The interference model has been widely used and studied in block designs where the treatment in a particular plot effects on ones in its neighbor plots. There are many experiments specially in agricultre that block size (k) is greater than the number of treatment (t). If \(k>t\), the universally optimal designs under the interference models are usually difficult to obtain. In this paper, we consider an interference model with equal left- and right-neighbor effects for uncorrelated errors when \(k>t\). Based on Kushner’s method, we obtain the universally optimal designs on the class of circular block designs. We also present some methods to construct these designs. Then, we generalize our results for one-sided interference models.

干扰模型已在块设计中广泛使用和研究，其中特定地块中的处理会影响其相邻地块中的处理。有许多专门在农业中的实验，块大小（k）大于处理数（t）。如果\(k>t\)，则通常难以获得干涉模型下的普遍最优设计。在本文中，我们考虑了一个在\(k>t\)时对不​​相关误差具有相等左右邻域效应的干扰模型。基于库什纳的方法，我们得到了圆形块设计类的普遍最优设计。我们还提出了一些构建这些设计的方法。然后，我们将我们的结果推广到单边干扰模型。