On some constacyclic codes over ℤ4[u]/⟨u2−1⟩, their ℤ4 images, and new codes
In this paper, we study λ-constacyclic codes over the ring R=ℤ4+uℤ4 where u2=1, for λ=3+2u and 2+3u. Two new Gray maps from R to ℤ34 are defined with the goal of obtaining new linear codes over ℤ4. The Gray images of λ-constacyclic codes over R are determined. We then conducted a computer search and obtained many λ-constacyclic codes over R whose ℤ4-images have better parameters than currently best-known linear codes over ℤ4.
Designs, Codes and Cryptography