Coexistence of Age and Throughput Optimizing Networks: Competition vs Cooperation

We investigate coexistence of an age optimizing network (AON) and a throughput optimizing network (TON) that access the same wireless spectrum band using a WiFi-like CSMA/CA based access. We consider two modes of long run coexistence: (a) networks compete with each other for spectrum access causing them to interfere and (b) networks cooperate and achieve non-interfering access. To model competition, we define a non-cooperative stage game parameterized by average age of the AON at the beginning of the stage, derive its mixed strategy Nash equilibrium (MSNE), and analyze the evolution of age and throughput over an infinitely repeated game in which each network plays the MSNE in every stage. Cooperation has a coordination device use a coin toss during each stage to select the network that must access the medium. Networks use the grim trigger punishment strategy, reverting to playing the MSNE every stage forever, if the other disobeys the device. We determine if there exists a subgame perfect equilibrium, that is the networks obey the device forever as they find cooperation beneficial. We find that networks choose to cooperate only when they have a small enough number of nodes. Else, they would rather disobey the device and compete.