NTT DOCOMO, INC., Copyright 2013, All rights reserved. 1
RAN Evolution
Beyond Release 12
Takehiro Nakamura
NTT DOCOMO, INC.
LTE World Summit 2013
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 2
FRA concept
Future Radio
Access
Massive device
connectivity
Support for traffic
explosion
QoE for various
applications
Intelligent network with
low cost & high robustness
Future Radio Access (FRA) will provide a total solution
to satisfy the requirements by future drivers
Beyond 500x in 10 years Gbps-experience data rate,
Reduced latency,
Battery saving
Reduced control signaling,
More simultaneous pipes
Support of diverse environments
(small cells & higher frequency bands),
Energy saving
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 3
Capacity
Higher system capacity:
Report ITU-R M.2243 (IMT.UPDATE): 1530 times traffic growth is envisioned between 2010 and 2015
Mobile data traffic is continuously growing over DOCOMO network
Approx. 1.6 times per year (2004 2009)
Approx. 2 times per year (2010 2011)
Approx. 12 times traffic growth is envisioned between 2011 and 2015
Mobile data traffic is
expected to grow to
x500~x1000 in 10 years
(2010 2020)
Traffic growth forecast
Tra
ffic
volu
me
2010 2011 2015
~ 2x
Fiscal Year
~ 12x
The main drivers are smartphones, video services and high-speed data access
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 4
Directions of evolution: The Cube
Spectrum extension
Network densification
Required performance
Spectrum efficiency
Current capacity
New cellular concept for cost/energy-
efficient dense deployments
Non-orthogonal multiple access
Study for new interference scenarios
Dense urban
Shopping mall
Hotspot
Cellular network assists
local area radio access
Efficient use of higher spectrum bands
Tx-Rx cooperative access technologies
A set of radio access technologies is required
to satisfy future requirements
Existing cellular bands Higher/wider frequency bands
Frequency
Very wide Super wide
Controller
TRx
TRx
TRx
TRx
TRx
TRx
TRx
TRx
3D/Massive MIMO,
Advanced receiver
WiFi
Traffic offloading
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 5
Evolution paths for FRA P
erf
orm
ance
~2015
Rel-10/11
Rel-8/9 Pico/Femto
LTE
LTE-Advanced
LTE-B
Rel-12/13
WRC-15
Potential
New RAT
Big gain
~2020 Year
Future Radio Access
LTE-C
Rel-14/15,
Further LTE enhancements Macro-assisted small cell enhancement
(Phantom cell) Further general LTE enhancements
Potential new RAT Should prioritize the achievement of more
big gains over backward compatibility Consider new spectrum allocations of
WRC-15 and beyond Some technical components may be
applied to further LTE enhancements
Macro-assisted small cell enhancement
(Phantom cell)
Further LTE
enhancements
CA/eICIC/CoMP
for HetNet
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 6
Combined usage of lower and higher frequency bands Higher frequency bands become useful and beneficial!
FRA technical concept
Existing cellular bands (high power density for coverage)
Higher frequency bands (wider bandwidth for high data rate)
Frequency
Very wide
(e.g. > 3GHz)
Super wide
(e.g. > 10GHz)
FRA technical concept
Future cellular
enhancements
New RAT for
higher frequencies
No coverage issue any more
Can provide very high throughput using wider
bandwidth
Big offloading gain from existing cellular bands
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 7
Phantom cell concept
Proposed macro-assisted small cell Phantom cell
Split of C-plane and U-plane between macro & small cells in different bands
Existing
cellular bands
Higher
frequency bands
Macro cell
Phantom cell
C-plane: Macro cell maintains
good connectivity and mobility
using lower frequency bands
U-plane: Small cell provides higher
throughput and more flexible/cost-
energy efficient operations using
higher/wider frequency bands (RRC: Radio Resource Control)
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 8
Massive MIMO BF gain
Beamforming (BF) gain with massive antenna elements
Massive MIMO
Massive MIMO in higher frequency bands Compensation of increased path loss & Improved spectrum efficiency
Improved coverage and spectrum
efficiency for super dense small cells
in higher freqeuncy bands
2GHz
min
L
G
Increasing number of antenna elements by X
1) Increase of BF gain by X
2) Decrease of BF width by 1/X
4GHz
min /2
2G
L
(/2)/2 /2
Distance between antenna
elements /2 reduced by half doubles the number of antenna
elements
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 9
NOMA utilizes path loss difference
for efficient user multiplexing
Non-orthogonal multiple access (NOMA) More efficient multiple access scheme
Non-Orthogonal Multiple Access (NOMA)
Why NOMA? Multiple access using interference cancellation itself is very old technology (for uplink in particular)
Evolution of device processing capabilities for interference cancellation
Moores law: 100x processing power after 10 years
In OFDMA, frequency-domain signal processing becomes possible
Exploitation of path loss difference among users
Multi-path fading was exploited by OFDMA,
but path loss still needs to be further exploited
W-CDMA LTE FRA
Radio resource
allocation
Non-orthogonal
(CDMA)
Orthogonal
(OFDMA)
Orthogonal (OFDMA)
+ Superposition/Cancellation
(NOMA)
Link adaptation Fast TPC (TPC: Transmission Power Control)
AMC (AMC: Adaptive Modulation & Coding)
MUPA/AMC (MUPA: Multi-User Power Allocation)
Multiple access
image
f f f
Orthogonal between users Non-orthogonal assisted
by power control
Superposition & interference cancellation
More details on NOMA concept and initial results are presented in this WS.
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 10
FRA real-time simulator
The potential perfomance gains of applying key FRA technologies are demonstrated using FRA real-time
simulator.
Demo Scenario Spectrum extension x NW densification
Efficient exploitation of higher
frequency bands using small cells
Key technology for small cells Massive MIMO
Key technology for macro cells Non-orthogonal Multiple Access (NOMA)
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 11
FRA real-time simulator
Macro Cell Only Macro + 12 small Cells, 100 MHz [email protected] GHz
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 12
FRA real-time simulator
100 MHz [email protected] GHz 200 MHz BW@5 GHz 400 MHz BW@10 GHz
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 13
FRA real-time simulator
400 MHz BW@10 GHz 600 MHz BW@20 GHz With Massive MIMO
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 14
Summary
We presented our views on requirements and potential key techologies for Future Radio Access (FRA):
Macro-assisted small cell, i.e., Phantom cell, and Massive MIMO are promising approaches for higher/wider frequency
bands towards the long-term future
Non-orthogonal multiple access (NOMA) is a promising technology for future cellular enhancements
FRA technical concept
Future cellular
enhancements
New RAT for
higher frequencies
NTT DOCOMO, INC., Copyright 2013, All rights reserved. 15