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Qualcomm Confidential and Proprietary — Restricted Distribution - DO NOT COPY MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION —
San Diego
Wireless Communications Networks – Research Challenges and Opportunities
John E. Smee, Ph.D.
Director, Engineering
Qualcomm Research
NITRD Workshop
Washington, DC
9/20/12
Data Traffic Growth
10–12x Mobile data traffic projected to grow
from 2010–2015
1000x Potentially up to
from 2010–2020
New Techniques Network Offload More Spectrum Het Nets
Reshaping Industries
Another Wave of Wireless Growth Coming
Health Care Energy
Auto Banking/Finance
Media/ Entertainment
Advertising
Computing
Retail
Mobile Video is Expected to Grow Dramatically
in Next 5 Years
• Mobile video spending is
expected to reach ~$14B
by 2016
• 70% of all mobile traffic
will consist of mobile
video by 2016
Source: Strategy Analytics, March 2011
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
2011 2012 2013 2014 2015 2016
Global Mobile Video Spending Forecast ($Billions)
Advertising Spend
Transport and PremiumSpend
Wireless Network Challenges / Opportunities
• Growing need to optimize network capacity while
1. Attaining robust mobility
2. Supporting planned and ad-hoc deployments
3. Enhancing user experience and fairness
4. Leveraging licensed (e.g. 3G/LTE and unlicensed (WLAN) networks
5. Dealing with backhaul variability, interference dynamics in co-channel and adjacent channel deployments
6. Minimizing power consumption
7. Solving multi-radio coexistence/interference issues
Dimensions of Wireless Network Improvements
Leverage wider bandwidth Carrier aggregation across
multiple carriers and multiple bands
Leverage heterogeneous network topology (HetNet)
With advanced interference management (low power picocells with adaptive resource partitioning
and advanced receiver based devices)
Leverage more radio links, more antennas
Downlink MIMO up to 8x8, enhanced Multi User MIMO and uplink MIMO up to 4x4
Primarily higher data rates
(bps)
Higher spectral efficiency
(bps/Hz)
Higher spectral efficiency per coverage area
(bps/Hz/km2)
The Next Leap In Performance—Small Cells
Adding small cells like
Picocells, Femtocells,
and Remote
Radioheads
How do we get more capacity?
Bring Network Closer to Users—Small Cells
Optimizations Makes the Leap Even Bigger—Smart HetNets
Radio Link approaching theoretical limit
Better Techniques Such as higher order MIMO, Smart Networks
More Spectrum New bands, Re-farming Aggregate TDD spectrum
8
Dense Het Nets – heading to “1 user per “cell”
with Macros, Picos, Relays, and many Femtos
Wireless Networking Research
• Challenge
– Supporting huge traffic growth with economically viable deployments
• Perspective on Breakthroughs Needed
– Improvements in deployment, devices, networks
– Mix of planned and ad-hoc
– Robust and adaptive approaches
• Turning Research into Societal Impact
– Focus on extensibility and viability of solution
– Real world data coupled with analysis and simulation
– Pace of innovation in wireless industry device capabilities and wireless standards is very high -- Evaluate research in context of current standards and brand new models
• Appendix slides with examples of some
wireless network research areas
LTE-Advanced: Further Enhancement of LTE
Range Extension,
Resource Partitioning To Enable Plug-n-Play, Advanced
UE Receivers • Plug-n-Play Relays
• Picos & Femtos
• Remote Radioheads
• Self Organizing Networks
• Range Extension
• Resource Partitioning To Enable Plug-n-Play
• Advanced UE Receivers
• Wider bandwidth
• Higher peak rates
• Efficient use of fragmented spectrum
• Asymmetric UL/DL bandwidth
• eNBs collaborating to enhance performance through multi-antenna gains and interference reduction
HETEROGENEOUS NETWORKS
INTERFERENCE MANAGEMENT
CARRIER AGGREGATION
COMP MULTIPOINT TRANSMISSION
12
WiFi Advanced—Next Generation WLAN
5 GHz Band (802.11ac)
• Evolution of 11n WLAN, > 1 Gbps
• MU-MIMO—up to 8 antenna AP 20/40/80/160 MHz bandwidth
• On path to commercialization in multiple MSMs and QC-Atheros APs
900 MHz Band (802.11ah) Sensors, M2M, Internet of Things
600 MHz Band (802.11af) TVWS for Cellular Offloading
Low Cost Access, Hetnets and
WiFi-Direct Enhancements
60 GHz Band (802.11ad) Multi-Gbps Sync-n-Go
SET-TOP BOXES/MEDIA
SERVERS
TV
PICTURE-FRAMES/ OTHER DISPLAYS
CAMCORDERS/ CAMERAS
ONLINE CAMERAS
Multi-radio Revolution
Multiple wireless applications
eMBMS
Entertainment Location
GPS
Connectivity
C2K, UMTS,
LTE
WWAN Voice/Data
Concurrent multi-radio operation is becoming the norm…
on capable devices, and
evolving usage models
Traffic Management-- Connectivity Engine for
Smart Interface Selection
3G/LTE
?
