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Signals Ahead: Fifty Shades of MIMO

  • ID: 2628127
  • Report
  • August 2013
  • 76 Pages
  • Signals Research Group, LLC
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Quantifying the Impact of MIMO in Commercial LTE Networks

This report analyzes the incremental benefits of MIMO (Multiple Input, Multiple Output), specifically Transmission Mode 3 (TM 3), in commercial LTE networks. The results are based on testing in LTE networks from two different operators (Knoxville, TN and Santa Clara, CA) with TM 3 enabled and with the network specially configured to only support Transmission Mode 2. In addition to adhering to a fairly rigorous test methodology, the analysis of the data included mapping the results to a common set of KPIs – primarily device-reported SINR and RSRP, to ensure an apples-to-apples comparison.

This report is included as part of a corporate subscription to Signals Ahead or it can be purchased separately.

KEY OBSERVATIONS INCLUDE THE FOLLOWING

- Both LTE networks delivered outstanding end user throughput with TM 3 enabled.

- Average throughput of 12.91 Mbps in a 2 x 5 MHz network in Knoxville, TN; at least 20 Mbps for 21.6% of the time

- Average throughput of 24.71 Mbps in a 2 x 10 MHz network in Santa Clara, CA; at least 40 Mbps for 18.5% of the time

- MIMO can double the end user throughput, but the gains are generally far more modest with no benefit, and even a negative impact, possible.

- Observed doubling of throughput in both markets with ideal conditions (SINR >> 25 dB)

- At least 40% of the time the availability of TM 3 can increase the end user throughput by at least 20%

- Conversely, at least 50% of the time, the availability of TM 3 would only have a modest impact on throughput (~5%-10%), at best, with negative gains possible

- Results are less favorable with network loading

- Not surprisingly, MIMO didn't have any impact on the user experience with certain applications.

- Web pages loaded just as fast with and without MIMO

- YouTube videos buffered and played pretty much the same

- Results merely demonstrate that throughput doesn't always matter - latency is king

- MIMO still benefits the operator since it reduces the amount of network resources required to deliver the content.

- Observed ~50% fewer Resource Blocks used to load web pages with TM 3 enabled

ABOUT SIGNALS AHEAD SUBSCRIPTION

Signals Ahead is a research-focused product that is published on a periodic basis. Its clientele include all facets of the wireless ecosystem, including some of the largest mobile operators, the top handset suppliers, the major infrastructure vendors, subsystem suppliers, semiconductor companies and financial institutions, including Wall Street, Private Equity and Venture Capitalists, spread across five continents.
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1.0 Executive Summary

2.0 key conclusions and observations

3.0 Detailed results - low-speed mobility
3.1 Overall Daytime PDSCH and SINR Results
3.2 Sample Nighttime Drive Test Results - Physical Layer Throughput versus SINR
3.2.1 Sample Nighttime Drive Test Results - Knoxville Band 5 Network
3.2.2 Sample Nighttime Drive Test Results - Santa Clara Band 4 Network
3.3 Sample Nighttime Drive Test Results - Physical Layer versus RSRP
3.4 Mapping MIMO Performance Impacts as a Function of SINR
3.5 Sample Nighttime Drive Test Results - PDSCH versus SINR during Cell Handovers

4.0 Detailed results - stationary positions

5.0 Detailed results - high-speed vehicular

6.0 user Experience Tests (web browsing and YouTube)

