (quantization-step) and the time resolution (coding frame-rate) are in a trade-off relationship, the coding control system is developed from the view point of visually optimum frame-rate and quantization step size derived from a subjective evaluation experiment. It is also shown that visually undesirable broad frame skipping can be prevented by providing a preframe buffer in the coding system.<<ETX>>