Transcript IoT Std (in dB)

EVM Definition Analysis: Supporting Document for C80216m10/0616
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number: IEEE S802.16m-10/0689
Date Submitted:
2010-05-05
Source:
Rongzhen Yan, Yang-seok Choi
Tom Harel, Hujun Yin, Amir Rubin, Jin Fu and Rui Huang
Intel Corporation
E-mail: [email protected]
Venue:.
RE: Comments on P802.16m/D5
Purpose:
EVM definition and requirement for IEEE 802.16m
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contained herein.
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EVM Definition/Requirement Background
• Current 16m text of EVM: reference to 802.16-2009 section 8.1.8.2.3:
– It is EVM definition and limitation for WirelessMAN-SC, not for OFDM/OFDMA;
– The definition don’t consider the impaction of EVM noise on modulated tone and unmodulated tones;
• 16e EVM Definition/Requirement in 8.4.13.3:
– The limitation in Table 544 was derived from very simply rule, the impaction of EVM
noise for capacity loss is not studied;
– The EVM noise on modulated and un-modulated tones, are evaluated and limited
separately. It is not appreciated because EVM noise on un-moudulated will be changed
according to the ratio of occupied bandwidth for modulated tones;
– For highest modulation in uplink, 64 QAM, is low possibility to used in full Tx power,
so, the test condition of power reduction comparing to the maximum Tx power, which is
not addressed;
Agenda
• EVM Noise Study and Equation Derivation
• EVM Basic Requirements by LLS Result
• Power Reduction Study for Uplink EVM Test
EVM Noise Study
• Rapp is selected as PA model for distortion study, parameters setting:
•
•
•
Saturation Power: 31 dBm
Maximum V = 3.3 v
Rapp P = 2 or 3
Rapp Example: Vsat = 3.3 v
4
3
 V
1   in
  Vsat

2



2P




1
2P
Rapp P=2
Rapp P=3
Rapp P=30
1
Output Voltage
Vout 
Vin
0
-1
-2
• Permutation for the study:
– 16m Uplink CRU
– 16m Uplink DRU
-3
-4
-5
-4
-3
-2
-1
0
Input Voltage
1
2
3
4
5
EVM Noise Distribution
• EVM Noise will be distributed into
Modulated Tones
Un-modulated Tones
Guard Band
OOBE
-50
• EVM Noise Definition:
LP
ErrorRMS 
2
Nf

2
2
0
j 1 kS
0
 I (i, j, k )
LP
i 1
j 1 kS
0
-60
-70
-80
-90
– On Modulated Tones (16e Equation)
 I (i, j, k )  I (i, j, k )  Q(i, j, k )  Q (i, j, k ) 
1
Nf
min spectrum
average spectrum
max-hold spectrum
FCC mask
-40
 xx(f) [dBm/Hz]
–
–
–
–
Spectral density and masks. TX power = 29.18
-30
2
 Q0 (i, j, k )2
-100
-110
-30
-20
-10
0
10
Frequency [MHz]

