1000x Capacity Increase by Small Cell Densification and UltraSON

Rajat Prakash

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Mobile Data Traffic Growth - Industry Preparing for 1000x

1000x

~2xGLOBAL DATA

TRAFFIC GROWTH

FROM 2010- 2011*

PREPARING FOR

*Global growth, some regions grew more/less

DATA TRAFFICGROWTH

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Rising to meet the 1000x mobile data challenge

HIGHEREFFICIENCY

1000x

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Network Densification: Bringing the network closer to the user using small cells

USERDEPLOYED

Typically indoor small cells

4G Relays & Wireless Backhaul

RESIDENTIAL

ENTERPRISE

Extreme Densification—3G/4G+Wi-Fi Small Cells Everywhere

OPERATORDEPLOYED

Indoor/outdoor small cells

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Neighborhood Small Cells (NSC)Evolution to low cost ad-hoc deployments for extreme network densificationInside-out coverage and capacity for significant improvement over outdoor only deployments

‘Unplanned’ Deployment

Plug & Play Self-Config./Healing

Leverage Existing Site and Backhaul

Managed ByThe Operator

AD-HOC USERDEPLOYED

Typically Indoor ResidentialOpen Access

AD-HOC OPERATORDEPLOYED

Indoor/Outdoor, Lampposts, Walls, Malls, Anywhere…

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Neighborhood Small Cells Is Key Enabler Towards 1000x

Add 10x Spectrum

3.5GHz

Example for LTE FDD, 2x2 MIMO. Assumptions: 70% indoor users, 200 Active users per macrocell, small cells randomly dropped in households in a mix of 2 to 6 story apartments.1Small cells on dedicated spectrum used in this example, but we envision future neighborhood small cells also sharing the spectrum with macro and other small cells. 20% household penetration equals ~ 144 small cells, and 9% penetration equals ~ 65 small cells.

90Mhz for femtos3.5GHz

Dense Indoor Deployment

100 MHz dedicated to small cells

Median throughput gain versus Macro only baseline

~ 20 %Household Penetration

1000X

10MHz

for macros

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Good Outdoor Coverage Even with Low Small Cell Penetration

Performed coverage tests of commercial 3G femto cells in a suburban neighborhood- ~7% small cell penetration on dedicated channel*

Good indoor to outdoor coverage with 10mW pilot tx power

-115 to -105

-105 to -95

-95 to -85

-85 to -75

-75 to -65

-65 to -55

• RSCP= -115dBm results in ~700kbps in thermal noise limited case

• Points with RSCP less than -115dBm is not shown on the plots

RSCP [dBm]

*Small cells deployed on a channel different from macro cells20 houses have small cells out of 320 houses

Small cell

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Neighborhood Small Cell Deployment Challenges

Qualcomm’sUltraSONTM

Solves MultipleChallenges

• Plug-n-play• User deployed nodes

Unplanned Deployment

• Seamless, robust mobility• Carrier grade QoS

QoS with Mobility

• Signaling load on core

Core network impact

• Reliable operation withnon-provisioned, shared backhaul

Backhaul Sharing

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UltraSON™ OverviewQualcomm’s Self-Organizing Network (SON) solution for small cells- 3GPP defines SON functions and interfaces but not the algorithms- UltraSON is Qualcomm’s “secret sauce” for SON to enable NSC model

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UltraSON for 3G Indoor Coverage(closed access small cells)

UltraSON for 3G & 4G NSC(open access small cells)

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UltraSON™ for Neighborhood Small Cells

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Mobility Management

• Frequent Handover Mitigation• Forward handover• Robust mobility signaling• Automatic neighbor discovery

Tx Power Management

• Network listen based Tx power Mgmt.• UE-assisted Tx power management

Resource & Interference Management

• Resource partitioning and coordination• Load balancing between macro and small

cell layer

Backhaul Management

• User prioritization based on backhaul• Load balancing based on backhaul

• Optimize Handover performance and signaling load

• Optimize capacity and user experience

• Minimize pilot pollution

• Handle backhaul constraints

OBJECTIVE CATEGORY UltraSON FEATURES

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UltraSON Enables Small Cells to Deliver Carrier-Grade Performance

