ON A RECENT 4-PHASE SEQUENCE DESIGN FOR CDMA

Recently, a family of 4-phase sequences (alphabet {1,j, -1, -j)) was d iscovered having the same size 2(r) + 1 and period 2(r) - 1 as the fam ily of binary (i.e., {+1, -1}) Gold sequences, but whose maximum nontr ivial correlation is smaller by a factor of square-root 2 . In additio n, the worst-case correlation magnitude remains the same for r odd or even, unlike in the case of Gold sequences. The family is asymptotical ly optimal with respect to the Welch lower bound on C(max) for complex -valued sequences and the sequences within the family are easily gener ated using shift registers. This paper aims to provide a more accessib le description of these sequences.