User's Manual

1-12 Millennial Net
Introduction
Store and Forward
In many applications, data can be captured and stored or even processed by a sensor node
before it is transmitted to the gateway or base station. Instead of immediately transmitting
every data unit as it is acquired, aggregating and processing data by remote sensor nodes can
potentially improve overall network performance in both power consumption and bandwidth
efficiency. One example of a store-and-forward application is cold-chain management where
the temperature in a freight container carrying produce or pharmaceuticals, for instance, is
captured and stored; when the shipment is received, the temperature readings from the trip are
downloaded and viewed to ensure that the temperature and humidity stayed within the desired
range.
Bi-Directional Dialogue Data Models
Bi-directional dialogue data models are characterized by a need for two-way communication
between the sensor/actuator nodes and gateway/application. The MeshScape system supports
the bi-directional dialogue data models described in this section.
Polling
Controller-based applications, such as those found in building automation systems, use a
polling data model. In this model, there is an initial device discovery process that associates a
device ID with each physical device in the network. The controller then polls each device on the
network successively, typically by sending a serial query message and waiting for a response to
that message. For example, an energy management application would use a polling data model
to enable the application controllers to poll thermostats, variable air volume sensors, and other
devices for temperature and other readings.
On-Demand
The on-demand data model supports highly mobile nodes in the network where a gateway
device enters the network, automatically binds to that network and gathers data, then leaves
the network. With this model, one mobile gateway can bind to multiple networks and multiple
mobile gateways can bind to a given network. An example of an application using the
on-demand data model is a medical monitoring application where patients in a hospital wear
sensors to monitor vital signs and doctors access that data via a PDA that is a mobile gateway. A
doctor enters a room and the mobile PDA automatically binds with the network associated with
that patient and downloads vital sensor data. When the doctor enters a second patient's room,
the PDA automatically binds with that network and downloads the second patient's data.
Broadcast Data Models
Broadcast data models are characterized by a need for one-to-many communication between
the gateway/application and sensor/actuator nodes. The MeshScape system supports the
broadcast data models described in this section.
Burst
The burst data model is characterized by an uneven pattern of data transmission from the
gateway/application to all sensor/actuator nodes on the wireless mesh network. The burst data
model has been used with industrial lighting applications.