1. Consideration on Technical Candidates for IMT-Advanced
Date: April 7th~8th, 2008
Agenda Item: 3
Source: LG Electronics, Inc.
3GPP RAN IMT-advanced Workshop

2. Overview of Target Features in IMT-advanced
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

3. Main Features in IMT-advanced
Service Perspective
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 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

4. Provisional View for IMT-advanced Requirement in ITU-R WP5D
Deployment environment
Requirement Parameters
Indoor
Microcellular
Base Coverage Urban
High Speed
Cell Spectral Efficiency
(bps/Hz/cell)
DL (4x2) 3
2.6
2.1 1
UL (2x4/1x4)
2.5/1.5
2/1.3
1.7/1.2
0.7/0.6
Peak Spectral Efficiency
DL (4x4/4x2)
10/7
5/2.5
Bandwidth (MHz)
20 or 40
Cell Edge Throughput
(bps/Hz) DL
0.1
0.075
0.08
0.05 UL
0.03
0.02
Latency (ms)
C-plane
100
U-plane 10
Handover Latency (ms)
Intra-freq.
[25/30]
Inter-freq.
N/A
Inter-sys.
Mobility class
Stationary
Pedestrian
Vehicular
Source: ITU-R WP5D IMT.TECH document, Feb. ’08 .

5. Overall Company Views on 3GPP RAN Specification of IMT-advanced
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

6. System Comparison between 3GPP LTE and IMT-advanced (1/2)
Peak Spectral Efficiency
Almost equal or better peak data rate potential of E-UTRAN compared with the related requirements of IMT-advanced
Cell Spectral Efficiency
Higher cell spectral efficiency requirement of IMT-advanced than performance of E-UTRAN in both uplink and downlink
System
Requirement Parameters
3GPP LTE
IMT-advanced
Peak Spectral Efficiency
(bps/Hz/cell) 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)
System
Requirement Parameters
3GPP LTE
IMT-advanced
ISD = 500m
ISD = 1732m
Microcellular
Base Coverage Urban
Cell Spectral Efficiency
(bps/Hz/cell) 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)
Source:
ITU-R WP5D IMT.TECH document, Feb. ’08
3GPP RAN1 R , May ’07

7. System Comparison between 3GPP LTE and IMT-advanced (2/2)
Cell Edge User Throughput
Higher cell edge throughput requirement of IMT-advanced than performance of E-UTRAN in both uplink and downlink
Latency
Equal or better requirement of E-UTRAN than that of IMT-advanced including handover latency
System
Requirement Parameters
3GPP LTE
IMT-advanced
ISD = 500m
ISD = 1732m
Microcellular
Base Coverage Urban
Cell Edge User Throughput
(bps/Hz/user) DL
0.08 (4x4)/0.06 (4x2)
0.08 (4x4)/0.05 (4x2)
0.075 (4x2)
0.06 (4x2)
UL (2x4/1x2)
0.01 (2x2) /0.024(1x2) /0.052 (1x4)
0.0044(1x2) / (1x4)
0.05 (1x4)
0.03 (1x4)
System
Requirement Parameters
3GPP LTE
IMT-advanced
Latency (ms)
C-plane
100
U-plane 5 10
Source:
ITU-R WP5D IMT.TECH document, Feb. ’08
3GPP RAN1 R , May ’07
3GPP TS25.912

8. 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
Network scalability
System inter-operability
Enhanced mobility support
Etc.

9. 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

10. Multi-hop Relaying (2/2)
Expected Trade-off
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
Benefits
Drawbacks
Coverage extension
Throughput/capacity improvement
New killer application/service
System complication
Enlarged control/signaling overhead
Large change factors from the
current 3GPP LTE spec
vs.

11. 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

12. Backward Compatible Co-existence of LTE and LTE-advanced
Smooth Migration toward LTE-advanced on LTE Carriers
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 LTE-advanced
Bandwidth aggregation capability of LTE-advanced
Freq
Freq
LTE
LTE-advanced
LTE
LTE-advanced
LTE
LTE Carrier
LTE Carrier
LTE-advanced
Time
Time
TDM-based allocation concept
FDM-based allocation concept
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
Improved uplink cell-edge performance
and/or coverage extension
Flexibility restriction in new system design
More guard band overhead and
limited bandwidth utilization

13. Bandwidth Aggregation
Motivation
Higher data rate support
Co-existence of LTE in wider carrier bandwidth of LTE-advanced
Basic cases
Consideration Points to Be Further Investigated
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
Case 1: Contiguous BW aggregation
Single or multiple Tx/Rx RF operation
Single or multiple physical layer processing under the single MAC/RRC
Case 2: Separate BW aggregation
Multiple (or single) Tx/Rx RF operation
Multiple (or single) physical layer processing under the single MAC/RRC

14. Multi-cell MIMO: Type 1 (DL/UL Cooperative MIMO)
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
eNodeB
eNodeB
Multi-cell MIMO: Type (DL/UL Cooperative MIMO)
Enhanced DL/UL MU-MIMO
Multi-cell MIMO: Type 2
(Adaptive Precoding/Beamforming)
UL Cooperative MIMO
Relay Node
Relay Node
Wireless single-/multi-antenna transmission
Interfernece

15. 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

16. 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
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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17. 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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18. Thank you !!!
LG, Life’s good