Adjusting uplink noise level (PrxNoise)Uplink noise (also known as system noise) is the sum of all stationary noise, not just thermal noise. It is very important that the uplink noise is estimated accurately, as it has a direct effect on the capacity of the cell in question. Uplink noise can either be set to a fixed value at the radio network planning stage, or allowed to fluctuate according to the current conditions, with the help of an autotuning algorithm. The autotuning algorithm of Uplink noise level (PrxNoise) can be switched on or off on a cell-by-cell basis using the management parameter PrxNoise autotuning allowed (prxnoiseautotuning).Naturally, the uplink noise level can only be measured when the cell is unloaded, or under a very low load. Therefore, the updating of uplink noise is dependent onPrxUnloaded measurements. When the cell is unloaded, PrxTotal is the same as PrxUnloaded. The cell is considered to be unloaded when the following conditions controlled with a PRFILE parameter are met:

if Bit9 of the 007:0283 PRFILE parameter is set to 1:LRT ≤ 0.02 ANDLNRT ≤ 0.01 AND NoEDCHUsersInCell

Variable Description

LRT uplink load factor for own cell RT-users (admission control estimates)

LNRT uplink load factor for own cell NRT-users (packet scheduler estimates)

Table 49:  Description of Own cell variables

if Bit9 of the 007:0283 PRFILE parameter is set to 0:no calls of the CELL_DCH state in the cell

When the conditions of the PrxNoise adjustment have been triggered, the BTS-specific load control delays the initiation of the function. The length of the delay is equal to:

the value of the RRIndPeriod management parameter in the NB/RSxxx cell - applies only to IPA-RNC and mcRNC products

the value of the PrxTotalReportPeriod management parameter in the WBTS cell

When adjusting the PrxNoise, the BTS-specific load control ensures that the own cell and the other cells of the BTS that have the same UL frequencies as the own cell are unloaded.When Uplink noise level (PrxNoise) is updated based on the autotuning algorithm, the target threshold parameter (Target for received power (PrxTarget) and overload threshold parameters (Target for received power (PrxTarget)+Offset for received power (PrxOffset)) are NOT changed, because they are fixed with respect to Uplink noise level (PrxNoise) (that is, a certain number of dBs over Uplink noise level (PrxNoise)).

When HSUPA is in use in the cell, the RNC does not update the result of the PrxNoise autotuning algorithm more than once per 10 seconds. 10 seconds is the fixed minimum interval and it cannot be controlled with any configuration parameter. In this case PrxNoise is also updated to the BTS and the limitation is set to restrict the frequency of the NBAP update procedures.Uplink noise level (PrxNoise) autotuning algorithm

PrxNoiseRNP (-105 dBm)  is an original noise threshold (PrxNoise) set by the operator and it is unaffected by the autotuning algorithm. This threshold is used by the radio resource management algorithms (admission control, load control, and the packet scheduler) in cases where adjusting the value of PrxNoise (by means of autotuning) is not allowed.PrxNoiseAdj is the threshold adjusted by the autotuning algorithm. This threshold is used by the radio resource management algorithms in cases where adjustingPrxNoise is allowed.

Step 1

Provided that the adjustment of PrxNoise is allowed in the unloaded cell and that a new PrxUnloaded is measured, the algorithm starts from STEP 1. If the adjustment ofPrxNoise is no longer allowed, PrxRef(n-1) is set to be the same as PrxNoiseAdj (<=>PrxRef(0) = PrxNoiseAdj and n= 1). In STEP 1, forgetting factor β of the mean filter with forgetting factor is selected. There are separate forgetting factors for uplink and downlink adjustments.

Step 2

In STEP2, PrxRef(n) is calculated.

Step 3

In STEP3, adjustment UP is performed if PrxRef(n) exceeds PrxNoise by the amount defined by Threshold for upward adjustment of system noise (PrxNoiseOffsetUp), and adjustment DOWN is performed if PrxRef(n) is less than PrxNoise by the amount defined by Threshold for downward adjustment of system noise (PrxNoiseOffsetDown).

