LTE FDD Throughput Calculations

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LTE FDD Throughput Calculations

Huawei Technologies Co., LTD

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Description

Author

20141104

V1.00

Draft

Muhammed Adel

2015-02-27

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Contents

1. LTE Basics concepts 2. FDD System Throughout Calculations 3. LTE Throughput KPI’s & Huawei Formula’s 4. References

1. LTE System Basics Concepts i. LTE System Bandwidth System BW

20

15

10

5

3

1.4

1200

900

600

300

180

72

100

75

50

25

15

6

(MHz)

Occupied Subcarriers # RB

ii. LTE Modulation schemes & Coding Rate (MCS) 2015-02-27

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

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According to 3GPP Protocol , LTE support 3 Modulation Scheme 64 QAM , 16 QAM & QPSK



M = Modulation order is the number of bits transmitted over each symbol Modulation Scheme QPSK 16 QAM 64 QAM

Modulation Order 2 4 6



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

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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 vertis ical 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.)

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 codeword reuse ratio, MIMO mode

codeword reuse ratio

2×2

2

4×4

4

MU-MIMO

iii. 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-

Maximum number of bits

SCH transport block bits

of a DL-SCH transport

received within a TTI

block received within a TTI

Category 1 2015-02-27

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Category 2

51024

51024

Category 3

102048

75376

Category 4

150752

75376

Category 5

299552

149776

Maximum number of UL UE Category

bits of an UL-SCH

Support for 64QAM in

transport block

UL

transmitted within a TTI

Category Category Category Category Category

1 2 3 4 5

5160 25456 51024 51024 75376

No No No No Yes

2. FDD System Throughout Calculations  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. 

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

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 2015-02-27

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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 6RBs in the middle)-24(PBCH share with RS)=264 

Throughput-DL =（168000-16000-8000-288264）*(1000ms/10(10ms/frame))*6（64QAM）*2（2x2MIMO）*0.93/10 24/1024=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)*1000/1043200）*6*0.93/1024/1024=74.8671Mbps

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3. Huawei LTE Throughput KPi’s KPI

Unit

HW Formula

Dl_Data_Volume

L.Thrp.bits.Dl/8/1000/1000/1000

Avg Dl_USER_THP

GByte/ s GByte/ s Kbit/s

Avg UL_USER_THP

Kbit/s

L.Thrp.bits.Ul /L.Thrp.Time.Cell.Ul.HighPrecision

Avg Dl_Cell_Thp

Kbit/s

L.Thrp.bits.DL /L.Thrp.Time.Cell.DL.HighPrecision

Avg UL_Cell_Thp

Kbit/s

L.Thrp.bits.UL /L.Thrp.Time.Cell.UL.HighPrecision

UL_Data_Volume

L.Thrp.bits.UL/8/1000/1000/1000 (L.Thrp.bits.DlL.Thrp.bits.Dl.LastTTI)/L.Thrp.Time.Dl.RmvLastTTI

4. 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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