Coordinated Multipoint Reception 2014-12-04 · LTE-Advanced Field Trial Coordinated Multipoint...
Transcript of Coordinated Multipoint Reception 2014-12-04 · LTE-Advanced Field Trial Coordinated Multipoint...
LTE-Advanced Field TrialCoordinated Multipoint Reception
Uwe Dötsch, Bell Labs
July-2010
2 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Motivation
Coordinated multipoint transmission / reception (CoMP)
� Candidate technology for LTE-Advanced (a.k.a. network MIMO)
� Enhance cell edge spectral efficiency
� More consistent QoS throughout the network
� Enhanced user experience
CoMP particularly promising in UL
� UE transmit power limitation at cell edge
� Coherent combining can be realized w/o changes of LTE air interface and
w/o changing the total number of antennas in the network
� Significant UL throughput gains observed in simulations
Objectives:
•Prove feasibility of UL CoMP in realistic LTE environment
•Quantify macro-diversity gains of UL CoMP in the field
3 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
UL CoMP basic principle
Exchange over X2 interface
CoMP with 3 sites
CoMP with 2 sites
Exchange over X2 interface
� UL signal from one user isreceived in multiple cells
� Radio resources allocatedmultiple times, i.e. multi-userMIMO over multiple cells
� Coherent combining of UL signals in a central unit
� Transfer of I/Q samples orsoft bits to the central unit
� Over X2 interface or using a distributed RF architecture
LTE eNB
4 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Framework
Field trials within EASY-C research project
� UL CoMP drive test conducted in Berlin testbed
Partners in Berlin trial:
� Alcatel-Lucent Bell Labs: LTE eNB central processing
� Deutsche Telekom Laboratories (T-Labs): antenna sites, fiber links, van
� Fraunhofer Heinrich Hertz Institute (HHI): Berlin testbed
� Kathrein: remote radio heads
EASY-C research project:
•Key technologies for next generation cellular networks
•Funded by German government
•Partners from academia and industry
•Mobile network operators: T-Mobile and Vodafone
•Two testbeds in Berlin and Dresden www.easy-c.com
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LTE UL CoMP setup (4Rx)
Architecture:� Central processing unit + two distributed
remote radio heads (RRH) with two cross polarized antennas each
� 1st RRH on T-Labs building
� 2nd RRH on Technical University Berlin
� About 570m distance between RRH sites
� RRHs connected via CPRI optical fibre links
� Length of fibre links ~3km
System parameters:� 2.6GHz carrier
� 5 MHz bandwidth
� UL peak data rate = 8.5 Mbps (16QAM SIMO)
LTE eNodeB
Central Processing Unit
2.5Gbps CPRI fibre links
~3km length
RemoteRadio Heads
+
antennas
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UL COMP Lab measurements with 2Rx and 4 Rx for fading profile
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UL SINR per path [dB]
UL
Th
rou
gh
pu
t [k
Bit
/s]
4Rx2Rx
LTE eNodeB
2.5Gbps CPRI fibre links
RRHs
FadingEmulator (Spirent)
Rx1
Rx2
Rx3
Rx4
Measurement Set up
Tx1
Test mobile
Splitter 1:4
Main results:
• Gains confirmed
• increased received energy for 4RX vs. 2RX� 3dB
• plus diversity gain depending from fading channel
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(estimated) UL SINR [dB]
UL
Th
rou
gh
pu
t [k
Bit
/s]
4Rx2Rx
3dB + diversity gain
diversity gain
7 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Field Test Berlin
T-Labs TU Berlin
Heinrich Hertz Institute
T-Labs
HHI
TUB
Optical fiber network
~570m distance
User equipmentcarried in van
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Consistency Check : Static user @ cell edge
• static field measurement matches lab data
• approximately 4 dB gain in SINR
• 80 % throughput gain
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(estimated) UL SINR [dB]
UL
Th
rou
gh
pu
t [k
Bit
/s]
4Rx
2Rx
diversity gain
2 Rx TLabs
2 Rx TUB
4 Rx TLabs
4 Rx TLabs
Simulated a cell edge situation:
- Static UE was positioned outside HHI (cell edge position, no velocity)
- Lab measurements for comparison
2 Rx TLabs/TUB
9 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Determination of serving cell
HHI
1Tx2Rx
T-LabsTUB
2Rx 2Rx UL SIR T-Labs > UL SIR TUB
2Rx UL SIR TUB > UL SIR T-Labs
Mapping of strongest Cell for drive route
• T-labs site dominates
• Handovers would not be too frequent
UL SIR (dB)
10 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
UL Throughput gain of Macro Diversity compared to 2Rx Handover
1Tx2Rx
T-Labs
HHI
TUB
2Rx
Serving Cell TUB
Significant Macro Diversity gain compared to Handover Scenario with 2 Rx for SIR threshold 0 dB
Throughput [kBit/s]
Position
Serving Cell TUB
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TLabs Site: Macro Diversity compared to 2Rx Handover
Serving Cell: TLabs
Significant throughput improvement with Macro Diversity compared to Handover Scenario with 2 Rx for SIR threshold 0 dB
Serving Cell: TLabs
Significant improvement of UL SINR for the Macro Diversity Case
SINR gains, but throughput limited by modulation� 64 QAM would help here
12 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Field Test Berlin
T-Labs TU Berlin
Heinrich Hertz Institute
T-Labs
HHI
TUB
Optical fiber network
~570m distance
User equipmentcarried in van
13 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
Throughput improvement
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Throughput improvement
TUB
2Rx
1Tx2Rx
HHI
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Throughput and SNR improvement
Throughput CDFs show the
improvement in throughput
and SINR
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Summary
Industry’s first live field test of CoMP in LTE network
Feasibility of UL CoMP in realistic LTE environment has been proven
� Central processing with distributed RRHs (>500m apart)
� Digital Baseband transmission over optical fibers of ~3km length
� UL coherent combining validated for MMSE receiver
� No issues with optical transmission delay
� Receiver can handle delay spread and alignment of timing advance
Quantitative results of test:
� Significant UL throughput enhancements observed for user at cell edge
� Potential improvement identified for 64 QAM modulation
17 | UL CoMP Trial Berlin | June. 2010 All Rights Reserved © Alcatel-Lucent 2010
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