Optimal design of linear arrays in a TDMA cellular system with Gaussian interference

Optimal design of a linear antenna array at the base station is investigated for the uplink of a TDMA cellular system. The problem is formulated as the maximization of the (ergodic or outage) capacity and entails the trade-off between diversity gain (large antenna spacing) and interference-rejection capability of the array (small antenna spacing). In many applications the positions of user and interferes are not known a priori at the time of the antenna deployment or the terminals are mobile. Therefore, the optimization is carried out not only for a fixed positions of users and interferers, but also by averaging the capacity over the positions of users and interferers within their cells. The approach to the solution of this problem is twofold. At first, an approximate analytical closed form expression for the capacity as a function of the antenna spacing is derived. Then, the results so obtained are corroborated by optimizing the exact capacity though an extensive search over the optimization domain.