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CONTENTS
• Progress of TD-LTE network
• Challenges for further development
• Expectation for further evolution
• Summary
2014/10/20
Progress on CMCC’s TD-LTE network
Base Station
(10^4) 48
>50
2014 up to now 2014 Total
Terminal (10^8)
0.22
1.0
Subscriber (10^4)
2957
5,000
2014 up to now 2014 Total 2014 up to now 2014 Total
Network
Largest LTE network at the end of 2014
International roaming with 8 operators
Traffic
Have balanced 13.4% traffics
4G ARPU:2 X average
4G DOU:6 X average
Customer
Much shorter access Latency to Internet
Better experience for users with video services
Globalization
41 TD-LTE commercial network globally
Guarantee roaming based on robust ecosystem
6:6:2
Extended Scale
Field Test 2012 Phase 1, 2013
2012 2013
Phase 2,2014
2015
Configuration
Multi-antenna
20M/10MHz,
2DL:2UL,3DL:1UL
TM3/8 adaptation
IRC
UL MU-MIMO
RRM Mobility
Static ICIC
Interworking 4G/3G data
reselection
CSFB to GSM
4G/3G data
redirection
VoLTE with
SRVCC
8Rx UL CoMP
Others SON SON
enhancement
300km/h high-
speed scenario
Deployed Features Features deployed in the network
Features in Trial
eMBMS,
service Caching
8Rx TM9/DL
CoMP
Wireless big data
Carrier agg.,
Relay
eMBMS
2014
Band 39:TDD
825 835 870 880 889 915 934 960 909 954 1710 1755 1785 1850 1735 1830 1880 1805
Band 3: FDD Band 3: FDD Band 8: FDD Band 8: FDD FDD FDD
2025 2010
B34: TDD
2400 2300
Band 40: TDD
2130 2125 2170 2110
Band 1: FDD
1920 1955 1980 1935
Band 1: FDD
1880 1900 2635 2575 2690 2500
Band 41: TDD
1940 2145 2320 2370
CM
CC
TD
L
CT
CD
MA
CT
CD
MA
CM
CC
GS
M
CM
CC
GS
M
CM
CC
GS
M
CM
CC
TD
S
CM
CC
TD
L/T
DS
CM
CC
GS
M
CM
CC
TD
L/T
DS
CU
GS
M
CU
GS
M
CU
GS
M
CU
GS
M
CT
/CU
PH
S
CT
CD
MA
2x
CT
CD
MA
CU
WC
DM
A
CU
WC
DM
A
TD
D
Converged FDD/TDD networking is a sufficient way for MBB
FDD
Band 8: 900MHz 2x20MHz for GSM
Band 3: 1800MHz 2x25MHz for GSM
TDD
Band 34: 2010-2025MHz for TD-SCDMA
Band 39: 1880-1900MHz for TD-SCDMA&TD-LTE
Band 40: 2320-2370MHz for TD-SCDMA&TD-LTE (indoor only)
Band 41: 2575-2635MHz for TD-LTE
Note: 1785-1805MHz has limited applications for broadband wireless access,
e.g. providing BWA service in some airports
1.Coverage-based
mobility management
Object: Balance the load and
increase bandwidth efficiency
2. Load-balancing
handover
Converged LTE TDD/FDD networking is in test
Object: Guarantee coverage and
seamless service continuity
TDD
FDD
3. LTE TDD/FDD
joint operation
Object: utilize FDD/TDD resources
simultaneously and maximize
bandwidth efficiency
For the first 2 phases, the industry is mature enough for commercial deployment
The convergence can be further enhanced by deploying TDD/FDD joint operation
in the near future
Industry is mature
enough for commercial
deployment
Well supported by both network equipment/terminal industry, ready for commercial deployment. All
5-mode or 4-mode smartphones can support handover between TD-LTE and LTE FDD
since H2 of 2013
Already been enabled in more than 6 commercial networks
Phase I: Coverage-based Mobility Management
Chipset
Network Equipment
Operator Enabled in>6 commercial networks
Industry & Commercial Deployment Status
Idle Reselection success rate: 100%, latency~31 ms
Handover success rate 100% control plane latency : 16~18 ms user plane latency:55~56 ms
Performance at the same level as inter-frequency handover within TDD or FDD
Performance in China Mobile Hong Kong (CMHK)
…
…
Network equipment: well supported, ready for commercial deployment
Terminal: no additional requirement needed as long as UE supports TDD/FDD handover,
well supported
In
Phase II: Load-Balancing Handover
Industry Status
Inter-Vendor Load-Balancing:Different vendors may have different definitions for
load evaluation/user selection/user transfer/load information exchange, which
might degrade the performance. Definitions needs to be unified to enhance user
experience/network efficiency during load-balancing handover
Notes on Commercial Deployment
eNB1 eNB2
Load eval.
