Ergodic capacity optimization in coexisting DVB-LTE-like systems

In this paper, the ergodic capacity maximization problem in case of coexistence between digital video broadcasting (DVB) and long term evolution (LTE) systems is studied. A full interference scenario, i.e. where the DVB and LTE systems spectrally overlap, is assumed. The objective function, defined as the summation of the LTE and DVB system capacities, is shown to be constituted by a convex and concave parts and only depends on the ratio of transmitted powers. Hence, we first apply the convex concave procedure (CCCP) to the maximization problem, under QoS constraints, in order to obtain the optimal functioning point. The optimal solution is shown to be the minimum of the global capacity but leads to a strict fairness situation between the LTE and DVB systems. We hence propose a second simple algorithm strictly maximizing the global capacity under QoS constraints. The algorithm leads to a global data rate higher than the one obtained with CCCP but favor largely one system over the other. This study can be useful for operators interested in dense network deployment scenarios to decide the operating point of resources allocated in a very aggressive frequency reuse pattern.