1. Submission doc.: IEEE 11-13/1440r0 November 2013 Clayton Shepard, Rice UniversitySlide 1 Argos | Practical Massive-MIMO Date: 2013-11-12 Authors:

2. Submission doc.: IEEE 11-13/1440r0 November 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.

3. 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

4. Submission doc.: IEEE 11-13/1440r0 Clayton Shepard, Rice UniversitySlide 4 Scalability Challenges 1)Acquire CSI M pilots, then MK feedback 2)Calculate Weights O(MK 2 ), non-parallelizable, centralized data 3)Apply Linear Precoding O(MK), then O(M) data transport November 2013

5. Submission doc.: IEEE 11-13/1440r0 Argos’ Solutions Slide 5Clayton Shepard, Rice University November 2013 1)Acquire CSI New reciprocal calibration method 2)Calculate Weights Novel distributed beamforming method 3)Apply Linear Precoding Carefully designed scalable architecture O(MK) → O(K) O(MK 2 ) → O(K)* O(MK) → O(K) * Ref: [1]

6. Submission doc.: IEEE 11-13/1440r0 Argos Architecture Clayton Shepard, Rice University November 2013 Slide 6

7. Submission doc.: IEEE 11-13/1440r0 Argos Implementation Slide 7Clayton Shepard, Rice University November 2013

8. Submission doc.: IEEE 11-13/1440r0 Clayton Shepard, Rice University November 2013 Slide 8

9. Submission doc.: IEEE 11-13/1440r0 9 WARP Modules Central Controller Argos Hub Clock Distribution Ethernet Switch Sync Distribution Argos Interconnects Clayton Shepard, Rice University November 2013

10. Submission doc.: IEEE 11-13/1440r0 Slide 10Clayton Shepard, Rice University November 2013 Ref: [3]

11. Submission doc.: IEEE 11-13/1440r0 Clayton Shepard, Rice University November 2013 Slide 11

12. Submission doc.: IEEE 11-13/1440r0 ArgosHub Slide 12Clayton Shepard, Rice University November 2013

13. Submission doc.: IEEE 11-13/1440r0 ArgosMobile Clayton Shepard, Rice University November 2013 Slide 13

14. Submission doc.: IEEE 11-13/1440r0 Results Without Considering Overhead CE Transmit Comp Clayton Shepard, Rice University November 2013 Slide 14

15. 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]

16. 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

17. 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

18. Submission doc.: IEEE 11-13/1440r0 Zero-forcing vs. Conjugate Slide 18 November 2013 1 GHz10 GHz Conjugate Adaptive Precoding Zero-forcing Faster Processing More Antennas or Higher Mobility Ref: [2] Clayton Shepard, Rice University

19. Submission doc.: IEEE 11-13/1440r0 Massive-MIMO in 802.11 Slide 19Clayton Shepard, Rice University November 2013 TDD Low Mobility High Frequency (5.8 GHz) CSMA Expensive Large Form-Factor

20. Submission doc.: IEEE 11-13/1440r0 Current 802.11ac Sounding Slide 20Clayton Shepard, Rice University November 2013 NDPANDPA ackackCSICSI ackackCSICSI DataDataNDPNDP ackackCSICSI Rx A Tx Rx B Rx C 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 <<

21. Submission doc.: IEEE 11-13/1440r0 Modified Implicit Sounding Slide 21Clayton Shepard, Rice University November 2013 NDPANDPA ackackNDPNDP ackackNDPNDP DataData ackackNDPNDP Rx A Tx Rx B 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

22. Submission doc.: IEEE 11-13/1440r0 802.11n Implicit Sounding High-overhead Required inter-STA cooperation for calibration Slide 22Clayton Shepard, Rice University November 2013 Ref: [4,5,6,7]

23. Submission 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 Slide 23Clayton Shepard, Rice University November 2013 http://argos.rice.edu

24. 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.