WaveRider LMS4000, User Manual

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3 Detailed Description
36 APCD-LM043-4.0
3.5.2 MAC Layer (Polling MAC)
EUM States
The LMS4000 900 MHz Radio Network data transmission is based on a WaveRider’s
patented polling algorithm, which takes advantage of patterns found in typical Internet usage.
Based on the EUM’s subscribed grade of service and current traffic level, the Polling MAC
continuously adjusts the rate at which the EUM is polled. This process is illustrated in the EUM
State Diagram in
Figure 22 .
Figure 22 EUM State Diagram
When an EUM first powers up, it is in an unregistered state.
In the unregistered state, the EUM is not being polled and is therefore not passing traffic. As
outlined in
EUM Registration on page 25, an unregistered EUM sends a registration_request
to the CCU. If the EUM is authorized in the CCU Authorization Table, it becomes registered/
disassociated.
In the registered/disassociated state, the EUM is still not being polled. But if the EUM has
traffic to send, it tries to associate with the CCU through the random access channel. The
EUM may also become associated if the CCU has a payload to send to the EUM. Once
associated, the state of the EUM changes to active/associated.
In the active/associated state, the EUM is polled often, at a rate consistent with its subscribed
grade of service. If there is no traffic to or from an active/associated EUM for a defined interval
(typically set around 0.5 seconds), the state of the EUM changes to inactive/associated.
An inactive/associated EUM is polled less frequently than an active/associated EUM. If traffic
is resumed, the state of the EUM changes back to active/associated. If there is no traffic for a
longer defined interval (typically set around 2 seconds), the state of the EUM changes back to
registered/associated.
inactive/
associated
active/
associated
unregistered
registered/
disassociated
Random access for
EUM or payload for
EUM arrives at CCU
Traffic in either
direction
No traffic for ~0.5s
EUM is
not polled
EUM is
polled
often
EUM is
polled less
often
N
o
tra
ffi
c
fo
r ~
2s
Pow
er u
p
EUM is
not polled
regRequest/regResponse
From any state:
- deregRequest
- extended period with no traffic (~12h)
* Parameters are derived from the GOS
configuration file, and vary with EUM
grade of service.