Trango Broadband TrangoLINK-45TM - Manual (Page 27)

Configuration Automatic Rate Shifting Feature Description
Trango Broadband Wireless — TrangoLINK-45 page 27
Automatic Rate Shifting Feature Description
With autorateshift feature enabled, the radios will automatically renegotiate the modulation method and speed
speed to maximize wireless link integrity. The link speed will vary depending on two factors: 1) the number of
ARQ errors received, 2)successful processing of special link assessment packets sent in both the current and
next higher speed. The radio will shift to the next higher in speed when no errors are detected. The radio will
shift down in speed if error rate is excessive.
Notes regarding the autorateshift feature:
1. The radio will begin initial speed test when upon association to peer radio. There are 40 steps and around 50
seconds to complete this initial test. The radio will send link assessment packets (3600 byte packets at a rate of
100 packets per second) at the highest speed (54 Mbps). The radio will deliver payload at the speed which is
specified before association. If the assessment packet dropping rate is higher than 10 percent, the speed test will
decrease the speed for assessment packets. If the current payload speed is higher than the speed of assessment
packet, the radio will set the current payload speed to be the same as the assessment packet’s speed. If the
current payload speed is lower than the assessment packet’s speed and more than 500 assessment packets have
been transmitted, the radio will set the payload speed to be the same as assessment packet’s speed.
2. After completion of initial speed test, the radio will set the payload speed to be the same as the final speed of
initial speed test.
3. The radio will check link quality and adjust payload speed periodically.
a. The radio will increase payload speed every 60 seconds, if
i. Speed test which is running at higher speed is successful. –and-
ii. Payload’s ARQ retransmit rate is less than 10 percent.
b. Radio will decrease payload speed every 10 seconds, if
i. Speed test which is running at payload speed is failure. –and-
ii. Payload’s ARQ retransmit rate is higher than 10 percent.
4. Payload speed can be changed manually when auto rate shift is on. But the speed setting will not be sustained.
Example:
#> autorateshift on
Success.
#>