Wireless Ad Hoc and Sensor Networks

Wireless Ad Hoc and Sensor Networks Wireless Ad Hoc and Sensor Networks

12.07.2015 Views

Congestion Control in ATM Networks and the Internet 117where W max is the maximum bound on the unknown weights. Then, theerror in the weights during estimation is given bỹW ( k) = W − Wk ˆ ( )(3.56)FACT 3.4.1Because the buffer size is finite, the activation functions are bounded by knownpositive values so that |(())| ϕ xk ≤ ϕmaxand |(())| ϕ̃ xk ≤ ϕ̃max.The traffic rate uk ( ) is∑1uk− (3.57)T x W T( ) = ( d − ˆ ( k ) ϕ( x ( k )) + k v e ( k )) uk ( − RTT)and the closed-loop buffer occupancy dynamics becomeek ( + 1) = kek ( ) + e( k) + ε( k) + dk ( )vi(3.58)where the traffic flow modeling error is defined byTe( k) = W ̃ ( k) ϕ( x( k))i(3.59)3.4.2.3 Weight Updates for Guaranteed QoSIt is required to demonstrate that the performance criterion in terms ofpacket losses c(k), transmission delay, and network utilization monitoredthrough error in buffer occupancy ek ( ), is suitably small and that the NNweights Wk ˆ ( ), remain bounded for, the traffic rate uk ( ) is bounded andfinite.THEOREM 3.4.3 (TRAFFIC RATE CONTROLLER DESIGN)Let the desired buffer length x d be finite and the NN traffic reconstruction errorbound ε N and the disturbance bound d M be known constants. Take the traffic rateinput for Equation 3.37 as Equation 3.47 with weight tuning provided byˆ ( ) ˆ ( ) ( ( ))TWk+ 1 = Wk+ αϕ xk e ( k+ 1 ) −Γ | I−αϕ( xk ( )) ϕ T ( xk ( ))| Wk ˆ ( )(3.60)with Γ>0 a design parameter. Then the error in buffer length ek ( ) andthe NN weight estimates Wk ˆ ( ) are UUB, with the bounds specifically

118 Wireless Ad Hoc and Sensor Networksgiven by Equation 3.67 and Equation 3.68 provided the following conditionshold:2() 1 α|(())|ϕ xk < 1(3.61)( 2)0< Γ < 1(3.62)( 3)k vmax < 1 ,σ(3.63)where is the maximum singular value of k and σ is given bykvmaxv2 2 2 22[ Γ ( 1− α|(())|) ϕ xk + 2αΓ|(())|(ϕ xk 1−α|(())|)]ϕ xkσ = η+2( 1−α|(())|)ϕ xk(3.64)PROOFDefine the Lyapunov function candidateT 1J e k e ka tr W T= ( ) ( ) + ( ̃ ( k ) W ̃ ( k )).(3.65)The first difference is given byT T 1 T∆J = e ( k+ 1) e( k+ 1) − e ( k) e( k) + tr( W̃ ( k+1) W̃ T( k+ 1) −W̃( k) W̃( k)).α(3.66)Use the buffer length error dynamics Equation 3.39 and tuning mechanismEquation 3.60 to obtain|( ek)|>12( 1−σ kvmax)21 ( 1 kvmax)⎡γkvmax+ ρ −σ⎣⎢⎤⎦⎥(3.67)orΓ( 1−Γ)W| ̃W ( k)|>Γ( 2 − Γ)max+2 2 2Γ ( 1− Γ) Wmax+ Γ(2 − Γ)θΓ( 2 − Γ)(3.68)where ρ 1 and θ are constants. In general, ∆J ≤ 0 in a compact set as long asEquation 3.61 through Equation 3.68 are satisfied and either Equation 3.67

Congestion Control in ATM <strong>Networks</strong> <strong>and</strong> the Internet 117where W max is the maximum bound on the unknown weights. Then, theerror in the weights during estimation is given bỹW ( k) = W − Wk ˆ ( )(3.56)FACT 3.4.1Because the buffer size is finite, the activation functions are bounded by knownpositive values so that |(())| ϕ xk ≤ ϕmax<strong>and</strong> |(())| ϕ̃ xk ≤ ϕ̃max.The traffic rate uk ( ) is∑1uk− (3.57)T x W T( ) = ( d − ˆ ( k ) ϕ( x ( k )) + k v e ( k )) uk ( − RTT)<strong>and</strong> the closed-loop buffer occupancy dynamics becomeek ( + 1) = kek ( ) + e( k) + ε( k) + dk ( )vi(3.58)where the traffic flow modeling error is defined byTe( k) = W ̃ ( k) ϕ( x( k))i(3.59)3.4.2.3 Weight Updates for Guaranteed QoSIt is required to demonstrate that the performance criterion in terms ofpacket losses c(k), transmission delay, <strong>and</strong> network utilization monitoredthrough error in buffer occupancy ek ( ), is suitably small <strong>and</strong> that the NNweights Wk ˆ ( ), remain bounded for, the traffic rate uk ( ) is bounded <strong>and</strong>finite.THEOREM 3.4.3 (TRAFFIC RATE CONTROLLER DESIGN)Let the desired buffer length x d be finite <strong>and</strong> the NN traffic reconstruction errorbound ε N <strong>and</strong> the disturbance bound d M be known constants. Take the traffic rateinput for Equation 3.37 as Equation 3.47 with weight tuning provided byˆ ( ) ˆ ( ) ( ( ))TWk+ 1 = Wk+ αϕ xk e ( k+ 1 ) −Γ | I−αϕ( xk ( )) ϕ T ( xk ( ))| Wk ˆ ( )(3.60)with Γ>0 a design parameter. Then the error in buffer length ek ( ) <strong>and</strong>the NN weight estimates Wk ˆ ( ) are UUB, with the bounds specifically

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