– On Un-Modulated tones (16e Equation)
  I (i, j, k )
LP
ErrorRMS
2
1

Nf
Nf

i 1
j 1 kSu
LP
 I (i, j, k )
j 1 kS
0

2
 Q (i , j , k ) 2
2
 Q0 (i, j, k )2

– Sum of the in-band EVM noise:
ErrorRMS  ErrorRMS ( Modulated)  ErrorRMS (Un modulated)
2
2
2
– EVM Noise in OOB is limited by spectral mask, don’t need to be
limited by EVM requirement.
20
30
EVM Noise Study – Case 1: Uplink CRU
•
16m Uplink CRU example: one subband assigned @ subband #2, other parameters:
•
•
•
•
Rapp P = 2
Noise on modulated tones and un-modulated tones is studied
EVM: SUM = -9.56, Modulated = -11.64, Un-Modulated = -13.75
EVM noise feature on modulated tones, AWGN can be assumed:
1000
1000
800
800
600
600
400
400
200
200
0
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
Real Part EVM on Modulated Tones
0.6
0
-1
0.8
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
Imagine Part EVM on Modulated Tones
0.6
0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Real Part EVM on UnModulated Tones - Adjacent Subband
0.8
EVM noise feature on un-modulated tones, obviously, no white:
EVM Noise Power Distribution for Localized Allocation
16m LLRU - 1000 Symbols Statistics - Rapp2
0.09
3000
0.08
2500
0.07
2000
0.06
EVM Noise Per Tone Distribution
EVM Noise Average per Subband
0.05
Histogram
Normalized EVM Noise Power
•
16m LLRU - 1000 Symbols Statistics - Rapp2
1200
Histogram
Histogram
16m LLRU - 1000 Symbols Statistics - Rapp2
1200
0.04
1500
1000
0.03
0.02
500
0.01
0
0
100
200
300
400
500
Tone Index
600
700
800
900
0
-0.8
EVM Noise Study – Case 1, Cont.
• 100% load is assumed and each AMS has been assigned for one subband
crossing the whole band. The generated EVM noise is accumulated with
same weight:
EVM Noise Power Distribution for Localized Allocation, 100% Load
0.12
Normalized EVM Noise Power
0.11
0.1
0.09
EVM Noise Per Tone Distribution
EVM Noise Average per Subband
0.08
0.07
0.06
0.05
0
100
200
300
400
500
Tone Index
600
700
800
900
• So, the accumulated EVM noise from all AMS still can be assumed as
AWGN.
EVM Noise Study – Case 1, Cont.
• Different rates of modulate vs. un-modulated are studied, and results are
summarized:
Assigned Band
(subband)
Offset
(subband)
EVM
(Modulated)
EVM
(Unmodulated)
Mod vs. Un-Mod EVM Noise Ratio
per Subcarrier (dB)
1
1
-11.6404
-13.7560
12.52
2
1
-11.6039
-14.2465
10.42
4
1
-11.5718
-14.9812
8.18
8
1
-11.5736
-16.9309
2.34
12
0
-11.5538
N/A
N/A
1
6
-11.6685
-13.8978
13.20
2
5
-11.6438
-13.8856
10.03
4
4
-11.5486
-13.9439
7.17
8
2
-11.5624
-16.6926
2.12
• Obviously, we can see that:
•
EVM noise on un-modulated tones cannot be ignored;
•
But, the limitation by 16e un-modulated equation is not suitable: it will be changed greatly
due to assigned band percentage of whole band.
EVM Noise Study – Case 2: Uplink DRU
•
16m Uplink Distributed example:
•
•
•
•
4 DLRU assigned, Tx Power = ~27.25 dBm, EVM = ~15.4 dB (sum)
Rapp P = 2
Noise on modulated tones and un-modulated tones is studied
EVM: SUM = -16.98, Modulated = -23.43, UnModulated = -18.10
Obviously, EVM noise on modulated tones can be assumed as AWGN:
700
700
600
600
500
500
400
400
300
300
200
200
100
100
0
-0.4
-0.3
-0.2
-0.1
0
0.1
Real Part EVM on UnModulated Tones
0.2
0
-0.4
0.3
-0.3
-0.2
-0.1
0
0.1
Imagine Part EVM on UnModulated Tones
0.2
0.3
Also, the EVM noise on un-modulated tones can be assumed as AWGN:
16m LLRU - 1000 Symbols Statistics - Rapp2
16m LLRU - 1000 Symbols Statistics - Rapp2
1800
1800
1600
1600
1400
1400
1200
1200
Histogram
Histogram
•
16m DLRU - 500 Symbols Statistics - Rapp2
800
Histogram
Histogram
16m DLRU - 500 Symbols Statistics - Rapp2
800
1000
800
1000
800
600
600
400
400
200
200
0
-0.4
-0.3
-0.2
-0.1
0
0.1
Real Part EVM on UnModulated Tones
0.2
0.3
0
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
Imagine Part EVM on UnModulated Tones
0.3
0.4
EVM Noise Study – Case 2, Cont.
• Different rates of modulate vs. un-modulated are studied, and results are
summarized:
Assigned
DLRU Num.
EVM
(Modulated)
EVM
(Unmodulated)
Mod vs. UnMod EVM Noise
Ratio per Subcarrier (dB)
1
-20.7584
-18.0257
13.99
2
-23.0256
-18.2187
8.81
4
-23.5273
-18.1345
5.02
8
-23.4201
-18.3091
1.88
16
-21.3967
-19.1258
0.74
32
-18.9053
-21.9739
0.05
48
-17.2001
N/A
N/A
• Obviously, we can see that:
•
Also, EVM noise on un-modulated tones cannot be ignored: even higher than EVM noise
on modulated tones.
•
But, the limitation by 16e un-modulated equation is not suitable: it will be changed greatly
due to assigned band percentage of whole band.
• Summary:
EVM Noise Study Summary and
EVM Equation Derivation
– AWGN assumption is acceptable for EVM noise on both modulated tones and unmodulated tones;
– EVM noise on un-modulated tones cannot be ignored.
• So, we set the modeling assumptions:
•
•
Total EVM noise:
Mt = Mm + Mum
Mm is the total EVM noise on modulated tones
Mum is the total EVM noise on un-modulated tones
For K numbers of AMS are assigned for 1/K resource of total available band with same
permutation (localized or distributed); All AMS has same EVM values and similar
received RSS at ABS side. We can get total capacity:
K
CTotal  
i 1

