A process and apparatus for removing elements is described herein. 5 to 15 mol % of structural units which are derived from olefinically unsaturated compounds which have at least one free hydroxyl group, and B2) from 85 to 99. The method for transmitting an extended preamble includes generating an extended preamble and transmitting the extended preamble during a receive or idle mode for maintaining visibility support and for better synchronization performance.