1. A method for operating a node in a network, said network further comprising a resource restricted device, the method comprising the steps of(a) placing an ACK message in a buffer of the node, when said buffer does not contain a buffered message to be transmitted to the resource restricted device;
(b) after step (a), detecting a received message transmitted by the resource restricted device;
(c) transmitting the ACK message or the buffered message to the resource restricted device after detection of the received message;
the method further comprising repeating steps (a) to (c) after the ACK message or the buffered message has been transmitted, wherein the buffer always contains a message ready to be sent.