Method of and a node device for transmitting a trigger message in a network of operatively interconnected node devices
A method of, a node device and a computer program product arranged for transmitting a trigger message in a network of operatively interconnected node devices arranged along at least one elongated track is disclosed. The trigger message is configured for triggering a service provided by the node devices to a moving object. The node devices are divided into a plurality of groups, each group comprising, seen in a moving direction of the object, a first edge node device, at least one normal node device and a second edge node device, within each group at least the first edge node device and the second edge node device respectively comprising a sensor for detecting the object. The method comprises the step of: receiving, by a first edge node device in a group, a first object-approaching trigger message transmitted by a second edge node device in an immediate preceding group; and transmitting, by the first edge node device in the group, a second object-approaching trigger message to other node devices in the group. The method therefore ensures that only forward group trigger of the service is performed.
1 . A method of triggering a service provided by a network of operatively interconnected node devices arranged along at least one elongated geographic track to an object moving along said geographic track, said node devices divided into a plurality of groups, each of said plurality of groups comprising a first edge node device, at least one normal node device, and a second edge node device, within each of said plurality of groups at least said first edge node device, said at least one normal node device, and said second edge node device each respectively comprising a sensor for detecting said object, said method comprising:
generating, by a node device within a group of said plurality of groups, an event log comprising a plurality of items for node devices in said group including said node device, each item comprising a unique identifier of a respective node device in said group with a sensor and a time of detecting said object by a sensor of said respective node device;
identifying, by said node device within said group, itself as an edge node device when an item comprising its unique identifier comprises an earliest or latest time of detecting said object by a sensor of said node device;
receiving, by a second edge node device in said group, an object-detected message from a first edge node device or a normal node device in said group; and
determining, by said second edge node device in said group, that said object has been detected by a sensor of said second edge node device,
wherein said object-detected message is configured to trigger a service provided by said node devices to said object.
2 . The method according to claim 1 , wherein each item of said event log further comprises a speed of said object.
3 . The method according to claim 1 , further comprising identifying, by a particular edge node device in a group, an edge node device as its closest edge node device in a neighbouring group by way of the following steps:
receiving, by said particular edge node device, a number of one hop broadcast messages transmitted by edge node devices in neighbouring groups;
creating, by said particular edge node device, a neighbouring edge node table comprising a plurality of items, each item comprising a unique identifier of an edge node device transmitting a one hop broadcast message, a group identifier of said edge node device, and a signal strength indicator of said one hop broadcast message; and
identifying, by said particular edge node device, an edge node device in a neighbouring group as said closest edge node device in said neighbouring group based on received one hop broadcast messages and/or signal strength of said received hop broadcast messages.
4 . The method according to claim 3 , further comprising:
transmitting, by said particular edge node device, a unicast message to said edge node device identified as its closest edge node device in an immediate preceding group; and
receiving, by said particular edge node device, a response unicast message as a confirmation from said edge node device identified as its closest edge node device in said immediate preceding group.
5 . The method according to claim 1 , wherein said node devices comprise at least one of smart pole devices and lighting devices providing at least one of a lighting service, a network access service and a geographic routing service to said object.
6 . The method according to claim 1 , wherein said second edge node device comprises at least one of smart pole devices and lighting devices.
7 . A network system comprising said operatively interconnected node devices arranged along at least one elongated geographic track, wherein the network system is configured to provide a service to an object according to claim 1 .
8 . A non-transitory computer program product, comprising a computer readable storage medium storing instructions which, when executed on at least one processor, cause said at least one processor to carry out the method according to claim 1 .
9 . A method of triggering a service provided by a network of operatively interconnected node devices arranged along at least one elongated geographic track to an object moving along said geographic track, said node devices divided into a plurality of groups, each of said plurality of groups comprising a first edge node device, at least one normal node device, and a second edge node device, within each of said plurality of groups at least said first edge node device and said second edge node device each respectively comprising a sensor for detecting said object, said method comprising:
receiving, by a second edge node device in a group of said plurality of groups, an object-detected message from a first edge node device or a normal node device in said group;
determining, by said second edge node device in said group, that said object has not been detected by a sensor of said second edge node device;
sending, by said second edge node device, a first object-approaching message to a first edge node device in an immediate subsequent group;
wherein said object-detected message and said first object-approaching message are configured to trigger a service provided by said node devices to said object.
10 . The method according to claim 9 , wherein said first object-approaching message is a unicast message, said object-detected message is a broadcast message.
11 . The method according to claim 9 , further comprising:
transmitting, by said first edge node device in said immediate subsequent group, a second object-approaching message to other node devices in said immediate subsequent group in response to receiving said first object-approaching message.
12 . The method according to claim 11 , further comprising:
transmitting, by a second edge node in said immediate subsequent group, another first object approaching message to a first edge node in a next immediate subsequent group in response to receiving said second object-approaching message.
13 . The method according to claim 11 , wherein said first and second object-approaching messages and said object-detected message are configured to trigger said service for a determined period of time, said determined period of time of said service triggered by said first and second object-approaching messages is longer than said determined period of time of said service triggered by said object-detected message.
14 . The method according to claim 9 , further comprising:
transmitting, by said first edge node device in said immediate subsequent group, an object-detected message only to node devices in said immediate subsequent group, in response to detecting said object by a sensor of said first edge node device in said immediate subsequent group, said object-detected message configured for triggering a second edge node device in said immediate subsequent group to transmit a further first object-approaching trigger message to a first edge node device in a next immediate subsequent group.
15 . The method according to claim 9 , wherein said first object-approaching message comprises an indicator indicating a number of groups to be sequentially triggered by relaying said first object-approaching trigger message from said second edge node device in said first group to a first edge node device in said immediate subsequent group.
16 . The method according to claim 9 , wherein said node devices comprise at least one of smart pole devices and lighting devices providing at least one of a lighting service, a network access service and a geographic routing service to said object.
17 . The method according to claim 9 , wherein said second edge node device comprises at least one of smart pole devices and lighting devices.
18 . A network system comprising said operatively interconnected node devices arranged along at least one elongated geographic track, wherein the network system is configured to provide a service to an object according to claim 9 .
19 . A non-transitory computer program product, comprising a computer readable storage medium storing instructions which, when executed on at least one processor, cause said at least one processor to carry out the method according to claim 9 .