Small Cells & UltraSONTM © 2014 Qualcomm Technologies, Inc. All rights reserved. Overview © 2014 Qualcomm Technologies, Inc. All rights reserved. Strong Mobile Data Demand Requires Extra Capacity 1000X Exabytes per Month Overall Mobile Data Traffic Growth 12 11.2 EB 66% CAGR 2012-2017 7.4 EB 6 4.7 EB 2.8 EB 1.6 EB 0.9 EB 0 2012 2013 2014 2015 2016 2017 MOBILE NETWORKS NEED TO PREPARE FOR 1000X TRAFFIC GROWTH! Source: Cisco VNI Mobile, 2014 3 © 2014 Qualcomm Technologies, Inc. All rights reserved. Small Cells & Extra Spectrum Are Critical For Reaching 1000x Evolve 3G/4G/Wi-Fi 4 HIGHER EFFICIENCY HetNets Interference Mgmt/SON Intelligently Access 3G/4G/Wi-Fi MORE SPECTRUM MORE SMALL CELLS MORE INDOOR CELLS IN LOW AND HIGHER BANDS EVERYWHERE! INSIDE-OUT DEPLOYMENT © 2014 Qualcomm Technologies, Inc. All rights reserved. Progressive Introduction Of Small Cells To Build Dense Carrier-Grade Network Macros Combined network managed by operator + planned small cells + dense unplanned* small cells Planned small cell Unplanned small cell BRING CARRIER-GRADE NETWORK CLOSER TO USER FOR NEXT LEAP OF PERFORMANCE 5 * Small cells will be deployed in areas of high demand without detailed RF planning. © 2014 Qualcomm Technologies, Inc. All rights reserved. Deploying Small Cells Wherever Needed Enterprise small cells Neighborhood Small Cells (NSCs) Picocells Enterprise small cells HIGH CAPACITY • Significant capacity gains compared to macro-only deployment 6 6 LOW COST DEPLOYMENT • Minimal CapEx and OpEx • Leverages existing premises and backhaul EASY TO DEPLOY • Simple plug-n-play by customer with SON • Unplanned yet scalable and operator-managed © 2014 Qualcomm Technologies, Inc. All rights reserved. LTE OTA Network in San Diego R&D platform for UltraSON features Hyper Dense Outdoor SC Network • ~15m between SCs • Semi-planned deployment • Wireless backhaul for some SCs Dense Indoor Network • NSC with in2out coverage over campus • Seamless mobility between cells • Unplanned deployment • Enterprise indoor network in one of the buildings 7 © 2014 Qualcomm Technologies, Inc. All rights reserved. UltraSON Features © 2014 Qualcomm Technologies, Inc. All rights reserved. LTE UltraSON Features Category UltraSON Features • • Automatic PCI selection Automatic neighbor discovery (including 3GPP ANR) Backhaul Aware Operation: Handle backhaul constraints • Backhaul quality aware load balancing Mobility Management: Optimize HO performance and reduce signaling load • • • Frequent Handover Mitigation Forward handover Robust mobility (including 3GPP MRO) Dynamic Resource and Tx Power Management: Optimize capacity, minimize pilot pollution and load balancing • • Tx power management Resource partitioning and coordination (including 3GPP ICIC) Load balancing (including 3GPP MLB and macro-SC) Self Configuration: Automatic cell parameter and backhaul config. • © 2014 Qualcomm Technologies, Inc. All rights reserved. SON Features Help Small Cells Deliver Carrier-Grade Performance • • In an unplanned/semi-planned deployment, RF environment around each small cell is different and dynamic Small cell needs to be able to respond when it is turned on and continue to adapt to the changing environment AT STARTUP AFTER STARTUP • Select PCI and configure neighbor list • Calibrate Tx power • Optimize idle re-selection parameters and paging area • Adapt Tx power & update neighbor list • Coordinate & partition resources with other cells • Monitor backhaul quality & prioritize preferred users • Balance load among different cells 10 © 2014 Qualcomm Technologies, Inc. All rights reserved. Automatic PCI Selection and PCI Collision Resolution • PCI selection/reselection using Network Listen and X2 messages PCI 3 PCI 2 PCI 1 PCI 4 PCI ? • Use a combination of Network Listen, X2 messages and UE assistance to detect/resolve any potential PCI