Apparatuses, methods, and systems are disclosed for reference signal sequence determination. One apparatus includes a processor that determines an RS sequence for transmission. The RS sequence includes three symbols determined by the following equation: ru(n)=ejϕ(n)π/4. The RS sequence includes: a first RS sequence, wherein ru(n) is the first RS sequence, n=0 to 2, φ(0)=−3, φ(1)=−3, and φ(2)=−1; or a second RS sequence, wherein ru(n) is the second RS sequence, n=0 to 2, φ(0)=−3, φ(1)=1, and φ(2)=1. The apparatus also includes a transmitter that transmits the RS sequence on a time-frequency resource.