User Selection &load transfer
Response Status Request
Response Status Response
Response Status Update
Handover Request
Handover Response
Standardization regarding inter-vendor
load-balancing have been done in both
3GPP and NGMN. Industry promotion can
be done when needed
Scenario 1 TDD-FDD co-baseband, single vendor
Scenario2 TDD-FDD non-co-baseband, multi-vendor
Solution: TDD-FDD Carrier Aggregation Solution: TDD-FDD Dual Connectivity
Non-ideal backhaul
(e.g., X2)
FDD Carrier
TDD Carrier
TDD eNBFDD eNB
TDD/FDD
Dual-mode UE
(Double Tx)
FDD Carrier
TDD Carrier
TDD/FDD
Dual-mode eNB
TDD/FDD
Dual-mode UE
(Single Tx)
Phase III: Joint Operation
• Peak data rate (theoretical): 20M TDD+20Mx2 FDD = 260 Mbps • Dynamic load balance (CA, ~ms level): 10% ↑ cell average throughut (simulation)
30% ↑ cell edge throughput (simulation)
Benefits
Standardization Progress & Industry Status
• Standard Progress: Both TDD-FDD CA and Dual Connectivity are ongoing in 3GPP R12; • Industry status: Initial PoC and field trial has been done by some network vendors;
Freq.
Finished B8(900M)+B40(2.3G) B1(2.1G)+B42(3.5G) B19(850M)+B42(3.5G)
Ongoing B1(2.1G)+B41(2.6G) B3(1.8G)+B40(2.3G) B26(850M)+B41(2.6G) B3(1.8G)+B41(2.6G)
Industry Status of TDD-FDD Joint Operation
TDD as Pcell:DL peak data rate 250Mbps
FDD as Pcell:DL peak data rate 250Mbps
PoC demo of TDD-FDD CA in MAE 2014 Field Trial of Dual connectivity in Shanghai
MSA enhances the peak data rate and cell-edge throughput
MSA balance load between Macro and small cell by load and inteference condition
Peak data rate Cell-edge throughput
Balance by load Balance by interference
• 20M TDD config.2 (band41)+ 20*2 FDD(band8); • Both TDD and FDD can be configured as Pcell;
TDD-FDD CA enhance peak data rate
• 10M TDD (3.5G)+ 10*2 FDD (2.6G);
CONTENTS
• Progress of LTE network
• Challenges for further development
• Expectation for further evolution
• Summary
2014/10/20
New Challenges for CMCC
• High data rate
• Traffic booming
• Delay sensitive
• Always online
• Seamless mobility
• ……
2014/10/20
• Densified deployment
• Heterogeneous architecture
• Multi-RAT co-existence
• Various terminal types
Challenges for TD-LTE Network Coverage
Challenges
High frequency band cause big path loss
Insufficient deep indoor coverage,high cost by deploy DAS
Co-exist of multi-band
and multi-system need
to be considered
Hard to obtain or to get site locations for macro cells
Flexible eNB types would be helpful !