collision caused by hidden node PCI 2 PCI 2 PCI 1 11 PCI 4 PCI 3 © 2014 Qualcomm Technologies, Inc. All rights reserved. Automatic Neighborhood Relation (ANR) • Target PCI to Cell ID mapping needs to be discovered to enable handover Small Cell 1 can only detect Macrocell1 Macrocell2 – Network Listen alone cannot detect all neighboring target cells for handover • Mobile reports (ANR) and X2 message exchange can be utilized to enhance the neighbor cell list obtained via Network Listen UE Small Cell 1 Small Cell 2 Macrocell1 12 UE can also detect Macrocell2 and Small Cell 2 • Need to handle persistence and dynamic nature of network topology © 2014 Qualcomm Technologies, Inc. All rights reserved. Main Considerations for Mobility Management for Small Cells Small cell to Small cell Small cell carrier Overlay Macro carrier Facilitate handover to small cells to maximize traffic offload Key Issues: Mobile UEs on small cell layer likely to cross cell boundary frequently Excessive handovers create signaling load and potential outage and hence should be avoided 13 © 2014 Qualcomm Technologies, Inc. All rights reserved. Frequent Handover Mitigation (FHM) Improves User Experience • Frequent handovers impact user experience and increased signaling load • Use MRO for overall mobility parameter optimization to improve handover performance • Use Frequent Handover Mitigation for per UE optimization beyond MRO: • Classify users as high speed or ping-pong users • Adjust handover parameters per UE to prevent ping-pongs • Handover high mobility users to macro layer Macrocell (Frequency f1) Small cells (Frequency f2) Ping-ponging UE at the edge of small cells 14 Fast moving UEs crossing coverage of different small cells © 2014 Qualcomm Technologies, Inc. All rights reserved. Reduce Handover Failures Through Mobility Robustness Optimization (MRO) • Small cells monitor handover failures and the causes – Example: “Too Early”, “Too Late”, and “Wrong Cell” handovers – X2 messages exchanged between source and target cells on failures • UltraSON tracks handover failures and successes for ping-pong, slow moving and fast moving users • UltraSON adjusts handover parameters for each user type at each cell to reduce handover failures A small cell serves and optimizes mobility for users with different mobility requirements Slow moving users Ping-pong users Fast moving users 15 © 2014 Qualcomm Technologies, Inc. All rights reserved. Forward Handover (FHO) Improves Robustness • Robust handover performance is important to ensure excellent user experience – E.g., for push-to-talk application • In regular handovers, source cell would prepare target cell by sending UE context • If target cell did not receive UE context in time, it can fetch UE context from the source cell to reduce handover interruption X2 16 Fetch UE context © 2014 Qualcomm Technologies, Inc. All rights reserved. Transmit (Tx) Power Management Improves SINR UltraSON ON UltraSON OFF • 7 outdoor small cells • Improvement in SINR with UltraSON techniques – Median SINR improvement of 6-10 dB 17 © 2014 Qualcomm Technologies, Inc. All rights reserved. Joint Tx Power and Resource Management • Dense small cell deployment results in degradation of SINR due to inter-SC interference • Joint Tx power and resource management to maximize capacity and networkwide user experience – Resource/interference coordination to improve user SINR – Dynamic orthogonalization of resources for cell edge users Signal A B All Users Benefit if the SCs use orthogonal resources • 18 Both Users can be served on all resources as the interference seen is low Interference Network-wide fairness is increased if User B gains a lot, in return of User A sacrificing a small fraction of resources Use of UE measurements reports and X2 messages for Tx power and resource management © 2014 Qualcomm