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Signals Ahead: 124.2 GB in a LTE TDD Network - Product Image

Signals Ahead: 124.2 GB in a LTE TDD Network

  • Published: September 2013
  • 49 Pages
  • Signals Research Group, LLC

This report is specifically tailored to those operators and other entities who are interested in understanding the performance similarities and differences when the two duplex schemes are deployed in the same market, albeit in different frequency bands and with different channel bandwidths.

KEY QUESTIONS ANSWERED

- What is the distribution of downlink and uplink throughput on an absolute basis for the two duplex schemes and how does the comparison change after normalizing the results for the amount of utilized spectrum?
- How do key underlying network metrics, such as the signal strength (RSRP) and channel quality(SINR), differ between the two duplex schemes when the two networks are deployed in different frequency bands and with slightly different cell site densities?
- How does the use of a higher frequency band and the amount of uplink network resources impact important uplink parameters, such as the transmit power and Power Headroom, which is a great means of identifying uplink coverage limitations?
- What is the relationship between the downlink throughput, the reported SINR and the received signal strength (RSRP), and how does it differ between the two READ MORE >

Contents

1. Executive Summary
2. Key Conclusions and Observations
3. LTE TDD and LTE FDD Downlink and Uplink Overall Results
4. Detailed LTE TDD and LTE FDD Downlink Analysis
5. Detailed LTE TDD and LTE FDD Uplink Analysis
6. Skype Video Call - Comparing and Contrasting LTE TDD and LTE FDD
7. MIMO Usage and Category 4 Device Implications
8. Test Methodology
9. Final Thoughts
10. Appendix

Index of Figures

Figure 1. LTE TDD and LTE FDD Resource Block Allocation by Sub-frame
Figure 2. LTE TDD and LTE FDD Downlink Throughput Probability Plots
Figure 3. LTE TDD and LTE FDD Uplink Throughput Probability Plots
Figure 4. CQI as a Function of SINR - Scatter Plot
Figure 5. Downlink Testing Drive Routes
Figure 6. Distribution of Modulation Schemes for LTE TDD and LTE FDD - pie charts
Figure 7. RSRP for LTE TDD and LTE FDD - probability plots
Figure 8. RSRP for Band 7 and Band 4 in the Rogers Wireless Network - probability plots
Figure 9. SINR for LTE TDD and LTE FDD - probability plots
Figure 10. Downlink Physical Layer Throughput for LTE FDD 5 MHz as a Function of RSRP and SINR - scatter plot
Figure 11. Downlink Physical Layer Throughput for LTE FDD 10 MHz as a Function of RSRP and SINR - scatter plot
Figure 12. Downlink Physical Layer Throughput for LTE TDD as a Function of RSRP and SINR - scatter plot
Figure 13. Transmit Power for LTE TDD and LTE FDD during Downlink and Uplink Throughput Tests - probability plots
Figure 14. Transmit Power for Band 7 and Band 4 in the Rogers Wireless Network - probability distribution plots
Figure 15. Power Headroom for LTE TDD and LTE FDD during Downlink and Uplink Throughput Tests - probability plots
Figure 16. Power Headroom for Band 7 and Band 4 in the Rogers Wireless Network - probability distribution plots
Figure 17. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE FDD 10 MHz - scatter plot
Figure 18. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE FDD 5 MHz - scatter plot
Figure 19. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE TDD - scatter plot
Figure 20. Transmit Power as a Function of RSRP for LTE TDD and LTE FDD - best fit plots
Figure 21. Power Headroom as a Function of RSRP with Corresponding Throughput values for LTE FDD 10 MHz - scatter plot
Figure 22. Power Headroom as a Function of RSRP with Corresponding Throughput values for LTE FDD 5 MHz - scatter plots
Figure 23. Power Headroom as a Function of RSRP with Corresponding Throughput values for LTE TDD - scatter plots
Figure 24. Power Headroom as a Function of RSRP for LTE TDD and LTE FDD - best fit plots
Figure 25. Uplink Physical Layer Throughput for LTE TDD and LTE FDD versus Serving Cell PCI Values - time series plots
Figure 26. Transmit Power for LTE TDD and LTE FDD versus Serving Cell PCI Values - time series plots
Figure 27. LTE TDD Serving Cell PCI Values during Skype Video Drive Test - geo plot
Figure 28. LTE FDD Serving Cell PCI Values during Skype Video Call Drive Test - geo plot
Figure 29. LTE TDD Aggregate Downlink Throughput and by Individual Code Word during a Skype Video Call - time series plot
Figure 30. LTE FDD Aggregate Downlink Throughput and by Individual Code Word during a Skype Video Call - time series plot
Figure 31. LTE TDD and LTE FDD Uplink Throughput during a Skype Video Call - time series plot
Figure 32. Transmit Power for LTE TDD and LTE FDD during a Skype Video Call - probability plots
Figure 33. MIMO Utilization versus SINR and its Impact on Aggregate Downlink Throughput and for each Individual Code Word - time series
Figure 34. Distribution of Rank Indicator Requests versus MIMO Utilization for LTE TDD and LTE FDD - pie charts
Figure 35. Estimated Category 4 LTE TDD Device Utilization and its Impact on Overall Throughput - 0816 Drive Test
Figure 36. Estimated Category 4 LTE TDD Device Utilization and its Impact on Overall Throughput - 0455 Drive Test
Figure 37. XCAL in Action
Figure 38. Downlink Pathloss for LTE TDD and LTE FDD - probability plots
Figure 39. LTE TDD Transmit Power versus RSRP during a Skype Video Call - scatter plot
Figure 40. LTE FDD Transmit Power versus RSRP during a Skype Video Call - scatter plot
Figure 41. Power Headroom for LTE TDD and LTE FDD during a Skype Video Call - probability plots
Figure 42. LTE FDD 10 MHz RSRP Versus SINR Versus Code Word #1 Throughput - scatter plot
Figure 43. LTE TDD RSRP Versus SINR Versus Code Word #1 Throughput - scatter plot
Figure 44. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE FDD 10 MHz during Cell Handovers - scatter plot
Figure 45. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE FDD 5 MHz during Cell Handovers - scatter plot
Figure 46. Transmit Power as a Function of RSRP with Corresponding Throughput Values of LTE TDD during Cell Handovers - scatter plot
Figure 47. Uplink Physical Layer Throughput for LTE FDD and LTE TDD versus Serving Cell PCI Values - time series plots
Figure 48. Transmit Power for LTE FDD and LTE TDD versus Serving Cell PCI Values - time series plots

