No
. 96-1886-01E
Rev
.
1.1
GTECH Aircon Radio (Model GWT154)
PAGE
21
OF
72
4.0
WIRELESS NETWORK INFRASTRUCTURE
4.1
Establishing
Network
The PAN Coordinator radio will establish an RF channel, PAN-ID, and network security key with
direction
from the Host CPU. Either the Host can force it to use a particular channel, or the radio
module can do an energy scan of all available channels. The Host CPU can also pre-set the PAN-ID or
it can automatically select an unused PAN-ID during network commissioning. The GTECH 802.14.5
wireless network will be implemented as a non-beacon-enabled network.
Often in beacon-less systems, an End Devices may still expect to periodically receive communication
from its Coordinator, often referred to as a heartbeat. In the event an End Device does not receive a
heartbeat within a reasonable period, the End Device may attempt to recover by scanning all channels
and requesting to rejoin its coordinator if found. This feature is not implemented in this design.
4.2
Device
Joining
Once a wireless network PAN Coordinator radio has been configured and started, the peripheral radios
may be joined to the PAN. End Device joining will be implemented in accordance to the 802.15.4
standard. Upon pairing activation by the End Device radio’s User Interface, the MAC will scan all
802.15.4 (mapped) RF channels by broadcasting a Beacon Request and registering any successful
responses in a PAN Descriptor list.
Once all enabled channels have been scanned, or the PAN Descriptor list is at maximum, the End
Device will sequentially unicast an Associate Request to each of the PAN Coordinators found in the
Descriptor list, and wait for a response. If it does not receive a response in a random amount of time
(between
TBD
seconds) it will try the next PAN in the Descriptor list, or if only one PAN, retry. This
time delay will keep the network from being overloaded with requests and reduce the chance of RF
collisions with other End Device radios.
When the Coordinator receives an Associate Request and successfully decrypts using the default
factory key, it saves the End Device’s 64-bit EUI address in a list for later processing by the Host
CPU. Subsequently, the End Device will issue a Data Request to the Coordinator, if the previous
Associate Request was accepted, the Coordinator will reply with an Associate Response. The End
Device has temporarily been joined to the PAN and will remain so until it is later permanently joined
to the PAN, or it times-out.
A failsafe timeout should be employed in the End Device radios during joining to ensure that if the
sequence fails to end in success, the radio discards any joining parameters obtained, and return the
radio to its inactive state.
The Host CPU will determine the length of time the Coordinator will accept Association Requests;
multiple End Devices may be associated during any given joining session. After terminating the
association period, the Host CPU gets the EUI-64 address list from the Coordinator.
Based upon each End Device’s EUI-64, the Host CPU will decide whether that device is allowed on
the PAN. The Host CPU instructs the Coordinator to enter an End Device into the Access Control List