doc.: IEEE /0786r0 Submission July 2010 Daewon Lee, LG ElectronicsSlide 1 Pilot Sequence design up to 8 Spatial Streams Date: Authors:

doc.: IEEE /0786r0 Submission July 2010 Daewon Lee, LG ElectronicsSlide 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

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 3

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 4

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 5

doc.: IEEE /0786r0 Submission Pilot Sequence for 20 MHz 20 MHz Pilot Sequence Positions 11n Pilot Sequence Proposed 11ac Pilot Sequence July 2010 Daewon Lee, LG ElectronicsSlide 6 : data subcarrier : pilot subcarrier Subcarrier index

doc.: IEEE /0786r0 Submission Pilot Sequence for 40 MHz 40 MHz Pilot Sequence Positions 11n Pilot Sequence Proposed 11ac Pilot Sequence July 2010 Daewon Lee, LG ElectronicsSlide 7 : data subcarrier : pilot subcarrier Subcarrier index

doc.: IEEE /0786r0 Submission Pilot Sequence for 80 MHz 80 MHz Pilot Sequence Positions Proposed 11ac Pilot Sequence July 2010 Daewon Lee, LG ElectronicsSlide 8 : data subcarrier : pilot subcarrier Subcarrier index

doc.: IEEE /0786r0 Submission July 2010 Daewon Lee, LG ElectronicsSlide 9 Proposed pilot sequence mother matrix Pilot Sequence mother matrix N STS i STS p iSTS,0 p iSTS,1 p iSTS,2 p iSTS,3 p iSTS,4 p iSTS,5 p iSTS,6 p iSTS,7 1~ ~ ~ ~ ~ ~ ~

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 10

doc.: IEEE /0786r0 Submission 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 , March July 2010 Daewon Lee, LG ElectronicsSlide 11

doc.: IEEE /0786r0 Submission Annex July 2010 Daewon Lee, LG ElectronicsSlide 12

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 13

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 14

doc.: IEEE /0786r0 Submission 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 July 2010 Daewon Lee, LG ElectronicsSlide 15