27 5 29 9 JOURNAL OF APPLIED SCIENCES Electronics and Information Engineering Vol. 27 No. 5 Sep. 29 : 255-8297(29)5-441-5 Mesh 1,2 2 2 2 1 2196 2 217 : Mesh Mesh. Mesh : Mesh : TP393 : A Reliability Evaluation Based on Multipath Routing in WMN HE Ming 1,2, QIU Hang-ping 2, BAO Guang-yu 2, XIAO Deng-hai 2 1. Institute of Information Science and Engineering, Southeast University, Nanjing 2196, China 2. Institute of Command Automation, PLA Science and Technology University, Nanjing 217, China Abstract: In order to evaluate reliability of wireless mesh networks (WMN), a new method for evaluating network reliability based on multipath routing (MP-NRE) is proposed. High mobility and ratio of link failure are studied. Incidental multipath attenuation has influence on the network reliability. Experimental results show that network reliability is higher with disjoint path than with multipath routing in WMN, and link lifetimes may be relatively short compared to traffic flows. This is significant for WMN to improve network reliability and reduce end-to-end delay. Keywords: wireless mesh networks(wmn), network reliability, multipath routing, reliability evaluating Mesh (wireless mesh networks WMN). (wireless LAN WLAN) Ad Hoc [1]. Internet Mesh WLAN [2]. WMN 1 1 Mesh Internet Mesh WMN [3] () Internet. WMN Mesh [4]. : 29-3-1; : 29-7-26 : 863(No.27AA1Z432, No.27AA1Z433) : E-mail: blue_horse@126.com
442 27 RF. Mesh Internet Mesh 1 Mesh Figure 1 Wireless mesh networks(wmn) 1 Mesh 1.. Mesh. [5]. NP Mesh [6] Mesh. /. [7]. [8]. Mesh. WMN. (networks reliability evaluation based on multipath routing, MP-NRE) WMN 2. IEEE82.16 [9].. 2.1 82.16 1.9 GHz, 2 m AT&T [1]. I II III I II III. ( db) P L = A + 1γ lg(d/d ) + X f + X h + s, d > d (1) γ d ( m) d = 1 m s A 1 m X f X h γ, A, X f, X h γ = a bh b + c/h b (2) A = 2 lg(4πd /λ) (3) X f = 6 lg(f/2 ) (4) 1.8 lg(h r /2), I II X h = 1. lg(h r /3), III, h r 3 m 2. lg(h r /3), III, h r > 3 (5) a, b, c, h r [1]. 2.2 Rice Rice f(r) = r ( σ 2 exp r2 + rd 2 ) ( rrd ) 2σ 2 I σ 2 (6) r d σ I Bessel
5 Mesh 443 Rice K = 1 lg ( r 2 d 2σ 2 ) db, ( r ) F (r) = 1 Q 2K, σ (7) Q( ) Q 82.16 [9] K K = 1 lg(f s ) + 1 lg(f h ) + 1 lg(f b )+ lg(k d γ ) + µ (8) k = 1, γ =.5, µ σ K = 8 R.V. d ( km). 3. IEEE 82.16 Mesh. /( + ) Ψ Ψ Γ, Γ. 82.16 Rice P i P i Pout, 1 L Rice Pout, 2 { ( P out = Pr (P < Γ ) P < Ψ L )} P i = i=1 P 1 out + P 2 out P 1 outp 2 out (9) P link out = 1. [(1. P up out)(1. P down out )] (1) P up out Pout down (9) [8] 1 2. 2.. 2 Mesh 1 PeriodicLinkQuality(N, w) uses=n.last_uses+n.current_uses loss=n.last_loss+n.current_loss Uses=max{uses, loss} If uses> newquality=(uses loss)/uses Else newquality=1. quality=w newquality+(1 w) N.quality Return quality 2 InstantLinkQuality(N, w) uses=n.last_uses+n.current_uses loss=n.last_loss+n.current_uses uses=max{uses, loss} If uses> 1 Quality=w N.quality+(1 w) (uses loss)/uses Else Quality=1. Return quality 2 3. p s-t s t R = 2p 4 p 8 (11) R Mesh = 2p 4 p 8 + (6p 4 12p 6 8p 7 + 15p 8 + 12p 9 2p 1 + 8p 11 p 12 ) (12) a b c 4 (MP-NRE) s t Mesh Mesh d e f 2 Figure 2 Disjoint path
444 27 s a b c t 1..8 Mesh f g h 3 Figure 3 Multipath routing.6.4.2 2 ({s, a, b, c, t} ). 3 Mesh 8 ({s, a, b, c, t}, {s, a, b, h, t}, {s, a, g, h, t}, {s, a, g, c, t} ).. P 1,, P h E i P i. D 1 = E 1 D i = E 1 E 2... E i 1 E i. R G = h i=1 P r[d i ]. 5 NS2v2.28 1 WMN. MAC 82.11 NS2 (914 MHz 2.1 GHz 25 m. 1 2 m 5 m 1 m 2 m. 4 512 1 CBR NS2 cbrgen.tcl WSN. 5 3 ms AODV 3 ms 7 42 ms 1.8 s. 4 Mesh.. [8] l λ = 1/l. F (t) = 1 exp( λt). k CDF F s (t) = 1 exp( kλt). m CDF F s (t), F p (t) = (F s (t)) m. 2 CDF F (t) = (1 exp[ 4λt]) 2 (13).2.4.6.8 1. 4 Figure 4 Comparison of the networks reliability E[X] = (1 F (x))dx E (T ) = 2e 4λt e 8λt dt = 3/(8λ) (14) h ( 1) j+1 j=1 I {1,...,h}, I =j P r[e I ] (15) E I P i, i I t n E I P r[e I ] = 1 exp[ nλt] (16) n t n. ap b ae bλt F Mesh (t) = 1 8e 4λt + 12e 7λt + 8e 7λt 14e 8λt 12e 9λt + 2e 1λt 8e 11λt + e 12λt E Mesh [T ] = 1 F Mesh (t)dt = 44/(77λ) (17) Mesh 1.56 s 3 1.29. 5 1.81. s-t 6 Mesh (WMN).. Mesh
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