1 research outputs found
Improved Method for Searching of Interleavers Using Garello's Method
In this paper an improved method for searching good interleavers from a
certain set is proposed. The first few terms, corresponding to maximum distance
of approximately 40 of the distance spectra, for turbo codes using these
interleavers are determined by means of Garello's method. The method is applied
to find quadratic permutation polynomials (QPP) based interleavers. Compared to
previous methods for founding QPP based interleavers, the search complexity is
reduced, allowing to find interleavers of higher length. This method has been
applied for QPP interleavers with lengths from the LTE (Long Term Evolution)
standard up to 1504. The analyzed classes are those with the largest spread QPP
(LS-QPP), with the D parameter equal to that of LTE interleaver (D_L_T_E-QPP),
and the class consisting of all QPP interleavers for lengths up to 1008. The
distance spectrum optimization is made for all classes. For the class of LS-QPP
interleavers of small lengths, the search led to superior or at least equal
performances with those of the LTE standard. For larger lengths the search in
the class of D_L_T_E-QPP interleavers is preferred. The interleavers from the
entire class of QPPs lead, in general, to weaker FER (Frame Error Rate)
performance.Comment: submitted to Wireless Communications and Mobile Computing, 24 pages,
5 tables, 7 figure