Phase Rotation for the 80 MHz ac Mixed Mode Packet

Transcription

1 Phas Rotation for th 80 MHz ac Mixd Mod Packt Dat: Authors: Nam Affiliations Addrss Phon mail Lonardo Lanant Jr. Kyushu Inst. of Tchnology Kawazu 680-, Iizuka, JAPAN Yuhi Nagao Kyushu Inst. of Kawazu 680-, Tchnology Iizuka, JAPAN Tht Htun Khin Radrix Corp. Kawazu 680-, Iizuka, JAPAN Tohru Oyama Kyushu Inst. of Kawazu 680-, Tchnology Iizuka, JAPAN Masayuki Kyushu Inst. of Kawazu 680-, Kurosaki Tchnology Iizuka, JAPAN Hiroshi Ochi Radrix Corp. Kawazu 680-, Iizuka, JAPAN p tht@radrix.com kurosaki@cs.kyutch.ac.p Slid 1

2 Abstract In n, a phas rotation of 90 dgrs was applid to th uppr 20MHz band of th 0MHz packt in ordr to rduc th PAPR [1]. In [2], w proposd phas rotations for vry 20MHz band in th 80MHz packt that achivs th sam ffct. W will show thortical proofs, additional simulations, and mak a straw poll for our proposal Slid 2

3 Optimal Phas Shifts (1/5) S 80 θ1 S20 θ2 S20 θ3 S20 θ S MHz s80 (n) = S80(k) 2πkn 6 S20can b (L-STF, L-LTF, L-SIG, VHT-SIG) subcarrir symbol vctor for th 20MHz packt θi = phas shift for th i th 20MHz band 7 2πn(k-2) 7 2πn(k-8) 7 2πn(k+ 8) 7 2πn(k+ 2) θ1 6 θ2 6 θ3 6 θ 6 80(n) = S20(k) + S20(k) + S20(k) + S20(k) s 7 2π 3πn πn πn 3 6 θ1 θ2 θ3 θ (n) = S20(k) kn πn 80 s Slid 3

4 Optimal Phas Shifts (2/5) 7 2πkn 3πn πn πn 3π 6 θ1 θ2 θ3 θ (n) = S20(k) s 80 rarranging 3πn πn πn 3πn 7 2πkn θ1 θ2 θ3 θ 6 80(n) = S20(k) -8 s n β (n) Ovrsampld IDFT of S20 It is clar that duplication of th 20MHz subcarrir bits to 80MHz band is qual to a x ovrsampld of th 20MHz signal modulatd by β (n) Slid

5 Optimal Phas Shifts (3/5) s 80 (n) (n) To minimiz th PAPR of, it is ncssary to nsur unity magnitud of β β 3πn πn πn θ1 θ2 θ3 θ (n) = πn β (n) = 3πn 3 k = 0 θ k 2πkn IDFT of θ k rpating priodically Constant amplitud To minimiz th PAPR of θ k β (n), w nd to choos whos IDFT has low PAPR can b chosn from any CAZAC (Constant Amplitud Zro Autocorrlation) squnc (.g. Frank Zadoff Chu) to nsur unity magnitud of β (n) Slid 5 θ k

6 Optimal Phas Shifts (/5) To maintain compatibility with 0MHz lgacy dvics, ϕ1 ϕ1 ϕ2 ϕ ( 1) ( ) ( 1) ( ) ] θk 2 = [ whr ϕ i ar any phas shifts θ (.g. k = [1 1 ] ) Unfortunatly, thr ar no CAZAC squncs of this form. Th closst and asist to implmnt squnc w found is E = {[1 1 ] } Including its cyclic shifts and scald vrsions Slid 6

7 Optimal Phas Shifts (5/5) 1.5 θ k = [1 1 θ k Tim Domain Signal ] 1.5 θ k = [1 1 θ k Tim Domain Signal ] 1 1 Magnitud 0.5 PAPR=0dB tim Magnitud 0.5 PAPR=3dB tim No PAPR incras from S20 Expct incras of 3dB from S20 Slid 7

8 Simulations Rsults PAPR (1/3) 20MHz Sampling Rat TX output (magnitud) Filds L-STF L-LTF L-SIG VHT-SIG PACKET PAPR 2.09dB 3.17dB 5.28dB 6.28dB 9.58dB Tim (µs) 20MHz 11n Mixd Mod packt Basis PAPR Slid 8

9 Simulations Rsults PAPR (2/3) 80MHz Sampling Rat TX output (magnitud) Filds L-STF L-LTF L-SIG VHT-SIG PACKET PAPR 2.28dB 3.20dB 7.98dB 8.12dB 9.3dB Tim (µs) θ k = [1 1 ] 80MHz Singl usr 11ac Mixd Mod Packt Slid 9 Excpt for th ffct of ovrsampling for L-STF and L-LTF, chang of subcarrir bits in SIG filds, th PAPR is unchangd

10 Simulations Rsults PAPR (3/3) 80MHz Sampling Rat TX output (magnitud) Filds L-STF L-LTF L-SIG VHT-SIG PACKET PAPR 5.1dB 6.21dB 11dB 10.87dB 11dB ~+3dB ~+3dB ~+3dB ~+3dB ~+2dB Tim (µs) PAPR incras du to θk θ k = [1 1 ] 80MHz Singl usr 11ac Mixd Mod Packt Slid 10

11 Simulations Rsults Backward Compatibility (1/2) S S S -S S S S -S 80MHz 0MHz 0MHz 80 MHz dvic 0 MHz dvic 0 MHz dvic 11n dvics at th UPPER 0 MHz channl xpcts [1 ] subcarrir rotation and has a possibl compatibility issu whn Cross Corrlation is usd for fram synchronization Slid 11

12 Simulations Rsults Backward Compatibility (2/2) SIG Fild Symbol Error Rat TGn Channl D itrations Impairmnts: CFO, Phas nois, PA nonlinarity, 0MHz lgacy dvics at both sids of th 80MHz channl that uss only Fram Synchronization has similar prformanc Slid 12

13 Conclusions In ordr to minimiz th PAPR of th 80MHz packt, phas rotation for vry 20MHz band is ncssary. CAZAC squncs ar optimal squnc for th phas rotation [1 1-] is th closst CAZAC squnc to xtndd 11n phas rotation of [1 1 ] [1 1 ] has no visibl backward compatibility issu compard with [1 1 ] Similar to n, w propos that this phas rotation b applid to all th symbols in th ac Mixd Mod Packt Slid 13

14 Rfrncs [1] Wirlss LAN Mdium Accss Control (MAC) and Physical Layr (PHY) Spcification. Amndmnt 5: Enhancmnts for Highr Throughput, IEEE Std n, [2] doc.: IEEE /087r1. IEEE802.11ac Prambl with Lgacy a/n Backward Compatibility Slid 1