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Submission
doc.: IEEE 11-13/1440r0November 2013
Clayton Shepard, Rice UniversitySlide 1
Argos | Practical Massive-MIMODate: 2013-11-12
Name Affiliations Address Phone email Clayton Shepard Rice University 6100 Main St.
Houston, TX 77005 713-348-0000 cws@rice.edu
Lin Zhong Rice University 6100 Main St. Houston, TX 77005
713-348-0000 zhong@rice.edu
Narendra Anand Rice University 6100 Main St. Houston, TX 77005
713-348-0000 nanand@rice.edu
Hang Yu Rice University 6100 Main St. Houston, TX 77005
713-348-0000 hang.yu@rice.edu
Oscar Bejarano Rice University 6100 Main St. Houston, TX 77005
713-348-0000 obejarano@rice.edu
Edward Knightly Rice University 6100 Main St. Houston, TX 77005
713-348-0000 knightly@rice.edu
Li Erran Li Alcatel-Lucent 600 Mountain Ave. New Providence, NJ 07974
908-582-4212 li-erran-li@alcatel-lucent.com
Authors:
Submission
doc.: IEEE 11-13/1440r0November 2013
Clayton Shepard, Rice UniversitySlide 2
Abstract
We present a practical architecture for massive-MIMO and show early results from a real-world prototype. We suggest a small modification to 802.11ac to enable implicit channel sounding, which is critical for the practicality of massive-MIMO.
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice UniversitySlide 3
Massive-MIMO Benefits
• Huge improvements in spectral capacity
• Reduced inter-AP interference
• Reduced STA power
• Increased range
November 2013
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice UniversitySlide 4
Scalability Challenges
1) Acquire CSIM pilots, then M•K feedback
2) Calculate WeightsO(M•K2), non-parallelizable, centralized data
3) Apply Linear PrecodingO(M•K), then O(M) data transport
November 2013
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Argos’ Solutions
Slide 5
November 2013
1) Acquire CSINew reciprocal calibration method
2) Calculate WeightsNovel distributed beamforming method
3) Apply Linear PrecodingCarefully designed scalable architecture
O(M•K) → O(K)
O(M•K2) → O(K)*
O(M•K) → O(K) *
Ref: [1]
Submission
doc.: IEEE 11-13/1440r0
Argos Architecture
Clayton Shepard, Rice University
November 2013
Slide 6
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Argos Implementation
Slide 7
November 2013
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
November 2013
Slide 8
Submission
doc.: IEEE 11-13/1440r0
Slide 9
WARP Modules
Central Controller
Argos Hub
Clock Distribution
Ethernet Switch
SyncDistribution
Argos Interconnects
Clayton Shepard, Rice University
November 2013
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice UniversitySlide 10
November 2013
Ref: [3]
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
November 2013
Slide 11
Submission
doc.: IEEE 11-13/1440r0
ArgosHub
Slide 12 Clayton Shepard, Rice University
November 2013
Submission
doc.: IEEE 11-13/1440r0
ArgosMobile
Clayton Shepard, Rice University
November 2013
Slide 13
Submission
doc.: IEEE 11-13/1440r0
Results Without Considering Overhead
CE TransmitComp
Clayton Shepard, Rice University
November 2013
Slide 14
Submission
doc.: IEEE 11-13/1440r0
Capacity vs. AP Antennas with 15 STAs
Linear Gains as # AP Antennas Increases
Clayton Shepard, Rice University
November 2013
Slide 15
Ref: [1]
Submission
doc.: IEEE 11-13/1440r0
Capacity vs. # of STAs, 64 AP antennas
Linear Gains as # of STAs Increases
Clayton Shepard, Rice University
November 2013
Slide 16
Submission
doc.: IEEE 11-13/1440r0
Capacity vs. # of STAs, 16 AP antennas
Scaling # of STAs with 16 AP Antennas
Clayton Shepard, Rice University
November 2013
Slide 17
Submission
doc.: IEEE 11-13/1440r0
Zero-forcing vs. Conjugate
Slide 18
November 2013
1 GHz 10 GHz
ConjugateAdaptivePrecodingZero-forcing
Faster ProcessingMore Antennas or Higher Mobility
Ref: [2]Clayton Shepard, Rice University
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Massive-MIMO in 802.11
Slide 19
November 2013
• TDD
• Low Mobility
• High Frequency (5.8 GHz)
• CSMA
• Expensive
• Large Form-Factor
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Current 802.11ac Sounding
Slide 20
November 2013
NDPA
ackCSI
ackCSI
DataNDP
ackCSIRx A
Tx
Rx B
Rx C
Transmission Procedure1. Select transmission group (NDPA)2. Send channel sounding training sequence (NDP)3. Receive channel state feedback (CSI) from each receiver serially4. Construct steering weights and transmit data5. Acknowledge transmission
<<
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Modified Implicit Sounding
Slide 21
November 2013
NDPA
ackNDP
ackNDP
Data
ackNDPRx A
Tx
Rx B
Rx C
Transmission Procedure1. Select transmission group (NDPA)2. Group serially transmits implicit sounding training sequence (NDP)3. Construct steering weights and transmit data4. Acknowledge transmission
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
802.11n Implicit Sounding
High-overhead
Required inter-STA cooperation for calibration
Slide 22
November 2013
Ref: [4,5,6,7]
Submission
doc.: IEEE 11-13/1440r0
Clayton Shepard, Rice University
Conclusions
Massive-MIMO can be practical
Massive-MIMO requires implicit sounding to be feasible
Implicit sounding is easily enabled in 802.11
Slide 23
November 2013
http://argos.rice.edu
Submission
doc.: IEEE 11-13/1440r0November 2013
Clayton Shepard, Rice UniversitySlide 24
References
[1] Clayton Shepard, Hang Yu, Narendra Anand, Erran Li, Thomas Marzetta, Richard Yang, Lin Zhong. "Argos: Practical Many-Antenna Base Stations," in Proc. ACM Int. Conf. Mobile Computing and Networking (MobiCom), August 2012.
[2] Clayton Shepard, Narendra Anand, and Lin Zhong. "Practical Performance of MU-MIMO Precoding in Many-Antenna Base Stations," in Proc. ACM workshop on Cellular networks (CellNet), June 2013.
[3] Clayton Shepard, Hang Yu, and Lin Zhong. "ArgosV2: A Flexible Many-Antenna Research Platform," Extended Abstract for demonstration in Proc. ACM Int. Conf. Mobile Computing and Networking (MobiCom), October 2013.
[4] 04/1404r2, Enhancements for 802.11: Features and Performance, John Ketchum.
[5] 04/1449r1, High-Throughput Enhancements for 802.11: PHY Supplement, John Ketchum.
[6] 05/0414r1, Response to “No” Vote Comments on Calibration, John Ketchum.
[7] IEEE 802.11n-2009
[8] 13/1046r1, Discussion on Massive MIMO for HEW, Zhigang Wen.
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