GE MDS entraNET 900, Техническое руководство

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05-4055A01, Rev. E MDS entraNET Technical Manual 163
6. View the
Radio Retries
and
No Ack
counts at the point of maximum
RSSI level. They should be the same or lower than the previous
reading.
(Main Menu > Performance Information > Packet Statistics > Wireless Packet
Statistics)
If the RSSI peak results in an increase in the
Radio Retries
and
No Ack
counts, the antenna might be aimed at an undesired signal source.
Try a different antenna orientation.
6.5.3 Tips for Improving Data Throughput
Some suggestions are offered below for maximizing the throughput of
the radio system. It is important to realize that an exact formula for every
radio system cannot be given. Much depends on the number of radios
contained in the radio system, the size of data strings being sent, the type
of data being sent, zone quality (interference potential), and data speed.
You should find several items here, however, that can be applied to your
radio system.
To Maximize Throughput of Data and Reduce Latency Time
• (AP only) Increment the
Hop Time
to the maximum of 28 ms.
This lowers the overhead, since it stays longer on a channel. The
drawback is that if a particular channel becomes blocked, it will
take longer to hop to another channel.
(
Main Menu>Radio Configuration>hop Time
)
• Match the buffer sizes and hop times to accommodate the
majority of message sizes. For example, a 7 ms hop time is best
suited to short data bursts, such as in telemetry applications. A
28 ms hop time is better suited to large data strings, such as
sending Web pages over the radio link.
The following table provides suggested settings for four different
message sizes.
Table 6-7. Hop Time Setting versus Message Size
Hop Time
(msec)
FEC Status* Bytes per
Packet
28 OFF 325
ON 151
14 OFF 139
ON 59
7 OFF 45
ON 11
* FEC ON is generally not recommended if optimal
throughput is desired. The transceiver Repeat-Retry
function is a more efficient means of ensuring message
delivery.