UltraSON performs self-configuration and optimization based on RF conditions around each cell

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AT STARTUP• Calibrate Tx power• Select PCI and configure neighbor list• Optimize mobility parameters and

paging area

AFTER STARTUP• Adapt Tx power and update neighbor list• Coordinate & partition resources with other cells• Adapt idle/connected state mobility parameters• Balance load among different cells• Monitor backhaul quality & ensure good user

experience

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Architecture for UltraSONSON functions operate in radio nodes- Operator control through

guidance from OAM/EMS- KPIs reported to OAM/EMS

Minimize interworking between Macro and Small Cell- Deploying Small Cell on

dedicated frequency removes most interworking requirements

- Co-channel deployments have dependency on macro

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Small Cell eNB

HeMSTR-196

Management

Small Cell eNB

Macro eNb

Macro EMS

Interface S

Macro eNB

Interface S

Central OAM

Interface N

Interface N

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Tx Power and Resource ManagementDense NSC deployment results in:- Frequent handovers due to pilot

pollution- Degradation of SINR due to inter-SC

interference

Perform NSC Tx power management to eliminate pilot pollution- Minimize number of handovers with

minimal impact on coverage

Perform NSC resource management to maximize capacity - Resource/interference coordination to

improve user SINR

Overall, jointly optimize mobility and capacity

NSC Coverage Regions: With Pilot Pollution

NSC Coverage Regions:With Pilot Pollution Elimination

6 Hard Handovers along route

2 Hard Handovers along route

Assumptions: 30% SC penetration (96 apartments out of 320),20dBm SCs (without Tx pwr mangement)

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Frequent Handover MitigationFrequent handovers impact user experience and increase signaling loadFHM algorithm:- Classify users as high speed or ping-pong users based on handover history- Adjust handover parameters per UE to prevent ping-pongs- Handover high mobility users to macro layer

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Neighborhood Discovery Target PCI to Cell ID mapping needs to be discovered to enable handover

Neighbor discovery using:- Network Listen- UE reports- X2 message exchange with

neighbors

UltraSON performs dynamic and efficient neighbor discovery - Use only relevant neighbors- Add/remove neighbors based on

changes in network topology

Macrocell2

Macrocell1

Small Cell 1

UE

Small Cell 2

Small Cell 1 can only detect Macrocell1

UE can also detect Macrocell2 and Small Cell 2

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Backhaul ManagementNSCs leverage existing backhaul with varying bandwidths- Backhaul BW availability varies due to

backhaul sharing with other traffic (e.g., WiFi) and other users

Backhaul management:- Estimate backhaul quality by probing

bandwidth & delay estimation servers- Adjust SC Tx power & mobility params.- Smart load balancing between small

cells and macros - Prioritizing home/enterprise user traffic

over other user trafficNon-cellular trafficfrom backhaul owner

Internet

Neighborhood Small Cell

ResidentialGateway

Competing trafficfrom neighbors

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Neighborhood Small Cell OTA Network20 node NSC OTA network deployedSelected UltraSON features implemented on 3G

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UltraSONON OFF

UE3

OFFON - High Tx powerON - Low Tx power

UE1

Serving cell

time

Throughput

Serving cell

time

Throughput

Serving cell

time

Throughput

UE1

UE2

UE3UE2

Mobility Demo• Frequent Handover Mitigation• Transmit Power Management

Self Config Demo• Cell ID Discovery• Transmit Power Management

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Taking Real World Neighborhood Small Cells to The Next level

Expand OTA network to a hyper dense LTE network

Macro cell site location (additional macros not

shown)

Example locations of indoor small cell locations in Qualcomm’s campus

Source: Google Earth

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To learn more:www.qualcomm.com/1000xwww.qualcomm.com/research/projects/smallcells