A method of detecting web pages belonging to at least one similarity class from a plurality of web pages includes determining clusters of the plurality of web pages based on characteristics of the content of the web pages. For each of time intervals, an objective function which includes an estimation error term or at least one transition error term is determined. Substantially no catalyst supporting layer is formed in a non-catalyst-supporting-layer area covering about 10% of the overall length on the gas outlet side. The method also includes mapping one or more control codewords to the final number of control vector symbols and transmitting vector symbols carrying the one or more user data codewords and the one or more control codewords over the plurality of transmission layers during the subframe.