As shown in the
figure, the shifted unit-impulse function dðn 2Þ is obtained by shifting the unit-impulse function dðnÞ
to the right by two samples, and the shifted unit-step function uðn 2Þ is achieved by shifting the unitstep function uðnÞ to the right by two samples; similarly, dðn þ 2Þ and uðn þ 2Þ are acquired by
shifting dðnÞ and uðnÞ two samples to the left, respectively.