Upper Bound to Interference Coordination with Channel State Information Outdating

We consider the network sum rate maximization in the downlink of a cellular system based on the spatial channel model of the 3GPP MIMO urban macro cell with multiple antenna base stations and single antenna mobile devices. We formulate an upper bound to the kind of cooperation, where each mobile device is served by only one base station, but base stations try to control the interference they produce. The benefits of higher possible data rates through interference mitigation are traded-off against a minimum overhead needed for realizing the required cooperation. The outdating of the channel state information is used to calculate an upper bound to the efficiency of the system. We show, that an increase in cooperation above a boundary does not lead to an increase in possible data rates.