User Manual

Introduction SmartPolling™ Overview
Trango Broadband Wireless — Access5830 User Manual Rev. H 3.0 page 2
SmartPolling™ Overview
One of the major advantages of the Access5830 system is the ability of the AP to handle multiple SU
connections, and share the 10 Mbps data throughput very efficiently. Bandwidth allocation is managed by the
AP’s SmartPolling™ algorithm according to provisioning rules set up by the system administrator. The AP
polls each SU in a round robin format to determine if the SU has data to transfer. The SU only transmits the
data “upstream” to the AP when the AP gives it authorization via a “transmit grant.” The SU parses every
“downstream” data packet from the AP, and identifies packets intended for it. In order for an SU to
communicate with an AP, the system administrator must first add the MAC address and ID number of that SU
to the subscriber database in the AP. The SmartPolling™ algorithm will poll active SUs more often, thus not
wasting time and bandwidth on inactive SUs. Several other parameters are considered in the SmartPolling™
algorithm, including Committed Information Rate (CIR), Maximum Information Rate (MIR), and the Priority
Setting.
Each of the above parameters is set in the AP by the system administrator and cannot be controlled at the SU.
These parameters will be covered in greater detail later in this text.
When power is first applied to a properly installed SU, it will scan all the channels in its scan table searching for
an AP with the same Base ID that is sending transmit grants. The SU will then stop the channel scanning
process and lock onto the AP’s channel and respond to the AP using maximum RF power. Before the AP can
add the SU to the polling list, it must authenticate the SU by verifying the MAC address and performing a
ranging operation to the SU.
Once successfully authenticated and ranged, the SU will be added to the AP’s normal polling list. The AP will
then adjust the RF transmit power of the SU according to the Target RSSI parameter set in the AP. This process
is referred to as “power leveling.”