Nokia Siemens Networks – 3G Uplink Optimization NSN response to Annex 6, Chapter 5 in T-Mobile Netherlands Single RAN RfQ September 2011
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Š Nokia Siemens Networks 2011
Customer Confidential
Introduction Target This presentation is intended to provide response to Annex 6 Chapter 5 in T-Mobile Netherlands Single RAN RfQ where the Supplier is requested to provide an overview of measures taken to reduce the radio and baseband/RNC resource allocation in a high smartphone penetration environment with extremely high signaling load. Confidentiality All information related to the Nokia Siemens Networks 3G Uplink Optimization features, functionality’s and roadmaps presented in this document are strictly Nokia Siemens Networks Customer confidential. No information shall be disclosed to any third party without permission from Nokia Siemens Networks.
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Customer Confidential
Uplink vs Downlink Traffic in Live 3G Networks (1) HSUPA / HSDPA daily volume ratio at selected operators 0.25
Europe 1
0.20
South America Europe 2
0.15
MEA Europe 3
0.10
• 0.05
• 0 01.03.2010
01.07.2010
01.10.2010
01.01.2011
Source: NSN Analysis, April 2011
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Customer Confidential
01.04.2011
Uplink traffic volume is 1520% of downlink Uplink volume is growing faster than downlink (due to HSUPA)
Uplink vs Downlink Traffic in Example Live 3G Network HSDPA vs HSUPA ratio 10x now and getting smaller due to higher HSUPA penetration
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HSDPA vs HSUPA + WCDMA UL ratio 6x and stabile
Customer Confidential
Uplink vs Downlink Capacity in Theory
• •
Evolution of HSPA efficiency
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1.74
Downlink Uplink
1.44
1.31
© Nokia Siemens Networks 2011
0.53
0.65
0.65
0.79
Customer Confidential
LTE R8
HSPA R10 QCHSDPA+MIMO
0.33
HSPA R8 DCHSDPA
0.33
HSPA R7 64QAM
0.55 0.33
1.52
1.11
HSPA R9 DCHSDPA+MIMO
1.06
HSPA R6 + UE equalizer
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0
HSPA R6
bps/Hz/cell
•
Downlink 1.31 bps/Hz/cell Uplink 0.33 bps/Hz/cell (0.53 with IC) => Theoretical ratio 4x
Smartphones Increase Signalling Load •
More multi-RABs due to smartphones
• Smartphones create frequent transmission of small packets which requires frequent RRC state changes (DCH allocations) and RACH signalling which increases uplink interference
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Starting Point for Uplink Optimization •
In theory, the networks should be downlink limited because the traffic is 5-6x in downlink while the capacity is 4x. The higher uplink noise rise is mainly caused by the control overhead
• – – – –
•
•
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RACH preambles and messages, like RRC requests, uplink capacity request and user plane data, especially related to smartphone traffic DPCCH overhead. For example, with AMR5.9 kbps 64% of interference comes from DPCCH. DPCCH overhead from PS 0/0 kbps users HS-DPCCH overhead for HSUPA
It is possible to improve the situation because we are not hitting any fundamental theoretical limit. The limit is ”only” system protocol design and configuration. There are already promising indications since RU20 ontop releases have stabilized the uplink in many networks. NSN uses interference based uplink RRM while some RAN vendors use throughput based solution (number of users). The interference based solution has the benefit that cell breathing can be controlled. But interference based solution requires also careful control of the uplink interference sources to provide optimal performance. © Nokia Siemens Networks 2011
Customer Confidential
NSN Solutions for Uplink Interference Control – Summary 3GPP Release 99-6 Cell_PCH
3GPP Release 7