S i, j  
B

log
1




s
2


M
i
,
j

N
jBK ( i )


i is the AMS index, j is subcarrier belong to AMS i bandwidth BK (i )
S i, j  is received signaling strength
M i, j  is EVM noise strength
N
Bs
is all other noise in the receiver (exclude EVM noise)
is the bandwidth of one subcarrier
Here, we assume EVM noise generated by all AMS are same feature, we can get:
M (i , j ) 
Mm
M um
( M m  M um )
Mt
 ( K  1) 


B/K
B  ( K  1) / K
B/K
B/K
and, we assume the received signaling strength is same: S i, j   S








B
S
S
  B  log2 1 

   log2 1 
M
M
t
t


i 1 K
 N 
 N 
B/K
B/K




K
CTotal
If 5% throughput loss is assumed because of EVM noise, we can get:




S
S

  0.95  B  log2 1  
B  log2 1 
Mt
 N

 N 
B/K


1
0.95


Mt
S
N


 1    1 

S  B / K   N 
S

becauseS  B / K is the total reference signal power on modulated tones, we can get suitable
EVM definitionas :
EVM Lin 
EVM Noise on Modulated Un modulated Tones
Re ference Signal Power on ModulatedTones
And we can get 5% throughput loss condition, EVM vs. working SNR
relationship:


1

1 
0.95

EVM Re quired  10log10 1  SNRLin   1 
SNRLin 

EVM Curve for 5% Throughput Loss
-5
-10
EVM Requirement (dB)
-15
-20
-25
-30
-35
-5
0
5
10
15
Working Instantaneous SNR (dB)
20
25
30
EVM Equation Definition
•
By the study, we can define the EVM noise equation by the sum of EVM noise in
modulated and un-modulated tones (same naming style of 16e):


 1
EVM  10log10
N
 f









I
(
i
,
j
,
k
)

I
(
i
,
j
,
k
)

Q
(
i
,
j
,
k
)

Q
(
i
,
j
,
k
)


