METHOD OF OPERATING A LINEAR NETWORK

1 . A method of operating an arrangement of a plurality of network nodes arranged in a linear configuration, each of which network nodes being configured to directly communicate with n neighbouring network nodes located in either direction of the linear arrangement of network nodes, and in which no network node can directly communicate with each one of the network nodes, wherein the method comprises:

determining and assigning an unambiguous and individual rank to each one of the plurality of network nodes, the rank of each network node having a major rank, and at least one network node having a minor rank, wherein the ranks are orderly increasing from one end of the linear arrangement of network nodes to the other end, and wherein each rank of a network node indicates a position of the respective network node within the linear arrangement of network nodes,

configuring the plurality of network nodes to coordinated toggling between a first and a second mode of operation, a power consumption of the network nodes in the first mode of operation being lower than in the second mode of operation, and

transmitting messages, using a non-synchronised or asynchronous, zero-signalling, stateless multipath and multi-hop message routing protocol, between the network nodes of the linear arrangement of network nodes via those network nodes that are in the second mode of operation.

2 . The method of claim 1 , wherein determining and assigning an unambiguous individual rank to each one of a plurality of network nodes comprises the steps of:

a first network node, located at a first end of the linear arrangement of network nodes, assuming a first major rank, and broadcasting a bootstrap message to those network nodes of the linear arrangement of network nodes that are within direct communication range, announcing its assumed major rank,

each one of up to n neighbouring nodes to either side of a transmitting network node receiving, at some point in time, a first bootstrap message announcing a major rank, assuming, in response to the first received bootstrap message, a major rank that is incremented by 1 over the major rank received in the first bootstrap message, and broadcasting a bootstrap message of its own, announcing its respective assumed major rank, wherein each network node may receive up to 2*n−1 further bootstrap messages, of which it will store the major ranks transmitted therein,

each network node, after having received bootstrap messages from at least n neighbouring network nodes, and/or upon a predetermined timeout period, which was started in response to receiving the first bootstrap message having expired, computing its minor rank from the received and stored major ranks.

3 . The method of claim 2 , wherein each node waits for a backoff time randomly selected from a backoff time interval before broadcasting its own bootstrap message.

4 . The method of claim 3 , further comprising increasing the lower limit of the backoff time interval with increasing major rank, while keeping the backoff time interval length constant or also increasing the backoff time interval.

5 . The method of claim 2 , further comprising each network node repeating broadcasting its own bootstrap message for a predetermined number of times, wherein any repetition occurs only after a bootstrap time period has expired.

6 . The method of claim 5 , further comprising:

the network node that has received only bootstrap messages announcing a lower major rank than its own assumed major rank, and after the bootstrap time period T bi having expired, broadcasting a bootstrap complete message into the linear arrangement of network nodes, and

all network nodes rebroadcasting the bootstrap complete message.

7 . The method of claim 6 , wherein the network node that broadcast the bootstrap complete message repeats broadcasting the bootstrap complete message, if it did not receive any further message, preferably a duty cycle message, within a predetermined time period after initially broadcasting the bootstrap complete message.

8 . A method of transmitting messages between nodes arranged in a ranked linear arrangement of network nodes that are configured to directly communicate with two or more neighbouring nodes in either direction of the ranked linear arrangement of network nodes, but wherein no network node can directly communicate with each one of the network nodes, the method comprising:

broadcasting, by a source node having a first rank R_r(s1), a first message, the first message including the rank (R_r(s1)) of the source node and the rank (R_r(d1)) of a first destination node,

wherein the method further comprises:

if the rank of the first destination node (R_r(d1)) is higher by two or more than that of the source node (R_r(s1)):

rebroadcasting, by all intermediate nodes whose rank (R_r(i)) is higher than that of the source node (R_r(s1)), and in accordance with their ascending ranks (R_r(i)), the first message, beginning with the intermediate node whose rank (R_r(i1)) is higher by one than that of the source node (R_r(s1)), or

if the rank of the first destination node (R_r(d1)) is lower by two or more than that of the source node (R_r(s1)):

rebroadcasting, by all intermediate nodes whose rank (R_r(i)) is lower than that of the source node (R_r(s1)), and in accordance with their descending ranks R_r(i), the first message, beginning with the intermediate node whose rank R_r(i1) is lower by one than that of the source node (R_r(s1)).

9 . The method of claim 8 , wherein an intermediate node rebroadcasts the first message despite having received the first message from a node that has a rank that is higher or lower than its own rank by at least two, respectively, only after having received the rebroadcast of the first message from the node having a rank that is higher or lower by one, respectively, or after not having received a rebroadcast from the node having a rank that is higher or lower by one, respectively, within a predetermined time period.

10 . The method of claim 8 , wherein each intermediate node may append data or a message of its own that is to be travelling in the same direction of travel as the first message, to a received message prior to rebroadcasting, optionally including a rank or identifier of a respective destination node, if the destination node of the appended message or data is different from that of the first message.

11 . The method of claim 8 , wherein any destination node removes the message that was intended for it and broadcasts any appended messages destined for destination nodes in the direction of travel of the first message.

