Systems and methods for communicating medium access control data without errors. Each receiver separately optimizes the quality of received information by subscribing to at least one error correction layer. The pinion has at least one guide knob, which can be brought into engagement optionally with one of two slide tracks provided in the guide sleeve, wherein the slide tracks are inclined in opposite directions. Controller circuitry is provided to sense signals associated with the control channel and to switch the changeable portion between the first and second modes.