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REV-080019
Consideration on Technical Candidates
for IMT-Advanced
3GPP RAN IMT-advanced Workshop
Date: April 7th~8th, 2008
Agenda Item: 3
Source: LG Electronics, Inc.
Outline
◙ Overview of Target Features in IMT-advanced
◙ Approach toward LTE-advanced from 3GPP LTE
◙ Technical View for Enabling Technologies and System
Design of LTE-advanced
 Multi-hop relaying
 Bandwidth Assignment
 Enhanced MIMO
 LTE technical items to be enhanced
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Main Features in IMT-advanced
◙ Service Perspective
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High quality mobile services
Enhanced peak data rate to support advanced services and application
Worldwide roaming capability
Compatibility of services within IMT and with fixed networks
Capability of interworking with other radio access systems
◙ Implementation Perspective
 A high degree of commonality of functionality worldwide while retaining the
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flexibility to support a wide range of services and applications in a cost
efficient manner
User-friendly applications, services and equipment
User equipment suitable for worldwide use
Source: Attachment 7.1 to Document 5D/97
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Provisional View for IMT-advanced Requirement in ITU-R
WP5D
Deployment environment
Requirement Parameters
Indoor
Microcellular
Base Coverage
Urban
High Speed
3
2.6
2.1
1
2.5/1.5
2/1.3
1.7/1.2
0.7/0.6
Cell Spectral Efficiency
(bps/Hz/cell)
DL (4x2)
Peak Spectral Efficiency
(bps/Hz/cell)
DL (4x4/4x2)
10/7
UL (2x4/1x4)
5/2.5
UL (2x4/1x4)
Bandwidth (MHz)
Cell Edge Throughput
(bps/Hz)
20 or 40
DL
0.1
0.075
0.08
0.05
UL
0.08
0.05
0.03
0.02
C-plane
100
U-plane
10
Latency (ms)
Handover Latency (ms)
Mobility class
Intra-freq.
[25/30]
Inter-freq.
N/A
Inter-sys.
N/A
Stationary
Pedestrian
Stationary
Pedestrian
Stationary
Pedestrian
Vehicular
Vehicular
High Speed
Source: ITU-R WP5D IMT.TECH document, Feb. ’08 .
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Overall Company Views on 3GPP RAN Specification of IMTadvanced
◙ Evolutionary Approach from 3GPP LTE Specification
 Very close potential of 3GPP LTE with target requirements of IMT-advanced
 Fast and efficient correspondence against the timeline of WP5D’s
specification and commercialization for IMT-advanced
◙ Careful Verification for Various Emerging Technology Candidates
 Feasibility at the commercial implementation time
 Accurate clarification for the trade-off between benefits and
overhead/complexity
◙ Efficient System Design for a New Value-added Service Creation
 Provisioning a technical background for development of killer applications in
IMT-advanced
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System Comparison between 3GPP LTE and IMT-advanced
(1/2)
◙
Peak Spectral Efficiency
System
3GPP LTE
IMT-advanced
DL
16.32 (4x4) / 8.64 (2x2)
10 (4x4) / 7 (4x2)
UL
4.32 (64QAM, 1x2) / 2.88 (16QAM, 1x2)
5 (2x4) / 2.5 (1x2)
Requirement Parameters
Peak Spectral Efficiency
(bps/Hz/cell)
 Almost equal or better peak data rate potential of E-UTRAN compared with the related
requirements of IMT-advanced
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Cell Spectral Efficiency
System
Requirement Parameters
Cell Spectral Efficiency
(bps/Hz/cell)
3GPP LTE
IMT-advanced
ISD = 500m
ISD = 1732m
Microcellular
Base Coverage
Urban
DL
2.67 (4x4)/1.87 (4x2)
2.41 (4x4)/1.85
(4x2)
2.6 (4x2)
2.1 (4x2)
UL
0.776 (2x2) /0.735(1x2)
/1.103 (1x4)
0.681(1x2) /1.038
(1x4)
2 (2x4)/1.3 (1x4)
1.7 (2x4)/1.2 (1x4)
 Higher cell spectral efficiency requirement of IMT-advanced than performance of E-UTRAN in both
uplink and downlink
Source:
• ITU-R WP5D IMT.TECH document, Feb. ’08
• 3GPP RAN1 R1-072580, May ’07
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System Comparison between 3GPP LTE and IMT-advanced
(2/2)
◙
Cell Edge User Throughput
System
Requirement Parameters
DL
Cell Edge User Throughput
(bps/Hz/user)
UL (2x4/1x2)
3GPP LTE
IMT-advanced
ISD = 500m
ISD = 1732m
Microcellular
Base Coverage
