NSN Smart Scheduler for LTE

NSN Smart Scheduler for LTE and TD-LTE

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Technology introduction Scheduling in LTE (FDD) and TD-LTE

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Scheduler = Software in the base station, which allocates spectrum to users

Interference

Frequency

QoS

Fading Time 180kHz

Resource block 1ms

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A scheduler needs to mitigate physical effects like interference and fading, which can severely impact the throughput. It also needs to assure QoS.

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The scheduler implementation allows for differentiation

What is a scheduler?  

The scheduler is the software within an eNodeB, which allocates the spectrum resources each millisecond to the users in a cell As the scheduler implementation is not defined in 3GPP, a smart scheduler implementation is

Why is it relevant?  The scheduler has a direct

impact on throughput and latency

 This impact has been documented in the analyses and benchmark tests of Signals Research Group

innovation beyond the standard

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©2014 Nokia Solutions and Networks. All rights reserved.

Scheduler introduction What does it take to achieve consistently high data rates and low latency? User Equipment

eNodeB scheduler Radio resource allocation per UE

Channel quality information (CQI)

assignment

Modulation and coding

MIMO recommendation (MIMO rank indicator)

MIMO vs. TX diversity

Data to send (UE buffer status)

Frequency-selective scheduling

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reporting Power available (power headroom)

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NSN Smart Scheduler Continuous innovation Long track record in delivering superior performance

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High throughput – low latency - consistently Continuous innovation for superior performance Capacity increase

Smart Scheduler

Continuous innovation

Cell edge performance boost

Extended QoS

Baseline efficiency

Higher average throughput

Consistently lower latency

Channel awareness Interference awareness

Defineable quality classes

CoMP

eICIC

Fast Link Adaptation

Interference shaping

Interference aware power control

Intra-frequency load balancing

Nominal bitrate

Robustness

Foundation: Frequency Selective Scheduling in UL and DL

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©2014 Nokia Solutions and Networks. All rights reserved.

September 2010 First independent analysis of LTE scheduler performance Downlink

Uplink frequency

 Full utilization of resources

 Full utilization of resources Smart Scheduler

20 MHz

t

time

One colour = one scheduled subscriber frequency

 Only half of the bandwidth  Only one subscriber per timeslot

•

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 Low resource utilization  Only one subscriber per timeslot 20 MHz

Performed measurements in the LTE network of Telia, Sweden in NSN and Ericsson supplied network areas. Published a detailed analysis. Full report available from: www.signalsresearch.com

©2014 Nokia Solutions and Networks. All rights reserved.

October 2011: Performance benchmark in multivendor network Consistently lower latency and higher throughput Throughput

Latency

Drive test measurements 10 MHz bandwidth LTE-FDD, commercial network

Drive test measurements 10 MHz bandwidth LTE-FDD, commercial network

Mbps

• average latency: 27ms • worst measurement: 51ms

+ 24% 72

+ 88% 18

25

61

58

34

Average throughput

Peak throughput

NSN

Vendor B Vendor C

Vendor B • average latency: 38ms • worst measurement: 322ms Vendor C • average latency: 53ms • worst measurement: 360ms

Drive tests in a commercial network performed by NSN in October 2011 Confidential 26-Feb-14 9

©2014 Nokia Solutions and Networks. All rights reserved.

2012 Smart Scheduler becomes interference aware in uplink Interference Aware Scheduling Allocation of medium / high interference frequency blocks to users close to the eNodeB Allocation of low interference frequency blocks to users at cell edge

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Up to 10% gain for cell edge users in low and medium loaded networks

Interference Signal

MWC 2012 Interference

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November 2012: Commercial networks throughput benchmark NSN outperforms Ericsson and Huawei Optimum downlink throughput in good conditions

Highest DL throughput in challenging conditions

Low interference Cell center

High interference Cell edge

Theoretical maximum throughput of 1.48-1.5 Mbps / PRB in good radio conditions only reached by NSN. •

•

Measurements taken by NSN in two commercial LTE networks in APAC, supplied by NSN (RL30), Ericsson and Huawei Presenting results per PRB reduces the effect of network load

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Throughput per PRB in challenging radio conditions almost 100% higher with NSN. • •

PRB = Physical Resource Block = 180kHz (smallest spectrum resource for LTE) SNR = Signal to Noise Ratio (noise = interference)

©2014 Nokia Solutions and Networks. All rights reserved.

January 2013 (remember the September 2010 benchmark test) “We also knew and validated once again that with the current implementation of the Ericsson scheduler that it only assigned downlink resources to one mobile device within a sub-frame (e.g., it was limited to timebased scheduling and it didn’t support frequencybased scheduling). “ Signals Research Group Full report (January 22, 2013) available from: www.signalsresearch.com

The NSN Smart Scheduler has been assigning both downlink and uplink resources to multiple devices within a sub-frame already since 2010.

