Solectek SkyWay-Excel Series User Manual page 44

GPS Mode: This mode should be used when there are co-located Master units at the same time.
In order to use this mode, the Master unit must be a GPS-ready version, e.g. AS5802 instead of
AS5800. The GPS port on the Master unit must be connected to a GPS sync controller.
Frame – This refers to the time slot (frame) duration that the Master unit allows for each
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downlink / uplink cycle. The default value is 10ms. The other choice is 20ms.
DL/UL Ratio – Each time slot is divided into downlink traffic (DL) and a uplink traffic (UL).
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The default is 5:5 (most Enterprise network). Available DL/UL radios are 9:1, 8:2, 7:3,
6:4, 5:5, 4:6, 3:7, 2:8, and 1:9.
The concepts of frame sizes and DL/UL ratios are explained in the following diagram. The
Master unit operates in a 10ms or 20ms cycle during which downlink and uplink portions are
defined by the DL/UP ratio. During the downlink portion, the Master unit will send data to Slave
units using polling MAC and then the Master unit switches to the uplink portion and Slave units
will send data during that portion of the cycle. This cycle continues during the period defined by
the frame size (10ms or 20ms).
DL/UP ratios should be set in accordance with the application. For example, ISP networks tend
to be downlink heavy with subscriber downloading web contents. In that case, the 7:3 ratio may
be appropriate. For IP camera backhaul, the traffic is dominated by uplink traffic coming from
cameras attached to Slave units. In that case, the 2:8 ratio may be suitable.
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