Technologies, Inc. All rights reserved. Backhaul Aware Load Balancing - Overview • Internet Backhaul bandwidth availability can vary due to backhaul sharing with other traffic (e.g., WiFi) and other users • Backhaul aware load balancing is done via: Competing traffic from neighbors Residential Gateway Neighborhood Small Cell – Estimating backhaul quality by probing bandwidth and delay estimation servers – Offloading SC UEs to macro when SC backhaul is the bottleneck – Dynamic load balancing between small cells and between small cells and macros based on backhaul quality – Prioritizing home/enterprise user traffic over other user traffic Non-cellular traffic from backhaul owner 19 © 2014 Qualcomm Technologies, Inc. All rights reserved. Mobility Load Balancing Between Neighboring Cells • Mobility Load Balancing (MLB) distributes user load between LTE macrocell and small cells as well as between small cells to provide better user experience and improve system capacity • MLB uses cell load information to optimize cell boundaries to offload users • UltraSON uses both mobility parameters and downlink transmit power adjustment for load balancing A B A 20 B © 2014 Qualcomm Technologies, Inc. All rights reserved. NSC Capacity Simulation Results © 2014 Qualcomm Technologies, Inc. All rights reserved. Dense Urban Neighborhood Small Cells Simulation Assumptions meter Dense-Urban Area (Simulation with Apartment Buildings) Parameter Value Macrocell ISD 500m Population Density 20000 per sq km Number of Apartments per Macrocell (2 subs per Apt.) 720 User Distribution 70% Indoors/ 30% Outdoors; Randomly dropped Notes: a) b) 22 Small cells are randomly dropped in a apartment statistically independent of other small cells’ locations At most one small cell is dropped in any apartment Red: 2 story bldg Blue: 3 story bldg Green: 4 story bldg Cyan: 5 story bldg Yellow: 6 story bldg Black star: Small cell Magenta Circle: Mobile Blue circle: Macrocell © 2014 Qualcomm Technologies, Inc. All rights reserved. Neighborhood Small Cell Capacity Simulation Dense Urban Model Configuration Birds-eye view • • • Multi-floor apartment blocks placed in a 3-cell macro area Each apartment block has two buildings with a street in the middle 10 apartments in each floor in each building – Two rows of 5 apts – Each apt is 10m x 10m with a 1m-wide balcony • Detailed RF propagation modeling for indoors and outdoors – Indoor propagation based on KeenanMotley multi-wall model – Explicit modeling of internal and external walls, windows and floor losses • Internal wall loss: 8dB • External wall loss: 20dB • Floor loss: 18.3dB (indoor users only) 23 ISD=1000m Zoomed-in layout 350 300 250 200 150 100 50 0 0 50 100 150 200 250 300 350 Apartment Block 10m 11m 10m © 2014 Qualcomm Technologies, Inc. All rights reserved. Neighborhood Small Cells Capacity Simulation Baseline (macro-only) vs. Macro+Small Cells Deployments Macro Network NSC Network F1 Macro Network F1 F2 24 Baseline Macro Deployment Macro + Small Cells Deployment Rel 8 LTE, single 10 MHz LTE carrier at 2 GHz carrier frequency Rel 8 LTE, 10 MHz carrier for macros at 2 GHz while small cells are deployed in 3.5 GHz © 2014 Qualcomm Technologies, Inc. All rights reserved. Neighborhood Small Cells Provide Significant DL Capacity Gains for LTE DL Median Throughput Gains DL Median Throughput Gain (x) (LTE dense urban, 10 MHz BW small cells in 3.5 GHz, gains relative to macros only) 25 UEs/macro 200 UEs/macro 180x 160x 140x 120x 100x 80x 60x 40x 20x 0x Simulation Configuration Macro 10 MHz @ 2 GHz Small cell 10 MHz @ 3.5 GHz 100x capacity gains at 20% penetration 0% 10% (72 small cells) 20% 30% Small Cell Penetration (%) 40% 50% (360 small cells) Neighborhood Small Cells Offer Scalable Capacity As Demand Increases • 500m ISD, 720 apartments/cell, 2 subs/apartment. Users randomly dropped, 70% indoor and 30% outdoor, 2x2 MIMO • Gains shown are relative to macro-only baseline. Macros deployed in 10 MHz bandwidth at 2 GHz. Small cells deployed at 3.5 GHz with 10 MHz bandwidth. • Small cell penetration is percentage of total apartments per macrocell (720) with a small cell. For a particular operator, this number cannot exceed its own market share. For example, an operator with 30% market share can at most have 216 small cells in a macro (assuming no small cell is deployed outside customer premise by the operator). 