12 . A method of locating a fault in a ranked linear arrangement of network nodes whose network nodes are configured to directly communicate with two or more neighbouring nodes in either direction of the ranked linear arrangement of network nodes, but in which no network node can directly communicate with all network nodes, the method comprising:

a first network node located at one end of the linear arrangement of network nodes broadcasting a topology checking message into the linear arrangement of network nodes,

all intermediate network nodes appending a topology checking message of their own to a received topology checking message and rebroadcasting the compound topology checking message only after having received the topology checking message from its direct upstream neighbour or after a backoff time period for the direct upstream neighbour has expired, and

a network node at the opposite end of the linear arrangement of network nodes analysing the received compound topology checking message for missing topology checking messages.

13 . The method of claim 12 , further comprising:

the network node at the opposite end of the linear arrangement of network nodes returning the result of the analysis to the first network node in a regular message, or

the network node at the opposite end of the linear arrangement of network nodes adding a topology checking message of its own to the compound topology checking message it received, broadcasting it, and

all intermediate network nodes between the network node at the opposite end and the first network node appending a further topology checking message of their own to a received topology checking message and rebroadcasting the compound topology checking message only after having received the topology checking message from its direct upstream neighbour or after a backoff time period for the upstream direct neighbour has expired, and

the first network node analysing the received compound topology checking message for missing topology checking messages.

14 . The method of claim 12 , further comprising, if a network node does not receive a rebroadcast from one of the up to n network nodes known to be located downstream in the direction of travel of a topology checking message:

broadcasting a topology checking message error message,

all intermediate network nodes between the network node that broadcast the topology checking message error message and the first network node rebroadcasting the topology checking message error message.

15 . A method of coordinated switching network nodes arranged in a fully configured and discovered linear arrangement of network nodes, which directly communicate with up to n neighbouring network nodes, but in which no network node can directly communicate with each one of the network nodes, between a first operating mode, in which at least the transceiver is inactive or powered down, and a second operating mode, in which at least the wireless transceiver is active or powered up, comprises:

broadcasting, by a first network node located at a first end of the linear arrangement of network nodes, a duty cycle message, wherein the duty cycle message includes at least a wakeup time that defines when to switch the network nodes to the second operating mode, and coordinated rebroadcasting the duty cycle message by all network nodes of the linear arrangement of network nodes,

switching each network node that has rebroadcast the duty cycle message to the first operating mode, and

switching to the second operating mode in accordance with the wakeup time.

16 . The method of claim 15 , further including, in any of the first and the intermediate network nodes, repeating the duty cycle message, if a rebroadcast of the duty cycle message from one or all network nodes further down the linear arrangement of network nodes that are within direct communication range is not received at the end of the respective backoff time periods, wherein at least the first and the intermediate network nodes only switch to the first operating mode after having received a rebroadcast of the duty cycle message from one or all network nodes further down the linear arrangement of network nodes that are within wireless range.

17 . The method of claim 15 , wherein a network node only switches to the first operating mode, if it has received a rebroadcast of the duty cycle message from one or all network nodes further down the linear arrangement of network nodes that are within wireless range, or after a predetermined maximum number of repetitions of broadcasting or rebroadcasting the duty cycle message.

18 . The method of claim 15 , wherein the duty cycle message further includes a duration of an active time period, defining a time period during which a network node is in the second operating mode before returning to the first operating mode.

19 . A network node having a microprocessor, associated volatile and non-volatile memory, and a communication interface, wherein, when the microprocessor executes corresponding computer program instructions stored in the non-volatile memory, the node is configured to operate an arrangement of a plurality of network nodes arranged in a linear configuration, each of which network nodes being configured to directly communicate with n neighbouring network nodes located in either direction of the linear arrangement of network nodes, and in which no network node can directly communicate with each one of the network nodes, by performing operations comprising:

determining and assigning an unambiguous and individual rank to each one of the plurality of network nodes, the rank of each network node having a major rank, and at least one network node having a minor rank, wherein the ranks are orderly increasing from one end of the linear arrangement of network nodes to the other end, and wherein each rank of a network node indicates a position of the respective network node within the linear arrangement of network nodes,

configuring the plurality of network nodes to coordinated toggling between a first and a second mode of operation, a power consumption of the network nodes in the first mode of operation being lower than in the second mode of operation, and

transmitting messages, using a non-synchronised or asynchronous, zero-signalling, stateless multipath and multi-hop message routing protocol, between the network nodes of the linear arrangement of network nodes via those network nodes that are in the second mode of operation.

20 . A linear arrangement of network nodes comprising at least two network nodes, each network node having a microprocessor, associated volatile and non-volatile memory, and a communication interface, wherein, when the microprocessor executes corresponding computer program instructions stored in the non-volatile memory, the node is configured to operate an arrangement of a plurality of network nodes arranged in a linear configuration, each of which network nodes being configured to directly communicate with n neighbouring network nodes located in either direction of the linear arrangement of network nodes, and in which no network node can directly communicate with each one of the network nodes, by performing operations comprising:

determining and assigning an unambiguous and individual rank to each one of the plurality of network nodes, the rank of each network node having a major rank, and at least one network node having a minor rank, wherein the ranks are orderly increasing from one end of the linear arrangement of network nodes to the other end, and wherein each rank of a network node indicates a position of the respective network node within the linear arrangement of network nodes,

configuring the plurality of network nodes to coordinated toggling between a first and a second mode of operation, a power consumption of the network nodes in the first mode of operation being lower than in the second mode of operation, and

transmitting messages, using a non-synchronised or asynchronous, zero-signalling, stateless multipath and multi-hop message routing protocol, between the network nodes of the linear arrangement of network nodes via those network nodes that are in the second mode of operation.