NR_PRACH_Power_Calculator

Author: Dustin_Chen, email: Dustin_Chen@compal.com or chuhpsdustin@gmail.com

• 3GPP spec
  • ETSI TS 38.213 chap 7.4 Physical random access channel
    • P_PRACH = min{P_CMAX, P_PRACH,target + PL} [dBm]
  • ETSI TS 38.321 chap 5.1.3 Random Access Preamble transmission
    • set PREAMBLE_RECEIVED_TARGET_POWER to preambleReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_POWER_RAMPING_COUNTER – 1) × PREAMBLE_POWER_RAMPING_STEP;
  • ETSI TS 38.211 V16.2.0 Table 6.3.3.2-3: Random access configurations for FR1 and unpaired spectrum.
  • ETSI TS 38.321 Table 7.3-1: DELTA_PREAMBLE values for long preamble formats. (Preamble format 0~3)
  • ETSI TS 38.321 Table 7.3-2: DELTA_PREAMBLE values for short preamble formats. (Preamble format A1/A2/A3/B1/B2/B3/B4/C0/C2)

  prach-ConfigurationIndex Range	Preamble Format	DELTA_PREAMBLE
  0-27	0	0
  28-33	1	-3
  34-39	2	-6
  40-66	3	0
  67-86	A1	8 + 3 × μ
  87-109	A2	5 + 3 × μ
  110-132	A3	3 + 3 × μ
  133-144	B1	8 + 3 × μ
  145-168	B4	3 × μ
  169-188	C0	11 + 3 × μ
  189-210	C2	5 + 3 × μ
  211-225	A1/B1	8 + 3 × μ
  226-240	A2/B2	5 + 3 × μ
  241-255	A3/B3	3 + 3 × μ
  256-262	0	0

• Enter the following parameters and press "Calculate" to get the PRACH power
  • preambleReceivedTargetPower (from SIB1):
    
  • prach-ConfigurationIndex (from SIB1):
    
  • μ (from SIB1 msg1-SubcarrierSpacing):
    
  • RACH Attempt:
    
  • powerRampingStep (from SIB1):
    
  • Pathloss (from ss-PBCH-BlockPower-RSRP):
    
  Calculate

==============================================================================================================================
【Example】
PPRACH power
= P_PRACH,target + Pathloss
= （preambleReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_POWER_RAMPING_COUNTER – 1) × PREAMBLE_POWER_RAMPING_STEP） + （referenceSignalPower – higher layer filtered RSRP）
= （preambleReceivedTargetPower + DELTA_PREAMBLE + (RACH Attempt – 1) × powerRampingStep） + （ss-PBCH-BlockPower – RSRP）
= （-60 +  3×1 + （1-1）*2） + (-15 - (-49))
= -23 dbm

// RSRP=-49
07:59:43.416	[0xB97F]	NR5G ML1 Searcher Measurement Database Update Ext
      -----------------------------------------------------------------------------------------------------------------------------------------
      |   |      |      |     |            |            |Detected Beams                                                                       |
      |   |      |      |     |            |            |   |     |RX Beam Info           |NR2NR       |NR2NR       |L2NR        |L2NR        |
      |   |      |PBCH  |Num  |Cell Quality|Cell Quality|   |SSB  |RX Beam|               |Filtered Tx |Filtered Tx |Filtered Tx |Filtered Tx |
      |#  |PCI   |SFN   |Beams|RSRP        |RSRQ        |#  |Index|Id     |RSRP           |Beam RSRP L3|Beam RSRQ L3|Beam RSRP L3|Beam RSRQ L3|
      -----------------------------------------------------------------------------------------------------------------------------------------
      |  0|     1|   778|    1|     -49.461|     -10.445|  0|    0|     NA|        -49.461|     -49.461|     -10.445|          NA|          NA|
      |   |      |      |     |            |            |   |     |     NA|        -51.133|            |            |            |            |

// SIB1 prach-ConfigurationIndex=148, msg1-SubcarrierSpacing kHz30
1980/03/16 07:59:43.496	[0xB821]	BCCH_DL_SCH / SystemInformationBlockType1
                  rach-ConfigGeneric 
                  {
                    prach-ConfigurationIndex 148, //format B4, DELTA_PREAMBLE = 3×μ。Ref: 38 321. Table 7.3-2: DELTA_PREAMBLE values for short preamble formats. 
                    msg1-FDM one,
                    msg1-FrequencyStart 0,
                    zeroCorrelationZoneConfig 6,
                    preambleReceivedTargetPower -60,
                    preambleTransMax n10,
                    powerRampingStep dB2,
                    ra-ResponseWindow sl80
                  },
                  msg1-SubcarrierSpacing kHz30,//μ=1。
          
		  ss-PBCH-BlockPower -15 //referenceSignalPower=-15
        },
		
// RSRP=-46
07:59:43.614	[0xB97F]	NR5G ML1 Searcher Measurement Database Update Ext
      -----------------------------------------------------------------------------------------------------------------------------------------
      |   |      |      |     |            |            |Detected Beams                                                                       |
      |   |      |      |     |            |            |   |     |RX Beam Info           |NR2NR       |NR2NR       |L2NR        |L2NR        |
      |   |      |PBCH  |Num  |Cell Quality|Cell Quality|   |SSB  |RX Beam|               |Filtered Tx |Filtered Tx |Filtered Tx |Filtered Tx |
      |#  |PCI   |SFN   |Beams|RSRP        |RSRQ        |#  |Index|Id     |RSRP           |Beam RSRP L3|Beam RSRQ L3|Beam RSRP L3|Beam RSRQ L3|
      -----------------------------------------------------------------------------------------------------------------------------------------
      |  0|     1|   804|    1|     -46.281|     -10.359|  0|    0|     NA|        -46.266|     -46.281|     -10.359|          NA|          NA|
      |   |      |      |     |            |            |   |     |     NA|        -48.594|            |            |            |            |

// (803,19) PRACH, Pathloss=(-15)-(-49)=34, PRACH Transmit Power = -23
07:59:43.644	[0xB8D2]	NR5G LL1 FW MAC TX IU Power
            System Frame Number = 803
            Slot Number = 19
         }
         Power Info[0] {
            Carrier Id = 0
            Channel Type = PRACH
            PRACH Data {
               Transmit Power = -23 //PRACH Transmit Power = -23
               RACH Attempt = 1
               Pathloss = 34 // Pathloss = referenceSignalPower – higher layer filtered RSRP
               PHR MTPL = 23
               Minimum Power = -38
            }