Embodiments of the invention provide multiple cyclic prefix lengths for either both the data-payload and frame control header or only the data payload. Each stand leg is bent by the same angle at a distance from the axis, with a freely projecting section of one leg being provided with a threaded bolt freely protruding transversely thereto. The moveable features while in one of the actuated state and non-actuated state are positioned, sized and shaped to fit within the loops.