LTE FDD Throughput Calculations

To calculate LTE FDD (Frequency Division Duplex) throughput, several technical parameters are taken into account:

  1. Bandwidth.
  2. Resource Blocks (RBs).
  3. Modulation and Coding Scheme (MCS).
  4. MIMO Configuration.
  5. LTE UE Category.

How to calculate LTE Throughput Calculation (FDD)?

  1. LTE System Basics Concepts.
  2. LTE System Bandwidth.
System BW (MHz)201510531.4
Occupied Subcarriers120090060030018072
# RB100755025156

LTE Modulation schemes & Coding Rate (MCS).

    • According to 3GPP Protocol , LTE support 3 Modulation Scheme 64 QAM , 16 QAM & QPSK
    LTE Modulation schemes & Coding Rate (MCS).

    M = Modulation order is the number of bits transmitted over each symbol.

    Modulation SchemeModulation Order
    QPSK2
    16 QAM4
    64 QAM6

    MCS = Modulation & Coding Scheme , which represent the combination of Modulation Scheme & Coding Rate.

    3GPP define 0 ~ 28 MCS for DL , and define 0 ~22 MCS for UL.

    LTE FDD Throughput Calculations

    The basis for LTE throughput calculation is the TBS specified in 3GPP TS 36.213. (The horizontal axis is the number of RBs, and the vertical axis is TBS index, or MCS.) TBS indicates the amount of data that can be transmitted at a time. (The table applies to both downlink and uplink.)

    LTE FDD Throughput Calculations

    Codeword reuse ratio is below in table shown.

    MIMO mode      Codeword Reuse Ratio.
    2×22
    4×44
    MU-MIMO 

    LTE UE Category:

    Different UE Category are having different capabilities. From 3GPP. 36.306 ,we can find the max bits supported in UL and DL (PUSCH and PDSCH respectively) for UE category as follows:

      DL UE Category.Maximum number of DL-SCH transport block bits received within a TTI.Maximum number of bits of a DL-SCH transport block received within a TTI.
    Category 110296  10296  
    Category 251024  51024  
    Category 3102048  75376  
    Category 4150752  75376  
    Category 5299552  149776  
    UL UE CategoryMaximum number of bits of an UL-SCH transport block transmitted within a TTI.  Support for 64QAM in UL.
    Category 15160No
    Category 225456No
    Category 351024No
    Category 451024No
    Category 575376Yes

    LTE FDD System Throughout Calculations.

    1. To calculate the throughput is to calculate how much bit the frame bears in one second. And we need to know how many RE is used in one second. Considering different codeword reuse in different MIMO modes and consumption of control signaling, here is how to calculate theoretic peak throughput.
    2. Throughput-DL= ([number of REs in a frame]－[number of REs occupied by RS]－[number of REs occupied by PDCCH]－[number of REs occupied by SCH]－[number of REs occupied by PBCH]）× (1000ms/10ms/frame) × [modulation efficiency] × [codeword reuse ratio] × 0.93/1024/1024.
    3. If FDD 20MHz, PDCCH takes one symbol, 2*2MIMO, normal CP, so

    [number of REs in a frame]=12(every RB takes 12 subcarriers)*7(every RB has 7 symbols)*2( 2 RBs in every subframe)*10(10 subframes in a frame)*100(20Mhz has 100 RBs)=16800

    [number of REs occupied by RS] = 16(16 RS in each subframe)*10(10 subframes in each frame)*100(100RBs in 20Mhz) = 16000

    [number of REs occupied by PDCCH] = 1 (in each subframe, PDCCH occupies 1 symbol)*(12-4)*10*100=8000

    [number of REs occupied by SCH]= 2 (primary SS occupies 2 symbols) * 2 (2 secondary SS in each frame) * 6(SCH occupies 6 RBs in the middle) * 12=288

    [number of REs occupied by PBCH] = 4 (PBCH occupies 4 symbols in each frame) * 12 * 6 (PBCH occupies 6 RBs in the middle) – 24(PBCH share with RS)= 264

    So, Throughput-DL =（168000-16000-8000-288-264）*(1000ms/10(10ms/frame))*6（64QAM）*2（2x2MIMO）*0.93/1024/1024 = 152.671776Mbps

    Throughput-UL = (([number of REs in a frame]－[number of Res occupied by DMRS]－[number of Res occupied by PUCCH])*1000/10－[number of Res occupied by prach]）×[modulation efficiency]×0.93/1024/1024

    If FDD 20MHz, PUCCH take 2 RBs, normal CP, DMRS takes 2 symbols

    [number of REs in a frame]=12*2*7*10*100=168000

    [number of REs occupied by DMRS]=2(2 DMRS in each subframe)*12*10*100=24000

    [number of REs occupied by PUCCH]=2*12*(14-2)*10=2880

    While in one second

    [number of REs occupied by prach]=6(PRACH occupies 6 RBs in the middle)*12*14-(2*6*12)(occupies the same RE with DMRS)*1000/20=43200

    So, Throughput-UL=（(168000-24000-2880)*1000/10-43200 * 6 * 0.93 / 1024 / 1024 = 74.8671Mbps.

    Huawei LTE Throughput KPI’s

      KPIUnitHW Formula
      Dl_Data_VolumeGByte/sL.Thrp.bits.Dl/8/1000/1000/1000
      UL_Data_VolumeGByte/sL.Thrp.bits.UL/8/1000/1000/1000
      Avg Dl_USER_THPKbit/s(L.Thrp.bits.Dl-L.Thrp.bits.Dl.LastTTI)/L.Thrp.Time.Dl.RmvLastTTI
      Avg UL_USER_THPKbit/sL.Thrp.bits.Ul /L.Thrp.Time.Cell.Ul.HighPrecision
      Avg Dl_Cell_ThpKbit/sL.Thrp.bits.DL /L.Thrp.Time.Cell.DL.HighPrecision
      Avg UL_Cell_ThpKbit/sL.Thrp.bits.UL /L.Thrp.Time.Cell.UL.HighPrecision

      References.

        • 3GPP ETSI TS 36.213 version 11.6.0 Release 11
        • 3GPP ETSI TS 36.211 V9.1.0 (2010-03)
        • 3GPP ETSI TS 136 306 V11.6.0 (2014-03)
        • 3900 Series Base Station_V100R008C00_06_en_31186316 Hedex

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