Interference cancellation
RU30
Continuous packet connectivity
RU20
Fast dormancy
RU20
HSUPA DPCCH interpolation
RU30
HS-RACH
RU40
Dynamic HSUPA power offset
RU20
Cell level control of uplink parameters
RU30
High noise optimized RRM1
RU20
Load aware outer loop power control
RU30
High noise optimized RRM2
RU20
RACH access class barring
RU40
Dynamic initial bit rate allocation
RU20
Fast BTS load control
Downgrade of DCH in SHO congestion
RU20
Dynamic parameter settings
RRC IPhone workaround
RU20
Dynamic CQI frequency
DPCCH overhead calculation
RU20
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3GPP Release 8
Customer Confidential
Dynamic HSUPA Power Offset • Two sets of DPCCH offset values defined. Lower DPCCH power is used when the condition (H=High load) is fulfilled DynPwrOffsetTable2 (High/low power offset indication table for 2ms TTI) RSCP [dBm]
EcNo [dB]
< -108
< - 14
L
L
L
L
L
L
-105…-108
-13…-14
L
L
L
L
L
L
-101…-104
-11…-12
L
L
L
L
L
L
-98..100
- 10
H
H
L
L
L
L
-98..-95
-9
H
H
H
L
L
L
> -95
> -9
H
H
H
L
L
L
0-1 9
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2-3
4-6
Customer Confidential
7-12
13-20
>20
# of HSPA serving cell users
High Noise Optimized RRM1 • Five features for optimizing the power based uplink RRM • Correction of the filtering parameter MaxIncrInterferenceUL • Filter out the short term spikes of the measured RTWP for avoiding the unnecessary admission control blockings during the period of the spike
• • • •
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Corrections in power increase and decrease estimations of the estimated R99 power Correction of the power increase and decrease estimations in the HSUPA cells Reference power of the management parameter DeltaPrxMaxUp Reduction of the SIR target values for the PS HSPA calls
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Initial SIR Target Optimization Parameters SIRDPCCHInitialDCHHS256 SIRDPCCHInitialDCHHS128 SIRDPCCHInitialDCHHS64 SIRDPCCHInitialDCHHS32 SIRDPCCHInitialDCHHS16 SIRDPCCHInitialDCHHS8 SIRDPCCHInitialDCHHS4 SIRDPCCHInitialDCH64
4.5 4.5 4.5 6.0 7.5 8.0 9.0 4.5
Initial DPCCH SIR w HSDPA AmplitudeRatioACK 1-RX 2-RX 4-RX nonSHO SHO beta_d / beta_c 2.5 -0.5 -1.5 1.3 2.0 2.5 -0.5 -1.5 1.3 2.0 1.2 2.5 -0.5 -1.5 1.3 2.0 4.0 1.0 0.0 1.3 2.0 1.4 5.5 2.5 1.5 1.0 1.6 1.7 6.0 3.0 2.0 1.0 1.6 7.0 4.0 3.0 0.8 1.3 2.5 2.5 -0.5 -1.5 1.2
R_b
SIRDPCCHInitialDCHOffset SIRDPCCHInitialDCHRxDiv2 SIRDPCCHInitialDCHRxDiv4 SIRDPCCHInitialDCHMax SF DPCCH
16 kbps 64 kbps 128 kbps
-2 -3 -4 6 256
dB dB dB dB
384 kbps AMR 12.2
Graphs are assuming activity factor as given below: 16kbps – 63%, 64kbps – 16%, 384kbps – 3%
Original Defaults
New Recommendation UL noise rise at initial SIR with DPCCH and HS-DPCCH overhead 10
9
9
8
8
7
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Customer Confidential
25
23
21
19
17
15
Num ber of links (DPCCH + HS-DPCCH + DPDCH)
Num ber of links (DPCCH + HS-DPCCH + DPDCH)
11
13
1
25
23
21
17
19
0 15
1
0 13
1
11
2
9
2
7
3
5
3
3
384 kbps
4
11
4
64 kbps
9
384 kbps
16 kbps
5
7
64 kbps
5
6
5
16 kbps
3
6
UL noise rise (dB)
10
1
UL noise rise (dB)
UL noise rise at initial SIR with DPCCH and HS-DPCCH overhead
High Noise Optimized RRM2 • 12 features for optimizing the power based uplink RRM • • • • • • • • • • • •
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Emergency call failure for the power blocking PrxNoise autotuning only in the cell without any CELL_DCH traffic PrxNoise is autotuned only if all cells of the same frequency in the BTS are on the low traffic level Adjusting of the increased reference noise floor value in the loaded cell Detection of the common measurement reports filtered by BTS Candidate prioritization and bit rate selection in PBS R99 Overload Control procedure Downgrading the PS NRT DCH for the soft handover branch addition congestion handling PRFILE parameter control for triggering the channel type switching from the SIR error Limited value of UL DPCCH power offset for the first RL setup in the RTWP spiking cell Power based Admission Control for the HSUPA call setups Correction in updating the the MIN and MAX PRXTOTAL counters of the Received Rel99 wideband power measurement © Nokia Siemens Networks 2011
