Simulation of Dynamic BAN Channel for Navel to Arm Links Based on Antenna Motion

Transcription

1 Simulatio of Dyamic BAN Chael for Navel to Arm Liks Based o Atea Motio Iswadi, Miseok Kim, Ju-ichi Takada, Takahiro Aoyagi Graduate School of Sciece ad Egieerig Tokyo Istitute of Techology

2 Outlie Itroductio Measuremet campaig Chael simulatios O-body atea modelig Results ad discussios Coclusios Future works 2

3 Itroductio CM1 CM2 CM3 CM4 Body Area Network (BAN) aims to provide wireless commuicatio amog wearable devices Regardig the applicatio o medical health-care, the etwork reliability ad huma safety are emphasized issues. error o data trasmissio ca damage or cause critical problem to the patiece Therefore, the chael model is very importat to provide the proper desig of devices ad etwork architecture of BAN. I-body ode O-body ode Off-body ode Stadardizatio IEEE Task Group [1] [1] 3

4 Itroductio The o-body chael depeds o [2]: Geometry of huma body Surroudig eviromet (distace, shadowig, scatterig) body movemet, propagatio mechaism Properties of o-body atea body proximity, dielectric properties of body tissue The decompositio of those properties is required to provide a accurate ad flexible chael model. To do this, the effect of each properties to the chael must be idividually characterisized. This research studies the body movemet properties o the BAN chaels. [2] Y. Nechayev, P. Hall, I. Kha, ad C. Costatiou, Wireless chaels ad Ateas for Body Area Network," Proceedig of IEEE /IFIP WONS 2010,

5 Itroductio The dyamic BAN chael geerally characterized i statistical maer, although some researcher ivestigated o the reaso of the chael fluctuatio, such as: Multiple cylider to model the body ad arms, the effect of body scatterig ad shadowig are solved aalytically by solvig the Maxwell s equatio [3] The distace variatio ad atea rotatio due to the body motio were used to simulate the BAN chael [4] Measuremet of o-body atea motio ad chael simulatio by cosiderig atea as poit source ear the dielectric cylider [5] I this presetatio, the avel-arm liks based is simulated based o the atea body motio as i [5] by cosiderig the short ad log term fadig ad effect of body shadowig [3] L. Liu, P. Docker, C. Oestges, Time-variat o-body chael fadig characterizatio ad modelig with dyamic huma body, COST 2100 Meetig, September, 2009 [4] B. Zhe, T. Aoyagi, ad R. Koho, "To reasos for the dyamic o-body chaels," Proceedig of IEEE Wireless Commuicatios ad Networkig Coferece, April, 2010 [5] Iswadi, M. Kim, J. Takada, Effect of o-body atea motios to the BAN Chael fluctuatio, 2010 Asia Pasific Radio Sciece Coferece, Toyama, Japa, September

6 Measuremet campaig Measuremet setup Cotroller USB to RS232 adapter USB to GPIB adapter trigger Motio data processig Vector etwork aalyzer trigger Motio capture system The motio capture equipmet [6] is used to observe the body motio, VNA is used to measured the chael gai. Both equipmets are sychroized by a sigle trigger [6] Motio aalysis," Number of poits Samplig rate Frequecy Freq. spa IFBW Number of poits Samplig rate Motio Capture Parameters Hz VNA Parameters MHz Zero spa 300 Hz Hz 6

7 Measuremet campaig Setup of etwork Network topology Star [7] Coordiator ode Device odes Body actios avel wrist, upper arm Still, walkig, stadig up sittig dow [7] K. Yazdadoost ad K. Sayraa, "Chael model for body area etwork BAN," IEEE P , November,

8 Chael simulatios Aalysis process L path 4πd ( t) f ( t) = c 2 Coordiator atea Device atea [8] R.J. Lytle, Far-Field Patters of Poit Sources Operated i the Presece of Dielectric Circular Cyliders, IEEE Tras. o Atea ad Propagat. Vol. AP-19, No.5, 1971 Markers positios Markers positios Propagatio directio v β α Atea positio Atea rotatio Atea positio Atea rotatio u atea w Propagatio distace, d(t) Propagatio vector Relative rotatio α C (t), β C (t) α D (t), β D (t) G G ( t) = ch Path-loss L path (d(t),f) C ( t) G L path G ( t) ref D ( t) Atea gai G C (α C (t), β C (t)) G D (α D (t), β D (t)) O-body atea patter: Simplified model [8] G ref is calculated from still actio i the begiig of each measuremet E[ Gch ] Lpath(E[ d]) Gref = G (E[ α ],E[ β ]) G (E[ α ],E[ β ]) C C C D D D 8