Wi-Fi
Radio Conditions
Policies
Congestion
Latency & Bandwidth
QoS, RSSI, FER
Battery Life etc.
Automatic selection of the best radio based on:
• Operator Policies • Multi Radio Environment • Application Requirements • User Preferences
Seamless offload between 3G/LTE and Wi-Fi
• IP Flow Mobility with DSMIPv6 • Seamless Handovers
Automatic Radio Selection Algorithms
Wi-Fi ACCESS POINT
BASE STATION
Integration of WiFi into 3G/4G Allows
Better Load Balancing
• Standalone WiFi offers opportunistic offloading for mobile traffic
– Combined small cells and WiFi offers best overall coverage, capacity and user
experience
• Control plane interworking will enable the management of WiFi
access via LTE/UMTS
– Allows more dynamic and reliable control of offloading
• User plane interworking will enable WiFi as an additional carrier to be
aggregated with LTE
– Options of bearer-level or packet-level aggregation based on node and
backhaul type
COMBINED PICO/WIFI
TM
WiFi for indoor and hotspot offloading
Adaptive Interference Management Adapts to
Network Changes And Actual Network Load
1Advanced adaptive interference management : enhanced time-domain adaptive resource partitioning with enhanced RRM/RLM and advanced receiver devices
Provides network load balancing
Benefits all Hetnets—but necessary for dense HetNets
Adapts to typically uneven load that changes with time and location
Heavy Load
Medium Load
Light Load
Adapts to added nodes, like Picocells
Hyper-dense Network Using More Spectrum
To Accommodate Future Traffic Growth
More Capacity with 100’s of MHz Spectrum
And Small Cell Densification
WIDE AREA SPECTRUM 700–2600 MHz
For macro and initial small cell deployment
LOCAL AREA SPECTRUM 3–6 GHz
Hotspot Capacity Boost
BRING NETWORK CLOSER TO USER FOR
NEXT LEAP OF PERFORMANCE
18
Interference Channels – Communications/Information Theory challenge to Turn Theory into Practice
Transmission rate control to avoid bursty interference
If not, rate can gravitate to the worst
HetNet Interference Management
• LTE Rel-10/11 eICIC and advanced receivers offer inter-cell
interference management
– Macro and small cells use Almost-Blank Subframe (ABS) for resource partitioning
– Advanced UE receiver suppresses the residual interference in ABS
• Performs cancellation of common signaling: CRS/PSS/SSS/PBCH
Small cell
Cell Range Expansion Enabled by eICIC and advanced receiver
Subframes reserved for Macro
Macro DL
Small Cell DL
Almost Blank Subframes
Time-Domain Resources Subframes reserved for
small cell CRE region Subframes for small cell center region
Time Domain Partitioning Example
Additional Receiver Enhancements
for More Flexibility and Gains
• Further enhancement of UE advanced receiver provides flexibility and capacity gains for eICIC
– Allow control and data transmission in ABS not subjected to eICIC partitioning
– Recover the dimension loss due to ABS subframe partitioning
• Allows Macro to transmit control and data in subframes where small cells serve CRE UEs
– Increase uplink capacity • Decouple eICIC TDM partitioning pattern for UL and DL
Subframes reserved for Macro
Macro DL
Small Cell DL
Almost Blank Subframes (ABS)
Subframes reserved for small cell CRE region
SIB1/Paging and associated control channels (PCFICH & PDCCH) is allowed in ABS
Subframes serving small cell CRE enabled by enhanced receiver
Interference Enhanced
Interference Cancellation
LTE C
arrier #5
LTE C
arrier #4
LTE C
arrier #3
LTE C
arrier #2
LTE C
arrier #1
Aggregated Data Pipe
Carrier Aggregation Leverages All Spectrum Assets
Aggregate spectrum within a band to create a fatter data pipe
Aggregate across spectrum bands
Aggregate more downlink capacity— supplemental downlink (unpaired spectrum)
Enhances heterogeneous networks (multiple carriers)
Aggregation within band E.g. 2.6 GHz
10 MHz
Macro Pico
Carrier 1
Carrier 2
Pico
Example: Carrier 1 used for wide area macro coverage, but also by picocells, carrier 2 used by all nodes, but with lower power around macrocell
10 MHz
Supplemental Downlink E.g. 700MHz
LTE Multi-Flow Enhances Carrier Aggregation(CA)
• Packet-level aggregation using fast backhaul allows choosing serving cell for each IP packet based on scheduling on each cell
