Huawei Technologies Co., LTD
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Release history
Date Version Description Author
20141104 V1.00 Draft Muhammed Adel
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 (MHz) 20 15 10 5 3 1.4 Occupied Subcarriers 1200 900 600 300 180 72 # RB 100 75 50 25 15 6 ii.
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 Modulation Order
QPSK 2
16 QAM 4
64 QAM 6
MCS = Modulation & Coding Scheme , which represent the combination of Modulation Scheme & Coding Rate
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.)
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-SCH transport block bits received within a TTI
Maximum number of bits of a DL-SCH transport block received within a TTI
Category 2 51024 51024 Category 3 102048 75376 Category 4 150752 75376 Category 5 299552 149776 UL UE Category Maximum number of bits of an UL-SCH transport block transmitted within a TTI
Support for 64QAM in UL Category 1 5160 No Category 2 25456 No Category 3 51024 No Category 4 51024 No Category 5 75376 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
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
=（168000-16000-8000-288-264）*(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)*1000/10-43200）*6*0.93/1024/1024=74.8671Mbps
3.
Huawei LTE Throughput KPi’s
KPI Unit HW Formula Dl_Data_Volume GByte/ s L.Thrp.bits.Dl/8/1000/1000/1000 UL_Data_Volume GByte/ s L.Thrp.bits.UL/8/1000/1000/1000 Avg Dl_USER_THP Kbit/s
(L.Thrp.bits.Dl-L.Thrp.bits.Dl.LastTTI)/L.Thrp.Time.Dl.RmvLastTTI 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
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)