Training Material_Introduction to HSDPA Scheduling Algorithm
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Transcript of Training Material_Introduction to HSDPA Scheduling Algorithm
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8/10/2019 Training Material_Introduction to HSDPA Scheduling Algorithm
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Introduction to HSDPA Scheduler
-UMTS Radio Network Planning & Optimization Dept
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HSDPA Schedulers Structure
HSDPA Scheduling Algorithm
HS-SCCH Power Control Algorithm AMC Algorithm
HARQ Algorithm
HSDPA power allocation methods
HSDPA code allocation methods
The Features of HSDPA scheduler
Q&A
Contents
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HSDPA Schedulers Structure
Wireless Resource calculation
HSDPA power
calculation module
HSDPA code
calculation module
HS-SCCH power
reservation
module
Priority Calculation Module
HS-SCCH Power Control Module
CQI Adjusment Module
TFRC Module
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Scheduling Algorithm 2/8
PFit always schedules the UE which has the biggestinstantaneous throughput/mean throughput. The fairness
and throughput could be adjusted according to operators
requirement.
RRit always schedules the UE which lies in the head ofqueue, then move this scheduled UE to the last.
MAX-C/Iit always
schedules the UE which
has the largest C/I or CQI.
W1W2W3 denote
respectively the
different fairness PF
algorithm
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Scheduling Algorithm 3/8
PFRRMAX-C/I field trial result:Alog ThroughputKbpsUE1far UE2far UE3near UE4near CELLtotal
RR 361 369 841.6 836.4 2408
PF1 421.4 411.7 939.3 937.4 2709.8
PF2 308.7 322.3 1150 1120 2901
PF3 213.8 240.8 1290 1250 2994.6
PF4 164.8 184 1380 1360 3088.8
PF5 111.1 132 1490 1460 3193.1
PF6 74 90 1510 1550 3224
MaxC/I 0 0 1670 1680 3350
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Scheduling Algorithm 4/8
The figure of above data:
Throughput vs Algorithm
0
500
1000
1500
20002500
3000
3500
4000
RR
PF1
PF2
PF3
PF4
PF5
PF6
MaxC/I
Algorithm
Throughput[
kbps]
UE1
UE2UE3
UE4
CELL
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Scheduling Algorithm 5/8
GBR algorithmthis algorithm is designed to schedule I/B/S
mixture trafficit combines M-LWDF algorithm and Tokenalgorithm, it considers two QoS parameters, i.e.,GBR andDiscardTimer . The priority formula is below:
, , _ ,j j
( ) / 2Priority (n)=f(SPI )
( )j n j n Token HOL j
j
w TB TB d
r n DiscardTime jf(SPI ) : denots the j users weight of different
Scheduling Priority Indicator.
,( )j nw TB :adjusts the fairness and throughput through it.
,j nTB :denotes the instantaneous throughput.
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Scheduling Algorithm 6/8
( )j
r n
:denotes the mean
throughput of j user.
_ ,Token HOL nd
:denotes the delay of j users virtual token.Its input and output is described as figure
below.
Token barrel
GBR
UE data
rate
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Scheduling Algorithm 7/8
Simulation result of GBR algorithm: in case of below 5%
unsatisfied user probability, cell throughput is about1.3Mbps, about 10~11 UE with 128kbps GBR service.
1200 1400 1600 1800 2000 2200 2400 2600
0
5
10
15
20
25
30
35
40
45
50
HS-DSCH throughput [kbps]
Unsatisfied
userprobability[%]
cell layout:19cell,57sector;3km velocity,UE uniform distribution,14codes and 65% HSDPA power
GBR=128Kbps;DiscardTimer=4 second
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Scheduling Algorithm 8/8
The characteristic of GBR algorithm:
Soft priority adjustment: when UE data rate decreases to
below GBR, scheduler increases gradually the UEs
priority, it can obtain more bigger multiuser diversity gain,
i.e., support more streaming user.
Relative scheduling priority: SPI is used for indicating UEscheduling priority, first we may map SPI to a weight,
then, multiply priority formula by the weight.
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HS-SCCH Power Control Algorithm 2/6
Outer loop Inner loop
Target BLER
HSDPA UE
HS-SCCH
Node B
ACK/NACK/DTX
CQI
MPO
HS-SCCH Power control Based on CQI
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HS-SCCH Power Control Algorithm 3/6
0
4.5 CQIs
HS DSCH
E
N
0 0
MPO 8s sHSSCCH CPICH
HS SCCH HS DSCH
E EP P
N N
Inner loop power calculation:
0
= 1.2dbs
HS SCCH
E
N
HS-SCCH Power control Based on CQI
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HS-SCCH Power Control Algorithm 5/6
HS-SCCH Power control associated with DPCCH PILOT
Outer loop Inner loop
Target BLER
HSDPA UE
HS-SCCH
Node B
ACK/NACK/DTXTPC
P_HS-SCCH = P_DL-DPCCH + delta
Delta is controled by outer loop.