LS
Nf

i 1
j 1 kS  Su
2
2
0
 I (i, j, k )
LP
j 1 kS
0
0
2
 Q0 (i, j, k )
2




Where:
N f is the number of frames for the measurement;
LS is the number of symbols used for the measurement;
S is the group of modulated data subcarriers;
Su is the group of un-modulated data subcarriers. It includes all subcarriers in
the range 0 … Nused – 1, except the DC and the modulated subcarriers (in S);
I0 (i, j, k ), Q0 (i, j, k ) denotes the ideal symbol point in the complex plane. It is set as (0,
0) in the un-modulated data subcarriers.
I (i, j, k ), Q(i, j, k ) denotes the observed point of the i-th frame, j-th OFDMA symbol,
k-th subcarrier in the complex plane;
Agenda
• EVM Noise Study and Equation Derivation
• EVM Basic Requirements by LLS Result
• Power Reduction Study for Uplink EVM Test
Uplink LLS Simulation Setting
For EVM Requirements, we needs to get the working SNR of each
modulation, so we perform uplink LLS for:
• Channel Model: eITU-PedB 3km/h
• Uplink Data Transmission Configuration:
•
•
•
•
Single stream SIMO: 1 Tx, 2 Rx (spacing 0.5 wavelength), MRC receiver.
Channel Estimation: MMSE
Permutation: 16m DRU
Data Burst Size: 3 subframes x 4 DRUs
• HARQ: disabled
Uplink LLS for 1x2, eITU-PedB, DRU, QPSK
10
10
10
eITU-PedB, 3km/h, 16m UL LLS, QPSK, DRU
0
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
-1
R=0.0992
R=0.1071
R=0.123
R=0.1429
R=0.1587
R=0.1746
R=0.1984
R=0.2262
R=0.254
R=0.2817
R=0.3175
R=0.3571
R=0.3968
R=0.4524
R=0.5079
R=0.5754
R=0.6508
R=0.7183
-2
-10
-5
0
5
10
15
20
• The maximum SNR of QPSK at 30% PER is ~6 dB.
• The EVM requirement should be -16 dB
Uplink LLS for 1x2, eITU-PedB, DRU, 16QAM and 64QAM
10
10
10
eITU-PedB, 3km/h, 16m UL LLS, 16QAM and 64QAM, DRU
0
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
-1
R=0.4067,
R=0.4623,
R=0.5198,
R=0.5774,
R=0.6508,
R=0.4868,
R=0.5503,
R=0.6243,
R=0.6984,
R=0.7937,
R=0.8677,
Modul 4
Modul 4
Modul 4
Modul 4
Modul 4
Modul 6
Modul 6
Modul 6
Modul 6
Modul 6
Modul 6
-2
0
5
10
15
20
25
30
35
40
• The maximum SNR (30% PER) of 16QAM is 11 dB, so the
EVM requirement is -19 dB
• The midpoint of 64QAM is 17dB, so the EVM requirement is
-24 dB
Downlink LLS Simulation Setting
Basic settings to derive the downlink working SNR range:
• Channel Model: eITU-PedB 3km/h
• Downlink Data Transmission Configuration:
•
•
•
•
2 Tx, 2 Rx, SFBC, Rate = 1
Channel Estimation: MMSE
Permutation: 16m DRU
Data Burst Size: 4 subframes x 4 DRUs
• HARQ: disabled
DL LLS for 2x2 SFBC, eITU-PedB, DRU, QPSK
10
10
10
0
eITU-PedB, 3km/h, 16m Downlink LLS, SFBC 2x2, QPSK, DLRU
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
-1
-2
-10
-5
0
5
R=0.0651
R=0.0703
R=0.0807
R=0.0938
R=0.1042
R=0.1146
R=0.1302
R=0.1484
R=0.1667
R=0.1849
R=0.2083
R=0.2344
R=0.2604
R=0.2969
R=0.3333
R=0.375
R=0.4271
R=0.4688
10
• The maximum SNR of QPSK at 30% PER is ~0 dB.
• The EVM requirement should be -11 dB
DL LLS for 2x2 SFBC, eITU-PedB, DRU, 16QAM and 64QAM
eITU-PedB,
3km/h, 2x2 SFBC, 16m Downlink LLS, 16QAM and 64QAM, DRU
0
10
10
10
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
CTC,
-1
R=0.2656,
R=0.3021,
R=0.3438,
R=0.3854,
R=0.4271,
R=0.3194,
R=0.4097,
R=0.4583,
R=0.5208,
Modul 4
Modul 4
Modul 4
Modul 4
Modul 4
Modul 6
Modul 6
Modul 6
Modul 6
-2
0
5
10
15
20
25
30
• The maximum SNR (30% PER) of 16QAM is 4.5 dB, so the EVM
requirement is -15 dB
• The maximum SNR (30% PER) of 64QAM is 11dB, so the EVM
requirement is -20 dB
EVM Requirements Summary
• LLS Results Summary:
– Uplink EVM Requirement for QPSK, 16 QAM, 64 QAM
(1x2 SIMO) is: -16, -19, -24 dB
– Downlink EVM Requirement for QPSK, 16 QAM, 64
QAM (2x2 SFBC) is: -11, -15, -20 dB
• Recommendation:
– Because downlink (ABS) implementation is less