Customer Confidential
Dynamic Initial Bit Rate Allocation • Allows more PS NRT users admitted at initial and minimum bit rates in and keep the existing PS NRT users longer in the CELL_DCH state. • High bit rate PS DCH users are selected first for downgrade, the QoS priority is applied only when the PS calls of the cell are not using higher than the initial DCH bit rates • PBS candidates will be prioritized in all congestion cases as follows: • PS NRT DCHs users having higher bit rate than initial bit rate users, in the QoS priority order. • PS NRT DCHs users having higher bit rate than minimum bit rate users, in the QoS priority order. • Finally the minimum bit rate users, in the QoS priority order. • Initial/minimum DCH bit rate selection of the PS call triggered the PBS: • New functionality applies to the UL interference, DL power and UL load congestion. • If BRM detects congestion and the PBS triggers, then: • If high bit rate (higher than initial) PBS candidates are available, then the incoming user gets the initial bit rate • If only low bit rate (lower or initial) PBS candidates are available, then the incoming user gets the minimum bit rate. 13
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Downgrading NRT DCH in Soft Handover Congestion • Present implementation does not allow the downgrading of the DCH bit rates of the PS bearers if a congestion occurs in the soft handover branch addition. If the target cell is better than the ones in the active set, the failed soft handover may cause significant spiking of the RTWP, unless the PS DCH is removed. • In the new implementation, the PS DCH is downgraded to the minimum bit rate and then attempted the branch addition once more. • If the congestion occurs still, the UE is switched to CELL_FACH state without applying the management parameter EnableRRCRelease. If the UE has also the AMR, the PS bearers are downgraded to DCH 0/0 as it is done already in the original implementation. • Function is similar if the congestion occurs in the soft handover branch addition over the Iur.
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RRC IPhone Workaround UE 1
Cell1
RNC
Cell1
UE 2
RACH: RRC: RRC Connection Request UE starts decoding FACH RL setup procedure, spreading code1 FACH: RRC: RRC Connection Setup, state indicator: Cell-DCH (Spreading code 1) UE decodes some rubbish from FACH
Solution: RNC ignores the repeated RRC connection request with protocol error cause and wait for the RRC connection setup complete for the first RRC connection setup.
RACH: RRC: RRC Connection Request cause: protocol error RNC thinks first RRC connection request has failed, and releases resources, and setup resources for second RRC connection request
UE decodes first RRC Connection setup message, and starts using spreading code 1 in Cell_DCH state
RL deletion procedure, spreading code 1 RL setup procedure, spreading code2 RNC allocates spreading code1 to UE2
FACH: RRC: RRC Connection Setup state indicator: Cell-DCH (Spreading code 2) DCH: RRC: RRC Connection Setup Complete spreading code 1
UE1 and UE2 decoding the same DL spreading code and TPC bits. UE1 can cause uncontrolled interference. 15
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DPCCH Overhead Calculation â&#x20AC;˘ DPCCH overhead included in load factor estimation has too conservative value based on initial UL SIR target. This modification multiplies the initial SIR target value with the activity factor of the signaling link DCH.
