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# Reply To: HR calculation ALU

#60946 Pix
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Rex, Jane,

Rex, your post seems to reach valid conclusions but the process is a little unclear.

The variable is AV_LOAD, which is the current load of the cell.
AV LOAD = number of busy TCH in the cell / number of available TCH in the cell.
For example : 3 TRX, 21 timeslots “TCH”
Assume : 11 HR Calls + 5 FR Calls
It means that there are 6 timeslots currently defined as HR (= carrying 2 TCH), while the other 15 timeslots are “Full” (= 1 TCH)

AV_LOAD = (11 + 5) busy TCH / (6*2 + 15) available TCH = 16 / 27 = 59%

The 2 parameters to control HR “non-AMR” are
THR_FR_LOAD_U_SV1
THR_FR_LOAD_L_SV1

If AV LOAD > THR_FR_LOAD_U_SV1
Then *New* calls are setup in HR

If AV LOAD < THR_FR_LOAD_L_SV1 Then *New* calls are setup in FR. It is important to understand that even though the load is decreasing below THR_FR_LOAD_U_SV1 (the upper threshold) ... the new calls are still setup in HR. They are setup in HR as long as the load is floating above the THR_FR_LOAD_L_SV1. Draw the graph to really understand this. Basically, my advice is to tune the THR_FR_LOAD_L_SV1= 30% THR_FR_LOAD_U_SV1 = 70% and if you see there is still congestion, then try this : THR_FR_LOAD_L_SV1= 20% THR_FR_LOAD_U_SV1 = 60% It is a game of trials, to find the best balance between FR (good quality) and HR (good capacity). For AMR, the algorithm is exactly the same, except that 1/ the thresholds end with "SV3" 2/ the impactis that (a) the new calls are setup in HR AND (b) the current ongoing calls are changed from FR to HR ! That's also very important to understand that. Regards, Pix