25 © 2014 Qualcomm Technologies, Inc. All rights reserved. Exceeding 1000x Capacity Gain With Dense Neighborhood Small Cells And More Spectrum DL Median Throughput Gain (LTE, dense urban, 100 MHz small cells in 3.5 GHz, relative to macros only) 25 UEs/macro DL Median Throughput Gain (x) 1,800x 200 UEs/macro Simulation Configuration 1,600x 1,400x 1,200x 1,000x Macro 10 MHz @ 2 GHz Small cell 100 MHz @ 3.5 GHz 1000x capacity at 20% small cell penetration 800x 600x 400x 200x 0x 0% 10% 20% 30% (72 small cells) 40% 50% (360 small cells) Small cell Penetration (%) • 500m ISD, 720 apartments/cell, 2 subs/apartment. Users randomly dropped, 70% indoor and 30% outdoor, 2x2 MIMO • Gains relative to baseline with macros only. Macros deployed in 10 MHz bandwidth at 2 GHz. Small cells deployed at 3.5 GHz with 100 MHz bandwidth. • Small cell penetration is percentage of total apartments per macrocell (720) with a Small Cell. For a particular operator, this number cannot exceed its own market share. For example, an operator with 30% market share can at most have 216 small cells in a macro (assuming no small cell is deployed outside customer premise by the operator). 26 © 2014 Qualcomm Technologies, Inc. All rights reserved. SON Architecture: Hybrid SON © 2014 Qualcomm Technologies, Inc. All rights reserved. Distributed and Centralized SON Components • Autonomous eNB operation with real-time decision making – eNB utilizes rich data set obtained from the radio layers – Reduced signaling load eases complexity and processing need at centralized entity • Centralized Node with long term decision making – Receives selected metrics from RAN – Sets policies for distributed algorithms – Performs optimization over wide area Central Node Sets policies, less signaling, more scalable Distributed Decision Making 28 © 2014 Qualcomm Technologies, Inc. All rights reserved. Hybrid SON: High Level View Centralized Node KPIs Alarms Filtered information Parameter Ranges Policy Guidelines RAN 2 RAN 1 Backhaul © 2014 Qualcomm Technologies, Inc. All rights reserved. Summary • Small cells can be deployed wherever extra capacity is needed • Hyper-dense deployment of open access neighborhood small cells utilizes additional spectrum in the most efficient way • Small cells provide a cost-effective way for operators to reach 1000x today’s network capacity – Low-cost deployment model leveraging existing premise and backhaul • Easy to deploy, scalable and operator-managed via SON – Qualcomm is developing UltraSON Open for robust small cell deployment • Hybrid SON preserves the advantages of centralized SON and distributed SON 30 © 2014 Qualcomm Technologies, Inc. All rights reserved. research.qualcomm.com Not to be used, copied, reproduced , or modified in whole or in part, nor its contents revealed in any manner to others without the express written permission of Qualcomm Technologies, Inc. Qualcomm is a trademark of QUALCOMM Incorporated, registered in the United States and other countries. All QUALCOMM Incorporated trademarks are used with permission. Other products and brand names may be trademarks or registered trademarks of their respective owners. © 2014 Qualcomm Technologies, Inc. All rights reserved. © 2014 Qualcomm Technologies, Inc. All rights reserved.
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