Orthogonal designs IV: Existence questions

Orthogonal Designs IV: Existence Questions

In [5] Raghavarao showed that if n = 2 (mod 4) and A is a {O, 1, -1} matrix satisfying AAt = (n 1) In. then n 1 = a2 b2 for a, b integers. In [4] van Lint and Seidel giving a proof modeled on a proof of the Witt cancellation theorem, proved more generally that if n is as above and A is a rational matrix satisfying AAt = kIn then k = q12 + q22 (q1, q2 E Q, the rational numbers). Consequently, if...

The asymptotic existence of orthogonal designs

Given any -tuple ( s1, s2, . . . , s ) of positive integers, there is an integer N = N ( s1, s2, . . . , s ) such that an orthogonal design of order 2 ( s1 + s2 + · · ·+ s ) and type ( 2s1, 2 s2, . . . , 2 s ) exists, for each n ≥ N . This complements a result of Eades et al. which in turn implies that if the positive integers s1, s2, . . . , s are all highly divisible by 2, then there is a ful...

Generalized orthogonal designs

Quaternion orthogonal designs from complex companion designs

The success of applying generalized complex orthogonal designs as space–time block codes recently motivated the definition of quaternion orthogonal designs as potential building blocks for space–timepolarization block codes. This paper offers techniques for constructing quaternion orthogonal designs via combinations of specially chosen complex orthogonal designs. One technique is used to build ...

Amicable complex orthogonal designs

In this letter, we define amicable complex orthogonal designs (ACOD) and propose two systematic methods to construct higher-order ACOD’s from lower-order ACOD’s. Although the upper bound on the number of variables of ACOD’s is found to be the same as that of amicable orthogonal designs (AOD), we show that certain types of AOD’s that were previously shown to be non-existent or undecided, such as...