New network architectures will be weakly coupled

Future wireless network control architectures will be based on weakly coupled agents in the form of hybrid self-organizing networks that combine centralized and distributed control. Weakly coupled systems have been studied scientifically in many disciplines since the 1960s. Vertically and horizontally weakly coupled agents form a stable, scalable, and efficient hierarchical system. In communications, a central agent acts as a network manager with the purpose to guarantee fairness and constrain the use of basic resources such as energy, time, and bandwidth. The lowest level agents are transmitters and receivers that work almost autonomously due to weak vertical coupling. The system is based on time-scale separation of hierarchy levels: high-level agents act much more slowly than low-level agents. Horizontal coupling through interference between users is minimized by using orthogonal signals. This is called interference avoidance. All feedback loops at different hierarchy levels and at the same hierarchy level must be decoupled. This combination of vertical and horizontal decoupling of feedback control loops forms our main contribution in this paper.