**7. Centralized monetization architecture**

According to [35, 41, 42], the centralized monetization architecture is shown in **Figure 2**. This architecture comprises the cloud, fog nodes, edge devices, and thirdparty payment gateway. The third-party payment gateway is an entity that helps the fog providers receive payment online for the services rendered to the end users. This is called a centralized monetization architecture because the fog provider has firm control and authority over the kind of services rendered and determines how the fog services will be monetized, irrespective of the QoS provided. The third-party payment gateway implements the pricing and monetization strategies between edge devices and fog nodes. This leads to a subscription-based pricing model [41]. This

**Figure 2.** *Central monetization architecture of fog nodes.*

fixed payment is only advantageous when the fog service providers deliver the quality of service promised. Still, there is mostly a variation in the quality of service (QoS) which is not reflected in the subscription-based pricing models. The QoS promised is not always the same in all instants when the customer accesses the fog service, resulting in mistrust between the fog node provider and customer. Also, service charges by third parties increase the cost of using the fog services by the consumers. Since it is centralized and embeds a fixed pricing model, hence once the promised quality of service is not met, it might lead to customers churn and vendors lock-in for situations where it is difficult for customers to migrate to another vendor due to sole dependence on a particular vendor [35].