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Interference Cancellation • Estimate the physical channel data after channel (Turbo) decoding. The physical channel data is generated by encoding the decoded data. Large gain from channel decoding • Uplink throughput gain 23-62% • SW upgrade to Flexi Rel.2 baseband ROT = 6 dB ROT = 8 dB thrput Mbps trp gain thrput Mbps trp gain PIC PIC PIC PIC (uncod.) (uncod.) no PIC (uncod.) (uncod.) no PIC PIC PIC PIC PIC 1 user 2 user 3 user
RX
5,84 4,78 3,96
5,92 5,87
RAKE
5,92 5,39
24% 48%
DECODER
24% 36%
7,61 5,53 4,29
© Nokia Siemens Networks 2011
7,69 6,19
39% 62%
39% 44%
ENCODER IC
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7,69 6,93
RAKE
DECODER Customer Confidential
Cell Level Control of Uplink Parameters • Some of the existing UL interference impacting parameters that are controlled in RNC level, change to cell level
• • • • • •
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HSDPAinitialBitrateUL HSDPAminallowedBitrateUL TrafVolPendingTimeDL TrafVolPendingTimeUL Prx NoiseMaxTuneAbsolute WaitTimeRRC
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Load Aware of Outer Loop Power Control • • • •
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Target: prevent too high increase of SIR target during high load Reason: SIR target increases if UE hits its max power Freeze AMR SIR targets and decrease NRT PS SIR targets until noise rise gets lower Potentially also decrease AMR SIR and/or increase BLER target with higher noise rise
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RACH Access Class Barring • The access classes [0,…9] which are barred are actually rotated by specified intervals. • If during first time interval, the access classes [1,2,3] were barred, in the next time interval [4,5,6] would be barred covering access classes 0,…,9, i.e. rotation by mod 10. Rotation time needs to be long enough.
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Fast BTS Load Control •
Reduce SIR target if noise rise exceeds PrxTarget + offset (2 dB)
If (Noise _ rise ) > Prx ,t arg et + Offset , SIRt arg et , BTS = SIRt arg et , RNC −
(Noise _ rise − P
rx ,t arg et
− Offset )
10
0 -0.1
SIR target correction [dB]
-0.2
SIR target adjustment
-0.3 -0.4 -0.5
PrxTarget 8 dB
-0.6 -0.7 -0.8 -0.9 -1
21
0
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4
6
8 10 12 Noise rise [dB]
14
16
18
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Customer Confidential
Dynamic Parameter Setting • High interference cases can be solved by using suitable timer and other parameters during mass events. Some of those parameters are not good for the non-congested cells. Therefore, the parameters should be automatically tuned according to the instantaneous load.
• Example parameters • WaitTimeRRC • TrafVolPendingTimeUL
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Dynamic CQI Frequency • Channel Quality Information (CQI) frequency is 4 ms currently • CQI frequency could be lowered during high uplink load to minimize the interference in the same way as DPCCH offset values are optimized • Current CQI interference contribution with 4 ms period = 0.41 x DPCCH. If we would lower CQI frequency to 10 ms or 20 ms, the interference would reduce to 0.08..0.16 x DPCCH. • The total uplink interference from HSDPA users without any uplink activity would be reduced be 1-(1+0.08)/(1+0.41) = 23%
HS-DPCCH
A/N
DPCCH
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CQI
A/N
CQI
A/N
DPCCH
Customer Confidential
CQI
CQI power offset –2 dB in single link and +4 dB in SHO compared to DPCCH
Continuous Packet Connectivity reduces interference especially for low data rate users • Gating is part of Continuous packet connectivity (CPC). It is part of 3GPP Release 7