Flexible eNB types is the way for deep coverage
Macro cell Micro cell Pico/Nanocell Nanocell
Macro coverage dead spot and
hot spot coverage Home coverage
Public indoor coverage
Macro
RRU
Distributed macro
Micro RRU
BBU
Integrated micro
Distributed micro Relay
Enterprise
Nanocell
Residential
Nanocell
Micro repeater
Active
antenna
BBU
Pico RRU
Small Cells
Small Cells become extremely important
Mobile data traffic exploding
High capacity demand
Multi-layer architecture
More small cells have to be deployed
• ~5X small cells vs. macro cells
without new frequency introduced
• ~3X small cells vs. macro cells
with new frequency introduced
Urban Village/Town
Rural
Microcell
DAS Pico/Nanocell
Microcell
Macrocell
Macrocell
Macrocell
Relay
Relay
Micro
Micro Pico/nano
Pico/nanocell
Challenges for Small Cell application
More dependent on SON Complex interference control
& mobility management
Others?
Multi-mode support O&M
Business model Cost control
CONTENTS
• Progress of LTE network
• Challenges for further development
• Expectation for further evolution
• Summary
2014/10/20
Key Issues Remained for Further Study
Spectrum
Explore the potentialities of convergence, e.g.
multi-RAT coordination, TDD/FDD joint
operation based on CA and DC etc.
Find new resources, e.g.
unlicensed
Network Capability
Deep Coverage
Voice and SON
Improve the deep coverage,
e.g. dense small cell
Improve the special coverage,
e.g. high rise building, etc.
Improve the capability , e.g.
UL64QAM, multiple CC
aggregation
Automatically respond the
metrics required by operators,
e.g. SINR, VoLTE related
Voice related optimization, e.g.
CSFB, VoLTE, etc.
More accurate and service-aware
management, e.g. RAN caching,
traffic localization, etc.
Converged Network to boost the user experience
Spectrum Flexibility
III:FDD/TDD Joint Operation
Evolution
I:Coverage Based
Load Increasing
II:Load Balancing
MRC (Multi-RAT Connectivity)
The first and second phase of FDD/TDD convergence has been tested, and coverage
based handover and load balance could be introduced
WLAN
MRC Controller
3G 2G
Traffic Steering Joint Radio Resource Allocation
4G
Multi-RAT Management
CA & DC
Licensed Assisted Access
• How to use the unlicensed band?
2014/10/20 20
Carrier Aggregation is supposed to be the only solution for LAA at least in R13
Carrier Aggregation Standalone
Perform interference handling Avoid congestion on unlicensed band Guarantee QoS Separate signaling and data
Possible for normal UE to deploy LTE Hard for interference handling
Licensed Band Unlicensed Band
YEAR Spectrum
Requirements
China 2015 570-690MHz
2020 1490-1810MHz
U.S. 2014 822 MHz
Australia 2020 1081 MHz
Russia 2020 1065 MHz
GSMA 2020 1600-1800MHz
ITU 2020 1340-1960MHz
• 687MHz has been allocated in China
• Not so much potential spectrum available for IMT below 6GHz
• Spectrum will be the most important aspect for IMT development
• Unlicensed spectrum requirements
UL Enhancement
• Spectral efficiency limitation for uplink transmission – E.g., maximum 16QAM or 64QAM, which limits higher transmission spectral efficiency
regardless higher transmission power
– Tx EVM limits higher SINR at receiver side, which limits higher transmission spectral efficiency
16QAM,8Rx
For example, ~90% users has SINR higher than MCS_16 - Assuming maximum 16QAM, 1Tx8Rx
~50% users has SINR higher than MCS_16 - Assuming maximum 16QAM, 1Tx2Rx
• Possible enhancement, especially for good SNR users • Uplink Dual Transport Blocks (TB) transmission for 1Tx UE (UL_1Tx_dualTB) can
offer gains from uplink peak data rate and spectral efficiency perspective[1]
• Utilization of uplink 64QAM (UL_64QAM) [2] Note:
[1] RP-140663 New Work Item Proposal: support of uplink 64QAM in LTE Huawei, HiSilicon
[2] RP-141287 Uplink dual transport block transmission to enhance uplink performance CMCC
3D-MIMO
UMa/UMi Indoor
RX
RX
RX
TX
Highrise
2D-MIMO 3D-MIMO
Increased receive energy
Reduced inter-cell-interference
Serve more users simultaneously
Wide beam in elevation domain Narrower beam in elevation domain
Fixed downtilt Larger downtilt for cell-center user
Can separate users in horizontal domain only
Can separate users in both horizontal and vertical domain
VoLTE
OTT
M2M
Video
The aim is to improve the radio access control and user data transmission in a
differentiated manner on a service-aware basis.
