User manual

Chapter 2 - Managing a Single Device/Cell Performance Parameters Page
AlvariCRAFT Device Manager 153 User Manual
The user can configure a Packet Threshold to Test Up Rate parameter to define
the number of successfully transmitted frames after which the unit will test the
higher modulation. The number of frames used for this test can also be configured
by the user via the Packet No On Upper Rate parameter.
When a frame needs to be retransmitted, the Statistics-Based Rate Control
algorithm may gradually decrease the modulation used for retransmitting that
particular frame. Based on the Number of HW retries parameter, the unit will try
to perform the three final retransmission attempts at progressively lower
modulations.
The retransmission mechanism described above does not apply for test frames
sent for evaluating link quality on higher modulations. If the number of HW
retries is lower than 3 or if the initial modulation is lower than 4, the number of
modulations used for retransmission will be limited as shown in Table 2-5
Table 2-5: Examples of Retransmissions on Different Modulation Levels
Scenario Transmission Attempts
Modulation Tries
Initial Modulation: 8
Number of HW Retries: 10
Total Number of Tries: 1+10 = 11
88
71
61
51
Initial Modulation: 6
Number of HW Retries: 5
Total Number of Tries: 1+5 = 6
63
51
41
31
Initial Modulation: 7
Number of HW Retries: 2
Total Number of Tries: 1+2 = 3
71
61
51
Initial Modulation: 3
Number of HW Retries: 12
Total Number of Tries: 1+12 = 13
311
21
11
Adaptive Modulation
Algorithm
This option switches between the basic Adaptive Modulation and the
Statistics Based Rate Control algorithm.