Slide - Argos - Rice University

Report
November 2013
doc.: IEEE 11-13/1440r0
Argos | Practical Massive-MIMO
Date: 2013-11-12
Authors:
Name
Affiliations
Address
Phone
email
Clayton Shepard
Rice University
713-348-0000
[email protected]
Lin Zhong
Rice University
713-348-0000
[email protected]
Narendra Anand
Rice University
713-348-0000
[email protected]
Hang Yu
Rice University
713-348-0000
[email protected]
Oscar Bejarano
Rice University
6100 Main St.
Houston, TX 77005
6100 Main St.
Houston, TX 77005
6100 Main St.
Houston, TX 77005
6100 Main St.
Houston, TX 77005
6100 Main St.
Houston, TX 77005
6100 Main St.
Houston, TX 77005
600 Mountain Ave.
New Providence, NJ
07974
713-348-0000
[email protected]
713-348-0000
[email protected]
908-582-4212
[email protected]
Edward Knightly Rice University
Li Erran Li
Submission
Alcatel-Lucent
Slide 1
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
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
Slide 2
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Massive-MIMO Benefits
• Huge improvements in spectral capacity
• Reduced inter-AP interference
• Reduced STA power
• Increased range
Submission
Slide 3
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Scalability Challenges
1) Acquire CSI
M pilots, then M•K feedback
2) Calculate Weights
O(M•K2), non-parallelizable, centralized data
3) Apply Linear Precoding
O(M•K), then O(M) data transport
Submission
Slide 4
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Argos’ Solutions
1) Acquire CSI
O(M•K) → O(K)
New reciprocal calibration method
2) Calculate Weights
O(M•K2) → O(K)*
Novel distributed beamforming method
3) Apply Linear Precoding
O(M•K) → O(K) *
Carefully designed scalable architecture
Ref: [1]
Submission
Slide 5
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Argos Architecture
Submission
Slide 6
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Argos Implementation
Submission
Slide 7
Clayton Shepard, Rice University
November 2013
Submission
doc.: IEEE 11-13/1440r0
Slide 8
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Central
Controller
WARP
Modules
Argos
Interconnects
Sync
Distribution
Clock
Distribution
Argos
Hub
Submission
Ethernet
Switch
9
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Ref: [3]
Submission
Slide 10
Clayton Shepard, Rice University
November 2013
Submission
doc.: IEEE 11-13/1440r0
Slide 11
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
ArgosHub
Submission
Slide 12
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
ArgosMobile
Submission
Slide 13
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Results Without Considering Overhead
CE
Submission
Comp
Transmit
Slide 14
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Linear Gains as # AP Antennas Increases
Capacity vs. AP Antennas with 15 STAs
Ref: [1]
Submission
Slide 15
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Linear Gains as # of STAs Increases
Capacity vs. # of STAs, 64 AP antennas
Submission
Slide 16
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Scaling # of STAs with 16 AP Antennas
Capacity vs. # of STAs, 16 AP antennas
Submission
Slide 17
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Zero-forcing vs. Conjugate
More Antennas
or Higher Mobility
Faster Processing
Zero-forcing
Adaptive
Precoding
Conjugate
1 GHz
Submission
10 GHz
Slide 18
Clayton Shepard, Rice University
Ref: [2]
November 2013
doc.: IEEE 11-13/1440r0
Massive-MIMO in 802.11
• CSMA
• TDD
• Expensive
• Low Mobility
• Large Form-Factor
• High Frequency (5.8 GHz)
Submission
Slide 19
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Current 802.11ac Sounding
<<
Tx
Rx A
Rx B
Rx C
NDPA
Data
NDP
CSI
ack
CSI
ack
CSI
ack
Transmission Procedure
1. Select transmission group (NDPA)
2. Send channel sounding training sequence (NDP)
3. Receive channel state feedback (CSI) from each receiver serially
4. Construct steering weights and transmit data
5. Acknowledge transmission
Submission
Slide 20
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Modified Implicit Sounding
Tx
Rx A
Data
NDPA
NDP
ack
ack
NDP
Rx B
ack
NDP
Rx C
Transmission Procedure
1. Select transmission group (NDPA)
2. Group serially transmits implicit sounding training sequence (NDP)
3. Construct steering weights and transmit data
4. Acknowledge transmission
Submission
Slide 21
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
802.11n Implicit Sounding
High-overhead
Required inter-STA cooperation for calibration
Ref: [4,5,6,7]
Submission
Slide 22
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
Conclusions
Massive-MIMO can be practical
Massive-MIMO requires implicit sounding to be feasible
Implicit sounding is easily enabled in 802.11
http://argos.rice.edu
Submission
Slide 23
Clayton Shepard, Rice University
November 2013
doc.: IEEE 11-13/1440r0
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.
Submission
Slide 24
Clayton Shepard, Rice University

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