Service-Aware Management
• SCM: Smart Congestion Management
•Differentiate the radio access probability Control signaling access
enhancement
•UPCON: User Plane Congestion management
•Differentiate the user data transmission
User data management optimization
• LIPA/SIPTO
•Differentiate the local service provision and routing Service localization
• Popular service cached in RAN side
•Reduce backhaul and Core load RAN Caching
•Adaptive service distribution and convergence
•Consistent service experience Service continuity
• Finer gratuity of QoS handling w.r.t. signaling and user data treatment
Small Cell Enhancement
256QAM
Small Cell On/off and discovery
Dual connectivity
Radio-Interface Based Synchronization
34% peak throughput gain vs. 64QAM
Average spectrum efficiency 16%↑
Maximum +/- 1.5us timing error supporting 4 stratum levels Supporting network listening between inter-vendor small cells
User peak throughput 90%↑
Better user mobility Energy saving, interference mitigation, off-loading Average spectrum efficiency 10%↑
Non-idea backhaul
(e.g.,X2)
User Plane D
ata
User Plane Data
Macro eNBSmall cell
Carrier 1
Carrier 2Small cell cluster
Cell discovery
Small cell on/off
· Cell 1 (on) · Cell2 (off) · Cell 3 (off) · Cell 4 (on)
· Cell 5 (off)
Macro eNB
256QAM
1 2
3 4
5
Dual Connectivity
MDT Enhancement
• Motivation • VoLTE: Deployment of VoLTE of
most operators is this year • SINR: Be used to detect
coverage problems and access network performance
• Towards eMDT • Specify VoLTE and video related
measurements and corresponding collection.
• Specify SINR-like measurement and collection
• The general motivation of MDT
– Decrease the cost of drive testing
– Avoid additional emission of CO2
– Extend time and space for drive testing
Voice Related Enhancement
CSFB ➡ VoLTE
• CSFB: UE automatic fast return after CSFB to GSM – Save the delay of returning LTE (about
0.4-1.9s), while the cell reselection delay is more than 40s
– Standardization needed, both CSFB to GSM and 3G
• VoLTE SPS: Unsatisfied Performance – Standard limitation on max MCS (below 15) – Scheduler has to be prepared for long term (e.g.200 ms) RF condition thus
sacrifice too much radio resource – Clarification needed for SPS + C-DRX
• eSRVCC: long preparation time & interruption time – prep time(asking 2G for resource reservation) takes 1 - 2s due to long signaling chain, making HO vulnerable to failure – User plane interruption time up to 800ms, optimization needed
CONTENTS
• Progress of LTE network
• Challenges for further development
• Expectation for further evolution
• Summary
2014/10/20
Summary
• Converged FDD/TDD networking becomes a trend
• Heterogeneous network is the flexible way for deep coverage and capacity expansion
• Further enhancement is expected to
– boost the network capacity and user experience
– simplify the network optimization and maintenance
2014/10/20
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