Signals Research Group (SRG) conducted what we believe is the first exhaustive [and exhausting] independent analysis of LTE TDD forpublic consumption. Over a four day period in late August, we conducteda drive test of Softbank's LTE TDD and LTE FDD networks in thegreater Tokyo region. In addition to comparing the two LTE duplexschemes while doing lengthy downlink and uplink throughput tests ina mobile environment - we transferred 124.2 GB just on the LTE TDDnetwork during these tests - we also looked at the performance of the twoduplex schemes with more typical applications.

This effort would not have been possible without the support of Accuver, who provided us withaccess to its XCAL data collection tool and its XCAP post-processing software. We have used thesolution numerous times over the last several years so we are very accustomed to using it, althoughwe do stumble upon new capabilities and features each time we use it. In our most recent benchmarkstudies, specifically LTE TDD in Tokyo and LTE Advanced Carrier Aggregation in Seoul, thesolution's ability to support recently introduced technology features, including Category 4 chipsetsand Carrier Aggregation, proved to be invaluable.

This drive test campaign was entirely self-sponsored although we did receive logistical support inthe form of test SIMs, a high bandwidth server, and mobile devices. SRG assumes full responsibilityfor the analysis and commentary included in this report.

Although LTE TDD and LTE FDD are merely different duplex options from the same standard,there is still a very robust interest in how LTE TDD performs. In theory, the performance of LTETDD should be largely comparable to the performance of LTE FDD, and Signals Ahead readers arewell-versed in that regard. However, there are practical matters, such as the frequency band whereLTE TDD is deployed and the downlink/uplink configuration of the available resources, whichmust be considered. For this reason, we focused our drive testing and analysis on specific areas thatwould allow us to quantify these differences in a real world network.

To varying degrees, operators around the world hope to leverage the Softbank network strategywith concurrent availability of LTE FDD and LTE TDD in their markets. Closer to home,Softbank hopes to replicate its success in North America with Sprint and Clearwire. Their goal willnot be an easy one and we wish them the best of luck. Operators may initially start with LTE FDD as a wide area coverage solution, but over time and out of necessity, they will turn to LTE TDDfor a much-needed capacity layer. This report is specifically tailored to those operators and otherentities who are interested in understanding the performance similarities and differences when thetwo duplex schemes are deployed in the same market, albeit in different frequency bands and withdifferent channel bandwidths.

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