In multi-rate IEEE 802.11 WLANs, the traditional user association based on the strongest received signal and the well known anomaly of the MAC protocol can lead to overloaded Access Points (APs), and poor or heterogeneous performance. Our goal is to propose an alternative game-theoretic approach for association. We model the joint resource allocation and user association as a matching game with complementarities and peer effects consisting of selfish players solely interested in their individual throughputs. Using recent game-theoretic results we first show that various resource sharing protocols actually fall in the scope of the set of stability-inducing resource allocation schemes. The game makes an extensive use of the Nash bargaining and some of its related properties that allow to control the incentives of the players. We show that the proposed mechanism can greatly improve the efficiency of 802.11 with heterogeneous nodes and reduce the negative impact of peer effects such as its MAC anomaly. The mechanism can be implemented as a virtual connectivity management layer to achieve efficient APs-user associations without modification of the MAC layer.

This article develops a simple model of the smartphone circular economy where the buy-back price offered to consumers is the main control variable. The model explicitly integrates refurbishment, recycling, and premature phone replacement encouraged by buy-back incentives. We distinguish three types of smartphones: premium, basic, and refurbished premium phones. Furthermore, consumers are segmented by buy-back sensitivity: sensitive users tend to return their phones and shorten their device lifespan, while non-sensitive users keep their phones longer. Additionally, refurbished consumers can buy new phones in case of insufficient supply. Our analysis reveals that with realistic parameters, there exists an optimal buy-back level that minimizes CO₂eq. emissions and waste, and this optimum coincides with the equilibrium between supply and demand on the refurbished market. However, depending on the system parameters, negative effects can be observed. For example, if most components are replaced during refurbishment, emissions increase with the buy-back. More generally, our results highlight the importance of eco-design. While the model is applied to smartphones, its structure is generic and can be adapted to other products with refurbishment and buy-back incentives.