A 10 MHz channelized orthogonal frequency division multiplexing transmitter is provided that communicates using a modified OFDM packet structure with a half-rate oscillator having standard accuracy. The invention is also directed to pharmaceutical compositions and the use of such compounds in the manufacture of medicaments, as well as to the use of such compounds for the prevention and treatment of such diseases in which mGluR4 is involved. Logic may determine a clear-to-send frame comprising a duration value indicative of a duration of a data transmission. An input of a third inverter is coupled to an input of the first inverter.