Urban
0.08 (4x4)/0.06
(4x2)
0.08 (4x4)/0.05
(4x2)
0.075 (4x2)
0.06 (4x2)
0.01 (2x2)
/0.024(1x2) /0.052
(1x4)
0.0044(1x2)
/0.0094 (1x4)
0.05 (1x4)
0.03 (1x4)
 Higher cell edge throughput requirement of IMT-advanced than performance of E-UTRAN in both
uplink and downlink
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Latency
System
3GPP LTE
IMT-advanced
C-plane
100
100
U-plane
5
10
Requirement Parameters
Latency (ms)
 Equal or better requirement of E-UTRAN than that of IMT-advanced including handover latency
Source:
• ITU-R WP5D IMT.TECH document, Feb. ’08
• 3GPP RAN1 R1-072580, May ’07
• 3GPP TS25.912
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Main Enhancement Factors of 3GPP LTE for Evolving
toward LTE-advanced
◙ Quantitative Enhancement Factors
 Uplink and downlink cell spectral efficiency
 Uplink and downlink cell edge user throughput
 Peak data rate and system latency
• Under the condition of a 3GPP’s decision regarding the superiority of a 3GPP
LTE-advanced to IMT-advanced requirement
◙ Non-quantitative Enhancement Factors
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Network scalability
System inter-operability
Enhanced mobility support
Etc.
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Multi-hop Relaying (1/2)
UE Peer-to-Peer Tx/Rx
Conventional UE-eNodeB Tx/Rx
• Direct inter-UE connectivity
• Autonomous ad-hoc network configuration
and management
• Conventional single-hop Tx/Rx between UE
and eNodeB as a basic connection scheme
Wireless link connection
eNodeB
Relay Node
Relay Node
Relay Node Tx/Rx
• Remote relay node Tx/Rx
• L1 baseband processing and RRM
• Coverage extension and throughput
enhancement
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Multi-hop Relaying (2/2)
◙ Expected Trade-off
Benefits
• Coverage extension
• Throughput/capacity improvement
• New killer application/service
Drawbacks
vs.
• System complication
• Enlarged control/signaling overhead
• Large change factors from the
current 3GPP LTE spec
◙ Consideration Points
 Things to be further investigated
• Verification for practical benefits against system overhand & complexity
• Smooth migration toward multi-hop relaying in addition to single-hop UE-eNB
transmission & reception
 Early-stage features of multi-hop relaying
• Max. 2 hop relaying, i.e. single relay node between UE and eNodeB
• Minimized impact on UE spec.
• No support of UE peer-to-peer ad hoc transmission & reception
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Bandwidth Assignment
◙ Consideration Points
 Backward compatible co-existence with LTE and LTE-advanced in IMT
carrier bands
• SI or WI creation in 3GPP RAN for most carrier BW candidates given by WRC’07
• Support of smooth migration from LTE toward LTE-advanced
 Support of wider system bandwidth in LTE-advanced for higher data rate
transmission
• Issue of the system BW of 20 or 40MHz on the system requirement
documentation of IMT-advanced in ITU-R WP5D
• Probable situation of using a more extended system BW for higher data rate
support
◙ Technical check points on implementation feasibility
 Potential of commercial-level RF filter
• Effective bandwidth range
 Potential of commercial-level ADC
• Sampling rate and quantization resolution
 Decoding complexity
• Channel decoding speed and required soft buffer size
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Backward Compatible Co-existence of LTE and LTEadvanced
◙ Smooth Migration toward LTE-advanced on LTE Carriers
Freq
Freq
LTE
Carrier
LTE
Carrier
LTE
LTE-advanced
LTE
LTE-advanced
LTE
LTE-advanced
Time
Time
FDM-based allocation concept
TDM-based allocation concept
• Improved uplink cell-edge performance
and/or coverage extension
• Flexibility restriction in new system design
• More guard band overhead and
limited bandwidth utilization
• Full transparency for UE Tx/Rx operation
• Full bandwidth utilization
• Large flexibility in new system design
• Relatively weak power utilization on
uplink cell-edge UE transmission
 Further investigation for other possibilities including spectrum sharing
