5 Enabling Multiple Gateway Support

A critical part of enabling the previously described network features has to do with providing a sensor device with the capability to switch between different PAN coordinators.

Consider for instance a network which is initially configured with one local gateway and a large amount of sensor devices. Given the distance between some of the sensor devices and the gateway, packets are being dropped, affecting the quality of the network. As new devices are added to the network, it is determined by the network’s administrator, that a second local gateway must be deployed to act as PAN coordinator for new sensor devices, and to improve the network coverage for previously deployed sensors.

Nevertheless, given that a sensor device can only exchange packets with its current PAN coordinator, the newly deployed local gateway, does not have a beneficial impact on the network’s coverage for the already deployed sensors. In order for the network to fully benefit from the addition of the second local gateway, the application must consider a procedure so that the sensors that have been previously deployed can switch between PAN coordinators.

This section describes the modifications needed so that an application can support PAN coordinator switching and therefore, multiple gateway support. The following steps require no modification to the TI 15.4-Stack and use the sensor and collector examples included in the SimpleLink SDK as base projects. Furthermore, the steps cover Beacon and Non-Beacon mode for the two most-common coordinator switching scenarios.