A method of registering a mobile node on a home agent in a mobile IP environment and a mobile IP network system using the same are provided. The invention also covers the resistive layer obtained and a soundproof wall using such a layer. In such a device, a first beamforming processing element is used to form multiple beams for each array output along a given row. The process chamber comprises a top closed barrier wall forming the roof of the process chamber, wherein the inlet of the solid material into the process chamber is arranged to the lower part of the wall of the process chamber and the outlet of the solid material out of the process chamber is arranged to the upper part of the wall of the process chamber. The outside surface of the body of an end cap, although arranged in large part to engage the tube, has provided therein a circumferential line of blind recesses designed to minimize the amount of polyurethane used for the end cap while still allowing for the provision of load bearing column of polyurethane.