• Bearer-level aggregation for non co-located nodes relies on per bearer decision where to serve each IP packet
Improved User Experience
• Extend CA across non co-located nodes
• Agile connection to nodes in enhanced layer
Efficient Load Balancing
• Utilize unused capacity across multiple nodes
• Improved overall system capacity
Mobility
Robustness
• Stable connection to macro base layer
• Reduced signaling load to core network for nomadic UEs
Opportunistic Small Cell Operation For Reduced
Interference And Energy Efficiency
• A small cell can be put into dormant mode when there is no active users nearby
– Reduce common channel interference to neighboring cells and power consumption
– Periodically monitor uplink signals from connected UEs served by macro or neighboring cells
• Transition into active mode when needed so UEs can be attached to the cell
S2 in dormant mode; No DL transmission
Macro S1 S2
S2 detects nearby connected UE
S1 S1 S2 S2
S2 transitions to active mode and
starts to serve UEs
Opportunistic Relays For Backhaul Constraints
Relay Relay
Core Network
– Relay uses existing licensed spectrum for backhaul link
• Backhaul is provided by a LTE link to a macro or pico cell
• Allows flexible site selection regardless of traditional backhaul availability
• Reduce backhaul cost and operating expenses
– Smart utilization of resources allows Relays to offer capacity gains
• Allows for more flexibility to densify network
• Opportunistic operation further reduces interference and power
consumption
A New Network Deployment Model:
Open Access Neighborhood Small Cells (NSC)
25
LOW COST DEPLOYMENT
• Leverages existing sites and backhaul
• Minimal CapEx and OpEx
• Simple plug-n-play
MORE SPECTRUM
• Can use high frequency bands due to smaller coverage area requirement
HIGH CAPACITY
• Huge capacity gains both for indoor and outdoor users
• At high density each small cell serves to one user
Dense Urban Neighborhood Small Cells Simulation Assumptions
Red: 2 story bldg Blue: 3 story bldg
Green: 4 story bldg Cyan: 5 story bldg
Yellow: 6 story bldg
Dense-Urban Area (Simulation with Apartment Buildings)
Black star: Small Cell
Magenta Circle: Mobile
Blue circle: Macrocell
met
er
Notes: a) Small cells are randomly dropped in a apartment statistically
independent of other small cell locations b) At the most one Small Cell is dropped in any apartment
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
Exceeding 1000x Capacity Gain With Dense
Neighborhood Small Cells And More Spectrum
• 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 • 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).
(360 small cells)
0x
200x
400x
600x
800x
1,000x
1,200x
1,400x
1,600x
1,800x
0% 10% 20% 30% 40% 50%
DL
Me
dia
n T
hro
ugh
pu
t G
ain
(x)
Small cell Penetration (%)
DL Median Throughput Gain (LTE, dense urban, 100 MHz small cells in 3.5 GHz, relative to
macros only) 25 UEs/macro 200 UEs/macro
(72 small cells)
1000x capacity at 20% small cell penetration
Qualcomm Confidential and Proprietary — Restricted Distribution - DO NOT COPY
MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION —
• Qualcomm Confidential and Proprietary
• Not to be used, copied, reproduced in whole or in part, nor its contents revealed in any manner to others without the express written permission of Qualcomm.
• Restricted Distribution: Not to be distributed to anyone who is not an employee of either Qualcomm, or a subsidiaries of Qualcomm, without the express approval of Qualcomm’s Configuration Management.
• Qualcomm is a registered trademark of QUALCOMM Incorporated in the United States and may be registered in other countries. Other product and brand names may be trademarks or registered trademarks of their respective owners.
• MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION This technical data may be subject to U.S. and international export, re-export, or transfer (“export”) laws. Diversion contrary to U.S. and international law is strictly prohibited.
• Copyright © 2012 QUALCOMM Incorporated. All rights reserved.
research.qualcomm.com
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