sensitive for higher EVM requirement, for the
simplification, we can set downlink EVM
requirement as same as uplink, for higher
downlink performance.
Agenda
• EVM Noise Study and Equation Derivation
• EVM Basic Requirements by LLS Result
• Power Reduction Study for Uplink EVM
Test
Modulation vs. Tx Power Study
• In 16m uplink transmission, because of uplink power control, the modulation
is related to uplink Tx power level.
• Uplink SLS Scenario for evaluation: IEEE 802.16m PCLA DG evaluation
setting:
Parameter
Value
Parameter
Value
Carrier frequency (GHz)
2.5 GHz
Site to site distance (m)
500m
10 MHz
Channel
eITU-Ped B, 3km/h
Reuse factor
1
Max power in MS (dBm)
23dBm
Frame duration
(Preamble+DL+UL)
5ms
Antenna Config
1x2 SIMO
Number of OFDM
symbols in UL Frame
18
HARQ
On (Max retrans: 4/Sync)
FFT size (tone)
1024
Target PER
0.2
Useful tone
864
Link to system mapping
RBIR
Number of LRU
48
Scheduler type
PF
LRU type
DRU
Resource Assignment Block
8 LRU
Number of users
per sector
10
Penetration loss (dB)
20dB
CMIMO support
no
Control Overhead
0 for SE calculation (not
defined yet)
System bandwidth (MHz)
Tx Power vs. Modulation CDF
Tx power distribution for different values of for all modulations
1
0.9
0.9
0.8
0.5
0.4
0.7
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
-80
-60
-20
0
20
Tx power (in dBm)
Tx power distribution for different values of for QPSK
-40
0
-80
40
1
0.9
0.9
=0
=0.2
=0.4
=0.6
=0.8
=1
=1.2
=1.4
0.6
0.5
0.4
-20
0
Tx power (in dBm)
20
40
0.7
=0.2
=0.4
=0.6
=0.8
=1
=1.2
=1.4
0.6
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0
-80
-40
0.8
CDF
0.7
-60
Tx power distribution for different values of for 64QAM
1
0.8
=0
=0.2
=0.4
=0.6
=0.8
=1
=1.2
=1.4
0.6
CDF
0.6
CDF
0.8
=0
=0.2
=0.4
=0.6
=0.8
=1
=1.2
=1.4
0.7
CDF
Tx power distribution for different values of for 16QAM
1
0.1
-60
-40
-20
0
Tx power (in dBm)
20
40
0
-70
-60
-50
-40
-30
-20
Tx power (in dBm)
-10
0
10
20
30
Typical gamma value selection
•
According to the all gamma value results, we can get:
•
•
•
•
QPSK/16QAM has high percentage of full power transmission; the test under full Tx power is necessary;
64 QAM has very low percentage of full power transmission, which is potential test under power reduction (vs. full
power)
But how much power reduction for 64 QAM is suitable?
Different gamma values (as control parameter of power control) will produce
different IoT distributions:
IoT Distribution for different values of
1
gamma
IoT mean
(in dB)
IoT Std
(in dB)
0.0
5.5069
1.0959
0.2
5.7500
1.0982
0.4
6.6577
1.0503
0.6
7.7271
1.0501
0.8
9.0305
1.0654
0.2
1.0
10.6258
1.2287
0.1
1.2
12.3736
1.4547
0
1.4
13.5477
1.5246
0.9
0.8
0.7
=0
=0.2
=0.4
=0.6
=0.8
=1.0
=1.2
=1.4
CDF
0.6
0.5
0.4
0.3
0
5
10
IoT (in dB)
15
20
Power Reduction of 64 QAM Study
• Considering the performance and IoT requirement (<10 dB), the Gamma
value 0.4 ~ 0.8 will be typically adopted values for the power reduction
study.
• We study the CDF 5% power of 64 QAM Tx power distribution:
gamma
IoT mean
(in dB)
Tx Power @ 5% CDF (dBm)
0.2
5.7500
7.8
0.4
6.6577
13.3
0.6
7.7271
17.9
0.8
9.0305
19.7
1.0
10.6258
21.9
1.2
12.3736
23.0
1.4
13.5477
23.0
•
If we consider the average power reduction of gamma value 0.4~0.8, it will be 6 dB;
•
If we consider the maximum gamma value to control IoT less than 10 dB, it will be
2~3 dB;
•
So, we set it as 3 dB as trade off value.
Summary of Minimum 16m EVM Requirement
• Downlink EVM Requirement:
Unit
Parameter
QPSK or BPSK
16QAM
64QAM
•
dB
dB
dB
Required EVM
Level (dB)
-16
-19
-24
Uplink EVM Requirement:
Unit
Parameter
QPSK or BPSK
16QAM
64QAM
dB
dB
dB
Required EVM
Level (dB)
-16
-19
-24
Power
Reduction (dB)
0
0
3