Intercell Interference Robustness Tradeoff with Loosened Covariance Shaping

We consider the downlink of a cellular network with multiple antenna base stations (BS) and single antenna mobile devices (MD). Whenever a BS changes its beamforming strategy, it changes the intercell interference (ICI) at every MD in the whole network. These changes are usually not predictable and a BS cannot keep track of the signal to interference plus noise ratio (SINR) of its associated MDs. Consequently, it is not optimal to choose beamforming strategies and link rate adaptions based on measured or assumed SINR values. We propose an optimized shaping constraint on the transmit covariances to make the ICI more predictable. The remaining ICI instationarity is handled with an expected rate optimization, which takes a sampled probability density function of the ICI into account.