Side Effects of IRS: On the Need for Coordination in 6G Multi-Operator IRS-Assisted Networks.

The deployment of intelligent reconfigurable surfaces (IRS) by a wireless operator is a widely discussed concept for optimizing the communication performance in 6G networks. However, an IRS manipulates the channel propagation characteristics not only of signals of the operator who controls the IRS, but also of signals of other operators, although they operate at different frequencies. This is because IRS usually do not employ band pass filtering and, thus, also reflect signals of other frequencies. Those unwanted reflections might cause interference due to uncontrolled multipath. We argue that IRS are part of the common environment and, thus, should be jointly controlled in order to achieve multi-operator coexistence. In this paper, we first introduce and discuss the problem of multi-operator coexistence issues that arise in IRS-assisted networks. We then propose splitting a single common IRS into multiple sub-blocks (subIRS) and controlling their dynamic assignment to operators, by taking into account the impact on the proximate operators as well. We show that the performance of the overall multi-operator network can be improved significantly if subIRS are properly assigned to the operators, compared to a purely static or random assignments. Our simulations results reveal that a significant improvement in terms of the sum rate and the fairness with respect to the respective data rate of the operators can be achieved.