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E. Fraccaroli and D. Quaglia
• router devices, i.e., all devices that have the ability to route packets in the
wireless mesh network;
• adapters that bind wired HART devices into the wireless mesh network;
• handheld devices carried by mobile users such as plant engineers and service
technicians;
• a single gateway (may be redundant) that functions as a bridge to the host
applications;
• access points that connect wireless mesh network to the gateway;
• a single Network Manager (may be redundant) that may reside in the gateway
device or be separate from the gateway;
• a Security Manager that may reside in the gateway device or separate from the
gateway.
In WirelessHART, communications are precisely scheduled based on TDMA and
employ a channel hopping scheme for added system data bandwidth and robustness.
The vast majority of communications are directed along graph routes in the wireless
mesh network. Graphs are a routing structure that creates a connection between
network devices over one or more hops and one or more paths. Scheduling is
performed by a centralized Network Manager which uses overall network routing
information in combination with communication requirements that devices and
applications have provided. The schedule is translated into transmit and receive
slots and transferred from the Network Manager to individual devices; devices are
only provided with information about the slots for which they have to transmit or
receive requirements. The network manager continuously adapts the network graphs
and network schedules to changes in the network topology and communication
demand [33].
Scaling WirelessHART to service large numbers of wireless devices and high
network data rates can be accomplished in a number of ways. One of the ways
to do this is to use multiple access points as shown in Fig. 3.16. This architecture
allows for a WirelessHART centralized network management of the wireless
communications and has the following advantages:
• it coordinates the wireless resources to prevent islands that overlap in the RF
space from interfering;
• it reuses wireless resources in non-overlapping islands to scale the network to
large number of devices and higher system throughput;
• it provides multiple backbone access points for higher throughput to the backbone network (each access point has the potential throughput of 100 packets per
second);
• it provides access points to connect to backbones that go to different plant
organizations and separate plants;
• WirelessHART islands may represent different parts of a plant like separate
operations or separate geographic regions.
Figure 3.17 shows the protocol stack of WirelessHART. Physical and Data
Link Layers are based on the IEEE 802.15.4-2006 standard using 2.4 GHz band
E. Fraccaroli and D. Quaglia
• router devices, i.e., all devices that have the ability to route packets in the
wireless mesh network;
• adapters that bind wired HART devices into the wireless mesh network;
• handheld devices carried by mobile users such as plant engineers and service
technicians;
• a single gateway (may be redundant) that functions as a bridge to the host
applications;
• access points that connect wireless mesh network to the gateway;
• a single Network Manager (may be redundant) that may reside in the gateway
device or be separate from the gateway;
• a Security Manager that may reside in the gateway device or separate from the
gateway.
In WirelessHART, communications are precisely scheduled based on TDMA and
employ a channel hopping scheme for added system data bandwidth and robustness.
The vast majority of communications are directed along graph routes in the wireless
mesh network. Graphs are a routing structure that creates a connection between
network devices over one or more hops and one or more paths. Scheduling is
performed by a centralized Network Manager which uses overall network routing
information in combination with communication requirements that devices and
applications have provided. The schedule is translated into transmit and receive
slots and transferred from the Network Manager to individual devices; devices are
only provided with information about the slots for which they have to transmit or
receive requirements. The network manager continuously adapts the network graphs
and network schedules to changes in the network topology and communication
demand [33].
Scaling WirelessHART to service large numbers of wireless devices and high
network data rates can be accomplished in a number of ways. One of the ways
to do this is to use multiple access points as shown in Fig. 3.16. This architecture
allows for a WirelessHART centralized network management of the wireless
communications and has the following advantages:
• it coordinates the wireless resources to prevent islands that overlap in the RF
space from interfering;
• it reuses wireless resources in non-overlapping islands to scale the network to
large number of devices and higher system throughput;
• it provides multiple backbone access points for higher throughput to the backbone network (each access point has the potential throughput of 100 packets per
second);
• it provides access points to connect to backbones that go to different plant
organizations and separate plants;
• WirelessHART islands may represent different parts of a plant like separate
operations or separate geographic regions.
Figure 3.17 shows the protocol stack of WirelessHART. Physical and Data
Link Layers are based on the IEEE 802.15.4-2006 standard using 2.4 GHz band