7.0 Test Methodology

8.0 Final Thoughts

9.0 Appendix

Index of Figures

Figure 1. The Impact of MIMO in a Commercial LTE Network - Band 4 and Band 5
Figure 2. Probability Distribution of Daytime Physical Layer Throughput - Knoxville Band 5 Network
Figure 3. Probability Distribution of Daytime Physical Layer Throughput - Santa Clara Band 4 Network
Figure 4. Daytime Physical Layer Throughput - Knoxville Band 5 Network (geo plot)
Figure 5. Distribution of Daytime Physical Layer Throughput - Santa Clara Band 4 Network (geo plot)
Figure 6. Probability Distribution of Daytime Reported SINR Values- Knoxville Band 5 Network
Figure 7. Probability Distribution of Daytime Reported SINR Values - Santa Clara Band 4 Network
Figure 8. Physical Layer Throughput with TM 3 Enabled, June 18th, 0148 hours - Knoxville Band 5 Network (geo plot)
Figure 9. Transmission Mode Assignments with TM3 Enabled, June 18th, 0148 hours - Knoxville Band 5 Network (geo plot)
Figure 10. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 3 Enabled, June 18th 0148 hours - Knoxville Band 5 Network
Figure 11. Physical Layer Throughput with TM 2 Only, July 19th, 0117 hours - Knoxville Band 5 Network (geo plot)
Figure 12. Transmission Mode Assignments with TM2 Only, June 19th, 0117 hours - Knoxville Band 5 Network (geo plot)
Figure 13. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 2 Only, June 19th 0117 hours - Knoxville Band 5 Network
Figure 14. Physical Layer Throughput with TM 3 Enabled, July 18th, 0232 hours - Santa Clara Band 4 Network (geo plot)
Figure 15. Transmission Mode Assignments with TM3 Enabled, July 18th, 0232 hours Santa Clara Band 4 Network (geo plot)
Figure 16. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 3 Enabled, July 18th 0232 hours Santa Clara Band 4 Network
Figure 17. Physical Layer Throughput with TM 2 Only, July 19th, 0105 hours Santa Clara Band 4 Network (geo plot)
Figure 18. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 2 Only, July 19th 0105 hours Santa Clara Band 4 Network
Figure 19. Physical Layer Throughput Versus RSRP Scatterplot with TM 3 Enabled, July 18th 0127 hours Santa Clara Band 4 Network
Figure 20. Physical Layer Throughput Versus RSRP for all Drive Tests Santa Clara Band 4 Network
Figure 21. Consolidated Physical Layer Throughput Versus RSRP for TM 3 Enabled Versus TM 2 Only Santa Clara Band 4 Network
Figure 22. Physical Layer Throughput Versus SINR for all Drive Tests Knoxville Band 5 Network
Figure 23. Consolidated Physical Layer Throughput Versus SINR for TM 3 Enabled Versus TM 2 Only Knoxville Band 5 Network
Figure 24. Physical Layer Throughput Versus SINR for all Drive Tests Santa Clara Band 4 Network
Figure 25. Consolidated Physical Layer Throughput Versus SINR for TM 3 Enabled Versus TM 2 Only Santa Clara Band 4 Network
Figure 26. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only as a Function of SINR Knoxville Band 5 Network
Figure 27. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only as a Function of SINR Santa Clara Band 4 Network
Figure 28. The Impact of MIMO in a Commercial LTE Network Band 4 and Band 5
Figure 29. Physical Layer Throughput Versus SINR Scatterplot at Edge of Cell with TM 3 Enabled, July 18th 0127 hours Santa Clara Band 4 Network
Figure 30. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only at Edge of Cell as a Function of SINR Knoxville Band 5 Network
Figure 31. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only at Edge of Cell as a Function of SINR Santa Clara Band 4 Network
Figure 32. Locations of Stationary Points - Knoxville
Figure 33. Locations of Stationary Points - Santa Clara
Figure 34. Transport Block Size Assignments with TM 3 Enabled, Point 7 Knoxville, Band 5 Network
Figure 35. Transport Block Size Assignments with TM 2 Only, Point 7 Knoxville, Band 5 Network
Figure 36. Transport Block Size Assignments with TM 3 Enabled, Point 3 Knoxville, Band 5 Network
