Wavenet Technology Pty Ltd. BM2900D Manuel D’Utilisation

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Appendix D - Application Development __________________________ Boomer II User Manual & Integrator’s Guide 
Copyright Wavenet Technology © November 2003 
120 
BM210012WT37 
Conserve battery life when out-of-range  
When all channels (from both dynamic and static channel lists) are 
scanned and network contact is not established, the wireless modem 
enters a scan-delay state. The scan-delay starts at one second and 
doubles on each scan cycle failure, to a maximum of 255 seconds 
between scan cycles. This delay time is reset to one second by 
establishing a network connection or by power-cycling the device. 
Re-establish network contact following inbound SDU failure (no 
response) and poor RF RSSI or signal quality  
Any wireless modem experiencing a no-response inbound SDU failure 
and either with RSSI or quality below the exit threshold level must re-
establish network contact. If unable to re-establish network contact, the 
modem indicates an out-of-range event. When network contact is re-
established, the wireless modem indicates an in-range event. The client 
application then resubmits any queued inbound SDU last rejected with 
an out-of-range response. 
Re-establish network contact due to loss of outbound channel  
The wireless modem attempts to re-establishes network contact 
following loss of the outbound channel. If unable to re-establish 
network contact, the modem indicates an out-of-range event, and 
procedures to re-establish network contact are initiated. When network 
contact is re-established, the wireless modem indicates an in-range 
event. The client application then resubmits any queued inbound SDU 
last rejected with an out-of-range response. 
Seek and locate the preferred alternate channel when the existing 
channel degrades to a marginal level  
When the existing RF channel degrades to a marginal (but still usable) 
level, the device periodically listens to neighbouring channels to 
determine whether a preferred alternate channel exists. This action 
occurs when the device would otherwise be sleeping, to prevent impact 
to the device’s synchronized-receive capability with the network. 
To be considered, a preferred alternate channel must meet the 
minimum channel entry criteria and be 5 dBm better than the current 
channel. If located, a full channel acquisition is performed to verify all 
other aspects of the alternate channel before registering to the new 
channel. This preferred-channel pre-roam algorithm is performed at 
intervals that increase exponentially and with identical reset conditions. 
See “Conserve battery life when out-of-range” above.