Patent ID: 6651209
Filing Date: 2003-11-18
Classification: H03M

Abstract:
A parallel turbo coder implementation method for a serial turbo coder block described according to: x1&af;(t)=I&af;(t-1)&CirclePlus;Î±1&CenterDot;x1&af;(t-1)&CirclePlus;Î±2&CenterDot;x2&af;(t-1)&CirclePlus;â€¦&CirclePlus;Î±N&CenterDot;xN&af;(t-1)â€ƒ&it;Î±i&it;â€ƒ&it;&varepsilon;&it;â€ƒ&it;{0,1}&it;â€ƒâ€ƒ&it;x2&af;(t)=x1&af;(t-1)&it;â€ƒâ€ƒ&it;&vellip;&it;â€ƒ&it;&vellip;&it;â€ƒâ€ƒ&it;xN&af;(t)=xN-1&af;(t-1)&it;â€ƒâ€ƒ&it;Qj&af;(t)=Î²j0&CenterDot;I&af;(t-1)&CirclePlus;â€ƒ&it;&NewLine;&it;â€ƒ&it;x1&af;(t-1)&CenterDot;[Î²j0&CenterDot;Î±1&CirclePlus;Î²j1]&CirclePlus;â€ƒ&it;&NewLine;&it;â€ƒ&it;&vellip;&it;â€ƒxN&af;(t-1)&CenterDot;[Î²j0&CenterDot;Î±N&CirclePlus;Î²jN]&it;â€ƒÎ²ij&it;&varepsilon;&it;â€ƒ&it;{0,1}â€ƒ&it;j&it;â€ƒ&it;&varepsilon;&af;[1,â€¦&it;â€ƒ,N]comprisinga) carrying out a time index substitution for a first internal state according to: x1&af;(t-1)=â€ƒ&it;I&af;(t-2)&CirclePlus;â€ƒ&it;Î±1&CenterDot;x1&af;(t-2)&CirclePlus;â€ƒâ€ƒ&it;Î±2&CenterDot;x2&af;(t-2)&CirclePlus;â€¦&CirclePlus;â€ƒâ€ƒ&it;Î±N&CenterDot;xN&af;(t-2)(2.&it;x1&it;.1)&vellip;&it;â€ƒâ€ƒx1&af;(t-(n-1))=â€ƒ&it;I&af;(t-n)&CirclePlus;â€ƒ&it;Î±1&CenterDot;x1&af;(t-n)&CirclePlus;â€ƒâ€ƒ&it;Î±2&CenterDot;x2&af;(t-n)&CirclePlus;â€¦&CirclePlus;â€ƒâ€ƒ&it;Î±N&CenterDot;xN&af;(t-n)(2.&it;x1.n&it;-&it;1)where n is the degree of parallelization;b) carrying out a time index substitution for the remaining internal states (i=2, . . . , N) according to: xi&af;(t-1)=xi-1&af;(t-2)(2.&it;xi&it;.1)&vellip;&it;â€ƒxi&af;(t-(n-1))=xi-1&af;(t-n)(2.&it;xi.n&it;-1)c) carrying out a time index substitution for the output signal according to: Qj&af;(t-i)=Î²j0&CenterDot;I&af;(t-(i+1))&CirclePlus;â€ƒ&it;&NewLine;&it;x1&af;(t-(i+1))&CenterDot;[Î²j0&CenterDot;Î±1&CirclePlus;Î²j1]&CirclePlus;â€ƒ&it;&NewLine;&it;&vellip;&it;â€ƒâ€ƒ&it;xN&af;(t-(i+1))&CenterDot;[Î²j0&CenterDot;Î±N&CirclePlus;Î²jN]&it;â€ƒâ€ƒ&it;i&it;â€ƒ&it;&varepsilon;&it;â€ƒ[1,â€¦&it;â€ƒ,n-1]â€ƒ&it;(2.&it;Q.i)to derive a parallel output vector: Qj&af;(t)=Qj&it;0&it;(p)&it;â€ƒQj&af;(t-1)=Qj&it;1&it;(p)&it;â€ƒ&vellip;&it;â€ƒQj&af;(t-(n-1))=Qj&it;n-1&it;(p)â€ƒ&it;j&it;â€ƒ&it;&varepsilon;&it;â€ƒ[1,â€¦&it;â€ƒ,M]d) carrying out an internal state substitution process for each internal state xk(t) (k=1, . . . N) according to the following: d1) set maximum time index element for the internal state xk(t) to tmax=tâˆ’1; d2) scan the representation of the internal state xk(t) for internal states with maximum time index tmax; d3) execute backward time index transition from tmax to tmaxâˆ’1 in the representation of the internal state xk(t) through state variable substitution steps using eqs. (2); and d4) decrement tmax by a value of 1 and repeat steps d2) to d4) while tmax>tâˆ’n; e) carrying out an internal state substitution process for each element Qj(tâˆ’i) (i=0, . . . , nâˆ’2) of each parallel output vector Qj(t) (j=1, . . . , M) according to the following e1) set maximum time index element for vector element Qj(tâˆ’i) in the considered parallel output vector Qj(t) to tmax=tâˆ’iâˆ’1; e2) scan the representation of the vector element Qj(tâˆ’i) for internal states with maximum time index; e3) execute backward time index transition in the representation of the vector element Qj(tâˆ’i) from tmax to tmaxâˆ’1 through state variable substitution steps using eqs. (2); and e4) decrement tmax by a value of 1 and repeat steps e2) to e4) while tmax>tâˆ’n.