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Best LTE network quality in South Korea (Spring 2013) Korean LTE audit confirms best LTE network quality for NSN LTE quality issues – vendor results (in percent of affected population)

The world’s first government conducted LTE network quality assessment • •

All networks in all major cities and provinces (end 2012 – early 2013) Quality measure = Call Success Rate (CSR) • Call setup success, call drops • Throughput levels • Voice and data quality

• •

“Excellent” if CSR > 97.5% 5.8 mn people in cities and provinces with networks with deteriorated quality (CSR 40% LTE population penetration

The NSN LTE network outperformed the other LTE networks by a wide margin*  Ensuring downlink throuphput remained above 34Mbps  2-3 times faster downlink speeds than the two non-NSN LTE networks  The only network maintaining 100% data call completion rate (CCR) at all times * note: according to an independent test by an operator,

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NSN’s LTE outperforming Huawei’s Measurements in Middle East (Dec. 2012) • In Middle East NSN swapped Huawei LTE sites Nov.-Dec.2012 • The performance was measured prior and after the swap, average results for 9 sites below:

70 60 50

DL Avg Rate (Mbps) UL Avg Rate (Mbps) Latency (ms)

49.44 21.16 30.88

• On average: • NSN DL throughput 148% higher • NSN UL throughput 100% higher • NSN latency 52% lower

19.9 10.57 64.4

64,40

49,44

40 30,88 30 19,90

21,16

20 10,57 10

NSN Huawei

0 DL Avg Rate (Mbps) Confidential 26-Feb-14 38

UL Avg Rate (Mbps)

Latency (ms)

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Descriptions of selected Smart Scheduler features

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©2014 Nokia Solutions and Networks. All rights reserved.

Interference Aware Scheduler (UL) Optimize the cell edge performance

• Frequency domain scheduler assigns cell edge users to frequency sub-bands with low measured inter-cell interference in order to improve the cell edge performance

eNode B measured interference

Sub-band low interference

• Self-tuning algorithm, i.e. no planning needed

Sub-band with medium interference

• No X2 needed • Up to 10% gain for cell edge users in low and medium loaded networks

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PRBs

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Operator Specific QCI QCI based user differentiation

• 21 non GBR operator specific QCI profiles S-GW MME

to allow for: •

User differentiation

•

Service and user differentiation for MOCN

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User class:

‚Gold‘

‚Silver‘

‚Bronze‘

QCI range:

150…155

160…165

170…175

©2014 Nokia Solutions and Networks. All rights reserved.

Channel Aware Scheduler (UL) Up to 25 % capacity gain over channel unaware

• Assignment of PRBs (physical resource blocks) in the frequency domain based on CSI (channel state indicator)

• UE specific CSI is based on filtered measurements from the UL reference signal and sounding reference signal Channel aware

‚CSI table‘

PRBs

UE A

0

1

0

1

2

3

UE B

0

1

2

1

1

0

UE C

3

1

2

1

0

0

Resulting weight: 12

Channel unaware

Resulting weight: 2

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GBR QoS Package (1/3): Support of QCI 2, 3 and 4 Video and gaming services for LTE

• Support of GBR QCI (QoS Class Identifier) 2, 3 and 4 • Scheduler takes target delay and GBR rate into account • Bearer combinations: • SRB1+SRB2+ … • 2, 3 or 4 x AM DRB + … • 1 x UM DRB

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GBR QoS Package (2/3): ARP at Admission Control Prioritized user access

• Bearer pre-emption at admission control based on: • Priority • Pre-emption capability • Pre-emption vulnerability

ARP=6

may trigger pre-emption

not pre-empted as higher ARP ARP=4 ARP=8

pre-empted

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GBR QoS Package (3/3): Smart Admission Control Efficient resource usage

• Radio admission control based on: • Current resource usage and • Estimated additional resource usage

admission control threshold estimated additional usage

current usage PDSCH

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PUSCH

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Interference aware uplink power control Improved uplink cell edge & cell capacity

• Advanced uplink power control algorithm • balancing • gain in own cell and • interference introduced to other cells • based on eNode B measurements • no X2 needed

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-

+

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UL intra eNodeB CoMP Improved uplink cell edge performance

• eNode B combines uplink signals from multiple cells

• Automatic selection of suitable Rx paths

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©2014 Nokia Solutions and Networks. All rights reserved.

eICIC- macro Dynamic hotspot capacity

• Dynamic assignment of ABS (Almost Blank Subframes) by macro eNode B • Load triggered algorithm • eICIC and FeICIC (Further enhanced ICIC) support Macro eNode B subframe Micro eNode B subframe

ABS

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Subframes to be used primarily by the Micro eNode B

Micro eNode B subframe ©2014 Nokia Solutions and Networks. All rights reserved.

Nominal bitrate Ensure consistent end user experience per user class even at cell edge

• Operator configurable nominal bitrate per QCI for uplink and downlink

S-GW

MME

• Allows to control end user experience for non GBR bearers

• Non GBR resources are allocated first to achieve the nominal bit rate

• Remaining resources distributed according to scheduling weights

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Gold

nominal rate = 1000 kbit/s

Silver

nominal rate =

100 kbit/s

Bronze

nominal rate =

10 kbit/s

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Intra-frequency load balancing Enhanced capacity for micro co-channel deployment or macro-macro deployments

• Adapt handover borders between cells based on load

• Load exchange between cells via X2 • Handover threshold change coordination via X2

• Cell scenarios • Macro – Macro • Macro – Micro • Micro – Micro

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‘expanded’ micro

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