1000x capacity increase by small cell densification and...
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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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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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