The algorithm presented below uses the following values:

Parameter Value

PrxNoiseRNP (PrxNoise) Range and step: -130...-50 dBm, step 0.1 dBm

-105 dBm

RT load threshold for system noise measurements (UnloadedRT)

0.02

NRT load threshold for system noise measurements (UnloadedNRT)

0.01

Threshold for upward adjustment of system noise (PrxNoiseOffsetUp)

0.1 dB

Threshold for downward adjustment of system noise (PrxNoiseOffsetDown)

-0.1 dB

Maximum adjustment step for upward adjustment of system noise (PrxNoiseStepUp)

0.3 dB

Maximum adjustment step for downward adjustment of system noise (PrxNoiseStepDown)

-0.3 dB

Forgetting factor for upward adjustment of system noise (β_up) 0.05

Forgetting factor for downward adjustment of system noise (β_down)

0.05

Table 50:  Description of PrxNoise autotuning algorithm parameters and their values

The Absolute limit in uplink noise autotuning (PrxNoiseMaxTuneAbsolute 255dB) management parameter sets the absolute limit for maximum autotuning compared to the initial value. For example, an operator sets the PrxNoise initial value to -101.5 dBm, and the Absolute limit in uplink noise autotuning (PrxNoiseMaxTuneAbsolute) parameter to the value 2 dB. This keeps the value of PrxNoiseadj between -99.5 dBm and -103.5 dBm. Limitation is needed because environment noise can be lower or higher (for example, a radar beam is occasionally directed towards a cell when measurement is ongoing). This kind of sporadic electromagnetic interference usually lasts for a very short time and is enough to seriously distort PrxNoise.

If the value of the management parameter(PrxNoiseMaxTuneAbsolute) is modified online, then the value of the autotuned noise power NRref is set to the following value:

NRref := MIN[MAX(NRef, PrxNoise - PrxNoiseMaxTuneAbsolute), PrxNoise + PrxNoiseMaxTuneAbsolute]

The value of the management parameter PrxNoiseMaxTuneAbsolute is configured by the operator at the cell level, and is read from the WAC object identified with the management parameter WACSetIdentifier.#STARTPrx_ref(0):=PrxNoiseRNP (-105 dBm)Prx_NoiseAdj:=PrxNoiseRNP (-105 dBm)n:=1

# RADIO RESOURCE INDICATION received.IF (PrxNoise adjustment not allowed in the unloaded cell or PrxTotal < -110 dBm or PrxTotal > -50 dBm) THENPrx_ref(0):=PrxNoiseAdjn:=1

ELSE

PrxUnloaded:=PrxTotal#STEP_1IF PrxUnloaded ≥ PrxNoiseAdj (-105 dBm (n=1),-104.7(n=2)) THENβ:=β_UPELSEβ:=β_DOWNENDIF#STEP_2Prx_ref(n):=β*PrxUnloaded+(1–β)*Prx_Ref(n-1)Prx_ref(1):=0.05*PrxUnloaded+(1–0.05)*(-105dBm)=0.05*(-85)+0.95*(-105)=-104Prx_ref(1):=0.05*PrxUnloaded+(1–0.05)*(-104.7dBm)=-103.715Prx_ref(1):=0.05*PrxUnloaded+(1–0.05)*(-104.4dBm)=-103.43#STEP_3IF (Prx_ref(n)) ≥ PrxNoiseAdj + PrxNoiseOffsetUP THENAdjStepUp:=MIN(((Prx_ref(n))— PrxNoiseAdj), PrxNoiseStepUP)PrxNoiseAdj:=PrxNoiseAdj + AdjStepUp (n=1:-105+0.3=-104.7 dBm, -104.4)Prx_ref(0):=PrxNoiseAdj (-104.7 dBm, -104.4)n:=1ELSE IF Prx_ref(n)) ≤ PrxNoiseAdj + PrxNoiseOffsetDown THENAdjStepDown:=Max(((Prx_ref(n) - PrxNoiseAdj), PrxNoiseStepDown)PrxNoiseAdj:=PrxNoiseAdj + AdjStepDownPrx_ref(0):=PrxNoiseAdjn:=1ELSEn:=n+1ENDIF

ENDIFConsider that the PrxNoise autotuning algorithm is activated with the parameter prxnoiseautotuning and that NRref is the current value of the adjusted PrxNoise. If the adjustment of PrxNoise is not allowed because the cell is in the traffic load, and the RTWP value measured and reported by the BTS (as described in Load control filters out short-term spikes of measured received wideband interference power) is smaller than the NRref value, the BTS-specific LC sets NRref to the new value:NRref = MAX (RTWP, PrxNoise)

PrxNoise is the value of the PrxNoise management parameter.