Figure 37. Transport Block Size Assignments with TM 2 Only, Point 2 Knoxville, Band 5 Network
Figure 38. Transport Block Size Assignments with TM 3 Enabled, Point 2 Santa Clara, Band 4 Network
Figure 39. Transport Block Size Assignments with TM 2 Only, Point 2 Santa Clara, Band 4 Network
Figure 40. Transmission Mode Assignments with TM 3 Enabled, July 18th, 0529 hours Santa Clara Band 4 Network (geo plot)
Figure 41. Transmission Mode Assignments with TM 2 Only, July 19th, 0410 hours Santa Clara Band 4 Network (geo plot)
Figure 42. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 3 Enabled, July 18th 0529 hours Santa Clara Band 4 Network Figure 43. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 2 Only, July 19th 0410 hours Santa Clara Band 4 Network
Figure 44. Physical Layer Throughput Versus Serving PCI with TM 3 Enabled, July 18th 0529 hours Santa Clara Band 4 Network
Figure 45. Physical Layer Throughput Versus Serving PCI with TM 2 Only, July 19th 0410 hours Santa Clara Band 4 Network
Figure 46. Web Page Load Times with and without TM 3 Enabled Knoxville Band 5 Network
Figure 47. Web Page Load Times with and without TM 3 Enabled Santa Clara Band 4 Network
Figure 48. Transport Block Size Assignments with TM 3 Enabled with FTP and Web Browsing, Point 7 Knoxville, Band 5 Network
Figure 49. Transport Block Size Assignments with TM 3 Enabled with Web Browsing, Point 3 Santa Clara, Band 4 Network
Figure 50. Transport Block Size Assignments with TM 2 Only with Web Browsing, Point 3 Santa Clara, Band 4 Network
Figure 51. Physical Layer Throughput with YouTube, Hotel Knoxville, Band 5 Network
Figure 52. Transport Block Size Assignments with TM 3 Enabled with YouTube, Hotel Knoxville, Band 5 Network
Figure 53. XCAL in Action
Figure 54. XCAL in Action
Figure 55. Physical Layer Throughput Versus SINR Scatterplot for Two Devices with TM 3 Enabled, June 18th 0427 hours Knoxville Band 5 Network
Figure 56. Physical Layer Throughput Versus SINR Scatterplot for Two Devices with TM 2 Only, June 19th 0300 hours Knoxville Band 5 Network
Figure 57. Probability Distribution of Physical Layer Throughput for Two Devices with TM 3 Enabled and with TM 2 Only Knoxville Band 5 Network
Figure 58. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 3 Enabled, June 18th 0128 hours Knoxville Band 5 Network
Figure 59. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 2 Only, June 19th 0136 hours Knoxville Band 5 Network
Figure 60. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 3 Enabled, July 18th 0340 hours Santa Clara Band 4 Network
Figure 61. Physical Layer Throughput Versus SINR Scatterplot Plus Assorted KPIs with TM 2 Only, July 19th 0320 hours Santa Clara Band 4 Network
Figure 62. Transport Block Size Assignments with TM 3 Enabled, Point 3 Santa Clara, Band 4 Network
Figure 63. Transport Block Size Assignments with TM 2 Only, Point 3 Santa Clara, Band 4 Network

Index of Tables

Table 1. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only as a Function of SINR Knoxville Band 5 Network
Table 2. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only as a Function of SINR Santa Clara Band 4 Network
Table 3. Rank 2 Indicator Usage as a Function of SINR Knoxville Band 5 Network
Table 4. Rank 2 Indicator Usage as a Function of SINR Santa Clara Band 4 Network
Table 5. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only at Edge of Cell as a Function of SINR Knoxville Band 5 Network
Table 6. Physical Layer Throughput Gains with TM 3 Enabled Versus TM 2 Only at Edge of Cell as a Function of SINR Santa Clara Band 4 Network
Table 7. Comparable Web Page Load Times - Santa Clara Band 4 Network
Table 8. Detailed Results, Part I - Knoxville
Table 9. Detailed Results, Part II - Knoxville
Table 10. Detailed Results, Part I Santa Clara
Table 11. Detailed Results, Part II Santa Clara
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