Web page download
Cell Throughput (kbps)
• Uplink DPCCH and E-DPCCH gating
1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 0
User reading web page
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5
10
15
20
25
30
35
40
45
Number of no-data UEs in CELL_DCH
E-DDCH (E-)DPCCH
24
PedA_not gated PedA_9/15 PedA_12/15 PedA_9/15 ideal PedA_12/15 ideal
Customer Confidential
50
55
HSUPA DPCCH Interpolation • Release 7 solution allows to minimize DPCCH overhead for low data rate HSUPA users • Fixed DPCCH power in Release 6 leads typically to too high DPCCH overhead at low kbps Relative power of E-DPDCHs over DPCCH 2 ms TTI
18 16 14 12 10 8 6 4
Data rate [kbps]
25
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09 6 4
84 0 3
58 4 3
32 8 3
07 2 3
81 6 2
2
56 0
30 4 2
04 8 2
79 2 1
53 6 1
28 0 1
02 4 1
76 8
51 2
Computed P(E-DPDCHs) Optimal P(E-DPDCHs) 25 6
Pred [dB] 6 7.1 8.1 8.9 9.9 8.1 8.1 6 6 6 7.1 8
0
E-TFC [kbps] 32 64 128 256 384 512 768 1024 1450 1920 2900 3800
P(E-DPDCHs) [dB]
Optimised gain factors
Fast Dormancy Other vendors DCH/HSPA
Active = >200 mA Cell_FACH = >100 mA
30 signaling messages IDLE
Nokia Siemens Networks
inactivity timer CELL_FACH
inactivity timer
Fast Dormancy to save battery
Cell_PCH = <5 mA Idle = <5 mA
Heavy signaling load Low battery life time
2s
IDLE
IDLE
Network avoids signaling storm Battery lasts longer
DCH/HSPA inactive
Active = >200 mA Cell_FACH = >100 mA Cell_PCH = <5 mA Idle = <5 mA
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12 signaling messages
CELL_FACH
3 signaling messages
PCH
<0.3 s
Customer Confidential
inactive
PCH
allocation is typically 10-60 kB for the smartphones. The median value is even smaller: 60% of allocations are below 1 kB ⇒ large part of smartphone traffic could be carried by HS-RACH • HS-RACH reduces control overhead considerably • No setup signalling • Immediate stop of control channel transmission compared to DCH with >1 second timer
27 © Nokia Siemens Networks 2011
Apple iPad 3G (A1337) Apple iPhone 3G (A1241) Apple iPhone 3G A1241 Apple iPhone 3G S - A1303 Apple iPhone 3G S (A1303) Apple iPhone 3GS A1303 Apple iPhone 4 (A1332) ASUSTek N³vifone A50 HTC DREA110 HTC Desire HTC Hero HTC Legend HTC Wildfire HTC MAPL110 HTC PB92200 HTC PB99100 HTC PB99210 HTC PD98100 Huawei E160E Huawei E169 Huawei E1762 LG GT540 Motorola MB501, ME501 Nokia E5-00 Nokia E63-1 Nokia E71-1 Nokia E72-1 Nokia N97-4 Nokia Nokia E63-1 Nokia Nokia E71-1 Nokia Nokia E72-1 Nokia Nokia N8-00 Qisda Streak RIM 9000 RIM 9300 RIM 9700 RIM 9700 (Generic) RIM 9780 RIM Blackberry 9800 Samsung GT-I5800 Samsung GT-I8700 Samsung GT-I9000 Samsung Samsung GT-I9000 SierraWireless MC8775V Sony Ericsson E10i Sony Ericsson X10i Sony Ericsson X10i
HS-RACH
• HS-RACH allows carrying medium size data packets without allocation of dedicated resources
• The avarage data volume per
315 320 300 280 260 240 220 199 200 180 160 140 117 120 100 94 100 78 6868 65 80 53 44 60 47 46 50 34 32 38 34 25 23 40 20 20 17 15 14 21 15 11 16 12 8 6 14 13 11 5 1 2 4 3 6 3 5 20 2 2 1 8 0
kB per DCH or HS-DSCH Allocation
Customer Confidential
Summary •
3G networks have turned to be uplink limited due to interference limited nature of CDMA uplink. The main problems come from the control channel and signalling overhead which is driven by increased smartphone traffic and HSUPA high data rates
•
NSN has introduced a large number of features in RU20 and RU30 to improve the uplink performance. The features have already shown to be highly useful in the practical networks.
•
NSN has been active in 3GPP to improve the system performance
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