1 / 15

Pilot Sequence Design for Up to 8 Spatial Streams in 11ac Networks

This paper discusses pilot design principles for IEEE 802.11ac, proposing a unified pilot mother matrix accommodating up to eight spatial streams for various bandwidths. The study evaluates the performance of orthogonal pilot sequences across spatial streams, aimed at enhancing robustness in correlated transmission scenarios. By defining pilot sequences within a large matrix instead of individual instances, we aim to simplify design without sacrificing performance. The analysis also touches upon the potential marginal impact of pilot sequence design on Peak-to-Average Power Ratio (PAPR) and overall tracking functionality.

nico
Download Presentation

Pilot Sequence Design for Up to 8 Spatial Streams in 11ac Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pilot Sequence design up to 8 Spatial Streams Authors: Date: 2010-07-13 Daewon Lee, LG Electronics

  2. Abstract We discuss some of the pilot design principles for 11ac and propose use a single pilot mother matrix in which all pilots for each bandwidth and spatial stream get its pilot sequence values Daewon Lee, LG Electronics

  3. Pilot Sequence Design • Design Target • Pilot sequences must be defined up to 8 spatial streams • Pilot sequence also must be defined for 80 MHz • Design principles • Performance difference between different pilot sequences is not expected to be large • Rather than defining a pilot sequence for each instance (number of spatial streams & bandwidth size) define a large sequence matrix for all spatial streams and bandwidth may be preferable Daewon Lee, LG Electronics

  4. Discussion (1/2) • performance in various scenarios • It will be important to consider tracking performance in various scenarios • orthogonal pilot sequence across spatial streams may give robust performance in case of correlated Tx antenna configurations • some studies [1] show that having orthogonal pilot design may be more robust for highly correlated channels • pilot tracking functionality • Orthogonal pilots do not necessary mean pilot tracking functionality is mandated to gather pilots over multiple OFDM symbols for processing Daewon Lee, LG Electronics

  5. Discussion (2/2) • Complexity for supporting orthogonal pilot design • 11n pilots has been design to be orthogonal between spatial streams (note that not all pilot tones in 40MHz are time domain orthogonal) • if orthogonal pilot tone tracking is implemented for 11n then same functionality can be re-utilized in 11ac • no mandate of separate phase tracking per spatial stream • may not be needed if single LO is used at Tx/Rx • no additional complexity for phase tracking is expected • PAPR of pilot sequence • PAPR increase due to certain ‘bad’ pilot sequences design is expected to be marginal because OFDM data tones will effect the PAPR the most • some PAPR analysis for pilot in VHT data portion is shown in the Annex Daewon Lee, LG Electronics

  6. Pilot Sequence for 20 MHz • 20 MHz Pilot Sequence Positions • 11n Pilot Sequence • Proposed 11ac Pilot Sequence -21 -7 7 21 Subcarrier index : pilot subcarrier : data subcarrier Daewon Lee, LG Electronics

  7. Pilot Sequence for 40 MHz • 40 MHz Pilot Sequence Positions • 11n Pilot Sequence • Proposed 11ac Pilot Sequence : pilot subcarrier : data subcarrier Subcarrier index -53 -25 -11 11 25 53 Daewon Lee, LG Electronics

  8. Pilot Sequence for 80 MHz • 80 MHz Pilot Sequence Positions • Proposed 11ac Pilot Sequence : pilot subcarrier : data subcarrier Subcarrier index -103 -75 -39 -11 11 39 75 103 Daewon Lee, LG Electronics

  9. Proposed pilot sequence mother matrix • Pilot Sequence mother matrix Daewon Lee, LG Electronics

  10. Summary • We give one candidate proposal for the pilot sequences for data portion of the VHT PLCP preamble • We propose to further consider different pilot sequence for each spatial streams • We propose to further consider orthogonal pilot sequence design to make pilot tracking more robust against various deployment scenarios Daewon Lee, LG Electronics

  11. Reference • [1] Aoki, T.; Sandell, M.; , "Analysis of pilots for residual frequency offset estimation in MIMO OFDM systems," Wireless Communications, IEEE Transactions on , vol.8, no.3, pp.1128-1132, March 2009. Daewon Lee, LG Electronics

  12. Annex Daewon Lee, LG Electronics

  13. Annex. PAPR analysis of proposed pilot sequence (1/3) • Data PAPR analysis as reference • 20 MHz BW with proposed pilot sequence • Different CDF curves represent CDF of each spatial stream Daewon Lee, LG Electronics

  14. Annex. PAPR analysis of proposed pilot sequence (2/3) • 40 MHz BW with proposed pilot sequence & PAPR reduction γ sequence [ +1 +j ] used • Different CDF curves represent CDF of each spatial stream Daewon Lee, LG Electronics

  15. Annex. PAPR analysis of proposed pilot sequence (3/3) • 80 MHz BW with proposed pilot sequence & PAPR reduction γ sequence [ +1 +j +1 +j ] used • Different CDF curves represent CDF of each spatial stream Daewon Lee, LG Electronics

More Related