Increasing reliability and reducing latency in a wireless network

A method of increasing reliability of a wireless mesh network in a process control system including a plurality of nodes, wherein the method is executed in a computer that manages the wireless mesh network, the method comprising:

• (i) establishing a plurality of direct connections, wherein each of the plurality of direct connections is a unidirectional wireless connection having a transmitting node and a receiving node;
• (ii) generating a plurality of directed graphs defining communication paths between pairs of nodes based on a topology of the wireless network, wherein:
• each directed graph includes at least two of the plurality direct connections,
• each directed graph has exactly one source node, a destination node, and one or more intermediate nodes,
• the source node of a particular directed graph is associated with only one or more outbound communication connections on the particular directed graph, and
• the destination node of the particular directed graph is associated with only one or more inbound communication connections on the particular directed graph;
• (iii) defining a multiplicity of concurrent superframes as repeating cycles of consecutively scheduled communication timeslots of a single predefined duration, wherein:
• a first portion of the communication timeslots of a first superframe included in the multiplicity of concurrent superframes is used for delivery of a first set of data packets over a first directed graph included in the plurality of directed graphs,
• a second portion of the communication timeslots of the first superframe included in the multiplicity of concurrent superframes is used for delivery of a second set of data packets over a second directed graph included in the plurality of directed graphs,
• the first set of data packets and the second set of data packets include process control data generated by or provided to control a set of physical control functions performed by a set of field devices to control a process in the process control system,
• a number of timeslots in each of the multiplicity of concurrent superframes defines a length of the superframe, and
• defining the multiplicity of concurrent superframes includes assigning at least one of the consecutively scheduled communications timeslots based on a predetermined periodic update rate of at least one of the plurality nodes;
• (iv) defining a plurality of primary links to generate a communication schedule of the wireless mesh network including, for each directed graph:
• associating each primary link with one of the plurality of direct connections of the each directed graph, wherein the one of the plurality of direct connections is associated with a primary fixed communication path from the source node to the destination node, wherein at least one intermediate node of the each directed graph, in response to a failure to deliver a data packet along the primary link, transmits the data packet along a secondary link associated with another one of the plurality of direct connections, and
• allocating a different individual timeslot associated with one of the plurality of superframes to each primary link of the each directed graph so that the allocated individual timeslots are scheduled in the order in which packets travel through the each directed graph,
• wherein at least one of the generating the plurality of directed graphs or the defining the plurality of primary links to generate the communication schedule is based on a set of requirements corresponding to delivery of process control data from a particular source node to a particular destination node;
• and
• (v) communicating, to each source node, each intermediate node, and each destination node, one or more portions of one or more respective directed graphs and one or more respective different individual timeslots corresponding to one or more respective primary links,
• wherein a first node of the plurality of nodes included in the wireless mesh network transmits, in accordance with a respective one or more portions of the one or more respective directed graphs and the one or more respective different individual timeslots, respective process control data to a second node of the plurality of nodes and other process control data to a gateway in connection with another communication network operating in the process control system.

A method of reliably transferring data in a wireless communication network operating in a process control environment and including a plurality of network devices, wherein the method is executed in a computer-based centralized network manager that manages the wireless communication network, the method comprising:

• (i) generating a routing scheme of the wireless communication network, including defining a plurality of routing graphs based on a topology of the wireless communication network, each of the plurality of routing graphs having a plurality of nodes and a set of edges, each of the plurality of nodes corresponding to a respective one of the plurality of network devices;
• (ii) defining a multiplicity of superframes each having a set of consecutively numbered communication timeslots of a predetermined duration based on predetermined regular communication requirements of at least some of the plurality of network devices, wherein a first portion of the communication timeslots of a first superframe included in the multiplicity of superframes is used for delivery of first process data using a first routing graph included in the plurality of routing graphs, and a second portion of the communication timeslots of the first superframe included in the multiplicity of superframes is used for delivery of second process data using a second routing graph included in the plurality of routing graphs, and wherein at least one of the first process data or the second process data is generated by or provided to control a physical control function performed by a field device to control a process in the process control environment;
• and
• (iii) combining the routing scheme with the definition of the multiplicity of superframes to define a communication schedule of the wireless communication network, including, for at least the first superframe included in the multiplicity of superframes and a respective particular routing graph in the plurality of routing graphs:
• assigning communication timeslots within the at least the first superframe to edges of the respective particular routing graph so that the communication timeslots are associated with the set of edges of the respective particular routing graph according to a predetermined order from the source node to the destination node of the respective particular routing graph, and
• communicating, to each of the plurality of network devices corresponding to respective nodes included in the respective particular routing graph, one or more portions of the respective particular routing graph and one or more respective communication timeslots,
• wherein:
• at least a portion of at least one of the defining the plurality of routing graphs or the defining the multiplicity of superframes is based on one or more requirements corresponding to delivery of the first process data from a source node to a destination node by way of at least one intermediate node, the source node, the destination node and the at least one intermediate node included in the plurality of nodes, and
• a first network device transmits, via the wireless communication network and according to a respective one or more portions of the respective particular routing graph and the one or more respective communication timeslots, respective process data to a second network device of the plurality of network devices to control the process and other process data to a gateway in connection with another communication network operating in the process control environment.

