Transmission method and node device implementing said method

An intermediate node device between a first node device and a second node device, said intermediate node device and said first and second node devices belonging to an electrical supply network and said intermediate node device belonging to a network neighbourhood of said first and second node devices, the first node device and said intermediate node being configured for communicating by powerline and by radio frequency, said second node device and said intermediate node device being able to communicate only using a single communication medium, referred to as a first communication medium, from the powerline and the radio frequency, the intermediate node device comprises:

• circuitry configured to cause the intermediate node device to perform:
• receiving a first fragment sent by said first node device either by the powerline or by the radio frequency;
• and
• sending an acknowledgement message to said first node device using a second communication medium selected from the powerline and the radio frequency where the second communication medium is selected based on (1) identifying what type of medium of communication the first communication medium is, and (2) selecting the second communication medium based on the first communication medium used so that the second communication medium is a medium type that is different from said first communication medium;
• transmitting said first fragment to said second node device using said first communication medium;
• and
• transmitting to said second node device fragments of the IP packet following said first fragment using only said second communication medium.