9 Chael simulatio The simulated results are compared to the measuremet result. However the measured chael cosists of log term fadig ad shortterm fadig. The itetioal body motio causes the log-term fadig, thus oly this fadig ca be simulated i by curret approach. The short term fadig, due to u-itetioal body motio, ripple of o-body atea radiatio patter, etc., should be removed by usig the movig averagig widow is applied G t+ N / 2 = ch, meas ( t) Gch, meas ( k) N k = t N / 2 the widow size is N = 40 or 0.4 s 1 However, some ripples are foud o the simulated results, it is probably caused by the precisio of the motio capture. 9

10 Chael simulatio chael gai(db) Wrist, walkig measured data filtered data time(s) The short term fadig ca be modeled statistically by ay distributio fuctio, such as Gaussia distributio. CDF CDF µ (db) σ 2 (db) wrist,walk wrist,up-dow upper-arm,walk upper-arm,up-dow µ (db) σ 2 (db) relative gai (db) relative gai (db) walk,measured walk,fitted up-dow,measured up-dow,fitted 10

11 O-body atea modelig The aalytical method of poit source ear the dielectric circular cylider [8] Far field patter for a z source orietatio: v β 2a u α E α P(α, β,z) µ 1,ε 1 µ 2,ε 2 E β w where = s (2) 2ρ) F + ah ( λ ρ = E α = + siα' j J ( λ 2 ) F = s (2) E β = b H ( λ 2 ρ) F a b s s H D = ψh (2) J ( ψ ) H '( ψ E0 j siα' 2 j ψ k E0 j siα' ωµ 2 πψ ξ ψ (2) '( ψ ) KJ '( ξ ) H '( ψ ) NJ '( ξ ) cos α' (2) (2) (2) 2 2 ( ψ ) ξh ( ξ ) ψh ( ψ ) KξH ( ξ ) ξ ψ (2) ) / ψh ( ψ ) KJ '( ξ ) / ξj ( ξ ) 2 (2) [ ] Dπψ H ( ψ ) cosα' (2) [ ] H ( ψ ) = 2 = 2 (2) (2) ( k k cos α ) 1/ 2 λ = = k si ' ' 2 2 α [8] R.J. Lytle, Far-Field Patters of Poit Sources Operated i the Presece of Dielectric Circular Cyliders, IEEE Tras. o Atea ad Propagat. Vol. AP-19, No.5, 1971 λ K = µ / λ = k F = e µ 2 ξ = λ1a ψ = 2a N k1 / j( β β ')

12 O-body atea modelig Results of radiatio patter 150 o 120 o Navel Wrist Upper-arm 90 o 60 o 30 o u 180 o db 0 o Navel, a = 12.7 cm ε r1 = (fat) v α β E α E β P(α, β,z) µ 1,ε 1 µ 2,ε 2 2a w -150 o -120 o -90 o -60 o -30 o Wrist, a = 3.0 cm ε r1 = (boe) Upper-arm a = 4.1 cm ε r1 = 13.05(boe) 12

13 Chael gai (db) Results ad discussios Wrist - walkig The results shows agreemet with measured chael Chael gai (db) Wrist up dow -70 measuremet simulatio time(s) Upper arm - walkig Correlatio coefficiets time(s) Upper arm up dow measuremet simulatio Chael gai (db) time(s) measuremet simulatio The correlatio coefficiet also shows their high correlatio Chael gai (db) time(s) measuremet simulatio 13

14 Results ad discussios To study the source of the error ad to study reaso of the fluctuatios of chael gai, the motios of the atea are re-observed x-axis (mm) y-axis (mm) z-axis (mm) MHz - wrist - walk Navel atea device atea time (t) x z y 14

15 Results ad discussios y-axis (mm) pathgai (db) -500 Wrist, walkig Navel atea device atea measuremet simulatio The chael gai icreases whe the arm moves i frot of the body Ad the gai decreases whe it is behid the body, due to body shadowig The lowest gai was happeed whe the chael is shadowed by the had The atea patter effect time (t) 15

16 Results ad discussios y-axis (mm) Wrist, up-dow Navel atea device atea The effect of the body ad arm shadowig also ca be observed i the chael gai The low atea gai i the rear side of the body causes the error o the simulatios pathgai (db) time (t) measuremet simulatio 16

17 Results ad discussios The effect of the body ad had shadowig also ca be foud i the avel-arm liks y-axis (mm) upper-arm - walk Navel atea y-axis (mm) upper-arm - up-dow device atea pathgai (db) pathgai (db) measuremet simulatio time (t) time (t) 17

18 Summary The BAN chael fluctuatio has bee simulated based o the atea motio. The distace variatio ad atea rotatio are cosidered by usig path loss model ad simplified atea radiatio patter. The simulatio ca approach the measured chael, although some errors are foud due to the atea patter icompatibility The study shows that the body shadowig has a sigificat effect i the chael loss. 18

19 Future Works The use of the referece gai i the simulatio is impractical, thus it must be studied to icluded better propagatio approach The atea patter is very importat to develop a good simulatio, a better o-body atea model will be studied As the body shadowig is sigificat, so the iformatio of the probability of the body shadowig for each sceario is also importat. It will be characterized as future works 19