◙ Co-existence of LTE in Wider Carrier Bandwidth of LTE-advanced
 Baseline: FDM-based legacy zone support
 Technical consideration points
• Bandwidth camping of LTE system according to the bandwidth size of LTEadvanced
• Bandwidth aggregation capability of LTE-advanced
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Bandwidth Aggregation
◙ Motivation
 Higher data rate support
 Co-existence of LTE in wider carrier bandwidth of LTE-advanced
◙ Basic cases
 Case 1: Contiguous BW aggregation
 Case 2: Separate BW aggregation
• Single or multiple Tx/Rx RF operation
• Single or multiple physical layer processing
under the single MAC/RRC
• Multiple (or single) Tx/Rx RF operation
• Multiple (or single) physical layer processing
under the single MAC/RRC
◙ Consideration Points to Be Further Investigated
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Feasibility of simultaneous multiple Tx/Rx RF processes
Maximum commercial-level RF BW capability
Implementation cost and complexity for multiple physical layer processing
Baseband decoding processing power
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Enhanced MIMO (1/2)
◙ Main Motivation
 Improvement of DL/UL peak & cell spectral efficiency
 Improvement of DL/UL cell edge user throughput by applying an enhanced MIMO
transmission considering multi-cell situation
◙ Technology Candidates
UL SU-MIMO & TxD using
multiple RF chains
Multi-cell MIMO: Type 1
(DL/UL Cooperative MIMO)
eNodeB
eNodeB
Multi-cell MIMO: Type 2
Enhanced DL/UL MU-MIMO
(Adaptive Precoding/Beamforming)
UL Cooperative MIMO
Relay Node
Relay Node
Wireless single-/multi-antenna transmission
Interfernece
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Enhanced MIMO (2/2)
 Number of antennas in an eNodeB and a UE
• Improvement of overall spectral efficiency
• Careful consideration of the required target performance and the feasible UE
capability for LTE-advanced
 Uplink single-user MIMO and transmit diversity
• Improvement of UL peak & cell spectral efficiency
• Issue points of UL SU-MIMO transmission scheme
– Antenna power balancing
– Low and uniform per-antenna PAPR
• Cost effective design for DL/UL control signaling
 Multi-cell MIMO
• Improvement of DL/UL cell edge user throughput as well as cell spectral
efficiency
• Downlink/uplink cooperative MIMO (Type1): Multi-cell/site MIMO transmission
and reception
– Precoding based dual-cell unicast transmission
– Enhanced MBMS transmission
• Adaptive precoding/beamformaing (Type 2): Evolved DL/UL MIMO transmission
scheme for inter-cell interference mitigation
– Enhanced DL/UL single-user MIMO
– Enhanced DL/UL multi-user MIMO
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LTE Technical Items to Be Enhanced (1/2)
◙ Downlink/uplink Inter-cell Interference Management
 Motivation
• Significant improvement in downlink & uplink cell-edge user throughput and cell spectral
efficiency
 Related LTE items
• DL/UL inter-cell interference coordination
• DL/UL inter-cell power control mechanism
 Consideration of relevant technologies
• Multi-cell MIMO technologies
• Dual-cell unicast transmission and fast cell-switching
• Multi-hop relaying, etc.
◙ Self-organizing & -optimizing Network
 Motivation
• Largely probable situation of using small remote eNodeBs for coverage extension and
throughput enhancement
• Mitigation of enlarged complexity/cost in deployment and network optimization for large
number of eNodeBs
 Consideration points
• Rel.8 work item initiation coming along with home eNodeB
• TBD whether further enhancement is necessary after investigating the specification results of
current Rel.8 work item
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LTE Technical Items to Be Enhanced (2/2)
◙ Multi-RAT Seamless Handover
 Motivation
• Enhanced requirement of inter-system interworking and its related mobility support
 Consideration points
• Extension level of inter-system interworking in addition to related Rel.8 work items
• Minimized impact on LTE-advanced specification
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Thank you !!!
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