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The method based on CQI have a great deal ofadvantage, i.e., because CQI always denotes channel
quality, whether UE is Non-SHO or SHO (Soft HandOver) ,while DPCCH is not like that.
So HS-SCCH power control based on CQI is stronglyrecommended. The figure below is got from field trial,target mean value is 3%.
HS-SCCH Power Control Algorithm 6/6
0
2
4
6
8
10
12
1 17 33 49 65 81 97 113 129 145 161 177 193 209 225 241 257 273 289 305 321 337 353 369 385 401 417 433 449 465 481 497
1
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AMC Algorithm 1/4
AMC theory:
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AMC Algorithm 2/4
AMC(Adaptive Modulation Coding): According to
CQIMPOUE capacityavailable power andcodesdata buffer size and BLER, HSDPA
scheduler smartly selects transmission format and
allocates power/codes resources.
CQI Adjustment
Module
HS-DSCHBLER
Transmmsion
Format Selction
Aailable HS-DSCH power
Aailable HS-DSCH codes
Adjusted CQI
Power/Codes
Allocation
Data Buffer Size
MPO
AMC
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AMC Algorithm 3/4
AMC algorithms basic link level results:
Simulation condition: RAKE receiver,AWGN channel.
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AMC Algorithm 4/4
AMC Algorithms characteristic:
Steady BLER
Higher throughput and power/codes efficiency,
especially for unbalanced power and codes case,because expanded TB tables has been included.
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HARQ Algorithm 1/7
HARQ types:
HARQ type 1: the same block is retransmitted andoptimum combining at the bit level is performed. This is
Chase Combining (CC).
2.TX
P2 P1
Systematic Bits Parity Bits
1.TX
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HARQ Algorithm 2/7
HARQ types:
HARQ type 2: Full IR (FIR) with non self-decodableretransmissions allowed. Optimum combining is
performed for bits already transmitted.
2.TX
P2 P1
Systematic Bits Parity Bits
1.TX
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HARQ Algorithm 3/7
HARQ types:
HARQ type 3: Partial IR (PIR) with self-decodableretransmissions only. Optimum combining is performed for
bits already transmitted (for instance systematic bits).
2.TX
P2 P1
Systematic Bits Parity Bits
1.TX
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HARQ Algorithm 4/7
HARQ types:
For 16QAM, constellationrearrangment may be availableto balance the bit reliability.
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HARQ Algorithm 5/7
HARQ combination program:
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HARQ Algorithm 6/7
CC/PIR/FIR performance
In case of higher code rate, FIR is better than
PIR, and PIR is better than CC.
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HARQ Algorithm 7/7
RV parameter selection:
CR: code rate; CA: constellation rearrangement.
Type 1stTX 2ndTX 3rdTX 4thTX
QPSK/low
CR
0 0(CC) 0(CC) 0(CC)
QPSK/highCR 0 1(FIR) 0(CC) 0(CC)
16QAM/low
CR
0 4(CC+CA) 6(CC+CA) 5(CC+CA)
16QAM/me
dia CR
0 2(PIR+CA) 6(CC+CA) 5(CC+CA)
16QAM/hig
h CR
0 3(FIR+CA) 6(CC+CA) 5(CC+CA)
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HSDPA power allocation methods
HSDPA and R99 share the total power.
In case of dynamic HSDPA power,Margin power may be about
2%, i.e., 98% cell total power may be used in ZTE system.
Dynamic HSDPA power Static HSDPA power
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HSDPA code allocation methods
RNC dynamic code allocation
Black ring: Common Channel codes
Blue ring: R99 codes
Pink ring: HSDPA codes
SF=16
SF=16
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Support PFRRMAX C/IGBR scheduling algorithm.
PF algorithm can adjust fairness and throughput. GBR algorithm consists of M-LWDF + Token, its soft priority
promotion could make the cell capacity maximize.
HS-SCCH power control based on CQI, and outloop powercontrol has been added.
Flexible AMC algorithm make steady BLER and highpower/codes efficiency.
The best RV parameter selection make high retransmissionefficiency.
Dynamic HSDPA total power allocation make high cellpower efficiency.
Dynamic HSDPA codes allocation make high codeefficiency.
Features of HSDPA scheduler
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