Method implemented in a pilotless mobile device system comprising a control station and at least one pilotless mobile device, the control station communicating with each pilotless mobile device using a medium-access technique of the time division multiple access type in which each communication takes place in frames, the method being characterised in that: each frame is divided into a plurality of timeslots, each timeslot being divided into a plurality of burst intervals, each burst interval being divided into a plurality of periods making it possible to transmit data in the form of data packets, each data packet being modulated by a predefined modulation before transmission thereof, a first period in the plurality of periods making it possible to transmit a preamble enabling a receiver of said preamble to make a channel estimation in order to perform frequency, phase and timing synchronisations and reception signal equalisations, said preamble being used to identify the uplink communications from the downlink communications and a second period making it possible to transmit a burst; and in that the method comprises: using, in each uplink communication from the control station to a pilotless mobile device (3A, 3B), a preamble, referred to as the uplink preamble, orthogonal to the preamble known as the downlink preamble used in each downlink communication from a pilotless mobile device (3A, 3B) to the control station; and, when a modulated data packet is received, determining whether said packet has been transmitted in the context of an uplink or downlink communication according to a result of a convolution between said packet with a reference preamble modulated according to the predefined modulation, said reference preamble corresponding to the uplink preamble or to the downlink preamble. each frame is divided into a plurality of timeslots, each timeslot being divided into a plurality of burst intervals, each burst interval being divided into a plurality of periods making it possible to transmit data in the form of data packets, each data packet being modulated by a predefined modulation before transmission thereof, a first period in the plurality of periods making it possible to transmit a preamble enabling a receiver of said preamble to make a channel estimation in order to perform frequency, phase and timing synchronisations and reception signal equalisations, said preamble being used to identify the uplink communications from the downlink communications and a second period making it possible to transmit a burst; and in that the method comprises: using, in each uplink communication from the control station to a pilotless mobile device (3A, 3B), a preamble, referred to as the uplink preamble, orthogonal to the preamble known as the downlink preamble used in each downlink communication from a pilotless mobile device (3A, 3B) to the control station; and, when a modulated data packet is received, determining whether said packet has been transmitted in the context of an uplink or downlink communication according to a result of a convolution between said packet with a reference preamble modulated according to the predefined modulation, said reference preamble corresponding to the uplink preamble or to the downlink preamble. using, in each uplink communication from the control station to a pilotless mobile device (3A, 3B), a preamble, referred to as the uplink preamble, orthogonal to the preamble known as the downlink preamble used in each downlink communication from a pilotless mobile device (3A, 3B) to the control station; and, when a modulated data packet is received, determining whether said packet has been transmitted in the context of an uplink or downlink communication according to a result of a convolution between said packet with a reference preamble modulated according to the predefined modulation, said reference preamble corresponding to the uplink preamble or to the downlink preamble.