Patent ID: 6526037
Filing Date: 2003-02-25
Classification: H04B,H04J

Abstract:
A method for allocating signature sequence used to distinguish a particular user's signal from the other users' signals in code division multiple access systems comprising the steps of:obtaining a k-th Park-Song sequence {Cl,k}l=0Nsâˆ’1 of length Ns for k=1,2, . . . , K, based upon Equation (1); selecting a Park-Song sequence as a signature sequence {&agr;l(k)}l=0Nâˆ’1 of length N, based upon Equation (2); and allocating the selected Park-Song sequence as the signature sequence to user k, cl,k=&Sum;p=0Nb-1&it;â€ƒ&it;WNslk&it;WVvP&it;WNb2lp&it;Î´&af;(R&af;(l+mp,Nb))=WVsis,(1)where, WNs=ej2&pgr;/Ns, WV=ej2&pgr;/V, WNb2=ej2&pgr;/Nb2, WVs=ej2&pgr;/Vs, Ns=KNb2 is the length of the Park-Song sequence, V is a natural number, Nb is the size of a basic complex symbol, m is a natural number less than Nb, is=Vl(k+Kps)+P(&bgr;ps)Ns, Vs=VNs, K is the maximum number of users, ps is the number satisfying R(l+mps, Nb)=0, the function P is defined by P(&bgr;p)=&ngr;p when &bgr;p=WV&ngr;p, &dgr;(â€¢) is the Kronecker delta function, R(a,b) is the remainder when a is divided b, &bgr;p&egr;{WVi, i=0,1, . . . , Vâˆ’1} is a basic complex symbol, e=2.718 . . . is the base of the natural logarithm, and j={square root over (âˆ’1)}, al(k)=â€ƒ&it;{â€ƒ&it;cl+Ns-L,k,if&it;â€ƒ&it;l=0,1,â€¦&it;â€ƒ,L-1,cl-L,k,if&it;â€ƒ&it;l=L,L+1,â€¦&it;â€ƒ,L+Ns-1,cl+Ns-L,k,if&it;â€ƒ&it;l=L+Ns,â€ƒ&it;L+Ns+1,â€¦&it;â€ƒ,N-1&it;â€ƒ&AutoRightMatch;=â€ƒ&it;cR&af;(l+Ns-L,Ns),k,l=0,1,â€¦&it;â€ƒ,N-1,k=0,1,â€¦&it;â€ƒ,Ku-1,&it;â€ƒ(2)where, L is a natural number chosen based upon the number of resolvable paths and time delay of the communication channel, N=Ns+2L is the length of the signature sequence, and Ku is the number of active users in the system.