Method for operating a node in a network and node device

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.

2. The method of claim 1 , wherein step (c) is carried out if the received message includes an indication of reception opportunity during which the resource restricted device is able to receive.

3. The method of claim 1 , wherein the buffer includes a multiple entry queue, wherein step (a) further comprises also placing an ACK message in the multiple entry queue if one of the entries is available.

4. The method of claim 1 , wherein the transmission priority level of the ACK message is set to the minimum transmission priority level.

5. The method of claim 1 , wherein the buffer includes a multiple entry queue, and wherein step (c) comprises finding the message having the highest transmission priority level in the multiple entry queue of the buffer, and transmitting said message.

6. The method of claim 1 , wherein step (c) is carried out regardless of whether the payload of the received message was decoded successfully.

7. The method of claim 1 , wherein the buffer includes a single entry queue, wherein, when the single entry queue contains the buffered message, step (c) comprises transmitting the buffered message only if the payload of the received message was decoded successfully.

8. The method of claim 1 , wherein the buffer includes a multiple entry queue, and wherein step (c) comprises transmitting a message having the highest transmission priority level if the decoding of a payload of the received message was successful and transmitting the ACK message if only the decoding of a header of the received message was successful.

9. The method of claim 1 , wherein step (c) is carried out so that the ACK message or the buffered message is transmitted during a reception window of the resource restricted device, said reception window starting after expiry of a time period starting when the transmission of the message from the resource restricted device is complete.

10. A node having a communication unit for communicating in a network with at least one resource restricted device, the node comprising

a buffer including a queue of at least one message to be transmitted to the resource restricted device,

a receiver configured to detect a received message from the resource restricted device,

a processor configured to, prior to the detection of the received message, control generation of an ACK message and place said ACK message in the buffer when said buffer does not contain a buffered message to be transmitted to the resource restricted device,

a transmitter configured to transmit the ACK message or the buffered message to the resource restricted device upon detection of the received message;

wherein the processor is arranged to also generate an ACK message and place said ACK message in the buffer when said buffer does not contain a buffered message to be transmitted to the resource restricted device after transmission of the ACK message or the buffered message, wherein the buffer always maintain at least one message ready to be sent.

11. A network comprising a first node as set forth in claim 10 and a resource restricted device.

12. The network of claim 11 , further comprising a plurality of second nodes in the vicinity of the resource restricted device, wherein the first node is configured to act as a master node for the resource restricted device, and wherein at least one of the first node and of the second nodes is adapted to trigger an election method for electing a new master node among the plurality second nodes instead of the first node upon detection of a failure of the first node.

13. A computer program product comprising a non-transitory computer readable medium encoded with instructions when being executed by a controller causing the controller to perform the method of claim 1 .

14. A method for operating a node in a network comprising a resource restricted device, the method comprising the steps of (a) placing a configuration signal indicative of a transmission property in a buffer of the node;

(b) after step (a), detecting a received message transmitted by the resource restricted device;

(c) transmitting the configuration signal to the resource restricted device after detection of the received message,

the method further comprising repeating steps (a) to (c) until a confirmation that the resource restricted device uses said transmission property is detected;

wherein the transmission property is at least one of: an operational transmission channel, security key, security key type, security level, frame counter value, network identifier, device identifier, reporting interval, and command type.