A method of reliably transferring data in a communication network operating in a process control environment, wherein the method is executed in a computer-based centralized network manager that manages the communication network, the method comprising:

• (i) generating a first routing graph having a plurality of nodes and a set of edges based on a topology of the communication network, including:
• associating each of the plurality of nodes with a respective one of a plurality of network devices participating in the communication network;
• associating each edge in the set of edges with a respective connection between two of the plurality of network devices participating in the communication network;
• associating a first one of the plurality of nodes with a source of the first routing graph;
• and
• associating a second one of the plurality of nodes with a destination of the first routing graph, wherein the source of the first routing graph and the destination of the first routing graph are separated by at least one intermediate node;
• and
• (ii) generating a communication schedule of the communication network, including:
• (a) selecting a superframe of a particular length for transmitting data from the source of the first routing graph, wherein:
• the superframe includes a number of consecutively scheduled communication timeslots defining the length of the superframe,
• a first portion of timeslots in the superframe are used for delivery of first process control data using the first routing graph,
• a second portion of communication timeslots in the superframe are used for delivery of second process control data using a second routing graph,
• at least one of the first process control data or the second process control data is generated based on a physical control function performed by a field device to control a process in the process control environment, and
• the length of the superframe is selected based on a criterion associated with one of the source or the destination of the first routing graph or one of the source of the destination of the second routing graph;
• and
• (b) assigning at least some of the communication timeslots of the superframe to the set of edges of the first routing graph according to a predetermined order of traversal of the first routing graph from the source to the destination,
• wherein at least one of the generating the first routing graph or the generating the communication schedule is based on a set of requirements corresponding to delivery of the first process control data from a source network device via one or more intermediate network devices to a destination network device, the source network device, the destination network device and the one or more intermediate network devices included in the plurality of network devices;
• and
• (iii) communicating, to network devices corresponding to the plurality of nodes of the first routing graph, respective one or more portions of the first routing graph and one or more respective communication timeslots,
• wherein a first network device transmits, via the communication network and according to a respective one or more portions of the first routing graph and the one or more respective communication timeslots, respective process control data to a second network device node for performing a control function in the process control environment and other respective process control data to a gateway in connection with another communication network operating in the process control environment.

A multi-node mesh communication network operating in a process control environment, comprising:

• a plurality of field devices to perform respective control functions in the process control environment and to define respective nodes of the multi-node mesh communication network;
• a network device operating in the multi-node mesh communication network to define a node of the multi-node mesh communication network;
• first computer-executable instructions stored on a computer-readable memory and executable to generate and store a routing scheme of the multi-node mesh communication network and a communication schedule of the multi-node mesh communication network, at least one of the routing scheme or the communication schedule based on a set of requirements corresponding to delivery of process data from a source field device to a destination field device,
• the routing scheme including a multiplicity of directed graphs, each of the multiplicity of directed graphs connecting a respective pair of nodes of the multi-node mesh communication network via one or more intermediate nodes, wherein each direct connection between two nodes associated with a particular directed graph define an edge of the graph;
• and
• the communication schedule including a superframe including a number of consecutively scheduled communication timeslots defining a length of the superframe, a first portion of the communication timeslots of the superframe used for delivery of first process data using a first directed graph in the multiplicity of directed graphs, and a second portion of the communication timeslots of the superframe used for delivery of second process data using a second directed graph in the multiplicity of directed graphs, wherein the length of the superframe is based on a predetermined periodic update rate of one of the plurality of field devices, and wherein at least one of the first process data or the second process data is generated based on a physical control function performed by a field device to control a process in the process control environment;
• and
• second computer-executable instructions stored on the computer-readable memory and executable to communicate, to the one of the plurality of field devices, respective portions of a particular directed graph with which the one of the plurality of field devices is associated and respective one or more corresponding communication timeslots of the superframe for the one of the plurality of field devices to use for transmitting respective process data to a gateway in connection with another communication network operating in the process control environment.